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Sample records for sol heat transport

Turbulent transport regimes and the SOL heat flux width

Science.gov (United States)

Myra, J. R.; D'Ippolito, D. A.; Russell, D. A.

2014-10-01

Understanding the responsible mechanisms and resulting scaling of the scrape-off layer (SOL) heat flux width is important for predicting viable operating regimes in future tokamaks, and for seeking possible mitigation schemes. Simulation and theory results using reduced edge/SOL turbulence models have produced SOL widths and scalings in reasonable accord with experiments in many cases. In this work, we attempt to qualitatively and conceptually understand various regimes of edge/SOL turbulence and the role of turbulent transport in establishing the SOL heat flux width. Relevant considerations include the type and spectral characteristics of underlying instabilities, the location of the gradient drive relative to the SOL, the nonlinear saturation mechanism, and the parallel heat transport regime. Recent SOLT turbulence code results are employed to understand the roles of these considerations and to develop analytical scalings. We find a heat flux width scaling with major radius R that is generally positive, consistent with older results reviewed in. The possible relationship of turbulence mechanisms to the heuristic drift mechanism is considered, together with implications for future experiments. Work supported by US DOE grant DE-FG02-97ER54392.
Integrated simulation of ELM energy loss determined by pedestal MHD and SOL transport

International Nuclear Information System (INIS)

Hayashi, N.; Takizuka, T.; Ozeki, T.; Aiba, N.; Oyama, N.

2007-01-01

An integrated simulation code TOPICS-IB based on a transport code with a stability code for the peeling-ballooning modes and a scrape-off-layer (SOL) model has been developed to clarify self-consistent effects of edge localized modes (ELMs) and the SOL on the plasma performance. Experimentally observed collisionality dependence of the ELM energy loss is found to be caused by both the edge bootstrap current and the SOL transport. The bootstrap current decreases with an increase in collisionality and intensifies the magnetic shear at the pedestal region. The increase in the magnetic shear reduces the width of eigenfunctions of unstable modes, which results in the reduction of both the area of the ELM enhanced transport and the ELM enhanced transport near the separatrix. On the other hand, when an ELM crash occurs, the energy flows into the SOL and the SOL temperature rapidly increases. The increase in the SOL temperature lowers the ELM energy loss due to the flattening of the radial edge gradient. The parallel electron heat conduction determines how the SOL temperature increases. For higher collisionality, the conduction becomes lower and the SOL electron temperature increases more. By the above two mechanisms, the ELM energy loss decreases with increasing collisionality
Effect of asymmetric plasma potential in the SOL on the particle radial transport and heat flux broadening

International Nuclear Information System (INIS)

Hara, Junichiro; Uesugi, Yoshihiko; Miura, Yukitoshi; Kawashima, Hisato.

1997-01-01

The effective divertor heat-load relaxation using ExB induced convective cells in the SOL is studied. The ExB convective cells in the SOL are generated by the toroidally asymmetric divertor biasing, which can control the local plasma potential in the SOL. The preliminary experiment has been done in the JFT-2M tokamak with poloidal divertor. The helical SOL current flows along the magnetic field between the locally biased inboard plate and grounded outer plates, thereby modifying plasma potential in the vicinity of the local divertor current flow. The generation of the poloidal electric field reaching up to 1.5kV/m locally in the SOL and the modification of the heat flux profile on the divertor plate is observed. (author)
Turbulent transport regimes and the scrape-off layer heat flux width

Science.gov (United States)

Myra, J. R.; D'Ippolito, D. A.; Russell, D. A.

2015-04-01

Understanding the responsible mechanisms and resulting scaling of the scrape-off layer (SOL) heat flux width is important for predicting viable operating regimes in future tokamaks and for seeking possible mitigation schemes. In this paper, we present a qualitative and conceptual framework for understanding various regimes of edge/SOL turbulence and the role of turbulent transport as the mechanism for establishing the SOL heat flux width. Relevant considerations include the type and spectral characteristics of underlying instabilities, the location of the gradient drive relative to the SOL, the nonlinear saturation mechanism, and the parallel heat transport regime. We find a heat flux width scaling with major radius R that is generally positive, consistent with the previous findings [Connor et al., Nucl. Fusion 39, 169 (1999)]. The possible relationship of turbulence mechanisms to the neoclassical orbit width or heuristic drift mechanism in core energy confinement regimes known as low (L) mode and high (H) mode is considered, together with implications for the future experiments.
Turbulent transport regimes and the scrape-off layer heat flux width

International Nuclear Information System (INIS)

Myra, J. R.; D'Ippolito, D. A.; Russell, D. A.

2015-01-01

Understanding the responsible mechanisms and resulting scaling of the scrape-off layer (SOL) heat flux width is important for predicting viable operating regimes in future tokamaks and for seeking possible mitigation schemes. In this paper, we present a qualitative and conceptual framework for understanding various regimes of edge/SOL turbulence and the role of turbulent transport as the mechanism for establishing the SOL heat flux width. Relevant considerations include the type and spectral characteristics of underlying instabilities, the location of the gradient drive relative to the SOL, the nonlinear saturation mechanism, and the parallel heat transport regime. We find a heat flux width scaling with major radius R that is generally positive, consistent with the previous findings [Connor et al., Nucl. Fusion 39, 169 (1999)]. The possible relationship of turbulence mechanisms to the neoclassical orbit width or heuristic drift mechanism in core energy confinement regimes known as low (L) mode and high (H) mode is considered, together with implications for the future experiments
Transport barrier fluctuations governed by SOL turbulence spreading

International Nuclear Information System (INIS)

Ghendrih, Ph.; Sarazin, Y.; Ciraolo, G.; Darmet, G.; Garbet, X.; Grangirard, V.; Tamain, P.; Benkadda, S.; Beyer, P.

2007-01-01

Turbulence spreading, namely turbulent transport extending into a stable region is reported both for the flat density profiles in the far SOL and into a modeled H-mode barrier. It is shown that due to turbulence penetration, the pedestal width fluctuates and that its effective width is a factor 2 smaller than the linear predicted width. Turbulence overshooting throughout the pedestal leads to a non-vanishing turbulent transport within the barrier and provides a coupling of core and SOL turbulence despite the transport barrier
Effect of heating scheme on SOL width in DIII-D and EAST

Directory of Open Access Journals (Sweden)

L. Wang

2017-08-01

Full Text Available Joint DIII-D/EAST experiments in the radio-frequency (RF heated H-mode scheme with comparison to that of neutral beam (NB heated H-mode scheme were carried out on DIII-D and EAST under similar conditions to examine the effect of heating scheme on scrape-off layer (SOL width in H-mode plasmas for application to ITER. A dimensionally similar plasma equilibrium was used to match the EAST shape parameters. The divertor heat flux and SOL widths were measured with infra-red camera in DIII-D, while with divertor Langmuir probe array in EAST. It has been demonstrated on both DIII-D and EAST that RF-heated plasma has a broader SOL than NB-heated plasma when the edge electrons are effectively heated in low plasma current and low density regime with low edge collisionality. Detailed edge and pedestal profile analysis on DIII-D suggests that the low edge collisionality and ion orbit loss effect may account for the observed broadening. The joint experiment in DIII-D has also demonstrated the strong inverse dependence of SOL width on the plasma current in electron cyclotron heated (ECH H-mode plasmas.
Repair of glass by sol-gel coating using either conventional or microwave heating

International Nuclear Information System (INIS)

Boonyapiwat, A.; Fathi, Z.; Folz, D.C.; Clark, D.E.

1993-01-01

A method of repairing glass is discussed. Microindentation was used to deliberately weaken the glass. Some samples were dip coated with silica sol. Effects of dipping the glass in copper nitrate solution also were studied. Heat treatments were conducted in either a conventional furnace or a microwave oven. Four-point bend testing was used to evaluate the merit of each process. Microwave hybrid heating had the same effect on the repair of uncoated glass as conventional heating. Coating the glass with sol resulted in higher strength of glass than heat treatment alone. Treating the glass with copper nitrate without heat treating had no effect on strength. Microwave hybrid heating appears to yield higher reliability in sol-gel coated samples than conventional processing. 21 refs., 8 figs., 2 tabs
Investigation of a solar heating system for space heating and domestic hot water supply for Sol&Træ A.m.b.a

DEFF Research Database (Denmark)

Vejen, Niels Kristian

1999-01-01

A solar heating system for space heating and domestic hot water supply from "Sol&Træ A.m.b.a." was tested in a laboratory test facility.......A solar heating system for space heating and domestic hot water supply from "Sol&Træ A.m.b.a." was tested in a laboratory test facility....
Poloidal electric field and variation of radial transport during ICRF heating in the JET scrape-off layer

International Nuclear Information System (INIS)

Clement, S.; Tagle, J.A.; Bures, M.; Vince, J.; Kock, L. de; Stangeby, P.C.

1989-01-01

The highly anomalous perpendicular transport in the plasma edge of a tokamak is generally attributed to plasma turbulence, primarily to density and electrostatic potential fluctuations. The edge transport could be modified by changing the geometry of objects in contact with the plasma (limiters, radio frequency antennae ...) and during additional heating experiments. Poloidal asymmetries in the scrape-off layer (SOL) in tokamaks using poloidal limiters (eg. ALCATOR-C) have been recently reported, indicating a poloidal asymmetry in cross-field transport. A poloidal ring limiter obstructs communications between different flux tubes in the SOL, thus permitting poloidal asymmetries in n e and T e to develop if D perpendicular is θ-dependent. When JET was operated with discrete limiters, equivalent to a single toroidal limiter at the outside mid-plane, little poloidal variation in the SOL plasma properties was observed. Currently JET is operated with two complete toroidal belt limiters located approximately one meter above and below the outside mid-plane. This configuration breaks the SOL into two regions: the low field side SOL (LFS), between the limiters, and the rest of the SOL on the high field side (HFS). Differences on the scrape-off lengths in the two SOLs are reported here, indicating that cross-field transport is faster on the LFS-SOL, in agreement with observations made on ASDEX and T-10. (author) 8 refs., 6 figs
Recent progress towards a quantitative description of filamentary SOL transport

DEFF Research Database (Denmark)

Carralero, D.; Siccinio, M.; Komm, M.

2017-01-01

A summary of recent results on filamentary transport, mostly obtained with the ASDEX-Upgrade tokamak (AUG), is presented and discussed in an attempt to produce a coherent picture of scrape-off layer (SOL) filamentary transport. A clear correlation is found between L-mode density shoulder formation...... in the outer midplane and a transition between the sheath-limited and the inertial filamentary regimes. Divertor collisionality is found to be the parameter triggering the transition. A clear reduction of the ion temperature takes place in the far SOL after the transition, both for the background......-mode plasmas, although a secondary threshold related to deuterium fueling is observed. EMC3-EIRENE simulations of neutral dynamics show that an ionization front near the main chamber wall is formed after the shoulder formation. Finally, a clear increase of SOL opacity to neutrals is observed, associated...
Integrated core-SOL simulations of L-mode plasma in ITER and Indian demo

International Nuclear Information System (INIS)

Wisitsorasak, Apiwat; Onjun, Thawatchai; Kanjanaput, Wittawat

2015-01-01

Core-SOL simulations are carried out using 1.5D BALDUR integrated predictive modeling code to investigate tokamak plasma in ITER and Indian DEMO reactors operating in low confinement mode (L-Mode). In each simulation, the plasma current, temperature, and density profiles in both core and SOL region are evolved self-consistency. The SOL is simulated by integrating the fluid equations, including sources, along the field lines. The solutions in SOL subsequently provide as the boundary conditions of core plasma region on low-confinement mode. The core plasma transport model is described using a combination of anomalous transport by Multi-Mode-Model version 2001 (MMM2001) and neoclassical transport calculated by NCLASS module together with the toroidal velocity based on the torque due to Neoclassical Toroidal Viscosity (NTV). In addition, a sensitivity analysis is explored by varying plasma parameters, such as plasma density and auxiliary heating power. Furthermore, the ignition tests are conducted to observed plasma response in each design after shutting down an auxiliary heating. (author)
L-mode SOL width scaling in the MAST spherical tokamak

International Nuclear Information System (INIS)

Ahn, J-W; Counsell, G F; Kirk, A

2006-01-01

A new data-set of outboard mid-plane scrape-off layer (SOL) heat flux widths, Δ h , has been constructed for L-mode plasmas in the MAST spherical tokamak (ST). The scaling with key plasma parameters such as density, toroidal magnetic field, parallel connection length in the SOL and surface heat flux at the separatrix is investigated. An empirical scaling is developed for the Δ h data-set, which exhibits a strong positive dependence on both the connection length (or edge safety factor) and density and weak or moderate inverse dependences on the surface heat flux and magnetic field, respectively. The empirical scaling is compared with earlier results for a range of tokamaks with conventional geometry, which show weaker dependence on the density and edge safety factor. Importantly, however, the weak negative dependence on the surface heat flux (and thus heating power) is common in both conventional and ST geometries. The experimental data are also used to test a number of dimensionally correct Δ h scalings developed from theoretical models for perpendicular transport in the SOL coupled with classical transport parallel to the magnetic field. A scaling based on perpendicular transport driven by resistive MHD interchange provides the best fit, although several models are close. A subset of the better fitting theoretical scalings are used to extrapolate for Δ h in one design for a future burning ST machine and finally to predict the peak heat loading on the outboard divertor target plate
Coarse Grained Transport Model for Neutrals in Turbulent SOL Plasmas

Energy Technology Data Exchange (ETDEWEB)

Marandet, Y.; Mekkaoui, A.; Genesio, P.; Rosato, J.; Capes, H.; Godbert-Mouret, L.; Koubiti, M.; Stamm, R., E-mail: yannick.marandet@univ-amu.fr [PIIM, CNRS/Aix-Marseille University, Marseille (France); Reiter, D.; Boerner, P. [IEK4, FZJ, Juelich (Germany)

2012-09-15

Full text: Edge plasmas of magnetic fusion devices exhibit strong intermittent turbulence, which governs perpendicular transport of particles and heat. Turbulent fluxes result from the coarse graining procedure used to derive the transport equation, which entails time averaging of the underlying equations governing the turbulent evolution of the electron and ion fluids. In previous works, we have pointed out that this averaging is not carried out on the Boltzmann equation that describes the transport of neutral particles (atoms, molecules) in current edge code suites (such as SOLPS). Since fluctuations in the far SOL are of order unity, calculating the transport of neutral particles, hence the source terms in plasma fluid equations, in the average plasma background might lead to misleading results. In particular, retaining the effects of fluctuations could affect the estimation of the importance of main chamber recycling, hence first wall sputtering by charge exchange atoms, as well as main chamber impurity contamination and transport. In this contribution, we obtain an exact coarse-grained equation for the average neutral density, assuming that density fluctuations are described by multivariate Gamma statistics. This equation is a scattering free Boltzmann equation, where the ionization rate has been renormalized to account for fluctuations. The coarse grained transport model for neutrals has been implemented in the EIRENE code, and applications in 2D geometry with ITER relevant plasma parameters are presented. Our results open the way for the implementation of the effects of turbulent fluctuations on the transport of neutral particles in coupled plasma/neutral edge codes like B2-EIRENE. (author)
Far SOL transport and main wall plasma interaction in DIII-D

International Nuclear Information System (INIS)

Rudakov, D.L.; Boedo, J.A.; Moyer, R.A.; Doerner, R.P.; Hollmann, E.M.; Krasheninnikov, S.I.; Pigarov, A.Yu.; Stangeby, P.C.; McLean, A.G.; Watkins, J.G.; Wampler, W.R.; Whyte, D.G.; McKee, G.R.; Zeng, L.; Wang, G.; Brooks, N.H.; Evans, T.E.; Leonard, A.W.; Mahdavi, M.A.; West, W.P.; Wong, C.P.C.; Fenstermacher, M.E.; Groth, M.; Lasnier, C.J.

2005-01-01

Far scrape-off layer (SOL) and near-wall plasma parameters in DIII-D depend strongly on the discharge parameters and confinement regime. In L-mode discharges cross-field transport increases with the average discharge density and flattens far SOL profiles, thus increasing plasma-wall contact. In H-mode between edge localized modes (ELMs), plasma-wall contact is generally weaker than in L-mode. During ELMs plasma fluxes to the wall increase to, or above the L-mode levels. Depending on the discharge conditions ELMs are responsible for 30-90% of the ion flux to the outboard chamber wall. Cross-field fluxes in far SOL are dominated by large amplitude intermittent transport events that may propagate all the way to the outer wall and cause sputtering. A Divertor Material Evaluation System (DiMES) probe containing samples of several ITER-relevant materials including carbon, beryllium and tungsten was exposed to a series of upper single null (USN) discharges as a proxy to measure the first wall erosion. (author)
ELECTRON TEMPERATURE FLUCTUATIONS AND CROSS-FIELD HEAT TRANSPORT IN THE EDGE OF DIII-D

International Nuclear Information System (INIS)

RUDAKOV, DL; BOEDO, JA; MOYER, RA; KRASENINNIKOV, S; MAHDAVI, MA; McKEE, GR; PORTER, GD; STANGEBY, PC; WATKINS, JG; WEST, WP; WHYTE, DG.

2003-01-01

OAK-B135 The fluctuating E x B velocity due to electrostatic turbulence is widely accepted as a major contributor to the anomalous cross-field transport of particles and heat in the tokamak edge and scrape-off layer (SOL) plasmas. This has been confirmed by direct measurements of the turbulent E x B transport in a number of experiments. Correlated fluctuations of the plasma radial velocity v r , density n, and temperature T e result in time-average fluxes of particles and heat given by (for electrons): Equation 1--Λ r ES = r > = 1/B varφ θ ; Equation 2--Q r ES = e (tilde v) r > ∼ 3/2 kT e Λ r ES + 3 n e /2 B varφ e (tilde E) θ > Q conv + Q cond . The first term in Equation 2 is referred to as convective and the second term as conductive heat flux. Experimental determination of fluxes given by Equations 1 and 2 requires simultaneous measurements of the density, temperature and poloidal electric field fluctuations with high spatial and temporal resolution. Langmuir probes provide most readily available (if not the only) tool for such measurements. However, fast measurements of electron temperature using probes are non-trivial and are not always performed. Thus, the contribution of the T e fluctuations to the turbulent fluxes is usually neglected. Here they report results of the studies of T e fluctuations and their effect on the cross-field transport in the SOL of DIII-D
Understanding the SOL flow in L-mode plasma on divertor tokamaks, and its influence on the plasma transport

International Nuclear Information System (INIS)

Asakura, Nobuyuki

2007-01-01

Significant progress has been made in understanding the driving mechanisms in SOL mass transport along the magnetic field lines (SOL flow). SOL flow measurements by Mach probes and impurity plume have been performed in L-mode plasma at various poloidal locations in divertor tokamaks. All results showed common SOL flow patterns: subsonic flow with parallel Mach number (M parallel ) of 0.2-1 was generated from the Low-Field-Side (LFS) SOL to the High-Field-Side (HFS) divertor for the ion ∇B drift towards the divertor. The SOL flow pattern was formed mainly by LFS-enhanced asymmetry in diffusion and by classical drifts. In addition, divertor detachment and/or intense puffing-and-pump enhanced the HFS SOL flow. Most codes have incorporated drift effects, and asymmetric diffusion was modelled to simulate the fast SOL flow. Influences of the fast SOL flow on the impurity flow in the SOL, shielding from core plasma, and deposition profile, were directly observed in experiments
The role of drifts in the plasma transport at the tokamak core–SOL interface

Energy Technology Data Exchange (ETDEWEB)

Chankin, A.V., E-mail: Alex.Chankin@ipp.mpg.de [Max-Planck-Institut für Pasmaphysik, EURATOM Association, 85748 Garching (Germany); Coster, D.P. [Max-Planck-Institut für Pasmaphysik, EURATOM Association, 85748 Garching (Germany)

2013-07-15

The interface between the core (inside the magnetic separatrix in X-point configurations) and the scrape-off layer (SOL) of tokamaks is a delicate region of the magnetic topology transition from closed to open field lines where neither the standard neoclassical theory nor the SOL physics fully apply. Sharp gradients of plasma parameters in the outer core, caused by the proximity of divertor sinks in the near SOL, invalidate some ordering assumptions of the neoclassical theory. At the same time, the existence of closed flux surfaces in the core enforces ambipolarity of radial plasma flows, in difference to the situation in the SOL where the current loop may close through the divertor. Detailed analysis of the plasma transport and flows with the emphasis on the outer core region, just inside the separatrix, is carried out in the paper, based on EDGE2D modelling and analytical formulas.
Soc dynamics in a 2D model of turbulent particle transport in the sol

International Nuclear Information System (INIS)

Ghendrih, Ph.; Sarazin, Y.

1998-01-01

Interchange turbulence in two-dimensions is investigated in the Scrape-Off Layer of fusion devices, when driven by a constant core particle influx. Contrary to the standard gradient driven approach, density is allowed to fluctuate around its average profile. Transverse transport exhibits some of the features of Self-organised Critical systems, namely, inward and outward avalanches, together with a frequency spectrum decrease in 1 / f and f -2 at intermediate and high frequencies respectively. An avalanches occurs when follows the large radial structures of the electric potential. As experimentally, the radial profile of density relative fluctuations decreases from the wall into the core plasma, while that of density relative fluctuations peaks inside the SOL. Equilibrium density exhibits the experimental exponential decrease. An analytical expression of the SOL width Δ SOL is obtained, which maximizes the linear growth rate, when the poloidal modulation of electric potential equilibrium is taken into account. The parametric dependence of Δ SOL well agrees with experimental data. (authors)
Density limit and cross-field edge transport scaling in Alcator C-Mod

International Nuclear Information System (INIS)

LaBombard, B.

2002-01-01

Experiments in Alcator C-Mod have uncovered a direct link between the character and scaling of edge transport and the empirical Greenwald density limit (n G ). In low to moderate density discharges, the scrape-off layer (SOL) exhibits a two-layer structure: a near SOL (∼5 mm zone) with steep density and temperature gradients and a far SOL with flatter profiles. In the far SOL, the transport fluxes exhibit large transport events ('bursts' which carry particles to main-chamber structures. In the near SOL, transport fluxes appear to be less 'bursty' particle diffusivities in this region is found to increase strongly with local plasma collisionality. As n/n G (or collisionality) is raised, cross-field heat convection begins to compete with parallel conduction to the divertor. At N/n G ∼0.5, T E at the separatrix is reduced. As n/n G approaches ∼1, regions inside the separatrix exhibit flatter profiles with 'bursty' transport behavior; cross-field heat convection to main-chamber structures becomes comparable to the radiated power. Thus as n/n G is increased, cross-field edge transport physics progressively changes, ultimately impacting the power balance of the discharge near N/n G ∼1. (author)

Analysis and theory of gas transport in microporous sol-gel derived ceramic membranes

NARCIS (Netherlands)

de Lange, R.S.A.; de Lange, Rob; Keizer, Klaas; Burggraaf, Anthonie; Burggraaf, A.J.

1995-01-01

Sol-gel modification of mesoporous alumina membranes is a very successful technique to improve gas separation performance. Due to the formed microporous top layer, the membranes show activated transport and molecular sieve-like separation factors. This paper concentrates on the mechanism of
SolNet

DEFF Research Database (Denmark)

Jordan, Ulrike; Vajen, Klaus; Bales, Chris

2014-01-01

-accompanying Master courses, placements of internships, and PhD scholarship projects. A new scholarship project, “SHINE”, was launched in autumn 2013 in the frame work of the Marie Curie program of the European Union (Initial Training Network, ITN). 13 PhD-scholarships on solar district heating, solar heat......SolNet, founded in 2006, is the first coordinated International PhD education program on Solar Thermal Engineering. The SolNet network is coordinated by the Institute of Thermal Engineering at Kassel University, Germany. The network offers PhD courses on solar heating and cooling, conference...... for industrial processes, as well as sorption stores and materials started in December 2013. Additionally, the project comprises a training program with five PhD courses and several workshops on solar thermal engineering that will be open also for other PhD students working in the field. The research projects...
Implications of high density operation on SOL transport: A multimachine investigation

Czech Academy of Sciences Publication Activity Database

Carralero, D.; Müller, H.W.; Groth, M.; Komm, Michael; Adámek, Jiří; Birkenmeier, G.; Brix, M.; Janky, Filip; Háček, Pavel; Marsen, S.; Reimold, F.; Silva, C.; Stroth, U.; Wischmeier, M.; Wolfrum, E.

2015-01-01

Roč. 463, August (2015), s. 123-127 ISSN 0022-3115. [PLASMA-SURFACE INTERACTIONS 21: International Conference on Plasma-Surface Interactions in Controlled Fusion Devices. Kanazawa, 26.05.2014-30.05.2014] Institutional support: RVO:61389021 Keywords : SOL transport * tokamak * COMPASS Subject RIV: JF - Nuclear Energetics OBOR OECD: Nuclear related engineering Impact factor: 2.199, year: 2015 http://www.sciencedirect.com/science/article/pii/S002231151400703X
Density limit and cross-field edge transport scaling in Alcator C-Mod

International Nuclear Information System (INIS)

LaBombard, B.; Greenwald, M.; Hughes, J.W.; Lipschultz, B.; Mossessian, D.; Terry, J.L.; Boivin, R.L.; Carreras, B.A.; Pitcher, C.S.; Zweben, S.J.

2003-01-01

Recent experiments in Alcator C-Mod have uncovered a direct link between the character and scaling of cross-field particle transport in the edge plasma and the density limit, n G . As n-bar e /n G is increased from low values to values approaching ∼1, an ordered progression in the cross-field edge transport physics occurs: first benign cross-field heat convection, then cross-field heat convection impacting the scrape-off layer (SOL) power loss channels and reducing the separatrix electron temperature, and finally 'bursty' transport (normally associated with the far SOL) invading into closed flux surface regions and carrying a convective power loss that impacts the power balance of the discharge. These observations suggest that SOL transport and its scaling with plasma conditions plays a key role in setting the empirically observed density limit scaling law. (author)
Recent progress towards a quantitative description of filamentary SOL transport

Czech Academy of Sciences Publication Activity Database

Carralero, D.; Siccinio, M.; Komm, Michael; Artene, S.A.; D’Isa, F.A.; Adámek, Jiří; Aho-Mantila, L.; Birkenmeier, G.; Brix, M.; Fuchert, G.; Groth, M.; Lunt, T.; Manz, P.; Madsen, J.; Marsen, S.; Müller, H.W.; Stroth, U.; Sun, H.J.; Vianello, N.; Wischmeier, M.; Wolfrum, E.

2017-01-01

Roč. 57, č. 5 (2017), č. článku 056044. ISSN 0029-5515. [IAEA Fusion Energy Conference/26./. Kyoto, 17.10.2016-22.10.2016] EU Projects: European Commission(XE) 633053 - EUROfusion Institutional support: RVO:61389021 Keywords : ASDEX-Upgrade * SOL transport * filaments * main wall recycling Subject RIV: BL - Plasma and Gas Discharge Physics OBOR OECD: Fluids and plasma physics (including surface physics) Impact factor: 3.307, year: 2016 http://iopscience.iop.org/article/10.1088/1741-4326/aa64b3
Paleoclassical electron heat transport

International Nuclear Information System (INIS)

Callen, J.D.

2005-01-01

Radial electron heat transport in low collisionality, magnetically-confined toroidal plasmas is shown to result from paleoclassical Coulomb collision processes (parallel electron heat conduction and magnetic field diffusion). In such plasmas the electron temperature equilibrates along magnetic field lines a long length L, which is the minimum of the electron collision length and a maximum effective half length of helical field lines. Thus, the diffusing field lines induce a radial electron heat diffusivity M ≅ L/(πR 0q ) ∼ 10 >> 1 times the magnetic field diffusivity η/μ 0 ≅ ν e (c/ω p ) 2 . The paleoclassical electron heat flux model provides interpretations for many features of 'anomalous' electron heat transport: magnitude and radial profile of electron heat diffusivity (in tokamaks, STs, and RFPs), Alcator scaling in high density plasmas, transport barriers around low order rational surfaces and near a separatrix, and a natural heat pinch (or minimum temperature gradient) heat flux form. (author)
Core-SOL modelling of neon seeded JET discharges with the ITER-like wall

Energy Technology Data Exchange (ETDEWEB)

Telesca, G. [Department of Applied Physics, Ghent University (Belgium); EUROfusion Consortium, JET, Culham Science Centre, Abingdon (United Kingdom); Ivanova-Stanik, I.; Zagoerski, R.; Czarnecka, A. [Institute of Plasma Physics and Laser Microfusion, Warsaw (Poland); EUROfusion Consortium, JET, Culham Science Centre, Abingdon (United Kingdom); Brezinsek, S.; Huber, A.; Wiesen, S. [Forschungszentrum Juelich GmbH, Institut fuer Klima- und Energieforschung-Plasmaphysik, Juelich (Germany); EUROfusion Consortium, JET, Culham Science Centre, Abingdon (United Kingdom); Drewelow, P. [Max-Planck-Institut fuer Plasmaphysik, Greifswald (Germany); EUROfusion Consortium, JET, Culham Science Centre, Abingdon (United Kingdom); Giroud, C. [CCFE Culham, Abingdon (United Kingdom); EUROfusion Consortium, JET, Culham Science Centre, Abingdon (United Kingdom); Collaboration: JET EFDA contributors

2016-08-15

Five ELMy H-mode Ne seeded JET pulses have been simulated with the self-consistent core-SOL model COREDIV. In this five pulse series only the Ne seeding rate was changed shot by shot, allowing a thorough study of the effect of Ne seeding on the total radiated power and of its distribution between core and SOL tobe made. The increase in the simulations of the Ne seeding rate level above that achieved in experiments shows saturation of the total radiated power at a relatively low radiated-heating power ratio (f{sub rad} = 0.60) and a further increase of the ratio of SOL to core radiation, in agreement with the reduction of W release at high Ne seeding level. In spite of the uncertainties caused by the simplified SOL model of COREDIV (neutral model, absence of ELMs and slab model for the SOL), the increase of the perpendicular transport in the SOL with increasing Ne seeding rate, which allows to reproduce numerically the experimental distribution core-SOL of the radiated power, appears to be of general applicability. (copyright 2016 The Authors. Contributions to Plasma Physics published by Wiley-VCH Verlag GmbH and Co. KGaA Weinheim. This)
Non-axisymmetric SOL-transport study for tokamaks and stellarators

International Nuclear Information System (INIS)

Sardei, F.; Feng, Y.; Kisslinger, J.; Grigull, P.; Kobayashi, M.; Harting, D.; Reiter, D.; Federici, G.; Loarte, A.

2007-01-01

The paper addresses basic features of non-axisymmetric edge transport induced in tokamaks by local limiters or external magnetic perturbations and in low-shear stellarators by the presence of edge magnetic islands. 3D simulations and, if available for comparison, experimental results are presented and discussed for three devices, ITER during start-up operation, TEXTOR-DED and W7-AS, having edge topologies totally different from each other. The modeling is performed with the EMC3/EIRENE code, which treats self-consistently plasma, neutral and impurity transport in a general 3D scrape-off layer (SOL) with arbitrarily complex geometry of magnetic configuration and plasma-facing components. Shown are code predictions of the power load on the ITER start-up limiters as well as modeling results on the transport in the TEXTOR-DED stochastic edge and on the physics of stable detachment in W7-AS. Experimental observations confirming the code simulations are referenced for both TEXTOR-DED and W7-AS, a direct comparison between modeling and experimental results is shown for W7-AS
2005 Tour de Sol: The Sustainable Energy and Transportation Festival and Competition

Energy Technology Data Exchange (ETDEWEB)

Nancy Hazard

2005-05-07

This report gives a summary of the 2005Tour de Sol: The Sustainable Energy and Transportation Festival and Competition. It lists our objectives, what we did, and an analysis of how we met our objectives. An 80-page report with a list of verified print, radio and TV media coverage, and copies of selected news clips and web media coverage is available at the NESEA office for review.
Modeling SOL evolution during disruptions

International Nuclear Information System (INIS)

Rognlien, T.D.; Cohen, R.H.; Crotinger, J.A.

1996-01-01

We present the status of our models and transport simulations of the 2-D evolution of the scrape-off layer (SOL) during tokamak disruptions. This evolution is important for several reasons: It determines how the power from the core plasma is distributed on material surfaces, how impurities from those surfaces or from gas injection migrate back to the core region, and what are the properties of the SOL for carrying halo currents. We simulate this plasma in a time-dependent fashion using the SOL transport code UEDGE. This code models the SOL plasma using fluid equations of plasma density, parallel momentum (along the magnetic field), electron energy, ion energy, and neutral gas density. A multispecies model is used to follow the density of different charge-states of impurities. The parallel transport is classical but with kinetic modifications; these are presently treated by flux limits, but we have initiated more sophisticated models giving the correct long-mean-free path limit. The cross-field transport is anomalous, and one of the results of this work is to determine reasonable values to characterize disruptions. Our primary focus is on the initial thermal quench phase when most of the core energy is lost, but the total current is maintained. The impact of edge currents on the MHD equilibrium will be discussed
Heat transfer in solids using infrared photothermal radiometry and simulation by Com sol multi physics

International Nuclear Information System (INIS)

Suarez, V.; Hernandez W, J.; Calderon, A.; Rojas T, J. B.; Juarez, A. G.; Marin, E.; Castaneda, A.

2012-10-01

We investigate the heat transfer through a homogeneous and isotropic solid exited by periodic light beam on its front surface. For this, we use the infrared photothermal radiometry in order to obtain the evolution of the temperature difference on the rear surface of the silicon sample as a function of the exposure time. Also, we solved the heat conduction equation for this problem with the boundary conditions congruent with the physical situation, by means of application the Com sol multi physics software and the heat transfer module. Our results show a good agree between the experimental and simulated results, which demonstrate the utility of this methodology in the study of the thermal response in solids. (Author)
SiO2 sol-gel films after ammonia and heat two-step treatments

International Nuclear Information System (INIS)

Zhang Chunlai; Wang Biyi; Tian Dongbin; Yin Wei; Jiang Xiaodong; Yuan Xiaodong; Yan Lianghong; Zhang Hongliang; Zhao Songnan; Lv Haibing

2008-01-01

SiO 2 thin films were deposited using tetraethoxylsilane as precursor, ammonia as catalyst on K9 glass by sol-gel method. These films were post-treated by ammonia and heat. The properties of the coatings were characterized by ellipsometer, UV-vis spectrophotometry, FTIR-spectroscopy, scanning probe microscope and contact angle measurement apparatus. The resuits indicate that the thickness of the films with ammonia and heat treatment tend to decrease. Both the refractive index and water contact angle increase after ammonia treatment. However, they both decrease after heat treatment. The former increases by 0.236 for the first step, then decreases by 0.202 for the second. The latter increases to 58.92 degree, then decreases to 38.07 degree. The transmittance of the coatings turn to be better and continuously shift to short wave by UV-vis spectrophotometry. The surface becomes smoother by AFM after the two-step treatment. (authors)
Fast dynamics of Type I ELM and transport of ELM pulse in JT-60U

International Nuclear Information System (INIS)

Oyama, N.

2002-01-01

The mitigation of the large ELM heat load on the divertor target is one of the most important issues to be overcome on ITER. Since the ELM heat load strikes the divertor target not as a time-averaged load but as an instantaneous heat pulse, the evaluation of both ELM energy, and the time scale of the collapse and transport is very important. In JT-60U, the detailed dynamic behaviors of the collapse were measured using O-mode reflectometer. The duration of the collapse was within 0.35 ms and the lost pedestal density was recovered quickly within 0.5 ms. The collapse reached 10 cm inside the separatrix, which corresponds to twice the pedestal width of 5 cm. Dedicated edge density measurements on high- and low-field side revealed the poloidal asymmetry of the collapse of density pedestal for the first time. The measurement of SOL flow and heat load to the divertor target by using SOL Mach probe and IRTV showed that convective transport of the SOL plasma gave large contribution to the ELM heat deposition process. (author)
Collisionality dependent transport in TCV SOL plasmas

DEFF Research Database (Denmark)

Garcia, Odd Erik; Pitts, R.A.; Horacek, J.

2007-01-01

Results are presented from probe measurements in the low field side scrape-off layer (SOL) region of TCV during plasma current scan experiments. It is shown that with decreasing plasma current the radial particle density profile becomes broader and the fluctuation levels and turbulence driven...... radial particle flux increase. In the far SOL the fluctuations exhibit a high degree of statistical similarity and the particle density and flux at the wall radius scale inversely with the plasma current. Together with previous TCV density scan experiments, this indicates that plasma fluctuations...
Heat transport and storage

International Nuclear Information System (INIS)

Despois, J.

1977-01-01

Recalling the close connections existing between heat transport and storage, some general considerations on the problem of heat distribution and transport are presented 'in order to set out the problem' of storage in concrete form. This problem is considered in its overall plane, then studied under the angle of the different technical choices it involves. The two alternatives currently in consideration are described i.e.: storage in a mined cavity and underground storage as captive sheet [fr
Driving mechanism of SOL plasma flow and effects on the divertor performance in JT-60U

International Nuclear Information System (INIS)

Asakura, N.

2002-01-01

SOL plasma flow plays an important role in the plasma transport along the field lines, and influences control of the divertor plasma and impurity ions. Recently, mechanisms producing the SOL flow such as drifts produced by electric field and pressure gradient are pointed out. In JT-60U, three reciprocating Mach probes were installed at the high-field-side (HFS) baffle, low-field-side (LFS) midplane and just below the X-point. The measurements of the SOL flow and plasma profiles both at the HFS and LFS, for the first time, found out the SOL flow pattern and its driving mechanism. 'Flow reversal' was found near the separatrix of the HFS and LFS. Radial profiles of the SOL flow were similar to those calculated numerically using the UEDGE code with the plasma drifts included. SOL particle fluxes towards the HFS and LFS divertors were, for the first time, evaluated. Important physics issues for the divertor design and operation, such as in-out asymmetries of the heat and particle fluxes, and control of impurity ions with intense gas puff and divertor pump (puff and pump), were investigated. (author)
Physics and modelling of scrape-off layer transport

International Nuclear Information System (INIS)

Cohen, R.H.; Allen, S.L.; Crotinger, J.A.; Kaiser, T.B.; Milovich, J.L.; Mattor, N.; Nevins, W.M.; Porter, G.D.; Rensink, M.E.; Rognlien, T.D.; Berk, H.L.; Diamond, P.H.; Rosenbluth, M.N.; Hinton, F.L.; Staebler, G.M.; Knoll, D.A.; Modi, B.; Xu, X.Q.; Prinja, A.K.; Ryutov, D.D.; Tsidulko, Y.A.

1992-01-01

We present studies of three schemes for reducing the peak heat flux on divertor plates, divertor biasing, impurity injection (''radiative divertor'') and neutral gas injection (''gas target divertor''). We report on theoretical analysis of a likely source of turbulent transport in the SOL and incorporation of the resultant transport coefficients into self-consistent models
Bursty fluctuation characteristics in SOL/divertor plasmas of large helical device

International Nuclear Information System (INIS)

Ohno, N.

2006-01-01

Full text: Fluctuation properties in the SOL plasmas were intensively studied to understand the crossfield plasma transport, which determines the SOL structure and heat/particle deposition onto the first wall. Recent studies in tokamaks showed that the SOL density fluctuation is highly intermittent. Convective cross-field transport associated with the intermittent events would have strong influence on recycling processes and impurity generation from the first wall. On the other hand, in helical devices, there are few systematic studies on the SOL fluctuation property focusing on the intermittent bursty fluctuations related to plasma blob transport. Recent theory predicts that the blobs propagate toward a low field side in tokamaks. On the other hand, in the Large Helical Device (LHD), the direction of the gradient in B is not uniform because the high-field and the low-field sides rotates poloidally along the torus in the helical system. Comparison between the intermittent bursty fluctuations in the edge plasma of tokamaks and helical devices makes it possible to understand the essential physics of the blob transport. Recently, fast camera observation showed the radial motion of filaments in the edge of the LHD, suggesting the convective cross-field transport. In this paper, bursty fluctuation properties in the edge of the LHD have been investigated by analyzing the ion saturation currents measured with a probe array embedded in an outboard divertor plate. Statistical analysis based on probability distribution function was employed to determine the intermittent evens in the density fluctuation. Large positive bursty events were often observed in the ion saturation current measured with a divertor probe near a divertor leg at which the magnetic line of force connected to the area of a low-field side with a short connection length. Condition averaging result of the positive bursty events indicates the intermittent feature with a rapid increase and a slow decay is
Numerical investigation of edge plasma phenomena in an enhanced D-alpha discharge at Alcator C-Mod: Parallel heat flux and quasi-coherent edge oscillations

International Nuclear Information System (INIS)

Russell, D. A.; D’Ippolito, D. A.; Myra, J. R.; LaBombard, B.; Terry, J. L.; Zweben, S. J.

2012-01-01

Reduced-model scrape-off layer turbulence (SOLT) simulations of an enhanced D-alpha (EDA) H-mode shot observed in the Alcator C-Mod tokamak were conducted to compare with observed variations in the scrape-off-layer (SOL) width of the parallel heat flux profile. In particular, the role of the competition between sheath- and conduction-limited parallel heat fluxes in determining that width was studied for the turbulent SOL plasma that emerged from the simulations. The SOL width decreases with increasing input power and with increasing separatrix temperature in both the experiment and the simulation, consistent with the strong temperature dependence of the parallel heat flux in balance with the perpendicular transport by turbulence and blobs. The particularly strong temperature dependence observed in the case analyzed is attributed to the fact that these simulations produce SOL plasmas which are in the conduction-limited regime for the parallel heat flux. A persistent quasi-coherent (QC) mode dominates the SOLT simulations and bears considerable resemblance to the QC mode observed in C-Mod EDA operation. The SOLT QC mode consists of nonlinearly saturated wave-fronts located just inside the separatrix that are convected poloidally by the mean flow, continuously transporting particles and energy and intermittently emitting blobs into the SOL.
Sol-gel applications for ceramic membrane preparation

Science.gov (United States)

Erdem, I.

2017-02-01

Ceramic membranes possessing superior properties compared to polymeric membranes are more durable under severe working conditions and therefore their service life is longer. The ceramic membranes are composed of some layers. The support is the layer composed of coarser ceramic structure and responsible for mechanical durability under filtration pressure and it is prepared by consolidation of ceramic powders. The top layer is composed of a finer ceramic micro-structure mainly responsible for the separation of components present in the fluid to be filtered and sol-gel method is a versatile tool to prepare such a tailor-made ceramic filtration structure with finer pores. Depending on the type of filtration (e.g. micro-filtration, ultra-filtration, nano-filtration) aiming separation of components with different sizes, sols with different particulate sizes should be prepared and consolidated with varying precursors and preparation conditions. The coating of sol on the support layer and heat treatment application to have a stable ceramic micro-structure are also important steps determining the final properties of the top layer. Sol-gel method with various controllable parameters (e.g. precursor type, sol formation kinetics, heat treatment conditions) is a practical tool for the preparation of top layers of ceramic composite membranes with desired physicochemical properties.

Sol-gel derived sorbents

Science.gov (United States)

Sigman, Michael E.; Dindal, Amy B.

2003-11-11

Described is a method for producing copolymerized sol-gel derived sorbent particles for the production of copolymerized sol-gel derived sorbent material. The method for producing copolymerized sol-gel derived sorbent particles comprises adding a basic solution to an aqueous metal alkoxide mixture for a pH.ltoreq.8 to hydrolyze the metal alkoxides. Then, allowing the mixture to react at room temperature for a precalculated period of time for the mixture to undergo an increased in viscosity to obtain a desired pore size and surface area. The copolymerized mixture is then added to an immiscible, nonpolar solvent that has been heated to a sufficient temperature wherein the copolymerized mixture forms a solid upon the addition. The solid is recovered from the mixture, and is ready for use in an active sampling trap or activated for use in a passive sampling trap.
Fast-wave power flow along SOL field lines in NSTX and the associated power deposition profile across the SOL in front of the antenna

International Nuclear Information System (INIS)

Perkins, R.J.; Bell, R.E.; Diallo, A.; Gerhardt, S.; Hosea, J.C.; Jaworski, M.A.; LeBlanc, B.P.; Kramer, G.J.; Maingi, R.; Phillips, C.K.; Podestà, M.; Roquemore, L.; Scotti, F.; Ahn, J.-W.; Gray, T.K.; Green, D.L.; McLean, A.; Ryan, P.M.; Jaeger, E.F.; Sabbagh, S.

2013-01-01

Fast-wave heating and current drive efficiencies can be reduced by a number of processes in the vicinity of the antenna and in the scrape-off layer (SOL). On NSTX from around 25% to more than 60% of the high-harmonic fast-wave power can be lost to the SOL regions, and a large part of this lost power flows along SOL magnetic field lines and is deposited in bright spirals on the divertor floor and ceiling. We show that field-line mapping matches the location of heat deposition on the lower divertor, albeit with a portion of the heat outside of the predictions. The field-line mapping can then be used to partially reconstruct the profile of lost fast-wave power at the midplane in front of the antenna, and the losses peak close to the last closed flux surface as well as the antenna. This profile suggests a radial standing-wave pattern formed by fast-wave propagation in the SOL, and this hypothesis will be tested on NSTX-U. RF codes must reproduce these results so that such codes can be used to understand this edge loss and to minimize RF heat deposition and erosion in the divertor region on ITER. (paper)
Vanadium dioxide formed by the sol-gel process

International Nuclear Information System (INIS)

Potember, R.S.; Speck, K.R.; Hu, H.S.

1990-01-01

This patent describes a process for the deposition of a crystalline vanadium dioxide thin film. It comprises: providing a solution comprising a vanadium tetraalkoxide and solvent; allowing hydrolysis and condensation reactions to progressively form a homogeneous sol from the solution, applying a coating of the sol to the substrate; allowing a gel to form from the sol on the substrate by evaporating the solvent; dehydrating the gel by heat treatment under an inert atmosphere to form the crystalline vanadium dioxide film
Radiative and SOL experiments in open and baffled divertors on DIII-D

International Nuclear Information System (INIS)

Allen, S.L.; Brooks, N.H.; Bastasz, R.

1998-11-01

The authors present recent progress towards an understanding of the physical processes in the divertor and scrape-off-layer (SOL) plasmas in DIII-D. This has been made possible by a combination of new diagnostics, improved computational models, and changes in divertor geometry. They have focused primarily on ELMing H-mode discharges. The physics of Partially Detached Divertor (PDD) plasmas, with divertor heat flux reduction by divertor radiation enhancement using D 2 puffing, has been studied in 2-D, and a model of the heat and particle transport has been developed that includes conduction, convection, ionization, recombination, and flows. Plasma and impurity particle flows have been measured with Mach probes and spectroscopy and these flows have been compared with the UEDGE model. The model now includes self-consistent calculations of carbon impurities. Impurity radiation has been increased in the divertor and SOL with puff and pump techniques using SOL D 2 puffing, divertor cryopumping, and argon puffing. The important physical processes in plasma-wall interactions have been examined with a DiMES probe, plasma characterization near the divertor plate, and the REDEP code. Experiments comparing single-null (SN) plasma operation in baffled and open divertors have demonstrated a change in the edge plasma profiles. These results are consistent with a reduction in the core ionization source calculated with UEDGE. Divertor particle control in ELMing H-mode with pumping and baffling has resulted in reduction in H-mode core densities to n e /n gw ∼ 0.25. Divertor particle exhaust and heat flux has been studied as the plasma shape was varied from a lower SN, to a balanced double null (DN), and finally to an upper SN
SEAWAT-based simulation of axisymmetric heat transport.

Science.gov (United States)

Vandenbohede, Alexander; Louwyck, Andy; Vlamynck, Nele

2014-01-01

Simulation of heat transport has its applications in geothermal exploitation of aquifers and the analysis of temperature dependent chemical reactions. Under homogeneous conditions and in the absence of a regional hydraulic gradient, groundwater flow and heat transport from or to a well exhibit radial symmetry, and governing equations are reduced by one dimension (1D) which increases computational efficiency importantly. Solute transport codes can simulate heat transport and input parameters may be modified such that the Cartesian geometry can handle radial flow. In this article, SEAWAT is evaluated as simulator for heat transport under radial flow conditions. The 1971, 1D analytical solution of Gelhar and Collins is used to compare axisymmetric transport with retardation (i.e., as a result of thermal equilibrium between fluid and solid) and a large diffusion (conduction). It is shown that an axisymmetric simulation compares well with a fully three dimensional (3D) simulation of an aquifer thermal energy storage systems. The influence of grid discretization, solver parameters, and advection solution is illustrated. Because of the high diffusion to simulate conduction, convergence criterion for heat transport must be set much smaller (10(-10) ) than for solute transport (10(-6) ). Grid discretization should be considered carefully, in particular the subdivision of the screen interval. On the other hand, different methods to calculate the pumping or injection rate distribution over different nodes of a multilayer well lead to small differences only. © 2013, National Ground Water Association.
A simple Boltzmann transport equation for ballistic to diffusive transient heat transport

International Nuclear Information System (INIS)

Maassen, Jesse; Lundstrom, Mark

2015-01-01

Developing simplified, but accurate, theoretical approaches to treat heat transport on all length and time scales is needed to further enable scientific insight and technology innovation. Using a simplified form of the Boltzmann transport equation (BTE), originally developed for electron transport, we demonstrate how ballistic phonon effects and finite-velocity propagation are easily and naturally captured. We show how this approach compares well to the phonon BTE, and readily handles a full phonon dispersion and energy-dependent mean-free-path. This study of transient heat transport shows (i) how fundamental temperature jumps at the contacts depend simply on the ballistic thermal resistance, (ii) that phonon transport at early times approach the ballistic limit in samples of any length, and (iii) perceived reductions in heat conduction, when ballistic effects are present, originate from reductions in temperature gradient. Importantly, this framework can be recast exactly as the Cattaneo and hyperbolic heat equations, and we discuss how the key to capturing ballistic heat effects is to use the correct physical boundary conditions
One-Loop Operation of Primary Heat Transport System in MONJU During Heat Transport System Modifications

International Nuclear Information System (INIS)

Goto, T.; Tsushima, H.; Sakurai, N.; Jo, T.

2006-01-01

MONJU is a prototype fast breeder reactor (FBR). Modification work commenced in March 2005. Since June 2004, MONJU has changed to one-loop operation of the primary heat transport system (PHTS) with all of the secondary heat transport systems (SHTS) drained of sodium. The purposes of this change are to shorten the modification period and to reduce the cost incurred for circuit trace heating electrical consumption. Before changing condition, the following issues were investigated to show that this mode of operation was possible. The heat loss from the reactor vessel and the single primary loop must exceed the decay heat by an acceptable margin but the capacity of pre-heaters to keep the sodium within the primary vessel at about 200 deg. C must be maintained. With regard to the heat loss and the decay heat, the estimated heat loss in the primary system was in the range of 90-170 kW in one-loop operation, and the calculated decay heat was 21.2 kW. Although the heat input of the primary pump was considered, it was clear that circuit heat loss greatly exceeded the decay heat. As for pre-heaters, effective capacity was less than the heat loss. Therefore, the temperature of the reactor vessel room was raised to reduce the heat loss. One-loop operation of the PHTS was able to be executed by means of these measures. The cost of electrical consumption in the power plant has been reduced by one-loop operation of the PHTS and the modification period was shortened. (authors)
Particle and heat transport in Tokamaks

International Nuclear Information System (INIS)

Chatelier, M.

1984-01-01

A limitation to performances of tokamaks is heat transport through magnetic surfaces. Principles of ''classical'' or ''neoclassical'' transport -i.e. transport due to particle and heat fluxes due to Coulomb scattering of charged particle in a magnetic field- are exposed. It is shown that beside this classical effect, ''anomalous'' transport occurs; it is associated to the existence of fluctuating electric or magnetic fields which can appear in the plasma as a result of charge and current perturbations. Tearing modes and drift wave instabilities are taken as typical examples. Experimental features are presented which show that ions behave approximately in a classical way whereas electrons are strongly anomalous [fr
ASDEX contributions to the 17th European conference on controlled fusion and plasma heating

International Nuclear Information System (INIS)

1990-09-01

The 'ASDEX contributions to the 17th European conference on controlled fusion and plasma heating' (Amsterdam, June 25-29, 1990) hold one invited paper (Physics of enhanced confinement with peaked and board density profiles) and 12 chapters containing 44 contributed papers dealing with the following topics: Lower hybrid current drive and heating; Ion cyclotron heating; General confinement studies; Fluctuation studies; Direct measurement of transport coefficients; H-mode studies; Pellet studies; Divertor and SOL-studies; Impurity and impurity transport studies; Density limit studies; MHD studies; Diagnostic development. (orig./AH)
Profiles and fluctuations in edge and SOL turbulence

DEFF Research Database (Denmark)

Naulin, Volker; Xu, G.; Vianello, N.

2012-01-01

propagating structures and parallel transport sets up the observed profiles and how intermittency influences edge conditions. The filamentary blob structures also transport and generate currents in the SOL, which can be investigated by means of local magnetic diagnostics. Finally, the ratio of ion to electron...... temperature in the SOL is an important measure for the influence of finite larmor radius effects on the propagation properties of blobs. Numerical investigations indicate that these effects can lead to an increased self confinement and radial reach of these structures. © 2012 WILEY-VCH Verlag GmbH & Co. KGa...
Heat in the Barents Sea: transport, storage, and surface fluxes

Directory of Open Access Journals (Sweden)

L. H. Smedsrud

2010-02-01

Full Text Available A column model is set up for the Barents Sea to explore sensitivity of surface fluxes and heat storage from varying ocean heat transport. Mean monthly ocean transport and atmospheric forcing are synthesised and force the simulations. Results show that by using updated ocean transports of heat and freshwater the vertical mean hydrographic seasonal cycle can be reproduced fairly well.

Our results indicate that the ~70 TW of heat transported to the Barents Sea by ocean currents is lost in the southern Barents Sea as latent, sensible, and long wave radiation, each contributing 23–39 TW to the total heat loss. Solar radiation adds 26 TW in the south, as there is no significant ice production.

The northern Barents Sea receives little ocean heat transport. This leads to a mixed layer at the freezing point during winter and significant ice production. There is little net surface heat loss annually in the north. The balance is achieved by a heat loss through long wave radiation all year, removing most of the summer solar heating.

During the last decade the Barents Sea has experienced an atmospheric warming and an increased ocean heat transport. The Barents Sea responds to such large changes by adjusting temperature and heat loss. Decreasing the ocean heat transport below 50 TW starts a transition towards Arctic conditions. The heat loss in the Barents Sea depend on the effective area for cooling, and an increased heat transport leads to a spreading of warm water further north.
Heat transport and surface heat transfer with helium in rotating channels

International Nuclear Information System (INIS)

Schnapper, C.

1978-06-01

Heat transport and surface heat transfer with helium in rotating radially arranged channels were experimentally studied with regard to cooling of large turbogenerators with superconducting windings. Measurements with thermosiphon and thermosiphon loops of different channel diameters were performed, and results are presented. The thermodynamic state of the helium in a rotating thermosiphon and the mass flow rate in a thermosiphon loop is characterized by formulas. Heat transport by directed convection in thermosiphon loops is found to be more efficient 12 cm internal convection in thermosiphons. Steady state is reached sooner in thermosiphon loops than in thermosiphons, when heat load suddenly changes. In a very large centrifugal field single-phase heat transfer with natural and forced convection is described by similar formulas which are also applicable 10 thermosiphons in gravitation field or to heat transfer to non-rotating helium. (orig.) [de
Ultrasound-assisted sol-gel synthesis of ZrO2.

Science.gov (United States)

Guel, Marlene Lariza Andrade; Jiménez, Lourdes Díaz; Hernández, Dora Alicia Cortés

2017-03-01

Synthesis of tetragonal ZrO 2 by both conventional sol-gel and ultrasound-assisted sol-gel methods and using a non-ionic surfactant Tween-20, was performed. A porous microstructure composed of nanometric particles was observed. Tetragonal ZrO 2 was obtained using a low heat treatment temperature of powders, 500°C by both methods. A higher crystallinity and a shorter reaction time were observed when ultrasound was used in the sol-gel method due to the cavitation phenomenon. Copyright Â© 2016 Elsevier B.V. All rights reserved.
Arcing at B4C-covered limiters exposed to a SOL-plasma

International Nuclear Information System (INIS)

Laux, M.; Schneider, W.; Wienhold, P.; Juettner, B.; Huber, A.; Balden, M.; Linke, J.; Kostial, H.; Mayer, M.; Rubel, M.; Herrmann, A.; Pospieszczyk, A.; Jachmich, S.; Schweer, B.; Hildebrandt, D.; Bolt, H.

2003-01-01

Plasma sprayed B 4 C-layers considered as wall coatings for the W7X stellarator have been studied during and after exposure to TEXTOR and after arcing experiments in vacuum. Arcing through the B 4 C layer occurred favoured by high power fluxes and not restricted to less stable phases. But this arcing implies an especially noisy scrape-off layer (SOL). Instead of moving retrograde in the external magnetic field, the arc spot on the B 4 C-layer sticks to the same location for its whole lifetime. Consequently, the arc erodes the entire B 4 C layer, finally burning down to the Cu substrate. In the neighbourhood of craters the surface contains Cu originating from those craters. This material, hauled to the surface by the arc, is subject to subsequent erosion, transport, and redeposition by the SOL-plasma. The behaviour of arcs on B 4 C is most probably caused by the peculiar temperature dependences of the electrical and heat conductivity of B 4 C
Understanding of flux-limited behaviors of heat transport in nonlinear regime

Energy Technology Data Exchange (ETDEWEB)

Guo, Yangyu, E-mail: yangyuhguo@gmail.com [Key Laboratory for Thermal Science and Power Engineering of Ministry of Education, Department of Engineering Mechanics and CNMM, Tsinghua University, Beijing 100084 (China); Jou, David, E-mail: david.jou@uab.es [Departament de Física, Universitat Autònoma de Barcelona, 08193 Bellaterra, Catalonia (Spain); Wang, Moran, E-mail: mrwang@tsinghua.edu [Key Laboratory for Thermal Science and Power Engineering of Ministry of Education, Department of Engineering Mechanics and CNMM, Tsinghua University, Beijing 100084 (China)

2016-01-28

The classical Fourier's law of heat transport breaks down in highly nonequilibrium situations as in nanoscale heat transport, where nonlinear effects become important. The present work is aimed at exploring the flux-limited behaviors based on a categorization of existing nonlinear heat transport models in terms of their theoretical foundations. Different saturation heat fluxes are obtained, whereas the same qualitative variation trend of heat flux versus exerted temperature gradient is got in diverse nonlinear models. The phonon hydrodynamic model is proposed to act as a standard to evaluate other heat flux limiters because of its more rigorous physical foundation. A deeper knowledge is thus achieved about the phenomenological generalized heat transport models. The present work provides deeper understanding and accurate modeling of nonlocal and nonlinear heat transport beyond the diffusive limit. - Highlights: • Exploring flux-limited behaviors based on a categorization of existing nonlinear heat transport models. • Proposing phonon hydrodynamic model as a standard to evaluate heat flux limiters. • Providing accurate modeling of nonlocal and nonlinear heat transport beyond the diffusive limit.
Theory of ion heat transport in tokamaks

International Nuclear Information System (INIS)

Gott, Y.V.; Yurchenko, E.I.

1987-01-01

Experiments which have been carried out in several tokamaks to determine the ion thermal conductivity show that it is several times the value predicted by the neoclassical theory. A possible explanation for this discrepancy is proposed. When the finite width of a banana is taken into account, there are substantial increases in the heat fluxes which stem from the important contribution of superthermal ions to the transport. If the electron diffusive flux is zero, a systematic account of the ions with E>T leads to an ion heat flux with a finite banana width which is two to four times the neoclassical prediction. The effect of the anomalous nature of the electron flux on the ion heat transport is analyzed. An expression is derived for calculating the ion heat transport over the entire range of collision rates
Electric probe diagnostics for measuring SOL parameters, wall and divertor fluxes in KSTAR

Energy Technology Data Exchange (ETDEWEB)

Kim, Heung-Su, E-mail: kimhs@nfri.re.kr [National Fusion Research Institute, Daejeon (Korea, Republic of); Bak, Jun-Gyo [National Fusion Research Institute, Daejeon (Korea, Republic of); Bae, Min-Keun; Chung, Kyu-Sun [Hanyang University, Seoul (Korea, Republic of); Hong, Suk-Ho [National Fusion Research Institute, Daejeon (Korea, Republic of)

2016-11-01

Highlights: • Some components in EPDs were improved to investigate characteristics of the SOL plasmas and to measure wall and divertor fluxes in the KSTAR tokamak plasmas. From the upgrades in the EPDs, the measured error of the elapsed distance for the evaluation of the SOL profiles can be reduced up to 1%. • In the SOL parameter measurement during IWL plasma, the e-folding lengths in the main SOL region lTe and lne were evaluated as 3.5 cm and 2.1 cm, respectively. • From flux measurement at the far SOL during a diverted ELMy H-mode, peaked heat flux toward to outboard wall during ELMs might be less than 1% of the peaked divertor heat flux. • The movement of an OSP during a diverted H-mode can be detected from the divertor probe measurement, and the peaked heat flux near the OSP was estimated as few MW m-2. - Abstract: Some components in electric probe diagnostics (EPDs) are improved in order to investigate characteristics of edge plasmas in the upstream scrape-off-layer (SOL) region and to measure wall and divertor fluxes during L-mode and H-mode plasma discharges in the Korea Superconducting Tokamak Advanced Research (KSTAR). From the upgrades in the EPDs, the measured error of the elapsed distance for the evaluation of the SOL profiles can be reduced up to 1% and the ion saturation current of up to 1.0 A near an outer strike point (OSP) can be measured at the divertor region. In the SOL profile measurements during L-mode and inner wall limited plasma (B{sub T} = 2.0 T, I{sub p} = 0.4 MA), the e-folding lengths in the main SOL region λ{sub Te} and λ{sub ne} are evaluated as 3.5 cm and 2.1 cm, respectively. From particle flux measurement at the far SOL region during a diverted ELMy H-mode discharge (B{sub T} = 1.8 T, I{sub p} = 0.65 MA), peaked heat flux toward to outboard wall during ELM bursts is estimated up to ∼20 k Wm{sup −2}, which may be less than 1% of the peaked divertor heat flux expected for the neutral beam (NB) heating power P{sub NB
Effects of parameters of sol-gel process on the phase evolution of sol-gel-derived hydroxyapatite

International Nuclear Information System (INIS)

Eshtiagh-Hosseini, Hossein; Housaindokht, Mohammad Reza; Chahkandi, Mohammad

2007-01-01

It has been established that hydroxyapatite powders can be produced using an alkoxide-based sol-gel technique. Nanocrystalline powders of hydroxyapatite (HA) were prepared from Ca(NO 3 ) 2 .4H 2 O and PO(OC 2 H 5 ) 3 as calcium and phosphorus precursors, respectively, using a sol-gel route. For a number of samples, sol of phosphorus was first hydrolyzed for 24 h with distilled water. The sol temperature, aging time and heat treatment temperature on apatite formation were systematically studied. Increasing the aging time affected the reducing of CaO. Also, increasing the mixed sol solution temperature up to 80 deg. C had a positive effect on the disappearance of impurity phases. With the increase of the calcination temperature >600 deg. C, calcium phosphate impurity phases disappeared. Structural evolution during the synthesis of hydroxyapatite is investigated by using infrared (IR) analysis, X-ray diffraction (XRD), thermal behavior (DTA), and elemental analysis of electron microscopy examination (SEM). X-ray diffraction with the aid of Scherrer and Williamson-Hall equations has been used to characterize the distributions of crystallite size and micro-strain of HA powders .The results indicated that mean crystallite size increased and micro-strain decreased significantly with the rise in firing temperature
Progress in understanding heat transport at JET

International Nuclear Information System (INIS)

Mantica, P.; Garbet, X.; Angioni, C.

2005-01-01

This paper reports recent progress in understanding heat transport mechanisms either in conventional or advanced tokamak scenarios in JET. A key experimental tool has been the use of perturbative transport techniques, both by ICH power modulation and by edge cold pulses. The availability of such results has allowed careful comparison with theoretical modelling using 1D empirical or physics based transport models, 3D fluid turbulence simulations or gyrokinetic stability analysis. In conventional L- and H-mode plasmas the issue of temperature profile stiffness has been addressed. JET results are consistent with the concept of a critical inverse temperature gradient length above which transport is enhanced by the onset of turbulence. A threshold value R/L Te ∼5 has been found for the onset of stiff electron transport, while the level of electron stiffness appears to vary strongly with plasma parameters, in particular with the ratio of electron and ion heating: electrons become stiffer when ions are strongly heated, resulting in larger R/L Ti values. This behaviour has also been found theoretically, although quantitatively weaker than in experiments. In plasmas characterized by Internal Transport Barriers (ITB), the properties of heat transport inside the ITB layer and the ITB formation mechanisms have been investigated. The plasma current profile is found to play a major role in ITB formation. The effect of negative magnetic shear on electron and ion stabilization is demonstrated both experimentally and theoretically using turbulence codes. The role of rational magnetic surfaces in ITB triggering is well assessed experimentally, but still lacks a convincing theoretical explanation. Attempts to trigger an ITB by externally induced magnetic reconnection using saddle coils have shown that MHD islands in general do not produce a sufficient variation of ExB flow shear to lead to ITB formation. First results of perturbative transport in ITBs show that the ITB is a narrow
Active transport and heat.

Science.gov (United States)

Tait, Peter W

2011-07-01

Increasing heat may impede peoples' ability to be active outdoors thus limiting active transport options. Co-benefits from mitigation of and adaptation to global warming should not be assumed but need to be actively designed into strategies.

Possible role of oceanic heat transport in early Eocene climate

Science.gov (United States)

Sloan, L. C.; Walker, J. C.; Moore, T. C. Jr

1995-01-01

Increased oceanic heat transport has often been cited as a means of maintaining warm high-latitude surface temperatures in many intervals of the geologic past, including the early Eocene. Although the excess amount of oceanic heat transport required by warm high latitude sea surface temperatures can be calculated empirically, determining how additional oceanic heat transport would take place has yet to be accomplished. That the mechanisms of enhanced poleward oceanic heat transport remain undefined in paleoclimate reconstructions is an important point that is often overlooked. Using early Eocene climate as an example, we consider various ways to produce enhanced poleward heat transport and latitudinal energy redistribution of the sign and magnitude required by interpreted early Eocene conditions. Our interpolation of early Eocene paleotemperature data indicate that an approximately 30% increase in poleward heat transport would be required to maintain Eocene high-latitude temperatures. This increased heat transport appears difficult to accomplish by any means of ocean circulation if we use present ocean circulation characteristics to evaluate early Eocene rates. Either oceanic processes were very different from those of the present to produce the early Eocene climate conditions or oceanic heat transport was not the primary cause of that climate. We believe that atmospheric processes, with contributions from other factors, such as clouds, were the most likely primary cause of early Eocene climate.
Heat and particle transport of sol/divertor plasma in the W-shaped divertor on JT-60U

International Nuclear Information System (INIS)

Asakura, N.; Sakurai, S.; Hosogane, N.

1999-01-01

The plasma profile and parallel flow in the scrape-off layer (SOL) were systematically measured using Mach probes installed at the midplane and the divertor x-point. Quantitative evaluation of a parallel flow: naturally produced in a torus to keep the pressure constant along the field line, was consistent with the measurement. Geometry effects of the W-shaped divertor on the divertor plasma and particle recycling at the newly installed baffle plates were evaluated quantitatively using the edge plasma data. (author)
The effect of microwave and conventional heating on a modified sol-gel derived biphasic calcium phosphate

Science.gov (United States)

Herradi, S.; Bouhazma, S.; Khaldi, M.; El Hachadi, A.; El Bali, B.; Lachkar, M.

