International Nuclear Information System (INIS)

It is shown that the usual proof of the second law of black hole physics breaks down if there are tachyons present in the vicinity of a black hole. Explicit cases are discussed where a tachyon of positive energy falling into the Kerr singularity actually decreases the area of the Kerr black hole. (author).

Science.gov (United States)

Black holes have been predicted since the 1940's from solutions of Einstein's general relativity

Energy Technology Data Exchange (ETDEWEB)

The inverse problem of interpreting the SS 433 optical light curves is solved for a geometrically thick model accretion disk around the compact relativistic object: most likely a black hole.

Science.gov (United States)

Black Hole Drawing Credit: A. Hobart, CXC Explanation: In the center of a swirling whirlpool of hot gas is likely a beast that has never been seen directly: a black hole....

Science.gov (United States)

Black Hole Drawing Credit: A. Hobart, CXC Explanation: In the center of a swirling whirlpool of hot gas is likely a beast that has never been seen directly: a black hole....

International Nuclear Information System (INIS)

It is shown that the interaction of a class of positive energy tachyons decreases the area of the horizon of the T-S, delta = 3 metric even in the case of a reversible transformation (Msub(ir) = constant). This is a violation of the second law of black hole physics. (author).

Science.gov (United States)

Black Hole Credit: April Hobart, CXC Explanation: In the center of a swirling whirlpool of hot gas is likely a beast that has never been seen directly: a black hole....

Energy Technology Data Exchange (ETDEWEB)

The Klein-Gordan equation in the background of the Schwarzschild curved space-time is considered and the scattering of radial tardyons and tachyons from a black hole is studied. It is shown that black holes of mass below 7x10/sup 14/g may contain bound states of tardyons of pion mass which will be unstable on account of the presence of an attractive r/sup -4/ term.

Science.gov (United States)

The suggestion has been made that stars with collapsing iron cores may be unable to explode, and hence may generate black holes. The situation when the collapsing core is rotating and magnetized is investigated and it is tentatively concluded that these effects make the situation even more conducive to the formation of black holes. (auth)

International Nuclear Information System (INIS)

The standard postulates of general relativity are modified by allowing changes of topologies in space-time, i.e. considering a multiply-connected manifold. This allows, for instance, a different description of black holes and, in particular, a more rigorous approach to previous work studying the connections between black holes and tachyons. (author).

CERN Document Server

We present results from a comprehensive number of relativistic, time-dependent, axisymmetric simulations of the runaway instability of non-constant angular momentum thick discs around black holes. This second paper extends earlier results where only constant angular momentum discs were considered. All relevant aspects of the theory of stationary thick discs around rotating black holes, necessary to build the initial state in our simulations, are presented in great detail. The angular momentum of the discs is assumed to increase outwards with the radial distance according to a power law. The main simplifying assumptions of our approach are not to include magnetic fields and self-gravity in the discs. Furthermore, the dynamics of the spacetime is accounted for by computing the transfer of mass and angular momentum from the disc to the black hole through the event ...

CERN Document Server

By employing the higher dimensional version of the Wu-Yang Ansatz we obtain magnetically charged new black hole solutions in the Einstein-Yang-Mills-Lovelock (EYML) theory with second ($\\alpha2$) and third ($\\alpha3$)order parameters. These parameters, where $\\alpha2$ is also known as the Gauss-Bonnet parameter, modify the horizons (and the resulting thermodynamical properties) of the black holes. It is shown also that asymptotically, these parameters contribute to an effective cosmological constant -without cosmological constant- so that the solution behaves de-Sitter (Anti de-Sitter) like.

CERN Document Server

No Kerr-like exact solution has yet been found in Chern-Simons modified gravity. Intrigued by this absence, we study stationary and axisymmetric metrics that could represent the exterior field of spinning black holes. For the standard choice of the background scalar, the modified field equations decouple into the Einstein equations and additional constraints. These constraints eliminate essentially all solutions except for Schwarzschild. For non-canonical choices of the background scalar, we find several exact solutions of the modified field equations, including mathematical black holes and pp-waves. We show that the ultrarelativistically boosted Kerr metric can satisfy the modified field equations, and we argue that physical spinning black holes may exist in Chern-Simons modified gravity only if the metric breaks stationarity, axisymmetry or energy-momentum ...

International Nuclear Information System (INIS)

We study the spin dependence of accretion onto rotating Kerr black holes using analytic techniques. In its linear regime, angular momentum transport in MHD turbulent accretion flow involves the generation of radial magnetic field connecting plasma in a differentially rotating flow. We take a first principles approach, highlighting the constraint that limits the generation and amplification of radial magnetic fields, stemming from the transfer of energy from mechanical to magnetic form. Because the energy transferred in magnetic form is ultimately constrained by gravitational potential energy or Killing energy, the spin dependence of the latter allows us to derive spin-dependent constraints on the success of the accreting plasma to expel its angular momentum. We find an inverse relationship between this ability and black hole spin. If this radial magnetic field generation forms the basis for angular ...

International Nuclear Information System (INIS)

Stellar rotation velocities and velocity dispersions along three slit positions in M31 have been measured, and three-dimensional velocity and velocity dispersion fields are obtained in order to search for a central black hole. Synthetic apparent spectra are constructed to eliminate problems with the reaction of the Fourier quotient program to stellar population mixes. Models are constructed to explore parameter space. The large velocities and velocity gradients that are found imply that the total mass-to-light ratio rises sharply at r of 0.5 arcsec or less to values greater than 100. This is much larger than normal for old stellar populations. Velocity anisotropies are not a major uncertainty because of the rapid rotation. There is thus strong evidence for a dark central mass, probably a supermassive black hole. 48 references.

CERN Document Server

Assuming the hoop conjecture in classical general relativity and quantum mechanics, any observer who attempts to perform an experiment in an arbitrarily small region will be stymied by the formation of a black hole within the spatial domain of the experiment. This behavior is often invoked in arguments for a fundamental minimum length. Extending a proof of the hoop conjecture for spherical symmetry to include higher curvature terms we investigate this minimum length argument when the gravitational couplings run with energy in the manner predicted by asymptotically safe gravity. We show that argument for the mandatory formation of a black hole within the domain of an experiment fails. Neither is there a proof that a black hole doesn't form. Instead, whether or not an observer can perform measurements in arbitrarily small regions depends on the specific numerical ...

CERN Document Server

We present the results of three-dimensional hydrodynamical simulations of the final stages of inspiral in a black hole-neutron star binary, when the separation is comparable to the stellar radius. We use a Newtonian Smooth Particle Hydrodynamics (SPH) code to model the evolution of the system, and take the neutron star to be a polytrope with a soft (adiabatic index G=2 and G=5/3) equation of state and the black hole to be a Newtonian point mass. The only non-Newtonian effect we include is a gravitational radiation back reaction force, computed in the quadrupole approximation for point masses. We use irrotational binaries as initial conditions for our dynamical simulations, which are begun when the system is on the verge of initiating mass transfer and followed for approximately 23 ms. For all the cases studied we find that the star is disrupted on a dynamical time-scale, and forms a massive (the disc ...

CERN Document Server

We calculate the structure of accretion disks around Kerr black holes for accretion rates 0.001 - 10 M_sun/s. Such disks are plausible candidates for the central engine of gamma-ray bursts. Our disk model is fully relativistic and treats accurately microphysics of the accreting matter: neutrino emissivity, opacity, electron degeneracy, and nuclear composition. The neutrino-cooled disk forms above a critical accretion rate that depends on the black hole spin. The disk has the ``ignition'' radius r_ign where neutrino flux rises dramatically, cooling becomes efficient, and the proton-to-nucleon ratio Y_e drops. Other characteristic radii are r_alpha where most of alpha-particles are disintegrated, r_nu where the disk becomes neutrino-opaque, and r_trap where neutrinos get trapped and advected into the black hole. We find r_alpha, r_ign, r_nu, r_trap and show their ...

CERN Document Server

We consider the simplest scenario when black strings (cigars) penetrate the cosmological brane. As a result, the brane has a Swiss-cheese structure, with Schwarzschild black holes immersed in a Friedmann-Lema\\^{\\i}tre-Robertson-Walker brane. There is no dark radiation in the model, the cosmological regions of the brane are characterized by a cosmological constant $\\Lambda$ and flat spatial sections. Regardless of the value of $\\Lambda$, these brane-world universes forever expand and forever decelerate. The totality of source terms in the modified Einstein equation sum up to a dust, establishing a formal equivalence with the general relativistic Einstein-Straus model. However in this brane-world scenario with black strings the evolution of the cosmological fluid strongly depends on $\\Lambda$. For $\\Lambda$ less or equal to zero it has positive energy density $\\rho$ and negative pressure $p$ and at ...

CERN Document Server

We report on the results of a simultaneous monitoring campaign employing eight Chandra X-ray (0.5-10 keV) and six VLA/EVLA (8.4 GHz) radio observations of NGC 4051 over seven months. Evidence for compact jets is observed in the 8.4 GHz radio band; This builds on mounting evidence that jet production may be prevalent even in radio-quiet Seyferts. Assuming comparatively negligible local diffuse emission in the nucleus, the results also demonstrate an inverse correlation of L_radio proportional to L_X-ray ^(-0.72+/-0.04) . Current research linking the mass of supermassive black holes and stellar-mass black holes in the "low/hard" state to X-ray luminosities and radio luminosities suggest a "fundamental plane of accretion onto black holes" that has a positive correlation of L_radio proportional to L_X-ray^(0.67+/-0.12) . Our simultaneous results differ from this ...

CERN Document Server

We investigate the existence of time-periodic solutions of the Dirac equation in the Kerr-Newman background metric. To this end, the solutions are expanded in a Fourier series with respect to the time variable $t$ and the Chandrasekhar separation ansatz is applied so that the question of existence of a time-periodic solution is reduced to the solvability of a certain coupled system of ordinary differential equations. First, we prove the already known result that there are no time-periodic solutions in the non-extreme case. Then it is shown that in the extreme case for fixed black hole data there is a sequence of particle masses $(m_N)_{N\\in\\mathbb N}$ for which a time-periodic solution of the Dirac equation does exist. The period of the solution depends only on the data of the black hole described by the Kerr-Newman metric.

CERN Document Server

We study the phonon fluxes emitted when the condensate velocity crosses the speed of sound, i.e., in backgrounds which are analogue to that of a black hole. We focus on elongated one dimensional condensates, and on stationary flows. Our theoretical analysis and numerical results are based on the Bogoliubov-de-Gennes equation without any further approximation. The spectral properties of the fluxes and of the long distance density-density correlations are obtained, with and without an initial temperature. In realistic conditions, we show that the condensate temperature dominates the fluxes, and thus hides the presence of the spontaneous emission (the Hawking effect). We also explain why the temperature amplifies the long distance correlations which are intrinsic to this effect. This confirms that the correlations pattern offers a neat signature of the Hawking effect. Optimal conditions to observe the pattern are discussed.

CERN Document Server

Large optical surveys provide an unprecedented census of galaxies in the local Universe, forming an invaluable framework into which more detailed studies of objects can be placed. But how useful are optical surveys for understanding the co-evolution of black holes and galaxies, given their limited wavelength coverage, selection criteria, and depth? In this conference paper I present work-in-progress comparing optical and mid-IR diagnostics of three "unusual" low redshift populations (luminous Seyferts, dusty Balmer-strong AGN, ULIRGs) with a set of ordinary star-forming galaxies from the SDSS. I address the questions: How well do the mid-infrared and optical diagnostics of star formation and AGN strength agree? To what extent do optical surveys allow us to include extreme, dusty, morphologically disturbed galaxies in our "complete" census of black hole-galaxy co-evolution?

CERN Document Server

A consistent combination of quantum geometry effects rules out a large class of models of loop quantum cosmology and their critical densities as they have been used in the recent literature. In particular, the critical density at which an isotropic universe filled with a free, massless scalar field would bounce must be well below the Planck density. In the presence of anisotropy, no model of the Schwarzschild black hole interior analyzed so far is consistent.

Energy Technology Data Exchange (ETDEWEB)

Research highlights: {yields} The use of resonant photoemission in its 'core-hole clock' expression for the study of the dynamical charge transfer across hybrid organic-inorganic interfaces and for the intermolecular charge transfer in the bulk of organic thin films is reviewed. {yields} The electronic coupling to the substrate and the efficiency of charge transport across hybrid interfaces is different for individual electronic subsystems of the molecular adsorbate. {yields} The intermolecular charge transfer in the bulk of discotic liquid crystals occurs on the order of a few femtoseconds and is faster than expected from the macroscopic charge transport characteristics of the material. -- Abstract: The focus of this brief review is the use of resonant photoemission in its 'core-hole clock' expression for the study of two important problems relevant for the field of organic electronics: ...

CERN Document Server

We study the Sunyaev-Zel'dovich (SZ) effect potentially generated by relativistic electrons injected from dark matter (DM) annihilation or decay in the Galaxy, and check whether it could be observed by Planck or ALMA, or even imprint the current CMB data as e.g. the specific fluctuation excess claimed from an recent re-analysis of the WMAP-5 data. We focus on high-latitude regions to avoid contamination of the Galactic astrophysical electron foreground, and consider the annihilation or decay coming from the smooth DM halo as well as from subhalos, further extending our analysis to a generic modeling of spikes arising around intermediate-mass-black-holes (IMBHs). We show that all these dark Galactic components are unlikely to produce any observable SZ effect. For a self-annihilating DM particle of 10 GeV with canonical properties, the largest optical depth we find is $\\tau_e \\lesssim 10^{-7}$ for massive isolated subhalos hosting IMBHs. We conclude that dark ...

