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Selected case studies of auroral structure/activity observed at different local times on the dayside are presented and discussed in the context of electrodynamic coupling between the different magnetospheric boundary regions and the ionosphere. The first case addresses the question of the auroral signatures of the two boundary regions referred to as cusp and cleft/LLBL. Combined ground-based and satellite data reveal the different latitudinal zones of auroral forms/particle precipitation/field-aligned current and the relationship with the respective magnetospheric plasma populations, i.e. CPS, BPS, LLBL, and the plasma mantle. Midday auroral breakup events and the related ionospheric ion drift and magnetic observations show many of the features that have been predicted to be ionospheric signatures of flux transfer events. An alternative explanation that has been proposed by others, i.e. ionospheric effect of magnetopause ...

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In this study we extend the analysis of magnetopause crossings observed with Magnetospheric Plasma Analyzer measurements to examine a much larger statistical data set. This study examines 39 maiznetosheath/LLBL intervals from 79 spacecraft-months of observations: these observations were taken from a survey of data from the start of each spacecraft mission and extending through March 1993. In contrast to the previous findings, we find no evidence for a significant dawn/dusk asymmetry in geosynchronous magnetopause crossings.

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This book is divided into the following chapters: the atmospheric boundary layer; atmospheric diffusion; pollutants and their properties; and environmental monitoring and impact.

British Library Electronic Table of Contents (United Kingdom)

An investigation into a three-dimensional, curved shock wave interacting with a three-dimensional, curved boundary layer on a slender body is presented. Three different nose profiles mounted on a cylindrical body were tested in a supersonic wind tunnel and numerically simulated by solving the Navier?Stokes equations. The conical and hemispherical nose profiles tested were found to generate shock waves of sufficient strength to separate the boundary layer on the cylinder, while the shock wave generated by the ogival profile did not separate the boundary layer. For the separated flow, separation was found to occur predominantly on the windward side of the cylinder with the lee-side remaining shielded from the direct impact of the incident shock wave. A thickening of the boundary layer on the...

Science.gov (United States)

... Separation," AGARD,Rept 272, April 1960, ... Leading Edge Effect on Supersonic Boundary Layer Flow." ... of Gas Injection in Separated Flows." TCEA, ...

Science.gov (United States)

The Baldwin-Lomax model is used in many CFD codes because it is quick and easy to implement. In this

Science.gov (United States)

The synthesis of experimental data concerning the effect of jet stagnation conditions on the drag of various afterbodies is presented. Jet pressure ratio effect on boattail pressure and on boundary layer separation is analyzed. This study is made for several values of the boundary layer thickness, taking into account the fact that some test rigs make its control possible by means of tangential blowing.

Science.gov (United States)

The dynamical factors controlling the mean state and variability of the east Pacific intertropical convergence zone (ITCZ) and the associated cross-equatorial boundary layer flow are investigated using observations from the East Pacific Investigation of Climate (EPIC2001) project. The tropical east Pacific exhibits a southerly boundary layer flow that terminates in the ITCZ. This flow is induced by the strong meridional sea surface temperature (SST) gradient in the region. Away from the equator and from deep convection, it is reasonably well described on a day-to-day basis by an extended Ekman balance model. Variability in the strength and northward extent of this flow is caused by variations in free-tropospheric pressure gradients that either reinforce or oppose the pressure gradient associated with the SST gradient. These free-tropospheric gradients are caused by easterly waves, tropical cyclones, and ...

International Nuclear Information System (INIS)

In this article, the ability of artificial neural networks in prediction of separation in steady two dimensional boundary layer flows is studied. Data for network training is extracted from numerical solution of an ODE obtained from Von Karman integral equation with approximate one parameter Pohlhousen velocity profile. As an appropriate neural network, a two layer radial basis generalized regression artificial neural network is used. The results shows good agreements between the overall behavior of the flow fields predicted by the artificial neural network and the actual flow fields for some cases. The method easily can be extended to unsteady separation and turbulent as well as compressible boundary layer flows. (author)

Science.gov (United States)

eling of the Stefan Problem, AIAA J., vol. 22, Nov. 1984, pp. 1685-1690. Schlichting, H., Boundary-Layer Theory. F. J. Cerra, ED. ...

Science.gov (United States)

Jul 8, 2008 ... This case involves the flow over the ONERA M6 wing. ... The wind tunnel tests are documented by Schmitt and Charpin in the AGARD Report AR-138 ... supersonic flow, shocks, and turbulent boundary layers separation). ...

Science.gov (United States)

A short account is given of the difficulties encountered in temperature measurement of boundary layers and a comparison of two types of thermometers, an infrared radiometer and mercury in glass thermometer. (Author)

International Nuclear Information System (INIS)

We consider the spin-up of the white dwarf in non-magnetic cataclysmic variables (CVs) during secular evolution. If this is unresisted, CVs are quenched as boundary-layer emitters once the binary period has decreased by #approx# 1 hr. Angular momentum loss in nova explosions may, however, prevent the star reaching breakup. If the explosions remove (1 + #epsilon#) x the mass accreted between outbursts, values 0.5 < #approx# #epsilon# < #approx# 1 allow CVs to be modest boundary-layer emitters for most of their lifetimes. Spectral effects will limit their detection as soft X-ray sources. (author).

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This report presents the status of development of a three-dimensional conceptual model for the unconfined aquifer system at Hanford. A conceptual model is needed to support development of a realistic three-dimensional numerical model for predicting ground-water flow and the transport of contaminants. The report focuses on developing a hydrogeologic framework, assessing available hydraulic property data, describing flow-system boundaries, and evaluating areal recharge and leakage. Geologic descriptions of samples obtained during well drilling were used to prepare cross sections that correlate relatively continuous layers. The layers were defined based on textural differences that are expected to reflect differences in hydraulic properties. Assigning hydraulic properties to the layers is a critical part of the conceptual model. Available hydraulic property data for the study area were compiled and were ...

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Solid recycling of AZ31 Mg alloy with vapor deposition coating layer of high purity Mg was evaluated. In the open die forging experiments, two AZ31 Mg alloy specimens with the pure Mg layer were sufficiently bonded by forging at 673 K. Furthermore, the Al and Zn of the AZ31 substrate diffused up to the center of the pure Mg layer. By the theoretical analysis, it is suggested that the grain boundary diffusion enhanced by grain refinement due to hot forging contributes to the solid state bonding of the specimens. Also, the solid recycled specimen was fabricated from the AZ31 Mg substrate with pure Mg layer by hot extrusion at 673 K. The solid recycled specimen showed almost the same tensile properties as the virgin extruded specimen. This is probably related not only to the grain boundary diffusion but also severe plastic deformation by hot extrusion. (orig.)

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Since living things began their activities on the earth, the extermination of living things in large number on global scale occurred twice 230 million years ago (P-Tr boundary) and 65 million years ago (K-T boundary). As to the cause of exterminating living things in short period, there are volcano eruption theory, meteorite collision theory and so on, but still it is not decided. Therefore, as to the strata of P-Tr boundary in south-western part of China where it has been known the preservation of P-Tr strata is especially good, the existence of elements was measured by instrument neutron activation analysis and ICP-MS, and the state of change was examined. According to the results, the change occurred at the P-Tr boundary on the earth, and further, the possibility of meteorite collision by paying attention to Ir were examined. The samples, the neutron activation analysis, the ICP-MS and the results ...

British Library Electronic Table of Contents (United Kingdom)

In this article, the authors analyzed the effect of thermal conductivity on unsteady magnetohydrodynamic (MHD) free convection in a micro-polar fluid past a semi-infinite vertical porous plate. The fluid thermal conductivity is assumed to vary as a linear function of temperature. By using the Chebyshev collocation method in the spatial direction and the Crank-Nicolson method in the time direction, the boundary layer equations are transformed into a linear algebraic system. There are several material parameters whose affect on the flow have been studied, for instance, thermal conductivity, radiation, magnetic, micro-polar, suction (or injection) parameters, and Prandtl number. Boundary layer and Boussineq approximations have been introduced together to describe the flow field. The domain of...

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A method of modeling freeze-thaw cycles of naturally deposited snowpacks is presented. The model involves the Stefan condition as an independent governing equation on the exterior moving boundary to calculate snowpack thinning, flow of water through a variably saturated layered porous medium as described by the Richards equation, and heat conduction with a phase change. The heat conduction problem was treated in two ways. Local heat conduction between a snow grain and its surrounding water film was treated by using a simple energy balance. Global heat conduction with a phase change (the Stefan problem) was introduced to calculate the space-time temperature distribution. In order to handle multiple interior moving boundaries, a specific form of the enthalpy formulation was used for heat conduction with a phase change. Changing material properties were considered according to the calculated meltwater refreezing. 48 refs., 11 ...

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In this study we discuss an unsteady free convection MHD flow past semi-infinite vertical porous plate. We have considered the flow in the presence of a strong magnetic field and therefore the electromagnetic force is very large. This brings in the phenomenon of Hall and Ion-slip currents. The effects of these two parameters together with that of viscous dissipation and radiation absorption among others on velocity, temperature and concentration profiles are presented. The profiles are presented graphically. As the partial differential equations governing this problem are highly non-linear they are solved numerically by a finite difference method. It is found that in presence of heating of the plate by free convection current the velocity boundary layer thickness decreases.

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The boundary-integral equation method is well suited for the calculation of the dynamic-stiffness matrix of foundations embedded in a layered visco-elastic halfspace (or a transmitting boundary of arbitrary shape), which represents an unbounded domain. It also allows pile groups to be analyzed, taking pile-soil-pile interaction into account. The discretization of this boundary-element method is restricted to the structure-soil interface. All trial functions satisfy exactly the field equations and the radiation condition at infinity. In the indirect boundary-element method distributed source loads of initially unknown intensities act on a source line located in the excavated part of the soil and are determined such that the prescribed boundary conditions on the structure-soil interface are satisfied in an average sense. In the two-dimensional case the variables ...

Science.gov (United States)

Numerical results on aeroelastic standard configurations are presented. The methods used for two dimensional configurations include the small perturbations approach for inviscid flow, coupling methods for unseparated flow, coupling methods for unseparated or separated, laminar or turbulent boundary layers, and a numerical solution of the Euler equations for inviscid flow. The three dimensional configurations are studied by the transonic small disturbance approach. The detailed results are given.

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The authors summarize EUVE's contribution to the study of the boundary layer emission of high accretion-rate nonmagnetic cataclysmic variables, especially the dwarf novae SS Cyg, U Gem, VW Hyi, and OY Car in outburst. They discuss the optical and EUV light curves of dwarf nova outbursts, the quasi-coherent oscillations of the EUV flux of SS Cyg, the EUV spectra of dwarf novae, and the future of EUV observations of cataclysmic variables.

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The effect of flame temperature on the Moza-Austin sticking test has been evaluated by increasing the adiabatic flame temperature used to melt the pellet and make it drop. It was found that the variation of apparent contact angle with substrate temperature, for an oxidized steel substrate, was almost independent of flame temperature over the range of 1750-2500 C. However, the strength of adhesion to the substrate increased with higher flame temperature at each substrate temperature. The adhesion force of a drop frozen on the substrate at constant temperature also increased with time up to about one h. This indicated that the adhesion was not caused solely by mechanical anchoring of solidified glass in the pores of the oxide layer. Reduction of the substrate temperature to lower temperatures after attachment of the drop caused lower strength of adhesion, but this was partially restored by raising the temperature. This also suggested a continuing solid-state ...

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A brief review and assessment of field measurement programs that provide data for mixed layer diffusion research is presented. The majority of programs emphasize either the meteorological aspects of the mixed layer or plume characterization. Few programs are available that provide the complimentary blend of plume and appropriate meteorological measurements needed to adequately validate mixed layer diffusion theory. Three major U.S. EPA (Environmental Protection Agency) field programs that provide data bases for model development and validation of mixed layer diffusion processes are described and discussed in more detail. The Regional Air Pollution Study (RAPS) focused on measurements of surface and mixed layer turbulent transport processes in the urban environment. The Tennessee Plume Study (TPS) obtained a database with coincident measurement of boundary ...

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Focus Ion Beam (FIB) milling has greatly extended the utility of atom probe and TEM because it enables sample preparation with a level of dimensional control never before possible. Using FIB it is possible to extract the samples from desired and very specific locations. The artifacts associated with this sample preparation method must also be fully understood. In this work issues specifically relevant to the FIB milling of aluminum alloys are presented. After using the FIB as a sample preparation technique it is evident that gallium will concentrate in three areas of the sample: on the surface, on grain boundaries and at interphase boundaries. This work also shows that low energy Ar ion nanomilling is potentially quite effective for removing gallium implantation layers and gallium from the internal surfaces of aluminum thin foils.