2018-03-01

A facile sol-gel method was used to synthesize either hydroxyapatite (HA) or beta-tricalcium phosphate (β-TCP) as the major phase. Herein, we report, on the one hand, the effect of a very low maturation temperature on the final powder composition after drying step, and on the other hand, we compare the effect of calcination of this powder by microwave or electric furnace. It was found that microwave heating has led to the formation of hydroxyapatite phase upon 180°C for 20 minutes, however, XRD patterns show that the powder becomes less crystallized upon 220°C and amorphous upon 230°C. In contrast, furnace heating at 600°C and 700°C converts the as-synthesized powder to β-TCP as the major phase together with HA as the minor phase. This work shows the possibility to obtain the as-prepared BCP at much lower maturation temperature; it also gives an insight into the role, of either microwave or conventional heating, in controlling the ratio between HA and β-TCP in the sintered powder.
Coupled heat transfer in high temperature transporting system with semitransparent/opaque material

International Nuclear Information System (INIS)

Du Shenghua; Xia Xinjin

2010-01-01

The heat transfer model of the aerodynamic heating coupled with radiative cooling was developed. The thermal protect system includes the higher heat flux region with high temperature semitransparent material, the heat transporting channel and the lower heat flux region with metal. The control volume method was combined with the Monte Carlo method to calculate the coupled heat transfer of the transporting system, and the thermal equilibrium equation for the transporting channel was solved simultaneously. The effect of the aeroheating flux radio, the area ratio of radiative surfaces, the convective heat transfer coefficient of the heat transporting channel on the radiative surface temperature and the fluid temperature in the heat transporting channel were analyzed. The effect of radiation and conduction in the semitransparent material was discussed. The result shows that to increase the convective heat transfer coefficient in heat flux channel can enhance the heat transporting ability of the system, but the main parameter to effect on the temperature of the heat transporting system is the area ratio of radiative surfaces. (authors)
Heat Transfer in Directional Water Transport Fabrics

Directory of Open Access Journals (Sweden)

Chao Zeng

2016-10-01

Full Text Available Directional water transport fabrics can proactively transfer moisture from the body. They show great potential in making sportswear and summer clothing. While moisture transfer has been previously reported, heat transfer in directional water transport fabrics has been little reported in research literature. In this study, a directional water transport fabric was prepared using an electrospraying technique and its heat transfer properties under dry and wet states were evaluated, and compared with untreated control fabric and the one pre-treated with NaOH. All the fabric samples showed similar heat transfer features in the dry state, and the equilibrium temperature in the dry state was higher than for the wet state. Wetting considerably enhanced the thermal conductivity of the fabrics. Our studies indicate that directional water transport treatment assists in moving water toward one side of the fabric, but has little effect on thermal transfer performance. This study may be useful for development of “smart” textiles for various applications.
Ion heat transport studies in JET

DEFF Research Database (Denmark)

Mantica, P; Angioni, C; Baiocchi, B

2011-01-01

Detailed experimental studies of ion heat transport have been carried out in JET exploiting the upgrade of active charge exchange spectroscopy and the availability of multi-frequency ion cyclotron resonance heating with 3He minority. The determination of ion temperature gradient (ITG) threshold a...
Screen-printable sol-gel enzyme-containing carbon inks.

Science.gov (United States)

Wang, J; Pamidi, P V; Park, D S

1996-08-01

Enzymes usually cannot withstand the high-temperature curing associated with the thick-film fabrication process and require a separate immobilization step in connection with the production of single-use biosensors. We report on the development of sol-gel-derived enzyme-containing carbon inks that display compatibility with the screen-printing process. Such coupling of sol-gel and thick-film technologies offers a one-step fabrication of disposable enzyme electrodes, as it obviates the need for thermal curing. The enzyme-containing sol-gel carbon ink, prepared by dispersing the biocatalyst, along with the graphite powder and a binder, within the sol-gel precursors, is cured very rapidly (10 min) at low temperature (4 °C). The influence of the ink preparation conditions is explored, and the sensor performance is evaluated in connection with the incorporation of glucose oxidase or horseradish peroxidase. The resulting strips are stable for at least 3 months. Such sol-gel-derived carbon inks should serve as hosts for other heat-sensitive biomaterials in connection with the microfabrication of various thick-film biosensors.
Electron and ion heat transport with lower hybrid current drive and neutral beam injection heating in ASDEX

International Nuclear Information System (INIS)

Soeldner, F.X.; Pereverzev, G.V.; Bartiromo, R.; Fahrbach, H.U.; Leuterer, F.; Murmann, H.D.; Staebler, A.; Steuer, K.H.

1993-01-01

Transport code calculations were made for experiments with the combined operation of lower hybrid current drive and heating and of neutral beam injection heating on ASDEX. Peaking or flattening of the electron temperature profile are mainly explained by modifications of the MHD induced electron heat transport. They originate from current profile changes due to lower hybrid and neutral beam current drive and to contributions from the bootstrap current. Ion heat transport cannot be described by one single model for all heating scenarios. The ion heat conductivity is reduced during lower hybrid heated phases with respect to Ohmic and neutral beam heating. (author). 13 refs, 5 figs
An Overview of Liquid Fluoride Salt Heat Transport Systems

Energy Technology Data Exchange (ETDEWEB)

Holcomb, David Eugene [ORNL; Cetiner, Sacit M [ORNL

2010-09-01

Heat transport is central to all thermal-based forms of electricity generation. The ever increasing demand for higher thermal efficiency necessitates power generation cycles transitioning to progressively higher temperatures. Similarly, the desire to provide direct thermal coupling between heat sources and higher temperature chemical processes provides the underlying incentive to move toward higher temperature heat transfer loops. As the system temperature rises, the available materials and technology choices become progressively more limited. Superficially, fluoride salts at {approx}700 C resemble water at room temperature being optically transparent and having similar heat capacity, roughly three times the viscosity, and about twice the density. Fluoride salts are a leading candidate heat-transport material at high temperatures. Fluoride salts have been extensively used in specialized industrial processes for decades, yet they have not entered widespread deployment for general heat transport purposes. This report does not provide an exhaustive screening of potential heat transfer media and other high temperature liquids such as alkali metal carbonate eutectics or chloride salts may have economic or technological advantages. A particular advantage of fluoride salts is that the technology for their use is relatively mature as they were extensively studied during the 1940s-1970s as part of the U.S. Atomic Energy Commission's program to develop molten salt reactors (MSRs). However, the instrumentation, components, and practices for use of fluoride salts are not yet developed sufficiently for commercial implementation. This report provides an overview of the current understanding of the technologies involved in liquid salt heat transport (LSHT) along with providing references to the more detailed primary information resources. Much of the information presented here derives from the earlier MSR program. However, technology has evolved over the intervening years
Fast wave power flow along SOL field lines in NSTX

Science.gov (United States)

Perkins, R. J.; Bell, R. E.; Diallo, A.; Gerhardt, S.; Hosea, J. C.; Jaworski, M. A.; Leblanc, B. P.; Kramer, G. J.; Phillips, C. K.; Roquemore, L.; Taylor, G.; Wilson, J. R.; Ahn, J.-W.; Gray, T. K.; Green, D. L.; McLean, A.; Maingi, R.; Ryan, P. M.; Jaeger, E. F.; Sabbagh, S.

2012-10-01

On NSTX, a major loss of high-harmonic fast wave (HHFW) power can occur along open field lines passing in front of the antenna over the width of the scrape-off layer (SOL). Up to 60% of the RF power can be lost and at least partially deposited in bright spirals on the divertor floor and ceiling [1,2]. The flow of HHFW power from the antenna region to the divertor is mostly aligned along the SOL magnetic field [3], which explains the pattern of heat deposition as measured with infrared (IR) cameras. By tracing field lines from the divertor back to the midplane, the IR data can be used to estimate the profile of HHFW power coupled to SOL field lines. We hypothesize that surface waves are being excited in the SOL, and these results should benchmark advanced simulations of the RF power deposition in the SOL (e.g., [4]). Minimizing this loss is critical optimal high-power long-pulse ICRF heating on ITER while guarding against excessive divertor erosion.[4pt] [1] J.C. Hosea et al., AIP Conf Proceedings 1187 (2009) 105. [0pt] [2] G. Taylor et al., Phys. Plasmas 17 (2010) 056114. [0pt] [3] R.J. Perkins et al., to appear in Phys. Rev. Lett. [0pt] [4] D.L. Green et al., Phys. Rev. Lett. 107 (2011) 145001.
Some factors affecting radiative heat transport in PWR cores

International Nuclear Information System (INIS)

Hall, A.N.

1989-04-01

This report discusses radiative heat transport in Pressurized Water Reactor cores, using simple models to illustrate basic features of the transport process. Heat transport by conduction and convection is ignored in order to focus attention on the restrictions on radiative heat transport imposed by the geometry of the heat emitting and absorbing structures. The importance of the spacing of the emitting and absorbing structures is emphasised. Steady state temperature distributions are found for models of cores which are uniformly heated by fission product decay. In all of the models, a steady state temperature distribution can only be obtained if the central core temperature is in excess of the melting point of UO 2 . It has recently been reported that the MIMAS computer code, which takes into account radiative heat transport, has been used to model the heat-up of the Three Mile Island-2 reactor core, and the computations indicate that the core could not have reached the melting point of UO 2 at any time or any place. We discuss this result in the light of the calculations presented in this paper. It appears that the predicted stabilisation of the core temperatures at ∼ 2200 0 C may be a consequence of the artificially large spacing between the radial rings employed in the MIMAS code, rather than a result of physical significance. (author)
Evolution of the SOL plasma background at density shoulder formation

International Nuclear Information System (INIS)

D'Isa, Federico Antonio; Carralero, Daniel; Lunt, Tilmann

2016-01-01

One of the main problems of our age is the ever increasing demand of energy. This prompts the search for new energy sources which should have the advantages of being nearly inexhaustible and usable to produce a predictable amount of energy. A possible solution is to build a reactor based on nuclear fusion. ITER will be the first divertor Tokamak to reach fusion break even and it will pave the way to a commercial use of fusion to produce sustainable and clean energy. One of the biggest obstacles to the construction of a commercial fusion reactor is represented by the heat and particle flux toward the main chamber plasma facing components and the divertor targets. A fusion reactor will likely experience power loads and erosion on the verge of the technical limits of available plasma facing materials. To predict properly the distribution of those fluxes between the divertor and the main chamber, a better understanding of the physics in the open field lines region (called Scrape-off layer or SOL) is required. This thesis, being developed in partnership with the Max-Planck-institut fuer Plasmaphysik (Garching bei Muenchen, DE), is framed in this context. In the SOL of L-mode (low confinement) discharges, qualitatively two kinds of density profiles can be distinguished. The first one is characterized by a strong density gradient in the vicinity of the separatrix, followed by a flat region towards the far SOL. The second profile lacks such a strong gradient and displays an almost linear decay in the whole SOL. The latter kind of density profile is characterized by stronger fluxes toward the first wall with respect to the first kind. This my be a threat for the ITER unlike the divertor targets which are made of tungsten, the first wall will be made beryllium which can suffer damage from sputtering. This work is focused on understanding the physics behind the transition between those two profiles, the so-called density shoulder formation. After the shoulder formation it is
Evolution of the SOL plasma background at density shoulder formation

Energy Technology Data Exchange (ETDEWEB)

D' Isa, Federico Antonio; Carralero, Daniel; Lunt, Tilmann; Collaboration: ASDEX Upgrade Team

2016-12-15

One of the main problems of our age is the ever increasing demand of energy. This prompts the search for new energy sources which should have the advantages of being nearly inexhaustible and usable to produce a predictable amount of energy. A possible solution is to build a reactor based on nuclear fusion. ITER will be the first divertor Tokamak to reach fusion break even and it will pave the way to a commercial use of fusion to produce sustainable and clean energy. One of the biggest obstacles to the construction of a commercial fusion reactor is represented by the heat and particle flux toward the main chamber plasma facing components and the divertor targets. A fusion reactor will likely experience power loads and erosion on the verge of the technical limits of available plasma facing materials. To predict properly the distribution of those fluxes between the divertor and the main chamber, a better understanding of the physics in the open field lines region (called Scrape-off layer or SOL) is required. This thesis, being developed in partnership with the Max-Planck-institut fuer Plasmaphysik (Garching bei Muenchen, DE), is framed in this context. In the SOL of L-mode (low confinement) discharges, qualitatively two kinds of density profiles can be distinguished. The first one is characterized by a strong density gradient in the vicinity of the separatrix, followed by a flat region towards the far SOL. The second profile lacks such a strong gradient and displays an almost linear decay in the whole SOL. The latter kind of density profile is characterized by stronger fluxes toward the first wall with respect to the first kind. This my be a threat for the ITER unlike the divertor targets which are made of tungsten, the first wall will be made beryllium which can suffer damage from sputtering. This work is focused on understanding the physics behind the transition between those two profiles, the so-called density shoulder formation. After the shoulder formation it is
Permanent Habitats in Earth-Sol/Mars-Sol Orbit Positions

Science.gov (United States)

Greenspon, J.

Project Outpost is a manned Earth-Sol/Mars-Sol platform that enables permanent occupation in deep space. In order to develop the program elements for this complex mission, Project Outpost will rely primarily on existing/nearterm technology and hardware for the construction of its components. For the purposes of this study, four mission requirements are considered: 1. Outpost - Man's 1st purpose-produced effort of space engineering, in which astructure is developed/constructed in an environment completely alien to currentpractices for EVA guidelines. 2. Newton - a concept study developed at StarGate Research, for the development ofa modified Hohmann personnel orbital transport operating between Earth andMars. Newton would serve as the primary crew delivery apparatus throughrepeatable transfer scheduling for all Earth-Lpoint-Mars activities. Thispermanent "transit system" would establish the foundations for Solar systemcolonization. 3. Cruis - a concept study developed at StarGate Research, for the development of amodified Hohmann cargo orbital transport operating between Earth and Mars.Cruis would serve as the primary equipment delivery apparatus throughrepeatable transfer scheduling for all Earth-Lpoint-Mars activities. Thispermanent "transit system" would establish the foundations for Solar systemcolonization, and 4. Ares/Diana - a more conventional space platform configuration for Lunar andMars orbit is included as a construction baseline. The operations of these assetsare supported, and used for the support, of the outpost. Outpost would be constructed over a 27-year period of launch opportunities into Earth-Sol or Mars-Sol Lagrange orbit (E-S/M-S L1, 4 or 5). The outpost consists of an operations core with a self-contained power generation ability, a docking and maintenance structure, a Scientific Research complex and a Habitation Section. After achieving initial activation, the core will provide the support and energy required to operate the outpost in a 365
Finite element modelling of transport and drift effects in tokamak divertor and SOL

International Nuclear Information System (INIS)

Simard, M.; Marchand, R.; Boucher, C.; Gunn, J.P.

1996-01-01

A finite element code is used to simulate transport of a single-species plasma in the edge and divertor of a tokamak. The physical model is based on Braginskii's fluid equations for the conservation of particles, parallel momentum, ion and electron energy. In modelling recycling, transport of neutral density and energy is treated in the diffusion approximation. The electrostatic potential is obtained from the generalized Ohm's law. It is used to compute the electric field and the associated E x B drift. In a first approximation, transport is assumed to be ambipolar. The system of equations is discretized on an unstructured triangular mesh, thus permitting good spatial resolution near the X-point and an accurate description of divertor plates of arbitrary shape. Special care must be taken to prevent numerical corruption of the highly anisotropic thermal diffusion. Comparisons will be made between simulations and experimental results from TdeV. This will focus, in particular, on density and temperature profiles at the divertor plates, and on the plasma parallel velocity in the SOL. The asymmetry in the power deposited to the inner and outer divertors and the effect of magnetic field reversal will be considered. Comparisons with B2-Eirene simulation results will also be presented
Source effects on impurity and heat transport in a tokamak

International Nuclear Information System (INIS)

Bennett, R.B.

1980-12-01

A recently developed generalization of neoclassical theory is extended here to study heat flux contributions to impurity transport, as well as the heat fluxes themselves. The theory accounts for the first four source moments, with external drags, which has been studied previously with either fewer moments or restricted to a collisional plasma. Conditions are established for which a momentum source may be used to modify the particle and heat transport. In the course of this work, the particle and heat transport is evaluated for a two species plasma with arbitrary plasma geometry, beta, and collisionality
Transport lattice models of heat transport in skin with spatially heterogeneous, temperature-dependent perfusion

Directory of Open Access Journals (Sweden)

Martin Gregory T

2004-11-01

Full Text Available Abstract Background Investigation of bioheat transfer problems requires the evaluation of temporal and spatial distributions of temperature. This class of problems has been traditionally addressed using the Pennes bioheat equation. Transport of heat by conduction, and by temperature-dependent, spatially heterogeneous blood perfusion is modeled here using a transport lattice approach. Methods We represent heat transport processes by using a lattice that represents the Pennes bioheat equation in perfused tissues, and diffusion in nonperfused regions. The three layer skin model has a nonperfused viable epidermis, and deeper regions of dermis and subcutaneous tissue with perfusion that is constant or temperature-dependent. Two cases are considered: (1 surface contact heating and (2 spatially distributed heating. The model is relevant to the prediction of the transient and steady state temperature rise for different methods of power deposition within the skin. Accumulated thermal damage is estimated by using an Arrhenius type rate equation at locations where viable tissue temperature exceeds 42°C. Prediction of spatial temperature distributions is also illustrated with a two-dimensional model of skin created from a histological image. Results The transport lattice approach was validated by comparison with an analytical solution for a slab with homogeneous thermal properties and spatially distributed uniform sink held at constant temperatures at the ends. For typical transcutaneous blood gas sensing conditions the estimated damage is small, even with prolonged skin contact to a 45°C surface. Spatial heterogeneity in skin thermal properties leads to a non-uniform temperature distribution during a 10 GHz electromagnetic field exposure. A realistic two-dimensional model of the skin shows that tissue heterogeneity does not lead to a significant local temperature increase when heated by a hot wire tip. Conclusions The heat transport system model of the
Intense radiative heat transport across a nano-scale gap

International Nuclear Information System (INIS)

Budaev, Bair V.; Ghafari, Amin; Bogy, David B.

2016-01-01

In this paper, we analyze the radiative heat transport in layered structures. The analysis is based on our prior description of the spectrum of thermally excited waves in systems with a heat flux. The developed method correctly predicts results for all known special cases for both large and closing gaps. Numerical examples demonstrate the applicability of our approach to the calculation of the radiative heat transport coefficient across various layered structures.
Reversible sol-gel-sol medium for enzymatic optical biosensors

NARCIS (Netherlands)

Safaryan, S.; Yakovlev, A.; Pidko, E.A.; Vinogradov, A.; Vinogradov, V.

2017-01-01

In this paper we for the first time report a reversible sol-gel-sol approach to obtain optical enzymatic biosensors with improved enzyme stability and good sensitivity by using desktop inkjet printing. The developed technique is based on the bio-inorganic inks allowing for a sol-gel-sol transition
Parallel Transport with Sheath and Collisional Effects in Global Electrostatic Turbulent Transport in FRCs

Science.gov (United States)

Bao, Jian; Lau, Calvin; Kuley, Animesh; Lin, Zhihong; Fulton, Daniel; Tajima, Toshiki; Tri Alpha Energy, Inc. Team

2017-10-01

Collisional and turbulent transport in a field reversed configuration (FRC) is studied in global particle simulation by using GTC (gyrokinetic toroidal code). The global FRC geometry is incorporated in GTC by using a field-aligned mesh in cylindrical coordinates, which enables global simulation coupling core and scrape-off layer (SOL) across the separatrix. Furthermore, fully kinetic ions are implemented in GTC to treat magnetic-null point in FRC core. Both global simulation coupling core and SOL regions and independent SOL region simulation have been carried out to study turbulence. In this work, the ``logical sheath boundary condition'' is implemented to study parallel transport in the SOL. This method helps to relax time and spatial steps without resolving electron plasma frequency and Debye length, which enables turbulent transports simulation with sheath effects. We will study collisional and turbulent SOL parallel transport with mirror geometry and sheath boundary condition in C2-W divertor.

Modelling of Temperature Profiles and Transport Scaling in Auxiliary Heated Tokamaks

DEFF Research Database (Denmark)

Callen, J.D.; Christiansen, J.P.; Cordey, J.G.

1987-01-01

time , the heating effectiveness η, and the energy offset W(0). Considering both the temperature profile responses and the global transport scaling, the constant heat pinch or excess temperature gradient model is found to best characterize the present JET data. Finally, new methods are proposed......The temperature profiles produced by various heating profiles are calculated from local heat transport models. The models take the heat flux to be the sum of heat diffusion and a non-diffusive heat flow, consistent with local measurements of heat transport. Two models are developed analytically...... in detail: (i) a heat pinch or excess temperature gradient model with constant coefficients; and (ii) a non-linear heat diffusion coefficient (χ) model. Both models predict weak (lesssim20%) temperature profile responses to physically relevant changes in the heat deposition profile – primarily because...
TOUGH, Unsaturated Groundwater Transport and Heat Transport Simulation

International Nuclear Information System (INIS)

Pruess, K.A.; Cooper, C.; Osnes, J.D.

1992-01-01

1 - Description of program or function: A successor to the TOUGH program, TOUGH2 offers added capabilities and user features, including the flexibility to handle different fluid mixtures (water, water with tracer; water, CO 2 ; water, air; water, air with vapour pressure lowering, and water, hydrogen), facilities for processing of geometric data (computational grids), and an internal version control system to ensure referenceability of code applications. TOUGH (Transport of Unsaturated Groundwater and Heat) is a multi-dimensional numerical model for simulating the coupled transport of water, vapor, air, and heat in porous and fractured media. The program provides options for specifying injection or withdrawal of heat and fluids. Although primarily designed for studies of high-level nuclear waste isolation in partially saturated geological media, it should also be useful for a wider range of problems in heat and moisture transfer, and in the drying of porous materials. For example, geothermal reservoir simulation problems can be handled simply by setting the air mass function equal to zero on input. The TOUGH simulator was developed for problems involving strongly heat-driven flow. To describe these phenomena a multi-phase approach to fluid and heat flow is used, which fully accounts for the movement of gaseous and liquid phases, their transport of latent transitions between liquid and vapor. TOUGH takes account of fluid flow in both liquid and gaseous phases occurring under pressure, viscous, and gravity forces according to Darcy's law. Interference between the phases is represented by means of relative permeability functions. The code handles binary, but not Knudsen, diffusion in the gas phase and capillary and phase absorption effects for the liquid phase. Heat transport occurs by means of conduction with thermal conductivity dependent on water saturation, convection, and binary diffusion, which includes both sensible and latent heat. 2 - Method of solution: All
ECRH and electron heat transport in tokamaks

International Nuclear Information System (INIS)

Zou, X.L.; Giruzzi, G.; Dumont, R.J.

2003-01-01

It has been observed during the ECRH experiments in tokamaks that the shape of the electron temperature profile in stationary regimes is not very sensitive to the ECRH power deposition i.e. the temperature profile remains peaked at the center even though the ECRH power deposition is off-axis. Various models have been invoked for the interpretation of this profile resilience phenomenon: the inward heat pinch, the critical temperature gradient, the Self-Organized Criticality, etc. Except the pinch effect, all of these models need a specific form of the diffusivity in the heat transport equation. In this work, our approach is to solve a simplified time-dependent heat transport equation analytically in cylindrical geometry. The features of this analytical solution are analyzed, in particular the relationship between the temperature profile resilience and the Eigenmode of the physical system with respect to the heat transport phenomenon. Finally, applications of this analytical solution for the determination of the transport coefficient and the polarization of the EC waves are presented. It has been shown that the solution of the simplified transport equation in a finite cylinder is a Fourier-Bessel series. This series represents in fact a decomposition of the heat source in Eigenmode, which are characterized by the Bessel functions of order 0. The physical interpretation of the Eigenmodes is the following: when the heat source is given by a Bessel function of order 0, the temperature profile has exactly the same form as the source at every time. At the beginning of the power injection, the effectiveness of the temperature response is the same for each Eigenmode, and the response in temperature, having the same form as the source, is local. Conversely, in the later phase of the evolution, the effectiveness of the temperature response for each Eigenmode is different: the higher the order, the lower the effectiveness. In this case the response in temperature appears as
Safe and Environmentally Acceptable Sol-Gel-Derived Pyrophoric Pyrotechnics

National Research Council Canada - National Science Library

Simpson, Randall L; Hubble, William; Stevenson, Bradley; Gash, Alexander; Satcher, Joe; Metcalf, Patricia

2004-01-01

It was demonstrated that highly porous sol-gel derived iron (III) oxide materials could be reduced to sub-micron-sized metallic iron by heating the materials to intermediate temperatures in a hydrogen atmosphere...
Sol-gel derived antireflective coatings for silicon

Energy Technology Data Exchange (ETDEWEB)

Brinker, C J; Harrington, M S

1981-08-01

The preparation of TiO2-SiO2 AR coatings, containing from 30 to 95 mol % TiO2, from alkoxide precursor solutions (titanium tetraethoxide and silicon tetraethoxide) by a sol-gel process is presented. The preparation of the solutions is described, which involves the separate partial hydrolysis of one or both alkoxides prior to their mixing (Yoldas, 1980). The solutions are applied to polished, circular (1 and 2 in. diameter) silicon wafers by a spinning process. The coated wafers are successively heated in air at each of the following temperatures: 200, 300, 350, 400, and 450 C, and optical measurements are performed on them after each heat treatment. The durability of 90 and 95% TiO2 coatings is evaluated in both acidic and basic environments, and reflectivity, film thickness, and refractive index are measured as a function of exposure time. It is shown that sol-gel films applied at 400 C reveal broad regions of antireflectance compared to other titanium-based films.
Miniature Heat Transport System for Spacecraft Thermal Control

Science.gov (United States)

Ochterbeck, Jay M.; Ku, Jentung (Technical Monitor)

2002-01-01

Loop heat pipes (LHP) are efficient devices for heat transfer and use the basic principle of a closed evaporation-condensation cycle. The advantage of using a loop heat pipe over other conventional methods is that large quantities of heat can be transported through a small cross-sectional area over a considerable distance with no additional power input to the system. By using LHPs, it seems possible to meet the growing demand for high-power cooling devices. Although they are somewhat similar to conventional heat pipes, LHPs have a whole set of unique properties, such as low pressure drops and flexible lines between condenser and evaporator, that make them rather promising. LHPs are capable of providing a means of transporting heat over long distances with no input power other than the heat being transported because of the specially designed evaporator and the separation of liquid and vapor lines. For LHP design and fabrication, preliminary analysis on the basis of dimensionless criteria is necessary because of certain complicated phenomena that take place in the heat pipe. Modeling the performance of the LHP and miniaturizing its size are tasks and objectives of current research. In the course of h s work, the LHP and its components, including the evaporator (the most critical and complex part of the LHP), were modeled with the corresponding dimensionless groups also being investigated. Next, analysis of heat and mass transfer processes in the LHP, selection of the most weighted criteria from known dimensionless groups (thermal-fluid sciences), heat transfer rate limits, (heat pipe theory), and experimental ratios which are unique to a given heat pipe class are discussed. In the third part of the report, two-phase flow heat and mass transfer performances inside the LHP condenser are analyzed and calculated for Earth-normal gravity and microgravity conditions. On the basis of recent models and experimental databanks, an analysis for condensing two-phase flow regimes
Policies and initiatives for carbon neutrality in nordic heating and transport systems

DEFF Research Database (Denmark)

Muller, Jakob Glarbo; Wu, Qiuwei; Ostergaard, Jacob

2012-01-01

Policies and initiatives promoting carbon neutrality in the Nordic heating and transport systems are presented. The focus within heating systems is the propagation of heat pumps while the focus within transport systems is initiatives regarding electric vehicles (EVs). It is found that conversion...... to heat pumps in the Nordic region rely on both private economic and national economic incentives. Initiatives toward carbon neutrality in the transport system are mostly concentrated on research, development and demonstration for deployment of a large number of EVs. All Nordic countries have plans...... for the future heating and transport systems with the ambition of realizing carbon neutrality....
Synthesis of cadmium tungstate films via sol-gel processing

Energy Technology Data Exchange (ETDEWEB)

Lennstrom, Kirk; Limmer, Steven J.; Cao Guozhong

2003-06-23

Cadmium tungstate is a scintillator material with excellent intrinsic photoluminescent properties. It is highly resistant to gamma radiation, has an almost non-existent afterglow and is highly efficient. Cadmium tungstate is also non-hydroscopic, unlike the more prevalent thallium-doped alkali halide scintillators. In order to create thin films of cadmium tungstate with precise stoichiometric control, a sol-gel processing technique has been applied to produce this material for the first time. In addition to lower processing temperatures, sol-gel-derived cadmium tungstate is cheaper and easier than other technologies, particularly for thin films. Furthermore, it has the potential to produce nanostructured materials with good optical quality. X-Ray diffraction results of sol-gel-derived materials fired at various temperatures imply crystallization of cadmium tungstate without the intermediate formation of either tungsten oxide or cadmium oxide. Scanning electron microscopy analysis shows the formation of nano-sized particles prior to heat treatment, which form meso-sized particles after the heat treatment. Photoluminesce analysis indicates emission of derived films at 480 nm, which agrees with other published data. Finally, the efficiency of derived films was approximately 6%{+-}1.8%.
Transport in Auxiliary Heated NSTX Discharges

International Nuclear Information System (INIS)

LeBlanc, B.P.; Bell, M.G.; Bell, R.E.; Bitte, M.L.; Bourdelle, C.; Gates, D.A.; Kaye, S.M.; Maingi, R.; Menard, J.E.; Mueller, D.; Ono, M.; Paul, S.F.; Redi, M.H.; Roquemore, A.L.; Rosenberg, A.; Sabbagh, S.A.; Stutman, D.; Synakowski, E.J.; Soukhanovskii, V.A.; Wilson, J.R.

2003-01-01

The NSTX spherical torus (ST) provides a unique platform to investigate magnetic confinement in auxiliary-heated plasmas at low aspect ratio. Auxiliary power is routinely coupled to ohmically heated plasmas by deuterium neutral-beam injection (NBI) and by high-harmonic fast waves (HHFW) launch. While theory predicts both techniques to preferentially heat electrons, experiment reveals the electron temperature is greater than the ion temperature during HHFW, but the electron temperature is less than the ion temperature during NBI. In the following we present the experimental data and the results of transport analyses
Sol-gel growth of vanadium dioxide

International Nuclear Information System (INIS)

Speck, K.R.

1990-01-01

This thesis examines the chemical reactivity of vanadium (IV) tetrakis(t-butoxide) as a precursor for the sol-gel synthesis of vanadium dioxide. Hydrolysis and condensation of the alkoxide was studied by FTIR spectroscopy. Chemical modification of the vanadium tetraalkoxide by alcohol interchange was studied using 51 V NMR and FTIR. Vanadium dioxide thin films and powders were made from vanadium tetrakis(t-butoxide) by standard sol-gel techniques. Post-deposition heating under nitrogen was necessary to transform amorphous gels into vanadium dioxide. Crystallization of films and powders was studied by FTIR, DSC, TGA, and XRD. Gel-derived vanadium dioxide films undergo a reversible semiconductor-to-metal phase transition near 68C, exhibiting characteristic resistive and spectral changes. The electrical resistance decreased by two to three orders of magnitude and the infrared transmission sharply dropped as the material was cycled through this thermally induced phase transition. The sol-gel method was also used to make doped vanadium dioxide films. Films were doped with tungsten and molybdenum ions to effectively lower the temperature at which the transition occurs
Electron heat transport analysis of low-collisionality plasmas in the neoclassical-transport-optimized configuration of LHD

International Nuclear Information System (INIS)

Murakami, Sadayoshi; Yamada, Hiroshi; Wakasa, Arimitsu

2002-01-01

Electron heat transport in low-collisionality LHD plasma is investigated in order to study the neoclassical transport optimization effect on thermal plasma transport with an optimization level typical of so-called ''advanced stellarators''. In the central region, a higher electron temperature is obtained in the optimized configuration, and transport analysis suggests the considerable effect of neoclassical transport on the electron heat transport assuming the ion-root level of radial electric field. The obtained experimental results support future reactor design in which the neoclassical and/or anomalous transports are reduced by magnetic field optimization in a non-axisymmetric configuration. (author)
Generalized heat-transport equations: parabolic and hyperbolic models

Science.gov (United States)

Rogolino, Patrizia; Kovács, Robert; Ván, Peter; Cimmelli, Vito Antonio

2018-03-01

We derive two different generalized heat-transport equations: the most general one, of the first order in time and second order in space, encompasses some well-known heat equations and describes the hyperbolic regime in the absence of nonlocal effects. Another, less general, of the second order in time and fourth order in space, is able to describe hyperbolic heat conduction also in the presence of nonlocal effects. We investigate the thermodynamic compatibility of both models by applying some generalizations of the classical Liu and Coleman-Noll procedures. In both cases, constitutive equations for the entropy and for the entropy flux are obtained. For the second model, we consider a heat-transport equation which includes nonlocal terms and study the resulting set of balance laws, proving that the corresponding thermal perturbations propagate with finite speed.
Results from transient transport experiments in Rijnhuizen tokamak project: Heat convection, transport barriers and 'non-local' effects

International Nuclear Information System (INIS)

Mantica, P.; Gorini, G.; Hogeweij, G.M.D.; Kloe, J. de; Lopez Cardozo, N.J.; Schilham, A.M.R.

2001-01-01

An overview of experimental transport studies performed on the Rijnhuizen Tokamak Project (RTP) using transient transport techniques in both Ohmic and ECH dominated plasmas is presented. Modulated Electron Cyclotron Heating (ECH) and oblique pellet injection (OPI) have been used to induce electron temperature (T e ) perturbations at different radial locations. These were used to probe the electron transport barriers observed near low order rational magnetic surfaces in ECH dominated steady-state RTP plasmas. Layers of inward electron heat convection in off-axis ECH plasmas were detected with modulated ECH. This suggests that RTP electron transport barriers consist of heat pinch layers rather than layers of low thermal diffusivity. In a different set of experiments, OPI triggered a transient rise of the core T e due to an increase of the T e gradient in the 1< q<2 region. These transient transport barriers were probed with modulated ECH and found to be due to a transient drop of the electron heat diffusivity, except for off-axis ECH plasmas, where a transient inward pinch is also observed. Transient transport studies in RTP could not solve this puzzling interplay between heat diffusion and convection in determining an electron transport barrier. They nevertheless provided challenging experimental evidence both for theoretical modelling and for future experiments. (author)
Preparation of TiO2 thin films from autoclaved sol containing needle-like anatase crystals

International Nuclear Information System (INIS)

Ge Lei; Xu Mingxia; Fang Haibo; Sun Ming

2006-01-01

A new inorganic sol-gel method was introduced in this paper to prepare TiO 2 thin films. The autoclaved sol with needle-like anatase crystals was synthesized using titanyl sulfate (TiOSO 4 ) and peroxide (H 2 O 2 ) as starting materials. The transparent anatase TiO 2 thin films were prepared on glass slides from the autoclaved sol by sol-gel dip-coating method. A wide range of techniques such as Fourier transform infrared transmission spectra (FT-IR), X-ray diffraction (XRD), thermogravimetry-differential thermal analysis (TG-DTA), scanning electron microscopes, X-ray photoelectron spectroscopy (XPS) and ultraviolet-visible spectrum were applied to characterize the autoclaved sol and TiO 2 thin films. The results indicate that the autoclaved sol is flavescent, semitransparent and stable at room temperature. The anatase crystals of TiO 2 films connect together to form net-like structure after calcined and the films become uniform with increasing heating temperature. The surface of the TiO 2 films contain not only Ti and O elements, but also a small amount of N and Na elements diffused from substrates during heat treatment. The TiO 2 films are transparent and their maximal light transmittances exceed 80% under visible light region
Influence of heat treatment on bond strength and corrosion resistance of sol-gel derived bioglass-ceramic coatings on magnesium alloy.

Science.gov (United States)

Shen, Sibo; Cai, Shu; Xu, Guohua; Zhao, Huan; Niu, Shuxin; Zhang, Ruiyue

2015-05-01

In this study, bioglass-ceramic coatings were prepared on magnesium alloy substrates through sol-gel dip-coating route followed by heat treatment at the temperature range of 350-500°C. Structure evolution, bond strength and corrosion resistance of samples were studied. It was shown that increasing heat treatment temperature resulted in denser coating structure as well as increased interfacial residual stress. A failure mode transition from cohesive to adhesive combined with a maximum on the measured bond strength together suggested that heat treatment enhanced the cohesion strength of coating on the one hand, while deteriorated the adhesion strength of coating/substrate on the other, thus leading to the highest bond strength of 27.0MPa for the sample heat-treated at 450°C. This sample also exhibited the best corrosion resistance. Electrochemical tests revealed that relative dense coating matrix and good interfacial adhesion can effectively retard the penetration of simulated body fluid through the coating, thus providing excellent protection for the underlying magnesium alloy. Copyright © 2015 Elsevier Ltd. All rights reserved.
Heat transport system

International Nuclear Information System (INIS)

Pierce, B.L.

1978-01-01

A heat transport system of small size which can be operated in any orientation consists of a coolant loop containing a vaporizable liquid as working fluid and includes in series a vaporizer, a condenser and two one-way valves and a pressurizer connected to the loop between the two valves. The pressurizer may be divided into two chambers by a flexible diaphragm, an inert gas in one chamber acts as a pneumatic spring for the system. This system is suitable for use in a nuclear-powered artificial heart
Integrated heat transport simulation of high ion temperature plasma of LHD

International Nuclear Information System (INIS)

Murakami, S.; Yamaguchi, H.; Sakai, A.

2014-10-01

A first dynamical simulation of high ion temperature plasma with carbon pellet injection of LHD is performed by the integrated simulation GNET-TD + TASK3D. NBI heating deposition of time evolving plasma is evaluated by the 5D drift kinetic equation solver, GNET-TD and the heat transport of multi-ion species plasma (e, H, He, C) is studied by the integrated transport simulation code, TASK3D. Achievement of high ion temperature plasma is attributed to the 1) increase of heating power per ion due to the temporal increase of effective charge, 2) reduction of effective neoclassical transport with impurities, 3) reduction of turbulence transport. The reduction of turbulence transport is most significant contribution to achieve the high ion temperature and the reduction of the turbulent transport from the L-mode plasma (normal hydrogen plasma) is evaluated to be a factor about five by using integrated heat transport simulation code. Applying the Z effective dependent turbulent reduction model we obtain a similar time behavior of ion temperature after the C pellet injection with the experimental results. (author)
Ballistic near-field heat transport in dense many-body systems

Science.gov (United States)

Latella, Ivan; Biehs, Svend-Age; Messina, Riccardo; Rodriguez, Alejandro W.; Ben-Abdallah, Philippe

2018-01-01

Radiative heat transport mediated by near-field interactions is known to be superdiffusive in dilute, many-body systems. Here we use a generalized Landauer theory of radiative heat transfer in many-body planar systems to demonstrate a nonmonotonic transition from superdiffusive to ballistic transport in dense systems. We show that such a transition is associated to a change of the polarization of dominant modes. Our findings are complemented by a quantitative study of the relaxation dynamics of the system in the different regimes of heat transport. This result could have important consequences on thermal management at nanoscale of many-body systems.
Enhanced heat transport in environmental systems using microencapsulated phase change materials

Science.gov (United States)

Colvin, D. P.; Mulligan, J. C.; Bryant, Y. G.

1992-01-01

A methodology for enhanced heat transport and storage that uses a new two-component fluid mixture consisting of a microencapsulated phase change material (microPCM) for enhanced latent heat transport is outlined. SBIR investigations for NASA, USAF, SDIO, and NSF since 1983 have demonstrated the ability of the two-component microPCM coolants to provide enhancements in heat transport up to 40 times over that of the carrier fluid alone, enhancements of 50 to 100 percent in the heat transfer coefficient, practically isothermal operation when the coolant flow is circulated in an optimal manner, and significant reductions in pump work.
Experimental study on the supercritical startup and heat transport capability of a neon-charged cryogenic loop heat pipe

International Nuclear Information System (INIS)

Guo, Yuandong; Lin, Guiping; He, Jiang; Bai, Lizhan; Zhang, Hongxing; Miao, Jianyin

2017-01-01

Highlights: • A neon-charged CLHP integrated with a G-M cryocooler was designed and investigated. • The CLHP can realize the supercritical startup with an auxiliary heat load of 1.5 W. • Maximum heat transport capability of the CLHP was 4.5 W over a distance of 0.6 m. • There existed an optimum auxiliary heat load to expedite the supercritical startup. • There existed an optimum charged pressure to reach the largest heat transfer limit. - Abstract: Neon-charged cryogenic loop heat pipe (CLHP) can realize efficient cryogenic heat transport in the temperature range of 30–40 K, and promises great application potential in the thermal control of future space infrared exploration system. In this work, extensive experimental studies on the supercritical startup and heat transport capability of a neon-charged CLHP integrated with a G-M cryocooler were carried out, where the effects of the auxiliary heat load applied to the secondary evaporator and charged pressure of the working fluid were investigated. Experimental results showed that the CLHP could successfully realize the supercritical startup with an auxiliary heat load of 1.5 W, and there existed an optimum auxiliary heat load and charged pressure of the working fluid respectively, to achieve the maximum temperature drop rate of the primary evaporator during the supercritical startup. The CLHP could reach a maximum heat transport capability of 4.5 W over a distance of 0.6 m corresponding to the optimum charged pressure of the working fluid; however, the heat transport capability decreased with the increase of the auxiliary heat load. Furthermore, the inherent mechanisms responsible for the phenomena observed in the experiments were analyzed and discussed, to provide a better understanding from the theoretical view.

Sol-gel derived ZnO as an electron transport layer (ETL) for inverted organic solar cells

Science.gov (United States)

Tiwari, D. C.; Dwivedi, Shailendra Kumar; Dipak, Phukhrambam; Chandel, Tarun; Sharma, Rishi

2017-05-01

In this work, we present the study of the fabrication process of the sol-gel derived zinc oxide (ZnO) as an electron transport layer (ETL.). The solution processed inverted bulk heterojunction organic solar cells based on a thin film blend of poly (3-hexylthiophene 2, 5-diyl) and [6,6]-phenyl-C61-butyric acid methyl ester is prepared. ZnO thin films are annealed at different temperature to optimize the solar cell performance and their characterization for their structural and optical properties are carried out. We have observed Voc=70mV, Jsc=1.33 µA/cm2 and FF=26% from the inverted heterojunction solar cell.
Observations of the effects of magnetic topology on the SOL characteristics of an electromagnetic coherent mode in the first experimental campaign of W7-X

Science.gov (United States)

Liu, S. C.; Liang, Y.; Drews, P.; Krämer-Flecken, A.; Han, X.; Nicolai, D.; Satheeswaran, G.; Wang, N. C.; Cai, J. Q.; Charl, A.; Cosfeld, J.; Fuchert, G.; Gao, Y.; Geiger, J.; Grulke, O.; Henkel, M.; Hirsch, M.; Hoefel, U.; Hollfeld, K. P.; Höschen, D.; Killer, C.; Knieps, A.; König, R.; Neubauer, O.; Pasch, E.; Rahbarnia, K.; Rack, M.; Sandri, N.; Sereda, S.; Schweer, B.; Wang, E. H.; Wei, Y. L.; Weir, G.; Windisch, T.; W7-X Team

2018-04-01

Turbulence is considered to play an important role in the edge cross field heat and particle transport in fusion devices. Scrape-off layer (SOL) turbulence characteristics were measured by the combined probe mounted on the multi-purpose manipulator during the first experimental campaign of W7-X. An electromagnetic coherent mode (EMCM) at 7 kHz has been observed by multiple diagnostics in both the plasma core and the SOL and exhibits a strong dependence of the magnetic topology. As demonstrated by the measurements of the combined probe, the EMCM starts to appear at a radius of R = 6.15 m along the path of probe measurement and this location is shifted inwards in higher iota configurations. It propagates along the direction of electron diamagnetic drift in the far SOL with a poloidal velocity about 0.6 km s-1 while it turns to the opposite direction gradually in the near SOL in the laboratory frame, but keeps a velocity of about 0.6-0.7 km s-1 along the direction of electron diamagnetic drift in the plasma frame. This mode can be induced by raising the ECRH heating power in similar discharge conditions, which is probably linked to the gradient of electron temperature and pressure. The EMCM is enhanced significantly in the edge magnetic island with long connection length where the EMCM can grow up due to the long particle confinement time.
Core-SOL simulations of L-mode tokamak plasma discharges using BALDUR code

Directory of Open Access Journals (Sweden)

Yutthapong Pinanroj

2014-04-01

Full Text Available Core-SOL simulations were carried out of plasma in tokamak reactors operating in a low confinement mode (L-mode, for various conditions that match available experimental data. The simulation results were quantitatively compared against experimental data, showing that the average RMS errors for electron temperature, ion temperature, and electron density were lower than 16% or less for 14 L-mode discharges from two tokamaks named DIII-D and TFTR. In the simulations, the core plasma transport was described using a combination of neoclassical transport calculated by NCLASS module and anomalous transport by Multi-Mode-Model version 2001 (MMM2001. The scrape-off-layer (SOL is the small amount of residual plasma that interacts with the tokamak vessel, and was simulated by integrating the fluid equations, including sources, along open field lines. The SOL solution provided the boundary conditions of core plasma region on low confinement mode (L-mode. The experimental data were for 14 L-mode discharges and from two tokamaks, named DIII-D and TFTR.
Electron heat transport studies using transient phenomena in ASDEX Upgrade

International Nuclear Information System (INIS)

Jacchia, A.; Angioni, C.; Manini, A.; Ryter, F.; Apostoliceanu, M.; Conway, G.; Fahrbach, H.-U.; Kirov, K.K.; Leuterer, F.; Reich, M.; Sutttrop, W.; Cirant, S.; Mantica, P.; De Luca, F.; Weiland, J.

2005-01-01

Experiments in tokamaks suggest that a critical gradient length may cause the resilient behavior of T e profiles, in the absence of ITBs. This agrees in general with ITG/TEM turbulence physics. Experiments in ASDEX Upgrade using modulation techniques with ECH and/or cold pulses demonstrate the existence of a threshold in R/L Te when T e >T i and T e ≤T i . For T e >T i linear stability analyses indicate that electron heat transport is dominated by TEM modes. They agree in the value of the threshold (both T e and n e ) and for the electron heat transport increase above the threshold. The stabilization of TEM modes by collisions yielded by gyro-kinetic calculations, which suggests a transition from TEM to ITG dominated transport at high collisionality, is experimentally demonstrated by comparing heat pulse and steady-state diffusivities. For the T e ∼T i discharges above the threshold the resilience, normalized by T e 3/2 , is similar to that of the TEM dominated cases, despite very different conditions. The heat pinch predicted by fluid modeling of ITG/TEM turbulence is investigated by perturbative transport in off-axis ECH-heated discharges. (author)
Long-distance heat transport by hot water

International Nuclear Information System (INIS)

Munser, H.; Reetz, B.

1990-01-01

From the analysis of the centralized heat supply in the GDR energy-economical and ecological indispensable developments of long-distance heat systems in conurbation are derived. The heat extraction from a nuclear power plant combined with long- distance hot-water transport over about 110 kilometres is investigated and presented as a possibility to perspective base load heat demands for the district around Dresden. By help of industrial-economic, hydraulic and thermic evaluations of first design variants of the transit system the acceptance of this ecologic and energetic preferred solution is proved and requirements for its realization are shown
Peculiar temperature aging effects on the piezoelectric constant of Pb(Mg1sol3Nb2sol3)O3-PbTiO3 single crystal near the morphotropic phase boundary

International Nuclear Information System (INIS)

Xu Guisheng; Wang Xiaofeng; Yang Danfeng; Duan Ziqing; Feng Chude; Chen Kai

2005-01-01

After temperature aging, peculiar changes of the piezoelectric response of 0.67 Pb(Mg 1sol3 Nb 2sol3 )O 3- 0.33 PbTiO 3 crystals appeared. The piezoelectric constant d 33 of the (001)-cut crystals with T RT ∼35 deg. C abruptly rose more than 1000 pC/N in some regions after heat treatment at 65 deg. C for 12 h. For the (001)-cut crystals with T RT ∼74 deg. C, in spite of a fall of 40-100 pC/N after heat treatment at 65 deg. C for 12 h, the values of d 33 rose 50-100 pC/N unexpectedly after the subsequent heat treatment at 85 deg. C for 4 h. The structure adjustment caused by the internal stress relaxation during heat treatment at T>T RT accounted for the enhancement of d 33
High efficiency heat transport and power conversion system for cascade

International Nuclear Information System (INIS)

Maya, I.; Bourque, R.F.; Creedon, R.L.; Schultz, K.R.

1985-02-01

The Cascade ICF reactor features a flowing blanket of solid BeO and LiAlO 2 granules with very high temperature capability (up to approx. 2300 K). The authors present here the design of a high temperature granule transport and heat exchange system, and two options for high efficiency power conversion. The centrifugal-throw transport system uses the peripheral speed imparted to the granules by the rotating chamber to effect granule transport and requires no additional equipment. The heat exchanger design is a vacuum heat transfer concept utilizing gravity-induced flow of the granules over ceramic heat exchange surfaces. A reference Brayton power cycle is presented which achieves 55% net efficiency with 1300 K peak helium temperature. A modified Field steam cycle (a hybrid Rankine/Brayton cycle) is presented as an alternate which achieves 56% net efficiency
Progress towards modeling tokamak boundary plasma turbulence and understanding its role in setting divertor heat flux widths

Science.gov (United States)

Chen, Bin

2017-10-01

QCMs (quasi-coherent modes) are well characterized in the edge of Alcator C-Mod, when operating in the Enhanced Dα (EDA) H-mode, a promising alternative regime for ELM (edge localized modes) suppressed operation. To improve the understanding of the physics behind the QCMs, three typical C-Mod EDA H-Mode discharges are simulated by BOUT + + using a six-field two-fluid model (based on the Braginskii equations). The simulated characteristics of the frequency versus wave number spectra of the modes is in reasonable agreement with phase contrast imaging data. The key simulation results are: 1) Linear spectrum analysis and the nonlinear phase relationship indicate the dominance of resistive-ballooning modes and drift-Alfven wave instabilities; 2) QCMs originate inside the separatrix; (3) magnetic flutter causes the mode spreading into the SOL; 4) the boundary electric field Er changes the turbulent characteristics of the QCMs and controls edge transport and the divertor heat flux width; 5) the magnitude of the divertor heat flux depends on the physics models, such as sources and sinks, sheath boundary conditions, and parallel heat flux limiting coefficient. The BOUT + + simulations have also been performed for inter-ELM periods of DIII-D and EAST discharges, and similar quasi-coherent modes have been found. The parallel electron heat fluxes projected onto the target from these BOUT + + simulations follow the experimental heat flux width scaling, in particular the inverse dependence of the width on the poloidal magnetic field with an outlier. Further turbulence statistics analysis shows that the blobs are generated near the pedestal peak gradient region inside the separatrix and contribute to the transport of the particle and heat in the SOL region. To understand the Goldston heuristic drift-based model, results will also be presented from self-consistent transport simulations with the electric and magnetic drifts in BOUT + + and with the sheath potential included in the
A review on transportation of heat energy over long distance. Exploratory development

Energy Technology Data Exchange (ETDEWEB)

Ma, Q.; Wang, R.Z. [Institute of Refrigeration and Cryogenics, Shanghai Jiao Tong University, 800 Dongchuan Road, Shanghai 200240 (China); Luo, L.; Sauce, G. [LOCIE, Polytech' Savoie, Campus Scientifique, Savoie Technolac, 73376 Le Bourget-Du-Lac cedex (France)

2009-08-15

This paper presents a review on transportation of heat energy over long distance. For the transportation of high-temperature heat energy, the chemical catalytic reversible reaction is almost the only way available, and there are several reactions have been studied. For the relatively low-temperature heat energy, which exists widely as waste heat, there are mainly five researching aspects at present: chemical reversible reactions, phase change thermal energy storage and transportation, hydrogen-absorbing alloys, solid-gas adsorption and liquid-gas absorption. The basic principles and the characteristics of these methods are discussed. (author)
Fluctuation theory for transport properties in multicomponent mixtures: thermodiffusion and heat conductivity

DEFF Research Database (Denmark)

Shapiro, Alexander

2004-01-01

The theory of transport properties in multicomponent gas and liquid mixtures, which was previously developed for diffusion coefficients, is extended onto thermodiffusion coefficients and heat conductivities. The derivation of the expressions for transport properties is based on the general statis...... of the heat conductivity coefficient for ideal gas. (C) 2003 Elsevier B.V. All rights reserved.......The theory of transport properties in multicomponent gas and liquid mixtures, which was previously developed for diffusion coefficients, is extended onto thermodiffusion coefficients and heat conductivities. The derivation of the expressions for transport properties is based on the general...
Heat and damp transport in cavity bricks. Waerme- und Feuchtetransport in Hochlochziegeln

Energy Technology Data Exchange (ETDEWEB)

Elsner, M

1987-11-19

The aim of this work is a systematic measurement of the structural effect of cavity bricks on the thermal insulation and thermal storage values depending on the material values of the bricks and the mortar. The arrangement and orientation of the hollow spaces and their dimensions should be varied. Brick shapes with socalled handle slots, which give more convenient handling, and with mortar pockets instead of mortar gaps, should be taken into account in the investigation. Special attention should be paid to the heat transport mechanism in the hollow spaces, where thermal conduction, thermal radiation and convection heat transport are superimposed on one another. The second main aim of the work is the calculation of the coupled heat and damp transport in hollow bricks. The heat and damp transport is described by a coupled system of differential equations, where the decisive transport coefficients should be shown as a function of the variables determining the transport processes. (orig./MM).
Sol-gel derived C-SiC composites and protective coatings for sustained durability in the space environment

Science.gov (United States)

Haruvy, Yair; Liedtke, Volker

2003-09-01

Composites and coatings were produced via the fast sol-gel process of a mixture of alkoxysilane precursors. The composites were comprised of carbon fibers, fabrics, or their precursors as reinforcement, and sol-gel-derived silicon carbide as matrix, aiming at high-temperature stable ceramics that can be utilized for re-entry structures. The protective coatings were comprised of fluorine-rich sol-gel derived resins, which exhibit high flexibility and coherence to provide sustained ATOX protection necessary for LEO space-exposed elements. For producing the composites, the sol-gel-derived resin is cast onto the reinforcement fibers/fabrics mat (carbon or its precursors) to produce a 'green' composite that is being cured. The 'green' composite is converted into a C-SiC composite via a gradual heat-pressure process under inert atmosphere, during which the organic substituents on the silicon atoms undergo internal oxidative pyrolysis via the schematic reaction: (SiRO3/2)n -> SiC + CO2 + H2O. The composition of the resultant silicon-oxi-carbide is tailorable via modifying the composition of the sol-gel reactants. The reinforcement, when made of carbon precursors, is converted into carbon during the heat-and-pressure processing as well. The C-SiC composites thus derived exhibit superior thermal stability and comparable thermal conductivity, combined with good mechanical strength features and failure resistance, which render them greatly applicable for re-entry shielding, heat-exchange pipes, and the like. Fluorine rich sol-gel derived coatings were developed as well, via the use of HF rich sol-gel process. These coatings provide oxidation-protection via the silica formation process, together with flexibility that allows 18,000 repetitive folding of the coating without cracking.
Puesto remisión de V. sol puesto a sol puesto, de.

OpenAIRE

2011-01-01

[ES] Definición del término Puesto remisión de V. sol puesto a sol puesto, de. en el diccionario Dicter. [EN] Definition of the word Puesto remisión de V. sol puesto a sol puesto, de. in the dictionary Dicter.
Dip coating of sol-gels

Science.gov (United States)

Schunk, P. R.; Hurd, A. J.; Brinker, C. J.

Dip coating is the primary means of depositing sol-gel films for precision optical coatings. Sols are typically multicomponent systems consisting of an inorganic phase dispersed in a solvent mixture, with each component differing in volatility and surface tension. This, together with slow coating speeds (less than 1cm/s), makes analysis of the coating process complicated; unlike most high-speed coating methods, solvent evaporation, evolving rheology, and surface tension gradients alter significantly the fluid mechanics of the deposition stage. These phenomena were studied with computer-aided predictions of the flow and species transport fields. The underlying theory involves mass, momentum, and species transport on a domain of unknown shape, with models and constitutive equations for vapor-liquid equilibria and surface tension. Due accounting is made for the unknown position of the free surface, which locates according to the capillary hydrodynamic forces and solvent loss by evaporation. Predictions of the effects of mass transfer, hydrodynamics, and surface tension gradients on final film thickness are compared with ellipsometry measurements of film thickness on a laboratory pilot coater. Although quantitative agreement is still lacking, both experiment and theory reveal that the film profile near the drying line takes on a parabolic shape.
Heat transport the cold way

International Nuclear Information System (INIS)

Anon.

1981-01-01

A novel system for long-distance heat transport is being born in the 'Kernforschungsanlage Juelich' with the project being called 'Nukleare Fernenergie' (nuclear district energy). The project is also known as 'EVA/ADAM' [EVA = Einzelrohr-Versuchs-Anlage (single tube test facility); ADAM = Anlage mit Drei Adiabaten Methanisierungsreaktoren (plant provided with three adiabate methanising reactors)] and is based in principle on transport of energy in chemical bond within a closed loop. In the 60ies already this development was discussed both in the 'Kernforschungsanlage Juelich' and in the 'Rheinische Braunkohlenwerke' independent of each other. In 1975 these two organizations concluded a co-operation contract. (orig.) [de
Dynamic behavior of detached recombining plasmas during ELM-like plasma heat pulses in the divertor plasma simulator NAGDIS-II

International Nuclear Information System (INIS)

Uesugi, Y.; Hattori, N.; Nishijima, D.; Ohno, N.; Takamura, S.

2001-01-01

It has been recognized that the ELMs associated with a good confinement at the edge, such as H-mode, must bring an enormous energy to the divertor target plate through SOL and detached plasmas. The understanding of the ELM energy transport through SOL to the divertor target is rather poor at the moment, which leads to an ambiguous estimation of the deposited heat load on the divertor target in ITER. In the present work the ELM-like plasma heat pulse is generated by rf heating in a linear divertor plasma simulator. Energetic electrons with an energy range 10-40 eV are effectively generated by rf heating in low temperature plasmas with (T e )< ∼1 eV. It is observed experimentally that the energetic electrons ionize the highly excited Rydberg atoms quickly, bringing a rapid increase of the ion particle flux to the target, and make the detached plasmas attached to the target. Detailed physical processes about the interaction between the heat pulse with conduction and convection, and detached recombining plasmas are discussed
Curvature and temperature gradient driven instabilities in tokomak edge plasmas with SOL

International Nuclear Information System (INIS)

Novakovskii, S.V.; Guzdar, P.N.; Drake, J.F.; Liu, C.S.

1996-01-01

Curvature driven resistive ballooning modes (RBM) as well as the electron temperature gradient (ETG) modes have been investigated in the tokomak edge region and the SOL, with the help of the numerical code open-quotes 2D-BALLOONclose quotes. This is an initial value code, which determines the stability properties and estimates the quasi-linear transport for given density, temperature, the magnetic and electric field profiles, taking into account the SOL geometry as well as a closed flux region. The results related to the following issues will be presented: (1) Comparative analysis of the ETG and the RBM instabilities in the SOL and their influence on the transport in the edge region (inside the Last Closed Magnetic Surface). (2) The influence of the effective Debye sheath current. (3) Different poloidal positions of the toroidal limiter and their effect on the instabilities. Other aspects of the edge plasma turbulence, such as finite β effects, flow-shear of the poloidal rotation etc. will also be discussed
Electron heat transport in shaped TCV L-mode plasmas

International Nuclear Information System (INIS)

Camenen, Y; Pochelon, A; Bottino, A; Coda, S; Ryter, F; Sauter, O; Behn, R; Goodman, T P; Henderson, M A; Karpushov, A; Porte, L; Zhuang, G

2005-01-01

Electron heat transport experiments are performed in L-mode discharges at various plasma triangularities, using radially localized electron cyclotron heating to vary independently both the electron temperature T e and the normalized electron temperature gradient R/L T e over a large range. Local gyro-fluid (GLF23) and global collisionless gyro-kinetic (LORB5) linear simulations show that, in the present experiments, trapped electron mode (TEM) is the most unstable mode. Experimentally, the electron heat diffusivity χ e is shown to decrease with increasing collisionality, and no dependence of χ e on R/L T e is observed at high R/L T e values. These two observations are consistent with the predictions of TEM simulations, which supports the fact that TEM plays a crucial role in electron heat transport. In addition, over the broad range of positive and negative triangularities investigated, the electron heat diffusivity is observed to decrease with decreasing plasma triangularity, leading to a strong increase of plasma confinement at negative triangularity
Thaw flow control for liquid heat transport systems

Science.gov (United States)

Kirpich, Aaron S.

1989-01-01

In a liquid metal heat transport system including a source of thaw heat for use in a space reactor power system, the thaw flow throttle or control comprises a fluid passage having forward and reverse flow sections and a partition having a plurality of bleed holes therein to enable fluid flow between the forward and reverse sections. The flow throttle is positioned in the system relatively far from the source of thaw heat.
Preparation and characterization of ZnO transparent semiconductor thin films by sol-gel method

International Nuclear Information System (INIS)

Tsay, Chien-Yie; Fan, Kai-Shiung; Chen, Sih-Han; Tsai, Chia-Hao

2010-01-01

Transparent semiconductor thin films of zinc oxide (ZnO) were deposited onto alkali-free glass substrates by the sol-gel method and spin-coating technique. In this study, authors investigate the influence of the heating rate of the preheating process (4 or 10 o C/min) on the crystallization, surface morphology, and optical properties of sol-gel derived ZnO thin films. The ZnO sol was synthesized by dissolving zinc acetate dehydrate in ethanol, and then adding monoethanolamine. The as-coated films were preheated at 300 o C for 10 min and annealed at 500 o C for 1 h in air ambiance. Experimental results indicate that the heating rate of the preheating process strongly affected the surface morphology and transparency of ZnO thin film. Specifically, a heating rate of 10 o C/min for the preheating process produces a preferred orientation along the (0 0 2) plane and a high transmittance of 92% at a wavelength of 550 nm. Furthermore, this study reports the fabrication of thin-film transistors (TFTs) with a transparent ZnO active channel layer and evaluates their electrical performance.

Perturbative Heat Transport Experiments on TJ-II

International Nuclear Information System (INIS)

Eguilor, S.; Castejon, F.; Luna, E. de la; Cappa, A.; Likin, K.; Fernandez, A.; Tj-II, T.

2002-01-01

Heat wave experiments are performed on TJ-II stellarator plasmas to estimate both heat diffusivity and power deposition profiles. High frequency ECRH modulation experiments are used to obtain the power deposition profiles, which is observed to be wider and duller than estimated by tracing techniques. The causes of this difference are discussed in the paper. Fourier analysis techniques are used to estimate the heat diffusivity in low frequency ECRH modulation experiments. This include the power deposition profile as a new ingredient. ECHR switch on/off experiments are exploited to obtain power deposition and heat diffusivities profile. Those quantities are compared with the obtained by modulation experiments and transport analysis, showing a good agreement. (Author) 18 refs
Perturbative Heat Transport Experiments on TJ-II

Energy Technology Data Exchange (ETDEWEB)

Eguilor, S.; Castejon, F.; Luna, E. de la; Cappa, A.; Likin, K.; Fernandez, A.; Tj-II, T.

2002-07-01

Heat wave experiments are performed on TJ-II stellarator plasmas to estimate both heat diffusivity and power deposition profiles. High frequency ECRH modulation experiments are used to obtain the power deposition profiles, which is observed to be wider and duller than estimated by tracing techniques. The causes of this difference are discussed in the paper. Fourier analysis techniques are used to estimate the heat diffusivity in low frequency ECRH modulation experiments. This include the power deposition profile as a new ingredient. ECHR switch on/off experiments are exploited to obtain power deposition and heat diffusivities profile. Those quantities are compared with the obtained by modulation experiments and transport analysis, showing a good agreement. (Author) 18 refs.
Diffusive and convective transport modelling from analysis of ECRH-stimulated electron heat wave propagation. [ECRH (Electron Cyclotron Resonance Heating)

Energy Technology Data Exchange (ETDEWEB)

Erckmann, V; Gasparino, U; Giannone, L. (Max-Planck-Institut fuer Plasmaphysik, Garching (Germany)) (and others)

1992-01-01

ECRH power modulation experiments in toroidal devices offer the chance to analyze the electron heat transport more conclusively: the electron heat wave propagation can be observed by ECE (or SX) leading to radial profiles of electron temperature modulation amplitude and time delay (phase shift). Taking also the stationary power balance into account, the local electron heat transport can be modelled by a combination of diffusive and convective transport terms. This method is applied to ECRH discharges in the W7-AS stellarator (B=2.5T, R=2m, a[<=]18 cm) where the ECRH power deposition is highly localized. In W7-AS, the T[sub e] modulation profiles measured by a high resolution ECE system are the basis for the local transport analysis. As experimental errors limit the separation of diffusive and convective terms in the electron heat transport for central power deposition, also ECRH power modulation experiments with off-axis deposition and inward heat wave propagation were performed (with 70 GHz o-mode as well as with 140 GHz x-mode for increased absorption). Because collisional electron-ion coupling and radiative losses are only small, low density ECRH discharges are best candidates for estimating the electron heat flux from power balance. (author) 2 refs., 3 figs.
Critical ageing and chemistry of nanocrystalline hydroxyapatite sol-gel solutions

Energy Technology Data Exchange (ETDEWEB)

Chai, C.S.; Gross, K.A.; Kannangara, K.; Ben-Nissan, B. [University of Technology, Sydney, NSW (Australia). Department of Chemistry, Materials and Forensic Sciences; Hanley, L. [University of Illinois at Chicago, (United States). Department of Chemistry

1998-12-31

In previous work we have demonstrated that using alkoxide precursors, it is possible to produce crystalline hydroxyapatite coatings with potential uses in orthopaedic and dental applications. However, to produce monophasic hydroxyapatite coatings, sols must be aged for a minimum of 24 hours prior to deposition. {sup 31}P NMR has been used to analyse chemical changes occurring in the sol during the ageing process and have revealed that P-O-C bonds present in the precursor material are gradually replaced by P-O-Ca bonds with an accompanying change in oxidation state from P(III) to P(V). Thermal analysis was used to examine hydrolysed gels and showed that sols aged less than 24 hours contain unreacted calcium diethoxide which produces CaO upon heating. These findings have been confirmed by x-ray diffraction. Copyright (1998) Australasian Ceramic Society 16 refs., 4 figs.
Critical ageing and chemistry of nanocrystalline hydroxyapatite sol-gel solutions

International Nuclear Information System (INIS)

Chai, C.S.; Gross, K.A.; Kannangara, K.; Ben-Nissan, B.; Hanley, L.

1998-01-01

In previous work we have demonstrated that using alkoxide precursors, it is possible to produce crystalline hydroxyapatite coatings with potential uses in orthopaedic and dental applications. However, to produce monophasic hydroxyapatite coatings, sols must be aged for a minimum of 24 hours prior to deposition. 31 P NMR has been used to analyse chemical changes occurring in the sol during the ageing process and have revealed that P-O-C bonds present in the precursor material are gradually replaced by P-O-Ca bonds with an accompanying change in oxidation state from P(III) to P(V). Thermal analysis was used to examine hydrolysed gels and showed that sols aged less than 24 hours contain unreacted calcium diethoxide which produces CaO upon heating. These findings have been confirmed by x-ray diffraction. Copyright (1998) Australasian Ceramic Society
Non-standard model for electron heat transport for multidimensional hydrodynamic codes

Energy Technology Data Exchange (ETDEWEB)

Nicolai, Ph.; Busquet, M.; Schurtz, G. [CEA/DAM-Ile de France, 91 - Bruyeres Le Chatel (France)

2000-07-01

In simulations of laser-produced plasma, modeling of heat transport requires an artificial limitation of standard Spitzer-Haerm fluxes. To improve heat conduction processing, we have developed a multidimensional model which accounts for non-local features of heat transport and effects of self-generated magnetic fields. This consistent treatment of both mechanisms has been implemented in a two-dimensional radiation-hydrodynamic code. First results indicate good agreements between simulations and experimental data. (authors)
Non-standard model for electron heat transport for multidimensional hydrodynamic codes

International Nuclear Information System (INIS)

Nicolai, Ph.; Busquet, M.; Schurtz, G.