CERN Document Server

We review results from general relativistic axisymmetric magnetohydrodynamic simulations of accretion in Sgr A*. We use general relativistic radiative transfer methods and to produce a broad band (from millimeter to gamma-rays) spectrum. Using a ray tracing scheme we also model images of Sgr A* and compare the size of image to the VLBI observations at 230 GHz. We perform a parameter survey and study radiative properties of the flow models for various black hole spins, ion to electron temperature ratios, and inclinations. We scale our models to reconstruct the flux and the spectral slope around 230 GHz. The combination of Monte Carlo spectral energy distribution calculations and 230 GHz image modeling constrains the parameter space of the numerical models. Our models suggest rather high black hole spin ($a_*\\approx 0.9$), electron temperatures close to the ion temperature ($T_i/T_e \\sim 3$) and high ...

CERN Document Server

The massive stars in the Galactic center inner arcsecond share analogous properties with the so-called Hot Jupiters. Most of these young stars have highly eccentric orbits, and were probably not formed in-situ. It has been proposed that these stars acquired their current orbits from the tidal disruption of compact massive binaries scattered toward the proximity of the central supermassive black hole. Assuming a binary star formed in a thin gaseous disk beyond 0.1 pc from the central object, we investigate the relevance of disk-satellite interactions to harden the binding energy of the binary, and to drive its inward migration. A massive, equal-mass binary star is found to become more tightly wound as it migrates inwards toward the central black hole. The migration timescale is very similar to that of a single-star satellite of the same mass. The binary's hardening is caused by the formation of spiral ...

CERN Document Server

Accretion processes in quasars and active galactic nuclei are still poorly understood, especially as far as the connection between observed spectral properties and physical parameters is concerned. Quasars show an additional degree of complexity compared to stars that is related to anisotropic emission/obscuration influencing the observed properties in most spectral ranges. This complicating factor has hampered efforts to define the equivalent of an Hertzsprung-Russel diagram for quasars. Even if it has recently become possible to estimate black hole mass and Eddington ratio for sources using optical and UV broad emission lines, the results are still plagued by large uncertainties. Nevertheless, robust trends are emerging from multivariate analysis of large spectral datasets of quasars. A firm observational basis is being laid out by accurate measurements of broad emission line properties especially when the source rest-frame is known. We ...

CERN Document Server

We consider a holographic description of a system of strongly-coupled fermions in 2+1 dimensions based on a D7-brane probe in the background of D3-branes. The black hole embedding represents a Fermi-like liquid. We study the excitations of the Fermi liquid system. Above a critical density which depends on the temperature, the system becomes unstable towards an inhomogeneous modulated phase which is similar to a charge density and spin wave state. The essence of this instability can be effectively described by a Maxwell-axion theory with a background electric field. We also consider the fate of zero sound at non-zero temperature.

CERN Document Server

It has been proposed that a hidden conformal field theory (CFT) governs the dynamics of low frequency scattering in a general Kerr black hole background. We further investigate this correspondence by mapping higher order corrections to the massless wave equations in a Kerr background to an expansion within the CFT in terms of higher dimension operators. This implies the presence of infinite towers of CFT primary operators with positive conformal dimensions compatible with unitarity. The exact Kerr background softly breaks the conformal symmetry and the scaling dimensions of these operators run with frequency. The scale-invariant fixed point is dual to a degenerate case of flat spacetime.

Science.gov (United States)

A general relativistic model for the formation and acceleration of lowmass-loaded jets from systems containing accreting black holes is presented. The model is based on previous numerical results and theoretical studies in the Newtonian regime, but modified to include the effects of space-time curvature in the vicinity of the event horizon of a spinning black hole. It is argued that the boundary layer between the Keplerian accretion disk and the event horizon is best suited for the formation and acceleration of the accretion-powered jets in active galactic nuclei and micro-quasars. The model presented here is based on matching the solutions of three different regions: i- a weakly magnetized Keplerian accretion disk in the outer part, where the transport of angular momentum is mediated through the magentorotational instability, ii- a strongly magnetized, advection-dominated and turbulent-free boundary ...

CERN Document Server

Exact solutions are found for the Chandrasekhar Page angular equation which results when the Dirac equation in a Kerr Newman space time is separated into its radial and angular parts. The solutions turn out to be remarkably simple in form while satisfying the asymptotic conditions deduced earlier. The eigenvalues are found to be the square root of the total angular momentum as first found by Dirac for flat space; supplemented by a term which is the product of the mass of the Dirac particle times the specific angular momentum of the black hole. The additional contribution is what is expected from frame dragging.

International Nuclear Information System (INIS)

We derive improved versions of the relations between supermassive black hole mass (M _B_H) and host-galaxy bulge velocity dispersion (#sigma#) and luminosity (L; the M-#sigma# and M-L relations), based on 49 M _B_H measurements and 19 upper limits. Particular attention is paid to recovery of the intrinsic scatter (#epsilon#_0) in both relations. We find log(M _B_H/M _s_u_n) = #alpha# + #beta#log(#sigma#/200 km s"-"1) with (#alpha#, #beta#, #epsilon#_0) = (8.12 #+-# 0.08, 4.24 #+-# 0.41, 0.44 #+-# 0.06) for all galaxies and (#alpha#, #beta#, #epsilon#_0) = (8.23 #+-# 0.08, 3.96 #+-# 0.42, 0.31 #+-# 0.06) for ellipticals. The results for ellipticals are consistent with previous studies, but the intrinsic scatter recovered for spirals is significantly larger. The scatter inferred reinforces the need for its consideration when calculating local black hole mass function based on the M-#sigma# relation, and ...

International Nuclear Information System (INIS)

In a series of recent papers, Corben recovered various properties of many hadronic resonances by considering them as compounds of a bradyon and of one (or more) tachyons. In this note it is explained why that success follows from considering the tachyon four-momenta orthogonal to the bradyon one, and why, in such a case, the bradyon and tachyons can be formally dealt with as non-interacting even when they keep participating in the ''self-trapping''. Finally an attempt is made to understand (on the basis of the model by Caldirola, Pavsic and Recami where hadrons are considered as ''strong black-holes'') why in general those compound hadrons decay and why in this decay the trapped tachyons are, quantum-mechanically, emitted in the corresponding bradyonic form.

Energy Technology Data Exchange (ETDEWEB)

Many solutions of General Relativity appear to allow the possibility of time travel. This was initially a fascinating discovery, but geometries of this type violate causality, a basic physical law which is believed to be fundamental. Although string theory is a proposed fundamental theory of quantum gravity, geometries with closed timelike curves have resurfaced as solutions to its low energy equations of motion. In this paper, we will study the class of solutions to low energy effective supergravity theories related to the BMPV black hole and the rotating wave-D1-D5-brane system. Time travel appears to be possible in these geometries. We will attempt to build the causality violating regions and propose that stringy effects prohibit their construction. The proposed chronology protection agent for these geometries mirrors a mechanism string theory employs to resolve a class of naked singularities. (author)

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CERN Document Server

We study the high-energy emission of the Galactic black hole candidate GX 339-4 using INTEGRAL/SPI and simultaneous RXTE/PCA data. By the end of January 2007, when it reached its peak luminosity in hard X-rays, the source was in a bright hard state. The SPI data from this period show a good signal to noise ratio, allowing a detailed study of the spectral energy distribution up to several hundred keV. As a main result, we report on the detection of a variable hard spectral feature (>150 keV) which represents a significant excess with respect to the cutoff power law shape of the spectrum. The SPI data suggest that the intensity of this feature is positively correlated with the 25 - 50 keV luminosity of the source and the associated variability time scale is shorter than 7 hours. The simultaneous PCA data, however, show no significant change in the spectral shape, indicating that the source is not undergoing a canonical state transition. We ...

CERN Document Server

Testing deviation of GR is one of the main goals of the proposed {\\emph{Laser Interferometer Space Antenna}}, a space-based gravitational-wave observatory. For the first time, we consistently compute the generation of gravitational waves from extreme-mass ratio inspirals (stellar compact objects into supermassive black holes) in a well-motivated alternative theory of gravity, that to date remains weakly constrained by double binary pulsar observations. The theory we concentrate on is Chern-Simons (CS) modified gravity, a 4-D, effective theory that is motivated both from string theory and loop-quantum gravity, and which enhances the Einstein-Hilbert action through the addition of a dynamical scalar field and the parity-violating Pontryagin density. We show that although point particles continue to follow geodesics in the modified theory, the background about which they inspiral is a modification to the Kerr metric, which imprints a CS ...

CERN Document Server

We use direct N-body simulations to investigate the evolution of star clusters with large size-scales with the particular goal of understanding the so-called extended clusters observed in various Local Group galaxies, including M31 and NGC6822. The N-body models incorporate a stellar mass function, stellar evolution and the tidal field of a host galaxy. We find that extended clusters can arise naturally within a weak tidal field provided that the tidal radius is filled at the start of the evolution. Differences in the initial tidal filling-factor can produce marked differences in the subsequent evolution of clusters and the size-scales that would be observed. These differences are more marked than any produced by internal evolution processes linked to the properties of cluster binary stars or the action of an intermediate-mass black hole, based on models performed in this work and previous work to date. Models evolved in a stronger tidal field ...

CERN Document Server

We derive spin-orbit coupling effects on the gravitational field and equations of motion of compact binaries in the 2.5 post-Newtonian approximation to general relativity, one PN order beyond where spin effects first appear. Our method is based on that of Blanchet, Faye, and Ponsot, who use a post-Newtonian metric valid for general (continuous) fluids and represent pointlike compact objects with a delta-function stress-energy tensor, regularizing divergent terms by taking the Hadamard finite part. To obtain post-Newtonian spin effects, we use a different delta-function stress-energy tensor introduced by Bailey and Israel. In a future paper we will use the 2.5PN equations of motion for spinning bodies to derive the gravitational-wave luminosity and phase evolution of binary inspirals, which will be useful in constructing matched filters for signal analysis. The gravitational field derived here may help in posing initial data for numerical evolutions of binary black ...

International Nuclear Information System (INIS)

Core-collapse supernovae are among Nature's most energetic events. They mark the end of massive star evolution and pollute the interstellar medium with the life-enabling ashes of thermonuclear burning. Despite their importance for the evolution of galaxies and life in the universe, the details of the core-collapse supernova explosion mechanism remain in the dark and pose a daunting computational challenge. We outline the multi-dimensional, multi-scale, and multi-physics nature of the core-collapse supernova problem and discuss computational strategies and requirements for its solution. Specifically, we highlight the axisymmetric (2D) radiation-MHD code VULCAN/2D and present results obtained from the first full-2D angle-dependent neutrino radiation-hydrodynamics simulations of the post-core-bounce supernova evolution. We then go on to discuss the new code Zelmani which is based on the open-source HPC Cactus framework and provides a scalable AMR approach for 3D fully general-relativistic ...

CERN Document Server

Dynamical friction, or the rate for a satellite to decay its orbit in a host galaxy halo, is often severely overestimated when applying the ChandraSekhar's formula without correcting for the tidal loss of the satellite and the adiabactic growth of the host galaxy potential over the Hubble time. As a satellite decays to the inner and denser region of the host galaxy, the high ambient density boosts the exchange of energy and angular momentum between the satellite and the host, but on the other hand shrinks the Roche lobe of the satellite by tides. Eventually the processes of orbital decay and tidal stripping hang up altogether once the satellite is light enough. These competing processes can be modeled analytically for a satellite if we parametrize the massloss history by an empirical formula. We also take into account the adiabatic contraction of orbits due to growth of the potential well of the host galaxy. Observed dwarf galaxies often show a finite density core, which determines how ...

CERN Document Server

Polarization measurements in the X-ray and gamma-ray energy range can provide crucial information on massive compact objects such as black holes and neutron stars. The Polarized Gamma-ray Observer (PoGO) is a new balloon-borne instrument designed to measure polarization from astrophysical objects in the 30-100 keV range, under development by an international collaboration with members from United States, Japan, Sweden and France. To examine PoGO's capability, a beam test of a simplified prototype detector array was conducted at the Argonne National Laboratory Advanced Photon Source. The detector array consisted of seven plastic scintillators, and was irradiated by polarized photon beams at 60, 73, and 83 keV. The data showed a clear polarization signal, with a measured modulation factor of $0.42 \\pm 0.01$. This was successfully reproduced at the 10% level by the computer simulation package Geant4 after modifications to its implementation of ...

CERN Document Server

While feedback is important in theoretical models, we do not really know if it works in reality. Feedback from jets appears to be sufficient to keep the cooling flows in clusters from cooling too much and it may be sufficient to regulate black hole growth in dominant cluster galaxies. Only about 10% of all quasars, however, have powerful radio jets, so jet-related feedback cannot be generic. The outflows could potentially be a more common form of AGN feedback, but measuring mass and energy outflow rates is a challenging task, the main unknown being the location and geometry of the absorbing medium. Using a novel technique, we made first such measurement in NGC 4051 using XMM data and found the mass and energy outflow rates to be 4 to 5 orders of magnitude below those required for efficient feedback. To test whether the outflow velocity in NGC 4051 is unusually low, we compared the ratio of outflow velocity to escape velocity in a sample of AGNs ...

Energy Technology Data Exchange (ETDEWEB)

{sup 188}Re is a {beta}{sup -} (Emax=2.12 MeV) and {gamma} (155 keV) emitter. Since its chemistry is similar to that of the largely employed tracer, {sup 99m}Tc, molecules of hyaluronic acid (HA) have been labelled with {sup 188}Re to produce a target specific radiopharmaceutical. The radiolabeled compound, i.v. injected in healthy mice, is able to accumulate into the liver after a few minutes. To study the effect of metabolic radiotherapy in mice, we have built a small gamma camera based on a matrix of YAP:Ce crystals, with 0.6x0.6x10 mm{sup 3} pixels, read out by a R2486 Hamamatsu PSPMT. A high-sensitivity 20 mm thick lead parallel-hole collimator, with hole diameter 1.5 mm and septa of 0.18 mm, is placed in front of the YAP matrix. Preliminary results obtained with various phantoms containing a solution of {sup 188}Re and with C57 black mice injected with the {sup 188}Re-HA solution are presented. To increase the space ...