International Nuclear Information System (INIS)

The effects of CH_4 content at nitriding step in the low temperature two-step plasma treatment (carburizing+nitriding) on the surface characteristics of AISI304L stainless steel were investigated. The low temperature plasma carburizing was carried out at 550 .deg. C for 5h in a gas mixture of H_2 Ar and CH_4. The thickness of a carburized layer increased up to about 30 #mu#m and corrosion resistance of the layer decreased due to the precipitation formed at the grain boundary. After carburizing, a low temperature plasma nitriding was subsequently performed in the same chamber at 400 .deg. C for 15h to improve corrosion resistance and to further increase the surface hardness. The surface hardness of a N-enriched layer after nitriding reached up to 1,200HV_0_._1, which is much higher than that of as-carburized layer(750 HV_0_._1). The post nitriding process had a beneficial effect on ...

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A numerical study of laminar flow and heat transfer in an array of stacked rectangular plates is presented. The array is placed in a uniform stream, and the plates are subjected to a constant surface heat flux. This flow configuration is relevant to a number of practical heat transfer devices with finned surfaces. The computations were performed using a finite volume solution of the steady, two-dimensional Navier-Stokes equations and energy equation. A numerical scheme that reduces numerical diffusion is used to discretize the equations. The dominant feature of the flow is the separation, and subsequent reattachment of, the boundary layer, which takes place at Reynolds numbers greater than about 75. The separation first occurs downstream of the leading edge of the plate; then as Re increases, the separation point moves upstream and remains fixed at the leading edge, and the reattachment length increases linearly with Re. The appearance and ...

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Discussed in this paper are the P-wave and S-wave zero-offset VSPs carried out utilizing boreholes located in Nada Ward, Kobe City, and Hokudan-cho, Hyogo Prefecture, as part of the deep layer boring survey following Hanshin Earthquake Disaster. This effort aims at the elucidation of P-wave and S-wave velocity structures, high-precision identification of data obtained by the surface reflection method, and collection of basic data for active faults investigation in the future. Among the velocity structures obtained for various layers, the S-wave velocity structures in particular agree with the stratigraphy excellently and may be utilized in seismic analyses to be conducted in the future. Reflection from geological boundaries is received with precision, providing accurate information about correlation between reflection and geological cross sections. The records will be useful in formulating plans for reflection surveys for ...

DEFF Research Database (Denmark)

Axially symmetric waveguides, resonators, and scatterers of arbitrary cross section and anisotropy in the cross section can be modeled rigorously with use of 2-D Cartesian-grid based codes by means of mere redefinition of material permittivity and permeability profiles. The method is illustrated by the frequencydomain simulations of resonant modes in a circular-cylinder cavity with perfectly conducting walls, a shielded uniaxial anisotropic dielectric cylinder, and an open dielectric sphere for which, after proper implementation of the perfectly matched layer boundary conditions, the radiation quality factor is also determined.

Science.gov (United States)

The present contribution deals with the thermophoresis particle deposition and thermal radiation effects on the flow, heat and mass transfer characteristics in a viscous fluid over a semi-infinite vertical porous plate. The governing boundary layer equations are written into a dimensionless form by similarity transformations. The transformed coupled nonlinear ordinary differential equations are solved numerically by means of the fourth-order Runge-Kutta method with a shooting technique. The effects of different parameters on the dimensionless velocity, temperature, and concentration profiles are shown graphically. In addition, results for the local skin-friction coefficient, the local Nusselt number, and the local Sherwood number are tabulated and discussed.

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A series of upper tropospheric radon concentration measurements made over the eastern Pacific and west coast of the United States during the summers of 1983 and 1984 has revealed the occurrence of unexpectedly high (>16 pCi/SCM) radon concentrations for 9 of the 61 measurements (and 6 of the 13 flights). A frequency distribution plot of the set of 61 observations shows a distinct bimodal distribution, with approximately 2/5 of the observations falling close to 1 pCi/SCM, and 3/5 falling in a high concentration mode centered at about 11 pCi/SCM. Trajectory and synoptic analyses for two of the flights on which such high radon concentrations were observed indicate that this radon-rich air originated in the Asian boundary layer, ascended in cumulus updrafts, and was carried eastward in the fast moving air on the anti-cyclonic side of the upper tropospheric jet. Transit times were of the order of 3 days; however, in one instance, transport from ...

Science.gov (United States)

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

International Nuclear Information System (INIS)

Slurry aluminizing is one method of protecting titanium alloys and intermetallics at temperatures at which oxidation would otherwise significantly degrade mechanical properties. The technique produces a continuous layer of alumina-forming TiAl_3 on exposed surfaces. The influence of composition, film thickness, and diffusion temperature upon the oxidation resistance of these slurry aluminides was studied in cyclic tests to 816degC (1500deg F). Degradation of slurry aluminized #beta#-titanium alloy and #alpha#-Z titanium aluminide intermetallic occurs by localized oxidation at cracks in the coating layer. These cracks are probably due to mismatch of coefficients of thermal expansion between the coatings and substrates. Addition of silicon to the slurry modifies the oxidation behaviour around a crack by introducing a continuous layer of titanium silicide at the boundary of the aluminide coating and ...

International Nuclear Information System (INIS)

The effects of gate and drain bias stresses on thin film transistors fabricated in polysilicon films crystallized using the advanced sequential lateral solidification excimer laser annealing (SLS ELA) process, which yields very elongated polysilicon grains and allows the fabrication of TFTs without grain boundary barriers to current flow, are investigated as a function of the active layer thickness and of the TFT orientation relative to the grains. The application of hot carrier stress, with a condition of V_G_S = V_D_S/2, was determined to induce threshold voltage, subthreshold swing and transconductance degradation for TFTs in thicker polysilicon films and the associated stress-induced increase in the active layer trap density was evaluated. However, this device degradation was drastically reduced for TFTs fabricated in ultra-thin films. Furthermore, the application of the same stress condition to TFTs oriented vertically ...

Science.gov (United States)

Timber Compartment Boundary This data set identifies the 90 timber compartment boundaries in a 200 square-mile study ... Kawishiwi Ranger Districts, Superior National ...

Energy Technology Data Exchange (ETDEWEB)

There are clearly identified scientific requirements for continuous profiling of atmospheric water vapor at the Department of Energy, Atmospheric Radiation Measurement program, Southern Great Plains CART (Cloud and Radiation Testbed) site in northern Oklahoma. Research conducted at several laboratories has demonstrated the suitability of Raman lidar for providing measurements that are an excellent match to those requirements. We have developed and installed a ruggedized Raman lidar system that resides permanently at the CART site, and that is computer automated to eliminate the requirements for operator interaction. In addition to the design goal of profiling water vapor through most of the troposphere during nighttime and through the boundary layer during daytime, the lidar provides quantitative characterizations of aerosols and clouds, including depolarization measurements for particle phase studies.

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Power loadings experienced by tokamak plasma-facing components during normal operation and during off-normal events are discussed. A model for power and particle flow in the tokamak boundary layer is presented and model predictions are compared to infrared measurements of component heating. The inclusion of the full three-dimensional geometry of the components and of the magnetic flux surface is very important in the modeling. Experimental measurements show that misalignment of component armour tile surfaces by only a millimeter can lead to significant localized heating. An application to the design of plasma-facing components for future machines is presented. Finally, thermal loads expected during tokamak disruptions are discussed. The primary problems are surface melting and vaporization due to localized intense heating during the disruption thermal quench and volumetric heating of the component armour and structure due to localised impact of ...

British Library Electronic Table of Contents (United Kingdom)

A non-similar boundary layer analysis is presented to study the flow, heat and mass transfer characteristics of non-Darcian mixed convection of a non-Newtonian fluid from a vertical isothermal plate embedded in a homogeneous porous medium with the effect of Soret and Dufour and in the presence of either surface injection or suction. The value of the mixed-convection parameter lies between 0 and 1. In addition, the power-law model is used for non-Newtonian fluids with exponent n1 for dilatant fluids. Furthermore, the coordinates and dependent variables are transformed to yield computationally efficient numerical solutions that are valid over the entire range of mixed convection, from the pure forced-convection limit to the pure free-conve...

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As lidar technology is able to provide fast data collection at a resolution of meters in an atmospheric volume, it is imperative to promote a modeling counterpart of the lidar capability. This paper describes an integrated capability based on data from a scanning water vapor lidar and a high-resolution hydrodynamic model (HIGRAD) equipped with a visualization routine (VIEWER) that simulates the lidar scanning. The purpose is to better understand the spatial and temporal representativeness of the lidar measurements and, in turn, to extend their utility in studying turbulence fields in the atmospheric boundary layer. Raman lidar water vapor data collected over the Pacific warm pool and the simulations with the HIGRAD code are used for identifying the underlying physics and potential aliasing effects of spatially resolved lidar measurements. This capability also helps improve the trade-off between spatial-temporal resolution and coverage of the ...

British Library Electronic Table of Contents (United Kingdom)

The effects of thermal radiation and viscous dissipation on magneto-hydrodynamic (MHD) unsteady free-convection flow over a semi-infinite vertical porous plate are analysed. The fluid considered is non-gray (absorption coefficient dependent on wave length). The Network Simulation Method is used to solve the boundary-layer equations based on the finite-difference formulation; only discretization of the spatial co-ordinates is necessary, while time remains as a real continuous variable. This method provides a solution for both transient and steady-state problems at the same time, and programming does not require manipulation of the sophisticated mathematical software that is inherent in other numerical methods. The velocity, temperature, local skin-friction and local Nusselt number are studi...

Energy Technology Data Exchange (ETDEWEB)

A study, based on a literature review was made to examine currently recommended meteorological measurement programs and diffusion prediction methods for nuclear power plants to determine their adequacy for plants located in coastal zones. Although procedures for handling the near-worst case (stable, light-wind situation) were judged adequately conservative, deficiencies in guidelines and procedures were found with respect to the following: failure to consider the role of coastal internal boundary layers; specifications for tower locations and instrument heights; methods of classifying atmospheric stability; methods of allowing credit for plume meander, and models specified for diffusion calculations. Recommendations were made for changes in the guidelines applicable to these topics. Areas in which additional research is needed were identified.

International Nuclear Information System (INIS)

By applying lock-in thermography imaging, light-beam-induced current imaging, electron-beam-induced current imaging at different stages of sample preparation, and infrared light microscopy in transmission mode, the physical nature of the dominant material-induced shunts in multicrystalline solar cells made from p-type silicon material has been investigated. It turns out that these shunts are due to silicon carbide (SiC) filaments, which grow preferentially in grain boundaries and cross the whole cell. These filaments are highly n-type doped, like the emitter layer on the surface of the cells. They are electrically connected both with the emitter and with the back contact, thereby producing internal shunts in the solar cell.

Science.gov (United States)

Double streamtube codes model the curved blade (Darrieus-type) vertical axis wind turbine (VAWT) as a double actuator fish arrangement (one half) and use conservation of momentum principles to determine the forces acting on the turbine blades and the turbine performance. Sandia National Laboratories developed a double multiple streamtube model for the VAWT which incorporates the effects of the incident wind boundary layer, nonuniform velocity between the upwind and downwind sections of the rotor, dynamic stall effects and local blade Reynolds number variations. The theory underlying this VAWT model is described, as well as the code capabilities. Code results are compared with experimental data from two VAWT's and with the results from another double multiple streamtube and a vortex filament code. The effects of neglecting dynamic stall and horizontal wind velocity distribution are also illustrated.

International Nuclear Information System (INIS)

This paper describes the study of particles' dispersion in an isotropic turbulent flow. The particle's motion and the turbulent flow characteristics are calculated independently. While the particles' displacement is computed by the author's code, the flow is simulated with a commercial code : PowerFLOW. The particles and the flow are coupled through the relative velocity component of the aerodynamic force. When the simulated flow is turbulent, a turbulence regeneration model is used in order to get the flow instantaneous velocity. Validation of the method is done by comparing the particles' dispersion obtained with experimental results from literature and with the results calculated by FLUENT. Good accordance is found between numerical studies and experimental results. However, comparison between results of PowerFLOW coupled to the author's code and results from FLUENT shows differences when the particle's path goes through the turbulent boundary ...