2000-01-01

In simulations of laser-produced plasma, modeling of heat transport requires an artificial limitation of standard Spitzer-Haerm fluxes. To improve heat conduction processing, we have developed a multidimensional model which accounts for non-local features of heat transport and effects of self-generated magnetic fields. This consistent treatment of both mechanisms has been implemented in a two-dimensional radiation-hydrodynamic code. First results indicate good agreements between simulations and experimental data. (authors)
Magnetically Modulated Heat Transport in a Global Simulation of Solar Magneto-convection

Energy Technology Data Exchange (ETDEWEB)

Cossette, Jean-Francois [Laboratory for Atmospheric and Space Physics, Campus Box 600, University of Colorado, Boulder, CO 80303 (United States); Charbonneau, Paul [Département de Physique, Université de Montréal, C.P. 6128, Succ. Centre-Ville, Montréal, QC H3C 3J7 (Canada); Smolarkiewicz, Piotr K. [European Centre for Medium-Range Weather Forecasts, Reading, RG2 9AX (United Kingdom); Rast, Mark P., E-mail: Jean-Francois.Cossette@lasp.colorado.edu, E-mail: paulchar@astro.umontreal.ca, E-mail: smolar@ecmwf.int, E-mail: Mark.Rast@lasp.colorado.edu [Department of Astrophysical and Planetary Sciences, Laboratory for Atmospheric and Space Physics, Campus Box 391, University of Colorado, Boulder, CO 80303 (United States)

2017-05-20

We present results from a global MHD simulation of solar convection in which the heat transported by convective flows varies in-phase with the total magnetic energy. The purely random initial magnetic field specified in this experiment develops into a well-organized large-scale antisymmetric component undergoing hemispherically synchronized polarity reversals on a 40 year period. A key feature of the simulation is the use of a Newtonian cooling term in the entropy equation to maintain a convectively unstable stratification and drive convection, as opposed to the specification of heating and cooling terms at the bottom and top boundaries. When taken together, the solar-like magnetic cycle and the convective heat flux signature suggest that a cyclic modulation of the large-scale heat-carrying convective flows could be operating inside the real Sun. We carry out an analysis of the entropy and momentum equations to uncover the physical mechanism responsible for the enhanced heat transport. The analysis suggests that the modulation is caused by a magnetic tension imbalance inside upflows and downflows, which perturbs their respective contributions to heat transport in such a way as to enhance the total convective heat flux at cycle maximum. Potential consequences of the heat transport modulation for solar irradiance variability are briefly discussed.
Heat transport analysis in a district heating and snow melting system in Sapporo and Ishikari, Hokkaido applying waste heat from GTHTR300

International Nuclear Information System (INIS)

Kasahara, Seiji; Kamiji, Yu; Terada, Atsuhiko; Yan Xing; Inagaki, Yoshiyuki; Murata, Tetsuya; Mori, Michitsugu

2015-01-01

A district heating and snow melting system utilizing waste heat from Gas Turbine High temperature Gas Reactor of 300 MW_e (GTHTR300), a heat-electricity cogeneration design of high temperature gas-cooled reactor, was analyzed. Application areas are set in Sapporo and Ishikari, the heavy snowfall cities in Northern Japan. The heat transport analyses are carried out by modeling the components in the system; pipelines of the secondary water loops between GTHTR300s and heat demand district and heat exchangers to transport the heat from the secondary water loops to the tertiary loops in the district. Double pipe for the secondary loops are advantageous for less heat loss and smaller excavation area. On the other hand, these pipes has disadvantage of more electricity consumption for pumping. Most of the heat demand in the month of maximum requirement can be supplied by 2 GTHTR300s and delivered by 9 secondary loops and around 5000 heat exchangers. Closer location of GTHTR300 site to the heat demand district is largely advantageous economically. Less decrease of the distance from 40 km to 20 km made the heat loss half and cost of the heat transfer system 22% smaller. (author)
Poloidal inhomogeneity of the particle fluctuation induced fluxes near of the LCFS at lower hybrid heating and improved confinement transition at the FT-2 tokamak

International Nuclear Information System (INIS)

Lashkul, S.I.; Altukhov, A.B.; Gurchenko, A.D.; Gusakov, E.Z.; Dyachenko, V.V.; Esipov, L.A.; Kantor, M.Y.; Kouprienko, D.V.; Stepanov, A.Y.; Sharpeonok, A.P.; Shatalin, S.V.; Vekshina, E.O.

2004-01-01

This paper present our observations and conclusions about development of the transport process at the plasma periphery of the small tokamak FT-2 during additional Lower Hybrid Heating (LHH), when external (ETB) transport barrier followed by Internal (ITB) transport barrier is observed. The peculiarities of the variations of the fluctuation fluxes near periphery are measured by three moveable multi-electrode Langmuir probes (L-probe) located in the same poloidal cross-section of the chamber. So the observed L-H transition and ETB formation after LHH and the associated negative E r rise result mainly from the decrease of the electron temperature (T e ) near inner region of the LCFS (last close flux surface) by greater extent than in SOL (scrape-off layer). This effect is stimulated by decrease of the input power and decrease of the radial correlation coefficient (for r equals 74-77 mm) (and radial particle fluctuation-induced Γ(t)) resulted from ITB formation mechanism during LHH. T e variation in the SOL after LH heating pulse takes place to a lesser extent. Observed non-monotonic radial profile of T e near LCFS with positive δT e /δr rise is kept constant obviously by large longitudinal conductivity and poloidal fluxes from the hotter limiter shadow regions because of the poloidal inhomogeneity of the T e (SOL) and n e (SOL). Such induced negative E r after RF pulse gives fast rise to a quasi-steady-state Γ 0 (t) drift fluxes with reversed direction structure, like 'zonal flows', which may inhibit transport across the flow. Large rise of grad(n e ) after LHH near LCFS with L-H transition is observed after the end of LH pulse for a long time - about 10-15 ms
Heat Transport in Gapped Spin-Chain Systems

International Nuclear Information System (INIS)

Shimshoni, E.

2006-01-01

Full Text: We study the contribution of magnetic excitations to the heat transport in gapped spin-chain systems. These systems are characterized by a substantially enhanced heat conductivity, which can be traced back to the existence of weakly violated conservation laws. We focus particularly on the behavior of clean two-leg spin ladder compounds, where one-dimensional exotic spin excitations are coupled to three-dimensional phonons. We show that the contributions of the two types of heat carriers can not be easily disentangled. Depending on the ratios of spin gaps and the Debye energy, the heat conductivity can be either exponentially increasing or exponentially decreasing as a function of temperature (T). In addition, the magnetic contribution to the total heat conductivity may be either positive or negative. We discuss its T-dependence in various possible regimes, and note that in most regimes it is dominated by spin-phonon drag: the two types of heat carriers have almost the
Salt-assisted and salt-suppressed sol-gel transitions of methylcellulose in water.

Science.gov (United States)

Xu, Y; Wang, C; Tam, K C; Li, L

2004-02-03

The effects of various salts on the sol-gel transition of aqueous methylcellulose (MC) solutions have been studied systematically by means of a micro differential scanning calorimeter. It was found that the heating process was endothermic while the cooling process was exothermic for both MC solutions with and without salts. The addition of salts did not change the patterns of gelation and degelation of MC. However, the salts could shift the sol-gel transition and the gel-sol transition to lower or higher temperatures from a pure MC solution, depending on the salt type. These opposite effects were termed the salt-assisted and salt-suppressed sol-gel transitions. Either the salt-assisted transition or the salt-suppressed sol-gel transition was a function of salt concentration. In addition, each salt was found to have its own concentration limit for producing a stable aqueous solution of MC at a given concentration of MC, which was related to the anionic charge density of the salt. Cations were proved to have weaker effects than anions. The "salt-out strength", defined as the salt effect per mole of anion, was obtained for each anion studied. The thermodynamic mechanisms involved in the salt-assisted and salt-suppressed sol-gel transitions are discussed.
Subcooled He II heat transport in the channel with abrupt contractions/enlargements

International Nuclear Information System (INIS)

Maekawa, R.; Iwamoto, A.; Hamaguchi, S.; Mito, T.

2002-01-01

Heat transport mechanisms for subcooled He II in the channel with abrupt contractions and/or enlargements have been investigated under steady state conditions. The channel, made of G-10, contains various contraction geometries to simulate the cooling channel of a superconducting magnet. In other words, contractions are periodically placed along the channel to simulate the spacers within the magnet winding. A copper block heater inputs the heat to the channel from one end, while the other end is open to the He II bath. Temperature profiles were measured with temperature sensors embedded in the channel as a function of heat input. Calculations were performed using a simple one-dimensional turbulent heat transport equation and with geometric factor consideration. The effects on heat transport mechanisms in He II caused by abrupt change of channel geometry and size are discussed
The conversion of the thermal energy of plasma in the SOL of tokamaks

International Nuclear Information System (INIS)

Nedospasov, A.V.; Nenova, N.V.

2008-01-01

When the plasma expands across the confining magnetic field, a part of its thermal energy is converted to electrical energy. In the SOL of tokamaks, the motion of the plasma across the field due to turbulent processes is accompanied by its departure along the open lines of the magnetic field. The conversion of thermal energy is taken into account in theoretical studies devoted to the physics of plasma in the SOL; however, this conversion is ignored in numerical models, for example, in B2-SOLPS4.0. This paper deals with thermal-to-electrical energy conversion in the SOL of tokamaks. It is demonstrated that the part of the thermal energy subjected to conversion to electrical energy forms an appreciable part of the total energy flowing in the SOL. In ITER, this fraction may be as high as 20-25%. The electrical energy generated in the SOL volume is liberated in the form of Joule heat in a relatively cold plasma in the vicinity of diverter plates or directly on these plates. (letter)
A sol-gel method to synthesize indium tin oxide nanoparticles

Institute of Scientific and Technical Information of China (English)

Xiuhua Li; Xiujuan xu; Xin Yin; Chunzhong Li; Jianrong Zhang

2011-01-01

Transparent conductive indium tin oxide (ITO) nanoparticles were synthesized by a novel sol-gel method.Granulated indium and tin were dissolved in HNO3 and partially complexed with citric acid.A sol-gel process was induced when tertiary butyl alcohol was added dropwise to the above solution.ITO nanoparticles with an average crystallite size of 18.5 nm and surface area of 32.6 m2/g were obtained after the gel was heat-treated at 700 C.The ITO nanoparticles showed good sinterability,the starting sintering temperature decreased sharply to 900 C,and the 1400 C sintered pellet had a density of 98.1 ％ of theoretical density (TD).
Comparison of temperature estimates from heat transport model and electrical resistivity tomography during a shallow heat injection and storage experiment

OpenAIRE

Hermans, Thomas; Daoudi, Moubarak; Vandenbohede, Alexander; Robert, Tanguy; Caterina, David; Nguyen, Frédéric

2012-01-01

Groundwater resources are increasingly used around the world as geothermal systems. Understanding physical processes and quantification of parameters determining heat transport in porous media is therefore important. Geophysical methods may be useful in order to yield additional information with greater coverage than conventional wells. We report a heat transport study during a shallow heat injection and storage field test. Heated water (about 50°C) was injected for 6 days at the rate of 80 l...
Development of cobalt ferrite powder preparation employing the sol-gel technique and its structural characterization

International Nuclear Information System (INIS)

Sajjia, M.; Oubaha, M.; Prescott, T.; Olabi, A.G.

2010-01-01

Research highlights: This work focuses on the sol-gel process and the effects that the initial parameters have on the final product, which is the cobalt ferrite powder, in addition to the heat treatment. Particular interest is devoted to understand how the crosslinker and the chelating agent work and affect the final product. - Abstract: This work focuses on the development of a method to make cobalt ferrite powder using the sol-gel process. A particular emphasis is devoted to the understanding of the role of the chemical parameters involved in the sol-gel technique, and of the heat treatment on the structures and morphologies of the materials obtained. Several samples of cobalt ferrite powder were obtained by varying the initial parameters of the process in addition to the heat treatment temperature. X-ray diffraction and scanning electron microscopy were used to identify the structure and morphology of samples demonstrating the influence of the initial parameters. DTA/TGA was carried out on two standard samples to identify important reaction temperatures during the heat treatment. The average size of the nano crystallites was estimated for a sample by the full width at half maximum (FWHM) of the strongest X-ray diffraction (XRD) peak. It has been found that the chelating agent and the crosslinker have a critical influence on the resultant structure, the particle size and the particle size distribution.
Influence of New Sol-gel Refractory Coating on the Casting Properties of Cold Box and Furan Cores for Grey Cast iron

DEFF Research Database (Denmark)

Nwaogu, Ugochukwu Chibuzoh; Poulsen, T.; Bischoff, C

2010-01-01

New Sol-Gel coated sand cores made from coldbox and furan binder systems were investigated. The idea of the coating was to improve the surface quality of castings. Grey iron was cast on the cores in a sand casting process. The effect of the high temperature of the melt on the cores was assessed...... by measuring the heating curves. The viscosity of the coating, moisture content and the permeability of the cores were evaluated. The surface quality of the castings was investigated using SEM and OM. The results show that the moisture content of the cores affected the permeability. In furan cores the vapour...... transport zone (VTZ) when in contact with the melt is larger than it is in a coldbox which means the furan cores have higher moisture content. The new sol-gel coating has the potential for improving the surface quality of castings without negative effects on the graphite distribution. The surface...
Slow Release of Plant Volatiles Using Sol-Gel Dispensers.

Science.gov (United States)

Bian, L; Sun, X L; Cai, X M; Chen, Z M

2014-12-01

The black citrus aphid, also known as the tea aphid, (Toxoptera aurantii Boyer) attacks economically important crops, including tea (Camellia sinensis (L.) O. Kuntze). In the current study, silica sol-gel formulations were screened to find one that could carry and release C. sinensis plant volatiles to lure black citrus aphids in a greenhouse. The common plant volatile trans-2-hexen-1-al was used as a model molecule to screen for suitable sol-gel formulations. A zNose (Electronic Sensor Technology, Newbury Park, CA) transportable gas chromatograph was used to continuously monitor the volatile emissions. A sol-gel formulation containing tetramethyl orthosilicate and methyltrimethoxysilane in an 8:2 (vol:vol) ratio was selected to develop a slow-release dispenser. The half-life of trans-2-hexen-1-al in the sol-gel dispenser increased slightly with the volume of this compound in the dispenser. Ten different volatiles were tested in the sol-gel dispenser. Alcohols of 6-10 carbons had the longest half-lives (3.01-3.77 d), while esters of 6-12 carbons had the shortest (1.53-2.28 d). Release of these volatiles from the dispensers could not be detected by the zNose after 16 d (cis-3-hexenyl acetate) to 26 d (3,7-dimethylocta-1,6-dien-3-ol). In greenhouse experiments, trans-2-hexen-1-al and cis-3-hexen-1-ol released from the sol-gel dispensers attracted aphids for ≍17 d, and release of these volatiles could not be detected by the zNose after ≍24 d. The sol-gel dispensers performed adequately for the slow release of plant volatiles to trap aphids in the greenhouse. © 2014 Entomological Society of America.
Zirconia/Hydroxyapatite Composites Synthesized Via Sol-Gel: Influence of Hydroxyapatite Content and Heating on Their Biological Properties

Science.gov (United States)

Bollino, Flavia; Armenia, Emilia; Tranquillo, Elisabetta

2017-01-01

Zirconia (ZrO2) and zirconia-based glasses and ceramics are materials proposed for use in the dental and orthopedic fields. In this work, ZrO2 glass was modified by adding different amounts of bioactive and biocompatible hydroxyapatite (HAp). ZrO2/HAp composites were synthesized via the sol-gel method and heated to different temperatures to induce modifications of their chemical structure, as ascertained by Fourier transform infrared spectroscopy (FTIR) analysis. The aim was to investigate the effect of both HAp content and heating on the biological performances of ZrO2. The materials’ bioactivity was studied by soaking samples in a simulated body fluid (SBF). FTIR and scanning electron microscopy (SEM)) analyses carried out after exposure to SBF showed that all materials are bioactive, i.e., they are able to form a hydroxyapatite layer on their surface. Moreover, the samples were soaked in a solution containing bovine serum albumin (BSA). FTIR analysis proved that the synthesized materials are able to adsorb the blood protein, the first step of cell adhesion. WST-8 ([2-(2-methoxy-4-nitrophenyl)-3-(4-nitrophenyl)-5-(2,4-disulfophenyl)-2H-tetrazolium, monosodium salt]) assay showed that no cytotoxicity effects were induced by the materials’ extract. However, the results proved that bioactivity increases with both the HAp content and the temperature used for the thermal treatment, whereas biocompatibility increases with heating but is not affected by the HAp content. PMID:28773116

Durable flame retardant finish for silk fabric using boron hybrid silica sol

Energy Technology Data Exchange (ETDEWEB)

Zhang, Qiang-hua; Gu, Jiali; Chen, Guo-qiang [National Engineering Laboratory for Modern Silk, Soochow University (China); Xing, Tie-ling, E-mail: xingtieling@suda.edu.cn [National Engineering Laboratory for Modern Silk, Soochow University (China); Jiangsu HuaJia Group (China)

2016-11-30

Highlights: • Highly homogeneous boron hybrid silica sol flame retardant system was prepared through sol-gel method. • The silk samples treated and cross-linked by this hybrid sol and BTCA solution showed a higher limiting oxygen index (LOI) more than 31.0% and a better washing durability for more than 30 times washing. • The smoke suppression, combustion performance and thermal stability properties of the treated samples have a significant improvement. - Abstract: A hybrid silica sol was prepared via sol gel method using tetraethoxysilane (TEOS) as a precursor and boric acid (H{sub 3}BO{sub 3}) as flame retardant additive and then applied to silk fabric. In order to endow silk fabric with durable flame retardancy, 1,2,3,4-butanetetracarboxylic acid (BTCA) was used as cross-linking agent for the sake of strong linkage formation between the hybrid silica sol and silk fabric. The FT-IR and XPS analysis demonstrated the Si-O-B formation in the sol system, as well as the linkage between the sol and silk after the treatment. The limiting oxygen index (LOI) and smoke density test indicated good flame retardancy and smoke suppression of the treated silk fabrics. The micro calorimeter combustion (MCC) test and thermo gravimetric (TG) analysis showed that the treated samples had less weight loss in the high temperature and lower heat release rate when burning. The washing durability evaluation results indicated that there was a distinct improvement for the silk samples treated with BTCA even after 30 times washing. In addition, the influence of the processing order of BTCA and silica sol treatment on the limiting oxygen index (LOI) of the finished silk fabric was also investigated. And the results demonstrated that the sample treated with BTCA first and then with the silica sol exhibited better LOI value (32.3%) than that of the sample by the conversed treatment order. Moreover the tensile property of treated samples was nearly unchanged, but the handle of sol treated
MHD stability of the ITER pedestal and SOL plasma and its influence on the heat flux width

NARCIS (Netherlands)

Loarte, A.; Liu, F.; Huijsmans, G.T.A.; Kukushkin, A.S.; Pitts, R.A.

2015-01-01

Proceedings of the 21st International Conference on Plasma-Surface Interactions in Controlled Fusion Devices Kanazawa, Japan May 26-30, 2014 MHD stability of ITER plasmas has been analyzed for QDT = 10 edge and SOL plasma conditions, showing that the SOL plasma is MHD stable down to pressure
Molecular dynamics study on heat transport from single-walled carbon nanotubes to Si substrate

Energy Technology Data Exchange (ETDEWEB)

Feng, Ya; Zhu, Jie, E-mail: zhujie@iet.cn; Tang, Da-Wei

2015-02-06

In this paper, non-equilibrium molecular dynamics simulations were performed to investigate the heat transport between a vertically aligned single-walled carbon nanotube (SWNT) and Si substrate, to find out the influence of temperature and system sizes, including diameter and length of SWNT and measurements of substrate. Results revealed that high temperature hindered heat transport in SWNT itself but was a beneficial stimulus for heat transport at interface of SWNT and Si. Furthermore, the system sizes strongly affected the peaks in vibrational density of states of Si, which led to interfacial thermal conductance dependent on system sizes. - Highlights: • NEMD is performed to simulate the heat transport from SWNT to Si substrate. • We analyze both interfacial thermal conductance and thermal conductivity of SWNT. • High temperature is a beneficial stimulus for heat transport at the interface. • Interfacial thermal conductance strongly depends on the sizes of SWNT and substrate. • We calculate VDOS of C and Si atoms to analyze phonon couplings between them.
Circum-Antarctic Shoreward Heat Transport Derived From an Eddy- and Tide-Resolving Simulation

Science.gov (United States)

Stewart, Andrew L.; Klocker, Andreas; Menemenlis, Dimitris

2018-01-01

Almost all heat reaching the bases of Antarctica's ice shelves originates from warm Circumpolar Deep Water in the open Southern Ocean. This study quantifies the roles of mean and transient flows in transporting heat across almost the entire Antarctic continental slope and shelf using an ocean/sea ice model run at eddy- and tide-resolving (1/48°) horizontal resolution. Heat transfer by transient flows is approximately attributed to eddies and tides via a decomposition into time scales shorter than and longer than 1 day, respectively. It is shown that eddies transfer heat across the continental slope (ocean depths greater than 1,500 m), but tides produce a stronger shoreward heat flux across the shelf break (ocean depths between 500 m and 1,000 m). However, the tidal heat fluxes are approximately compensated by mean flows, leaving the eddy heat flux to balance the net shoreward heat transport. The eddy-driven cross-slope overturning circulation is too weak to account for the eddy heat flux. This suggests that isopycnal eddy stirring is the principal mechanism of shoreward heat transport around Antarctica, though likely modulated by tides and surface forcing.
Characteristics of convective heat transport in a packed pebble-bed reactor

Energy Technology Data Exchange (ETDEWEB)

Abdulmohsin, Rahman S., E-mail: rsar62@mst.edu [Department of Chemical and Biochemical Engineering, Missouri University of Science and Technology, 400 West 11th Street/231 Schrenk Hall, Rolla, MO 65409-1230 (United States); Al-Dahhan, Muthanna H., E-mail: aldahhanm@mst.edu [Department of Chemical and Biochemical Engineering, Missouri University of Science and Technology, 400 West 11th Street/231 Schrenk Hall, Rolla, MO 65409-1230 (United States); Department of Nuclear Engineering, 301 W. 14th St./222 Fulton Hall (United States)

2015-04-01

Highlights: • A fast-response heat transfer probe has been developed and used in this work. • Heat transport has been quantified in terms of local heat transfer coefficients. • The method of the electrically heated single sphere in packing has been applied. • The heat transfer coefficient increases from the center to the wall of packed bed. • This work advancing the knowledge of heat transport in the studied packed bed. - Abstract: Obtaining more precise results and a better understanding of the heat transport mechanism in the dynamic core of packed pebble-bed reactors is needed because this mechanism poses extreme challenges to the reliable design and efficient operation of these reactors. This mechanism can be quantified in terms of a solid-to-gas convective heat transfer coefficient. Therefore, in this work, the local convective heat transfer coefficients and their radial profiles were measured experimentally in a separate effect pilot-plant scale and cold-flow experimental setup of 0.3 m in diameter, using a sophisticated noninvasive heat transfer probe of spherical type. The effect of gas velocity on the heat transfer coefficient was investigated over a wide range of Reynolds numbers of practical importance. The experimental investigations of this work include various radial locations along the height of the bed. It was found that an increase in coolant gas flow velocity causes an increase in the heat transfer coefficient and that effect of the gas flow rate varies from laminar to turbulent flow regimes at all radial positions of the studied packed pebble-bed reactor. The results show that the local heat transfer coefficient increases from the bed center to the wall due to the change in the bed structure, and hence, in the flow pattern of the coolant gas. The findings clearly indicate that one value of an overall heat transfer coefficient cannot represent the local heat transfer coefficients within the bed; therefore, correlations are needed to
Preparation of Flame Retardant Polyacrylonitrile Fabric Based on Sol-Gel and Layer-by-Layer Assembly.

Science.gov (United States)

Ren, Yuanlin; Huo, Tongguo; Qin, Yiwen; Liu, Xiaohui

2018-03-23

This paper aims to develop a novel method, i.e., sol-gel combined with layer-by-layer assembly technology, to impart flame retardancy on polyacrylonitrile (PAN) fabrics. Silica-sol was synthesized via the sol-gel process and acted as cationic solution, and phytic acid (PA) was used as the anionic medium. Flame-retardant-treated PAN fabric (FR-PAN) could achieve excellent flame retardancy with 10 bilayer (10BL) coating through layer-by-layer assembly. The structure of the fabrics was characterized by X-ray photoelectron spectroscopy (XPS) and Fourier transform infrared spectroscopy (FTIR). The thermal stability and flame retardancy were evaluated by thermogravimetric (TG) analysis, cone calorimetry (CC) and limiting oxygen index (LOI). The LOI value of the coated fabric was up to 33.2 vol % and the char residue at 800 °C also increased to 57 wt %. Cone calorimetry tests revealed that, compared to the control fabric, the peak of heat release rate (PHRR) and total heat release (THR) of FR-PAN decreased by 66% and 73%, respectively. These results indicated that sol-gel combined with layer-by-layer assembly technique could impart PAN fabric with satisfactory flame-retardant properties, showing an efficient flame retardant strategy for PAN fabric.
Measurement of inner wall limiter SOL widths in KSTAR tokamak

Directory of Open Access Journals (Sweden)

J.G. Bak

2017-08-01

Full Text Available Scrape-off layer (SOL widths λq are presented from the KSTAR tokamak using fast reciprocating Langmuir probe assembly (FRLPA measurements at the outboard mid-plane (OMP and the infra-Red (IR thermography at inboard limiter tiles in moderately elongated (κ = 1.45 – 1.55 L-mode inner wall-limited (IWL plasmas under experimental conditions such as BT = 2.0 T, PNBI = 1.4 – 1.5 MW, line averaged densities 2.5 – 5.1 × 1019 m−3 and plasma current Ip = 0.4 − 0.7 MA. There is clear evidence for a double exponential structure in q||(r from the FRLPA such that, for example at Ip = 0.6 MA, a narrow feature, λq,near (=3.5 mm is found close to the LFCS, followed by a broader width, λq,main (=57.0 mm. Double exponential profiles (λq,near = 1.5 – 2.8 mm, λq,main = 17.0 – 35.0 mm can be also observed in the IR heat flux mapped to the OMP throughout the range of Ip investigated. In addition, analysis of SOL turbulence statistics obtained with the FRLPA shows high relative fluctuation levels and positively skewed distributions in electron temperature and ion particle flux across the SOL, with both properties increasing for longer distance from the LCFS, as often previously observed in the tokamaks. Interestingly, the fluctuation character expressed in terms of spectral distributions remains unchanged in passing from the narrow to the broad SOL heat flux channel.
A low-frequency wave motion mechanism enables efficient energy transport in carbon nanotubes at high heat fluxes.

Science.gov (United States)

Zhang, Xiaoliang; Hu, Ming; Poulikakos, Dimos

2012-07-11

The great majority of investigations of thermal transport in carbon nanotubes (CNTs) in the open literature focus on low heat fluxes, that is, in the regime of validity of the Fourier heat conduction law. In this paper, by performing nonequilibrium molecular dynamics simulations we investigated thermal transport in a single-walled CNT bridging two Si slabs under constant high heat flux. An anomalous wave-like kinetic energy profile was observed, and a previously unexplored, wave-dominated energy transport mechanism is identified for high heat fluxes in CNTs, originated from excited low frequency transverse acoustic waves. The transported energy, in terms of a one-dimensional low frequency mechanical wave, is quantified as a function of the total heat flux applied and is compared to the energy transported by traditional Fourier heat conduction. The results show that the low frequency wave actually overtakes traditional Fourier heat conduction and efficiently transports the energy at high heat flux. Our findings reveal an important new mechanism for high heat flux energy transport in low-dimensional nanostructures, such as one-dimensional (1-D) nanotubes and nanowires, which could be very relevant to high heat flux dissipation such as in micro/nanoelectronics applications.
Mobile heat accumulators for lorry or train transport?; Mobile Waermespeicher fuer den LKW- oder Zugtransport?

Energy Technology Data Exchange (ETDEWEB)

Goldenberg, Philipp

2013-07-01

Where heat grids cannot be laid for geographic reasons, mobile heat accumulators may be appropriate. The mobile heat accumulators are transported by lorry or train between the heat source and the heat sink. The waste heat can be decoupled from biogas plants, waste incineration plants or industrial sites. Existing road or rail networks can be used for transportation. Decisive factors to achieve low heat production costs are: free waste heat, large and continuous heat quantities as well as a short distance between the heat source and the heat sink. (orig.)
Metal-silica sol-gel materials

Science.gov (United States)

Stiegman, Albert E. (Inventor)

2002-01-01

The present invention relates to a single phase metal-silica sol-gel glass formed by the co-condensation of a transition metal with silicon atoms where the metal atoms are uniformly distributed within the sol-gel glass as individual metal centers. Any transition metal may be used in the sol-gel glasses. The present invention also relates to sensor materials where the sensor material is formed using the single phase metal-silica sol-gel glasses. The sensor materials may be in the form of a thin film or may be attached to an optical fiber. The present invention also relates to a method of sensing chemicals using the chemical sensors by monitoring the chromatic change of the metal-silica sol-gel glass when the chemical binds to the sensor. The present invention also relates to oxidation catalysts where a metal-silica sol-gel glass catalyzes the reaction. The present invention also relates to a method of performing oxidation reactions using the metal-silica sol-gel glasses. The present invention also relates to organopolymer metal-silica sol-gel composites where the pores of the metal-silica sol-gel glasses are filled with an organic polymer polymerized by the sol-gel glass.
Stable solutions of nonlocal electron heat transport equations

International Nuclear Information System (INIS)

Prasad, M.K.; Kershaw, D.S.

1991-01-01

Electron heat transport equations with a nonlocal heat flux are in general ill-posed and intrinsically unstable, as proved by the present authors [Phys. Fluids B 1, 2430 (1989)]. A straightforward numerical solution of these equations will therefore lead to absurd results. It is shown here that by imposing a minimal set of constraints on the problem it is possible to arrive at a globally stable, consistent, and energy conserving numerical solution
Multi-machine scaling of the main SOL parallel heat flux width in tokamak limiter plasmas

Czech Academy of Sciences Publication Activity Database

Horáček, Jan; Pitts, R.A.; Adámek, Jiří; Arnoux, G.; Bak, J.-G.; Brezinsek, S.; Dimitrova, Miglena; Goldston, R.J.; Gunn, J. P.; Havlíček, Josef; Hong, S.-H.; Janky, Filip; LaBombard, B.; Marsen, S.; Maddaluno, G.; Nie, L.; Pericoli, V.; Popov, Tsv.; Pánek, Radomír; Rudakov, D.; Seidl, Jakub; Seo, D.S.; Shimada, M.; Silva, C.; Stangeby, P.C.; Viola, B.; Vondráček, Petr; Wang, H.; Xu, G.S.; Xu, Y.

2016-01-01

Roč. 58, č. 7 (2016), č. článku 074005. ISSN 0741-3335 R&D Projects: GA ČR(CZ) GAP205/12/2327; GA ČR(CZ) GA15-10723S; GA MŠk(CZ) LM2011021 EU Projects: European Commission(XE) 633053 - EUROfusion Institutional support: RVO:61389021 Keywords : tokamak * ITER * SOL decay length * SOL width * scaling Subject RIV: BL - Plasma and Gas Discharge Physics OBOR OECD: Fluids and plasma physics (including surface physics) Impact factor: 2.392, year: 2016 http://iopscience.iop.org/article/10.1088/0741-3335/58/7/074005
Thoria sol-gel processes

International Nuclear Information System (INIS)

Matthews, R.B.

1978-10-01

Alternate fuel fabrication techniques are being developed at WNRE as part of the thorium fuel cycle program. The sol-gel techniques are attractive and this report assembles and summarizes information relating to thoria sol-gel fuels. Some background information on the behaviour and advantages of sol-gel fuel forms is presented, followed by a review of relevant colloid chemistry and an explanation of the fundamental steps of sol-gel processes. Finally, several variants to the basic process are reviewed and evaluated. (author)
The adjoint space in heat transport theory

International Nuclear Information System (INIS)

Dam, H. van; Hoogenboom, J.E.

1980-01-01

The mathematical concept of adjoint operators is applied to the heat transport equation and an adjoint equation is defined with a detector function as source term. The physical meaning of the solutions for the latter equation is outlined together with an application in the field of perturbation analysis. (author)
Latent heat increases storage capacity. Heat transport by truck; Latente warmte vergroot opslagcapaciteit. Warmtetransport per vrachtauto is soms heel slim

Energy Technology Data Exchange (ETDEWEB)

De Jong, K.

2012-11-15

The project-group Biomass CHP (combined production of heat and power) organized a tour with a workshop in Dortmund, Germany, September 26, 2012, on storage and transport of heat and biogas. There are several projects in Germany involving road transport of heat by means of containers. A swimming pool in Dortmund already is using this option since 2008. Waste heat from a CHP-installation for landfill gas is collected from a waste dump [Dutch] De projectgroep Biomassa en WKK organiseerde 26 September een excursie met workshop in Dortmund over opslag en transport van warmte en biogas. Er zijn in Duitsland al meerdere projecten waarbij warmte per container over de weg wordt vervoerd. Een Dortmunds zwembad werkt hier al sinds 2008 mee. De restwarmte van een wkk op stortgas wordt opgehaald bij een afvalstortplaats.
Heat transport in low-dimensional materials: A review and perspective

Directory of Open Access Journals (Sweden)

Zhiping Xu

2016-05-01

Full Text Available Heat transport is a key energetic process in materials and devices. The reduced sample size, low dimension of the problem and the rich spectrum of material imperfections introduce fruitful phenomena at nanoscale. In this review, we summarize recent progresses in the understanding of heat transport process in low-dimensional materials, with focus on the roles of defects, disorder, interfaces, and the quantum-mechanical effect. New physics uncovered from computational simulations, experimental studies, and predictable models will be reviewed, followed by a perspective on open challenges.
Integral representation of nonlinear heat transport

International Nuclear Information System (INIS)

Kishimoto, Y.; Mima, K.; Haines, M.G.

1985-07-01

The electron distribution function in a plasma with steep temperature gradient is obtained from a Fokker-Planck equation by Green's function method. The formula describes the nonlocal effects on thermal transport over the range, λ e /L e /L → 0. As an example, the heat wave is analyzed numerically by the integral formula and it is found that the previous simulation results are well reproduced. (author)
Moment approach to neoclassical flows, currents and transport in auxiliary heated tokamaks

International Nuclear Information System (INIS)

Kim, Yil Bong.

1988-02-01

The moment approach is utilized to derive the full complement of neoclassical transport processes in auxiliary heated tokamaks. The effects of auxiliary heating [neutral beam injection (NBI) and ion cyclotron resonance heating (ICRH)] considered arise from the collisional interaction between the background plasma species and the fast-ion-tail species. From a known fast ion distribution function we evaluate the parallel (to the magnetic field) momentum and heat flow inputs to the background plasma. Then, through the momentum and heat flow balance equations, we can determine the induced parallel flows (and current) and radial transpot fluxes in ''equilibrium'' (on the time scale much longer than the collisional relaxation time, i.e., t >> 1ν/sub ii/). In addition to the fast-ion-induced current, the total neoclassical current includes the boostap current, which is driven by the pressure and temperature gradients, the Pfirsch-Schlueter current which is required for charge neutrality, and the neoclassical (including trapped particle effects) Spitzer current due to the parallel electric field. The radial transport fluxes also include off-diagonal compnents in the transport matrix which correspond to the Ware (neoclassical) pinch due to the inductive applied electric field an the fast-ion-induced radial fluxes, in addition to the usual pressure- and temperature-gradient-driven fluxes (particle diffusion and heat conduction). Once the tranport coefficient are completely determined, the radial fluxes and the heat fluxes can be substituted into the density and energy evolution equations to provide a complete description of ''equilibrium'' (δδt << ν/sub ii/) neoclassical transport processes in a plasma. 47 refs., 14 figs
The Role of Ocean and Atmospheric Heat Transport in the Arctic Amplification

Science.gov (United States)

Vargas Martes, R. M.; Kwon, Y. O.; Furey, H. H.

2017-12-01

Observational data and climate model projections have suggested that the Arctic region is warming around twice faster than the rest of the globe, which has been referred as the Arctic Amplification (AA). While the local feedbacks, e.g. sea ice-albedo feedback, are often suggested as the primary driver of AA by previous studies, the role of meridional heat transport by ocean and atmosphere is less clear. This study uses the Community Earth System Model version 1 Large Ensemble simulation (CESM1-LE) to seek deeper understanding of the role meridional oceanic and atmospheric heat transports play in AA. The simulation consists of 40 ensemble members with the same physics and external forcing using a single fully coupled climate model. Each ensemble member spans two time periods; the historical period from 1920 to 2005 using the Coupled Model Intercomparison Project Phase 5 (CMIP5) historical forcing and the future period from 2006 to 2100 using the CMIP5 Representative Concentration Pathways 8.5 (RCP8.5) scenario. Each of the ensemble members are initialized with slightly different air temperatures. As the CESM1-LE uses a single model unlike the CMIP5 multi-model ensemble, the internal variability and the externally forced components can be separated more clearly. The projections are calculated by comparing the period 2081-2100 relative to the time period 2001-2020. The CESM1-LE projects an AA of 2.5-2.8 times faster than the global average, which is within the range of those from the CMIP5 multi-model ensemble. However, the spread of AA from the CESM1-LE, which is attributed to the internal variability, is 2-3 times smaller than that of the CMIP5 ensemble, which may also include the inter-model differences. CESM1LE projects a decrease in the atmospheric heat transport into the Arctic and an increase in the oceanic heat transport. The atmospheric heat transport is further decomposed into moisture transport and dry static energy transport. Also, the oceanic heat
SOL RF physics modelling in Europe, in support of ICRF experiments

Directory of Open Access Journals (Sweden)

Colas Laurent

2017-01-01

Full Text Available A European project was undertaken to improve the available SOL ICRF physics simulation tools and confront them with measurements. This paper first reviews code upgrades within the project. Using the multi-physics finite element solver COMSOL, the SSWICH code couples RF full-wave propagation with DC plasma biasing over “antenna-scale” 2D (toroidal/radial domains, via non-linear RF and DC sheath boundary conditions (SBCs applied at shaped plasma-facing boundaries. For the different modules and associated SBCs, more elaborate basic research in RF-sheath physics, SOL turbulent transport and applied mathematics, generally over smaller spatial scales, guides code improvement. The available simulation tools were applied to interpret experimental observations on various tokamaks. We focus on robust qualitative results common to several devices: the spatial distribution of RF-induced DC bias; left-right asymmetries over strap power unbalance; parametric dependence and antenna electrical tuning; DC SOL biasing far from the antennas, and RF-induced density modifications. From these results we try to identify the relevant physical ingredients necessary to reproduce the measurements, e.g. accurate radiated field maps from 3D antenna codes, spatial proximity effects from wave evanescence in the near RF field, or DC current transport. Pending issues towards quantitative predictions are also outlined.

Climate in the Absence of Ocean Heat Transport

Science.gov (United States)

Rose, B. E. J.

2015-12-01

The energy transported by the oceans to mid- and high latitudes is small compared to the atmosphere, yet exerts an outsized influence on the climate. A key reason is the strong interaction between ocean heat transport (OHT) and sea ice extent. I quantify this by comparing a realistic control climate simulation with a slab ocean simulation in which OHT is disabled. Using the state-of-the-art CESM with a realistic present-day continental configuration, I show that the absence of OHT leads to a 23 K global cooling and massive expansion of sea ice to near 30º latitude in both hemisphere. The ice expansion is asymmetric, with greatest extent in the South Pacific and South Indian ocean basins. I discuss implications of this enormous and asymmetric climate change for atmospheric circulation, heat transport, and tropical precipitation. Parameter sensitivity studies show that the simulated climate is far more sensitive to small changes in ice surface albedo in the absence of OHT, with some perturbations sufficient to cause a runaway Snowball Earth glaciation. I conclude that the oceans are responsible for an enormous global warming by mitigating an otherwise very potent sea ice albedo feedback, but that the magnitude of this effect is still rather uncertain. I will also present some ideas on adapting the simple energy balance model to account for the enhanced sensitivity of sea ice to heating from the ocean.
Role of ocean heat transport in climates of tidally locked exoplanets around M dwarf stars.

Science.gov (United States)

Hu, Yongyun; Yang, Jun

2014-01-14

The distinctive feature of tidally locked exoplanets is the very uneven heating by stellar radiation between the dayside and nightside. Previous work has focused on the role of atmospheric heat transport in preventing atmospheric collapse on the nightside for terrestrial exoplanets in the habitable zone around M dwarfs. In the present paper, we carry out simulations with a fully coupled atmosphere-ocean general circulation model to investigate the role of ocean heat transport in climate states of tidally locked habitable exoplanets around M dwarfs. Our simulation results demonstrate that ocean heat transport substantially extends the area of open water along the equator, showing a lobster-like spatial pattern of open water, instead of an "eyeball." For sufficiently high-level greenhouse gases or strong stellar radiation, ocean heat transport can even lead to complete deglaciation of the nightside. Our simulations also suggest that ocean heat transport likely narrows the width of M dwarfs' habitable zone. This study provides a demonstration of the importance of exooceanography in determining climate states and habitability of exoplanets.
Diffusive and convective transport modelling from analysis of ECRH-stimulated electron heat wave propagation

International Nuclear Information System (INIS)

Erckmann, V.; Gasparino, U.; Giannone, L.

1992-01-01

ECRH power modulation experiments in toroidal devices offer the chance to analyze the electron heat transport more conclusively: the electron heat wave propagation can be observed by ECE (or SX) leading to radial profiles of electron temperature modulation amplitude and time delay (phase shift). Taking also the stationary power balance into account, the local electron heat transport can be modelled by a combination of diffusive and convective transport terms. This method is applied to ECRH discharges in the W7-AS stellarator (B=2.5T, R=2m, a≤18 cm) where the ECRH power deposition is highly localized. In W7-AS, the T e modulation profiles measured by a high resolution ECE system are the basis for the local transport analysis. As experimental errors limit the separation of diffusive and convective terms in the electron heat transport for central power deposition, also ECRH power modulation experiments with off-axis deposition and inward heat wave propagation were performed (with 70 GHz o-mode as well as with 140 GHz x-mode for increased absorption). Because collisional electron-ion coupling and radiative losses are only small, low density ECRH discharges are best candidates for estimating the electron heat flux from power balance. (author) 2 refs., 3 figs
MICROSTRUCTURE CHARACTERISTIC OF ALUMINUM TITANATE SYNTHESIED BY BOTH SOLID- STATE AND SOL-GEL PROCESSES

Directory of Open Access Journals (Sweden)

M. Khosravi Saghezchi

2015-12-01

Full Text Available A comparing study on formation and microstructure features of aluminum titanate is investigated through both solid-state and sol-gel processes. Aluminum titanate formed by firing at 1350ºC and 1450ºC for 4h in solid-state process. In the sol-gel process formation of submicron sized particles is followed by addition of sucrose into the transparent sol. XRD analysis was confirmed the formation of aluminum titanate at 1400ºC in lower duration of calcination (3h without any additives in the sol-gel process. In this work 2wt% MgO is added to the samples as the additive for forming acceleration of aluminum titanate. The influence of MgO addition and heat treatment are studied on phase formation and microstructure development of aluminum titanate in both procedures. Additive optimizes aluminum titanate formation at lower temperatures (1300-1350ºC. Phase and microstructure studies of Mg containing samples optimally show significance in aluminum titanate formation.
Magnetic-field asymmetry of nonlinear thermoelectric and heat transport

International Nuclear Information System (INIS)

Hwang, Sun-Yong; Sánchez, David; López, Rosa; Lee, Minchul

2013-01-01

Nonlinear transport coefficients do not obey, in general, reciprocity relations. We here discuss the magnetic-field asymmetries that arise in thermoelectric and heat transport of mesoscopic systems. Based on a scattering theory of weakly nonlinear transport, we analyze the leading-order symmetry parameters in terms of the screening potential response to either voltage or temperature shifts. We apply our general results to a quantum Hall antidot system. Interestingly, we find that certain symmetry parameters show a dependence on the measurement configuration. (paper)
Latent heat transport and microlayer evaporation in nucleate boiling

International Nuclear Information System (INIS)

Jawurek, H.H.

1977-08-01

Part 1 of this work provides a broad overview and, where possible, a quantitative assessment of the complex physical processes which together constitute the mechanism of nucleate boiling heat transfer. It is shown that under a wide range of conditions the primary surface-to-liquid heat flows within an area of bubble influence are so redistributed as to manifest themselves predominantly as latent heat transport, that is, as vaporisation into attached bubbles. Part 2 deals in greater detail with one of the component processes of latent heat transport, namely microlayer evaporation. A literature review reveals the need for synchronised records of microlayer geometry versus time and of normal bubble growth and departure. An apparatus developed to provide such records is described. High-speed cine interference photography from beneath and through a transparent heating surface provided details of microlayer geometry and an image reflection system synchronised these records with the bubble profile views. Results are given for methanol and ethanol boiling at sub-atmospheric pressures and at various heat fluxes and bulk subcoolings. In all cases it is found that microlayers were of sub-micron thickness, that microlayer thinning was restricted to the inner layer edge (with the thickness elsewhere remaining constant or increasing with time) and that the contribution of this visible evaporation to the total vapour flow into bubbles was negligible. The observation of thickening towards the outer microlayer edge, however, demonstrates that a liquid replenishment flow occurred simultaneously with the evaporation process
Expedition sol

DEFF Research Database (Denmark)

Jacobsen, Aase Roland

2006-01-01

Tag på expedition sol rundt i museet. Er der nogen, der har taget en bid af solen? Hvorfor bliver der solformørkelse? Kan vi undvære Solen?......Tag på expedition sol rundt i museet. Er der nogen, der har taget en bid af solen? Hvorfor bliver der solformørkelse? Kan vi undvære Solen?...
Measurements of RF-induced sol modifications in Tore Supra tokamak

International Nuclear Information System (INIS)

Kubic, Martin; Gunn, James P.; Colas, Laurent; Heuraux, Stephane; Faudot, Eric

2012-01-01

Since spring 2011, one of the three ion cyclotron resonance heating (ICRH) antennas in the Tore Supra (TS) tokamak is equipped with a new type of Faraday screen (FS). Results from Radio Frequency (RF) simulations of the new Faraday screen suggest the innovative structure with cantilevered bars and 'shark tooth' openings significantly changes the current flow pattern on the front of the antenna which in turn reduces the RF potential and RF electrical field in particular parallel to the magnetic field lines which contributes to generating RF sheaths. Effects of the new FS operation on RF-induced scrape-off layer (SOL) modifications are studied for different plasma and antenna configurations - scans of strap power ratio imbalance, phasing, injected power and SOL density. (authors)
Study of electronic heat transport in plasma through diagnosis based on modulated electron cyclotron heating; Etudes de transport de la chaleur electronique par injection modulee d'ondes a la frequence cyclotronique electronique

Energy Technology Data Exchange (ETDEWEB)

Clemencon, A.; Guivarch, C

2003-07-01

In order to make nuclear fusion energetically profitable, it is crucial to heat and confine the plasma efficiently. Studying the behavior of the heat diffusion coefficient is a key issue in this matter. The use of modulated electron cyclotron heating as a diagnostic has suggested the existence of a transport barrier under certain plasma conditions. We have determined the solution to the heat transport equation, for several heat diffusion coefficient profiles. By comparing the analytical solutions with experimental data; we are able to study the heat diffusion coefficient profile. Thus, in certain experiments, we can confirm that the heat diffusion coefficient switches from low to high values at the radius where the electron cyclotron heat deposition is made. (authors)
Thermophysical and heat transfer properties of phase change material candidate for waste heat transportation system

Science.gov (United States)

Kaizawa, Akihide; Maruoka, Nobuhiro; Kawai, Atsushi; Kamano, Hiroomi; Jozuka, Tetsuji; Senda, Takeshi; Akiyama, Tomohiro

2008-05-01

A waste heat transportation system trans-heat (TH) system is quite attractive that uses the latent heat of a phase change material (PCM). The purpose of this paper is to study the thermophysical properties of various sugars and sodium acetate trihydrate (SAT) as PCMs for a practical TH system and the heat transfer property between PCM selected and heat transfer oil, by using differential scanning calorimetry (DSC), thermogravimetry-differential thermal analysis (TG-DTA) and a heat storage tube. As a result, erythritol, with a large latent heat of 344 kJ/kg at melting point of 117°C, high decomposition point of 160°C and excellent chemical stability under repeated phase change cycles was found to be the best PCM among them for the practical TH system. In the heat release experiments between liquid erythritol and flowing cold oil, we observed foaming phenomena of encapsulated oil, in which oil droplet was coated by solidification of PCM.
First-principles simulations of heat transport

Science.gov (United States)

Puligheddu, Marcello; Gygi, Francois; Galli, Giulia

2017-11-01

Advances in understanding heat transport in solids were recently reported by both experiment and theory. However an efficient and predictive quantum simulation framework to investigate thermal properties of solids, with the same complexity as classical simulations, has not yet been developed. Here we present a method to compute the thermal conductivity of solids by performing ab initio molecular dynamics at close to equilibrium conditions, which only requires calculations of first-principles trajectories and atomic forces, thus avoiding direct computation of heat currents and energy densities. In addition the method requires much shorter sequential simulation times than ordinary molecular dynamics techniques, making it applicable within density functional theory. We discuss results for a representative oxide, MgO, at different temperatures and for ordered and nanostructured morphologies, showing the performance of the method in different conditions.
Heat transport in an anharmonic crystal

Science.gov (United States)

Acharya, Shiladitya; Mukherjee, Krishnendu

2018-04-01

We study transport of heat in an ordered, anharmonic crystal in the form of slab geometry in three dimensions. Apart from attaching baths of Langevin type to two extreme surfaces, we also attach baths of same type to the intermediate surfaces of the slab. Since the crystal is uninsulated, it exchanges energy with the intermediate heat baths. We find that both Fourier’s law of heat conduction and the Newton’s law of cooling hold to leading order in anharmonic coupling. The leading behavior of the temperature profile is exponentially falling from high to low temperature surface of the slab. As the anharmonicity increases, profiles fall more below the harmonic one in the log plot. In the thermodynamic limit thermal conductivity remains independent of the environment temperature and its leading order anharmonic contribution is linearly proportional to the temperature change between the two extreme surfaces of the slab. A fast crossover from one-dimensional (1D) to three-dimensional (3D) behavior of the thermal conductivity is observed in the system.
Mesoscale Eddies in the Northwestern Pacific Ocean: Three-Dimensional Eddy Structures and Heat/Salt Transports

Science.gov (United States)

Dong, Di; Brandt, Peter; Chang, Ping; Schütte, Florian; Yang, Xiaofeng; Yan, Jinhui; Zeng, Jisheng

2017-12-01

The region encompassing the Kuroshio Extension (KE) in the Northwestern Pacific Ocean (25°N-45°N and 130°E-180°E) is one of the most eddy-energetic regions of the global ocean. The three-dimensional structures and transports of mesoscale eddies in this region are comprehensively investigated by combined use of satellite data and Argo profiles. With the allocation of Argo profiles inside detected eddies, the spatial variations of structures of eddy temperature and salinity anomalies are analyzed. The results show that eddies predominantly have subsurface (near-surface) intensified temperature and salinity anomalies south (north) of the KE jet, which is related to different background stratifications between these regions. A new method based on eddy trajectories and the inferred three-dimensional eddy structures is proposed to estimate heat and salt transports by eddy movements in a Lagrangian framework. Spatial distributions of eddy transports are presented over the vicinity of the KE for the first time. The magnitude of eddy-induced meridional heat (freshwater volume) transport is on the order of 0.01 PW (103 m3/s). The eddy heat transport divergence results in an oceanic heat loss south and heat gain north of the KE, thereby reinforcing and counteracting the oceanic heat loss from air-sea fluxes south and north of the KE jet, respectively. It also suggests a poleward heat transport across the KE jet due to eddy propagation.
Fabrication of YBa2Cu3O7-δ superconducting fibers by the sol-gel method

International Nuclear Information System (INIS)

Umeda, Tetsu; Kozuka, Hiromitsu; Sakka, Sumio

1988-01-01

High-T c superconducting oxide fibers were fabricated by the sol-gel method. An aqueous solution of metal acetates was concentrated to form a viscous sol, from which gel fibers were spun. The gel fibers, 5 to 1,000 μm in diameter, were converted to ceramic fibers by heating to 900 degree C. The fired fibers (T c (onset) of 94 K and T c (end) of 62.2 K) were rough and had porous microstructures
Solar-energy heats a transportation test center--Pueblo, Colorado

Science.gov (United States)

1981-01-01

Petroleum-base, thermal energy transport fluid circulating through 583 square feet of flat-plate solar collectors accumulates majority of energy for space heating and domestic hot-water of large Test Center. Report describes operation, maintenance, and performance of system which is suitable for warehouses and similar buildings. For test period from February 1979 to January 1980, solar-heating fraction was 31 percent, solar hot-water fraction 79 percent.
Thickness Optimisation of Textiles Subjected to Heat and Mass Transport during Ironing

Directory of Open Access Journals (Sweden)

Korycki Ryszard

2016-09-01

Full Text Available Let us next analyse the coupled problem during ironing of textiles, that is, the heat is transported with mass whereas the mass transport with heat is negligible. It is necessary to define both physical and mathematical models. Introducing two-phase system of mass sorption by fibres, the transport equations are introduced and accompanied by the set of boundary and initial conditions. Optimisation of material thickness during ironing is gradient oriented. The first-order sensitivity of an arbitrary objective functional is analysed and included in optimisation procedure. Numerical example is the thickness optimisation of different textile materials in ironing device.
Systems with a constant heat flux with applications to radiative heat transport across nanoscale gaps and layers

Science.gov (United States)

Budaev, Bair V.; Bogy, David B.

2018-06-01

We extend the statistical analysis of equilibrium systems to systems with a constant heat flux. This extension leads to natural generalizations of Maxwell-Boltzmann's and Planck's equilibrium energy distributions to energy distributions of systems with a net heat flux. This development provides a long needed foundation for addressing problems of nanoscale heat transport by a systematic method based on a few fundamental principles. As an example, we consider the computation of the radiative heat flux between narrowly spaced half-spaces maintained at different temperatures.
Theory-based scaling of the SOL width in circular limited tokamak plasmas

International Nuclear Information System (INIS)

Halpern, F.D.; Ricci, P.; Labit, B.; Furno, I.; Jolliet, S.; Loizu, J.; Mosetto, A.; Arnoux, G.; Silva, C.; Gunn, J.P.; Horacek, J.; Kočan, M.; LaBombard, B.

2013-01-01

A theory-based scaling for the characteristic length of a circular, limited tokamak scrape-off layer (SOL) is obtained by considering the balance between parallel losses and non-linearly saturated resistive ballooning mode turbulence driving anomalous perpendicular transport. The SOL size increases with plasma size, resistivity, and safety factor q. The scaling is verified against flux-driven non-linear turbulence simulations, which reveal good agreement within a wide range of dimensionless parameters, including parameters closely matching the TCV tokamak. An initial comparison of the theory against experimental data from several tokamaks also yields good agreement. (letter)
Sol-gel-processed yttrium-doped NiO as hole transport layer in inverted perovskite solar cells for enhanced performance

Science.gov (United States)

Hu, Zijun; Chen, Da; Yang, Pan; Yang, Lijun; Qin, Laishun; Huang, Yuexiang; Zhao, Xiaochong

2018-05-01

In this work, high-performance inverted planar perovskite solar cells (PSCs) using sol-gel processed Y-doped NiO thin films as hole transport layer (HTL) were demonstrated. Y-doped NiO thin films containing different Y doping concentrations were successfully prepared through a simple sol-gel process. The Y doping could significantly improve the electrical conductivity of NiO thin film, and the photovoltaic performance of Y-doped NiO HTL-based PSC devices outperformed that of the pristine NiO HTL-based device. Notably, the PSC using a 5%Y-NiO HTL exhibited the champion performance with an open-circuit voltage (Voc) of 1.00 V, a short circuit current density (Jsc) of 23.82 mA cm-2, a fill factor (FF) of 68% and a power conversion efficiency (PCE) of 16.31%, resulting in a 27.62% enhancement in PCE in comparison with the NiO device. The enhanced performance of the Y-doped NiO device could be attributed to the improved hole mobility, the high quality compact active layer morphology, the more efficient charge extraction from perovskite absorber as well as the lower recombination probability of charge carriers. Thus, this work provides a simple and effective approach to improve the electrical conductivity of p-type NiO thin films for use as a promising HTL in high performance PSCs.
Parallel SOL transport in MAST and JET: the impact of the mirror force

International Nuclear Information System (INIS)

Kirk, A; Fundamenski, W; Ahn, J-W; Counsell, G

2003-01-01

Interpretative modelling of the SOL plasma in conventional (JET) and tight (MAST) aspect ratio devices has been performed using OSM2/EIRENE. A detailed comparison has been made of the solutions of the fluid equations and one key issue uncovered by this modelling is the significance of the mirror force for the spherical tokamak (ST) SOL. This force is proportional to ∇ parallel B/B, which is typically a factor 10 larger in an ST due to the low aspect ratio. This term leads to changes in the charged particle velocity distributions near regions with large V parallel B/B representing an effective, upstream particle and momentum source. The modelling performed in this paper indicates that exclusion of the ∇ parallel B term may lead to incorrect conclusions on, for example, the upstream density, especially in STs

Control of long range turbulent transport with biasing in the tokamak scrape-off-layer

International Nuclear Information System (INIS)

Figarella, C.F.; Ghendrih, Ph.; Sarazin, Y.; Attuel, G.; Benkadda, S.; Beyer, P.; Falchetto, G.; Fleurence, E.; Garbet, X.; Grandgirard, V.

2005-01-01

Cross-field transport in the SOL influences tokamak performance in particular regarding the divertor efficiency. Recent experiment evidence emphasizes non-exponential and/or flat SOL profiles that suggest a large perpendicular transport. A 2D fluid model based on the interchange instability to simulate the SOL turbulence was found to exhibits intermittent dynamics of the particle flux. We propose a control method that prevents long range transport events from reaching the far SOL: It consists in biasing the far SOL leading to a transport barrier which stops the propagation of these intermittent events. The best trade off is to localize the biased toroidal ring around the baffles. We show that such a control is achievable providing the strength of the barrier is strong enough. The investigation of the minimal biasing power required to achieve the control as well as its experimental estimate is performed
Control of long range turbulent transport with biasing in the tokamak scrape-off-layer

International Nuclear Information System (INIS)

Figarella, C.F.; Ghendrih, Ph.; Sarazin, Y.; Attuel, G.; Falchetto, G.; Fleurence, E.; Garbet, X.; Grandgirard, V.

2004-01-01

Cross field transport in the SOL (scrape-off-layer) influences tokamak performance in particular regarding the divertor efficiency. Recent experiment evidence emphasizes non-exponential and/or flat SOL profiles that suggest a large perpendicular transport. A 2-dimensional fluid model based on the interchange instability to simulate the SOL turbulence was found to exhibits intermittent dynamics of the particle flux. We propose a control method that prevents long range transport events from reaching the far SOL: It consists in biasing the far SOL leading to a transport barrier which stops the propagation of these intermittent events. The best trade off is to localize the biased toroidal ring around the baffles. We show that such a control is achievable providing the strength of the barrier is strong enough. The investigation of the minimal biasing power required to achieve the control as well as its experimental estimate is performed. (authors)
Study of the electron heat transport in Tore-Supra tokamak

International Nuclear Information System (INIS)

Harauchamps, E.

2004-01-01

This work presents analytical solutions to the electron heat transport equation involving a damping term and a convection term in a cylindrical geometry. These solutions, processed by Matlab, allow the determination of the evolution of the radial profile of electron temperature in tokamaks during heating. The modulated injection of waves around the electron cyclotron frequency is an efficient tool to study heat transport experimentally in tokamaks. The comparison of these analytical solutions with experimental results from Tore-Supra during 2 discharges (30550 and 31165) shows the presence of a sudden change for the diffusion and damping coefficients. The hypothesis of the presence of a pinch spread all along the plasma might explain the shape of the experimental temperature profiles. These analytical solutions could be used to determine the time evolution of plasma density as well or of any parameter whose evolution is governed by a diffusion-convection equation. (A.C.)
Oxygen transport membrane system and method for transferring heat to catalytic/process reactors

Science.gov (United States)

Kelly, Sean M; Kromer, Brian R; Litwin, Michael M; Rosen, Lee J; Christie, Gervase Maxwell; Wilson, Jamie R; Kosowski, Lawrence W; Robinson, Charles

2014-01-07

A method and apparatus for producing heat used in a synthesis gas production is provided. The disclosed method and apparatus include a plurality of tubular oxygen transport membrane elements adapted to separate oxygen from an oxygen containing stream contacting the retentate side of the membrane elements. The permeated oxygen is combusted with a hydrogen containing synthesis gas stream contacting the permeate side of the tubular oxygen transport membrane elements thereby generating a reaction product stream and radiant heat. The present method and apparatus also includes at least one catalytic reactor containing a catalyst to promote the stream reforming reaction wherein the catalytic reactor is surrounded by the plurality of tubular oxygen transport membrane elements. The view factor between the catalytic reactor and the plurality of tubular oxygen transport membrane elements radiating heat to the catalytic reactor is greater than or equal to 0.5.
Oxygen transport membrane system and method for transferring heat to catalytic/process reactors

Science.gov (United States)

Kelly, Sean M.; Kromer, Brian R.; Litwin, Michael M.; Rosen, Lee J.; Christie, Gervase Maxwell; Wilson, Jamie R.; Kosowski, Lawrence W.; Robinson, Charles

2016-01-19

A method and apparatus for producing heat used in a synthesis gas production process is provided. The disclosed method and apparatus include a plurality of tubular oxygen transport membrane elements adapted to separate oxygen from an oxygen containing stream contacting the retentate side of the membrane elements. The permeated oxygen is combusted with a hydrogen containing synthesis gas stream contacting the permeate side of the tubular oxygen transport membrane elements thereby generating a reaction product stream and radiant heat. The present method and apparatus also includes at least one catalytic reactor containing a catalyst to promote the steam reforming reaction wherein the catalytic reactor is surrounded by the plurality of tubular oxygen transport membrane elements. The view factor between the catalytic reactor and the plurality of tubular oxygen transport membrane elements radiating heat to the catalytic reactor is greater than or equal to 0.5
Analysis for Heat Transfer in a High Current-Passing Carbon Nanosphere Using Nontraditional Thermal Transport Model.

Science.gov (United States)

Hol C Y; Chen, B C; Tsai, Y H; Ma, C; Wen, M Y

2015-11-01

This paper investigates the thermal transport in hollow microscale and nanoscale spheres subject to electrical heat source using nontraditional thermal transport model. Working as supercapacitor electrodes, carbon hollow micrometer- and nanometer-sized spheres needs excellent heat transfer characteristics to maintain high specific capacitance, long cycle life, and high power density. In the nanoscale regime, the prediction of heat transfer from the traditional heat conduction equation based on Fourier's law deviates from the measured data. Consequently, the electrical heat source-induced heat transfer characteristics in hollow micrometer- and nanometer-sized spheres are studied using nontraditional thermal transport model. The effects of parameters on heat transfer in the hollow micrometer- and nanometer-sized spheres are discussed in this study. The results reveal that the heat transferred into the spherical interior, temperature and heat flux in the hollow sphere decrease with the increasing Knudsen number when the radius of sphere is comparable to the mean free path of heat carriers.
Numerical simulation of the transport phenomena due to sudden heating in porous media

Energy Technology Data Exchange (ETDEWEB)

Lei, S.Y.; Zheng, G.Y.; Wang, B.X.; Yang, R.G.; Xia, C.M.

1997-07-01

Such process as wet porous media suddenly heated by hot fluids frequently occurs in nature and in industrial applications. The three-variable simulation model was developed to predict violent transport phenomena due to sudden heating in porous media. Two sets of independent variables were applied to different regions in porous media in the simulation. For the wet zone, temperature, wet saturation and air pressure were used as the independent variables. For the dry zone, the independent variables were temperature, vapor pressure and air pressure. The model simulated two complicated transport processes in wet unsaturated porous media which is suddenly heated by melting metal or boiling water. The effect of the gas pressure is also investigated on the overall transport phenomena.
Superhydrophobic properties induced by sol-gel routes on copper surfaces

Science.gov (United States)

Raimondo, M.; Veronesi, F.; Boveri, G.; Guarini, G.; Motta, A.; Zanoni, R.

2017-11-01

Superhydrophobic surfaces are attracting increasing attention in different fields such as energy, transportation, building industry and electronics, as they exhibit many interesting properties such as high water repellence, anti-fogging, anti-corrosion, anti-fouling and self-cleaning abilities. Here, superhydrophobic nanostructured hybrid materials obtained by depositing alumina nanoparticles on copper surfaces via dip coating in Al2O3 sol are presented. Two different preparation routes were explored, based on either an alcoholic or an aqueous Al2O3 sol, and the resulting wetting properties were compared. Wettability measurements showed that when the alcoholic sol is used superhydrophobicity is attained, with values of water contact angle very close to the upper limit of 180°, while highly hydrophobic coatings are obtained with the aqueous sol. These findings were further supported by electron microscopy and X-ray photoelectron spectroscopy, which revealed that the surface layer deposited on Cu is more homogenous and richer in alumina nanoparticles when the alcoholic sol was used. Durability of the superhydrophobic coating was assessed by performing ageing tests in chemically aggressive environments. A remarkable resistance is displayed by the superhydrophobic coating in acid environment, while alkaline conditions severely affect its properties. Such behaviors were investigated by XPS and FE-SEM measurements, which disclosed the nature of the surface reactions under the different conditions tested. The present results underline that a thorough investigation of surface morphology, chemical composition and wetting properties reveals their strongly connection and helps optimizing the combination of substrate nanostructuring and suitable chemical coating for an improved durability in different aggressive environments.
VS2DRTI: Simulating Heat and Reactive Solute Transport in Variably Saturated Porous Media.

Science.gov (United States)

Healy, Richard W; Haile, Sosina S; Parkhurst, David L; Charlton, Scott R

2018-01-29

Variably saturated groundwater flow, heat transport, and solute transport are important processes in environmental phenomena, such as the natural evolution of water chemistry of aquifers and streams, the storage of radioactive waste in a geologic repository, the contamination of water resources from acid-rock drainage, and the geologic sequestration of carbon dioxide. Up to now, our ability to simulate these processes simultaneously with fully coupled reactive transport models has been limited to complex and often difficult-to-use models. To address the need for a simple and easy-to-use model, the VS2DRTI software package has been developed for simulating water flow, heat transport, and reactive solute transport through variably saturated porous media. The underlying numerical model, VS2DRT, was created by coupling the flow and transport capabilities of the VS2DT and VS2DH models with the equilibrium and kinetic reaction capabilities of PhreeqcRM. Flow capabilities include two-dimensional, constant-density, variably saturated flow; transport capabilities include both heat and multicomponent solute transport; and the reaction capabilities are a complete implementation of geochemical reactions of PHREEQC. The graphical user interface includes a preprocessor for building simulations and a postprocessor for visual display of simulation results. To demonstrate the simulation of multiple processes, the model is applied to a hypothetical example of injection of heated waste water to an aquifer with temperature-dependent cation exchange. VS2DRTI is freely available public domain software. © 2018, National Ground Water Association.
Sol-Gel Derived Hafnia Coatings

Science.gov (United States)

Feldman, Jay D.; Stackpoole, Mairead; Blum, Yigal; Sacks, Michael; Ellerby, Don; Johnson, Sylvia M.; Venkatapathy, Ethiras (Technical Monitor)

2002-01-01

Sol-gel derived hafnia coatings are being developed to provide an oxidation protection layer on ultra-high temperature ceramics for potential use in turbine engines (ultra-efficient engine technology being developed by NASA). Coatings using hafnia sol hafnia filler particles will be discussed along with sol synthesis and characterization.
Characterization of the Sol-Gel Transition for Zirconia-Toughened Alumina Precursors

Science.gov (United States)

Moeti, I.; Karikari, E.; Chen, J.

1998-01-01

High purity ZTA ceramic powders with and without yttria were produced using metal alkoxide precursors. ZTA ceramic powders with varying volume percents of zirconia were prepared (7, 15, and 22%). Aluminum tri-sec butoxide, zirconium propoxide, and yttrium isopropoxide were the reagents used. Synthesis conditions were varied to control the hydrolysis and the aging conditions for the sol to gel transition. FTIR analysis and theological characterization were used to follow the structural evolution during the sol to gel transition. The greater extent of hydrolysis and the build-up of structure measured from viscoelastic properties were consistent. Heat treatment was conducted to produce submicron grain fully crystalline ZTA ceramic powders. In all experimental cases a-alumina and tetragonal zirconia phases were confirmed even in the absence of yttria.
Plasma transport in the Scrape-off-Layer of magnetically confined plasma and the plasma exhaust

DEFF Research Database (Denmark)

Rasmussen, Jens Juul; Naulin, Volker; Nielsen, Anders Henry

An overview of the plasma dynamics in the Scrape-off-Layer (SOL) of magnetically confined plasma is presented. The SOL is the exhaust channel of the warm plasma from the core, and the understanding of the SOL plasma dynamics is one of the key issues in contemporary fusion research. It is essential...... for operation of fusion experiments and ultimately fusion power plants. Recent results clearly demonstrate that the plasma transport through the SOL is dominated by turbulent intermittent fluctuations organized into filamentary structures convecting particles, energy, and momentum through the SOL region. Thus......, the transport cannot be described and parametrized by simple diffusive type models. The transport leads to strong localized power loads on the first wall and the plasma facing components, which have serious lasting influence....
Optimizing the design of large-scale ground-coupled heat pump systems using groundwater and heat transport modeling

Energy Technology Data Exchange (ETDEWEB)

Fujii, H.; Itoi, R.; Fujii, J. [Kyushu University, Fukuoka (Japan). Faculty of Engineering, Department of Earth Resources Engineering; Uchida, Y. [Geological Survey of Japan, Tsukuba (Japan)

2005-06-01

In order to predict the long-term performance of large-scale ground-coupled heat pump (GCHP) systems, it is necessary to take into consideration well-to-well interference, especially in the presence of groundwater flow. A mass and heat transport model was developed to simulate the behavior of this type of system in the Akita Plain, northern Japan. The model was used to investigate different operational schemes and to maximize the heat extraction rate from the GCHP system. (author)
Consequences of nonlinear heat transport laws on expected plasma profiles

International Nuclear Information System (INIS)

Lackner, K.