UK PubMed Central (United Kingdom)

Purpose. To describe the characteristics of idiopathic macular holes (MH) on optical coherence tomography (OCT) and correlate OCT with clinical assessment. Design....Full Text Available

Science.gov (United States)

... Accession Number : ADD813911. Title : Examining Deep-Hole Waterjet Boring. Descriptive Note : Journal article,. Corporate Author : ...

Science.gov (United States)

... was noted. It was reported that similar fibers also grew on particles of thermal carbon black at a temperature of 10500 and in an atmosphere ...

Energy Technology Data Exchange (ETDEWEB)

The macroscopic behavior of magnetostrictive materials results from domain evolutions occurring at a microscopic scale. The author shows how to compute magnetization and magnetostriction curves by appraising the behavior of the underlying microstructures. The method hinges on an averaging device (Young measures), which allows one to pass from the microscopic to the macroscopic scale. He takes into account the kinematical constraints on the accommodation of elastic effects, and he highlights the role of material symmetry in the selection of energetically optimal microstructures.

Energy Technology Data Exchange (ETDEWEB)

Three holes the size of deposition holes (depth 7.5 m and diameter 1.5 m) were bored in the Research Tunnel at Olkiluoto, Finland. A novel full-face boring technique was used based on rotary crushing of rock and removal of crushed rock by vacuum flushing through the drill string. The purpose of the work was to demonstrate the feasibility of the technique. During the boring test procedures were carried out in order to determine the effect of changes in operating parameters on the performance of the boring machine and the quality of the hole. The boring method was found to be technically feasible and efficient. Evaluation of the quality of the hole included studies of the geometry of the hole, measurements of the surface roughness using a laser profilometer and study of excavation disturbances in the zone adjacent to the surface of the holes using two novel ...

Energy Technology Data Exchange (ETDEWEB)

When nanometer scale holes (diameters of 50 to a few hundred nm) are imaged in a scanning electron microscope (SEM) at pressures in the 10{sup -5} to 10{sup -6} torr range, hydrocarbon deposits built up and result in the closing of holes within minutes of imaging. Additionally, electron beam deposition of material from a gas source allows the closing of holes with films of platinum or TEOS oxide. In an instrument equipped both with a focused ion beam (FIB), and an SEM, holes can be formed and then covered with a thin film to form nanopores with controlled openings, ranging down to only a few nanometers.

Energy Technology Data Exchange (ETDEWEB)

Significantly improved immunity to hot-hole damage of the SiO[sub 2]/Si structure is achieved by a shallow fluorine implantation into the poly-Si gate of MOS capacitors followed by a drive-in process. Compared to the nonfluorinated control, the fluorinated samples exhibit a dramatic reduction of both hole trapping probability and interface-trap generation under avalanche hole injection conditions. The degree of such an improvement increases monotonically as a function of the F implantation dose (up to 10[sup 16]/cm[sup 2]). Significant decrease of the hole detrapping rate is also observed in fluorinated samples. Possible mechanisms are discussed.

Energy Technology Data Exchange (ETDEWEB)

In general, macroscopic material failure is a manifestation of irreversible changes at the microscopic level. Many tissues, which may appear to be macroscopically homogeneous, are, at a fundamental microscopic level, a composite material. For example, cornea is composed of a hyaluronic acid matrix in which layers of collagen fibers are overlaid in a crossing pattern. The points where the collagen fibers intersect are potential nucleation sites for microscopic defects, which under the action of tensile stress, nucleate, grow and coalesce to form macroscopic failure planes, or spall planes. Using a model based on microstructural evolution, this paper examines the failure process during photoablation. Specifically, the paper describes a physically motivated, micromechanical model based on the nucleation and growth of spherical voids. This model is then used to simulate photoablation of cornea. Potential for using this model to ...

Science.gov (United States)

... 1670/07-076.1 Spitting versus Biting: Differential Venom Gland Contraction Regulates Venom Expenditure in the Black-Necked Spitt...

UK PubMed Central (United Kingdom)

Background and objectives: Blacks are over-represented among dialysis patients, but they have better survival rates than whites. It is unclear if the over-representation of blacks on dialysis is due...Full Text Available

British Library Electronic Table of Contents (United Kingdom)

In-situ sodium activated organo modified bentonite clay was also used for partial replacement of the carbon black (N330). Detailed study with the black filled compound revealed that, with slight modification of the curing package, up to 10 phr of the carbon black replacement is possible. At equivalent loading of 5 and 10 phr of in-situ sodium activated organo modified bentonite clay exhibited better properties in comparison to carbon black filled compound.

CERN Document Server

We study the risk premium impact in the Perturbative Black Scholes model. The Perturbative Black Scholes model, developed by Scotti, is a subjective volatility model based on the classical Black Scholes one, where the volatility used by the trader is an estimation of the market one and contains measurement errors. In this article we analyze the correction to the pricing formulas due to the presence of an underlying drift different from the risk free return. We prove that, under some hypothesis on the parameters, if the asset price is a sub-martingale under historical probability, then the implied volatility presents a skewed structure, and the position of the minimum depends on the risk premium $\\lambda$.

UK PubMed Central (United Kingdom)

Secreted human bronchial mucins, directly collected from macroscopically healthy bronchial mucosa, were prepared in the presence of six proteinase inhibitors, and analysed by electron microscopy. These...Full Text Available

Science.gov (United States)

The thermodynamic characteristics of adsorption of sulfur-containing amino acids and their derivatives on the surface of graphitized thermal carbon black were calculated by the molecular statistical method. The parameters of the atom-atom potential function of intermolecular interaction between the S atom in amino acids and the graphite C atom were determined. It was shown that an intramolecular H-bond influenced the adsorption of amino acids on the surface of graphitized thermal carbon black.

Energy Technology Data Exchange (ETDEWEB)

The macroscopic stress distribution across an annealed Zircaloy-4 gas tungsten arc weld was measured by neutron time-of-flight diffraction at the SMARTS diffractometer at Los Alamos National Laboratory. The stresses after annealing are about 40% lower than those in the same weld prior to heat treatment. The intergranular strains in the reference coupons, which give the macroscopic stress free lattice spacings, are consistent with the difference in cooling the strongly textured plate and the weakly textured weld.

International Nuclear Information System (INIS)

We investigate how 'extra' or 'excess' central light in the surface brightness profiles of cusp or power-law elliptical galaxies relates to the profiles of ellipticals with cores. The envelopes of cusp ellipticals are established by violent relaxation in mergers acting on stars present in gas-rich progenitor disks, while their centers are structured by the relics of dissipational, compact starbursts. Ellipticals with cores are formed by the subsequent merging of the now gas-poor cusp ellipticals, with the fossil starburst components combining to preserve a dense, compact component in these galaxies as well (although mixing of stars smooths the transition from the outer to inner components in the profiles). By comparing extensive hydrodynamical simulations to observed profiles spanning a broad mass range, we show how to observationally isolate and characterize the relic starburst component in core ellipticals. Our method recovers the younger starburst population, demonstrating that ...

British Library Electronic Table of Contents (United Kingdom)

One of vector-borne avian protozoa, Leucocytozoon lovati, has been found in the Japanese rock ptarmigans (Lagopus mutus japonicus), the endangered bird species distributed in the alpine regions in Japan. Vector arthropod species of L. lovati has also been estimated as Simuliidae black flies distributed in the same habitat of the host bird, however, possible blood meals of the black flies were not identified yet. To reveal host animals of black flies, we estimated the blood resources by using molecular techniques. Black flies were collected at Mt. Chogatake, one of the alpine regions of Japan in which Japanese rock ptarmigans live in June 2005. The analyzed 144 specimens were morphologically identified into five species including Simulium japonicum (n?=?87), Prosimulium hirtipes (n?=?48), P...

Energy Technology Data Exchange (ETDEWEB)

As a part of the Finnish radioactive waste disposal research three holes (the size of deposition holes) were bored in the research tunnel at Olkiluoto in Finland. A novel full-face boring technique was used based on rotary crushing of rock and removal of crushed rock by vacuum flushing through the drill string an the purpose of the work was to demonstrate the feasibility of the technique. During the boring test procedures were carried out in order to determine the effect of charges in operating parameters on the performance of the boring machine and the quality of the hole. (refs.).

Energy Technology Data Exchange (ETDEWEB)

A relocatable storage magazine apparatus for storing and retrieving explosives and ordnance and for partially containing and attenuating the blast, conflagration and flying debris from an accidental explosion is described comprising: (a) a container having an access hole; (b) a debris trap attached to the container, the debris trap communicating with said container via the access hole, said debris trap having vent holes for venting the pressure of an explosion from said debris trap to the atmosphere; (c) means for covering said access hole; (d) means for suspending explosives and ordnance from the covering means; (e) means for entering the storage magazine to store and retrieve explosives and ordnance; (f) means for retaining said covering means in a position above the access hole wherein said explosives and ordnance are accessible from the entering means.

CERN Document Server

The effects of strong Coulomb correlations in dense three-dimensional electron-hole plasmas are studied by means of unbiased direct path integral Monte Carlo simulations. The formation and dissociation of bound states, such as excitons and bi-excitons is analyzed and the density-temperature region of their appearance is identified. At high density, the Mott transition to the fully ionized metallic state (electron-hole liquid) is detected. Particular attention is paid to the influence of the hole to electron mass ratio $M$ on the properties of the plasma. Above a critical value of about M=80 formation of a hole Coulomb crystal was recently verified [Phys. Rev. Lett. {\\bf 95}, 235006 (2005)] which is supported by additional results. Results are related to the excitonic phase diagram of intermediate valent Tm[Se,Te], where large values of $M$ have been observed experimentally.

Science.gov (United States)

... The addition of 0.5 pphr of fine thermal carbon black to the polymers gave good resistance to 500 hours of ultraviolet (UV) xposure in a Weather ...

British Library Electronic Table of Contents (United Kingdom)

In vibration control field, magneto-rheological (MR) fluid dampers are semi-active control devices that have recently begun to receive more attention. This paper presents a nonlinear black-box model (BBM) and an inverse black-box model (IBBM) for the identification of a MR fluid damper and their application to design a novel force-sensorless control method for any damping system using that damper. The nonlinear model named 'black-box' is a simple direct modeling method which was designed based on fuzzy-neural technique. Characteristics of the damper in study are directly estimated through a fuzzy mapping system. In order to improve the model accuracy, neural network technique including back-propagation and gradient descent method were used to train the fuzzy parameters to minimize the mode...

Science.gov (United States)

... technique aBF n-Butyiferrocene P-33 Thermal carbon black PAP Porous Amnmonium Perchlorate Plastinox 711 Antioxidant ...

Science.gov (United States)

Graphitized thermal carbon black has also been reported by Kalaschinikova et al. (11) to have excellent adsorption properties for CI-C6 alkanes, ...

International Nuclear Information System (INIS)

Favorable reaction channels are searched for in order to obtain the superheavy element "2"9"8114. The interaction energy is supposed to comply with the adiabatic hypothesis. Concerning the deformation energy, a very complete binary macroscopic-microscopic energy method is used to perform calculations. Deformed two-center shell model provides the energy level schemes for shell effects. Yukawa-plus-exponential model gives the macroscopic (liquid drop) part of the total energy. The mass tensor is obtained by the Werner-Wheeler irrotational flow hypothesis. Finally the minimization of the multidimensional action integral produces the highest penetrability values. Kr-projectile reactions provide the best pairs, although generally the presentabilities are very low. (author)

CERN Document Server

The emergence of nanoscience has increased the importance of experiments able to probe the very local structure of materials, especially for disordered and heterogeneous systems. This is technologically important; for example, the nanoscale structure of glassy polymers has a direct correlation with their macroscopic physical properties. We have discovered how a local, high frequency dynamic process can be used to monitor and even predict macroscopic behavior in glassy polymers. Polyvinylethylenes vitrified by different chemical and thermodynamic pathways exhibit different densities in the glassy state. We find that the rate and amplitude of a high frequency relaxation mode (the Johari-Goldstein process involving local motion of segments of the chain backbone) can either correlate or anti-correlate with the density. This implies that neither the unoccupied (free) volume nor the configurational entropy governs the local dynamics in any general ...

International Nuclear Information System (INIS)

Nonparabolicity of the heavy hole band in diamond-like semiconductors, which occurs within the framework of the three band model with the perturbation from the other bands taken into account according to the Loewdin procedure, is studied. A direct dependence of nonparabolicity on the band anisotropy (caused by the different effect of Gamma/sub 15c/ and Gamma/sub 12c/ bands) and the inverse dependence on the magnitude of the spin-orbit splittiing is established. A connection between the effective mass of heavy holes and their energy is obtained, which is valid for the majority of diamond-like semiconductors, except for materials with a very strong nonparabolicity of the band of silicon type.

Science.gov (United States)

For coupled quantum wires and dots, tunneling effects and coherent transport for quantum computing are being studied. In 2D systems, electron-hole bilayers for exciton...

Science.gov (United States)

... of Dist SpeA tI/ __LLL5' Page 5. 3 the coherent effects on the spontaneous radiation, we calculate the pump- field-induced ...

Science.gov (United States)

The thermodynamic characteristics of adsorption on the surface of graphitized thermal carbon black at 300 K were determined by the molecular statistical method for three phenylalklylamines. The influence of the intramolecular H-bond on the conformation of the molecules compared with structurally related n-alkyl-benzenes was considered. It was shown that the conformations of the molecules could influence chromatographic retention. Conformational isomers stabilized by intramolecular H-bonds were found to retain their structure in adsorption on graphitized thermal carbon black.