Energy Technology Data Exchange (ETDEWEB)

Using a quasi-static approach valid for Stefan numbers less than one, we derive approximate equations governing the movement of a phase change front for materials which generate internal heat. These models are applied for both constant surface temperature and constant surface heat flux boundary conditions, in cylindrical, spherical, plane wall and semi-infinite geometries. Exact solutions with the constant surface temperature condition are obtained for the steady-state solidification thickness using the cylinder, sphere, and plane wall geometries which show that the thickness depends on the inverse square root of the internal heat generation. Under constant surface heat flux conditions, closed form equations can be obtained for the three geometries. In the case of the semi-infinite wall, we show that for constant temperature and constant heat flux out of the wall conditions, the solidification layer grows then remelts. (orig.)

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The pitting behavior of Alloy 800 was investigated as a function of temperature and prefilming in high temperature water. The pitting behavior was characterized in terms of the pitting potential and the pit density. The pitting potential decreases with increasing temperature and chloride activity. Prefilming of test coupons over a time period between 100 and 5,000 hours in ammoniated water at 300 C has no apparent influence on the pitting potential at room temperature, 180 C and 300 C. However, the number of pits in prefilmed coupons is much higher than in coupons covered with an air passive layer. The effect of prefilming on pit nucleation was investigated in more detail with regard to a model and test methods developed by Bianchi and co-workers. Density of pits in prefilmed coupons is at least one order of magnitude higher than in air passive coupons. Maximum pit density was measured after a prefilming period of 1 00 hours. The effect is discussed in terms of ...

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This report presents the methodology and the results from the modelling of an open repository for spent nuclear fuel in Laxemar. Specifically, the present work analyses the hydrological effects of the planned repository during the construction and operational phases when it is open, i.e. air-filled, and hence may cause a disturbance of the hydrological conditions in the surroundings. The numerical modelling is based on the SDM-Site Laxemar MIKE SHE model. The modelling was divided into three steps. The first step was to update the SDM-Site Laxemar model with a new hydrogeological bedrock model. The other main updates were an increase of the depth of the MIKE SHE model domain, enhanced vertical computational resolution and that the drainage of the Aespoe Hard Rock Laboratory was included in the model. The resulting model was used to simulate undisturbed natural conditions. The next step was to describe the open repository conditions, using Laxemar layout D2, by implementing the access ...

Science.gov (United States)

... Progress: For a one-dimensional two-phase degenerate Stefan problem, it was proved that the boundary and the solutions up to the boundary are C ...

British Library Electronic Table of Contents (United Kingdom)

A boundary value problem for Laplace?s equation in a bounded two-dimensional domain filled with a piecewise homogeneous medium is considered. The boundary of the inhomogeneity is assumed to be unknown. The inverse problem of determining the inhomogeneity boundary and the solution of the equation given the solution and its normal derivative on the boundary of the domain is discussed. Numerical methods are proposed for solving the inverse problem, and the results of numerical experiments are presented.

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The process of carbonate dissolution at the sediment-water interface has two possible end-member boundary conditions. Either the carbonate particles dissolve mostly before they are incorporated into the sediment by bioturbation (interface dissolution), or the vertical mixing is rapid relative to their extermination rate (homogeneous dissolution). In this study, a detailed radiocarbon profile was determined in deep equatorial Pacific sediment that receives a high rate of carbonate supply. In addition, a box model of sediment mixing was used to simulate radiocarbon, carbonate content, and excess thorium profiles that result from either boundary process following a dissolution increase. Results from homogeneous dissolution imply a strong, very recent erosional event, while interface dissolution suggests that moderately increased dissolution began about 10,000 years ago. In order to achieve the observed mixed layer radiocarbon ...

CERN Document Server

We propose the exact boundary S matrix for breathers of the N=2 supersymmetric sine-Gordon model. We argue that this S matrix has three independent parameters, in agreement with a recently-proposed action. We also show, contrary to a previous claim, that the ``universal'' supersymmetric boundary S matrix commutes with two supersymmetry charges. General N=2 supersymmetric boundary integrable models are expected to have boundary S matrices with a similar structure.

British Library Electronic Table of Contents (United Kingdom)

We study a rapidly convergent modification of a two-sided method for the approximate integration of a boundary-value problem with parameters in boundary conditions for a system of quasilinear second-order differential equations.

CERN Document Server

Sediment transport over wave-induced ripples is a very complex phenomenon where available models fail to provide accurate predictions. For coastal engineering applications, the 1-DV advection-diffusion equation could be used with an additional parameter {\\alpha} related to the process of vortex shedding above ripples (Absi, 2010). The aim of this study is to provide simple practical analytical tools. An analytical eddy viscosity profile was validated by DNS data of turbulent channel flows (Absi et al., 2011). In this study, we will show that: (1) the period-averaged eddy viscosity in oscillatory boundary layers could be described by this simple analytical formulation; (2) The shape of the vertical profile is validated by period-averaged eddy viscosity of baseline (BSL) k-{\\omega} model (Suntoyo and Tanaka, 2009) for sinusoidal and asymmetric waves; (3) The vertical eddy viscosity profile depends on the wave non-linearity parameter and ...

Energy Technology Data Exchange (ETDEWEB)

Beside traditional applications of refractory metals, e.g. in high temperature furnace construction, lighting or glass industry, one of the most important molybdenum products nowadays are large plates which are frequently used as targets for the sputtering of molybdenum layers in thin-film transistor liquid crystal displays. For the hot rolling of the sintered pre-material, the control over the recovery and recrystallization behavior is of particular importance. Molybdenum tends to a very recovery controlled behavior during hot deformation, at which the dislocations arrange into subcell boundaries instantaneously. These pronounced recovery processes seem to consume a large amount of the stored deformation energy for the actual recrystallization. On the other hand, recovery provides the future recrystallization nuclei. For a comprehensive characterization of these microstructural processes, electron microscopy appears to be the most proper ...

Energy Technology Data Exchange (ETDEWEB)

An experimental campaign, aiming to investigate the perturbation effects induced by fixed obstacles on turbulence measurements in airflows at the air-sea interface, was carried out at the marine platform of the Italian Navy, located in the harbour of La Spezia (North Ligurian Sea, Italy) on 28., 29., and 30. June 1994. This study was prompted by the ever-growing interest in more reliable estimates of energy, mass, and momentum exchanges between water surfaces and atmosphere, whose measurements are severely limited by the geometrical constraints of floating or fixed platforms where they are installed. Two types of meteorological instruments have been used: fast response (20 and 21 Hz) ultrasonic anemometers and fluxmeters to measure turbulent momentum, sensible, and latent heat fluxes and slow-response sensors (less than 4 Hz and sampled at a rate of 10{sup 2} Hz) to measure average wind and temperature vertical profiles in the perturbed boundary ...

International Nuclear Information System (INIS)

Measurements of ion-induced electron emission have been performed with helium and argon ions with energies between 300 and 900 eV on W, W with 10% Ti, Al, Al with 1% Cu, Al with 1% Si, Si, and Be. This article describes many of the important surface characteristics that influence the ion-induced electron emission. For low-energy ions, the substrate material was found to be less important as the velocity of the incident ion decreased. In the case of incident Ar"+ the substrate material had a negligible effect on the emission for this energy range. The presence of an adsorbed layer enhanced emission in all cases. Heating the substrates resulted in oxidation of the surfaces and a subsequent increase in emission. The electron emission from aluminum samples with smaller grain sizes was higher than samples of identical composition with larger grains. This effect is due to the greater number of adsorption sites resulting from the higher grain boundary ...

Energy Technology Data Exchange (ETDEWEB)

Double streamtube codes model the curved blade (Darrieus-type) vertical-axis wind turbine (VAWT) as a double actuator-disk arrangement (one disk for the upwind half of the rotor and a second disk for the downwind half) and use conservation of momentum principles to determine the forces acting on the turbine blades and the turbine performance. These models differentiate between the upwind and downwind sections of the rotor and are capable of determining blade loading more accurately than the widely-used single-actuator-disk streamtube models. Additional accuracy may be obtained by representing the turbine as a collection of several streamtubes, each of which is modeled as a double actuator disk. This is referred to as the double-multiple-streamtube model. Sandia National Laboratories has developed a double-multiple streamtube model for the VAWT which incorporates the effects of the incident wind boundary layer, nonuniform velocity between the ...

Energy Technology Data Exchange (ETDEWEB)

Heat and momentum transport in self-sustained oscillatory viscous flows is investigated by direct numerical simulation using the spectral element method. Above a critical Reynolds number, these flows bifurcate to a time-periodic, self-sustained oscillatory state. Traveling waves are observed, even at moderately low Reynolds numbers, inducing self-sustained oscillations that result in very well-mixed flows, which, in turn, lead to convective heat transfer augmentation. These oscillatory states are investigated and correlations between the time- and space-averaged Nusselt and Reynolds numbers are obtained. The transport phenomena of heat and momentum due to the oscillatory components of the flow are analyzed by looking at the phase portraits of velocity and temperature, investigating the behavior of the terms involving their fluctuations, as well as considering the correlation coefficients between the fluctuating components. Results are presented for laminar and transitional ...

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The effect of transverse magnetic field parameter (Hartmann number, Ha) Reynolds number (Re) and Prandtl number (Pr) on the mixed convection flow past a semi-infinite vertical porous plate in a non-Darcian porous medium with variable viscosity and porosity, viscous dissipation and fluid-solid thermal conductivity ratio in the presence of plate transpiration (lateral mass flux) is investigated theoretically and numerically using Keller`s implicit finite difference scheme. It is shown that the Harmann number acts as a retarding force and increases the momentum boundary layer thickness, analogous to the flow against a positive pressure gradient, simultaneously decreasing local skin friction (shear stress). The heat transfer rate is however enhanced by the magnetic field (for positive values of the Eckert number) since the fluid is heated and temperature gradients become reduced between the fluid and the plate, with important potential applications ...

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In the present study, the type and densities of defects in AlN crystals grown on 6H-SiC seeds by the sublimation-recombination method were assessed. The positions of the defects in AlN were first identified by defect selective etching (DSE) in molten NaOH-KOH at 400 C for 2 minutes. Etching produced pits of three different sizes: 1.77 m, 2.35 m , and 2.86 m. The etch pits were either aligned together forming a sub-grain boundary or randomly distributed. The smaller etch pits were either isolated or associated with larger etch pits. After preparing crosssections of the pits by the focused ion beam (FIB) technique, transmission electron microscopy (TEM) was performed to determine which dislocation type (edge, mixed or screw) produced a specific etch pit sizes. Preliminary TEM bright field and dark field study using different zone axes and diffraction vectors indicates an edge dislocation with a Burgers vector 1/3[1120] is associated with the smallest etch pit size.

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A range of <110> symmetric tilt grain boundaries (GBs) are investigated in several fcc metals with simulations and high resolution electron microscopy. Boundaries with tilt angles between 50.5{degree} and 109.5{degree} dissociate into two boundaries 0.6 to 1.1 nm apart. The dissociation takes place by the emission of stacking faults from one boundary that are terminated by Shockley partials at a second boundary. This is a general mode of GB relaxation for low stacking fault energy metals. The reasons for the occurrence of this relaxation mode are discussed using the theory of GB dislocations.

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Three studies of electrochemical current distribution have been performed using potential-theory models and the boundary-element method (BEM). (1) The steady-state behavior of cells with nonuniform current density over a passivating anode is investigated. Current distributions calculated for a test cell, using the measured kinetic behavior of nickel in acid-nickel-sulfate solution, are compared to estimates from earlier models. Although current-density profiles determined by weight loss on a segmented rotating cylinder agreed satisfactorily with model calculations, the measured length of the passive zone exceeds the theoretical value. The model's applicability to anodic protection is demonstrated for a stainless-steel sulfuric-acid holding tank. (2) A model is established to describe the effects of attached bubbles on the potential drop at gas-evolving electrodes including: (1) ohmic obstruction within the electrolyte; (2) area masking on the electrode ...

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Computation of effective flow properties of fluids in porous media based on three dimensional (3D) pore structure information has become more successful in the last few years, due to both improvements in the input data and the network models. Computed X-ray microtomography has been successful in 3D pore imaging at micron scale, which is adequate for many sandstones. For other rocks of economic interest, such as chalk and diatomite, submicron resolution is needed in order to resolve the 3D-pore structure. To achieve submicron resolution, a new method of sample serial sectioning and imaging using Focused Ion Beam (FIB) technology has been developed and 3D pore images of the pore system for diatomite and chalk have been obtained. FIB was used in the milling of layers as wide as 50 micrometers and as thin as 100 nanometers by sputtering of atoms from the sample surface. The focused ion beam, consisting of gallium ions (Ga+) accelerated by potentials of up to 30 kV and ...

