WorldWideScience

Sample records for resistant fluid conducting

  1. A numerical study on the flow and performance characteristics of a piezoelectric micropump with electromagnetic resistance for electrically conducting fluids

    International Nuclear Information System (INIS)

    An, Yong Jun; Choi, Chung Ryul; Kim, Chang Nyung

    2008-01-01

    A numerical analysis has been conducted for flow characteristics and performance of a micropump with piezodisk and MHD (MagnetoHydroDynamics) fluid. Various micro systems which could not be considered in the past have been recently growing with the development of MEMS (Micro Electro Mechanical System) and micro machining technology. Especially, micropumps, essential part of micro fluidic devices, are being lively studied by many researchers. In the present study, the piezo electric micropump with electromagnetic resistance for electrically conducting fluids is considered. The prescribed grid deformation method is used for the displacement of the membrane. The change of the performance of the micropump and flow characteristics of the electrically conducting fluid with the magnitude of the magnetic fields, duct size, the position of the inlet and outlet duct are investigated in the present study

  2. Hall Effect Influence on a Highly Conducting Fluid

    Energy Technology Data Exchange (ETDEWEB)

    Witalis, E.A.

    1966-11-15

    The properties of an incompressible perfect fluid exhibiting Hall effect is investigated in the limit of infinite electrical conductivity and mobility. The magnetic field strength and the fluid velocity are found to obey the equations B = {mu}{rho}/{sigma} x curlV and V -{mu}/({sigma}{mu}{sub 0}) x curlB (MKS units) where {rho}, {sigma} and {mu} denote mass density, conductivity and charge carrier mobility. Some physical interpretations and applications are given.

  3. Thermal conductivity of the Lennard-Jones chain fluid model.

    Science.gov (United States)

    Galliero, Guillaume; Boned, Christian

    2009-12-01

    Nonequilibrium molecular dynamics simulations have been performed to estimate, analyze, and correlate the thermal conductivity of a fluid composed of short Lennard-Jones chains (up to 16 segments) over a large range of thermodynamic conditions. It is shown that the dilute gas contribution to the thermal conductivity decreases when the chain length increases for a given temperature. In dense states, simulation results indicate that the residual thermal conductivity of the monomer increases strongly with density, but is weakly dependent on the temperature. Compared to the monomer value, it has been noted that the residual thermal conductivity of the chain was slightly decreasing with its length. Using these results, an empirical relation, including a contribution due to the critical enhancement, is proposed to provide an accurate estimation of the thermal conductivity of the Lennard-Jones chain fluid model (up to 16 segments) over the domain 0.8values of the Lennard-Jones chain fluid model merge on the same "universal" curve when plotted as a function of the excess entropy. Furthermore, it is shown that the reduced configurational thermal conductivity of the Lennard-Jones chain fluid model is approximately proportional to the reduced excess entropy for all fluid states and all chain lengths.

  4. NONLINEAR DYNAMO IN A ROTATING ELECTRICALLY CONDUCTING FLUID

    Directory of Open Access Journals (Sweden)

    M. I. Kopp

    2017-05-01

    Full Text Available We found a new large-scale instability, which arises in the rotating conductive fluid with small-scale turbulence. Turbulence is generated by small-scale external force with a low Reynolds number. The theory is built simply by the method of multiscale asymptotic expansions. Nonlinear equations for vortex and magnetic perturbations obtained in the third order for small Reynolds number. It is shown that the combined effects of the Coriolis force and the small external forces in a rotating conducting fluid possible large-scale instability. The large-scale increments of the instability, correspond to generation as the vortex and magnetic disturbances. This type of instability is classified as hydrodynamic and MHD alpha-effect. We studied the stationary regimes of nonlinear equations of magneto-vortex dynamo. In the limit of weakly conducting fluid found stationary solutions in the form of helical kinks. In the limit of high conductivity fluid was obtained stationary solutions in the form of nonlinear periodic waves and kinks.

  5. Electrical Conductivity Distributions in Discrete Fluid-Filled Fractures

    Science.gov (United States)

    James, S. C.; Ahmmed, B.; Knox, H. A.; Johnson, T.; Dunbar, J. A.

    2017-12-01

    It is commonly asserted that hydraulic fracturing enhances permeability by generating new fractures in the reservoir. Furthermore, it is assumed that in the fractured system predominant flow occurs in these newly formed and pre-existing fractures. Among the phenomenology that remains enigmatic are fluid distributions inside fractures. Therefore, determining fluid distribution and their associated temporal and spatial evolution in fractures is critical for safe and efficient hydraulic fracturing. Previous studies have used both forward modeling and inversion of electrical data to show that a geologic system consisting of fluid filled fractures has a conductivity distribution, where fractures act as electrically conductive bodies when the fluids are more conductive than the host material. We will use electrical inversion for estimating electrical conductivity distribution within multiple fractures from synthetic and measured data. Specifically, we will use data and well geometries from an experiment performed at Blue Canyon Dome in Socorro, NM, which was used as a study site for subsurface technology, engineering, and research (SubTER) funded by DOE. This project used a central borehole for energetically stimulating the system and four monitoring boreholes, emplaced in the cardinal directions. The electrical data taken during this project used 16 temporary electrodes deployed in the stimulation borehole and 64 permanent electrodes in the monitoring wells (16 each). We present results derived using E4D from scenarios with two discrete fractures, thereby discovering the electric potential response of both spatially and temporarily variant fluid distribution and the resolution of fluid and fracture boundaries. These two fractures have dimensions of 3m × 0.01m × 7m and are separated by 1m. These results can be used to develop stimulation and flow tests at the meso-scale that will be important for model validation. Sandia National Laboratories is a multi

  6. Simultaneous Rheoelectric Measurements of Strongly Conductive Complex Fluids

    Science.gov (United States)

    Helal, Ahmed; Divoux, Thibaut; McKinley, Gareth H.

    2016-12-01

    We introduce an modular fixture designed for stress-controlled rheometers to perform simultaneous rheological and electrical measurements on strongly conductive complex fluids under shear. By means of a nontoxic liquid metal at room temperature, the electrical connection to the rotating shaft is completed with minimal additional mechanical friction, allowing for simultaneous stress measurements at values as low as 1 Pa. Motivated by applications such as flow batteries, we use the capabilities of this design to perform an extensive set of rheoelectric experiments on gels formulated from attractive carbon-black particles, at concentrations ranging from 4 to 15 wt %. First, experiments on gels at rest prepared with different shear histories show a robust power-law scaling between the elastic modulus G0' and the conductivity σ0 of the gels—i.e., G0'˜σ0α, with α =1.65 ±0.04 , regardless of the gel concentration. Second, we report conductivity measurements performed simultaneously with creep experiments. Changes in conductivity in the early stage of the experiments, also known as the Andrade-creep regime, reveal for the first time that plastic events take place in the bulk, while the shear rate γ ˙ decreases as a weak power law of time. The subsequent evolution of the conductivity and the shear rate allows us to propose a local yielding scenario that is in agreement with previous velocimetry measurements. Finally, to establish a set of benchmark data, we determine the constitutive rheological and electrical behavior of carbon-black gels. Corrections first introduced for mechanical measurements regarding shear inhomogeneity and wall slip are carefully extended to electrical measurements to accurately distinguish between bulk and surface contributions to the conductivity. As an illustrative example, we examine the constitutive rheoelectric properties of five different grades of carbon-black gels and we demonstrate the relevance of this rheoelectric apparatus as a

  7. The magnetic-distortion probe: velocimetry in conducting fluids.

    Science.gov (United States)

    Miralles, Sophie; Verhille, Gautier; Plihon, Nicolas; Pinton, Jean-François

    2011-09-01

    A new type of velocimeter, capable of local velocity measurements in conducting fluids, is introduced. The principle of the "magnetic-distortion probe" is based on the measurement of the induced magnetic field by the flow of a conducting fluid in the vicinity of a localized magnetic field. The new velocimeter has no moving parts, and can be enclosed in a sealed cap, easing the implementation in harsh environments, such as liquid metals. The proposed method allows one to probe both the continuous part and fluctuations of the velocity, the temporal and spatial resolution being linked to the actual geometric configuration of the probe. A prototype probe has been tested in a gallinstan pipe flow and in a fully turbulent flow of liquid gallium generated by the counter rotation of two coaxial impellers in a cylinder. The signals have been compared to a reference potential probe and show very good agreement both for time-averaged velocities and turbulent fluctuations. The prototype is shown to detect motion from a few cm s(-1) to a few m s(-1). Moreover, the use of the magnetic-distortion probe with large-scale applied magnetic field is discussed. © 2011 American Institute of Physics

  8. Thermophysical properties of fluids: dynamic viscosity and thermal conductivity

    Science.gov (United States)

    Latini, G.

    2017-11-01

    Thermophysical properties of fluids strongly depend upon atomic and molecular structure, complex systems governed by physics laws providing the time evolution. Theoretically the knowledge of the initial position and velocity of each atom, of the interaction forces and of the boundary conditions, leads to the solution; actually this approach contains too many variables and it is generally impossible to obtain an acceptable solution. In many cases it is only possible to calculate or to measure some macroscopic properties of fluids (pressure, temperature, molar volume, heat capacities...). The ideal gas “law,” PV = nRT, was one of the first important correlations of properties and the deviations from this law for real gases were usefully proposed. Moreover the statistical mechanics leads for example to the “hard-sphere” model providing the link between the transport properties and the molecular size and speed of the molecules. Further approximations take into account the intermolecular interactions (the potential functions) which can be used to describe attractions and repulsions. In any case thermodynamics reduces experimental or theoretical efforts by relating one physical property to another: the Clausius-Clapeyron equation provides a classical example of this method and the PVT function must be known accurately. However, in spite of the useful developments in molecular theory and computers technology, often it is usual to search for physical properties when the existing theories are not reliable and experimental data are not available: the required value of the physical or thermophysical property must be estimated or predicted (very often estimation and prediction are improperly used as synonymous). In some cases empirical correlations are useful, if it is clearly defined the range of conditions on which they are based. This work is concerned with dynamic viscosity µ and thermal conductivity λ and is based on clear and important rules to be respected

  9. 30 CFR 75.1107-2 - Approved fire-resistant hydraulic fluids; minimum requirements.

    Science.gov (United States)

    2010-07-01

    ... 30 Mineral Resources 1 2010-07-01 2010-07-01 false Approved fire-resistant hydraulic fluids... Protection Fire Suppression Devices and Fire-Resistant Hydraulic Fluids on Underground Equipment § 75.1107-2 Approved fire-resistant hydraulic fluids; minimum requirements. Fire-resistant hydraulic fluids and...

  10. A High-Temperature Transient Hot-Wire Thermal Conductivity Apparatus for Fluids.

    Science.gov (United States)

    Perkins, R A; Roder, H M; Nieto de Castro, C A

    1991-01-01

    A new apparatus for measuring both the thermal conductivity and thermal diffusivity of fluids at temperatures from 220 to 775 K at pressures to 70 MPa is described. The instrument is based on the step-power-forced transient hot-wire technique. Two hot wires are arranged in different arms of a Wheatstone bridge such that the response of the shorter compensating wire is subtracted from the response of the primary wire. Both hot wires are 12.7 µm diameter platinum wire and are simultaneously used as electrical heat sources and as resistance thermometers. A microcomputer controls bridge nulling, applies the power pulse, monitors the bridge response, and stores the results. Performance of the instrument was verified with measurements on liquid toluene as well as argon and nitrogen gas. In particular, new data for the thermal conductivity of liquid toluene near the saturation line, between 298 and 550 K, are presented. These new data can be used to illustrate the importance of radiative heat transfer in transient hot-wire measurements. Thermal conductivity data for liquid toluene, which are corrected for radiation, are reported. The precision of the thermal conductivity data is ± 0.3% and the accuracy is about ±1%. The accuracy of the thermal diffusivity data is about ± 5%. From the measured thermal conductivity and thermal diffusivity, we can calculate the specific heat, C p , of the fluid, provided that the density is measured, or available through an equation of state.

  11. Mathematical Theory of Compressible Viscous, and Heat Conducting Fluids

    Czech Academy of Sciences Publication Activity Database

    Feireisl, Eduard

    2007-01-01

    Roč. 33, č. 4 (2007), s. 461-490 ISSN 0898-1221 R&D Projects: GA ČR GA201/05/0164 Institutional research plan: CEZ:AV0Z10190503 Keywords : compressible fluid * viscous fluid * entropy Subject RIV: BA - General Mathematics Impact factor: 0.720, year: 2007

  12. Conduction Mechanism of Valence Change Resistive Switching Memory: A Survey

    Directory of Open Access Journals (Sweden)

    Ee Wah Lim

    2015-09-01

    Full Text Available Resistive switching effect in transition metal oxide (TMO based material is often associated with the valence change mechanism (VCM. Typical modeling of valence change resistive switching memory consists of three closely related phenomena, i.e., conductive filament (CF geometry evolution, conduction mechanism and temperature dynamic evolution. It is widely agreed that the electrochemical reduction-oxidation (redox process and oxygen vacancies migration plays an essential role in the CF forming and rupture process. However, the conduction mechanism of resistive switching memory varies considerably depending on the material used in the dielectric layer and selection of electrodes. Among the popular observations are the Poole-Frenkel emission, Schottky emission, space-charge-limited conduction (SCLC, trap-assisted tunneling (TAT and hopping conduction. In this article, we will conduct a survey on several published valence change resistive switching memories with a particular interest in the I-V characteristic and the corresponding conduction mechanism.

  13. Effects of temperature gradient induced nanoparticle motion on conduction and convection of fluid

    International Nuclear Information System (INIS)

    Zhou Leping; Peterson, George P.; Yoda, Minani; Wang Buxuan

    2012-01-01

    The role of temperature gradient induced nanoparticle motion on conduction and convection was investigated. Possible mechanisms for variations resulting from variations in the thermophysical properties are theoretically and experimentally discussed. The effect of the nanoparticle motion on conduction is demonstrated through thermal conductivity measurement of deionized water with suspended CuO nanoparticles (50 nm in diameter) and correlated with the contributions of Brownian diffusion, thermophoresis, etc. The tendencies observed is that the magnitude of and the variation in the thermal conductivity increases with increasing volume fraction for a given temperature, which is due primarily to the Brownian diffusion of the nanoparticles. Using dimensional analysis, the thermal conductivity is correlated and both the interfacial thermal resistance and near-field radiation are found to be essentially negligible. A modification term that incorporates the contributions of Brownian motion and thermophoresis is proposed. The effect of nanoscale convection is illustrated through an experimental investigation that utilized fluorescent polystyrene nanoparticle tracers (200 nm in diameter) and multilayer nanoparticle image velocimetry. The results indicate that both the magnitude and the deviation of the fluid motion increased with increasing heat flux in the near-wall region. Meanwhile, the fluid motion tended to decrease with the off-wall distance for a given heating power. A corresponding numerical study of convection of pure deionized water shows that the velocity along the off-wall direction is several orders of magnitude lower than that of deionized water, which indicates that Brownian motion in the near-wall region is crucial for fluid with suspended nanoparticles in convection.

  14. Relating bulk electrical conduction to litho-textural properties and pore-fluid conductivity within porous alluvial aquifers

    Science.gov (United States)

    Mele, M.; Giudici, M.; Inzoli, S.; Cavalli, E.; Bersezio, R.

    2012-04-01

    The estimate of hydraulic conductivity from Direct Current methods represents a powerful tool in aquifer characterization as both electrical and hydraulic conductivities depend on connected pore volumes and connected pore surface areas. A crucial, intermediate stage of this process is the assessment of sediments' textures and lithology from DC electrical conductivity as the electrical response of the aquifers' basic building blocks (i.e., hydrofacies) is controlled by the prevailing process of electrical conduction, electrolytic (σEL; pore-volume dominated) vs. "shale" (σSH; pore-surface dominated), determined by pore-space structure, clay distribution and electrical properties of pore fluids (σW). In this work laboratory experiments were conducted and the results were interpreted through the analysis i) of a volume-averaged, macroscopic litho-textural property of alluvial hydrofacies', the coarse-to-fine ratio (C/F), as a "proxy" of the process of electrical conduction within each samples on the basis of the volume proportion between nonconductive, coarse-grained and conductive, shaly textures and ii) of the surface conduction component, produced in fresh-to-salt water environment by clay materials. 8 hydrofacies' samples were collected with an hand-auger within the outcropping alluvial aquifers of the Quaternary meander river belt of the southernmost Lodi plain (northern Italy), represented by loose gravelly-sands to sands (6 samples), fine and sandy-silty clays (2 samples). As a first step, laboratory measurements of the bulk electrical conductivity (σB) of representative sub-samples, totally saturated with water with different salinity (σW from 125 to 1100 μs/cm), were performed. The experimental apparatus was made up by a series of polycarbonate, cylindrical cells (9cm x 12cm) equipped with external, copper plates as current electrodes and internal, copper squared-grids as potential electrodes. Electrical conductivity of each sample was obtained

  15. Effect of fluid-filled boreholes on resistivity tomography; Hiteiko tomography ni okeru konaisui no eikyo

    Energy Technology Data Exchange (ETDEWEB)

    Sugimoto, Y. [DIA Consultants Co. Ltd., Tokyo (Japan)

    1997-10-22

    Theoretical discussions were given on the effect of fluid-filled boreholes on resistivity tomography. The discussions performed incorporation of earth resistance as a method to consider borehole diameters in an FEM calculation using wire elements. The numerical experiment conducted a simulation on the following two objects: resistivity tomography in a horizontal multi-layer structure consisted of layers with resistivity ranging from 10 to 10000 ohm-m, and a model with a slanted low resistivity band existing in a background of 5000 ohm-m. As a result of the discussions, it was made clear that the effect of the boreholes can be corrected by giving earth resistance between the wire elements and natural ground. An improved potential calculating program indicated that the effect of the fluid-filled boreholes in the resistivity tomography generates false images with high resistivity along the bores if the resistivity has high contrast. Incorporating the wire elements into an inverse analysis model reduces the false images and improves the accuracy. 1 ref., 12 figs.

  16. Enhancing thermal conductivity of fluids with graphite nanoparticles and carbon nanotube

    Science.gov (United States)

    Zhang, Zhiqiang [Lexington, KY; Lockwood, Frances E [Georgetown, KY

    2008-03-25

    A fluid media such as oil or water, and a selected effective amount of carbon nanomaterials necessary to enhance the thermal conductivity of the fluid. One of the preferred carbon nanomaterials is a high thermal conductivity graphite, exceeding that of the neat fluid to be dispersed therein in thermal conductivity, and ground, milled, or naturally prepared with mean particle size less than 500 nm, and preferably less than 200 nm, and most preferably less than 100 nm. The graphite is dispersed in the fluid by one or more of various methods, including ultrasonication, milling, and chemical dispersion. Carbon nanotubes with graphitic structure is another preferred source of carbon nanomaterial, although other carbon nanomaterials are acceptable. To confer long term stability, the use of one or more chemical dispersants is preferred. The thermal conductivity enhancement, compared to the fluid without carbon nanomaterial, is proportional to the amount of carbon nanomaterials (carbon nanotubes and/or graphite) added.

  17. Resistive fluid turbulence and tokamak edge plasma dynamics

    International Nuclear Information System (INIS)

    Thayer, D.R.; Diamond, P.H.; Ritz, C.P.

    1988-01-01

    Electrostatic and electromagnetic turbulence has been linked to particle and heat transport in tokamaks. Here we report on several related theoretical and experimental investigations of edge plasma dynamics. The theory of thermally-driven convective cell edge turbulence has been developed to treat the coupling of the radiative-condensation instability to the resistivity-gradient expansion free energy. This model of edge turbulence has led to theoretical understanding of several anomalies in electrostatic edge turbulence found from experiment: that fluctuation levels and transport coefficients are larger than naively expected, that potential fluctuations are significantly larger than the density. Impurity gas-puffing experiments on the TEXT tokamak have been performed to test this theory, and have indicated favorable results. Resistive fluid turbulence models have also been explored and applied in the hope of understanding the extensive edge magnetic fluctuation studies. We discuss models of electromagnetic microtearing turbulence, resistive-pressure-gradient-driven turbulence, and ion temperature gradient driven turbulence. In particular we study the role of resistive fluid turbulence with separatrix effects in the L /yield/ H mode transition. 36 refs., 2 figs

  18. Smart conducting polymer composites having zero temperature coefficient of resistance

    Science.gov (United States)

    Chu, Kunmo; Lee, Sung-Chul; Lee, Sangeui; Kim, Dongearn; Moon, Changyoul; Park, Sung-Hoon

    2014-12-01

    Zero temperature coefficient of resistance (TCR) is essential for the precise control of temperature in heating element and sensor applications. Many studies have focused on developing zero-TCR systems with inorganic compounds; however, very few have dealt with developing zero-TCR systems with polymeric materials. Composite systems with a polymer matrix and a conducting filler show either a negative (NTC) or a positive temperature coefficient (PTC) of resistance, depending on several factors, e.g., the polymer nature and the filler shape. In this study, we developed a hybrid conducting zero-TCR composite having self-heating properties for thermal stability and reliable temperature control. The bi-layer composites consisted of a carbon nanotube (CNT)-based layer having an NTC of resistance and a carbon black (CB)-based layer having a PTC of resistance which was in direct contact with electrodes to stabilize the electrical resistance change during electric Joule heating. The composite showed nearly constant resistance values with less than 2% deviation of the normalized resistance until 200 °C. The CB layer worked both as a buffer and as a distributor layer against the current flow from an applied voltage. This behavior, which was confirmed both experimentally and theoretically, has been rarely reported for polymer-based composite systems.Zero temperature coefficient of resistance (TCR) is essential for the precise control of temperature in heating element and sensor applications. Many studies have focused on developing zero-TCR systems with inorganic compounds; however, very few have dealt with developing zero-TCR systems with polymeric materials. Composite systems with a polymer matrix and a conducting filler show either a negative (NTC) or a positive temperature coefficient (PTC) of resistance, depending on several factors, e.g., the polymer nature and the filler shape. In this study, we developed a hybrid conducting zero-TCR composite having self

  19. Vaginal washing fluid C-reactive protein levels in women with recurrent or treatment resistant vaginitis

    OpenAIRE

    Aytekin Tokmak; İrfan Özer; Selçuk Erkılınç; Ali İrfan Güzel; Mahmut Kuntay Kokanalı; Mustafa Uğur

    2015-01-01

    Objective: The aim of this study is to evaluate the C-reactive protein (CRP) levels in vaginal washing fluid (VWF) in women with a history of recurrent and/or treatment resistant vaginitis. Methods: This prospective case control study was conducted in the gynecology clinic of the current hospital. A total of 64 women (33 with a history of recurrent and/ or treatment resistant vaginitis as study group and 31 healthy women as control group) were enrolled in the study. The recorded parameters we...

  20. Resistivity mapping: An example of aged conducting polymer

    Czech Academy of Sciences Publication Activity Database

    Křivka, I.; Prokeš, J.; Stejskal, Jaroslav

    2007-01-01

    Roč. 92, č. 5 (2007), s. 829-837 ISSN 0141-3910 Institutional research plan: CEZ:AV0Z40500505 Keywords : conductivity * resistivity * van der Pauw method Subject RIV: CD - Macromolecular Chemistry Impact factor: 2.073, year: 2007

  1. Electrical Resistivity Survey For Conductive Soils At Gas Turbine ...

    African Journals Online (AJOL)

    Ten (10) vertical electrical soundings (VES) using Schlumberger configuration were carried out to delineate subsurface conductive soils for the design of earthling grid for electrical materials installation at the Gas Turbine Station, Ajaokuta, SW Nigeria. Interpretation of the resistivity data revealed three major geoelectric ...

  2. Couette flow of a hydro-magnetic electrically conducting fluid with ...

    African Journals Online (AJOL)

    Numerical solution of the problem of Couette flow of a hydromagnetic electrically conducting fluid has been obtained where the temperature of the fluid is assumed to vary exponentially. Results obtained for the flow velocity, temperature, skin friction and rate of heat transfer indicate that the temperature is higher when the ...

  3. Leaching of Conductive Species: Implications to Measurements of Electrical Resistivity.

    Science.gov (United States)

    Spragg, R; Jones, S; Bu, Y; Lu, Y; Bentz, D; Snyder, K; Weiss, J

    2017-05-01

    Electrical tests have been used to characterize the microstructure of porous materials, the measured electrical response being determined by the contribution of the microstructure (porosity and tortuosity) and the electrical properties of the solution (conductivity of the pore solution) inside the pores of the material. This study has shown how differences in concentration between the pore solution (i.e., the solution in the pores) and the storage solution surrounding the test specimen leads to significant transport (leaching) of the conductive ionic species between the pore solution and the storage solution. Leaching influences the resistivity of the pore solution, thereby influencing electrical measurements on the bulk material from either a surface or uniaxial bulk resistance test. This paper has three main conclusions: 1.) Leaching of conductive species does occur with concentration gradients and that a diffusion based approach can be used to estimate the time scale associated with this change. 2.) Leaching of ions in the pore solution can influence resistivity measurements, and the ratio of surface to uniaxial resistivity can be used as a method to assess the presence of leaching and 3.) An estimation of the magnitude of leaching for standardized tests of cementitious materials.

  4. Growth and Morphology of Supercritical Fluids, a Fluid Physics Experiment Conducted on Mir, Complete

    Science.gov (United States)

    Wilkinson, R. Allen

    2001-01-01

    The Growth and Morphology of Supercritical Fluids (GMSF) is an international experiment facilitated by the NASA Glenn Research Center and under the guidance of U.S. principal investor Professor Hegseth of the University of New Orleans and three French coinvestigators: Daniel Beysens, Yves Garrabos, and Carole Chabot. The GMSF experiments were concluded in early 1999 on the Russian space station Mir. The experiments spanned the three science themes of near-critical phase separation rates, interface dynamics in near-critical boiling, and measurement of the spectrum of density fluctuation length scales very close to the critical point. The fluids used were pure CO2 or SF6. Three of the five thermostats used could adjust the sample volume with the scheduled crew time. Such a volume adjustment enabled variable sample densities around the critical density as well as pressure steps (as distinct from the usual temperature steps) applied to the sample. The French-built ALICE II facility was used for these experiments. It allows tightly thermostated (left photograph) samples (right photograph) to be controlled and viewed/measured. Its diagnostics include interferometry, shadowgraph, high-speed pressure measurements, and microscopy. Data were logged on DAT tapes, and PCMCIA cards and were returned to Earth only after the mission was over. The ground-breaking near critical boiling experiment has yielded the most results with a paper published in Physical Review Letters (ref. 1). The boiling work also received press in Science Magazine (ref. 2). This work showed that, in very compressible near-critical two-phase pure fluids, a vapor bubble was induced to temporarily overheat during a rapid heating of the sample wall. The temperature rise in the vapor was 23-percent higher than the rise in the driving container wall. The effect is due to adiabatic compression of the vapor bubble by the rapid expansion of fluid near the boundary during heatup. Thermal diffusivity is low near the

  5. Thermal conductivity and thermal boundary resistance of nanostructures

    Directory of Open Access Journals (Sweden)

    Merabia Samy

    2011-01-01

    Full Text Available Abstract We present a fabrication process of low-cost superlattices and simulations related with the heat dissipation on them. The influence of the interfacial roughness on the thermal conductivity of semiconductor/semiconductor superlattices was studied by equilibrium and non-equilibrium molecular dynamics and on the Kapitza resistance of superlattice's interfaces by equilibrium molecular dynamics. The non-equilibrium method was the tool used for the prediction of the Kapitza resistance for a binary semiconductor/metal system. Physical explanations are provided for rationalizing the simulation results. PACS 68.65.Cd, 66.70.Df, 81.16.-c, 65.80.-g, 31.12.xv

  6. Effective conductivity by fluid analogy for a porous insulator filled with a conductor

    International Nuclear Information System (INIS)

    Berryman, J.G.

    1983-01-01

    By combining of identities relating effective conductivity to tortuosity and tortuosity to induced mass, a general formula for the effective (electrical or thermal) conductivity of a porous insulator filled with a conductor is obtained. This formula depends on an induced-mass factor which arises by treating of the conducting material as an inviscid fluid. This induced-mass factor can be estimated with the use of an effective-medium theory. For random arrays of equal spheres, the estimates of conductivity obtained with the use of this fluid analogy are in good agreement with recent exact values derived for periodic arrays of insulating spheres to closest packing

  7. Maximum thermal conductance for a micro-channel, utilising Newtonian and non-Newtonian fluid

    Science.gov (United States)

    Stocks, M. D.; Bello-Ochende, T.; Meyer, J. P.

    2014-06-01

    This paper investigates the thermal behaviour of two micro-channel elements cooled by Newtonian and non-Newtonian fluids, with the objective to maximise thermal conductance subject to constraints. This is done firstly for a two-dimensional duct micro-channel and secondly for a three-dimensional complex micro-channel. A numerical model is used to solve the governing equations relating to flow and temperature fields for both cases. The geometric configuration of each cooling channel is optimised for Newtonian and non-Newtonian fluid at a fixed inlet velocity and heat flux. In addition, the effect of porosity on thermal conductance is investigated. It was found, in both cases, that the non-Newtonian fluid characteristics result in a significant variation in thermal conductance as inlet velocity is increased. The characteristics of a dilatant fluid greatly reduce thermal conductance on account of shear thickening on the boundary surface. In contrast, a pseudoplastic fluid shows increased thermal conductance. A comparison of the complex micro-channel and the duct micro-channel shows the improved thermal conductance resulting from greater flow access to the conductive area, achieved by the complex micro-channel.

  8. Thermal conductivity and viscosity of self-assembled alcohol/polyalphaolefin nanoemulsion fluids

    Science.gov (United States)

    2011-01-01

    Very large thermal conductivity enhancement had been reported earlier in colloidal suspensions of solid nanoparticles (i.e., nanofluids) and more recently also in oil-in-water emulsions. In this study, nanoemulsions of alcohol and polyalphaolefin (PAO) are spontaneously generated by self-assembly, and their thermal conductivity and viscosity are investigated experimentally. Alcohol and PAO have similar thermal conductivity values, so that the abnormal effects, such as particle Brownian motion, on thermal transport could be deducted in these alcohol/PAO nanoemulsion fluids. Small angle neutron-scattering measurement shows that the alcohol droplets are spheres of 0.8-nm radius in these nanoemulsion fluids. Both thermal conductivity and dynamic viscosity of the fluids are found to increase with alcohol droplet loading, as expected from classical theories. However, the measured conductivity increase is very moderate, e.g., a 2.3% increase for 9 vol%, in these fluids. This suggests that no anomalous enhancement of thermal conductivity is observed in the alcohol/PAO nanoemulsion fluids tested in this study. PMID:21711807

  9. Thermal conductivity and viscosity of self-assembled alcohol/polyalphaolefin nanoemulsion fluids

    Directory of Open Access Journals (Sweden)

    Hammouda Boualem

    2011-01-01

    Full Text Available Abstract Very large thermal conductivity enhancement had been reported earlier in colloidal suspensions of solid nanoparticles (i.e., nanofluids and more recently also in oil-in-water emulsions. In this study, nanoemulsions of alcohol and polyalphaolefin (PAO are spontaneously generated by self-assembly, and their thermal conductivity and viscosity are investigated experimentally. Alcohol and PAO have similar thermal conductivity values, so that the abnormal effects, such as particle Brownian motion, on thermal transport could be deducted in these alcohol/PAO nanoemulsion fluids. Small angle neutron-scattering measurement shows that the alcohol droplets are spheres of 0.8-nm radius in these nanoemulsion fluids. Both thermal conductivity and dynamic viscosity of the fluids are found to increase with alcohol droplet loading, as expected from classical theories. However, the measured conductivity increase is very moderate, e.g., a 2.3% increase for 9 vol%, in these fluids. This suggests that no anomalous enhancement of thermal conductivity is observed in the alcohol/PAO nanoemulsion fluids tested in this study.

  10. Parametric electroconvection in a weakly conducting fluid in a horizontal parallel-plate capacitor

    International Nuclear Information System (INIS)

    Kartavykh, N. N.; Smorodin, B. L.; Il’in, V. A.

    2015-01-01

    We study the flows of a nonuniformly heated weakly conducting fluid in an ac electric field of a horizontal parallel-plate capacitor. Analysis is carried out for fluids in which the charge formation is governed by electroconductive mechanism associated with the temperature dependence of the electrical conductivity of the medium. Periodic and chaotic regimes of fluid flow are investigated in the limiting case of instantaneous charge relaxation and for a finite relaxation time. Bifurcation diagrams and electroconvective regimes charts are constructed. The regions where fluid oscillations synchronize with the frequency of the external field are determined. Hysteretic transitions between electroconvection regimes are studied. The scenarios of transition to chaotic oscillations are analyzed. Depending on the natural frequency of electroconvective system and the external field frequency, the transition from periodic to chaotic oscillations can occur via quasiperiodicity, a subharmonic cascade, or intermittence

  11. Further evidence for a fluid pathway during bone conduction auditory stimulation.

    Science.gov (United States)

    Sohmer, Haim; Freeman, Sharon

    2004-07-01

    This study was designed to evaluate the suggestion that during bone vibrator stimulation on skull bone (bone conduction auditory stimulation), a major connection between the site of the bone vibrator and the inner ear is a fluid pathway. A series of experiments were conducted on pairs of animals (rats or guinea pigs). The cranial cavities of each pair of animals were coupled by means of a saline filled plastic tube sealed into a craniotomy in the skull of each animal. In response to bone conduction click stimulation to the skull bone of animal I, auditory nerve-brainstem evoked responses could be recorded in animal II. Various procedures showed that these responses were initiated in animal II in response to audio-frequency sound pressures generated within the cranial cavity of animal I by the bone conduction stimulation and transferred to the cranial cavity of animal II through the fluid in the plastic tube: they were not responses to air conducted sounds generated by the bone vibrator, were not induced in animal II by vibrations conveyed to it by the plastic tube and were not electrically conducted activity from animal I. Exposing the fluid in the tube to air was not accompanied by any change in threshold. These experiments confirm that during bone conduction stimulation on the skull, audio-frequency sound pressures (alternating condensations and rarefactions) can be conveyed by a fluid pathway to the cochlea and stimulate it.

  12. One-Dimensional Problem of a Conducting Viscous Fluid with One Relaxation Time

    Directory of Open Access Journals (Sweden)

    Angail A. Samaan

    2011-01-01

    Full Text Available We introduce a magnetohydrodynamic model of boundary-layer equations for conducting viscous fluids. This model is applied to study the effects of free convection currents with thermal relaxation time on the flow of a viscous conducting fluid. The method of the matrix exponential formulation for these equations is introduced. The resulting formulation together with the Laplace transform technique is applied to a variety problems. The effects of a plane distribution of heat sources on the whole and semispace are studied. Numerical results are given and illustrated graphically for the problem.

  13. On Electromagnetic Modulation of Flow Instabilities, Mixing and Heat Transfer in Conducting and Magnetized Fluids

    NARCIS (Netherlands)

    Kenjeres, S.

    2016-01-01

    In the present paper we give a concise review of some recent highlights of our research dealing with electromagnetic control of flow, mixing and heat transfer of electrically conductive or magnetized fluids. We apply a combination of state-of-art numerical (DNS and LES) and experimental (PIV and

  14. A Variable Thermal Conductivity Flow of A Micropolar Fluid Over A ...

    African Journals Online (AJOL)

    We revisited the paper of Mahmoud et al, on the hydromagnetic boundary layer micropolar fluid flow over a stretching surface embedded in a non-Darcian porous medium with radiation.We show that even when the thermal conductivity depends linearly or quadratically on temperature the problem still has a unique solution.

  15. Interstitial hydraulic conductivity and interstitial fluid pressure for avascular or poorly vascularized tumors.

    Science.gov (United States)

    Liu, L J; Schlesinger, M

    2015-09-07

    A correct description of the hydraulic conductivity is essential for determining the actual tumor interstitial fluid pressure (TIFP) distribution. Traditionally, it has been assumed that the hydraulic conductivities both in a tumor and normal tissue are constant, and that a tumor has a much larger interstitial hydraulic conductivity than normal tissue. The abrupt transition of the hydraulic conductivity at the tumor surface leads to non-physical results (the hydraulic conductivity and the slope of the TIFP are not continuous at tumor surface). For the sake of simplicity and the need to represent reality, we focus our analysis on avascular or poorly vascularized tumors, which have a necrosis that is mostly in the center and vascularization that is mostly on the periphery. We suggest that there is an intermediary region between the tumor surface and normal tissue. Through this region, the interstitium (including the structure and composition of solid components and interstitial fluid) transitions from tumor to normal tissue. This process also causes the hydraulic conductivity to do the same. We introduce a continuous variation of the hydraulic conductivity, and show that the interstitial hydraulic conductivity in the intermediary region should be monotonically increasing up to the value of hydraulic conductivity in the normal tissue in order for the model to correspond to the actual TIFP distribution. The value of the hydraulic conductivity at the tumor surface should be the lowest in value. Copyright © 2015 Elsevier Ltd. All rights reserved.

  16. Nonlinear waves in an ultrarelativistic heat-conducting fluid II (Eckart formulation

    Directory of Open Access Journals (Sweden)

    Sebastiano Giambò

    2012-06-01

    Full Text Available In this paper a second-order theory for relativistic heat-conducting fluids is derived in the Eckart scheme, based on the assumption that the entropy 4-current should include quadratic terms in the heat flux. In the special case of ultrarelativistic fluids, the velocities of hydrodynamic and thermal weak discontinuity wave fronts are determined and, through the second-order compatibility conditions, the discontinuities associated to the waves and the transport equations for the amplitude of the discontinuities are found out. Finally, for heat wave, plane, cylindrical and spherical diverging waves are also investigated.

  17. Graphene oxide-loaded shortening as an environmentally friendly heat transfer fluid with high thermal conductivity

    Directory of Open Access Journals (Sweden)

    Vongsetskul Thammasit

    2017-01-01

    Full Text Available Graphene oxide-loaded shortening (GOS, an environmentally friendly heat transfer fluid with high thermal conductivity, was successfully prepared by mixing graphene oxide (GO with a shortening. Scanning electron microscopy revealed that GO particles, prepared by the modified Hummer’s method, dispersed well in the shortening. In addition, the latent heat of GOS decreased while their viscosity and thermal conductivity increased with increasing the amount of loaded GO. The thermal conductivity of the GOS with 4% GO was higher than that of pure shortening of ca. three times, from 0.1751 to 0.6022 W/mK, and increased with increasing temperature. The GOS started to be degraded at ca. 360°C. After being heated and cooled at 100°C for 100 cycles, its viscosity slightly decreased and no chemical degradation was observed. Therefore, the prepared GOS is potentially used as environmentally friendly heat transfer fluid at high temperature.

  18. The effect of functionalized silver nanoparticles over the thermal conductivity of base fluids

    Science.gov (United States)

    Seyhan, Merve; Altan, Cem Levent; Gurten, Berna; Bucak, Seyda

    2017-04-01

    Thermal conductivities of nanofluids are expected to be higher than common heat transfer fluids. The use of metal nanoparticles has not been intensely investigated for heat transfer applications due to lack of stability. Here we present an experimental study on the effect of silver nanoparticles (Ag NPs) which are stabilized with surfactants, on the thermal conductivity of water, ethylene glycol and hexane. Hydrophilic Ag NPs were synthesized in aqueous medium with using gum arabic as surfactant and oleic acid/oleylamine were used to stabilize Ag NPs in the organic phase. The enhancement up to 10 per cent in effective thermal conductivity of hexane and ethylene glycol was achieved with addition of Ag NPs at considerably low concentrations (i.e. 2 and 1 per cent, by weight, for hexane and ethylene glycol respectively). However, almost 10 per cent of deterioration was recorded at effective thermal conductivity of water when Ag NPs were added at 1 per cent (by wt). Considerable amount of Gum Arabic in the medium is shown to be the major contributor to this fall, causing lowering of thermal conductivity of water. Same particles performed much better in ethylene glycol where the stabilizer does not lower the thermal conductivity of the base fluid. Also thermal conductivity of nanofluids was found to be temperature independent except water based Ag nanofluids above a threshold concentration. This temperature dependency is suggested to be due to inhibition of hydrogen bonding among water molecules in the presence of high amounts of gum arabic.

  19. VHBORE: A code to compute borehole fluid conductivity profiles with pressure changes in the borehole

    International Nuclear Information System (INIS)

    Hale, F.V.; Tsang, C.F.

    1994-06-01

    This report describes the code VHBORE which can be used to model fluid electric conductivity profiles in a borehole intersecting fractured rock under conditions of changing pressure in the well bore. Pressure changes may be due to water level variations caused by pumping or fluid density effects as formation fluid is drawn into the borehole. Previous reports describe the method of estimating the hydrologic behavior of fractured rock using a time series of electric conductivity logs and an earlier code, BORE, to generate electric conductivity logs under constant pressure and flow rate conditions. The earlier model, BORE, assumed a constant flow rate, q i , for each inflow into the well bore. In the present code the user supplies the location, constant pressure, h i , transmissivity, T i , and storativity, S i , for each fracture, as well as the initial water level in the well, h w (0), In addition, the input data contains changes in the water level at later times, Δh w (t), typically caused by turning a pump on or off. The variable density calculation also requires input of the density of each of the inflow fluids, ρ i , and the initial uniform density of the well bore fluid, ρ w (0). These parameters are used to compute the flow rate for each inflow point at each time step. The numerical method of Jacob and Lohman (1952) is used to compute the flow rate into or out of the fractures based on the changes in pressure in the wellbore. A dimensionless function relates flow rate as a function of time in response to an imposed pressure change. The principle of superposition is used to determine the net flow rate from a time series of pressure changes. Additional reading on the relationship between drawdown and flow rate can be found in Earlougher (1977), particularly his Section 4.6, open-quotes Constant-Pressure Flow Testingclose quotes

  20. 30 CFR 75.1107-1 - Fire-resistant hydraulic fluids and fire suppression devices on underground equipment.

    Science.gov (United States)

    2010-07-01

    ... 30 Mineral Resources 1 2010-07-01 2010-07-01 false Fire-resistant hydraulic fluids and fire...-UNDERGROUND COAL MINES Fire Protection Fire Suppression Devices and Fire-Resistant Hydraulic Fluids on Underground Equipment § 75.1107-1 Fire-resistant hydraulic fluids and fire suppression devices on underground...

  1. Flow of conductive fluid between parallel disks in an axial magnetic field, (2)

    International Nuclear Information System (INIS)

    Koike, Kazuo; Kamiyama, Shin-ichi

    1981-01-01

    The basic characteristics of the flow in a disc type non-equilibrium MHD power generator were studied. The flow of conductive fluid between parallel disks in an axial magnetic field was analyzed as the subsonic MHD turbulent approach flow of viscous compressible fluid, taking the electron temperature dependence of conductivity into account. The equations for the flow between disks are described by ordinary electromagnetic hydrodynamic approximation. Practical numerical calculation was performed for the non-equilibrium argon plasma seeded with potassium. The effects of the variation of characteristics of non-equilibrium plasma in main flow and boundary layer on the flow characteristics became clear. The qualitative tendency of the properties of MHD generators can be well explained. (Kato, T.)

  2. A code to compute borehole fluid conductivity profiles with multiple feed points

    International Nuclear Information System (INIS)

    Hale, F.V.; Tsang, C.F.

    1988-03-01

    It is of much current interest to determine the flow characteristics of fractures intersecting a wellbore in order to understand the hydrologic behavior of fractured rocks. Often inflow from these fractures into the wellbore is at very low rates. A new procedure has been proposed and a corresponding method of analysis developed to obtain fracture inflow parameters from a time sequence of electric conductivity logs of the borehole fluid. The present report is a companion document to NTB--88-13 giving the details of equations and computer code used to compute borehole fluid conductivity distributions. Verification of the code used and a listing of the code are also given. (author) 9 refs., 5 figs., 7 tabs

  3. Segmentation of plate coupling, fate of subduction fluids, and modes of arc magmatism in Cascadia, inferred from magnetotelluric resistivity

    Science.gov (United States)

    Wannamaker, Philip E.; Evans, Rob L.; Bedrosian, Paul A.; Unsworth, Martyn J.; Maris, Virginie; McGary, R. Shane

    2014-01-01

    Five magnetotelluric (MT) profiles have been acquired across the Cascadia subduction system and transformed using 2-D and 3-D nonlinear inversion to yield electrical resistivity cross sections to depths of ∼200 km. Distinct changes in plate coupling, subduction fluid evolution, and modes of arc magmatism along the length of Cascadia are clearly expressed in the resistivity structure. Relatively high resistivities under the coasts of northern and southern Cascadia correlate with elevated degrees of inferred plate locking, and suggest fluid- and sediment-deficient conditions. In contrast, the north-central Oregon coastal structure is quite conductive from the plate interface to shallow depths offshore, correlating with poor plate locking and the possible presence of subducted sediments. Low-resistivity fluidized zones develop at slab depths of 35–40 km starting ∼100 km west of the arc on all profiles, and are interpreted to represent prograde metamorphic fluid release from the subducting slab. The fluids rise to forearc Moho levels, and sometimes shallower, as the arc is approached. The zones begin close to clusters of low-frequency earthquakes, suggesting fluid controls on the transition to steady sliding. Under the northern and southern Cascadia arc segments, low upper mantle resistivities are consistent with flux melting above the slab plus possible deep convective backarc upwelling toward the arc. In central Cascadia, extensional deformation is interpreted to segregate upper mantle melts leading to underplating and low resistivities at Moho to lower crustal levels below the arc and nearby backarc. The low- to high-temperature mantle wedge transition lies slightly trenchward of the arc.

  4. Design of instantaneous liquid film thickness measurement system for conductive or non-conductive fluid with high viscosity

    Directory of Open Access Journals (Sweden)

    Yongxin Yu

    2017-06-01

    Full Text Available In the paper, a new capacitive sensor with a dielectric film coating was designed to measure the thickness of the liquid film on a flat surface. The measured medium can be conductive or non-conductive fluid with high viscosity such as silicone oil, syrup, CMC solution and melt. With the dielectric film coating, the defects caused by the humidity in a capacitor can be avoided completely. With a excitation frequency 0-20kHz, the static permittivity of capacitive sensor is obtained and stable when small thicknesses are monitored within the frequency of 0-3kHz. Based on the measurement principle, an experimental system was designed and verified including calibration and actual measurement for different liquid film thickness. Experimental results showed that the sensitivity, the resolution, repeatability and linear range of the capacitive sensor are satisfied to the liquid film thickness measurement. Finally, the capacitive measuring system was successfully applied to the water, silicone oil and syrup film thickness measurement.

