Energy Technology Data Exchange (ETDEWEB)

It is shown numerically that on a time scale of order 1 msec a neutron star with pion condensation will undergo separation into a core and an envelope with a sharp interface. The envelope will not, however, be ejected.

Energy Technology Data Exchange (ETDEWEB)

No abstract prepared.

International Nuclear Information System (INIS)

On all steam turbines operating with condensation the air leakage penetrating from the part of the plant which is under vacuum must be eliminated, in order to maintain the vacuum created by physical conditions. In order to attain effective air bleed-off, the water-steam-air mixture is conveyed via the super-cooling bundles in the condenser. In this way the steam partial pressure decreases and the air partial pressure increases at a constant condenser pressure. In this procedure the mixture is supercooled by about 4"0C compared with the saturate steam temperature appertaining to the condenser pressure. The values of volume of air leakage are the result of a year's experience on existing plant. (orig.).

CERN Document Server

The X-ray spectra of some magnetized isolated neutron stars (NSs) show absorption features with equivalent widths (EWs) of 50 - 200 eV, whose nature is not yet well known. To explain the prominent absorption features in the soft X-ray spectra of the highly magnetized (B ~ 10^{14} G) X-ray dim isolated NSs (XDINSs), we theoretically investigate different NS local surface models, including naked condensed iron surfaces and partially ionized hydrogen model atmospheres, with semi-infinite and thin atmospheres above the condensed surface. We also developed a code for computing light curves and integral emergent spectra of magnetized neutron stars with various temperature and magnetic field distributions over the NS surface. We compare the general properties of the computed and observed light curves and integral spectra for XDINS RBS\\,1223 and conclude that the observations can be explained by a thin ...

British Library Electronic Table of Contents (United Kingdom)

By assuming that not only counter-ions but DNA molecules as well are thermally distributed according to a Boltzmann law, we propose a modified Poisson-Boltzmann equation, at the classical level, as a starting point to compute the effects of quantum fluctuations of the electric field on the interaction among DNA-cation complexes. The latter are modeled here as infinite one-dimensional wires (?-functions). Our goal is to single out such quantum-vacuum-driven interaction from the counterion-induced and water-related interactions. We obtain a universal, frustration-free Casimir-like (codimension 2) interaction that extensive numerical analysis show to be a good candidate to explain the formation and stability of DNA aggregates. Such Casimir energy is computed for a variety of configurations of...

CERN Document Server

Bose-Einstein condensation in nonlinear system

International Nuclear Information System (INIS)

We construct a phenomenological model which describes the dynamical chiral symmetry breaking (DCSB) of a QCD vacuum and reproduces meson spectra. Quark condensates, the pion decay constant, and meson spectra are well reproduced by the phenomenological interaction which consists of a linear confining potential, a Coulombic potential, and the close-quote t Hooft determinant interaction. In this model, the close-quote t Hooft determinant interaction plays an important role to not only the mass difference between the #eta# and #eta#"' mesons, but other meson masses through DCSB. copyright 1997 The American Physical Society.

CERN Document Server

In studying the dynamics of large N_c SU(N_c) gauge theory with fundamental quark flavours in the quenched approximation, we observe a novel phase transition at finite temperature. A quark condensate forms at finite quark mass, and the value of the condensate varies smoothly with the quark mass for generic region in parameter space. At a particular value of the quark mass, there is a finite discontinuity in the condensate's vacuum expectation value, corresponding to a first order phase transition. We study this using holography, the string dual being the geometry of N_c D3--branes at finite temperature, AdS_5-Schwarzschild times S^5, probed by a D7-brane. The D7-brane has topology R^4 times S^3 times S^1, and allowed solutions correspond to either the S^3 or the S^1 shrinking away in the interior of the geometry. The phase transition represents a jump between branches of solutions having these two ...

Energy Technology Data Exchange (ETDEWEB)

No abstract prepared.

Science.gov (United States)

Binary Star Evolution. The evolution of close binary stars can be very different from that of wide binaries of isolated stars. If the stars are close enough ...

Science.gov (United States)

Another difference lies in the speed of star evolution. 2. Computation of Stellar Structure and Their Evolution. The structure of stars at certain instants ...

Science.gov (United States)

The evolution of massive stars through hydrogen and helium burning is addressed. A set of stellar

International Nuclear Information System (INIS)

We present and characterize an experimental system in which we achieve the integration of an ultrahigh finesse optical cavity with a Bose-Einstein condensate (BEC). The conceptually novel design of the apparatus for the production of BECs features nested vacuum chambers and an in vacuo magnetic transport configuration. It grants large scale spatial access to the BEC for samples and probes via a modular and exchangeable ''science platform.'' We are able to produce 87Rb condensates of 5x106 atoms and to output couple continuous atom lasers. The cavity is mounted on the science platform on top of a vibration isolation system. The optical cavity works in the strong coupling regime of cavity quantum electrodynamics and serves as a quantum optical detector for single atoms. This system enables us to study atom optics on a single particle level and to further develop the field of quantum atom optics. We describe the technological ...

Science.gov (United States)

star formation. To either side of the center, a small bar of dust and gas is helping to fuel the new stars. NASA's Jet Propulsion Laboratory, Pasadena, Calif., manages the...

Science.gov (United States)

... each star goes. The results of (1) are compared with predictions based on (2) and on single star evolution theory to discover the various stages which occur. ...

Energy Technology Data Exchange (ETDEWEB)

We present photoelectric BVRI photometry for 16 T Tau and related stars in the Rho Oph dark cloud, as well as vidicon spectroscopic observations for nine stars. The color excesses of these stars favor circumstellar dust shells as the source of the observed infrared excesses.

Energy Technology Data Exchange (ETDEWEB)

The present review focuses on the isotropic composition in extra-terrestrial materials. There are many different factors in the variation in isotopic abundance between terrestrial and extra-terrestrial materials. Major factors in unusual isotopic composition are roughly grouped into three categories: factors associated with fractionation of isotopes, nuclear reaction or radioactive disintegration. Fractionation takes place due to differences in mass among various isotopes. There are physical and chemical factors. Physical ones include vaporization and condensation which meteorites may experience during their formation while the chemical ones include chemical reactions and chemical equilibration. There phenomena are mentioned as factors in the variation in isotopic ratio which is associated with nuclear reactions. An important nuclear reaction is the formation of elements that has been occurring continuously in stars since the big bang. The ...

Science.gov (United States)

Binary Star Evolution. Stars in binary systems evolve individually and together. " individually: evolution follows normal progression based on ...

Energy Technology Data Exchange (ETDEWEB)

In the synthesis of the peptidyl-polymer corresponding to the sequence (57-100) of the ..beta.. chain of human hemoglobin on Teflon with radiationally grafted polystyrene a comparative study was made of different methods of fragment condensation. It was shown that the most effective methods are azide condensation and condensation with the use of complex F.

Energy Technology Data Exchange (ETDEWEB)

Asymptotic giant branch stars are red supergiant stars of low-to-intermediate mass. This class of stars is of particular interest because many of these stars can have nuclear processed material brought up repeatedly from the deep interior to the surface where it can be observed. A review of recent theoretical and observational work on stars undergoing the asymptotic giant branch phase is presented. 41 refs.

Energy Technology Data Exchange (ETDEWEB)

The development of KNGR (Korean Next Generation Reactor) is now in progress. KAERI is developing KNGR which is a advanced active PWR (pressurized water reactor) and 1350 MW electric capacities and is by based on UCN(Ulchin) 3 and 4 nuclear power plant which is a Korean standard PWR. In this report, the PZR (pressurizer) and Related System Design Features for KNGR which include PZR volume, PPCS (pressurizer safety valve)were analyzed. First, the Design Parameters between KNGR compared to UCH 3 and 4 were compared, and second, advanced design features of KNGR compared to UCN 3 and 4 were analyzed. After the present analysis, it has been concluded that the safety margins for the PZR level and pressure of KNGR were more increased by the larger PZR volume than those of UCN 3 and 4, for PZR minimum water level at reactor/turbine trip and PZR maximum pressure at LOCV(loss of condenser vacuum) of KNGR were higher and lower, respectively than those of ...

International Nuclear Information System (INIS)

Single pellets (of approximately 70 g each) of irradiated lithium aluminate target from N-Reactor test PT-57 were used in a series of experiments to determine the extent to which the product tritium can be recovered by (a) vacuum outgassing of the target (thermal extraction-TX) and (b) in-vacuo chemical dissolution of the target in molten sodium tetraborate (flux extraction-FX). Five TX runs and seven FX runs were made. Thirty-five percent of the tritium was recovered in a form non-condensable at -196"0C. The remainder was recovered in a condensable form (as T_2O, HTO, etc.). Post-extraction analysis of the melt from the seven flux extractions showed that a maximum of 2 percent of the original amount of tritium remained and that target dissolution was essentially complete in 12 hours. Flux extraction of two pellets which had been subjected to thermal extraction showed less than 0.4 percent of the original amount of tritium ...

CERN Document Server

The galaxies of the Local Group that are currently forming stars can serve as our laboratories for understanding star formation and the evolution of massive stars. In this talk I will summarize what I think we've learned about these topics over the past few decades of research, and briefly mention what I think needs to happen next.

Energy Technology Data Exchange (ETDEWEB)

This paper is concerned with the development and application of an analytical method for the performance prediction of air cooled condensers. A local analysis is employed in which the condenser is considered as a matrix of small basic heat transfer modules. For each element, local film coefficients for both the air and the condensing fluid are determined according to the existing local conditions, including the two-phase flow regime. The paper considers an application of the method to heat pump condensing.

CERN Document Server

If B is a compact space and B\\{pt} is Lindelof then B^k\\{pt} is star-Linedlof for every cardinality k. If B\\{pt} is compact then B^k\\{pt} is discretely star-Lindelof. In particular, this gives new examples of Tychonoff discretely star-Lindelof spaces with unlimited extent.

Energy Technology Data Exchange (ETDEWEB)

Research on Be stars from the early work of Merrill and Struve to the present is reviewed, including recent observations from space. A number of models which have been proposed to explain the Be phenomenon are discussed, and the evolutionary status of Be stars is considered. 126 references.

Science.gov (United States)

single star evolution. To understand the evolution of massive stars and their role in shaping the galaxy, understanding of the distribution of ...

Energy Technology Data Exchange (ETDEWEB)

The Nobel lecture of Chandrasekhar is printed in which he describes the basic processes that determine the life history of a star with particular emphasis on the roles of stellar mass and radiation pressure. (AIP)

Science.gov (United States)

A SCENARIO FOR CARBON STAR EVOLUTION WILLEMS, F., DE JONG, T. 213> 821111 INFRARED OBSERVATIONS OF OH/IR STARS WILLIAMS, D. M., BOYLE, ...