1987-03-01

The expected variation of plasma pressure profiles against changes in power deposition is investigated by using a simple linear heat transport law as well as a quadratic one. Applying the quadratic transport law it can be shown that the stiffening of the resulting profiles is sufficient to understand the experimentally measured phenomenon of 'profile consistence' without further assumptions of nonlocal effects. (orig.) [de
Study on a neon cryogenic oscillating heat pipe with long heat transport distance

Science.gov (United States)

Liang, Qing; Li, Yi; Wang, Qiuliang

2017-12-01

An experimental study is carried out to study the heat transfer characteristics of a cryogenic oscillating heat pipe (OHP) with long heat transport distance. The OHP is made up of a capillary tube with an inner diameter of 1.0 mm and an outer diameter of 2.0 mm. The working fluid is neon, and the length of the adiabatic section is 480 mm. Tests are performed with the different heat inputs, liquid filling ratios and condenser temperature. For the cryogenic OHP with a liquid filling ratio of 30.7% at the condenser temperature of 28 K, the effective thermal conductivity is 3466-30,854 W/m K, and the maximum transfer power is 35.60 W. With the increment of the heat input, the effective thermal conductivity of the cryogenic OHP increases at the liquid filling ratios of 30.7% and 38.5%, while it first increases and then decreases at the liquid filling ratios of 15.2% and 23.3%. Moreover, the effective thermal conductivity increases with decreasing liquid filling ratio at the small heat input, and the maximum transfer power first increases and then decreases with increasing liquid filling ratio. Finally, it is found that the thermal performance of the cryogenic OHP can be improved by increasing the condenser temperature.
Sol-gel technology for biomedical engineering

International Nuclear Information System (INIS)

Podbielska, H.; Ulatowska-Jarza, A.

2005-01-01

Sol-gel derived silica possess many promising features, including low-temperature preparation procedure, porosity, chemical and physical stability. Applications exploiting porous materials to encapsulate sensor molecules, enzymes and many other compounds, are developing rapidly. In this paper some potential applications, with emphasis on biomedical and environmental ones, are reviewed. The material preparation procedure is described and practical remarks on silica-based sol-gels are included. It is reported that sol-gels with entrapped various molecules may be used in construction of implants and coatings with bioactive properties. It is shown how to exploit the sol-gel production route for construction of sol-gel coated fiberoptic applicators for laser therapy. The applications of bioactive materials are discussed, as well. It is demonstrated that it is possible to immobilize photosensitive compounds in sol-gel matrix without loosing their photoactivity. Some examples of sol-gel based biosensors are demonstrated, as well, showing their potential for detecting various gases, toxic substances, acidity, humidity, enzymes and biologically active agents. (authors)
INKJET PRINTING OF ALUMOOXIDE SOL FOR DEPOSITION OF ANTIREFLECTING COATINGS

Directory of Open Access Journals (Sweden)

E. A. Eremeeva

2017-01-01

Full Text Available Subject of Research. This work describes for the first time the formation of antireflective coating on the base of boehmite phase of AlOOH with low refractive index (1.35 by inkjet printing on the nonporous substrate. This method gives the possibility to increase the contrast of colorful interfering images by 32% obtaining by inkjet printing of titanium dioxide sol. The usage of this technology enables to obtain patterns with wide viewing angle and makes them highly stable. Methods. Traditional sol-gel method with peptizing agents and heating for 90oC was applied for sol synthesis. Then the mixture was under sonic treatment for the obtaining of viscous sol. The viscosity was determined by Brookfield HA/HB viscometer, and the surface tension by Kyowa DY-700 tensiometer. Aluminum oxide ink was deposited on polished slides (26×76 mm2, Paul Marienfeld, Germany, over titanium oxide layer. To print titania ink, we use a desktop office printer Canon Pixma IP 2840 and Dimatix DMP-2831. The thickness of an inkjet AlOOH layer after drying in the air and removal of the solvents did not exceed 150 nm with an RI not less than 1.35 in the entire visible range. Results. The stable colloidal ink was obtained for the first time on the base of aluminum oxide matrix with neutral pH. The rheology was regulated by controlling parameters of sol-gel method in the system of aqueous titanium dioxide sol and by adding ethanol that affects the charge of double electrical layer of disperse phase. The controllable coalesce of drops enables to apply antireflection coating within the thickness accuracy of 10 nm. The morphology of particles and the topology of printed structures were analyzed by optical, scanning electron and atomic-force microscopes. Practical Relevance. We have proposed the approach to obtain colorful, interference patterns using two types of high refractive inks with different refractive indexes. The inkjet printing method opens new opportunities for
Diffusive heat transport across magnetic islands and stochastic layers in tokamaks

International Nuclear Information System (INIS)

Hoelzl, Matthias

2010-01-01

Heat transport in tokamak plasmas with magnetic islands and ergodic field lines was simulated at realistic plasma parameters in realistic tokamak geometries. This requires the treatment of anisotropic heat diffusion, which is more efficient along magnetic field lines by up to ten orders of magnitude than perpendicular to them. Comparisons with analytical predictions and experimental measurements allow to determine the stability properties of neoclassical tearing modes as well as the experimental heat diffusion anisotropy.
Heat, mass, and momentum transport model for hydrogen diffusion flames in nuclear reactor containments

International Nuclear Information System (INIS)

Travis, J.R.

1985-01-01

It is now possible to analyze the time-dependent, fully three-dimensional behavior of hydrogen diffusion flames in nuclear reactor containments. This analysis involves coupling the full Navier-Stokes equations with multi-species transport to the global chemical kinetics of hydrogen combustion. A transport equation for the subgrid scale turbulent kinetic energy density is solved to produce the time and space dependent turbulent transport coefficients. The heat transfer coefficient governing the exchange of heat between fluid computational cells adjacent to wall cells is calculated by a modified Reynolds analogy formulation. The analysis of a MARK-III containment indicates very complex flow patterns that greatly influence fluid and wall temperatures and heat fluxes. 18 refs., 24 figs
Energy selecting action of limiters on particle fluxes penetrating into the SOL-plasma

International Nuclear Information System (INIS)

Hildebrandt, D.

1986-01-01

A single model of the penetration of particle effluxes from the core plasma into the SOL-plasma of tokamaks is proposed. The assumptions made are free streaming of particles parallel to the magnetic field and anomalous particle transport perpendicular to the toroidal field with a constant radial velocity. The model has been proved for measured particle fluxes of Li which was injected into the core plasma of the tokamak T-10. The dependence of the Li-particle flux on the minor radius as well as toroidal asymmetries in the SOL-plasma can be explained by the results of the calculations. (author)

Three dimensional heat transport modeling in Vossoroca reservoir

Science.gov (United States)

Arcie Polli, Bruna; Yoshioka Bernardo, Julio Werner; Hilgert, Stephan; Bleninger, Tobias

2017-04-01

Freshwater reservoirs are used for many purposes as hydropower generation, water supply and irrigation. In Brazil, according to the National Energy Balance of 2013, hydropower energy corresponds to 70.1% of the Brazilian demand. Superficial waters (which include rivers, lakes and reservoirs) are the most used source for drinking water supply - 56% of the municipalities use superficial waters as a source of water. The last two years have shown that the Brazilian water and electricity supply is highly vulnerable and that improved management is urgently needed. The construction of reservoirs affects physical, chemical and biological characteristics of the water body, e.g. stratification, temperature, residence time and turbulence reduction. Some water quality issues related to reservoirs are eutrophication, greenhouse gas emission to the atmosphere and dissolved oxygen depletion in the hypolimnion. The understanding of the physical processes in the water body is fundamental to reservoir management. Lakes and reservoirs may present a seasonal behavior and stratify due to hydrological and meteorological conditions, and especially its vertical distribution may be related to water quality. Stratification can control heat and dissolved substances transport. It has been also reported the importance of horizontal temperature gradients, e.g. inflows and its density and processes of mass transfer from shallow to deeper regions of the reservoir, that also may impact water quality. Three dimensional modeling of the heat transport in lakes and reservoirs is an important tool to the understanding and management of these systems. It is possible to estimate periods of large vertical temperature gradients, inhibiting vertical transport and horizontal gradients, which could be responsible for horizontal transport of heat and substances (e.g. differential cooling or inflows). Vossoroca reservoir was constructed in 1949 by the impoundment of São João River and is located near to
Cross-field blob transport in tokamak scrape-off-layer plasmas

International Nuclear Information System (INIS)

D'Ippolito, D.A.; Myra, J.R.; Krasheninnikov, S.I.

2002-01-01

Recent measurements show that nondiffusive, intermittent transport of particles can play a major role in the scrape-off-layer (SOL) of fusion experiments. A possible mechanism for fast convective plasma transport is related to the plasma filaments or 'blobs' observed in the SOL with fast cameras and probes. In this paper, physical arguments suggesting the importance of blob transport [S. I. Krasheninnikov, Phys. Lett. A 283, 368 (2001)] have been extended by calculations using a three-field fluid model, treating the blobs as coherent propagating structures. The properties of density, temperature and vorticity blobs, and methods of averaging over ensembles of blobs to get the average SOL profiles, are illustrated. The role of ionization of background neutrals in sustaining the density blob transport is also discussed. Many qualitative features of the experiments, such as relatively flat density profiles and transport coefficients increasing toward the wall, are shown to emerge naturally from the blob transport paradigm
Hybrid sol-gel optical materials

Science.gov (United States)

Zeigler, John M.

1992-01-01

Hybrid sol-gel materials comprise silicate sols cross-linked with linear polysilane, polygermane, or poly(silane-germane). The sol-gel materials are useful as optical identifiers in tagging and verification applications and, in a different aspect, as stable, visible light transparent non-linear optical materials. Methyl or phenyl silicones, polyaryl sulfides, polyaryl ethers, and rubbery polysilanes may be used in addition to the linear polysilane. The linear polymers cross-link with the sol to form a matrix having high optical transparency, resistance to thermooxidative aging, adherence to a variety of substrates, brittleness, and a resistance to cracking during thermal cycling.
Momentum, heat, and mass transfer analogy for vertical hydraulic transport of inert particles

Directory of Open Access Journals (Sweden)

Jaćimovski Darko R.

2014-01-01

Full Text Available Wall-to-bed momentum, heat and mass transfer in vertical liquid-solids flow, as well as in single phase flow, were studied. The aim of this investigation was to establish the analogy among those phenomena. Also, effect of particles concentration on momentum, heat and mass transfer was studied. The experiments in hydraulic transport were performed in a 25.4 mm I.D. cooper tube equipped with a steam jacket, using spherical glass particles of 1.94 mm in diameter and water as a transport fluid. The segment of the transport tube used for mass transfer measurements was inside coated with benzoic acid. In the hydraulic transport two characteristic flow regimes were observed: turbulent and parallel particle flow regime. The transition between two characteristic regimes (γ*=0, occurs at a critical voidage ε≈0.85. The vertical two-phase flow was considered as the pseudofluid, and modified mixture-wall friction coefficient (fw and modified mixture Reynolds number (Rem were introduced for explanation of this system. Experimental data show that the wall-to-bed momentum, heat and mass transfer coefficients, in vertical flow of pseudofluid, for the turbulent regime are significantly higher than in parallel regime. Wall-to-bed, mass and heat transfer coefficients in hydraulic transport of particles were much higher then in single-phase flow for lower Reynolds numbers (Re15000, there was not significant difference. The experimental data for wall-to-bed momentum, heat and mass transfer in vertical flow of pseudofluid in parallel particle flow regime, show existing analogy among these three phenomena. [Projekat Ministarstva nauke Republike Srbije, br. 172022
Heat Transport in Graphene Ferromagnet-Insulator-Superconductor Junctions

Institute of Scientific and Technical Information of China (English)

LI Xiao-Wei

2011-01-01

We study heat transport in a graphene ferromagnet-insulator-superconducting junction. It is found that the thermal conductance of the graphene ferromagnet-insulator-superconductor (FIS) junction is an oscillatory function of the barrier strength x in the thin-barrier limit. The gate potential U0 decreases the amplitude of thermal conductance oscillation. Both the amplitude and phase of the thermal conductance oscillation varies with the exchange energy Eh. The thermal conductance of a graphene FIS junction displays the usual exponential dependence on temperature, reflecting the s-wave symmetry of superconducting graphene.%@@ We study heat transport in a graphene ferromagnet-insulator-superconducting junction.It is found that the thermal conductance of the graphene ferromagnet-insulator-superconductor(FIS)junction is an oscillatory function of the barrier strength X in the thin-barrier limit.The gate potential Uo decreases the amplitude of thermal conductance oscillation.Both the amplitude and phase of the thermal conductance oscillation varies with the exchange energy Eh.The thermal conductance of a graphene FIS junction displays the usual exponential dependence on temperature, reflecting the s-wave symmetry of superconducting graphene.
Poloidal profiles and transport during turbulent heating

International Nuclear Information System (INIS)

Mascheroni, P.L.

1977-01-01

The current penetration stage of a turbulently heated tokamak is modeled. The basic formulae are written in slab geometry since the dominant anomalous transport has a characteristic frequency much larger than the bounce frequency. Thus, the basic framework is provided by the Maxwell and fluid equations, with classical and anomalous transport. Quasi-neutrality is used. It is shown that the anomalous collision frequency dominates the anomalous viscosity and thermal conductivity, and that the convective wave transport can be neglected. For these numerical estimates, the leading term in the quasi-linear series is used. During the current penetration stage the distribution function for the particles will depart from a single Maxwellian type. Hence, the first objective was to numerically compare calculated poloidal magnetic field profiles with measured, published poloidal profiles. The poloidal magnetic field has been calculated using a code which handles the anomalous collision frequency self-consistently. The agreement is good, and it is concluded that the current penetration stage can be satisfactorily described by this model
Mobile heat storage containers and their transport by rail or road

Energy Technology Data Exchange (ETDEWEB)

Goldenberg, Philipp

2013-10-15

Mobile heat storage containers are capable of making a contribution to the meaningful use of energy which is needed for use at a location other than where it originates. The study presented in this report outlines the technology of mobile heat storage and analyses an example of its transport by rail or road. (orig.)
Process for the transport of heat energy released by a nuclear reactor

International Nuclear Information System (INIS)

Nuernberg, H.W.; Wolff, G.

1978-01-01

The heat produced in a nuclear reactor is converted into latent chemical binding energy. The heat can be released again below 400 0 C by recombination after transport by decomposition of ethane or propane into ethylene or propylene and hydrogen. (TK) [de
The Improvement of Foam Concrete Geoecoprotective Properties in Transport Construction

Science.gov (United States)

Svatovskaya, Larisa; Kabanov, Alexander; Sychov, Maxim

2017-10-01

The article analyses 2 kinds of properties of silica sol foam concrete: technical and geoecoprotective ones. Foam concrete stabilized with silica sol foam has lower heat conductivity resulting in fuel saving. Foam concrete obtained according to sol absorption technology has lower water absorption and is good enough for blocking to prevent the environment pollution. Pollution blocking can be achieved by two methods. The first method is saturation of an article affected by oil products with silica sol. The second method is to create a special preventive protection using silica sol screen. The article shows geoecoprotective properties of protein foam soil systems.
Studies of heat transport to forced-flow He II

International Nuclear Information System (INIS)

Dresner, L.; Kashani, A.; Van Sciver, S.W.

1985-01-01

Analytical and experimental studies of heat transport to forced-flow He II are reported. The work is pertinent to the transfer of He II in space. An analytical model has been developed that establishes a condition for two-phase flow to occur in the transfer line. This condition sets an allowable limit to the heat leak into the transfer line. Experimental measurements of pressure drop and flow meter performances indicate that turbulent He II can be analyzed in terms of classical pressure drop correlations
Required momentum, heat, and mass transport experiments for liquid-metal blankets

International Nuclear Information System (INIS)

Tillack, M.S.; Sze, D.K.; Abdou, M.A.

1986-01-01

Through the effects on fluid flow, many aspects of blanket behavior are affected by magnetohydrodynamic (MHD) effects, including pressure drop, heat transfer, mass transfer, and structural behavior. In this paper, a set of experiments is examined that could be performed in order to reduce the uncertainties in the highly related set of issues dealing with momentum, heat, and mass transport under the influence of a strong magnetic field (i.e., magnetic transport phenomena). By improving our basic understanding and by providing direct experimental data on blanket behavior, these experiments will lead to improved designs and an accurate assessment of the attractiveness of liquid-metal blankets
Thermal stability of a modified sol-gel derived hydroxyapatite nanopowders

Science.gov (United States)

Herradi, S.; El Bali, B.; Khaldi, M.; Lachkar, M.

2017-03-01

Hydroxyapatite Ca10(PO4)6(OH)2 (HA) powder was successfully synthesized by a modified sol-gel method using a solution of calcium nitrate in ethanol, along with a solution of diammonium hydrogen phosphate in water and NH4OH as starting materials. The Ca/P molar ratio was maintained at 1.67. The powder was subjected to furnace and microwave heating to compare the decomposition of HA and study the crystallite sizes. It was found that microwave heated powders were pure HAP up to 230°C with absence of secondary phases. However, XRD patterns show that furnace heated powders convert completely to β-TCP when treated at 750°C and 1000°C. This result was confirmed by the absence of hydroxyl bands in the FT-IR spectra for these temperatures.
Heat transport in the quasi-single-helicity islands of EXTRAP T2R

Science.gov (United States)

Frassinetti, L.; Brunsell, P. R.; Drake, J.

2009-03-01

The heat transport inside the magnetic island generated in a quasi-single-helicity regime of a reversed-field pinch device is studied by using a numerical code that simulates the electron temperature and the soft x-ray emissivity. The heat diffusivity χe inside the island is determined by matching the simulated signals with the experimental ones. Inside the island, χe turns out to be from one to two orders of magnitude lower than the diffusivity in the surrounding plasma, where the magnetic field is stochastic. Furthermore, the heat transport properties inside the island are studied in correlation with the plasma current and with the amplitude of the magnetic fluctuations.
Characteristics of nonlocally-coupled transition of the heat transport in LHD

International Nuclear Information System (INIS)

Tamura, N.; Ida, K.; Tanaka, K.; Tokuzawa, T.; Itoh, K.; Shimozuma, T.; Kubo, S.; Tsuchiya, H.; Nagayama, Y.; Kawahata, K.; Sudo, S.; Yamada, H.; Inagaki, S.

2010-01-01

A comparison of characteristics between a nonlocal transport phenomenon and an electron internal transport barrier (ITB) in the Large Helical Device is performed with a transient transport analysis and from the viewpoint of a dynamic behavior of transport state. The electron ITB is characterized by a jump of electron temperature gradient. In contrast, the transient transport analysis indicates the nonlocal transport phenomenon is characterized by a jump of electron heat flux. And seen from the viewpoint of the dynamic behavior of transport state, the physical mechanism of the appearance of the nonlocal transport phenomenon is found to be qualitatively different from that of the formation of the electron ITB. (copyright 2010 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim) (orig.)
Effect of sol concentration on the properties of ZnO thin films prepared by sol-gel technique

International Nuclear Information System (INIS)

Dutta, M.; Mridha, S.; Basak, D.

2008-01-01

ZnO thin films are deposited on the glass substrates by sol-gel drain coating technique by varying the concentration of the sol. X-ray diffraction (XRD) and scanning electron microscopy (SEM) analysis were used to investigate the effect of sol concentration on the crystallinity and surface morphology of the films. The results show that with increase in sol concentration, the value of full width at half maximum (FWHM) of (0 0 2) peak decreases while the strain first increases and then decreases. The sol with higher concentration results in the increase in the grain size. The studies on the optical properties show that the band gap value increases from 3.27 to 3.3 eV when the sol concentration changes from 0.03 to 0.1 M. The photoconductivity studies reveal that the film for 0.05 M sol shows the maximum photoresponse for ultraviolet (UV) wavelength (<400 nm) which is co-related with the deep-level defects. The growth and decay of the photocurrent is found to be slowest for the same film
Monju secondary heat transport system sodium leak

International Nuclear Information System (INIS)

Suzuki, Takeo; Hiroi, Hiroshi; Usami, Shin; Iwata, Koji.

1996-01-01

On December 8, 1995, the sodium leakage from the secondary heat transport system (SHTS) occurred in the piping room of the reactor auxiliary building in Monju. The secondary sodium leaked through a temperature sensor, due to the breakaway of the tip of the well tube of the sensor installed near the outlet of the intermediate heat exchanger (IHX) in the C loop of SHTS. The reactor core remained cooled and thus, from the viewpoint of radiological hazards, the safety of the reactor was secured. There were no adverse effects for operating personnel or the surrounding environment. The cause of the well tube failure is considered to result from high cycle fatigue due to flow induced vibrations. Delay in draining the sodium from the leaking loop increased the consequential effects from sodium combustion products. (author)
EFFECT OF SANDSTONE ANISOTROPY ON ITS HEAT AND MOISTURE TRANSPORT PROPERTIES

Directory of Open Access Journals (Sweden)

Jan Fořt

2015-09-01

Full Text Available Each type of natural stone has its own geological history, formation conditions, different chemical and mineralogical composition, which influence its possible anisotropy. Knowledge in the natural stones anisotropy represents crucial information for the process of stone quarrying, its correct usage and arrangement in building applications. Because of anisotropy, many natural stones exhibit different heat and moisture transport properties in various directions. The main goal of this study is to analyse several anisotropy indices and their effect on heat transport and capillary absorption. For the experimental determination of the anisotropy effect, five types of sandstone coming from different operating quarries in the Czech Republic are chosen. These materials are often used for restoration of culture heritage monuments as well as for other building applications where they are used as facing slabs, facade panels, decoration stones, paving, etc. For basic characterization of studied materials, determination of their bulk density, matrix density and total open porosity is done. Chemical composition of particular sandstones is analysed by X-Ray Fluorescence. Anisotropy is examined by the non-destructive measurement of velocity of ultrasonic wave propagation. On the basis of ultrasound testing data, the relative anisotropy, total anisotropy and anisotropy coefficient are calculated. Then, the measurement of thermal conductivity and thermal diffusivity in various directions of samples orientation is carried out. The obtained results reveal significant differences between the parameters characterizing the heat transport in various directions, whereas these values are in accordance with the indices of anisotropy. Capillary water transport is described by water absorption coefficient measured using a sorption experiment, which is performed for distilled water and 1M NaCl water solution. The measured data confirm the effect of anisotropy which is
The heat and moisture transport properties of wet porous media

International Nuclear Information System (INIS)

Wang, B.X.; Fang, Z.H.; Yu, W.P.

1989-01-01

Existing methods for determining heat and moisture transport properties in porous media are briefly reviewed, and their merits and deficiencies are discussed. Emphasis is placed on research in developing new transient methods undertaken in China during the recent years. An attempt has been made to relate the coefficients in the heat and mass transfer equations with inherent properties of the liquid and matrix and then to predict these coefficients based on limited measurements
1D momentum-conserving systems: the conundrum of anomalous versus normal heat transport

International Nuclear Information System (INIS)

Li, Yunyun; Li, Nianbei; Hänggi, Peter; Li, Baowen; Liu, Sha

2015-01-01

Transport and the spread of heat in Hamiltonian one dimensional momentum conserving nonlinear systems is commonly thought to proceed anomalously. Notable exceptions, however, do exist of which the coupled rotator model is a prominent case. Therefore, the quest arises to identify the origin of manifest anomalous energy and momentum transport in those low dimensional systems. We develop the theory for both, the statistical densities for momentum- and energy-spread and particularly its momentum-/heat-diffusion behavior, as well as its corresponding momentum/heat transport features. We demonstrate that the second temporal derivative of the mean squared deviation of the momentum spread is proportional to the equilibrium correlation of the total momentum flux. Subtracting the part which corresponds to a ballistic momentum spread relates (via this integrated, subleading momentum flux correlation) to an effective viscosity, or equivalently, to the underlying momentum diffusivity. We next put forward the intriguing hypothesis: normal spread of this so adjusted excess momentum density causes normal energy spread and alike normal heat transport (Fourier Law). Its corollary being that an anomalous, superdiffusive broadening of this adjusted excess momentum density in turn implies an anomalous energy spread and correspondingly anomalous, superdiffusive heat transport. This hypothesis is successfully corroborated within extensive molecular dynamics simulations over large extended time scales. Our numerical validation of the hypothesis involves four distinct archetype classes of nonlinear pair-interaction potentials: (i) a globally bounded pair interaction (the noted coupled rotator model), (ii) unbounded interactions acting at large distances (the coupled rotator model amended with harmonic pair interactions), (iii) the case of a hard point gas with unbounded square-well interactions and (iv) a pair interaction potential being unbounded at short distances while displaying an
1D momentum-conserving systems: the conundrum of anomalous versus normal heat transport

Science.gov (United States)

Li, Yunyun; Liu, Sha; Li, Nianbei; Hänggi, Peter; Li, Baowen

2015-04-01

Transport and the spread of heat in Hamiltonian one dimensional momentum conserving nonlinear systems is commonly thought to proceed anomalously. Notable exceptions, however, do exist of which the coupled rotator model is a prominent case. Therefore, the quest arises to identify the origin of manifest anomalous energy and momentum transport in those low dimensional systems. We develop the theory for both, the statistical densities for momentum- and energy-spread and particularly its momentum-/heat-diffusion behavior, as well as its corresponding momentum/heat transport features. We demonstrate that the second temporal derivative of the mean squared deviation of the momentum spread is proportional to the equilibrium correlation of the total momentum flux. Subtracting the part which corresponds to a ballistic momentum spread relates (via this integrated, subleading momentum flux correlation) to an effective viscosity, or equivalently, to the underlying momentum diffusivity. We next put forward the intriguing hypothesis: normal spread of this so adjusted excess momentum density causes normal energy spread and alike normal heat transport (Fourier Law). Its corollary being that an anomalous, superdiffusive broadening of this adjusted excess momentum density in turn implies an anomalous energy spread and correspondingly anomalous, superdiffusive heat transport. This hypothesis is successfully corroborated within extensive molecular dynamics simulations over large extended time scales. Our numerical validation of the hypothesis involves four distinct archetype classes of nonlinear pair-interaction potentials: (i) a globally bounded pair interaction (the noted coupled rotator model), (ii) unbounded interactions acting at large distances (the coupled rotator model amended with harmonic pair interactions), (iii) the case of a hard point gas with unbounded square-well interactions and (iv) a pair interaction potential being unbounded at short distances while displaying an

Heat transport in the XXZ spin chain: from ballistic to diffusive regimes and dephasing enhancement

International Nuclear Information System (INIS)

Mendoza-Arenas, J J; Al-Assam, S; Clark, S R; Jaksch, D

2013-01-01

In this work we study the heat transport in an XXZ spin-1/2 Heisenberg chain with homogeneous magnetic field, incoherently driven out of equilibrium by reservoirs at the boundaries. We focus on the effect of bulk dephasing (energy-dissipative) processes in different parameter regimes of the system. The non-equilibrium steady state of the chain is obtained by simulating its evolution under the corresponding Lindblad master equation, using the time evolving block decimation method. In the absence of dephasing, the heat transport is ballistic for weak interactions, while being diffusive in the strongly interacting regime, as evidenced by the heat current scaling with the system size. When bulk dephasing takes place in the system, diffusive transport is induced in the weakly interacting regime, with the heat current monotonically decreasing with the dephasing rate. In contrast, in the strongly interacting regime, the heat current can be significantly enhanced by dephasing for systems of small size. (paper)
A practical nonlocal model for heat transport in magnetized laser plasmas

International Nuclear Information System (INIS)

Nicolaie, Ph.D.; Feugeas, J.-L.A.; Schurtz, G.P.

2006-01-01

A model of nonlocal transport for multidimensional radiation magnetohydrodynamics codes is presented. In laser produced plasmas, it is now believed that the heat transport can be strongly modified by the nonlocal nature of the electron conduction. Other mechanisms, such as self-generated magnetic fields, may also affect the heat transport. The model described in this work, based on simplified Fokker-Planck equations aims at extending the model of G. Schurtz, Ph. Nicolaie, and M. Busquet [Phys. Plasmas 7, 4238 (2000)] to magnetized plasmas. A complete system of nonlocal equations is derived from kinetic equations with self-consistent electric and magnetic fields. These equations are analyzed and simplified in order to be implemented into large laser fusion codes and coupled to other relevant physics. The model is applied to two laser configurations that demonstrate the main features of the model and point out the nonlocal Righi-Leduc effect in a multidimensional case
Controlling Heat Transport and Flow Structures in Thermal Turbulence Using Ratchet Surfaces

Science.gov (United States)

Jiang, Hechuan; Zhu, Xiaojue; Mathai, Varghese; Verzicco, Roberto; Lohse, Detlef; Sun, Chao

2018-01-01

In this combined experimental and numerical study on thermally driven turbulence in a rectangular cell, the global heat transport and the coherent flow structures are controlled with an asymmetric ratchetlike roughness on the top and bottom plates. We show that, by means of symmetry breaking due to the presence of the ratchet structures on the conducting plates, the orientation of the large scale circulation roll (LSCR) can be locked to a preferred direction even when the cell is perfectly leveled out. By introducing a small tilt to the system, we show that the LSCR orientation can be tuned and controlled. The two different orientations of LSCR give two quite different heat transport efficiencies, indicating that heat transport is sensitive to the LSCR direction over the asymmetric roughness structure. Through a quantitative analysis of the dynamics of thermal plume emissions and the orientation of the LSCR over the asymmetric structure, we provide a physical explanation for these findings. The current work has important implications for passive and active flow control in engineering, biofluid dynamics, and geophysical flows.
Heat transport modelling in EXTRAP T2R

Science.gov (United States)

Frassinetti, L.; Brunsell, P. R.; Cecconello, M.; Drake, J. R.

2009-02-01

A model to estimate the heat transport in the EXTRAP T2R reversed field pinch (RFP) is described. The model, based on experimental and theoretical results, divides the RFP electron heat diffusivity χe into three regions, one in the plasma core, where χe is assumed to be determined by the tearing modes, one located around the reversal radius, where χe is assumed not dependent on the magnetic fluctuations and one in the extreme edge, where high χe is assumed. The absolute values of the core and of the reversal χe are determined by simulating the electron temperature and the soft x-ray and by comparing the simulated signals with the experimental ones. The model is used to estimate the heat diffusivity and the energy confinement time during the flat top of standard plasmas, of deep F plasmas and of plasmas obtained with the intelligent shell.
Nanocrystal/sol-gel nanocomposites

Science.gov (United States)

Petruska, Melissa A [Los Alamos, NM; Klimov, Victor L [Los Alamos, NM

2007-06-05

The present invention is directed to solid composites including colloidal nanocrystals within a sol-gel host or matrix and to processes of forming such solid composites. The present invention is further directed to alcohol soluble colloidal nanocrystals useful in formation of sol-gel based solid composites.
Edge transport studies in the edge and scrape-off layer of the National Spherical Torus Experiment with Langmuir probes

Energy Technology Data Exchange (ETDEWEB)

Boedo, J. A., E-mail: jboedo@ucsd.edu; Rudakov, D. L. [University of California San Diego, 9500 Gilman Dr., La Jolla, California 92093 (United States); Myra, J. R.; D' Ippolito, D. A. [Lodestar Research Corp, 2400 Central Ave., Boulder, Colorado 80301 (United States); Zweben, S.; Maingi, R.; Maqueda, R. J.; Bell, R.; Kugel, H.; Leblanc, B.; Roquemore, L. A. [Princeton University, PO Box 451, Princeton, New Jersey 08543 (United States); Soukhanovskii, V. A. [Lawrence Livermore National Laboratory, Livermore, California 94550 (United States); Ahn, J. W.; Canik, J. [Oak Ridge National Laboratory, PO Box 2008, Oak Ridge, Tennessee 37830 (United States); Crocker, N. [University of California Los Angeles, PO Box 957099, Los Angeles, California 90095 (United States)

2014-04-15

Transport and turbulence profiles were directly evaluated using probes for the first time in the edge and scrape-off layer (SOL) of NSTX [Ono et al., Nucl. Fusion 40, 557 (2000)] in low (L) and high (H) confinement, low power (P{sub in}∼ 1.3 MW), beam-heated, lower single-null discharges. Radial turbulent particle fluxes peak near the last closed flux surface (LCFS) at ≈4×10{sup 21} s{sup −1} in L-mode and are suppressed to ≈0.2×10{sup 21} s{sup −1} in H mode (80%–90% lower) mostly due to a reduction in density fluctuation amplitude and of the phase between density and radial velocity fluctuations. The radial particle fluxes are consistent with particle inventory based on SOLPS fluid modeling. A strong intermittent component is identified. Hot, dense plasma filaments 4–10 cm in diameter, appear first ∼2 cm inside the LCFS at a rate of ∼1×10{sup 21} s{sup −1} and leave that region with radial speeds of ∼3–5 km/s, decaying as they travel through the SOL, while voids travel inward toward the core. Profiles of normalized fluctuations feature levels of 10% inside LCFS to ∼150% at the LCFS and SOL. Once properly normalized, the intermittency in NSTX falls in similar electrostatic instability regimes as seen in other devices. The L-H transition causes a drop in the intermittent filaments velocity, amplitude and number in the SOL, resulting in reduced outward transport away from the edge and a less dense SOL.
Preparation, microstructure and properties of yttrium aluminum garnet fibers prepared by sol-gel method

Energy Technology Data Exchange (ETDEWEB)

Li Chengshun [Key Laboratory for Liquid Structure and Heredity of Materials of Ministry of Education, Shandong University, Jinan 250061 (China); Zhang Yujun [Key Laboratory for Liquid Structure and Heredity of Materials of Ministry of Education, Shandong University, Jinan 250061 (China)], E-mail: yujunzhangcn@sdu.edu.cn; Gong Hongyu; Zhang Jingde; Nie Lifang [Key Laboratory for Liquid Structure and Heredity of Materials of Ministry of Education, Shandong University, Jinan 250061 (China)

2009-01-15

Yttrium aluminum garnet (YAG) fiber was prepared by sol-gel method using water as the solvent. The spinnable YAG sol was synthesized using Al powder, Y(CH{sub 3}COOH){sub 3}.4H{sub 2}O and HCl as precursors, polyethylene oxide as viscosity adjusting agent. Gel fibers with diameter of 5-10 {mu}m were prepared from the YAG sol by using centrifugal spinning technique. YAG crystalline fibers were obtained by drying gel fibers and heat-treating at selected temperature. TG/DTA analysis showed an exotherm at 906 deg. C attributed to formation of YAG phase and weight loss of 45% at 1000 deg. C. XRD and FT-IR analysis showed that phase-pure YAG can be formed at 900 deg. C, and no other intermediate was observed. The grain size of YAG fibers increased from 25 to 220 nm and tensile strength decreased rapidly from 970 to 380 MPa when the sintering temperature increased from 900 to 1550 deg. C.
Effects of sintering temperature on structural and electrical transport properties of zinc ferrites prepared by sol-gel route

International Nuclear Information System (INIS)

Anis-ur-Rehman, M.; Malik, M.A.; Ahmad, I.; Nasir, S.; Mubeen, M.; Abdullah, A.

2011-01-01

The effects of sintering temperature on the structural and electrical transport properties of nanocrystalline zinc ferrites are reported. The zinc ferrites were prepared by WOWS sol-gel synthesis route. The prepared sample was sintered at temperatures 500 deg. C, 700 deg. C and 900 deg. C respectively for 2 h. X-ray Diffraction (XRD) technique was used to describe the structural properties. The crystallite size, lattice parameters and porosity of samples were measured from the analysis of XRD data. The average crystallite size for each sample was measured using the Scherrer formula by considering the most intense (3 1 1) peak. The dielectric constant (e), dielectric loss tangent (tan theta ) and AC electrical conductivity of nanocrystalline Zn ferrites are investigated as a function of frequency and sintering temperature. All the electrical properties are explained in accordance with MaxwellWagner model and Koops phenomenological theory. (author)
Structural and optical properties of sol-gel deposited proton conducting Ta{sub 2}O{sub 5} films

Energy Technology Data Exchange (ETDEWEB)

Ozer, N.; Lampert, C.M.

1995-08-01

Proton conducting tantalum oxide films were deposited by spin coating using a sol-gel process. The coating solutions were prepared using Ta(OC{sub 2}H{sub 5}){sub 5} as a precursor. X-ray diffraction studies determined that the sol-gel films, heat treated at temperatures below 400 C, were amorphous. Films heat treated at higher temperatures were crystalline Ta{sub 2}O{sub 5}. The solar transmission values (T{sub s}) of tantala films on glass generally range from 0.8--0.9 depending on thickness. The refractive index and the extinction coefficient were evaluated from transmittance characteristics in the UV-VIS-NIR regions. The refractive index values calculated at 550 nm increased from 1.78 to 1.97 with increasing heat treatment from 150 to 450 C. The films heat treated at different temperatures showed low absorption with extinction coefficients of less than k=1x10{sup -3} in the visible range. Spectrophotometric and impedance spectroscopic investigations performed on Ta{sub 2}O{sub 5} films revealed that these films have protonic conductivity of 3.2x10{sup -6} S/cm. The films are suitable for proton conducting layers in electrochromic (EC) devices.
Turbulence induced radial transport of toroidal momentum in boundary plasma of EAST tokamak

International Nuclear Information System (INIS)

Zhao, N.; Yan, N.; Xu, G. S.; Wang, H. Q.; Wang, L.; Ding, S. Y.; Chen, R.; Chen, L.; Zhang, W.; Hu, G. H.; Shao, L. M.; Wang, Z. X.

2016-01-01

Turbulence induced toroidal momentum transport in boundary plasma is investigated in H-mode discharge using Langmuir-Mach probes on EAST. The Reynolds stress is found to drive an inward toroidal momentum transport, while the outflow of particles convects the toroidal momentum outwards in the edge plasma. The Reynolds stress driven momentum transport dominates over the passive momentum transport carried by particle flux, which potentially provides a momentum source for the edge plasma. The outflow of particles delivers a momentum flux into the scrape-off layer (SOL) region, contributing as a momentum source for the SOL flows. At the L-H transitions, the outward momentum transport suddenly decreases due to the suppression of edge turbulence and associated particle transport. The SOL flows start to decelerate as plasma entering into H-mode. The contributions from turbulent Reynolds stress and particle transport for the toroidal momentum transport are identified. These results shed lights on the understanding of edge plasma accelerating at L-H transitions.
Flexibility analysis of main primary heat transport system : Narora Atomic Power Project

International Nuclear Information System (INIS)

Rastogi, S.K.

1975-01-01

The paper presents flexibility analysis problem of main primary heat transport system and the approximate analysis that has been made to estimate the loads coming on major equipments. The primary heat transport system for Narora Atomic Power Project is adopting vertical steam generators and pumps equally divided on either side of the reactor with inter-connecting pipes and feeders. Since the system is mainly spring supported with movement of a few points in certain direction defined but no anchorage, it represents a good problem for flexibility analysis which can only be solved in one step by developing a good computer programme. (author)
A continuum self organized critically model of turbulent heat transport in tokamaks

Energy Technology Data Exchange (ETDEWEB)

Tangri, V; Das, A; Kaw, P; Singh, R [Institute for Plasma Research, Gandhinagar (India)

2003-09-01

Based on the now well known and experimentally observed critical gradient length (R/L{sub Te} = RT/{nabla}T) in tokamaks, we present a continuum one dimensional model for explaining self organized heat transport in tokamaks. Key parameters of this model include a novel hysteresis parameter which ensures that the switch of heat transport coefficient {chi} upwards and downwards takes place at two different values of R/L{sub Te}. Extensive numerical simulations of this model reproduce many features of present day tokamaks such as submarginal temperature profiles, intermittent transport events, 1/f scaling of the frequency spectra, propagating fronts, etc. This model utilises a minimal set of phenomenological parameters, which may be determined from experiments and/or simulations. Analytical and physical understanding of the observed features has also been attempted. (author)
Thermal behavior of La2O3/Nio composite prepared by sol-gel method

International Nuclear Information System (INIS)

Sakallioglu, M.

2005-01-01

The La 2 O 3 /NiO composite was prepared by sol-gel method by using transition metal oxides (La 2 O 3 /NiO). The variation of specific heat capacity Cp with temperature for La2O3/NiO composite was investigated by DSC. The heat capacity curve was taken with a heating rate of 20 degrees/min between 0-100 degrees. The variation of specific heat capacity was found by PKI Muse Standard Analysis Program. The thermal stability of the La 2 O 3 /NiO composite was investigated by thermogravimetric analysis (TG) in air atmosphere at a heating rate of 20 degrees/min. The weight loss of La 2 O 3 /NiO composite was determined by the variation of temperature
Heating and active control of profiles and transport by IBW in the HT-7 tokamak

International Nuclear Information System (INIS)

Zhao Yanping; Wan Baonian; Li Jiangang

2003-01-01

Significant progress on Ion Bernstein Wave (IBW) heating and control of profiles has been obtained in HT-7. Both on-axis and off-axis electron heating with global peaked and local steep electron pressure profiles were realized if the position of the resonant layer was selected to be plasma far from the plasma edge region. Reduction of electron heat transport has been observed from sawtooth heat pulse propagation. Improvement of both particle and energy confinement was slight in the on-axis and considerable in the off-axis heating cases. The improved confinement in off-axis heating mode may be due to the extension of the high performance plasma volume caused by IBW. These studies demonstrate that IBWs are potentially a tool for active control of plasma profiles and transport. (author)
A practical nonlocal model for heat transport in magnetized laser plasmas

Science.gov (United States)

Nicolaï, Ph. D.; Feugeas, J.-L. A.; Schurtz, G. P.

2006-03-01

A model of nonlocal transport for multidimensional radiation magnetohydrodynamics codes is presented. In laser produced plasmas, it is now believed that the heat transport can be strongly modified by the nonlocal nature of the electron conduction. Other mechanisms, such as self-generated magnetic fields, may also affect the heat transport. The model described in this work, based on simplified Fokker-Planck equations aims at extending the model of G. Schurtz, Ph. Nicolaï, and M. Busquet [Phys. Plasmas 7, 4238 (2000)] to magnetized plasmas. A complete system of nonlocal equations is derived from kinetic equations with self-consistent electric and magnetic fields. These equations are analyzed and simplified in order to be implemented into large laser fusion codes and coupled to other relevant physics. The model is applied to two laser configurations that demonstrate the main features of the model and point out the nonlocal Righi-Leduc effect in a multidimensional case.
Physics of tokamak scrape-off layer confinement

International Nuclear Information System (INIS)

Cohen, R.H.

1993-01-01

Confinement in the scrape-off layer (SOL) of a tokamak is believed to be governed by classical flows along magnetic field lines terminated by sheaths, and turbulent transport across field lines. In this paper we review how these two effects conspire to establish the width of the SOL, and survey recent and ongoing work on mechanisms for turbulence in SOL's. The beneficial relationship between scrape-off layer turbulence in mitigating the heat flux density on divertors is noted, and tactics for actively altering SOL confinement so as to reduce the heat flux density are discussed
Effect of sol-age on the surface and optical properties of sol-gel derived mesoporous zirconia thin films

Directory of Open Access Journals (Sweden)

Manish Kumar

2011-06-01

Full Text Available Mesoporous ZrO2 thin films have been deposited by a modified sol-gel dip coating technique using HCl as catalyst. Effects of sol-age on the surface and on the optical properties are studied. Transmission electron micrographs of the films reveal the pore dimensions in mesoporous regime. A strong correlation in surface topography with sol-age has been observed where increase in sol-age induces a systematic enhancement in the value of root mean square roughness of the films. Optical study shows that deposited films have high transmittance and an enhancement of 5.6 times in porosity in films prepared with sol-age of 10 days with respect to that of 1 day. Band gap estimation by Tauc's plots of films is observed to 5.74 eV, which shows invariance with the sol-age.
A concetration-dependent model for silver colloids in nanostructured sol-gel materials

Science.gov (United States)

Garcia-Macedo, Jorge A.; Franco, Alfredo; Renteria, Victor; Valverde-Aguilar, Guadalupe

2005-08-01

We report on the physical modelling of the photoconductive response of nanostructured sol-gel films in function of the silver nitrate concentration (ions and colloids). This model considers several factors as the silver nitrate concentration and the transport parameters obtained. The model is compared with others commonly used. 2d-hexagonal nanostructured sol-gel thin films were prepared by dip-coating method using a non-ionic diblock copolymer Brij58 (surfactant) to produce channels into the film. Silver colloids (metallic Ag0 nanoparticles ) were obtained by spontaneous reduction process of Ag+ ions to Ag0. These nanoparticles were deposited into the channels formed by the surfactant. The structure was identified by X-ray diffraction and TEM. An absorption band located at 430 nm was detected by optical absorption; it corresponds to the plasmon surface. Fit to this band with modified Gans theory is presented. Photoconductivity studies were performed on films with silver ions and films with silver colloids to characterized their mechanisms of charge transport in the darkness and under illumination at 420, 633 nm wavelengths. Transport parameters were calculated. The films with silver colloids exhibit a photovoltaic effect stronger than the films with silver ions. While, the last ones possesses a photoconductivity behaviour.
Heating and transport in TFTR D-T plasmas

International Nuclear Information System (INIS)

Zarnstorff, M.C.; Scott, S.D.

1994-01-01

The confinement and heating of supershot plasmas are significantly enhanced with tritium beam injection relative to deuterium injection in TFTR. The global energy confinement and local thermal transport are analyzed for deuterium and tritium fueled plasmas to quantify their dependence on the average mass of the hydrogenic ions. The radial profiles of the deuterium and tritium densities are determined from the DT fusion neutron emission profile
Sol-gel synthesis of hydroxyapatite; Sintese de hidroxiapatita via sol-gel

Energy Technology Data Exchange (ETDEWEB)

Zupanski, M.D.; Lucena, M.P.P.; Bergmann, C.P., E-mail: michelledunin@yahoo.com.b [Universidade Federal do Rio Grande do Sul (UFRGS), Porto Alegre, RS (Brazil)

2010-07-01

Hydroxyapatite (HAp) has been established as the calcium phosphate based compound with most applications in the biological field. Among the numerous techniques for synthesis of HAp, the sol-gel processing route affords great control over purity and formed phases using low processing temperatures. In addition, the sol-gel approach offers an option for homogeneous HAp coating on metal substrates, as well as the ability to generate nanocrystalline powders. In this work, the sol-gel synthesis of HAp was investigated employing triethyl phosphate and calcium nitrate tetrahydrate as phosphorous and calcium precursors, respectively. The aging effect on phase composition and powder morphology of the final product was studied in terms of temperature and aging time. The powders were studied by using X-ray diffraction, Fourier transform infrared spectroscopy, particle size distribution by laser diffraction and scanning electron microscopy. (author)

Heating and active control of profiles and transport by IBW in the HT-7 tokamak

International Nuclear Information System (INIS)

Zhao Yanping

2002-01-01

By a series of technical improvements and intensive RF boronization, significant progresses on the IBW heating and control of profiles and transport has been obtained since last IAEA meeting. Both on-axis and off-axis electron heating with global peaked and local steeped electron pressure profile was realized if the resonant layer is in plasma far from the edge region. Maximum increment of electron temperature was about 2 keV at power of 200 kW. The heating factor reached 9.4 eV x 10 13 cm -3 /kW. Reduction of local electron heat transport around resonant layer has been observed. Significant improvement of particle confinement by a factor of 2-4 with very peaked density profile was obtained if 5/2-deuterium resonant layer is located at the plasma edge. Global transport and edge poloidal velocity shear can been controlled by IBW. (author)
Mullite fibres preparation by aqueous sol-gel process and activation energy of mullitization

International Nuclear Information System (INIS)

Tan Hongbin; Ding Yaping; Yang Jianfeng

2010-01-01

Mullite fibres were prepared by sol-gel process using aluminum carboxylates (ACs) and silica sol. ACs was synthesized from dissolving aluminum powder in a mixture of formic acid and oxalic acid using aluminum chloride hexahydrate as catalyst. A molar ratio of 1:2:1 for aluminum, formic acid and oxalic acid was optimized to obtain clear solution and viscous ACs sol for fibres synthesis. Thermogravimetry-differential scanning calorimetry (TG-DSC), Fourier transform infrared (FTIR) spectroscopy, X-ray diffraction (XRD), and scanning electron microscopy (SEM) analysis were used to characterize the properties of the gel and ceramic fibres. The gel fibres completely transformed to mullite at 1200 o C, with a smooth surface and uniform diameter. The activation energy for mullite formation in precursor gel fibres was determined by means of differential thermal analysis. The value obtained, E a = 741.4 kJ/mol, was lower than most data reported in the literatures, which was attributed to the silica-alumina micro-phase separation when organic acids decomposed during gel fibres heating.
Thermal performance and heat transport in aquifer thermal energy storage

Science.gov (United States)

Sommer, W. T.; Doornenbal, P. J.; Drijver, B. C.; van Gaans, P. F. M.; Leusbrock, I.; Grotenhuis, J. T. C.; Rijnaarts, H. H. M.

2014-01-01

Aquifer thermal energy storage (ATES) is used for seasonal storage of large quantities of thermal energy. Due to the increasing demand for sustainable energy, the number of ATES systems has increased rapidly, which has raised questions on the effect of ATES systems on their surroundings as well as their thermal performance. Furthermore, the increasing density of systems generates concern regarding thermal interference between the wells of one system and between neighboring systems. An assessment is made of (1) the thermal storage performance, and (2) the heat transport around the wells of an existing ATES system in the Netherlands. Reconstruction of flow rates and injection and extraction temperatures from hourly logs of operational data from 2005 to 2012 show that the average thermal recovery is 82 % for cold storage and 68 % for heat storage. Subsurface heat transport is monitored using distributed temperature sensing. Although the measurements reveal unequal distribution of flow rate over different parts of the well screen and preferential flow due to aquifer heterogeneity, sufficient well spacing has avoided thermal interference. However, oversizing of well spacing may limit the number of systems that can be realized in an area and lower the potential of ATES.
A simulation of heat transfer during billet transport

Energy Technology Data Exchange (ETDEWEB)

Jaklic, A.; Glogovac, B. [Institute of Metals and Technology, Ljubljana (Slovenia); Kolenko, T. [University of Ljubljana (Slovenia). Faculty of Natural Science and Technology; Zupancic, B. [University of Ljubljana (Slovenia). Faculty of Electrical Engineering; Zak, B. T. [Terming d.o.o., Ljubljana (Slovenia)

2002-07-01

This paper presents a simulation model for billet cooling during the billet's transport from the reheating furnace to the rolling mill. During the transport, the billet is exposed to radiation, convection and conduction. Due to the rectangular shape of the billet, the three-dimensional finite-difference model could be applied to calculate the heat conduction inside the billet. The billets are reheated in a gas-fired walking-beam furnace and are exposed to scaling. The model takes into account the effect of the thin oxide scale. We proved that the scale significantly affects the temperature distribution in the billet and should not be neglected. The model was verified by using a thermal camera. (author)
Comparison of transient electron heat transport in LHD helical and JT-60U tokamak plasmas

International Nuclear Information System (INIS)

Inagaki, S.; Ida, K.; Tamura, N.; Shimozuma, T.; Kubo, S.; Nagayama, Y.; Kawahata, K.; Sudo, S.; Ohkubo, K.; Takenaga, H.; Isayama, A.; Takizuka, T.; Kamada, Y.; Miura, Y.

2005-01-01

Transient transport experiments are performed in plasmas with and without Internal Transport Barrier (ITB) on LHD and JT-60U. The dependence of χ e on electron temperature, T e , and electron temperature gradient, ∇T e , is analyzed by an empirical non-linear heat transport model. In plasmas without ITB, two different types of non-linearity of the electron heat transport are observed from cold/heat pulse propagation. The χ e depends on T e and ∇T e in JT-60U, while the ∇T e dependence is weak in LHD. Inside the ITB region, there is no or weak ∇T e dependence both in LHD and JT-60U. A cold pulse growing driven by the negative T e dependence of χ e is observed inside the ITB region (LHD) and near the boundary of the ITB region (JT-60U). (author)
The influence of meridional ice transport on Europa's ocean stratification and heat content

Science.gov (United States)

Zhu, P.; Manucharyan, G.; Thompson, A. F.; Goodman, J. C.; Vance, S.

2017-12-01

Jupiter's moon Europa likely hosts a saltwater ocean beneath its icy surface. Geothermal heating and rotating convection in the ocean may drive a global overturning circulation that redistributes heat vertically and meridionally, preferentially warming the ice shell at the equator. Here we assess thepreviously unconstrained influence of ocean-ice coupling on Europa's ocean stratification and heat transport. We demonstrate that a relatively fresh layer can form at the ice-ocean interface due to a meridional ice transport forced by the differential ice shell heating between the equator and the poles. We provide analytical and numerical solutions for the layer's characteristics, highlighting their sensitivity to critical ocean parameters. For a weakly turbulent and highly saline ocean, a strong buoyancy gradient at the base of the freshwater layer can suppress vertical tracer exchange with the deeper ocean. As a result, the freshwater layer permits relatively warm deep ocean temperatures.
Impact of an integrated core/SOL description on the R and B T optimization of tokamak fusion reactors

Science.gov (United States)

Siccinio, M.; Fable, E.; Angioni, C.; Saarelma, S.; Scarabosio, A.; Zohm, H.

2018-01-01

An updated and improved version of the 0D divertor and scrape-off layer (SOL) model published in Siccinio et al (2016 Plasma Phys. Control. Fusion 58 125011) was coupled with the 1.5D transport code ASTRA (Pereverzev 1991 IPP Report 5/42, Pereverzev and Yushmanov 2002 IPP Report 5/98 and Fable et al 2013 Plasma Phys. Control. Fusion 55 124028). The resulting numerical tool was employed for various scans in the major radius R and in the toroidal magnetic field B T—for different safety factors q, allowable loop voltages V loop and H factors—in order to identify the most convenient choices for an electricity producing tokamak. Such a scenario analysis was carried out evaluating self-consistently, and simultaneously, the core profile and transport effects, which significantly impact on the fusion power outcome, and the divertor heat loads, which represent one of the most critical issues in view of the realization of fusion power plants (Zohm et al 2013 Nucl. Fusion 53 073019 and Wenninger et al 2017 Nucl. Fusion 57 046002). The main result is that, when divertor limits are enforced, the curves at constant electrical power output are closed on themselves in the R-BT plane, and a maximum achievable power exists—i.e. no benefits would be obtained from a further increase in R and B T once the optimum is reached. This result appears as an intrinsic physical limit for all those devices where a radiative SOL is needed to deal with the power exhaust, and where a lower limit on the power crossing the separatrix (e.g. because of the L-H transition) is present.
Controlling heat transport and flow structures in thermal turbulence using ratchet surfaces

Science.gov (United States)

Sun, Chao; Jiang, Hechuan; Zhu, Xiaojue; Mathai, Varghese; Verzicco, Roberto; Lohse, Detlef

2017-11-01

In this combined experimental and numerical study on thermally driven turbulence in a rectangular cell, the global heat transport and the coherent flow structures are controlled with an asymmetric ratchet-like roughness on the top and bottom plates. We show that, by means of symmetry breaking due to the presence of the ratchet structures on the conducting plates, the orientation of the Large Scale Circulation Roll (LSCR) can be locked to a preferred direction even when the cell is perfectly leveled out. By introducing a small tilt to the system, we show that the LSCR orientation can be tuned and controlled. The two different orientations of LSCR give two quite different heat transport efficiencies, indicating that heat transport is sensitive to the LSCR direction over the asymmetric roughness structure. Through analysis of the dynamics of thermal plume emissions and the orientation of the LSCR over the asymmetric structure, we provide a physical explanation for these findings. This work is financially supported by the Natural Science Foundation of China under Grant No. 11672156, the Dutch Foundation for Fundamental Research on Matter (FOM), the Dutch Technology Foundation (STW) and a VIDI Grant.
Heat transport as torsional responses and Keldysh formalism in a curved spacetime

OpenAIRE

Shitade, Atsuo

2013-01-01

We revisit a theory of heat transport in the light of a gauge theory of gravity and find the proper heat current with a corresponding gauge field, which yields the natural definitions of the heat magnetization and the Kubo-formula contribution to the thermal conductivity as torsional responses. We also develop a general framework for calculating gravitational responses by combining the Keldysh and Cartan formalisms. By using this framework, we explicitly calculate these two quantities and rep...
Correlation of the oxidation state of cerium in sol-gel glasses as a function of thermal treatment via optical spectroscopy and XANES studies.

Science.gov (United States)

Assefa, Zerihun; Haire, R G; Caulder, D L; Shuh, D K

2004-07-01

Sol-gel glass matrices containing lanthanides have numerous technological applications and their formation involves several chemical facets. In the case of cerium, its ability to exist in two different oxidation states or in mixed valence state provides additional complexities for the sol-gel process. The oxidation state of cerium present during different facets of preparation of sol-gel glasses, and also as a function of the starting oxidation state of cerium added, were studied both by optical spectroscopy and X-ray absorption near-edge structures (XANES). The findings acquired by each approach were compared. The primary focus was on the redox chemistries associated with sample preparation, gelation, and thermal treatment. When Ce3+ is introduced into the starting sols, the trivalent state normally prevails in the wet and room temperature-dried gels. Heating in air at >100 degrees C can generate a light yellow coloration with partial oxidation to the tetravalent state. Above 200 degrees C and up to approximately 1000 degrees C, cerium is oxidized to its tetravalent state. In contrast, when tetravalent cerium is introduced into the sol, both the wet and room temperature-dried gels lose the yellow-brown color of the initial ceric ammonium nitrate solution. When the sol-gel is heated to 110 degrees C it turns yellowish as the cerium tends to be re-oxidized. The yellow color is believed to represent the effect of oxidation and oligomerization of the cerium-silanol units in the matrix. The luminescence properties are also affected by these changes, the details of which are reported herein.
Design considerations for CRBRP heat transport system piping operating at elevated temperatures

International Nuclear Information System (INIS)

Pollono, L.P.; Mello, R.M.

1979-01-01

The heat transport system sodium piping for the Clinch River Breeder Reactor Plant (CRBRP) within the reactor containment building must withstand high temperatures for long periods of time. Each phase of the mechanical design process of the piping system is influenced by elevated temperature considerations which include material thermal creep effects, ratchetting caused by rapid temperature transients and stress relaxation, and material degradation effects. The structural design philosophy taken to design the CRBRP piping operating in a high temperature environment is described. The resulting design of the heat transport system piping is presented along with a discussion of special features that resulted from the elevated temperature considerations
Sol-gel bonding of silicon wafers

International Nuclear Information System (INIS)

Barbe, C.J.; Cassidy, D.J.; Triani, G.; Latella, B.A.; Mitchell, D.R.G.; Finnie, K.S.; Short, K.; Bartlett, J.R.; Woolfrey, J.L.; Collins, G.A.

2005-01-01

Sol-gel bonds have been produced between smooth, clean silicon substrates by spin-coating solutions containing partially hydrolysed silicon alkoxides. The two coated substrates were assembled and the resulting sandwich fired at temperatures ranging from 60 to 600 deg. C. The sol-gel coatings were characterised using attenuated total reflectance Fourier transform infrared spectroscopy, ellipsometry, and atomic force microscopy, while the corresponding bonded specimens were investigated using scanning electron microscopy and cross-sectional transmission electron microscopy. Mechanical properties were characterised using both microindentation and tensile testing. Bonding of silicon wafers has been successfully achieved at temperatures as low as 60 deg. C. At 300 deg. C, the interfacial fracture energy was 1.55 J/m 2 . At 600 deg. C, sol-gel bonding provided superior interfacial fracture energy over classical hydrophilic bonding (3.4 J/m 2 vs. 1.5 J/m 2 ). The increase in the interfacial fracture energy is related to the increase in film density due to the sintering of the sol-gel interface with increasing temperature. The superior interfacial fracture energy obtained by sol-gel bonding at low temperature is due to the formation of an interfacial layer, which chemically bonds the two sol-gel coatings on each wafer. Application of a tensile stress on the resulting bond leads to fracture of the samples at the silicon/sol-gel interface
Study of heat flux deposition in the Tore Supra Tokamak

International Nuclear Information System (INIS)

Carpentier, S.

2009-02-01

Accurate measurements of heat loads on internal tokamak components is essential for protection of the device during steady state operation. The optimisation of experimental scenarios also requires an in depth understanding of the physical mechanisms governing the heat flux deposition on the walls. The objective of this study is a detailed characterisation of the heat flux to plasma facing components (PFC) of the Tore Supra tokamak. The power deposited onto Tore Supra PFCs is calculated using an inverse method, which is applied to both the temperature maps measured by infrared thermography and to the enthalpy signals from calorimetry. The derived experimental heat flux maps calculated on the toroidal pumped limiter (TPL) are then compared with theoretical heat flux density distributions from a standard SOL-model. They are two experimental observations that are not consistent with the model: significant heat flux outside the theoretical wetted area, and heat load peaking close to the tangency point between the TPL and the last closed field surface (LCFS). An experimental analysis for several discharges with variable security factors q is made. In the area consistent with the theoretical predictions, this parametric study shows a clear dependence between the heat flux length λ q (estimated in the SOL (scrape-off layer) from the IR measurements) and the magnetic configuration. We observe that the spreading of heat fluxes on the component is compensated by a reduction of the power decay length λ q in the SOL when q decreases. On the other hand, in the area where the derived experimental heat loads are not consistent with the theoretical predictions, we observe that the spreading of heat fluxes outside the theoretical boundary increases when q decreases, and is thus not counterbalanced. (author)
Ductile fracture behaviour of primary heat transport piping material ...

Indian Academy of Sciences (India)

R. Narasimhan (Krishtel eMaging) 1461 1996 Oct 15 13:05:22

Abstract. Design of primary heat transport (PHT) piping of pressurised heavy water reactors (PHWR) has to ensure implementation of leak-before-break con- cepts. In order to be able to do so, the ductile fracture characteristics of PHT piping material have to be quantified. In this paper, the fracture resistance of SA333, Grade.
Sol-gel processing to form doped sol-gel monoliths inside hollow core optical fiber and sol-gel core fiber devices made thereby

Science.gov (United States)

Shaw, Harry C. (Inventor); Ott, Melanie N. (Inventor); Manuel, Michele V. (Inventor)

2002-01-01

A process of fabricating a fiber device includes providing a hollow core fiber, and forming a sol-gel material inside the hollow core fiber. The hollow core fiber is preferably an optical fiber, and the sol-gel material is doped with a dopant. Devices made in this manner includes a wide variety of sensors.
Density dependence of SOL power width in ASDEX upgrade L-Mode

Directory of Open Access Journals (Sweden)

B. Sieglin

2017-08-01

A recent study [4] with an open divertor configuration found an asymmetry of the power fall-off length between inner and outer target with a smaller power fall-off length λq,i on the inner divertor target. Measurements with a closed divertor configuration find a similar asymmetry for low recycling divertor conditions. It is found, in the experiment, that the in/out asymmetry λq,i/λq,o is strongly increasing with increasing density. Most notably the heat flux density at the inner divertor target is reducing with increasing λq,i whilst the total power onto each divertor target stays constant. It is found that λq,o exhibits no significant density dependence for hydrogen and deuterium but increases with about the square root of the electron density for helium. The difference between H,D and He could be due to the different recycling behaviour in the divertor. These findings may help current modelling attempts to parametrize the density dependence of the widening of the power channel and thus allow for detailed comparison to both divertor effects like recycling or increased upstream SOL cross field transport.
Thermal transport in low dimensions from statistical physics to nanoscale heat transfer

CERN Document Server

2016-01-01

Understanding non-equilibrium properties of classical and quantum many-particle systems is one of the goals of contemporary statistical mechanics. Besides its own interest for the theoretical foundations of irreversible thermodynamics(e.g. of the Fourier's law of heat conduction), this topic is also relevant to develop innovative ideas for nanoscale thermal management with possible future applications to nanotechnologies and effective energetic resources. The first part of the volume (Chapters 1-6) describes the basic models, the phenomenology and the various theoretical approaches to understand heat transport in low-dimensional lattices (1D e 2D). The methods described will include equilibrium and nonequilibrium molecular dynamics simulations, hydrodynamic and kinetic approaches and the solution of stochastic models. The second part (Chapters 7-10) deals with applications to nano and microscale heat transfer, as for instance phononic transport in carbon-based nanomaterials, including the prominent case of na...
Nonlocal heat transport and improved target design for x-ray heating studies at x-ray free electron lasers

Science.gov (United States)

Hoidn, Oliver; Seidler, Gerald T.

2018-01-01

The extremely high-power densities and short durations of single pulses of x-ray free electron lasers (XFELs) have opened new opportunities in atomic physics, where complex excitation-relaxation chains allow for high ionization states in atomic and molecular systems, and in dense plasma physics, where XFEL heating of solid-density targets can create unique dense states of matter having temperatures on the order of the Fermi energy. We focus here on the latter phenomena, with special emphasis on the problem of optimum target design to achieve high x-ray heating into the warm dense matter (WDM) state. We report fully three-dimensional simulations of the incident x-ray pulse and the resulting multielectron relaxation cascade to model the spatial energy density deposition in multicomponent targets, with particular focus on the effects of nonlocal heat transport due to the motion of high energy photoelectrons and Auger electrons. We find that nanoscale high-Z /low-Z multicomponent targets can give much improved energy density deposition in lower-Z materials, with enhancements reaching a factor of 100. This has three important benefits. First, it greatly enlarges the thermodynamic parameter space in XFEL x-ray heating studies of lower-Z materials. Second, it allows the use of higher probe photon energies, enabling higher-information content x-ray diffraction (XRD) measurements such as in two-color XFEL operations. Third, while this is merely one step toward optimization of x-ray heating target design, the demonstration of the importance of nonlocal heat transport establishes important common ground between XFEL-based x-ray heating studies and more traditional laser plasma methods.
Heat and momentum transport of ion internal transport barrier plasmas on Large Helical Device

International Nuclear Information System (INIS)

Nagaoka, K.; Ida, K.; Yoshinuma, M.

2010-11-01

The peaked ion-temperature profile with steep gradient so called ion internal transport barrier (ion ITB) was formed in the neutral beam heated plasmas on the Large Helical Device (LHD) and the high-ion-temperature regime of helical plasmas has been significantly extended. The ion thermal diffusivity in the ion ITB plasma decreases down to the neoclassical transport level. The heavy ion beam probe (HIBP) observed the smooth potential profile with negative radial electric field (ion root) in the core region where the ion thermal diffusivity decreases significantly. The large toroidal rotation was also observed in the ion ITB core and the transport of toroidal momentum was analyzed qualitatively. The decrease of momentum diffusivity with ion temperature increase was observed in the ion ITB core. The toroidal rotation driven by ion temperature gradient so called intrinsic rotation is also identified. (author)
A new treatment of the heat transport equation with a transport barrier and applications to ECRH experiments in Tore Supra

Energy Technology Data Exchange (ETDEWEB)

Zou, X.L.; Giruzzi, A.G.; Bouquey, F.; Clary, J.; Darbos, C.; Lennholm, M.; Magne, R.; Segui, J.L. [CEA Cadarache, Dept. de Recherches sur la Fusion Controlee, 13 - Saint-Paul-lez-Durance (France); Clemencon, A. [MIT, Electrochemical Energy Laboratory, Cambridge, MA (United States); Guivarch, C. [Ecole Nationale des Ponts et Chaussees, 77 - Marne-la-Vallee (France)

2004-07-01

An exact analytical solution of the electron heat diffusion equation in a cylinder has been found with a step-like diffusion coefficient, plus a monomial increase in the radial direction and a constant damping term. This model is sufficiently general to describe heat diffusion in the presence of a critical gradient threshold or a transport barrier, superimposed to the usual trend of increasing heat diffusivity from the plasma core to the edge. This type of representation allows us to see some well-known properties of heat transport phenomena in a different light. For instance, it has been shown that the contributions of the Eigenmodes to the time dependent solution grow at speeds that depend on the Eigenmode order i.e. at the beginning of the heating phase all the Eigenmodes are equally involved, whereas at the end only the lower order ones are left. This implies, e.g., that high frequency modulation experiments provide a characterization of transport phenomena that is intrinsically different with respect to power balance analysis of a stationary phase. It is particularly useful to analyse power switch on/off events and whenever high frequency modulations are not technically feasible. Low-frequency (1-2 Hz) ECRH modulation experiments have been performed on Tore Supra. A large jump (a factor of 8) in the heat diffusivity has been clearly identified at the ECRH power deposition layer. The amplitude and phase of several harmonics of the Fourier transform of the modulated temperature, as well as the time evolution of the modulated temperature have been reproduced by the analytical solution. The jump is found to be much weaker at lower ECRH power (one gyrotron)

Influence of geologic layering on heat transport and storage in an aquifer thermal energy storage system

Science.gov (United States)

Bridger, D. W.; Allen, D. M.

2014-01-01

A modeling study was carried out to evaluate the influence of aquifer heterogeneity, as represented by geologic layering, on heat transport and storage in an aquifer thermal energy storage (ATES) system in Agassiz, British Columbia, Canada. Two 3D heat transport models were developed and calibrated using the flow and heat transport code FEFLOW including: a "non-layered" model domain with homogeneous hydraulic and thermal properties; and, a "layered" model domain with variable hydraulic and thermal properties assigned to discrete geological units to represent aquifer heterogeneity. The base model (non-layered) shows limited sensitivity for the ranges of all thermal and hydraulic properties expected at the site; the model is most sensitive to vertical anisotropy and hydraulic gradient. Simulated and observed temperatures within the wells reflect a combination of screen placement and layering, with inconsistencies largely explained by the lateral continuity of high permeability layers represented in the model. Simulation of heat injection, storage and recovery show preferential transport along high permeability layers, resulting in longitudinal plume distortion, and overall higher short-term storage efficiencies.
Optimal hysteretic control for a B M A P / S M / 1 / N queue with two operation modes

Directory of Open Access Journals (Sweden)

Dudin Alexander N.