  5. Stab Resistance of Shear Thickening Fluid (STF)-Kevlar Composites for Body Armor Applications

    National Research Council Canada - National Science Library

    Egres Jr., R. G; Decker, M. J; Halbach, C. J; Lee, Y. S; Kirkwood, J. E; Kirwood, K. M; Wagner, N. J; Wetzel, E. D

    2004-01-01

    The stab resistance of shear thickening fluid (STF)-Kevlar and STF-Nylon fabric composites are investigated and found to exhibit significant improvements over neat fabric targets of equivalent areal density...

  6. Application of multirate flowing fluid electric conductivity logging method to well DH-2, Tono Site, Japan

    Science.gov (United States)

    Doughty, Christine; Takeuchi, Shinji; Amano, Kenji; Shimo, Michito; Tsang, Chin-Fu

    2005-10-01

    In the flowing fluid electric conductivity (FEC) logging method, well bore fluid is replaced with deionized water, following which FEC profiles in the well bore are measured at a series of times while the well is pumped at a constant rate. Locations where fluid enters the well bore show peaks in the FEC logs, which are analyzed to infer inflow strengths and salinities of permeable features intersected by the borehole. In multirate flowing FEC logging, the flowing FEC logging method is repeated using two or more pumping rates. The results, coupled with those of a conventional well test over the entire borehole, enable the transmissivities and inherent pressure heads of permeable features to be determined. Multirate FEC logging is carried out on a deep borehole in fractured granitic rock using three different pumping rates. Results identify 19 hydraulically conducting fractures and indicate that transmissivity, pressure head, and salinity vary significantly among them. Using three pumping rates rather than the minimum number of two permits an internal consistency check on the analysis that provides a measure of the uncertainty of the results. Good comparisons against static FEC profiles and against independent chemical, geological, and hydrogeological data have further enhanced confidence in the results of the multirate flowing FEC logging method.

  7. Unsteady Flow of Reactive Viscous, Heat Generating/Absorbing Fluid with Soret and Variable Thermal Conductivity

    Directory of Open Access Journals (Sweden)

    I. J. Uwanta

    2014-01-01

    Full Text Available This study investigates the unsteady natural convection and mass transfer flow of viscous reactive, heat generating/absorbing fluid in a vertical channel formed by two infinite parallel porous plates having temperature dependent thermal conductivity. The motion of the fluid is induced due to natural convection caused by the reactive property as well as the heat generating/absorbing nature of the fluid. The solutions for unsteady state temperature, concentration, and velocity fields are obtained using semi-implicit finite difference schemes. Perturbation techniques are used to get steady state expressions of velocity, concentration, temperature, skin friction, Nusselt number, and Sherwood number. The effects of various flow parameters such as suction/injection (γ, heat source/sinks (S, Soret number (Sr, variable thermal conductivity δ, Frank-Kamenetskii parameter λ, Prandtl number (Pr, and nondimensional time t on the dynamics are analyzed. The skin friction, heat transfer coefficients, and Sherwood number are graphically presented for a range of values of the said parameters.

  8. Magnetoresistance Behavior of Conducting Filaments in Resistive-Switching NiO with Different Resistance States.

    Science.gov (United States)

    Zhao, Diyang; Qiao, Shuang; Luo, Yuxiang; Chen, Aitian; Zhang, Pengfei; Zheng, Ping; Sun, Zhong; Guo, Minghua; Chiang, Fu-Kuo; Wu, Jian; Luo, Jianlin; Li, Jianqi; Kokado, Satoshi; Wang, Yayu; Zhao, Yonggang

    2017-03-29

    The resistive switching (RS) effect in various materials has attracted much attention due to its interesting physics and potential for applications. NiO is an important system and its RS effect has been generally explained by the formation/rupture of Ni-related conducting filaments. These filaments are unique since they are formed by an electroforming process, so it is interesting to explore their magnetoresistance (MR) behavior, which can also shed light on unsolved issues such as the nature of the filaments and their evolution in the RS process, and this behavior is also important for multifunctional devices. Here, we focus on MR behavior in NiO RS films with different resistance states. Rich and interesting MR behaviors have been observed, including the normal and anomalous anisotropic magnetoresistance and tunneling magnetoresistance, which provide new insights into the nature of the filaments and their evolution in the RS process. First-principles calculation reveals the essential role of oxygen migration into the filaments during the RESET process and can account for the experimental results. Our work provides a new avenue for exploration of the conducting filaments in resistive switching materials and is significant for understanding the mechanism of RS effect and multifunctional devices.

  9. A borehole fluid conductivity logging method for the determination of fracture inflow parameters

    International Nuclear Information System (INIS)

    Tsang, C.F.; Hufschmied, P.

    1988-01-01

    It is of much current interest to determine the flow characteristics of fractures intersecting a wellbore in order to provide data in the estimation of the hydrologic behavior of fractured rocks. In particular the fluid inflow rates from the fractures into the wellbore are important quantities to measure. However often these inflows are at very low rates. In addition very often one finds that only a few percent of the fractures identified by core inspection and geophysical logging are water-conducting fractures, the rest being closed, clogged or isolated from the water flow system. A new method has been developed to locate water-conducting fractures and obtain fracture inflow parameters by means of a time sequence of electric conductivity logs of the borehole fluid. The physical basis of the analysis method is discussed. The procedure is applied to an existing set of data, which shows initiation and growth of nine conductivity peaks in a 900-m section of a 1690-m borehole, corresponding to nine waterconducting fractures intersecting the borehole. We are able to match all nine peaks and determine the flow rates from these fractures. A discussion is given on the applicability of this technique in the context of a borehole testing program. (author) 18 refs., 30 figs., 5 tabs

  10. Transport tensors in perfectly aligned low-density fluids: Self-diffusion and thermal conductivity

    International Nuclear Information System (INIS)

    Singh, G. S.; Kumar, B.

    2001-01-01

    The modified Taxman equation for the kinetic theory of low-density fluids composed of rigid aspherical molecules possessing internal degrees of freedom is generalized to obtain the transport tensors in a fluid of aligned molecules. The theory takes care of the shape of the particles exactly but the solution has been obtained only for the case of perfectly aligned hard spheroids within the framework of the first Sonine polynomial approximation. The expressions for the thermal-conductivity components have been obtained for the first time whereas the self-diffusion components obtained here turn out to be exactly the same as those derived by Kumar and Masters [Mol. Phys. >81, 491 (1994)] through the solution of the Lorentz-Boltzmann equation. All our expressions yield correct results in the hard-sphere limit

  11. A High-Temperature Transient Hot-Wire Thermal Conductivity Apparatus for Fluids

    OpenAIRE

    Perkins, R. A.; Roder, H. M.; Nieto de Castro, C. A.

    1991-01-01

    A new apparatus for measuring both the thermal conductivity and thermal diffusivity of fluids at temperatures from 220 to 775 K at pressures to 70 MPa is described. The instrument is based on the step-power-forced transient hot-wire technique. Two hot wires are arranged in different arms of a Wheatstone bridge such that the response of the shorter compensating wire is subtracted from the response of the primary wire. Both hot wires are 12.7 ?m diameter platinum wire and are simultaneously use...

  12. Supercritical fluid processing: opportunities for new resist materials and processes

    Science.gov (United States)

    Gallagher-Wetmore, Paula M.; Ober, Christopher K.; Gabor, Allen H.; Allen, Robert D.

    1996-05-01

    Over the past two decades supercritical fluids have been utilized as solvents for carrying out separations of materials as diverse as foods, polymers, pharmaceuticals, petrochemicals, natural products, and explosives. More recently they have been used for non-extractive applications such as recrystallization, deposition, impregnation, surface modification, and as a solvent alternative for precision parts cleaning. Today, supercritical fluid extraction is being practiced in the foods and beverage industries; there are commercial plants for decaffeinating coffee and tea, extracting beer flavoring agents from hops, and separating oils and oleoresins from spices. Interest in supercritical fluid processing of polymers has grown over the last ten years, and many new purification, fractionation, and even polymerization techniques have emerged. One of the most significant motivations for applying this technology to polymers has been increased performance demands. More recently, with increasing scrutiny of traditional solvents, supercritical fluids, and in particular carbon dioxide, are receiving widespread attention as 'environmentally conscious' solvents. This paper describes several examples of polymers applications, including a few involving photoresists, which demonstrate that as next- generation advanced polymer systems emerge, supercritical fluids are certain to offer advantages as cutting edge processing tools.

  13. Empirical resistive-force theory for slender biological filaments in shear-thinning fluids.

    Science.gov (United States)

    Riley, Emily E; Lauga, Eric

    2017-06-01

    Many cells exploit the bending or rotation of flagellar filaments in order to self-propel in viscous fluids. While appropriate theoretical modeling is available to capture flagella locomotion in simple, Newtonian fluids, formidable computations are required to address theoretically their locomotion in complex, nonlinear fluids, e.g., mucus. Based on experimental measurements for the motion of rigid rods in non-Newtonian fluids and on the classical Carreau fluid model, we propose empirical extensions of the classical Newtonian resistive-force theory to model the waving of slender filaments in non-Newtonian fluids. By assuming the flow near the flagellum to be locally Newtonian, we propose a self-consistent way to estimate the typical shear rate in the fluid, which we then use to construct correction factors to the Newtonian local drag coefficients. The resulting non-Newtonian resistive-force theory, while empirical, is consistent with the Newtonian limit, and with the experiments. We then use our models to address waving locomotion in non-Newtonian fluids and show that the resulting swimming speeds are systematically lowered, a result which we are able to capture asymptotically and to interpret physically. An application of the models to recent experimental results on the locomotion of Caenorhabditis elegans in polymeric solutions shows reasonable agreement and thus captures the main physics of swimming in shear-thinning fluids.

  14. Empirical resistive-force theory for slender biological filaments in shear-thinning fluids

    Science.gov (United States)

    Riley, Emily E.; Lauga, Eric

    2017-06-01

    Many cells exploit the bending or rotation of flagellar filaments in order to self-propel in viscous fluids. While appropriate theoretical modeling is available to capture flagella locomotion in simple, Newtonian fluids, formidable computations are required to address theoretically their locomotion in complex, nonlinear fluids, e.g., mucus. Based on experimental measurements for the motion of rigid rods in non-Newtonian fluids and on the classical Carreau fluid model, we propose empirical extensions of the classical Newtonian resistive-force theory to model the waving of slender filaments in non-Newtonian fluids. By assuming the flow near the flagellum to be locally Newtonian, we propose a self-consistent way to estimate the typical shear rate in the fluid, which we then use to construct correction factors to the Newtonian local drag coefficients. The resulting non-Newtonian resistive-force theory, while empirical, is consistent with the Newtonian limit, and with the experiments. We then use our models to address waving locomotion in non-Newtonian fluids and show that the resulting swimming speeds are systematically lowered, a result which we are able to capture asymptotically and to interpret physically. An application of the models to recent experimental results on the locomotion of Caenorhabditis elegans in polymeric solutions shows reasonable agreement and thus captures the main physics of swimming in shear-thinning fluids.

  15. Fuel cell assembly fluid flow plate having conductive fibers and rigidizing material therein

    Science.gov (United States)

    Walsh, Michael M.

    2000-01-01

    A fluid flow plate is preferably formed with three initial sections, for instance, two layers of conductive (e.g., metal) fibers and a barrier material (e.g., metal foil) which is interposed between the two layers. For example, sintering of these three sections can provide electrical path(s) between outer faces of the two layers. Then, the sintered sections can be, for instance, placed in a mold for forming of flow channel(s) into one or more of the outer faces. Next, rigidizing material (e.g., resin) can be injected into the mold, for example, to fill and/or seal space(s) about a conductive matrix of the electrical path(s). Preferably, abrading of surface(s) of the outer face(s) serves to expose electrical contact(s) to the electrical path(s).

  16. Fluid simulation of the conduction phase of the plasma erosion opening switch

    International Nuclear Information System (INIS)

    Grossmann, J.M.; Mosher, D.; Ottinger, P.F.

    1987-01-01

    The conduction phase of the plasma erosion openings switch (PEOS) is studied using a 1 1/2-D electromagnetic two-fluid code. The focus of this work is on understanding how two effects, a current-limiting model of electron emission, and the magnetic insulation of electrons at the cathode, determine current conduction in the plasma. Simulations are performed in the parameter regimes of the Gamble I, POP, and PBFA II pulsed power generators, and previous low-density, short-rise time simulations of the PEOS. Fluid code results are compared to a 1-D analytic theory and to the Gamble I and POP experiments. Good agreement between theory and simulation, but mixed agreement between simulation and experiment is found. Experimental Β-field measurements on POP show weaker j x Β compression than the simulation. Current penetration and plasma current channels qualitatively similar to experimental observation are found in the Gamble I regime. However, magnetic insulation of electrons emitted from the cathode bunches the electron flow into narrower current channels than observed experimentally. In several cases, the presence of an electron-scattering or energy-loss mechanism near the cathode must be invoked to overcome magnetic insulation and widen the current channels

  17. Evaluation of fire-resistant fluid lubricants for water reactor coolant pump motors

    International Nuclear Information System (INIS)

    Degueurce, B.

    1995-07-01

    Fires occurred in different reactor coolant pumps, caused by lubricant leakage and impregnation of lagging. The application of phosphate esters in steam turbine control systems eliminated fire hazard. The use of fire resistant fluids for the lubrication of reactor coolant pump motor would eliminate these fires. In 1985, it was decided to evaluate these fluids after 1977 EDF tests' results and 1980 EPRI Reports. Commercially available lubricating fluids were evaluated in the laboratory, using representative tests, to develop data to permit to select a fluid. The recommended fluid has the best results for long-term hydrolysis and showed good radiation tolerance at exposure tests at TRICASTIN power plant. The fluid should now be tests in the actual motor to confirm its properties for the lubrication of reactor coolant pumps. (author). 11 refs., 2 figs., 3 tabs

  18. Standard test method for conducting potentiodynamic polarization resistance measurements

    CERN Document Server

    American Society for Testing and Materials. Philadelphia

    1997-01-01

    1.1 This test method covers an experimental procedure for polarization resistance measurements which can be used for the calibration of equipment and verification of experimental technique. The test method can provide reproducible corrosion potentials and potentiodynamic polarization resistance measurements. 1.2 The values stated in SI units are to be regarded as standard. No other units of measurement are included in this standard. 1.3 This standard does not purport to address all of the safety concerns, if any, associated with its use. It is the responsibility of the user of this standard to establish appropriate safety and health practices and determine the applicability of regulatory limitations prior to use.

  19. Decoupling ion conductivity and fluid permeation through optimizing hydrophilic channel morphology

    Energy Technology Data Exchange (ETDEWEB)

    Chu, Peter Po-Jen, E-mail: pjchu@cc.ncu.edu.tw; Fang, Yu-Shin; Tseng, Yu-Chen [Department of Chemistry, National Central University, No. 300, Jhongda Rd., Jhongli City, Taoyuan County 32001, Taiwan (R.O.C.) (China)

    2016-05-18

    Approaches to improve membrane ion conductivity usually leads to higher degree of swelling, more serious fuel cross-over and often sacrificed membrane mechanical strength. Preserving all three main membrane properties is a tough challenge in searching high ion conducting fuel cell membrane. The long standing dilemma is resolved by decoupling ion conduction and fluid permeation property by creating optimized channel morphology using external electric field poling. Success of this approach is demonstrated in the proton conducting membrane composed of poly(ether sulfones) (PES) and sulfonated poly(ether ether ketone) (sPEEK, degree of sulfonation=50%) composites prepared under electric field poling condition. The external field enhanced the aromatic chain ordering from both sPEEK and PES and improved the miscibility. This induced interaction is conducive to the formation of more densely packed amorphous domains that eventually leads to preferentially ordered hydrophilic proton conducting channels having a average dimension (3 nm) smaller than that in generic sPEEK or Nafion. The narrower but more ordered channel displayed much lower methanol permeability (3.17×10{sup −7} cm{sup 2}/s), and lower swelling ratio (31.20%), while the conductivity (~10{sup −1} S/cm) is higher than that of Nafion, or sPEEK at higher (64%) degree of sulfonation. The composite is chemically stable and highly durable with improved membrane mechanical strength. Nearly 50% increase of DMFC power output is observed using this membrane, and the best power density is recorded at 155 mA/cm{sup 2} (80 °C, 1M Methanol).

  20. Evaluation of water based intelligent fluids for resist stripping in single wafer cleaning tools

    Science.gov (United States)

    Rudolph, Matthias; Esche, Silvio; Hohle, Christoph; Schumann, Dirk; Steinke, Philipp; Thrun, Xaver; von Sonntag, Justus

    2016-03-01

    The application of phasefluid based intelligent fluids® in the field of photoresist stripping was studied. Due to their highly dynamic inner structure, phasefluids penetrate into the polymer network of photoresists and small gaps between resist layer and substrate and lift off the material from the surface. These non-aggressive stripping fluids were investigated regarding their efficiency in various resist stripping applications including initial results on copper metallization. Furthermore intelligent fluids® have been evaluated on an industry standard high volume single wafer cleaner. A baseline process on 300 mm wafers has been developed and characterized in terms of metallic and ionic impurities and defect level. Finally a general proof of concept for removal of positive tone resist from 300 mm silicon wafers is demonstrated.

  1. Three-Dimensional Printing of Highly Conductive Carbon Nanotube Microarchitectures with Fluid Ink.

    Science.gov (United States)

    Kim, Jung Hyun; Lee, Sanghyeon; Wajahat, Muhammad; Jeong, Hwakyung; Chang, Won Suk; Jeong, Hee Jin; Yang, Jong-Ryul; Kim, Ji Tae; Seol, Seung Kwon

    2016-09-27

    Moving printed electronics to three dimensions essentially requires advanced additive manufacturing techniques yielding multifunctionality materials and high spatial resolution. Here, we report the meniscus-guided 3D printing of highly conductive multiwall carbon nanotube (MWNT) microarchitectures that exploit rapid solidification of a fluid ink meniscus formed by pulling a micronozzle. To achieve high-quality printing with continuous ink flow through a confined nozzle geometry, that is, without agglomeration and nozzle clogging, we design a polyvinylpyrrolidone-wrapped MWNT ink with uniform dispersion and appropriate rheological properties. The developed technique can produce various desired 3D microstructures, with a high MWNT concentration of up to 75 wt % being obtained via post-thermal treatment. Successful demonstrations of electronic components such as sensing transducers, emitters, and radio frequency inductors are also described herein. We expect that the technique presented in this study will facilitate selection of diverse materials in 3D printing and enhance the freedom of integration for advanced conceptual devices.

  2. Effect of Cattaneo-Christov heat flux on Jeffrey fluid flow with variable thermal conductivity

    Science.gov (United States)

    Hayat, Tasawar; Javed, Mehwish; Imtiaz, Maria; Alsaedi, Ahmed

    2018-03-01

    This paper presents the study of Jeffrey fluid flow by a rotating disk with variable thickness. Energy equation is constructed by using Cattaneo-Christov heat flux model with variable thermal conductivity. A system of equations governing the model is obtained by applying boundary layer approximation. Resulting nonlinear partial differential system is transformed to ordinary differential system. Homotopy concept leads to the convergent solutions development. Graphical analysis for velocities and temperature is made to examine the influence of different involved parameters. Thermal relaxation time parameter signifies that temperature for Fourier's heat law is more than Cattaneo-Christov heat flux. A constitutional analysis is made for skin friction coefficient and heat transfer rate. Effects of Prandtl number on temperature distribution and heat transfer rate are scrutinized. It is observed that larger Reynolds number gives illustrious temperature distribution.

  3. The application of moment methods to the analysis of fluid electrical conductivity logs in boreholes

    International Nuclear Information System (INIS)

    Loew, S.; Tsang, Chin-Fu; Hale, F.V.; Hufschmied, P.

    1990-08-01

    This report is one of a series documenting the results of the Nagra-DOE Cooperative (NDC-I) research program in which the cooperating scientists explore the geological, geophysical, hydrological, geochemical, and structural effects anticipated from the use of a rock mass as a geologic repository for nuclear waste. Previous reports have presented a procedure for analyzing a time sequence of wellbore electric conductivity logs in order to obtain outflow parameters of fractures intercepted by the borehole, and a code, called BORE, used to simulate borehole fluid conductivity profiles given these parameters. The present report describes three new direct (not iterative) methods for analyzing a short time series of electric conductivity logs based on moment quantities of the individual outflow peaks and applies them to synthetic as well as to field data. The results of the methods discussed show promising results and are discussed in terms of their respective advantages and limitations. In particular it is shown that one of these methods, the so-called ''Partial Moment Method,'' is capable of reproducing packer test results from field experiments in the Leuggern deep well within a factor of three, which is below the range of what is recognized as the precision of packer tests themselves. Furthermore the new method is much quicker than the previously used iterative fitting procedure and is even capable of handling transient fracture outflow conditions. 20 refs., 11 figs., 10 tabs

  4. Estimation of penetration resistance and hydraulic conductivity of ...

    African Journals Online (AJOL)

    The PR was measured by Bush recording penetrometer, while hydraulic conductivity was determined by using Decagon mini disk infiltrometer. Soil analysis according to the USDA textural classification showed the texture of the soil was a sandy clay loam in nine out of the ten locations sampled and sandy clay at the ...

  5. Corrosion-resistant, electrically-conductive plate for use in a fuel cell stack

    Science.gov (United States)

    Carter, J David [Bolingbrook, IL; Mawdsley, Jennifer R [Woodridge, IL; Niyogi, Suhas [Woodridge, IL; Wang, Xiaoping [Naperville, IL; Cruse, Terry [Lisle, IL; Santos, Lilia [Lombard, IL

    2010-04-20

    A corrosion resistant, electrically-conductive, durable plate at least partially coated with an anchor coating and a corrosion resistant coating. The corrosion resistant coating made of at least a polymer and a plurality of corrosion resistant particles each having a surface area between about 1-20 m.sup.2/g and a diameter less than about 10 microns. Preferably, the plate is used as a bipolar plate in a proton exchange membrane (PEMFC) fuel cell stack.

  6. A laboratory study of the correlation between the thermal conductivity and electrical resistivity of soil

    Science.gov (United States)

    Wang, Jie; Zhang, Xiaopei; Du, Lizhi

    2017-10-01

    Thermal conductivity k (Wm- 1 K- 1) and electrical resistivity ρ (Ω·m) depend on common parameters such as grain size, dry density and saturation, allowing the finding of a relationship between both parameters. In this paper, we found a linear quantitative formula between thermal conductivity and electrical resistivity of soil. To accomplish this, we measured the thermal conductivity and electrical resistivity of 57 soil samples in the laboratory; samples included 8 reconstructed soils from the Changchun area (clay, silt, and sand) with approximately 7 different saturation levels. A linear relationship between thermal conductivity and electrical resistivity was found excluding the parameter of soil saturation, and the linear model was validated with undisturbed soils in Changchun area. To fully use this relationship (e.g., by imaging the thermal conductivity of soils with electrical resistivity tomography), further measurements with different soils are needed.

  7. Numerical Study of Thermo-Fluid Features of Electrically Conducting Fluids in Tube Bank Heat Exchangers Exposed to Uniform Magnetic Fields

    Energy Technology Data Exchange (ETDEWEB)

    Oh, Jin Ho; Kang, Namcheol [Kyungpook Nat’l Univ., Daegu (Korea, Republic of)

    2017-10-15

    When an electrically conducting fluid flows through a staggered tube bank, the heat transfer and fluid flow features are changed by the externally introduced magnetic field. This study provides a numerical investigation of this phenomenon. Heat and fluid flows are investigated for unsteady laminar flows at Reynolds numbers of 50 and 100 with the Hartmann number gradually increasing from zero to 100. As the Hartmann number increases, and owing to the effects of the introduced magnetic field, the velocity boundary layer near the tube wall is thinned, the flow separation is delayed downstream, and the shrinkage of a recirculation zone formed near the rear side is observed. Based on these thermo-fluid deformations, the resulting changes in the local and average Nusselt number are investigated.

  8. Heat transfer from a particle in creeping flow of a variable-conductivity fluid

    Science.gov (United States)

    Dehdashti, Esmaeil; Razizadeh, Meghdad; Masoud, Hassan

    2017-11-01

    We revisit the classical problem of heat transfer from a single particle in a uniform Stokes flow with the assumption that the fluid conductivity changes linearly with the temperature. We use a combination of asymptotic analysis and numerical simulation to derive semi-analytical expressions for the dimensionless heat transfer coefficient, i.e. Nusselt number (Nu), of spheroidal particles. The results cover the entire range of Peclet number (Pe). We find that, for a constant temperature boundary condition and fixed geometry, the Nusselt number is essentially equal to the product of two terms, one of which is only a function of Pe while the other one is nearly independent of Pe and mainly depends on the proportionality constant of the conductivity-temperature relation. We also show that, in contrast, when a uniform heat flux is imposed on the surface of the particle, Nu can be written as a summation of a Pe dependent piece and one that solely varies with the proportionality constant. Finally, we discuss the extension of these results to non-spheroidal particles and to finite-Reynolds-number flows.

  9. Quantification of nasal airflow resistance in English bulldogs using computed tomography and computational fluid dynamics.

    Science.gov (United States)

    Hostnik, Eric T; Scansen, Brian A; Zielinski, Rachel; Ghadiali, Samir N

    2017-09-01

    Stenotic nares, edematous intranasal turbinates, mucosal swelling, and an elongated, thickened soft palate are common sources of airflow resistance for dogs with brachycephalic airway syndrome. Surgery has focused on enlarging the nasal apertures and reducing tissue of the soft palate. However, objective measures of surgical efficacy are lacking. Twenty-one English bulldogs without previous surgery were recruited for this prospective, pilot study. Computed tomography was performed using conscious sedation and without endotracheal intubation using a 128 multidetector computed tomography scanner. Raw multidetector computed tomography data were rendered to create a three-dimensional surface mesh model by automatic segmentation of the air-filled nasal passage from the nares to the caudal soft palate. Three-dimensional surface models were used to construct computational fluid dynamics models of nasal airflow resistance from the nares to the caudal aspect of the soft palate. The computational fluid dynamics models were used to simulate airflow in each dog and airway resistance varied widely with a median 36.46 (Pa/mm)/(l/s) and an interquartile range of 19.84 to 90.74 (Pa/mm)/(/s). In 19/21 dogs, the rostral third of the nasal passage exhibited a larger airflow resistance than the caudal and middle regions of the nasal passage. In addition, computational fluid dynamics data indicated that overall measures of airflow resistance may significantly underestimate the maximum local resistance. We conclude that computational fluid dynamics models derived from nasal multidetector computed tomography can quantify airway resistance in brachycephalic dogs. This methodology represents a novel approach to noninvasively quantify airflow resistance and may have utility for objectively studying effects of surgical interventions in canine brachycephalic airway syndrome. © 2017 American College of Veterinary Radiology.

  10. Multidrug resistant tuberculosis diagnosed by synovial fluid analysis

    Directory of Open Access Journals (Sweden)

    M. van Zeller

    2012-09-01

    Full Text Available Tuberculosis remains a major public health problem worldwide. HIV co-infection is contributing to an increased incidence of the disease, particularly that caused by multidrug resistant strains of Mycobacterium tuberculosis (MT. We describe an HIV-infected patient with pleural and lymph node tuberculosis diagnosed by pleural effusion characteristics and biopsy specimens, without MT identification, that further presented with knee-joint involvement. Arthrocentesis allowed MT isolation and drug susceptibility testing, resulting in a diagnosis of multidrug-resistant tuberculosis and an appropriate treatment regimen.MT identification and drug susceptibility tests are very important, especially for HIV co-infected patients. Resumo: A tuberculose constitui um importante problema de saúde pública mundial. A co-infecção pelo HIV contribui para o aumento da incidência da doença e em particular a causada por estirpes de Mycobacterium tuberculosis (MT multirresistentes. Os autores descrevem um doente HIV-positivo com tuberculose pleural e ganglionar diagnosticada pelas características bioquímicas do líquido pleural e resultados anatomo-patológicos de biopsias mas sem identificação do agente, que posteriormente apresentou envolvimento do joelho. A artrocentese do joelho permitiu o isolamento do MT e a realização de teste de sensibilidade possibilitando o diagnóstico de tuberculose multirresistente e a instituição de um esquema terapêutico adequado.A identificação do MT e a realização de testes de sensibilidade são muito importantes, especialmente em doentes com co-infecção por HIV. Keywords: Multidrug resistant tuberculosis, Drug susceptibility test, HIV, Palavras-chave: Tuberculose multirresistente, Teste de sensibilidade aos antimicrobiana, Infecção VIH

  11. Thermal conductivity enhancement and sedimentation reduction of magnetorheological fluids with nano-sized Cu and Al additives

    Science.gov (United States)

    Rahim, M. S. A.; Ismail, I.; Choi, S. B.; Azmi, W. H.; Aqida, S. N.

    2017-11-01

    This work presents enhanced material characteristics of smart magnetorheological (MR) fluids by utilizing nano-sized metal particles. Especially, enhancement of thermal conductivity and reduction of sedimentation rate of MR fluids those are crucial properties for applications of MR fluids are focussed. In order to achieve this goal, a series of MR fluid samples are prepared using carbonyl iron particles (CIP) and hydraulic oil, and adding nano-sized particles of copper (Cu), aluminium (Al), and fumed silica (SiO2). Subsequently, the thermal conductivity is measured by the thermal property analyser and the sedimentation of MR fluids is measured using glass tubes without any excitation for a long time. The measured thermal conductivity is then compared with theoretical models such as Maxwell model at various CIP concentrations. In addition, in order to show the effectiveness of MR fluids synthesized in this work, the thermal conductivity of MRF-132DG which is commercially available is measured and compared with those of the prepared samples. It is observed that the thermal conductivity of the samples is much better than MRF-132DG showing the 148% increment with 40 vol% of the magnetic particles. It is also observed that the sedimentation rate of the prepared MR fluid samples is less than that of MRF-132DG showing 9% reduction with 40 vol% of the magnetic particles. The mixture optimized sample with high conductivity and low sedimentation was also obtained. The magnetization of the sample recorded an enhancement of 70.5% when compared to MRF-132DG. Furthermore, the shear yield stress of the sample were also increased with and without the influence of magnetic field.

  12. Investigation of film flow of a conducting fluid in a transverse magnetic field, (1)

    International Nuclear Information System (INIS)

    Oshima, Shuzo; Yamane, Ryuichiro; Mochimaru, Yoshihiro; Sudo, Kouzo.

    1985-01-01

    Accompanying the development of large electromagnetic pumps transporting liquid metals used as the heat transfer media for nuclear power plants and the electromagnetic flow meters of large capacity, many researches have been carried out on the flow of liquid metals under the action of magnetic field. The utilization of electromagnetic force for continuous casting facilities seems very effective for the total processes from refining to solidification. Hereafter, it will be a technologically important problem to clarify the behavior of electro-conductive fluid with free surface under the action of magnetic field concerning the non-contact control of the interface form of molten metals as well as the cooling problem in nuclear fusion reactors. In this study, first the flow phenomena of MHD liquid film flow in a magnetic field with intensity gradient was analytically examined, and the effect of magnetic field gradient exerted on liquid film thickness and liquid surface form was clarified. Next, the experiment using mercury was carried out. For liquid film flow, magnetic field gradient acted as a kind of non-contact weir. (Kako, I.)

  13. Proteomic analysis of apoplastic fluid of Coffea arabica leaves highlights novel biomarkers for resistance against Hemileia vastatrix

    Directory of Open Access Journals (Sweden)

    Leonor eGuerra-Guimarães

    2015-06-01

    Full Text Available A proteomic analysis of the apoplastic fluid (APF of coffee leaves was conducted to investigate the cellular processes associated with incompatible (resistant and compatible (susceptible Coffea arabica-Hemileia vastatrix interactions, during the 24-96 hai period. The APF proteins were extracted by leaf vacuum infiltration and protein profiles were obtained by 2-DE. The comparative analysis of the gels revealed 210 polypeptide spots whose volume changed in abundance between samples (control, resistant and susceptible during the 24-96 hai period. The proteins identified were involved mainly in protein degradation, cell wall metabolism and stress/defense responses, most of them being hydrolases (around 70%, particularly sugar hydrolases and peptidases/proteases. The changes in the APF proteome along the infection process revealed two distinct phases of defense responses, an initial/basal one (24-48 hai and a late/specific one (72-96 hai. Compared to susceptibility, resistance was associated with a higher number of proteins, which was more evident in the late/specific phase. Proteins involved in the resistance response were mainly, glycohydrolases of the cell wall, serine proteases and pathogen related-like proteins (PR-proteins, suggesting that some of these proteins could be putative candidates for resistant markers of coffee to H. vastatrix. Antibodies were produced against chitinase, pectin methylesterase, serine carboxypeptidase, reticuline oxidase and subtilase and by an immunodetection assay it was observed an increase of these proteins in the resistant sample. With this methodology we have identified proteins that are candidate markers of resistance and that will be useful in coffee breeding programs to assist in the selection of cultivars with resistance to H. vastatrix.

  14. Thermal convection in a magnetized conducting fluid with the Cattaneo-Christov heat-flow model

    Science.gov (United States)

    Bissell, J. J.

    2016-11-01

    By substituting the Cattaneo-Christov heat-flow model for the more usual parabolic Fourier law, we consider the impact of hyperbolic heat-flow effects on thermal convection in the classic problem of a magnetized conducting fluid layer heated from below. For stationary convection, the system is equivalent to that studied by Chandrasekhar (Hydrodynamic and Hydromagnetic Stability, 1961), and with free boundary conditions we recover the classical critical Rayleigh number Rc(c )(Q ) which exhibits inhibition of convection by the field according to Rc(c )→π2Q as Q →∞ , where Q is the Chandrasekhar number. However, for oscillatory convection we find that the critical Rayleigh number Rc(o )(Q ,P1,P2,C ) is given by a more complicated function of the thermal Prandtl number P1, magnetic Prandtl number P2 and Cattaneo number C. To elucidate features of this dependence, we neglect P2 (in which case overstability would be classically forbidden), and thereby obtain an expression for the Rayleigh number that is far less strongly inhibited by the field, with limiting behaviour Rc(o )→π √{Q }/ C , as Q →∞ . One consequence of this weaker dependence is that onset of instability occurs as overstability provided C exceeds a threshold value CT(Q); indeed, crucially we show that when Q is large, CT∝1 / √{Q }, meaning that oscillatory modes are preferred even when C itself is small. Similar behaviour is demonstrated in the case of fixed boundaries by means of a novel numerical solution.

  15. On the motion of several rigid bodies in an incompressible non-Newtonian and heat-conducting fluid

    Czech Academy of Sciences Publication Activity Database

    Nečasová, Šárka

    2009-01-01

    Roč. 55, - (2009), s. 325-352 ISSN 0430-3202 R&D Projects: GA AV ČR IAA100190804 Institutional research plan: CEZ:AV0Z10190503 Keywords : Non-Newtonian fluid * heat conductivity * several rigid bodies * global weak solutions * no collisions in finite time Subject RIV: BA - General Mathematics

  16. Conducting mechanism of Ag-diffused Bi-Te based resistive switching devices

    Science.gov (United States)

    Liu, N.; Yan, P.; Li, Y.; Lu, K.; Sun, H. J.; Ji, H. K.; Xue, K. H.; Miao, X. S.

    2018-02-01

    The forming-free resistive switching (RS) and conducting mechanism of Ag-diffused BiTe chalcogenide thin film has been investigated. The mutual diffusion of Ag, Bi and Te elements at the interface is proved to suppress the crystallization of the as-deposited BiTe film. The amorphization of BiTe and the Schottky barrier between Ag and BiTe contribute to high resistance state (HRS) of the switching devices. When switched to low resistance state (LRS), the coexistence of metallic conduction and variable-range hopping is found to be the dominant conduction mechanism. The temperature dependence of LRS exhibits an interesting transport behavior, so that a positive temperature coefficient becomes a negative one at 24 K. Our results help to further understand the conduction mechanism and promote the design for future nonvolatile memory applications.

  17. The Resistive Switching Characteristics in ZrO2 and Its Filamentary Conduction Behavior

    Directory of Open Access Journals (Sweden)

    Chun-Hung Lai

    2016-07-01

    Full Text Available This study investigated the conduction properties of sputtered ZrO2 exhibiting reversible and stable resistance change. Similar current distributions in on/off conduction and set/reset switching were observed in top electrodes with a diameter of 150, 250, and 350 µm. The size independence of current magnitude implied the presence of an uneven filamentary path over the electrode area. Increased current compliance was imposed on the turn-on process, and the observed increase in on-state current and turn-off threshold was attributed to incremental filament diameter. Variations in current conduction and resistance switching were analyzed by monitoring sweeping bias limits in both positive and negative polarities. These experimental observations were interpreted based on the aspect ratio of channels comprising conductive and oxidized filament portions, thereby elucidating the characteristics of filamentary resistive switching.

  18. Interpretation of Epithelial Lining Fluid Concentrations of Antibiotics against Methicillin Resistant Staphylococcus aureus

    OpenAIRE

    Kiem, Sungmin; Schentag, Jerome J

    2014-01-01

    Although antibiotics whose epithelial lining fluid (ELF) concentrations are reported high tend to be preferred in treatment of pneumonia, measurement of ELF concentrations of antibiotics could be misled by contamination from lysis of ELF cells and technical errors of bronchoalveolar lavage (BAL). In this review, ELF concentrations of anti-methicillin resistant Staphylococcus aureus (MRSA) antibiotics were interpreted considering above confounding factors. An equation used to explain antibioti...

  19. Low-power resistive random access memory by confining the formation of conducting filaments

    International Nuclear Information System (INIS)

    Huang, Yi-Jen; Lee, Si-Chen; Shen, Tzu-Hsien; Lee, Lan-Hsuan; Wen, Cheng-Yen

    2016-01-01

    Owing to their small physical size and low power consumption, resistive random access memory (RRAM) devices are potential for future memory and logic applications in microelectronics. In this study, a new resistive switching material structure, TiO x /silver nanoparticles/TiO x /AlTiO x , fabricated between the fluorine-doped tin oxide bottom electrode and the indium tin oxide top electrode is demonstrated. The device exhibits excellent memory performances, such as low operation voltage (<±1 V), low operation power, small variation in resistance, reliable data retention, and a large memory window. The current-voltage measurement shows that the conducting mechanism in the device at the high resistance state is via electron hopping between oxygen vacancies in the resistive switching material. When the device is switched to the low resistance state, conducting filaments are formed in the resistive switching material as a result of accumulation of oxygen vacancies. The bottom AlTiO x layer in the device structure limits the formation of conducting filaments; therefore, the current and power consumption of device operation are significantly reduced.

  20. Functional resistance of enamel and the phenomenon of transtegumental fluid transport

    Directory of Open Access Journals (Sweden)

    Okushko V.R. Okushko R.V. Ursan R.V.

    2011-03-01

    Full Text Available Current data related to transport of fluid through the covering tissue formations (skin, nail plate, dental enamel, gum valley are being analyzed. A supposition is made of transtegumental fluid transport (TFT as a general biological regularity which is specifically manifested in tissues of different functional purposes. Depending on the peculiarity of the organ, the tooth performs the TFT providing functional resistance of the enamel, whose level is clinically detected in the «test of enamel resistance» (TER used in modern research. The article draws attention to the reasonability of an in-depth study of the tooth physiology, where the central element is TFT. This phenomenon is of interest both from fundamental and highly practical standpoints. Identification of seasonal periods in the functional resistance decline makes it possible to get a distinct effect by means of concentrating prevention efforts on this. The TER sample, as well as other transtegumental fluid transport patterns, is to find place in the system of personalized predictive approach to caries diseases

  1. On flow of electrically conducting fluids over a flat plate in the presence of a transverse magnetic field

    Science.gov (United States)

    Rossow, Vernon J

    1958-01-01

    The use of a magnetic field to control the motion of electrically conducting fluids is studied. The incompressible boundary-layer solutions are found for flow over a flat plate when the magnetic field is fixed relative to the plate or to the fluid. The equations are integrated numerically for the effect of the transverse magnetic field on the velocity and temperature profiles, and hence, the skin friction and rate of heat transfer. It is concluded that the skin friction and the heat-transfer rate are reduced when the transverse magnetic field is fixed relative to the plate and increased when fixed relative to the fluid. The total drag is increased in all of the areas.

  2. Three-fluid, three-dimensional magnetohydrodynamic solar wind model with eddy viscosity and turbulent resistivity

    Energy Technology Data Exchange (ETDEWEB)

    Usmanov, Arcadi V.; Matthaeus, William H. [Department of Physics and Astronomy, University of Delaware, Newark, DE 19716 (United States); Goldstein, Melvyn L., E-mail: arcadi.usmanov@nasa.gov [Code 672, NASA Goddard Space Flight Center, Greenbelt, MD 20771 (United States)

    2014-06-10

    We have developed a three-fluid, three-dimensional magnetohydrodynamic solar wind model that incorporates turbulence transport, eddy viscosity, turbulent resistivity, and turbulent heating. The solar wind plasma is described as a system of co-moving solar wind protons, electrons, and interstellar pickup protons, with separate energy equations for each species. Numerical steady-state solutions of Reynolds-averaged solar wind equations coupled with turbulence transport equations for turbulence energy, cross helicity, and correlation length are obtained by the time relaxation method in the corotating with the Sun frame of reference in the region from 0.3 to 100 AU (but still inside the termination shock). The model equations include the effects of electron heat conduction, Coulomb collisions, photoionization of interstellar hydrogen atoms and their charge exchange with the solar wind protons, turbulence energy generation by pickup protons, and turbulent heating of solar wind protons and electrons. The turbulence transport model is based on the Reynolds decomposition and turbulence phenomenologies that describe the conversion of fluctuation energy into heat due to a turbulent cascade. In addition to using separate energy equations for the solar wind protons and electrons, a significant improvement over our previous work is that the turbulence model now uses an eddy viscosity approximation for the Reynolds stress tensor and the mean turbulent electric field. The approximation allows the turbulence model to account for driving of turbulence by large-scale velocity gradients. Using either a dipole approximation for the solar magnetic field or synoptic solar magnetograms from the Wilcox Solar Observatory for assigning boundary conditions at the coronal base, we apply the model to study the global structure of the solar wind and its three-dimensional properties, including embedded turbulence, heating, and acceleration throughout the heliosphere. The model results are

  3. Comparative study of Eyring and Carreau fluids in a suspension of dust and nickel nanoparticles with variable conductivity

    Science.gov (United States)

    Mamatha Upadhya, S.; Mahesha; Raju, C. S. K.

    2018-04-01

    A theoretical analysis is carried out to investigate the magnetohydrodynamic unsteady flow of Eyring-Powell and Carreau non-Newtonian fluids in a suspension of dust and nickel nanoparticles by considering variable thermal conductivity and thermal radiation. Dispersion of nickel nanoparticles in dusty fluids finds applications in heat exchanger systems, rechargeable batteries, chemical catalysts, metallurgy, conducting paints, magnetic recording media, drug delivery, nanofibers, textiles, etc. The initially arising set of physical governing partial differential equations is transformed to ordinary differential equations (ODEs) with the aid of similarity transformations. Consequentially, the nonlinear ODEs are solved numerically through the Runge-Kutta Fehlberg scheme (RKFS). The computational results for non-dimensional temperature and velocity profiles are presented through graphs. Furthermore, the numerical values of friction factor and heat transfer rate are tabulated numerically for the unsteady and steady cases of the Eyring and Carreau fluid cases and of the dusty non-Newtonian (φ=0) and the dusty non-Newtonian nanofluid (φ≠ 0) cases of the unsteady flow. We also validated the present results with previous published studies and found them to be highly satisfactory. The formulated model reveals that the rate of heat transfer is higher in the mixture of the nickel + Eyring-Powell case compared to the nickel + Carreau case. From this we can highlight that, depending on the industrial appliances, we can use heating or cooling processes for Eyring and Carreau fluids, respectively.

  4. Conduction-only transport phenomena in compressible bivelocity fluids: diffuse interfaces and Korteweg stresses.

    Science.gov (United States)

    Brenner, Howard

    2014-04-01

    "Diffuse interface" theories for single-component fluids—dating back to van der Waals, Korteweg, Cahn-Hilliard, and many others—are currently based upon an ad hoc combination of thermodynamic principles (built largely upon Helmholtz's free-energy potential) and so-called “nonclassical” continuum-thermomechanical principles (built largely upon Newtonian mechanics), with the latter originating with the pioneering work of Dunn and Serrin [Arch. Ration. Mech. Anal. 88, 95 (1985)]. By introducing into the equation governing the transport of energy the notion of an interstitial work-flux contribution, above and beyond the usual Fourier heat-flux contribution, namely, jq = -k∇T, to the energy flux, Dunn and Serrin provided a rational continuum-thermomechanical basis for the presence of Korteweg stresses in the equation governing the transport of linear momentum in compressible fluids. Nevertheless, by their failing to recognize the existence and fundamental need for an independent volume transport equation [Brenner, Physica A 349, 11 (2005)]—especially for the roles played therein by the diffuse volume flux j v and the rate of production of volume πν at a point of the fluid continuum—we argue that diffuse interface theories for fluids stand today as being both ad hoc and incomplete owing to their failure to recognize the need for an independent volume transport equation for the case of compressible fluids. In contrast, we point out that bivelocity hydrodynamics, as it already exists [Brenner, Phys. Rev. E 86, 016307 (2012)], provides a rational, non-ad hoc, and comprehensive theory of diffuse interfaces, not only for single-component fluids, but also for certain classes of crystalline solids [Danielewski and Wierzba, J. Phase Equilib. Diffus. 26, 573 (2005)]. Furthermore, we provide not only what we believe to be the correct constitutive equation for the Korteweg stress in the class of fluids that are constitutively Newtonian in their rheological response

  5. A solution for the Graetz problem in parallel plates, with axial heat conduction in the fluid and in the wall

    International Nuclear Information System (INIS)

    Biage, M.