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The role played by planetary boundary layer (PBL) in the development and evolution of a severe convective storm is studied by means of meso-scale modeling and surface and upper air observations. The severe convective precipitation event that occurred on 14 September 1999 in the northeast of the Iberian Peninsula was simulated by means of the mesoscale model MM5 (version 3) using three different PBL schemes. The numerical results show a large impact of the PBL schemes on the precipitation fields associated to the convective storm. The schemes are based on different physical assumptions: the nonlocal first order medium-range forecast (MRF) and blackadar (BLA) scheme and the local, one-and-a-half order ETA scheme. Surface and radar observations are used to validate the model results. The comparison focuses on three aspects: the evolution, the spatial distribution and the 24-h accumulated precipitation. The comparison with rain gauge observations ...

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This article considers the fundamentals of what happens in asolid when it is impacted with a medium energy gallium ion. The study ofthe ion/sample interaction at the nanometer scale is applicable to mostfocused ion beam (FIB) based work even if the FIB/sample interaction isonly a step in the process, e.g., micromachining or microelectronicdevice processing. Whereas the objective in other articles in this issueis to use the FIB tool to characterize a material or to machine a deviceor transmission electron microscopy (TEM) sample, the goal of the FIB inthis article is to have the FIB/sample interaction itself become theproduct. To that end, the FIB/sample interaction is considered in threecategories according to geometry: below, at, and above the surface.First, the FIB ions can penetrate the top atom layer(s) and interactbelow the surface. Ion implantation and ion damage on flat surfaces havebeen comprehensively examined; however, FIB applications require thefurther ...

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Two mechanical design requirements are defined for the SSC Collider beam tube. First, the vacuum requirement (luminosity lifetime = 150 hrs). It requires the design of a pressure boundary within the cold mass vessel to provide a vacuum tunnel for the proton beam and to minimize the synchrotron radiation gas desorbtion with a suitable material. The Collider beam tube design is under an intensive activity to search for a material that will meet the luminosity requirement without a distributed pump or liner. Second is the tube wall's resistivity requirement ([sigma]*t = 2E5 [Omega][sup [minus]1]). For a 4.2 K beam tube the Cu thickness is 100 [mu]m (RRR=30,6.7 T, [sigma]=2E9[Omega][sup [minus]1]m[sup [minus]1]). The copper yield strength is relatively low in comparison to steel and, therefore, the design of the steel layer is governed by the copper layer yield stress limit. A beam tube subjected to eddy current load ...

KoreaScience (Korea)

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Science.gov (United States)

We study a two-level atom in interaction with a real massless scalar quantum field in a spacetime with a reflecting boundary. The presence of the boundary modifies the quantum fluctuations of the scalar field, which in turn modifies the radiative properties of atoms. We calculate the rate of change of the mean atomic energy of the atom for both inertial motion and uniform acceleration. It is found that the modifications induced by the presence of a boundary make the spontaneous radiation rate of an excited inertial atom oscillate near the boundary and this oscillatory behavior may offer a possible opportunity for experimental tests for geometrical (boundary) effects in flat spacetime. While for accelerated atoms, the transitions from ground states to excited states are found to be possible even in a vacuum due to changes in the vacuum fluctuations induced by both the presence of the ...

Energy Technology Data Exchange (ETDEWEB)

Evaluation of grain boundary composition and structure in superplastically deformed AA5083-based alloys (Al-4.5Mg-1.6Mn-0.2Zr) was carried out in a field-emission gun transmission electron microscope (FEG-TEM). During superplastic deformation at high homologous temperatures materials undergo extensive grain boundary sliding (GBS) which creates a flow of defects in the near-boundary region. Recent literature has shown that the grain-boundary composition in Al-Mg alloys is not necessarily the same as the matrix, and that these differences can have an effect on GBS.

Energy Technology Data Exchange (ETDEWEB)

Using a radioactive tracer method the bulk and grain boundary diffusion of {sup 59}Fe was determined in industrial alloy 800 and melts of alloy 800 with additional P and S in the temperature range 800 to 1000 C. The use of the approximation of Suzuoka was confirmed by autoradiographs. In alloy 800 H the activation energy of grain boundary diffusion of {sup 59}Fe is (209 {+-} 17)kJ/mol. Dissolved elements especially P increase the activation energy of the grain boundary diffusion of Fe by their segregation to the grain boundaries. In addition the influence of the grain boundary diffusion on the growth of creep cavities was investigated in the same materials, and the chemical composition of the creep cavities and grain boundaries were analysed by Auger electron spectroscopy (AES). For alloy 800 + 0.088 wt-%P an enrichment of about 14 at-%P was observed at the ...

Energy Technology Data Exchange (ETDEWEB)

TiO{sub 2} is a vital material in several technologies including, photocatalysis, gas sensing, biomaterials and optical coatings. Among the several crystal structures of this oxide, rutile has the highest density and microhardness, the highest index of refraction and the highest temperature stability. The processing of dense polycrystalline materials often includes the addition of a liquid-forming phase at higher temperatures. This technique is known as liquid-phase sintering and has been studied extensively. Rutile boundaries containing an amorphous phase have been used to study boundary migration and grain-boundary grooving. Visible-light (VLM), scanning electron (SEM) and transmission electron microscopy (TEM) in addition to electron-backscatter diffraction (EBSD) and a focused-ion beam (FIB) tool were used to characterize boundary migration in rutile. EBSD analysis was carried out on a Philips XL30 ...

Science.gov (United States)

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British Library Electronic Table of Contents (United Kingdom)

Layered carbon fiber mats have been prepared by layer-by-layer (LBL) electrospinning of polyacrylonitrile onto thin natural cellulose paper and subsequent carbonization. The layered carbon fiber mat has been proved to be a promising microbial fuel cell anode for high density layered biofilm propagation and high bioelectrocatalytic anodic current density.

UK PubMed Central (United Kingdom)

Somite boundary formation is crucial for segmentation of vertebrate somites and vertebrae and skeletal muscle morphogenesis. Previously, we developed a Tol2 transposon-mediated...Full Text Available

British Library Electronic Table of Contents (United Kingdom)

On the basis of the resolvent of a simple differential operator, a method for finding approximations to continuous functions is constructed. In this method, both the approximated function and its approximations satisfy the given integral boundary condition.

Energy Technology Data Exchange (ETDEWEB)

Formulation is introduced for discretizing a boundary integral equation into an indirect boundary element method for the solution of 3-dimensional topographic problems. Yokoi and Takenaka propose an analytical solution-capable reference solution (solution for the half space elastic body with flat free surface) to problems of topographic response to seismic motion in a 2-dimensional in-plane field. That is to say, they propose a boundary integral equation capable of effectively suppressing the non-physical waves that emerge in the result of computation in the wake of the truncation of the discretized ground surface making use of the wave field in a semi-infinite elastic body with flat free surface. They apply the proposed boundary integral equation discretized into the indirect boundary element method to solve some examples, and succeed in proving its validity. In this report, the ...

Energy Technology Data Exchange (ETDEWEB)

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Energy Technology Data Exchange (ETDEWEB)

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British Library Electronic Table of Contents (United Kingdom)

Epitaxial thin films of nanotwinned face-centered cubic metals such as Cu possess an unprecedented combination of high hardness and high electrical conductivity due to the unique structure of nanometer-spaced coherent twin boundaries. Recent studies of in-situ nanoindentation in a transmission electron microscope have provided new insights on the deformation behavior of nanotwins that are reviewed here. In particular, two unit processes are highlighted: first, stress-induced migration of ?3 {112} incoherent twin boundary that leads to de-twinning of nanotwins; second, twinning dislocation can be multiplied at ?3 {111} coherent twin boundary.

Science.gov (United States)

Molten zone recrystallized as well as sheet grown polycrystalline silicon has shown a minimum in the temperature dependence of the Hall mobility. In order to explain this experimental finding a new model is proposed, which is based on negatively charged grain boundaries for the p-type silicon material under study. This results in a potential well at the grain boundaries instead of the more generally observed potential barrier. A key feature in the model is that the space charge density at the grain boundary depends on the Fermi level position and therefore on temperature. In addition, the change in the measured Hall mobility before and after hydrogen passivation of the grain boundaries is discussed.

Energy Technology Data Exchange (ETDEWEB)

In our previous theoretical analyses, solubility-limited mass transfer from waste solids applies if a species is at a constant elemental concentration in liquid at the waste surface. For an element with isotopes that decay appreciably during the time of interest, a solubility boundary condition results in a time-dependent boundary concentration of each isotope. Here we present mass-transfer equations that include the effects of isotopic decay boundary conditions. 9 refs., 1 fig.

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Solid state effects are taken into account in an internal conversion coefficients computation by using Wigner-Seitz boundary conditions. Both the bound and free electron wave functions are calculated from an atomic Dirac-Hartree-Fock-Slater self consistent potential. These internal conversion coefficients are compared with those obtained from the usual free atom boundary conditions.

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Cementitious materials provide an ideal geochemical environment (e.g., high pH pore fluids and large surface areas for sorption) for immobilizing nuclear waste. The inclusion of reducing agents, such as blast furnace slag (BFS) can immobilize radionuclides by forming of solid sulfide phases. Thermodynamic calculations using the MINTEQ geochemical computer code indicate the elemental sulfur present in BPS reacts with the highly mobile pertechnetate anion (TcO{sub 4}{sup -}) anion to form an insoluble technetium sulfide phase (Tc{sub 2}S{sub 7(s)}). Initially, the waste form very effectively immobilizes technetium. However, as oxygen diffuses into the waste form, an outer zone of oxidized concrete and a shrinking core of reduced intact concrete develops. Oxidation of sulfur in the outer zone results in increased technetium concentrations in the pore fluid because Tc{sub 2}S{sub 7(a)} oxidizes to the mobile TcO{sub 4}{sup -} anion. The TcO{sub 4}{sup -} anion can then diffuse from the ...

Energy Technology Data Exchange (ETDEWEB)

The corrosion and passivation behaviour of bulk polycrystalline martensite Ni{sub 50}Mn{sub 30}Ga{sub 20} and austenite Ni{sub 48}Mn{sub 30}Ga{sub 22} alloys was compared in electrolytes with different pH values. Linear anodic and cyclic potentiodynamic polarisation methods and anodic current transient measurements have been conducted for the alloys and their constituents to analyze free corrosion, anodic dissolution and passive layer formation processes. Electrochemically treated alloy surfaces were characterized with scanning electron microscopy (SEM) and angle-resolved x-ray photoelectron spectroscopy (XPS). The electrochemical response of both alloys is in principal similar and is dominated by the Ni oxidation. In acidic solutions (pH 0.5 and 5) a slightly higher reactivity is detectable for the martensitic alloy which is mainly attributed to enhanced dissolution processes at the multiple twin boundaries. In weakly acidic to strongly ...

International Nuclear Information System (INIS)

As an unconventional surface alloying process, ion implantation has been utilized to improve the active-passive behavior and the pitting resistance of martensitic M50 engineering alloy. In a field simulation study, Cr-implantation only at 150 kev to a fluence of 2 x 10"1"7 ions/cm"2 prevented pitting. The best pitting resistance of the steel was obtained with multiple implantations of Cr and Mo. The intermixing effect of high fluence P-implantation into 304 stainless produced an amorphous surface alloy. The removal of the grain boundaries and the uniformity of the resulting structure had a great influence on corrosion properties. REED analysis indicated that the anodic passive films formed on P-implanted 304 stainless steel at 250 mV (SCE) in 0.5M H_2SO_4 was amorphous. Phosphorus and boron were implanted into 316 stainless steel to study the passivity of 316 stainless. Electrochemical experiments were carried out to evaluate the effects of phosphorus and boron on ...