Energy Technology Data Exchange (ETDEWEB)

Using the example of perhydrophenanthrene, perhydroanthracene and cyclopentanodecalin isomers a possibility is shown to use packed capillary columns containing graphitized thermal carbon black for a complete separation of high-boiling mixtures of polycyclic saturated hydrocarbon isomers in accordance with the geometric structure of their molecules.

Science.gov (United States)

The thermodynamic characteristics of adsorption of proline and its hydroxy derivatives on the surface of graphitized thermal carbon black (GTCB) were calculated. The arrangement of hydroxyl groups in the amino acid molecule was shown to influence their adsorption on GTCB. The influence of internal rotation angles in proline and its hydroxy derivative molecules on their adsorption on GTCB was studied.

British Library Electronic Table of Contents (United Kingdom)

Henry constants for the adsorption of o- and p-phenylenediamines on the surface of graphitized thermal carbon black within the temperature range 433?479 K were calculated by the molecular statistical method. The parameters of the atom-atom potential function of intermolecular interaction between the nitrogen atom in aniline and isomeric phenylenediamines and the carbon atom of the basal face of graphite were determined. It was shown that an intramolecular H bond influenced the geometry and adsorption properties of o-phenylenediamine.

Energy Technology Data Exchange (ETDEWEB)

Properties of the multi-species electromagnetic Weibel and electrostatic two-stream instabilities are investigated for an intense ion beam propagating through background plasma. Assuming that the background plasma electrons provide complete charge and current neutralization, detailed linear stability properties are calculated within the framework of a macroscopic cold-fluid model for a wide range of system parameters.

British Library Electronic Table of Contents (United Kingdom)

Abstract A diacrylate polysulfone oligomer is synthesized and used as the acrylic oligomer for the in situ synthesis of noble metal/PSU nanocomposites through UV-induced simultaneous radical polymerization of acrylic functionalities and NP formation by reduction of their precursors. Thus, silver or gold NPs are formed in situ during polymer network formation. FESEM analysis of the morphology of the cured systems demonstrates that the nanoparticles of the noble metals are homogeneously distributed in the network without macroscopic agglomeration.

International Nuclear Information System (INIS)

This report focuses on a better understanding of the physical phenomenon related to the enhancement of boiling and non-boiling heat transfer by applying ultrasonic waves. Experimental results obtained both in a pool of water and in a vertically upward water flow proved clearly that macroscopic acoustic steam induced by ultrasonics is a major contribution to heat transfer augmentation. (author).

Science.gov (United States)

A simplified stormwater management model has been developed to provide an inexpensive, flexible tool for planning and preliminary sizing of stormwater facilities. The model was developed to be part of a methodology for use in the management of stormwater that utilizes both simple...

International Nuclear Information System (INIS)

A super-hydrophobic coating was prepared by combining a rigid base film with crater-like hemispherical holes and acicular nanoparticles. The acicular boehmite powder provides a high contact angle on the film surface. The rigid base film with crater-like hemispherical holes inhibits the rapid decrease of contact angle by surface rubbing. The combination of different roughness is an effective method for improving the abrasion resistance of super-hydrophobic films.

British Library Electronic Table of Contents (United Kingdom)

Comparative patterns of equilibrium adsorption of argon on the surface of graphitized thermal carbon black (GCB) and the inhomogeneous surfaces of nongraphitized carbon black and silica at 77 and 87.3 K were considered. It was shown that argon acquires the properties of a special phase with a layered structure and exhibits two-dimensional phase transitions with the formation of crystal-like layers near the homogeneous surface of GCB even at a temperature exceeding the triple point. However, already at a distance of three-four molecular diameters from the surface, adsorbed argon behaves as a bulk phase in a weak external field. The defect surface of nongraphitized carbon black and the amorphous surface structure of silica destroy the longrange order of adsorbed argon and lower its solidific...

British Library Electronic Table of Contents (United Kingdom)

Purpose - This paper discusses the impact of aesthetic design of smartphones on users' emotional reactions and preferences towards the product. To this end, the paper presents a study that explores emotional reaction of males to varying aesthetic design of the BlackBerry and empirically evaluates their preferences for the BlackBerry in different colours and overlay patterns. The paper then presents the statistical results of the study in an innovative graphical representation. Design/methodology/approach - A quantitative and qualitative research design was used, including three types of data-collection instruments (direct observations, rating scales, and interviews) to investigate if males have a stronger positive emotional reaction for visually treated BlackBerry Pearl devices over the or...

Energy Technology Data Exchange (ETDEWEB)

An apparatus is described for measuring the total hemispherical emittance of pipes of a length suitable for use in a prototype solar collector. The calorimetric method used requires measurements of the temperatures of the surface of the test pipe and of a concentric outer cylinder and measurement of the electrical power used to heat the test pipe. Measurements were made of the total hemispherical emittance of black chrome, nickel, and bare steel pipes as a function of temperature. The emittance of the black chrome surfaces increased significantly from an extrapolated value of about 0.1 at 25 deg C to values on the order of 0.3-0.4 at 300 deg C. The extrapolated values for black chrome agreed with measurements made using other techniques at room temperature. The results for the nickel-plated pipe agreed with total emittance calculated from spectral reflectance data.

UK PubMed Central (United Kingdom)

This article aims to open up the biographical black box of three experts working in the boundary zone between science, policy and public debate. A biographical-narrative approach is used to analyse...Full Text Available

UK PubMed Central (United Kingdom)

BackgroundThymoquinone (TQ) is a compound extracted from Black Caraway seeds of Nigella Sativa and is active against various cancers. Cisplatin (CDDP) is the most...Full Text Available

UK PubMed Central (United Kingdom)

We have examined the association between cytokine, chemokine and growth factor concentrations with bacterial vaginosis (BV) in pregnant white and black women. A nested case-control analysis...Full Text Available

UK PubMed Central (United Kingdom)

Factors potentially contributing to the lower incidence of Lyme borreliosis (LB) in the far-western than in the northeastern United States include tick host-seeking behavior resulting in fewer human...Full Text Available

UK PubMed Central (United Kingdom)

Racial and ethnic disparities in healthcare persist in the U.S. Although pain is one of the most prevalent and disabling symptoms of disease, only a few studies have assessed disparities in...Full Text Available

UK PubMed Central (United Kingdom)

Benzidine-based azo dyes are proven mutagens and have been linked to bladder cancer. Previous studies have indicated that their initial reduction is the result of the azo reductase activity of the intestinal...Full Text Available

Energy Technology Data Exchange (ETDEWEB)

Infrared astronomical instruments require absorptive coatings on internal surfaces to trap scattered and stray photons. This is typically accomplished with any one of a number of black paints. Although inexpensive and simple to apply, paint has several disadvantages. Painted surfaces can be fragile, prone to shedding particles, and difficult to clean. Most importantly, the vacuum performance is poor. Recently a plasma enhanced chemical vapor deposition (PECVD) process was developed to apply thick (30 {micro}m) diamond-like carbon (DLC) based protective coatings to the interior of oil pipelines. These DLC coatings show much promise as an infrared black for an ultra high vacuum environment. The coatings are very robust with excellent cryogenic adhesion. Their total infrared reflectivity of < 10% at normal incidence approaches that of black paints. We measured outgas rates of <10{sup -12} Torr liter/sec cm{sup ...

International Nuclear Information System (INIS)

The author demonstrates through a specific example that it is possible to extract rotational energy from a Kerr source (in principle, of arbitrary size but not turned black) through a reversible process by suitably injecting tachyons. (Auth.).

UK PubMed Central (United Kingdom)

BackgroundLifestyle, genetics and environmental factors are established determinants of bone density. We aimed to describe the bone characteristics of competitive top-ranked Nigerian...Full Text Available

British Library Electronic Table of Contents (United Kingdom)

Abstract A fabrication process for Emitter-Wrap-Through solar cells on monocrystalline material with high quality gap passivation by wet thermal silicon dioxide is investigated. Masking and structuring steps are performed by screen-printing technology. Via-holes are created by an industrially applicable high-speed laser drilling process. The cell structure features a selective emitter structure fabricated in a single high temperature step: a highly doped emitter at the via-holes and the rear side, allowing for a low via-hole resistivity as well as a low resistivity contact to screen-printed pastes, and a moderately doped front side emitter exhibiting high quantum efficiency in the low wavelength range. Therefore a novel approach is applied depositing either doped or undoped PECVD silicon d...

International Nuclear Information System (INIS)

We compare standard nuclear polarization mechanisms, #DELTA#-hole-polarization and meson-exchange-current effects in the q-dependent quenching of isovector spin transitions. Calculations are performed for the M1-transition form factors of the 1"+ states in "4"8Ca (10.23 MeV) and "8"8Sr (3.48 MeV). We obtain a satisfactory description of both form factors if the repulsive part of the residual interaction in the #DELTA#-hole channel is of similar strength to that in the nucleon-hole channel. Meson-exchange currents lead to an enhancement of M1 transitions by an amount which is small in general, but sensitive to the particular nuclear state involved. (orig.).

Science.gov (United States)

The purpose of this study is to search for a new method of dispersing spilled heavy oil, which has a detrimental effect on the natural environment and marine ecosystem. A method ejecting a waterjet vertically downward to heavy oil on the water surface was studied, particularly focusing on the effect of the guide nozzle shape. The waterjet comprised heavy oil and minute air bubbles, and passed through the hole of the guide nozzle. Thirteen guide nozzle shapes were tested and compared. The dispersion efficiency of a tapered hole was the best among the 13 nozzles. The flow in the hole of the guide nozzles was recorded by a high-speed video camera. The occurrence of two flows, regular and counter flows, was observed in the taper guide nozzle. It seemed that the counter flows generated the shearing force between the waterjet and the heavy oil layer. It is considered that the shearing force determines the surplus efficiency of ...

British Library Electronic Table of Contents (United Kingdom)

This paper introduces a new way of estimating parameters in a Brownian motion regime switching asset model to incorporate volatility clustering. The regime switching model is then applied to pricing of up-and-in barrier call options. We take the probability of crossing the barrier between simulation points into account, and we increase accuracy in simulations by importance sampling. The regime switching model is compared to the Normal Inverse Gaussian model and the traditional Black-Scholes model, and option prices from the regime switching model are compared to the closed form expression of up-and-in barrier calls in a Black-Scholes market.

International Nuclear Information System (INIS)

By comparison of standard entropies theoretically calculated and determined from gas-chromatographic data for 40 halo-aliphatic and halo-aromatic compounds 8 organic iodine compounds among them, adsorbed on graphitized thermal carbon black it was found that in all the cases the molecular model of ideal two-dimensional gas is a sufficiently good approximation. It was shown that for a number of systems the agreement can be improved if the vibrations of the center of molecular mass relative to the surface are taken into account

Science.gov (United States)

In this article, we describe an approach to model the electromechanical behavior of the skeletal muscle based on the Huxley formulation. We propose a model that complies with a well established macroscopic behavior of striated muscles where force-length, force-velocity, and Mirsky-Parmley properties are taken into account. These properties are introduced at the microscopic scale and related to a tentative explanation of the phenomena. The method used integrates behavior ranging from the microscopic to the macroscopic scale, and allows the computation of the dynamics of the output force and stiffness controlled by EMG or stimulation parameters. The model can thus be used to simulate and carry out research to develop control strategies using electrical stimulation in the context of rehabilitation. Finally, through animal experiments, we estimated model parameters using a Sigma Point Kalman Filtering technique and dedicated experimental protocols ...

Energy Technology Data Exchange (ETDEWEB)

A fractographic and numerical approach is presented to analyze hydrogen-plasticity interactions in pearlitic steel and to elucidate the main hydrogen transport mechanism in this material under triaxial stress states produced by notches. Fractographic analysis showed that the microdamage produced by the hydrogen was clearly detectable by scanning electron microscopy (SEM), through a specific microscopic topography associated with hydrogen effects (tearing topography surface or TTS). Numerical computations obtained by using an elastic-plastic finite element program gave the progressive spreading of the plastic zone, closely associated with the movement of dislocations. In the majority of cases, the plastic zone (PZ) clearly exceeds the hydrogen affected region (TTS) and has no relation with it. In some tests, however, the hydrogen-induced micro-damage surpasses the only region in which there is dislocation movement, and in this case the net macroscopic transport of ...

International Nuclear Information System (INIS)

New surface photometry of all known elliptical galaxies in the Virgo cluster is combined with published data to derive composite profiles of brightness, ellipticity, position angle, isophote shape, and color over large radius ranges. These provide enough leverage to show that Sersic log I #propor to# r "1"/"n functions fit the brightness profiles I(r) of nearly all ellipticals remarkably well over large dynamic ranges. Therefore, we can confidently identify departures from these profiles that are diagnostic of galaxy formation. Two kinds of departures are seen at small radii. All 10 of our ellipticals with total absolute magnitudes M_V_T #<=# -21.66 have cuspy cores-"missing light"-at small radii. Cores are well known and naturally scoured by binary black holes (BHs) formed in dissipationless ("dry") mergers. All 17 ellipticals with -21.54 #<=# M_V_T #<=# -15.53 do not have cores. We find a new distinct component in these galaxies: all ...

CERN Document Server

We study quantum Darwinism -- the redundant recording of information about a decohering system by its environment -- in zero-temperature quantum Brownian motion. An initially nonlocal quantum state leaves a record whose redundancy increases rapidly with its spatial extent. Significant delocalization (e.g., a Schroedinger's Cat state) causes high redundancy: many observers can measure the system's position without perturbing it. This explains the objective (i.e. classical) existence of einselected, decoherence-resistant pointer states of macroscopic objects.

Energy Technology Data Exchange (ETDEWEB)

This paper presents fundamental researches based on the electronic structure calculations and X absorption spectroscopy, allowing the knowledge on nuclear fuels at an atomic scale. They bring a better understanding of these material behavior to accurate the macroscopic simulation. The calculation methods, the experimental techniques of validation and the ab initio calculations results are detailed. (A.L.B.)