    1983-04-01

    A heat transfer problem in parallel plates with infinite with has been solved, with axial heat conduction in the fluid and in the wall, considering steady-state laminar flow for a Newtonian fluid and a fully developed velocity profile. The duct consists of an infinite inicial part, insulated on both plates, an intermediale part of finite length, with a prescribed heat flux in the upper plate and insulated on the botton plate, and by another infinite part also insulated on both plates. The problem has been solved by a numerical combination of the integral equation method and the variational method. Both, the performance of the numerical technique employed and results obtained are analyzed in this work. It is demostrated that the heat conduction in the wall significantly modifies the heat transfer parameters. (Author) [pt

  6. Deformation of the free surface of a conducting fluid in the magnetic field of current-carrying linear conductors

    Energy Technology Data Exchange (ETDEWEB)

    Zubarev, N.M. [Institute of Electrophysics, UB RAS, Ekaterinburg (Russian Federation); P.N. Lebedev Physical Institute, RAS, Moscow (Russian Federation); Zubareva, O.V., E-mail: olga@iep.uran.ru [Institute of Electrophysics, UB RAS, Ekaterinburg (Russian Federation)

    2017-06-01

    The magnetic shaping problem is studied for the situation where a cylindrical column of a perfectly conducting fluid is deformed by the magnetic field of a system of linear current-carrying conductors. Equilibrium is achieved due to the balance of capillary and magnetic pressures. Two two-parametric families of exact solutions of the problem are obtained with the help of conformal mapping technique. In accordance with them, the column essentially deforms in the cross section up to its disintegration.

  7. Stabilizing effect of gas conductivity evolution on the resistive sausage mode of a propagating beam

    International Nuclear Information System (INIS)

    Lampe, M.; Joyce, G.

    1983-01-01

    Previous theoretical work has shown that a highly current-neutralized charged particle beam propagating in a preionized plasma channel of fixed conductivity is subject to a resistive sausage instability. It is shown that the instability is stabilized, for the case of beam propagation into an initially un-ionized gas, when the effect of beam-collisional ionization on the gas conductivity is modeled fully self-consistently

  8. Borehole Heat Exchanger Systems: Hydraulic Conductivity and Frost-Resistance of Backfill Materials

    Science.gov (United States)

    Anbergen, Hauke; Sass, Ingo

    2016-04-01

    Ground source heat pump (GSHP) systems are economic solutions for both, domestic heating energy supply, as well as underground thermal energy storage (UTES). Over the past decades the technology developed to complex, advanced and highly efficient systems. For an efficient operation of the most common type of UTES, borehole heat exchanger (BHE) systems, it is necessary to design the system for a wide range of carrier fluid temperatures. During heat extraction, a cooled carrier fluid is heated up by geothermal energy. This collected thermal energy is energetically used by the heat pump. Thereby the carrier fluid temperature must have a lower temperature than the surrounding underground in order to collect heat energy. The steeper the thermal gradient, the more energy is transferred to the carrier fluid. The heat injection case works vice versa. For fast and sufficient heat extraction, even over long periods of heating (winter), it might become necessary to run the BHE with fluid temperatures below 0°C. As the heat pump runs periodically, a cyclic freezing of the pore water and corresponding ice-lens growth in the nearfield of the BHE pipes becomes possible. These so called freeze-thaw-cycles (FTC) are a critical state for the backfill material, as the sealing effect eventually decreases. From a hydrogeological point of view the vertical sealing of the BHE needs to be secured at any time (e.g. VDI 4640-2, Draft 2015). The vertical hydraulic conductivity of the BHE is influenced not only by the permeability of the grouting material itself, but by the contact area between BHE pipes and grout. In order to assess the sealing capacity of grouting materials a laboratory testing procedure was developed that measures the vertical hydraulic conductivity of the system BHE pipe and grout. The key features of the procedure are: • assessment of the systeḿs hydraulic conductivity • assessment of the systeḿs hydraulic conductivity after simulation of freeze-thaw-cycle

  9. Buoyancy and thermocapillary driven convection flow of electrically conducting fluid in an enclosure with heat generation

    International Nuclear Information System (INIS)

    Hossain, Md. Anwar; Rees, D.A.S.

    2002-05-01

    The effect of surface tension on unsteady laminar natural convection flow of a viscous incompressible fluid in a rectangle enclosure with internal heat generation and in presence of a uniform transverse magnetic field acting in the direction normal to the gravity has been investigated. The top horizontal surface of the rectangular cavity is assumed to be free and the bottom ones insulated; whereas the left vertical wall is cold and the right one is uniformly hot. The equations are non-dimensionalized and solved numerically by an upwind finite difference method together with a successive over-relaxation (SOR) technique. The effects of heat generation together with the combined effects of the magnetic field and the surface tension are presented graphically in terms of isotherms, streamlines and velocity vector plots. The effects of varying the physical parameters on the rate of heat transfer from the heated surface of the enclosure are also depicted. The fluid here has Prandtl number Pr=0.054 while the value of the Grashof number is 2x10 4 . (author)

  10. Orthotropic conductivity reconstruction with virtual-resistive network and Faraday's law

    KAUST Repository

    Lee, Min-Gi

    2015-06-01

    We obtain the existence and the uniqueness at the same time in the reconstruction of orthotropic conductivity in two-space dimensions by using two sets of internal current densities and boundary conductivity. The curl-free equation of Faraday\\'s law is taken instead of the elliptic equation in a divergence form that is typically used in electrical impedance tomography. A reconstruction method based on layered bricks-type virtual-resistive network is developed to reconstruct orthotropic conductivity with up to 40% multiplicative noise.

  11. Application of Multi-rate Flowing Fluid Electric ConductivityLogging Method to Well DH-2, Tono Site, Japan

    Energy Technology Data Exchange (ETDEWEB)

    Doughty, Christine; Takeuchi, Shinji; Amano, Kenji; Shimo, Michito; Tsang, Chin-Fu

    2004-10-04

    The flowing fluid electric conductivity (FEC) logging method, wellbore fluid is replaced with de-ionized water, following which FEC profiles in the wellbore are measured at a series of times while the well is pumped at a constant rate. Locations were fluid enters the wellbore show peaks in the FEC logs, which may be analyzed to infer inflow strengths and salinities of permeable features intersected by the wellbore. In multi-rate flowing FEC logging, the flowing FEC logging method is repeated using two or more pumping rates, which enables the transmissivities and inherent pressure heads of these features to be estimated as well. We perform multi-rate FEC logging on a deep borehole in fractured granitic rock, using three different pumping rates. Results identify 19 hydraulically conducting fractures and indicate that transmissivity, pressure head, and salinity vary significantly among them. By using three pumping rates rather than the minimum number of two, we obtain an internal consistency check on the analysis that provides a measure of the uncertainty of the results. Good comparisons against static FEC profiles and against independent chemical, geological, and hydrogeological data have further enhanced confidence in the results of the multi-rate flowing FEC logging method.

  12. Multi-channel conduction in redox-based resistive switch modelled using quantum point contact theory

    Energy Technology Data Exchange (ETDEWEB)

    Miranda, E., E-mail: enrique.miranda@uab.cat; Suñé, J. [Departament d' Enginyeria Electrònica, Universitat Autònoma de Barcelona, 08193 Cerdanyola del Vallés, Barcelona (Spain); Mehonic, A.; Kenyon, A. J. [Department of Electronic and Electrical Engineering, University College London, Torrington Place, London WC1E 7JE (United Kingdom)

    2013-11-25

    A simple analytic model for the electron transport through filamentary-type structures in Si-rich silica (SiO{sub x})-based resistive switches is proposed. The model is based on a mesoscopic description and is able to account for the linear and nonlinear components of conductance that arise from both fully and partially formed conductive channels spanning the dielectric film. Channels are represented by arrays of identical scatterers whose number and quantum transmission properties determine the current magnitude in the low and high resistance states. We show that the proposed model not only reproduces the experimental current-voltage (I-V) characteristics but also the normalized differential conductance (dln(I)/dln(V)-V) curves of devices under test.

  13. Scratch-resistant, highly conductive, and high-strength carbon nanotube-based composite yarns.

    Science.gov (United States)

    Liu, Kai; Sun, Yinghui; Lin, Xiaoyang; Zhou, Ruifeng; Wang, Jiaping; Fan, Shoushan; Jiang, Kaili

    2010-10-26

    High-strength and conductive carbon nanotube (CNT) yarns are very attractive in many potential applications. However, there is a difficulty when simultaneously enhancing the strength and conductivity of CNT yarns. Adding some polymers into CNT yarns to enhance their strength will decrease their conductivity, while treating them in acid or coating them with metal nanoparticles to enhance their conductivity will reduce their strength. To overcome this difficulty, here we report a method to make high-strength and highly conductive CNT-based composite yarns by using a continuous superaligned CNT (SACNT) yarn as a conductive framework and then inserting polyvinyl alcohol (PVA) into the intertube spaces of the framework through PVA/dimethyl sulphoxide solution to enhance the strength of yarns. The as-produced CNT/PVA composite yarns possess very high tensile strengths up to 2.0 GPa and Young's moduli more than 120 GPa, much higher than those of the CNT/PVA yarns reported. The electric conductivity of as-produced composite yarns is as high as 9.2 × 10(4) S/m, comparable to HNO(3)-treated or Au nanoparticle-coated CNT yarns. These composite yarns are flexible, lightweight, scratch-resistant, very stable in the lab environment, and resistant to extremely humid ambient and as a result can be woven into high-strength and heatable fabrics, showing potential applications in flexible heaters, bullet-proof vests, radiation protection suits, and spacesuits.

  14. Surface resistivity/conductivity of oxide–hydroxide compounds in inhibited seawater by optical interferometry

    Directory of Open Access Journals (Sweden)

    Khaled Habib

    2016-09-01

    Full Text Available Optical interferometry techniques were used to measure the surface resistivity/conductivity of carbon steel samples in blank seawater and in seawater with different concentrations of a corrosion inhibitor, without any physical contact. The measurement of the surface resistivity/conductivity of carbon steel samples was carried out in blank seawater and in seawater with a concentration range of 5–20 ppm of RA-41 corrosion inhibitor, at room temperature. In this investigation, the real-time holographic interferometry was carried out to measure the thickness of anodic dissolved layer or the total thickness, Utotal, of the formed oxide layer of carbon steel samples during the alternating current (AC impedance of the samples in blank seawater and in 5–20 ppm RA-41 inhibited seawater, respectively. In other words, the surface resistivity/conductivity of carbon steel samples was determined simultaneously by holographic interferometry, an electromagnetic method, and by the Electrochemical Impedance (E.I spectroscopy, an electronic method. In addition, a mathematical model was derived in order to correlate between the AC impedance (resistance and to the surface (orthogonal displacement of the surface of the samples in solutions.

  15. Using Integrated 2D and 3D Resistivity Imaging Methods for Illustrating the Mud-Fluid Conduits of the Wushanting Mud Volcanoes in Southwestern Taiwan

    Directory of Open Access Journals (Sweden)

    Ping-Yu Chang

    2011-01-01

    Full Text Available We conducted 2D and 3D looped resistivity surveys in the Wushanting Natural Landscape Preservation Area (WNLPA in order to understand the relationships of the mud-fluid conduits in the mud volcano system. 2D resistivity surveys were conducted along seven networked lines. Two separate C-shape looped electrode arrays surrounding the volcano craters were used in the study. First, the two 3D looped measurements were inverted separately. Yet the inverted 3D images of the mud-volcano system were inconsistent with the landscape features suggesting that artifacts perhaps appeared in the images. The 3D looped data were then combined with the 2D data for creating a global resistivity model of WNLPA. The resulting 3D image is consistent with the observed landscape features. With the resistivity model of WNLPA, we further tried to estimate the distribution of water content. The results suggest that the 3D resistivity image has the potential to resolve the dual porosity structures in the mudstone area. Last, we used a simplified WNLPA model for forward simulation in order to verify the field measurement results. We have concluded that the artifacts in the 3D looped images are in fact shadow effects from conductive objects out of the electrode loops, and that inverted images of combined 2D and 3D data provide detailed regional conductive structures in the WNLPA site.

  16. Thermal resistance and conductivity of recycled construction and demolition waste (RCDW concrete blocks

    Directory of Open Access Journals (Sweden)

    Ivan Julio Apolonio Callejas

    Full Text Available Abstract In Brazil, studies to reuse construction and demolition waste are a special issue because a large amount of this material has been delivered to the public landfills and in illegal places. Some researchers have suggested reusing this material in building elements, such as bricks or blocks. It is possible to find a lot of researches in physical/mechanical characterization, while little effort has been made to characterize recycled construction and demolition waste blocks (RCDW for their thermal properties. The aim of this work was to characterize the RCDW thermal resistance and conductivity in order to provide subsidies for a building's thermal performance analysis. The hot-box method was adapted, together with measuring techniques with a heat-flow meter to determine the RCDW thermal properties. The results indicated that the RCDW block overall thermal resistance and thermal conductivity in the solid region was within the intervals of 0.33≤RT≤0.41m2KW-1 and 0.60≤l≤0.78Wm-1K-1, respectively. The lower resistance and conductivity values are justified by the presence of aggregate with a lower density and lower thermal conductivity than the natural aggregate.

  17. Heat transfer within hydrodissection fluids: An analysis of thermal conduction and convection using liquid and gel materials.

    Science.gov (United States)

    Johnson, Alexander; Brace, Christopher

    2015-01-01

    Interventional oncology procedures such as thermal ablation are becoming widely used for many tumours in the liver, kidney and lung. Thermal ablation refers to the focal destruction of tissue by generating cytotoxic temperatures in the treatment zone. Hydrodissection - separating tissues with fluids - protects healthy tissues adjacent to the ablation treatment zone to improve procedural safety, and facilitate more aggressive power application or applicator placement. However, fluids such as normal saline and 5% dextrose in water (D5W) can migrate into the peritoneum, reducing their protective efficacy. As an alternative, a thermo-gelable poloxamer 407 (P407) solution has been recently developed to facilitate hydrodissection procedures. We hypothesise that the P407 gel material does not provide convective heat dissipation from the ablation site, and therefore may alter the heat transfer dynamics compared to liquid materials during hydrodissection-assisted thermal ablation. The purpose of this study was to investigate the heat dissipation mechanics within D5W, liquid P407 and gel P407 hydrodissection barriers. Overall it was shown that the gel P407 dissipated heat primarily through conduction, whereas the liquid P407 and D5W dissipated heat through convection. Furthermore, the rate of temperature change within the gel P407 was greater than liquid P407 and D5W. Testing to evaluate the in vivo efficacy of the fluids with different modes of heat dissipation seems warranted for further study.

  18. Numerical analysis of fluid resistance exerted on vibrating micro-sphere controlled by optical radiation pressure

    Science.gov (United States)

    Tanaka, Shimpei; Takaya, Yasuhiro; Hayashi, Terutake

    2008-08-01

    With the recent development of microfabrication technology, the measurement technology to evaluate geometric quantities is demanded to assure their accuracy. In order to measure the 3D shape of these microcomponents, a novel nano-CMM system has been developed based on an oscillated probing technique, which uses an optically trapped particle. The particle as a probe is trapped by focused laser light using an objective in the air. The trapped particle is laterally oscillated or circularly at the focal plane of the objective using AOD (acousto-optical deflector). The motion of the trapped particle is induced by a trapping force toward a focal spot and damped by the viscosity of the surrounding atmosphere. The frequency response of the oscillated particle typically agrees with the spring-mass-damper model. On the other hand the response disagrees with the theoretical curve of the model at high frequency range, i.e. 4.6% at 4000 Hz. It is considered the difference is caused from the numerical error for the fluid effect, which is given by the stokes formula 6πηr In this report, we construct a fluid simulation using SMAC method that calculates fluid resistance against an oscillating sphere in noninertial frame of reference. The fluid effect is investigated in order to improve the model of the sphere motion. 2D simulation indicates the same tendency in frequency response of the oscillating sphere with amplitudes of 500 nm in 100-4000 Hz frequency range. 3D simulation could improve the measurement accuracy of nano-CMM system as compared with 2D simulation.

  19. Resistance switching of the interfacial conductance in amorphous SrTiO3 heterostructures

    DEFF Research Database (Denmark)

    Christensen, Dennis; Trier, Felix; Chen, Yunzhong

    Complex oxides have attracted a lot of interest recently as this class of material exhibits a plethora of remarkable properties. In particular, a great variety of properties is observed in the heterostructure composed of lanthanum aluminate (LaAlO3) and strontium titanate (SrTiO3). For instance...... by an electric field. It has previously been demonstrated that SrTiO3 heterostructures with amorphous LaAlO3 top layers can display interfacial conductivity with similar critical thickness dependence. Here, we report resistance switching of the interfacial conductance for SrTiO3 heterostructures with amorphous...

  20. Spatial resolution of the electrical conductance of ionic fluids using a Green-Kubo method

    Science.gov (United States)

    Jones, R. E.; Ward, D. K.; Templeton, J. A.

    2014-11-01

    We present a Green-Kubo method to spatially resolve transport coefficients in compositionally heterogeneous mixtures. We develop the underlying theory based on well-known results from mixture theory, Irving-Kirkwood field estimation, and linear response theory. Then, using standard molecular dynamics techniques, we apply the methodology to representative systems. With a homogeneous salt water system, where the expectation of the distribution of conductivity is clear, we demonstrate the sensitivities of the method to system size, and other physical and algorithmic parameters. Then we present a simple model of an electrochemical double layer where we explore the resolution limit of the method. In this system, we observe significant anisotropy in the wall-normal vs. transverse ionic conductances, as well as near wall effects. Finally, we discuss extensions and applications to more realistic systems such as batteries where detailed understanding of the transport properties in the vicinity of the electrodes is of technological importance.

  1. Electrical-conductivity measurements of leachates for the rapid assessment of wasteform corrosion resistance

    International Nuclear Information System (INIS)

    Sales, B.C.; Petek, M.; Boatner, L.A.

    1982-01-01

    Measurements of the electrical conductivity of leachate solutions as a function of time can be used as an efficient, informative means of evaluation and comparison in the development of nuclear waste forms and in the preliminary analysis of their corrosion resistance in distilled water. Three separate applications of this technique are described in this work. These are: (1) its use in the optimization of the corrosion resistance of a crystalline wasteform (monazite); (2) a study of the protective ability of the surface layer (gel layer) which forms on the nuclear waste glass Frit 21 + 20 wt % SRW in distilled water; and (3) making comparisons of the overall corrosion resistance of three different nuclear wasteforms (i.e., monazite, SYNROC, and borosilicate glass). A complete solution analysis of the borosilicate glass leachate and a straightforward analysis of the conductivity results agree to within +-20%. In the absence of a complete, time consuming solution analysis, conductivity measurements can be used to estimate reliably the total ionic concentration in the leachate to within a factor of 2

  2. Enhanced Thermal Conductivity of Graphene Nanoplatelet-Polymer Nanocomposites Fabricated via Supercritical Fluid-Assisted in Situ Exfoliation.

    Science.gov (United States)

    Hamidinejad, S Mahdi; Chu, Raymond K M; Zhao, Biao; Park, Chul B; Filleter, Tobin

    2018-01-10

    As electronic devices become increasingly miniaturized, their thermal management becomes critical. Efficient heat dissipation guarantees their optimal performance and service life. Graphene nanoplatelets (GnPs) have excellent thermal properties that show promise for use in fabricating commercial polymer nanocomposites with high thermal conductivity. Herein, an industrially viable technique for manufacturing a new class of lightweight GnP-polymer nanocomposites with high thermal conductivity is presented. Using this method, GnP-high-density polyethylene (HDPE) nanocomposites with a microcellular structure are fabricated by melt mixing, which is followed by supercritical fluid (SCF) treatment and injection molding foaming, which adds an extra layer of design flexibility. Thus, the microstructure is tailored within the nanocomposites and this improves their thermal conductivity. Therefore, the SCF-treated HDPE 17.6 vol % GnP microcellular nanocomposites have a solid-phase thermal conductivity of 4.13 ± 0.12 W m -1 K -1 . This value far exceeds that of their regular injection-molded counterparts (2.09 ± 0.03 W m -1 K -1 ) and those reported in the literature. This dramatic improvement results from in situ GnPs' exfoliation and dispersion, and from an elevated level of random orientation and interconnectivity. Thus, this technique provides a novel approach to the development of microscopically tailored structures for the production of lighter and more thermally conductive heat sinks for next generations of miniaturized electronic devices.

  3. Transient plane source (tps) sensors for simultaneous measurements of thermal conductivity and thermal diffusivity of insulators, fluids and conductors

    Science.gov (United States)

    Maqsood, Asghari; Anis-ur-Rehman, M.

    2013-12-01

    Thermal conductivity and thermal diffusivity are two important physical properties for designing any food engineering processes1. The knowledge of thermal properties of the elements, compounds and different materials in many industrial applications is a requirement for their final functionality. Transient plane source (tps) sensors are reported2 to be useful for the simultaneous measurement of thermal conductivity, thermal diffusivity and volumetric heat capacity of insulators, conductor liquids3 and high-TC superconductors4. The tps-sensor consists of a resistive element in the shape of double spiral made of 10 micrometer thick Ni-foils covered on both sides with 25 micrometer thick Kapton. This sensor acts both as a heat source and a resistance thermometer for recording the time dependent temperature increase. From the knowledge of the temperature co-efficient of the metal spiral, the temperature increase of the sensor can be determined precisely by placing the sensor in between two surfaces of the same material under test. This temperature increase is then related to the thermal conductivity, thermal diffusivity and volumetric heat capacity by simple relations2,5. The tps-sensor has been used to measure thermal conductivities from 0.001 Wm-1K-1to 600 Wm-1K-1 and temperature ranges covered from 77K- 1000K. This talk gives the design, advantages and limitations of the tpl-sensor along with its applications to the measurementof thermal properties in a variety of materials.

  4. Transient plane source (tps) sensors for simultaneous measurements of thermal conductivity and thermal diffusivity of insulators, fluids and conductors

    International Nuclear Information System (INIS)

    Maqsood, Asghari; Anis-ur-Rehman, M

    2013-01-01

    Thermal conductivity and thermal diffusivity are two important physical properties for designing any food engineering processes 1 . The knowledge of thermal properties of the elements, compounds and different materials in many industrial applications is a requirement for their final functionality. Transient plane source (tps) sensors are reported 2 to be useful for the simultaneous measurement of thermal conductivity, thermal diffusivity and volumetric heat capacity of insulators, conductor liquids 3 and high-T C superconductors 4 . The tps-sensor consists of a resistive element in the shape of double spiral made of 10 micrometer thick Ni-foils covered on both sides with 25 micrometer thick Kapton. This sensor acts both as a heat source and a resistance thermometer for recording the time dependent temperature increase. From the knowledge of the temperature co-efficient of the metal spiral, the temperature increase of the sensor can be determined precisely by placing the sensor in between two surfaces of the same material under test. This temperature increase is then related to the thermal conductivity, thermal diffusivity and volumetric heat capacity by simple relations 2,5 . The tps-sensor has been used to measure thermal conductivities from 0.001 Wm −1 K −1 to 600 Wm −1 K −1 and temperature ranges covered from 77K– 1000K. This talk gives the design, advantages and limitations of the tpl-sensor along with its applications to the measurementof thermal properties in a variety of materials

  5. G-300, the first French Getaway Special microgravity measurements of fluid thermal conductivity

    Science.gov (United States)

    Perron, J. C.; Chretien, P.; Garnier, C.; Lecaude, N.

    On Earth thermal conductivity measurements on liquids are difficult to perform because thermal motions due to convection. In microgravity the convection due to buoyancy is evanescent and we expect a strong lowering of Rayleigh and Nusselt numbers. Three low viscosity liquids are selected to carry out the measurements: distilled water (standard) and two silicone oils. We use a modified "hot plate" method with a simplified guard ring, the lowering of convective motions let us to use in the experimental cells larger interplate distances and/or temperature differences than in earth measurements so the accuracy must be improved. Comparisons between Earth and orbit results may help to understand the convection occurrence in our cells. G-300 payload is cantilevered from the experiment mounting plate (EMP) and it includes: four struts, an intermediate plate, a bottom plate with four bumpers, a battery box, an electronic rack and six experimental cells assembled in twin-packs thermally coupled with the EMP. Thermal, vibration and EMI tests have proved that the design satisfies the Nasa requirements and acceptance is in progress.

  6. Resistance exercise-induced fluid shifts: change in active muscle size and plasma volume

    Science.gov (United States)

    Ploutz-Snyder, L. L.; Convertino, V. A.; Dudley, G. A.

    1995-01-01

    The purpose of this study was to test the hypothesis that the reduction in plasma volume (PV) induced by resistance exercise reflects fluid loss to the extravascular space and subsequently selective increase in cross-sectional area (CSA) of active but not inactive skeletal muscle. We compared changes in active and inactive muscle CSA and PV after barbell squat exercise. Magnetic resonance imaging (MRI) was used to quantify muscle involvement in exercise and to determine CSA of muscle groups or individual muscles [vasti (VS), adductor (Add), hamstring (Ham), and rectus femoris (RF)]. Muscle involvement in exercise was determined using exercise-induced contrast shift in spin-spin relaxation time (T2)-weighted MR images immediately postexercise. Alterations in muscle size were based on the mean CSA of individual slices. Hematocrit, hemoglobin, and Evans blue dye were used to estimate changes in PV. Muscle CSA and PV data were obtained preexercise and immediately postexercise and 15 and 45 min thereafter. A hierarchy of muscle involvement in exercise was found such that VS > Add > Ham > RF, with the Ham and RF showing essentially no involvement. CSA of the VS and Add muscle groups were increased 10 and 5%, respectively, immediately after exercise in each thigh with no changes in Ham and RF CSA. PV was decreased 22% immediately following exercise. The absolute loss of PV was correlated (r2 = 0.75) with absolute increase in muscle CSA immediately postexercise, supporting the notion that increased muscle size after resistance exercise reflects primarily fluid movement from the vascular space into active but not inactive muscle.

  7. Interpretation of Epithelial Lining Fluid Concentrations of Antibiotics against Methicillin Resistant Staphylococcus aureus.

    Science.gov (United States)

    Kiem, Sungmin; Schentag, Jerome J

    2014-12-01

    Although antibiotics whose epithelial lining fluid (ELF) concentrations are reported high tend to be preferred in treatment of pneumonia, measurement of ELF concentrations of antibiotics could be misled by contamination from lysis of ELF cells and technical errors of bronchoalveolar lavage (BAL). In this review, ELF concentrations of anti-methicillin resistant Staphylococcus aureus (MRSA) antibiotics were interpreted considering above confounding factors. An equation used to explain antibiotic diffusion into CSF (cerebrospinal fluid) was adopted: ELF/free serum concentration ratio = 0.96 + 0.091 × ln (partition coefficient / molecular weight(1/2)). Seven anti-MRSA antibiotics with reported ELF concentrations were fitted to this equation to see if their ELF concentrations were explainable by the penetration capacity only. Then, outliers were modeled under the assumption of varying contamination from lysed ELF cells (test range 0-10% of ELF volume). ELF concentrations of oritavancin, telavancin, tigecycline, and vancomycin were well described by the diffusion equation, with or without additional impact from cell lysis. For modestly high ELF/free serum concentration ratio of linezolid, technical errors of BAL should be excluded. Although teicoplanin and iclaprim showed high ELF/free serum ratios also, their protein binding levels need to be cleared for proper interpretation. At the moment, it appears very premature to use ELF concentrations of anti-MRSA antibiotics as a relevant guide for treatment of lung infections by MRSA.

  8. Fast prototyping of conducting polymer microelectrodes using resistance-controlled high precision drilling

    DEFF Research Database (Denmark)

    Kafka, Jan Robert; Geschke, Oliver; Skaarup, Steen

    2011-01-01

    We present a straightforward method for fast prototyping of microelectrode arrays in the highly conductive polymer poly(3,4-ethylenedioxythiophene) (PEDOT). Microelectrode arrays were produced by electrical resistance-controlled microdrilling through an insulating polymer layer (TOPAS® 5013......) covering a PEDOT layer. The sudden drop in electrical resistance between the metal drill and the PEDOT layer upon physical contact was employed as stop criterion for the drilling process. Arrays of 3×3 microelectrodes of diameter 30μm or 100μm, respectively, and having center-to-center electrode spacings...... approach the steady state currents predicted from modeling, but at a much slower rate than expected. This is shown to be caused by the use of electroactive PEDOT electrodes. Subtraction of the latter contribution gives approach to steady state currents within a few seconds, which is in very good agreement...

  9. Evaluation of the electrical conductivity and corrosion resistance for layers deposited via sputtering on stainless steel

    Science.gov (United States)

    Blanco, J.; Salas, Y.; Jiménez, C.; Pineda, Y.; Bustamante, A.

    2017-12-01

    In some Engineering fields, we need that conductive materials have a mechanic performance and specific electrical for that they maintain conditions or corrosive attack if they are in the environment or if they are closed structure. The stainless steels have an inert film on their surface and it has the function to act in contrast to external agents who generates the corrosion, especially for stings, spoiling the film until to fail. We found a solution taking into account the electrical performance and the anticorrosive; into the process we put recovering of specific oxides on, stainless steel using the method of sputtering with Unbalanced Magnetron, (UBM) varying the oxygen in the reactive environment. The coating obtained had a thickness one micron approximately and we saw on serious structural uniformity [1]. The corrosion resistance was evaluated through the potentiodynamics polarization and electrochemical spectroscopy impedance in NACL according to the standard. The cathode protection is the most important method employed for the corrosion prevention of metallic structures in the soil or immersed on the water. The electrical resistivity was evaluated with the four points methods and it showed a behaviour of diode type in some substrates with a threshold potential in several volts. We noticed a simple resistance solution when it was analysed in the Nyquist graphics whit the Electrochemical Impedance Spectroscopy technique. With on equivalent circuit, for this reason we determinate a variation in the corrosion speed in almost two orders of magnitude when we analysed the potentiodynamics curve by Tafel approximation. The data obtained and analysed show that this type of surface modification maintains the conductivity condition at the interface, improving the resistance in relation whit the corrosion of these elements where the recovering allowed the ionic flow wished for overcoming threshold voltage, acting as an insulator in different cases.

  10. Political struggles in disability’s visibilization: direct actions, counter-conducts and resistance

    Directory of Open Access Journals (Sweden)

    Alejandro Martín Contino

    2013-12-01

    Full Text Available Since the examination of the current situation of persons under disability, the hypothesis of conceiving disability as a device is carried out, according to the French philosopher Michel Foucault. Thus, the negative aspects experienced by subjects in situation of disability, not implying malfunction of public policy, would be logical and expected effects, the typical function of a disability device that works according to the guidelines of the Medical-Individual model. This article intends to present the tactics of counter-conduct as ways of subjectivation that resist current governmentality, becoming the visibilization of such actions, a key aspect of any strategy of political transformation.

  11. MHD Stagnation Point Flow of Williamson Fluid over a Stretching Cylinder with Variable Thermal Conductivity and Homogeneous/Heterogeneous Reaction

    Science.gov (United States)

    Bilal, M.; Sagheer, M.; Hussain, S.; Mehmood, Y.

    2017-06-01

    The present study reveals the effect of homogeneous/hetereogeneous reaction on stagnation point flow of Williamson fluid in the presence of magnetohydrodynamics and heat generation/absorption coefficient over a stretching cylinder. Further the effects of variable thermal conductivity and thermal stratification are also considered. The governing partial differential equations are converted to ordinary differential equations with the help of similarity transformation. The system of coupled non-linear ordinary differential equations is then solved by shooting technique. MATLAB shooting code is validated by comparison with the previously published work in limiting case. Results are further strengthened when the present results are compared with MATLAB built-in function bvp4c. Effects of prominent parameters are deliberated graphically for the velocity, temperature and concentration profiles. Skin-friction coefficient and Nusselt number for the different parameters are investigated with the help of tables.

  12. Magnetic fluid hyperthermia enhances cytotoxicity of bortezomib in sensitive and resistant cancer cell lines.

    Science.gov (United States)

    Alvarez-Berríos, Merlis P; Castillo, Amalchi; Rinaldi, Carlos; Torres-Lugo, Madeline

    2014-01-01

    The proteasome inhibitor bortezomib (BZ) has shown promising results in some types of cancer, but in others it has had minimal activity. Recent studies have reported enhanced efficacy of BZ when combined with hyperthermia. However, the use of magnetic nanoparticles to induce hyperthermia in combination with BZ has not been reported. This novel hyperthermia modality has shown better potentiation of chemotherapeutics over other types of hyperthermia. We hypothesized that inducing hyperthermia via magnetic nanoparticles (MFH) would enhance the cytotoxicity of BZ in BZ-sensitive and BZ-resistant cancer cells more effectively than hyperthermia using a hot water bath (HWH). Studies were conducted using BZ in combination with MFH in two BZ-sensitive cell lines (MDA-MB-468, Caco-2), and one BZ-resistant cell line (A2780) at two different conditions, ie, 43°C for 30 minutes and 45°C for 30 minutes. These experiments were compared with combined application of HWH and BZ. The results indicate enhanced potentiation between hyperthermic treatment and BZ. MFH combined with BZ induced cytotoxicity in sensitive and resistant cell lines to a greater extent than HWH under the same treatment conditions. The observation that MFH sensitizes BZ-resistant cell lines makes this approach a potentially effective anticancer therapy platform.

  13. Newton's Investigation of the Resistance to Moving Bodies in Continuous Fluids and the Nature of "Frontier Science"

    Science.gov (United States)

    Gauld, Colin F.

    2010-01-01

    Newton's experiments into the resistance which fluids offer to moving bodies provide some insight into the way he related theory and experiment. His theory demonstrates a way of thought typical of 17th century physics and his experiments are simple enough to be replicated by present day students. Newton's investigations using pendulums were…

  14. Electrically Conductive, Corrosion-Resistant Coatings Through Defect Chemistry for Metallic Interconnects

    International Nuclear Information System (INIS)

    Anil V. Virkar

    2006-01-01

    The principal objective of this work was to develop oxidation protective coatings for metallic interconnect based on a defect chemistry approach. It was reasoned that the effectiveness of a coating is dictated by oxygen permeation kinetics; the slower the permeation kinetics, the better the protection. All protective coating materials investigated to date are either perovskites or spinels containing metals exhibiting multiple valence states (Co, Fe, Mn, Cr, etc.). As a result, all of these oxides exhibit a reasonable level of electronic conductivity; typically at least about ∼0.05 S/cm at 800 C. For a 5 micron coating, this equates to a maximum ∼0.025 (Omega)cm 2 area specific resistance due to the coating. This suggests that the coating should be based on oxygen ion conductivity (the lower the better) and not on electronic conductivity. Measurements of ionic conductivity of prospective coating materials were conducted using Hebb-Wagner method. It was demonstrated that special precautions need to be taken to measure oxygen ion conductivity in these materials with very low oxygen vacancy concentration. A model for oxidation under a protective coating is presented. Defect chemistry based approach was developed such that by suitably doping, oxygen vacancy concentration was suppressed, thus suppressing oxygen ion transport and increasing effectiveness of the coating. For the cathode side, the best coating material identified was LaMnO 3 with Ti dopant on the Mn site (LTM). It was observed that LTM is more than 20 times as effective as Mn-containing spinels. On the anode side, LaCrO3 doped with Nb on the Cr site (LNC) was the material identified. Extensive oxidation kinetics studies were conducted on metallic alloy foils with coating ∼1 micron in thickness. From these studies, it was projected that a 5 micron coating would be sufficient to ensure 40,000 h life

  15. High Thermal Conductivity and High Wear Resistance Tool Steels for cost-effective Hot Stamping Tools

    Science.gov (United States)

    Valls, I.; Hamasaiid, A.; Padré, A.

    2017-09-01

    In hot stamping/press hardening, in addition to its shaping function, the tool controls the cycle time, the quality of the stamped components through determining the cooling rate of the stamped blank, the production costs and the feasibility frontier for stamping a given component. During the stamping, heat is extracted from the stamped blank and transported through the tool to the cooling medium in the cooling lines. Hence, the tools’ thermal properties determine the cooling rate of the blank, the heat transport mechanism, stamping times and temperature distribution. The tool’s surface resistance to adhesive and abrasive wear is also an important cost factor, as it determines the tool durability and maintenance costs. Wear is influenced by many tool material parameters, such as the microstructure, composition, hardness level and distribution of strengthening phases, as well as the tool’s working temperature. A decade ago, Rovalma developed a hot work tool steel for hot stamping that features a thermal conductivity of more than double that of any conventional hot work tool steel. Since that time, many complimentary grades have been developed in order to provide tailored material solutions as a function of the production volume, degree of blank cooling and wear resistance requirements, tool geometries, tool manufacturing method, type and thickness of the blank material, etc. Recently, Rovalma has developed a new generation of high thermal conductivity, high wear resistance tool steel grades that enable the manufacture of cost effective tools for hot stamping to increase process productivity and reduce tool manufacturing costs and lead times. Both of these novel grades feature high wear resistance and high thermal conductivity to enhance tool durability and cut cycle times in the production process of hot stamped components. Furthermore, one of these new grades reduces tool manufacturing costs through low tool material cost and hardening through readily

  16. Geophysical monitoring of simulated graves with resistivity, magnetic susceptibility, conductivity and GPR in Colombia, South America.

    Science.gov (United States)

    Molina, Carlos Martin; Pringle, Jamie K; Saumett, Miguel; Evans, Gethin T

    2016-04-01

    In most Latin American countries there are significant numbers of both missing people and forced disappearances, ∼71,000 Colombia alone. Successful detection of buried human remains by forensic search teams can be difficult in varying terrain and climates. Three clandestine burials were simulated at two different depths commonly encountered in Latin America. In order to gain critical knowledge of optimum geophysical detection techniques, burials were monitored using: ground penetrating radar, magnetic susceptibility, bulk ground conductivity and electrical resistivity up to twenty-two months post-burial. Radar survey results showed good detection of modern 1/2 clothed pig cadavers throughout the survey period on 2D profiles, with the 250MHz antennae judged optimal. Both skeletonised and decapitated and burnt human remains were poorly imaged on 2D profiles with loss in signal continuity observed throughout the survey period. Horizontal radar time slices showed good anomalies observed over targets, but these decreased in amplitude over the post-burial time. These were judged due to detecting disturbed grave soil rather than just the buried targets. Magnetic susceptibility and electrical resistivity were successful at target detection in contrast to bulk ground conductivity surveys which were unsuccessful. Deeper burials were all harder to image than shallower ones. Forensic geophysical surveys should be undertaken at suspected burial sites. Copyright © 2016 Elsevier Ireland Ltd. All rights reserved.

  17. High-resolution and high-conductive electrode fabrication on a low thermal resistance flexible substrate

    International Nuclear Information System (INIS)

    Kang, Bongchul; Kno, Jinsung; Yang, Minyang

    2011-01-01

    Processes based on the liquid-state pattern transfer, like inkjet printing, have critical limitations including low resolution and low electrical conductivity when fabricating electrodes on low thermal resistance flexible substrates such as polyethylene terephthalate (PET). Those are due to the nonlinear transfer mechanism and the limit of the sintering temperature. Although the laser direct curing (LDC) of metallic inks is an alternative process to improve the resolution, it is also associated with the disadvantages of causing thermal damage to the polymer substrate. This paper suggests the laser induced pattern adhesion transfer method to fabricate electrodes of both high electrical conductivity and high resolution on a PET substrate. First, solid patterns are cost-effectively created by the LDC of the organometallic silver ink on a glass that is optically and thermally stable. The solid patterns sintered on the glass are transferred to the PET substrate by the photo-thermally generated adhesion force of the substrate. Therefore, we achieved electrodes with a minimum line width of 10 µm and a specific resistance of 3.6 μΩcm on the PET substrate. The patterns also showed high mechanical reliability

  18. High-resolution and high-conductive electrode fabrication on a low thermal resistance flexible substrate

    Science.gov (United States)

    Kang, Bongchul; Kno, Jinsung; Yang, Minyang

    2011-07-01

    Processes based on the liquid-state pattern transfer, like inkjet printing, have critical limitations including low resolution and low electrical conductivity when fabricating electrodes on low thermal resistance flexible substrates such as polyethylene terephthalate (PET). Those are due to the nonlinear transfer mechanism and the limit of the sintering temperature. Although the laser direct curing (LDC) of metallic inks is an alternative process to improve the resolution, it is also associated with the disadvantages of causing thermal damage to the polymer substrate. This paper suggests the laser induced pattern adhesion transfer method to fabricate electrodes of both high electrical conductivity and high resolution on a PET substrate. First, solid patterns are cost-effectively created by the LDC of the organometallic silver ink on a glass that is optically and thermally stable. The solid patterns sintered on the glass are transferred to the PET substrate by the photo-thermally generated adhesion force of the substrate. Therefore, we achieved electrodes with a minimum line width of 10 µm and a specific resistance of 3.6 μΩcm on the PET substrate. The patterns also showed high mechanical reliability.

  19. Estimation of hydraulic conductivity on clay content in soil determined from resistivity data

    Energy Technology Data Exchange (ETDEWEB)

    Shevnin, Vladimir; Delgado-Rodriguez, Omar; Mousatov, Aleksandr [Mexican Petroleum Institute, Mexico, D.F. (Mexico); Ryjov, Albert [Moscow State Geological Prospecting Academy, Geophysical Faculty, Moscow (Russian Federation)

    2006-07-15

    The influence of clay content in sandy and clayey soils on hydraulic conductivity (filtration coefficient) is considered. A review of published experimental data on the relationship of hydraulic conductivity with soil lithology and grain size, as dependent on clay content is presented. Theoretical calculations include clay content. Experimental and calculated data agree, and several approximation formulas for filtration coefficient vs clay content are presented. Clay content in soil is estimated from electric resistivity data obtained from 2D VES interpretation. A two-step method is proposed, the first step including clay content calculating from soil resistivity and groundwater salinity, and the second step including filtration coefficient estimating from clay content. Two applications are presented. [Spanish] El contenido de arcilla en suelos areno-arcillosos influye sobre la permeabilidad hidraulica (coeficiente de filtracion). Se presenta una revision de datos experimentales publicados que relacionan el coeficiente de filtracion con el tipo litologico del suelo y el tamano de las particulas. A partir de calculos teoricos, se modifican las conocidas formulas que relacionan el coeficiente de filtracion con el contenido de arcilla. Se estima el contenido de arcilla a partir de los datos interpretados por el metodo SEV, y se propone un procedimiento para la estimacion del coeficiente de filtracion: (a) calculo del contenido de arcilla a partir de la resistividad del suelo y de la salinidad del agua subterranea, (b) estimacion del coeficiente de filtracion a partir del contenido de arcilla. Se presentan algunos ejemplos de la aplicacion de esta metodologia.

  20. 10 CFR 26.97 - Conducting an initial test for alcohol using a specimen of oral fluids.

    Science.gov (United States)

    2010-01-01

    ... oral fluids. 26.97 Section 26.97 Energy NUCLEAR REGULATORY COMMISSION FITNESS FOR DUTY PROGRAMS... fluids. (a) To perform the initial test, the collector shall— (1) Check the expiration date on the device... fluids in the manner described by the device's manufacturer (wear single-use examination or similar...

  1. Acute extracellular fluid volume changes increase ileocolonic resistance to saline flow in anesthetized dogs

    Directory of Open Access Journals (Sweden)

    Santiago Jr. A.T.

    1997-01-01

    Full Text Available We determined the effect of acute extracellular fluid volume changes on saline flow through 4 gut segments (ileocolonic, ileal, ileocolonic sphincter and proximal colon, perfused at constant pressure in anesthetized dogs. Two different experimental protocols were used: hypervolemia (iv saline infusion, 0.9% NaCl, 20 ml/min, volume up to 5% body weight and controlled hemorrhage (up to a 50% drop in mean arterial pressure. Mean ileocolonic flow (N = 6 was gradually and significantly decreased during the expansion (17.1%, P<0.05 and expanded (44.9%, P<0.05 periods while mean ileal flow (N = 7 was significantly decreased only during the expanded period (38%, P<0.05. Mean colonic flow (N = 7 was decreased during expansion (12%, P<0.05 but returned to control levels during the expanded period. Mean ileocolonic sphincter flow (N = 6 was not significantly modified. Mean ileocolonic flow (N = 10 was also decreased after hemorrhage (retracted period by 17% (P<0.05, but saline flow was not modified in the other separate circuits (N = 6, 5 and 4 for ileal, ileocolonic sphincter and colonic groups, respectively. The expansion effect was blocked by atropine (0.5 mg/kg, iv both on the ileocolonic (N = 6 and ileal (N = 5 circuits. Acute extracellular fluid volume retraction and expansion increased the lower gastrointestinal resistances to saline flow. These effects, which could physiologically decrease the liquid volume being supplied to the colon, are possible mechanisms activated to acutely balance liquid volume deficit and excess.

  2. Effects of transverse electric field and heterogeneity of a poorly electrically conducting fluid saturated nanoporous zeolites acquiring smart material properties

    International Nuclear Information System (INIS)

    Rudraiah, N.; Ranganna, G.; Shilpa, P.

    2013-01-01

    In this paper we explain a Mathematical Model involving Darcy linear drag, Forchheimer quadratic drag, horizontal density gradient and the variation of electrical conductivity due to organic substances dissolved in a heterogeneous Boussinesq poorly conducting couple stress fluid flow (PCPCSFF) through Nano Porous Zeolites regarded as densely packed porous media. Initially, the flow is at rest and set in motion due to initial piecewise horizontal concentration gradient. Analytical solutions, for electric potential using the Maxwell field equations and for velocity and density using nonlinear Darcy – Forchheimer equation in the presence of couple stress and electric force are obtained using the method of time series evolution. The analytical solutions for streamlines and density are computed for different values of time, t, for a particular value of electric number W 1 and couple stress parameterβ and the results are depicted graphically in figures 1 and 2. From these figures we found that the streamlines are closer in the region of x 0 and the density profiles are concentrated in the lower region and develop curvature in the presence of electric field and couple stress parameter. The physical reason for the nature of streamlines and density profiles are given in the last section and some important conclusions are drawn. (author)

  3. Conductive Protection Layers on Oxidation Resistant Alloys for SOFC Interconnect Applications

    Energy Technology Data Exchange (ETDEWEB)

    Yang, Zhenguo; Xia, Guanguang; Maupin, Gary D.; Stevenson, Jeffry W.