1999-01-01

Full Text Available We consider B M A P / S M / 1 type queueing system with finite buffer of size N . The system has two operation modes, which are characterized by the matrix generating function of B M A P -input, the kernel of the semi-Markovian service process, and utilization cost. An algorithm for determining the optimal hysteresis strategy is presented.
Advances in the optimisation of apparel heating products: A numerical approach to study heat transport through a blanket with an embedded smart heating system

International Nuclear Information System (INIS)

Neves, S.F.; Couto, S.; Campos, J.B.L.M.; Mayor, T.S.

2015-01-01

The optimisation of the performance of products with smart/active functionalities (e. g. in protective clothing, home textiles products, automotive seats, etc.) is still a challenge for manufacturers and developers. The aim of this study was to optimise the thermal performance of a heating product by a numerical approach, by analysing several opposing requirements and defining solutions for the identified limitations, before the construction of the first prototype. A transfer model was developed to investigate the transport of heat from the skin to the environment, across a heating blanket with an embedded smart heating system. Several parameters of the textile material and of the heating system were studied, in order to optimise the thermal performance of the heating blanket. Focus was put on the effects of thickness and thermal conductivity of each layer, and on parameters associated with the heating elements, e.g. position of the heating wires relative to the skin, distance between heating wires, applied heating power, and temperature range for operation of the heating system. Furthermore, several configurations of the blanket (and corresponding heating powers) were analysed in order to minimise the heat loss from the body to the environment, and the temperature distribution along the skin. The results show that, to ensure an optimal compromise between the thermal performance of the product and the temperature oscillation along its surface, the distance between the wires should be small (and not bigger than 50 mm), and each layer of the heating blanket should have a specific thermal resistance, based on the expected external conditions during use and the requirements of the heating system (i.e. requirements regarding energy consumption/efficiency and capacity to effectively regulate body exchanges with surrounding environment). The heating system should operate in an ON/OFF mode based on the body heating needs and within a temperature range specified based on
Diffusive-to-ballistic transition of the modulated heat transport in a rarefied air chamber

Science.gov (United States)

Gomez-Heredia, C. L.; Macias, J.; Ordonez-Miranda, J.; Ares, O.; Alvarado-Gil, J. J.

2017-01-01

Modulated heat transfer in air subject to pressures from 760 Torr to 10-4 Torr is experimentally studied by means of a thermal-wave resonant cavity placed in a vacuum chamber. This is done through the analysis of the amplitude and phase delay of the photothermal signal as a function of the cavity length and pressure through of the Knudsen's number. The viscous, transitional, and free molecular regimes of heat transport are observed for pressures P>1.5 Torr, 25 mTorrheat transport.
Driving mechanism of SOL plasma flow and effects on the divertor performance in JT-60U

International Nuclear Information System (INIS)

Asakura, N.; Takenaga, H.; Sakurai, S.

2003-01-01

The measurements of the SOL flow and plasma profiles both at the high-field-side (HFS) and low field- side (LFS), for the first time, identified the SOL flow pattern and its driving mechanism. 'Flow reversal' was found near the HFS and LFS separatrix of the main plasma for the ion ∇β drift direction towards the divertor. Radial profiles of the SOL flow were similar to those calculated numerically using the UEDGE code with the plasma drifts included although Mach numbers in measurements were greater than those obtained numerically. Particle fluxes towards the HFS and LFS divertors produced by the parallel SOL flow and E r xB drift flow were evaluated. The particle flux for the case of intense gas puff and divertor pump (puff and pump) was investigated, and it was found that both the Mach number and collisionality were enhanced, in particular, at HFS. Drift flux in the private flux region was also evaluated, and important physics issues for the divertor design and operation, such as in-out asymmetries of the heat and particle fluxes, and control of impurity ions were investigated. (author)
Driving mechanism of SOL plasma flow an effects on the divertor performance in JT-60U

International Nuclear Information System (INIS)

Asakura, Nobuyuki; Takenaga, H.; Sakurai, S.

2003-01-01

The measurements of the scrape-off layer(SOL) flow and plasma profiles both at the high-field-side (HFS) and low-field-side (LFS), for the first time, identified the SOL flow pattern and its driving mechanism. 'Flow reversal' was found near the HFS and LFS separatrix of the main plasma for the ion ∇B drift direction towards the divertor, Radial profiles of the SOL flow were similar to those calculated numerically using the UEDGE code with the plasma drifts included although Mach numbers in measurements were greater than those obtained numerically. Particle fluxes towards the HFS and LFS divertors produced by the parallel SOL flow and E r xB drift flow were evaluated. The particle flux for the case of intense gas puff and divertor pump (puff and pump) was investigated, and it was found that both the Mach number and collisionality were enhanced, in particular, at HFS. Drift flux in the private flux region was also evaluated, and important physics issues for the divertor design and operation, such as in-out asymmetries of the heat and particle fluxes, and control of impurity ions were investigated. (author)
Sol-gel-state of hydrated zirconium dioxide

International Nuclear Information System (INIS)

Karakchiev, L.G.; Lyakhov, N.Z.

1995-01-01

The change in viscosity and density of a system in the course of sol-gel-xerogel has been traced. The size and molecular mass of particles in sol have been determined. Initial sol is practically a monodisperse system. Gel is a spatial net of similar particles. Reversible character of sol-gel transition with a change in water content in the system suggests instability of the bond between the particles in the structure of the solid state body formed. 11 refs.; 4 figs
Study of heat transfer and particle transport in Tore Supra and HL-2A tokamaks

International Nuclear Information System (INIS)

Song, S.

2011-12-01

This thesis reports on experimental studies of heat and particles transport performed on 2 large tokamaks: Tore Supra (based at CEA/Cadarache, France) and HL-2A (based at the Southwestern Institute of Physics, Chengdu, China). The modulated source is the Electron Cyclotron Resonance Heating (ECRH) for the heat pinch and density pump-out studies, while the non-local transport experiments use the Supersonic Molecular Beam Injection (SMBI) as source of modulation. The emphasis is put on the inward heat pinch. In the off-axis ECRH modulation experiments on Tore Supra with low frequency (1 Hz), strong heat inward transport has been observed, in particular for low density. Two transport models have been applied in order to analyze the experimental behavior. The first one is the linear pinch model (LPM) and the second one is an empirical model based on micro-instabilities theory, named Critical Gradient Model (CGM). Good agreement has been found for all harmonics between the experimental data and the simulation using LPM. On the other hand, good agreement has not been achieved using CGM. The density pump-out with large particles and energy losses during ECRH is commonly observed in tokamaks. A new dynamic approach using the modulation technique has been used in HL-2A for analyzing the transient phase of the density pump-out. A correlation between the turbulence increase and the density pump-out has been found. The non-local transport phenomenon, characterized by a fast transient process compared to the normal diffusive response to the perturbation is observed. Both phenomena, i.e., pump-out and non-locality, show as simultaneous variation of density and temperature. This can be an inspiration for the usage of a transport matrix which considers the density and temperature evolution together. Simulations with a simple transport matrix, with non-diagonal terms coupling temperature and density qualitatively reproduce the non-local and pump-out effects qualitatively
Skylab and solar exploration. [chromosphere-corona structure, energy production and heat transport processes

Science.gov (United States)

Von Puttkamer, J.

1973-01-01

Review of some of the findings concerning solar structure, energy production, and heat transport obtained with the aid of the manned Skylab space station observatory launched on May 14, 1973. Among the topics discussed are the observation of thermonuclear fusion processes which cannot be simulated on earth, the observation of short-wave solar radiation not visible to observers on earth, and the investigation of energy-transport processes occurring in the photosphere, chromosphere, and corona. An apparent paradox is noted in that the cooler chromosphere is heating the hotter corona, seemingly in defiance of the second law of thermodynamics, thus suggesting that a nonthermal mechanism underlies the energy transport. Understanding of this nonthermal mechanism is regarded as an indispensable prerequisite for future development of plasma systems for terrestrial applications.
Heat and fission product transport in molten core material pool with crust

International Nuclear Information System (INIS)

Yun, J.I.; Suh, K.Y.; Kang, C.S.

2005-01-01

Heat transfer and fluid flow in a molten pool are influenced by internal volumetric heat generated from the radioactive decay of fission product species retained in the reactor vessel during a severe accident. The pool superheat is determined based on the overall energy balance that equates the heat production rate to the heat loss rate. Decay heat of fission products in the pool is estimated by product of the mass concentration and energy conversion factor of each fission product. Twenty-nine elements are chosen and classified by their chemical properties to calculate heat generation rate in the pool. The mass concentration of a fission product is obtained from released fraction and the tabular output of the ORIGEN 2 code. The initial core and pool inventories at each time can also be estimated using ORIGEN 2. The released fraction of each fission product is calculated based on the bubble dynamics and mass transport. Numerical analysis is performed for heat and fission product transport in a molten core material pool during the Three Mile Island Unit 2 (TMI-2) accident. The pool is assumed to be a partially filled hemisphere, whose change in geometry is neglected during the numerical calculation. Calculated results indicate that the peak temperature in the molten pool is significantly lowered, since a substantial amount of the volatile fission products is released from the molten pool during progression of the accident. The results may directly be applied to the existing severe accident analysis codes to more mechanistically determine the thermal load to the reactor vessel lower head during the in-vessel retention
Method of making ionic liquid mediated sol-gel sorbents

Science.gov (United States)

Malik, Abdul; Shearrow, Anne M.

2017-01-31

Ionic liquid (IL)-mediated sol-gel hybrid organic-inorganic materials present enormous potential for effective use in analytical microextraction. One obstacle to materializing this prospect arises from high viscosity of ILs significantly slowing down sol-gel reactions. A method was developed which provides phosphonium-based, pyridinium-based, and imidazolium-based IL-mediated advanced sol-gel organic-inorganic hybrid materials for capillary microextraction. Scanning electron microscopy results demonstrate that ILs can serve as porogenic agents in sol-gel reactions. IL-mediated sol-gel coatings prepared with silanol-terminated polymers provided up to 28 times higher extractions compared to analogous sol-gel coatings prepared without any IL in the sol solution. This study shows that IL-generated porous morphology alone is not enough to provide effective extraction media: careful choice of the organic polymer and the precursor with close sol-gel reactivity must be made to ensure effective chemical bonding of the organic polymer to the created sol-gel material to be able to provide the desired sorbent characteristics.
Transport properties and specific heat of UTe and USb

International Nuclear Information System (INIS)

Ochiai, A.; Suzuki, Y.; Shikama, T.; Suzuki, K.; Hotta, E.; Haga, Y.; Suzuki, T.

1994-01-01

Uranium monochalcogenides and monopnictides crystallize in the NaCl-type structure and exhibit ferromagnetic and antiferromagnetic order, respectively. These series reveal interesting properties such as Kondo behavior of UTe. However, such interesting properties are much sample dependent. We grew single crystals of USb and UTe with high purity using the Bridgman technique, and measured transport properties and specific heat. ((orig.))
Sol-gel additive for systems with inorganic binders

International Nuclear Information System (INIS)

Akstinat, M.; Antenen, D.; Suter, W.

1996-01-01

A sol-gel additive for inorganic binder systems and sol-gel process for producing air-placed concrete and mortar by using such sol-gel additives are disclosed. Sol-gel additives for gel-derived inorganic binder systems (for example plaster, cement, lime, special slags, etc.) marked improve the consistency of such binder systems during processing or allow their consistency to be regulated. In addition, these sol-gel additives regulate setting times and substantially improve durability (chemical resistance, reduced permeability) and the mechanical properties of the set binder system. (author)
Application of Sol-Gel Method as a Protective Layer on a Specular Reflective Surface for Secondary Reflector in a Solar Receiver

Energy Technology Data Exchange (ETDEWEB)

Afrin, Samia; Dagdelen, John; Ma, Zhiwen; Kumar, Vinod

2017-01-01

Highly-specular reflective surfaces that can withstand elevated-temperatures are desirable for many applications including reflective heat shielding in solar receivers and secondary reflectors, which can be used between primary concentrators and heat collectors. A high-efficiency, high-temperature solar receiver design based on arrays of cavities needs a highly-specular reflective surface on its front section to help sunlight penetrate into the absorber tubes for effective flux spreading. Since this application is for high-temperature solar receivers, this surface needs to be durable and to maintain its optical properties through the usable life. Degradation mechanisms associated with elevated temperatures and thermal cycling, which include cracking, delamination, corrosion/oxidation, and environmental effects, could cause the optical properties of surfaces to degrade rapidly in these conditions. Protected mirror surfaces for these applications have been tested by depositing a thin layer of SiO2 on top of electrodeposited silver by means of the sol-gel method. To obtain an effective thin film structure, this sol-gel procedure has been investigated extensively by varying process parameters that affect film porosity and thickness. Endurance tests have been performed in a furnace at 150 degrees C for thousands of hours. This paper presents the sol-gel process for intermediate-temperature specular reflective coatings and provides the long-term reliability test results of sol-gel protected silver-coated surfaces.
Study of Heat Flux Threshold and Perturbation Effect on Transport Barrier Formation Based on Bifurcation Model

International Nuclear Information System (INIS)

Chatthong, B.; Onjun, T.; Imbeaux, F.; Sarazin, Y.; Strugarek, A.; Picha, R.; Poolyarat, N.

2011-06-01

Full text: Formation of transport barrier in fusion plasma is studied using a simple one-field bistable S-curve bifurcation model. This model is characterized by an S-line with two stable branches corresponding to the low (L) and high (H) confinement modes, connected by an unstable branch. Assumptions used in this model are such that the reduction in anomalous transport is caused by v E velocity shear effect and also this velocity shear is proportional to pressure gradient. In this study, analytical and numerical approaches are used to obtain necessary conditions for transport barrier formation, i.e. the ratio of anomalous over neoclassical coefficients and heat flux thresholds which must be exceeded. Several profiles of heat sources are considered in this work including constant, Gaussian, and hyperbolic tangent forms. Moreover, the effect of perturbation in heat flux is investigated with respect to transport barrier formation
Minimization of transport and distribution cost for district heating study of particular cases

International Nuclear Information System (INIS)

Barreau, A.; Caizergues, R.; Moret Bailly, J.

1977-01-01

The transport and distribution of hot pressurized water involve different sets of criteria: transport networks, heat distribution networks, storages. The minimization of transport cost is studied together with the distribution of thermal energy. The same parameters are introduced into these programs. The same method is used for rate of flow calculations, but mathematical methods of pipe diameter calculation are different. Some transport and distribution networks are studied with the corresponding computed programs: 52 branches networks-27 terminations; 287 branches networks-148 terminations
3D modeling of groundwater heat transport in the shallow Westliches Leibnitzer Feld aquifer, Austria

Science.gov (United States)

Rock, Gerhard; Kupfersberger, Hans

2018-02-01

For the shallow Westliches Leibnitzer feld aquifer (45 km2) we applied the recently developed methodology by Kupfersberger et al. (2017a) to derive the thermal upper boundary for a 3D heat transport model from observed air temperatures. We distinguished between land uses of grass and agriculture, sealed surfaces, forest and water bodies. To represent the heat flux from heated buildings and the mixture between different land surfaces in urban areas we ran the 1D vertical heat conduction module SoilTemp which is coupled to the heat transport model (using FEFLOW) on a time step basis. Over a simulation period of 23 years the comparison between measured and observed groundwater temperatures yielded NSE values ranging from 0.41 to 0.92 including readings at different depths. The model results showed that the thermal input signals lead to distinctly different vertical groundwater temperature distributions. To overcome the influence of specific warm or cold years we introduced the computation of an annual averaged groundwater temperature profile. With respect to the use of groundwater cooling or heating facilities we evaluated the application of vertically averaged statistical groundwater temperature distributions compared to the use of temperature distributions at selected dates. We concluded that the heat transport model serves well as an aquifer scale management tool to optimize the use of the shallow subsurface for thermal purposes and to analyze the impacts of corresponding measures on groundwater temperatures.
Effect of Chelating Agents on the Stability of Nano-TiO2 Sol Particles for Sol-Gel Coating.

Science.gov (United States)

Maeng, Wan Young; Yoo, Mi

2015-11-01

Agglomeration of sol particles in a titanium alkoxide (tetrabutyl orthotitanate (TBOT), > 97%) solution during the hydrolysis and condensation steps makes the sol solution difficult to use for synthesizing homogeneous sol-gel coating. Here, we have investigated the effect of stabilizing agents (acetic acid and ethyl acetoacetate (EAcAc)) on the agglomeration of Ti alkoxide particles during hydrolysis and condensation in order to determine the optimized conditions for controlling the precipitation of TiO2 particles. The study was conducted at R(AC) ([acetic acid]/[TBOT]) = 0.1-5 and R(EAcAc)([EAcAc]/[TBOT]) = 0.05-0.65. We also studied the effects of a basic catalyst ethanolamine (ETA), water, and HCl on sol stability. The chelating ligands in the precursor sol were analyzed with FT-IR. The coating properties were examined by focused ion beam. The stabilizing agents (acetic acid and EAcAc) significantly influenced the agglomeration and precipitation of TBOT precursor particles during hydrolysis. As R(AC) and R(EAcAc) increased, the agglomeration remarkably decreased. The stability of the sol with acetic acid and EAcAc arises from the coordination of the chelating ligand to TBOT that hinders hydrolysis and condensation. A uniform fine coating (thickness: 30 nm) on stainless steel was obtained by using an optimized sol with R(AC) = 0.5 and R(EAcAc) = 0.65.
A pumped, two-phase flow heat transport system for orbiting instrument payloads

Science.gov (United States)

Fowle, A. A.

1981-01-01

A pumped two-phase (heat absorption/heat rejection) thermal transport system for orbiting instrument payloads is investigated. The thermofluid characteristics necessary for the system design are discussed. A preliminary design with a series arrangement of four instrument heat stations and six radiators in a single loop is described in detail, and the total mass is estimated to be 134 kg, with the radiators, instrument heat stations, and fluid reservoir accounting for approximately 86, 24, and 12 kg, respectively. The evaluation of preliminary test results shows that the system has potential advantages; however, further research is necessary in the areas of one-g and zero-g heat transfer coefficients/fluid regimes, fluid by-pass temperature control, and reliability of small pumps.
Conceptual design of heat transport systems and components of PFBR-NSSS

International Nuclear Information System (INIS)

Chetal, S.C.; Bhoje, S.B.; Kale, R.D.; Rao, A.S.L.K.; Mitra, T.K.; Selvaraj, A.; Sethi, V.K.; Sundaramoorthy, T.R.; Balasubramaniyan, V.; Vaidyanathan, G.

1996-01-01

The production of electrical power from sodium cooled fast reactors in the present power scenario in India demands emphasis on plant economics consistent with safety. Number of heat transport systems/components and the design of principal heat transport components viz sodium pumps, IHX and steam generators play significant role in the plant capital cost and capacity factor. The paper discusses the basis of selection of 2 primary pumps, 4 IHX, 2 secondary loops, 2 secondary pumps and 8 steam generators for the 500 MWe Prototype Fast Breeder Reactor (PFBR), which is now in design stage. The principal design features of primary pump, IHX and steam generator have been selected based on design simplicity, ease of manufacture and utilization of established designs. The paper also describes the conceptual design of above mentioned three components. (author). 3 figs, 2 tabs

An alternative treatment of heat flow for charge transport in semiconductor devices

International Nuclear Information System (INIS)

Grupen, Matt

2009-01-01

A unique thermodynamic model of Fermi gases suitable for semiconductor device simulation is presented. Like other models, such as drift diffusion and hydrodynamics, it employs moments of the Boltzmann transport equation derived using the Fermi-Dirac distribution function. However, unlike other approaches, it replaces the concept of an electron thermal conductivity with the heat capacity of an ideal Fermi gas to determine heat flow. The model is used to simulate a field-effect transistor and show that the external current-voltage characteristics are strong functions of the state space available to the heated Fermi distribution.
Amperometric biosensor for hydrogen peroxide based on hemoglobin entrapped in titania sol-gel film

International Nuclear Information System (INIS)

Yu Jiuhong; Ju Huangxian

2003-01-01

Hemoglobin (Hb) was entrapped in a titania sol-gel matrix and used as a mimetic peroxidase to construct a novel amperometric biosensor for hydrogen peroxide. The Hb entrapped titania sol-gel film was obtained with a vapor deposition method, which simplified the traditional sol-gel process for protein immobilization. The morphologies of both titania sol-gel and the Hb films were characterized using scanning electron microscopy (SEM) and proved to be chemically clean, porous, homogeneous. This matrix provided a biocompatible microenvironment for retaining the native structure and activity of the entrapped Hb and a very low mass transport barrier to the substrates. H 2 O 2 could be reduced by the catalysis of the entrapped hemoglobin at -300 mV without any mediator. The reagentless H 2 O 2 sensor exhibited a fast response (less than 5 s) and sensitivity as high as 1.29 mA mM -1 cm -2 . The linear range for H 2 O 2 determination was from 5.0x10 -7 to 5.4x10 -5 M with a detection limit of 1.2x10 -7 M. The apparent Michaelis-Menten constant of the encapsulated hemoglobin was calculated to be 0.18±0.02 mM. The stability of the biosensor was also evaluated
Structural evolution of silica sols modified with formamide

Directory of Open Access Journals (Sweden)

Lenza R.F.S.

2001-01-01

Full Text Available In this work we investigated the influence of formamide on the acid-catalyzed sol-gel process by Fourier transform infrared spectroscopy (FTIR. Three silica sols were studied: Sol catalyzed with nitric acid without formamide, sol catalyzed with nitric acid containing formamide and sol catalyzed with a mixture of nitric acid and hydrofluoric acid and modified with formamide. Following the time evolution of both the Si-(OH stretching vibration at around 950 cm-1 and the Si-O-(Si vibration between 1040 cm-1 and 1200 cm-1 we were able to describe the structural evolution of each sol. The curve of evolution of Si-(OH stretching vibration corresponding to sol A has a simple asymptotic evolution. In the case of formamide containing sol, we observed a two-step structural evolution indicating that for the system containing formamide the polymerization goes through a temporary stabilization of oligomers, which can explain the non-variation of the Si-O(H bond wavenumber for a certain time. Gelation times were of several days for gels without formamide and few hours for gels containing additive. The presence of additive resulted in a highly interconnected gel.
Synthesis and characterization of NiO nanopowder by sol-gel process

Energy Technology Data Exchange (ETDEWEB)

Ningsih, Sherly Kasuma Warda [Department of Chemistry, Faculty of Mathematics and Natural Sciences Padang State University, Kampus Air Tawar, Jl. Prof. Dr. Hamka, West Sumatera, 25161, Indonesia Email: sherly-kasuma@yahoo.com (Indonesia)

2015-09-30

Preparation of nickel oxide (NiO) nanopowder by sol-gel process has been studied. NiO nanopowders were obtained by sol-gel method by using nickel nitrate hexahydrate and sodium hydroxide and aquadest were used as precursor, agent precipitator and solvent, respectively. The powders were formed by drying at 110°C and followed by heating in the furnace at 400°C for 1.5 hours. The product was obtained black powder. The product was characterized by Energy Dispesive X-ray Fluorescence (ED-XRF), X-ray diffraction (XRD) and Scanning Electron Microscopy (SEM). The ED-XRF pattern shows the composition of NiO produced was 97.1%. The XRD pattern showed NiO forms were produced generally in monoclinic stucture. The crystalline size of NiO was obtained in the range 40-85 nm. SEM micrograph clearly showed that powder had a spherical with uniform distribution size is 0.1-1.0 µm approximately.
The influence of Uranium-Thorium ratio and heating time during gelation using as a CCl4(NH3) on the Gel quality

International Nuclear Information System (INIS)

Indra-Suryawan; Sukarsono, R; Setyo-Sulardi

1996-01-01

Gel has been prepared from a uranium-thorium sol using CCI 4 (NH 3 ) as a gelling medium. The uranium-thorium ratio and the heating time during gelation have been chosen as variables. The sol was prepared by mixing Th(NO 3 ) 4 and UO 2 (NO 3 ) 2 solutions, heating the solution at 95 o C and adding NH 4 OH solution drop by drop until colloidal particles were formed. Sol was then fed into a gelation column containing CCI 4 (NH 3 ), where the sol was transformed into gel. A good gel has properties such as sphere in shape and elastic which it will not crack when it is dropped from 2 metres height. The experimental work resulted a good gel when the percentage of uranium was about 15 - 25 % at heating time of 40 - 50 minutes
Functional coatings: the sol-gel approach

International Nuclear Information System (INIS)

Belleville, Ph.

2010-01-01

CEA's sol-gel laboratory is specialized in the development of innovative sol-gel optical coatings and has extended its application field to membrane materials and coatings for energy conversion, to electric coatings for microelectronics devices and to thin films for gas sensing. This article describes, by way of examples, the laboratory's research on sol-gel functional coatings, including nano-material synthesis, organic-inorganic hybrid-based solution preparation as well as deposition process development and prototyping. (author)
The SOL width and the MHD interchange instability in tokamaks

Energy Technology Data Exchange (ETDEWEB)

Kerner, W [Commission of the European Communities, Abingdon (United Kingdom). JET Joint Undertaking; Pogutse, O [Kurchatov institute, Moscow (Russian Federation)

1994-07-01

Instabilities in the SOL plasma can strongly influence the SOL plasma behaviour and in particular the SOL width. The SOL stability analysis shows that there exists a critical ratio of the thermal energy and the magnetic energy. If the SOL beta is greater than this critical value, the magnetic field cannot prevent the plasma displacement and a strong MHD instability in the SOL occurs. In the opposite case only slower resistive instabilities can develop. A theoretical investigation of the SOL plasma stability is presented for JET single-null and double-null divertor configurations. The dependence of the stability threshold on the SOL beta and on the sheath resistance is established. Applying a simple mixing length argument gives the scaling of the SOL width. 5 refs., 2 figs.
Increased Heat Transport in Ultra-hot Jupiter Atmospheres through H2 Dissociation and Recombination

Science.gov (United States)

Bell, Taylor J.; Cowan, Nicolas B.

2018-04-01

A new class of exoplanets is beginning to emerge: planets with dayside atmospheres that resemble stellar atmospheres as most of their molecular constituents dissociate. The effects of the dissociation of these species will be varied and must be carefully accounted for. Here we take the first steps toward understanding the consequences of dissociation and recombination of molecular hydrogen (H2) on atmospheric heat recirculation. Using a simple energy balance model with eastward winds, we demonstrate that H2 dissociation/recombination can significantly increase the day–night heat transport on ultra-hot Jupiters (UHJs): gas giant exoplanets where significant H2 dissociation occurs. The atomic hydrogen from the highly irradiated daysides of UHJs will transport some of the energy deposited on the dayside toward the nightside of the planet where the H atoms recombine into H2; this mechanism bears similarities to latent heat. Given a fixed wind speed, this will act to increase the heat recirculation efficiency; alternatively, a measured heat recirculation efficiency will require slower wind speeds after accounting for H2 dissociation/recombination.
Sol-gel method for encapsulating molecules

Science.gov (United States)

Brinker, C. Jeffrey; Ashley, Carol S.; Bhatia, Rimple; Singh, Anup K.

2002-01-01

A method for encapsulating organic molecules, and in particular, biomolecules using sol-gel chemistry. A silica sol is prepared from an aqueous alkali metal silicate solution, such as a mixture of silicon dioxide and sodium or potassium oxide in water. The pH is adjusted to a suitably low value to stabilize the sol by minimizing the rate of siloxane condensation, thereby allowing storage stability of the sol prior to gelation. The organic molecules, generally in solution, is then added with the organic molecules being encapsulated in the sol matrix. After aging, either a thin film can be prepared or a gel can be formed with the encapsulated molecules. Depending upon the acid used, pH, and other processing conditions, the gelation time can be from one minute up to several days. In the method of the present invention, no alcohols are generated as by-products during the sol-gel and encapsulation steps. The organic molecules can be added at any desired pH value, where the pH value is generally chosen to achieve the desired reactivity of the organic molecules. The method of the present invention thereby presents a sufficiently mild encapsulation method to retain a significant portion of the activity of the biomolecules, compared with the activity of the biomolecules in free solution.
Design to nullify activity movement in heat transport systems

International Nuclear Information System (INIS)

Hemmings, R.L.; Barber, D.

1975-01-01

This article describes the methods by which designers can reduce the adverse effects of system corrosion and the resultant activation of the corrosion products in heat transport systems. The presentation will cover: a) choice of materials; b) assessment of the need of components; c) control of system chemistry; d) factors considered in sizing HTS purification systems; i) control of activation and fission products; ii) decontamination. (author)
FFTF Heat Transport System (HTS) component and system design

International Nuclear Information System (INIS)

Young, M.W.; Edwards, P.A.

1980-01-01

The FFTF Heat Transport Systems and Components designs have been completed and successfully tested at isothermal conditions up to 427 0 C (800 0 F). General performance has been as predicted in the design analyses. Operational flexibility and reliability have been outstanding throughout the test program. The components and systems have been demonstrated ready to support reactor powered operation testing planned later in 1980
Comparing the value of bioenergy in the heating and transport sectors of an electricity-intensive energy system in Norway

International Nuclear Information System (INIS)

Assefa Hagos, Dejene; Gebremedhin, Alemayehu; Folsland Bolkesjø, Torjus

2015-01-01

The objective of this paper is to identify the most valuable sector for the use of bioenergy in a flexible energy system in order to meet the energy policy objectives of Inland Norway. A reference system was used to construct alternative systems in the heating and transport sectors. The alternative system in the heating sector is based on heat pumps and bio-heat boilers while the alternative systems in the transport sector are based on three different pathways: bio-dimethyl ether, hydrogen fuel cell vehicles and battery electric vehicles. The alternative systems were compared with the reference system after a business-economic optimisation had been made using an energy system analysis tool. The results show that the excess electricity availability due to increased energy efficiency measures hampers the competitiveness and penetration of bio-heating over heat pumps in the heating sector. Indeed, the synergy effect of using bio-dimethyl ether in the transport sector for an increased share of renewable energy sources is much higher than that of the hydrogen fuel cell vehicle and battery electric vehicle pathways. The study also revealed that increasing renewable energy production would increase the renewable energy share more than what would be achieved by an increase in energy efficiency. -- Highlights: •Bio-heating is less competitive over heat pump for low quality heat production. •Renewable energy production meets policy objectives better than system efficiency. •Bioenergy is more valuable in the transport sector than the heating sector
Convective transport in tokamaks

International Nuclear Information System (INIS)

D'Ippolito, D.A.; Myra, J.R.; Russell, D.A.; Krasheninnikov, S.I.; Pigarov, A.Yu.; Yu, G.Q.; Xu, X.Q.; Nevins, W.M.

2005-01-01

Scrape-off-layer (SOL) convection in fusion experiments appears to be a universal phenomenon that can 'short-circuit' the divertor in some cases. The theory of 'blob' transport provides a simple and robust physical paradigm for studying convective transport. This paper summarizes recent advances in the theory of blob transport and its comparison with 2D and 3D computer simulations. We also discuss the common physical basis relating radial transport of blobs, pellets, and ELMs and a new blob regime that may lead to a connection between blob transport and the density limit. (author)
Turbulence in the SOL of ASDEX and W7-AS

Energy Technology Data Exchange (ETDEWEB)

Endler, M [Association Euratom-Max-Planck-Institut fuer Plasmaphysik, Garching (Germany); Giannone, L. [Association Euratom-Max-Planck-Institut fuer Plasmaphysik, Garching (Germany); McCormick, K [Association Euratom-Max-Planck-Institut fuer Plasmaphysik, Garching (Germany); Niedermeyer, H [Association Euratom-Max-Planck-Institut fuer Plasmaphysik, Garching (Germany); Rudyj, A [Association Euratom-Max-Planck-Institut fuer Plasmaphysik, Garching (Germany); Theimer, G [Association Euratom-Max-Planck-Institut fuer Plasmaphysik, Garching (Germany); Tsois, N [Association Euratom-Max-Planck-Institut fuer Plasmaphysik, Garching (Germany); Zoletnik, S [Hungarian Academy of Sciences, Budapest (Hungary). Central Research Inst. for Physics; ASDEX Team; W7-AS Team

1995-05-01

Electrostatic fluctuations have been measured in the scrape-off layer of ASDEX and W7-AS by Langmuir probes and by observation of H{sub {alpha}} light and light emitted from a fast Li atom beam with high spatial and temporal resolution. It was demonstrated that these fluctuations contribute a significant, if not dominant, fraction of the anomalous radial particle transport. The basic properties of the fluctuations are the same in both experiments. A model for an instability mechanism specific to the SOL is presented including density, temperature and electric potential fluctuations. From this model mixing length estimates for the radial transport and resulting density and pressure gradients in the SOL are derived and compared to measurements in the mid-plane and in the divertor of ASDEX. In spite of several simplifications in the model a quantitative agreement up to factors of 1-3 and a qualitative agreement for variations of discharge parameters is achieved between the model predictions and the measurements. Data from poloidal multi-pin probe arrays are decomposed into a sum of spatial-temporal ``events`` by means of a fitting procedure. Centres of selected events serve as reference points for the analysis of the dynamics in their surroundings. Averaging shows that positive and negative potential events appear mostly in pairs with the E x B drift in between directed radially outward. (orig.).
Dielectric Properties of Sol-Gel Derived Barium Strontium Titanate and Microwave Sintering of Ceramics

Science.gov (United States)

Selmi, Fathi A.

60% of theoretical density. Microwave sintering also led to improvement in terms of uniform structure and electrical properties. Ba_{0.65}Sr _{0.35}TiO_3 was sintered using the microwave power at 1300 ^circC for 10 minutes. A density of 99% was achieved with small and uniform grain size. Superconducting powders have been successfully prepared by the sol-gel process and sintered and annealed using microwave power. Sintering and densification was achieved in a shorter time with microwave heating than with conventional heating and microwave heating appears to result in refined microstructure.
Heat transport inventory monitoring for CANDU-PHW reactors

International Nuclear Information System (INIS)

Hussein, E.; Luxat, J.C.

1984-01-01

A computer-based D 2 O coolant inventory monitoring system proposed for implementation on the digital computer controllers at Ontario Hydro's CANDU generating units is discussed. By monitoring process parameters and utilizing probabilistically-based decision algorithms, timely indication of any significant loss of D 2 O inventory will be provided to the operator. The monitoring is performed in a co-ordinated manner such that D 2 O losses from either the heat transport system or the inventory control system can be detected. (orig.)
Synthesis of uranium and thorium dioxides by Complex Sol-Gel Processes (CSGP). Synthesis of uranium oxides by Complex Sol-Gel Processes (CSGP)

International Nuclear Information System (INIS)

Deptula, A.; Brykala, M.; Lada, W.; Olczak, T.; Wawszczak, D.; Chmielewski, A.G.; Modolo, G.; Daniels, H.

2010-01-01

In the Institute of Nuclear Chemistry and Technology (INCT), a new method of synthesis of uranium and thorium dioxides by original variant of sol-gel method - Complex Sol-Gel Process (CSGP), has been elaborated. The main modification step is the formation of nitrate-ascorbate sols from components alkalized by aqueous ammonia. Those sols were gelled into: - irregularly agglomerates by evaporation of water; - medium sized microspheres (diameter <150) by IChTJ variant of sol-gel processes by water extraction from drops of emulsion sols in 2-ethylhexanol-1 by this solvent. Uranium dioxide was obtained by a reduction of gels with hydrogen at temperatures >700 deg. C, while thorium dioxide by a simple calcination in the air atmosphere. (authors)
Mesure de la vitesse d'infiltration des eaux dans le sol : Cas des sols ...

African Journals Online (AJOL)

C'est donc une infiltration superficielle qui ne peut pas modifier la composition des eaux de l'aquifère. Ces sols sont alors favorables à une telle agriculture. Mots clés: mesure, vitesse, infiltration, sols, pollutions, eau, Niari, Congo. English Title: Measuring the speed of the water infiltration into the soil: case of the soil of the ...
Tokamak electron heat transport by direct numerical simulation of small scale turbulence

International Nuclear Information System (INIS)

Labit, B.

2002-10-01

In a fusion machine, understanding plasma turbulence, which causes a degradation of the measured energy confinement time, would constitute a major progress in this field. In tokamaks, the measured ion and electron thermal conductivities are of comparable magnitude. The possible sources of turbulence are the temperature and density gradients occurring in a fusion plasma. Whereas the heat losses in the ion channel are reasonably well understood, the origin of the electron losses is more uncertain. In addition to the radial velocity associated to the fluctuations of the electric field, electrons are more affected than ions by the magnetic field fluctuations. In experiments, the confinement time can be conveniently expressed in terms of dimensionless parameters. Although still somewhat too imprecise, these scaling laws exhibit strong dependencies on the normalized pressure β or the normalized Larmor radius, ρ * . The present thesis assesses whether a tridimensional, electromagnetic, nonlinear fluid model of plasma turbulence driven by a specific instability can reproduce the dependence of the experimental electron heat losses on the dimensionless parameters β and ρ * . The investigated interchange instability is the Electron Temperature Gradient driven one (ETG). The model is built by using the set of Braginskii equations. The developed simulation code is global in the sense that a fixed heat flux is imposed at the inner boundary, leaving the gradients free to evolve. From the nonlinear simulations, we have put in light three characteristics for the ETG turbulence: the turbulent transport is essentially electrostatic; the potential and pressure fluctuations form radially elongated cells called streamers; the transport level is very low compared to the experimental values. The thermal transport dependence study has shown a very small role of the normalized pressure, which is in contradiction with the Ohkama's formula. On the other hand, the crucial role of the
Influence of transport on EBW heating efficiency in magnetic confinement devices

International Nuclear Information System (INIS)

Cappa, A.; Castejon, F.; Lopez-Bruna, D.; Tereshchenko, M.

2007-01-01

The main advantage of the heating performed by electron Bernstein waves (EBW) in the O-X-B1 regime (O mode injection that is converted into X mode, which is converted in Bernstein wave, strongly absorbed close to the cyclotron resonance layer at first harmonic) is that there is no cut-off density. Therefore, this heating system can work without upper density limit, still having all the advantages of electron cyclotron resonance heating (ECRH), which is localised in phase space due to its resonant nature. The heating efficiency of Bernstein waves depends on the fraction of waves that is transformed from O to X mode at the O mode cut off layer, then on the fraction of power converted into Bernstein waves at the upper hybrid resonance layer and, finally, on the final position of the absorption in the plasma. All these factors are related to the density profile, since the positions of the cut off and of the upper hybrid resonance layers depend on the actual plasma density profile. Besides, the absorption profile depends also on the temperature profile. Moreover, it is possible to observe that the former layers only appear for high enough plasma density, than can be obtained by gas puffing, as has been observed in the simulations performed for TJ-II stellarator. For such reasons, particle transport is basic for understanding and guaranteeing EBW heating. In this work, TJ-II plasmas are taken as a case example in order to simulate the full evolution of a plasma discharge that is created and heated by ECRH in a first step and finally is heated using EBW. The evolution of the discharge is simulated using the transport code ASTRA and the sequence of the discharge is as follows: O mode is launched on a steady state plasma with density lower than the O mode cut-off. Then a gas puff is injected in order to increase the plasma density over the level in which EBW heating is efficient because O mode cut off and upper hybrid layer appear. EBW ray tracing calculations are performed

Transport-driven scrape-off layer flows and the x-point dependence of the L-H power threshold in Alcator C-Moda)

Science.gov (United States)

LaBombard, B.; Rice, J. E.; Hubbard, A. E.; Hughes, J. W.; Greenwald, M.; Granetz, R. S.; Irby, J. H.; Lin, Y.; Lipschultz, B.; Marmar, E. S.; Marr, K.; Mossessian, D.; Parker, R.; Rowan, W.; Smick, N.; Snipes, J. A.; Terry, J. L.; Wolfe, S. M.; Wukitch, S. J.

2005-05-01

Factor of ˜2 higher power thresholds for low- to high-confinement mode transitions (L-H) with unfavorable x-point topologies in Alcator C-Mod [Phys. Plasmas 1, 1511 (1994)] are linked to flow boundary conditions imposed by the scrape-off layer (SOL). Ballooning-like transport drives flow along magnetic field lines from low- to high-field regions with toroidal direction dependent on upper/lower x-point balance; the toroidal rotation of the confined plasma responds, exhibiting a strong counter-current rotation when B ×∇B points away from the x point. Increased auxiliary heating power (rf, no momentum input) leads to an L-H transition at approximately twice the edge electron pressure gradient when B ×∇B points away. As gradients rise prior to the transition, toroidal rotation ramps toward the co-current direction; the H mode is seen when the counter-current rotation imposed by the SOL flow becomes compensated. Remarkably, L-H thresholds in lower-limited discharges are identical to lower x-point discharges; SOL flows are also found similar, suggesting a connection.
LONG DURATION FLARE EMISSION: IMPULSIVE HEATING OR GRADUAL HEATING?

Energy Technology Data Exchange (ETDEWEB)

Qiu, Jiong; Longcope, Dana W. [Department of Physics, Montana State University, Bozeman MT 59717-3840 (United States)

2016-03-20

Flare emissions in X-ray and EUV wavelengths have previously been modeled as the plasma response to impulsive heating from magnetic reconnection. Some flares exhibit gradually evolving X-ray and EUV light curves, which are believed to result from superposition of an extended sequence of impulsive heating events occurring in different adjacent loops or even unresolved threads within each loop. In this paper, we apply this approach to a long duration two-ribbon flare SOL2011-09-13T22 observed by the Atmosphere Imaging Assembly (AIA). We find that to reconcile with observed signatures of flare emission in multiple EUV wavelengths, each thread should be heated in two phases, an intense impulsive heating followed by a gradual, low-rate heating tail that is attenuated over 20–30 minutes. Each AIA resolved single loop may be composed of several such threads. The two-phase heating scenario is supported by modeling with both a zero-dimensional and a 1D hydrodynamic code. We discuss viable physical mechanisms for the two-phase heating in a post-reconnection thread.
Influence of silane on the structure of polystyrene prepared by sol-gel coatings via UV curing

Directory of Open Access Journals (Sweden)

Balbay Senay

2017-01-01

Full Text Available Light, heat, oxygen, moisture, ozone, atmospheric pollution and biological effects are the most important effectives wreak to chemical degradation in the polymer structure. In result of chemical degradation on the polymer consist of problems such as discoloration, brittleness, surface cracks, perspiration, crumbling, smell, surface acidity. In this work, it is aimed to improve the problem of the polystyrene (PS material against chemical degradation. For this reason, PS is coated with silica sol-gel hybrid coating. Silica sol-gel was synthesized by using vinyltrimethoxysilane (VTMS as a cross-linker and tetraethylorthosilicate (TEOS as a silica source. Firstly, four different pre-treatment technique (oven, vacuum oven, lyophilizer and freezing was studied to determine the most suitable pre-treatment technique for coating on PS substrate of sol-gel prepared with initial formulation (S1. A freezing technique gave the best results for coating sample. The change of surface colour of coated PS was measured by CIE L*a*b* methods. Secondly, the most suitable curing agent (Irgacure 184, Irgacure 819, Darocur 1173 and TiO2 as crystalline anatase phase was determined to coat the sol-gel on PS. It was determined to the lowest yellowing of PS surface hybrid coated as UV curing of TEOS sol modified by VTMS and TiO2 as photo-initiators. Finally, the chemical and morphological structure of the coated PS samples was determined by FT-IR and SEM instruments, respectively.
Local and Nonlocal Parallel Heat Transport in General Magnetic Fields

International Nuclear Information System (INIS)

Castillo-Negrete, D. del; Chacon, L.

2011-01-01

A novel approach for the study of parallel transport in magnetized plasmas is presented. The method avoids numerical pollution issues of grid-based formulations and applies to integrable and chaotic magnetic fields with local or nonlocal parallel closures. In weakly chaotic fields, the method gives the fractal structure of the devil's staircase radial temperature profile. In fully chaotic fields, the temperature exhibits self-similar spatiotemporal evolution with a stretched-exponential scaling function for local closures and an algebraically decaying one for nonlocal closures. It is shown that, for both closures, the effective radial heat transport is incompatible with the quasilinear diffusion model.
Air and liquid solar heating system with heatpump, VP-SOL

DEFF Research Database (Denmark)

Kristiansen, Finn Harken; Jensen, Søren Østergaard

1998-01-01

For more than a year, measurements have been made on an air/fluid solar heating system with heat pump. The annual thermal performance of the system has been found and compared with simulations carried out by means of the simulation program KVIKSOL.The heat loss of the hot water tank is calculated...... be changed in such a way that the air is drawn through the solar collectors when the air temperature of the solar collectors is e.g. 5 K higher than the open air temperature.It has turned out that under the given conditions the system (compared to the simulations) performs as expected.If the heat pump...... is changed in such a way that it only heats the tank to max. 55ºC the net utilized solar energy of the system can be increased by approximately 30%.All things considered, it is estimated that the net utilized solar energy of the system can be increased by about 40% on condition that the proposed changes...
Opportunity's Surroundings on Sol 1687

Science.gov (United States)

2009-01-01

NASA's Mars Exploration Rover Opportunity used its navigation camera to take the images combined into this 360-degree view of the rover's surroundings on the 1,687th Martian day, or sol, of its surface mission (Oct. 22, 2008). Opportunity had driven 133 meters (436 feet) that sol, crossing sand ripples up to about 10 centimeters (4 inches) tall. The tracks visible in the foreground are in the east-northeast direction. Opportunity's position on Sol 1687 was about 300 meters southwest of Victoria Crater. The rover was beginning a long trek toward a much larger crater, Endeavour, about 12 kilometers (7 miles) to the southeast. This view is presented as a cylindrical projection with geometric seam correction.
Scrape-off layer transport and deposition studies in DIII-D

International Nuclear Information System (INIS)

Groth, M.; Allen, S. L.; Fenstermacher, M. E.; Lasnier, C. J.; Porter, G. D.; Rensink, M. E.; Rognlien, T. D.; Boedo, J. A.; Rudakov, D. L.; Brooks, N. H.; Groebner, R. J.; Leonard, A. W.; West, W. P.; Elder, J. D.; McLean, A. G.; Lisgo, S.; Stangeby, P. C.; Wampler, W. R.; Watkins, J. G.; Whyte, D. G.

2007-01-01

Trace 13 CH 4 injection experiments into the main scrape-off layer (SOL) of low density L-mode and high-density H-mode plasmas have been performed in the DIII-D tokamak [J. L. Luxon, Nucl. Fusion 42, 614 (2002)] to mimic the transport and deposition of carbon arising from a main chamber sputtering source. These experiments indicated entrainment of the injected carbon in plasma flow in the main SOL, and transport toward the inner divertor. Ex situ surface analysis showed enhanced 13 C surface concentration at the corner formed by the divertor floor and the angled target plate of the inner divertor in L-mode; in H-mode high surface concentration was found both at the corner and along the surface bounding the private flux region inboard of the outer strike point. Interpretative modeling was made consistent with these experimental results by imposing a parallel carbon ion flow in the main SOL toward the inner target, and a radial pinch toward the separatrix. Predictive modeling carried out to better understand the underlying plasma transport processes suggests that the deuterium flow in the main SOL is related to the degree of detachment of the inner divertor leg. These simulations show that carbon ions are entrained with the deuteron flow in the main SOL via frictional coupling, but higher charge-state carbon ions may be suspended upstream of the inner divertor X-point region due to balance of the friction force and the ion temperature gradient force
Comparison between stellarator and tokamak divertor transport

International Nuclear Information System (INIS)

Feng, Y.; Lunt, T.; Kobayashi, M.; Reiter, D.

2010-11-01

The paper compares the essential divertor transport features of the poloidal divertor, which is well-developed for tokamaks, and the non-axisymmetric divertors currently investigated on helical devices. It aims at surveying the fundamental similarities and differences in divertor concept and geometry, and their consequences for how the divertor functions. In particular, the importance of various transport terms governing axisymmetric and helical scrape-off-layers (SOLs) is examined, with special attention being paid to energy, momentum and impurity transport. Tokamak and stellarator SOLs are compared by identifying key geometric parameters through which the governing physics can be illustrated by simple models and estimates. More quantitative assessments rely nevertheless on the modeling using EMC3-EIRENE code. Most of the theoretical results are discussed in conjunction with experimental observations. (author)
Analyses of desorbed H2O with temperature programmed desorption technique in sol-gel derived HfO2 thin films

International Nuclear Information System (INIS)

Shimizu, H.; Nemoto, D.; Ikeda, M.; Nishide, T.

2009-01-01

Hafnium oxide (HfO 2 ) is a promising material for the gate insulator in highly miniaturized silicon (Si) ultra-large-scale-integration (ULSI) devices (32 nm and beyond). In the field chemistry, a sol-gel processing has been used to fabricate HfO 2 thin film with the advantages of low cost, relative simplicity, and easy control of the composition of the layers formed. Temperature-programmed desorption (TPD) has been used not only for analyzing adsorbed gases on the surfaces of bulk sol-gel-derived HfO 2 of sol-gel-derived HfO 2 thin film fired at 350, 450, 550 and 700 deg C in sol-gel derived HfO 2 films in air is investigated using TPD, and also the material characterization of HfO 2 thin films is evaluated by X-ray diffraction (XRD) method. The dielectric constant of the films was also estimated using the capacitance-voltage (C-V) method. TPD is essentially a method of analyzing desorped gases from samples heated by infra-red light as a function of temperature under vacuum conditions using a detector of quadruple mass spectroscopy (QMS). Sol-gel-derived HfO 2 films were fabricated on 76-mm-diameter Si(100) wafers as follows. Hafnia sol solutions were prepared by dissolving HfCl 4 in NH 4 OH solution, followed by the of HCOOH. (author)
Exact harmonic solutions to Guyer-Krumhansl-type equation and application to heat transport in thin films

Science.gov (United States)

Zhukovsky, K.; Oskolkov, D.

2018-03-01

A system of hyperbolic-type inhomogeneous differential equations (DE) is considered for non-Fourier heat transfer in thin films. Exact harmonic solutions to Guyer-Krumhansl-type heat equation and to the system of inhomogeneous DE are obtained in Cauchy- and Dirichlet-type conditions. The contribution of the ballistic-type heat transport, of the Cattaneo heat waves and of the Fourier heat diffusion is discussed and compared with each other in various conditions. The application of the study to the ballistic heat transport in thin films is performed. Rapid evolution of the ballistic quasi-temperature component in low-dimensional systems is elucidated and compared with slow evolution of its diffusive counterpart. The effect of the ballistic quasi-temperature component on the evolution of the complete quasi-temperature is explored. In this context, the influence of the Knudsen number and of Cauchy- and Dirichlet-type conditions on the evolution of the temperature distribution is explored. The comparative analysis of the obtained solutions is performed.
Sol-Gel Process for Making Pt-Ru Fuel-Cell Catalysts

Science.gov (United States)

Narayanan, Sekharipuram; Valdez, Thomas; Kumta, Prashant; Kim, Y.

2005-01-01

A sol-gel process has been developed as a superior alternative to a prior process for making platinum-ruthenium alloy catalysts for electro-oxidation of methanol in fuel cells. The starting materials in the prior process are chloride salts of platinum and ruthenium. The process involves multiple steps, is time-consuming, and yields a Pt-Ru product that has relatively low specific surface area and contains some chloride residue. Low specific surface area translates to incomplete utilization of the catalytic activity that might otherwise be available, while chloride residue further reduces catalytic activity ("poisons" the catalyst). In contrast, the sol-gel process involves fewer steps and less time, does not leave chloride residue, and yields a product of greater specific area and, hence, greater catalytic activity. In this sol-gel process (see figure), the starting materials are platinum(II) acetylacetonate [Pt(C5H7O2)2, also denoted Pt-acac] and ruthenium(III) acetylacetonate [Ru(C5H7O2)3, also denoted Ru-acac]. First, Pt-acac and Ru-acac are dissolved in acetone at the desired concentrations (typically, 0.00338 moles of each salt per 100 mL of acetone) at a temperature of 50 C. A solution of 25 percent tetramethylammonium hydroxide [(CH3)4NOH, also denoted TMAH] in methanol is added to the Pt-acac/Ruacac/ acetone solution to act as a high-molecular-weight hydrolyzing agent. The addition of the TMAH counteracts the undesired tendency of Pt-acac and Ru-acac to precipitate as separate phases during the subsequent evaporation of the solvent, thereby helping to yield a desired homogeneous amorphous gel. The solution is stirred for 10 minutes, then the solvent is evaporated until the solution becomes viscous, eventually transforming into a gel. The viscous gel is dried in air at a temperature of 170 C for about 10 hours. The dried gel is crushed to make a powder that is the immediate precursor of the final catalytic product. The precursor powder is converted to the
An Assessment of Transport Property Estimation Methods for Ammonia–Water Mixtures and Their Influence on Heat Exchanger Size

DEFF Research Database (Denmark)

Kærn, Martin Ryhl; Modi, Anish; Jensen, Jonas Kjær

2015-01-01

Transport properties of fluids are indispensable for heat exchanger design. The methods for estimating the transport properties of ammonia–water mixtures are not well established in the literature. The few existent methods are developed from none or limited, sometimes inconsistent experimental...... of ammonia–water mixtures. Firstly, the different methods are introduced and compared at various temperatures and pressures. Secondly, their individual influence on the required heat exchanger size (surface area) is investigated. For this purpose, two case studies related to the use of the Kalina cycle...... the interpolative methods in contrast to the corresponding state methods. Nevertheless, all possible mixture transport property combinations used herein resulted in a heat exchanger size within 4.3 % difference for the flue-gas heat recovery boiler, and within 12.3 % difference for the oil-based boiler....
Relationship between particle and heat transport in JT-60U plasmas with internal transport barrier

International Nuclear Information System (INIS)

Takenaga, Hidenobu; Higashijima, S.; Oyama, N.

2003-01-01

The relationship between particle and heat transport in an internal transport barrier (ITB) has been systematically investigated in reversed shear (RS) and high β p ELMy H-mode plasmas in JT-60U. No helium and carbon accumulation inside the ITB is observed even with ion heat transport reduced to a neoclassical level. On the other hand, the heavy impurity argon is accumulated inside the ITB. The argon density profile estimated from the soft x-ray profile is more peaked, by a factor of 2-4 in the RS plasma and of 1.6 in the high β p mode plasma, than the electron density profile. The helium diffusivity (D He ) and the ion thermal diffusivity (χ i ) are at an anomalous level in the high β p mode plasma, where D He and χ i are higher by a factor of 5-10 than the neoclassical value. In the RS plasma, D He is reduced from the anomalous to the neoclassical level, together with χ i . The carbon and argon density profiles calculated using the transport coefficients reduced to the neoclassical level only in the ITB are more peaked than the measured profiles, even when χ i is reduced to the neoclassical level. Argon exhaust from the inside of the ITB is demonstrated by applying ECH in the high β p mode plasma, where both electron and argon density profiles become flatter. The reduction of the neoclassical inward velocity for argon due to the reduction of density gradient is consistent with the experimental observation. In the RS plasma, the density gradient is not decreased by ECH and argon is not exhausted. These results suggest the importance of density control to suppress heavy impurity accumulation. (author)
Relationship between particle and heat transport in JT-60U plasmas with internal transport barrier

International Nuclear Information System (INIS)

Takenaga, H.; Higashijima, S.; Oyama, N.

2003-01-01

The relationship between particle and heat transport in an internal transport barrier (ITB) has been systematically investigated in reversed shear (RS) and high β p ELMy H-mode plasmas in JT-60U. No helium and carbon accumulation inside the ITB is observed even with ion heat transport reduced to a neoclassical level. On the other hand, the heavy impurity argon is accumulated inside the ITB. The argon density profile estimated from the soft x-ray profile is more peaked, by a factor of 2-4 in the RS plasma and of 1.6 in the high β p mode plasma, than the electron density profile. The helium diffusivity (D He ) and the ion thermal diffusivity (χ i ) are at an anomalous level in the high β p mode plasma, where D He and χ i are higher by a factor of 5-10 than the neoclassical value. In the RS plasma, D He is reduced from the anomalous to the neoclassical level, together with χ i . The carbon and argon density profiles calculated using the transport coefficients reduced to the neoclassical level only in the ITB are more peaked than the measured profiles, even when χ i is reduced to the neoclassical level. Argon exhaust from the inside of the ITB is demonstrated by applying ECH in the high β p mode plasma, where both electron and argon density profiles become flatter. The reduction of the neoclassical inward velocity for argon due to the reduction of density gradient is consistent with the experimental observation. In the RS plasma, the density gradient is not decreased by ECH and argon is not exhausted. These results suggest the importance of density gradient control to suppress heavy impurity accumulation. (author)
Polymeric-silica-based sols for membrane modification applications: sol-gel synthesis and characterization with SAXS

NARCIS (Netherlands)

de Lange, Rob; de Lange, R.S.A.; Hekkink, J.H.A.; Hekkink, J.H.A.; Keizer, Klaas; Burggraaf, Anthonie; Burggraaf, A.J.

1995-01-01

Polymeric SiO2 and binary SiO2/TiO2, SiO2/ZrO2 and SiO2/Al2O3 sols, for ceramic membrane modification applications, have been prepared by acid-catalyzed hydrolysis and condensation of alkoxides in alcohol. The sols were characterized with small angle X-ray scattering, using synchrotron radiation.
Heat pulse analysis in JET and relation to local energy transport models

International Nuclear Information System (INIS)

Haas, J.C.M. de; Lopes Cardozo, N.J.; Han, W.; Sack, C.; Taroni, A.

1989-01-01

The evolution of a perturbation T e of the electron temperature depends on the linearised expression of the heat flux q e and may be not simply related to the local value of the electron heat conductivity χ e . It is possible that local heat transport models predicting similar temperature profiles and global energy confinement properties, imply a different propagation of heat pulses. We investigate here this possibility for the case of two models developed at JET. We also present results obtained at JET on a set of discharges covering the range of currents from 2 to 5 MA. Only L-modes, limiter discharges are considered here. Experimental results on the scaling of χ HP , the value of χ e related to heat pulse propagation, are compared with those of χ HP derived from the models. (author) 7 refs., 2 figs., 2 tabs
Highly concentrated zinc oxide nanocrystals sol with strong blue emission

International Nuclear Information System (INIS)

Vafaee, M.; Sasani Ghamsari, M.; Radiman, S.

2011-01-01

Highly concentrated ZnO sol was synthesized by an improved sol-gel method. Water was used as a modifier to control the sol-gel reaction and provide a way to increase the sol concentration. Concentration of ZnO in the prepared sol is higher than from other methods. Optical absorption and photoluminescence were used to investigate optical properties of the prepared sol. FTIR test was performed to study the influence of water on the compounds of as-prepared sol. The size and morphology of ZnO nanoparticles have been studied by HRTEM. The prepared colloidal ZnO nanocrystals have narrow size distribution (5-8 nm) and showed strong blue emission. The prepared sol has enough potential for optoelectronic applications. - Research highlights: → Novel sol-gel route has been employed to prepare highly concentrated ZnO colloidal nanocrystals. → Water has been used to control the sources of emission in synthesized material. → A strong blue luminescent material has been obtained.
Plasma confinement modification and convective transport suppression in the scrape-off layer using additional gas puffing in the STOR-M tokamak

International Nuclear Information System (INIS)

Dreval, M; Hubeny, M; Ding, Y; Onchi, T; Liu, Y; Hthu, K; Elgriw, S; Xiao, C; Hirose, A

2013-01-01

The influence of short gas puffing (GP) pulses on the scrape-off layer (SOL) transport is studied. Similar responses of ion saturation current and floating potential measured near the GP injection valve and in the 90° toroidally separated cross-section suggest that the GP influence on the SOL region should be global. A drop in plasma temperature and a decrease in the rotational velocity of the plasma are observed in the SOL region immediately after the GP pulse; however, an unexpected increase in electron and ion temperatures is observed in the second stage of the plasma response. The decrease in floating potential fluctuations indicates that the turbulent transport is dumped immediately after the GP pulse. The GP-induced modification of turbulence properties in the SOL points to a convective transport suppression in the STOR-M tokamak. A substantial decrease in the skewness and kurtosis of ion saturation current fluctuations is observed in the SOL region resulting in the probability distribution function (PDF) getting closer to the Gaussian distribution. The plasma potential reduction, the change in plasma rotation and the suppression of turbulent transport in the SOL region indicate that the plasma confinement is modified after the GP injection. Some features of the H-mode-like confinement in the plasma bulk also accompany the SOL observations after application of the additional sharp GP pulse. (paper)
Diamond nucleation by carbon transport from buried nanodiamond TiO.sub.2./sub. sol-gel composites

Czech Academy of Sciences Publication Activity Database

Daenen, M.; Zhang, L.; Erni, R.; Williams, O.A.; Hardy, A.; Van Bael, M.K.; Wagner, P.; Haenen, K.; Nesládek, Miloš; van Tendeloo, G.

2009-01-01

Roč. 21, č. 6 (2009), s. 670-673 ISSN 0935-9648 Institutional research plan: CEZ:AV0Z10100520 Keywords : diamond nucleation * nanodiamond * TiO 2 sol-gel omposites Subject RIV: BM - Solid Matter Physics ; Magnetism Impact factor: 8.379, year: 2009
The Sizing and Optimization Language, (SOL): Computer language for design problems

Science.gov (United States)

Lucas, Stephen H.; Scotti, Stephen J.

1988-01-01

The Sizing and Optimization Language, (SOL), a new high level, special purpose computer language was developed to expedite application of numerical optimization to design problems and to make the process less error prone. SOL utilizes the ADS optimization software and provides a clear, concise syntax for describing an optimization problem, the OPTIMIZE description, which closely parallels the mathematical description of the problem. SOL offers language statements which can be used to model a design mathematically, with subroutines or code logic, and with existing FORTRAN routines. In addition, SOL provides error checking and clear output of the optimization results. Because of these language features, SOL is best suited to model and optimize a design concept when the model consits of mathematical expressions written in SOL. For such cases, SOL's unique syntax and error checking can be fully utilized. SOL is presently available for DEC VAX/VMS systems. A SOL package is available which includes the SOL compiler, runtime library routines, and a SOL reference manual.

Heat transport and afterheat removal for gas cooled reactors under accident conditions

International Nuclear Information System (INIS)

2001-01-01

The Co-ordinated Research Project (CRP) on Heat Transport and Afterheat Removal for Gas Cooled Reactors Under Accident Conditions was organized within the framework of the International Working Group on Gas Cooled Reactors (IWGGCR). This International Working Group serves as a forum for exchange of information on national programmes, provides advice to the IAEA on international co-operative activities in advanced technologies of gas cooled reactors (GCRs) and supports the conduct of these activities. Advanced GCR designs currently being developed are predicted to achieve a high degree of safety through reliance on inherent safety features. Such design features should permit the technical demonstration of exceptional public protection with significantly reduced emergency planning requirements. For advanced GCRs, this predicted high degree of safety largely derives from the ability of the ceramic coated fuel particles to retain the fission products under normal and accident conditions, the safe neutron physics behaviour of the core, the chemical stability of the core and the ability of the design to dissipate decay heat by natural heat transport mechanisms without reaching excessive temperatures. Prior to licensing and commercial deployment of advanced GCRs, these features must first be demonstrated under experimental conditions representing realistic reactor conditions, and the methods used to predict the performance of the fuel and reactor must be validated against these experimental data. Within this CRP, the participants addressed the inherent mechanisms for removal of decay heat from GCRs under accident conditions. The objective of this CRP was to establish sufficient experimental data at realistic conditions and validated analytical tools to confirm the predicted safe thermal response of advance gas cooled reactors during accidents. The scope includes experimental and analytical investigations of heat transport by natural convection conduction and thermal
Analysis of simulation methodology for calculation of the heat of transport for vacancy thermodiffusion

Energy Technology Data Exchange (ETDEWEB)

Tucker, William C.; Schelling, Patrick K., E-mail: patrick.schelling@ucf.edu [Advanced Material Processing and Analysis Center and Department of Physics, University of Central Florida, 4000 Central Florida Blvd., Orlando, Florida 32816 (United States)

2014-07-14

Computation of the heat of transport Q{sub a}{sup *} in monatomic crystalline solids is investigated using the methodology first developed by Gillan [J. Phys. C: Solid State Phys. 11, 4469 (1978)] and further developed by Grout and coworkers [Philos. Mag. Lett. 74, 217 (1996)], referred to as the Grout-Gillan method. In the case of pair potentials, the hopping of a vacancy results in a heat wave that persists for up to 10 ps, consistent with previous studies. This leads to generally positive values for Q{sub a}{sup *} which can be quite large and are strongly dependent on the specific details of the pair potential. By contrast, when the interactions are described using the embedded atom model, there is no evidence of a heat wave, and Q{sub a}{sup *} is found to be negative. This demonstrates that the dynamics of vacancy hopping depends strongly on the details of the empirical potential. However, the results obtained here are in strong disagreement with experiment. Arguments are presented which demonstrate that there is a fundamental error made in the Grout-Gillan method due to the fact that the ensemble of states only includes successful atom hops and hence does not represent an equilibrium ensemble. This places the interpretation of the quantity computed in the Grout-Gillan method as the heat of transport in doubt. It is demonstrated that trajectories which do not yield hopping events are nevertheless relevant to computation of the heat of transport Q{sub a}{sup *}.
Modified silica sol coatings for surface enhancement of leather.

Science.gov (United States)

Mahltig, Boris; Vossebein, Lutz; Ehrmann, Andrea; Cheval, Nicolas; Fahmi, Amir

2012-06-01

The presented study reports on differently modified silica sols for coating applications on leather. Silica sols are prepared by acidic hydrolysis of tetraethoxysilane and modified by silane compounds with fluorinated and non-fluorinated alkylgroups. In contrast to many earlier investigations regarding sol-gel applications on leather, no acrylic resin is used together with the silica sols when applying on leather. The modified silica particles are supposed to aggregate after application, forming thus a modified silica coating on the leather substrate. Scanning electron microscopy investigation shows that the applied silica coatings do not fill up or close the pores of the leather substrate. However, even if the pores of the leather are not sealed by this sol-gel coating, an improvement of the water repellent and oil repellent properties of the leather substrates are observed. These improved properties of leather by application of modified silica sols can provide the opportunity to develop sol-gel products for leather materials present in daily life.
Application of the docking program SOL for CSAR benchmark.

Science.gov (United States)

Sulimov, Alexey V; Kutov, Danil C; Oferkin, Igor V; Katkova, Ekaterina V; Sulimov, Vladimir B

2013-08-26

This paper is devoted to results obtained by the docking program SOL and the post-processing program DISCORE at the CSAR benchmark. SOL and DISCORE programs are described. SOL is the original docking program developed on the basis of the genetic algorithm, MMFF94 force field, rigid protein, precalculated energy grid including desolvation in the frame of simplified GB model, vdW, and electrostatic interactions and taking into account the ligand internal strain energy. An important SOL feature is the single- or multi-processor performance for up to hundreds of CPUs. DISCORE improves the binding energy scoring by the local energy optimization of the ligand docked pose and a simple linear regression on the base of available experimental data. The docking program SOL has demonstrated a good ability for correct ligand positioning in the active sites of the tested proteins in most cases of CSAR exercises. SOL and DISCORE have not demonstrated very exciting results on the protein-ligand binding free energy estimation. Nevertheless, for some target proteins, SOL and DISCORE were among the first in prediction of inhibition activity. Ways to improve SOL and DISCORE are discussed.
Poly(aniline) nanowires in sol-gel coated ITO: A pH-responsive substrate for planar supported lipid bilayers

Science.gov (United States)

Ge, Chenhao; Orosz, Kristina S.; Armstrong, Neal R.; Saavedra, S. Scott

2011-01-01

Facilitated ion transport across an artificial lipid bilayer coupled to a solid substrate is a function common to several types of bioelectronic devices based on supported membranes, including biomimetic fuel cells and ion channel biosensors. Described here is fabrication of a pH-sensitive transducer composed of a porous sol-gel layer derivatized with poly(aniline) (PANI) nanowires grown from an underlying planar indium-tin oxide (ITO) electrode. The upper sol-gel surface is hydrophilic, smooth, and compatible with deposition of a planar supported lipid bilayer (PSLB) formed via vesicle fusion. Conducting tip AFM was used to show that the PANI wires are connected to the ITO, which convert this electrode into a potentiometric pH sensor. The response to changes in the pH of the buffer contacting the PANI nanowire/sol-gel/ITO electrode is blocked by the very low ion permeability of the overlying, fluid PSLB. The feasibility of using this assembly to monitor facilitated proton transport across the PSLB was demonstrated by doping the membrane with lipophilic ionophores that respond to a transmembrane pH gradient, which produced an apparent proton permeability several orders of magnitude greater than values measured for undoped lipid bilayers. PMID:21707069
Sol-gel processing with inorganic metal salt precursors

Science.gov (United States)

Hu, Zhong-Cheng

2004-10-19

Methods for sol-gel processing that generally involve mixing together an inorganic metal salt, water, and a water miscible alcohol or other organic solvent, at room temperature with a macromolecular dispersant material, such as hydroxypropyl cellulose (HPC) added. The resulting homogenous solution is incubated at a desired temperature and time to result in a desired product. The methods enable production of high quality sols and gels at lower temperatures than standard methods. The methods enable production of nanosize sols from inorganic metal salts. The methods offer sol-gel processing from inorganic metal salts.
Transient heat transport studies in JET conventional and advanced tokamak plasmas

International Nuclear Information System (INIS)

Mantica, P.; Coffey, I.; Dux, R.