Science.gov (United States)

Form as the end result of massive star evolution; Type II supernova: collapse of iron core in highly evolved massive star; outer regions blasted away in ...

Science.gov (United States)

These include, but are not limited to: stellar winds and outflows, post-main- sequence star evolution, binary star evolution, globular cluster structure and ...

Energy Technology Data Exchange (ETDEWEB)

Observation of lithium lines in two halo stars could bring some information about /sup 7/Li abundance at the time of the formation of the galaxy.

Science.gov (United States)

and the implications for massive star evolution. In recent years, the complex nature of the circumstellar regions of evolved massive stars has become apparent. ...

Science.gov (United States)

Apr 23, 2009 ... Wolf-Rayet stars have over 20 times the mass of the Sun and are thought to be in a brief, pre-supernova phase of massive star evolution. ...

International Nuclear Information System (INIS)

The neutron star parameters in the model extended by the inclusion of #delta# meson and additional nonlinear vector meson interactions are studied.

Science.gov (United States)

for massive star evolution, or they could all be very blue super- giant stars experiencing A , = 1-1.5 mag. The fact that the en- ...

Energy Technology Data Exchange (ETDEWEB)

Compact heat exchangers are being increasingly considered for condensation applications in the process, cryogenic, aerospace, power and refrigeration industries. In this paper, different configurations available for condensation applications are analyzed and the current state-of-the-knowledge for the design of compact condensers is evaluated. The key technical issues for the design and development of compact heat exchangers for condensation applications are analyzed and major advantages are identified. The experimental data and performance prediction methods reported in the literature are analyzed to evaluate the present design capabilities for different compact heat-exchanger configurations. The design flexibility is evaluated for the development of new condensation applications, including integration with other process equipment.

Science.gov (United States)

Fluid dynamic design criteria for mercury condenser-subcooler component for sunflower power conversion system

Energy Technology Data Exchange (ETDEWEB)

Hamiltonian light-front dynamics of quantum fields may provide a useful approach to systematic nonperturbative approximations to quantum field theories. The authors investigate inequivalent Hilbert-space representations of the light-front field algebra in which the stability group of the light front is implemented by unitary transformations. The Hilbert space representation of states is generated by the operator algebra from the vacuum state. There is a large class of vacuum states besides the Fock vacuum which meets all the invariance requirements. The light-front Hamiltonian must annihilate the vacuum and have a positive spectrum. Relations are exhibited of the Hamiltonian to the nontrivial vacuum structure. 30 refs.

International Nuclear Information System (INIS)

It is shown that vacuum instabilities possibly arising because of tachyons do not contradict any experimental evidence, and therefore that no objection against tachyon existence can be found even on this ground. (Auth.).

International Nuclear Information System (INIS)

Results of UBVRI observations of 127 stars in the field of Tauri dark clouds are presented. The distance of these clouds is 132+-10 pc. The reddening law in direction of the clouds is close to the normal one. The stars associated with the clouds have been picked out. The space density of these stars is several times higher than that in the Sun neighbourhood.

Science.gov (United States)

The thermal evolution predicted by current models of the superfluid-crust interaction is noted to

Energy Technology Data Exchange (ETDEWEB)

For most of the history of binary star astronomy, systems have been classified largely on the basis of how they were discovered and qualitative appearance of their spectra and light curves. Present understanding of single and double star evolution has now progressed to the point where most of the classes previously identified, and some new ones, can be arranged into evolutionary sequences, depending primarily on the initial masses and separation of the component stars.

Energy Technology Data Exchange (ETDEWEB)

A work on the world of astrophysics primarily for lay readers. The author writes only about the discoveries he ''experienced'' during the past 25 years (before 1979). Illustrated somewhat in color plus a set of superb colar plates. Contents, abridged: The long life of stars. The life story of the sun. The life story of massive stars. The end of stars. How stars are born. Planets and their inhabitants.

International Nuclear Information System (INIS)

Thermodynamic consideration and process calculations at equilibrium conditions showed that processes for separating gas mixtures by partial condensation at low temperatures using turboexpanders have got less energy losses than processes with quasi isobar partial condensation. Compared to the low-pressure parts of condensing steam turbines in turboexpanders less erosion problems are to expected for such separating processes. Separation of liquid in the machine, however, is more difficult withouf additional measures. (orig.).

KoreaScience (Korea)

Full Text Available

International Science & Technology Center (ISTC)

Production of High-Purity (>99.99% wt.) Condensed Beryllium

International Nuclear Information System (INIS)

In spite of extensive cooling water studies premature damage due to corrosion occurred on the CuZn20Al condenser tubes. It was then decided to incorporate new titanium-tubed condensers during the annual overhauls of 1983 and 1985 and also take ameliorating measures up to the exchange of individual condensers. (orig.).

CERN Document Server

We numerically investigate whether and how gaseous ejecta from AGB stars can be converted into new stars within originally massive star clusters (MSCs) in order to understand the origin of multiple stellar populations in globular clusters (GCs). We adopt a scenario in which (i) MSCs with masses of M_s can be formed from high-mass, high-density giant molecular clouds (GMCs) in their host galactic building blocks embedded in dark matter halos at high redshifts and (ii) their evolution therefore can be significantly influenced by M_s, their initial locations, and physical properties of their hosts. Our 3D hydrodynamical simulations show that gaseous ejecta from AGB stars can be retained within MSCs and consequently converted into new stars very efficiently in the central regions of MSCs, only if M_s exceed a threshold mass (M_th) of ~10^6 M_sun. The new stars can ...

CERN Document Server

We highlight the role of the light elements (Li, Be, B) in the evolution of massive single and binary stars, which is largely restricted to a diagnostic value, and foremost so for the element boron. However, we show that the boron surface abundance in massive early type stars contains key information about their foregoing evolution which is not obtainable otherwise. In particular, it allows to constrain internal mixing processes and potential previous mass transfer event for binary stars (even if the companion has disappeared). It may also help solving the mystery of the slowly rotating nitrogen-rich massive main sequence stars.

Science.gov (United States)

The first quarter 1982 report summarizes the operating and test data obtained at the six ton per day Advanced Coal Liquefaction Research and Development Facility in Wilsonville, Alabama. The Wilsonville R and D Facility was in operation 52% of the period with scheduled shutdowns accounting for 33% of the downtime. Illinois 6 coal from the Burning Star No. 2 mine was processed during Run 236. The three process units of the Wilsonville facility were operated in a non-integrated mode to evaluate process parameters and to test equipment and operating modifications. Data were obtained in the following areas: In the SRC Unit: operation at low severity reaction conditions for single stage liquefaction with a high LSRC recycle rate using Illinois 6 coal; process solvent activity control; and preliminary feeding tests with hydrotreated SRC as a replacement for LSRC in the process solvent. In the CSD Unit: operation with T102 Vacuum Column bottoms ...

Energy Technology Data Exchange (ETDEWEB)

With an objective to know coal condensation structure which has influence on coal conversion reaction, an attempt was made on quantitative evaluation of hydrogen bonding in coal. Using as test samples the VDC made from Taiheiyo coal swollen by tetralin and vacuum-dried, and its pyrolyzed char, DSC measurement and Fourier transform infrared spectroscopy (FT) were performed. An FT spectrum comparison revealed that the VDC swollen at 220{degree}C has the hydrogen bonding relaxed partly from the original coal. However, since the change is in a huge coal molecular structure restraining space, it has stopped at relaxation of the bonding energy without causing separation as far as free radicals. On the other hand, the DSC curve shows that the VDC has slower endothermic velocity than the original coal. In other words, the difference in heat absorption amounts in both materials is equivalent to the difference of enthalpy ({Delta} H) of both materials, ...

Energy Technology Data Exchange (ETDEWEB)

No abstract prepared.

International Nuclear Information System (INIS)

Purpose: To enable the use of a vacuum container under a relatively high temperature or a high level radioactive dose. Constitution: Vacuum sealing materials for use in a vacuum container are made of resins such as polyimide and polyamide. The sealing materials are joined to the both surfaces of a plate-like insulator by means of adhesives or sealants, or the sealing materials are joined between two plate-like insulators by means of adhesives or sealants. They are situated within grooves of both of flanges, which are clamped tightly by insulation bolt and nut. Since the vacuum sealing materials are joined to the insulator by means of the adhesives or sealants, the reliability of the vacuum sealing can be improved without impairing the electrical insulation. The resin of the vacuum sealing material can be used for the radiation dose up to 10"8 rad, temperature up ...

Energy Technology Data Exchange (ETDEWEB)

The vacuum system of the XVTS (X-Ray Vacuum Transport System) for the LCLS (Linac Coherent Light Source) XTOD (X-ray Transport, Optics and Diagnostics) system has been analyzed and configured by the Lawrence Livermore National Laboratory's NTED (New Technologies Engineering Division) as requested by the SLAC/LCLS program. The system layout, detailed analyses and selection of the vacuum components for the XTOD tunnel section are presented in this preliminary design report. The vacuum system was analyzed and optimized using a coupled gas load balance model of sub-volumes of the components to be evacuated. Also included are the plans for procurement, mechanical integration, and the cost estimates.

British Library Electronic Table of Contents (United Kingdom)

ABSTRACT New observations from the Hubble Ultra Deep Field suggest that the star formation rate at Formula Not Shown drops off faster than previously thought. Using a newly determined star formation rate for the normal mode of Population II/I (PopII/I) stars, including this new constraint, we compute the Thomson scattering optical depth and find a result that is marginally consistent with Wilkinson Microwave Anisotropy Probe 5 results. We also reconsider the role of Population III (PopIII) stars in light of cosmological and stellar evolution constraints. While this input may be needed for reionization, we show that it is essential in order to account for cosmic chemical evolution in the early universe. We investigate the consequences of PopIII stars on the local metallicity distribution fu...

Energy Technology Data Exchange (ETDEWEB)

Comparative studies of flocculent and grand-design spirals suggest that density waves are not the predominant trigger of star formation in most galaxies. Implications for chemical evolution are profound. It may be possible to ignore the details of the spiral-wave phenomenon in research aimed at unifying the chemical properties of spiral disks. 16 references.

Energy Technology Data Exchange (ETDEWEB)

A study of the joint evolution of the normal- and neutron-star components of massive binaries opens with a classification scheme and the analytic expressions to be applied in Paper II for computer simulation of the observable properties of such systems.

Science.gov (United States)

Neutron Star Evolution with Internal Energy h'q/>a. Dissipation by Vortex Creep. N. Shibazaki and F. K. Lamb. University of Illinois at Urbana-Champaign ...