Energy Technology Data Exchange (ETDEWEB)

Positron Emission Tomography (PET) was used to analyze in vivo antagonist binding to human myocardial muscarinic cholinergic receptor. The methiodide salt of the muscarinic antagonist, quinuclidinyl benzilate (MQNB), was labeled with the positron emitter, Carbon-11, and injected intravenously to 8 normal subjects. /sup 11/C-MQNB concentration was determined in vivo in the ventricular septum from 40 cross-sectional images acquired at the same transverse level over a period of 70 minutes. In 4 subjects, various amounts of unlabeled atropine were rapidly injected at 20 minutes to study whether atropine competitively inhibited MQNB. The kinetics of binding of /sup 11/C-MQNB were not the same in vivo and in vitro. The apparent dissociation rate of /sup 11/C-MQNB in vivo was much slower (by 1 to 2 orders of magnitude) than that observed in vitro with /sup 3/H-QNB. After atropine injection, /sup 11/C-MQNB dissociated from its binding sites at a rate that apparently depended on the amount of ...

Energy Technology Data Exchange (ETDEWEB)

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

Energy Technology Data Exchange (ETDEWEB)

The Electrohydrodynamic (EHD) is an active heat transfer augmentation technique which utilizes the effect of secondary motions generated through the application of an electrostatic potential to a dielectric fluid. Net result is better momentum and heat transfer between the fluid and the heat transfer wall through destabilization of the thermal boundary layer and better mixing of the fluid adjacent to the heat transfer surface. EHD enhancement of refrigerant/refrigerant oil mixtures heat transfer using the Electrohydrodynamic (EHD) technique is the subject of a three-year experimental investigation in a project funded by the US Department of Energy, effective June 1, 1993. For the interim period between November 1992 and June 1993 when the DOE funds became available, the Air-Conditioning and Refrigeration Technology Institute (ARTI) provided partial funding for our EHD research program with the aim of accomplishing three major tasks: (1) conduct ...

Energy Technology Data Exchange (ETDEWEB)

The Early Palaeozoic Warburton Basin underlies the gas and oil producing Cooper and Eromanga Basins. Postdepositional tectonism created high potential fracture porosities, complicating the stratigraphy and making reservoir prediction difficult. Sequence stratigraphy integrating core, cuttings, well-log, seismic and biostratigraphic data has recognized a carbonate-dominated to mixed carbonate/siliciclastic supersequence comprising several depositional sequences. Biostratigraphy based on trilobites and conodonts ensures reliable well and seismic correlations across structurally complex areas. Lithofacies interpretation indicates sedimentary environments ranging from carbonate inner shelf, peritidal, shelf edge, deep outer shelf and slope to basin. Log facies show gradually upward shallowing trends or abrupt changes indicating possible sequence boundaries. With essential depositional models and sequence analysis from well data, seismic facies suggest general ...

CERN Document Server

The Eady problem of baroclinic instability as applicable to quasi-geostrophic oceanic flows with zero internal PV gradients is revisited by introducing a mild slope and Ekman pumping on the lower boundary. The solution behaviour is determined by the isopycnal slope relative to either the bottom slope or the ratio of Ekman depth to horizontal wavenumber. Attention is paid to the physical interpretation of the growing, decaying and stable disturbances, with emphasis on the intimate connection between the quasigeostrophic edge waves and Eady waves, and the role of the isopycnal slope for the stability properties as opposed to the bottom density gradient. The disturbance structure is found to be strongly influenced by the boundary conditions. For a sloping bottom boundary, the growth rate is enhanced for the most unstable waves if the isopycnals tilt in the same direction as the bottom, but in general non-standard ...

Energy Technology Data Exchange (ETDEWEB)

The concepts of general flow and thermal boundary conditions are introduced to treat the interaction between indoor and outdoor thermal environments in computational fluid dynamics (CFD) simulations. The results from a multi-zone model are used to supply the general flow boundary conditions. The energy balance equation at wall-air interfaces is used to supply the general thermal boundary conditions. An example calculation in a 13-room building shows that infiltration influences indoor air flow patterns considerably. The air flow in a room ventilated by displacement is measured and simulated. Two surface coatings are considered, i.e. black walls and aluminum walls. Implementation of these two boundary conditions is essential in predicting air flow patterns, air quality, and thermal comfort in a real building. (author)

Energy Technology Data Exchange (ETDEWEB)

To prove that two-layer, TBP-nitric acid mixtures can be safely stored in the canyon evaporators, it must be demonstrated that a runaway reaction between TBP and nitric acid will not occur. Previous bench-scale experiments showed that, at typical evaporator temperatures, this reaction is endothermic and therefore cannot run away, due to the loss of heat from evaporation of water in the organic layer. However, the reaction would be exothermic and could run away if the small amount of water in the organic layer evaporates before the nitric acid in this layer is consumed by the reaction. Provided that there is enough water in the aqueous layer, this would occur if the organic layer is sufficiently thick so that the rate of loss of water by evaporation exceeds the rate of replenishment due to mixing with the aqueous layer. This report presents ...

Energy Technology Data Exchange (ETDEWEB)

This thesis deals with the evaluation of Solar Grade Silicon (SoG-Si) purified by different techniques, and also the fabrication and characterization of high efficiency and advanced bifacial solar cells. In the beginning of Chapter 1, various SoG-Si production methods relevant for this work are qualitatively described. The three feedstock materials used in this work are from the Fluidized Bed Reactor (FBR) process, metallurgical feedstock-I and feedstock-II process. In metallurgical feedstock-I, the lifetime of the minority charge carriers in multicrystalline silicon (mc-Si) samples at the grain boundaries are found to be higher than the grains themselves possibly due to lower resistivities in the grain boundaries. The efficiency of the best solar cell obtained using the mc-Si metallurgical feedstock-I is 16.1%. It has been identified that the fast light induced degradation, whose magnitude is lower than that of a reference cell suggests the ...

Energy Technology Data Exchange (ETDEWEB)

This work deals with a rational vision of stratospheric ozone including the threats on ozone layer, the verifications and the fears. After a recalling on the ozone layer history, the authors treats the question of the ultraviolets particularly the beneficial effects. Then an explanation of the ozone layer decrease is given. (O.L.). 29 refs., 6 figs.

Energy Technology Data Exchange (ETDEWEB)

The variations of thickness of the ozone layer over Denmark in the 1978-1994 period based on monthly figures are presented. (CLS)

International Nuclear Information System (INIS)

Silicon layered structures containing porous silicon modified with various thermal treatments and epitaxial layers deposited on porous layers were studied with a number of complementary X-ray diffraction methods using synchrotron source. The methods of characterization included recording of rocking curves for reflections with various asymmetry as well as projection, section and micro-Laue topography. It was found that oxidizing and sintering of porous silicon seriously modified the strains in the porous layer and in some cases even inverting the sense of strain with respect to that in initially formed porous layer. Consequently the deposited epitaxial layer usually was not laterally coherent with the substrate. Some of investigated layers were not stable in time and after few months period exhibited significant lost of coherence of porous ...

Energy Technology Data Exchange (ETDEWEB)

The influence of the velocity profile at the inlet boundary on the simulation of air velocity distribution inside an electrostatic precipitator is presented in this study. Measurements and simulations were performed in a duct and an electrostatic precipitator (ESP). A four-hole cobra probe was used for the measurement of velocity distribution. The flow simulation was performed by using the computational fluid dynamics (CFD) code FLUENT. Numerical calculations for the air flow were carried out by solving the Reynolds-averaged Navier-Stokes equations coupled with the realizable k-{epsilon} turbulence model equations. Simulations were performed with two different velocity profiles at the inlet boundary - one with a uniform (ideal) velocity profile and the other with a non-uniform (real) velocity profile to demonstrate the effect of velocity inlet boundary condition on the flow simulation results inside an ESP. The real ...

International Nuclear Information System (INIS)

The crystallography of #alpha#(hcp) precipitates formed on the #beta#(bcc) matrix grain boundaries has been studied with transmission electron microscopy (TEM) in a Ti-15V-3Cr-3Sn-3Al alloy. The #alpha# precipitates have a near-Burgers orientation relationship with respect to at least one of the adjacent #beta# grains. Among the possible 12 variants in this orientation relationship, the variant that [11 bar 20]_#alpha# is parallel to the _#beta# closest to the grain boundary plane tends to be preferred by the #alpha# precipitates. Additionally, further variant selections are made so as to minimize the deviation of orientation relationship with respect to the ''opposite'' #beta# grain from the Burgers one. Such rules in variant selection often result in the formation of precipitates with a single variant at a planar grain boundary. Prior small deformation of #beta# matrix changes the variant of #alpha# precipitates at the ...

Science.gov (United States)

Some bacteria move inside cells by recruiting the actin filaments of the host cells. The filaments are polymerized at the back surface of the bacteria, and they move away, forming a "comet" tail behind the bacterium, which consists of gel network. We develop a one-dimensional mathematical model of the gel based on partial differential equations which involve the number of filaments, the density and velocity of the gel, and the pressure. The two end-points of the gel form two free boundaries. The resulting free boundary problem is rather non-standard. We prove local existence and uniqueness.

CERN Document Server

We investigate stability properties of indirectly damped systems of evolution equations in Hilbert spaces, under new compatibility assumptions. We prove polynomial decay for the energy of solutions and optimize our results by interpolation techniques, obtaining a full range of power-like decay rates. In particular, we give explicit estimates with respect to the initial data. We discuss several applications to hyperbolic systems with {\\em hybrid} boundary conditions, including the coupling of two wave equations subject to Dirichlet and Robin type boundary conditions, respectively.

Science.gov (United States)

Observational evidence is presented for the nucleation of condensation nuclei (CN) in the clear air adjacent to an isolated, marine, cumulus cloud. Two separate regions of particle nucleation are identified: one located above the cloud top, and the second located downwind of the cloud near the level of the anvil outflow. The regions of high CN concentrations were located in extremely clean marine air, with unactivated aerosol surface area (excluding the nucleation mode) less than 2 sq micrometers/cu cm, air temperature -31 C, and higher relative humidities than the undisturbed environment. Vertical profile measurements downwind of the cloud showed that CN concentrations at the level of the anvil outflow (4.9 km) were 8 times greater than at any other level between the surface and 5.3 km. A conceptual model is formulated in which aerosol particles, sulfur dioxide (SO2), sulfuric acid vapor (H2SO4), dimethyl sulfide (DMS), and ozone (O3) from the boundary ...

Energy Technology Data Exchange (ETDEWEB)

Dominating factors in plasma nitriding and plasma condition that makes nitriding possible in plasma nitriding process of metals having hard oxide film were studied. In case of stainless steel, oxide film sputtering was easier comparing to nitriding layer. Three phenomena such as sputtering of oxide layer, formation of nitriding layer and sputtering of nitriding layer occurred simultaneously. Nitriding was achieved when the formation of nitriding layer reached the peak comparing to the removal of nitriding layer after the removal of oxide layer. Situations of metallic surface of stainless steel in surface nitriding were divided into four categories and they were, situation where oxide layer remained as it is, situation where nitriding layer was formed although oxide layer remained ...

UK PubMed Central (United Kingdom)

Ultraconserved elements (UCEs) are sequences that are identical between reference genomes of distantly related species. As they are under negative selection and enriched near or in specific classes...Full Text Available

Energy Technology Data Exchange (ETDEWEB)

We consider Rashba spin-orbit effects on spin transport driven by an electric field in semiconductor quantum wells. We derive spin diffusion equations that are valid when the mean free path and the Rashba spin-orbit interaction vary on length scales larger than the mean free path in the weak spin-orbit coupling limit. From these general diffusion equations, we derive boundary conditions between regions of different spin-orbit couplings. We show that spin injection is feasible when the electric field is perpendicular to the boundary between two regions. When the electric field is parallel to the boundary, spin injection only occurs when the mean free path changes within the boundary, in agreement with the recent work by Tserkovnyak et al (Preprint cond-mat/0610190)

Science.gov (United States)

... Finally, the one dimensional, one phase Stefan problem is well known as a model for the melting of ice (see, eg, [5]). There are many approaches to ...

Science.gov (United States)

We set a symmetric boundary at x=200 and a conducting wall at z=150. The domain of 0200. 0150 is resolved by 60004500 grid cells. Harris sheet ...

Energy Technology Data Exchange (ETDEWEB)

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

International Nuclear Information System (INIS)

The structure of the layers formed on a silver electrode by the adsorption of pyridine, Cl"-, CN"- and SO_4"2"- is discussed. A comparison of the amount of the species adsorbed with their Raman spectra shows that there is no simple relation between the species concentration and the enhancement of the Raman intensity. Furthermore, the inhomogeneity of the layers is shown by Raman microscopy observations. These results lead the authors to propose the formation of a new species stabilized in the colloidal silver layer. The Raman enhancement could be explained by the existence of a resonance effect. (Auth.).