2003-01-01

Transient transport studies are a valuable complement to steady-state analysis for the understanding of transport mechanisms and the validation of physics-based transport models. This paper presents results from transient heat transport experiments in JET and their modelling. Edge cold pulses and modulation of ICRH (in mode conversion scheme) have been used to provide detectable electron and ion temperature perturbations. The experiments have been performed in conventional L-mode plasmas or in Advanced Tokamak regimes, in the presence of an Internal Transport Barrier (ITB). In conventional plasmas, the issues of stiffness and non-locality have been addressed. Cold pulse propagation in ITB plasmas has provided useful insight into the physics of ITB formation. The use of edge perturbations for ITB triggering has been explored. Modelling of the experimental results has been performed using both empirical models and physics-based models. Results of cold pulse experiments in ITBs have also been compared with turbulence simulations. (author)
Acoustically enhanced heat transport

Energy Technology Data Exchange (ETDEWEB)

Ang, Kar M.; Hung, Yew Mun; Tan, Ming K., E-mail: tan.ming.kwang@monash.edu [School of Engineering, Monash University Malaysia, 47500 Bandar Sunway, Selangor (Malaysia); Yeo, Leslie Y. [Micro/Nanophysics Research Laboratory, RMIT University, Melbourne, VIC 3001 (Australia); Friend, James R. [Department of Mechanical and Aerospace Engineering, University of California, San Diego, California 92093 (United States)

2016-01-15

We investigate the enhancement of heat transfer in the nucleate boiling regime by inducing high frequency acoustic waves (f ∼ 10{sup 6} Hz) on the heated surface. In the experiments, liquid droplets (deionized water) are dispensed directly onto a heated, vibrating substrate. At lower vibration amplitudes (ξ{sub s} ∼ 10{sup −9} m), the improved heat transfer is mainly due to the detachment of vapor bubbles from the heated surface and the induced thermal mixing. Upon increasing the vibration amplitude (ξ{sub s} ∼ 10{sup −8} m), the heat transfer becomes more substantial due to the rapid bursting of vapor bubbles happening at the liquid-air interface as a consequence of capillary waves travelling in the thin liquid film between the vapor bubble and the air. Further increases then lead to rapid atomization that continues to enhance the heat transfer. An acoustic wave displacement amplitude on the order of 10{sup −8} m with 10{sup 6} Hz order frequencies is observed to produce an improvement of up to 50% reduction in the surface temperature over the case without acoustic excitation.
Heat and momentum transport scalings in vertical convection

Science.gov (United States)

Shishkina, Olga

2016-11-01

For vertical convection, where a fluid is confined between two differently heated isothermal vertical walls, we investigate the heat and momentum transport, which are measured, respectively, by the Nusselt number Nu and the Reynolds number Re . For laminar vertical convection we derive analytically the dependence of Re and Nu on the Rayleigh number Ra and the Prandtl number Pr from our boundary layer equations and find two different scaling regimes: Nu Pr 1 / 4 Ra 1 / 4 , Re Pr - 1 / 2 Ra 1 / 2 for Pr > 1 . Direct numerical simulations for Ra from 105 to 1010 and Pr from 0.01 to 30 are in excellent ageement with our theoretical findings and show that the transition between the regimes takes place for Pr around 0.1. We summarize the results from and present new theoretical and numerical results for transitional and turbulent vertical convection. The work is supported by the Deutsche Forschungsgemeinschaft (DFG) under the Grant Sh 405/4 - Heisenberg fellowship.
Thermal relaxation and heat transport in spin ice Dy{sub 2}Ti{sub 2}O{sub 7}

Energy Technology Data Exchange (ETDEWEB)

Klemke, Bastian; Meissner, M.; Tennant, D.A. [Helmholtz-Zentrum Berlin (Germany); Technische Universitaet Berlin (Germany); Strehlow, P. [Technische Universitaet Berlin (Germany); Physikalisch Technische Bundesanstalt, Institut Berlin (Germany); Kiefer, K. [Helmholtz-Zentrum Berlin (Germany); Grigera, S.A. [School of Physics and Astronomy, St. Andrews (United Kingdom); Instituto de Fisica de Liquidos y Sistemas Biologicos, CONICET, UNLP, La Plata (Argentina)

2011-07-01

The thermal properties of single crystalline Dy{sub 2}Ti{sub 2}O{sub 7} have been studied at temperature below 30 K and magnetic fields applied along [110] direction up to 1.5 T. Based on a thermodynamic field theory (TFT) various heat relaxation and thermal transport measurements were analysed. So we were able to present not only the heat capacity of Dy{sub 2}Ti{sub 2}O{sub 7}, but also for the first time the different contributions of the magnetic excitations and their corresponding relaxation times in the spin ice phase. In addition, the thermal conductivity and the shortest relaxation time were determined by thermodynamic analysis of steady state heat transport measurements. Finally, we were able to reproduce the temperature profiles recorded in heat pulse experiments on the basis of TFT using the previously determined heat capacity and thermal conductivity data without additional parameters. Thus, TFT has been proved to be thermodynamically consistent in describing three thermal transport experiments on different time scales. The observed temperature and field dependencies of heat capacity contributions and relaxation times indicate the magnetic excitations in the spin ice Dy{sub 2}Ti{sub 2}O{sub 7} as thermally activated monopole-antimonopole defects.
Electrophoretic deposition of sol-gel-derived ceramic coatings

International Nuclear Information System (INIS)

Zhang, Y.; Crooks, R.M.

1992-01-01

In this paper the physical, optical, and chemical characteristics of electrophoretically and dip-coated sol-gel ceramic films are compared. The results indicate that electrophoresis may allow a higher level of control over the chemistry and structure of ceramic coatings than dip-coating techniques. For example, controlled-thickness sol-gel coatings can be prepared by adjusting the deposition time or voltage. Additionally, electrophoretic coatings can be prepared in a four-component alumino-borosilicate sol display interesting optical characteristics. For example, the ellipsometrically-measured refractive indices of electrophoretic coatings are higher than the refractive indices of dip-coated films cast from identical sols, and they are also higher than any of the individual sol components. This result suggests that there are physical and/or chemical differences between films prepared by dip-coating and electrophoresis
Block Gas Sol Unit in Haderslev

DEFF Research Database (Denmark)

Vejen, Niels Kristian

2000-01-01

Investigation of a SDHW system based on a Block Gas Sol Unit from Baxi A/S installed by a consumer i Haderslev, Denmark.......Investigation of a SDHW system based on a Block Gas Sol Unit from Baxi A/S installed by a consumer i Haderslev, Denmark....
Two-phase optimizing approach to design assessments of long distance heat transportation for CHP systems

International Nuclear Information System (INIS)

Hirsch, Piotr; Duzinkiewicz, Kazimierz; Grochowski, Michał; Piotrowski, Robert

2016-01-01

Highlights: • New method for long distance heat transportation system effectivity evaluation. • Decision model formulation which reflects time and spatial structure of the problem. • Multi-criteria and complex approach to solving the decision-making problem. • Solver based on simulation-optimization approach with two-phase optimization method. • Sensitivity analysis of the optimization procedure elements. - Abstract: Cogeneration or Combined Heat and Power (CHP) for power plants is a method of putting to use waste heat which would be otherwise released to the environment. This allows the increase in thermodynamic efficiency of the plant and can be a source of environmental friendly heat for District Heating (DH). In the paper CHP for Nuclear Power Plant (NPP) is analyzed with the focus on heat transportation. A method for effectivity and feasibility evaluation of the long distance, high power Heat Transportation System (HTS) between the NPP and the DH network is proposed. As a part of the method the multi-criteria decision-making problem, having the structure of the mathematical programming problem, for optimized selection of design and operating parameters of the HTS is formulated. The constraints for this problem include a static model of HTS, that allows considerations of system lifetime, time variability and spatial topology. Thereby variation of annual heat demand within the DH area, variability of ground temperature, insulation and pipe aging and/or terrain elevation profile can be taken into account in the decision-making process. The HTS construction costs, pumping power, and heat losses are considered as objective functions. In general, the analyzed optimization problem is multi-criteria, hybrid and nonlinear. The two-phase optimization based on optimization-simulation framework is proposed to solve the decision-making problem. The solver introduces a number of assumptions concerning the optimization process. Methods for problem decomposition
New Record Five-Wheel Drive, Spirit's Sol 1856

Science.gov (United States)

2009-01-01

NASA's Mars Exploration Rover Spirit used its navigation camera to take the images that have been combined into this stereo, 180-degree view of the rover's surroundings during the 1,856th Martian day, or sol, of Spirit's surface mission (March 23, 2009). The center of the view is toward the west-southwest. The rover had driven 25.82 meters (84.7 feet) west-northwestward earlier on Sol 1856. This is the longest drive on Mars so far by a rover using only five wheels. Spirit lost the use of its right-front wheel in March 2006. Before Sol 1856, the farthest Spirit had covered in a single sol's five-wheel drive was 24.83 meters (81.5 feet), on Sol 1363 (Nov. 3, 2007). The Sol 1856 drive made progress on a route planned for taking Spirit around the western side of the low plateau called 'Home Plate.' A portion of the northwestern edge of Home Plate is prominent in the left quarter of this image, toward the south. This view is presented as a cylindrical projection with geometric seam correction.
Identification, expression, and immuno-reactivity of Sol i 2 & Sol i 4 venom proteins of queen red imported fire ants, Solenopsis invicta Buren (Hymenoptera: Formicidae).

Science.gov (United States)

Lockwood, Stephanie A; Haghipour-Peasley, Jilla; Hoffman, Donald R; Deslippe, Richard J

2012-10-01

We report on two low-molecular weight proteins that are stored in the venom of queen red imported fire ants (Solenopsis invicta). Translated amino acid sequences identified one protein to have 74.8% identity with the Sol i 2w worker allergen, and the other protein was found to have 96/97% identity with Sol i 4.01w/4.02w worker allergens. Both Sol i 2 and Sol i 4 queen and worker proteins were expressed using pEXP1-DEST vector in SHuffle™ T7 Express lysY Escherichia coli. Proteins were expressed at significant concentrations, as opposed to the μg/ml amounts by our previous expression methods, enabling further study of these proteins. Sol i 2q protein bound weakly to human IgE, sera pooled from allergic patients, whereas Sol i 2w, Sol i 4.01w, and Sol i 4q proteins bound strongly. Despite Sol i 2w and Sol i 2q proteins having 74.8% identity, the queen protein is less immuno-reactive than the worker allergen. This finding is consistent with allergic individuals being less sensitive to queen than worker venom. Copyright © 2012 Elsevier Ltd. All rights reserved.
Parallel heat transport in integrable and chaotic magnetic fields

Energy Technology Data Exchange (ETDEWEB)

Castillo-Negrete, D. del; Chacon, L. [Oak Ridge National Laboratory, Oak Ridge, Tennessee 37831-8071 (United States)

2012-05-15

The study of transport in magnetized plasmas is a problem of fundamental interest in controlled fusion, space plasmas, and astrophysics research. Three issues make this problem particularly challenging: (i) The extreme anisotropy between the parallel (i.e., along the magnetic field), {chi}{sub ||} , and the perpendicular, {chi}{sub Up-Tack }, conductivities ({chi}{sub ||} /{chi}{sub Up-Tack} may exceed 10{sup 10} in fusion plasmas); (ii) Nonlocal parallel transport in the limit of small collisionality; and (iii) Magnetic field lines chaos which in general complicates (and may preclude) the construction of magnetic field line coordinates. Motivated by these issues, we present a Lagrangian Green's function method to solve the local and non-local parallel transport equation applicable to integrable and chaotic magnetic fields in arbitrary geometry. The method avoids by construction the numerical pollution issues of grid-based algorithms. The potential of the approach is demonstrated with nontrivial applications to integrable (magnetic island), weakly chaotic (Devil's staircase), and fully chaotic magnetic field configurations. For the latter, numerical solutions of the parallel heat transport equation show that the effective radial transport, with local and non-local parallel closures, is non-diffusive, thus casting doubts on the applicability of quasilinear diffusion descriptions. General conditions for the existence of non-diffusive, multivalued flux-gradient relations in the temperature evolution are derived.
Control size of silver nanoparticles in sol-gel glasses

Science.gov (United States)

Renteria, Victor M.; Celis, Antonio C.; Garcia-Macedo, Jorge A.

2000-10-01

By the sol-gel processing, silver ions in presence of stabilizing function (3-thiocyanatopropyl)triethoxysilane are reduced by heating gels at 180 C for several times in air atmosphere. The spectroscopic Uv-Vis observations, confirm silver nanoparticles presence with peak maximum around 350 nm. The optical properties of the metallic particles are observed at room temperature as function of time, and the absorption spectra practically do not change, which indicated they are trapped and stabilized within the fine porous silica cage. Mie theory calculations, considering the mean free path effect of the conduction electrons, are compatible with experimental spectra, indicating homogeneity in size and form of the metallic nanoparticles. Smithard correlation curve, between half width height (W1/2) of the optical absorption and the particle diameter 2r, predict silver particles size between 4 and 10 nm, during composite heating. Activation energy was measured and compared with previous data on similar systems and the probable reduction process are discussed.
Fluid simulations of ∇Te-driven turbulence and transport in boundary plasmas

International Nuclear Information System (INIS)

Xu, X.Q.

1992-01-01

It is clear that the edge plasma plays a crucial role in global tokamak confinement. This paper is a report on simulations of a new drift wave type instability driven by the electron temperature gradient in tokamak scrapeoff-layers (SOL). A 2d fluid code has been developed in order to explore the anomalous transport in the boundary plasmas. The simulation consists of a set of fluid equations for the vorticity ∇ perpendicular 2 φ, the electron density n c and the temperature T c in a shearless plasma slab confined by a uniform, straight magnetic field B z with two divertor (or limiter) plates intercepting the magnetic field. The model has two regions separated by a magnetic separatrix: in the edge region inside the separatrix, the model is periodic along the magnetic field while in the SOL region outside the separatrix, the magnetic field is taken to be of finite length with model boundary conditions at diverter plates. The simulation results show that the observed linear instability agrees well with theory, and that a saturated state of turbulence is reached. In saturated turbulence, clear evidence of the expected long-wavelength mode penetration into the edge is seen, an inverse cascade of wave energy is observed. The simulation results also show that amplitudes of potential and the electron temperature fluctuations are somewhat above and the heat flux are somewhat below those of the simplest mixing-length estimates, and furthermore the large-scale radial structures of fluctuation quantities indicate that the cross-field transport is not diffusive. After saturation, the electron density and temperature profiles are flattened. A self-consistent simulation to determine the microturbulent SOL electron temperature profile has been done, the results of which reasonably agree with the experimental measurements
Applications of sol gel ceramic coatings

International Nuclear Information System (INIS)

Barrow, D.

1996-01-01

The sol gel method is a chemical technique in which polycrystalline ceramic films are fabricated from a solution of organometallic precursors. The technique is attractive for many industrial applications because it is a simple (films are processed in air), flexible (can be used to coat complex geometries) and cost effective (does not require expensive equipment) process. In addition, dense, high quality coatings can be achieved at much lower temperatures than is generally required for sintering bulk ceramics. In this paper the conventional sol gel method and the new datec process are reviewed and potential applications of sol gel coatings in automotive, aerospace, petrochemical, nuclear and electronic industries are discussed. (orig.)
Methylene blue degradation by NaTaO3 sol-gel doped with Sm and La

International Nuclear Information System (INIS)

Torres-Martinez, Leticia M.; Cruz-Lopez, Arquimedes; Juarez-Ramirez, Isaias; Meza-de la Rosa, Ma. Elena

2009-01-01

In this work, NaTaO 3 compounds doped with 1 M% of La and Sm, were prepared by the sol-gel (SG) method and solid state (SS) reaction; and tested as photocatalysts on the degradation of methylene blue (MB) under UV light. The structural characterization by X-ray powder diffraction revealed that the crystallization of the NaTaO 3 phase prepared by the sol-gel method started at 600 deg. C, reaching maximum crystallization at 800 deg. C. It was determined that the presence of Sm and La retard the crystallization of the NaTaO 3 phase. On the other hand, the compounds synthesized in this work showed particle sizes in the nanometric scale, as it was observed by scanning electron microscopy (SEM). The specific surface area of the compounds synthesized by the sol-gel method, showed values 4 times higher than those obtained by the solid state reaction, favoring their functional and photocatalytic performance in the methylene blue degradation. In addition, the best photocatalytic performance was shown by the NaTaO 3 doped with Sm and heated at 600 deg. C, having a half-life time of 65 min.

Magnetic flux tubes and transport of heat in the convection zone of the sun

International Nuclear Information System (INIS)

Spruit, H.C.

1977-01-01

This thesis consists of five papers dealing with transport of heat in the solar convection zone on the one hand, and with the structure of magnetic flux tubes in the top of the convection zone on the other hand. These subjects are interrelated. For example, the heat flow in the convection zone is disturbed by the presence of magnetic flux tubes, while exchange of heat between a flux tube and the convection zone is important for the energy balance of such a tube. A major part of this thesis deals with the structure of small magnetic flux tubes. Such small tubes (diameters less than about 2'') carry most of the flux appearing at the solar surface. An attempt is made to construct models of the surface layers of such small tubes in sufficient detail to make a comparison with observations possible. Underlying these model calculations is the assumption that the magnetic elements at the solar surface are flux tubes in a roughly static equilibrium. The structure of such tubes is governed by their pressure equilibrium, exchange of heat with the surroundings, and transport of heat by some modified form of convection along the tube. The tube models calculated are compared with observations
Production of porous titanate microspheres by spray-drying of sols

International Nuclear Information System (INIS)

Sizgek, E.; Bartlett, J.R.; Woolfrey, J.L.

1992-01-01

Porous, multi-component titanate microspheres (20 to 50 μm in diameter) have been produced on a 10 kg scale by spray-drying a precursor sol containing titania, zirconia and alumina, and calcining the resulting powders at 723 K. The mixed TiO 2 /ZrO 2 sols were produced by hydrolysing tetraisopropyltitanate and peptising the hydrolysate slurry with zirconyl nitrate solution. TiO 2 /ZrO 2 sols with oxide concentrations in excess of 900 g dm -3 were produced. These sols were subsequently mixed with dispersible δ-Al 2 O 3 to produce well-dispersed TiO 2 /ZrO 2 /Al 2 O 3 (TZA) sols. The rheology and degree of aggregation of the multi-component sols were controlled by the addition of Al(NO 3 ) 3 solution. At relatively low electrolyte concentrations, the sols exhibited Newtonian behaviour, and the viscosity increased with increasing addition of electrolyte. However, at higher electrolyte concentrations, the colloidal dispersions exhibited shear-thinning behaviour. Hollow spheres were produced by spray-drying well-dispersed sols. In contrast, 'solid' spheres were produced by using dilute Al(NO 3 ) 3 to produce partially-aggregated TZA sols, prior to spray-drying. Calcined microspheres produced from partially-aggregated sols had total porosities of ∼ 50 %, with average pore diameters of ∼ 8 nm. These particles exhibited a high sorption capacity for simulated High Level Nuclear Waste
Currents and fluctuations of quantum heat transport in harmonic chains

International Nuclear Information System (INIS)

Motz, T; Ankerhold, J; Stockburger, J T

2017-01-01

Heat transport in open quantum systems is particularly susceptible to the modeling of system–reservoir interactions. It thus requires us to consistently treat the coupling between a quantum system and its environment. While perturbative approaches are successfully used in fields like quantum optics and quantum information, they reveal deficiencies—typically in the context of thermodynamics, when it is essential to respect additional criteria such as fluctuation-dissipation theorems. We use a non-perturbative approach for quantum dissipative dynamics based on a stochastic Liouville–von Neumann equation to provide a very general and extremely efficient formalism for heat currents and their correlations in open harmonic chains. Specific results are derived not only for first- but also for second-order moments, which requires us to account for both real and imaginary parts of bath–bath correlation functions. Spatiotemporal patterns are compared with weak coupling calculations. The regime of stronger system–reservoir couplings gives rise to an intimate interplay between reservoir fluctuations and heat transfer far from equilibrium. (paper)
Digging Movie from Phoenix's Sol 18

Science.gov (United States)

2008-01-01

The Surface Stereo Imager on NASA's Phoenix Mars Lander recorded the images combined into this movie of the lander's Robotic Arm enlarging and combining the two trenches informally named 'Dodo' (left) and 'Goldilocks.' The 21 images in this sequence were taken over a period of about 2 hours during Phoenix's Sol 18 (June 13, 2008), or the 18th Martian day since landing. The main purpose of the Sol 18 dig was to dig deeper for learning the depth of a hard underlying layer. A bright layer, possibly ice, was increasingly exposed as the digging progressed. Further digging and scraping in the combined Dodo-Goldilocks trench was planned for subsequent sols. The combined trench is about 20 centimeters (about 8 inches) wide. The depth at the end of the Sol 18 digging is 5 to 6 centimeters (about 2 inches). The Goldilocks trench was the source of soil samples 'Baby Bear' and 'Mama Bear,' which were collected on earlier sols and delivered to instruments on the lander deck. The Dodo trench was originally dug for practice in collecting and depositing soil samples. The Phoenix Mission is led by the University of Arizona, Tucson, on behalf of NASA. Project management of the mission is by NASA's Jet Propulsion Laboratory, Pasadena, Calif. Spacecraft development is by Lockheed Martin Space Systems, Denver.
Coupling between particle and heat transport during power modulation experiments in Tore Supra

International Nuclear Information System (INIS)

Zou, X.L.; Giruzzi, G.; Artaud, J.F.; Bouquey, F.; Bremond, S.; Clary, J.; Darbos, C.; Eury, S.P.; Lennholm, M.; Magne, R.; Segui, J.L.

2004-01-01

Power modulations are a powerful tool often used to investigate heat transport processes in tokamaks. In some situations, this could also be an interesting method for the investigation of the particle transport due to the anomalous pinch. Low frequency (∼ 1 Hz) power modulation experiments, using both electron cyclotron resonance heating (ECRH) and ion cyclotron resonance heating (ICRH), have been performed in the Tore Supra tokamak. Strong coupling has been observed between the temperature and density modulations during the low frequency ECRH and ICRH modulation experiments. It has been shown that mechanisms as outgassing, Ware pinch effect, curvature driven pinch are not likely to be responsible for this density modulation. Because of its dependence on temperature or temperature gradient, the thermodiffusion is a serious candidate to be the driving source for this density modulation. This analysis shows that low frequency power modulation experiments have a great potential for the investigation of the anomalous particle pinch in tokamaks. Future plans will include the use of more precise density profile measurements using X-mode reflectometry
Coupling between particle and heat transport during power modulation experiments in Tore Supra

Energy Technology Data Exchange (ETDEWEB)

Zou, X.L.; Giruzzi, G.; Artaud, J.F.; Bouquey, F.; Bremond, S.; Clary, J.; Darbos, C.; Eury, S.P.; Lennholm, M.; Magne, R.; Segui, J.L

2004-07-01

Power modulations are a powerful tool often used to investigate heat transport processes in tokamaks. In some situations, this could also be an interesting method for the investigation of the particle transport due to the anomalous pinch. Low frequency ({approx} 1 Hz) power modulation experiments, using both electron cyclotron resonance heating (ECRH) and ion cyclotron resonance heating (ICRH), have been performed in the Tore Supra tokamak. Strong coupling has been observed between the temperature and density modulations during the low frequency ECRH and ICRH modulation experiments. It has been shown that mechanisms as outgassing, Ware pinch effect, curvature driven pinch are not likely to be responsible for this density modulation. Because of its dependence on temperature or temperature gradient, the thermodiffusion is a serious candidate to be the driving source for this density modulation. This analysis shows that low frequency power modulation experiments have a great potential for the investigation of the anomalous particle pinch in tokamaks. Future plans will include the use of more precise density profile measurements using X-mode reflectometry.
Sol-gel synthesis of hydroxyapatite

International Nuclear Information System (INIS)

Zupanski, M.D.; Lucena, M.P.P.; Bergmann, C.P.

2010-01-01

Hydroxyapatite (HAp) has been established as the calcium phosphate based compound with most applications in the biological field. Among the numerous techniques for synthesis of HAp, the sol-gel processing route affords great control over purity and formed phases using low processing temperatures. In addition, the sol-gel approach offers an option for homogeneous HAp coating on metal substrates, as well as the ability to generate nanocrystalline powders. In this work, the sol-gel synthesis of HAp was investigated employing triethyl phosphate and calcium nitrate tetrahydrate as phosphorous and calcium precursors, respectively. The aging effect on phase composition and powder morphology of the final product was studied in terms of temperature and aging time. The powders were studied by using X-ray diffraction, Fourier transform infrared spectroscopy, particle size distribution by laser diffraction and scanning electron microscopy. (author)
Upgrades for TwinSol facility

Energy Technology Data Exchange (ETDEWEB)

O’Malley, P.D.; Bardayan, D.W.; Kolata, J.J.; Hall, M.R.; Hall, O.; Allen, J. [Physics Department, University of Notre Dame, Notre Dame, IN 46556 (United States); Becchetti, F.D. [Physics Department, U. Michigan, Ann Arbor MI 48109 (United States)

2016-06-01

TwinSol, a pair of coupled, superconducting solenoids, was one of the first devices capable of producing beams of radioactive nuclei at energies near the Coulomb barrier. A primary beam from University of Notre Dame (UND) tandem accelerator is used to bombard a primary target producing a secondary beam in flight. TwinSol is used to gather, separate, and focus the recoils. Since it was commissioned at the UND in 1997, at least 58 publications have reported data from its use and there have been hundreds of collaborators from many different countries that use this device. Currently, plans are in place at the UND to provide several upgrades to TwinSol, including a multi-cell gas production target and the possible addition of a third solenoid. Upgrades currently in progress will be discussed along with future plans.
Study of the electron heat transport in Tore-Supra tokamak; Etude du transport de la chaleur electronique dans le Tokamak Tore Supra

Energy Technology Data Exchange (ETDEWEB)

Harauchamps, E

2004-07-01

This work presents analytical solutions to the electron heat transport equation involving a damping term and a convection term in a cylindrical geometry. These solutions, processed by Matlab, allow the determination of the evolution of the radial profile of electron temperature in tokamaks during heating. The modulated injection of waves around the electron cyclotron frequency is an efficient tool to study heat transport experimentally in tokamaks. The comparison of these analytical solutions with experimental results from Tore-Supra during 2 discharges (30550 and 31165) shows the presence of a sudden change for the diffusion and damping coefficients. The hypothesis of the presence of a pinch spread all along the plasma might explain the shape of the experimental temperature profiles. These analytical solutions could be used to determine the time evolution of plasma density as well or of any parameter whose evolution is governed by a diffusion-convection equation. (A.C.)
Phase change heat transfer device for process heat applications

International Nuclear Information System (INIS)

Sabharwall, Piyush; Patterson, Mike; Utgikar, Vivek; Gunnerson, Fred

2010-01-01

The next generation nuclear plant (NGNP) will most likely produce electricity and process heat, with both being considered for hydrogen production. To capture nuclear process heat, and transport it to a distant industrial facility requires a high temperature system of heat exchangers, pumps and/or compressors. The heat transfer system is particularly challenging not only due to the elevated temperatures (up to ∼1300 K) and industrial scale power transport (≥50 MW), but also due to a potentially large separation distance between the nuclear and industrial plants (100+ m) dictated by safety and licensing mandates. The work reported here is the preliminary analysis of two-phase thermosyphon heat transfer performance with alkali metals. A thermosyphon is a thermal device for transporting heat from one point to another with quite extraordinary properties. In contrast to single-phased forced convective heat transfer via 'pumping a fluid', a thermosyphon (also called a wickless heat pipe) transfers heat through the vaporization/condensing process. The condensate is further returned to the hot source by gravity, i.e., without any requirement of pumps or compressors. With this mode of heat transfer, the thermosyphon has the capability to transport heat at high rates over appreciable distances, virtually isothermally and without any requirement for external pumping devices. Two-phase heat transfer by a thermosyphon has the advantage of high enthalpy transport that includes the sensible heat of the liquid, the latent heat of vaporization, and vapor superheat. In contrast, single-phase forced convection transports only the sensible heat of the fluid. Additionally, vapor-phase velocities within a thermosyphon are much greater than single-phase liquid velocities within a forced convective loop. Thermosyphon performance can be limited by the sonic limit (choking) of vapor flow and/or by condensate entrainment. Proper thermosyphon requires analysis of both.
A New Scheme for Considering Soil Water-Heat Transport Coupling Based on Community Land Model: Model Description and Preliminary Validation

Science.gov (United States)

Wang, Chenghai; Yang, Kai

2018-04-01

Land surface models (LSMs) have developed significantly over the past few decades, with the result that most LSMs can generally reproduce the characteristics of the land surface. However, LSMs fail to reproduce some details of soil water and heat transport during seasonal transition periods because they neglect the effects of interactions between water movement and heat transfer in the soil. Such effects are critical for a complete understanding of water-heat transport within a soil thermohydraulic regime. In this study, a fully coupled water-heat transport scheme (FCS) is incorporated into the Community Land Model (version 4.5) to replaces its original isothermal scheme, which is more complete in theory. Observational data from five sites are used to validate the performance of the FCS. The simulation results at both single-point and global scale show that the FCS improved the simulation of soil moisture and temperature. FCS better reproduced the characteristics of drier and colder surface layers in arid regions by considering the diffusion of soil water vapor, which is a nonnegligible process in soil, especially for soil surface layers, while its effects in cold regions are generally inverse. It also accounted for the sensible heat fluxes caused by liquid water flow, which can contribute to heat transfer in both surface and deep layers. The FCS affects the estimation of surface sensible heat (SH) and latent heat (LH) and provides the details of soil heat and water transportation, which benefits to understand the inner physical process of soil water-heat migration.
Hydroxyapatite, fluor-hydroxyapatite and fluorapatite produced via the sol-gel method: bonding to titanium and scanning electron microscopy.

Science.gov (United States)

Tredwin, Christopher J; Georgiou, George; Kim, Hae-Won; Knowles, Jonathan C

2013-05-01

Hydroxyapatite (HA), fluor-hydroxyapatite (FHA) with varying levels of fluoride ion substitution and fluorapatite (FA) production has been characterised and optimised by the sol-gel method and the dissolution and biological properties of these materials were investigated. It was the objective of this study to investigate the potential bond strength and interaction of these materials with titanium. HA, FHA and FA were synthesised by a sol-gel method. Calcium nitrate and triethyl phosphite were used as precursors under an ethanol-water based solution. Different amounts of ammonium fluoride (NH4F) were incorporated for the preparation of the FHA and FA sol-gels. Using a spin coating technique the sol-gels were coated onto commercially pure titanium disks and crystallised at various temperatures. Using scanning electron microscopy (SEM) and elemental analysis, the surface characteristics, coating thickness and interaction of the Ti substrate and coating were investigated. The bond strengths of the coating to the Ti were investigated using an Instron Universal Load Testing Machine. Statistical analysis was performed with a two-way analysis of variance and post hoc testing with a Bonferroni correction. (1) Coating speed inversely influenced the coating thickness. (2) Increasing fluoride ion substitution and heating temperature significantly increased bond strength and (3) increasing fluoride ion substitution increased the coating thickness. FHA and FA synthesised using the sol-gel technique may offer a superior alternative to coating titanium implants with HA and plasma spraying. HA, FHA and FA materials synthesised by the sol-gel method may also have a use as bone grafting materials. Copyright © 2013 Academy of Dental Materials. Published by Elsevier Ltd. All rights reserved.
Air quality investigations of the Sandia National Laboratories Sol se Mete Aerial Cable Facility

International Nuclear Information System (INIS)

Gutman, W.M.; Silver, R.J.

1994-12-01

The air quality implications of the test and evaluation activities at the Sandia National Laboratories Sol se Mete Aerial Cable Facility are examined. All facets of the activity that affect air quality are considered. Air contaminants produced directly include exhaust products of rocket motors used to accelerate test articles, dust and gas from chemical explosives, and exhaust gases from electricity generators in the test arenas. Air contaminants produced indirectly include fugitive dust and exhaust contaminants from vehicles used to transport personnel and material to the test area, and effluents produced by equipment used to heat the project buildings. Both the ongoing program and the proposed changes in the program are considered. Using a reliable estimate of th maximum annual testing level, the quantities of contaminants released by project activities ar computed either from known characteristics of test items or from EPA-approved emission factors Atmospheric concentrations of air contaminants are predicted using EPA dispersion models. The predicted quantities and concentrations are evaluated in relation to Federal, New Mexico, an Bernalillo County air quality regulations and the human health and safety standards of the American Conference of Governmental Industrial Hygienists
Optical and electrochromic properties of sol-gel deposited Ti- doped vanadium oxide films

International Nuclear Information System (INIS)

Oezer, N.; Sabuncu, S.

1997-01-01

Because of the yellowish color, vanadium oxide films in the as deposited state is not as favorable as transparent coatings for most elector chromic devices. an interesting possibility to alter the yellowish colours is the doping with other non-absorbing metal oxides. Ti doped vanadium oxide films with various amounts of titanium were synthesized and investigated as transparent counter electrodes for electrochromic transmissive device application. Electrochromic titanium doped vanadium pentoxide (V sub 2 O 5) coatings were prepared by the sol-gel dip coating technique. The coating solutions were synthesized from vanadium tri(isopropoxide) precursors. X-ray diffraction (XRD) studies showed that the sol-gel deposited doped films heat treated at temperatures below 350 degree centigrade, were amorphous, whereas hose heat treated at higher temperatures were slight y crystalline. The optical and electrochemical properties of the Ti doped vanadium oxide films has been investigated in 0.1 m LiClO sub 4 propylene carbonate solution color changes by dropping were noted for all investigated films exhibits good electrochemical cycling (CV) measurements also showed that Ti doped V sub 2 O sub 5 films exhibits good electrochemical cycling reversibility, 'in situ' optical measurement revealed that those films exhibits good electrochemical cycling the spectra range 300 < lambda < 800 nm and change color between yellow and light green. The change in visible transmittance was 25 % for 5% Ti doped film. (author)
Fast Processing of Sol-Gel TCO

NARCIS (Netherlands)

Deelen, J. van; Rem, M.; Arfsten, N.; Buskens, P.P.

2016-01-01

TCOs are usually deposited using sputtering or chemical vapor deposition, which have a yield of typically 50-75%. The sol gel method does not need low pressure and can be done with a high precursor yield in the range of 90 – 100%. Sol gel enables also the TCO function as a planarization or
Opportunity's Surroundings on Sol 1687 (Vertical)

Science.gov (United States)

2009-01-01

NASA's Mars Exploration Rover Opportunity used its navigation camera to take the images combined into this 360-degree view of the rover's surroundings on the 1,687th Martian day, or sol, of its surface mission (Oct. 22, 2008). Opportunity had driven 133 meters (436 feet) that sol, crossing sand ripples up to about 10 centimeters (4 inches) tall. The tracks visible in the foreground are in the east-northeast direction. Opportunity's position on Sol 1687 was about 300 meters southwest of Victoria Crater. The rover was beginning a long trek toward a much larger crater, Endeavour, about 12 kilometers (7 miles) to the southeast. This view is presented as a vertical projection with geometric seam correction.
Opportunity's Surroundings on Sol 1687 (Polar)

Science.gov (United States)

2009-01-01

NASA's Mars Exploration Rover Opportunity used its navigation camera to take the images combined into this 360-degree view of the rover's surroundings on the 1,687th Martian day, or sol, of its surface mission (Oct. 22, 2008). Opportunity had driven 133 meters (436 feet) that sol, crossing sand ripples up to about 10 centimeters (4 inches) tall. The tracks visible in the foreground are in the east-northeast direction. Opportunity's position on Sol 1687 was about 300 meters southwest of Victoria Crater. The rover was beginning a long trek toward a much larger crater, Endeavour, about 12 kilometers (7 miles) to the southeast. This view is presented as a polar projection with geometric seam correction.
Latest investigations on fluctuations, ELM filaments and turbulent transport in the SOL of ASDEX Upgrade

Czech Academy of Sciences Publication Activity Database

Müller, H. W.; Adámek, Jiří; Cavazzana, R.; Conway, G.D.; Fuchs, C.; Gunn, J. P.; Herrmann, A.; Horáček, Jan; Ionita, C.; Kallenbach, A.; Kočan, M.; Maraschek, M.; Maszl, C.; Mehlmann, F.; Nold, B.; Peterka, M.; Rohde, V.; Schweinzer, J.; Schrittwieser, R.; Vianello, N.; Wolfrum, E.; Zuin, M.

2011-01-01

Roč. 51, č. 7 (2011), 073023-073023 ISSN 0029-5515 R&D Projects: GA AV ČR KJB100430901 Institutional research plan: CEZ:AV0Z20430508 Keywords : SOL * ASDEX * ELM * tokamak * ball- pen * H-mode Subject RIV: BL - Plasma and Gas Discharge Physics Impact factor: 4.090, year: 2011 http://iopscience.iop.org/0029-5515/51/7/073023/pdf/0029-5515_51_7_073023.pdf
Bioactive materials for biomedical applications using sol-gel technology

International Nuclear Information System (INIS)

Gupta, Radha; Kumar, Ashok

2008-01-01

This review paper focuses on the sol-gel technology that has been applied in many of the potential research areas and highlights the importance of sol-gel technology for preparing bioactive materials for biomedical applications. The versatility of sol-gel chemistry enables us to manipulate the characteristics of material required for particular applications. Sol-gel derived materials have proved to be good biomaterials for coating films and for the construction of super-paramagnetic nanoparticles, bioactive glasses and fiberoptic applicators for various biomedical applications. The introduction of the sol-gel route in a conventional method of preparing implants improves the mechanical strength, biocompatibility and bioactivity of scaffolds and prevents corrosion of metallic implants. The use of organically modified silanes (ORMOSILS) yields flexible and bioactive materials for soft and hard tissue replacement. A novel approach of nitric-oxide-releasing sol-gels as antibacterial coatings for reducing the infection around orthopedic implants has also been discussed
Sol-gel preparation of uranium oxide spheres

International Nuclear Information System (INIS)

Dolezal, J.; Urbanek, V.

1978-01-01

Information is presented on problems of preparing nuclear fuel by the sol-gel method. Basic data on different process types are given. A more detailed description of the method of preparation of spherical particles of uranium oxide gel developed and used at the Nuclear Research Institute at Rez is given. Advantages and disadvantages of sol-gel materials are discussed in comparison with fuel materials prepared by classical precipitation methods. The feasibility of the sol-gel methods for preparing other materials is shortly mentioned and their application outlined. (author)

Modeling of amorphous pocket formation in silicon by numerical solution of the heat transport equation

International Nuclear Information System (INIS)

Kovac, D.; Otto, G.; Hobler, G.

2005-01-01

In this paper we present a model of amorphous pocket formation that is based on binary collision simulations to generate the distribution of deposited energy, and on numerical solution of the heat transport equation to describe the quenching process. The heat transport equation is modified to consider the heat of melting when the melting temperature is crossed at any point in space. It is discretized with finite differences on grid points that coincide with the crystallographic lattice sites, which allows easy determination of molten atoms. Atoms are considered molten if the average of their energy and the energy of their neighbors meets the melting criterion. The results obtained with this model are in good overall agreement with published experimental data on P, As, Te and Tl implantations in Si and with data on the polyatomic effect at cryogenic temperature
Impact on Divertor Operation of the Pattern of Edge and SOL Flows Induced by Particle Sources and Sinks

Energy Technology Data Exchange (ETDEWEB)

Ghendrih, P.; Bucalossi, J.; Futtersack, R.; Guillemaut, C.; Moulton, D.; Tamain, P., E-mail: philippe.ghendrih@cea.fr [CEA-IRFM, Saint Paul-lez-Durance (France); Auphan, T.; Mentrelli, A. [LATP, Technopole de Chateau-Gombert, Marseille (France); Bensiali, B.; Chiavassa, G.; Ciracolo, G.; Paredes, A.; Serre, E.; Schwander, F. [M2P2, Technopole de Chateau-Gombert, Marseille (France); Bilanceri, M.; Guillard, H. [INRIA, Sophia Antipolis and LJAD, Nice (France); Bodi, K. [M2P2, Technopole de Chateau-Gombert, Marseille (France); Dept. of Aerospace Engg., IIT Bombay, Mumbai (India); Bufferand, H. [CEA-IRFM, Saint Paul-lez-Durance (France); M2P2,Technopole de Chateau-Gombert, Marseille (France); Marandet, Y. [PIIM, CNRS/Aix-Marseille Universite, Marseille (France); Pasquetti, R. [LJAD, Nice (France)

2012-09-15

Full text: The role of divertors in present device operation is to control particle sources and sinks and consequently the energy flux channels in the boundary region of magnetically confined plasmas. The ESPOIR effort is based on a set of fluid codes from 1-D parallel to 3-D micro-turbulence modelling. Due to the long range particle transport into the SOL governed by intermittent turbulent bursts, the precise location of the particle sources at the wall is required to properly address the screening of the neutral particle influx. To that end we have developed a penalisation technique that extends the simulation domain up to all the plasma facing components of interest. The penalisation technique initiated for particle and momentum sinks has been extended to the temperatures as well as to electric currents. We have used the penalisation technique in 2D simulations of the radial shift of the plasma from the low field side modular limiter to the high field side bumper limiter. Experiments of the kind where achieved in TFTR, JET and Tore Supra to investigate the particle confinement time and particle trapping in the wall. We show that the ballooned transport plays a crucial role in these experiments so that most of the core density drop is reversible. In the divertor configuration, low ionisation sources are shown to govern a supersonic solution. Simulations of such a regime exhibit weak divertor density variation as the core plasma density is ramped up, in agreement with analytical predictions. In the standard divertor regimes, we show analytically that the plasma tends to a supersonic flow when the total plasma pressure is conserved along the field lines. The back transition to the subsonic flow at the plate then takes place at the cross-over between the diffusive heat transport and the convective energy transport. Such behaviour disappears when total plasma pressure losses take place. In the case of very strong divertor screening one finds a Mach number close to
Modeling Coupled Water and Heat Transport in the Root Zone of Winter Wheat under Non-Isothermal Conditions

Directory of Open Access Journals (Sweden)

Rong Ren

2017-04-01

Full Text Available Temperature is an integral part of soil quality in terms of moisture content; coupling between water and heat can render a soil fertile, and plays a role in water conservation. Although it is widely recognized that both water and heat transport are fundamental factors in the quantification of soil mass and energy balance, their computation is still limited in most models or practical applications in the root zone under non-isothermal conditions. This research was conducted to: (a implement a fully coupled mathematical model that contains the full coupled process of soil water and heat transport with plants focused on the influence of temperature gradient on soil water redistribution and on the influence of change in soil water movement on soil heat flux transport; (b verify the mathematical model with detailed field monitoring data; and (c analyze the accuracy of the model. Results show the high accuracy of the model in predicting the actual changes in soil water content and temperature as a function of time and soil depth. Moreover, the model can accurately reflect changes in soil moisture and heat transfer in different periods. With only a few empirical parameters, the proposed model will serve as guide in the field of surface irrigation.
Numerical modelling of coupled fluid, heat, and solute transport in deformable fractured rock

International Nuclear Information System (INIS)

Chan, T.; Reid, J.A.K.

1987-01-01

This paper reports on a three-dimensional (3D) finite-element code, MOTIF (model of transport in fractured/porous media), developed to model the coupled processes of groundwater flow, heat transport, brine transport, and one-species radionuclide transport in geological media. Three types of elements are available: a 3D continuum element, a planar fracture element that can be oriented in any arbitrary direction in 3D space or pipe flow in 3D space, and a line element for simulating fracture flow in 2D space or pipe flow in 3D space. As a quality-assurance measure, the MOTIF code was verified by comparison of its results with analytical solutions and other published numerical solutions
Dynamics of water transport and storage in conifers studied with deuterium and heat tracing techniques.

Science.gov (United States)

F.C. Meinzer; J.R. Brooks; J.-C. Domec; B.L. Gartner; J.M. Warren; D.R. Woodruff; K. Bible; D.C. Shaw

2006-01-01

The volume and complexity of their vascular systems make the dynamics of tong-distance water transport in large trees difficult to study. We used heat and deuterated water (D20) as tracers to characterize whole-tree water transport and storage properties in individual trees belonging to the coniferous species Pseudotsuga menziesii...
Heat science and transport phenomena in fuel cells; Thermique et phenomenes de transport dans les piles a combustible

Energy Technology Data Exchange (ETDEWEB)

Liberatore, P.M.; Boillot, M. [Laboratoire des Sciences du Genie Chimique de Nancy, 54 - Vandoeuvre-les-Nancy (France); Bonnet, C.; Didieerjean, S.; Lapicque, F.; Deseure, J.; Lottin, O.; Maillet, D.; Oseen-Senda, J. [Laboratoire d' Energetique et de Mecanique Theorique et Appliquee, 54 - Vandoeuvre Les Nancy (France); Alexandre, A. [Laboratoire d' Etudes Thermiques, ENSMA, 86 Poitiers (France); Topin, F.; Occelli, R.; Daurelle, J.V. [IUSTI / Polytech' Marseille, Institut universitaire des Systemes Thermiques Industriels Ecole, 13 - Marseille (France); Pauchet, J.; Feidt, M. [CEA Grenoble, Groupement pour la recherche sur les echangeurs thermiques (Greth), 38 (France); Voarino, C. [CEA Centre d' Etudes du Ripault, 37 - Tours (France); Morel, B.; Laurentin, J.; Bultel, Y.; Lefebvre-Joud, F. [CEA Grenoble, LEPMI, 38 (France); Auvity, B.; Lasbet, Y.; Castelain, C.; Peerohossaini, H. [Ecole Centrale de Nantes, Laboratoire de Thermocinetique de Nantes (LTN), 44 - Nantes (France)

2005-07-01

In this work are gathered the transparencies of the lectures presented at the conference 'heat science and transport phenomena in fuel cells'. The different lectures have dealt with 1)the gas distribution in the bipolar plates of a fuel cell: experimental studies and computerized simulations 2)two-phase heat distributors in the PEMFC 3)a numerical study of the flow properties of the backing layers on the transfers in a PEMFC 4)modelling of the heat and mass transfers in a PEMFC 5)two-phase cooling of the PEMFC with pentane 6)stationary thermodynamic model of the SOFC in the GECOPAC system 7)modelling of the internal reforming at the anode of the SOFC 8)towards a new thermal design of the PEMFC bipolar plates. (O.M.)
Effects of frequently used pharmaceutical excipients on the organic cation transporters 1-3 and peptide transporters 1/2 stably expressed in MDCKII cells.

Science.gov (United States)

Otter, Marcus; Oswald, Stefan; Siegmund, Werner; Keiser, Markus

2017-03-01

There is ample evidence that pharmaceutical excipients, which are supposed to be pharmacologically inactive, have an impact on drug metabolism and efflux transport. So far, little is known whether they also modulate uptake transporter proteins. We have recently shown that commonly used solubilizing agents exert significant effects on the function of organic anion uptake transporting polypeptides. Therefore, we investigated in this study the influence of frequently used pharmaceutical excipients on the transport activity of organic cation transporters OCT1, OCT2 and OCT3 and the peptide transporters PEPT1 and PEPT2. Inhibition of the OCTs and PEPTs by the excipients polyethylene glycol 400 (PEG), hydroxypropyl-β-cyclodextrin (HPCD), Solutol® HS15 (SOL), Cremophor® EL (CrEL), Tween® 20 (Tw20), Tween® 80 (Tw80), Kolliphor® P188 (P188) and Kolliphor® P407 (P407) was evaluated using stably transfected MDCKII cells with radio-labeled reference substrates and established inhibitors as controls. Intracellular accumulation of [3H]-1-methyl-4-phenylpyridinium (MPP + ) for the OCTs and [3H]-glycyl-sarcosine (Gly-Sar) for the PEPTs was measured by liquid scintillation counting after cell lysis. Our studies revealed that PEG, HPCD, SOL, CrEL, Tw20 and Tw80 were potent inhibitors of OCT1-3 (e.g., Tw20 IC 50 values<0.04%). Cellular uptake of Gly-Sar by PEPT1 and PEPT2 was strongly inhibited by both Tw20 and Tw80. SOL was also a strong inhibitor of PEPT1 and PEPT2 (e.g., SOL IC 50 values<0.02%), while CrEL showed significantly inhibition of only PEPT2. The substantial inhibitory effects of certain solubilizing agents on OCTs and PEPTs should be considered if they are to be used in dosage forms for new chemical entities and registered drugs to avoid misinterpretation of pharmacokinetic data and undesired drug interactions. Copyright © 2016 Elsevier B.V. All rights reserved.
Current and future possibilities of sol-gel process

International Nuclear Information System (INIS)

Sakka, Sumio

2004-01-01

The sol-gel method is characterized by the low temperature processing. Since this method starts from solutions, the product is essentially nanomaterials. So far, various kinds of microstructures, including dense, porous, hybrid, amorphous and crystalline microstructures have been realized. Accordingly, sol-gel materials cover a wide range of functions, such as optical, electronic, mechanical, chemical and bio-functions. Future perspectives of the sol-gel method are described in the article. (author)
Sol-gel process for thermal reactor fuel fabrication

International Nuclear Information System (INIS)

Mukerjee, S.K.

2008-01-01

Full text: Sol-gel processes have revolutionized conventional ceramic technology by providing extremely fine and uniform powders for the fabrication of ceramics. The use of this technology for nuclear fuel fabrication has also been explored in many countries. Unlike the conventional sol-gel process, sol-gel process for nuclear fuels tries to eliminate the preparation of powders in view of the toxic nature of the powders particularly those of plutonium and 233 U. The elimination of powder handling thus makes this process more readily amenable for use in glove boxes or for remote handling. In this process, the first step is the preparation of microspheres of the fuel material from a solution which is then followed by vibro-compaction of these microspheres of different sizes to obtain the required smear density of fuel inside a pin. The maximum achievable packing density of 92 % makes it suitable for fast reactors only. With a view to extend the applicability of sol-gel process for thermal reactor fuel fabrication the concept of converting the gel microspheres derived from sol-gel process, to the pellets, has been under investigation for several years. The unique feature of this process is that it combines the advantages of sol-gel process for the preparation of fuel oxide gel microspheres of reproducible quality with proven irradiation behavior of the pellet fuel. One of the important pre-requisite for the success of this process is the preparation of soft oxide gel microspheres suitable for conversion to dense pellets free from berry structure. Studies on the internal gelation process, one of the many variants of sol-gel process, for obtaining soft oxide gel microspheres suitable for gel pelletisation is now under investigation at BARC. Some of the recent findings related to Sol-Gel Microsphere Pelletisation (SGMP) in urania-plutonia and thoria-urania systems will be presented
Analysis on the factors affecting the preparation of TIO2-ADUN composite sol by sol-gel method

International Nuclear Information System (INIS)

Wang Hui; Yin Rongcai; Liu Jinhong

2010-01-01

With C 2 H 2 O 5 and water as solvent and TBT as precursor and HNO 3 as the activator and valorize, the process for preparing TiO 2 -ADUN composite Sol method was studied. The influence of different reaction conditions on Sol-Gel time was analyzed in this study. The optimal reaction condition are: reaction temperature 20-25 degree C; pH value of reaction mixture 2-5; HNO 3 value of reaction mixture 0.3-0.5 ml; molar rations of alcohol to TBT 10, of water to TBT 2-3, respectively. A concentrated ADUN solution with Ti Sol , urea, water as additive is dispersed into uniform which are prepared by external mlii. (authors)
Simulation of the scrape-off layer plasma during a disruption

International Nuclear Information System (INIS)

Rognlien, T.D.; Crotinger, J.A.; Porter, G.D.; Smith, G.R.; Kellman, A.G.; Taylor, P.L.

1996-01-01

The evolution of the scrape-off layer (SOL) during a disruption in the DIII-D tokamak is modeled using the 2-D UEDGE transport code. The focus is on the thermal quench phase when most of the energy content of the discharge is rapidly transported across the magnetic separatrix where it then flows to material surfaces or is radiated. Comparisons between the simulation and an experiment on the DIII-D tokamak are made with the heat flux to the divertor plate, and temperature and density profiles at the SOL midplane. The temporal response of the separate electron and ion heat-flux components to the divertor plate is calculated. The sensitivity of the solution to assumptions of electron heat-flux models and impurity radiation is investigated
SOL: INNOVACIÓN ON-LINE

Directory of Open Access Journals (Sweden)

Rubén Faúndez

2007-11-01

Full Text Available Las aplicaciones de simulación tienden a ser cada vez más cercanas a usuarios e industrias. Sin embargo, muchas de ellas no poseen ni la capacidad ni el conocimiento como para desarrollar internamente sus modelos de simulación. Por este motivo, y como una forma de apoyar la toma de decisiones basándose en modelos de simulación, se presenta la plataforma SOL (Simulación On Line. La metodología completa de trabajo, así como la interacción entre SOL, Empresa y Asesor, son presentadas. Su base de datos, los niveles de usuarios, sus funcionalidades, y la creación automatizada de información grafica y visual, también son explicadas. En el caso de aplicación, el uso de SOL para apoyar la toma de decisiones en una operación de movimiento de material, permite a los tomadores de decisión acceder a análisis robustos basados en información extraída de los modelos de simulación. SOL, al almacenar información, funcionar vía web, generar análisis automatizados y crear visualizaciones, permite cumplir con las expectativas de los usuarios respecto a una solución integral en simulación.
Sol-gel-based biosensing applied to medicinal science.

Science.gov (United States)

Moreira, Felismina T C; Moreira-Tavares, Ana P; Sales, M Goreti F

2015-01-01

Biosensors have opened new horizons in biomedical analysis, by ensuring increased assay speed and flexibility, and allowing point-of-care applications, multi-target analyses, automation and reduced costs of testing. This has been a result of many studies merging nanotechnology with biochemistry over the years, thereby enabling the creation of more suitable environments to biological receptors and their substitution by synthetic analogue materials. Sol-gel chemistry, among other materials, is deeply involved in this process. Sol-gel processing allows the immobilization of organic molecules, biomacromolecules and cells maintaining their properties and activities, permitting their integration into different transduction devices, of electrochemical or optical nature, for single or multiple analyses. Sol-gel also allows to the production of synthetic materials mimicking the activity of natural receptors, while bringing advantages, mostly in terms of cost and stability. Moreover, the biocompatibility of sol-gel materials structures of biological nature allowed the use of these materials in emerging in vivo applications. In this chapter, biosensors for biomedical applications based on sol-gel derived composites are presented, compared and described, along with current emerging applications in vivo, concerning drug delivery or biomaterials. Sol-gel materials are shown as a promising tool for current, emerging and future medical applications.
Nanoscale phase engineering of thermal transport with a Josephson heat modulator

Science.gov (United States)

Fornieri, Antonio; Blanc, Christophe; Bosisio, Riccardo; D'Ambrosio, Sophie; Giazotto, Francesco

2016-03-01

Macroscopic quantum phase coherence has one of its pivotal expressions in the Josephson effect, which manifests itself both in charge and energy transport. The ability to master the amount of heat transferred through two tunnel-coupled superconductors by tuning their phase difference is the core of coherent caloritronics, and is expected to be a key tool in a number of nanoscience fields, including solid-state cooling, thermal isolation, radiation detection, quantum information and thermal logic. Here, we show the realization of the first balanced Josephson heat modulator designed to offer full control at the nanoscale over the phase-coherent component of thermal currents. Our device provides magnetic-flux-dependent temperature modulations up to 40 mK in amplitude with a maximum of the flux-to-temperature transfer coefficient reaching 200 mK per flux quantum at a bath temperature of 25 mK. Foremost, it demonstrates the exact correspondence in the phase engineering of charge and heat currents, breaking ground for advanced caloritronic nanodevices such as thermal splitters, heat pumps and time-dependent electronic engines.
Ultraviolet Stimulated Emission from Sol-Gel Spin Coated ZnO Thin Films

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Ahmed S. Razeen

2017-01-01

Full Text Available Low cost ultraviolet stimulated emission has been generated using optical excitation of ZnO thin films deposited by sol-gel spin coating on n+ As-doped 100 Si-substrate. The number of deposited layers and the heat treatment have been investigated to obtain a film that can generate stimulated emission under optical excitation. The optimum condition for preparation of the film has been presented. X-ray diffraction and scanning electron microscope have been used for structural and morphological investigations. Input-output intensity dependence and spectral width, peak emission wavelength, and the quantum efficiency versus the pump intensity have been presented. A quantum efficiency of about 24.2% has been reported, a power exponent higher than 8 has been obtained in input-output intensity dependence, and a threshold of about 23 Mw/cm2 has been evaluated for the samples. The mechanism by which stimulated emission occurs has been discussed. The results show that sol-gel spin coating is a promising method for generating ultraviolet stimulated emission from ZnO thin films.
Electron thermal energy transport research based on dynamical relationship between heat flux and temperature gradient

International Nuclear Information System (INIS)

Notake, Takashi; Inagaki, Shigeru; Tamura, Naoki

2008-01-01

In the nuclear fusion plasmas, both of thermal energy and particle transport governed by turbulent flow are anomalously enhanced more than neoclassical levels. Thus, to clarify a relationship between the turbulent flow and the anomalous transports has been the most worthwhile work. There are experimental results that the turbulent flow induces various phenomena on transport processes such as non-linearity, transition, hysteresis, multi-branches and non-locality. We are approaching these complicated problems by analyzing not conventional power balance but these phenomena directly. They are recognized as dynamical trajectories in the flux and gradient space and must be a clue to comprehend a physical mechanism of arcane anomalous transport. Especially, to elucidate the mechanism for electron thermal energy transport is critical in the fusion plasma researches because the burning plasmas will be sustained by alpha-particle heating. In large helical device, the dynamical relationships between electron thermal energy fluxes and electron temperature gradients are investigated by using modulated electron cyclotron resonance heating and modern electron cyclotron emission diagnostic systems. Some trajectories such as hysteresis loop or line segments with steep slope which represent non-linear property are observed in the experiment. (author)
A comparison of mid-plane scrape-off-layer measurements with model predictions in MAST and the calculation of cross-field transport coefficients

International Nuclear Information System (INIS)

Kirk, A; Counsell, G F; Fundamenski, W; Ahn, J-W; Taylor, D; Walsh, M J; Yang, Y

2004-01-01

The outboard mid-plane values of electron density (n e ) and temperature (T e ) in the scrape-off-layer (SOL) of MAST are derived from target Langmuir probe measurements using OSM2-EIRENE and also using a simple two-point model. The values are compared with mid-plane measurements of n e and T e from a reciprocating probe and a Thomson scattering system for Ohmic, L- and H-modes single-null divertor (SND) discharges. The cross-field heat (χ perpendicular ) diffusion coefficient at the low field side of SND discharges is derived both using the OSM2-EIRENE model and a two-point model coupled with a simple theory. The results are found to be similar within the errors. Typically χ perpendicular values are found to lie in the range 0.5-2.0 m 2 s -1 for L-mode and 0.1-0.5 m 2 s -1 for H-mode. A comparison is made of the transport coefficients derived at the low and high field sides for a set of connected double-null discharges. These results are used to make preliminary observations of the effect of magnetic fields on SOL transport in MAST
Numerical Simulation of Density-Driven Flow and Heat Transport Processes in Porous Media Using the Network Method

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Manuel Cánovas

2017-09-01

Full Text Available Density-driven flow and heat transport processes in 2-D porous media scenarios are governed by coupled, non-linear, partial differential equations that normally have to be solved numerically. In the present work, a model based on the network method simulation is designed and applied to simulate these processes, providing steady state patterns that demonstrate its computational power and reliability. The design is relatively simple and needs very few rules. Two applications in which heat is transported by natural convection in confined and saturated media are studied: slender boxes heated from below (a kind of Bénard problem and partially heated horizontal plates in rectangular domains (the Elder problem. The streamfunction and temperature patterns show that the results are coherent with those of other authors: steady state patterns and heat transfer depend both on the Rayleigh number and on the characteristic Darcy velocity derived from the values of the hydrological, thermal and geometrical parameters of the problems.
Silica Sol-Gel Entrapment of the Enzyme Chloro peroxidase

International Nuclear Information System (INIS)

Le, T.; Chan, S.; Ebaid, B.; Sommerhalter, M.

2015-01-01

The enzyme chloro peroxidase (CPO) was immobilized in silica sol-gel beads prepared from tetramethoxysilane. The average pore diameter of the silica host structure (∼3 nm) was smaller than the globular CPO diameter (∼6 nm) and the enzyme remained entrapped after sol-gel maturation. The catalytic performance of the entrapped enzyme was assessed via the pyrogallol peroxidation reaction. Sol-gel beads loaded with 4 μg CPO per mL sol solution reached 9-12% relative activity compared to free CPO in solution. Enzyme kinetic analysis revealed a decrease in K_cat but no changes in K_M or K_I . Product release or enzyme damage might thus limit catalytic performance. Yet circular dichroism and visible absorption spectra of transparent CPO sol-gel sheets did not indicate enzyme damage. Activity decline due to methanol exposure was shown to be reversible in solution. To improve catalytic performance the sol-gel protocol was modified. The incorporation of 5, 20, or 40% methyltrimethoxysilane resulted in more brittle sol-gel beads but the catalytic performance increased to 14% relative to free CPO in solution. The use of more acidic casting buffers (ph 4.5 or 5.5 instead of 6.5) resulted in a more porous silica host reaching up to 18% relative activity
Non-equilibrium thermodynamics, heat transport and thermal waves in laminar and turbulent superfluid helium

Science.gov (United States)

Mongiovì, Maria Stella; Jou, David; Sciacca, Michele

2018-01-01

This review paper puts together some results concerning non equilibrium thermodynamics and heat transport properties of superfluid He II. A one-fluid extended model of superfluid helium, which considers heat flux as an additional independent variable, is presented, its microscopic bases are analyzed, and compared with the well known two-fluid model. In laminar situations, the fundamental fields are density, velocity, absolute temperature, and heat flux. Such a theory is able to describe the thermomechanical phenomena, the propagation of two sounds in liquid helium, and of fourth sound in superleak. It also leads in a natural way to a two-fluid model on purely macroscopical grounds and allows a small amount of entropy associated with the superfluid component. Other important features of liquid He II arise in rotating situations and in superfluid turbulence, both characterized by the presence of quantized vortices (thin vortex lines whose circulation is restricted by a quantum condition). Such vortices have a deep influence on the transport properties of superfluid helium, as they increase very much its thermal resistance. Thus, heat flux influences the vortices which, in turn, modify the heat flux. The dynamics of vortex lines is the central topic in turbulent superfluid helium. The model is generalized to take into account the vortices in different cases of physical interest: rotating superfluids, counterflow superfluid turbulence, combined counterflow and rotation, and mass flow in addition to heat flow. To do this, the averaged vortex line density per unit volume L, is introduced and its dynamical equations are considered. Linear and non-linear evolution equations for L are written for homogeneous and inhomogeneous, isotropic and anisotropic situations. Several physical experiments are analyzed and the influence of vortices on the effective thermal conductivity of turbulent superfluid helium is found. Transitions from laminar to turbulent flows, from diffusive to

Non-local transport in a tokamak plasma divertor with recycling

International Nuclear Information System (INIS)

Abou-Assaleh, Z.; Petravic, M.; Vesey, R.

1993-01-01

The plasma transport, particle and energy fluxes, near the diverter plate with high recycling has been modeled by using an electron kinetic code (Fokker-Planck International) in conjunction with a two-fluid ambipolar code. We include the effects of ionization and excitation of the hydrogen atoms. The electron energy distribution calculated from the kinetic code shows a large deviation from Maxwellian especially near the plate. This deviation from Maxwellian is due to the non-local transport of the suprathermal electrons from the SOL, and due also to the absorption of the fast electrons by the target plate. The heat flux near the plate is shown to be nonlocal, in that it is not determined uniquely by the local plasma parameters. Therefore the classical transport coefficients in the fluid model must be modified by including a nonlocal effect to produce the kinetic results. The kinetic calculation is compared with those of the fluid code with different values of the electron heat flux limiter factor (f). To reduce the computer load, the initial condition we used corresponds to the equilibrium solution already found with the fluid code with f=0.2. The fluid and Fokker-Planck codes are relaxed until all transients associated with electron dynamics have disappeared. In section 2, we present the kinetic code. The fluid code is presented in section 3. The boundary conditions used in these simulations are given in section 4. Finally the results and conclusion of these simulations are presented in section 5
Numerical simulations for ITER divertor armour erosion and SOL contamination due to disruptions and ELMs

International Nuclear Information System (INIS)

Landman, I.S.; Pestchanyi, S.E.; Bazylev, B.N.

2005-01-01

The divertor armour materials for ITER are going to be tungsten (as brushe or plates) and CFC. Disruptive loads with the heat deposition Q up to 30 MJ/m 2 on the time scale τ of 3 ms or operation with ELMs at repetitive loads of Q ∼ 3 MJ/m 2 and τ ∼ 0.3 ms cause enhanced armour erosion and produce contamination of SOL. Recent numerical investigations of erosion mechanisms with the anisotropic thermomechanics code PEGASUS-3D and the surface melt motion code MEMOS-1.5D as well as hot hydrogen plasma dynamics, heat loads at the armour surface and backward propagation of material plasma in SOL with the radiation-magnetohydrodynamics code FOREV-2D are survived. For CFC targets, the local overheating model is explained and numerically demonstrated. For the tungsten targets the numerical analysis of melt motion erosion of W-brushe and bulk tungsten targets on the base of MEMOS-1.5D calculations is developed and accompanied by numerical results. For validation of the codes at the regimes relevant to ITER disruptions and ELMs, the simulation results are compared with available experiments carried out at plasma guns, electron beam test facilities and the tokamak JET. (author)
Synthesis of phthalocyanine doped sol-gel materials

Science.gov (United States)

Dunn, Bruce

1993-01-01

The synthesis of sol-gel silica materials doped with three different types of metallophthalocyanines has been studied. Homogeneous materials of good optical quality were prepared and the first optical limiting measurements of dyes in sol-gel hosts were carried out. The properties of these solid state limiters are similar to limiters based on phthalocyanine (Pc) in solution. Sol-gel silica materials containing copper, tin and germanium phthalocyanines were investigated. The initial step in all cases was to prepare silica sols by the sonogel method using tetramethoxy silane (TMOS), HCl and distilled water. Thereafter, the synthesis depended upon the specific Pc and its solubility characteristics. Copper phthalocyanine tetrasulfonic acid tetra sodium salt (CuPc4S) is soluble in water and various doping levels (1 x 10 (exp -4) M to 1 x 10 (exp -5) M) were added to the sol. The group IV Pc's, SnPc(OSi(n-hexyl)3)2 and GePc(OSi(n-hexyl)3)2, are insoluble in water and the process was changed accordingly. In these cases, the compounds were dissolved in THF and then added to the sol. The Pc concentration in the sol was 2 x 10(exp -5)M. The samples were then aged and dried in the standard method of making xerogel monoliths. Comparative nanosecond optical limiting experiments were performed on silica xerogels that were doped with the different metallophthalocyanines. The ratio of the net excited state absorption cross section (sigma(sub e)) to the ground state cross section (sigma(sub g)) is an important figure of merit that is used to characterize these materials. By this standard the SnPc sample exhibits the best limiting for the Pc doped sol-gel materials. Its cross section ratio of 19 compares favorably with the value of 22 that was measured in toluene. The GePc materials appear to not be as useful as those containing SnPc. The GePc doped solids exhibit a higher onset energy (2.5 mj and lower cross section ratio, 7. The CuPc4S sol-gel material has a still lower cross
Low frequency turbulence, particle and heat transport in the Wisconsin levitated octupole

International Nuclear Information System (INIS)

Garner, H.R.

1982-01-01

Low frequency turbulence in the drift frequency range and its relation to the observed particle transport in the Wisconsin Levitated Octupole has been studied with a microwave scattering apparatus. The experimental parameters were T/sub e/ approx. T/sub i/ 13 cm -3 , 200 G < B/sub p-average/ < 1.25 kG. The effect of shear on the transport was studied by the addition of a small toroidal field. By matching experimentally measured density profiles to those given by numerical solutions of the transport equations, diffusion coefficients were obtained. Time dependent density fluctuation spectra were measured with an 8 mm microwave scattering diagnostic to correlate the drift wave portion of the spectrum with the observed diffusion. The density fluctuation spectrum of low frequency (1 kHz < ω < 6 MHz) turbulence was measured for several values of perpendicular wavenumber, k/sub perpendicular to/. Electron heat transport was studied by fitting experimentally measured electron temperature profiles to those predicted by numerical solutions of electron energy transport equation
Modification of the finite element heat and mass transfer code (FEHMN) to model multicomponent reactive transport

International Nuclear Information System (INIS)

Viswanathan, H.S.