Energy Technology Data Exchange (ETDEWEB)

Observational work on quasars, galaxies, and stars is summarized. Theoretical studies covering stars and stellar evolution, galaxies, clusters and cosmology, high energy astrophysics the solar system and the Sun are described. (ESA)

Energy Technology Data Exchange (ETDEWEB)

A large majority of stars and their lines are white dwarfs, the ultimate stellar stage whose structure and properties still fascinate astrophysicists.

Science.gov (United States)

This is a study done in collaboration with Deidre Hunter at Lowell Observatory studying star formation in two luminous spiral galaxies NGC 801 and UGC 2885. We used ultra-deep H? images taken at the KPNO 2.1 m telescope. We compare these data to stellar images at various wavelengths and to HI maps to determine the extent of star formation activity into the outer disk in these galaxies and its relationship to the gas and older stars. TW is grateful for an REU internship during the summer of 2010 at Northern Arizona University, funded by NSF through grant AST-1004107.

CERN Document Server

The nature of the first generation of stars in the Universe remains largely unknown. Observations imply the existence of massive primordial stars early in the history of the universe, and the standard theory for the growth of cosmic structure predicts that structures grow hierarchically through gravitational instability. We have developed an ab initio computer simulation of the formation of primordial stars that follows the relevant atomic and molecular processes in a primordial gas in an expanding universe. The results show that primeval density fluctuations left over from the Big Bang can drive the formation of a tiny protostar with a mass of just one percent that of the sun. The protostar is a seed for the subsequent formation of a massive primordial star.

International Nuclear Information System (INIS)

Attention is given to the folowing topics: population I and II variable stars; LP variables, the sun, and mass determination; and predegenerate and degenerate variables. Particular papers are presented on alternative evolutionary approaches to the absolute magnitude of the RR Lyrae variables; the evolution of the Cepheid stars; nonradial pulsations in rapidly rotating Delta Scuti stars; dynamical models of dust shells around Mira variables; and pulsations of central stars of planetary nebulae.

Science.gov (United States)

Jun 19, 2008 ... As a result of the May 30 police chase on Redstone Arsenal, ..... Brian Mitchell , the Marshall Center's education and public ...

Science.gov (United States)

... materials science and engineering, condensed-matter or materials physics, solid-state or materials ... include materials theory, condensed-matter and materials physics, solid-state and materials ...

Energy Technology Data Exchange (ETDEWEB)

The properties of strange neutron stars have been studied with the use of the parameter sets stemming from the effective field theory. The impact of the strength of hyperon interactions on neutron star masses has been analyzed. The inclusion of additional nonlinear meson interaction terms together with the strong hyperon-hyperon interaction leads to the existence of additional stable stellar configurations. (authors)

Energy Technology Data Exchange (ETDEWEB)

We demonstrate the nonuniqueness of the basic assumptions leading to spiral structure in self-propagating star formation models. Even in the case where star formation occurs purely spontaneously and does not propagate, we have generated spiral structure by adopting the radically different assumption where star formation is systematically inhibited.

International Nuclear Information System (INIS)

Recent developments in the knowledge of Delta Scuti stars in relation to stellar evolution are reviewed. The stability of periods and amplitudes is examined, and a working hypothesis suggested. Furthermore, the systematics of the observed long-term period changes are compared with the computed evolutionary tracks, suggesting a severe disagreement for the evolved stars if the period changes are caused by radius changes resulting from stellar evolution. 30 refs.

Energy Technology Data Exchange (ETDEWEB)

The author presents his impressions of the conference - that is - major lessons as presented in the talks on nonlinearities and their role in condensed matter physics. (WRF)

Science.gov (United States)

... The performance at reduced condenser water temper- atures was assumed to be the same as that of the single-effect unit. ...

Energy Technology Data Exchange (ETDEWEB)

A correlation was developed for laminar film condensation on vertical fluted surfaces. The theoretical analysis of Panchal and Bell was used for defining important physical property groups. The experimental data of Combs et al. were used to validate the proposed correlation. The experimental database used in the present study included four flute geometries that could be approximated to cosine-type flutes and seven fluids. The resulting correlation can predict the average condensate heat transfer coefficient within {+-}20%.

International Nuclear Information System (INIS)

Corrosion resistance of Cu-W system condensates in tap water was studies. It is shown that with an increase in W concentration in the condensates of the Cu-W system their corrosion in tap water enhances. In the material designated for power supply facilities the optimal tungsten content is up to 6%. Owing to formation of oxide film on the surface of the samples corrosion is stabilitized 40 h after the test start.

International Nuclear Information System (INIS)

Purpose: To ensure continuous operation for condensate desalters with the control device for desalter group in a nuclear power plant by automatically averaging the operation interval between each of the desalters. Constitution: Electroconduction meters are provided at the inlet and the outlet for each of the desalters. The conduction rates at the inlet and outlet are compared to determine the re-generation timing of the condensate desalter. Limiting set value for each of the equipments in the cleanup systems is changed by using a mathematical operation circuit to average the operation interval between each of the desalters. (Ikeda, J.).

Science.gov (United States)

... Accession Number : ADD141533. Title : Yttrium Oxides in Vacuum-Plasma- Sprayed CoNiCrAlY Coatings,. Descriptive Note : Journal Article,. ...

British Library Electronic Table of Contents (United Kingdom)

Abstract We analyse extinction maps of nearby giant molecular clouds to forge a link between driving processes of turbulence and modes of star formation. Our investigation focuses on cloud structure in the column density range above the self-shielding threshold of 1-mag AV and below the star formation threshold - the regime in which turbulence is expected to dominate. We identify clouds with shallow mass distributions as cluster forming. Clouds that form stars in a less clustered or isolated mode show a steeper mass distribution. Structure functions prove inadequate to distinguish between clouds of different star formation mode. They may, however, suggest that the turbulence in the average cloud is governed by solenoidal forcing. The same is found using the -variance analysis which also in...

Energy Technology Data Exchange (ETDEWEB)

In this paper the basic properties of non-rotating and slowly rotating protoneutron stars in the relativistic mean-field approach are discussed. The equation of state is the main input to the structure equations. The TM1 parameter set extended to the finite-temperature case is used to obtain the mass-radius relation for protoneutron stars. The occurrence of unstable branches in the mass-radius relation are presented. This allows for the existence of distinctively different evolution tracks for protoneutron stars. The low-density protoneutron star configurations are estimated. The stable configurations obtained for fixed lepton number Y{sub L}=0.4 are compared with those obtained for fixed proton fraction Y{sub P}=0.1776. (author)

Science.gov (United States)

This is the final report of a three-year, Laboratory Directed Research and Development (LDRD) project at the Los Alamos National Laboratory (LANL). The authors investigated the evolution and radiation characteristics of individual neutron stars and stellar systems. The work concentrated on phenomena where new techniques and observations are dramatically enlarging the understanding of stellar phenomena. Part of this project was a study of x-ray and gamma-ray emission from neutron stars and other compact objects. This effort included calculating the thermal x-ray emission from young neutron stars, deriving the radio and gamma-ray emission from active pulsars and modeling intense gamma-ray bursts in distant galaxies. They also measured periodic optical and infrared fluctuations from rotating neutron stars and search for high-energy TeV gamma rays from discrete celestial sources.

International Nuclear Information System (INIS)

The possibility of surface modification of high-speed steel cutting tool by means of vacuum-plasma treatment including ion nitriding in gas plasma followed by the deposition of wear resistant (Ti, Al)N coatings in metal-gas plasma of a vacuum arc discharge is studied. The regularities of nitrided layer formation and the structure of these layers under various operation conditions of cutting tool are investigated. Optimum conditions of vacuum-plasma treatment providing the best wear resistance of cutting are determined

International Science & Technology Center (ISTC)

Development of Method and Technical Project of the Plant for Thermo-Vacuum Desorption of Tritium Oxide (HTO) from the Environmental Samples

International Nuclear Information System (INIS)

The method of an effective potential is used to investigate the possible types of evolution of vacuum shells in the Friedmann-Schwarzschild world. Such shells are assumed to emerge during phase transitions in the early Universe. The possible global geometries are constructed for the Friedmann-Schwarzschild worlds. Approximate solutions to the equation of motion of a vacuum shell have been found. The conditions under which the end result of the evolution of the vacuum shells under consideration is the formation of black holes and wormholes with baby universes inside have been found. The interior of this world can be a closed, flat, or open Friedmann universe.

International Nuclear Information System (INIS)

We present 14 years of contemporaneous photometric and spectroscopic observations of 28 solar analog stars, taken with the Tennessee State University Automatic Photometric Telescopes at Fairborn Observatory and the Solar-Stellar Spectrograph at Lowell Observatory. These are the best observed and most nearly Sun-like of the targets in our magnitude-limited (V #<=# 7.5) sample. The correlations between luminosity and activity reveal the expected inverse activity-brightness correlations for active stars. Strong direct correlations between activity and brightness are not prevalent for the less active solar age stars, but are precision limited. The Sun does not appear to have unusually low photometric variability when compared with the most Sun-like inactive solar analogs. We present evidence that the activity index R'_H_K is not a good discriminant of Maunder Minimum candidate stars. On the basis of a ...

CERN Document Server

We have obtained UBVRI images with the Kitt Peak and Cerro Tololo 4-m telescopes and Mosaic cameras of seven dwarfs in (or near) the Local Group, all of which have known evidence of recent star formation: IC10, NGC 6822, WLM, Sextans B, Sextans A, Pegasus,and Phoenix. We construct color-magnitude diagrams (CMDs) of these systems, as well as neighboring regions that can be used to evaluate the degree of foreground contamination by stars in the Milky Way. Inter-comparison of these CMDs with those of M31, M33, the LMC, and the SMC permits us to determine improved reddening values for a typical OB star found within these galaxies. All of the CMDs reveal a strong or modest number of blue supergiants. All but Pegasus and Phoenix also show the clear presence of red supergiants in the CMD, although IC10 appears to be deficient in these objects given its large WR population. The bright stars of intermediate ...

Energy Technology Data Exchange (ETDEWEB)

It is needless to say that one of the most important roles of the condensate demineralizer in Japanese boiling water reactors (BWR) is to eliminate such impurities during accidental occurrence of sea water leakage from condensate cooling system. Ion exchange resins packed in condensate demineralizer have also been expected to decrease crud, or corrosion products (CP) in condensate water in order to finally reduce activated corrosion products (ACP) in the reactor coolant loop. It is perceived that crud removal ability of a condensate demineralizer has been improved year by year. And we call this phenomenon as `Aging Effect`. Typical property changes of aged cation exchange resin consisted of an increase of water retention capacity and a change of surface texture. Based on these findings, we formulated a new concept and developed new gel type ion exchange resins for the better crud ...