Energy Technology Data Exchange (ETDEWEB)

The production of many important commercial materials involves the evolution of a complex fluid through a cooling phase into a hardened product. Textile fibers, high-strength fibers(KEVLAR, VECTRAN), plastics, chopped-fiber compounds, and fiber optical cable are such materials. Industry desires to replace experiments with on-line, real time models of these processes. Solutions to the problems are not just a matter of technology transfer, but require a fundamental description and simulation of the processes. Goals of the project are to develop models that can be used to optimize macroscopic properties of the solid product, to identify sources of undesirable defects, and to seek boundary-temperature and flow-and-material controls to optimize desired properties.

International Nuclear Information System (INIS)

This work presents results of investigations on d.c. glow discharge nitriding of #alpha#+#beta# Ti-6Al-4V titanium alloy. The treatment was performed at 843 K in nitrogen-hydrogen atmosphere, pressure 300 Pa. Special attention was paid to nitriding mechanism and determination of the role of ion bombarding in nitriding process of titanium alloys. Produced as a result of d.c. plasma nitriding surface layers were subjected to macroscopic observations, microstructure studies, microhardness testing and X-ray analysis. (author)

Energy Technology Data Exchange (ETDEWEB)

We present a description of the ground state and low-lying excited states of two holes in the 4x4 cluster t-J model in terms of a simple model for the motion of a single bipolaron. The existence of short-range antiferromagnetic correlations has been assumed. According to the suggested scenario, the formation of the bipolaron is mediated by the reduction of the magnetic energy in the case of two holes occupying nearest neighbor sites. The relevant part of the Hilbert space consists of wave functions corresponding to holes oscillating around pairs of nearest neighbor sites and trapped in a potential well due to strings of spin defects. Virtual processes which connect these states involve both the kinetic term and the transverse part of the Heisenberg Hamiltonian. Many properties of energy level schemes obtained by numerical diagonalizations such as the sequence of the lowest states for each irreducible representation of the k ...

International Nuclear Information System (INIS)

Laser frequency stabilization giving a 500-Hz Allan deviation for a 2-ms integration time with drift reduced to 7 kHz/min over several minutes was achieved at 1536 nm in the optical communication band. A continuously regenerated spectral hole in the inhomogeneously broadened "4I_1_5_/_2(1)#->#"4I_1_3_/_2(1) optical absorption of an Er"3"+:Y_2SiO_5 crystal was used as the short-term frequency reference, while a variation on the locking technique allowed simultaneous use of the inhomogeneously broadened absorption line as a long-term reference. The reported frequency stability was achieved without vibration isolation. Spectral hole burning frequency stabilization provides ideal laser sources for high-resolution spectroscopy, real-time optical signal processing, and a range of applications requiring ultra-narrow-band light sources or coherent detection; the time scale for stability and the compatibility with spectral hole ...

Energy Technology Data Exchange (ETDEWEB)

An application of the renormalized random phase approximation to nuclear structure is presented for the semi-magic nuclei /sup 88/Sr and /sup 90/Zr. It is reported the outcome for the microscopic approach in comparison with the semiphenomenological version for the particle-hole forces.

Energy Technology Data Exchange (ETDEWEB)

Energy levels in N=50 nuclei are calculated allowing single-particle excitations from the p{sub 1/2} and g{sub 9/2} shells into the d{sub 5/2}, s{sub 1/2}, d{sub 3/2}, and g{sub 7/2} shells. Important parts of the interaction are determined by least-squares fits to known levels. Agreement with experiment is very good. The high-spin particle-hole states appear to be mainly yrast levels in mass 93 and higher, but are not in {sup 90}Zr. {copyright} {ital 1997} {ital The American Physical Society}

International Nuclear Information System (INIS)

The wide-angle spectra of the 134-MeV (p,n) reaction on "4"8Ca, "5"4Fe, "8"8Sr, and "2"0"8Pb are each dominated by the excitation of a single state at low excitation energy. These excitations correspond to the ''0h#omega#'' stretched states and are seen to be fragmented much less than ''1h#omega#'' stretched states in medium- and heavy-mass nuclei. The normalization factors required for comparison with distorted-wave impulse-approximation calculations are >0.50 and indicate that these are the purest particle-hole states known in these nuclei.

Energy Technology Data Exchange (ETDEWEB)

This report describes the results from acoustic emission (AE) and ultrasonic monitoring of the Aespoe Pillar Stability Experiment (APSE) at SKB's Hard Rock Laboratory (HRL), Sweden. The APSE is being undertaken to demonstrate the current capability to predict spalling in a fractured rock mass using numerical modelling techniques, and to demonstrate the effect of backfill and confining pressure on the propagation of micro-cracks in rock adjacent to deposition holes within a repository. An ultrasonic acquisition system has provided acoustic emission and ultrasonic survey monitoring throughout the various phases of the experiment. Results from the entire data set are provided with this document so that they can be effectively compared to several numerical modelling studies, and to mechanical and thermal measurements conducted around the pillar volume, in an 'integrated analysis' performed by SKB staff. This document provides an in-depth ...

Science.gov (United States)

Comparative patterns of equilibrium adsorption of argon on the surface of graphitized thermal carbon black (GCB) and the inhomogeneous surfaces of nongraphitized carbon black and silica at 77 and 87.3 K were considered. It was shown that argon acquires the properties of a special phase with a layered structure and exhibits two-dimensional phase transitions with the formation of crystal-like layers near the homogeneous surface of GCB even at a temperature exceeding the triple point. However, already at a distance of three-four molecular diameters from the surface, adsorbed argon behaves as a bulk phase in a weak external field. The defect surface of nongraphitized carbon black and the amorphous surface structure of silica destroy the longrange order of adsorbed argon and lower its solidification temperature. Therefore, argon adsorbed at a temperature of 77 K, i.e., below the triple point, exhibits the properties of a ...

British Library Electronic Table of Contents (United Kingdom)

Single crystal tungsten oxide (WO3) nanoparticles were prepared via a microwave-assisted method. Electrochemical activity for hydrogen evolution reaction (HER) on WO3 supported on carbon black (WO3/C) electrocatalyst was first studied in acid solution (0.5 M H2SO4) and alkaline solution (1.0 M KOH) at room temperature. The overall experimental results revealed that the electrocatalytic activity for HER on WO3/C is one order magnitude higher than those obtained with carbon black in 0.5 M H2SO4 and is six times than in the case of carbon black in 1.0 M KOH. These results demonstrated that WO3 could enhance the electrocatalytic activity for hydrogen evolution reaction in acid solution (0.5 M H2SO4) and alkaline solution (1.0 M KOH). On the other hand, the kinetic reaction mechanisms were disc...

International Nuclear Information System (INIS)

A new formulation of meson self-energies is introduced for #sigma#,#omega#,#pi#,#rho#,#delta#, and #eta# mesons on the basis of the particle-hole-antiparticle representation. We have studied the difference between the meson self-energy (MSE) of this representation and the MSE of the traditional density-Feynman (DF) representation. It is shown that the new formulation describes exactly the physical processes such as particle-hole excitations or particle-antiparticle excitations, and that, on the other hand, the meson self-energy based on the DF representation includes unphysical components. By numerical calculations, the meson self-energies describing the particle-hole excitations are shown to be close to each other for most of the meson self-energy in low momentum (R<500 MeV) and low energy (R_0<200 MeV). This fact implies that former calculations using the low momentum and low-energy part do not change greatly. The ...

British Library Electronic Table of Contents (United Kingdom)

In this study, the use of the weakly basic anion exchange resins of phenol-formaldehyde (Amberlyst A 23), polyacrylate (Amberlite IRA 67) and polystyrene (Lewatit MonoPlus MP 62) matrices for removal of the reactive dye Remazol Black B (RBB) from aqueous solution and wastewater were investigated. RBB sorption on the anion exchangers was a time dependent process. Color reduction percentiles of 75.2, 33.9 and 25.1% in wastewater treatment were found after 216 h of phase contact time with Lewatit MonoPlus MP 62, Amberlyst A 23 and Amberlite IRA 67, respectively. Inorganic salts and anionic surfactant action influenced RBB uptake by the anion exchangers. The amounts of dye retained by the anion exchangers increased with a rise in temperature. The maximum sorption capacities calculated from the...

Energy Technology Data Exchange (ETDEWEB)

On efficient glass capillary columns packed with graphitized thermal carbon black (GTCB) the stereoisomers of aromatic and saturated tricyclic hydrocarbons are completely separated and identified. The Henry's adsorption constants of the individual isomers were determined from mixture at different temperatures. Five isomers of perhydroanthracene, five isomers of perhydrofluorene, two isomers of perhydrophenalene, four isomers of perhydroacenaphthene, as well as phenalene, dihydrophenalene, acenaphthene and acenaphthylene were investigated. The increase of the hydrogenization degree of unsaturated tricyclic hydrocarbons reduces the retention. Among the saturated tricyclic isomers the retention becomes shorter with the larger bending of the molecules, i.e. from the molecule having more equatorial bonds to the molecules having more axial connections. The experimentally determined Henry's constants were qualitatively compared with the structure of the ...

Energy Technology Data Exchange (ETDEWEB)

The possibility of employing a number of adsorbents (polyphenylquinoxaline, Tenax GC, Carbopak C, graphitized thermal carbon black, silica gels modified with pyrocarbon or hexamethyldisilazane) for the trapping of organic traces from air has been investigated. Adsorption capacities of these adsorbents with respect to a number of volatiles released from certain plastics used as building material (polyvinylchloride, Relin, Acronal, etc.) have been measured. A number of the volatiles were identified by gas chromatography - mass-spectrometry after trapping on the adsorbents investigated. Chromatographic separation after trapping on the adsorbents was carried out on wall-coated open-tubular capillary columns as well as in capillary columns packed with graphitized thermal carbon black.

CERN Document Server

A historical overview is given on the basic results which appeared by the year 1926 concerning Einstein's fluctuation formula of black-body radiation, in the context of light-quanta and wave-particle duality. On the basis of the original publications (from Planck's derivation of the black-body spectrum and Einstein's introduction of the photons up to the results of Born, Heisenberg and Jordan on the quantization of a continuum) a comparative study is presented on the first line of thoughts that led to the concept of quanta. The nature of the particle-like fluctuations and the wave-like fluctuations are analysed by using several approaches. With the help of the classical probability theory, it is shown that the infinite divisibility of the Bose distribution leads to the new concept of classical poissonian photo-multiplets or to the binary photo-multiplets of fermionic character. As an application, Einstein's fluctuation formula is derived as a ...

Energy Technology Data Exchange (ETDEWEB)

The black carbon continuum is composed of a series of carbon-rich components derived from combustion or metamorphism and characterized by contrasting environmental behavior and susceptibility to oxidation. In this work, we present a micro-scale density fractionation method that allows isolating the small quantities of soot-like and graphitic material usually found in natural samples. Organic carbon and {delta}{sup 13}C mass balance calculations were used to quantify the relative contributions of the two fractions to thermally-stable organic matter from a series of aquatic sediments. Varying proportions of soot-like and graphitic material were found in these samples, with large variations in {delta}{sup 13}C signatures suggesting important differences in their origin and/or dynamics in the environment.

Science.gov (United States)

The thermodynamic characteristics of adsorption of iodobenzene, 2-iodothiophene, and 1- and 2-iodoadamantanes on the surface of graphitized thermal carbon black were determined experimentally. The influence of the special features of the molecular structure of the adsorbates on the thermodynamic characteristics of adsorption was studied. The atom-atom approximation of the semiempirical molecular-statistical theory of adsorption was used to calculate the thermodynamic characteristics of adsorption of the adsorbates using the newly determined potential function parameters of pair intermolecular interaction (?( r)) of I with C atoms of the basal graphite face. For the example of isostructural monohalogenated benzenes, thiophenes, and adamantanes, a comparative analysis of the contributions of the F, Cl, Br, and I atoms to the thermodynamic characteristics of adsorption was performed for the nonspecific adsorption of these compounds on a plane graphitized carbon ...

CERN Document Server

Liquid-liquid wetting failure is investigated in a two-dimensional Couette system with two immiscible fluids of arbitrary viscosity. The problem is solved exactly using a sharp interface treatment of hydrodynamics (lubrication theory) as a function of the capillary number, viscous ratio and separation of scale, i.e. slip length versus macroscopic scale of the system. The existence of critical velocities, above which no stationary solutions are found, is analyzed in detail in terms of the relevant parameters of the system. Comparisons with existing analysis for other geometries are also carried out. A numerical method of analysis is also presented, based on diffuse interface models obtained from multiphase extensions of the lattice Boltzmann equation (LBE). Sharp interface and diffuse interface models are quantitatively compared face to face indicating the correct limit of applicability of the diffuse interface models.

CERN Document Server

Upcoming high-intensity laser systems will be able to probe the quantum-induced nonlinear regime of electrodynamics. So far unobserved QED phenomena such as the discovery of a nonlinear response of the quantum vacuum to macroscopic electromagnetic fields can become accessible. In addition, such laser systems provide for a flexible tool for investigating fundamental physics. Primary goals consist in verifying so far unobserved QED phenomena. Moreover, strong-field experiments can search for new light but weakly interacting degrees of freedom and are thus complementary to accelerator-driven experiments. I review recent developments in this field, focusing on photon experiments in strong electromagnetic fields. The interaction of particle-physics candidates with photons and external fields can be parameterized by low-energy effective actions and typically predict characteristic optical signatures. I perform first estimates of the accessible new-physics parameter space ...