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Governments around the world will soon make decisions on policies that could determine the fate of the ozone layer-the Earth's shield from harmful ultraviolet radiation. The Vienna Convention for the Protection of the Ozone Layer, signed on March 22, 1985, created a framework for scientific cooperation and information exchange that will form the basis for a protocol for controlling substances thought to threaten the ozone layer. As of mid-1987, 29 countries had signed the Convention, including the major producers and users of chlorofluorocarbons (CFCs), the most important of suspect chemicals.

KoreaScience (Korea)

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KoreaScience (Korea)

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KoreaScience (Korea)

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International Nuclear Information System (INIS)

Planar channeling effects are studied in such well-oriented polycrystalline layers as NiSi_2 and Pb_2Si layers formed on single crystalline Si. Crystalline perfection of such layers is discussed by using the energy- and angular dependences of the axial and planar channeling yields. It has been shown that, in suitable conditions, the energy dependence of the planar yield is more sensitive to the spread of crystallite orientations in polycrystals than that of the axial one. (Auth.).

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The effects of reservoir layering and gravity segregation on nonisothermal injection and falloff tests are investigated. Results show that layering does not affect injection or falloff data if all the layers are permeable and accept fluids from the wellbore. In such cases, the average permeability, skin factor, and distance to the thermal front can be calculated using the techniques developed for homogeneous reservoirs. Special considerations have to be taken for cases where several layers are impermeable or are permeable but do not accept fluids of the well face. In the first case (impermeable layers), knowledge of the total thickness of the permeable layers is required for the existing techniques to be applied successfully. In the second case, the existing techniques cannot be applied, but characteristic responses from injection and falloff test are seen; ...

International Nuclear Information System (INIS)

Reflection coefficients of electromagnetic waves in a nonuniform plasma layer with electrons, positive ions and negative ions, covering a metal surface are investigated by using the finite-difference-time-domain method. It is shown that the reflection coefficients are influenced greatly by the density gradient on the layer edge, layer thickness and electron proportion, i.e., the effect of the negative ions. It is also found that low reflection or high attenuation can be reached by properly choosing high electron proportion, thick plasma layer, and smooth density gradient in the low frequency regime, but sharp density gradient in the high frequency regime. (authors)

Science.gov (United States)

A flutter-motion equation is presently derived for a 2D composite sandwich panel considering the total lateral displacement of the plate as the sum of the displacement due to bending of the plate, and that which is due to shear deformation at the core. The effects of core thickness and stacking sequence of the faces on the flutter boundary of the plate are discussed; it is shown that the sandwich panel greatly improves the flutter boundary over that of a composite laminate panel, provided it has sufficient core thickness.

British Library Electronic Table of Contents (United Kingdom)

The steady-state advective flow in a long horizontal rectangular channel with rigid adiabatic boundaries in the presence of a uniform longitudinal pressure gradient is investigated. The stability of this flow with respect to perturbations of various types is studied. The dependence of the critical Rayleigh number on the Prandtl number is found for various aspect ratios.

International Nuclear Information System (INIS)

Nanocrystalline materials can exhibit properties which are considerably different from their coarse-grained counterparts, making them unique for basic or applied research and also very promising for potential applications. The topics which are addressed in the present paper are magnetic properties and magnetic correlations on the nanometer scale, mechanical properties, in particular the influence of grain boundaries on the elastic and plastic behaviour, and vibration models of grain boundary atoms in nanostructured materials. (author)

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The question about expanding the boundaries of the open pit mining method is examined. The use of methods which consider the advantages of open and underground mining operations with their joint use in horizontal and evenly dipping deposits will make it possible to objectively select the mining method, to expand the range of use of open pit mining operations in the deposits of the Far North and provide an improvement in the technical and economic indicators of mineral extraction.

Scientific Electronic Library Online (English)

Abstract in english This paper presents an HP-Adaptive Procedure with Hierarchical formulation for the Boundary Element Method in 2-D Elasticity problems. Firstly, H, P and HP formulations are defined. Then, the hierarchical concept, which allows a substantial reduction in the dimension of equation system, is introduced. The error estimator used is based on the residual computation over each node inside an element. Finally, the HP strategy is defined and applied to two examples.

Energy Technology Data Exchange (ETDEWEB)

Alloy 800 is an austenitic Fe-Ni-Cr steel containing relatively minor but important amounts of carbon, aluminium and titanium. Special grades of alloy 800 known as 800H, 800HT and 800LC differ in the concentrations of these elements. In addition to these industrial specifications, further melts were prepared containing phosphorous or sulphur. Using a radioactive tracer method the bulk and grain-boundary diffusion of {sup 59}Fe was investigated in these alloys in the temperature range 800 to 1000 C. For evaluation of the diffusion profiles the approximation of Suzuoka was used, which considers the depletion of the tracer on the surface. By autoradiography it was confirmed that such depletion occurs. In alloy 800H the activation energy of grain-boundary diffusion of {sup 59}Fe was found to be (209{+-}17) kJ/mol; dissolved elements, especially phosphorous, increase the activation energy. The same materials - aged at 800 C for 100 h - were used for ...

International Nuclear Information System (INIS)

High quality graphene sheets are synthesized through efficient oxidation process followed by rapid thermal expansion and reduction by H2. The number of graphene layers is controlled by tuning the oxidation degree of GOs. The higher the oxidation degree of GOs is getting, the fewer the numbers of graphene layers can be obtained. The material is characterized by elemental analysis, thermo-gravimetric analysis, scanning electron microscopy, atomic force microscopy, transmission electron microscopy and Fourier transform infrared spectroscopies. The obtained graphene sheets with single, triple and quintuplicate layers as anode materials exhibit a high reversible capacity of 1175, 1007, and 842 mA h g-1, respectively, which show that the graphene sheets with fewer layers have higher reversible capacity. -- Graphical abstract: The typical TEM images of the graphene sheets derived from GO3(a), GO2(b) and ...

Energy Technology Data Exchange (ETDEWEB)

Nanowires, films, and membranes comprising ordered porous manganese oxide-based octahedral molecular sieves, and methods of making, are disclosed. A single crystal ultra-long nanowire includes an ordered porous manganese oxide-based octahedral molecular sieve, and has an average length greater than about 10 micrometers and an average diameter of about 5 nanometers to about 100 nanometers. A film comprises a microporous network comprising a plurality of single crystal nanowires in the form of a layer, wherein a plurality of layers is stacked on a surface of a substrate, wherein the nanowires of each layer are substantially axially aligned. A free standing membrane comprises a microporous network comprising a plurality of single crystal nanowires in the form of a layer, wherein a plurality of layers is aggregately stacked, and wherein the nanowires of each layer ...

British Library Electronic Table of Contents (United Kingdom)

In this work AISI 1045 steel were duplex treated via plasma nitriding of chromized layer. Samples were pack chromized by using a powder mixture consisting of ferrochromium, ammonium chloride and alumina at 1273K for 5h. The samples were then plasma-nitrided for 5h at 803K and 823K, in a gas mixture of 75%N2+25%H2. The treated specimens were characterized by scanning electron microscopy (SEM), X-ray diffraction (XRD) analysis and Vickers micro-hardness test. The thickness of chromized layer before nitriding was about 8mm and it was increased after plasma nitriding. According to XRD analysis, the chromized layer was composed of chromium and iron carbides. Plasma nitriding of chromized layer resulted in the formation of chromium and iron nitrides and carbides. The hardness of the duplex layer...

Science.gov (United States)

The storage and chemical properties of the forest litter in dark coniferous forest of Sejila Mountain were studied. The results showed that the existing storage was 5.863 t.hm-2 and the annual litter fall was 0.3205 t.hm-2. It implied that the forest litter decomposed slowly and accumulated quickly, and the turnover of nutrient circles was slow. The contents of N, Ca, Na, and Mn nutrient elements in litter layer were in the order of un-decomposed layer (U layer) > semi-decomposed layer (S layer) > decomposed layer (D layer), those of K, Fe, and Mg were in the order of D layer > S layer > U layer, and P element content was in the order of U layer > D layer > S layer. The pool of elements was 78.483 ...

Energy Technology Data Exchange (ETDEWEB)

The subscale Varestraint test has been used to determine the relative hot cracking susceptibility of the fusion zone in four commercial heats of alloy 800. Although all four heats were susceptible to cracking, one heat exhibited a significant increase in cracking relative to the other three. Optical metallography revealed that nearly all the cracking was localized along fusion zone grain boundaries. Microprobe analysis of the grain boundaries detected high concentrations of titanium, silicon, and niobium resulting from partitioning during solidification. The fusion zone hot cracking mechanism in alloy 800 involves the complex interaction of titanium, silicon, niobium, and carbon along the solidification boundaries. SEM and Auger analyses of the hot crack fracture surfaces revealed the presence of (Ti, Nb)-rich carbides, suggesting that these particles precipitate from the liquid which solidifies last on the fracture ...

British Library Electronic Table of Contents (United Kingdom)

In this research, the interactive effect of grain and specimen sizes on the flow stress of sheet metal in microforming is investigated via the tensile test of pure copper and numerical modeling. Models based on different assumptions are proposed to analyze the size effect phenomenon. It is found that the flow stress decreases linearly with the decrease of the ratio of specimen to grain sizes. The grain boundary thickness decreases and its volume fraction increases with the decrease of grain size. The variation of grain boundary thickness is not proportional to the variation of grain size. Furthermore, the fraction of grain boundary increases with the strain and the ratio of specimen to grain sizes. Based on the FE simulation, it is found that the simulated flow stress, which is modeled bas...

UK PubMed Central (United Kingdom)

The purpose of this study was to determine the thickness of the macula and the retinal nerve fiber layer (RNFL) in Japanese subjects by Stratus optical coherence tomography (OCT), and to compare the...Full Text Available

UK PubMed Central (United Kingdom)

Hydrolytic exoenzymes as indicators of metabolically active bacteria were investigated in four consecutive sapropel layers collected from bathyal sediments of the eastern Mediterranean Sea. For comparison,...Full Text Available

Energy Technology Data Exchange (ETDEWEB)

A prototype detector based on the inclined boron layer principle is introduced. For typical measurement conditions at the Liquids Reflectometer at the Spallation Neutron Source, its count rate capability is shown to be superior to that of the current detector by nearly two orders of magnitude.

Energy Technology Data Exchange (ETDEWEB)

In this work, the silicon oxynitride layer was studied as a tunneling layer for non-volatile memory application by fabricating low temperature polysilicon thin film transistors on glass. Silicon wafers were oxynitrided by only nitrous oxide plasma under different radio frequency powers and plasma treatment times. Plasma oxynitridation was performed in RF plasma using inductively coupled plasma chemical vapor deposition. The X-ray energy dispersive spectroscopy was employed to analyze the atomic concentration ratio of nitrogen/oxygen in oxynitride layer. The oxynitrided layer formed under radio frequency power of 150 W and substrate temperature of 623 K was found to contain the atomic concentration ratio of nitrogen/oxygen as high as 1.57. The advantage of high nitrogen concentration in silicon oxide layer formed by using nitrous oxide plasma was investigated by capacitance-voltage ...

Energy Technology Data Exchange (ETDEWEB)

A duplex surface treatment technique based on calorizing and plasma nitriding was developed to improve the wear and oxidation resistance of H13 steel at high temperatures. The effects of the relative thickness of the calorized layer to the depth of plasma nitriding on the wear and oxidation properties at temperatures up to 900 C were investigated in this work. High-temperature wear tests were performed at 500 C with dry conditions in open air using a ball-on-disk type tribotest machine. Isothermal oxidation tests were performed at 900 C for up to 100 h under controlled atmosphere. The results indicated that the specimens with a calorized layer as an intermediate phase between the surface duplex layer and the base metal showed higher wear and oxidation resistance than the specimens with a nitrided layer alone. During exposure to elevated temperatures, the aluminum in the calorized ...

UK PubMed Central (United Kingdom)

The mammalian neocortex consists of six layers. By contrast, the reptilian and avian cortices have only three, which are believed to be equivalent to layers I, V and VI of mammals. In mammals, the majority...Full Text Available

Science.gov (United States)

... This pinhole process may be similar to the formation of an oxide layer in aluminum electrolytic capacitors immersed in a borax solution. ...