International Nuclear Information System (INIS)

Development of a front end system for a high energy proton accelerator is in progress at Korea Atomic Energy Research Institute (KAERI) for basic science and industrial applications. The proper vacuum components has been installed and operated successfully between ion source and RFQ. The reliable operation of the accelerator has been completed at vacuum system in the high and ultra high vacuum range under operating conditions. Proper control system for the vacuum instruments, based on PC operated by Windows, has been designed and constructed by control group at PAL. As PC operated by windows with inherent instability does not proper, embedded system can be replaced for reliable operation system, such as VME system operated by vxWorks.

Energy Technology Data Exchange (ETDEWEB)

Typical beam lines are comprised of an assembly of vacuum valves and shutters referred to as a ''front end'', optical elements to monochromatize, focus and split the photon beam, and an experimental area where a target sample is placed into the photon beam and data from the interaction is detected and recorded. Windows are used to separate sections of beam lines that are not compatible with storage ring ultra high vacuum. Some experimental beam lines share a common vacuum with storage rings. Sections of beam lines are only allowed to vent up to atmospheric pressure using pure nitrogen gas after a vacuum barrier is established to protect ring vacuum. The front end may only be bled up when there is no current in the machine. This is especially true on the VUV storage ring where for most experiments, windows are not used. For the shorter wavelength, ...

CERN Document Server

A debris disk is a constituent of any planetary system surrounding a main sequence star. We study whether close stellar encounters can disrupt and strip a debris disk of its planetesimals in the expanding open cluster of its birth. Such stripping would affect the dust production and hence detectability of the disk. We tabulated the fractions of planetesimals stripped off during stellar flybys of miss distances between 100 and 1000 AU and for several mass ratios of the central to passing stars. We then estimated the numbers of close stellar encounters over the lifetime of several expanding open clusters characterized by their initial star densities. We found that a standard disk, with inner and outer radii of 40 and 100 AU, suffers no loss of planetesimals around a star born in a common embedded cluster with star density 20 000 pc^-3. In this environment, a disk loses >97% of its ...

CERN Document Server

We examine patterns of variation of 32 primarily main sequence stars, extending our previous 7-12 year time series to 13-20 years by combining b, y data from Lowell Observatory with similar data from Fairborn Observatory. Parallel chromospheric Ca II H and K emission data from the Mount Wilson Observatory span the entire interval. The extended data strengthen the relationship between chromospheric and photometric variation derived previously. Twenty-seven stars are deemed variable. On a year-to-year timescale young active stars become fainter when their Ca II emission increases while older less active stars such as the Sun become brighter when their Ca II emission increases. The Sun's total irradiance variation, scaled to the b and y filter photometry, still appears to be somewhat smaller than stars in our limited sample with similar mean chromospheric activity, but we now regard ...

International Nuclear Information System (INIS)

Recent experimental and theoretical studies of two-dimensional (2D) turbulence reveal that spectrally condensed turbulence which is a system of coupled large-scale coherent flow and broadband turbulence, is similar to plasma turbulence near the L-H transition threshold. Large condensate vortices fed via the turbulent inverse energy cascade, can control both the level of the broadband turbulence by shear decorrelation, and the energy injected into turbulence at the forcing scale via sweeping of the forcing-scale vortices. The interaction between these ingredients of spectrally condensed fluid turbulence is in many aspects similar to the interactions in the zonal flow-GAMs-turbulence system in plasma. In this paper we overview recent results on condensed 2D turbulence and present evidence of interaction between its three components: condensate structures, turbulence and forcing-scale ...

British Library Electronic Table of Contents (United Kingdom)

The collapsar scenario for long gamma-ray bursts requires rapidly rotating Wolf-Rayet stars as progenitor stars. We highlight two possible ways out of the dilemma that the strong winds of Wolf-Rayet lead to a fast spin-down. One way is to restrict the duration of the Wolf-Rayet phase to a short time span at the end of the star's evolution. We show that this appears to apply to GRB 021004. The other way is to choose a sub-solar metallicity, thus limiting the Wolf-Rayet wind efficiency. We discuss corresponding stellar evolution models and show that a metallicity limit of about 1/10th solar, as it is required by the models, may be consistent with the empirical gamma-ray burst rate.

CERN Document Server

We report Sr, Pd and Ag abundances for a sample of metal-poor field giants and analyze a larger sample of Y, Zr, and Ba abundances. The [Y/Zr] and [Pd/Ag] abundance ratios are similar to those measured for the r-process-rich stars CS 22892-052 and CS 31082-001. The [Pd/Ag] ratio is larger than predicted from the solar-system r-process abundances. The constant[Y/Zr] and [Sr/Y] values in the field stars places strong limits on the contributions of the weak s-process and the main s-process to the light neutron-capture elements. Stars in the globular cluster M 15 possess lower [Y/Zr] values than the field stars. There is a large dispersion in [Y/Ba]. Because the r-process is responsible for the production of the heavy elements in the early Galaxy, these dispersions require varying light-to-heavy ratios in r-process yields.

Science.gov (United States)

May 18, 2007 ... This exciting new development in neutron star evolution was presented at the Winter 2004 AAS Meeting in Atlanta, Georgia. ...

Science.gov (United States)

... and high-quality photospheric-phase Type II SN spectra to constrain core- collapse SN explosions, massive star evolution, and distances in the Universe ...

Science.gov (United States)

the revealed stage of T Tauri star evolution, is only a mere shadow of its former self. Once primary accretion starts, one has the (poorly quantified) ...

Science.gov (United States)

These include, but are not limited to: stellar winds and outflows, post-main- sequence stellar evolution, binary/multiple star evolution, globular cluster ...

International Nuclear Information System (INIS)

We study the magnetic braking and viscous damping of differential rotation in incompressible, uniform density stars in general relativity. Differentially rotating stars can support significantly more mass in equilibrium than nonrotating or uniformly rotating stars, according to general relativity. The remnant of a binary neutron star merger or supernova core collapse may produce such a 'hypermassive' neutron star. Although a hypermassive neutron star may be stable on a dynamical time scale, magnetic braking and viscous damping of differential rotation will ultimately alter the equilibrium structure, possibly leading to delayed catastrophic collapse. Here we treat the slow-rotation, weak-magnetic field limit in which E_r_o_t<

British Library Electronic Table of Contents (United Kingdom)

Abstract We use Smoothed Particle Hydrodynamics to simulate the formation of a massive (106-M-) stellar cluster system formed from the gravitational collapse of a turbulent molecular cloud. We investigate the hierarchical clustering properties of our model system and we study the influence of the photoionizing radiation produced by the system's multiple O-type stars on the evolution of the protocluster. We find that dense gas near the ionizing sources prevents the radiation from eroding the filaments in which most of the star formation occurs and that instead, ionized gas fills pre-existing voids and bubbles originally created by the turbulent velocity field.

Science.gov (United States)

You can find a discussion of time travel and Tipler's cylinder at this site: http://www.star-names.freeserve.co.uk/travel.htm ...

Science.gov (United States)

These include, but are not limited to: stellar winds and outflows, post-main- sequence stellar evolution, binary/multiple star evolution, globular cluster structure ...

British Library Electronic Table of Contents (United Kingdom)

We consider the evolution of binary systems formed by a Supermassive Black Hole (SMBH) residing in the center of a galaxy or a globular cluster and a star in its immediate vicinity. The star is assumed to fill its Roche lobe, and the SMBH accretes primarily the matter of this star. The evolution of such a system is mainly determined by the same processes as for an ordinary binary. The main differences are that the donor star is irradiated by hard radiation emitted during accretion onto the SMBH; in a detached system, nearly all the donor wind is captured by the black hole, which strongly affects the evolution of the semi-major axis; it is not possible for companions of the most massive SMBHs to fill their Roche lobes, since the corresponding orbital separations are smaller than the radius ...

Science.gov (United States)

gently constrain calculations of single-star evolution at high metallicity. Independent of SIM Lite observa- tions, we also propose to establish 4) how to ...

Science.gov (United States)

Mar 6, 2009 ... remnants of massive star evolution) to worlds that are more reassuringly familiar. In the latter category, we now have excellent evidence ...

Science.gov (United States)

... than the age of the universe unless it is an unresolved double degenerate or a product of common-envelope binary star evolution (Fontaine et al. ...

Science.gov (United States)

Feb 13, 2005 ... Part 8 of a non-mathematical historical review of elementary quantum theory, to help explain processes in the Sun and in stars; part of an ...

Science.gov (United States)

Experiments were conducted to study the condensation heat transfer characteristics of horizontal enhanced tubes. In the current experiment, six different enhanced tubes, including 26, 40 fpi low fin tubes and four three-dimensional-fin tubes, were tested. The working fluid used in the experiment was HCFC-22. Data were presented in the form of overall heat transfer coefficient at three working pressures, namely 1.32, 1.47 and 1.62 Mpa. In addition, the condensing heat transfer coefficients for the test tubes were obtained from the Wilson plot technique.

Energy Technology Data Exchange (ETDEWEB)

Condensing curves are presented for a number of two-component mixed hydrocarbon working fluids which are potentially usable in binary geothermal cycles. Performance of geothermal thermodynamic cycles incorporating these fluids has been evaluated under separate cover; two figures summarizing the results of those evaluations have been included here for continuity. The purpose of this report is: first, to document the condensing curves which were used in the mixed fluid cycle analyses, and second, to provide background useful in the preliminary evaluation of heat rejection systems for advanced geothermal electric power plants utilizing mixed hydrocarbon working fluids. Some concluding remarks are presented.

International Nuclear Information System (INIS)

Russian 2004 p. 50-51 Russian Federation Kalyakin, SG Kapinos,

UK PubMed Central (United Kingdom)

BackgroundThe monolignol biosynthetic pathway interconnects with the biosynthesis of other secondary phenolic metabolites, such as cinnamic acid derivatives, flavonoids and condensed...Full Text Available

Energy Technology Data Exchange (ETDEWEB)

Apart from condensing the off-air condensers have a number of additional functions, which have been added more or less incidentally as development progressed. Advanced development of certain types of turbine condensers justifies the hope that these additional functions can be improved as power plants become cheaper and simpler.(orig.) [German] Kondensatoren haben neben ihrer Hauptaufgabe, der Kondensation des Turbinenabdampfes eine Reihe zusaetzlicher Funktionen, die sich z.T. im Laufe der Entwicklung eher beilaeufig ergeben haben. Der hohe Entwicklungsstand bei bestimmten Bauarten von Turbinenkondensatoren laesst die Erwartung zu, dass im Zuge der Vereinfachung und Verbilligung von Kraftwerksanlagen 'Nebenfunktionen' verbessert werden koennen. (orig.)