    2006-12-20

    Conductive oxide coatings are used as protection layers on metallic interconnects in SOFCs to improve their surface stability and electrical performance, as well as to mitigate or prevent chromium poisoning to cells. This paper discusses materials requirements for this particular application and summarizes our systematic study on varied conductive oxides as potential candidate materials for protection layers on stainless steel substrates. Overall, it appeared that chromites such as (La,Sr)CrO3 improved surface stability, but might not be good candidates for the protection layer applications due to chromium vaporization, albeit at a lower rate than Cr2O3, from these oxides at high temperatures in air or moist air. The application of non-chromite perovskite (La,Sr)FeO3 protection layers resulted in improved oxidation resistance and electrical performance. It is doubtful, however, that LSF can be an effective barrier to prevent chromium release during long term SOFC stack operation due to chromium diffusion through the LSF coatings. With a high oxygen ion conductivity, the coatings of Sn-doped In2O3 failed to provide protection to the metal substrate and are thus not suitable for the protection layer applications. The best performance was achieved using thermally-grown (Mn,Co)3O4 spinel protection layers that substantially improved the surface stability of the metal substrates, and prevented chromium outward migration.

  4. Testing hypotheses that link wood anatomy to cavitation resistance and hydraulic conductivity in the genus Acer.

    Science.gov (United States)

    Lens, Frederic; Sperry, John S; Christman, Mairgareth A; Choat, Brendan; Rabaey, David; Jansen, Steven

    2011-05-01

    • Vulnerability to cavitation and conductive efficiency depend on xylem anatomy. We tested a large range of structure-function hypotheses, some for the first time, within a single genus to minimize phylogenetic 'noise' and maximize detection of functionally relevant variation. • This integrative study combined in-depth anatomical observations using light, scanning and transmission electron microscopy of seven Acer taxa, and compared these observations with empirical measures of xylem hydraulics. • Our results reveal a 2 MPa range in species' mean cavitation pressure (MCP). MCP was strongly correlated with intervessel pit structure (membrane thickness and porosity, chamber depth), weakly correlated with pit number per vessel, and not related to pit area per vessel. At the tissue level, there was a strong correlation between MCP and mechanical strength parameters, and some of the first evidence is provided for the functional significance of vessel grouping and thickenings on inner vessel walls. In addition, a strong trade-off was observed between xylem-specific conductivity and MCP. Vessel length and intervessel wall characteristics were implicated in this safety-efficiency trade-off. • Cavitation resistance and hydraulic conductivity in Acer appear to be controlled by a very complex interaction between tissue, vessel network and pit characteristics. © 2010 The Authors. New Phytologist © 2010 New Phytologist Trust.

  5. Effects of electric field and Coriolis force on electrohydrodynamic stability of poorly conducting couple stress parallel fluid flow in a channel

    International Nuclear Information System (INIS)

    Shankar, B.M.; Rudraiah, N.

    2013-01-01

    The linear stability of electrohydrodynamic poorly conducting couple stress viscous parallel fluid flow in a channel is studied in the presence of a non-uniform transverse electric field and Coriolis force using energy method and supplemented with Galerkin Technique. The sufficient condition for stability is obtained for sufficiently small values of the Reynolds number, R e . From this condition we show that strengthening or weakening of the stability criterion is dictated by the values of the strength of electric field, the coefficient of couple stress fluid and independent of Taylor number. In particular, it is shown that the interaction of electric field with couple stress is more effective in stabilizing the poorly conducting couple stress fluid compared to that in an ordinary Newtonian viscous fluid. (author)

  6. Effects of electric field and Coriolis force on electrohydrodynamic stability of poorly conducting couple stress parallel fluid flow in a channel

    International Nuclear Information System (INIS)

    Shankar, B.M.; Rudraiah, N.

    2013-01-01

    The effective functioning of microfluidic devices in chemical, electrical and mechanical engineering involving fluidics particularly those having vibrations and petroleum products containing organic, inorganic and other microfluidics require understanding and control of stability of poorly conducting parallel fluid flows. The electrical conductivity, σ, of a poorly conducting fluidics, increases with the temperature and the concentration of freely suspended particles like RBC, WBC and so on in the blood, the hylauronic acid (HA) and nutrients of synovial fluid in synovial joints will spin producing microrotation, forming micropolar fluid of Eringen. The presence of Deuterium - Tritium (DT) in inertial fusion target (IFT) may also be modeled using micropolar fluid theory of Eringen. A particular case of micropolar fluid theory when microrotation balances with the natural vorticity of a poorly conducting fluidics in the presence of an electric field is called ‘electrohydrodynamic couple stress fluid’ (EHDCF). These EHDCFs exhibit a variation of electrical conductivity, ∇ σ, increasing with temperature and concentration of freely suspended particles, releases the charges from the nuclei forming distribution of charge density, ρ e . These charges induce an electric field, 1 E i . If need be, we can apply an electric field, 1 E a , by embedding electrodes of different potentials at the boundaries. The total electric field, 1 E = 1 E i + 1 E a , produces a current density, 1 J = ρ σ 1 E, according to Ohm’s law and also produces an electric force, 1 F σ = σ 1 E. This current 1 J acts as sensing and the force, 1 F σ acts as actuation. These two properties make the poorly conducting couple stress fluid to act as a smart material. The objective of this paper is to show that EHDCV in presence of coriolis force plays a significant role in controlling the stability of parallel flows which is essential for an effective functioning of machineries that occur in

  7. Nanoscale fluid-structure interaction: flow resistance and energy transfer between water and carbon nanotubes.

    Science.gov (United States)

    Chen, Chao; Ma, Ming; Jin, Kai; Liu, Jefferson Zhe; Shen, Luming; Zheng, Quanshui; Xu, Zhiping

    2011-10-01

    We investigate here water flow passing a single-walled carbon nanotube (CNT), through analysis based on combined atomistic and continuum mechanics simulations. The relation between drag coefficient C(D) and Reynolds number Re is obtained for a wide range of flow speed u from 5 to 600 m/s. The results suggest that Stokes law for creep flow works well for small Reynolds numbers up to 0.1 (u ≈ 100 m/s), and indicates a linear dependence between drag force and flow velocity. Significant deviation is observed at elevated Re values, which is discussed by considering the interfacial slippage, reduction of viscosity due to friction-induced local heating, and flow-induced structural vibration. We find that interfacial slippage has a limited contribution to the reduction of the resistance, and excitations of low-frequency vibration modes in the carbon nanotube play an important role in energy transfer between water and carbon nanotubes, especially at high flow speeds where drastic enhancement of the carbon nanotube vibration is observed. The results reported here reveal nanoscale fluid-structure interacting mechanisms, and lay the ground for rational design of nanofluidics and nanoelectromechanical devices operating in a fluidic environment.

  8. A numerical analysis and experimental demonstration of a low degradation conductive bridge resistive memory device

    Science.gov (United States)

    Berco, Dan; Chand, Umesh; Fariborzi, Hossein

    2017-10-01

    This study investigates a low degradation metal-ion conductive bridge RAM (CBRAM) structure. The structure is based on placing a diffusion blocking layer (DBL) between the device's top electrode (TE) and the resistive switching layer (RSL), unlike conventional CBRAMs, where the TE serves as a supply reservoir for metallic species diffusing into the RSL to form a conductive filament (CF) and is kept in direct contact with the RSL. The properties of a conventional CBRAM structure (Cu/HfO2/TiN), having a Cu TE, 10 nm HfO2 RSL, and a TiN bottom electrode, are compared with a 2 nm TaN DBL incorporating structure (Cu/TaN/HfO2/TiN) for 103 programming and erase simulation cycles. The low and high resistive state values for each cycle are calculated and the analysis reveals that adding the DBL yields lower degradation. In addition, the 2D distribution plots of oxygen vacancies, O ions, and Cu species within the RSL indicate that oxidation occurring in the DBL-RSL interface results in the formation of a sub-stoichiometric tantalum oxynitride with higher blocking capabilities that suppresses further Cu insertion beyond an initial CF formation phase, as well as CF lateral widening during cycling. The higher endurance of the structure with DBL may thus be attributed to the relatively low amount of Cu migrating into the RSL during the initial CF formation. Furthermore, this isomorphic CF displays similar cycling behavior to neural ionic channels. The results of numerical analysis show a good match to experimental measurements of similar device structures as well.

  9. A numerical analysis and experimental demonstration of a low degradation conductive bridge resistive memory device

    KAUST Repository

    Berco, Dan

    2017-10-23

    This study investigates a low degradation metal-ion conductive bridge RAM (CBRAM) structure. The structure is based on placing a diffusion blocking layer (DBL) between the device\\'s top electrode (TE) and the resistive switching layer (RSL), unlike conventional CBRAMs, where the TE serves as a supply reservoir for metallic species diffusing into the RSL to form a conductive filament (CF) and is kept in direct contact with the RSL. The properties of a conventional CBRAM structure (Cu/HfO2/TiN), having a Cu TE, 10 nm HfO2 RSL, and a TiN bottom electrode, are compared with a 2 nm TaN DBL incorporating structure (Cu/TaN/HfO2/TiN) for 103 programming and erase simulation cycles. The low and high resistive state values for each cycle are calculated and the analysis reveals that adding the DBL yields lower degradation. In addition, the 2D distribution plots of oxygen vacancies, O ions, and Cu species within the RSL indicate that oxidation occurring in the DBL-RSL interface results in the formation of a sub-stoichiometric tantalum oxynitride with higher blocking capabilities that suppresses further Cu insertion beyond an initial CF formation phase, as well as CF lateral widening during cycling. The higher endurance of the structure with DBL may thus be attributed to the relatively low amount of Cu migrating into the RSL during the initial CF formation. Furthermore, this isomorphic CF displays similar cycling behavior to neural ionic channels. The results of numerical analysis show a good match to experimental measurements of similar device structures as well

  10. An improved heat conduction and mass diffusion models for rotating flow of an Oldroyd-B fluid

    Science.gov (United States)

    Khan, W. A.; Irfan, M.; Khan, M.

    An analysis is presented to inspect the steady three-dimensional boundary layer flow of an Oldroyd-B fluid over a stretching surface. Heat and mass transfer analysis are scrutinized by utilizing the non-Fourier's and non-Fick's models in rotating frame. The expressions of heat and mass fluxes are based upon the Cattaneo-Christov theory. The Cattaneo-Christov heat and mass flux models are used for the development of energy and concentration equations which account the contribution of thermal and concentration relaxation times. Additionally, temperature dependent thermal conductivity is also considered here. Apposite transformations are betrothed to obtain the ordinary differential equations with high nonlinearity. The analytical solutions are established for the resulting ordinary differential system by utilizing the homotopy analysis method (HAM). Our observations reveal that the rotation parameter serves to diminish the primary velocity f‧ (η) and associated momentum boundary layer thickness and similar trend is observed for the secondary velocity g (η) . It is also observed that the thermal and concentration relaxation time parameters reduce the temperature and concentration profiles. For endorsement of the current relation, the attained consequences are eminent with former exploration in precise cases and splendid agreement has been distinguished.

  11. Direct observation of conductive filament formation in Alq3 based organic resistive memories

    Energy Technology Data Exchange (ETDEWEB)

    Busby, Y., E-mail: yan.busby@unamur.be; Pireaux, J.-J. [Research Center in the Physics of Matter and Radiation (PMR), Laboratoire Interdisciplinaire de Spectroscopie Electronique (LISE), University of Namur, B-5000 Namur (Belgium); Nau, S.; Sax, S. [NanoTecCenter Weiz Forschungsgesellschaft mbH, Franz-Pichler Straße 32, A-8160 Weiz (Austria); List-Kratochvil, E. J. W. [NanoTecCenter Weiz Forschungsgesellschaft mbH, Franz-Pichler Straße 32, A-8160 Weiz (Austria); Institute of Solid State Physics, Graz University of Technology, A-8010 Graz (Austria); Novak, J.; Banerjee, R.; Schreiber, F. [Institute of Applied Physics, Eberhard-Karls-Universität Tübingen, D-72076 Tübingen (Germany)

    2015-08-21

    This work explores resistive switching mechanisms in non-volatile organic memory devices based on tris(8-hydroxyquinolie)aluminum (Alq{sub 3}). Advanced characterization tools are applied to investigate metal diffusion in ITO/Alq{sub 3}/Ag memory device stacks leading to conductive filament formation. The morphology of Alq{sub 3}/Ag layers as a function of the metal evaporation conditions is studied by X-ray reflectivity, while depth profile analysis with X-ray photoelectron spectroscopy and time-of-flight secondary ion mass spectrometry is applied to characterize operational memory elements displaying reliable bistable current-voltage characteristics. 3D images of the distribution of silver inside the organic layer clearly point towards the existence of conductive filaments and allow for the identification of the initial filament formation and inactivation mechanisms during switching of the device. Initial filament formation is suggested to be driven by field assisted diffusion of silver from abundant structures formed during the top electrode evaporation, whereas thermochemical effects lead to local filament inactivation.

  12. Forced convection heat transfer in rectangular ducts - general case of wall resistances and peripheral conduction for ventilation cooling of nuclear waste repositories

    International Nuclear Information System (INIS)

    Lyczkowski, R.W.; Solbrig, C.W.; Gidaspow, D.

    1982-01-01

    A numerical solution for laminar flow heat transfer between a flowing gas and its containing rectangular duct has been obtained for many different boundary conditions which may arise in nuclear waste repository ventilation corridors. The problem has been solved for the cases of insulation on no walls, one wall, two walls, and three walls with various finite resistances on the remaining walls. Simplifications are made to decouple the convective heat transfer problem from the far field conduction problem, but peripheral conduction is retained. Results have been obtained for several duct aspect ratios in the thermal entrance and in the fully developed regions, including the constant temperature cases. When one wall is insulated and the other three are at constant temperature, the maximum temperature occurs in the fluid rather than on the insulated wall. This maximum moves toward the insulated wall with increasing axial distance. Nusselt numbers for the same constant flux on all four walls with peripheral conduction lie in a narrow band bounded by zero and infinite peripheral conduction cases. A dimensionsless wall conduction group of four can be considered infinite for the purpose of estimating fully developed Nusselt numbers to within an accuracy of 3%. A decrease in wall and bulk temperatures by finite wall conduction has been demonstrated for the case of a black body radiation boundary condition. Nusselt numbers for the case of constant temperature on the top and bottom walls and constant heat flux on the side walls exhibited unexpected behavior. (orig.)

  13. Forced convection heat transfer in rectangular ducts - general case of wall resistances and peripheral conduction for ventilation cooling of nuclear waste repositories

    International Nuclear Information System (INIS)

    Lyczkowski, R.W.; Solbrig, C.W.; Gidaspow, D.

    1980-01-01

    A numerical solution for laminar flow heat transfer between a flowing gas and its containing rectangular duct has been obtained for many different boundary conditions which may arise in nuclear waste repository ventilation corridors. The problem has been solved for the cases of insulation on no walls, one wall, two walls, and three walls with various finite resistances on the remaining walls. Simplifications are made to decouple the convective heat transfer problem for the far field conduction problem, but peripheral conduction is retained. Results have been obtained for several duct aspect ratios in the thermal entrance and in the fully developed regions, including the constant temperature cases. When one wall is insulated and the other three are at constant temperature, the maximum temperature occurs in the fluid rather than on the insulated wall. This maximum moves toward the insulated wall with increasing axial distance. Nusselt numbers for the same constant flux on all four walls with peripheral conduction lie in a narrow band bounded by zero and infinite peripheral conduction cases. A dimensionless wall conduction group of four can be considered infinite for the purpose of estimating fully developed Nusselt numbers to within an accuracy of 3%. A decrease in wall and bulk temperatures by finite wall conduction has been demonstrated for the case of a black body radiation boundary condition. Nusselt numbers for the case of constant temperature on the top and bottom walls and constant heat flux on the side walls exhibited unexpected behavior

  14. A peptide-based biological coating for enhanced corrosion resistance of titanium alloy biomaterials in chloride-containing fluids.

    Science.gov (United States)

    Muruve, Noah; Feng, Yuanchao; Platnich, Jaye; Hassett, Daniel; Irvin, Randall; Muruve, Daniel; Cheng, Frank

    2017-03-01

    Titanium alloys are common materials in the manufacturing of dental and orthopedic implants. Although these materials exhibit excellent biocompatibility, corrosion in response to biological fluids can impact prosthesis performance and longevity. In this work, a PEGylated metal binding peptide (D-K122-4-PEG), derived from bacteria Pseudomonas aeruginosa, was applied on a titanium (Ti) alloy, and the corrosion resistance of the coated alloy specimen was investigated in simulated chloride-containing physiological fluids by electrochemical impedance spectroscopy and micro-electrochemical measurements, surface characterization, and biocompatibility testing. Compared to uncoated specimen, the D-K122-4-PEG-coated Ti alloy demonstrates decreased corrosion current density without affecting the natural passivity. Morphological analysis using atomic force microscopy and scanning electron microscopy confirms a reduction in surface roughness of the coated specimens in the fluids. The D-K122-4-PEG does not affect the binding of HEK-293T cells to the surface of unpolished Ti alloy, nor does it increase the leukocyte activation properties of the metal. D-K122-4-PEG represents a promising coating to enhance the corrosion resistance of Ti alloys in physiological fluids, while maintaining an excellent biocompatibility.

  15. Effects of fabric thickness and material on apparent 'wet' conductive thermal resistance of knitted fabric 'skin' on sweating manikins.

    Science.gov (United States)

    Wang, Faming; Lai, Dandan; Shi, Wen; Fu, Ming

    2017-12-01

    Currently, no published standard and research work have addressed the basic requirements on knitted fabric 'skin' on sweating manikins. In this study, we performed 252 experiments to investigate the influence of fabric thickness and material on the apparent 'wet' conductive (or effective) thermal resistance of the fabric 'skin' using a 'Newton' manikin. Four types of cotton fabric 'skin' (fabric thickness: 0.38, 0.54, 0.92 and 1.43mm) and three types of polyester fabric 'skin' (fabric thickness: 0.41, 0.54 and 1.0mm) were selected and their 'wet' conductive thermal resistance was determined. Empirical equations were also developed for each fabric 'skin' to predict wet fabric 'skin' surface temperatures. It was found that both fabric thickness and material significantly affected the apparent 'wet' conductive thermal resistance. Clothing total evaporative resistance determined using thin fabric 'skin' (e.g., CO1, CO2) was normally lower than that determined using thick fabric 'skin' (e.g., CO4). Besides, synthetic fabric 'skin' tended to have a larger apparent 'wet' conductive thermal resistance than the cotton fabric 'skin' due to a smaller amount of moisture contained. Hence, there is a great need to standardize the fabric 'skin' to eliminate the influence of fabric 'skin' on the measurement of clothing evaporative resistance by means of a sweating manikin. Copyright © 2017 Elsevier Ltd. All rights reserved.

  16. Modeling the sensing characteristics of chemi-resistive thin film semi-conducting gas sensors.

    Science.gov (United States)

    Ghosh, Abhishek; Majumder, S B

    2017-08-30

    For chemi-resistive thin film gas sensors a generic theoretical model is proposed to predict the variation of sensor response with the operating temperature and thickness of the sensing film. A diffusion equation is formulated assuming that inflammable target gases move through the sensing film by Knudsen diffusion and react with the adsorbed oxygen following first-order kinetics. We have assumed a realistic non-linear variation between the conductance and test gas concentration and derived a general expression relating the sensor response to the operating temperature and thickness of the film. Assuming Langmuir adsorption kinetics, we have theoretically predicted the response and recovery transients during gas sensing using thin film sensing elements. It is predicted that for irreversible type sensing, the response time is reduced with an increase in test gas concentration, whereas for reversible sensing, the response time is independent of test gas concentration. For zinc oxide thin film sensors, an excellent match is obtained between the model prediction and experimental data for their thickness (122 nm to 380 nm) and temperature variation (200 °C to 325 °C) in 500 ppm carbon monoxide (CO) sensing. The maximum CO response% (∼53%) was achieved in 320 nm thick ZnO films. The conductance transients for response and recovery for CO sensing closely follow Langmuir adsorption kinetics and as predicted theoretically, indeed for irreversible sensing, the response time reduces from 350 s to 220 s with an increase in test gas concentration from 20 to 550 ppm. In the case of reversible sensing we found that the response time is ∼55 s irrespective of the CO gas concentration in the range of 5-500 ppm. The models developed in the present work are quite generic in nature and we have discussed their applicability to a wide variety of sensing materials with various types of surface morphologies.

  17. Electrical resistivity and thermal conductivity of SiC/Si ecoceramics prepared from sapele wood biocarbon

    Science.gov (United States)

    Parfen'eva, L. S.; Orlova, T. S.; Smirnov, B. I.; Smirnov, I. A.; Misiorek, H.; Mucha, J.; Jezowski, A.; Gutierrez-Pardo, A.; Ramirez-Rico, J.

    2012-10-01

    Samples of β-SiC/Si ecoceramics with a silicon concentration of ˜21 vol % have been prepared using a series of consecutive procedures (carbonization of sapele wood biocarbon, synthesis of high-porosity biocarbon with channel-type pores, infiltration of molten silicon into empty channels of the biocarbon, formation of β-SiC, and retention of residual silicon in channels of β-SiC). The electrical resistivity ρ and thermal conductivity κ of the β-SiC/Si ecoceramic samples have been measured in the temperature range 5-300 K. The values of ρ{Si/chan}( T) and κ{Si/chan}( T) have been determined for silicon Sichan located in β-SiC channels of the synthesized β-SiC/Si ecoceramics. Based on the performed analysis of the obtained results, the concentration of charge carriers (holes) in Sichan has been estimated as p ˜ 1019 cm-3. The factors that can be responsible for such a high value of p have been discussed. The prospects for practical application of β-SiC/Si ecoceramics have been considered.

  18. Structural changes and conductance thresholds in metal-free intrinsic SiOx resistive random access memory

    Science.gov (United States)

    Mehonic, Adnan; Buckwell, Mark; Montesi, Luca; Garnett, Leon; Hudziak, Stephen; Fearn, Sarah; Chater, Richard; McPhail, David; Kenyon, Anthony J.

    2015-03-01

    We present an investigation of structural changes in silicon-rich silicon oxide metal-insulator-metal resistive RAM devices. The observed unipolar switching, which is intrinsic to the bulk oxide material and does not involve movement of metal ions, correlates with changes in the structure of the oxide. We use atomic force microscopy, conductive atomic force microscopy, x-ray photoelectron spectroscopy, and secondary ion mass spectroscopy to examine the structural changes occurring as a result of switching. We confirm that protrusions formed at the surface of samples during switching are bubbles, which are likely to be related to the outdiffusion of oxygen. This supports existing models for valence-change based resistive switching in oxides. In addition, we describe parallel linear and nonlinear conduction pathways and suggest that the conductance quantum, G0, is a natural boundary between the high and low resistance states of our devices.

  19. Structural changes and conductance thresholds in metal-free intrinsic SiOx resistive random access memory

    International Nuclear Information System (INIS)

    Mehonic, Adnan; Buckwell, Mark; Montesi, Luca; Garnett, Leon; Hudziak, Stephen; Kenyon, Anthony J.; Fearn, Sarah; Chater, Richard; McPhail, David

    2015-01-01

    We present an investigation of structural changes in silicon-rich silicon oxide metal-insulator-metal resistive RAM devices. The observed unipolar switching, which is intrinsic to the bulk oxide material and does not involve movement of metal ions, correlates with changes in the structure of the oxide. We use atomic force microscopy, conductive atomic force microscopy, x-ray photoelectron spectroscopy, and secondary ion mass spectroscopy to examine the structural changes occurring as a result of switching. We confirm that protrusions formed at the surface of samples during switching are bubbles, which are likely to be related to the outdiffusion of oxygen. This supports existing models for valence-change based resistive switching in oxides. In addition, we describe parallel linear and nonlinear conduction pathways and suggest that the conductance quantum, G 0 , is a natural boundary between the high and low resistance states of our devices

  20. Structural changes and conductance thresholds in metal-free intrinsic SiO{sub x} resistive random access memory

    Energy Technology Data Exchange (ETDEWEB)

    Mehonic, Adnan, E-mail: a.mehonic@ee.ucl.ac.uk, E-mail: t.kenyon@ucl.ac.uk; Buckwell, Mark; Montesi, Luca; Garnett, Leon; Hudziak, Stephen; Kenyon, Anthony J., E-mail: a.mehonic@ee.ucl.ac.uk, E-mail: t.kenyon@ucl.ac.uk [Department of Electronic and Electrical Engineering, UCL, Torrington Place, London WC1E 7JE (United Kingdom); Fearn, Sarah; Chater, Richard; McPhail, David [Department of Materials, Imperial College London, South Kensington Campus, London SW7 2AZ (United Kingdom)

    2015-03-28

    We present an investigation of structural changes in silicon-rich silicon oxide metal-insulator-metal resistive RAM devices. The observed unipolar switching, which is intrinsic to the bulk oxide material and does not involve movement of metal ions, correlates with changes in the structure of the oxide. We use atomic force microscopy, conductive atomic force microscopy, x-ray photoelectron spectroscopy, and secondary ion mass spectroscopy to examine the structural changes occurring as a result of switching. We confirm that protrusions formed at the surface of samples during switching are bubbles, which are likely to be related to the outdiffusion of oxygen. This supports existing models for valence-change based resistive switching in oxides. In addition, we describe parallel linear and nonlinear conduction pathways and suggest that the conductance quantum, G{sub 0}, is a natural boundary between the high and low resistance states of our devices.

  1. Stabilization of the Resistive Wall Mode and Error Field Reduction by a Rotating Conducting Wall

    Science.gov (United States)

    Paz-Soldan, Carlos

    2011-10-01

    The hypothesis that the Resistive Wall Mode (RWM) can be stabilized by high-speed differentially-rotating conducting walls is tested in a linear device. This geometry allows the use of cylindrical solid metal walls, whereas a torus would require a flowing liquid metal. Experiments over the past year have for the first time explored RWM stability with a rotating copper wall capable of achieving speeds (rΩw) of up to 280 km/h, equivalent to a magnetic Reynolds number (Rm) of 5. The main results are: 1) Wall rotation increases the stability window of the RWM, allowing ~ 25% more plasma current (Ip) at Rm = 5 while maintaining MHD stability. 2) Error field reduction below a critical value allows the observation of initial mode rotation, followed by braking, wall-locking, and subsequent faster growth. 3) Locking is found to depend on the direction of wall rotation (Ω̂w) with respect to the intrinsic plasma rotation, with locking to both the static wall (vacuum vessel) and rotating wall observed. Additionally, indirect effects on RWM stability are observed via the effect of wall rotation on device error fields. Wall rotation shields locking error fields, which reduces the braking torque and inhibits mode-locking. The linear superposition of error fields from guide field (Bz) solenoid misalignments and current-carrying leads is also shown to break symmetry in Ω̂w , with one direction causing stronger error fields and earlier locking irrespective of plasma flow. Vacuum field measurements further show that rotation decreases the error field penetration time and advects the field to a different orientation, as predicted by theory. Experiments are conducted on the Rotating Wall Machine, a 1.2 m long and 16 cm diameter screw-pinch with Bz ~ 500 G, where hollow-cathode injectors are biased to source up to 7 kA of Ip, exciting current-driven RWMs. MHD activity is measured through 120 edge Br, Bθ, Bz probes as well as internal Bdot, Langmuir and Mach probes. RWM

  2. Thermal resistance of rotating closed-loop pulsating heat pipes: Effects of working fluids and internal diameters

    Directory of Open Access Journals (Sweden)

    Kammuang-Lue Niti

    2017-01-01

    Full Text Available The objective of this study was to experimentally investigate the effects of working fluids and internal diameters on the thermal resistance of rotating closed-loop pul¬sating heat pipes (RCLPHP. The RCLPHP were made of a copper tube with internal diameters of 1.50 mm and 1.78 mm, bent into the shape of a flower petal, and arranged into a circle with 11 turns. The evaporator section was located at the outer end of the tube bundle. R123, ethanol, and water were filled as the working fluids. The RCLPHP was rotated at centrifugal accelerations 0.5, 1, 3, 5, 10, and 20 times of the gravitational acceleration considered at the connection between the evaporator and the condenser sections. The heat input was varied from 30 W to 50 W, and then to 100 W, 150 W, and 200 W. It can be concluded that when the latent heat of evaporation increases, the pressure difference between the evaporator and the condenser sections decreases, and the thermal resistance increases. Moreover, when the internal diameter increases, the driving force increases and the frictional force proportionally decreases, or the Karman number increases, and the thermal resistance decreases.

  3. The influence of sulfur on the electrical resistivity of hcp iron: Implications for the core conductivity of Mars and Earth

    Science.gov (United States)

    Suehiro, Sho; Ohta, Kenji; Hirose, Kei; Morard, Guillaume; Ohishi, Yasuo

    2017-08-01

    Cosmochemical and geochemical studies suggest sulfur (S) as a light alloying element in the iron-rich cores of telluric planets, but there is no report of sulfur's alloying effect on the electrical and thermal transport properties of iron (Fe); a subject that is closely related to the dynamo action and thermal evolution of planetary cores. We measured the electrical resistivity of hexagonal-closed-packed (hcp) structured Fe alloy containing 3 wt. % silicon (Si) and 3 wt. % S up to 110 GPa at 300 K. Combined with the reported resistivities of hcp Fe and hcp Fe-Si alloy, we determined the impurity resistivity of S in a hcp Fe matrix at high pressures. The obtained impurity resistivity of S is found to be smaller than that of Si. Therefore, S is a weaker influence on the conductivity of Fe alloy, even if S is a major light element in the planetary cores.

  4. Termination of Vernakalant-Resistant Atrial Fibrillation by Inhibition of Small-Conductance Ca2+-Activated K+ Channels in Pigs

    DEFF Research Database (Denmark)

    Diness, Jonas Goldin; Skibsbye, Lasse; Simó-Vicens, Rafel

    2017-01-01

    Background Evidence has emerged that small-conductance Ca2+-activated K+ (SK) channels constitute a new target for treatment of atrial fibrillation (AF). SK channels are predominantly expressed in the atria as compared with the ventricles. Various marketed antiarrhythmic drugs are limited......-resistant porcine model of AF. These results suggest SK channel blockers as potentially interesting anti-AF drugs....

  5. Effects of temperature dependent conductivity and absorptive/generative heat transfer on MHD three dimensional flow of Williamson fluid due to bidirectional non-linear stretching surface

    Directory of Open Access Journals (Sweden)

    S. Bilal

    Full Text Available Present work is communicated to identify characteristics of magnetohydrodynamic (MHD three dimensional boundary layer flow of Williamson fluid confined by a bidirectional stretched surface. Conductivity of working fluid is assumed to be temperature dependent. Generative/absorptive heat transfer is also taken into account. Mathematical model is formulated in the form of partial expressions and then transmuted into ordinary differential equations with the help of newfangled set of similarity transformations. The resulting non-linear differential system of equations is solved numerically with the aid of Runge-Kutta algorithm supported by shooting method. Flow features are exemplified quantitatively through graphs. Scintillating results for friction factor and convective heat transfer are computed and scrutinized tabularly. Furthermore, the accuracy of present results is tested with existing literature and we found an excellent agreement. It is inferred that velocity along x-direction mounts whereas along y-direction depreciates for incrementing values of stretching ratio parameter. Moreover, it is also elucidated that non-linearity index tends to decrement the velocity and thermal distributions of fluid flow. Keywords: MHD flow, Williamson fluid, Variable thermal conductivity, Heat absorption/generation, Bidirectional non-linear stretching

  6. Bianchi - I, II, VIII, IX and Kantowski-Sachs-like cosmological models with perfect fluid and electromagnetic fields with conductivity current

    International Nuclear Information System (INIS)

    Portugal, R.

    1984-01-01

    Three processes of solutions of the Einstein-Maxwell equations for Bianchi - I, II, VIII, IX and Kantowski-Sachs-like cosmological models with perfect fluid in magnetohydrolodynamical regimem are presented. Diagonal Bianchi-like models are considered with two anisotropy direction in the maximum. Solutions are found for Bianchi-II and IX-like models with energy conditions to be analyzed. Solutions are found for Bianchi-IX and Kantowski-Sachs-Like models with positive electric conductivity and satisfering to the predominant energy conditions. Solutions are formed for isotropic Kantowski-Sachs-Like models satisfering to the equation of state p=λρ, 0 0, admiting, in addition to the perfect fluid, electric field only. It is shown that a class of Bertotti-Robinson-like solutions is unstable by perturbations and it is carried in Kantowski-Sachs-like models with non-null electric conductivity. (L.C.) [pt

  7. Features of Calculation of the Equation of State, Composition, and Conductivity for a Plasma of Dense, Supercritical Metal Vapors—a Plasma Fluid

    Science.gov (United States)

    Khomkin, A. L.; Shumikhin, A. S.

    2017-12-01

    The caloric and thermal equations of state, composition, and conductivity have been calculated for a supercritical aluminum plasma fluid. A previously proposed chemical plasma model called the "3+"-component one was used for the calculations. The model includes atoms, electrons, ions, and an electron jellium. The thermodynamic functions have been calculated for the first time within the "3+" model for a plasma fluid. The magnification and compensation of intercharge and interatomic interactions when calculating the equation of state and composition are analyzed. The introduction of the jellium leads to an increase in conductivity under compression, while the compensation of interactions when calculating the composition leads to a virtually ideal-gas behavior of the equation of state. Comparison with the data from physical and numerical experiments has confirmed our conclusions and demonstrated that the hypothesis about jellium, a new gas-plasma component, is constructive.

  8. Synthesis and Characterization of Mixed-Conducting Corrosion Resistant Oxide Supports

    Energy Technology Data Exchange (ETDEWEB)

    Ramani, Vijay K. [Washington Univ., St. Louis, MO (United States)

    2015-01-31

    /C and Pt/RTO cathode catalyst layers were 150 and 12 mΩ-cm2, respectively. Pt/RTO catalyst layer has about an order or magnitude lower proton transfer resistance than Pt/C catalyst layer. Since the ionomer/support ratio that was used in formulating the ink for both catalysts was the same (0.9), it is expected that the volumetric coverage of ionomer of both catalysts will be significantly different due to the disparity in the surface areas (Pt/C had ~ 800 m2/g, while Pt/RTO had ~ 50 m2/g). The differences in the ionomer volumetric coverage and the ionomer film thickness may explain the significantly higher proton conductivity in the Pt/RTO catalyst layer when compared to Pt/HSAC. It is therefore very important to optimize the ionomer loadings when synthesizing new catalyst supports (and never rely on values for carbon-based commercial catalysts). Finally, NTCNA has elaborated a cost model for non-carbon support materials considering their durability benefits. Material costs for production of Pt/ RuO2-TiO2 electrodes were compared to Pt/C. RuO2-TiO2 support was more expensive than carbon but the total material cost was still dominated by platinum cost. Though ruthenium is considered a precious metal, its cost is far less than platinum. It should also be noted that ruthenium only makes up 38% of the mass of the support, while the rest is inexpensive TiO2. After considering the durability advantages of Pt/RTO, cost model showed that even with almost double the Pt loading (0.35 vs 0.18 mgPt/cm2), Pt/RTO ($22.7/kWnet) is only slightly more expensive than Pt/C ($21.9/kWnet).

  9. Penicillin resistance is not extrapolable to amoxicillin resistance in Streptococcus pneumoniae isolated from middle ear fluid in children with acute otitis media.

    Science.gov (United States)

    Rosenblüt, Andrés; Santolaya, María Elena; Gonzalez, Patricia; Borel, Cecilia; Cofré, José

    2006-03-01

    We evaluated the in vitro antibacterial activity of amoxicillin against penicillin-susceptible and -nonsusceptible Streptococcus pneumoniae strains isolated from children with acute otitis media (AOM). Children more than 3 months of age with AOM who were seen in the Dr Sótero del Rio and Luis Calvo Mackenna Hospitals in Santiago, Chile, between July 1998 and December 2002 were subjected to tympanic puncture for middle ear fluid culture. The penicillin and amoxicillin susceptibilities of the S pneumoniae isolates were determined by epsilometer test (E test). A bacterial pathogen was isolated in 432 of 543 children (80%) as follows: S pneumoniae, 40%; Haemophilus influenzae, 29%; Moraxella catarrhalis, 7%; and Streptococcus pyogenes, 4%. Penicillin-susceptible S pneumoniae strains were less common than amoxicillin-susceptible strains (60% versus 95%; odds ratio [OR], 0.08; 95% confidence interval [CI], 0.04 to 0.18). Both intermediate- and high-resistance strains were more common for penicillin (22% versus 4.5%; OR, 5.6; 95% CI, 2.5 to 12.7) than for amoxicillin (18% versus 0.5%; OR, 41.3; 95% CI, 6.0 to 821). Penicillin resistance is not extrapolable to amoxicillin among S pneumoniae strains isolated from middle ear fluid of children with AOM. Our results support the recommendation to evaluate the minimal inhibitory concentrations of penicillin-nonsusceptible S pneumoniae for amoxicillin and to continue use of this antimicrobial as a first-line antimicrobial choice for children with AOM.

  10. Analysis of Printing Substrate, Ink Age and Number of IR Drying Influence on Electrical Resistance of Conductive Inks

    Directory of Open Access Journals (Sweden)

    Josip Jerić

    2015-05-01

    Full Text Available As a result of availability of new technologies, functional printing as a segment has become one of the most interesting directions of research and development in graphic technology. Conductive inks are not a novelty and they already have broad possibilities in production of everyday products. There is still a big market for the broadening of their use, as well as a possibility of further enhancing their properties. This paper analyzes the influence of printing substrate, age of ink and the number of IR drying on the electrical resistance of the conductive inks. In the paper, subject of analysis was the change of electrical resistance in the line that was 9 cm long and 10 typographic points wide. The semi-automated screen-printing machine was used for printing. Three types of printing substrates were used; uncoated, coated and recycled paper. Two types of inks were used; newly opened ink and ink that was out of date for half year. After the printing, prints were dried using the IR dryer. Prints were dried once, and then additional three times. After the first and last drying, multimeter was used to measure electrical resistance of the lines. Analysis of the data shows that the older ink produces prints with higher electrical resistance. There are also notable differences in the electrical resistance based on the printing substrate.

  11. A Review on Resistive Switching in High-k Dielectrics: A Nanoscale Point of View Using Conductive Atomic Force Microscope

    Directory of Open Access Journals (Sweden)

    Mario Lanza

    2014-03-01

    Full Text Available Metal-Insulator-Metal (MIM structures have raised as the most promising configuration for next generation information storage, leading to great performance and fabrication-friendly Resistive Random Access Memories (RRAM. In these cells, the memory concept is no more based on the charge storage, but on tuning the electrical resistance of the insulating layer by applying electrical stresses to reach a high resistive state (HRS or “0” and a low resistive state (LRS or “1”, which makes the memory point. Some high-k dielectrics show this unusual property and in the last years high-k based RRAM have been extensively analyzed, especially at the device level. However, as resistance switching (in the most promising cells is a local phenomenon that takes place in areas of ~100 nm2, the use of characterization tools with high lateral spatial resolution is necessary. In this paper the status of resistive switching in high-k materials is reviewed from a nanoscale point of view by means of conductive atomic force microscope analyses.

  12. Investigation of the magnetic neutral line region with the frame of two-fluid equations: A possibility of anomalous resistivity inferred from MMS observations

    Science.gov (United States)

    Kobayashi, Y.; Kitamura, N.; Ieda, A.; Yoshizumi, M.; Imada, S.; Tsugawa, Y.; Burch, J. L.; Russell, C. T.; Moore, T. E.; Giles, B. L.; Paterson, W.; Torbert, R. B.; Ergun, R.; Saito, Y.; Yokota, S.; Machida, S.

    2017-12-01

    Magnetic reconnection is a basic physical process by which energy of magnetic field is converted into the kinetic energy of plasmas. In recent years, MMS missionconsisting of four spacecraft has been conducted aiming at elucidating the physical mechanism of merging themagnetic fields in the vicinity of the magnetic neutral linethat exists in the central part of the structure. In this paper, we examine the magnetic field frozen-in relation near the magnetic neutral line as well as the causal relationship between electron and ion dynamics in the frame of two fluid equations.Theoretically, it is shown that electrons are frozen-in to the magnetic fields while ion's frozen-in relation is broken in the ion dissipation region. However, when we examined the observational data around 1307 UT on October 16, 2015 when MMS spacecraft passed through the vicinity of the magnetic neutral line [Burch et al., Science 2016] , it was confirmed that the frozen-ion relation was not established for electrons in the ion dissipation region. In addition, we found that intense wave electric fields in this region. From the spectral analysis of the waves, it turned out that their characteristic frequencies are the lower-hybrid and electron cyclotron frequencies.In the framework of the two-fluid equation, we can evaluate the values of each term of the equations of motion for both ions and electrons except for the collision term from MMS spacecraft data. Therefore, it is possible to obtain collision terms for both species. Since magnetospheric plasma is basically collisionless, it is considered that the collision term is due to anomalous resistivity associated with the excited waves . On the other hand, in the two-fluid equation system, the two vectors corresponding to the collision terms of ions and electrons have the same absolute value. Because the force exerted between the two is the internal force, they should face in the opposite direction. However, the vectors corresponding to the

  13. A reversible, non-invasive method for airway resistance measurements and bronchoalveolar lavage fluid sampling in mice.

    Science.gov (United States)

    Polikepahad, Sumanth; Barranco, Wade T; Porter, Paul; Anderson, Bruce; Kheradmand, Farrah; Corry, David B

    2010-04-13

    Airway hyperreactivity (AHR) measurements and bronchoalveolar lavage (BAL) fluid sampling are essential to experimental asthma models, but repeated procedures to obtain such measurements in the same animal are generally not feasible. Here, we demonstrate protocols for obtaining from mice repeated measurements of AHR and bronchoalveolar lavage fluid samples. Mice were challenged intranasally seven times over 14 days with a potent allergen or sham treated. Prior to the initial challenge, and within 24 hours following each intranasal challenge, the same animals were anesthetized, orally intubated and mechanically ventilated. AHR, assessed by comparing dose response curves of respiratory system resistance (RRS) induced by increasing intravenous doses of acetylcholine (Ach) chloride between sham and allergen-challenged animals, were determined. Afterwards, and via the same intubation, the left lung was lavaged so that differential enumeration of airway cells could be performed. These studies reveal that repeated measurements of AHR and BAL fluid collection are possible from the same animals and that maximal airway hyperresponsiveness and airway eosinophilia are achieved within 7-10 days of initiating allergen challenge. This novel technique significantly reduces the number of mice required for longitudinal experimentation and is applicable to diverse rodent species, disease models and airway physiology instruments.

  14. Assessing thermal conductivity of composting reactor with attention on varying thermal resistance between compost and the inner surface.

    Science.gov (United States)

    Wang, Yongjiang; Niu, Wenjuan; Ai, Ping

    2016-12-01

    Dynamic estimation of heat transfer through composting reactor wall was crucial for insulating design and maintaining a sanitary temperature. A model, incorporating conductive, convective and radiative heat transfer mechanisms, was developed in this paper to provide thermal resistance calculations for composting reactor wall. The mechanism of thermal transfer from compost to inner surface of structural layer, as a first step of heat loss, was important for improving insulation performance, which was divided into conduction and convection and discussed specifically in this study. It was found decreasing conductive resistance was responsible for the drop of insulation between compost and reactor wall. Increasing compost porosity or manufacturing a curved surface, decreasing the contact area of compost and the reactor wall, might improve the insulation performance. Upon modeling of heat transfers from compost to ambient environment, the study yielded a condensed and simplified model that could be used to conduct thermal resistance analysis for composting reactor. With theoretical derivations and a case application, the model was applicable for both dynamic estimation and typical composting scenario. Copyright © 2016 Elsevier Ltd. All rights reserved.

  15. On the thermal convection in a viscoelastic Jeffreys fluid layer heated from below confined between walls of finite thickness and thermal conductivity

    Science.gov (United States)

    Pérez-Reyes, Ildebrando; Vargas-Aguilar, René O.

    2016-11-01

    The thickness and thermal conductivity of the bounding walls are of interest in the hydrodynamic stability of a viscoelastic fluid layer. In this work the linear hydrodynamic stability is studied by means of the Galerkin method. The two ideal cases of thermal insulating and perfect thermal conducting walls are bridged by taking into account these two properties. Curves of criticality for the Rayleigh number, the wavenumber and the frequency of oscillation against the thermal conductivity for fixed wall thickness, Prandtl number and relaxation and retardation times are presented. Here, the dimensionless retardation time E was set to 0.05 and 0.1 while the dimensionless relaxation time F was set to 0.1 and 100. The role of the thermal conductivity and of the thickness of the walls are discussed. One important result of this investigation is that for non ideal thermal conducting conditions the system is more stable when the thickness of the fluid layer is larger in comparison to that of the boundaries. A discussion on the effect of E and F on the stability is given as well. Ciencia Básica - Conacyt through Project No. 255839.

  16. Designing CO2-resistant oxygen-selective mixed ionic-electronic conducting membranes: guidelines, recent advances, and forward directions.

    Science.gov (United States)

    Zhang, Chi; Sunarso, Jaka; Liu, Shaomin

    2017-05-22

    CO 2 resistance is an enabling property for the wide-scale implementation of oxygen-selective mixed ionic-electronic conducting (MIEC) membranes in clean energy technologies, i.e., oxyfuel combustion, clean coal energy delivery, and catalytic membrane reactors for greener chemical synthesis. The significant rise in the number of studies over the past decade and the major progress in CO 2 -resistant MIEC materials warrant systematic guidelines on this topic. To this end, this review features the pertaining aspects in addition to the recent status and advances of the two most promising membrane materials, perovskite and fluorite-based dual-phase materials. We explain how to quantify and design CO 2 resistant membranes using the Lewis acid-base reaction concept and thermodynamics perspective and highlight the relevant characterization techniques. For perovskite materials, a trade-off generally exists between CO 2 resistance and O 2 permeability. Fluorite materials, despite their inherent CO 2 resistance, typically have low O 2 permeability but this can be improved via different approaches including thin film technology and the recently developed minimum internal electronic short-circuit second phase and external electronic short-circuit decoration. We then elaborate the two main future directions that are centralized around the development of new oxide compositions capable of featuring simultaneously high CO 2 resistance and O 2 permeability and the exploitation of phase reactions to create a new conductive phase along the grain boundaries of dual-phase materials. The final part of the review discusses various complimentary characterization techniques and the relevant studies that can provide insights into the degradation mechanism of oxide-based materials upon exposure to CO 2 .