International Nuclear Information System (INIS)

With the aim of optimizing the nitriding process parameters (temperature and gas mixture ) experimental studies of the plasma nitriding of Ck 15 steel were carried out, using a D. C. glow discharge. Nitriding treatments were performed at 450, 500 and 550 and N_2/H_2 volume ratio of 3/1, 1/1 and 1/3 for 5 hours. Nitriding treatment produces modified surface layer consisting of an outer compound layer and an inner diffusion layer.The plasma nitriding of Ck 15 produce single white layer consisting of #gamma#-(Fe_4N).

British Library Electronic Table of Contents (United Kingdom)

There is investigated the role of polymer layers on the metal surface of a fine filler in the formation of a PVC system with electrophysical properties. It is shown that a physicochemical polymer modification takes place under the surface active center influence. Thus, the surface layer properties (density and geometrical characteristics) differ from the PVC ones. The correlation between the electrophysical properties of the PVC composite and the surface layer in the range of the fine copper fraction of 0?11.3 vol % at E ? 106 V m?1 and a frequency response of 20?2 ? 105 Hz is determined. An explanation of the investigated relation is presented.

KoreaScience (Korea)

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Energy Technology Data Exchange (ETDEWEB)

In contrast to plants based on formed coal where, for the purposes of calculating sorbent volume, only one activated charcoal design can be used in a filter layer, powder sorbent technology enables two variations to be used. This can be either a mixture of a number of different activated charcoal forms in one and the same filter layer, or the combination of a number of filter layers on top of each other, each containing a different activated charcoal form, in one and the same construction unit.

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In order to investigate the role of amorphous SiO{sub 2} particles in corrosion and wear resistance of Ni-based metal matrix composite alloying layer, the amorphous nano-SiO{sub 2} particles reinforced Ni-based composite alloying layer has been prepared by double glow plasma alloying on AISI 316L stainless steel surface, where Ni/amorphous nano-SiO{sub 2} was firstly predeposited by brush plating. The composition and microstructure of the nano-SiO{sub 2} particles reinforced Ni-based composite alloying layer were analyzed by using SEM, TEM and XRD. The results indicated that the composite alloying layer consisted of {gamma}-phase and amorphous nano-SiO{sub 2} particles, and under alloying temperature (1000 deg. C) condition, the nano-SiO{sub 2} particles were uniformly distributed in the alloying layer and still kept the amorphous structure. The corrosion resistance of composite ...

CERN Document Server

The paper describes design and practical realization of an internal communication layer referred to as the Internal Interface (II). The system was realized for the RFC Muon Trigger of the CMS experiment. Fully automatic implementation of the communication layer is realized in the FPGA chips and in the control software. The methodology of implementation was presented in the description form of the interface structure from the sides of hardware and software. The examples of the communication layer realizations were given for the RFC Muon Trigger.

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The properties of Mn-doped GaAs layers grown by laser deposition were investigated with measurements of Hall effect and magneto-optical Kerr effect (MOKE). The electrical and magnetic parameters of the layers were defined by growth temperature and quantity of sputtered Mn. It was shown that room-temperature ferromagnetism is revealed by MOKE and, after ruby laser 25 ns pulse annealing, by Hall effect measurements.

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Visible laser light output from an electrically injected vertical cavity surface emitting laser (VSCEL) diode is enabled by the addition of phase-matching spacer layers on either side of the active region to form the optical cavity. The spacer layers comprise InAlP which act as charge carrier confinement means. Distributed Bragg reflector layers are formed on either side of the optical cavity to act as mirrors. 5 figs.

UK PubMed Central (United Kingdom)

BackgroundChromatin insulators or boundary elements are a class of functional elements in the eukaryotic genome. They regulate gene transcription by interfering with promoter-enhancer...Full Text Available

UK PubMed Central (United Kingdom)

Randomized clinical trials are designed with stopping boundaries to guide data monitoring committees with their decision making concerning ongoing trials. In particular, when extremely positive results...Full Text Available

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A procedure was developed to monitor boundaries within which secondary mining operations can be applied. Principal techniques include instrument and operative-remote observations of earth shifts and aerial photography of displacements on the surface of the trough.

UK PubMed Central (United Kingdom)

BackgroundRecent advances in the understanding of the maternal and paternal heritage of south and southwest Asian populations have highlighted their role in the colonization of Eurasia...Full Text Available

International Nuclear Information System (INIS)

Localized deformation may play a key role in the underlying mechanism of irradiation assisted stress corrosion cracking (IASCC) in light water reactor core components. In this study, four austenitic alloys, 18Cr8Ni, 15Cr12Ni, 13Cr15Ni and 21Cr32Ni, with different stacking fault energies were irradiated to 1 and 5 dpa at 360 deg. C using 3.2 MeV protons. Interrupted constant extension rate tensile (CERT) tests were conducted in a simulated BWR environment to determine IASCC susceptibility. In order to characterize the localized deformation in slip channels and grain boundaries, parallel CERT experiments were also performed in an argon atmosphere. Results show that the IASCC susceptibility of the tested alloys increases with increasing irradiation dose and decreasing stacking fault energy. IASCC tends to initiate at locations where slip channels intersect grain boundaries. Localized deformation in the form of grain boundary ...

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A Fe-20at.%Cr-10%Al matrix was dispersed with a wide range of different oxides in order to study the effect of oxygen-active dopants on the high-temperature growth and adhesion of {alpha}-Al{sub 2}O{sub 3} scales. Effect of these various cation dopants on the alumina scale microstructure was correlated with dopant ion segregation to the {alpha}-Al{sub 2}O{sub 3} grain boundaries using analytical electron microscopy. Elements such as Mn and V showed little effect on the oxide scale and were not observed to segregate. Elements such as Y and Gd resulted in finer, more columnar {alpha}-Al{sub 2}O{sub 3} grains and were segregated to scale grain boundaries. However, Ti, Ta, Ca, and Nb also were found to segregate but had a lesser effect on scale morphology. This indicates that cation segregation to scale grain boundaries is not a sufficient condition to achieve beneficial oxidation effects. The driving force for segregation in ...

International Nuclear Information System (INIS)

May 2010 p. 81-84 Japan Ishizawa, Makoto JFE Steel Corporation, Tokyo

Energy Technology Data Exchange (ETDEWEB)

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

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Two additional hyperfine components of the interstellar radical C3H were detected. In addition, methanol was discovered in interstellar clouds. The abundance of HCCN and various chemical isomers in molecular clouds was investigated.

UK PubMed Central (United Kingdom)

Arabidopsis thaliana SUPERMAN (SUP) plays an important role during flower development by maintaining the boundary between stamens and carpels in the inner two whorls....Full Text Available

UK PubMed Central (United Kingdom)

A new 3D model is developed to simulate the self-oscillation of the elongated vocal folds. This model allows for large deformation and longitudinal displacement. The displacement boundary condition...Full Text Available

CERN Document Server

We discuss models of computing that are beyond classical. The primary motivation is to unearth the cause of nonclassical advantages in computation. Completeness results from computational complexity theory lead to the identification of very disparate problems, and offer a kaleidoscopic view into the realm of quantum enhancements in computation. Emphasis is placed on the `power of one qubit' model, and the boundary between quantum and classical correlations as delineated by quantum discord. A recent result by Eastin on the role of this boundary in the efficient classical simulation of quantum computation is discussed. Perceived drawbacks in the interpretation of quantum discord as a relevant certificate of quantum enhancements are addressed.

Energy Technology Data Exchange (ETDEWEB)

An extension of the Polyakov path-integral formulation to compute off-shell amplitudes for open bosonic strings is derived. Boundary conditions require evaluating the path integral on open surfaces with corners on the boundaries. The contribution to the topological term in the action from the corners is exactly that required for unitarity. The presence of corners introduces a Weyl anomaly in the Polyakov measure. This requires a gauge-fixing procedure for the off-shell amplitudes. Consistent factorization of amplitudes with one or two off-shell strings and any number of on-shell tachyons is established.

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The grain boundary crystallographic misorientations of magnetic-pulse-welded (MPW) aluminum alloy (AA) 6061-T6 in linear and tubular configurations were examined using the electron backscattered diffraction (EBSD) technique. A refined structure of heavily deformed grains with higher grain boundary angles was observed in linear welds. Significant spalling was observed away from the joints, in the interior of tubular welds. The results show the complex interaction of shock waves with the materials during this impact welding process.

British Library Electronic Table of Contents (United Kingdom)

We study a generalization of the classical Riemannian Tonnetz to N-tone equally tempered scales (for all N) and arbitrary triads. We classify all the spaces that result. The torus turns out to be the most common possibility, especially as N grows. Other spaces include 2-simplices, tetrahedra boundaries, and the harmonic strip (in both its cylinder and Mobius band variants). The final and most exotic space we find is something we call a 'circle of tetrahedra boundaries'. These are the Tonnetze for spaces of triads which contain a tritone. They are closely related to Peck's Klein bottle Tonnetz.

Energy Technology Data Exchange (ETDEWEB)

In the Ti-Si-C and Ti-Si-C-N systems, metastable layers were precipitated by means of non-reactive magnetron sputtering of hot-pressed two-phase TiC/SiC and TiN/SiC targets with 20 mole% and 50 mole% SiC. The preparation parameters were varied as follows: ion bombardment during precipitation (bias sputtering), substrate temperature, and annealing times when annealing amorphous 50%:50% TiC/SiC and 50%:50% TiN/SiC layers. Sputtering of targets containing 20% SiC was found to result in monophase fcc layers (NaCl structure). This was documented on the basis of X-ray and electron diffraction patterns. Direct precipitation of targets with 50 mole% SiC resulted in amorphous layers. Increasing the ion bombardment during accretion, raising the substrate temperature, and annealing amorphous 50%:50% TiC/SiC and 50%:50% TiN/SiC (layers precipitated directly) resulted in the crystallization of ...

Energy Technology Data Exchange (ETDEWEB)

Superplasticity can be generally achieved by grain boundary sliding (GBS). The GBS in polycrystalline materials sometimes accompanies with intergranular fracture because of stress concentrations at triple points and/or GB irregularities. To develop the superplastic flow, it is necessary to suppress the intergranular cracking. In the present study, therefore, polycrystalline molybdenum with distinct GB microstructures, such as grain boundary character distribution (GBCD), has been employed to clarify the relationship between fracture behaviour and GB microstructures. Microstructures were analyzed using a FE-SEM/EBSP/OIM system prior to 4-points bending tests at 77K, thereafter, crack propagation was observed. The main results obtained are as follows. Stress fluctuations on stress - strain curves were observed for specimens with random oriented grains, whereas such behaviour rarely occurred for ones with textured grains. Difference in the ...

Energy Technology Data Exchange (ETDEWEB)

Thin films of sodium montmorillonite clay and cationic polyacrylamide were grown on a polyethylene terephthalate film using layer-by-layer assembly. After 30 clay-polymer layers are deposited, with a thickness of 571 nm, the resulting transparent film has an oxygen transmission rate (OTR) below the detection limit of commercial instrumentation (< 0.005 cc/m{sup 2}/day/atm). This low OTR, which is unprecedented for a clay-filled polymer composite, is believed to be due to a brick wall nanostructure comprised of completely exfoliated clay in polymeric mortar. With an optical transparency greater than 90% and potential for microwaveability, this thin composite is a good candidate for foil replacement in food packaging and may also be useful for flexible electronics packaging.

International Nuclear Information System (INIS)

This report summarizes the findings of a five-month LDRD project funded through Sandia's NTM Investment Area. The project was aimed at providing the foundation for the development of advanced functional materials through the application of ultrathin coatings of microporous or mesoporous materials onto the surface of substrates such as silicon wafers. Prior art teaches that layers of microporous materials such as zeolites may be applied as, e.g., sensor platforms or gas separation membranes. These layers, however, are typically several microns to several hundred microns thick. For many potential applications, vast improvements in the response of a device could be realized if the thickness of the porous layer were reduced to tens of nanometers. However, a basic understanding of how to synthesize or fabricate such ultra-thin layers is lacking. This report describes traditional and novel approaches to the ...

Energy Technology Data Exchange (ETDEWEB)

As for surface treatment of steel, the ion nitriding method has a lot of advantages and is practically used, while the plasma nitriding is known as a method which is faster in nitriding than the ion nitriding method. However, there are few reports and many unclear points on the plasma nitriding method. In this study, the plasma nitriding of pure iron and SUS304 is conducted using r.f. nitrogen plasma glow discharge to examine composition of the nitrided layers, microstructures, nitriding rate, etc. Moreover, by exposing the specimen once nitrided to H2 plasma, a phenomenon that nitrogen comes out of the specimen surface is examined. It is found from the result that the nitrided layer is divided into a compound layer and a diffusion layer in order from the surface, that in case of pure iron, the compound layer grows predominantly at a low temperature, and the diffusion ...