1995-01-01

The finite element code FEHMN is a three-dimensional finite element heat and mass transport simulator that can handle complex stratigraphy and nonlinear processes such as vadose zone flow, heat flow and solute transport. Scientists at LANL have been developed hydrologic flow and transport models of the Yucca Mountain site using FEHMN. Previous FEHMN simulations have used an equivalent K d model to model solute transport. In this thesis, FEHMN is modified making it possible to simulate the transport of a species with a rigorous chemical model. Including the rigorous chemical equations into FEHMN simulations should provide for more representative transport models for highly reactive chemical species. A fully kinetic formulation is chosen for the FEHMN reactive transport model. Several methods are available to computationally implement a fully kinetic formulation. Different numerical algorithms are investigated in order to optimize computational efficiency and memory requirements of the reactive transport model. The best algorithm of those investigated is then incorporated into FEHMN. The algorithm chosen requires for the user to place strongly coupled species into groups which are then solved for simultaneously using FEHMN. The complete reactive transport model is verified over a wide variety of problems and is shown to be working properly. The simulations demonstrate that gas flow and carbonate chemistry can significantly affect 14 C transport at Yucca Mountain. The simulations also provide that the new capabilities of FEHMN can be used to refine and buttress already existing Yucca Mountain radionuclide transport studies
Sol-gel coatings on carbon/carbon composites

International Nuclear Information System (INIS)

Sim, S.M.; Krabill, R.M.; Dalzell, W.J. Jr.; Chu, P.Y.; Clark, D.E.

1986-01-01

The need for structural materials that can withstand severe environments up to 4000 0 F has promulgated the investigation of sol-gel derived ceramic and composite coatings on carbon/carbon composite materials. Alumina and zirconia sols have been deposited via thermophoresis on carbon/carbon substrates
Low-Temperature Sol-Gel Synthesis of Nitrogen-Doped Anatase/Brookite Biphasic Nanoparticles with High Surface Area and Visible-Light Performance

Directory of Open Access Journals (Sweden)

Liang Jiang

2017-12-01

Full Text Available Nitrogen doping in combination with the brookite phase or a mixture of TiO2 polymorphs nanomaterials can enhance photocatalytic activity under visible light. Generally, nitrogen-dopedanatase/brookite mixed phases TiO2 nanoparticles obtained by hydrothermal or solvothermal method need to be at high temperature and with long time heating treatment. Furthermore, the surface areas of them are low (<125 m2/g. There is hardly a report on the simple and direct preparation of N-doped anatase/brookite mixed phase TiO2 nanostructures using sol-gel method at low heating temperature. In this paper, the nitrogen-doped anatase/brookite biphasic nanoparticles with large surface area (240 m2/g were successfully prepared using sol-gel method at low temperature (165 °C, and with short heating time (4 h under autogenous pressure. The obtained sample without subsequent annealing at elevated temperatures showed enhanced photocatalytic efficiency for the degradation of methyl orange (MO with 4.2-, 9.6-, and 7.5-fold visible light activities compared to P25 and the amorphous samples heated in muffle furnace with air or in tube furnace with a flow of nitrogen at 165 °C, respectively. This result was attributed to the synergistic effects of nitrogen doping, mixed crystalline phases, and high surface area.
Impact of plasma triangularity and collisionality on electron heat transport in TCV L-mode plasmas

International Nuclear Information System (INIS)

Camenen, Y.; Pochelon, A.; Behn, R.; Bottino, A.; Bortolon, A.; Coda, S.; Karpushov, A.; Sauter, O.; Zhuang, G.

2007-01-01

The impact of plasma shaping on electron heat transport is investigated in TCV L-mode plasmas. The study is motivated by the observation of an increase in the energy confinement time with decreasing plasma triangularity which may not be explained by a change in the temperature gradient induced by changes in the geometry of the flux surfaces. The plasma triangularity is varied over a wide range, from positive to negative values, and various plasmas conditions are explored by changing the total electron cyclotron (EC) heating power and the plasma density. The mid-radius electron heat diffusivity is shown to significantly decrease with decreasing triangularity and, for similar plasma conditions, only half of the EC power is required at a triangularity of -0.4 compared with +0.4 to obtain the same temperature profile. Besides, the observed dependence of the electron heat diffusivity on the electron temperature, electron density and effective charge can be grouped in a unique dependence on the plasma effective collisionality. In summary, the electron heat transport level exhibits a continuous decrease with decreasing triangularity and increasing collisionality. Local gyro-fluid and global gyro-kinetic simulations predict that trapped electron modes are the most unstable modes in these EC heated plasmas with an effective collisionality ranging from 0.2 to 1. The modes stability dependence on the plasma triangularity is investigated
Synthesis of TiO{sub 2} sol in a neutral solution using TiCl{sub 4} as a precursor and H{sub 2}O{sub 2} as an oxidizing agent

Energy Technology Data Exchange (ETDEWEB)

Sasirekha, Natarajan; Rajesh, Baskaran [Department of Chemical Engineering, National Central University, Chung-Li 320, Taiwan (China); Chen, Yu-Wen, E-mail: ywchen@cc.ncu.edu.t [Department of Chemical Engineering, National Central University, Chung-Li 320, Taiwan (China)

2009-11-02

Nanosize TiO{sub 2} thin film on glass substrate was obtained through dip-coating method using TiO{sub 2} sol. Suspended nanosize TiO{sub 2} sols with anatase structure in aqueous solution were synthesized by sol-gel method using TiCl{sub 4} as a precursor. TiCl{sub 4} was reacted with an aqueous solution of NH{sub 4}OH to form Ti(OH){sub 4}, and H{sub 2}O{sub 2} was then added to form peroxo titanic acid. It was further heated in water and converted to TiO{sub 2}. The effects of the preparation parameters, viz., pH value of the Ti(OH){sub 4} gel, concentration of H{sub 2}O{sub 2}, and heating temperature and time, on the properties of the TiO{sub 2} sol were investigated. The materials were characterized by X-ray diffraction, Fourier transform-infrared spectroscopy, and transmission electron microscopy. The results showed that the primary TiO{sub 2} particles were rhombus with the major axis ca. 10 nm and minor axis ca. 4 nm, and were in anatase structure. The sol was excellent in dispersibility and was stable in neutral and even slight basic conditions for at least 2 years without causing agglomeration. The best preparation condition was optimized with the pH value of Ti(OH){sub 4} gel at 8, H{sub 2}O{sub 2}/TiO{sub 2} mole ratio of 2, and heating at 97 {sup o}C for 8 h. The transparent adherent TiO{sub 2} film on glass substrates exhibits strong hydrophilicity after illuminating with ultraviolet light and it can be used as an efficient photocatalyst.
[The design of heat dissipation of the field low temperature box for storage and transportation].

Science.gov (United States)

Wei, Jiancang; Suin, Jianjun; Wu, Jian

2013-02-01

Because of the compact structure of the field low temperature box for storage and transportation, which is due to the same small space where the compressor, the condenser, the control circuit, the battery and the power supply device are all placed in, the design for heat dissipation and ventilation is of critical importance for the stability and reliability of the box. Several design schemes of the heat dissipation design of the box were simulated using the FLOEFD hot fluid analysis software in this study. Different distributions of the temperature field in every design scheme were constructed intimately in the present study. It is well concluded that according to the result of the simulation analysis, the optimal heat dissipation design is decent for the field low temperature box for storage and transportation, and the box can operate smoothly for a long time using the results of the design.
Sol-gel optical coatings for lasers: Part 1

International Nuclear Information System (INIS)

Floch, H.G.; Belleville, P.F.; Priotton, J.J.

1995-01-01

Many manufacturers and users claim that optical coatings are best prepared by physical vapor deposition technology. Others believe that sol-gel technology is an effective and competitive alternative. This article, the first of three, emphasizes sol-gel thin-film history and relates it to high-power laser technology, chemistry of the sol-gel process, production of optical coatings and deposition techniques. The second and third articles describe the preparation and performance of antireflective and highly reflective sol-gel optical coatings, respectively, that have been developed for the 1.8-MJ/500-TW (351-nm) pulsed neodymium-glass laser. This powerful laser is to be used in France's Inertial Confinement Fusion (ICF) program. It will demonstrate, at the laboratory scale, ignition of deuterium-tritium fusion fuel
Self-Healing Corrosion Protective Sol-Gel Coatings

NARCIS (Netherlands)

Abdolah Zadeh, M.

2016-01-01

Inspired by the state of the art and the recent advances in the field of self-healing corrosion protective coatings, the thesis entitled “Self-healing corrosion protective sol-gel coatings” addresses novel routes to self-healing corrosion protective sol-gel coatings via extrinsic and intrinsic
Efficiency Analysis of Solar Facilities for Building Heating and Household Water Heating Under Conditions in the Czech Republic / Analýza Efektivity Solárnych Zariadení Pre Ohrev Úžitkovej Vody A Vykurovanie Budov V Podmienkach Českej Republiky

Directory of Open Access Journals (Sweden)

Pivko Michal

2012-10-01

Full Text Available Štúdia v tomto článku sa zaoberá efektivitou solárnych zariadení pre ohrev úžitkovej vody a vykurovanie budov v Českej republike. Česká republika je situovaná v miernom podnebnom pásme, to by malo byť brané do úvahy pri inštalácii solárnych zariadení. Efektivita solárnych zariadení je hodnotená podľa energetických a ekonomických bilancií. Analyzované sú solárne zariadenia pre ohrev úžitkovej vody a vykurovanie budov. Hlavný problém súvisí s implementáciou solárnych zariadení a ich prevádzka v miernom podnebnom pásme so striedajúcimi sa horúcimi letami a chladnými zimami.
Electrochemical behaviour of ceramic yttria stabilized zirconia on carbon steel synthesized via sol-gel process

International Nuclear Information System (INIS)

Crespo, M.A. Dominguez; Murillo, A. Garcia; Torres-Huerta, A.M.; Yanez-Zamora, C.; Carrillo-Romo, F. de J

2009-01-01

Chromate conversion coatings have been widely applied for the corrosion of different metallic substrates. However, the waste containing Cr 6+ has many limitations due to the environmental consideration and health hazards. An interesting alternative seems to be the deposition on metallic surface of thin layers of yttria or zirconia or both by the sol-gel process. In this study, Ytttria and Yttria stabilized zirconia (YSZ, 8% Y 2 O 3 ) thin films were used for coating commercial carbon steel substrates by sol-gel method and the dip-coating process. The evolution of organic compounds up to crystallization process as a function of heat treatments was study by FT-IR spectroscopy. The structure and morphology of the coatings were analysed using X-ray diffraction (XRD) and scanning electron microscopy (SEM). The anticorrosion performance of the coatings has been evaluated by using electrochemical techniques in an aggressive media (3.5 wt.% NaCl). The corrosion behaviour of sol-gel method was compared with traditional chromate conversion coatings. Differences in the electrochemical behaviour of YSZ coatings are related to the development of microcracks during the sintering process and to the presence of organic compounds during growth film. Electrochemical results showed that sol-gel YSZ and Y 2 O 3 coatings can act as protective barriers against wet corrosion; however yttria films displayed low adhesion to substrate. The corrosion parameters provide an explanation of the role of each film and show a considerable increase in the corrosion resistance for coated samples in comparison to the bare steel samples.
Electrochemical behaviour of ceramic yttria stabilized zirconia on carbon steel synthesized via sol-gel process

Energy Technology Data Exchange (ETDEWEB)

Crespo, M.A. Dominguez, E-mail: mdominguezc@ipn.m [Centro de Investigacion en Ciencia Aplicada y Tecnologia Avanzada, Unidad Altamira (CICATA-IPN) km 14.5 Carr. Tampico-Puerto Industrial, C.P. 89600, Altamira, Tamaulipas (Mexico); Murillo, A. Garcia; Torres-Huerta, A.M. [Centro de Investigacion en Ciencia Aplicada y Tecnologia Avanzada, Unidad Altamira (CICATA-IPN) km 14.5 Carr. Tampico-Puerto Industrial, C.P. 89600, Altamira, Tamaulipas (Mexico); Yanez-Zamora, C. [Estudiante del postgrado en Tecnologia Avanzada del CICATA-IPN, Unidad Altamira, km 14.5, Carr. Tampico-Puerto Industrial. C.P. 89600, Altamira, Tamaulipas (Mexico); Carrillo-Romo, F. de J [Centro de Investigacion en Ciencia Aplicada y Tecnologia Avanzada, Unidad Altamira (CICATA-IPN) km 14.5 Carr. Tampico-Puerto Industrial, C.P. 89600, Altamira, Tamaulipas (Mexico)

2009-08-26

Chromate conversion coatings have been widely applied for the corrosion of different metallic substrates. However, the waste containing Cr{sup 6+} has many limitations due to the environmental consideration and health hazards. An interesting alternative seems to be the deposition on metallic surface of thin layers of yttria or zirconia or both by the sol-gel process. In this study, Ytttria and Yttria stabilized zirconia (YSZ, 8% Y{sub 2}O{sub 3}) thin films were used for coating commercial carbon steel substrates by sol-gel method and the dip-coating process. The evolution of organic compounds up to crystallization process as a function of heat treatments was study by FT-IR spectroscopy. The structure and morphology of the coatings were analysed using X-ray diffraction (XRD) and scanning electron microscopy (SEM). The anticorrosion performance of the coatings has been evaluated by using electrochemical techniques in an aggressive media (3.5 wt.% NaCl). The corrosion behaviour of sol-gel method was compared with traditional chromate conversion coatings. Differences in the electrochemical behaviour of YSZ coatings are related to the development of microcracks during the sintering process and to the presence of organic compounds during growth film. Electrochemical results showed that sol-gel YSZ and Y{sub 2}O{sub 3} coatings can act as protective barriers against wet corrosion; however yttria films displayed low adhesion to substrate. The corrosion parameters provide an explanation of the role of each film and show a considerable increase in the corrosion resistance for coated samples in comparison to the bare steel samples.
Sol-gel based oxidation catalyst and coating system using same

Science.gov (United States)

Watkins, Anthony N. (Inventor); Leighty, Bradley D. (Inventor); Oglesby, Donald M. (Inventor); Patry, JoAnne L. (Inventor); Schryer, Jacqueline L. (Inventor)

2010-01-01

An oxidation catalyst system is formed by particles of an oxidation catalyst dispersed in a porous sol-gel binder. The oxidation catalyst system can be applied by brush or spray painting while the sol-gel binder is in its sol state.
The physics of transport barrier formation in the PBX-M H-mode

International Nuclear Information System (INIS)

Tynan, G.R.; Schmitz, L.; Blush, L.

1994-01-01

Measurements of edge profiles, turbulence, and turbulent-driven transport were made inside the last-closed flux surface (LCFS) and in the scrape-off layer (SOL) of PBX-M L-mode and H-mode plasmas using a fast reciprocating Langmuir probe diagnostic. Direct measurements of the potential profile confirm the generation of a strong inward radial electric field (E r ∼ -100 V/cm) just inside the LCFS in H-mode. Density and potential fluctuations levels are reduced at the L-H transition, resulting in significantly lower turbulent transport. The reduction in turbulent transport occurs across the LCFS and SOL regions and is not localized to the region of strong radial electric field. (author)
Fast temperature fluctuation measurements in SOL of tokamak TCV

DEFF Research Database (Denmark)

Horacek, J.; Nielsen, Anders Henry; Pitts, R.A.

to compare the statistical character of turbulence in the SOL particle flux on TCV with results from the 2D fluid electrostatic model ESEL [2][4]. Using results from the fast sweeping, similar comparisons can now be made with the fluctuating Te and will be described in this contribution. We also present...... basic statistics derived from the Te time series obtained at different radii in the SOL plasma and show, in particular, that the relationship between higher moments of the probability distribution function from both experimental and simulated Te’s may be well described by the Beta probability...... distribution function, introduced for SOL turbulence in [5]. The fast Te capability also allows the SOL response to Edge Localised Modes (ELMs) to be studied and new results will be presented for the far SOL Te response during Type III ELMs....
Separations using biological carriers immobilized in porous polymeric and sol-gel template synthesized nanotubular membranes

Science.gov (United States)

Lakshmi, Brinda B.

1998-12-01

The overall goal of the dissertation was to use immobilized biological carriers in membranes to separate compounds as challenging as enantiomers. The membranes were prepared by a process called 'template synthesis'. Template synthesis has been used to synthesize semiconductor nanostructures and also membranes which do the enantioseparation by a process called facilitated transport. The immobilized proteins act as carriers facilitating the transport of the substrate molecules through the membrane. The apoenzymes are enzymes devoid of cofactor. Apoenzymes will possess the molecular recognition site for the substrate but will not catalyze the reaction. Apoenzymes immobilized in the pores of porous polycarbonate membrane was used as a carrier. The ends of the pores were closed with porous polypyrrole. Compounds as interesting as enantiomers were separated with these membranes. Template synthesis has been extended to the synthesis of many important semiconductor oxide naostructures like TiO2, SiO2, ZnO, Co3O4 and MnO2. These structures were made by dipping the alumina template membrane in the sol and heating. Ti0 2 tubules and fibers were obtained by this method. The fibers were used to study photocatalysis reaction of organic compounds in sunlight. Proteins were immobilized within the inner surface of the tubules using Sn chemistry. Bovine serum albumn (BSA) immobilized within the different diameter tubules showed varying degree of facilitation with phenylalanine. The membranes also show interesting switching of selectivity from L to D depending on the tube size and feed concentration.
New insights into uranium (VI) sol-gel processing

International Nuclear Information System (INIS)

King, C.M.; Thompson, M.C.; Buchanan, B.R.; King, R.B.; Garber, A.R.

1990-01-01

Nuclear Magnetic Resonance (NMR) investigations on the Oak Ridge National Laboratory process for sol-gel synthesis of microspherical nuclear fuel (UO 2 ), has been extremely useful in sorting out the chemical mechanism in the sol-gel steps. 13 C, 15 N, and 1 H NMR studies on the HMTA gelation agent (Hexamethylene tetramine, C 6 H 12 N 4 ) has revealed near quantitative stability of this adamantane-like compound in the sol-gel process, contrary to its historical role as an ammonia source for gelation from the worldwide technical literature. 17 O NMR of uranyl (UO 2 ++ ) hydrolysis fragments produced in colloidal sols has revealed the selective formation of a uranyl trimer, [(UO 2 ) 3 (μ 3 -O)(μ 2 -OH) 3 ] + , induced by basic hydrolysis with the HMTA gelation agent. Spectroscopic results will be presented to illustrate that trimer condensation occurs during sol-gel processing leading to layered polyanionic hydrous uranium oxides in which HMTAH + is occluded as an ''intercalation'' cation. Subsequent sol-gel processing of microspheres by ammonia washing results in in-situ exchange and formation of a layered hydrous ammonium uranate with a proposed structural formula of (NH 4 ) 2 [(UO 2 ) 8 O 4 (OH) 10 ] · 8H 2 O. This compound is the precursor to sintered UO 2 ceramic fuel. 23 refs., 10 figs

Diffusive-to-ballistic transition of the modulated heat transport in a rarefied air chamber

Directory of Open Access Journals (Sweden)

C. L. Gomez-Heredia

2017-01-01

Full Text Available Modulated heat transfer in air subject to pressures from 760 Torr to 10-4 Torr is experimentally studied by means of a thermal-wave resonant cavity placed in a vacuum chamber. This is done through the analysis of the amplitude and phase delay of the photothermal signal as a function of the cavity length and pressure through of the Knudsen’s number. The viscous, transitional, and free molecular regimes of heat transport are observed for pressures P>1.5 Torr, 25 mTorrheat transport.
[Basic Studies on Locoregional Injection of a Newly Designed Chitin Sol].

Science.gov (United States)

Chiba, Takehiro; Sugitachi, Akio; Kume, Kouhei; Segawa, Takenori; Nishinari, Yutaka; Ishida, Kaoru; Noda, Hironobu; Nishizuka, Satoshi; Kimura, Yusuke; Koeda, Keisuke; Sasaki, Akira

2015-11-01

Systemic chemotherapy in advanced cancer cases often provokes serious adverse events. We aimed to examine the fundamental properties and efficacy of a novel chitin sol, an anti-cancer agent with minor side effects designed to avoid the adverse effects of chemotherapy and enhance the QOL and ADL of patients. DAC-70 was used to create the novel agent termed DAC-70 sol. The anti-proliferative activity was assayed by the WST method using different types of cell lines. The anti-cancer efficacy of the novel agent was examined using cancer-bearing mice. DAC-70 sol was easily injectable through a 21-G needle. The sol suppressed proliferation of the cells in vitro. Intra-tumor injection of DAC-70 sol inhibited the rapid growth of solid tumors in the mice. CDDP-loaded DAC-70 sol, CDDP/DAC-70 sol, successfully controlled malignant ascites in the mice (psol and CDDP/DAC-70 sol is clinically useful as novel cancer chemotherapy for advanced cases. This warrants further clinical studies in cancer chemotherapy.
Radiation hardening in sol-gel derived Er3+-doped silica glasses

International Nuclear Information System (INIS)

Hari Babu, B.; León Pichel, Mónica; Ollier, Nadège; El Hamzaoui, Hicham; Bigot, Laurent; Savelii, Inna; Bouazaoui, Mohamed; Poumellec, Bertrand; Lancry, Matthieu; Ibarra, Angel

2015-01-01

The aim of the present paper is to report the effect of radiation on the Er 3+ -doped sol-gel silica glasses. A possible application of these sol-gel glasses could be their use in harsh radiation environments. The sol-gel glasses are fabricated by densification of erbium salt-soaked nanoporous silica xerogels through polymeric sol-gel technique. The radiation-induced attenuation of Er 3+ -doped sol-gel silica is found to increase with erbium content. Electron paramagnetic resonance studies reveal the presence of E′ δ point defects. This happens in the sol-gel aluminum-silica glass after an exposure to γ-rays (kGy) and in sol-gel silica glass after an exposure to electrons (MGy). The concentration levels of these point defects are much lower in γ-ray irradiated sol-gel silica glasses. When the samples are co-doped with Al, the exposure to γ-ray radiation causes a possible reduction of the erbium valence from Er 3+ to Er 2+ ions. This process occurs in association with the formation of aluminum oxygen hole centers and different intrinsic point defects
Silica scintillating materials prepared by sol-gel methods

International Nuclear Information System (INIS)

Werst, D.W.; Sauer, M.C. Jr.; Cromack, K.R.; Lin, Y.; Tartakovsky, E.A.; Trifunac, A.D.

1993-01-01

Silica was investigated as a rad-hard alternative to organic polymer hosts for organic scintillators. Silica sol-gels were prepared by hydrolysis of tetramethoxysilane in alcohol solutions. organic dyes were incorporated into the gels by dissolving in methanol at the sol stage of gel formation. The silica sol-gel matrix is very rad-hard. The radiation stability of silica scintillators prepared by this method is dye-limited. Transient radioluminescence was measured following excitation with 30 ps pulses of 20 MeV electrons
Effective Heat and Mass Transport Properties of Anisotropic Porous Ceria for Solar Thermochemical Fuel Generation

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Sophia Haussener

2012-01-01

Full Text Available High-resolution X-ray computed tomography is employed to obtain the exact 3D geometrical configuration of porous anisotropic ceria applied in solar-driven thermochemical cycles for splitting H2O and CO2. The tomography data are, in turn, used in direct pore-level numerical simulations for determining the morphological and effective heat/mass transport properties of porous ceria, namely: porosity, specific surface area, pore size distribution, extinction coefficient, thermal conductivity, convective heat transfer coefficient, permeability, Dupuit-Forchheimer coefficient, and tortuosity and residence time distributions. Tailored foam designs for enhanced transport properties are examined by means of adjusting morphologies of artificial ceria samples composed of bimodal distributed overlapping transparent spheres in an opaque medium.
La microflore des sols du vignoble de Touraine

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Claude Cuinier

1975-12-01

Full Text Available L'étude microbiologique des sols du vignoble porte sur trois années. Les déterminations quantitatives des bactéries, champignons, actinomycètes et des groupes fonctionnels des cycles de l'azote, du carbone et du soufre sont effectuées au cours de trois périodes du cycle végétatif de la vigne. Des variations saisonnières et annuelles sont observées. La microflore des sols viticoles est comparée à celle d'autres sols. Elle est au moins aussi riche et se distingue par son caractère plus aérobie. De grands écarts dans la composition microbiologique sont apparus entre des sols viticoles différant par leurs caractéristiques physiques et chimiques.
NON-LINEAR TRANSIENT HEAT CONDUCTION ANALYSIS OF INSULATION WALL OF TANK FOR TRANSPORTATION OF LIQUID ALUMINUM

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Miroslav M Živković

2010-01-01

Full Text Available This paper deals with transient nonlinear heat conduction through the insulation wall of the tank for transportation of liquid aluminum. Tanks designed for this purpose must satisfy certain requirements regarding temperature of loading and unloading, during transport. Basic theoretical equations are presented, which describe the problem of heat conduction finite element (FE analysis, starting from the differential equation of energy balance, taking into account the initial and boundary conditions of the problem. General 3D problem for heat conduction is considered, from which solutions for two- and one-dimensional heat conduction can be obtained, as special cases. Forming of the finite element matrices using Galerkin method is briefly described. The procedure for solving equations of energy balance is discussed, by methods of resolving iterative processes of nonlinear transient heat conduction. Solution of this problem illustrates possibilities of PAK-T software package, such as materials properties, given as tabular data, or analytical functions. Software also offers the possibility to solve nonlinear and transient problems with incremental methods. Obtained results for different thicknesses of the tank wall insulation materials enable its comparison in regards to given conditions
Crossover from ballistic to normal heat transport in the ϕ4 lattice: If nonconservation of momentum is the reason, what is the mechanism?

Science.gov (United States)

Xiong, Daxing; Saadatmand, Danial; Dmitriev, Sergey V.

2017-10-01

Anomalous (non-Fourier) heat transport is no longer just a theoretical issue since it has been observed experimentally in a number of low-dimensional nanomaterials, such as SiGe nanowires, carbon nanotubes, and others. To understand these anomalous behaviors, exploring the microscopic origin of normal (Fourier) heat transport is a fascinating theoretical topic. However, this issue has not yet been fully understood even for one-dimensional (1D) model chains, in spite of a great amount of thorough studies done to date. From those studies, it has been widely accepted that the conservation of momentum is a key ingredient to induce anomalous heat transport, while momentum-nonconserving systems usually support normal heat transport where Fourier's law is valid. But if the nonconservation of momentum is the reason, what is the underlying microscopic mechanism for the observed normal heat transport? Here we carefully revisit a typical 1D momentum-nonconserving ϕ4 model, and we present evidence that the mobile discrete breathers, or, in other words, the moving intrinsic localized modes with frequency components above the linear phonon band, can be responsible for that.
Structure changes in the sol-gel systems of hydrated oxides

International Nuclear Information System (INIS)

Gaponov, Y.A.; Karakchiev, L.G.; Lyakhov, N.Z.; Tolochko, B.P.; Ito, K.; Amemiya, Y.

1998-01-01

Sols of hydrated aluminium oxide, hydrated zirconium oxide and their mixtures were investigated during the xerogel-amorphous-product-crystalline-product transition by SAXS using synchrotron radiation. In the different temperature regions certain changes in structure and morphology were observed. Some correlation between the characteristics of the initial sols and their mixtures (the size and shape of the pores) was observed. In the temperature region 298-1173 K the characteristics of the mixed sol are defined by the characteristics of the initial sols
Biocatalysis with Sol-Gel Encapsulated Acid Phosphatase

Science.gov (United States)

Kulkarni, Suhasini; Tran, Vu; Ho, Maggie K.-M.; Phan, Chieu; Chin, Elizabeth; Wemmer, Zeke; Sommerhalter, Monika

2010-01-01

This experiment was performed in an upper-level undergraduate biochemistry laboratory course. Students learned how to immobilize an enzyme in a sol-gel matrix and how to perform and evaluate enzyme-activity measurements. The enzyme acid phosphatase (APase) from wheat germ was encapsulated in sol-gel beads that were prepared from the precursor…
Influence of low-order rational magnetic surfaces on heat transport in TJ-II heliac ECRH plasmas

International Nuclear Information System (INIS)

Castejon, F.; Lopez-Bruna, D.; Estrada, T.; Ascasibar, E.; Zurro, B.; Baciero, A.

2004-01-01

We study the effect of low-order rational surfaces on electron heat transport in plasmas confined in the TJ-II stellarator (Alejaldre et al 1990 Fusion Technol. 17 131) and heated by electron cyclotron waves. Enhancement of core electron heat confinement is observed when the rational surface is placed in the vicinity of the power deposition zone, either by performing a magnetic configuration scan or by inducing Ohmic current in a single discharge. The key to improving heat confinement seems to be a locally strong positive radial electric field, which is made possible by a synergistic effect between enhanced electron heat fluxes through radial positions around low-order rationals and pump out mechanisms in the heat deposition zone. (author)
Energy Conversion Advanced Heat Transport Loop and Power Cycle

Energy Technology Data Exchange (ETDEWEB)

Oh, C. H.

2006-08-01

The Department of Energy and the Idaho National Laboratory are developing a Next Generation Nuclear Plant (NGNP) to serve as a demonstration of state-of-the-art nuclear technology. The purpose of the demonstration is two fold 1) efficient low cost energy generation and 2) hydrogen production. Although a next generation plant could be developed as a single-purpose facility, early designs are expected to be dual-purpose. While hydrogen production and advanced energy cycles are still in its early stages of development, research towards coupling a high temperature reactor, electrical generation and hydrogen production is under way. Many aspects of the NGNP must be researched and developed in order to make recommendations on the final design of the plant. Parameters such as working conditions, cycle components, working fluids, and power conversion unit configurations must be understood. Three configurations of the power conversion unit were demonstrated in this study. A three-shaft design with 3 turbines and 4 compressors, a combined cycle with a Brayton top cycle and a Rankine bottoming cycle, and a reheated cycle with 3 stages of reheat were investigated. An intermediate heat transport loop for transporting process heat to a High Temperature Steam Electrolysis (HTSE) hydrogen production plant was used. Helium, CO2, and an 80% nitrogen, 20% helium mixture (by weight) were studied to determine the best working fluid in terms cycle efficiency and development cost. In each of these configurations the relative component size were estimated for the different working fluids. The relative size of the turbomachinery was measured by comparing the power input/output of the component. For heat exchangers the volume was computed and compared. Parametric studies away from the baseline values of the three-shaft and combined cycles were performed to determine the effect of varying conditions in the cycle. This gives some insight into the sensitivity of these cycles to various
Relationship between particle and heat transport in JT-60U plasmas with internal transport barrier

International Nuclear Information System (INIS)

Takenaga, H.

2002-01-01

Relationship between particle and heat transport in an internal transport barrier (ITB) has been systematically investigated for the first time in reversed shear (RS) and high-β p ELMy H-mode (weak positive shear) plasmas of JT-60U for understanding of compatibility of improved energy confinement and effective particle control such as exhaust of helium ash and reduction in impurity contamination. In the RS plasma, no helium and carbon accumulation inside the ITB is observed even with highly improved energy confinement. In the high-β p plasma, both helium and carbon density profiles are flat. As the ion temperature profile changes from parabolic- to box-type, the helium diffusivity decreases by a factor of about 2 as well as the ion thermal diffusivity in the RS plasma. The measured soft X-ray profile is more peaked than that calculated by assuming the same n AR profile as the n e profile in the Ar injected RS plasma with the box-type profile, suggesting accumulation of Ar inside the ITB. Particle transport is improved with no change of ion temperature in the RS plasma, when density fluctuation is drastically reduced by a pellet injection. (author)
Preparation and characterization of sol-gel derived TiO2 films

International Nuclear Information System (INIS)

Hong, Y.J.; Brungs, M.P.; Chaplin, R.P.; Sizgek, E.

2001-01-01

Crack-free transparent titania films have been prepared through a new sol-gel process combined with hydrogen peroxide treatment. Hydrogen peroxide and HCl were used to dissolve amorphous titania powder which is obtained by drying common sol-gel titania sol. The peroxo-titania sol produced a thicker film than the common sol-gel titania sol due to a higher degree of condensation. Film thickness could be further increased by controlled drying conditions of the amorphous titania powder or 'aging' the sol. Polyethylene glycol (PEG) and chemical additives were effective in controlling condensation rate by preventing rapid condensation during curing of the film. When these two components were incorporated, it was possible to create a 0.5μm transparent film and PEG could also control the porosity of the film. The cured film was analysed by XRD and Raman spectroscopy. In order to measure the reflective index and thickness of the titania film, an ellipsometer was used. Copyright (2001) The Australian Ceramic Society
ITO/Poly(Aniline/Sol-Gel Glass: An Optically Transparent, pH-Responsive Substrate for Supported Lipid Bilayers

Directory of Open Access Journals (Sweden)

Ahmed Al-Obeidi

2013-01-01

Full Text Available Described here is fabrication of a pH-sensitive, optically transparent transducer composed of a planar indium-tin oxide (ITO electrode overcoated with a poly(aniline (PANI thin film and a porous sol-gel layer. Adsorption of the PANI film renders the ITO electrode sensitive to pH, whereas the sol-gel spin-coated layer makes the upper surface compatible with fusion of phospholipid vesicles to form a planar supported lipid bilayer (PSLB. The response to changes in the pH of the buffer contacting the sol-gel/PANI/ITO electrode is pseudo-Nernstian with a slope of 52 mV/pH over a pH range of 4–9. Vesicle fusion forms a laterally continuous PSLB on the upper sol-gel surface that is fluid with a lateral lipid diffusion coefficient of 2.2 μm2/s measured by fluorescence recovery after photobleaching. Due to its lateral continuity and lack of defects, the PSLB blocks the pH response of the underlying electrode to changes in the pH of the overlying buffer. This architecture is simpler to fabricate than previously reported ITO electrodes derivatized for PSLB formation and should be useful for optical monitoring of proton transport across supported membranes derivatized with ionophores and ion channels.
Silica- and germania-based dual-ligand sol-gel organic-inorganic hybrid sorbents combining superhydrophobicity and π-π interaction. The role of inorganic substrate in sol-gel capillary microextraction.

Science.gov (United States)

Seyyal, Emre; Malik, Abdul

2017-04-29

Principles of sol-gel chemistry were utilized to create silica- and germania-based dual-ligand surface-bonded sol-gel coatings providing enhanced performance in capillary microextraction (CME) through a combination of ligand superhydrophobicity and π-π interaction. These organic-inorganic hybrid coatings were prepared using sol-gel precursors with bonded perfluorododecyl (PF-C 12 ) and phenethyl (PhE) ligands. Here, the ability of the PF-C 12 ligand to provide enhanced hydrophobic interaction was advantageously combined with π-π interaction capability of the PhE moiety to attain the desired sorbent performance in CME. The effect of the inorganic sorbent component on microextraction performance of was explored by comparing microextraction characteristics of silica- and germania-based sol-gel sorbents. The germania-based dual-ligand sol-gel sorbent demonstrated superior CME performance compared to its silica-based counterpart. Thermogravimetric analysis (TGA) of the created silica- and germania-based dual-ligand sol-gel sorbents suggested higher carbon loading on the germania-based sorbent. This might be indicative of more effective condensation of the organic ligand-bearing sol-gel-active chemical species to the germania-based sol-gel network (than to its silica-based counterpart) evolving in the sol solution. The type and concentration of the organic ligands were varied in the sol-gel sorbents to fine-tune extraction selectivity toward different classes of analytes. Specific extraction (SE) values were used for an objective comparison of the prepared sol-gel CME sorbents. The sorbents with higher content of PF-C 12 showed remarkable affinity for aliphatic hydrocarbons. Compared to their single-ligand sol-gel counterparts, the dual-ligand sol-gel coatings demonstrated significantly superior CME performance in the extraction of alkylbenzenes, providing up to ∼65.0% higher SE values. The prepared sol-gel CME coatings provided low ng L -1 limit of detections (LOD
Vertical transport of water in the Martian boundary layer

Science.gov (United States)

Zent, Aaron P.; Haberle, R. M.; Houben, Howard C.

1993-01-01

We are continuing our examination of the transport of H2O through the martian boundary layer, and we have written a one-dimensional numerical model of the exchange of H2O between the atmosphere and subsurface of Mars through the planetary boundary layer (PBL). Our goal is to explore the mechanisms of H2O exchange, and to elucidate the role played by the regolith in the local H2O budget. The atmospheric model includes effects of Coriolis, pressure gradient, and frictional forces for momentum, as well as radiation, sensible heat flux, and advection for heat. The model differs from Flasar and Goody by use of appropriate Viking-based physical constants and inclusion of the radiative effects of atmospheric dust. We specify the pressure gradient force or compute it from a simple slope model. The subsurface model accounts for conduction of heat and diffusion of H2O through a porous adsorbing medium in response to diurnal forcing. The model is initialized with depth-independent H2O concentrations (2 kg M(exp -3)) in the regolith, and a dry atmosphere. The model terminates when the atmospheric H2O column abundance stabilizes at 0.1 percent per sol.
Finite speed heat transport in a quantum spin chain after quenched local cooling

Science.gov (United States)

Fries, Pascal; Hinrichsen, Haye

2017-04-01

We study the dynamics of an initially thermalized spin chain in the quantum XY-model, after sudden coupling to a heat bath of lower temperature at one end of the chain. In the semi-classical limit we see an exponential decay of the system-bath heatflux by exact solution of the reduced dynamics. In the full quantum description however, we numerically find the heatflux to reach intermediate plateaus where it is approximately constant—a phenomenon that we attribute to the finite speed of heat transport via spin waves.
Anion embedded sol-gel films on Al for corrosion protection

International Nuclear Information System (INIS)

Sheffer, Mari; Groysman, Alec; Starosvetsky, David; Savchenko, Natali; Mandler, Daniel

2004-01-01

We report here on the successful incorporation of organic anions into a sol-gel film on Al as a means of enhancing the protection against corrosion. Following our previous study where we showed that hydrophobic sol-gel films provided pronounced corrosion inhibition, we studied the corrosion inhibition that phenylphosphonic acid (PPA) has when embedded inside a thin sol-gel coating on Al. The anion of this organic anion tends to stay inside a phenyltrimethoxysilane (PTMOS) based sol-gel film due to π-interactions. Our findings, which are derived primarily from potentiodynamic polarization measurements, electrochemical noise, scanning electron microscopy measurements and Auger electron spectroscopy (AES), clearly show that the organic phosphonate adds to the protection efficiency of the sol-gel film
Sol-Gel Manufactured Energetic Materials

Science.gov (United States)

Simpson, Randall L.; Lee, Ronald S.; Tillotson, Thomas M.; Hrubesh, Lawrence W.; Swansiger, Rosalind W.; Fox, Glenn A.

2005-05-17

Sol-gel chemistry is used for the preparation of energetic materials (explosives, propellants and pyrotechnics) with improved homogeneity, and/or which can be cast to near-net shape, and/or made into precision molding powders. The sol-gel method is a synthetic chemical process where reactive monomers are mixed into a solution, polymerization occurs leading to a highly cross-linked three dimensional solid network resulting in a gel. The energetic materials can be incorporated during the formation of the solution or during the gel stage of the process. The composition, pore, and primary particle sizes, gel time, surface areas, and density may be tailored and controlled by the solution chemistry. The gel is then dried using supercritical extraction to produce a highly porous low density aerogel or by controlled slow evaporation to produce a xerogel. Applying stress during the extraction phase can result in high density materials. Thus, the sol-gel method can be used for precision detonator explosive manufacturing as well as producing precision explosives, propellants, and pyrotechnics, along with high power composite energetic materials.

Effect of Sol Concentration, Aging and Drying Process on Cerium Stabilization Zirconium Gel Produced by External Gelation

Science.gov (United States)

Sukarsono, R.; Rachmawati, M.; Susilowati, S. R.; Husnurrofiq, D.; Nurwidyaningrum, K.; Dewi, A. K.

2018-02-01

to release the decomposition of the material during heating. Larger the concentration of nitric metal in sol solution, yields a gel with a larger diameter of gels. This research allows us to plan the diameter of the sintered particles to be made.
Spatially resolved speckle-correlometry of sol-gel transition

Science.gov (United States)

Isaeva, A. A.; Isaeva, E. A.; Pantyukov, A. V.; Zimnyakov, D. A.

2018-04-01

Sol-gel transition was studied using the speckle correlometry method with a localized light source and spatial filtering of backscattered radiation. Water solutions of technical or food gelatin with added TiO2 nanoparticles were used as studied objects. Structural transformation of "sol-gel" system was studied at various temperatures from 25°C to 50°C using analysis of the correlation and structure functions of speckle intensity fluctuations. The characteristic temperatures of "sol - gel" transition were evaluated for studied systems. Obtained results can be used for various applications in biomedicine and food industry.
Time for a Change; Spirit's View on Sol 1843

Science.gov (United States)

2009-01-01

NASA's Mars Exploration Rover Spirit used its navigation camera to take the images that have been combined into this full-circle view of the rover's surroundings during the 1,843rd Martian day, or sol, of Spirit's surface mission (March 10, 2009). South is in the middle. North is at both ends. The rover had driven 36 centimeters downhill earlier on Sol 1854, but had not been able to get free of ruts in soft material that had become an obstacle to getting around the northeastern corner of the low plateau called 'Home Plate.' The Sol 1854 drive, following two others in the preceding four sols that also achieved little progress in the soft ground, prompted the rover team to switch to a plan of getting around Home Plate counterclockwise, instead of clockwise. The drive direction in subsequent sols was westward past the northern edge of Home Plate. This view is presented as a cylindrical projection with geometric seam correction.
Abstracts of International Conference on Sol-Gel Materials' 04

International Nuclear Information System (INIS)

2004-01-01

International Conference on Sol-Gel Materials '04 was an important forum for discussion on problems related to sol-gel processes applied for preparation materials with special physical properties and assignment. The application of sol-gel materials as phosphors, surface coatings, sensors, waveguides, medical implants, joints etc. has been presented. Preparation conditions, methods of physical characterization as well as optimal chemical composition of such materials have been also discussed in detail
Characterization of ion heat conduction in JET and ASDEX Upgrade plasmas with and without internal transport barriers

Energy Technology Data Exchange (ETDEWEB)

Wolf, R C [Institut fuer Plasmaphysik, Forschungszentrum Juelich, Association EURATOM/FZJ, Trilateral Euregio Cluster, D-52425 Juelich (Germany); Baranov, Y [UKAEA/EURATOM Fusion Association, Culham Science Centre, Abingdon, OX14 3DB (United Kingdom); Garbet, X [Association EURATOM-CEA sur la fusion, CEA Cadarache, F-13108 St Paul lez Durance (France); Hawkes, N [UKAEA/EURATOM Fusion Association, Culham Science Centre, Abingdon, OX14 3DB (United Kingdom); Peeters, A G [Max-Planck-Institut fuer Plasmaphysik, EURATOM-Assoziation, D-85748 Garching (Germany); Challis, C [UKAEA/EURATOM Fusion Association, Culham Science Centre, Abingdon, OX14 3DB (United Kingdom); Baar, M de [FOM Instituut voor Plasmafyisica Rijnhuizen, Association EURATO-FOM, Trilateral Euregio Cluster, PO Box 1207, 3430 BE Nieuwegein (Netherlands); Giroud, C [FOM Instituut voor Plasmafyisica Rijnhuizen, Association EURATO-FOM, Trilateral Euregio Cluster, PO Box 1207, 3430 BE Nieuwegein (Netherlands); Joffrin, E [Association EURATOM-CEA sur la fusion, CEA Cadarache, F-13108 St Paul lez Durance (France); Mantsinen, M [Helsinki University of Technology, Association-EURATOM Tekes, FIN-02015 HUT (Finland); Mazon, D [Association EURATOM-CEA sur la fusion, CEA Cadarache, F-13108 St Paul lez Durance (France); Meister, H [Max-Planck-Institut fuer Plasmaphysik, EURATOM-Assoziation, D-85748 Garching (Germany); Suttrop, W [Max-Planck-Institut fuer Plasmaphysik, EURATOM-Assoziation, D-85748 Garching (Germany); Zastrow, K-D [UKAEA/EURATOM Fusion Association, Culham Science Centre, Abingdon, OX14 3DB (United Kingdom)

2003-09-01

In ASDEX Upgrade and JET, the ion temperature profiles can be described by R/L{sub Ti} which exhibits only little variations, both locally, when comparing different discharges, and radially over a wide range of the poloidal cross-section. Considering a change of the local ion heat flux of more than a factor of two, this behaviour indicates some degree of profile stiffness. In JET, covering a large ion temperature range from 1 to 25 keV, the normalized ion temperature gradient, R/L{sub Ti}, shows a dependence on the electron to ion temperature ratio or toroidal rotational shear. In particular, in hot ion plasmas, produced predominantly by neutral beam heating at low densities, in which large T{sub i}/T{sub e} is coupled to strong toroidal rotation, the effect of the two quantities cannot be distinguished. Both in ASDEX Upgrade and JET, plasmas with internal transport barriers (ITBs), including the PEP mode in JET, are characterized by a significant increase of R/L{sub Ti} above the value of L- and H-mode plasmas. In agreement with previous ASDEX Upgrade results, no increase of the ion heat transport in reversed magnetic shear ITB plasmas is found in JET when raising the electron heating. Evidence is presented that magnetic shear directly influences R/L{sub Ti}, namely decreasing the ion heat transport when going from weakly positive to negative magnetic shear.
Material and fabrication considerations for the CANDU-PHWR heat transport system

International Nuclear Information System (INIS)

Filipovic, A.; Price, E.G.; Barber, D.; Nickerson, J.

1987-03-01

CANDU PHWR nuclear systems have used carbon steel material for over 25 years. The accumulated operating experience of over 200 reactor years has proven this unique AECL approach to be both technically and economically attractive. This paper discusses design, material and fabrication considerations for out-reactor heat transport system major components. The contribution of this unique choice of materials and equipment to the outstanding CANDU performance is briefly covered
Impact of electro-magnetic stabilization, small- scale turbulence and multi-scale interactions on heat transport in JET

Science.gov (United States)

Mantica, Paola

2016-10-01

Heat transport experiments in JET, based on ICRH heat flux scans and temperature modulation, have confirmed the importance of two transport mechanisms that are often neglected in modeling experimental results, but are crucial to reach agreement between theory and experiment and may be significant in ITER. The first mechanism is the stabilizing effect of the total pressure gradient (including fast ions) on ITG driven ion heat transport. Such stabilization is found in non-linear gyro-kinetic electro-magnetic simulations using GENE and GYRO, and is the explanation for the observed loss of ion stiffness in the core of high NBI-power JET plasmas. The effect was recently observed also in JET plasmas with dominant ICRH heating and small rotation, due to ICRH fast ions, which is promising for ITER. Such mechanism dominates over ExB flow shear in the core and needs to be included in quasi-linear models to increase their ability to capture the relevant physics. The second mechanism is the capability of small- scale ETG instabilities to carry a significant fraction of electron heat. A decrease in Te peaking is observed when decreasing Zeff Te/Ti, which cannot be ascribed to TEMs but is in line with ETGs. Non-linear GENE single-scale simulations of ETGs and ITG/TEMs show that the ITG/TEM electron heat flux is not enough to match experiment. TEM stiffness is also much lower than measured. In the ETG single scale simulations the external flow shear is used to saturate the ETG streamers. Multi-scale simulations are ongoing, in which the ion zonal flows are the main saturating mechanism for ETGs. These costly simulations should provide the final answer on the importance of ETG-driven electron heat flux in JET. with JET contributors [F.Romanelli, Proc.25thIAEA FEC]. Supported by EUROfusion Grant 633053.
The development and characterization of sol-gel substrates for chemical and optical applications

Science.gov (United States)

Powers, Kevin William

1998-12-01

The sol gel process can be used to make monolithic porous glass for various scientific and engineering uses. The porosity of the material imparts a large surface area which is advantageous in applications such as catalyst supports or in the study of surface mediated chemical reactions. The chemical stability and transparency of the porous glass also make it suitable for use in the emerging field of optical sensors. In this study fluoride catalysis is used to produce sol gel monoliths with pore radii of up to 400 Angstroms, four times larger than any previously reported using conventional drying techniques. Gel monoliths with pore radii of 200 Angstroms were found to have the best combination of surface area, pore volume and optical transparency. Typical monoliths have surface areas of 150 m2/g and pore volumes of 1.60 cm3/g with good transparency. The monoliths are chemically stable, have good mechanical strength and can be easily rehydrated without cracking. The substrates are also suitable for sintering into dense high purity silica glass with little tendency towards foaming. An in-depth study of the catalytic effect of fluoride on the sol gel process is also included. It has been theorized that fluoride serves to expand the coordination sphere of the silicon center making it more subject to nucleophilic attack. In this work an ion-specific fluoride electrode is used to monitor free fluoride concentrations in HF catalyzed sols while silicic acid is added in the form of tetramethoxysilane (TMOS). It is found that fluoride is rapidly bound by the silicic acid in a ratio of four to one, indicating the formation of silicon tetrafluoride. A concurrent decrease in pH suggests that a pentacoordinate species is formed that is more stable than previously thought. A polymerization mechanism is proposed that explains the hydrophobicity of fluoride catalyzed gels and the difficulty in retaining structural fluoride in fluoride catalyzed sol gel glasses. Finally, several
Hybrid manganese oxide films for supercapacitor application prepared by sol-gel technique

International Nuclear Information System (INIS)

Chen, Chin-Yi; Wang, Sheng-Chang; Tien, Yue-Han; Tsai, Wen-Ta; Lin, Chung-Kwei

2009-01-01

Hybrid films were prepared by adding various concentrations of meso-carbon microbeads (MCMB) during sol-gel processing of manganese oxide films. The heat-treated films were characterized by scanning electron microscopy (SEM) and X-ray diffraction (XRD). In addition, electrochemical performance of the MCMB-added Mn-oxide hybrid coatings was evaluated by cyclic voltammetry (CV) and compared with its unadded counterpart. Experimental results showed that Mn-oxide films exhibited a mixture of Mn 2 O 3 and Mn 3 O 4 phases. The higher the heat-treatment temperature, the more Mn 2 O 3 can be observed. The specific capacitance of the unadded Mn-oxide electrodes is 209 F/g. Because the MCMB particles provide more interfacial surface area for electrochemical reactions, a significant improvement can be noticed by adding MCMB in Mn-oxide coatings. The 300 o C heat-treated hybrid Mn-oxide coating with a Mn/MCMB ratio of 10/1 exhibits the highest value of 350 F/g, showing a ∼ 170% increase in specific capacitance.
A model for a scrape-off-layer low-high (L-H) mode transition

International Nuclear Information System (INIS)

Cohen, R.H.; Xu, X.

1995-01-01

Increasing the radial mode number has a stabilizing effect on the conducting-wall and curvature-driven interchange modes in a tokamak scrape-off layer (SOL), arising from the increased polarization response. Such an effect is naturally imposed as the SOL width is decreased, and for a narrow-enough SOL, the stabilizing effect is stronger than the increase in the instability drives. By combining a mixing-length estimate for the thermal diffusivity with energy conservation and heat conduction equations and the condition of continuity of the heat flux at the separatrix, it is found that the resultant turbulence-transport system admits two solutions, one stable and one unstable, at different SOL widths; the inclusion of additional physics can add a second stable root at lower width. These roots are plausibly identified with SOL behavior in low (L) and high (H) modes. Particularly when a model is introduced for finite-β, finite-k parallel effects on the modes, a power threshold for transition to the narrower root is obtained, suggesting a possible L-H transition mechanism. The non-monotonic dependence of the turbulent heat flux vs SOL width and the possibility of multiple solutions for the equilibrium SOL width are verified with nonlinear simulations. copyright 1995 American Institute of Physics
Transition to ballistic regime for heat transport in helium II

Energy Technology Data Exchange (ETDEWEB)

Sciacca, Michele, E-mail: michele.sciacca@unipa.it [Dipartimento Scienze Agrarie e Forestali, Università degli studi di Palermo, Viale delle Scienze, 90128 Palermo (Italy); Departament de Física, Universitat Autònoma de Barcelona, 08193 Bellaterra, Catalonia (Spain); Sellitto, Antonio, E-mail: ant.sellitto@gmail.com [Dipartimento di Matematica, Informatica ed Economia, Università della Basilicata, Campus Macchia Romana, 85100 Potenza (Italy); Jou, David, E-mail: david.jou@uab.cat [Departament de Física, Universitat Autònoma de Barcelona, 08193 Bellaterra, Catalonia (Spain); Institut d' Estudis Catalans, Carme 47, 08001 Barcelona, Catalonia (Spain)

2014-07-04

The size-dependent and flux-dependent effective thermal conductivity of narrow capillaries filled with superfluid helium is analyzed from a thermodynamic continuum perspective. The classical Landau evaluation of the effective thermal conductivity of quiescent superfluid, or the Gorter–Mellinck regime of turbulent superfluids, is extended to describe the transition to ballistic regime in narrow channels wherein the radius R is comparable to (or smaller than) the phonon mean-free path ℓ in superfluid helium. To do so, we start from an extended equation for the heat flux incorporating non-local terms, and take into consideration a heat slip flow along the walls of the tube. This leads from an effective thermal conductivity proportional to R{sup 2} (Landau regime) to another one proportional to Rℓ (ballistic regime). We consider two kinds of flows: along cylindrical pipes and along two infinite parallel plates. - Highlights: • Heat transport in counterflow helium in the ballistic regime. • The one-fluid model based on the Extended Thermodynamics is used. • The transition from the Landau regime to the ballistic regime. • The transition from quantum turbulence to ballistic regime.
Ab-initio quantum transport simulation of self-heating in single-layer 2-D materials

Science.gov (United States)

Stieger, Christian; Szabo, Aron; Bunjaku, Teutë; Luisier, Mathieu

2017-07-01

Through advanced quantum mechanical simulations combining electron transport and phonon transport from first-principles, self-heating effects are investigated in n-type transistors with single-layer MoS2, WS2, and black phosphorus as channel materials. The selected 2-D crystals all exhibit different phonon-limited mobility values, as well as electron and phonon properties, which have a direct influence on the increase in their lattice temperature and on the power dissipated inside their channel as a function of the applied gate voltage and electrical current magnitude. This computational study reveals (i) that self-heating plays a much more important role in 2-D materials than in Si nanowires, (ii) that it could severely limit the performance of 2-D devices at high current densities, and (iii) that black phosphorus appears less sensitive to this phenomenon than transition metal dichalcogenides.
Opportunity's Surroundings on Sol 1818

Science.gov (United States)

2009-01-01

NASA's Mars Exploration Rover Opportunity used its navigation camera to take the images combined into this full-circle view of the rover's surroundings during the 1,818th Martian day, or sol, of Opportunity's surface mission (March 5, 2009). South is at the center; north at both ends. The rover had driven 80.3 meters (263 feet) southward earlier on that sol. Tracks from the drive recede northward in this view. The terrain in this portion of Mars' Meridiani Planum region includes dark-toned sand ripples and lighter-toned bedrock. This view is presented as a cylindrical projection with geometric seam correction.
Sol-gel synthesis of YBa2Cu3O7-x superconductor by mixed organic-inorganic polymerization

International Nuclear Information System (INIS)

Valente, I.; Sanchez, C.; Henry, M.; Livage, J.

1989-01-01

Sol-gel processes are quite attractive methods to produce films or fibers of high Tc superconducting materials. The gel step allows a good chemical homogeneity and generally provides a rather low processing temperature. Blue sols or monolithic gels can be easily produced using mixed organic-inorganic polymerisation of molecular precursors. An aqueous solution of copper, barium acetates and yttrium nitrate is mixed with an acrylic acid solution where a radical organic polymerisation process has been initiated. After pH adjustments, the viscosity of the resulting solution can be adjusted by heating. After drying at 150 0 C and calcination above 700 0 C, the YBaCuO network is formed and superconducting properties appears above 850 0 C. Fine particles (0.1-1 μm) are obtained which can be sintered to produce a ceramic material with a particularly narrow resistive transition [fr
Transport and confinement in the Mega Ampere Spherical Tokamak (MAST) plasma

Energy Technology Data Exchange (ETDEWEB)

Akers, R J; Ahn, J W; Appel, L C; Brickley, C; Bunting, C; Carolan, P G; Challis, C D; Conway, N J; Counsell, G F; Dendy, R O; Dudson, B; Field, A R; Kirk, A; Lloyd, B; Meyer, H F; Morris, A W; Patel, A; Roach, C M; Sykes, A; Taylor, D; Tournianski, M R; Valovic, M; Wilson, H R; Axon, K B; Buttery, R J; Ciric, D; Cunningham, G; Dowling J; Dunstan, M R; Gee, S J; Gryaznevich, M P; Helander, P; Keeling, D L; Knight, P J; Lott, F; Loughlin, M J; Manhood, S J; Martin, R; McArdle, G J; Price, M N; Stammers, K; Storrs, J [EURATOM/UKAEA Fusion Association, Culham Science Centre, Abingdon, Oxon OX14 3DB (United Kingdom); Antar, G Y [Fusion Energy Research Program, University of California San Diego, 9500 Gilman Dr., La Jolla, CA 92093-0417 (United States); Applegate, D [Imperial College of Science, Technology and Medicine, University of London, London SW7 2BZ (United Kingdom); Rohzansky, V [St. Petersburg State Politechnical University, Polytechnicheskaya 29, 195251 St. Petersburg (Russian Federation); Walsh, M J [Walsh Scientific Ltd., Abingdon, Oxon OX14 3EB (United Kingdom)

2003-12-01

techniques developed at conventional aspect ratio. Electron and ion energy diffusivities are reduced towards the ion-neoclassical level in the ITB region of both co- and counter-injection NBI heated plasmas, with momentum diffusivity up to 10 times lower. Moving out to the edge and SOL, OSM2/EIRENE modelling is being used to extract edge perpendicular particle and heat diffusivities, results being consistent with the ballooning nature of power-flow seen in L-mode and reduction in outboard turbulence seen in ELM-free and inter-ELM H-mode. Modelling of parallel SOL transport requires the inclusion of the mirror force (approx. 10 times higher in MAST than at the conventional aspect ratio) and B2SOLPS5.0 simulations show the edge electric field to be well modelled by neoclassical theory. Transient edge transport phenomena are being studied in detail using a variety of techniques (e.g. probability density function (PDF) and power spectrum analysis, differencing and rescaling methods). Intermittent transport is associated with a radial efflux at up to a tenth of the sound speed and up to 30 cm from the separatrix. Arguably, the most dramatic edge events seen in the plasma periphery are the ELMs. Recent results using fast, high-resolution visible imaging confirm the hypothesis that ELMs have both poloidal and toroidal structures (n approx. 10 at q = 4), consistent with recent theories of the non-linear evolution of ballooning modes.
Transport and confinement in the Mega Ampere Spherical Tokamak (MAST) plasma

International Nuclear Information System (INIS)

Akers, R J; Ahn, J W; Antar, G Y; Appel, L C; Applegate, D; Brickley, C; Bunting, C; Carolan, P G; Challis, C D; Conway, N J; Counsell, G F; Dendy, R O; Dudson, B; Field, A R; Kirk, A; Lloyd, B; Meyer, H F; Morris, A W; Patel, A; Roach, C M; Rohzansky, V; Sykes, A; Taylor, D; Tournianski, M R; Valovic, M; Wilson, H R; Axon, K B; Buttery, R J; Ciric, D; Cunningham, G; Dowling, J; Dunstan, M R; Gee, S J; Gryaznevich, M P; Helander, P; Keeling, D L; Knight, P J; Lott, F; Loughlin, M J; Manhood, S J; Martin, R; McArdle, G J; Price, M N; Stammers, K; Storrs, J; Walsh, M J

2003-01-01

ratio. Electron and ion energy diffusivities are reduced towards the ion-neoclassical level in the ITB region of both co- and counter-injection NBI heated plasmas, with momentum diffusivity up to 10 times lower. Moving out to the edge and SOL, OSM2/EIRENE modelling is being used to extract edge perpendicular particle and heat diffusivities, results being consistent with the ballooning nature of power-flow seen in L-mode and reduction in outboard turbulence seen in ELM-free and inter-ELM H-mode. Modelling of parallel SOL transport requires the inclusion of the mirror force (approx. 10 times higher in MAST than at the conventional aspect ratio) and B2SOLPS5.0 simulations show the edge electric field to be well modelled by neoclassical theory. Transient edge transport phenomena are being studied in detail using a variety of techniques (e.g. probability density function (PDF) and power spectrum analysis, differencing and rescaling methods). Intermittent transport is associated with a radial efflux at up to a tenth of the sound speed and up to 30 cm from the separatrix. Arguably, the most dramatic edge events seen in the plasma periphery are the ELMs. Recent results using fast, high-resolution visible imaging confirm the hypothesis that ELMs have both poloidal and toroidal structures (n approx. 10 at q = 4), consistent with recent theories of the non-linear evolution of ballooning modes
Multi-scale transport in the DIII-D ITER baseline scenario with direct electron heating and projection to ITER

Science.gov (United States)

Grierson, B. A.; Staebler, G. M.; Solomon, W. M.; McKee, G. R.; Holland, C.; Austin, M.; Marinoni, A.; Schmitz, L.; Pinsker, R. I.; DIII-D Team

2018-02-01

Multi-scale fluctuations measured by turbulence diagnostics spanning long and short wavelength spatial scales impact energy confinement and the scale-lengths of plasma kinetic profiles in the DIII-D ITER baseline scenario with direct electron heating. Contrasting discharge phases with ECH + neutral beam injection (NBI) and NBI only at similar rotation reveal higher energy confinement and lower fluctuations when only NBI heating is used. Modeling of the core transport with TGYRO using the TGLF turbulent transport model and NEO neoclassical transport reproduces the experimental profile changes upon application of direct electron heating and indicates that multi-scale transport mechanisms are responsible for changes in the temperature and density profiles. Intermediate and high-k fluctuations appear responsible for the enhanced electron thermal flux, and intermediate-k electron modes produce an inward particle pinch that increases the inverse density scale length. Projection to ITER is performed with TGLF and indicates a density profile that has a finite scale length due to intermediate-k electron modes at low collisionality and increases the fusion gain. For a range of E × B shear, the dominant mechanism that increases fusion performance is suppression of outward low-k particle flux and increased density peaking.
Mitigation of strontium and ruthenium release in the CANDU primary heat transport system

International Nuclear Information System (INIS)

McFarlane, J.

1998-03-01

In certain severe accident scenarios, low-volatility fission products can appear to contribute significantly to dose, if treated with undue conservatism. Hence a survey was performed, to see if factors that may mitigate release of strontium and ruthenium could be incorporated into safety analyses, to cover parameters such as location in the fuel matrix under normal operating conditions, release from fuel, transport and deposition in the primary heat transport system and chemistry. In addition chemical equilibrium calculations were performed to investigate the volatility of strontium and ruthenium in the presence of uranium and important fission products. Strontium is very soluble in the U0 2 fuel, up to 12 atom %, and hence release is improbable, particularly under oxidizing conditions until volatilization of the fuel matrix itself occurs. Ruthenium, however, can be released at low temperatures, but only under oxidizing conditions. These may occur during a fuel-handling accident or as a result of an end-fitting failure. Under these conditions, the primary heat transport system cannot be credited for retention. The volatile form of ruthenium, RuO 4 (g), is thermally unstable above 381 K and decomposes to RuO 2 (s) and O 2 (g) upon contact with surfaces, a factor that is likely to minimize the release of ruthenium into the environment. (author)
Sol-gel materials for optofluidics - process and applications

DEFF Research Database (Denmark)

Mikkelsen, Morten Bo Lindholm

2011-01-01

This Ph.D. thesis is concerned with the use of sol-gel materials in optofluidic applications and the physics of DNA molecules in nanoconfinement. The bottom-up formation of solid material, which is provided by the sol-gel process, enables control of the chemical composition and porosity...... of the material. At early stages of gelation, thin gel coatings can be structured by nanoimprint lithography, and purely inorganic silica materials can be obtained by subsequent thermal annealing. The sol-gel process thus constitutes a unique method for nanofabrication of silica materials of special properties....... In this work, sol-gel silica is introduced as a new material class for the fabrication of lab-on-a-chip devices for DNA analysis. An imprint process with a rigid, non-permeable stamp was developed, which enabled fabrication of micro- and nanofluidic silica channels in a single process step without use of any...
Influence of Uranium and Polivinyl Alcohol Concentration in the Feed of Sol Gel Process on the Gel Spherical Product

International Nuclear Information System (INIS)

Indra Suryawan; Endang Susiantini

2007-01-01

The gel particles have been made at various uranium and polyvinyl alcohol concentration in the sol gel process. The variables of uranium concentration were 0.3; 0.5; 0.7; 0.9; 1.1; 1.3; 1.5; 1.7; 1.9 and 2.1 M The variables of polyvinyl alcohol concentration were 0.3; 0.6; 0.9; 1.2; 1.5; 1.8; 2.1 and 2.4 M After drying the sol gel process products were heated at 300, 500 and 750°C during 4 hours. The gel particles were characterized using an optic microscope to know the shape and condition morphology of gel. From experimental result using uranium concentration of 0.3 until 2.1 M and polyvinyl alcohol of 1.8 until 2.4 M spherical and gel was formed elastic, after heating at 750°C it was unbreakable. At the concentration of polyvinyl alcohol from 0.3 to 0.5 M, the gel product was soft and broken after being dried. At the concentration of polyvinyl alcohol from 0.6 to 0.8 M, the dried gel product was not perfect. At the concentration of polyvinyl alcohol from 0.9 to 1.7 M, the gel product of gelation process was spherical and it was broken after being heated up to 300°C. (author)

Bounds on heat transport in rapidly rotating Rayleigh–Bénard convection

International Nuclear Information System (INIS)

Grooms, Ian; Whitehead, Jared P

2015-01-01

The heat transport in rotating Rayleigh–Bénard convection is considered in the limit of rapid rotation (small Ekman number E) and strong thermal forcing (large Rayleigh number Ra). The analysis proceeds from a set of asymptotically reduced equations appropriate for rotationally constrained dynamics; the conjectured range of validity for these equations is Ra ≲ E −8/5 . A rigorous bound on heat transport of Nu ⩽ 20.56Ra 3 E 4 is derived in the limit of infinite Prandtl number using the background method. We demonstrate that the exponent in this bound cannot be improved on using a piece-wise monotonic background temperature profile like the one used here. This is true for finite Prandtl numbers as well, i.e. Nu ≲ Ra 3 is the best upper bound for this particular setup of the background method. The feature that obstructs the availability of a better bound in this case is the appearance of small-scale thermal plumes emanating from (or entering) the thermal boundary layer. The derived upper bound is consistent with, although significantly higher than the observed behaviour in simulations of the reduced equations, which find at most Nu ∼ Ra 2 E 8/3 . (paper)
Production of Monodisperse Cerium Oxide Microspheres with Diameters near 100 µm by Internal Gelation Sol-Gel Methods

Energy Technology Data Exchange (ETDEWEB)

Katalenich, Jeffrey A.; Kitchen, Brian B.; Pierson, Bruce

2018-05-01

Internal gelation sol-gel methods have used a variety of sphere forming methods in the past to produce metal oxide microspheres, but typically with poor control over the size uniformity at diameters near 100 µm. This work describes efforts to make and measure internal gelation, sol-gel microspheres with very uniform diameters in the 100 – 200 µm size range using a two-fluid nozzle. A custom apparatus was used to form aqueous droplets of sol-gel feed solutions in silicone oil and heat them to cause gelation of the spheres. Gelled spheres were washed, dried, and sintered prior to mounting on glass slides for optical imaging and analysis. Microsphere diameters and shape factors were determined as a function of silicone oil flow rate in a two-fluid nozzle and the size of a needle dispensing the aqueous sol-gel solution. Nine batches of microspheres were analyzed and had diameters ranging from 65.5 ± 2.4 µm for the smallest needle and fastest silicone oil flow rate to 211 ± 4.7 µm for the largest needle and slowest silicone oil flow rate. Standard deviations for measured diameters were less than 8% for all samples and most were less than 4%. Microspheres had excellent circularity with measured shape factors of 0.9 – 1. However, processing of optical images was complicated by shadow effects in the photoresist layer on glass slides and by overlapping microspheres. Based on calculated flow parameters, microspheres were produced in a simple dripping mode in the two-fluid nozzle. Using flow rates consistent with a simple dripping mode in a two-fluid nozzle configuration allows for very uniform oxide microspheres to be produced using the internal-gelation sol-gel method.
Threshold heating temperature for magnetic hyperthermia: Controlling the heat exchange with the blocking temperature of magnetic nanoparticles

Science.gov (United States)

Pimentel, B.; Caraballo-Vivas, R. J.; Checca, N. R.; Zverev, V. I.; Salakhova, R. T.; Makarova, L. A.; Pyatakov, A. P.; Perov, N. S.; Tishin, A. M.; Shtil, A. A.; Rossi, A. L.; Reis, M. S.