  17. Acyclovir-resistant herpes simplex virus type 1 in intra-ocular fluid samples of herpetic uveitis patients.

    Science.gov (United States)

    van Velzen, Monique; Missotten, Tom; van Loenen, Freek B; Meesters, Roland J W; Luider, Theo M; Baarsma, G Seerp; Osterhaus, Albert D M E; Verjans, Georges M G M

    2013-07-01

    Acyclovir (ACV) is the antiviral drug of choice to treat patients with herpes simplex virus type 1 (HSV-1) uveitis. The prevalence of intra-ocular ACV-resistant (ACV(R)) HSV-1 in herpetic uveitis is unknown and may have clinical consequences. In addition to its predictive value on ACV susceptibility, the polymorphic HSV-1 thymidine kinase (TK) gene facilitates differentiation between HSV-1 strains. The objective of this study was to determine the genetic composition and ACV susceptibility of the causative virus in intra-ocular fluid samples (IOF) of HSV-1 uveitis patients. The intra-ocular HSV-1 pool from 11 HSV-1 uveitis patients was determined by sequencing IOF-derived viral TK genes. The ACV susceptibility profile of the cloned intra-ocular TK variants was defined by mass spectrometry. In addition, the ganciclovir (GCV) susceptibility of the ACV(R) HSV-1 TK variants was defined. Intra-ocular fluid samples of HSV-1 uveitis patients contain HSV-1 quasispecies, principally consisting of one major and multiple genetically related minor patient-specific TK variants. Four of 10 patients analyzed had an intra-ocular ACV(R) HSV-1 of which 3 were cross-resistant to GCV. The ACV(R) profile of intra-ocular HSV-1 did not correlate with symptomatic ACV treatment. Affected eyes of HSV-1 uveitis patients are commonly infected with a patient-specific HSV-1 quasispecies, including one major and multiple genetically related minor variants. A relatively high prevalence of intra-ocular ACV(R) HSV-1, mainly ACV/GCV cross-resistant viruses, was detected in HSV-1 uveitis patients. Copyright © 2013 Elsevier B.V. All rights reserved.

  18. Development and Life Prediction of Erosion Resistant Turbine Low Conductivity Thermal Barrier Coatings

    Science.gov (United States)

    Zhu, Dongming; Miller, Robert A.; Kuczmarski, Maria A.

    2010-01-01

    Future rotorcraft propulsion systems are required to operate under highly-loaded conditions and in harsh sand erosion environments, thereby imposing significant material design and durability issues. The incorporation of advanced thermal barrier coatings (TBC) in high pressure turbine systems enables engine designs with higher inlet temperatures, thus improving the engine efficiency, power density and reliability. The impact and erosion resistance of turbine thermal barrier coating systems are crucial to the turbine coating technology application, because a robust turbine blade TBC system is a prerequisite for fully utilizing the potential coating technology benefit in the rotorcraft propulsion. This paper describes the turbine blade TBC development in addressing the coating impact and erosion resistance. Advanced thermal barrier coating systems with improved performance have also been validated in laboratory simulated engine erosion and/or thermal gradient environments. A preliminary life prediction modeling approach to emphasize the turbine blade coating erosion is also presented.

  19. Differential conductance measurements of low-resistance CoFeB/MgO/CoFeB magnetic tunnel junctions

    International Nuclear Information System (INIS)

    Nishioka, S.; Hamada, Y.V.; Matsumoto, R.; Mizuguchi, M.; Shiraishi, M.; Fukushima, A.; Kubota, H.; Nagahama, T.; Yuasa, S.; Maehara, H.; Nagamine, Y.; Tsunekawa, K.; Djayaprawira, D.D.; Watanabe, N.; Suzuki, Y.

    2007-01-01

    We measured differential conductance spectra of magnetic tunnel junctions (MTJs) with thin MgO barrier and low-resistance area product. The spectra of MTJs with MgO barrier thicker than 1.05 nm were essentially the same except for slight decrease of contributions from low-energy excitations, such as magnons. The spectra of MTJ with 1.01 nm MgO barrier were thoroughly different from the MTJs with thicker barrier. The result reveals that an MTJ with very thin MgO barrier thickness has different conduction characteristics from those with thicker MgO barriers

  20. Numerical experiments on thermal convection of highly compressible fluids with variable viscosity and thermal conductivity: Implications for mantle convection of super-Earths

    Science.gov (United States)

    Kameyama, Masanori; Yamamoto, Mayumi

    2018-01-01

    We conduct a series of numerical experiments of thermal convection of highly compressible fluids in a two-dimensional rectangular box, in order to study the mantle convection on super-Earths. The thermal conductivity and viscosity are assumed to exponentially depend on depth and temperature, respectively, while the variations in thermodynamic properties (thermal expansivity and reference density) with depth are taken to be relevant for the super-Earths with 10 times the Earth's. From our experiments we identified a distinct regime of convecting flow patterns induced by the interplay between the adiabatic temperature change and the spatial variations in viscosity and thermal conductivity. That is, for the cases with strong temperature-dependent viscosity and depth-dependent thermal conductivity, a "deep stratosphere" of stable thermal stratification is formed at the base of the mantle, in addition to thick stagnant lids at their top surfaces. In the "deep stratosphere", the fluid motion is insignificant particularly in the vertical direction in spite of smallest viscosity owing to its strong dependence on temperature. Our finding may further imply that some of super-Earths which are lacking in mobile tectonic plates on their top surfaces may have "deep stratospheres" at the base of their mantles.

  1. Effect of Electrical Contact Resistance on Measurement of Thermal Conductivity and Wiedemann-Franz Law for Individual Metallic Nanowires.

    Science.gov (United States)

    Wang, Jianli; Wu, Zhizheng; Mao, Chengkun; Zhao, Yunfeng; Yang, Juekuan; Chen, Yunfei

    2018-03-20

    The electrical and thermal properties of metallic nanostructures have attracted considerable fundamental and technological interests. Recent studies confirmed a dramatic decrease in the electrical and thermal conductivities when the dimension is comparable or even smaller than the electron mean free path. However, the verification of the Wiedemann-Franz law in these nanostructures remains hotly debated. The Lorenz number obtained from the two-probe measurement is found to be much larger than that from the four-probe measurement. Here, we reported the electrical and thermal properties of the individual silver nanowires measured by the two-probe and four-probe configurations. The measured electrical contact resistance is found to be nearly temperature-independent, indicating a ballistic-dominant electronic transport at the contacts. When the effect of thermal contact resistance is diminished, the Lorenz number measured by the four-probe configuration is comparable to the Sommerfeld value, verifying that the Wiedemann-Franz law holds in the monocrystalline-like silver nanowire. Comparatively, the derived electrical conductivity becomes smaller and the thermal conductivity becomes larger in the two-probe measurement, confirming that the electrical contact resistance will introduce a large error. The present study experimentally demonstrates a reasonable explanation to the discouragingly broad span in the Lorenz number obtained from different metallic nanostructures.

  2. Technology of Processing of Fluorol with Metallic Oxides and It's Resistance toward Active Fluid

    International Nuclear Information System (INIS)

    Mahmoud, G.M.; Hadhoud, M.K.; Mohamed, A.Z.; Sherif, S.A

    2004-01-01

    Fluorocarbon polymers are the best elastomers for a variety of applications. In this work we investigate the characteristics of fluorocarbon rubber for use in different applications, via preparation different formulations. We investigate the effect of added metallic oxides ( CaO, MgO, ZnO and PbO ) on the chemical and physical properties of prepared formulations. Chemical resistance tests were made for conc. H 2 SO 4 , conc. HCl, conc. HNO 3 , ASTM Oil No.2, ASTM Ref. Fuel C and conc. NaOH solution. Results showed that the prepared fluorocarbon rubber have high chemical resistance to various acids, alkalis, oils and fuels, also chemical resistance towards conc. HNO 3 is enhanced in the presence of lead oxide

  3. Magnetohydrodynamic thin film and heat transfer of power law fluids over an unsteady stretching sheet with variable thermal conductivity

    Directory of Open Access Journals (Sweden)

    Lin Yanhai

    2016-01-01

    Full Text Available This paper presents an investigation on the MHD thin film flow and heat transfer of a power law fluid over an unsteady stretching sheet. The effects of power law viscosity on a temperature field are taken into account with a modified Fourier’s law Proposed by Zheng by assuming that the temperature field is similar to the velocity field. The governing equations are reduced to a system of nonlinear ordinary differential equations. The numerical solutions are obtained by using the shooting method coupled with the Runge-Kutta method. The influence of the Hartmann number, the power law exponent, the unsteadiness parameter, the thickness parameter and the generalized Prandtl number on the velocity and temperature fields are presented graphically and analyzed. Moreover, the critical formula for parameters are derived which indicated that the magnetic field has no effect on the critical value.

  4. Fracture Network and Fluid Flow Imaging for Enhanced Geothermal Systems Applications from Multi-Dimensional Electrical Resistivity Structure

    Energy Technology Data Exchange (ETDEWEB)

    Wannamaker, Philip E. [Univ. of Utah, Salt Lake City, UT (United States)

    2016-03-26

    We have developed an algorithm for the inversion of magnetotelluric (MT) data to a 3D earth resistivity model based upon the finite element method. Hexahedral edge finite elements are implemented to accommodate discontinuities in the electric field across resistivity boundaries, and to accurately simulate topographic variations. All matrices are reduced and solved using direct solution modules which avoids ill-conditioning endemic to iterative solvers such as conjugate gradients, principally PARDISO for the finite element system and PLASMA for the parameter step estimate. Large model parameterizations can be handled by transforming the Gauss-Newton estimator to data-space form. Accuracy of the forward problem and jacobians has been checked by comparison to integral equations results and by limiting asymptotes. Inverse accuracy and performance has been verified against the public Dublin Secret Test Model 2 and the well-known Mount St Helens 3D MT data set. This algorithm we believe is the most capable yet for forming 3D images of earth resistivity structure and their implications for geothermal fluids and pathways.

  5. Horizontal coring using air as the circulating fluid: Some prototype studies conducted in G Tunnel at the Nevada Test Site for the Yucca Mountain Project

    International Nuclear Information System (INIS)

    Chornack, M.P.; French, C.A.

    1989-01-01

    Horizontal coring using air as the circulating fluid has been conducted in the G Tunnel Underground Facility (GTUF) at the Nevada Test Site. This work is part of the prototype investigations of hydrogeology for the Yucca Mountain Project. The work is being conducted to develop methods and procedures that will be used at the Department of Energy's Yucca Mountain Site, a candidate site for the nation's first high-level nuclear waste repository, during the site characterization phase of the investigations. The United States Geological Survey (USGS) is conducting this prototype testing under the guidance of the Los Alamos National Laboratory (LANL) and in conjunction with Reynolds Electrical ampersand Engineering Company (REECo), the drilling contractor. 7 refs., 8 figs., 5 tabs

  6. Surfaces resistant to fouling from biological fluids: towards bioactive surfaces for real applications

    Czech Academy of Sciences Publication Activity Database

    Rodriguez-Emmenegger, Cesar; Houska, Milan; Bologna Alles, A.; Brynda, Eduard

    2012-01-01

    Roč. 12, č. 10 (2012), s. 1413-1422 ISSN 1616-5187 R&D Projects: GA ČR GAP205/12/1702; GA ČR GAP106/12/1451; GA ČR GAP503/10/0664; GA ČR GBP205/12/G118 Institutional research plan: CEZ:AV0Z40500505 Institutional support: RVO:61389013 Keywords : affinity biosensors * blood plasma * cerebrospinal fluid Subject RIV: CD - Macromolecular Chemistry Impact factor: 3.742, year: 2012

  7. Improvement of corrosion resistance of transparent conductive multilayer coating consisting of silver layers and transparent metal oxide layers

    International Nuclear Information System (INIS)

    Koike, Katsuhiko; Yamazaki, Fumiharu; Okamura, Tomoyuki; Fukuda, Shin

    2007-01-01

    An optical filter for plasma display panel (PDP) requires an electromagnetic shield with very high ability. The authors investigated a transparent conductive multilayer coating consisting of silver (Ag) layers and transparent metal oxide layers. The durability of the multilayer sputter coating, including the silver layer, is very sensitive to the surrounding atmosphere. For example, after an exposure test they found discolored points on the multilayer sputter coatings, possibly caused by migration of silver atoms in the silver layers. In their investigation, they modified the top surface of the multilayer sputter coatings with transition metals to improve the corrosion resistance of the multilayer coating. Specifically, they deposited transition metals 0.5-2 nm thick on the top surface of the multilayer coatings by sputtering. They chose indium tin oxide (ITO) as the transparent metal oxide. They applied the multilayer sputter coatings of seven layers to a polyethylene terephthalate (PET) film substrate. A cross-sectional structure of the film with the multilayer coatings is PET film/ITO/Ag/ITO/Ag/ITO/Ag/ITO. They evaluated the corrosion resistance of the films by a salt-water immersion test. In the test, they immersed the film with multilayer coatings into salt water, and then evaluated the appearance, transmittance, and electrical resistance of the multilayer coatings. They investigated several transition metals as the modifying material, and found that titanium and tantalum drastically improved the resistance of the multilayer coatings to the salt-water exposure without a significant decline in transmittance. They also investigated the relation between elapsed time after deposition of the modifying materials and resistance to the salt water. Furthermore, they investigated the effects of a heat treatment and an oxide plasma treatment on resistance to the salt water

  8. Thermally stratified flow of second grade fluid with non-Fourier heat flux and temperature dependent thermal conductivity

    Science.gov (United States)

    Khan, M. Ijaz; Zia, Q. M. Zaigham; Alsaedi, A.; Hayat, T.

    2018-03-01

    This attempt explores stagnation point flow of second grade material towards an impermeable stretched cylinder. Non-Fourier heat flux and thermal stratification are considered. Thermal conductivity dependents upon temperature. Governing non-linear differential system is solved using homotopic procedure. Interval of convergence for the obtained series solutions is explicitly determined. Physical quantities of interest have been examined for the influential variables entering into the problems. It is examined that curvature parameter leads to an enhancement in velocity and temperature. Further temperature for non-Fourier heat flux model is less than Fourier's heat conduction law.

  9. Literature survey of heat transfer and hydraulic resistance of water, carbon dioxide, helium and other fluids at supercritical and near-critical pressures

    Energy Technology Data Exchange (ETDEWEB)

    Pioro, I.L.; Duffey, R.B

    2003-04-01

    This survey consists of 430 references, including 269 Russian publications and 161 Western publications devoted to the problems of heat transfer and hydraulic resistance of a fluid at near-critical and supercritical pressures. The objective of the literature survey is to compile and summarize findings in the area of heat transfer and hydraulic resistance at supercritical pressures for various fluids for the last fifty years published in the open Russian and Western literature. The analysis of the publications showed that the majority of the papers were devoted to the heat transfer of fluids at near-critical and supercritical pressures flowing inside a circular tube. Three major working fluids are involved: water, carbon dioxide, and helium. The main objective of these studies was the development and design of supercritical steam generators for power stations (utilizing water as a working fluid) in the 1950s, 1960s, and 1970s. Carbon dioxide was usually used as the modeling fluid due to lower values of the critical parameters. Helium, and sometimes carbon dioxide, were considered as possible working fluids in some special designs of nuclear reactors. (author)

  10. Modelling of tetracycline resistance gene transfer by commensal Escherichia coli food isolates that survived in gastric fluid conditions.

    Science.gov (United States)

    Hwang, Daekeun; Kim, Seung Min; Kim, Hyun Jung

    2017-01-01

    Antimicrobial resistance (AR) is a major public health concern and a food safety issue worldwide. Escherichia coli strains, indicators of antibiotic resistance, are a source of horizontal gene transfer to other bacteria in the human intestinal system. A probabilistic exposure model was used to estimate the transfer of the AR gene tet(A). The acid resistance and kinetic behaviour of E. coli was analysed as a function of pH to describe the inactivation of E. coli in simulated gastric fluid (SGF), the major host barrier against exogenous micro-organisms. The kinetic parameters of microbial inactivation in SGF were estimated using GInaFiT, and log-linear + tail and Weibull models were found to be suitable for commensal and enterohaemorrhagic E. coli (EHEC), respectively. A probabilistic exposure model was developed to estimate E. coli survival in gastric pH conditions as well as gene transfer from resistant to susceptible cells in humans. E. coli-contaminated retail foods for consumption without further cooking and gastric pH data in South Korea were considered as an example. The model predicts that 22-33% of commensal E. coli can survive under gastric pH conditions of Koreans. The estimated total mean tet(A) transfer level by commensal E. coli was 1.68 × 10 -4 -8.15 × 10 -4 log CFU/mL/h. The inactivation kinetic parameters of E. coli in SGF and the quantitative exposure model can provide useful information regarding risk management options to control the spread of AR. Copyright © 2016 Elsevier B.V. and International Society of Chemotherapy. All rights reserved.

  11. Testing hypotheses that link wood anatomy to cavitation resistance and hydraulic conductivity in the genus Acer

    NARCIS (Netherlands)

    Lens, F.; Sperry, J.S.; Christmas, M.A.; Rabaey, D.; Jansen, S.

    2011-01-01

    • Vulnerability to cavitation and conductive efficiency depend on xylem anatomy. We tested a large range of structure–function hypotheses, some for the first time, within a single genus to minimize phylogenetic ‘noise’ and maximize detection of functionally relevant variation. • This integrative

  12. The iron and cerium oxide influence on the electric conductivity and the corrosion resistance of anodized aluminium

    International Nuclear Information System (INIS)

    Souza, Kellie Provazi de

    2006-01-01

    The influence of different treatments on the aluminum system covered with aluminum oxide is investigated. The aluminum anodization in sulphuric media and in mixed sulphuric and phosphoric media was used to alter the corrosion resistance, thickness, coverage degree and microhardness of the anodic oxide. Iron electrodeposition inside the anodic oxide was used to change its electric conductivity and corrosion resistance. Direct and pulsed current were used for iron electrodeposition and the Fe(SO 4 ) 2 (NH 4 ) 2 .6H 2 O electrolyte composition was changed with the addition of boric and ascorbic acids. To the sealing treatment the CeCl 3 composition was varied. The energy dispersive x-ray (EDS), the x-ray fluorescence spectroscopy (FRX) and the morphologic analysis by scanning electronic microscopy (SEM) allowed to verify that, the pulsed current increase the iron content inside the anodic layer and that the use of the additives inhibits the iron oxidation. The chronopotentiometric curves obtained during iron electrodeposition indicated that the boric and ascorbic acids mixture increased the electrodeposition process efficiency. The electrochemical impedance spectroscopy (EIE), the Vickers (Hv) microhardness measurements and morphologic analysis evidenced that the sealing treatment improves the corrosion resistance of the anodic film modified with iron. The electrical impedance (EI) technique allowed to prove the electric conductivity increase of the anodized aluminum with iron electrodeposited even after the cerium low concentration treatment. Iron nanowires were prepared by using the anodic oxide pores as template. (author)

  13. Design and Performance Optimizations of Advanced Erosion-Resistant Low Conductivity Thermal Barrier Coatings for Rotorcraft Engines

    Science.gov (United States)

    Zhu, Dongming; Miller, Robert A.; Kuczmarski, Maria A.

    2012-01-01

    Thermal barrier coatings will be more aggressively designed to protect gas turbine engine hot-section components in order to meet future rotorcraft engine higher fuel efficiency and lower emission goals. For thermal barrier coatings designed for rotorcraft turbine airfoil applications, further improved erosion and impact resistance are crucial for engine performance and durability, because the rotorcraft are often operated in the most severe sand erosive environments. Advanced low thermal conductivity and erosion-resistant thermal barrier coatings are being developed, with the current emphasis being placed on thermal barrier coating toughness improvements using multicomponent alloying and processing optimization approaches. The performance of the advanced thermal barrier coatings has been evaluated in a high temperature erosion burner rig and a laser heat-flux rig to simulate engine erosion and thermal gradient environments. The results have shown that the coating composition and architecture optimizations can effectively improve the erosion and impact resistance of the coating systems, while maintaining low thermal conductivity and cyclic oxidation durability

  14. Numerical solution of Williamson fluid flow past a stretching cylinder and heat transfer with variable thermal conductivity and heat generation/absorption

    Directory of Open Access Journals (Sweden)

    M. Y. Malik

    2016-03-01

    Full Text Available In this article, Williamson fluid flow and heat transfer over a stretching cylinder is discussed. The thermal conductivity is assumed to be vary linearly with temperature. Heat generation/absorption effects are also taken into account. Modeled partial differential equations are converted into ordinary differential form by using appropriate transformations. Shooting method in conjunction with Runge-Kutta-Fehlberg method is used to find the solution of the problem. Moreover, the effects of different flow parameters γ, λ, ϵ, β and Pr on velocity and temperature profiles are shown graphically. Local Nusselt number and skin friction coefficient are shown in tabular and graphical form.

  15. Conducting atomic force microscopy studies on doped CulnO2 thin films for resistive memory device applications

    International Nuclear Information System (INIS)

    Mehta, B.R.

    2009-01-01

    Full text: Delafosite thin films have interesting structural, optical and electronic properties due to the highly anisotropic crystal structure and possibility of bipolar conductivity. In this presentation, optical, structural and electrical properties of Sn (n type) and Ca (p type) doped CulnO 2 layers grown by rf magnetron sputtering technique will be discussed. Depending on doping and deposition temperature, these films show nanocolumnar structure with (110) and (006) preferred orientations. The observed decrease in activation energy from 0.9 eV to about 0.10 eV and a large decrease in conductivity from 2.11 x 10 -10 Scm -1 to 1.66 x 10 -1 Scm -1 on Sn doping has been explained due to the change in preferred orientation along with efficient doping. Our results show that crystallite orientation is the most important factor controlling the electrical conduction in delafossite thin films. The anisotropy of electrical conduction along (006) and (110) directions in tin doped samples has been further established using conducting atomic force microscopy (CAFM) measurements. The CAFM measurements shows the presence of nanoconducting region when the current flow direction is aligned along the BO 6 layer and complete absence of conducting regions when the current direction is perpendicular to the film surface. Resistive memory devices based on Sn and Ca doped CulnO 2 films show stable and reproducible 'on' and 'off' states. CAFM measurement on these devices carried out before and after 'forming' show the growth of nanoconducting filaments on the application of a threshold voltage. It is possible to control resistance in the 'on' and 'off' states and magnitude of the forming and switching voltages by controlling the doping concentration and crystallite orientation in CulnO 2 layers

  16. Effects of temperature dependent conductivity and absorptive/generative heat transfer on MHD three dimensional flow of Williamson fluid due to bidirectional non-linear stretching surface

    Science.gov (United States)

    Bilal, S.; Khalil-ur-Rehman; Malik, M. Y.; Hussain, Arif; Khan, Mair

    Present work is communicated to identify characteristics of magnetohydrodynamic (MHD) three dimensional boundary layer flow of Williamson fluid confined by a bidirectional stretched surface. Conductivity of working fluid is assumed to be temperature dependent. Generative/absorptive heat transfer is also taken into account. Mathematical model is formulated in the form of partial expressions and then transmuted into ordinary differential equations with the help of newfangled set of similarity transformations. The resulting non-linear differential system of equations is solved numerically with the aid of Runge-Kutta algorithm supported by shooting method. Flow features are exemplified quantitatively through graphs. Scintillating results for friction factor and convective heat transfer are computed and scrutinized tabularly. Furthermore, the accuracy of present results is tested with existing literature and we found an excellent agreement. It is inferred that velocity along x-direction mounts whereas along y-direction depreciates for incrementing values of stretching ratio parameter. Moreover, it is also elucidated that non-linearity index tends to decrement the velocity and thermal distributions of fluid flow.

  17. Hypercapnia modulates cAMP signalling and cystic fibrosis transmembrane conductance regulator‐dependent anion and fluid secretion in airway epithelia

    Science.gov (United States)

    Turner, Mark J.; Saint‐Criq, Vinciane; Patel, Waseema; Ibrahim, Salam H.; Verdon, Bernard; Ward, Christopher; Garnett, James P.; Tarran, Robert; Cann, Martin J.

    2015-01-01

    Key points Raised arterial blood CO2 (hypercapnia) is a feature of many lung diseases.CO2 has been shown to act as a cell signalling molecule in human cells, notably by influencing the levels of cell signalling second messengers: cAMP and Ca2+.Hypercapnia reduced cAMP‐stimulated cystic fibrosis transmembrane conductance regulator‐dependent anion and fluid transport in Calu‐3 cells and primary human airway epithelia but did not affect cAMP‐regulated HCO3 − transport via pendrin or Na+/HCO3 − cotransporters.These results further support the role of CO2 as a cell signalling molecule and suggests CO2‐induced reductions in airway anion and fluid transport may impair innate defence mechanisms of the lungs. Abstract Hypercapnia is clinically defined as an arterial blood partial pressure of CO2 of above 40 mmHg and is a feature of chronic lung disease. In previous studies we have demonstrated that hypercapnia modulates agonist‐stimulated cAMP levels through effects on transmembrane adenylyl cyclase activity. In the airways, cAMP is known to regulate cystic fibrosis transmembrane conductance regulator (CFTR)‐mediated anion and fluid secretion, which contributes to airway surface liquid homeostasis. The aim of the current work was to investigate if hypercapnia could modulate cAMP‐regulated ion and fluid transport in human airway epithelial cells. We found that acute exposure to hypercapnia significantly reduced forskolin‐stimulated elevations in intracellular cAMP as well as both adenosine‐ and forskolin‐stimulated increases in CFTR‐dependent transepithelial short‐circuit current, in polarised cultures of Calu‐3 human airway cells. This CO2‐induced reduction in anion secretion was not due to a decrease in HCO3 − transport given that neither a change in CFTR‐dependent HCO3 − efflux nor Na+/HCO3 − cotransporter‐dependent HCO3 − influx were CO2‐sensitive. Hypercapnia also reduced the volume of forskolin‐stimulated fluid

  18. The split-cross-bridge resistor for measuring the sheet resistance, linewidth, and line spacing of conducting layers

    Science.gov (United States)

    Buehler, M. G.; Hershey, C. W.

    1986-01-01

    A new test structure was developed for evaluating the line spacing between conductors on the same layer using an electrical measurement technique. This compact structure can also be used to measure the sheet resistance, linewidth, and line pitch of the conducting layer. Using an integrated-circuit fabrication process, this structure was fabricated in diffused polycrystalline silicon and metal layers and measured optically and electrically. For the techniques used, the optical measurements were typically one-quarter micron greater than the electrical measurements. Most electrically measured line pitch values were within 2 percent of the designed value. A small difference between the measured and designed line pitch is used to validate sheet resistance, linewidth, and line spacing values.

  19. Proton Conductive Channel Optimization in Methanol Resistive Hybrid Hyperbranched Polyamide Proton Exchange Membrane

    Directory of Open Access Journals (Sweden)

    Liying Ma

    2017-12-01

    Full Text Available Based on a previously developed polyamide proton conductive macromolecule, the nano-scale structure of the self-assembled proton conductive channels (PCCs is adjusted via enlarging the nano-scale pore size within the macromolecules. Hyperbranched polyamide macromolecules with different size are synthesized from different monomers to tune the nano-scale pore size within the macromolecules, and a series of hybrid membranes are prepared from these two micromoles to optimize the PCC structure in the proton exchange membrane. The optimized membrane exhibits methanol permeability low to 2.2 × 10−7 cm2/s, while the proton conductivity of the hybrid membrane can reach 0.25 S/cm at 80 °C, which was much higher than the value of the Nafion 117 membrane (0.192 S/cm. By considering the mechanical, dimensional, and the thermal properties, the hybrid hyperbranched polyamide proton exchange membrane (PEM exhibits promising application potential in direct methanol fuel cells (DMFC.

  20. Silver nanosheet-coated copper nanowire/epoxy resin nanocomposites with enhanced electrical conductivity and wear resistance

    Energy Technology Data Exchange (ETDEWEB)

    Zeng, Ningning; Ma, Jingyi; Zhang, Yujuan; Yang, Guangbin; Zhang, Shengmao, E-mail: zsm@henu.edu.cn; Zhang, Pingyu [Henan University, Engineering Research Center for Nanomaterials (China)

    2017-03-15

    Silver (Ag) nanosheet-coated Cu nanowires (denoted as Cu@AgNWs) were prepared with a facile transmetalation reaction method. The effect of reaction conditions on the morphology and microstructure of the as-prepared Cu@AgNWs was investigated, and the thermal stability of Cu@AgNWs was evaluated by thermogravimetric analysis. In the meantime, the as-prepared Cu@AgNWs were used as the nanofillers of epoxy resin (EP), and their effect on the electrical conductivity and wear resistance of the EP-matrix composites was examined. Results indicate that the as-prepared Cu@AgNWs consist of CuNW core and Ag nanosheet shell. The Ag nanosheet shell can well inhibit the oxidation of the CuNW core, thereby providing the as-prepared Cu@AgNWs with good thermal stability even at an elevated temperature of 230 °C. The reaction temperature, Cu/Ag molar ratio, Cu dispersion concentration, and the dropping speed of silver ammonia reagent are suggested to be 40 °C, 5:1, 1% (mass fraction), and poured directly, respectively. Resultant Cu@AgNWs exhibit desired morphology and performance and can effectively increase the electrical conductivity and wear resistance of EP. This could make it feasible for the Cu@AgNW-EP composite to be applied as an electrostatic conductive material.

  1. Perovskite-type metal oxides exhibiting negligible grain boundary resistance to total electrical conductivity.

    Science.gov (United States)

    Pannu, Tania; Pannu, Kanwar Gulsher Singh; Thangadurai, Venkataraman

    2011-01-17

    In this paper, we report the synthesis, structure and electrical properties of the perovskite-type AZn0.33+xNb0.67-xO3-δ (A = Sr or Ba; 0 ≤ x ≤ 0.08). The investigated compounds were prepared by employing the solid-state (ceramic) reaction using alkaline nitrates, zinc oxide, and niobium oxide at elevated temperatures in air. Powder X-ray diffraction (PXRD) showed the formation of disordered Zn and Nb at the B-sites of space group Pm3̅m with cubic structure and a lattice constant comparable to that of the literature. The AC impedance study showed mainly bulk contribution to the total electrical conductivity over the investigated frequency range of 0.01 Hz to 1 MHz in all the investigated atmospheres even at low temperatures, which is significantly different from that of the well-known perovskite-type B-site ordered BaCa0.33+xNb0.67-xO3-δ and the disordered acceptor-doped BaCeO3. The bulk dielectric constant determined at 500 and 700 °C in air was found to be in the range of 35-100. In air, the isothermal bulk dielectric constant seems to increase with an increasing Zn content, and a similar trend was observed for total electrical conductivity. In dry and wet H2, the electrical conductivity decreases with an increasing Zn content in AZn0.33+xNb0.67-xO3-δ, and the x = 0 member of the Ba compound exhibits the highest total conductivity of 7.2 × 10(-3) S cm(-1) in dry H2 at 800 °C. Both Sr and Ba compounds were found to be stable against the reaction with pure CO2 at 700 °C and H2O at 100 °C for a long period of time. SrZn0.33+xNb0.67-xO3-δ was found to be stable in 30 ppm H2S at 800 °C, while the corresponding Ba compound formed reaction products such as BaS (JCPDS Card 01-0757), BaS2 (JCPDS Card 21-0087), and BaS3 (JCPDS Card 03-0824).

  2. Multiplexed and Switchable Release of Distinct Fluids from Microneedle Platforms via Conducting Polymer Nanoactuators for Potential Drug Delivery

    Science.gov (United States)

    Valdés-Ramírez, Gabriela; Windmiller, Joshua R.; Claussen, Jonathan C.; Martinez, Alexandra G.; Kuralay, Filiz; Zhou, Ming; Zhou, Nandi; Polsky, Ronen; Miller, Philip R.; Narayan, Roger; Wang, Joseph

    2013-01-01

    We report on the development of a microneedle-based multiplexed drug delivery actuator that enables the controlled delivery of multiple therapeutic agents. Two individually-addressable channels on a single microneedle array, each paired with its own reservoir and conducting polymer nanoactuator, are used to deliver various permutations of two unique chemical species. Upon application of suitable redox potentials to the selected actuator, the conducting polymer is able to undergo reversible volume changes, thereby serving to release a model chemical agent in a controlled fashion through the corresponding microneedle channels. Time-lapse videos offer direct visualization and characterization of the membrane switching capability and, along with calibration investigations, confirm the ability of the device to alternate the delivery of multiple reagents from individual microneedles of the array with higher precision and temporal resolution than conventional drug delivery actuators. Analytical modeling offers prediction of the volumetric flow rate through a single microneedle and accordingly can be used to assist in the design of subsequent microneedle arrays. The robust solid-state design and lack of mechanical components circumvent reliability issues that challenge fragile conventional microelectromechanical drug delivery devices. This proof-of-concept study demonstrates the potential of the drug delivery actuator system to aid in the rapid administration of multiple therapeutic agents and indicates the potential to counteract diverse biomedical conditions. PMID:24174709

  3. Surveying and Comparing Thermal Conductivity and Physical Properties of Oil Base NanoFluids Containing Carbon and Metal Oxide Nanotubes

    Directory of Open Access Journals (Sweden)

    H. Ahmadi

    2012-12-01

    Full Text Available In this research, nano materials with tubular structures are added to SAE 20W50 engine oil to study the rate of their effects on the properties of engine oil. Multi-walled carbon nanotubes (MWCNTs and vanadium oxide nanotubes (VONTs has been used as two different additive materials, one of them is carbonic and the other is metallic oxides and their effect on  different parameters containing viscosity, thermal conductivity coefficient, flash point and pour point of engine oil as the quality properties of engine oil has been studied and compared. The samples of two concentrations 0.1 and 0.2 wt% with using planetary ball mill were made. The obtained results show that MWCNTs in all cases, which  have been evaluated, had better functionality with respect to vanadium oxide nanotubes. In the 0.1 wt% concentration, flash point of MWCNTs/oil and VONTs/oil increased about 9.3% and 5.8% respectively. In addition, thermal conductivity of them increased 13.2% and 10.2% respectively.

  4. Low mercury concentrations cause oxidative stress and endothelial dysfunction in conductance and resistance arteries.

    Science.gov (United States)

    Wiggers, G A; Peçanha, F M; Briones, A M; Pérez-Girón, J V; Miguel, M; Vassallo, D V; Cachofeiro, V; Alonso, M J; Salaices, M

    2008-09-01

    Increased cardiovascular risk after mercury exposure has been described, but the underlying mechanisms are not well explored. We analyzed the effects of chronic exposure to low mercury concentrations on endothelium-dependent responses in aorta and mesenteric resistance arteries (MRA). Wistar rats were treated with mercury chloride (1st dose 4.6 microg/kg, subsequent dose 0.07 microg.kg(-1).day(-1) im, 30 days) or vehicle. Blood levels at the end of treatment were 7.97 +/- 0.59 ng/ml. Mercury treatment: 1) did not affect systolic blood pressure; 2) increased phenylephrine-induced vasoconstriction; 3) reduced acetylcholine-induced vasodilatation; and 4) reduced in aorta and abolished in MRA the increased phenylephrine responses induced by either endothelium removal or the nitric oxide synthase (NOS) inhibitor N(G)-nitro-l-arginine methyl ester (l-NAME, 100 microM). Superoxide dismutase (SOD, 150 U/ml) and the NADPH oxidase inhibitor apocynin (0.3 mM) decreased the phenylephrine-induced contraction in aorta more in mercury-treated rats than controls. In MRA, SOD did not affect phenylephrine responses; however, when coincubated with l-NAME, the l-NAME effect on phenylephrine response was restored in mercury-treated rats. Both apocynin and SOD restored the impaired acetylcholine-induced vasodilatation in vessels from treated rats. Endothelial NOS expression did not change in aorta but was increased in MRA from mercury-treated rats. Vascular O2(-) production, plasmatic malondialdehyde levels, and total antioxidant status increased with the mercury treatment. In conclusion, chronic exposure to low concentrations of mercury promotes endothelial dysfunction as a result of the decreased NO bioavailability induced by increases in oxidative stress. These findings offer further evidence that mercury, even at low concentrations, is an environmental risk factor for cardiovascular disease.

  5. Characterizing reach-scale flow resistance in mountain streams using structure-from-motion surveys and computational fluid dynamics simulation

    Science.gov (United States)

    DiBiase, R.; Liu, X.; Chen, Y.

    2016-12-01

    Understanding flow hydraulics in mountain streams is important for assessing flooding hazard, and for quantifying sediment transport and bedrock incision in upland landscapes. In such settings, reach-scale flow resistance is sensitive to grain-scale roughness in channel bed sediment cover, which has traditionally been characterized by particle size distributions derived from time-consuming point counts performed in the field. However, developing a general framework for quantifying frictional relationships in mountain channels has proven a significant challenge. Here we combine millimeter-scale Structure-from-Motion (SfM) surveys of bed topography, traditional point counts of surface clast size and shape, and computational fluid dynamics (CFD) simulations in order to better evaluate the important scales of roughness for turbulent flow in mountain rivers. We focused our field surveys on gravel, cobble, and boulder bedded channels in Southern California and Central Pennsylvania spanning a wide range of grain size, sorting, and shape, with the goal of deriving empirical relationships between metrics of bed microtopography roughness and particle size and shape distributions. The resulting reach-scale topographic models were then used in large eddy simulation CFD experiments to quantify flow behavior and bed resistance. By analyzing bed microtopography using structure function analysis, we identified three scaling regimes that correspond to roughness length scales important for constraining the geometric complexity required for CFD simulations. Our preliminary results highlight the potential for rapid estimation of reach-scale microtopography using SfM methods that in addition provides a more direct measure of flow resistance than particle size statistics. Additionally, SfM methods enable a similarly straightforward assessment of vegetation and bedrock channel roughness, with broad applications in fluvial geomorphology.

  6. Aluminum exposure for one hour decreases vascular reactivity in conductance and resistance arteries in rats

    International Nuclear Information System (INIS)

    Schmidt, Patrícia Medeiros; Escobar, Alyne Goulart; Torres, João Guilherme Dini; Martinez, Caroline Silveira; Rizzetti, Danize Aparecida; Kunz, Simone Noremberg; Vassallo, Dalton Valentim; Alonso, María Jesús; Peçanha, Franck Maciel; Wiggers, Giulia Alessandra

    2016-01-01

    Aims: Aluminum (Al) is an important environmental contaminant; however, there are not enough evidences of Al-induced cardiovascular dysfunction. We investigated the effects of acute exposure to aluminum chloride (AlCl 3 ) on blood pressure, vascular reactivity and oxidative stress. Methods and results: Male Wistar rats were divided into two groups: Untreated: vehicle (ultrapure water, ip) and AlCl 3 : single dose of AlCl 3 (100 mg/kg,ip). Concentration-response curves to phenylephrine in the absence and presence of endothelium, the nitric oxide synthase inhibitor L-NAME, the potassium channel blocker tetraethylammonium, and the NADPH oxidase inhibitor apocynin were performed in segments from aortic and mesenteric resistance arteries. NO released was assessed in aorta and reactive oxygen species (ROS), malondialdehyde, non-protein thiol levels, antioxidant capacity and enzymatic antioxidant activities were investigated in plasma, aorta and/or mesenteric arteries. After one hour of AlCl 3 exposure serum Al levels attained 147.7 ± 25.0 μg/L. Al treatment: 1) did not affect blood pressure, heart rate and vasodilator responses induced by acetylcholine or sodium nitroprusside; 2) decreased phenylephrine-induced vasoconstrictor responses; 3) increased endothelial modulation of contractile responses, NO release and vascular ROS production from NADPH oxidase; 4) increased plasmatic, aortic and mesenteric malondialdehyde and ROS production, and 5) decreased antioxidant capacity and affected the antioxidant biomarkers non-protein thiol levels, glutathione peroxidase, glutathione-S-transferase, superoxide dismutase and catalase enzymatic activities. Conclusion: AlCl 3 -acute exposure reduces vascular reactivity. This effect is associated with increased NO production, probably acting on K + channels, which seems to occur as a compensatory mechanism against Al-induced oxidative stress. Our results suggest that Al exerts toxic effects to the vascular system. - Highlights:

  7. The use of low resistivity substrates for optimal noise reduction, ground referencing, and current conduction in mixed signal ASICs

    Energy Technology Data Exchange (ETDEWEB)

    Zimmerman, T.

    1997-12-01

    This paper is distilled from a talk given at the 3rd International Meeting on Front End Electronics in Taos, N.M. on Nov. 7,1997. It is based on experience gained by designing and testing the SVX3 128 channel silicon strip detector readout chip. The SVX3 chip organization is shown in Fig. 1. The Front End section consists of an integrator and analog pipeline designed at Fermilab, and the Back End section is an ADC plus sparsification and readout logic designed at LBL. SVX3 is a deadtimeless readout chip, which means that the front end is acquiring low level analog signals while the back end is digitizing and reading out digital signals. It is thus a true mixed signal chip, and demands close attention to avoid disastrous coupling from the digital to the analog sections. SVX3 is designed in a bulk CMOS process (i.e., the circuits sit in a silicon substrate). In such a process, the substrate becomes a potential coupling path. This paper discusses the effect of the substrate resistivity on coupling, and also goes into a more general discussion of grounding and referencing in mixed signal designs and how low resistivity substrates can be used to advantage. Finally, an alternative power supply current conduction method for ASICs is presented as an additional advantage which can be obtained with low resistivity substrates. 1 ref., 13 figs., 1 tab.

  8. A Continuous 3D-Graphene Network to Overcome Threshold Issues and Contact Resistance in Thermally Conductive Graphene Nanocomposites

    Directory of Open Access Journals (Sweden)

    Federico Conrado

    2017-01-01

    Full Text Available In order to overcome thermal resistance issues in polymeric matrix composites, self-standing graphene aerogels were synthetized and infiltrated with an epoxy resin, in order to create conductive preferential pathways through which heat can be easily transported. These continuous highly thermally conductive 3D-structures show, due to the high interconnection degree of graphene flakes, enhanced transport properties. Two kinds of aerogels were investigated, obtained by hydrothermal synthesis (HS and ice-templated direct freeze synthesis (DFS. Following HS method an isotropic structure is obtained, and following DFS method instead an anisotropic arrangement of graphene flakes results. The density of the structure can be tuned leading to a different amount of graphene inside the final composite. The residual oxygen, known to be detrimental to thermal properties, was removed by thermal treatment before the infiltration process. With 1,25 wt.% of graphene, using HS method, the thermal conductivity of the polymeric resin was increased by 80%, suggesting that this technique is a valid route to improve the thermal performance of graphene-based composites. When preferential orientation of the filler was present (DFS case, thermal conductivity was increased more than 25% with a graphene content of only 0,27 wt.%, demonstrating that oriented structures can further improve the thermal transport efficiency.

  9. Mechanisms of double stratification and magnetic field in flow of third grade fluid over a slendering stretching surface with variable thermal conductivity

    Science.gov (United States)

    Hayat, Tasawar; Qayyum, Sajid; Alsaedi, Ahmed; Ahmad, Bashir

    2018-03-01

    This article addresses the magnetohydrodynamic (MHD) stagnation point flow of third grade fluid towards a nonlinear stretching sheet. Energy expression is based through involvement of variable thermal conductivity. Heat and mass transfer aspects are described within the frame of double stratification effects. Boundary layer partial differential systems are deduced. Governing systems are then converted into ordinary differential systems by invoking appropriate variables. The transformed expressions are solved through homotopic technique. Impact of embedded variables on velocity, thermal and concentration fields are displayed and argued. Numerical computations are presented to obtain the results of skin friction coefficient and local Nusselt and Sherwood numbers. It is revealed that larger values of magnetic parameter reduces the velocity field while reverse situation is noticed due to wall thickness variable. Temperature field and local Nusselt number are quite reverse for heat generation/absorption parameter. Moreover qualitative behaviors of concentration field and local Sherwood number are similar for solutal stratification parameter.

  10. Uncorrelated multiple conductive filament nucleation and rupture in ultra-thin high-κ dielectric based resistive random access memory

    KAUST Repository

    Wu, Xing

    2011-08-29

    Resistive switching in transition metal oxides could form the basis for next-generation non-volatile memory (NVM). It has been reported that the current in the high-conductivity state of several technologically relevant oxide materials flows through localized filaments, but these filaments have been characterized only individually, limiting our understanding of the possibility of multiple conductive filaments nucleation and rupture and the correlation kinetics of their evolution. In this study, direct visualization of uncorrelated multiple conductive filaments in ultra-thin HfO2-based high-κ dielectricresistive random access memory (RRAM) device has been achieved by high-resolution transmission electron microscopy (HRTEM), along with electron energy loss spectroscopy(EELS), for nanoscale chemical analysis. The locations of these multiple filaments are found to be spatially uncorrelated. The evolution of these microstructural changes and chemical properties of these filaments will provide a fundamental understanding of the switching mechanism for RRAM in thin oxide films and pave way for the investigation into improving the stability and scalability of switching memory devices.