Energy Technology Data Exchange (ETDEWEB)

First French manufacturer of steel boilers, Geminox proposes the THRi series, composed of condensation gas boilers whose four mural for the propane model. (O.M.)

CERN Document Server

A prescription is given for computing anomalous dimensions of single trace operators in SYM at strong coupling and large $N$ using a reduced model of matrix quantum mechanics. The method involves treating some parts of the operators as "BPS condensates" which, in certain limit, have a dual description as null geodesics on the $S^5$. In the gauge theory, the condensate is similar to a representative of the chiral ring and it is described by a background of commuting matrices. Excitations around these condensates correspond to excitations around this background and take the form of ``string bits" which are dual to the "giant magnons" of Hofman and Maldacena. In fact, the matrix model approach gives a {\\it quantum} description of these string configurations and explains why the infinite momentum limit suppresses the quantum effects. This method allows, not only to derive part of the classical sigma model Hamiltonian of the ...

British Library Electronic Table of Contents (United Kingdom)

The properties of ZnO films were investigated as functions of annealing temperatures in H2/Ar and vacuum. The resistivities and mobilities of ZnO films decreased with increase of annealing temperatures in vacuum and H2/Ar ambients. However, the carrier densities of ZnO films increased with increase of annealing temperatures in vacuum and H2/Ar ambients. The resistivities of ZnO2 films annealed at 300degreeC were 2186cm and 798cm in H2/Ar and vacuum ambients, respectively. The resistivities of ZnO films annealed in vacuum and H2/Ar ambients at 600degreeC were similar with 0.040cm and 0.035cm, respectively. The hydrogen donor was more dominant than the oxygen vacancy or Zn interstitial donor in ZnO films annealed in ambient H2/Ar at low temperatures. The average optical transmission was >82%...

Energy Technology Data Exchange (ETDEWEB)

The Dental Investigation Service, USAFSAM, Brooks AFB, has outlined the need for a vacuum unit to be used in the Air Force dental clinics. The unit must be capable of effectively picking up mercury and at the same time not redistribute mercury vapors throughout the dental clinic during normal operations or mercury-spill situations. The Dental Investigation Service selected the MRS-3, Minuteman Mercury Recovery System, product of American Cleaning Equipment Corporation as the mercury vacuum to be used for T E. The USAF OEHL/ECH was requested by the Dental Investigation Service to perform the T E on the MRS-3 for possible health hazards due to exposures of mercury vapors.

CERN Document Server

We investigate the solar neutrino problem in the scenario of three generation neutrino oscillation hypothesis, taking into account other phenomenological constraints to the neutrino mixing and mass parameters.

Energy Technology Data Exchange (ETDEWEB)

A miniature x-ray source utilizing a hot filament cathode. The source has a millimeter scale size and is capable of producing broad spectrum x-ray emission over a wide range of x-ray energies. The miniature source consists of a compact vacuum tube assembly containing the hot filament cathode, an anode, a high voltage feedthru for delivering high voltage to the cathode, a getter for maintaining high vacuum, a connector for initial vacuum pump down and crimp-off, and a high voltage connection for attaching a compact high voltage cable to the high voltage feedthru. At least a portion of the vacuum tube wall is fabricated from highly x-ray transparent materials, such as sapphire, diamond, or boron nitride.

International Nuclear Information System (INIS)

A high-average power (kW) infrared (IR) free-electron laser (FEL) is currently being commissioned for the Jefferson Laboratory FEL User Facility. The IR FEL is driven by a unique superconducting rf linac which is recirculated to recover electron beam power that is not radiated in the FEL. The design and installation of the vacuum system for the FEL involved particular attention to minimizing particulate contamination which could cause problems with the superconducting acceleration cavities and the high power FEL optics. Particulate contamination levels of all vacuum components were monitored during the cleaning process using laser scattering. Cleaning, transport, and installation procedures were developed to minimize the contamination of the complete system. We will summarize a data base we compiled of particulate contamination levels of the various components installed in the FEL vacuum system.

Energy Technology Data Exchange (ETDEWEB)

The abstract contains a misprint in the value for the star central density, {rho}{sub s}, above which strange quarks appear. A factor of 10{sup 14} was omitted from the original version. Strange quarks appear for central densities {rho}{sub c} above {rho}{sub s}=9.85x10{sup 14} g cm{sup -3}. The abstract has also been rewritten to differentiate more clearly {rho}{sub c}, the general star central density, {rho}{sub m}, the maximal central density and {rho}{sub s} the minimal central density. It now reads as: The strange quark star is investigated within the enlarged SU(3) Nambu-Jona-Lasinio model. The stable star can exist until a maximal configuration with central density {rho}{sub c}={rho}{sub m}=3.11x10{sup 15} g cm{sup -3} with M{sub m}=1.61 M circle and R{sub m}=8.74 km is reached. Strange quarks appear for densities {rho}{sub c} above {rho}{sub s}=9.85x10{sup 14} g cm{sup -3} for the quark ...

International Nuclear Information System (INIS)

Global angular momentum balance suggests that the neutron stars in Be/X-ray binaries are not spinning in equilibrium. This requires an X-ray lifetime ''approx <'' 10"5 yr, and suggests that there are many 'dead' Be/X-ray binaries in the Galaxy. Some of these may be turned up as millisecond radio pulsars with Be star companions. (author).

Science.gov (United States)

The interaction between core and envelope in stars with central helium burning is investigated. If core and envelope are treated as independent systems, feedback terms arise. All feedback terms are discussed in detail. The approximative treatment of feedback terms in the earlier papers of Lauterborn, Refsdal, and Weigert is found to be fully justified. The problem of secular instabilities in models with central helium burning is rediscussed. (auth)

Science.gov (United States)

The theoretical evolution of a horizontal branch star of Population II is followed through the helium burning in the core phase and is compared with the results given by other investigators. The m- fluence of different physics and interpolation schemes in the opacity tables is discussed. Some thoughts are given on the explanation of the erratic period variations observed in some of the RR Lyrae variables in the globular clusters. (auth)

International Nuclear Information System (INIS)

Methods of preparation, stability in solutions and in the solid phase, composition of orthophosphate crystallohydrates and condensed uranyl- and uranium (4) phosphates, are considered. Structures of these compounds are discussed; it is shown that they are steric polymers with an uranylphosphate framework. The problem of phosphate-anion polymerization in the process of thermal decomposition is discussed. It is established that condensed uranyl polyphosphates are not stable during storage, capable of degradation, its degree increasing with the phosphate chain length and uranium content.

CERN Document Server

The early idea that a non-perturbative gluon condensate affects the spectrum of heavy quarks is revisited in the light of modern simulation techniques. We evaluate the low lying spectrum of bound states of two heavy quarks for large hypothetical quark mass, m_Q > m_b, using non-relativistic QCD and compare with other models to test the consistency.

CERN Document Server

We argue that the occurrence of late-time acceleration can conveniently be described by first-order general relativity covariantly coupled to fermions. Dark energy arises as a gravitationally driven BCS condensate of fermions which forms in the early universe. At late times, the gap and chemical potential evolve to have an equation of state with effective negative pressure, thus naturally leading to acceleration.

Science.gov (United States)

Through the collaborative efforts of undergraduates and faculty at Gettysburg and Franklin & Marshall Colleges, we present the compilation of 10 years of differential photometry for three K-type stars in the Pleiades. These young stars have rotational light curves with V-band amplitudes of a few percent (10% in the most active) due to BY Draconis-type behavior (modulation due to rotation of a star with non-uniform surface brightness). With 10 years of photometry reduced, measured, and compiled we are now in a position to probe the V-band variations in these stars for indications of the extent of brightness asymmetry in the photosphere, and characteristics of the long-term activity of these stars. These observations were acquired at the National Undergraduate Research Observatory, operated by Lowell Observatory and Northern Arizona University. This work is supported by Gettysburg ...

CERN Document Server

Spatially resolved studies of star forming regions show that the assumption of spherical geometry is not realistic in most cases, with a major complication posed by the gas being ionised by multiple non-centrally located stars or star clusters. We try to isolate the effects of multiple non-centrally located stars on the temperature and ionisation structure of HII regions, via the construction of 3D photoionisation models using the 3D Monte Carlo photoionisation code MOCASSIN. We find that the true temperature fluctuations due to the stellar distribution (as opposed to the large-scale temperature gradients due to other gas properties) are small in all cases and not a significant cause of error in metallicity studies. Strong emission lines from HII regions are often used to study the metallicity of star-forming regions. We compare integrated emission line spectra from our models and ...

CERN Document Server

We study the structure of the medium surrounding sites of high-mass star formation to determine the interrelation between the HII regions and the environment from which they were formed. The density distribution of the surroundings is key in determining how the radiation of the newly formed stars interacts with the surrounds in a way that allows it to be used as a star formation tracer. We present new Herschel/SPIRE 250, 350 and 500 mum data of LHA 120-N44 and LHA 120-N63 in the LMC. We construct average spectral energy distributions (SEDs) for annuli centered on the IR bright part of the star formation sites. The annuli cover ~10-~100 pc. We use a phenomenological dust model to fit these SEDs to derive the dust column densities, characterise the incident radiation field and the abundance of polycyclic aromatic hydrocarbon molecules. We see a factor 5 decrease in the radiation field energy density as a ...

CERN Document Server

The ultra-precise photometric space satellite MOST (Microvariability and Oscillations of STars) will provide the first opportunity to measure the albedos and scattered light curves from known short-period extrasolar planets. Due to the changing phases of an extrasolar planet as it orbits its parent star, the combined light of the planet-star system will vary on the order of tens of micromagnitudes. The amplitude and shape of the resulting light curve is sensitive to the planet's radius and orbital inclination, as well as the composition and size distribution of the scattering particles in the planet's atmosphere. To predict the capabilities of MOST and other planned space missions, we have constructed a series of models of such light curves, improving upon earlier work by incorporating more realistic details such as: limb darkening of the star, intrinsic granulation noise in the ...

CERN Document Server

Kepler Mission results are rapidly contributing to fundamentally new discoveries in both the exoplanet and asteroseismology fields. The data returned from Kepler are unique in terms of the number of stars observed, precision of photometry for time series observations, and the temporal extent of high duty cycle observations. As the first mission to provide extensive time series measurements on thousands of stars over months to years at a level hitherto possible only for the Sun, the results from Kepler will vastly increase our knowledge of stellar variability for quiet solar-type stars. Here we report on the stellar noise inferred on the timescale of a few hours of most interest for detection of exoplanets via transits. By design the data from moderately bright Kepler stars are expected to have roughly comparable levels of noise intrinsic to the stars and arising from a combination ...