2018-04-01

La0.75Sr0.25MnO3 nanoparticles with average diameter close to 20.9 nm were synthesized using a sol-gel method. Measurements showed that the heating process stops at the blocking temperaturesignificantly below the Curie temperature. Measurements of Specific Absorption Rate (SAR) as a function of AC magnetic field revealed a superquadratic power law, indicating that, in addition to usual Néel and Brown relaxation, the hysteresis also plays an important role in the mechanism of heating. The ability to control the threshold heating temperature, a low remanent magnetization and a low field needed to achieve the magnetic saturation are the advantages of this material for therapeutic magnetic hyperthermia.
Physical aspects of thermotherapy: A study of heat transport with a view to treatment optimisation

Science.gov (United States)

Olsrud, Johan Karl Otto

1998-12-01

Local treatment with the aim to destruct tissue by heating (thermotherapy) may in some cases be an alternative or complement to surgical methods, and has gained increased interest during the last decade. The major advantage of these, often minimally-invasive methods, is that the disease can be controlled with reduced treatment trauma and complications. The extent of thermal damage is a complex function of the physical properties of tissue, which influence the temperature distribution, and of the biological response to heat. In this thesis, methods of obtaining a well-controlled treatment have been studied from a physical point of view, with emphasis on interstitial laser-induced heating of tumours in the liver and intracavitary heating as a treatment for menorrhagia. Hepatic inflow occlusion, in combination with temperature-feedback control of the output power of the laser, resulted in well defined damaged volumes during interstitial laser thermotherapy in normal porcine liver. In addition, phantom experiments showed that the use of multiple diffusing laser fibres allows heating of clinically relevant tissue volumes in a single session. Methods for numerical simulation of heat transport were used to calculate the temperature distribution and the results agreed well with experiments. It was also found from numerical simulation that the influence of light transport on the damaged volume may be negligible in interstitial laser thermotherapy in human liver. Finite element analysis, disregarding light transport, was therefore proposed as a suitable method for 3D treatment planning. Finite element simulation was also used to model intracavitary heating of the uterus, with the purpose of providing an increased understanding of the influence of various treatment parameters on blood flow and on the depth of tissue damage. The thermal conductivity of human uterine tissue, which was used in these simulations, was measured. Furthermore, magnetic resonance imaging (MRI) was
Characterisation of a new alkoxide sol-gel hydroxyapatite

International Nuclear Information System (INIS)

Green, D.D.; Kannangara, G.S.K.; Milev, A.; Ben-Nissan, B.

1999-01-01

Hydroxyapatite (HAp) coatings have been used to promote bone growth and fixation towards implant surfaces to encourage faster recovery times for the recipient. Current coating processing techniques, capable of producing thin HAp layers are pulsed-laser deposition and sputtering (high-temperature processing). Other technologies are in vitro methods, electrodeposition and sol-gel, due to the fact that these techniques utilise lower processing temperatures they avoid structural instabilities of HAp at elevated temperatures. The term sol-gel encompasses any process of producing ceramic materials (single and mixed oxides, as well as non-oxides e.g. nitrides) from solutions. The sol-gel process was first identified by Ebelman, and has been used to produce ceramic powders, coatings, and bulk materials including glasses. The implementation of a sol-gel methodology enables increased stoichiometry and homogeneity, while having the ability to coat complex shapes. Sol-gel hydroxyapatite reported by Chai et al. employed tri ethyl phosphite [ P(OEt) 3 ] as the staring phosphorus alkoxide precursor, whereby it was established that in order to obtain monophasic hydroxyapatite upon firing there must be a 24 hour ripening period. The ripening period was determined to be an equilibrium step whereby the equilibrium intermediate phase lied in favour of a diethyl phosphite arrangement (species) within the sol. Therefore, the work here under taken was to produce hydroxyapatite using diethyl phosphite [HOP(OEt) 2 ] as a starting alkoxide precursor with a final aim to reduce or eliminate the ageing period as observed by Chai et al in P(OEt) 3 solutions
Coatings of active and heat-resistant cobalt-aluminium xerogel catalysts.

Science.gov (United States)

Schubert, Miriam; Schubert, Lennart; Thomé, Andreas; Kiewidt, Lars; Rosebrock, Christopher; Thöming, Jorg; Roessner, Frank; Bäumer, Marcus

2016-09-01

The application of catalytically coated metallic foams in catalytic processes has a high potential for exothermic catalytic reactions such as CO2 methanation or Fischer-Tropsch synthesis due to good heat conductivity, improved turbulent flow properties and high catalyst efficiencies. But the preparation of homogenous catalyst coats without pore blocking is challenging with conventional wash coating techniques. Here, we report on a stable and additive free colloidal CoAlOOH suspension (sol) for the preparation of catalytically active Co/Al2O3 xerogel catalysts and coatings. Powders with 18wt% Co3O4 prepared from this additive free synthesis route show a catalytic activity in Fischer-Tropsch synthesis and CO2 methanation which is similar to a catalyst prepared by incipient wetness impregnation (IWI) after activating the material under flowing hydrogen at 430°C. Yet, the xerogel catalyst exhibits a much higher thermal stability as compared to the IWI catalyst, as demonstrated in catalytic tests after different heat agings between 430°C and 580°C. It was also found that the addition of polyethylene glycol (PEG) to the sol influences the catalytic properties of the formed xerogels negatively. Only non-reducible cobalt spinels were formed from a CoAlOOH sol with 20wt% PEG. Metallic foams with pores sizes between 450 and 1200μm were coated with the additive free CoAlOOH sol, which resulted in homogenous xerogel layers. First catalytic tests of the coated metal foams (1200μm) showed good performance in CO2 methanation. Copyright © 2016 Elsevier Inc. All rights reserved.
Waste heat recovery for transport trucks using thermally regenerative fuel cells

Energy Technology Data Exchange (ETDEWEB)

Carrier, A.; Wechsler, D.; Whitney, R.; Jessop, P. [Queen' s Univ., Kingston, ON (Canada). Dept. of Chemistry; Davis, B.R. [Queen' s-RMC Fuel Cell Research Centre, Kingston, ON (Canada)

2009-07-01

Carbon emissions associated with transportation can be reduced by increasing the fuel efficiency of transport trucks. This can be achieved with thermally regenerative fuel cells that transform the waste heat from the engine block into electricity. In order to operate such a fuel cell, one needs a fluid which rapidly, reversibly, and selectively undergoes dehydrogenation. Potential fluids have been screened for their ability to dehydrogenate and then rehydrogenate at the appropriate temperatures. An examination of the thermodynamics, kinetics, and selectivities of these processes have shown that the challenge involving hydrogenolysis at high temperature must be addressed. This paper discussed the economics of thermally regenerative fuel cells and the advantages and disadvantages of the identified fluids, and of such systems in general.
High-performance heat pipes for heat recovery applications

Science.gov (United States)

Saaski, E. W.; Hartl, J. H.

1980-01-01

Methods to improve the performance of reflux heat pipes for heat recovery applications were examined both analytically and experimentally. Various models for the estimation of reflux heat pipe transport capacity were surveyed in the literature and compared with experimental data. A high transport capacity reflux heat pipe was developed that provides up to a factor of 10 capacity improvement over conventional open tube designs; analytical models were developed for this device and incorporated into a computer program HPIPE. Good agreement of the model predictions with data for R-11 and benzene reflux heat pipes was obtained.
Modification of the finite element heat and mass transfer code (FEHM) to model multicomponent reactive transport

International Nuclear Information System (INIS)

Viswanathan, H.S.

1996-08-01

The finite element code FEHMN, developed by scientists at Los Alamos National Laboratory (LANL), is a three-dimensional finite element heat and mass transport simulator that can handle complex stratigraphy and nonlinear processes such as vadose zone flow, heat flow and solute transport. Scientists at LANL have been developing hydrologic flow and transport models of the Yucca Mountain site using FEHMN. Previous FEHMN simulations have used an equivalent Kd model to model solute transport. In this thesis, FEHMN is modified making it possible to simulate the transport of a species with a rigorous chemical model. Including the rigorous chemical equations into FEHMN simulations should provide for more representative transport models for highly reactive chemical species. A fully kinetic formulation is chosen for the FEHMN reactive transport model. Several methods are available to computationally implement a fully kinetic formulation. Different numerical algorithms are investigated in order to optimize computational efficiency and memory requirements of the reactive transport model. The best algorithm of those investigated is then incorporated into FEHMN. The algorithm chosen requires for the user to place strongly coupled species into groups which are then solved for simultaneously using FEHMN. The complete reactive transport model is verified over a wide variety of problems and is shown to be working properly. The new chemical capabilities of FEHMN are illustrated by using Los Alamos National Laboratory's site scale model of Yucca Mountain to model two-dimensional, vadose zone 14 C transport. The simulations demonstrate that gas flow and carbonate chemistry can significantly affect 14 C transport at Yucca Mountain. The simulations also prove that the new capabilities of FEHMN can be used to refine and buttress already existing Yucca Mountain radionuclide transport studies
Structural Evolution and Stability of Sol-Gel Biocatalysts

International Nuclear Information System (INIS)

Rodgers, L.E.; Foster, L.J.R.; Holden, P.J.; Knott, R.B.; Bartlett, J.B.

2005-01-01

Full text: Immobilisation strategies for catalytic enzymes are important as they allow reuse of the biocatalysts. Sol-gel materials have been used to immobilise Candida antarctica lipase B (CALB), a commonly used industrial enzyme with a known crystal structure. The sol-gel bioencapsulate is produced through the condensation of suitable metal alkoxides in the presence of CALB, yielding materials with controlled pore sizes, volume and surface chemistry. Sol-gel matrices have been shown to prolong the catalytic life and enhance the activity of CALB, although the molecular basis for this effect has yet to be elucidated due to the limitations of analysis techniques applied to date. Small angle neutron scattering (SANS) allows such multicomponent systems to be characterised through contrast matching. In the sol-gel bioencapsulate system, at the contrast match point for silica, residual scattering intensity is due to the CALB and density fluctuations in the matrix. A SANS contrast variation series found the match point for the silica matrix, both with and without enzyme present, to be around 35 percent. The model presented here proposes a mechanism for the interaction between CALB and the surrounding sol-gel matrix, and the observed improvement in enzyme activity and matrix strength. The SANS protocol developed here may be applied more generally to bioencapsulates. (authors)
Events leading to foreign material being left in the primary heat transport system

International Nuclear Information System (INIS)

Groom, S.H.; Benton, A.J.

1996-01-01

On October 6,1995, following an extensive maintenance outage which had included boiler primary side cleaning, a Primary Heat Transport (PHT) system pump run was started in preparation for ultrasonic feeder flow measurements. Wooden debris in the system resulted in failure of the shaft seals of the PHT Pump 1. The subsequent investigation and assessment of this event provided an understanding of both the pump shaft failure mechanism and the origin of the debris in the PHT system. The pump shaft failed as a result of friction-generated heat resulting from contact between the rotating shaft and the stationary seal housing. This contact was initiated by mechanical and hydraulic imbalance in the pump impeller caused by wooden debris lodged in the impeller. The origin of the wooden debris was a temporary plywood cover which was inadvertently left in a boiler following maintenance. This cover moved from the boiler to the pump impeller when the PHT pumps were started. The cover was not accounted for and verified as being removed prior to boiler closure, although a visual inspection was conducted. A detailed institutional process for component accounting and verification of removal of materials did not exist at the time of this event. Details of the methods used to establish alternative heat sinks, provide debris recovery facilities and to assess the fitness for duty of the heat transport system and fuel channels prior to reactor startup are discussed in detail elsewhere. This report will concentrate on the events leading up to and following the events which ultimately resulted in failure of the PHT pump shaft
Safety studies on heat transport and afterheat removal for GCR accident conditions

International Nuclear Information System (INIS)

Hishida, Makoto

1996-01-01

The IAEA coordinated an international research program on 'Heat Transport and Afterheat Removal for GCRs under Accident Conditions (CRP-3)'. America, China, France, Germany, Japan, Netherlands and Russia participate the program. Final goal of the program is to show clearly to the world one of the most important salient features of the HTGR, that is the HTGR reactor can be cooled down by passive measures without causing any damage to the nuclear reactor system even in accidental conditions, and to make clear the boundaries (or restrictions) for the passive cooling regime. The first 5 year term of the coordinate program started in 1993 and established a goal to improve common knowledge for decay heat removal and to improve our tools, like computer codes and analytical models for the prediction of the performance of decay heat removal system. We are now performing benchmark problems for these purposes. The present efforts are concentrated on the benchmark for the passive heat removal performance outside the reactor vessel, partly because we have two different type of the HTGR in the world, the pebble bed type and the block type reactor. They have quite different heat dissipation behavior inside the reactor vessel. However, they have quite similar residual heat removal process outside the reactor vessel. For the first step of the international cooperation, we selected the common problem. After finishing the present benchmark we are planning to proceed to tackle the inside heat removal problem. (J.P.N.)
Structural development and kinetic analysis of PbTiO3 powders processed at low-temperature via new sol-gel approach

Science.gov (United States)

Bel-Hadj-Tahar, Radhouane; Abboud, Mohamed

2018-04-01

The synthesis of crystalline lead titanate powder by a generic low-temperature sol-gel approach is developed. Acetoin was added as ligand, instead of the commonly used alkanolamines, to ensure total dissolution of the precursor compounds. The feasibility of the acetoin-Ti isopropoxide complex as a new precursor of PbTiO3 perovskite particles via sol-gel method has been demonstrated. No excess lead has been introduced. Nanometric PbTiO3 crystallites have been formed at 400 °C under atmospheric pressure from titanium isopropoxide and lead acetate in alcoholic solution by remarkably low activation energy of crystallization process of 90 kJ mol-1. The powders show tetragonal lattice and dendritic morphology. In addition to the effect of heat-treatment temperature, time, and atmosphere, the sol chemistry particularly influenced the phase composition, particle size, and particle morphology. The use of different ligands significantly modified powder morphology. The extent of the crystallization was quantitatively evaluated by differential thermal analysis and analyzed by Johnson-Mehl-Avrami approach. The crystallization followed two rate regimes depending on the interval of the crystallized fraction.
Alkali passivation mechanism of sol-gel derived TiO2-SiO2 films coated on soda-lime-silica glass substrates

Energy Technology Data Exchange (ETDEWEB)

Matsuda, A; Matsuno, Y; Katayama, S; Tsuno, T [Nippon Steel Glass Co. Ltd., Tokyo (Japan); Toge, N; Minami, T [University of Osaka Prefecture, Osaka (Japan). College of Engineering

1992-09-01

TiO2-SiO2 films prepared by the sol-gel method serves as an effective alkali passivation layer on a soda-lime-silica glass substrate and the film is superior to a sol-gel derived pure SiO2 film from the view point of weathering resistance improvement. To clarify the reason, alkali passivation mechanism of sol-gel derived TiO2-SiO2 glass films with different TiO2 contents coated on a soda-lime-silica glass substrate was studied by SIMS (secondary ion mass spectroscopy) and XPS (X-ray photoelectron spectroscopy) analyses, and compared with the results of a sol-gel derived pure SiO2 film. As a result, the following conclusions were obtained: An increase in TiO2 content in the TiO2 SiO2 film increases the sodium concentration in the film, which was induced by sodium migration from the glass substrate during the heat-treatment. Because of the presence of sodium the TiO2 -SiO2 films serve not as a barrier but as an effective getter of alkali ions and thereby effectively improve the weathering resistance Of the glass substrate. 10 refs., 6 figs.
Development of highly-ordered, ferroelectric inverse opal films using sol gel infiltration

Science.gov (United States)

Matsuura, N.; Yang, S.; Sun, P.; Ruda, H. E.

2005-07-01

Highly-ordered, ferroelectric, Pb-doped Ba0.7Sr0.3TiO3, inverse opal films were fabricated by spin-coating a sol gel precursor into a polystyrene artificial opal template followed by heat treatment. Thin films of the ferroelectric were independently studied and were shown to exhibit good dielectric properties and high refractive indices. The excellent quality of the final inverse opal film using this spin-coating infiltration method was confirmed by scanning electron microscopy images and the good correspondence between optical reflection data and theoretical simulations. Using this method, the structural and material parameters of the final ferroelectric inverse opal film were easily adjusted by template heating and through repeated infiltrations, without changes in the initial template or precursor. Also, crack-free inverse opal thin films were fabricated over areas comparable to that of the initial crack-free polystyrene template (˜100 by 100 μm2).
Electrical stability of Al-doped ZnO transparent electrode prepared by sol-gel method

International Nuclear Information System (INIS)

Tabassum, Samia; Yamasue, Eiji; Okumura, Hideyuki; Ishihara, Keiichi N.

2016-01-01

Highlights: • Al-doped ZnO thin film was deposited by sol-gel method in different annealing temperature and duration. • We examined the environmental stability in ambient and damp heat condition. • We investigated chemical state of thin film. • Better stability was observed in the film annealed at high temperature (600 °C) along with longer duration (120 min). • An ultrathin aluminum oxide layer formation was predicted by XPS measurement which protects further oxidation and improves stability. - Abstract: Al-doped zinc oxide (AZO) thin films have been considered as a promising alternative to tin doped indium oxide (ITO), which is currently used in various optoelectronic applications. However, the environmental stability of AZO film is not satisfactory, in that the resistivity is significantly increases in air. Here, we investigate the resistivity stability of AZO thin films prepared by sol-gel method using various annealing temperatures and durations. The degradation of resistivity property was observed for AZO films stored in ambient or damp heat environment, where the degradation rate was influenced by annealing temperature. A significant improvement of electrical stability was attained in AZO films that were prepared at high annealing temperature. The films, which showed the highest and the lowest increasing rate of resistivity, were further characterized in detail to shed light on the possible mechanisms explaining the improved stability through crystallinity, surface morphology and elemental state of the thin film.
Electrical stability of Al-doped ZnO transparent electrode prepared by sol-gel method

Energy Technology Data Exchange (ETDEWEB)

Tabassum, Samia, E-mail: shawon14@gmail.com; Yamasue, Eiji; Okumura, Hideyuki; Ishihara, Keiichi N.

2016-07-30

Highlights: • Al-doped ZnO thin film was deposited by sol-gel method in different annealing temperature and duration. • We examined the environmental stability in ambient and damp heat condition. • We investigated chemical state of thin film. • Better stability was observed in the film annealed at high temperature (600 °C) along with longer duration (120 min). • An ultrathin aluminum oxide layer formation was predicted by XPS measurement which protects further oxidation and improves stability. - Abstract: Al-doped zinc oxide (AZO) thin films have been considered as a promising alternative to tin doped indium oxide (ITO), which is currently used in various optoelectronic applications. However, the environmental stability of AZO film is not satisfactory, in that the resistivity is significantly increases in air. Here, we investigate the resistivity stability of AZO thin films prepared by sol-gel method using various annealing temperatures and durations. The degradation of resistivity property was observed for AZO films stored in ambient or damp heat environment, where the degradation rate was influenced by annealing temperature. A significant improvement of electrical stability was attained in AZO films that were prepared at high annealing temperature. The films, which showed the highest and the lowest increasing rate of resistivity, were further characterized in detail to shed light on the possible mechanisms explaining the improved stability through crystallinity, surface morphology and elemental state of the thin film.
Study on a non-powered heat transporting system; Mudoryoku netsu hanso system ni kansuru kenkyu

Energy Technology Data Exchange (ETDEWEB)

Kamiya, Y [Kanto Gakuin University, Yokohama (Japan)

1997-11-25

This paper proposes a non-powered heat transportation (HT) system. The system is composed of an evaporator, condenser, receiver, switching chamber (SC) and 3 check valves which are connected with each other by vapor and liquid tubes. Condensed liquid supercooled in the condenser exists in the receiver forming a saturated condition at a concerned temperature, and condensed liquid is lifted up from the condenser to the receiver by pressure difference between the evaporator and receiver. Generally evaporation pressure is higher by pressure difference between liquid levels in the condenser and receiver. The lifted up amount of condensed liquid increases with evaporation pressure, resulting in an increase in heating surface area of the condenser and amount of condensed liquid. A proper evaporator pressure is thus retained by reduction of evaporation pressure. SC is connected with the receiver and evaporator, and switches high- and low-pressure valves by motion of an inner float to transport heat from the evaporator to condenser. Reverse HT is possible as normal latent HT by installing a bypass. Some problems are also described. 2 refs., 8 figs.
Development of fluorocarbon/silica composites via sol/gel process

International Nuclear Information System (INIS)

Ferreira, Max P.; Maria, Daniel A.; Gomes, Luiza M.F.

2009-01-01

Fluorocarbon/silica composites have interesting physical-chemical properties, combining the great resistance to chemical products, the electric insulation, and the thermal stability of fluorine polymers with the optical, magnetic, and dielectric properties of silica. Due to the unique mechanical, thermal, and dielectric properties of fluorocarbon and silica composites, there is interest in their application in the development of fuel cells, the production of integrated circuit boards (ICB), and packages for the transportation of integrated circuits. The sol-gel process is a chemical route to prepare ceramic materials with specific properties that are hard or impossible to obtain by conventional methods. Fluorocarbon/silica composites were obtained by the sol-gel method from tetramethoxysilane - TMOS and fluorinated hydrocarbons with low molecular weight and main chains with 10 - 20 carbon atoms previously obtained from PTFE scraps irradiated with a 60 Co γ source in oxygen atmosphere with a dose of 1 MGy. Syntheses were performed in 125-mL reaction flasks in basic medium at 35 deg C and in acid medium at 60 deg C with N-N dimethylformamide as a chemical additive for drying control. After synthesis, the material was thermally treated in an oven with electronic temperature control. The monoliths obtained were characterized by Fourier transform infrared spectroscopy (FTIR), electron microprobe and by a standard nitrogen adsorption-desorption technique. (author)
The heat transport system and plant design for the HYLIFE-2 fusion reactor

International Nuclear Information System (INIS)

Hoffman, M.A.

1990-01-01

HYLIFE is the name given to a family of self-healing liquid-wall reactor concepts for inertial confinement fusion. This HYLIFE-II concept employs the molten salt, Flibe, for the liquid jets instead of liquid lithium used in the original HYLIFE-I study. A preliminary conceptual design study of the heat transport system and the balance of plant of the HYLIFE-II fusion power plant is described in this paper with special emphasis on a scoping study to determine the best intermediate heat exchanger geometry and flow conditions for minimum cost of electricity. 11 refs., 8 figs

Enhancement of Ce/Cr Codopant Solubility and Chemical Homogeneity in TiO2 Nanoparticles through Sol-Gel versus Pechini Syntheses.

Science.gov (United States)

Chen, Wen-Fan; Mofarah, Sajjad S; Hanaor, Dorian Amir Henry; Koshy, Pramod; Chen, Hsin-Kai; Jiang, Yue; Sorrell, Charles Christopher

2018-06-18

Ce/Cr codoped TiO 2 nanoparticles were synthesized using sol-gel and Pechini methods with heat treatment at 400 °C for 4 h. A conventional sol-gel process produced well-crystallized anatase, while Pechini synthesis yielded less-ordered mixed-phase anatase + rutile; this suggests that the latter method enhances Ce solubility and increases chemical homogeneity but destabilizes the TiO 2 lattice. Greater structural disruption from the decomposition of the Pechini precursor formed more open agglomerated morphologies, while the lower levels of structural disruption from pyrolysis of the dried sol-gel precursor resulted in denser agglomerates of lower surface areas. Codoping and associated destabilization of the lattice reduced the binding energies in both powders. Cr 4+ formation in sol-gel powders and Cr 6+ formation in Pechini powders suggest that these valence changes derive from synergistic electron exchange from intervalence and/or multivalence charge transfer. Since Ce is too large to allow either substitutional or interstitial solid solubility, the concept of integrated solubility is introduced, in which the Ti site and an adjacent interstice are occupied by the large Ce ion. The photocatalytic performance data show that codoping was detrimental owing to the effects of reduced crystallinity from lattice destabilization and surface area. Two regimes of mechanistic behavior are seen, which are attributed to the unsaturated solid solutions at lower codopant levels and supersaturated solid solutions at higher levels. The present work demonstrates that the Pechini method offers a processing technique that is superior to sol-gel because the former facilitates solid solubility and consequent chemical homogeneity.
Electron heat transport in current carrying and currentless thermonuclear plasmas. Tokamaks and stellarators compared

International Nuclear Information System (INIS)

Peters, M.

1996-01-01

In the first experiment the plasma current in the RTP tokamak is varied. Here the underlying idea was to check whether at a low plasma current, transport in the tokamak resembles transport in stellarators more than at higher currents. Secondly, experiments have been done to study the relation of the diffusivity χ to the temperature and its gradient in both W7-AS and RTP. In this case the underlying idea was to find the explanation for the phenomenon observed in both tokamaks and stellarators that the quality of the confinement degrades when more heating is applied. A possible explanation is that the diffusivity increases with the temperature or its gradient. Whereas in standard tokamak and stellarator experiments the temperature and its gradient are strongly correlated, a special capability of the plasma heating system of W7-AS and RTP can force them to decouple. (orig.)
Electron heat transport in current carrying and currentless thermonuclear plasmas. Tokamaks and stellarators compared

Energy Technology Data Exchange (ETDEWEB)

Peters, M

1996-01-16

In the first experiment the plasma current in the RTP tokamak is varied. Here the underlying idea was to check whether at a low plasma current, transport in the tokamak resembles transport in stellarators more than at higher currents. Secondly, experiments have been done to study the relation of the diffusivity {chi} to the temperature and its gradient in both W7-AS and RTP. In this case the underlying idea was to find the explanation for the phenomenon observed in both tokamaks and stellarators that the quality of the confinement degrades when more heating is applied. A possible explanation is that the diffusivity increases with the temperature or its gradient. Whereas in standard tokamak and stellarator experiments the temperature and its gradient are strongly correlated, a special capability of the plasma heating system of W7-AS and RTP can force them to decouple. (orig.).
Luminescence behavior of the dibenzoyl methane europium(III) complexes in sol-gel derived host materials

International Nuclear Information System (INIS)

Wang Feng; Fan Xianping; Wang Minquan; Zhang Xianghua

2005-01-01

The luminescence behavior of the dibenzoyl methane europium(III) complexes (Eu(DBM) 3 ) in sol-gel derived host materials have been investigated. The steady-state excitation and emission spectra and the time-resolved spectra of the 1% EuCl 3 and 3% DBM co-doped gel indicated an efficient ligand-to-metal energy transfer. The Eu(DBM) 3 complexes in the gel showed longer 5 D 0 lifetimes in comparison with Eu(DBM) 3 .3H 2 O complexes. The luminescence intensity of the 1% EuCl 3 and 3% DBM co-doped gel decreased continuously with increasing temperature and time of heat treatment, which indicated the gradual decomposition of the Eu(DBM) 3 complexes in the gel during heat treatment
Thermal transport of carbon nanotubes and graphene under optical and electrical heating measured by Raman spectroscopy

Science.gov (United States)

Hsu, I.-Kai

This thesis presents systematic studies of thermal transport in individual single walled carbon nanotubes (SWCNTs) and graphene by optical and electrical approaches using Raman spectroscopy. In the work presented from Chapter 2 to Chapter 6, individual suspended CNTs are preferentially measured in order to explore their intrinsic thermal properties. Moreover, the Raman thermometry is developed to detect the temperature of the carbon nanotube (CNT). A parabolic temperature profile is observed in the suspended region of the CNT while a heating laser scans across it, providing a direct evidence of diffusive thermal transport in an individual suspended CNT. Based on the curvature of the temperature profile, we can solve for the ratio of thermal contact resistance to the thermal resistance of the CNT, which spans the range from 0.02 to 17. The influence of thermal contact resistance on the thermal transport in an individual suspended CNT is also studied. The Raman thermometry is carried out in the center of a CNT, while its contact length is successively shortened by an atomic force microscope (AFM) tip cutting technique. By investigating the dependence of the CNT temperature on its thermal contact length, the temperature of a CNT is found to increase dramatically as the contact length is made shorter. This work reveals the importance of manipulating the CNT thermal contact length when adopting CNT as a thermal management material. In using a focused laser to induce heating in a suspended CNT, one open question that remains unanswered is how many of the incident photons are absorbed by the CNT of interest. To address this question, micro-fabricated platinum thermometers, together with micro-Raman spectroscopy are used to quantify the optical absorption of an individual CNT. The absorbed power in the CNT is equal to the power detected by two thermometers at the end of the CNT. Our result shows that the optical absorption lies in the range between 0.03 to 0.44%. In
A phenomenological model for cross-field plasma transport in non-ambipolar scrape-off layers

International Nuclear Information System (INIS)

LaBombard, B.; Grossman, A.A.; Conn, R.W.

1990-01-01

A simplified two-fluid transport model which includes phenomenological coefficients of particle diffusion, mobility, and thermal diffusivity is used to investigate the effects of nonambipolar particle transport on scrape-off layer (SOL) plasma profiles. A computer code (BSOLRAD3) has been written to iteratively solve for 2-D cross-field density, potential, and electron temperature profiles for arbitrary boundary conditions, including segments of 'limiters' that are electrically conducting or non-conducting. Numerical results are presented for two test cases: (1) a 1-D slab geometry showing the interdependency of the density, potential, and temperature gradient scale lengths on particle diffusion, mobility, and thermal diffusivity coefficients and limiter bias conditions, and (2) a 2-D geometry illustrating ExB plasma flow effects. It is shown that the SOL profiles can be quite sensitive to non-ambipolarity conditions imposed by the limiter and, in particular, whether the limiter surfaces are biased. Such effects, if overlooked in SOL transport analysis, can lead to erroreous conclusions about the magnitude of the local ambipolar diffusion coefficient. (orig.)
Studies of Electron Transport and Isochoric Heating and Their Applicability to Fast Ignition

International Nuclear Information System (INIS)

Key, M H; Amiranoff, F; Andersen, C; Batani, D; Baton, S D; Cowan, T; Fisch, N; Freeman, R; Gremillet, L; Hall, T; Hatchett, S; Hill, J; King, J; Kodama, R; Koch, J; Koenig, M; Lasinski, B; Langdon, B; MacKinnon, A; Martinolli, E; Norreys, P; Parks, P; Perrelli-Cippo, E; Rabec Le Gloahec, M; Rosenbluth, M; Rousseaux, C; Santon, J J; Scianitti, F; Snavely, R; Tabak, M; Tanaka, K; Town, R; Tsutumi, T; Stephens, R

2003-01-01

Experimental measurements of electron transport and isochoric heating in 100 J, 1 ps laser irradiation of solid A1 targets are presented. Modeling with a hybrid PIC code is compared with the data and good agreement is obtained using a heuristic model for the electron injection. The relevance for fast ignition is discussed
Tungsten transport in the plasma edge at ASDEX upgrade

Energy Technology Data Exchange (ETDEWEB)

Janzer, Michael Arthur

2015-04-30

Heating (ICRH) limiters on the injected ICRH power was used. The phase and amplitude of the inwardly propagating tungsten signal was then observed at the erosion site and at three radial positions in the main plasma, from which two were identified in the course of this work by a thorough investigation of the tungsten radiation features in the Vacuum Ultra-Violet (VUV) spectral range. The newly found observation sites are located right in the steep gradient region, close to the Edge Transport Barrier (ETB) and slightly further inside at the pedestal top of AUG H-mode discharges. Furthermore, the parallel flows in the SOL have been monitored by spectroscopical means and Langmuir probes. The experimental results were quite unexpected, since the ELM frequency had no influence on the tungsten concentration, and the sole actuator on this quantity was the gas injection rate. The evaluation of the modulated tungsten signal revealed that neither gas puffing nor plasma shape had an measureable influence on the radial tungsten transport processes. In addition, the tungsten erosion sources were only partially responsible for the observed tungsten behavior. These observations inspired a simple model, which balanced the tungsten outflux with the tungsten influx. In this model the impurity exhaust by ELMs is not diffusive, but turbulent and linked to the ELM size. The model predicted a linear dependence between the tungsten concentration and the parallel velocity in the SOL. This linear dependence was confirmed by the spectroscopical evaluation of the SOL parallel flows.
Laser sintering of doped strontium aluminate via modified sol-gel for use as a ceramic pigment; Sinterizacao a laser do aluminato de estroncio dopado via sol-gel modificado para aplicacao como pigmento ceramico

Energy Technology Data Exchange (ETDEWEB)

Soares, F.M. dos S.; Valerio, M.E.G. [Universidade Federal de Sergipe (UFS), Sao Cristovao, SE (Brazil)

2017-01-15

Powder of Dy{sup 3+} co-doped SrAl{sub 2}O{sub 4} :Eu{sup 3+} was produced via proteic sol-gel method, a modified sol-gel route which allows the formation of oxides at lower temperatures than other methods. CO{sub 2} laser sintering was used as a method for heat treatment, effective in reducing trivalent europium ions in doped samples. Thermal analysis of the precursors, performed by TG and DTA, revealed that the crystallization of SrAl{sub 2}O{sub 4} phase occurred at approximately 1060 °C. X-ray diffraction showed that the samples, before and after sintering, had monoclinic and hexagonal phases formation. DLS technique revealed the presence of nanosized and micrometric particles, and particle agglomerates, confirmed by SEM images. Micrographs of the fracture surface of a sintered pellet revealed a high degree of densification caused by heat treatment. Photoluminescence measurements showed that the samples after synthesis and before heat treatment with laser had reddish emission, composed of characteristic narrow emission lines from Eu{sup 3+} and more intense emission when the samples were excited at 265 nm. The laser treatment promoted the reduction of Eu{sup 3+} to Eu{sup 2+} and this effect was confirmed by the presence of a wide emission band in the green region of the spectrum with a maximum emission obtained after excitation at 350 nm. The luminescent decay time of the thermally treated sample was approximately 100 min. Via XRF measurements of acquired frit and DTA and TG of the frit, pigment and mixtures of both, it was noticed good compatibility in terms of thermal processes, that indicated that the pigment has a potential to be used in ceramic tiles. (author)
Development of integrated SOL/Divertor code and simulation study of the JT-60U/JT-60SA tokamaks

International Nuclear Information System (INIS)

Kawashima, H.; Shimizu, K.; Takizuka, T.

2007-01-01

To predict the particle and heat controllability in the divertor of tokamak reactors such as ITER and to optimize the divertor design, comprehensive simulations by integrated modelling with taking in various physical processes are indispensable. For the design study of ITER divertor, the modelling codes such as B2, UEDGE and EDGE2D have been developed, and their results have contributed to the evolution of the divertor concept. In Japan Atomic Energy Agency (JAEA), SOL/divertor codes have also been developed for the interpretation and the prediction on behaviours of plasmas, neutrals and impurities in the SOL/divertor regions. The code development is originally carried out since physics models can be verified quickly and flexibly under the circumstance of close collaboration with JT-60 team. Figure 1 shows our code system, which consists of the 2 dimensional fluid code SOLDOR, the neutral Monte Carlo (MC) code NEUT2D, and the impurity MC code IMPMC. The particle simulation code PARASOL has also been developed in order to establish the physics modelling used in fluid simulations. Integration of SOLDOR, NEUT2D and IMPMC, called the '' SONIC '' code, is being carried out to simulate self-consistently the SOL/divertor plasmas in present tokamaks and in future devices. Combination of the SOLDOR and NEUT2D was completed, which has the features such as 1) high-resolution oscillation-free scheme in solving fluid equations, 2) neutral transport calculation under the fine meshes, 3) success in reduction of MC noise, 4) optimization on the massive parallel computer, etc. The simulation reproduces the X-point MARFE in the JT-60U experiment. It is found that the chemically sputtered carbon at the dome causes the radiation peaking near the X-point. The performance of divertor pumping in JT-60U is evaluated from the particle balances. We also present the divertor designing of JT-60SA, which is the modification program of JT-60U to establish high beta steady-state operation. To
Heat transfer analysis of porous media receiver with different transport and thermophysical models using mixture as feeding gas

International Nuclear Information System (INIS)

Wang, Fuqiang; Tan, Jianyu; Wang, Zhiqiang

2014-01-01

Highlights: • Using local thermal non-equilibrium model to solve heat transfer of porous media. • CH 4 /H 2 O mixture is adopted as feeding gas of porous media receiver. • Radiative transfer equation between porous strut is solved by Rosseland approximation. • Transport and thermophysical models not included in Fluent are programmed by UDFs. • Variations of model on thermal performance of porous media receiver are studied. - Abstract: The local thermal non-equilibrium model is adopted to solve the steady state heat and mass transfer problems of porous media solar receiver. The fluid entrance surface is subjected to concentrated solar radiation, and CH 4 /H 2 O mixture is adopted as feeding gas. The radiative heat transfer equation between porous strut is solved by Rosseland approximation. The impacts of variation in transport and thermophysical characteristics model of gas mixture on thermal performance of porous media receiver are investigated. The transport and thermophysical characteristics models which are not included in software Fluent are programmed by user defined functions (UDFs). The numerical results indicate that models of momentum source term for porous media receiver have significant impact on pressure drop and static pressure distribution, and the radiative heat transfer cannot be omitted during the thermal performance analysis of porous media receiver
Cross-separatrix Coupling in Nonlinear Global Electrostatic Turbulent Transport in C-2U

Science.gov (United States)

Lau, Calvin; Fulton, Daniel; Bao, Jian; Lin, Zhihong; Binderbauer, Michl; Tajima, Toshiki; Schmitz, Lothar; TAE Team

2017-10-01

In recent years, the progress of the C-2/C-2U advanced beam-driven field-reversed configuration (FRC) experiments at Tri Alpha Energy, Inc. has pushed FRCs to transport limited regimes. Understanding particle and energy transport is a vital step towards an FRC reactor, and two particle-in-cell microturbulence codes, the Gyrokinetic Toroidal Code (GTC) and A New Code (ANC), are being developed and applied toward this goal. Previous local electrostatic GTC simulations find the core to be robustly stable with drift-wave instability only in the scrape-off layer (SOL) region. However, experimental measurements showed fluctuations in both regions; one possibility is that fluctuations in the core originate from the SOL, suggesting the need for non-local simulations with cross-separatrix coupling. Current global ANC simulations with gyrokinetic ions and adiabatic electrons find that non-local effects (1) modify linear growth-rates and frequencies of instabilities and (2) allow instability to move from the unstable SOL to the linearly stable core. Nonlinear spreading is also seen prior to mode saturation. We also report on the progress of the first turbulence simulations in the SOL. This work is supported by the Norman Rostoker Fellowship.
Cascade: a review of heat transport and plant design issues

International Nuclear Information System (INIS)

Murray, K.A.; McDowell, M.W.

1984-01-01

A conceptual heat transfer loop for Cascade, a centrifugal-action solid-breeder reaction chamber, has been investigated and results are presented. The Cascade concept, a double-cone-shaped reaction chamber, rotates along its horizontal axis. Solid Li 2 O or other lithium-ceramic granules are injected tangentially through each end of the chamber. The granules cascade axially from the smaller radii at the ends to the larger radius at the center, where they are ejected into a stationary granule catcher. Heat and tritium are then removed from the granules and the granules are reinjected into the chamber. A 50% dense Li 2 O granule throughput of 2.8 m 3 /s is transferred from the reaction chamber to the steam generators via continuous bucket elevators. The granules then fall by gravity through 4 vertical steam generators. The entire transport system is maintained at the same vacuum conditions present inside the reaction chamber
Heat and Mass Transport in Heat Pipe Wick Structures

OpenAIRE

Iverson, B. D.; Davis, T. W.; Garimella, S V; North, M. T.; Kang, S.

2007-01-01

Anovel experimental approach is developed for characterizing the performance of heat pipe wick structures. This approach simulates the actual operation of wick structures in a heat pipe. Open, partially submerged, sintered copper wicks of varying pore size are studied under the partially saturated conditions found in normal heat pipe operation. A vertical wick orientation, where the capillary lift is in opposition to gravity, is selected to test the wicks under the most demanding conditions. ...
A minimization procedure for estimating the power deposition and heat transport from the temperature response to auxiliary power modulation

International Nuclear Information System (INIS)

Eester, Dirk van

2004-01-01

A method commonly used for determining where externally launched power is absorbed inside a tokamak plasma is to examine the temperature response to modulation of the launched power. Strictly speaking, this response merely provides a first good guess of the actual power deposition rather than the deposition profile itself: not only local heat sources but also heat losses and heat wave propagation affect the temperature response at a given position. Making use of this, at first sight non-desirable, effect modulation becomes a useful tool for conducting transport studies. In this paper a minimization method based on a simple conduction-convection model is proposed for deducing the power deposition and transport characteristics from the experimentally measured (electron) energy density response to a modulation of the auxiliary heating power. An L-mode JET example illustrates the potential of the technique
Opportunity's View After Long Drive on Sol 1770

Science.gov (United States)

2009-01-01

NASA's Mars Exploration Rover Opportunity used its navigation camera to take the images combined into this full-circle view of the rover's surroundings just after driving 104 meters (341 feet) on the 1,770th Martian day, or sol, of Opportunity's surface mission (January 15, 2009). Tracks from the drive extend northward across dark-toned sand ripples and light-toned patches of exposed bedrock in the Meridiani Planum region of Mars. For scale, the distance between the parallel wheel tracks is about 1 meter (about 40 inches). Prior to the Sol 1770 drive, Opportunity had driven less than a meter since Sol 1713 (November 17, 2008), while it used the tools on its robotic arm first to examine a meteorite called 'Santorini' during weeks of restricted communication while the sun was nearly in line between Mars and Earth, then to examine bedrock and soil targets near Santorini. The rover's position after the Sol 1770 drive was about 1.1 kilometer (two-thirds of a mile) south southwest of Victoria Crater. Cumulative odometry was 13.72 kilometers (8.53 miles) since landing in January 2004, including 1.94 kilometers (1.21 miles) since climbing out of Victoria Crater on the west side of the crater on Sol 1634 (August 28, 2008). This view is presented as a cylindrical projection with geometric seam correction.
Semiquantum molecular dynamics simulation of thermal properties and heat transport in low-dimensional nanostructures

Science.gov (United States)

Savin, Alexander V.; Kosevich, Yuriy A.; Cantarero, Andres

2012-08-01

We present a detailed description of semiquantum molecular dynamics simulation of stochastic dynamics of a system of interacting particles. Within this approach, the dynamics of the system is described with the use of classical Newtonian equations of motion in which the effects of phonon quantum statistics are introduced through random Langevin-like forces with a specific power spectral density (the color noise). The color noise describes the interaction of the molecular system with the thermostat. We apply this technique to the simulation of thermal properties and heat transport in different low-dimensional nanostructures. We describe the determination of temperature in quantum lattice systems, to which the equipartition limit is not applied. We show that one can determine the temperature of such a system from the measured power spectrum and temperature- and relaxation-rate-independent density of vibrational (phonon) states. We simulate the specific heat and heat transport in carbon nanotubes, as well as the heat transport in molecular nanoribbons with perfect (atomically smooth) and rough (porous) edges, and in nanoribbons with strongly anharmonic periodic interatomic potentials. We show that the effects of quantum statistics of phonons are essential for the carbon nanotube in the whole temperature range T<500K, in which the values of the specific heat and thermal conductivity of the nanotube are considerably less than that obtained within the description based on classical statistics of phonons. This conclusion is also applicable to other carbon-based materials and systems with high Debye temperature like graphene, graphene nanoribbons, fullerene, diamond, diamond nanowires, etc. We show that the existence of rough edges and quantum statistics of phonons change drastically the low-temperature thermal conductivity of the nanoribbon in comparison with that of the nanoribbon with perfect edges and classical phonon dynamics and statistics. The semiquantum molecular
Advanced Intermediate Heat Transport Loop Design Configurations for Hydrogen Production Using High Temperature Nuclear Reactors

International Nuclear Information System (INIS)

Chang Oh; Cliff Davis; Rober Barner; Paul Pickard

2005-01-01

The US Department of Energy is investigating the use of high-temperature nuclear reactors to produce hydrogen using either thermochemical cycles or high-temperature electrolysis. Although the hydrogen production processes are in an early stage of development, coupling either of these processes to the high-temperature reactor requires both efficient heat transfer and adequate separation of the facilities to assure that off-normal events in the production facility do not impact the nuclear power plant. An intermediate heat transport loop will be required to separate the operations and safety functions of the nuclear and hydrogen plants. A next generation high-temperature reactor could be envisioned as a single-purpose facility that produces hydrogen or a dual-purpose facility that produces hydrogen and electricity. Early plants, such as the proposed Next Generation Nuclear Plant (NGNP), may be dual-purpose facilities that demonstrate both hydrogen and efficient electrical generation. Later plants could be single-purpose facilities. At this stage of development, both single- and dual-purpose facilities need to be understood. A number of possible configurations for a system that transfers heat between the nuclear reactor and the hydrogen and/or electrical generation plants were identified. These configurations included both direct and indirect cycles for the production of electricity. Both helium and liquid salts were considered as the working fluid in the intermediate heat transport loop. Methods were developed to perform thermal-hydraulic evaluations and cycle-efficiency evaluations of the different configurations and coolants. The thermal-hydraulic evaluations estimated the sizes of various components in the intermediate heat transport loop for the different configurations. The relative sizes of components provide a relative indication of the capital cost associated with the various configurations. Estimates of the overall cycle efficiency of the various
Heat-pipe effect on the transport of gaseous radionuclides released from a nuclear waste container

International Nuclear Information System (INIS)

Zhou, W.; Chambre, P.L.; Pigford, T.H.; Lee, W.W.L.

1990-11-01

When an unsaturated porous medium is subjected to a temperature gradient and the temperature is sufficiently high, vadose water is heated and vaporizes. Vapor flows under its pressure gradient towards colder regions where it condenses. Vaporization and condensation produce a liquid saturation gradient, creating a capillary pressure gradient inside the porous medium. Condensate flows towards the hot end under the influence of a capillary pressure gradient. This is a heat pipe in an unsaturated porous medium. We study analytically the transport of gaseous species released from a spent-fuel waste package, as affected by a time-dependent heat pipe in an unsaturated rock. For parameter values typical of a potential repository in partially saturated fractured tuff at Yucca Mountain, we found that a heat pipe develops shortly after waste is buried, and the heat-pipe's spatial extent is time-dependent. Water vapor movements produced by the heat pipe can significantly affect the migration of gaseous radionuclides. 12 refs., 6 figs., 1 tab
Influent of Carbonization of Sol Solution at the External Gelation Process on the Quality of Uranium Oxide Kernel

International Nuclear Information System (INIS)

Damunir; Sukarsono

2007-01-01

The influent of carbonization of sol solution at the external gelation process on the quality of uranium oxide kernel was done. Variables observed are the influent of carbon, temperature and time of reduction process of U 3 O 8 kernel resulted from carbonization of sol solution. First of all, uranyl nitrate was reacted with 1 M NH 4 OH solution, producing the colloid of UO 3 . Then by mixing and heating up to the temperature of 60-80 °C, the colloid solution was reacted with PVA, mono sorbitol oleate and paraffin producing of uranium-PVA sol. Then sol solution was carbonized with carbon black of mol ratio of carbon to uranium =2.32-6.62, produce of carbide gel. Gel then washed, dried and calcined at 800 °C for 4 hours to produce of U 3 O 8 kernel containing carbon. Then the kernel was reduced by H 2 gas in the medium of N 2 gas at 500-800 °C, 50 mmHg pressure for 3 hours. The process was repeated at 700 °C, 50 mmHg pressure for 1-4 hours. The characterization of chemical properties of the gel grains and uranium oxide kernel using FTIR covering the analysis of absorption band of infra red spectrum of UO 3 , C-OH, NH 3 , C-C, C-H and OH functional group. The physical properties of uranium oxide covering specific surface area, void volume, mean diameter using surface area meter Nova-1000 and as N 2 gas an absorbent. And O/U ratio of uranium dioxide kernel by gravimetry method. The result of experiment showed that carbonization of sol solution at the external gelation process give influencing the quality of uranium oxide kernel. (author)

Mitigation of strontium and ruthenium release in the CANDU primary heat transport system

Energy Technology Data Exchange (ETDEWEB)

McFarlane, J

1998-03-01

In certain severe accident scenarios, low-volatility fission products can appear to contribute significantly to dose, if treated with undue conservatism. Hence a survey was performed, to see if factors that may mitigate release of strontium and ruthenium could be incorporated into safety analyses, to cover parameters such as location in the fuel matrix under normal operating conditions, release from fuel, transport and deposition in the primary heat transport system and chemistry. In addition chemical equilibrium calculations were performed to investigate the volatility of strontium and ruthenium in the presence of uranium and important fission products. Strontium is very soluble in the U0{sub 2} fuel, up to 12 atom %, and hence release is improbable, particularly under oxidizing conditions until volatilization of the fuel matrix itself occurs. Ruthenium, however, can be released at low temperatures, but only under oxidizing conditions. These may occur during a fuel-handling accident or as a result of an end-fitting failure. Under these conditions, the primary heat transport system cannot be credited for retention. The volatile form of ruthenium, RuO{sub 4}(g), is thermally unstable above 381 K and decomposes to RuO{sub 2}(s) and O{sub 2}(g) upon contact with surfaces, a factor that is likely to minimize the release of ruthenium into the environment. (author)
Sol-Gel SiO2-CaO-P2O5 biofilm with surface engineered for medical application

Directory of Open Access Journals (Sweden)

Sonia Regina Federman

2007-06-01

Full Text Available Sol-gel film in the SiO2-CaO-P2O5 system was prepared from TEOS, TEP, alcohol and hydrated calcium nitrate in an acidic medium. The coatings were deposited on stainless steel using the dip-coating technique. After deposition, the composite was submitted to heat treatment, at different temperatures and exposure times to investigate the influence of such parameters on the surface morphology of the composite. The coated surfaces were characterized by AFM, SEM and FTIR. The present study showed that the formation of different textures (an important parameter in implant fixation could be controlled by temperature and time of heat treatment.
Strength of interactions between immobilized dye molecules and sol-gel matrices.

Science.gov (United States)

Ismail, Fanya; Schoenleber, Monika; Mansour, Rolan; Bastani, Behnam; Fielden, Peter; Goddard, Nicholas J

2011-02-21

In this paper we present a new theory to re-examine the immobilization technique of dye doped sol-gel films, define the strength and types of possible bonds between the immobilized molecule and sol-gel glass, and show that the immobilized molecule is not free inside the pores as was previously thought. Immobilizing three different pH sensitive dyes with different size and functional groups inside the same sol-gel films revealed important information about the nature of the interaction between the doped molecule and the sol-gel matrix. The samples were characterized by means of ultraviolet-visible spectrophotometer (UV-VIS), thermal gravimetric analysis (TGA), mercury porosimetry (MP), nuclear magnetic resonance spectroscopy ((29)Si NMR) and field-emission environmental scanning electron microscopy (ESEM-FEG). It was found that the doped molecule itself has a great effect on the strength and types of the bonds. A number of factors were identified, such as number and types of the functional groups, overall charge, size, pK(a) and number of the silanol groups which surround the immobilized molecule. These results were confirmed by the successful immobilization of bromocresol green (BCG) after a completely polymerized sol-gel was made. The sol-gel consisted of 50% tetraethoxysilane (TEOS) and 50% methyltriethoxysilane (MTEOS) (w/w). Moreover, the effect of the immobilized molecule on the structure of the sol-gel was studied by means of a leaky waveguide (LW) mode for doped films made before and after polymerization of the sol-gel.
Sol-gel encapsulation for controlled drug release and biosensing

Science.gov (United States)

Fang, Jonathan

The main focus of this dissertation is to investigate the use of sol-gel encapsulation of biomolecules for controlled drug release and biosensing. Controlled drug release has advantages over conventional therapies in that it maintains a constant, therapeutic drug level in the body for prolonged periods of time. The anti-hypertensive drug Captopril was encapsulated in sol-gel materials of various forms, such as silica xerogels and nanoparticles. The primary objective was to show that sol-gel silica materials are promising drug carriers for controlled release by releasing Captopril at a release rate that is within a therapeutic range. We were able to demonstrate desired release for over a week from Captopril-doped silica xerogels and overall release from Captopril-doped silica nanoparticles. As an aside, the antibiotic Vancomycin was also encapsulated in these porous silica nanoparticles and desired release was obtained for several days in-vitro. The second part of the dissertation focuses on immobilizing antibodies and proteins in sol-gel to detect various analytes, such as hormones and amino acids. Sol-gel competitive immunoassays on antibody-doped silica xerogels were used for hormone detection. Calibration for insulin and C-peptide in standard solutions was obtained in the nM range. In addition, NASA-Ames is also interested in developing a reagentless biosensor using bacterial periplasmic binding proteins (bPBPs) to detect specific biomarkers, such as amino acids and phosphate. These bPBPs were doubly labeled with two different fluorophores and encapsulated in silica xerogels. Ligand-binding experiments were performed on the bPBPs in solution and in sol-gel. Ligand-binding was monitored by fluorescence resonance energy transfer (FRET) between the two fluorophores on the bPBP. Titration data show that one bPBP has retained its ligand-binding properties in sol-gel.
Pemodelan Desain Sol Sepatu dengan Inovasi Penambahan Wave Spring

Directory of Open Access Journals (Sweden)

Redyarsa Dharma Bintara

2015-07-01

Full Text Available Desain sepatu sport berkembang pesat dengan tujuan mengurangi cedera dan meningkatkankenyamanan pengguna. Pengurangan cedera dilakukan dengan cara memperbesar energi yangdiserap dari beban akibat pengguna berlari atau melompat. Pada penelitian ini dilakukanpenambahan wave spring yang digunakan sebagai mekanisme penyerap beban.Pemodelandilakukan pada sol sepatu dengan menggunakan bantuan software finite element method (FEMAnsys 14.5 Academic. Model awal dilakukan untuk mengetahui batas deformasi sol sepatu yangakan dimanfaatkan sebagai input model berikutnya yaitu model dengan diberikan inovasipenambahan wave spring. Analisa difokuskan pada sol sepatu bagian belakang (tumit kaki.Darihasil simulasi, didapatkan bahwa penyerapan energi sol sepatu dengan penambahan wave springlebih besar daripada penyerapan energi sol sepatu tanpa penambahan wave spring, sehinggapenambahan wave spring memungkinkan untuk diaplikasikan pada sol sepatu sport.Kata kunci: Penyerapan energi, wave spring, sol sepatu. Sport shoe design had been developed rapidly with the purpose to reduce injuries and increaseuser comfort. Reduction of injury is done by enlarging the energy absorbed from the user running orjumping load. In this study, the addition of the wave spring is used as the load absorbingmechanism. The shoes sole is modeled by using finite element method (FEM software Ansys 14.5Academic. Initial model was conducted to determine the deformation boundary in soles which willbe used as input to the next model for the wave spring addition innovation. Analysis focused onshoe sole on heel foot. From the simulation results, it was found that the energy absorption shoessoles with the addition of the wave spring is greater than the energy absorption soles without theaddition of wave spring. It can be concluded that the addition of a spring wave can be applied to thesoles of sports shoes.Keywords: Energy absorb, wave spring, shoe sole, deformation boundary
Magnetic Field Enhancement of Heat Transport in the 2D Heisenberg Antiferromagnet K_2V_3O_8

Science.gov (United States)

Sales, B. C.; Lumsden, M. D.; Nagler, S. E.; Mandrus, D.; Jin, R.

2002-03-01

The thermal conductivity and heat capacity of single crystals of the spin 1/2 quasi-2D Heisenberg antiferromagnet K_2V_3O8 have been measured from 1.9 to 300 K in magnetic fields from 0 to 8T. The data are consistent with resonant scattering of phonons by magnons near the zone boundary and heat transport by long wavelength magnons. The magnon heat transport only occurs after the small anisotropic gap at k=0 is closed by the application of a magnetic field. The low temperature thermal conductivity increases linearly with magnetic field after the gap has been closed. Oak Ridge National Laboratory is managed by UT-Battelle LLC for the U.S. Department of Energy under Contract No. DE-AC05-00R22725.
Time for a Change; Spirit's View on Sol 1843 (Polar)

Science.gov (United States)

2009-01-01

NASA's Mars Exploration Rover Spirit used its navigation camera to take the images that have been combined into this full-circle view of the rover's surroundings during the 1,843rd Martian day, or sol, of Spirit's surface mission (March 10, 2009). South is in the middle. North is at both ends. This view is presented as a polar projection with geometric seam correction. North is at the top. The rover had driven 36 centimeters downhill earlier on Sol 1854, but had not been able to get free of ruts in soft material that had become an obstacle to getting around the northeastern corner of the low plateau called 'Home Plate.' The Sol 1854 drive, following two others in the preceding four sols that also achieved little progress in the soft ground, prompted the rover team to switch to a plan of getting around Home Plate counterclockwise, instead of clockwise. The drive direction in subsequent sols was westward past the northern edge of Home Plate.
Time for a Change; Spirit's View on Sol 1843 (Vertical)

Science.gov (United States)

2009-01-01

NASA's Mars Exploration Rover Spirit used its navigation camera to take the images that have been combined into this full-circle view of the rover's surroundings during the 1,843rd Martian day, or sol, of Spirit's surface mission (March 10, 2009). South is in the middle. North is at both ends. This view is presented as a vertical projection with geometric seam correction. North is at the top. The rover had driven 36 centimeters downhill earlier on Sol 1854, but had not been able to get free of ruts in soft material that had become an obstacle to getting around the northeastern corner of the low plateau called 'Home Plate.' The Sol 1854 drive, following two others in the preceding four sols that also achieved little progress in the soft ground, prompted the rover team to switch to a plan of getting around Home Plate counterclockwise, instead of clockwise. The drive direction in subsequent sols was westward past the northern edge of Home Plate.
Water-based sol-gel synthesis of hydroxyapatite: process development.

Science.gov (United States)

Liu, D M; Troczynski, T; Tseng, W J

2001-07-01

Hydroxyapatite (HA) ceramics were synthesized using a sol-gel route with triethyl phosphite and calcium nitrate as phosphorus and calcium precursors, respectively. Two solvents, water and anhydrous ethanol, were used as diluting media for HA sol preparation. The sols were stable and no gelling occurred in ambient environment for over 5 days. The sols became a white gel only after removal of the solvents at 60 degrees C. X-ray diffraction showed that apatitic structure first appeared at a temperature as low as 350 degrees C. The crystal size and the HA content in both gels increase with increasing calcination temperature. The type of initial diluting media (i.e., water vs. anhydrous ethanol) did not affect the microstructural evolution and crystallinity of the resulting HA ceramic. The ethanol-based sol dip-coated onto a Ti substrate, followed by calcination at 450 degrees C, was found to be porous with pore size ranging from 0.3 to 1 microm. This morphology is beneficial to the circulation of physiological fluid when the coating is used for biomedical applications. The satisfactory adhesion between the coating and substrate suggests its suitability for load-bearing uses.
The influence of p H and UV visible absorption on hydrolysis stage and gel behavior of glasses synthesized by sol-gel

International Nuclear Information System (INIS)

Khosravi Saghezchi, M.; Sarpoolaky, H.; Heshmatpour, F.

2008-01-01

Lead-containing glass borosilicate was synthesized by Sol-gel technique using metal alkoxide such as tetra ethyleorthosilicate, Al-sec-butoxide and trimethyl borate. The sol containing tetra ethyle ortho silicate converts to gel during drop wise addition of Al-alkoxide while inorganic lead salt was added in the last stage of gelation to prepare the alcogels. The specimens were dried at room temperature to set then heated at 600 d eg C quickly to avoid crystallization preparing a glass containing 63 weight percent lead oxide. The influence of p H on absorption behavior of the sols studied by UV visible technique so the characteristic of the gel, alcogel and xerogel were studied in the different acidic concentrations. The UV spectrums show that the higher the acidity of the hydrolysis stages, the higher the absorbance. The results showed the sample with 63 weight percent lead was found fully amorphous. Microstructure and phase analysis of the glass powders were investigated by X-ray diffraction, X-ray fluorescence and scanning electron microscopy equipped with energy dispersive spectroscopy analysis
Study of heat flux deposition in the Tore Supra Tokamak; Etude des depots de chaleur dans le tokamak Tore Supra

Energy Technology Data Exchange (ETDEWEB)

Carpentier, S.

2009-02-15

Accurate measurements of heat loads on internal tokamak components is essential for protection of the device during steady state operation. The optimisation of experimental scenarios also requires an in depth understanding of the physical mechanisms governing the heat flux deposition on the walls. The objective of this study is a detailed characterisation of the heat flux to plasma facing components (PFC) of the Tore Supra tokamak. The power deposited onto Tore Supra PFCs is calculated using an inverse method, which is applied to both the temperature maps measured by infrared thermography and to the enthalpy signals from calorimetry. The derived experimental heat flux maps calculated on the toroidal pumped limiter (TPL) are then compared with theoretical heat flux density distributions from a standard SOL-model. They are two experimental observations that are not consistent with the model: significant heat flux outside the theoretical wetted area, and heat load peaking close to the tangency point between the TPL and the last closed field surface (LCFS). An experimental analysis for several discharges with variable security factors q is made. In the area consistent with the theoretical predictions, this parametric study shows a clear dependence between the heat flux length lambda{sub q} (estimated in the SOL (scrape-off layer) from the IR measurements) and the magnetic configuration. We observe that the spreading of heat fluxes on the component is compensated by a reduction of the power decay length lambda{sub q} in the SOL when q decreases. On the other hand, in the area where the derived experimental heat loads are not consistent with the theoretical predictions, we observe that the spreading of heat fluxes outside the theoretical boundary increases when q decreases, and is thus not counterbalanced. (author)
Modelling of activity transport in primary heat transport (PHT) system of Indian PHWRs

International Nuclear Information System (INIS)

Markandeya, S.G.; Pujari, P.K.; Gandhi, H.C.; Venkateswaran, G.; Narasimhan, S.V.; Krishnarao, K.S.; Mathur, P.K.; Venkat Raj, V.

2000-01-01

Nuclear Power plants (NPPs) are designed and built with the aim of minimising the occupational exposure to the operational and maintenance staff. Despite the use of prudently selected materials of construction with high corrosion resistance and adopting very stringent water chemistry controls during operation the build-up of activity in the Primary Heat Transport (PHT) systems of NPPs has been found to be unavoidable. The Indian Pressurised Heavy Water Reactors (PHWRs) are no exception to this. To enable advance planning of maintenance work and the decontamination schedules, it is necessary to perform the off-site calculations to predict the activity buildup in the PHT circuits of the NPPs. A computer code ANUCRUD is under development for predicting the corrosion product and activity transport behaviour in the PHT circuits of Indian PHWRs. The present paper briefly describes some of the salient features of the code ANUCRUD. As a first attempt, preliminary calculations for predicting corrosion product crud concentration buildup in the PHT circuit of the 220 MWe Indian PHWR have been carried out using the code. The findings of these studies are discussed in the paper. Finally, the further improvements proposed to be carried out in the code are also brought out in the paper. (author)
Production of continuous mullite fiber via sol-gel processing

Science.gov (United States)

Tucker, Dennis S.; Sparks, J. Scott; Esker, David C.

1990-01-01

The development of a continuous ceramic fiber which could be used in rocket engine and rocket boosters applications was investigated at the Marshall Space Flight Center. Methods of ceramic fiber production such as melt spinning, chemical vapor deposition, and precursor polymeric fiber decomposition are discussed and compared with sol-gel processing. The production of ceramics via the sol-gel method consists of two steps, hydrolysis and polycondensation, to form the preceramic, followed by consolidation into the glass or ceramic structure. The advantages of the sol-gel method include better homogeneity and purity, lower preparation temperature, and the ability to form unique compositions. The disadvantages are the high cost of raw materials, large shrinkage during drying and firing which can lead to cracks, and long processing times. Preparation procedures for aluminosilicate sol-gel and for continuous mullite fibers are described.
Current & Heat Transport in Graphene Nanoribbons: Role of Non-Equilibrium Phonons

Science.gov (United States)

Pennington, Gary; Finkenstadt, Daniel

2010-03-01

The conducting channel of a graphitic nanoscale device is expected to experience a larger degree of thermal isolation when compared to traditional inversion channels of electronic devices. This leads to enhanced non-equilibrium phonon populations which are likely to adversely affect the mobility of graphene-based nanoribbons due to enhanced phonon scattering. Recent reports indicating the importance of carrier scattering with substrate surface polar optical phonons in carbon nanotubes^1 and graphene^2,3 show that this mechanism may allow enhanced heat removal from the nanoribbon channel. To investigate the effects of hot phonon populations on current and heat conduction, we solve the graphene nanoribbon multiband Boltzmann transport equation. Monte Carlo transport techniques are used since phonon populations may be tracked and updated temporally.^4 The electronic structure is solved using the NRL Tight-Binding method,^5 where carriers are scattered by confined acoustic, optical, edge and substrate polar optical phonons. [1] S. V. Rotkin et al., Nano Lett. 9, 1850 (2009). [2] J. H. Chen, C. Jang, S. Xiao, M. Ishigami and M. S. Fuhrer, Nature Nanotech. 3, 206 (2008). [3] V. Perebeinos and P. Avouris, arXiv:0910.4665v1 [cond-mat.mes-hall] (2009). [4] P. Lugli et al., Appl. Phys. Lett. 50, 1251 (1987). [5] D. Finkenstadt, G. Pennington & M.J. Mehl, Phys. Rev. B 76, 121405(R) (2007).
FEFLOW finite element modeling of flow, mass and heat transport in porous and fractured media

CERN Document Server

Diersch, Hans-Jörg G

2013-01-01

Placing advanced theoretical and numerical methods in the hands of modeling practitioners and scientists, this book explores the FEFLOW system for solving flow, mass and heat transport processes in porous and fractured media. Offers applications and exercises.
Ceramic protective coatings applied by sol-gel or electrophoresis

International Nuclear Information System (INIS)

Stoch, A.

1993-01-01

Sol-gel and electrophoresis are the complementary techniques which may be used for obtaining the ceramic coatings. The composition of such a coatings depends on the composition of electrophoresis bath or sol solution. Thermal treatment is used for densifying the coating and promoting the adherence of coating to the substrate. In presented work silica, silica-alumina or alumina coatings are applied by sol-gel dip coating procedure on steel, aluminium or ceramic substrates. Electrophoresis is employed for obtaining zirconia, alumina or hydroxyapatite coatings on stainless steel. (author). 7 refs
Study of heat transport in structured soil under grass cover. Dual-continuum approach

Czech Academy of Sciences Publication Activity Database

Votrubová, J.; Dohnal, M.; Tesař, Miroslav; Vogel, T.

2011-01-01

Roč. 13, - (2011), s. 7414 ISSN 1607-7962. [European Geosciences Union General Assembly 2011. 03.04.2011-08.04.2011, Vienna] R&D Projects: GA ČR GA205/08/1174 Institutional research plan: CEZ:AV0Z20600510 Keywords : water and heat transport * model S1D * Sumava Mts. Subject RIV: DA - Hydrology ; Limnology
Investigation of thermal energy transport from an anisotropic central heating element to the adjacent channels: A multipoint flux approximation

KAUST Repository

Salama, Amgad; Sun, Shuyu; El-Amin, Mohamed

2015-01-01

anisotropy of the heating element and/or the encompassing plates on thermal energy transport to the fluid passing through the two channels. When the medium is anisotropic with respect to thermal conductivity; energy transport to the neighboring channels
Opportunity's View After Drive on Sol 1806

Science.gov (United States)

2009-01-01

NASA's Mars Exploration Rover Opportunity used its navigation camera to take the images combined into this full-circle view of the rover's surroundings just after driving 60.86 meters (200 feet) on the 1,806th Martian day, or sol, of Opportunity's surface mission (Feb. 21, 2009). North is at the center; south at both ends. Tracks from the drive extend northward across dark-toned sand ripples and light-toned patches of exposed bedrock in the Meridiani Planum region of Mars. For scale, the distance between the parallel wheel tracks is about 1 meter (about 40 inches). Engineers designed the Sol 1806 drive to be driven backwards as a strategy to redistribute lubricant in the rovers wheels. The right-front wheel had been showing signs of increased friction. The rover's position after the Sol 1806 drive was about 2 kilometer (1.2 miles) south southwest of Victoria Crater. Cumulative odometry was 14.74 kilometers (9.16 miles) since landing in January 2004, including 2.96 kilometers (1.84 miles) since climbing out of Victoria Crater on the west side of the crater on Sol 1634 (August 28, 2008). This view is presented as a cylindrical projection with geometric seam correction.
Transport stress induces heart damage in newly hatched chicks via blocking the cytoprotective heat shock response and augmenting nitric oxide production.

Science.gov (United States)

Sun, F; Zuo, Y-Z; Ge, J; Xia, J; Li, X-N; Lin, J; Zhang, C; Xu, H-L; Li, J-L

2018-04-20

Transport stress affects the animal's metabolism and psychological state. As a pro-survival pathway, the heat shock response (HSR) protects healthy cells from stressors. However, it is unclear whether the HSR plays a role in transport stress-induced heart damage. To evaluate the effects of transport stress on heart damage and HSR protection, newly hatched chicks were treated with transport stress for 2 h, 4 h and 8 h. Transport stress caused decreases in body weight and increases in serum creatine kinase (CK) activity, nitric oxide (NO) content in heart tissue, cardiac nitric oxide syntheses (NOS) activity and NOS isoforms transcription. The mRNA expression of heat shock factors (HSFs, including HSF1-3) and heat shock proteins (HSPs, including HSP25, HSP40, HSP47, HSP60, HSP70, HSP90 and HSP110) in the heart of 2 h transport-treated chicks was upregulated. After 8 h of transport stress in chicks, the transcription levels of the same HSPs and HSF2 were reduced in the heart. It was also found that the changes in the HSP60, HSP70 and HSP90 protein levels had similar tendencies. These results suggested that transport stress augmented NO generation through enhancing the activity of NOS and the transcription of NOS isoforms. Therefore, this study provides new evidence that transport stress induces heart damage in the newly hatched chicks by blocking the cytoprotective HSR and augmenting NO production.

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