  11. Anisotropic Magnetoresistance of Nano-conductive Filament in Co/HfO2/Pt Resistive Switching Memory.

    Science.gov (United States)

    Li, Leilei; Liu, Yang; Teng, Jiao; Long, Shibing; Guo, Qixun; Zhang, Meiyun; Wu, Yu; Yu, Guanghua; Liu, Qi; Lv, Hangbing; Liu, Ming

    2017-12-01

    Conductive bridge random access memory (CBRAM) has been extensively studied as a next-generation non-volatile memory. The conductive filament (CF) shows rich physical effects such as conductance quantization and magnetic effect. But so far, the study of filaments is not very sufficient. In this work, Co/HfO 2 /Pt CBRAM device with magnetic CF was designed and fabricated. By electrical manipulation with a partial-RESET method, we controlled the size of ferromagnetic metal filament. The resistance-temperature characteristics of the ON-state after various partial-RESET behaviors have been studied. Using two kinds of magnetic measurement methods, we measured the anisotropic magnetoresistance (AMR) of the CF at different temperatures to reflect the magnetic structure characteristics. By rotating the direction of the magnetic field and by sweeping the magnitude, we obtained the spatial direction as well as the easy-axis of the CF. The results indicate that the easy-axis of the CF is along the direction perpendicular to the top electrode plane. The maximum magnetoresistance was found to appear when the angle between the direction of magnetic field and that of the electric current in the CF is about 30°, and this angle varies slightly with temperature, indicating that the current is tilted.

  12. Develop Hydrophilic Conductive Coating Technology with High Oxidation Resistance for Non-Flow-Through PEM Fuel Cells and Electrolyzers, Phase I

    Data.gov (United States)

    National Aeronautics and Space Administration — ElectroChem proposes to develop oxidation resistant, electrically conductive, hydrophilic coatings in PEM fuel cells and in PEM electrolyzers. The use of hydrophilic...

  13. High order ADER schemes for a unified first order hyperbolic formulation of continuum mechanics: Viscous heat-conducting fluids and elastic solids

    International Nuclear Information System (INIS)

    Dumbser, Michael; Peshkov, Ilya; Romenski, Evgeniy; Zanotti, Olindo

    2016-01-01

    Highlights: • High order schemes for a unified first order hyperbolic formulation of continuum mechanics. • The mathematical model applies simultaneously to fluid mechanics and solid mechanics. • Viscous fluids are treated in the frame of hyper-elasticity as generalized visco-plastic solids. • Formal asymptotic analysis reveals the connection with the Navier–Stokes equations. • The distortion tensor A in the model appears to be well-suited for flow visualization. - Abstract: This paper is concerned with the numerical solution of the unified first order hyperbolic formulation of continuum mechanics recently proposed by Peshkov and Romenski [110], further denoted as HPR model. In that framework, the viscous stresses are computed from the so-called distortion tensor A, which is one of the primary state variables in the proposed first order system. A very important key feature of the HPR model is its ability to describe at the same time the behavior of inviscid and viscous compressible Newtonian and non-Newtonian fluids with heat conduction, as well as the behavior of elastic and visco-plastic solids. Actually, the model treats viscous and inviscid fluids as generalized visco-plastic solids. This is achieved via a stiff source term that accounts for strain relaxation in the evolution equations of A. Also heat conduction is included via a first order hyperbolic system for the thermal impulse, from which the heat flux is computed. The governing PDE system is hyperbolic and fully consistent with the first and the second principle of thermodynamics. It is also fundamentally different from first order Maxwell–Cattaneo-type relaxation models based on extended irreversible thermodynamics. The HPR model represents therefore a novel and unified description of continuum mechanics, which applies at the same time to fluid mechanics and solid mechanics. In this paper, the direct connection between the HPR model and the classical hyperbolic–parabolic Navier

  14. High order ADER schemes for a unified first order hyperbolic formulation of continuum mechanics: Viscous heat-conducting fluids and elastic solids

    Science.gov (United States)

    Dumbser, Michael; Peshkov, Ilya; Romenski, Evgeniy; Zanotti, Olindo

    2016-06-01

    This paper is concerned with the numerical solution of the unified first order hyperbolic formulation of continuum mechanics recently proposed by Peshkov and Romenski [110], further denoted as HPR model. In that framework, the viscous stresses are computed from the so-called distortion tensor A, which is one of the primary state variables in the proposed first order system. A very important key feature of the HPR model is its ability to describe at the same time the behavior of inviscid and viscous compressible Newtonian and non-Newtonian fluids with heat conduction, as well as the behavior of elastic and visco-plastic solids. Actually, the model treats viscous and inviscid fluids as generalized visco-plastic solids. This is achieved via a stiff source term that accounts for strain relaxation in the evolution equations of A. Also heat conduction is included via a first order hyperbolic system for the thermal impulse, from which the heat flux is computed. The governing PDE system is hyperbolic and fully consistent with the first and the second principle of thermodynamics. It is also fundamentally different from first order Maxwell-Cattaneo-type relaxation models based on extended irreversible thermodynamics. The HPR model represents therefore a novel and unified description of continuum mechanics, which applies at the same time to fluid mechanics and solid mechanics. In this paper, the direct connection between the HPR model and the classical hyperbolic-parabolic Navier-Stokes-Fourier theory is established for the first time via a formal asymptotic analysis in the stiff relaxation limit. From a numerical point of view, the governing partial differential equations are very challenging, since they form a large nonlinear hyperbolic PDE system that includes stiff source terms and non-conservative products. We apply the successful family of one-step ADER-WENO finite volume (FV) and ADER discontinuous Galerkin (DG) finite element schemes to the HPR model in the stiff

  15. Evaluation of sloshing resistance performance for LNG carrier insulation system based on fluid-structure interaction analysis

    Directory of Open Access Journals (Sweden)

    Chi-Seung Lee

    2013-03-01

    Full Text Available In the present paper, the sloshing resistance performance of a huge-size LNG carrier's insulation system is evaluated by the fluid-structure interaction (FSI analysis. To do this, the global-local analysis which is based on the arbitrary Lagrangian-Eulerian (ALE method is adopted to accurately calculate the structural behavior induced by internal LNG sloshing of a KC-1 type LNG carrier insulation system. During the global analysis, the sloshing flow and hydrodynamic pressure of internal LNG are analyzed by postulating the flexible insulation system as a rigid body. In addition, during the local analysis, the local hydroelastic response of the LNG carrier insulation system is computed by solving the local hydroelastic model where the entire and flexible insulation system is adopted and the numerical analysis results of the global analysis such as initial and boundary conditions are implemented into the local finite element model. The proposed novel analysis techniques can potentially be used to evaluate the structural integrity of LNG carrier insulation systems.

  16. Application of direct-fitting, mass-integral, and multi-ratemethods to analysis of flowing fluid electric conductivity logs fromHoronobe, Japan

    Energy Technology Data Exchange (ETDEWEB)

    Doughty, C.; Tsang, C.-F.; Hatanaka, K.; Yabuuchi, S.; Kurikami, H.

    2007-08-01

    The flowing fluid electric conductivity (FFEC) loggingmethod is an efficient way to provide information on the depths,salinities, and transmissivities of individual conductive featuresintercepted by a borehole, without the use of specialized probes. Usingit in a multiple-flow-rate mode allows, in addition, an estimate of theinherent "far-field" pressure heads in each of the conductive features.The multi-rate method was successfully applied to a 500-m borehole in agranitic formation and reported recently. The present paper presents theapplication of the method to two zones within a 1000-m borehole insedimentary rock, which produced, for each zone, three sets of logs atdifferent pumping rates, each set measured over a period of about oneday. The data sets involve a number of complications, such as variablewell diameter, free water table decline in the well, and effects ofdrilling mud. To analyze data from this borehole, we apply varioustechniques that have been developed for analyzing FFEC logs:direct-fitting, mass-integral, and the multi-rate method mentioned above.In spite of complications associated with the tests, analysis of the datais able to identify 44 hydraulically conducting fractures distributedover the depth interval 150-775 meters below ground surface. Thesalinities (in FEC), and transmissivities and pressure heads (indimensionless form) of these 44 features are obtained and found to varysignificantly among one another. These results are compared with datafrom eight packer tests with packer intervals of 10-80 m, which wereconducted in this borehole over the same depth interval. They are foundto be consistent with these independent packer-test data, thusdemonstrating the robustness of the FFEC logging method under non-idealconditions.

  17. Effects of variable viscosity and thermal conductivity on unsteady MHD flow of non-Newtonian fluid over a stretching porous sheet

    Directory of Open Access Journals (Sweden)

    Rahman Abdel-Gamal M.

    2013-01-01

    Full Text Available The unsteady flow and heat transfer in an incompressible laminar, electrically conducting and non-Newtonian fluid over a non-isothermal stretching sheet with the variation in the viscosity and thermal conductivity in a porous medium by the influence of an external transverse magnetic field have been obtained and studied numerically. By using similarity analysis the governing differential equations are transformed into a set of non-linear coupled ordinary differential equations which are solved numerically. Numerical results were presented for velocity and temperature profiles for different parameters of the problem as power law parameter, unsteadiness parameter, radiation parameter, magnetic field parameter, porous medium parameter, temperature buoyancy parameter, Prandtl parameter, modified Eckert parameter, Joule heating parameter , heat source/sink parameter and others. A comparison with previously published work has been carried out and the results are found to be in good agreement. Also the effects of the pertinent parameters on the skin friction and the rate of heat transfer are obtained and discussed numerically and illustrated graphically.

  18. Structure, electrical resistivity, and thermal conductivity of beech wood biocarbon produced at carbonization temperatures below 1000°C

    Science.gov (United States)

    Parfen'eva, L. S.; Orlova, T. S.; Kartenko, N. F.; Smirnov, B. I.; Smirnov, I. A.; Misiorek, H.; Jezowski, A.; Muha, J.; Vera, M. C.

    2011-11-01

    This paper reports on measurements of the thermal conductivity κ and the electrical resistivity ρ in the temperature range 5-300 K, and, at 300 K, on X-ray diffraction studies of high-porosity (with a channel pore volume fraction of ˜47 vol %) of the beech wood biocarbon prepared by pyrolysis (carbonization) of tree wood in an argon flow at the carbonization temperature T carb = 800°C. It has been shown that the biocarbon template of the samples studied represents essentially a nanocomposite made up of amorphous carbon and nanocrystallites—"graphite fragments" and graphene layers. The sizes of the nanocrystallites forming these nanocomposites have been determined. The dependences ρ( T) and κ( T) have been measured for the samples cut along and perpendicular to the tree growth direction, thus permitting determination of the magnitude of the anisotropy of these parameters. The dependences ρ( T) and κ( T), which have been obtained for beech biocarbon samples prepared at T carb = 800°C, are compared with the data amassed by us earlier for samples fabricated at T carb = 1000 and 2400°C. The magnitude and temperature dependence of the phonon thermal conductivity of the nanocomposite making up the beech biocarbon template at T carb = 800°C have been found.

  19. Failure analysis of fire resistant fluid (FRF piping used in hydraulic control system at oil-fired thermal power generation plant

    Directory of Open Access Journals (Sweden)

    Muhammad Akram

    2017-04-01

    Full Text Available This is a case study regarding frequent forced outages in an oil-fired power generating station due to failure of fire resistant fluid (FRF piping of material ASTM A-304. This analysis was done to find out the most probable cause of failure and to rectify the problem. Methods for finding and analyzing the cracks include nondestructive testing techniques such as visual testing (VT and dye penetrant testing (PT along with that periodic monitoring after rectification of problem. The study revealed that pitting and pit to crack transitions were formed in stainless steel piping containing high pressure (system pressure 115 bars fire resistant fluid. However, after replacement of piping the pitting and cracking reoccurred. It was observed that due to possible exposure to chlorinated moisture in surrounding environment pitting was formed which then transformed into cracks. The research work discussed in this paper illustrates the procedure used in detection of the problem and measures taken to solve the problem.

  20. Effective thermal conductivity of nanofluids: the effects of microstructure

    International Nuclear Information System (INIS)

    Fan Jing; Wang Liqiu

    2010-01-01

    We examine numerically the effects of particle-fluid thermal conductivity ratio, particle volume fraction, particle size distribution and particle aggregation on macroscale thermal properties for seven kinds of two-dimensional nanofluids. The results show that the radius of gyration and the non-dimensional particle-fluid interfacial area are two important parameters in characterizing the geometrical structure of nanoparticles. A non-uniform particle size is found to be unfavourable for the conductivity enhancement, while particle-aggregation benefits the enhancement especially when the radius of gyration of aggregates is large. Without considering the interfacial thermal resistance, a larger non-dimensional particle-fluid interfacial area between the base fluid and the nanoparticles is also desirable for enhancing thermal conductivity. The nanofluids with nanoparticles of connected cross-shape show a much higher (lower) effective thermal conductivity when the particle-fluid conductivity ratio is larger (smaller) than 1.

  1. Antimicrobial resistance in leprosy: results of the first prospective open survey conducted by a WHO surveillance network for the period 2009-15.

    Science.gov (United States)

    Cambau, E; Saunderson, P; Matsuoka, M; Cole, S T; Kai, M; Suffys, P; Rosa, P S; Williams, D; Gupta, U D; Lavania, M; Cardona-Castro, N; Miyamoto, Y; Hagge, D; Srikantam, A; Hongseng, W; Indropo, A; Vissa, V; Johnson, R C; Cauchoix, B; Pannikar, V K; Cooreman, E A W D; Pemmaraju, V R R; Gillini, L

    2018-03-01

    Antimicrobial resistance (AMR) is a priority for surveillance in bacterial infections. For leprosy, AMR has not been assessed because Mycobacterium leprae does not grow in vitro. We aim to obtain AMR data using molecular detection of resistance genes and to conduct a prospective open survey of resistance to antileprosy drugs in countries where leprosy is endemic through a WHO surveillance network. From 2009 to 2015, multi-bacillary leprosy cases at sentinel sites of 19 countries were studied for resistance to rifampicin, dapsone and ofloxacin by PCR sequencing of the drug-resistance-determining regions of the genes rpoB, folP1 and gyrA. Among 1932 (1143 relapse and 789 new) cases studied, 154 (8.0%) M. leprae strains were found with mutations conferring resistance showing 182 resistance traits (74 for rifampicin, 87 for dapsone and 21 for ofloxacin). Twenty cases showed rifampicin and dapsone resistance, four showed ofloxacin and dapsone resistance, but no cases were resistant to rifampicin and ofloxacin. Rifampicin resistance was observed among relapse (58/1143, 5.1%) and new (16/789, 2.0%) cases in 12 countries. India, Brazil and Colombia reported more than five rifampicin-resistant cases. This is the first study reporting global data on AMR in leprosy. Rifampicin resistance emerged, stressing the need for expansion of surveillance. This is also a call for vigilance on the global use of antimicrobial agents, because ofloxacin resistance probably developed in relation to the general intake of antibiotics for other infections as it is not part of the multidrug combination used to treat leprosy. Copyright © 2018 The Authors. Published by Elsevier Ltd.. All rights reserved.

  2. Lunar soil properties and soil mechanics. Flow in porous media under rarefied gas conditions. Research phase: Fluid conductivity of lunar surface materials

    Science.gov (United States)

    Hurlbut, F. C.; Jih, C. R.

    1972-01-01

    Theoretical and experimental research on fluid conductivity of lunar surface materials is summarized. Theoretical methods were developed for the analysis of transitional and free-molecular flows, and for analysis of lunar permeability probe data in general. Experimental studies of rarefied flows under conditions of a large pressure gradient show flows in the continuum regime to be responsible for the largest portion of the pressure drop between source and sink for one dimensional flow, provided the entrance Knudsen number is sufficiently small. The concept of local similarity leading to a universal nondimensional function of Knudsen number was shown to have approximate validity; flows in all regimes may be described in terms of an area fraction and a single length parameter. Synthetic porous media prepared from glass beads exhibited flow behavior similar in many regards to that of a natural sandstone; studies using artificial stones with known pore configurations may lead to new insight concerning the structure of natural materials. The experimental method involving the use of segmented specimens of large permeability is shown to be fruitful.

  3. Surface-conduction enhanced dielectrophoretic-like particle migration in electric-field driven fluid flow through a straight rectangular microchannel

    Science.gov (United States)

    Liu, Zhijian; Li, Di; Song, Yongxin; Pan, Xinxiang; Li, Dongqing; Xuan, Xiangchun

    2017-10-01

    An electric field has been extensively used to manipulate fluids and particles via electrokinetic flow in microchannels and nanochannels for various lab-on-a-chip applications. Recent studies have demonstrated the action of a dielectrophoretic-like lift force on near-wall particles in an electrokinetic flow due to the particles' modifications of the field-line structure adjacent to a planar wall. This work presents a fundamental investigation of the lateral migration of dielectric particles in the electrokinetic flow of buffer solutions of varying molar concentrations through a straight rectangular microchannel. We find that the particle migration-induced electrokinetic centerline focusing is significantly enhanced with the decrease of the buffer concentration. This observed phenomenon may be attributed to the increased surface conduction effect in a lower-concentration buffer that yields a larger Dukhin number, Du. It seems qualitatively consistent with a recent theoretical study that predicts a greater wall-induced electrical lift with the increasing value of the Dukhin number for Du ≥ 1.

  4. Computational fluid dynamics analyses of lateral heat conduction, coolant azimuthal mixing and heat transfer predictions in a BR2 fuel assembly geometry

    International Nuclear Information System (INIS)

    Tzanos, C.P.; Dionne, B.

    2011-01-01

    To support the analyses related to the conversion of the BR2 core from highly-enriched (HEU) to low-enriched (LEU) fuel, the thermal-hydraulics codes PLTEMP and RELAP-3D are used to evaluate the safety margins during steady-state operation (PLTEMP), as well as after a loss-of-flow, loss-of-pressure, or a loss of coolant event (RELAP). In the 1-D PLTEMP and RELAP simulations, conduction in the azimuthal and axial directions is not accounted. The very good thermal conductivity of the cladding and the fuel meat and significant temperature gradients in the lateral directions (axial and azimuthal directions) could lead to a heat flux distribution that is significantly different than the power distribution. To evaluate the significance of the lateral heat conduction, 3-D computational fluid dynamics (CFD) simulations, using the CFD code STAR-CD, were performed. Safety margin calculations are typically performed for a hot stripe, i.e., an azimuthal region of the fuel plates/coolant channel containing the power peak. In a RELAP model, for example, a channel between two plates could be divided into a number of RELAP channels (stripes) in the azimuthal direction. In a PLTEMP model, the effect of azimuthal power peaking could be taken into account by using engineering factors. However, if the thermal mixing in the azimuthal direction of a coolant channel is significant, a stripping approach could be overly conservative by not taking into account this mixing. STAR-CD simulations were also performed to study the thermal mixing in the coolant. Section II of this document presents the results of the analyses of the lateral heat conduction and azimuthal thermal mixing in a coolant channel. Finally, PLTEMP and RELAP simulations rely on the use of correlations to determine heat transfer coefficients. Previous analyses showed that the Dittus-Boelter correlation gives significantly more conservative (lower) predictions than the correlations of Sieder-Tate and Petukhov. STAR-CD 3-D

  5. Thermal conductivity, electrical resistivity, and Seebeck coefficient of high-purity chromium from 280 to 1000 K

    International Nuclear Information System (INIS)

    Moore, J.P.; Williams, R.K.; Graves, R.S.

    1977-01-01

    The thermal conductivity lambda, electrical resistivity rho, and Seebeck coefficient S of a high-purity Cr specimen (rho 273 /rho/sub 4.2/ = 380) were measured from 285 to 1000 K. The rho and S of two other Cr specimens (rho 273 /rho/sub 4.1/ = 380 and 58) were determined from 300 to 1300 K. The rho and S results from the three specimens are in excellent agreement, and all three properties agree to within experimental uncertainty with previous low-temperature results on the same specimens over the temperature range of overlap. Near T'/sub N/ (300--320 K), the present lambda results are within 0.7% of the previous data and indicate that lambdarho/T should be smooth to within 1%. At high temperature, the present lambda data are about 8% above those of Powell and Tye, but the ratios of lambdarho/T agree to within 2% up to 1000 K. These new data on pure Cr are compared to calculations from standard transport theory and to previous results from W and Mo

  6. Investigation of Superficial Resistance of Different Purity Copper at Boiling Nitrogen Temperature Depending on Treatment of Current-Conducting Layer

    International Nuclear Information System (INIS)

    Kutovoj, V.A.; Nikolaenko, A.A.; Stoev, P.I.

    2007-01-01

    Results of this scientific work show influence of annealing temperature and deformation degree of initial MOB copper and after electron beam refining on superficial resistance at temperature of boiling nitrogen. It is shown, that 30 % deformation and annealing in 873...923 K temperature range results in appreciable reduction of superficial resistance at the investigated samples of copper. The lowest values of superficial resistance after thermal and mechanical treatment were observed in the samples after electron beam refinement

  7. 30 CFR 35.7 - Date for conducting tests.

    Science.gov (United States)

    2010-07-01

    ... APPROVAL OF MINING PRODUCTS FIRE-RESISTANT HYDRAULIC FLUIDS General Provisions § 35.7 Date for conducting tests. The date of acceptance of an application will determine the order of precedence for testing when... 30 Mineral Resources 1 2010-07-01 2010-07-01 false Date for conducting tests. 35.7 Section 35.7...

  8. Vertical variation in groundwater chemistry inferred from fluid specific-conductance well logging of the Snake River Plain Basalt aquifer, Idaho National Engineering Laboratory, southeastern Idaho

    International Nuclear Information System (INIS)

    Wood, S.H.; Bennecke, W.

    1994-01-01

    Well logging of electrical fluid specific conductance (C s ) shows that permeable zones yielding ground water to intrawell flows and the water columns in some wells at INEL have highly different chemistry, with as much as a two-fold variation in C s . This suggests that dedicated-pump sampling of ground water in the aquifer may not be representative of the chemistry of the waste plumes migrating southwest of the nuclear facilities. Natural background C s in basalt-aquifer ground water of this part of the Snake River Plain aquifer is less than 325μS/cm (microSiemans/cm), and total dissolved solids in mg/L units, (TDS) ∼ 0.6C s . This relationship underestimates TDS for waters with chemical waste, when C s is above 800 μS/cm. At well 59 near the ICPP water of 1115 μS/cm (∼6570+ mg/L TDS) enters the well from a permeable zone between 521 and 537 ft depth; the zone being 60 ft below the water level and water of 550 μS/cm. At the time of logging (9/14/93) the 1115/μS/cm water was flowing down the well, mixing with less concentrated waters and exciting at 600 or 624-ft depth. Waste water disposed of down the injection well at ICPP until 1984 was estimated to have a C 5 of 1140 μS/cm, identical to the water detected in logging. 29 refs., 8 figs., 1 tab

  9. Effect of current compliance and voltage sweep rate on the resistive switching of HfO2/ITO/Invar structure as measured by conductive atomic force microscopy

    Science.gov (United States)

    Wu, You-Lin; Liao, Chun-Wei; Ling, Jing-Jenn

    2014-06-01

    The electrical characterization of HfO2/ITO/Invar resistive switching memory structure was studied using conductive atomic force microscopy (AFM) with a semiconductor parameter analyzer, Agilent 4156C. The metal alloy Invar was used as the metal substrate to ensure good ohmic contact with the substrate holder of the AFM. A conductive Pt/Ir AFM tip was placed in direct contact with the HfO2 surface, such that it acted as the top electrode. Nanoscale current-voltage (I-V) characteristics of the HfO2/ITO/Invar structure were measured by applying a ramp voltage through the conductive AFM tip at various current compliances and ramp voltage sweep rates. It was found that the resistance of the low resistance state (RLRS) decreased with increasing current compliance value, but resistance of high resistance state (RHRS) barely changed. However, both the RHRS and RLRS decreased as the voltage sweep rate increased. The reasons for this dependency on current compliance and voltage sweep rate are discussed.

  10. A study to investigate viscous coupling effects on the hydraulic conductance of fluid layers in two-phase flow at the pore level.

    Science.gov (United States)

    Shams, Mosayeb; Raeini, Ali Q; Blunt, Martin J; Bijeljic, Branko

    2018-07-15

    This paper examines the role of momentum transfer across fluid-fluid interfaces in two-phase flow. A volume-of-fluid finite-volume numerical method is used to solve the Navier-Stokes equations for two-phase flow at the micro-scale. The model is applied to investigate viscous coupling effects as a function of the viscosity ratio, the wetting phase saturation and the wettability, for different fluid configurations in simple pore geometries. It is shown that viscous coupling effects can be significant for certain pore geometries such as oil layers sandwiched between water in the corner of mixed wettability capillaries. A simple parametric model is then presented to estimate general mobility terms as a function of geometric properties and viscosity ratio. Finally, the model is validated by comparison with the mobilities computed using direct numerical simulation. Copyright © 2018 The Authors. Published by Elsevier Inc. All rights reserved.

  11. Improvement of bio-corrosion resistance for Ti42Zr40Si15Ta3 metallic glasses in simulated body fluid by annealing within supercooled liquid region.

    Science.gov (United States)

    Huang, C H; Lai, J J; Wei, T Y; Chen, Y H; Wang, X; Kuan, S Y; Huang, J C

    2015-01-01

    The effects of the nanocrystalline phases on the bio-corrosion behavior of highly bio-friendly Ti42Zr40Si15Ta3 metallic glasses in simulated body fluid were investigated, and the findings are compared with our previous observations from the Zr53Cu30Ni9Al8 metallic glasses. The Ti42Zr40Si15Ta3 metallic glasses were annealed at temperatures above the glass transition temperature, Tg, with different time periods to result in different degrees of α-Ti nano-phases in the amorphous matrix. The nanocrystallized Ti42Zr40Si15Ta3 metallic glasses containing corrosion resistant α-Ti phases exhibited more promising bio-corrosion resistance, due to the superior pitting resistance. This is distinctly different from the previous case of the Zr53Cu30Ni9Al8 metallic glasses with the reactive Zr2Cu phases inducing serious galvanic corrosion and lower bio-corrosion resistance. Thus, whether the fully amorphous or partially crystallized metallic glass would exhibit better bio-corrosion resistance, the answer would depend on the crystallized phase nature. Copyright © 2015 Elsevier B.V. All rights reserved.

  12. Further insights into the components of resistance to Ophiostoma novo-ulmi in Ulmus minor: hydraulic conductance, stomatal sensitivity and bark dehydration.

    Science.gov (United States)

    Pita, Pilar; Rodríguez-Calcerrada, Jesús; Medel, David; Gil, Luis

    2018-02-01

    Dutch elm disease (DED) is a vascular disease that has killed over 1 billion elm trees. The pathogen spreads throughout the xylem network triggering vessel blockage, which results in water stress, tissue dehydration and extensive leaf wilting in susceptible genotypes. We investigated the differences between four Ulmus minor Mill. clones of contrasting susceptibility to Ophiostoma novo-ulmi Brasier regarding morphological, anatomical and physiological traits affecting water transport, in order to gain a better understanding of the mechanisms underlying DED susceptibility. We analyzed the differential response to water shortage and increased air vapor pressure deficit (VPD) to investigate whether resistance to water stress might be related to DED tolerance. Sixteen plants per clone, aged 2 years, were grown inside a greenhouse under differential watering. Stomatal conductance was measured under ambient and increased VPD. Growth, bark water content and stem hydraulic and anatomical parameters were measured 22 days after starting differential watering. Vessel lumen area, lumen fraction and hydraulic conductance were highest in susceptible clones. Stomatal conductance was lowest under low VPD and decreased faster under increased VPD in resistant clones. We found a negative relationship between the decrease in stomatal conductance at increased VPD and specific hydraulic conductance, revealing a narrower hydraulic margin for sustaining transpiration in resistant clones. The effect of water shortage was greater on radial stem growth than on leaf area, which could be explained through an extensive use of capacitance water to buffer xylem water potential. Water shortage reduced stomatal conductance and vessel lumen area. Bark water content under conditions of water shortage only decreased in susceptible clones. Higher hydraulic constraints to sap flow in resistant clones may determine higher stomatal sensitivity to VPD and so contribute to DED resistance by limiting pathogen

  13. Role of Al2O3 thin layer on improving the resistive switching properties of Ta5Si3-based conductive bridge random accesses memory device

    Science.gov (United States)

    Kumar, Dayanand; Aluguri, Rakesh; Chand, Umesh; Tseng, Tseung-Yuen

    2018-04-01

    Ta5Si3-based conductive bridge random access memory (CBRAM) devices have been investigated to improve their resistive switching characteristics for their application in future nonvolatile memory technology. Changes in the switching characteristics by the addition of a thin Al2O3 layer of different thicknesses at the bottom electrode interface of a Ta5Si3-based CBRAM devices have been studied. The double-layer device with a 1 nm Al2O3 layer has shown improved resistive switching characteristics over the single layer one with a high on/off resistance ratio of 102, high endurance of more than 104 cycles, and good retention for more than 105 s at the temperature of 130 °C. The higher thermal conductivity of Al2O3 over Ta5Si3 has been attributed to the enhanced switching properties of the double-layer devices.

  14. Disseminated tuberculosis in an HIV-infected child: rifampicin resistance detected by GeneXpert in a lymph node aspirate but not in cerebrospinal fluid.

    Science.gov (United States)

    Gamell, Anna; Ntamatungiro, Alex John; Battegay, Manuel; Letang, Emilio

    2015-08-03

    A 9-year-old HIV-infected child previously treated with inadequate doses of antitubercular drugs based on weight was admitted 5 months after initial tuberculosis (TB) diagnosis with acute hemiplegia and inguinal lymphadenopathies in a rural hospital in Tanzania. He was diagnosed with TB meningitis and lymphadenitis using Xpert Mycobacterium tuberculosis/rifampicin (MTB/RIF) assay. Rifampicin resistance was detected in the lymph node aspirate but not in the cerebrospinal fluid. His TB therapy was optimised based on available medications and antiretroviral treatment was initiated 6 weeks later. Despite these efforts, the clinical evolution was poor and the child died 12 weeks after admission. 2015 BMJ Publishing Group Ltd.

  15. Computational Fluid Dynamics

    International Nuclear Information System (INIS)

    Myeong, Hyeon Guk

    1999-06-01

    This book deals with computational fluid dynamics with basic and history of numerical fluid dynamics, introduction of finite volume method using one-dimensional heat conduction equation, solution of two-dimensional heat conduction equation, solution of Navier-Stokes equation, fluid with heat transport, turbulent flow and turbulent model, Navier-Stokes solution by generalized coordinate system such as coordinate conversion, conversion of basic equation, program and example of calculation, application of abnormal problem and high speed solution of numerical fluid dynamics.

  16. Room-Temperature Voltage Stressing Effects on Resistive Switching of Conductive-Bridging RAM Cells with Cu-Doped SiO2 Films

    Directory of Open Access Journals (Sweden)

    Jian-Yang Lin

    2014-01-01

    Full Text Available SiO2 or Cu-doped SiO2 (Cu:SiO2 insulating films combined with Cu or W upper electrodes were constructed on the W/Si substrates to form the conductive-bridging RAM (CB-RAM cells. The CB-RAMs were then subjected to a constant-voltage stressing (CVS at room temperature. The experimental results show that the room-temperature CVS treatment can effectively affect the current conduction behavior and stabilize the resistive switching of the memory cells. After the CVS, the current conduction mechanisms in the high resistance state during the set process of the Cu/Cu:SiO2/W cell can be changed from Ohm’s law and the space charge limited conduction to Ohm’s law, the Schottky emission, and the space charge limited conduction. Presumably, it is due to the breakage of the conduction filaments during the CVS treatment that the conduction electrons cannot go back to the back electrode smoothly.

  17. In-vitro long term and electrochemical corrosion resistance of cold deformed nitrogen containing austenitic stainless steels in simulated body fluid.

    Science.gov (United States)

    Talha, Mohd; Behera, C K; Sinha, O P

    2014-07-01

    This work was focused on the evaluation of the corrosion behavior of deformed (10% and 20% cold work) and annealed (at 1050 °C for 15 min followed by water quenching) Ni-free high nitrogen austenitic stainless steels (HNSs) in simulated body fluid at 37°C using weight loss method (long term), electrochemical impedance spectroscopy (EIS) and potentiodynamic polarization. Scanning electron microscopy (SEM) was used to understand the surface morphology of the alloys after polarization test. It has been observed that cold working had a significant influence on the corrosion resistant properties of these alloys. The weight loss and corrosion rates were observed to decrease with increasing degree of cold working and nitrogen content in the alloy. The corrosion resistance of the material is directly related to the resistance of the passive oxide film formed on its surface which was enhanced with cold working and nitrogen content. It was also observed that corrosion current densities were decreased and corrosion potentials were shifted to more positive values. By seeing pit morphology under SEM, shallower and smaller pits were associated with HNSs and cold worked samples, indicating that corrosion resistance increases with increasing nitrogen content and degree of cold deformation. X-ray diffraction profiles of annealed as well as deformed alloys were revealed and there is no evidence for formation of martensite or any other secondary phases. Copyright © 2014 Elsevier B.V. All rights reserved.

  18. A Kinetics Study on Electrical Resistivity Transition of In Situ Polymer Aging Sensors Based on Carbon-Black-Filled Epoxy Conductive Polymeric Composites (CPCs)

    Science.gov (United States)

    Liang, Qizhen; Nyugen, Mark T.; Moon, Kyoung-Sik; Watkins, Ken; Morato, Lilian T.; Wong, Ching Ping

    2013-06-01

    Sensors based on carbon-black-filled bisphenol A-type epoxy conductive polymeric composites (CPCs) have been prepared and applied to monitor thermal oxidation aging of polymeric materials. Thermogravimetric analysis (TGA) is applied to characterize weight loss of epoxy resin in the aging process. By using a mathematical model based on the Boltzmann equation, a relationship between the electrical resistivity of the sensors based on epoxy/carbon black composites and aging time is established, making it possible to monitor and estimate the aging status of polymeric components in situ based on a fast and convenient electrical resistance measurement.

  19. Ca(2+) sensitisation of force production by noradrenaline in femoral conductance and resistance arteries from rats with postinfarction congestive heart failure

    DEFF Research Database (Denmark)

    Trautner, Simon; Amtorp, Ole; Boesgaard, Soren

    2006-01-01

    In this study we tested the hypothesis that arterial myofilament Ca(2+) sensitivity and/or the Ca(2+) sensitising effect of noradrenaline (NA) is enhanced in post-infarction congestive heart failure (CHF), which could contribute to the high peripheral vascular resistance in this condition. Femoral...... using wire myography and the FURA-2 fluorescence technique. In conductance and resistance arteries, the resting levels of [Ca(2+)](i) and tension in physiological saline solution (PSS) and active tension in response to single doses of 125 mM K(+) (KPSS) were unaffected by CHF. During cumulative...

  20. Development of Conductivity Method as an Alternative to Titration for Hydrolytic Resistance Testing Used for Evaluation of Glass Vials Used in Pharmaceutical Industry.

    Science.gov (United States)

    Fujimori, Kiyoshi; Lee, Hans; Phillips, Joseph; Nashed-Samuel, Yasser

    The European Pharmacopeia surface test to analyze the hydrolytic resistance is a common industrial method to understand and ensure the quality of produced glass vials. Hydrolytic resistance is evaluated by calculating the alkalinity of water extract from autoclaved vials by titration. As an alternative to this titration technique, a conductivity technique was assessed, which directly measures the ions in the water extract. A conductivity meter with a 12 mm diameter electrode was calibrated with a 100 μS/cm conductivity standard and carryover minimized by rinsing the probe in a water beaker per analysis. The limit of quantification at 1 μS/cm was determined as having a signal-to-noise ratio of 3 compared with the water blank. The conductivity method was selective for glass-composing elements (boron, sodium, aluminum, silicon, potassium, and calcium) within the vial extract. Accuracies of spiked conductivity standard within the range of 1 to 100 μS/cm were ±7% and had linearity with coefficient of determination (R 2 ) of ≥0.9999. Intraday precision had a relative standard deviation (RSD) (n = 5) of ≤6% for spiked conductivity standard within the range of 1 to 100 μS/cm. Interday precision had a RSD (n = 4) of ≤6% for 10 vials from three glass vial lots. Conductivity of water extracts from nine sets of seven lots of glass vials had a precise linear relationship [R 2 = 0.9876, RSD = 1% (n = 9)] with titration volumes of the same lots. Conductivity results in μS/cm could be converted to titration volumes in milliliters by a conversion factor of 0.0275. The simplicity, sample stability, and individual vial analysis of the conductivity technique were more advantageous than the current titration technique. The quality of glass vials used as primary containers in the pharmaceutical industry is of concern due to recent observations of glass flake-like delamination, or lamellae, under specific storage conditions. The current European Pharmacopoeia method to assess

  1. Wide range local resistance imaging on fragile materials by conducting probe atomic force microscopy in intermittent contact mode

    International Nuclear Information System (INIS)

    Vecchiola, Aymeric; Chrétien, Pascal; Schneegans, Olivier; Mencaraglia, Denis; Houzé, Frédéric; Delprat, Sophie; Bouzehouane, Karim; Seneor, Pierre; Mattana, Richard; Tatay, Sergio; Geffroy, Bernard

    2016-01-01

    An imaging technique associating a slowly intermittent contact mode of atomic force microscopy (AFM) with a home-made multi-purpose resistance sensing device is presented. It aims at extending the widespread resistance measurements classically operated in contact mode AFM to broaden their application fields to soft materials (molecular electronics, biology) and fragile or weakly anchored nano-objects, for which nanoscale electrical characterization is highly demanded and often proves to be a challenging task in contact mode. Compared with the state of the art concerning less aggressive solutions for AFM electrical imaging, our technique brings a significantly wider range of resistance measurement (over 10 decades) without any manual switching, which is a major advantage for the characterization of materials with large on-sample resistance variations. After describing the basics of the set-up, we report on preliminary investigations focused on academic samples of self-assembled monolayers with various thicknesses as a demonstrator of the imaging capabilities of our instrument, from qualitative and semi-quantitative viewpoints. Then two application examples are presented, regarding an organic photovoltaic thin film and an array of individual vertical carbon nanotubes. Both attest the relevance of the technique for the control and optimization of technological processes.

  2. Wide range local resistance imaging on fragile materials by conducting probe atomic force microscopy in intermittent contact mode

    Energy Technology Data Exchange (ETDEWEB)

    Vecchiola, Aymeric [Laboratoire de Génie électrique et électronique de Paris (GeePs), UMR 8507 CNRS-CentraleSupélec, Paris-Sud and UPMC Universities, 11 rue Joliot-Curie, Plateau de Moulon, 91192 Gif-sur-Yvette (France); Concept Scientific Instruments, ZA de Courtaboeuf, 2 rue de la Terre de Feu, 91940 Les Ulis (France); Unité Mixte de Physique CNRS-Thales UMR 137, 1 avenue Augustin Fresnel, 91767 Palaiseau (France); Chrétien, Pascal; Schneegans, Olivier; Mencaraglia, Denis; Houzé, Frédéric, E-mail: frederic.houze@geeps.centralesupelec.fr [Laboratoire de Génie électrique et électronique de Paris (GeePs), UMR 8507 CNRS-CentraleSupélec, Paris-Sud and UPMC Universities, 11 rue Joliot-Curie, Plateau de Moulon, 91192 Gif-sur-Yvette (France); Delprat, Sophie [Unité Mixte de Physique CNRS-Thales UMR 137, 1 avenue Augustin Fresnel, 91767 Palaiseau (France); UPMC, Université Paris 06, 4 place Jussieu, 75005 Paris (France); Bouzehouane, Karim; Seneor, Pierre; Mattana, Richard [Unité Mixte de Physique CNRS-Thales UMR 137, 1 avenue Augustin Fresnel, 91767 Palaiseau (France); Tatay, Sergio [Molecular Science Institute, University of Valencia, 46980 Paterna (Spain); Geffroy, Bernard [Lab. Physique des Interfaces et Couches minces (PICM), UMR 7647 CNRS-École polytechnique, 91128 Palaiseau (France); Lab. d' Innovation en Chimie des Surfaces et Nanosciences (LICSEN), NIMBE UMR 3685 CNRS-CEA Saclay, 91191 Gif-sur-Yvette (France); and others

    2016-06-13

    An imaging technique associating a slowly intermittent contact mode of atomic force microscopy (AFM) with a home-made multi-purpose resistance sensing device is presented. It aims at extending the widespread resistance measurements classically operated in contact mode AFM to broaden their application fields to soft materials (molecular electronics, biology) and fragile or weakly anchored nano-objects, for which nanoscale electrical characterization is highly demanded and often proves to be a challenging task in contact mode. Compared with the state of the art concerning less aggressive solutions for AFM electrical imaging, our technique brings a significantly wider range of resistance measurement (over 10 decades) without any manual switching, which is a major advantage for the characterization of materials with large on-sample resistance variations. After describing the basics of the set-up, we report on preliminary investigations focused on academic samples of self-assembled monolayers with various thicknesses as a demonstrator of the imaging capabilities of our instrument, from qualitative and semi-quantitative viewpoints. Then two application examples are presented, regarding an organic photovoltaic thin film and an array of individual vertical carbon nanotubes. Both attest the relevance of the technique for the control and optimization of technological processes.

  3. Geo-electrical investigation of near surface conductive structures suitable for groundwater accumulation in a resistive crystalline basement environment: A case study of Isuada, southwestern Nigeria

    Science.gov (United States)

    Kayode, J. S.; Adelusi, A. O.; Nawawi, M. N. M.; Bawallah, M.; Olowolafe, T. S.

    2016-07-01

    This paper presents a geophysical surveying for groundwater identification in a resistive crystalline basement hard rock in Isuada area, Southwestern Nigeria. Very low frequency (VLF) electromagnetic and electrical resistivity geophysical techniques combined with well log were used to characterize the concealed near surface conductive structures suitable for groundwater accumulation. Prior to this work; little was known about the groundwater potential of this area. Qualitative and semi-quantitative interpretations of the data collected along eight traverses at 20 m spacing discovered conductive zones suspected to be fractures, faults, and cracks which were further mapped using Vertical Electrical Sounding (VES) technique. Forty VES stations were utilized using Schlumberger configurations with AB/2 varying from 1 to 100 m. Four layers i.e. the top soil, the weathered layer, the partially weathered/fractured basement and the fresh basement were delineated from the interpreted resistivity curves. The weathered layers constitute the major aquifer unit in the area and are characterized by moderately low resistivity values which ranged between about 52 Ωm and 270 Ωm while the thickness varied from 1 to 35 m. The depth to the basement and the permeable nature of the weathered layer obtained from both the borehole and the hand-dug wells was used to categorize the groundwater potential of the study area into high, medium and low ratings. The groundwater potential map revealed that about 45% of the study area falls within the low groundwater potential rating while about 10% constitutes the medium groundwater potential and the remaining 45% constitutes high groundwater potential. The low resistivity, thick overburden, and fractured bedrock constitute the aquifer units and the series of basement depressions identified from the geoelectric sections as potential conductive zones appropriate for groundwater development.

  4. Study of the size effects in the electrical resistivity of ultrathin (conduction models

    Energy Technology Data Exchange (ETDEWEB)

    Messaadi, Saci, E-mail: messaadi_saci@yahoo.f [L.E.P.C.M., Departement de physique, Faculte des sciences, Universite de Batna, B.P. C2045, Poste Hadj Lakhdar, Batna 05011 (Algeria); Medouer, Hadria; Daamouche, Mosbah [L.E.P.C.M., Departement de physique, Faculte des sciences, Universite de Batna, B.P. C2045, Poste Hadj Lakhdar, Batna 05011 (Algeria)

    2010-01-21

    In their pioneering experimental work, Liu et al. have given the data related to the in situ sheet resistance measurements of polycrystalline ultrathin Cu films, where the resistivity {rho}, was determined as a function of film thickness d. The aim of this paper is to show that the size effects in polycrystalline ultrathin Cu films can be easily reinterpreted by using a simple analytical expression of the electrical conductivity, earlier proposed in the framework of the multidimensional conduction models. The electronic transport parameters obtained in this study are in good agreement with our previous theoretical works. For this purpose, the study given by the authors which has been interpreted by using the Namba's model is reconsidered.

  5. Fluid and particle mechanics

    CERN Document Server

    Michell, S J

    2013-01-01

    Fluid and Particle Mechanics provides information pertinent to hydraulics or fluid mechanics. This book discusses the properties and behavior of liquids and gases in motion and at rest. Organized into nine chapters, this book begins with an overview of the science of fluid mechanics that is subdivided accordingly into two main branches, namely, fluid statics and fluid dynamics. This text then examines the flowmeter devices used for the measurement of flow of liquids and gases. Other chapters consider the principle of resistance in open channel flow, which is based on improper application of th

  6. The influence of Al(OH)3-coated graphene oxide on improved thermal conductivity and maintained electrical resistivity of Al2O3/epoxy composites

    International Nuclear Information System (INIS)

    Heo, Yuseon; Im, Hyungu; Kim, Jiwon; Kim, Jooheon

    2012-01-01

    This study investigates the thermal and electrical conductivity of Al 2 O 3 /epoxy composites containing graphene oxide and Al(OH) 3 -coated graphene oxide. The functionalized graphene oxide was prepared by sol–gel method with aluminum isopropoxide (AlIP). The aluminum hydroxide layer (50–150 nm) was successfully formed on graphene oxide surface. The introduction of both graphene oxide and Al(OH) 3 -coated graphene oxide in Al 2 O 3 /epoxy composites significantly improved the thermal conductivity due to the high thermal conductivity of graphene-based materials and their role as heat conductive bridges among the Al 2 O 3 particles ( 2 O 3 /epoxy composites-containing 5 wt% graphene oxide and Al(OH) 3 -coated graphene oxide are 3.5 and 3.1 W/mK, respectively. On the other hand, the Al(OH) 3 -coated graphene oxide/Al 2 O 3 /epoxy composites exhibited the more retained electrical resistivity compared with graphene oxide/Al 2 O 3 /epoxy composite. Thus, the Al(OH) 3 -coated graphene oxide composites showed simultaneously improvements in the thermal conductivity and retention of electrical resistivity.

  7. In vitro investigation of biodegradable polymeric coating for corrosion resistance of Mg-6Zn-Ca alloy in simulated body fluid.