CERN Document Server

A macroscopic realization of the strange virtual particles is presented. The classical Helmholtz and the quantum mechanical Schr\\"odinger equations are analogous differential equations. Their imaginary solutions are called evanescent modes in the case of elastic and electromagnetic fields. In the case of non-relativistic quantum mechanical fields they are called tunneling solutions. The imaginary solutions of this differential equation point to strange consequences: They are non local, they are not observable, and they described as virtual particles. During the last two decades QED calculations of the imaginary solutions have been experimentally confirmed for phonons, photons, and for electrons. The experimental proofs of the predictions of the non-relativistic quantum mechanics and of the Wigner phase time approach for the elastic, the electromagnetic and the Schr\\"odinger fields will be presented in this article. The results are zero tunneling time and an ...

Energy Technology Data Exchange (ETDEWEB)

High-energy synchrotron x-ray diffraction (XRD) has been used to quantify load transfer in bovine plexiform bone. By using both wide-angle and small-angle XRD, strains in the mineral as well as the collagen phase of bone were measured as a function of applied compressive stress. We suggest that a greater proportion of the load is borne by the more mineralized woven bone than the lamellar bone as the applied stress increases. With a further increase in stress, load is shed back to the lamellar regions until macroscopic failure occurs. The reported data fit well with reported mechanisms of microdamage accumulation in bovine plexiform bone.

International Nuclear Information System (INIS)

The determination of ratio of neutron over proton matrix elements by inelastic proton scattering, for 0"+#->#2"+ transitions, is investigated via the comparison between experimental data and theoretical calculations. Calculations into the context of a macroscopic and a microscopic description are performed for a wide mass range nuclei: "1"8O, "3"0Si, "3"2","3"4S, "4"8Ca, "8"8Sr, for which these ratios were determined previously with an independent technique. At that point the choice of the theoretical model may be very critical. It is thus the purpose of this investigation to point out the most suitable model. It is found that in general both theoretical models can be employed for the reliable determination of neutron over proton matrix element ratios.

British Library Electronic Table of Contents (United Kingdom)

Abstract Introduction: Laparoscopic subtotal adrenalectomy (LSA) has emerged as a treatment option in the management of certain adrenal pathologies. After LSA, a satisfactory blood supply to the adrenal remnant is vital to preserve steroid function. The aim of this study was to review the adrenal blood supply with relevance to LSA. Materials and Methods: The adrenal blood supply was examined in three ways: 1) a review of six previous cadaver studies looking at adrenal blood supply; 2) a review of our 164 consecutive laparoscopic adrenalectomies (LAs) (January 1999?January 2009); the details of the main adrenal veins and variants had been prospectively recorded; and 3) dissection of 4 cadaver specimens (macroscopic and histologic examination was performed). Results: The six cadaver studies ...

British Library Electronic Table of Contents (United Kingdom)

Objective: : Evaluate expression of inducible negative regulators of JAK/STAT pathway and their target proteins during the course of ligature-induced experimental periodontal disease in rats. Design: : Rats were sacrificed 07, 15 and 30days after disease induction for histological evaluation of periodontal inflammation and macroscopic analysis of alveolar bone loss. SOCS expression and the activation status of STAT1 and STAT3 were evaluated in gingival biopsies by real time PCR and Western blot. Results: : Ligature-induced model presented significant progressive bone loss from 7 to 30days. Inflammation was evident and similar for 07 and 15days; however, a decrease on severity at the end of the experimental period was observed. There was a significant (p<0.05) increase on SOCS1 and SOCS3 ge...

International Nuclear Information System (INIS)

Reduction of the metallic impurity concentration in the TCA plasma has enabled us to correlate the observed heating with the calculated position where the rf energy is deposited. In modelling the measured antenna loading due to the presence of Alfven resonance surfaces, and hence inferring the energy deposition profile, both ion cyclotron effects and the toroidal geometry must be considered. In particular, toroidicity couples energy to resonance surfaces that would not be excited in cylindrical geometry. The increase in electron density during a rf pulse changes the positions of these surfaces so that spectrum-related effects may be observed. The appearance of a new surface at the centre of the plasma is seen as a sharp discontinuity on many of the macroscopic parameters, accompanied by evidence of changes in the current density profile. These results, and the predictions of numerical codes, have imposed new constraints on the optimisation of our antenna system.

British Library Electronic Table of Contents (United Kingdom)

Background Photopolymerizable poly(ethylene glycol) (PEG) hydrogels offer a platform to deliver cells in vivo and support three-dimensional cell culture but should be designed to degrade in sync with neotissue development and endure the physiologic environment. Questions/purposes We asked whether (1) incorporation of degradation into PEG hydrogels facilitates tissue development comprised of essential cartilage macromolecules; (2) with early loading before pericellular matrix formation, the duration of load affects matrix production; and (3) dynamic loading in general influences macroscopic tissue development. Methods Primary bovine chondrocytes were encapsulated in hydrogels (n?=?3 for each condition). The independent variables were hydrogel degradation (nondegrading PEG and degrading olig...

International Nuclear Information System (INIS)

We present results of multiple-time-scale simulations of 5, 10 and 15 keV low temperature ion implantation of arsenic on silicon (100), followed by high temperature anneals. The simulations start with a molecular dynamics (MD) calculation of the primary state of damage after 10ps. The results are then coupled to a kinetic Monte Carlo (MC) simulation of bulk defect diffusion and clustering. Dose accumulation is achieved considering that at low temperatures the damage produced in the lattice is stable. After the desired dose is accumulated, the system is annealed at 800 degrees C for several seconds. The results provide information on the evolution for the damage microstructure over macroscopic length and time scales and affords direct comparison to experimental results. We discuss the database of inputs to the MC model and how it affects the diffusion process.

International Nuclear Information System (INIS)

The dependence of the carrier concentrations, of the resistivity and of the Hall coefficient of irradiated silicon on the neutron fluences has been investigated, starting from the supposition that the main phenomena induced by irradiation in the semiconductor bulk are shallow-donor removal and deep-centres creation. The free parameters of the model are initial doping of the starting material, the permitted energy level values of the radiation-induced centres in the semiconductor band gap and their introduction rates. The influence of each parameter on the calculated dependences is studied in detail, for three cases: one deep acceptor-like centre, two deep acceptors and one deep acceptor plus one deep donor-like centre. each of the three cases is discussed in correspondence with different experimental results.

Energy Technology Data Exchange (ETDEWEB)

One of the most loaded parts of a steam generator of VVER 440 MW type are the bolts and thread holes of the primary collector cover sealing set. The strength calculations and tensometric measurings performed during operation proved the high degree of a load on the bolts. The conditions of the stress limitation are not met in some cases according to the pertinent standards. The untightnesses at nickel rings occurred during putting the units of Jaslovske Bohunice and Dukovany nuclear power stations into operation. With regard to improve the reliability, the producer has taken measures to improve the quality of the rings and users have introduced more strict regulations for bolts tightening. Due to these measures the high reliability of the set has been obtained from point of view of the tightness, but substantial reduction of bolts and holes threads loading have not been obtained. Several years operation experience proved relatively low service ...

Energy Technology Data Exchange (ETDEWEB)

A method to control charge transfer reaction in DNA using hybrid nanometer-sized TiO{sub 2} nanoparticles was developed. In this system extended charge separation reflects the sequence of DNA and was measured using metallic silver deposition or by photocurrent response. Light-induced extended charge separation in these systems was found to be dependent on the DNA-bridge length and sequence. The yield of photocatalytic deposition of silver was studied in systems having GG accepting sites imbedded in AT runs at varying distances from the TiO{sub 2} nanoparticle surface. Weak distance dependence of charge separation indicative of a hole hopping through mediating adenine (A) sites was found. The quantum yield of silver deposition in the system having a GG accepting site placed 8.5 {angstrom} from the nanoparticle surface was found to be {Phi} = 0.70 (70%) and {Phi} = 0.56 (56%) for (A){sub n} and (AT){sub n/2} bridge, respectively. Hole injection ...

International Nuclear Information System (INIS)

The inspection of PFR evaporator tubing, superheater and reheater tubing, and tube plate examinations, are described. Ferritic steel U tubes in the evaporator have been examined by an eddy current system operating at 400 kHz using flexible rotating probes. Surface defects as shallow as 0.1 mm can be detected and sized in the range 0.1 to 0.5 mm deep. An ultrasonic method is under development for wall thickness. Special test coil probes have been developed for examination of the type 316 stainless steel superheater and reheater tubing. Crack-life defects in the bore are detectable at approximately 10% wall thickness and 20% on the outside diameter. Tube plate examinations from the tube holes, have been conducted using eddy current probes which identify surface breaking cracks in the holes. For detecting curtain cracks between tube plate holes, ultrasonic compression wave probes have been used. (U.K.).

International Nuclear Information System (INIS)

This report is in accordance with Phase I of the United States Department of Energy and Bureau of Mines Contract No. USDOE DE-AC01-77QQ90147. A thorough literature search was conducted and the current mining practice at nine coal stripping operations reviewed in detail. A review of the state of the art of blast design using current theory and practice is presented. Based upon this information, a series of recommendations are presented and a detailed test program is outlined for three operations. The recommendations to increase dragline productivity by improved blast design are directed at filling the bucket more quickly, with greater consistency and with a better fill factor: (a) overburden fragmentation, (b) muckpile displacements, and (c) blasting reliability. Recommended blast design concepts and operating procedures to provide the desired blast performance include: (1) Increase energy input per BCY by 40 to 100 percent and improve the effective powder distribution by modifying ...

British Library Electronic Table of Contents (United Kingdom)

Manual drilling in titanium structures is a tedious and labor-intensive work. To reduce man-hour requirements while concurrently improving hole quality, we developed a robotic drilling system for this application. The lean system contains the product holding fixture, the industrial robot, the end effector, the control and sensor system, and the offline programming. The system functions include locating workpiece with a calibration stick or the vision system, weld mark inspection, one-sided clamping, drilling and reaming hole in material stack combinations of titanium and aluminum, and real-time thrust force feedback. The positional accuracy and the repeatability of the system have successfully been placed within the specification?s 0.3?mm tolerance and 0.2?mm tolerance, respectively. The d...

Energy Technology Data Exchange (ETDEWEB)

We continue the study of the hole coupling resonator for free electron laser (FEL) application. The previous resonator code is further developed to include the effects of the azimutally asymmetric modes and the FEL gain. The implication of the additional higher order modes is that there are more degeneracies to be avoided in tuning the FEL wavelengths. The FEL interaction is modeled by constructing a transfer map in the small signal regime and incorporating it into the resonator code. The FEL gain is found to be very effective in selecting a dominant mode from the azimuthally symmetric class of modes. Schemes for broad wavelength tuning based on passive mode control via adjustable apertures are discussed. 12 refs., 7 figs., 1 tab.

Energy Technology Data Exchange (ETDEWEB)

The pronounced selectivity of near-threshold (p,..pi../sup -/) reactions for high-spin two-particle, one-hole states is exploited, in the first spectroscopic application of a (p,..pi..) reaction, to identify previously unknown 25/2/sup +/ and 21/2/sup +/ (g/sub 9/2/)/sup 3/ states in /sup 89/Zr. Relative cross sections for the two transitions are well reproduced by simple model calculations. The analyzing power for the 25/2/sup +/ state is markedly similar to previous (p/sub pol/,..pi../sup -/) results for two-particle one-hole stretched states in lighter nuclei.

Energy Technology Data Exchange (ETDEWEB)

Problems can sometimes occur during the construction of cast in-situ concrete piles. These foundations are formed by drilling a substantial hole into the ground and subsequently filling it with steel reinforcement and wet concrete. Several well-documented cases exist where concrete has not filled the hole and substantial voids have been left in the apparently completed pile. A theory has been developed by which it is possible to identify the nature, size and position of a finite defect within a suspect pile. The technique is based on the concept of receptances, and requires information obtained from vibration tests performed on piles after the concrete has hardened, and the nominal dimensions and material properties of the pile. The application of the theory is demonstrated using data relating to a pile with a known defect. The theory described in this paper ignores the effect of the surrounding soil; this can be included by further development ...

UK PubMed Central (United Kingdom)

The sera of NZB/BL mice have been found to be active in the complement fixation test against isogeneic liver antigens to a higher titre than the sera of CBA, C57BL and DBA/2 mice. Six sera from NZB...Full Text Available

Energy Technology Data Exchange (ETDEWEB)

A study has been made of the interaction between graphitized thermal carbon-black and cyclodextrins and a series of 28 derivatives of benzene (benzene, alkyl-, isoalkyl-, dialkyl-, trialkylbenzenes, vinyl-, and allyl-benzene). The specific retention volumes form the basis for a discussion of the mechanism of interaction and drawing conclusions for the practical separation of isomeric compounds. (orig.).

Energy Technology Data Exchange (ETDEWEB)

The method and results of the quantitative gas chromatographic determination of volatile organic substances in an urban atmosphere are presented. The concentration of organic substances was determined by using a mixed adsorber consisting of graphitized thermal carbon black and activated charcoal modified by pyrocarbon. Average, maximum and minimum concentrations of constant organic components in the atmosphere of Leningrad as a typical large industrial city are reported.

Science.gov (United States)

Adsorption of ethylene and ethane on graphitized thermal carbon black and in slit pores whose walls are composed of graphene layers is studied in detail to investigate the packing efficiency, the two-dimensional critical temperature, and the variation of the isosteric heat of adsorption with loading and temperature. Here we used a Monte Carlo simulation method with a grand canonical Monte Carlo ensemble. A number of two-center Lennard-Jones (LJ) potential models are investigated to study the impact of the choice of potential models in the description of adsorption behavior. We chose two 2C-LJ potential models in our investigation of the (i) UA-TraPPE-LJ model of Martin and Siepmann for ethane and Wick et al. for ethylene and (ii) AUA4-LJ model of Ungerer et al. for ethane and Bourasseau et al. for ethylene. These models are used to study the adsorption of ethane and ethylene on graphitized thermal carbon black. It is found that the solid-fluid ...