Energy Technology Data Exchange (ETDEWEB)

This thesis deals with the analysis of dominant loss mechanisms in direct methanol fuel cells (DMFC) and hydrogen fed polymer electrolyte membrane fuel cells (PEFC) by means of experimental characterization and modeling work. Due to different fuels used in these two fuel cell types, the dominant loss mechanisms are different in their nature. All in-situ characterization techniques that are used in this work are based on a novel test fuel cell with embedded reference electrodes. The first part of this work presents a new concept for realizing a reference electrode configuration in a polymer electrolyte membrane fuel cell by means of laser ablation. The laser beam is used to evaporate a small gap into the electrode surface of a catalyst coated membrane (CCM) to isolate the reference electrode from the working/counter electrode (WE/CE). This method enables the simultaneous ablation of the electrodes on both sides of the CCM because the membrane is transparent for the laser beam. ...

International Nuclear Information System (INIS)

In the present study, the relationship between the crystallographic orientations and growth directions of grain boundary-allotriomorphic-#alpha# (GB #alpha#) and secondary Widmanstaetten #alpha# laths growing from the GB #alpha# at grain boundaries separating #beta# grains with specific misorientations has been examined. These relationships have been determined using a variety of characterization techniques, including scanning electron microscopy, orientation imaging microscopy, transmission electron microscopy (TEM) and a dual-beam focused ion beam instrument to provide site-selected TEM foils. Two very interesting cases, one in which the two adjacent #beta# grains are rotated mutually by approximately 10.5"o about a common direction and the other in which the two #beta# grains are in a twin relationship, i.e. a 60"o rotation about a common direction, have been studied. It was discovered that the #alpha# laths growing into two adjacent ...

International Nuclear Information System (INIS)

The present work describes the surface improvement and biocompatibility of TiAl_2_4Nb_1_0 intermetallic alloy using rf plasma nitriding. The nitriding process was carried out at different plasma power from 400 W to 650 W where the other plasma conditions were fixed. Grazing incidence X-ray diffractometry (GIXRD), Auger electron spectroscopy (AES), tribometer and a nanohardness tester were employed to characterize the nitrided layer. Further potentiodynamic polarization method was used to describe the corrosion behavior of the un-nitrided and nitrided alloy. It has been found that the Vickers hardness (HV) and corrosion resistance values of the nitrided layers increase with increasing plasma power while the wear rates of the nitrided layers reduce by two orders of magnitude as compared to those of the un-nitrided layer. This improvement in surface properties of the intermetallic alloy is due to formation ...

International Nuclear Information System (INIS)

The present invention provides a fuel cladding tube having an excellent corrosion resistance and thus a long life, and a suitable manufacturing method therefor. Namely, in the fuel cladding tube, the outer circumference of an inner layer made of a zirconium base alloy is coated with an outer layer made of a metal more corrosion resistant than the zirconium base alloy. Ti or a titanium alloy is suitable for the corrosion resistant metal. In addition, the outer layer can be coated by a method such as vapor deposition or plating, not limited to joining of the inner layer material and the outer layer material. Specifically, a composite material having an inner layer made of a zirconium alloy coated by the outer material made of a titanium alloy is applied with hot fabrication at a temperature within a range of from 500 to 850degC and at a fabrication rate of not ...

International Nuclear Information System (INIS)

The layer-by-layer (LBL) self-assembly has been extensively used as a simple and effective method for the preparation of polyelectrolyte multilayer films. In this work, we utilized this unique method to prepare polyimide precursor/layered double hydroxide (LDH) ultrathin films. Well-crystallized Co-Al-CO_3 LDH and subsequent anion exchanged Co-Al-NO_3 LDH were prepared and characterized by scanning electron microscopy and X-ray diffraction (XRD). By vigorous shaking of the as-prepared Co-Al-NO_3 LDH, positively charged and exfoliated LDH nanosheets were obtained. Atomic force microscopy and XRD investigations indicated the delamination of LDH nanosheets. The precursor of polyimide, poly(amic acid) tertiary amine salt (PAS) was prepared by the polycondensation of dianhydride and diamine, and subsequent amine salt formation. By using the LBL method, heterogeneous ultrathin films of PAS and LDH were prepared. The formation of the ordered ...

Science.gov (United States)

Target vessel materials used in spallation neutron source will be exposed to proton and neutron irradiation and mercury immersion environments. In order to evaluate the surface degradation of the vessel candidate materials due to such environment, the triple-ion beam irradiation taking the spallation reaction into account and mercury immersion tests were carried out. Mechanical properties of the gradient surface layer were evaluated by the inverse analysis with multi-layer model that considers distribution of surface characteristic was applied to the load and depth curves measured by using the instrumented indentation machine. Transmission electron microscopic observations were performed to evaluate the changes of microstructure in irradiated surface layer using focused ion-beam cut micro-specimen. The mechanical properties distributions in the surface layer were evaluated quantitatively and the changes ...

International Nuclear Information System (INIS)

A highly reliable screening method was developed for the determination of lead in tin plated layers and tin-bismuth plated layers. The contents of lead in the layers of the various samples were determined by inductively coupled plasma optical emission spectrometry. The calibration curve for lead in the tin and tin-bismuth plated layers by using WD-XRF exhibited linear correlation from 130 #mu#g/g to 2070 #mu#g/g. Calibration curve of lead normalized with Pb-L#alpha#/Sn-K#alpha# intensity was more linear, and this method was possible to evaluate very small sample. The calibration curve for lead in the tin plated layers by using ED-XRF was good linearly, but it for lead in the tin-bismuth plated layers was affected by Pb-L#alpha# spectrum and Bi-L#alpha# spectrum overlap each other. It was effective for decreasing affect of Bi-L#alpha# spectrum by using curve ...

Energy Technology Data Exchange (ETDEWEB)

Thin passive films formed on highly corrosion-resistant type-312L stainless steel, containing 20 mass% chromium and 6 mass% molybdenum, in 2 mol dm{sup -3} HCl solution at 293 K have been analyzed by glow discharge optical emission spectroscopy (GDOES). The stainless steel does not suffer pitting corrosion even in this aggressive solution, showing a wide passive potential region. The depth profiles obtained clearly show a two-layer structure of the air-formed and passive films: an outer iron-rich layer and an inner layer highly enriched in chromium. Alloy-constituting molybdenum is deficient in the inner layer of the passive films and is enriched in the outer layer, particularly at the active dissolution potential. The molybdenum species in the outer layer may retard the active dissolution of stainless steel, promoting the formation of stable passive films ...

Energy Technology Data Exchange (ETDEWEB)

An approximate analyzing model was developed to predict the azimuth of zigzag streamline, the distribution ratio between two neighboring layers and the radial distribution among the layers of the gas passing through the shaft of blast furnace loaded in layers. The theoretical basis of the approximate analysis is composed of the material balance derived from the assumption that any stream line surrounded with two streamlines is isolated and no material transfer occurs through the tube wall, and of the energy theory that the stream tube and passage are formed so that the total pressure drop in the whole system is the minimum. The effects of the apparent angle of repose between two layers, the packing volume and the passage resistance on the non-uniform flow in the layer were evaluated on the basis of the model. The result calculated by the approximate analysis agrees with the result ...

Science.gov (United States)

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

International Nuclear Information System (INIS)

An annealing with the nanosecond laser light pulse is applied for crystal lattice reconstruction of a disturbed near-surface layer, which was created in semiconductor material as a result of the implantation process. Radiation with energy density higher than the threshold value causes the melting of the surface layer and than the epitaxial recrystallization from the melt on a different substrate. Structural changes occurring in the Ge implanted Si crystals after annealing with different energy densities are investigated by means of the cross-section high-resolution transmission electron microscopy. (author)

Energy Technology Data Exchange (ETDEWEB)

A synthesis of papers based on the United Nations Environment Programme meeting on the ozone layer, Washington DC, this book contains valuable information on ongoing and planned activities concerned with stratospheric ozone problems, and presents the recommendations for further action resulting from the meeting. Possible changes in the characteristics of the ozone layer are discussed, together with the environmental, ecological, climatic, economic, and health implications of stratospheric ozone depletion. A comprehensive survey of current research in five European countries, the USA, Canada, and Australia is included and the volume is concluded by the UNEP report of the meeting and a world plan of action.

CERN Document Server

The conceptual design of the support structures of the EM muon chambers is presented. On each side of the detector the EM chambers are arranged in four layers: one layer of MDTs and the three layers of TGCs. The chambers are mounted on four individual wheel structures per side. The four wheels are inclined by 1.23% and suspended from two longitudinal beams parallel to the beam axis. In order to allow for the opening of the ATLAS detector the wheels can be displaced longitudinally over a distance of 6 m. In addition individual wheels can be separated from each other by up to 1 m for maintenance purposes.

Energy Technology Data Exchange (ETDEWEB)

This paper deals with an artificial neural network (ANN) based adaptive conventional power system stabilizer (PSS). The ANN comprises an input layer, a hidden layer and an output layer. The input vector to the ANN comprises real power (P) and reactive power (Q), while the output vector comprises optimum PSS parameters. A systematic approach for generating training set covering wide range of operating conditions, is presented. The ANN has been trained using back-propagation training algorithm. Investigations reveal that the dynamic performance of ANN based adaptive conventional PSS is quite insensitive to wide variations in loading conditions.

International Nuclear Information System (INIS)

Highly reliable, practical 0.6 #mu#m-band AlGaInP visible laser diodes (LDs), using a GaInP active layer, are described. Over 10,000 hour stable operation at 50 degrees C has been achieved for 3mW light output. Characteristics for visible LDs with an AlGaInP active layer or a multi-quantum-well active layer are also presented.

Science.gov (United States)

... In addition to changes in BrdU, we also observed transient changes in p63 gene expression in the myoepithelial/stem cell layer. ...

Science.gov (United States)

In order to support long duration cryogenic propellant storage, the Cryogenic Fluid Management (CFM)

Energy Technology Data Exchange (ETDEWEB)

For a solar cell, in order to minimize the loss of incident light, transparent glass or plastic material is used at the incident part. When a solar cell is watched from the light incident part, a silicon base material is directly observed with either block or brown color only. This invention enables a solar cell to give brighter color on the incident surface by placing a reflective film which reflects only the light of specific wavelength, without reducing the efficiency of the solar cell. This reflective film consists of multi-layered dielectric with 12 layers and alternative combination of highly refractive and less refractive substances. Highly refractive layer is Y/sub 2/O/sub 3/ with refractive index 1.74 and the less refractive layer is SiO/sub 2/ with refractive index 1.45. (5 figs)

International Nuclear Information System (INIS)

Agricultural practices frequently cause the development of a soil compacted layer below the surface. These compacted layers restrict the root penetration into deeper layers of soil, in search for water. It is proposed to monitor, using Non Destructive Test, the roots growth due to the planting of standard seeds in different agricultural soils, in function of their compactness and humidity. It will be used the neutrons beams derived from an irradiation channel called J-9 of the Reactor Argonauta (IEN/CNEN), so that the neutron radiographic images of the soil-plant system can be obtained. Each root can be evaluated for its ability to penetrate into compacted soil layers; this fact would mean an optimization of agricultural harvests. (author)

Science.gov (United States)

... The insu- lation between gate and nanowire is the high-k dielectric HfO2, deposited by atomic layer depo- sition (ALD). ...

Science.gov (United States)

Map layer displays land designated as Suitable Land For Timber Production for the Forest Plan. It consists of all National Forest Lands less Non-forested ... ...

Energy Technology Data Exchange (ETDEWEB)

The growth of thin Pd[sub 2]Si films on Si(111) surfaces is studied using [ital in] [ital situ] transmission electron microscope under ultrahigh vacuum conditions. No immediate reaction of deposited Pd with Si is observed at room temperature. At [similar to]200 [degree]C, uniform Pd[sub 2]Si films can be formed. The thin Pd[sub 2]Si films are found to grow into strained islands at elevated temperatures. Interfacial misfit dislocations associated with interfacial steps propagate across the strained islands, causing the islands to grow layer-by-layer at the interface. The strain fields associated with the misfit dislocations are believed to be responsible for this behavior.