    Science.gov (United States)

    Gaur, Swati; Singh Raman, R K; Khanna, A S

    2014-09-01

    A silane-based biodegradable coating was developed and investigated to improve corrosion resistance of an Mg-6Zn-Ca magnesium alloy to delay the biodegradation of the alloy in the physiological environment. Conditions were optimized to develop a stable and uniform hydroxide layer on the alloys surface-known to facilitate silane-substrate adhesion. A composite coating of two silanes, namely, diethylphosphatoethyltriethoxysilane (DEPETES) and bis-[3-(triethoxysilyl) propyl] tetrasulfide (BTESPT), was developed, by the sol-gel route. Corrosion resistance of the coated alloy was characterized in a modified-simulated body fluid (m-SBF), using potentiodynamic polarization and electrochemical impedance spectroscopy (EIS). The silane coating provided significant and durable corrosion resistance. During the course of this, hydrogen evolution and pH variation, if any, were monitored for both bare and coated alloys. The coating morphology was characterized using scanning electron microscopy (SEM) and energy dispersive X-ray analysis (EDAX) and the cross-linking in the coating was studied using Fourier transform infrared spectroscopy (FTIR). As indicated by X-ray diffraction (XRD) results, an important finding was the presence of hydrated magnesium phosphate on the sample that was subjected to immersion in m-SBF for 216h. Magnesium phosphate is reported to support osteoblast formation and tissue healing. Copyright © 2014 Elsevier B.V. All rights reserved.

  8. Clinical Validation of the Analysis of Linezolid and Clarithromycin in Oral Fluid of Patients with Multidrug-Resistant Tuberculosis

    NARCIS (Netherlands)

    Bolhuis, M. S.; van Altena, R.; van Hateren, K.; de Lange, W. C. M.; Greijdanus, B.; Uges, D. R. A.; Kosterink, J. G. W.; van der Werf, T. S.; Alffenaar, J. W. C.

    Linezolid plays an increasingly important role in the treatment of multidrug-resistant tuberculosis (MDR-TB). However, patients should be carefully monitored due to time-and dose-dependent toxicity. Clarithromycin plays a more modest role. Therapeutic drug monitoring may contribute to assessment of

  9. Contact Resistance and Channel Conductance of Graphene Field-Effect Transistors under Low-Energy Electron Irradiation

    Directory of Open Access Journals (Sweden)

    Filippo Giubileo

    2016-11-01

    Full Text Available We studied the effects of low-energy electron beam irradiation up to 10 keV on graphene-based field effect transistors. We fabricated metallic bilayer electrodes to contact mono- and bi-layer graphene flakes on SiO2, obtaining specific contact resistivity ρ c ≈ 19 k Ω · µ m 2 and carrier mobility as high as 4000 cm2·V−1·s−1. By using a highly doped p-Si/SiO2 substrate as the back gate, we analyzed the transport properties of the device and the dependence on the pressure and on the electron bombardment. We demonstrate herein that low energy irradiation is detrimental to the transistor current capability, resulting in an increase in contact resistance and a reduction in carrier mobility, even at electron doses as low as 30 e−/nm2. We also show that irradiated devices recover their pristine state after few repeated electrical measurements.

  10. Model for multi-filamentary conduction in graphene/hexagonal-boron-nitride/graphene based resistive switching devices

    Science.gov (United States)

    Pan, Chengbin; Miranda, Enrique; Villena, Marco A.; Xiao, Na; Jing, Xu; Xie, Xiaoming; Wu, Tianru; Hui, Fei; Shi, Yuanyuan; Lanza, Mario

    2017-06-01

    Despite the enormous interest raised by graphene and related materials, recent global concern about their real usefulness in industry has raised, as there is a preoccupying lack of 2D materials based electronic devices in the market. Moreover, analytical tools capable of describing and predicting the behavior of the devices (which are necessary before facing mass production) are very scarce. In this work we synthesize a resistive random access memory (RRAM) using graphene/hexagonal-boron-nitride/graphene (G/h-BN/G) van der Waals structures, and we develop a compact model that accurately describes its functioning. The devices were fabricated using scalable methods (i.e. CVD for material growth and shadow mask for electrode patterning), and they show reproducible resistive switching (RS). The measured characteristics during the forming, set and reset processes were fitted using the model developed. The model is based on the nonlinear Landauer approach for mesoscopic conductors, in this case atomic-sized filaments formed within the 2D materials system. Besides providing excellent overall fitting results (which have been corroborated in log-log, log-linear and linear-linear plots), the model is able to explain the dispersion of the data obtained from cycle-to-cycle in terms of the particular features of the filamentary paths, mainly their confinement potential barrier height.

  11. Ink for Ink-Jet Printing of Electrically Conductive Structures on Flexible Substrates with Low Thermal Resistance

    Science.gov (United States)

    Mościcki, A.; Smolarek-Nowak, A.; Felba, J.; Kinart, A.

    2017-07-01

    The development of new technologies in electronics related to flexible polymeric substrates forces the industry to introduce suitable tools (special type of dispensers) and modern conductive materials for printing electronic circuits. Moreover, due to the wide use of inexpensive polymeric foils (polyethene, PE, or poly(ethylene terephthalate), PET), there is a need to develop materials with the lowest possible processing temperatures. The present paper presents the selection criteria of suitable components and their preparation for obtaining electrically conductive ink with a special nanosilver base. In the case of the discussed solution, all components allow to make circuits in relatively low sintering temperature (even below 130°C). Additionally, the authors show the most significant ink parameters that should be taken into consideration during Research and Development (R&D) works with electrically conductive inks. Moreover, ink stability parameters are discussed and some examples of printed circuits are presented.

  12. Preparation of Phytic Acid/Silane Hybrid Coating on Magnesium Alloy and Its Corrosion Resistance in Simulated Body Fluid

    Science.gov (United States)

    Wang, Fengwu; Cai, Shu; Shen, Sibo; Yu, Nian; Zhang, Feiyang; Ling, Rui; Li, Yue; Xu, Guohua

    2017-09-01

    In order to decrease the corrosion rate and improve the bioactivity of magnesium alloy, phytic acid/saline hybrid coatings were synthesized on AZ31 magnesium alloys by sol-gel dip-coating method. It was found that the mole ratio of phytic acid to γ-APS had a great influence on coating morphology and the corresponding corrosion resistance of the coated magnesium alloys. When the mole ratio of phytic acid to γ-APS was 1:1, the obtained hybrid coating was integral and without cracks, which was ascribed to the strong chelate capability of phytic acid and Si-O-Si network derived from silane. Electrochemical test result indicated that the corrosion resistance of the coated magnesium alloy was about 27 times larger than that of the naked counterpart. In parallel, immersion test showed that the phytic acid/silane hybrid coating could induce CaP-mineralized product deposition, which offered another protection for magnesium alloy.

  13. Genetic effects on transpiration, canopy conductance, stomatal sensitivity to vapour pressure deficit, and cavitation resistance in loblolly pine

    Science.gov (United States)

    Michael J Aspinwall; John S King; Jean-Christophe Domec; Steven E McKeand; Isik Fikret

    2011-01-01

    Physiological uniformity and genetic effects on canopy-level gas-exchange and hydraulic function could impact loblolly pine (Pinus taeda L.) plantation sustainability and ecosystem dynamics under projected changes in climate. Over a 1-year period, we examined genetic effects on mean and maximum mid-day canopy conductance (Gs, Gsmax...

  14. Fabrication and electrical resistivity of Mo-doped VO2 thin films coated on graphite conductive plates by a sol-gel method

    Energy Technology Data Exchange (ETDEWEB)

    Choi, W.; Jung, H.M.; Um, S. [Hanyang Univ., Seoul (Korea, Republic of). School of Mechanical Engineering

    2008-07-01

    Vanadium oxides (VO2) can be used in optical devices, thermochromic smart windows and sensors. This paper reported on a study in which vanadium pentoxide (V2O5) powder was prepared and mixed with Molybdenum Oxides (MoO3) to form Mo-doped and -undoped VO2 thin films by a sol-gel method on graphite conductive substrates. The micro-structure and chemical compositions of the Mo-doped and -undoped VO2 thin films was investigated using X-Ray diffraction and scanning electron microscopy. Changes in electrical resistivity were measured as a function of the stoichiometric compositions between vanadium and molybdenum. In this study. Mo-doped and -undoped VO2 thin films showed the typical metal to insulator transition (MIT), where temperature range could be adjusted by modifying the dopant atomic ratio. The through-plane substrate structure of the Mo-doped layer influences the electrical resistivity of the graphite substrate. As the amount of the molybdenum increases, the electrical resistivity of the graphite conductive substrate decreases in the lower temperature range below the freezing point of water. The experimental results showed that if carefully controlled, thermal dissipation of VO2 thin films can be used as a self-heating source to melt frozen water with the electrical current flowing through the graphite substrate. 3 refs., 3 figs.

  15. Wood anatomy reveals high theoretical hydraulic conductivity and low resistance to vessel implosion in a Cretaceous fossil forest from northern Mexico.

    Science.gov (United States)

    Martínez-Cabrera, Hugo I; Estrada-Ruiz, Emilio

    2014-01-01

    The Olmos Formation (upper Campanian), with over 60 angiosperm leaf morphotypes, is Mexico's richest Cretaceous flora. Paleoclimate leaf physiognomy estimates indicate that the Olmos paleoforest grew under wet and warm conditions, similar to those present in modern tropical rainforests. Leaf surface area, tree size and climate reconstructions suggest that this was a highly productive system. Efficient carbon fixation requires hydraulic efficiency to meet the evaporative demands of the photosynthetic surface, but it comes at the expense of increased risk of drought-induced cavitation. Here we tested the hypothesis that the Olmos paleoforest had high hydraulic efficiency, but was prone to cavitation. We characterized the hydraulic properties of the Olmos paleoforest using theoretical conductivity (Ks), vessel composition (S) and vessel fraction (F), and measured drought resistance using vessel implosion resistance (t/b)h(2) and the water potential at which there is 50% loss of hydraulic conductivity (P50). We found that the Olmos paleoforest had high hydraulic efficiency, similar to that present in several extant tropical-wet or semi-deciduous forest communities. Remarkably, the fossil flora had the lowest (t/b)h(2), which, together with low median P50 (-1.9 MPa), indicate that the Olmos paleoforest species were extremely vulnerable to drought-induced cavitation. Our findings support paleoclimate inferences from leaf physiognomy and paleoclimatic models suggesting it represented a highly productive wet tropical rainforest. Our results also indicate that the Olmos Formation plants had a large range of water conduction strategies, but more restricted variation in cavitation resistance. These straightforward methods for measuring hydraulic properties, used herein for the first time, can provide useful information on the ecological strategies of paleofloras and on temporal shifts in ecological function of fossil forests chronosequences.

  16. Ingestion of an Amino Acid Electrolyte Beverage during Resistance Exercise Does Not Impact Fluid Shifts into Muscle or Performance

    Directory of Open Access Journals (Sweden)

    JohnEric W. Smith

    2017-06-01

    Full Text Available The purpose of this study was to investigate the impact of ingesting an amino acid-electrolyte (AAE beverage during upper body resistance exercise on transient muscle hypertrophy, exercise performance, markers of muscle damage, and recovery. Participants (n = 15 performed three sets of six repetitions—bench press, lat pull down, incline press, and seated row—followed by three sets of eight repetitions at 75% of the estimated 1 repetition maximum—triceps kickback, hammer curl, triceps push down, and preacher curl—with 90 s of rest between sets. The final set of the push down/preacher curl was performed to failure. Prior to and immediately post-exercise, as well as 24, 48, and 72 h post exercise, cross-sectional muscle thickness was measured. Blood samples were collected prior to exercise, as well as 24, 48, and 72 h post-exercise for serum creatine kinase (CK analysis. No treatment effect was found for muscle cross-sectional area, repetitions to failure, or serum CK. A main effect (p < 0.001 was observed in the change in serum CK levels in the days following the resistance exercise session. The findings of this study suggest that the acute ingestion of a AAE beverage does not alter acute muscle thickness, performance, perceived soreness and weakness, or markers of muscle damage.

  17. Application of own computer program for assessment of brain-fluid index in the medial temporal lobe portions in patients with drug-resistant temporal lobe epilepsy

    International Nuclear Information System (INIS)

    Boguslawska, R.; Skrobowska, E.; Rysz, A.

    2009-01-01

    Background: Epilepsy resistant to pharmacological treatment still remains one of the main problems in contemporary epileptology. The problem most frequently concerns patients with focal epilepsy, with the seizure focus possible to localize. In case of drug-resistant epilepsy, both morphological imaging methods (MR) and manual measurements or volumetry are used. Also functional studies, such as MRS (magnetic resonance spectroscopy), fMRI (functional magnetic resonance), SPECT (single photon emission tomography) and PET (positron emission tomography) are performed. Material/Methods: The study presents application of own computer program based on the method of segmentation of the cerebrospinal fluid (CSF) and the brain tissue. The program calculates automatically the brain-fluin index in the hippocampal region. The material comprises the brain-fluin index results calculated with the presented program in comparison with the method of manual delineation in a group of 50 patients with drug-resistant temporal lobe epilepsy. The program is easy to use, it reads the MR data recorded in DICOM installed on a PC. Results: The brain-fluin index result (expressed as a decimal fraction) is calculated on the basis of 4 consecutive layers examined by MR (evaluating hippocampal structures) performed using SE sequence, and T2-weighted imaging in the frontal plane perpendicular to the long axis of the temporal lobes. The results obtained in epilepsy patients were compared with 24 control subjects. Conclusions: Detailed analysis of the obtained data allowed to conclude that precise hippocampal volume assessment can be obtained by combination of both methods, i.e. manual delineation and automatic calculation of brain-fluin index taking into consideration the total volume of cerebral structures. (authors)

  18. Transmission electron microscopy assessment of conductive-filament formation in Ni-HfO2-Si resistive-switching operational devices

    Science.gov (United States)

    Martín, Gemma; González, Mireia B.; Campabadal, Francesca; Peiró, Francesca; Cornet, Albert; Estradé, Sònia

    2018-01-01

    Resistive random-access memory (ReRAM) devices are currently the object of extensive research to replace flash non-volatile memory. However, elucidation of the conductive-filament formation mechanisms in ReRAM devices at nanoscale is mandatory. In this study, the different states created under real operation conditions of HfO2-based ReRAM devices are characterized through transmission electron microscopy and electron energy-loss spectroscopy. The physical mechanism behind the conductive-filament formation in Ni/HfO2/Si ReRAM devices based on the diffusion of Ni from the electrode to the Si substrate and of Si from the substrate to the electrode through the HfO2 layer is demonstrated.

  19. Enhanced stress corrosion cracking resistance and electrical conductivity of a T761 treated Al-Zn-Mg-Cu alloy thin plate

    Science.gov (United States)

    Chen, Xu; Zhai, Sudan; Gao, Di; Liu, Ye; Xu, Jing; Liu, Yang

    2018-01-01

    The stress corrosion cracking (SCC) behavior, electrical conductivity and mechanical properties of an Al-Zn-Mg-Cu alloy pre-stretched thin plate for wing skin were researched in this paper. The microstructures and SCC fracture surfaces of the alloy treated at different conditions were characterized by transmission electron microscopy, optical microscopy and scanning electron microscopy. Results indicated that with the increasing of aging temperature, the electrical conductivity and the elongation increased greatly, while the strength decreased gradually which were closely associated with the type and morphology of the precipitates. Compared with the T6 treated alloy, the SCC resistance of the T761 treated Al-Zn-Mg-Cu alloy was improved greatly. The SCC behavior of the T6 treated alloy was dominated by anodic dissolution theory, whereas the hydrogen induced cracking controlled the fracture behavior of the T761 treated alloy which was influenced by the morphology of grain boundary precipitates in this investigated alloy.

  20. Anisotropy of the thermal conductivity and electrical resistivity of the SiC/Si biomorphic composite based on a white-eucalyptus biocarbon template

    Science.gov (United States)

    Parfen'eva, L. S.; Orlova, T. S.; Smirnov, B. I.; Smirnov, I. A.; Misiorek, H.; Mucha, J.; Jezowski, A.; de Arellano-Lopez, A. R.; Martinez-Fernandez, J.; Varela-Feria, F. M.

    2006-12-01

    The thermal conductivity κ and electrical resistivity ρ of a cellular ecoceramic, namely, the SiC/Si biomorphic composite, are measured in the temperature range 5 300 K. The SiC/Si biomorphic composite is fabricated using a cellular biocarbon template prepared from white eucalyptus wood by pyrolysis in an argon atmosphere with subsequent infiltration of molten silicon into empty through cellular channels of the template. The temperature dependences κ(T) and ρ(T) of the 3C-SiC/Si biomorphic composite at a silicon content of ˜30 vol % are measured for samples cut out parallel and perpendicular to the direction of tree growth. Data on the anisotropy of the thermal conductivity κ are presented. The behavior of the dependences κ(T) and ρ(T) of the SiC/Si biomorphic composite at different silicon contents is discussed in terms of the results obtained and data available in the literature.

  1. Mapping fluids to subduction megathrust locking and slip behavior

    Science.gov (United States)

    Saffer, Demian M.

    2017-09-01

    In subduction zones, high fluid content and pore pressure are thought to promote aseismic creep, whereas well-drained conditions are thought to promote locking and failure in earthquakes. However, observations directly linking fluid content and seismic coupling remain elusive. Heise et al. (2017) use a magnetotelluric survey to image the electrical resistivity structure of the northern Hikurangi subduction thrust to 30 km depth, as an indicator of interconnected fluid content. The authors document a clear correlation between high resistivity and a distinct geodetically locked patch and between conductive areas and weak coupling. Their study, together with other recent geophysical investigations, provides new evidence for the role of fluids in governing subduction thrust locking.

  2. Understanding the Resistive Switching Phenomena of Stacked Al/Al2O3/Al Thin Films from the Dynamics of Conductive Filaments

    Directory of Open Access Journals (Sweden)

    Joel Molina-Reyes

    2017-01-01

    Full Text Available We present the resistive switching characteristics of Metal-Insulator-Metal (MIM devices based on amorphous Al2O3 which is deposited by Atomic Layer Deposition (ALD. A maximum processing temperature for this memory device is 300°C, making it ideal for Back-End-of-Line (BEOL processing. Although some variations in the forming, set, and reset voltages (VFORM, VSET, and VRESET are obtained for many of the measured MIM devices (mainly due to roughness variations of the MIM interfaces as observed after atomic-force microscopy analysis, the memristor effect has been obtained after cyclic I-V measurements. These resistive transitions in the metal oxide occur for both bipolar and unipolar conditions, while the IOFF/ION ratio is around 4–6 orders of magnitude and is formed at gate voltages of Vg<4 V. In unipolar mode, a gradual reduction in VSET is observed and is related to combined (a incomplete dissolution of conductive filaments (made of oxygen vacancies and metal ions which leaves some residuals and (b thickening of chemically reduced Al2O3 during localized Joule heating. This is important because, by analyzing the macroscopic resistive switching behavior of this MIM structure, we could indirectly relate it to microscopic and/or nanoscopic phenomena responsible for the physical mechanism upon which most of these devices operate.

  3. Thermal contact resistance measurement of conduction cooled binary current lead joint block in cryocooler based self field I-V characterization facility

    Energy Technology Data Exchange (ETDEWEB)

    Kundu, Ananya, E-mail: ananya@ipr.res.in; Das, Subrat Kumar; Agarwal, Anees Bano Pooja; Pradhan, Subrata [Institute for Plasma Research, Bhat, Gandhinagar, Gujarat 382428 (India)

    2016-05-23

    In the present study thermal resistance of conduction cooled current lead joint block employing two different interfacial material namely AlN sheet and Kapton Film have been studied in the temperature range 5K-35K. In each case, the performance of different interlayer materials e.g. Indium foil for moderately pressurized contacts (contact pressure <1 MPa), and Apiezon N Grease, GE varnish for low pressurized contact (contact pressure <1 MPa) is studied. The performances of AlN joint with Indium foil and with Apeizon N Grease are studied and it is observed that the contact resistance reduces more with indium foil as compared to greased contact. The contact resistance measurements of Kapton film with Apiezon N grease and with GE varnish were also carried out in the same temperature range. A comparative study of AlN joint with Indium foil and Kapton with GE varnish as filler material is carried out to demonstrate better candidate material among Kapton and AlN for a particular filler material in the same temperature range.

  4. Apparatus for the measurement of electrical resistivity, Seebeck coefficient, and thermal conductivity of thermoelectric materials between 300 K and 12 K

    Science.gov (United States)

    Martin, Joshua; Nolas, George S.

    2016-01-01

    We have developed a custom apparatus for the consecutive measurement of the electrical resistivity, the Seebeck coefficient, and the thermal conductivity of materials between 300 K and 12 K. These three transport properties provide for a basic understanding of the thermal and electrical properties of materials. They are of fundamental importance in identifying and optimizing new materials for thermoelectric applications. Thermoelectric applications include waste heat recovery for automobile engines and industrial power generators, solid-state refrigeration, and remote power generation for sensors and space probes. The electrical resistivity is measured using a four-probe bipolar technique, the Seebeck coefficient is measured using the quasi-steady-state condition of the differential method in a 2-probe arrangement, and the thermal conductivity is measured using a longitudinal, multiple gradient steady-state technique. We describe the instrumentation and the measurement uncertainty associated with each transport property, each of which is presented with representative measurement comparisons using round robin samples and/or certified reference materials. Transport properties data from this apparatus have supported the identification, development, and phenomenological understanding of novel thermoelectric materials.

  5. Comparative In Vivo Efficacies of Epithelial Lining Fluid Exposures of Tedizolid, Linezolid, and Vancomycin for Methicillin-Resistant Staphylococcus aureus in a Mouse Pneumonia Model

    Science.gov (United States)

    Tessier, Pamela R.; Keel, Rebecca A.; Hagihara, Mao; Crandon, Jared L.

    2012-01-01

    The antibacterial efficacies of tedizolid phosphate (TZD), linezolid, and vancomycin regimens simulating human exposures at the infection site against methicillin-resistant Staphylococcus aureus (MRSA) were compared in an in vivo mouse pneumonia model. Immunocompetent BALB/c mice were orally inoculated with one of three strains of MRSA and subsequently administered 20 mg/kg TZD every 24 hours (q24h), 120 mg/kg linezolid q12h, or 25 mg/kg vancomycin q12h over 24 h. These regimens produced epithelial lining fluid exposures comparable to human exposures observed following intravenous regimens of 200 mg TZD q24h, 600 mg linezolid q12h, and 1 g vancomycin q12h. The differences in CFU after 24 h of treatment were compared between control and treatment groups. Vehicle-dosed control groups increased in bacterial density an average of 1.1 logs. All treatments reduced the bacterial density at 24 h with an average of 1.2, 1.6, and 0.1 logs for TZD, linezolid, and vancomycin, respectively. The efficacy of TZD versus linezolid regimens against the three MRSA isolates was not statistically different (P > 0.05), although both treatments were significantly different from controls. In contrast, the vancomycin regimen was significantly different from TZD against one MRSA isolate and from linezolid against all isolates. The vancomycin regimen was less protective than either the TZD or linezolid regimens, with overall survival of 61.1% versus 94.7% or 89.5%, respectively. At human simulated exposures to epithelial lining fluid, vancomycin resulted in minimal reductions in bacterial counts and higher mortality compared to those of either TZD or linezolid. TZD and linezolid showed similar efficacies in this MRSA pneumonia model. PMID:22354302

  6. Comparative in vivo efficacies of epithelial lining fluid exposures of tedizolid, linezolid, and vancomycin for methicillin-resistant Staphylococcus aureus in a mouse pneumonia model.

    Science.gov (United States)

    Tessier, Pamela R; Keel, Rebecca A; Hagihara, Mao; Crandon, Jared L; Nicolau, David P

    2012-05-01

    The antibacterial efficacies of tedizolid phosphate (TZD), linezolid, and vancomycin regimens simulating human exposures at the infection site against methicillin-resistant Staphylococcus aureus (MRSA) were compared in an in vivo mouse pneumonia model. Immunocompetent BALB/c mice were orally inoculated with one of three strains of MRSA and subsequently administered 20 mg/kg TZD every 24 hours (q24h), 120 mg/kg linezolid q12h, or 25 mg/kg vancomycin q12h over 24 h. These regimens produced epithelial lining fluid exposures comparable to human exposures observed following intravenous regimens of 200 mg TZD q24h, 600 mg linezolid q12h, and 1 g vancomycin q12h. The differences in CFU after 24 h of treatment were compared between control and treatment groups. Vehicle-dosed control groups increased in bacterial density an average of 1.1 logs. All treatments reduced the bacterial density at 24 h with an average of 1.2, 1.6, and 0.1 logs for TZD, linezolid, and vancomycin, respectively. The efficacy of TZD versus linezolid regimens against the three MRSA isolates was not statistically different (P > 0.05), although both treatments were significantly different from controls. In contrast, the vancomycin regimen was significantly different from TZD against one MRSA isolate and from linezolid against all isolates. The vancomycin regimen was less protective than either the TZD or linezolid regimens, with overall survival of 61.1% versus 94.7% or 89.5%, respectively. At human simulated exposures to epithelial lining fluid, vancomycin resulted in minimal reductions in bacterial counts and higher mortality compared to those of either TZD or linezolid. TZD and linezolid showed similar efficacies in this MRSA pneumonia model.

  7. Mechanistic Analysis of Oxygen Vacancy-Driven Conductive Filament Formation in Resistive Random Access Memory Metal/NiO/Metal Structures.

    Science.gov (United States)

    Yildirim, Handan; Pachter, Ruth

    2018-03-13

    Electrically switchable resistive random access memories have drawn much interest as nonvolatile memory device candidates based on metal-insulator-metal (MIM) structure concepts. However, atomic level mechanisms that lead to conductive filament (CF) formation in MIM structures are often lacking, such as for the system with NiO as the oxide layer, which was found promising for resistive random access memory (RRAM) device applications. In this work, using density functional theory with a Hubbard-type on-site Coulomb correction, which we carefully benchmarked, we analyzed the intrinsic propensity toward CF formation in NiO upon introduction of oxygen vacancies, including interfacial effects of Ag or Pt electrodes. First, for stoichiometric MIM structural models, contributions from metal-induced gap states to the electronic density of states (DOS) were identified, accommodating oxygen vacancy states and showing that the interface region is reduced more easily than the bulklike region, for example, for the Ag/NiO/Ag structure. Moreover, a tendency toward oxygen vacancy clustering was demonstrated, important for CF formation. Indeed, by introducing ordered oxygen vacancies into the oxide layer for both MIM models, several extended defect states within the forbidden gap have resulted, which lead to defect-assisted transport. These were shown to be influenced by the spatial distribution and number of oxygen vacancies in the filament, where the degree of reduction of Ni atoms changes based on the immediate surroundings. Projected electronic DOS for individual Ni atoms in regions near and away from oxygen vacancies indicated that those Ni close to oxygen vacancies contribute most to the conductivity. Interestingly, based on charge analyses, these atoms are revealed to undergo significant reduction, generating a locally conductive region in the oxide layer that consists of metallic/near-metallic Ni (Ni 0 ), formed through local reduction.

  8. A case-control study of skin conductance biofeedback on seizure frequency and emotion regulation in drug-resistant temporal lobe epilepsy.

    Science.gov (United States)

    Kotwas, Iliana; McGonigal, Aileen; Khalfa, Stéphanie; Bastien-Toniazzo, Mireille; Bartolomei, Fabrice; Micoulaud-Franchi, Jean-Arthur

    2018-01-01

    This study investigates the physiological basis of effects of skin conductance biofeedback on anxiety disorders, depressive disorders and stress in drug-resistant temporal lobe epilepsy (TLE). This method presents an interest in seizure reduction and improvement in psychiatric comorbidities frequently associated with TLE. Our goal was to better understand the impact of biofeedback on seizure control and on emotional regulation. Fifteen patients with TLE were treated with 12 skin conductance biofeedback sessions and compared with 15 control TLE patients on a waiting list. They were evaluated in terms of seizure frequency, clinical evaluations of anxiety and depression and skin conductance responses (SCR) to five emotions: fear, disgust, sadness, happiness and peacefulness induced by short films. Biofeedback training significantly reduced seizure frequency with a mean reduction of -47.42% in the biofeedback group, while the control group did not differ at the two time measures. A significant improvement was found for depression and trait-anxiety in the biofeedback group but not in the control group. There were no differences on SCR on any emotion after biofeedback treatment. A correlation was found between mean change in SCR over the biofeedback treatment and the reduction of seizure frequency, but not between SCR changes and scores on psychiatric comorbidities. These results show independent effect of biofeedback on mood and seizure control. Improvements in anxiety and depressive symptoms were not related to SCR, whereas improved seizure control was, suggesting differential mechanisms underlying these two phenomena. Copyright © 2017 Elsevier B.V. All rights reserved.

  9. Intermediate Temperature Fluids Life Tests — Theory

    Science.gov (United States)

    Tarau, Calin; Sarraf, David B.; Locci, Ivan E.; Anderson, William G.

    2007-01-01

    There are a number of different applications that could use heat pipes or loop heat pipes (LHPs) in the intermediate temperature range of 450 to 750 K, including space nuclear power system radiators, and high temperature electronics cooling. Potential working fluids include organic fluids, elements, and halides, with halides being the least understood, with only a few life tests conducted. Potential envelope materials for halide working fluids include pure aluminum, aluminum alloys, commercially pure (CP) titanium, titanium alloys, and corrosion resistant superalloys. Life tests were conducted with three halides (AlBr3, SbBr3, and TiCl4) and water in three different envelopes: two aluminum alloys (Al-5052, Al-6061) and CP-2 titanium. The AlBr3 attacked the grain boundaries in the aluminum envelopes, and formed TiAl compounds in the titanium. The SbBr3 was incompatible with the only envelope material that it was tested with, Al-6061. TiCl4 and water were both compatible with CP2-titanium. A theoretical model was developed that uses electromotive force differences to predict the compatibility of halide working fluids with envelope materials. This theory predicts that iron, nickel, and molybdenum are good envelope materials, while aluminum and titanium halides are good working fluids. The model is in good agreement with results from previous life tests, as well as the current life tests.

  10. Intermediate Temperature Fluids Life Tests - Theory

    Science.gov (United States)

    Tarau, Calin; Sarraf, David B.; Locci, Ivan E.; Anderson, William G.

    2008-01-01

    There are a number of different applications that could use heat pipes or loop heat pipes (LHPs) in the intermediate temperature range of 450 to 750 K, including space nuclear power system radiators, and high temperature electronics cooling. Potential working fluids include organic fluids, elements, and halides, with halides being the least understood, with only a few life tests conducted. Potential envelope materials for halide working fluids include pure aluminum, aluminum alloys, commercially pure (CP) titanium, titanium alloys, and corrosion resistant superalloys. Life tests were conducted with three halides (AlBr3, SbBr3, and TiCl4) and water in three different envelopes: two aluminum alloys (Al-5052, Al-6061) and Cp-2 titanium. The AlBr3 attacked the grain boundaries in the aluminum envelopes, and formed TiAl compounds in the titanium. The SbBr3 was incompatible with the only envelope material that it was tested with, Al-6061. TiCl4 and water were both compatible with CP2-titanium. A theoretical model was developed that uses electromotive force differences to predict the compatibility of halide working fluids with envelope materials. This theory predicts that iron, nickel, and molybdenum are good envelope materials, while aluminum and titanium halides are good working fluids. The model is in good agreement with results form previous life tests, as well as the current life tests.

  11. Postimpact heat conduction and compaction-driven fluid flow in the Chesapeake Bay impact structure based on downhole vitrinite reflectance data, ICDP-USGS Eyreville deep core holes and Cape Charles test holes

    Science.gov (United States)

    Malinconico, M.L.; Sanford, W.E.; Wright, Horton W.J.J.

    2009-01-01

    Vitrinite reflectance data from the International Continental Scientific Drilling Program (ICDP)-U.S. Geological Survey (USGS) Eyreville deep cores in the centralcrater moat of the Chesapeake Bay impact structure and the Cape Charles test holes on the central uplift show patterns of postimpact maximum-temperature distribution that result from a combination of conductive and advective heat flow. Within the crater-fill sediment-clast breccia sequence at Eyreville, an isoreflectance (-0.44% Ro) section (525-1096 m depth) is higher than modeled background coastal-plain maturity and shows a pattern typical of advective fluid flow. Below an intervening granite slab, a short interval of sediment-clast breccia (1371-1397 m) shows a sharp increase in reflectance (0.47%-0.91% Ro) caused by conductive heat from the underlying suevite (1397-1474 m). Refl ectance data in the uppermost suevite range from 1.2% to 2.1% Ro. However, heat conduction alone is not sufficient to affect the temperature of sediments more than 100 m above the suevite. Thermal modeling of the Eyreville suevite as a 390 ??C cooling sill-like hot rock layer supplemented by compaction- driven vertical fluid flow (0.046 m/a) of cooling suevitic fluids and deeper basement brines (120 ??C) upward through the sediment breccias closely reproduces the measured reflectance data. This scenario would also replace any marine water trapped in the crater fill with more saline brine, similar to that currently in the crater, and it would produce temperatures sufficient to kill microbes in sediment breccias within 450 m above the synimsuevite. A similar downhole maturity pattern is present in the sediment-clast breccia over the central uplift. High-reflectance (5%-9%) black shale and siltstone clasts in the suevite and sediment-clast breccia record a pre-impact (Paleozoic?) metamorphic event. Previously published maturity data in the annular trough indicate no thermal effect there from impact-related processes. ?? 2009 The

  12. Inner Ear Conductive Hearing Loss and Unilateral Pulsatile Tinnitus Associated with a Dural Arteriovenous Fistula: Case Based Review and Analysis of Relationship between Intracranial Vascular Abnormalities and Inner Ear Fluids

    Directory of Open Access Journals (Sweden)

    Ettore Cassandro

    2015-01-01

    Full Text Available While pulsatile tinnitus (PT and dural arteriovenous fistula (DAVF are not rarely associated, the finding of a conductive hearing loss (CHL in this clinical picture is unusual. Starting from a case of CHL and PT, diagnosed to be due to a DAVF, we analyzed relationship between intracranial vascular abnormalities and inner ear fluids. DAVF was treated with endovascular embolization. Following this, there was a dramatic recovery of PT and of CHL, confirming their cause-effect link with DAVF. We critically evaluated the papers reporting this association. This is the first case of CHL associated with PT and DAVF. We describe the most significant experiences and theories reported in literature, with a personal analysis about the possible relationship between vascular intracranial system and labyrinthine fluids. In conclusion, we believe that this association may be a challenge for otolaryngologists. So we suggest to consider the possibility of a DAVF or other AVMs when PT is associated with CHL, without alterations of tympanic membrane and middle ear tests.

  13. The low resistive and transparent Al-doped SnO{sub 2} films: p-type conductivity, nanostructures and photoluminescence

    Energy Technology Data Exchange (ETDEWEB)

    Benouis, C.E. [Department of Material Technology, Physics Faculty, USTOMB University, BP1505 Oran (Algeria); Benhaliliba, M., E-mail: mbenhaliliba@gmail.com [Department of Material Technology, Physics Faculty, USTOMB University, BP1505 Oran (Algeria); Mouffak, Z. [Department of Electrical and Computer Engineering California State University, Fresno, CA (United States); Avila-Garcia, A. [Cinvestav-IPN, Dept. Ingeniería Eléctrica-SEES, Apdo. Postal 14-740, 07000 México, D.F. (Mexico); Tiburcio-Silver, A. [ITT-DIE, Apdo, Postal 20, Metepec 3, 52176 Estado de Mexico (Mexico); Ortega Lopez, M.; Romano Trujillo, R. [Centro de Investigación en Dispositivos Semiconductores, Instituto de Ciencias-BUAP, 14 Sur y Av. San Claudio, C.U. Puebla, Pue. (Mexico); Ocak, Y.S. [Dicle University, Education Faculty, Science Department, 21280 Diyarbakir (Turkey)

    2014-08-01

    Highlights: • Low resistive and high transparency Al doped SnO{sub 2} films. • Films are deposited onto ITO substrate by spray pyrolysis. • Nanostructured films are revealed. • p-Type conductivity is exhibited. • Photoluminescence of films is studied. - Abstract: In this work, we study the crystalline structure, surface morphology, transmittance, optical bandgap and n/p type inversion of tin oxide (SnO{sub 2}). The Nanostructured films of Al-doped SnO{sub 2} were successfully produced onto ITO-coated glass substrates via the spray pyrolysis method at a deposition temperature of 300 °C. A (1 0 1) and (2 1 1)-oriented tetragonal crystal structure was confirmed by X-ray patterns; and grain sizes varied within the range 8−42 nm. The films were polycrystalline, showing a high transparency in the visible (VIS) and infrared (IR) spectra. The optical bandgap was estimated to be around 3.4 eV. The atomic force microscopy (AFM) analysis showed the nanostructures consisting of nanotips, nanopatches, nanopits and nanobubbles. The samples exhibited high conductivity that ranged from 0.55 to 10{sup 4} (S/cm) at ambient and showed an inversion from n to p-type as well as a degenerate semiconductor characters with a bulk concentration reaching 1.7 x 10{sup 19} cm{sup −3}. The photoluminescence measurements reveal the detection of violet, green and yellow emissions.

  14. Thermal conductivity and Kapitza resistance of cyanate ester epoxy mix and tri-functional epoxy electrical insulations at superfluid helium temperature

    CERN Document Server

    Pietrowicz, S; Jones, S; Canfer, S; Baudouy, B

    2012-01-01

    In the framework of the European Union FP7 project EuCARD, two composite insulation systems made of cyanate ester epoxy mix and tri-functional epoxy (TGPAP-DETDA) with S-glass fiber have been thermally tested as possible candidates to be the electrical insulation of 13 T Nb$_{3}$Sn high field magnets under development for this program. Since it is expected to be operated in pressurized superfluid helium at 1.9 K and 1 atm, the thermal conductivity and the Kapitza resistance are the most important input parameters for the thermal design of this type of magnet and have been determined in this study. For determining these thermal properties, three sheets of each material with different thicknesses varying from 245 μm to 598 μm have been tested in steady-state condition in the temperature range of 1.6 K - 2.0 K. The thermal conductivity for the tri-functional epoxy (TGPAP-DETDA) epoxy resin insulation is found to be k=[(34.2±5.5).T-(16.4±8.2)]×10-3 Wm-1K-1 and for the cyanate ester epoxy k=[(26.8±4.8).T- (9...

  15. Sodium Channel Nav1.8 Underlies TTX-Resistant Axonal Action Potential Conduction in Somatosensory C-Fibers of Distal Cutaneous Nerves.

    Science.gov (United States)

    Klein, Amanda H; Vyshnevska, Alina; Hartke, Timothy V; De Col, Roberto; Mankowski, Joseph L; Turnquist, Brian; Bosmans, Frank; Reeh, Peter W; Schmelz, Martin; Carr, Richard W; Ringkamp, Matthias

    2017-05-17

    Voltage-gated sodium (Na V ) channels are responsible for the initiation and conduction of action potentials within primary afferents. The nine Na V channel isoforms recognized in mammals are often functionally divided into tetrodotoxin (TTX)-sensitive (TTX-s) channels (Na V 1.1-Na V 1.4, Na V 1.6-Na V 1.7) that are blocked by nanomolar concentrations and TTX-resistant (TTX-r) channels (Na V 1.8 and Na V 1.9) inhibited by millimolar concentrations, with Na V 1.5 having an intermediate toxin sensitivity. For small-diameter primary afferent neurons, it is unclear to what extent different Na V channel isoforms are distributed along the peripheral and central branches of their bifurcated axons. To determine the relative contribution of TTX-s and TTX-r channels to action potential conduction in different axonal compartments, we investigated the effects of TTX on C-fiber-mediated compound action potentials (C-CAPs) of proximal and distal peripheral nerve segments and dorsal roots from mice and pigtail monkeys ( Macaca nemestrina ). In the dorsal roots and proximal peripheral nerves of mice and nonhuman primates, TTX reduced the C-CAP amplitude to 16% of the baseline. In contrast, >30% of the C-CAP was resistant to TTX in distal peripheral branches of monkeys and WT and Na V 1.9 -/- mice. In nerves from Na V 1.8 -/- mice, TTX-r C-CAPs could not be detected. These data indicate that Na V 1.8 is the primary isoform underlying TTX-r conduction in distal axons of somatosensory C-fibers. Furthermore, there is a differential spatial distribution of Na V 1.8 within C-fiber axons, being functionally more prominent in the most distal axons and terminal regions. The enrichment of Na V 1.8 in distal axons may provide a useful target in the treatment of pain of peripheral origin. SIGNIFICANCE STATEMENT It is unclear whether individual sodium channel isoforms exert differential roles in action potential conduction along the axonal membrane of nociceptive, unmyelinated peripheral nerve

  16. Resistance of Listeria monocytogenes F2365 cells to synthetic gastric fluid is greater following growth on ready-to-eat deli turkey meat than in brain heart infusion broth.

    Science.gov (United States)

    Peterson, Luke D; Faith, Nancy G; Czuprynski, Charles J

    2007-11-01

    Ready-to-eat (RTE) deli meats have been categorized as high-risk foods for contraction of foodborne listeriosis. Several recent listeriosis outbreaks have been associated with the consumption of RTE deli turkey meat. In this study, we examined whether the growth of Listeria monocytogenes F2365 on commercially prepared RTE deli turkey meat causes listerial cells to become more resistant to inactivation by synthetic gastric fluid (SGF). Listerial cells grown on turkey meat to late logarithmic-early stationary phase were significantly more resistant to SGF at pH 7.0, 5.0, or 3.5 than listerial cells grown in brain heart infusion (BHI) broth. The pH was lower in the fluid in packages of turkey meat than in BHI broth (6.5 versus 7.5). However, listerial cells grown in BHI broth adjusted to a lower pH (6.0) did not exhibit enhanced resistance to SGF. The lesser resistance to SGF of listerial cells grown in BHI broth may be due, in part, to the presence of glucose (0.2%). This study indicates the environment presented by the growth of L. monocytogenes on deli turkey meat affects its ability to survive conditions it encounters in the gastrointestinal tract.

  17. Lithography-free resistance thermometry based technique to accurately measure Seebeck coefficient and electrical conductivity for organic and inorganic thin films

    Science.gov (United States)

    Kumar, Pawan; Repaka, D. V. Maheswar; Hippalgaonkar, Kedar

    2017-12-01

    We have developed a new and accurate technique to measure temperature dependent in-plane Seebeck coefficient and electrical conductivity of organic and inorganic thin films. The measurement device consists of one heater, two thermometers, and a four-probe configuration which is patterned on a substrate of choice using a simple shadow mask. The high resolution in temperature measurements and repeatability of resistance thermometry is leveraged while enabling simple implementation using only a shadow mask for patterning. We calibrate the technique using nickel and poly(3,4-ethylenedioxythiophene):poly(styrenesulfonate) thin films. The error bar for the Seebeck coefficient is less than 1%, almost 10 times better than complementary techniques for thin films. Moreover, our method enables high-throughput characterization of thermoelectric properties of a variety of different large area inorganic and organic thin films that can be prepared by spin coating, drop casting, evaporation, sputtering, or any other growth technique and hence has potential for wide usage in the thermoelectrics and nanoscale transport community to study thin films.

  18. DYNAMICS OF FLUID IN OSCILLATORY FLOW: THE Z COMPONENT

    Directory of Open Access Journals (Sweden)

    V. C. -C. LEE

    2015-10-01

    Full Text Available In an oscillatory flow, the resistance to flow, more appropriately defined as the impedance to flow, is a function of oscillating frequency, which refers to the harmonic composition of the driving pressure wave. Flow in an elastic tube may be resisted in numerous ways such as the fluid viscosity, fluid inertia and tube elasticity. The concept of impedance arises in the dynamics of the ResistanceInductance-Capacitance. In oscillating flow, these represent the fluid viscosity, inertia and tube elasticity. This paper describes the effects of impedance, or the Z component as described in-text of an oscillating flow in a valveless impedance pump using numerical simulation. A one-dimensional lumpedsystem model is chosen to perform the analysis in this study. The simulation domain is a mimic to known experimental model previously conducted by Lee et.al. [18-21]. Impedance-induced flow has shown to be combined effects of fluid viscosity, inertia and tube elasticity. Results presented are in reasonable agreement with experimental results presented in Ref [21] with an estimate of 16% variance. This simple model has shown to predict results with significant values, using simple approximations; and further the understanding of fluid impedance’s role in a valveless impedance pump.

  19. Thyroxine (T4 Transfer from Blood to Cerebrospinal Fluid in Sheep Isolated Perfused Choroid Plexus: Role of Multidrug Resistance-Associated Proteins and Organic Anion Transporting Polypeptides

    Directory of Open Access Journals (Sweden)

    Kazem Zibara

    2017-05-01

    Full Text Available Thyroxine (T4 enters the brain either directly across the blood–brain barrier (BBB or indirectly via the choroid plexus (CP, which forms the blood–cerebrospinal fluid barrier (B-CSF-B. In this study, using isolated perfused CP of the sheep by single-circulation paired tracer and steady-state techniques, T4 transport mechanisms from blood into lateral ventricle CP has been characterized as the first step in the transfer across the B-CSF-B. After removal of sheep brain, the CPs were perfused with 125I-T4 and 14C-mannitol. Unlabeled T4 was applied during single tracer technique to assess the mode of maximum uptake (Umax and the net uptake (Unet on the blood side of the CP. On the other hand, in order to characterize T4 protein transporters, steady-state extraction of 125I-T4 was measured in presence of different inhibitors such as probenecid, verapamil, BCH, or indomethacin. Increasing the concentration of unlabeled-T4 resulted in a significant reduction in Umax%, which was reflected by a complete inhibition of T4 uptake into CP. In fact, the obtained Unet% decreased as the concentration of unlabeled-T4 increased. The addition of probenecid caused a significant inhibition of T4 transport, in comparison to control, reflecting the presence of a carrier mediated process at the basolateral side of the CP and the involvement of multidrug resistance-associated proteins (MRPs: MRP1 and MRP4 and organic anion transporting polypeptides (Oatp1, Oatp2, and Oatp14. Moreover, verapamil, the P-glycoprotein (P-gp substrate, resulted in ~34% decrease in the net extraction of T4, indicating that MDR1 contributes to T4 entry into CSF. Finally, inhibition in the net extraction of T4 caused by BCH or indomethacin suggests, respectively, a role for amino acid “L” system and MRP1/Oatp1 in mediating T4 transfer. The presence of a carrier-mediated transport mechanism for cellular uptake on the basolateral membrane of the CP, mainly P-gp and Oatp2, would account

  20. Prevalence and antibiotic resistance profiles of cerebrospinal fluid pathogens in children with acute bacterial meningitis in Yunnan province, China, 2012-2015.