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 ...

Energy Technology Data Exchange (ETDEWEB)

Non-uniform radionuclide distribution in tumours will lead to a non-uniform absorbed dose. The aim of this study was to investigate how tumour control probability (TCP) depends on the radionuclide distribution in the tumour, both macroscopically and at the subcellular level. The absorbed dose in the cell nuclei of tumours was calculated for {sup 90}Y, {sup 177}Lu, {sup 103m}Rh and {sup 211}At. The radionuclides were uniformly distributed within the subcellular compartment and they were uniformly, normally or log-normally distributed among the cells in the tumour. When all cells contain the same amount of activity, the cumulated activities required for TCP = 0.99 (A-tilde{sub TCP=0.99}) were 1.5-2 and 2-3 times higher when the activity was distributed on the cell membrane compared to in the cell nucleus for {sup 103m}Rh and {sup 211}At, respectively. TCP for {sup 90}Y was not affected by different radionuclide distributions, whereas for {sup 177}Lu, it was slightly ...

Science.gov (United States)

This study addresses the modeling of transdermal diffusion of drugs, to better understand the permeation of molecules through the skin, and especially the stratum corneum, which forms the main permeation barrier of the skin. In transdermal delivery of systemic drugs, the drugs diffuse from a patch placed on the skin through the epidermis to the underlying blood vessels. The epidermis is the outermost layer of the skin and can be further divided into the stratum corneum (SC) and the viable epidermis layers. The SC consists of keratinous cells (corneocytes) embedded in the lipid multi-bilayers of the intercellular space. It is widely accepted that the barrier properties of the skin mostly arises from the ordered structure of the lipid bilayers. The diffusion path, at least for lipophilic molecules, seems to be mainly through the lipid bilayers. Despite the advantages of transdermal drug delivery compared to other drug delivery routes such as oral dosing and injections, the low ...

Wastenet

... Space weather is the biggest driver of ozone depletion and much else we are only beginning to understand. Solar Cycle 24 may turn out to be weak in terms of sun spot count but the amount of energy delivered by CME/SPE will probably not be. Remember that the Carrington Event in 1859 happened during a cycle with a lowish sun spot count. Recommend (1) Report abuse ...

UK PubMed Central (United Kingdom)

The covered self-expandable metallic stent (SEMS) has been developed to overcome the problem of tissue in­growth, However, stent migration is a well-known com­­plication of covered...Full Text Available

CERN Document Server

Using spectral hole-burning-based ultraslow group velocity in a dilute solid medium, we report enhanced photon echo efficiency three orders of magnitude higher than that in a nonslow light regime. The enhancement is due to exponentially increased absorption of an optical data pulse owing to the enhanced photon-atom interaction in an ultraslow light regime, whereas echo reabsorption is negligibly small due to group-velocity dependent population depletion.

Wastenet

... It is well camouflaged and each individual has unique back pattern markings. It eats mainly spiders and insects. The Eastern Lined Earless Dragon is a small dragon lizard measuring up to 21cm in length. It is well camouflaged and each individual has unique back ... It is well camouflaged and each individual has unique back pattern markings. It eats mainly spiders and insects. It lives in and around grass tussocks as well as small holes in the ground that are also used by invertebrates such as wolf spiders and crickets....

Energy Technology Data Exchange (ETDEWEB)

This study by CTES, L.C. meets two main objectives. First, evaluate the feasibility of using coiled tubing (CT) to drill 1.0 inches-2.5 inches diameter directional holes in hard rocks. Second, develop a conceptual design for a micro borehole drilling platform (MBDP) meeting specific size, weight, and performance requirements. The Statement of Work (SOW) in Appendix A contains detailed specifications for the feasibility study and conceptual design.

Energy Technology Data Exchange (ETDEWEB)

Concerning heat transfer augmentation of an axisymmetric impinging jet using a perforated plate set, the bore of the hole in the plate for local and averge heat transfer rate, pitch, and effect of the distance between perforated plate and target plate were examined. Heat transfer augmentation was examined under the condition of 0.063 /ge/d/D /ge/0.200, 1.25 /ge/p/d /ge/4.00, Re is approximately equal to 18000, (where d is the bore of the hole in the plate, D is the axisymmetric nozzle outlet bore, p is the pitch of the perforated plate, and Re is the jet Reynolds number). The findings are as follows; The velocity of the small jet after passing the perforated plate is reduced, and resistance to disturbance is remarkably large. The small jet which is not at the center hole extends to the outside of the plate. The heat transfer rate at a stagnation point is high when the target plate is placed in the jet potential core area ...

Energy Technology Data Exchange (ETDEWEB)

With an objective to detect gas leaking from an underground gas pipeline, discussions have been given on a method which utilizes acoustic characteristics of leakage. On leaking sound generated from damaged portions, the form of damaging was hypothesized as pinholes, and spectra of leaking sounds from holes with different diameters were measured. The dominant frequency decreases as the hole diameter increases, while it is in a region of relatively high frequency of 1 kHz or higher. However, detection from the ground surface was impossible when cover soil has thickness from 0.5 to 1.5 m. In an experiment to measure leaking sound inside the pipe, pressure in the pipe was adjusted to 0.02 atm which is a standard pressure for a low-pressure pipe, and the sound was measured when the hole diameters were varied. In any of the results obtained by varying the hole diameter, spectra having the dominant frequency ...

Energy Technology Data Exchange (ETDEWEB)

A downhole seismic source which can output continuous waves having arbitrary waveforms was developed. The development was targeted to make tomographic exploration purposed to evaluate geological properties of a ground bed before and after constructing a building in a ground several hundred meters deep from the ground surface. The source is considered to be used in an environment consisting of soft rocks or more robust rocks and having no casing. It can be used in a well hole having a diameter of 100 mm, is capable of measuring P and S waves in a distance between well holes of up to 100 m, can be used at a depth of up to 500 m, and can output waveforms having seismic source spectra of up to 1000 Hz. An oscillation actuator using laminated piezo-electric elements was used for the oscillation element. The seismic source consists of a hydraulic device to clamp the equipment onto hole walls, piezo-electric elements as the ...

International Nuclear Information System (INIS)

In this paper, finite-difference time-domain method is used to research the transient electromagnetic pulse (EMP) coupling to the cylinder object which is shielded in another shielding cavity with a hole numerically. The different coupling effectiveness of three transient EMP is simulated. The distribution of the electric field in the shielding cavity and the current on the cavity are researched. The shielding effectiveness is evaluated. (authors)

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 ...

Energy Technology Data Exchange (ETDEWEB)

The microbial process of converting organic matter into methane and carbon dioxide is so complex that anaerobic digesters have long been treated as {open_quotes}black boxes.{close_quotes} Research into this process during the past few decades has gradually unraveled this complexity, but many questions remain. The major biochemical reactions for forming methane by methanogens are largely understood, and evolutionary studies indicate that these microbes are as different from bacteria as they are from plants and animals. In anaerobic digesters, methanogens are at the terminus of a metabolic web, in which the reactions of myriads of other microbes produce a very limited range of compounds - mainly acetate, hydrogen, and formate - on which the methanogens grow and from which they form methane. {open_quotes}Interspecies hydrogen-transfer{close_quotes} and {open_quotes}interspecies formate-transfer{close_quotes} are major mechanisms by which methanogens obtain their ...

Energy Technology Data Exchange (ETDEWEB)

Both x-ray and optical cone-beam CT (CBCT) scanners are limited by scattered photons that contaminate the primary images. Transparent radiochromic gels and plastics are anticipated to produce less scattering than polymerization gels and hence result in reconstructed dose distributions with greater contrast and dynamic range. Four methods of scatter measurement were investigated to quantify scatter fractions using an in-house optical CBCT scanner. The methods consisted of generating either 'coin' shadows or primary beamlets in transmission images. The four methods generated similar results of 10% scatter fractions in gel transmission images for this particular scanner configuration with both leuco crystal violet and carbon black micelle gels. The scatter contributions were distributed as 5% from micelle gel, 2% from Teflon wall, 2% from refractive index matching liquid and 1% other sources. Applying a uniform background subtraction of 2% of open ...

International Nuclear Information System (INIS)

For an assessment of the future US spallation neutron source (SNS) target performance, radiation induced hardening and microstructural evolution were investigated as a function of ion dose for EC316LN stainless steel. Irradiation was carried out using 3.5 MeV Fe"+, 360 keV He"+, and 180 keV H"+ simultaneous ion-beams at 200 deg. C to simulate the damage, He and H production in the SNS target vessel wall. At low dose (< 1 dpa), the predominant defects were black dots whose number density saturated rapidly within a few dpa. This was followed by the evolution of interstitial loops whose number density saturated below 15 dpa. Although He-bubbles were not visible, severely scalloped loops suggested that the implanted He/H atoms existed in the form of small clusters. Comparison with reported neutron irradiation data showed that hardening and ductility loss occurred mostly in the black dot regime (< 1 dpa), but that good ductility (>20% ...

Energy Technology Data Exchange (ETDEWEB)

Assessment of the oil shale resources in Kentucky has continued with 75 NX cores available where the oil shale crops out or is overlain by relatively thin cover in the area from Estill County westward to Bullitt County. In this 14 county area, the total black shale section thins across the crest of the Cincinnati arch and changes stratigraphically from that characteristic of the Ohio Shale in Estill County to that of the New Albany Shale in Bullitt County. Despite this stratigraphic transition the two high-carbon zones (greater than 8.0% carbon) can be traced across the arch. As the traverse is followed from the east, the intervening low-carbon zones thin such that at the crest of the arch, there are areas where the entire section of black shale contains more than 8% carbon. Then upon leaving the crest the two high-carbon zones separate again with one remaining at the very top of the section and one in the lower part. In the 14 county area, ...

International Nuclear Information System (INIS)

In many experiments involving fast neutrons generated in nuclear reactions initiated by accelerator produced charged particle beams, it is important to be able to determine accurately the neutron yield from the target. A detector suitable for such applications should have: a constant efficiency over a large energy range; a fast time response; and the ability to discriminate between gamma rays and neutrons. The authors have constructed a open-quotes black neutron detectorclose quotes based on the design of Poenitz that has these characteristics. At the Lowell Van de Graaff accelerator laboratory neutrons are produced via the "7Li(p,n)"7Be reaction using a pulsed proton beam which impinges on metallic lithium targets. The pulsed beam enables the detector to be used in a time-of-flight spectrometer. Use of BC501 liquid scintillator permits neutron-gamma discrimination. The scintillator is viewed by five RCA 48796 photo tubes. The detector is housed in a massive shield ...

Energy Technology Data Exchange (ETDEWEB)

In the framework of the European Fusion Technology Programme ECN participates in a NET task PSM-8 `Coatings and Surface Effects on Stainless Steel 316L`. High emissivity coatings were developed for enhanced heat transfer from graphite tiles to a Stainless Steel First Wall. Four candidate materials, Cr{sub 2}O{sub 3}, Black Cr, Al{sub 2}O{sub 3}/TiO{sub 2} and TiC were tested as candidate high emissivity coatings. These coatings were manufactured by atmospheric and vacuum plasma spraying technique and the Black Chromium coatings were manufactured by a galvanic coating technique. The tests included total emissivity measurements and Low Cycle Fatigue (LCF) experiments. The total emissivity of two TiC coatings at 525 K appeared to be 0.62 and 0.64. The total emissivity of the TiC and 5 wt% TiO{sub 2}/Al{sub 2}O{sub 3} coating was about 0.7. (orig.)

Science.gov (United States)

In this paper we consider the adsorption of argon on the surface of graphitized thermal carbon black and in slit pores at temperatures ranging from subcritical to supercritical conditions by the method of grand canonical Monte Carlo simulation. Attention is paid to the variation of the adsorbed density when the temperature crosses the critical point. The behavior of the adsorbed density versus pressure (bulk density) shows interesting behavior at temperatures in the vicinity of and those above the critical point and also at extremely high pressures. Isotherms at temperatures greater than the critical temperature exhibit a clear maximum, and near the critical temperature this maximum is a very sharp spike. Under the supercritical conditions and very high pressure the excess of adsorbed density decreases towards zero value for a graphite surface, while for slit pores negative excess density is possible at extremely high pressures. For imperfect pores (defined as ...

Energy Technology Data Exchange (ETDEWEB)

This invention is concerned with a solar energy system for propelling aircraft. Obtained are forces for aerodynamic lift and impetus. The lifted body had a transparent upper surface for the sun light, but black or reflecting for IR-radiation and high thermal insulation properties. Inside of the lifted body, the air temperature increases and is lifted by convection influence. The air resistance of this body is low in horizontal direction and higher in vertical position. The payload could be shifted, so that the positive or negative angle of the whole body can be selected. By this principal it is possible to transform the static lifting force in a dynamic impetus.

Science.gov (United States)

The removal of Reactive Black 5 dye in an aqueous solution by electrocoagulation (EC) as well as addition of flocculant was investigated. The effect of operational parameters, i.e. current density, treatment time, solution conductivity and polymer dosage, was investigated. Two models, namely the artificial neural network (ANN) and the response surface method (RSM), were used to model the effect of independent variables on percentage of dye removal. The findings of this work showed that current density, treatment time and dosage of polymer had the most significant effect on percentage of dye removal (p0.8). PMID:21411950

Wastenet

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Energy Technology Data Exchange (ETDEWEB)

Methods are discussed for optimization of organizational model of longwall mining. Operations at a working face, their duration, number of miners, miner qualifications are analyzed. The so-called method for allocation of heteregeneous resources is used. Using the method optimum organizational models of working faces are constructed. The models consider working conditions, coal output, personnel, miner qualifications, duration of various operations and of idletime, and safety regulations. A computer code developed by the author for optimizing organizational models of longwall mining is described. 9 refs.