International Nuclear Information System (INIS)

Pulsations driven by partial ionization of hydrogen in the envelope are often considered important for driving winds from red supergiants (RSGs). In particular, it has been suggested by some authors that the pulsation growth rate in an RSG can be high enough to trigger an unusually strong wind (or a superwind), when the luminosity-to-mass ratio becomes sufficiently large. Using both hydrostatic and hydrodynamic stellar evolution models with initial masses ranging from 15 to 40 M_s_u_n, we investigate (1) how the pulsation growth rate depends on the global parameters of supergiant stars and (2) what would be the consequences of a pulsation-driven superwind, if it occurred, for the late stages of massive star evolution. We suggest that such a superwind history would be marked by a runaway increase, followed by a sudden decrease, of the wind's mass-loss rate. The impact on the late evolution of massive stars would be ...

Energy Technology Data Exchange (ETDEWEB)

Condensing two-phase channel flow occurs in many industrial applications, including heating and refrigeration systems. It can also occur in certain nuclear reactor accidents. For example, during a small-break loss-of-coolant accident in a pressurized water reactor, following the partial depletion of the primary coolant, condensation of steam on the primary side of the steam generator tubes can provide a heat sink for disposal of the decay heat generated in the reactor core. Condensing two-phase flow can also play an important role in the operation of the passive emergency cooling system in the advanced simplified boiling water reactor. Here, steady-state condensation in the presence of a noncondensable in a concurrent two-phase channel flow is analyzed using a two-fluid model. The effect of noncondensables on the combined heat transfer at the liquid-gas mixture interphase is accounted for by using the ...

Science.gov (United States)

> Develoopments which have imporved fuel core quality and reduced production costs are described. These developments in the melting and casting of uranium ingots arei modification of the crucible and knockout-slide assembly, substitution of uncoated crucibles for coated crucibles, and substitution of a one-piece gun barrel mold for a vertically split mold. (N.W.R.)

International Nuclear Information System (INIS)

A technique has been developed for joining a large calcium fluoride crystal to a stainless-steel flange by means of a silver transition ring. The process involves both vacuum brazing using a copper-silver alloy and air brazing using silver chloride. This paper describes the procedure used in fabricating a high-vacuum leak-tight calcium fluoride window assembly.

Energy Technology Data Exchange (ETDEWEB)

In order to judge the potential fluorescent lamp applications of various low-pressure positive column discharges it is necessary to measure the absolute power emitted in the ultraviolet region of the spectrum. For rare-gas discharges the principle emission occurs in the vacuum ultraviolet so that it is difficult to measure the radiant emittance (power per unit area) of the resonance radiation by standard methods. Two independent techniques are discussed for measuring the radiant emittance of positive column discharges in the vacuum ultraviolet. These techniques are used to study xenon positive column discharges at the resonance wavelength of 147 nm. The first method relies on the measurement of the resonance level density by absorption techniques. The effective decay rate of the resonance level is then determined by the simulation of resonance radiation transport. These two quantities are combined to yield the radiant emittance at 147 nm ...

Energy Technology Data Exchange (ETDEWEB)

The current status of the ZTH vacuum liner design is covered by this report. ZTH will be the first experiment to be installed in the CPRF (Confinement Physics Research Facility) at the Los Alamos National Laboratory and is scheduled to be operational at the rated current of 4 MA in 1992. The vacuum vessel has a 2.4 m major radius and a 40 cm minor radius. Operating parameters which drive the vacuum vessel mechanical design include a 300 C bakeout temperature, an armour support system capable of withstanding 25 kV, a high toroidal resistance, 1250 kPa magnetic loading, a 10 minute cycle time, and high positional accuracy with respect to the conducting shell. The vacuum vessel design features which satisfy the operating parameters are defined. The liner is constructed of Inconel 625 and has a geometry which alternates sections of thin walled bellows with rigid ribs. These composite sections span between ...

International Nuclear Information System (INIS)

We investigate the relationship between spiral arms and star formation in the grand-design spirals NGC 5194 and NGC 628 and in the flocculent spiral NGC 6946. Filtered maps of near-IR (3.6 #mu#m) emission allow us to identify 'arm regions' that should correspond to regions of stellar mass density enhancements. The two grand-design spirals show a clear two-armed structure, while NGC 6946 is more complex. We examine these arm and interarm regions, looking at maps that trace recent star formation-far-ultraviolet (GALEX NGS) and 24 #mu#m emission (Spitzer SINGS)-and cold gas-CO (HERACLES) and H I (THINGS). We find the star formation tracers and CO more concentrated in the spiral arms than the stellar 3.6 #mu#m flux. If we define the spiral arms as the 25% highest pixels in the filtered 3.6 #mu#m images, we find that the majority (60%) of star formation tracers occur in the interarm regions; this result ...

Energy Technology Data Exchange (ETDEWEB)

This project dealt with use of condensing heat exchangers to recover water vapor from flue gas at coal-fired power plants. Pilot-scale heat transfer tests were performed to determine the relationship between flue gas moisture concentration, heat exchanger design and operating conditions, and water vapor condensation rate. The tests also determined the extent to which the condensation processes for water and acid vapors in flue gas can be made to occur separately in different heat transfer sections. The results showed flue gas water vapor condensed in the low temperature region of the heat exchanger system, with water capture efficiencies depending strongly on flue gas moisture content, cooling water inlet temperature, heat exchanger design and flue gas and cooling water flow rates. Sulfuric acid vapor condensed in both the high temperature and low temperature regions of the heat ...

International Nuclear Information System (INIS)

The evolution of intermediate and high mass stars is reviewed focusing on the interpretation of Pop I Cepheids. First, a summary is given of the classical results of stellar evolution theory for the main evolutionary phases (main sequence and core He-burning) all over the HR diagram, putting into evidence the various points of disagreement with current observational data. Second, models incorporating the effect of convective overshoot, are reviewed, and studies are presented on the rich, young clusters in the Large Magellanic Cloud, in which the models are compared with the observational data. Arguments are given to favor the adoption of models with convective overshoot instead of the classical ones. Third, new results are presented for pulsational models of the Cepheid stars, and the shape of the instability strip in the HR diagram, the number frequency-period distribution, and the mass discrepancy are discussed. 81 refs.

Energy Technology Data Exchange (ETDEWEB)

Overall architecture of a local computer network, STAR, is described. The objective is to accomplish a cost-effective system which provides multiple users a real-time service of manipulating very large volume imagery information and data. STAR consists of a reconfigurable communication subnet (starnet), heterogeneous resource units, and distributed-control software entities. Architectural aspects of a fault-tolerant communication subnet, distributed database management, and a distributed scheduling strategy for configuring desirable computation topology are exploited. A model for comparing cost-effectiveness among starnet, crossbar, and multiple buses is included. It is concluded that starnet outperforms the other two when the number of units to be connected is larger than 64. This project serves as a research tool for using current and projected technology to innovate better schemes for parallel image processing. 30 references.

British Library Electronic Table of Contents (United Kingdom)

Abstract A large number of massive stars are known to rotate rapidly, resulting in a significant distortion and variation in surface temperature from the pole to the equator. Radiatively driven mass-loss is temperature-dependent, so rapid rotation produces a variation in the mass-loss and angular momentum loss rates across the surface of the star, which is expected to affect the evolution of rapidly rotating massive stars. In this work, we use zero-age main-sequence (ZAMS) stellar models to investigate the two-dimensional effects of rotation on stellar mass-loss, using two common prescriptions for radiatively driven mass-loss. The associated loss of angular momentum from these models is also considered. Using 2D stellar models, which give the variation in surface parameters as a function o...

British Library Electronic Table of Contents (United Kingdom)

New photometric observations of the variable star FG Sge, a rapidly evolving planetary nebula nucleus, were performed in 2003?2008. On 230 nights, we obtained 86 UBV and 155 BV RI (or R c , I c ) magnitude estimates. The maximum amplitude of the V-band light variations was >8 m . Six deep minima and four high maxima were observed. Analysis of the light curve has shown that the pulsation period of the star remained constant since 1991 and was P = 115 days. We have studied the wavelength dependence of the extinction at various phases of the light curve. The blueing of the B-V color at deep minima is interpreted as the result of light scattering in the circumstellar dust shell of the star formed by preceding dust ejections since 1992. Our spectroscopic observations performed on nine nights in...

British Library Electronic Table of Contents (United Kingdom)

Abstract Recent work (Schawinski et al.) indicates that star-forming early-type galaxies residing in the blue cloud migrate rapidly to the red sequence within around a Gyr, passing through several phases of increasingly strong active galactic nucleus (AGN) activity in the process. We show that natural depletion of the cold gas reservoir through star formation (i.e. in the absence of any feedback from the AGN) induces a blue-to-red reddening rate that is several factors lower than that observed by Schawinski et al. This is because the gas depletion rate due to star formation alone is too slow, implying that another process needs to be invoked to remove cold gas from the system and accelerate the reddening rate. We develop a simple phenomenological model, in which a fraction of the AGN-s lum...

Energy Technology Data Exchange (ETDEWEB)

A solar energy desalination process utilizing solar radiation directly for the evaporation of salt water is described. Ambient air takes on water vapor as the air passes through an evaporative medium. It is then directed between a saline water-covered, solar absorbing surface and a solar collecting housing. The resulting heated and moisture-saturated air is cooled in a heat exchange means where condensation of fresh water occurs. Simultaneously, cool salt water is utilized as the cooling water in the heat exchange means, and takes on the heat of condensation given up by the condensing vapor. The heated salt water from the heat exchange means is partially directed over the solar absorbing surface, and at least a portion of it is also directed to wet the evaporative medium. Several optional sub-processes are described for operation of the system during periods of reduced insolation, and an alternative process is described for ...

International Nuclear Information System (INIS)

A 340-watt CO_2 laser is being used to generate PuO_2-UO_2 condensation aerosol from the surface of a Liquid Metal Fast Breeder Reactor (LMFBR) fuel pellet. A wide range of concentrations is achieved by varying the laser power, pulse width, and/or pulse period. The resulting aerosol is composed of branch chain-like aggregates, with the primary particle size ranging between 0.005 and 0.15 #mu#m. X-ray diffraction analyses show that these aerosols condense into a face-centered cubic crystal structure. The activity mean aerodynamic diameter (AMAD), for most power levels, is approximately 0.85 #mu#m with a geometric standard deviation of 1.5.

British Library Electronic Table of Contents (United Kingdom)

The investigation of steam, water, and air flow characteristics in horizontal channel is a part of major investigations program at the Lithuanian Energy Institute. The objective of this program is to identify condensation effects on two-phase flow stability and to predict conditions when rapid condensation could be induced in two-phase condensable flow. This article presents investigation of steam-water and air multiphase flow in nearly horizontal rectangular channel. The experimental data for pressure drop and interfacial and wall shear stresses in the channel with uniform distribution of void fraction are presented in this paper. Overall channel dimensions are length = 1.2 m, width = 0.02 m, height = 0.1 m; however, the test section was about 0.84 m in length. Three different flow types ...

Energy Technology Data Exchange (ETDEWEB)

Fundamental phenomena of condensation heat transfer at a steam-water interface have been studied related to the thermo-hydrodynamics of the emergency core cooling system for light water reactors. In this study temperature fluctuations near the interface and in the liquid phase were measured using fine thermocouples for a saturated steam-subcooled water co-current stratified two-phase flow in a nearly horizontal rectangular channel, and heat transfer coefficients were determined experimentally. The values of the condensation heat transfer coefficients in this experiment are from 6 to 40 kW/m{sup 2}K. In the regions of high Reynolds numbers, as the steam Reynolds numbers become larger, the average interfacial heat transfer coefficients tend to increase. The corelations of Nusselt numbers were obtained from the heat transfer data. (author)

Energy Technology Data Exchange (ETDEWEB)

As a part of the WE-NET project, the tanker for liquid hydrogen transport was studied. In fiscal 1996, some experiments and numerical analyses were proposed which are necessary to solve technological issues extracted in fiscal 1995 for heat insulation structure. The issue was roughly classified into vacuum and non-vacuum insulation, and their basic functions and required performance were arranged. Boil-off rate of 0.2-0.4%/d was targeted. The insulation system which applies polyurethane form (PUF) to tank surfaces and injects atmospheric N2 gas into the surrounding hold space, could achieve the targeted insulation performance by PUF of 1m in thickness. The system of vacuum panel insulation and atmospheric N2 gas injection into a hold space required the panel of 500mm in thickness because of the large effect of metallic outer panel material. The system of vacuum hold and PUF panels was faced with the ...

CERN Document Server

We present evidence for the existence of two ~35 day clocks in the Her X-1/HZ Her binary system. ~35 day modulations are observed 1) in the Turn-On cycles with two on- and two off-states, and 2) in the changing shape of the pulse profiles which re-appears regularly. The two ways of counting the 35 day cycles are generally in synchronization. This synchronization did apparently break down temporarily during the long Anomalous Low (AL3) which Her X-1 experienced in 1999/2000, in the sense that there must have been one extra Turn-On cycle. Our working hypothesis is that there are two clocks in the system, both with a period of about ~35 days: precession of the accretion disk (the less stable "Turn-On clock") and free precession of the neutron star (the more stable "Pulse profile clock"). We suggest that free precession of the neutron star is the master clock, and that the precession of the accretion disk is basically synchronized to that of the ...

CERN Document Server

The He-shell flash convection in AGB stars is the site for the high-temperature component of the s-process in low- and intermediate mass giants, driven by the Ne22 neutron source. [...] The upper convection boundary plays a critical role during the H-ingestion episode that may lead to neutron-bursts in the most metal-poor AGB stars. We address these problems through global 3-dimensional hydrodynamic simulations including the entire spherical He-shell flash convection zone (as oposed to the 3D box-in-a-star simulations). An important aspect of our current effort is to establish the feasibility of our appoach. We explain why we favour the explicit treatment over the anelastic approximation for this problem. The simulations presented in this paper use a Cartesian grid of 512^3 cells and have been run on four 8-core workstations for four days to simulate ~5000s, which corresponds to almost ten convective turn-over times. The ...

CERN Document Server

Recent wide-field imaging observations of the X-ray luminous cluster RDCSJ1252.9-2927 at z=1.24 uncovered several galaxy groups that appear to be embedded in filamentary structure extending from the cluster core. We make a spectroscopic study of the galaxies in these groups using GMOS on Gemini-South and FORS2 on VLT with the aim of determining if these galaxies are physically associated to the cluster. We find that three groups contain galaxies at the cluster redshift and that they are probably bound to the cluster. This is the first confirmation of filamentary structure as traced by galaxy groups at z>1. We then use several spectral features in the FORS2 spectra to determine the star formation histories of group galaxies. We find a population of relatively red star-forming galaxies in the groups that are absent from the cluster core. While similarly red star forming galaxies can also be found in the field, the average ...

Science.gov (United States)

Oct 20, 2005 ... GE over-the-counter microwave, $40; Kitchen-Aid cooktop,. $75; both almond colored. 883-2877. Mossberg 835, RT Camo, slug barrel, scope. ...

Energy Technology Data Exchange (ETDEWEB)

The current status of cosmological observations is presented; and the light curves and radiation spectra from supernova SN1987A are used in comparison between expected and observed universal nucleosynthesis and star evolution data./aip/.

Energy Technology Data Exchange (ETDEWEB)

The aim of this paper is to obtain the effective potential of the non-topological soliton model at finite temperature with the assumption that the chemical potential {mu} of the system is different from zero and to analyse how the effective potential is influenced by changes in the chemical potential and temperature. (author)

Energy Technology Data Exchange (ETDEWEB)

This review covers research done at Lawrence Livermore National Laboratory in the fields of astronomy and astrophysics. The research areas mentioned are as follows: star evolution, supernovae, and nucleosynthesis; stellar atmospheres and winds; galaxies and the interstellar medium; and high-energy astrophysics.

Energy Technology Data Exchange (ETDEWEB)

This article throws light on an only recently understood but important development of star evolution - that of the occurrence of planetary nebulae. The process is controlled by thermonuclear physics and gravitation and now and again greatly influenced by mass loss.

CERN Document Server

Ultra-luminous infrared galaxies are among the most luminous objects in the local universe and are thought to be powered by intense star formation. It has been shown that in these objects the rotational spectral lines of molecular hydrogen observed at mid-infrared wavelengths are not affected by dust obscuration, leaving unresolved the source of excitation of this emission. Here I report an analysis of archival Spitzer Space Telescope data on ultra-luminous infrared galaxies and demonstrate that star formation regions are buried inside optically thick clouds of gas and dust, so that dust obscuration affects star-formation indicators but not molecular hydrogen. I thereby establish that the emission of H_2 is not co-spatial with the buried starburst activity and originates outside the obscured regions. This is rather surprising in light of the standard view that H_2 emission is directly associated with ...

International Nuclear Information System (INIS)

A disk formation model during collapse of the protosolar nebula, yielding a low-mass protoplanetary disk is presented. The following subject areas are covered: (1) circumstellar disks; (2) conditions for the formation of stars with disks; (3) early evolution of the protoplanetary disk; and (4) temperature conditions and the convection in the protoplanetary disk.

UK PubMed Central (United Kingdom)

BackgroundSteroidogenic acute regulatory (StAR) protein related lipid transfer (START) domains are small globular modules that form a cavity where lipids and lipid hormones bind....Full Text Available

Science.gov (United States)

Probing Neutron Star Evolution with Gamma Rays Online Source: Click to View PDF File [PDF Size: 217 KB] Author: Wijers, Ralph A. M. J. ...

Science.gov (United States)

international vehicles, control centers, and ground support personnel. ... consists of thin membranes made from a polymer-based film and ..... (including airplanes and submarines), environmental monitoring, and control ...... sciences can use it to analyze the birth and death of stars, the formation of solar ...

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br /br /GOLD STARbr /Highly effective power tools, these are some of the ...Tracy is a blueprint for success on the power of self-discipline.A 5 Gold Star ...one of the greatest strengths of all: The power of self-discipline.You'll like the A+

CERN Document Server

One hope to solve the cosmological constant problem is to identify a symmetry principle, based on which the cosmological constant can be reduced either to zero, or to a tiny value. Here, we note that requiring that the vacuum state is Lorentz invariant significantly reduces the theoretical value of the vacuum energy density. Hence, this also reduces the discrepancy between the observed value of the cosmological constant and its theoretical expectation, down from 123 orders of magnitude to 56 orders of magnitude. We find that, at one loop level, massless particles do not yield any contribution to the cosmological constant. Another important consequence of Lorentz symmetry is stabilization of the gravitational hierarchy: the cosmological constant (divided by Newton's constant) does not run as the quartic power of the renormalization group scale, but instead only logarithmically.

British Library Electronic Table of Contents (United Kingdom)

We have measured time-resolved laser-induced incandescence of flame-generated soot under high-vacuum conditions (4.1?10?6 mbar) at an excitation wavelength of 532 nm with laser fluences spanning 0.06?0.5 J/cm2. We generated soot in an ethylene/air diffusion flame, introduced it into the vacuum system with an aerodynamic lens, heated it using a pulsed laser with a spatially homogeneous and temporally smooth laser profile, and recorded LII temporal profiles at 685 nm. At low laser fluences LII signal decay rates are slow, and LII signals persist beyond the residence time of the soot particles in the detection region. At these fluences, the temporal maximum of the LII signal increases nearly linearly with increasing laser fluence until reaching a plateau at ?0.18?J/cm2. At higher fluences, th...

International Nuclear Information System (INIS)

White dwarf evolution, particularly in the early phases, is not very strongly constrained by observation. Fortunately, white dwarfs undergo nonradial pulsation in three distinct regions of the H-R diagram. These pulsations provide accurate masses, surface compositional structure and rotation velocities, and help constrain other important physical properties. We demonstrate the application of the tools of stellar seismology to white dwarf evolution using the hot white dwarf star PG 1159-035 and the cool DAV (or ZZ Ceti) stars as examples. From pulsation studies, significant challenges to the theory of white dwarf evolution emerge. 44 refs.

Energy Technology Data Exchange (ETDEWEB)

Results of analytical study of early stages of a single star evolution are used investigation of the rotational fragmentation of the collapsing gas-dust cloud which leads to formation of two types of binaries. Wide ..cap alpha..-systems (Psub(orb) > or approximately 100 yrs) with usually unequal masses of components are formed before the formation of gas-dust core in hydrostatical equilibrium. Close ..beta..-systems (Psub(orb) < or approximation 100 yrs) with usually nearly equal masses of components are formed in the course of the collapse of gas-dust core.

Energy Technology Data Exchange (ETDEWEB)

The thermal evolution predicted by current models of the superfluid-crust interaction is noted to differ substantially from the thermal evolution predicted by models without internal heating as well as previous models of heating. Heating rates approaching the maximum predicted by current models enhance the photon luminosity of the star in the neutrino cooling era, and dramatically alter the thermal evolution in the photon cooling era. Standard cooling models are consistent with current pulsar temperature estimates and upper limits, except those for the Vela pulsar, which are lower than predicted. 77 refs.