Science.gov (United States)

The total area ( s m) of Voronoi-Dirichlet polyhedron faces corresponding to all intermolecular contacts of one molecule in the structure of crystals and the total volume of pyramids ( V m) built on such faces and containing the nuclei of atoms participating in intermolecular contacts in their vertices were determined for 19 unsaturated hydrocarbons. The differential molar heat of adsorption of the hydrocarbons on graphitized thermal carbon black was found to be linearly related to the s m or V m integral parameters of their Voronoi-Dirichlet polyhedra. Aromatic hydrocarbons on the one hand and saturated hydrocarbons, olefins, and acetylene on the other are characterized by different dependences because of the special shapes of their molecular Voronoi-Dirichlet polyhedra.

Energy Technology Data Exchange (ETDEWEB)

The key component for improving the energy efficiency and cycle life of the electrically rechargeable zinc-air battery is the bifunctional air electrode. The air electrodes described in this paper contained different types of carbon black as the substrate for the perovskite catalyst (La{sub 0.6}Ca{sub 0.4}CoO{sub 3}). Morphological and physical properties of the carbon substrates play an important role in enhancing the activity and stability of the bifunctional air electrode. Current-potential curves and cycle-life tests were applied in order to gather information on the activity and stability of these electrodes. (authors)

International Nuclear Information System (INIS)

A revision of some basic concepts related to the analysis of variance of repeated measures is presented within an ecological context topics such as the types of experiments in which the technique is applicable, the hypotheses of interest, and its preference over other traditional techniques such as regression and conventional analysis of variance, are discussed. As an example, the technique was successfully applied to an experiment carried out at Cienaga Grande de Santa Marta, Colombia, in which the concentration of cadmium #mu#g/g in leaves of the black mangrove Avicennia germinans was measured in several monitoring stations and throughout several sampling intervals representing seasons.

International Nuclear Information System (INIS)

The adsorption properties of four samples of the #alpha#-modification of boron nitride (#alpha#-BN) were investigated by the gas-chromatographic method. According to the electron microscopy data, the #alpha#-BN particles possess the shape of thin plates. An #alpha#-BN sample prepared from magnesium polyboride, is the most uniform adsorbent. For a series of n-alkanes, benzene, and alkyl benzenes, by testing the #alpha#-BN samples one has obtained the retained volumes (Henry constants) and the values of the differential adsorption heat, which are close to those of the surface zero filling. These thermodynamic characteristics of adsorption have shown that the #alpha#-BN, line the graphitized thermal carbon black, is not a specific adsorbent.

International Nuclear Information System (INIS)

In the framework of nuclear waste transmutation studies, the Mini-INCA project has been initiated at CEA/DSM with objectives to determine optimal conditions for transmutation and incineration of minor actinides (MA) in high intensity neutron fluxes. Our experimental tools based on alpha- and gamma-spectroscopy of the samples and the development of micro fission chambers could gather either microscopic information on nuclear reactions (total or partial cross sections for neutron capture and/or fission reactions) or macroscopic information on transmutation and incineration potentials. Neutron capture cross sections of selected actinides ("2"4"1Am, "2"4"2Am, "2"4"2Pu, "2"3"7Np) have already been measured at ILL, showing some discrepancies when compared to evaluated data libraries but in overall good agreement with recent data. The studies and possibilities offer by the MEGAPIE project to assess neutronic performances of a 1 MW spallation target and the incineration of ...

Energy Technology Data Exchange (ETDEWEB)

In this work, a comprehensive model including heat transfer, fluid flow and solidification was used to evaluate the performance of a novel delivery system for a single-belt steel casting process. This near-net-shape casting, although still in development, is one of the most promising routes for casting of low-carbon steel in large scale. This paper focuses on the performance of a low-Re {kappa}-{epsilon} model that was employed to simulate the three-dimensional turbulent flows fully-coupled with heat transfer and macroscopic solidification. Simulations were run for the intended conditions of caster operation, and the results obtained with the {kappa}-{epsilon} were compared with the results obtained with an ad hoc viscosity model, where the molecular viscosity was boosted 100 times, uniformly throughout the computational domain. A semi-analytical solution was employed for validating the models and the results showed that the ad hoc viscosity model overestimated the ...

International Nuclear Information System (INIS)

Silicon nitride-based ceramics behavior is strongly influenced by microstructural parameters, which, in turn are determined by chosen densification method. Highly covalent Si-N bond hind are the silicon nitride densification. Therefore, metal oxides are used in order to get high density. However, such oxides must be carefully selected, because they affect the general macroscopic properties of sintered bodies. In the present work, the viability of rare earth concentrate use to produce #beta#--Si_6_-_xAl_xO_xN_8_-_x and its effect on mechanical properties of the sintering ceramics are studied. Additive composition, heating rate, soaking time and sintering temperature were took as variables. Hardness, fracture toughness, Young's modulus and flexural strength were investigated. Lattice parameter compositional dependence and secondary phases crystallized after past-sintering heat treatment were also determined. The results show that rare earth concentrate works very ...

International Nuclear Information System (INIS)

A calculation program (URA 6.F4) was elaborated on FORTRAN IV language, that through finite differences solves the unidimensional scalar Helmholtz equation, assuming only one energy group, in spherical cylindrical or plane geometry. The purpose is the determination of the flow distribution in a reactor of spherical cylindrical or plane geometry and the critical dimensions. Feeding as entrance datas to the program the geometry, diffusion coefficients and macroscopic transversals cross sections of absorption and fission for each region. The differential diffusion equation is converted with its boundary conditions, to one system of homogeneous algebraic linear equations using the box integration technique. The investigation on criticality is converted then in a succession of eigenvalue problems for the critical eigenvalue. In general, only is necessary to solve the first eigenvalue and its corresponding eigenvector, employing the power method. The obtained results by ...

International Nuclear Information System (INIS)

This introductory text treats thermodynamics as an incomplete description of quantum systems with many degrees of freedom. Its main goal is to show that the approach to equilibrium -with equilibrium characterized by maximum ignorance about the open system of interest- neither requires that many particles nor is the precise way of partitioning, relevant for the salient features of equilibrium and equilibration. Furthermore, the text depicts that it is indeed quantum effects that are at work in bringing about thermodynamic behavior of modest-sized open systems, thus making Von Neumann's concept of entropy appear much more widely useful than sometimes feared, far beyond truly macroscopic systems in equilibrium. This significantly revised and expanded second edition pays more attention to the growing number of applications, especially non-equilibrium phenomena and thermodynamic processes of the nano-domain. In addition, to improve readability and reduce unneeded ...

Science.gov (United States)

The macroscopic rotation of plasma in a toroidal containment device is an important feature of the equilibrium. Toroidal and polidal rotation in the high-beta tokamak Torus II is measured experimentally by examining the Doppler shift of the 4685.75 A He II line emitted from the plasma. The toroidal flow at an average velocity of 1.6 x 10/sup 6/ cm/sec, a small fraction of the ion thermal speed, moves in the same direction as the toroidal-plasma current. The poloidal flow follows the ion diamagnetic current direction, also at an average speed of 1.6 x 10/sup 6/ cm/sec. In view of certain ordering parameters, the toroidal flow is compared with predictions from neoclassical theory in the collisional, Pfirsch-Schluter regime. The poloidal motion, however, results from an E x B drift in a positive radial electric field, approaching a stable ambipolar state. This radial electric field is determined from theory by using the measured poloidal velocity. Mechanisms for the ...

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 ...

Energy Technology Data Exchange (ETDEWEB)

An axisymmetric unit cell model based on a regular array of second-phase particles arranged on a BCC lattice is used to study deformation mechanisms of ferrite-pearlite structural steels. Microstructural characteristics of the steels were parameterized by the pearlite volume fraction, the aspect ratio of the pearlite particles, and the neighboring factor, which represents the ratio of interparticle spacing in the longitudinal direction to that in the transverse direction. FE analyses were carried out to investigate the macroscopic and microscopic response of unit cells with morphological features based on idealizations of the microstructures of the actual steels. Tensile properties of each constituent phase were obtained experimentally and used in the analyses. As compared to traditional axisymmetric models, the BCC tell model appears to be able to capture more realistically the behavior of the materials, and it accurately estimates the tensile behavior of the ...

CERN Document Server

Calcium (Ca) plays an important role in regulating various cellular processes. In a variety of cell types, Ca signaling occurs within microdomains where channels deliver localized pulses of Ca which activate a nearby collection of Ca-sensitive receptors. The small number of channels involved ensures that the signaling process is stochastic. The aggregate response of several thousand of these microdomains yields a whole-cell response which dictates the cell behavior. Here, we study analytically the statistical properties of a population of these microdomains in response to a trigger signal. We apply these results to understand the relationship between Ca influx and Ca release in cardiac cells. In this context, we use a first passage time approach to show analytically how Ca release in the whole cell depends on the single channel kinetics of Ca channels and the properties of microdomains. Using these results, we explain the underlying mechanism for the graded relationship between Ca ...

Energy Technology Data Exchange (ETDEWEB)

Under severe operating conditions, such as starved lubrication, performance, service life, and reliability of rolling element bearings depend on the chemical and physical interactions between the contacting surfaces, the lubricant components, and the atmosphere. The IMKT{sup 1}, PI{sup 2}, and the imt{sup 3} have been cooperating on systematic investigations of interfacial interactions in high speed grease lubricated ball bearings. These include long time tests with complete bearings lubricated with greases of different composition under defined operating conditions, conducted at the IMKT, and chemical and physical characterizations of the running surfaces at the PI and imt. At the PI, in particular the chemical nature of the boundary layers has been investigated with time of flight secondary ion mass spectrometry (TOF-SIMS). The imt has been involved in the investigations by measuring the physical/mechanical properties of interacting surfaces at the micro/nano-scale after the removal ...

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 the Navier-Stokes ...

Energy Technology Data Exchange (ETDEWEB)

Soil contamination by liquid organic pollutants represents a serious threat to phreatic ground water. These organic liquids get into the ground and migrate through the porous medium until they finally reach the aquifer. After a critical study of the literature, we listed various existing multiple displacements under three-phase conditions of a disconnected polluting phase that may or not spread over water. The aim of this thesis is to model (at pore scale level) and integrate in the pore network model the various flows that occur when three phases (gas, pollutant and air) are present in a porous medium. The porous medium is supposed completely water-wet. The polluting phase may be connected or not, and the spreading coefficient of the pollutant over water may either be positive or negative. The goal of our study is to obtain macroscopic parameters such as relative permeabilities and capillary pressure. These parameters can be then incorporated in a larger-scale ...

Energy Technology Data Exchange (ETDEWEB)

Neutron radiography has been put to practical use in foreign countries as one of nondestructive inspection technologies, but in Japan, its application to other scientific fields is mainly researched. The reason is, the neutron radiography apparatuses installed in Japan are hard to be industrially utilized for a number of reasons, but also the characteristics of neutron radiography are not clearly established, and it is not standardized. The part from a collimator through an object to a detector is called ``upstream``, the part of an image detector is called ``midstream``, and the part of image processing is called ``downstream``. The nonparallel property of beam, image distortion and the lack of sharpness, beam quality and the interaction of neutron beam with an object are discussed about the upstream. The intensity of neutron beam, the energy spectra, the effective total macroscopic cross section, the effective energy, the evaluation of scattered beam and ...

Energy Technology Data Exchange (ETDEWEB)

Deformation mechanisms of Mg-Al-Zn (AZ31) alloys were investigated by performing tensile test at room temperature. In fine grain Mg alloys deformed at room temperature, nonbasal slip systems were found to be active as well as basal slip systems because of grain-boundary compatibility effect. Slip-induced grain-boundary sliding occurred as a complementary deformation mechanism to give rise to c-axis component of strain. With increasing grain size, the activation of the nonbasal slip systems was limited near grain boundaries. Instead of grain-boundary sliding, twinning occurred as a complementary deformation mechanism in large grained samples. Orientation analysis of twins indicated that twinning is induced by stress concentration due to the pile up of basal dislocations. The grain-size dependence on deformation mechanism was found to affect yielding behavior both microscopically and macroscopically which can influence various mechanical properties such as fatigue ...

Energy Technology Data Exchange (ETDEWEB)

From a macroscopic point of view, corrosion of Zn alloy coated steel sheet occurs by the coating preceding corrosion mechanism; microscopically, however, the coated layer corrosion velocity in the tip of corrosion is different. In order to find the main factors of under-film corrosion of Zn and Zn-Fe alloy coatings in the salt water spray atmospheric exposure test, the correlation between point inflation-exfoliation width and chlorine penetration behavior, point adhesion, and the difference in chlorine penetration behavior due to alloy coating components were investigated. Consequently, the following results were obtained: 1. The better correlation was observed between chlorine penetration distance and point inflation-point exfoliation width. 2. The durability of coating against chlorine penetration improved by increase in point adhesion and Zn content in the coating layer. 3. Zn-Fe (10-20%) alloy coating showed better durability against chlorine penetration than ...

Energy Technology Data Exchange (ETDEWEB)

The possibility of improving the cold formability of wrought magnesium alloys is considered in light of their good hot forming characteristics. Magnesium alloy AZ31B sheet is selected as a model system. Parameters affecting formability, such as strain hardening rate, strain rate sensitivity, and the degree of anisotropy are examined systematically by conducting tensile tests over a range of temperatures (room temperature to 250 C) and strain rates (1 x 10{sup -5} to 0.1 s{sup -1}). The plastic anisotropy and deformation texture evolution are examined in samples aligned with the sheet rolling and transverse directions. Polycrystal plasticity simulations using a viscoplastic self-consistent (VPSC) formulation are used to model the observed anisotropy and texture evolution. The adjustable parameters in the model are the relative critical resolved shear stresses of the dislocation mechanisms known to operate within magnesium. The experimental results suggest that an increased strain rate ...