British Library Electronic Table of Contents (United Kingdom)

The common envelope phase of binary star evolution plays a central role in many evolutionary pathways leading to the formation of compact objects in short period systems. Using three dimensional hydrodynamical computations, we review the major features of this evolutionary phase, focusing on the conditions that lead to the successful ejection of the envelope and, hence, survival of the system as a post common envelope binary. Future hydrodynamical calculations at high spatial resolution are required to delineate the regime in parameter space for which systems survive as compact binary systems from those for which the two components of the system merge into a single rapidly rotating star. Recent algorithmic developments will facilitate the attainment of this goal.

Energy Technology Data Exchange (ETDEWEB)

We study the condensation of localized closed string tachyons in C{sup 3}/Z{sub N} non-supersymmetric noncompact orbifold singularities via renormalization group flows that preserve supersymmetry in the worldsheet conformal field theory and their interrelations with the toric geometry of these orbifolds. We show that for worldsheet supersymmetric tachyons, the endpoint of tachyon condensation generically includes 'geometric' terminal singularities (orbifolds that do not have any marginal or relevant Kahler blowup modes) as well as singularities in co-dimension two. Some of the various possible distinct geometric resolutions are related by flip transitions. For Type II theories, we show that the residual singularities that arise under tachyon condensation in various classes of Type II theories also admit a Type II GSO projection. We further show that Type II orbifolds entirely devoid of marginal or relevant ...

Energy Technology Data Exchange (ETDEWEB)

A cost study is described which compared the economics of four dry/wet cooling systems to use at the existing Raft River Geothermal Plant. The results apply only at this site and should not be generalized without due consideration of the complete geothermal cycle. These systems are: the Binary Cooling Tower, evaporative condenser, Combin-aire, and a metal fin-tube dry cooling tower with deluge augmentation. The systems were evaluated using cooled, treated geothermal fluid instead of ground or surface water in the cooling loops. All comparisons were performed on the basis of a common plant site - the Raft River 5 MWe geothermal plant in Idaho. The Binary Cooling Tower and the Combin-aire cooling system were designed assuming the use of the isobutane/water surface condenser currently installed at the Raft River Plant. The other two systems had the isobutane ducted to the evaporative condensers. Capital credit was not given to ...

British Library Electronic Table of Contents (United Kingdom)

A new process for the hydrogenation of coal in the presence of wide-cut coal tar was proposed; it involves cavitation treatment, mixing with catalytic additives, and heating the resulting mixture at an elevated pressure in an atmosphere of hydrogen. The yields of hydrocarbon fractions to 300?C and gas condensate were evaluated.

Science.gov (United States)

Measurement of local steam condensation rates of cocurrent stratified flow of steam and subcooled water was carried out at atmospheric pressure in a horizontal rectangular channel. The channel was constructed of stainless steel with pyrex glass windows, a...

UK PubMed Central (United Kingdom)

The biosynthetic costs of phenylpropanoid-derived condensed tannins (CTs) and phenolic glycosides (PGs) are substantial. However, despite reports of negative correlations between leaf phenolic content...Full Text Available

Energy Technology Data Exchange (ETDEWEB)

We propose triplet superconductors, such as ruthenates, as prospective materials for qubit construction. The vectorial nature of the order parameter in triplet superconductors makes it conceptually easy to estimate the performance of the qubits. The Cooper condensate of pairs in triplet superconductors has all the attributes of Bose-Einstein condensates and should facilitate long decoherence times for these qubits, relative to other vectorial schemes for qubits, such as small ferromagnets. There are other benefits, which the superconducting state provides for requirements such as entanglement between qubits via the proximity effect, etc. We consider these benefits in detail, although our consideration is only preliminary and further experimental and theoretical research will undoubtedly introduce correctives.

Energy Technology Data Exchange (ETDEWEB)

All sections of the third edition of this well-known textbook have been revised and enlarged in consequence of the change-over to SI units. Numerous examples and illustrations have been included or replaced by new ones. The book considers the latest research results as well as the constructive developments of industrial steam turbine construction. On a scientific basis, this plain book imparts basic knowledge of the design, calculation, execution, condensation and performance in service of steam turbines of all types. The well-founded introduction, together with many calculated examples addresses the student as well as the engineer.

Energy Technology Data Exchange (ETDEWEB)

Researchers are developing polymer-based coating systems to reduce scaling and corrosion of air-cooled condensers that use a geothermal fluid spray for heat transfer augmentation. These coating systems act as barriers to corrosion to protect aluminum fins and steel tubing; they are formulated to resist the strong attachment of scale. Field tests have been done to determine the corrosion and scaling issues related to brine spraying and a promising organometallic polymer has been evaluated in salt spray tests.

Energy Technology Data Exchange (ETDEWEB)

Energy savings in the synthetic fiber industry could be realized by using autoclave reactor condensate and boiler flue gas heat recovery. The non-cellulose (polyester) production process analysis shows that condensate returning from the reactor to the steam boiler raises inlet temperature, giving a reduced fuel requirement of about 8%. Also, boiler flue gas with a sufficiently high outlet temperature for boiler feed water and combustion air preheating results in further fuel savings. The process with an economizer saves up to 8.44%, and with a combustion air preheater, 6.25%. (Author)

International Nuclear Information System (INIS)

In dual-energy projection radiography with double exposures, rapid energy switching is mandatory to eliminate motion artifacts, but it is costly for use in a clinical environment. We developed a system with practical exposure intervals at reasonable cost by modifying a condenser-type X-ray generator. A commercially available system for digital radiography (Fuji Computed Radiography, FCR) was used to subtract images. This report dealt with technical factors to obtain adequate kV and mAs settings in this technique. (author).

International Nuclear Information System (INIS)

A diagnosis of the refrigerant flows in a refrigerator was carried out by real-time neutron radiography. The thermal neutron radiography system of JRR-3M in Japan Atomic Energy Research Institute and the real-time image processing system developed by Musashi Institute of Technology were used. Freon evaporating flows in the evaporator, condensing flows in the condenser, flashing flows in the capillary tube and flows in the accumulator were visualized and the dynamic behaviors under practical conditions were clarified. In the case of the capillary tube of 0.8 mm i.d., a cooled-CCD camera was utilized. (orig.).

International Nuclear Information System (INIS)

The interaction of free electrons in the energy range from 0 to 10 eV with molecules at different stages of aggregation is investigated. The mechanism in the gas phase under single collision conditions is described. Fullerenes C_6_0 and C_7_0 are used as targets. Electron impact on condensed molecules can lead to temporary negative ions. The formation of Cl"- from gas phase CCl_4 and the desorption of Cl"- from 6 monolayer CCl_4 film on an Au substrate is determined experimentally. (Suda).

Energy Technology Data Exchange (ETDEWEB)

The Heat Cycle Research Program, which is being conducted for the Department of Energy, has as its objective the development of the technology for effecting the improved utilization of moderate temperature geothermal resources. To meet this objective, the program has as one of its goals to improve the performance of geothermal binary cycles to levels approaching the practicable thermodynamic maximum. In pursuit of this goal, tests are being conducted at the Heat Cycle Research Facility located at the DOE Geothermal Test Facility, East Mesa, California. The current testing involves the investigation of binary power cycle performance utilizing mixtures of non-adjacent hydrocarbons as the working fluids, with supercritical vaporization and in-tube condensation of the working fluid. In addition to the present test program, preparations are being made to investigate the binary cycle performance improvements which can be achieved by allowing supersaturated vapor ...

International Nuclear Information System (INIS)

Since 1984 the thermal-hydraulic code ATHLET has been also applied for the analyses of LOCA and transients in VVER plants. The specific design of these plants especially of the steam generator design requires a specific modelling of the phenomena which may occur under LOCA and transient conditions in these plants. Differences in design compared to the design of western reactors have been briefly listed. Specific phenomena occurring under small leak accidents are shortly described. The consideration of the simulation of the boiler-condenser mode illustrates the modelling requirements for a code which may be applied to the prediction of such a thermal-hydraulic behaviour. Facing the lack of experimental data, the reliability of the simulation has been discussed by means of plausibility studies based on the momentum balance for steam and water. In summary: The VVER reactors differ in design compared to reactors of western design. The VVER design, especially the design ...

CERN Document Server

We study from a critical perspective several quantum-electrodynamic phenomena commonly related to vacuum electromagnetic (EM) fluctuations in complex media. We compute the resonance-shift, the spontaneous emission rate, the local density of states and the van-der-Waals-Casimir pressure in a dielectric medium using a microscopic diagrammatic approach. We find, in agreement with some recent works, that these effects cannot be attributed to variations on the energy of the EM vacuum but to variations of the dielectric self-energy. This energy is the result of the interaction of the bare polarizability of the dielectric constituents with the EM fluctuations of an actually polarized vacuum. We have found an exact expression for the spectrum of these fluctuations in a statistically homogeneous dielectric. Those fluctuations turn out to be different to the ones of normal radiative modes. It is the latter that carry the ...

International Nuclear Information System (INIS)

A scheme is presented for the generation of entangled states for two cavity mirrors. In the scheme each mirror initially in a vacuum state interacts with a weak coherent field, resulting in a photon-number dependent kick. The detection of a photon leaking from the cavities collapses the two mirrors to an entangled state.

International Nuclear Information System (INIS)

A Monte Carlo simulation of the vacuum Bianchi type-IX (mixmaster) cosmology yields a significant correlation between large universe volume and high anisotropy. An analog of the model's chaotic classical behavior is seen in the break up of the universe wave function at large volume into fingers in the corners of the minisuperspace anisotropy potential.

Science.gov (United States)

Spontaneous radiation by an atom in a Rydberg state is inhibited by use of parallel conducting planes to eliminate the vacuum modes at the transition frequency. Spontaneous radiation emission is observed to turn off abruptly at the cutoff frequency of the waveguidelike structure, and the natural lifetime is measured to increase by a factor of at least 20.

Science.gov (United States)

Bulk monomer MMA was impregnated into simul, a fuel wood of Bangladesh, under vacuum and under normal temperature and pressure conditions in order to compare the mode of impregnation and its effect on various characteristic parameters of wood plastic composites. Methanol (MeOH) was used as the swelling solvent with methylmethacrylate (MMA) at MMA: MeOH = 70:30, v/v. Impregnation of the bulk monomer was very high under vacuum compared to that at normal condition; but the difference of grafting of MMA to the wood cellulose under these two impregnating conditions was much lower as compared to that of the uptakes of impregnating solution MMA + MeOH under these two modes of impregnation. Incorporation of additives to MMA + MeOH has substantially enhanced grafting, tensile strength, bending strength and compression strength of the composite to such an extent that there is virtually very little difference between vacuum ...