    Science.gov (United States)

    Jiang, Hongchao; Su, Min; Kui, Liyue; Huang, Hailin; Qiu, Lijuan; Li, Li; Ma, Jing; Du, Tingyi; Fan, Mao; Sun, Qiangming; Liu, Xiaomei

    2017-01-01

    Acute bacterial meningitis is still considered one of the most dangerous infectious diseases in children. To investigate the prevalence and antibiotic resistance profiles of cerebrospinal fluid (CSF) pathogens in children with acute bacterial meningitis in Southwest China, CSF samples from 179 meningitis patients (3 days to 12 years old) with positive culture results were collected from 2012 to 2015. Isolated pathogens were identified using the Vitek-32 system. Gram stain results were used to guide subcultures and susceptibility testing. The antimicrobial susceptibility of isolates was determined using the disc diffusion method. Of the isolates, 50.8% were Gram-positive bacteria, and 49.2% were Gram-negative bacteria. The most prevalent pathogens were E. coli (28.5%), Streptococcus pneumoniae (17.8%), Staphylococcus epidermidis (10.0%), Haemophilus influenzae type b (9.5%), and group B streptococcus (7.2%). In young infants aged ≤3 months, E. coli was the organism most frequently isolated from CSF (39/76; 51.3%), followed by group B streptococcus (13/76; 17.1%) and Streptococcus pneumoniae (8/76; 10.5%). However, in young infants aged >3 months, the most frequently isolated organism was Streptococcus pneumoniae (24/103; 23.3%), followed by Staphylococcus epidermidis (18/103; 17.5%) and Haemophilus influenzae type b (16/103; 15.5%). Antimicrobial susceptibility tests indicated that for E. coli isolates, the susceptibility rates to aminoglycosides ranged from 56.8% to 100.0%, among them, amikacin was identified as the most effective against E. coli. As for cephalosporins, the susceptibility rates ranged from 29.4% to 78.4%, and cefoxitin was identified as the most effective cephalosporin. In addition, the susceptibility rates of piperacillin/tazobactam and imipenem against E. coli were 86.3% and 100%. Meanwhile, the susceptibility rates of Streptococcus pneumoniae isolates to penicillin G, erythromycin, chloramphenicol, ceftriaxone and tetracycline were 68.8%, 0

  1. Conduction heat transfer in a cylindrical dielectric barrier discharge reactor

    Energy Technology Data Exchange (ETDEWEB)

    Sadat, H. [Laboratoire d' Etudes Thermiques, Universite de Poitiers, 40 Avenue du Recteur Pineau, 86022 Poitiers (France)], E-mail: hamou.sadat@univ-poitiers.fr; Dubus, N. [Laboratoire d' Etudes Thermiques, Universite de Poitiers, 40 Avenue du Recteur Pineau, 86022 Poitiers (France); Pinard, L.; Tatibouet, J.M.; Barrault, J. [Laboratoire en catalyse et chimie organique, Universite de Poitiers, 40 Avenue du Recteur Pineau, 86022 Poitiers (France)

    2009-04-15

    The thermal behaviour of a dielectric barrier discharge reactor is studied. The experimental tests are performed on a laboratory reactor with two working fluids: helium and air. A simple heat conduction model for calculating the heat loss is developed. By using temperature measurements in the internal and external electrodes, a thermal resistance of the reactor is defined. Finally, the percentage of the input power that is dissipated to the environment is given.

  2. Fluid Mechanics.

    Science.gov (United States)

    Drazin, Philip

    1987-01-01

    Outlines the contents of Volume II of "Principia" by Sir Isaac Newton. Reviews the contributions of subsequent scientists to the physics of fluid dynamics. Discusses the treatment of fluid mechanics in physics curricula. Highlights a few of the problems of modern research in fluid dynamics. Shows that problems still remain. (CW)

  3. Fluid Interfaces

    DEFF Research Database (Denmark)

    Hansen, Klaus Marius

    2001-01-01

    Fluid interaction, interaction by the user with the system that causes few breakdowns, is essential to many user interfaces. We present two concrete software systems that try to support fluid interaction for different work practices. Furthermore, we present specificity, generality, and minimality...... as design goals for fluid interfaces....

  4. Slip in quantum fluids

    International Nuclear Information System (INIS)

    Einzel, D.; Parpia, J.M.

    1997-01-01

    In this review the authors describe theoretical and experimental investigations of general slip phenomena in context with the flow of the quantum liquids 3 He, 4 He and their mixtures at low temperatures. The phenomena of slip is related to a boundary effect. It occurs when sufficiently dilute gases flow along the wall of an experimental cell. A fluid is said to exhibit slip when the fluid velocity at the wall is not equal to the wall's velocity. Such a situation occurs whenever the wall reflects the fluid particles in a specular-like manner, and/or if the fluid is describable in terms of a dilute ordinary gas (classical fluid) or a dilute gas of thermal excitations (quantum fluid). The slip effect in quantum fluids is discussed theoretically on the basis of generalized Landau-Boltzmann transport equations and generalized to apply to a regime of ballistic motion of the quasiparticles in the fluid. The central result is that the transport coefficient of bulk shear viscosity, which typically enters in the Poiseuille flow resistance and the transverse acoustic impedance, has to be replaced by geometry dependent effective viscosity, which depends on the details of the interaction of the fluid particles with the cell walls. The theoretical results are compared with various experimental data obtained in different geometries and for both Bose and Fermi quantum fluids. Good agreement between experiment and theory is found particularly in the case of pure normal and superfluid 3 He, with discrepancies probably arising because of deficiencies in characterization of the experimental surfaces

  5. Relativistic thermodynamics of fluids

    International Nuclear Information System (INIS)

    Souriau, J.-M.

    1977-05-01

    The relativistic covariant definition of a statistical equilibrium, applied to a perfect gas, involves a 'temperature four-vector', whose direction is the mean velocity of the fluid, and whose length is the reciprocal temperature. The hypothesis of this 'temperature four-vector' being a relevant variable for the description of the dissipative motions of a simple fluid is discussed. The kinematics is defined by using a vector field and measuring the number of molecules. Such a dissipative fluid is subject to motions involving null entropy generation; the 'temperature four-vector' is then a Killing vector; the equations of motion can be completely integrated. Perfect fluids can be studied by this way and the classical results of Lichnerowicz are obtained. In weakly dissipative motions two viscosity coefficient appear together with the heat conductibility coefficient. Two other coefficients perharps measurable on real fluids. Phase transitions and shock waves are described with using the model [fr

  6. Magnetohydraulic flow through a packed bed of electrically conducting spheres

    International Nuclear Information System (INIS)

    Sanders, T.L.

    1985-01-01

    The flow of an electrically conducting fluid through a packed bed of electrically conducting spheres in the presence of a strong magnetic field constitutes a very complex flow situation due to the constant turning of the fluid in and out of magnetic field lines. The interaction of the orthogonal components of the velocity and magnetic field will induce electric fields that are orthogonal to both and the electric fields in turn can cause currents that interact with the magnetic field to generate forces against the direction of flow. The strengths of these generated forces depend primarily upon the closure paths taken by the induced currents which, in turn, depend upon the relative ratio of the electrical resistance of the solid spheres to that of the fluid. Both experimental and analytical analyses of the slow flow of a eutectic mixture of sodium and potassium (NaK) through packed cylinders containing stainless steel spheres in the presence of a strong transverse magnetic field were completed. A theory of magnetohydraulic flow is developed by analogy with the development of hydraulic radius theories of flow through porous media. An exact regional analysis is successfully applied to an infinite bed of electrically conducting spheres with a conducting or non-conducting constraining wall on one side. The equations derived are solved for many different combinations of flowrate, magnetic field strength, porosity, and electrical resistance ratio

  7. Conserved allosteric hot spots in the transmembrane domains of cystic fibrosis transmembrane conductance regulator (CFTR) channels and multidrug resistance protein (MRP) pumps.

    Science.gov (United States)

    Wei, Shipeng; Roessler, Bryan C; Chauvet, Sylvain; Guo, Jingyu; Hartman, John L; Kirk, Kevin L

    2014-07-18

    ATP-binding cassette (ABC) transporters are an ancient family of transmembrane proteins that utilize ATPase activity to move substrates across cell membranes. The ABCC subfamily of the ABC transporters includes active drug exporters (the multidrug resistance proteins (MRPs)) and a unique ATP-gated ion channel (cystic fibrosis transmembrane conductance regulator (CFTR)). The CFTR channel shares gating principles with conventional ligand-gated ion channels, but the allosteric network that couples ATP binding at its nucleotide binding domains (NBDs) with conformational changes in its transmembrane helices (TMs) is poorly defined. It is also unclear whether the mechanisms that govern CFTR gating are conserved with the thermodynamically distinct MRPs. Here we report a new class of gain of function (GOF) mutation of a conserved proline at the base of the pore-lining TM6. Multiple substitutions of this proline promoted ATP-free CFTR activity and activation by the weak agonist, 5'-adenylyl-β,γ-imidodiphosphate (AMP-PNP). TM6 proline mutations exhibited additive GOF effects when combined with a previously reported GOF mutation located in an outer collar of TMs that surrounds the pore-lining TMs. Each TM substitution allosterically rescued the ATP sensitivity of CFTR gating when introduced into an NBD mutant with defective ATP binding. Both classes of GOF mutations also rescued defective drug export by a yeast MRP (Yor1p) with ATP binding defects in its NBDs. We conclude that the conserved TM6 proline helps set the energy barrier to both CFTR channel opening and MRP-mediated drug efflux and that CFTR channels and MRP pumps utilize similar allosteric mechanisms for coupling conformational changes in their translocation pathways to ATP binding at their NBDs. © 2014 by The American Society for Biochemistry and Molecular Biology, Inc.

  8. Fluid dynamics of dilatant fluid

    DEFF Research Database (Denmark)

    Nakanishi, Hiizu; Nagahiro, Shin-ichiro; Mitarai, Namiko

    2012-01-01

    A dense mixture of granules and liquid often shows a severe shear thickening and is called a dilatant fluid. We construct a fluid dynamics model for the dilatant fluid by introducing a phenomenological state variable for a local state of dispersed particles. With simple assumptions for an equation...

  9. GASP: A computer code for calculating the thermodynamic and transport properties for ten fluids: Parahydrogen, helium, neon, methane, nitrogen, carbon monoxide, oxygen, fluorine, argon, and carbon dioxide. [enthalpy, entropy, thermal conductivity, and specific heat

    Science.gov (United States)

    Hendricks, R. C.; Baron, A. K.; Peller, I. C.

    1975-01-01

    A FORTRAN IV subprogram called GASP is discussed which calculates the thermodynamic and transport properties for 10 pure fluids: parahydrogen, helium, neon, methane, nitrogen, carbon monoxide, oxygen, fluorine, argon, and carbon dioxide. The pressure range is generally from 0.1 to 400 atmospheres (to 100 atm for helium and to 1000 atm for hydrogen). The temperature ranges are from the triple point to 300 K for neon; to 500 K for carbon monoxide, oxygen, and fluorine; to 600 K for methane and nitrogen; to 1000 K for argon and carbon dioxide; to 2000 K for hydrogen; and from 6 to 500 K for helium. GASP accepts any two of pressure, temperature and density as input conditions along with pressure, and either entropy or enthalpy. The properties available in any combination as output include temperature, density, pressure, entropy, enthalpy, specific heats, sonic velocity, viscosity, thermal conductivity, and surface tension. The subprogram design is modular so that the user can choose only those subroutines necessary to the calculations.

  10. Materials for ER Fluids

    Science.gov (United States)

    Bloodworth, Robert; Wendt, Eckhard

    Recent improvements in the physical understanding of ER fluids have led to the rational design of new ER materials with improved properties. This paper gives an overview of several recent developments in the formulation of ER fluids, concentrating on new particulate phases for ER dispersions. Examples of homogeneous ER fluids are also discussed. The trend leading to designed ER dispersions is demonstrated by a new class of electrorheological fluids based on non-aqueous polyurethane dispersions. The fluids exhibit an attractive combination of properties: low viscosity, high ER effect, and low conductivity. The dispersed phase consists of a specially developed polyurethane elastomer which solvates and stabilizes metal salts. The polymer network density influences the mobility of the dissolved ions, allowing a surprising degree of control over the ER effect. Properties such as the field strength dependence of the ER-effect, switching response, and conductivity of these fluids correlate directly with changes in the polymer structure. Electrorheological measurements in a couette viscometer (shear-mode) and in a model shock absorber (flow-mode) using a commercial polyurethane-based fluid show that the ER effect is also dependent upon the shearing geometry.

  11. Fluids engineering

    International Nuclear Information System (INIS)

    Anon.

    1991-01-01

    Fluids engineering has played an important role in many applications, from ancient flood control to the design of high-speed compact turbomachinery. New applications of fluids engineering, such as in high-technology materials processing, biotechnology, and advanced combustion systems, have kept up unwaining interest in the subject. More accurate and sophisticated computational and measurement techniques are also constantly being developed and refined. On a more fundamental level, nonlinear dynamics and chaotic behavior of fluid flow are no longer an intellectual curiosity and fluid engineers are increasingly interested in finding practical applications for these emerging sciences. Applications of fluid technology to new areas, as well as the need to improve the design and to enhance the flexibility and reliability of flow-related machines and devices will continue to spur interest in fluids engineering. The objectives of the present seminar were: to exchange current information on arts, science, and technology of fluids engineering; to promote scientific cooperation between the fluids engineering communities of both nations, and to provide an opportunity for the participants and their colleagues to explore possible joint research programs in topics of high priority and mutual interest to both countries. The Seminar provided an excellent forum for reviewing the current state and future needs of fluids engineering for the two nations. With the Seminar ear-marking the first formal scientific exchange between Korea and the United States in the area of fluids engineering, the scope was deliberately left broad and general

  12. Hydraulic properties of a low permeable rupture zone on the Yingxiu-Beichuan fault activated during the Wenchuan earthquake, China : Implications for fluid conduction, fault sealing and dynamic weakening mechanisms

    NARCIS (Netherlands)

    Duan, Qingbao; Yang, Xiaosong; Chen, J.

    2017-01-01

    Fluid transport properties of fault rocks are crucial parameters that affect earthquake nucleation and rupture propagation. In this study, we examined the internal structure, mineral composition and fluid transport properties of fault rocks collected from two shallow boreholes penetrating a granitic

  13. Soil properties affecting wheat yields following drilling-fluid application.

    Science.gov (United States)

    Bauder, T A; Barbarick, K A; Ippolito, J A; Shanahan, J F; Ayers, P D

    2005-01-01

    Oil and gas drilling operations use drilling fluids (mud) to lubricate the drill bit and stem, transport formation cuttings to the surface, and seal off porous geologic formations. Following completion of the well, waste drilling fluid is often applied to cropland. We studied potential changes in soil compaction as indicated by cone penetration resistance, pH, electrical conductivity (EC(e)), sodium adsorption ratio (SAR), extractable soil and total straw and grain trace metal and nutrient concentrations, and winter wheat (Triticum aestivum L. 'TAM 107') grain yield following water-based, bentonitic drilling-fluid application (0-94 Mg ha(-1)) to field test plots. Three methods of application (normal, splash-plate, and spreader-bar) were used to study compaction effects. We measured increasing SAR, EC(e), and pH with drilling-fluid rates, but not to levels detrimental to crop production. Field measurements revealed significantly higher compaction within areas affected by truck travel, but also not enough to affect crop yield. In three of four site years, neither drilling-fluid rate nor application method affected grain yield. Extractions representing plant availability and plant analyses results indicated that drilling fluid did not significantly increase most trace elements or nutrient concentrations. These results support land application of water-based bentonitic drilling fluids as an acceptable practice on well-drained soils using controlled rates.

  14. Analysis of sources of bulk conductivity change in saturated silica sand after unbuffered TCE oxidation by permanganate.

    Science.gov (United States)

    Hort, Ryan D; Revil, André; Munakata-Marr, Junko

    2014-09-01

    Time lapse resistivity surveys could potentially improve monitoring of permanganate-based in situ chemical oxidation (ISCO) of organic contaminants such as trichloroethene (TCE) by tracking changes in subsurface conductivity that result from injection of permanganate and oxidation of the contaminant. Bulk conductivity and pore fluid conductivity changes during unbuffered TCE oxidation using permanganate are examined through laboratory measurements and conductivity modeling using PHREEQC in fluid samples and porous media samples containing silica sand. In fluid samples, oxidation of one TCE molecule produces three chloride ions and one proton, resulting in an increase in fluid electrical conductivity despite the loss of two permanganate ions in the reaction. However, in saturated sand samples in which up to 8mM TCE was oxidized, at least 94% of the fluid conductivity associated with the presence of protons was removed within 3h of sand contact, most likely through protonation of silanol groups found on the surface of the sand grains. Minor conductivity effects most likely associated with pH-dependent reductive dissolution of manganese dioxide were also observed but not accounted for in pore-fluid conductivity modeling. Unaccounted conductivity effects resulted in an under-calculation of post-reaction pore fluid conductivity of 2.1% to 5.5%. Although small increases in the porous media formation factor resulting from precipitation of manganese dioxide were detected (about 3%), these increases could not be confirmed to be statistically significant. Both injection of permanganate and oxidation of TCE cause increases in bulk conductivity that would be detectable through time-lapse resistivity surveys in field conditions. Copyright © 2014 Elsevier B.V. All rights reserved.

  15. Fluid machinery

    International Nuclear Information System (INIS)

    Ha, Jae Hyeon; Son, Byeong Jin

    2001-04-01

    This book tells of definition and classification of fluid machinery, energy equation of incompressible fluid, principle of momentum, classification and structure of pump, size, safety of centrifugal pump, theory and operation of contraction pump, reciprocating pump, rotary pump, special pump, using of water power, classification of water turbine, impulse water turbine, reaction water turbine, pump water turbine, liquid movement apparatus, fluid type control machinery and solid and gas type pneumatic machine.

  16. White Paper: Recommendations on the Conduct of Superiority and Organism-Specific Clinical Trials of Antibacterial Agents for the Treatment of Infections Caused by Drug-Resistant Bacterial Pathogens

    Science.gov (United States)

    2012-01-01

    There is a critical need for new pathways to develop antibacterial agents to treat life-threatening infections caused by highly resistant bacteria. Traditionally, antibacterial agents have been studied in noninferiority clinical trials that focus on one site of infection (eg, pneumonia, intra-abdominal infection). Conduct of superiority trials for infections caused by highly antibiotic-resistant bacteria represents a new, and as yet, untested paradigm for antibacterial drug development. We sought to define feasible trial designs of antibacterial agents that could enable conduct of superiority and organism-specific clinical trials. These recommendations are the results of several years of active dialogue among the white paper's drafters as well as external collaborators and regulatory officials. Our goal is to facilitate conduct of new types of antibacterial clinical trials to enable development and ultimately approval of critically needed new antibacterial agents. PMID:22891041

  17. White paper: recommendations on the conduct of superiority and organism-specific clinical trials of antibacterial agents for the treatment of infections caused by drug-resistant bacterial pathogens.

    Science.gov (United States)

    2012-10-01

    There is a critical need for new pathways to develop antibacterial agents to treat life-threatening infections caused by highly resistant bacteria. Traditionally, antibacterial agents have been studied in noninferiority clinical trials that focus on one site of infection (eg, pneumonia, intra-abdominal infection). Conduct of superiority trials for infections caused by highly antibiotic-resistant bacteria represents a new, and as yet, untested paradigm for antibacterial drug development. We sought to define feasible trial designs of antibacterial agents that could enable conduct of superiority and organism-specific clinical trials. These recommendations are the results of several years of active dialogue among the white paper's drafters as well as external collaborators and regulatory officials. Our goal is to facilitate conduct of new types of antibacterial clinical trials to enable development and ultimately approval of critically needed new antibacterial agents.

  18. Metallic and semi-conducting resistivity behaviour of La0.7Ca0.3- x K x MnO3 ( x = 0.05, 0.1) manganites

    Science.gov (United States)

    Varshney, Dinesh; Dodiya, Neha

    2015-12-01

    The temperature dependence of electrical resistivity, ρ, of ceramic La0.7Ca0.3- x K x MnO3 ( x = 0.05, 0.1) is investigated in metallic and semi-conducting phase. The metallic resistivity is attributed to be caused by electron-phonon, electron-electron and electron-magnon scattering. Substitutions affect average mass and ionic radii of A-site resulting in an increase in Debye temperature θ D attributed to hardening of lattice with K doping. The optical phonon modes shift gradually to lower mode frequencies leading to phonon softening. Estimated resistivity compared with reported metallic resistivity, accordingly ρ diff. = [ ρ exp. - { ρ 0 + ρ e-ph (= ρ ac + ρ op)}], infers electron-electron and electron-magnon dependence over most of the temperature range. Semi-conducting nature is discussed with variable range hopping and small polaron conduction model. The decrease in activation energies and increase in density of states at the Fermi level with enhanced Ca doping is consistently explained by cationic disorder and Mn valence.

  19. Schroedinger fluid

    International Nuclear Information System (INIS)

    Kan, K.K.

    1983-01-01

    The relationship of nuclear internal flow and collective inertia, the difference of this flow from that of a classical fluid, and the approach of this flow to rigid flow in independent-particle model rotation are elucidated by reviewing the theory of Schroedinger fluid and its implications for collective vibration and rotation. (author)

  20. Fluid Dynamics

    DEFF Research Database (Denmark)

    Brorsen, Michael

    These lecture notes are intended mainly for the 7th semester course "Fluid Dynamics" offered by the Study Committee on Civil Engineering, Aalborg University.......These lecture notes are intended mainly for the 7th semester course "Fluid Dynamics" offered by the Study Committee on Civil Engineering, Aalborg University....

  1. Absorption fluids data survey

    Science.gov (United States)

    Macriss, R. A.; Zawacki, T. S.

    Development of improved data for the thermodynamic, transport and physical properties of absorption fluids were studied. A specific objective of this phase of the study is to compile, catalog and coarse screen the available US data of known absorption fluid systems and publish it as a first edition document to be distributed to manufacturers, researchers and others active in absorption heat pump activities. The methodology and findings of the compilation, cataloguing and coarse screening of the available US data on absorption fluid properties and presents current status and future work on this project are summarized. Both in house file and literature searches were undertaken to obtain available US publications with pertinent physical, thermodynamic and transport properties data for absorption fluids. Cross checks of literature searches were also made, using available published bibliographies and literature review articles, to eliminate secondary sources for the data and include only original sources and manuscripts. The properties of these fluids relate to the liquid and/or vapor state, as encountered in normal operation of absorption equipment employing such fluids, and to the crystallization boundary of the liquid phase, where applicable. The actual data were systematically classified according to the type of fluid and property, as well as temperature, pressure and concentration ranges over which data were available. Data were sought for 14 different properties: Vapor-Liquid Equilibria, Crystallization Temperature, Corrosion Characteristics, Heat of Mixing, Liquid-Phase-Densities, Vapor-Liquid-Phase Enthalpies, Specific Heat, Stability, Viscosity, Mass Transfer Rate, Heat Transfer Rate, Thermal Conductivity, Flammability, and Toxicity.

  2. Using post-breakdown conduction study in a MIS structure to better understand the resistive switching mechanism in an MIM stack

    International Nuclear Information System (INIS)

    Wu Xing; Pey, Kin-Leong; Raghavan, Nagarajan; Liu, Wen-Hu; Li Xiang; Bai Ping; Zhang Gang; Bosman, Michel

    2011-01-01

    We apply our understanding of the physics of failure in the post-breakdown regime of high-κ dielectric-based conventional logic transistors having a metal–insulator–semiconductor (MIS) structure to interpret the mechanism of resistive switching in resistive random-access memory (RRAM) technology metal–insulator–metal (MIM) stacks. Oxygen vacancies, gate metal migration and metal filament formation in the gate dielectric which constitute the chemistry of breakdown in the post-breakdown stage of logic gate stacks are attributed to be the mechanisms responsible for the SET process in RRAM technology. In this paper, we draw an analogy between the breakdown study in logic devices and filamentation physics in resistive non-volatile memory.

  3. In search of an optimum plutonium density measurement fluid

    Energy Technology Data Exchange (ETDEWEB)

    Dziewinska, K.M.; Peters, A.M.; Martinez, P.; Dziewinski, J.J.; Davenhall, L.B. [Los Alamos National Lab., Los Alamos, NM (United States); LaVerne, J.A.; Rajesh, P. [Notre Dame Univ., Notre Dame, IN (United States). Radiation Lab.

    2009-07-01

    Density measurements of plutonium metal and its alloys are performed at Los Alamos National Laboratory (LANL) using a technique based on the Archimedes principle. The goal is to find and characterize a fluid for density determination of large objects made of plutonium to replace the currently used monobromobenzene. Physical and chemical properties must be considered while selecting the fluid. Chemical properties of the fluid must ensure low corrosion rates and good resistance to radiological decomposition. The study was carried on to evaluate the corrosion rates of Pu metal cause by FC-43 and the FC-43 decomposition products of radiolysis. The results of these studies proved favourable for this application. The evaluation of the surface reactions between FC-43 and Pu metal will be conducted in the near future. (orig.)

  4. In search of an optimum plutonium density measurement fluid

    International Nuclear Information System (INIS)

    Dziewinska, K.M.; Peters, A.M.; Martinez, P.; Dziewinski, J.J.; Davenhall, L.B.; LaVerne, J.A.; Rajesh, P.

    2009-01-01

    Density measurements of plutonium metal and its alloys are performed at Los Alamos National Laboratory (LANL) using a technique based on the Archimedes principle. The goal is to find and characterize a fluid for density determination of large objects made of plutonium to replace the currently used monobromobenzene. Physical and chemical properties must be considered while selecting the fluid. Chemical properties of the fluid must ensure low corrosion rates and good resistance to radiological decomposition. The study was carried on to evaluate the corrosion rates of Pu metal cause by FC-43 and the FC-43 decomposition products of radiolysis. The results of these studies proved favourable for this application. The evaluation of the surface reactions between FC-43 and Pu metal will be conducted in the near future. (orig.)

  5. Magnetron sputtered Hf-B-Si-C-N films with controlled electrical conductivity and optical transparency, and with ultrahigh oxidation resistance

    Czech Academy of Sciences Publication Activity Database

    Šímová, V.; Vlček, J.; Zuzjaková, Š.; Houška, J.; Shen, Y.; Jiang, J. C.; Meletis, E. I.; Peřina, Vratislav

    2018-01-01

    Roč. 653, č. 5 (2018), s. 333-340 ISSN 0040-6090 R&D Projects: GA MŠk LM2015056 Institutional support: RVO:61389005 Keywords : Hf-B-Si-C-N films * pulsed reactive magnetron sputtering * electrical conductivitiy * optical transparency * high-temperature oxidation resistance Subject RIV: BG - Nuclear, Atomic and Molecular Physics, Colliders OBOR OECD: Nuclear physics Impact factor: 1.879, year: 2016

  6. Thermostating highly confined fluids.

    Science.gov (United States)

    Bernardi, Stefano; Todd, B D; Searles, Debra J

    2010-06-28

    In this work we show how different use of thermostating devices and modeling of walls influence the mechanical and dynamical properties of confined nanofluids. We consider a two dimensional fluid undergoing Couette flow using nonequilibrium molecular dynamics simulations. Because the system is highly inhomogeneous, the density shows strong fluctuations across the channel. We compare the dynamics produced by applying a thermostating device directly to the fluid with that obtained when the wall is thermostated, considering also the effects of using rigid walls. This comparison involves an analysis of the chaoticity of the fluid and evaluation of mechanical properties across the channel. We look at two thermostating devices with either rigid or vibrating atomic walls and compare them with a system only thermostated by conduction through vibrating atomic walls. Sensitive changes are observed in the xy component of the pressure tensor, streaming velocity, and density across the pore and the Lyapunov localization of the fluid. We also find that the fluid slip can be significantly reduced by rigid walls. Our results suggest caution in interpreting the results of systems in which fluid atoms are thermostated and/or wall atoms are constrained to be rigid, such as, for example, water inside carbon nanotubes.

  7. Surface resistance of superconductors - examples from Nb - O systems

    International Nuclear Information System (INIS)

    Palmer, F.

    1988-01-01

    The observed surface resistance of most superconductors can be written as the sum of two terms. R/sub obs/ = R/sub BCS/ + R/sub res/. This paper is divided into three sections. The first section describes the BCS theory of surface resistance in terms of a simplified two-fluid model. The second section describes several possible causes of residual resistance including normal conducting materials, tunneling across cracks in the surface, and direct generation of phonons by the RF electric field. The last section describes recent experiments having to do with the effects of oxide layers on surface resistance. Layers grown in pure oxygen at room temperature were found to have little or no effect, but if these layers are heated to temperatures near 300 0 C, they can alter both the BCS resistance and the residual resistance. Heated oxide layers also increased the dependence of the residual resistance on ambient magnetic field. 31 references, 13 figures, 3 tables

  8. Fouling resistance prediction using artificial neural network nonlinear auto-regressive with exogenous input model based on operating conditions and fluid properties correlations

    Energy Technology Data Exchange (ETDEWEB)

    Biyanto, Totok R. [Department of Engineering Physics, Institute Technology of Sepuluh Nopember Surabaya, Surabaya, Indonesia 60111 (Indonesia)

    2016-06-03

    Fouling in a heat exchanger in Crude Preheat Train (CPT) refinery is an unsolved problem that reduces the plant efficiency, increases fuel consumption and CO{sub 2} emission. The fouling resistance behavior is very complex. It is difficult to develop a model using first principle equation to predict the fouling resistance due to different operating conditions and different crude blends. In this paper, Artificial Neural Networks (ANN) MultiLayer Perceptron (MLP) with input structure using Nonlinear Auto-Regressive with eXogenous (NARX) is utilized to build the fouling resistance model in shell and tube heat exchanger (STHX). The input data of the model are flow rates and temperatures of the streams of the heat exchanger, physical properties of product and crude blend data. This model serves as a predicting tool to optimize operating conditions and preventive maintenance of STHX. The results show that the model can capture the complexity of fouling characteristics in heat exchanger due to thermodynamic conditions and variations in crude oil properties (blends). It was found that the Root Mean Square Error (RMSE) are suitable to capture the nonlinearity and complexity of the STHX fouling resistance during phases of training and validation.

  9. Influence of the MBC/MIC ratio on the antibacterial activity of vancomycin versus linezolid against methicillin-resistant Staphylococcus aureus isolates in a pharmacodynamic model simulating serum and soft tissue interstitial fluid concentrations reported in diabetic patients.

    Science.gov (United States)

    Gonzalez, Natalia; Sevillano, David; Alou, Luis; Cafini, Fabio; Gimenez, Maria-Jose; Gomez-Lus, Maria-Luisa; Prieto, Jose; Aguilar, Lorenzo

    2013-10-01

    To explore serum and tissue pharmacodynamics of linezolid versus vancomycin against methicillin-resistant Staphylococcus aureus (MRSA) clinical isolates with different MBC/MIC ratios. Five strains (vancomycin MIC/MBCs, mg/L) were used: TOL-1 (2/≥64), TOL-2 (1/16), LT-1 and LT-2 (1/8) and NT (1/2). The linezolid MIC/MBC for all strains was 2/≥64 mg/L. A two-compartment dynamic computerized device was used (inocula 10(7) cfu/mL). Free concentrations obtained in serum and interstitial fluid with twice-daily regimens of 1 g of vancomycin or 600 mg of linezolid were simulated over 48 h. ABBCs (differences between control growth curves and killing curves of bacteria exposed to antibiotics; log10 cfu × h/mL) and log10 reductions in initial inocula were calculated. In serum simulations, vancomycin (AUC0-24/MIC = 251.8 for TOL-1 and 503.6 for the remaining strains) was bacteriostatic against strains with MBC/MIC ≥8, but bactericidal against NT. In interstitial fluid simulations (AUC0-24/MIC = 54.6 for TOL-1 and 109.2 for the remaining strains), initial inocula grew in all cases. Linezolid, both in serum (AUC0-24/MIC = 87.0) and in interstitial fluid (AUC0-24/MIC = 130.6) simulations, reduced initial inocula ≥2.2 log10 for all strains (apart from LT-1 in serum simulations that showed a bacteriostatic profile). ABBCs were similar in serum and interstitial fluid with linezolid, but significantly lower in interstitial fluid simulations with vancomycin. From the pharmacodynamic perspective (serum concentrations), vancomycin tolerance should include MBC/MIC ≥8 since strains exhibiting this ratio showed bacteriostatic profiles similar to those obtained with isolates with MBC/MIC ratios of 16 or 32. Insufficient concentrations of vancomycin at the simulated infected site were linked to bacteriological failure. Free concentrations of linezolid at the infection site pharmacodynamically covered MRSA.

  10. On radiative fluids

    International Nuclear Information System (INIS)

    Straumann, N.

    1976-01-01

    The Thomas calculation of the energy-momentum tensor of radiation quanta, which are nearly in thermal equilibrium with a relativistically moving material medium, is simplified and extended to more general transport equations. It is shown that the fluid (matter plus radiation) behaves, independently of the detailed form of the Boltzmann equation, like a relativistic imperfect fluid (in the formulation of Eckart). General expressions for the coefficients of heat conduction, shear viscosity and bulk viscosity are given. Published formulae for these coefficients in special cases are corrected. (Auth.)

  11. Conduct disorder

    Science.gov (United States)

    ... this page: //medlineplus.gov/ency/article/000919.htm Conduct disorder To use the sharing features on this page, please enable JavaScript. Conduct disorder is a set of ongoing emotional and behavioral ...

  12. Conducting Polymers

    Indian Academy of Sciences (India)

    would exhibit electronic conductivity, their conductivities (of compressed pellets) were indeed measured by others, and were found to be .... Polyaniline. Polyphenylene. Polypheny lene- vinylene. Table 1. G!NeRAl I ARTICl! structure. Maximum conductivity Stem Stability. Processability. ~. 1.5 x 105. Reacts with Film not n air.

  13. FLUID- THERMODYNAMIC AND TRANSPORT PROPERTIES OF FLUIDS (IBM PC VERSION)

    Science.gov (United States)

    Fessler, T. E.

    1994-01-01

    The accurate computation of the thermodynamic and transport properties of fluids is a necessity for many engineering calculations. The FLUID program was developed to calculate the thermodynamic and transport properties of pure fluids in both the liquid and gas phases. Fluid properties are calculated using a simple gas model, empirical corrections, and an efficient numerical interpolation scheme. FLUID produces results that are in very good agreement with measured values, while being much faster than older more complex programs developed for the same purpose. A Van der Waals equation of state model is used to obtain approximate state values. These values are corrected for real-gas effects by model correction factors obtained from tables based on experimental data. These tables also accurately compensate for the special circumstances which arise whenever phase conditions occur. Viscosity and thermal conductivity values are computed directly from tables. Interpolation within tables is based on Lagrange's three point formula. A set of tables must be generated for each fluid implemented. FLUID currently contains tables for nine fluids including dry air and steam. The user can add tables for any fluid for which adequate thermal property data is available. The FLUID routine is structured so that it may easily be incorporated into engineering programs. The IBM 360 version of FLUID was developed in 1977. It is written in FORTRAN IV and has been implemented on an IBM 360 with a central memory requirement of approximately 222K of 8 bit bytes. The IBM PC version of FLUID is written in Microsoft FORTRAN 77 and has been implemented on an IBM PC with a memory requirement of 128K of 8 bit bytes. The IBM PC version of FLUID was developed in 1986.

  14. FLUID- THERMODYNAMIC AND TRANSPORT PROPERTIES OF FLUIDS (IBM VERSION)

    Science.gov (United States)

    Fessler, T. E.

    1994-01-01

    The accurate computation of the thermodynamic and transport properties of fluids is a necessity for many engineering calculations. The FLUID program was developed to calculate the thermodynamic and transport properties of pure fluids in both the liquid and gas phases. Fluid properties are calculated using a simple gas model, empirical corrections, and an efficient numerical interpolation scheme. FLUID produces results that are in very good agreement with measured values, while being much faster than older more complex programs developed for the same purpose. A Van der Waals equation of state model is used to obtain approximate state values. These values are corrected for real-gas effects by model correction factors obtained from tables based on experimental data. These tables also accurately compensate for the special circumstances which arise whenever phase conditions occur. Viscosity and thermal conductivity values are computed directly from tables. Interpolation within tables is based on Lagrange's three point formula. A set of tables must be generated for each fluid implemented. FLUID currently contains tables for nine fluids including dry air and steam. The user can add tables for any fluid for which adequate thermal property data is available. The FLUID routine is structured so that it may easily be incorporated into engineering programs. The IBM 360 version of FLUID was developed in 1977. It is written in FORTRAN IV and has been implemented on an IBM 360 with a central memory requirement of approximately 222K of 8 bit bytes. The IBM PC version of FLUID is written in Microsoft FORTRAN 77 and has been implemented on an IBM PC with a memory requirement of 128K of 8 bit bytes. The IBM PC version of FLUID was developed in 1986.

  15. Hazardous fluid leak detector

    Science.gov (United States)

    Gray, Harold E.; McLaurin, Felder M.; Ortiz, Monico; Huth, William A.

    1996-01-01

    A device or system for monitoring for the presence of leaks from a hazardous fluid is disclosed which uses two electrodes immersed in deionized water. A gas is passed through an enclosed space in which a hazardous fluid is contained. Any fumes, vapors, etc. escaping from the containment of the hazardous fluid in the enclosed space are entrained in the gas passing through the enclosed space and transported to a closed vessel containing deionized water and two electrodes partially immersed in the deionized water. The electrodes are connected in series with a power source and a signal, whereby when a sufficient number of ions enter the water from the gas being bubbled through it (indicative of a leak), the water will begin to conduct, thereby allowing current to flow through the water from one electrode to the other electrode to complete the circuit and activate the signal.

  16. Essentials of fluid dynamics with applications to hydraulics, aeronautics, meteorology and other subjets

    CERN Document Server

    Prandtl, Ludwig

    1953-01-01

    Equilibrium of liquids and gases ; kinematics : dynamics of frictionless fluids ; motion of viscous fluids : turbulence : fluid resistance : practical applications ; flow with appreciable volume changes (dynamics of gases) ; miscellaneous topics.

  17. The iron and cerium oxide influence on the electric conductivity and the corrosion resistance of anodized aluminium; A influencia do ferro e do oxido de cerio sobre a condutividade eletrica e a resistencia a corrosao do aluminio anodizado

    Energy Technology Data Exchange (ETDEWEB)

    Souza, Kellie Provazi de

    2006-07-01

    The influence of different treatments on the aluminum system covered with aluminum oxide is investigated. The aluminum anodization in sulphuric media and in mixed sulphuric and phosphoric media was used to alter the corrosion resistance, thickness, coverage degree and microhardness of the anodic oxide. Iron electrodeposition inside the anodic oxide was used to change its electric conductivity and corrosion resistance. Direct and pulsed current were used for iron electrodeposition and the Fe(SO{sub 4}){sub 2}(NH{sub 4}){sub 2}.6H{sub 2}O electrolyte composition was changed with the addition of boric and ascorbic acids. To the sealing treatment the CeCl{sub 3} composition was varied. The energy dispersive x-ray (EDS), the x-ray fluorescence spectroscopy (FRX) and the morphologic analysis by scanning electronic microscopy (SEM) allowed to verify that, the pulsed current increase the iron content inside the anodic layer and that the use of the additives inhibits the iron oxidation. The chronopotentiometric curves obtained during iron electrodeposition indicated that the boric and ascorbic acids mixture increased the electrodeposition process efficiency. The electrochemical impedance spectroscopy (EIE), the Vickers (Hv) microhardness measurements and morphologic analysis evidenced that the sealing treatment improves the corrosion resistance of the anodic film modified with iron. The electrical impedance (EI) technique allowed to prove the electric conductivity increase of the anodized aluminum with iron electrodeposited even after the cerium low concentration treatment. Iron nanowires were prepared by using the anodic oxide pores as template. (author)

  18. Fluid Shifts

    Science.gov (United States)

    Stenger, M. B.; Hargens, A. R.; Dulchavsky, S. A.; Arbeille, P.; Danielson, R. W.; Ebert, D. J.; Garcia, K. M.; Johnston, S. L.; Laurie, S. S.; Lee, S. M. C.; hide

    2017-01-01

    Introduction. NASA's Human Research Program is focused on addressing health risks associated with long-duration missions on the International Space Station (ISS) and future exploration-class missions beyond low Earth orbit. Visual acuity changes observed after short-duration missions were largely transient, but now more than 50 percent of ISS astronauts have experienced more profound, chronic changes with objective structural findings such as optic disc edema, globe flattening and choroidal folds. These structural and functional changes are referred to as the visual impairment and intracranial pressure (VIIP) syndrome. Development of VIIP symptoms may be related to elevated intracranial pressure (ICP) secondary to spaceflight-induced cephalad fluid shifts, but this hypothesis has not been tested. The purpose of this study is to characterize fluid distribution and compartmentalization associated with long-duration spaceflight and to determine if a relation exists with vision changes and other elements of the VIIP syndrome. We also seek to determine whether the magnitude of fluid shifts during spaceflight, as well as any VIIP-related effects of those shifts, are predicted by the crewmember's pre-flight status and responses to acute hemodynamic manipulations, specifically posture changes and lower body negative pressure. Methods. We will examine a variety of physiologic variables in 10 long-duration ISS crewmembers using the test conditions and timeline presented in the figure below. Measures include: (1) fluid compartmentalization (total body water by D2O, extracellular fluid by NaBr, intracellular fluid by calculation, plasma volume by CO rebreathe, interstitial fluid by calculation); (2) forehead/eyelids, tibia, and calcaneus tissue thickness (by ultrasound); (3) vascular dimensions by ultrasound (jugular veins, cerebral and carotid arteries, vertebral arteries and veins, portal vein); (4) vascular dynamics by MRI (head/neck blood flow, cerebrospinal fluid

  19. Thanatochemistry: Study of synovial fluid potassium

    African Journals Online (AJOL)

    Nilesh Keshav Tumram

    2014-03-28

    Mar 28, 2014 ... tion of various body fluids immediately after death.2 Several investigators have tried to find the relation between death interval and postmortem biochemical changes in various body fluids such as blood, serum, cerebrospinal, vitreous, and syno- vial fluid.3 Various studies conducted till now have well estab-.

  20. Effectiveness of Geoelectrical Resistivity Surveys for the Detection of a Debris Flow Causative Water Conducting Zone at KM 9, Gap-Fraser’s Hill Road (FT 148, Fraser’s Hill, Pahang, Malaysia

    Directory of Open Access Journals (Sweden)

    Mohamad Anuri Ghazali

    2013-01-01

    Full Text Available This study reports the findings of resistivity surveys which were conducted at the initiation area of debris flow at KM 9, Fraser’s Hill Gap road (FT148. The study involves three slope parallel survey lines and two lines perpendicular to the slope face. The parallel lines are FH01, FH02, and FH03, while the lines FH04 and FH05 are perpendicular. A granite body was detected at the central part of the east line and is nearest to the ground surface along FH02. The existence of low resistivity zones within the granite body is interpreted as highly fractured, water conducting zones. These zones are continuous as they have been detected in both the east-west as well as the north-south lines. The residual soil layer is relatively thin at zones where weathered granite dominates the slope face of the failure mass. The weak layer is relatively thick with an estimated thickness of 80 m and water flow occurs at the base of it. The high water flow recorded from the horizontal drains further supports the possible existence of these highly fractured, water conducting zones located within the granite. The shallow fractured granite is virtually “floating” above the water saturated zone and therefore is considered unstable.

  1. Electrically Conductive Epoxy Adhesives

    Directory of Open Access Journals (Sweden)

    Lan Bai

    2011-02-01

    Full Text Available Conductive adhesives are widely used in electronic packaging applications such as die attachment and solderless interconnections, component repair, display interconnections, and heat dissipation. The effects of film thickness as functions of filler volume fraction, conductive filler size, shape, as well as uncured adhesive matrix viscosity on the electrical conduction behavior of epoxy-based adhesives are presented in this work. For this purpose, epoxy-based adhesives were prepared using conductive fillers of different size, shape, and types, including Ni powder, flakes, and filaments, Ag powder, and Cu powder. The filaments were 20 μm in diameter, and 160 or 260 μm in length. HCl and H3PO4 acid solutions were used to etch and remove the surface oxide layers from the fillers. The plane resistance of filled adhesive films was measured using the four-point method. In all cases of conductive filler addition, the planar resistivity levels for the composite adhesive films increased when the film thickness was reduced. The shape of resistivity-thickness curves was negative exponential decaying type and was modeled using a mathematical relation. The relationships between the conductive film resistivities and the filler volume fractions were also derived mathematically based on the experimental data. Thus, the effects of surface treatment of filler particles, the type, size, shape of fillers, and the uncured epoxy viscosity could be included empirically by using these mathematical relations based on the experimental data. By utilizing the relations we proposed to model thickness-dependent and volume fraction-dependent conduction behaviors separately, we were able to describe the combined and coupled volume fraction-film thickness relationship mathematically based on our experimental data.

  2. Conduct Disorder

    Science.gov (United States)

    ... do not receive early and comprehensive treatment . Without treatment, many youngsters with conduct disorder are unable to adapt to the demands of ... break laws or behave in an antisocial manner. Treatment of children with conduct disorder can be complex and challenging. Treatment can be ...

  3. Temporary formation of highly conducting domain walls for non-destructive read-out of ferroelectric domain-wall resistance switching memories

    Science.gov (United States)

    Jiang, Jun; Bai, Zi Long; Chen, Zhi Hui; He, Long; Zhang, David Wei; Zhang, Qing Hua; Shi, Jin An; Park, Min Hyuk; Scott, James F.; Hwang, Cheol Seong; Jiang, An Quan

    2018-01-01

    Erasable conductive domain walls in insulating ferroelectric thin films can be used for non-destructive electrical read-out of the polarization states in ferroelectric memories. Still, the domain-wall currents extracted by these devices have not yet reached the intensity and stability required to drive read-out circuits operating at high speeds. This study demonstrated non-destructive read-out of digital data stored using specific domain-wall configurations in epitaxial BiFeO3 thin films formed in mesa-geometry structures. Partially switched domains, which enable the formation of conductive walls during the read operation, spontaneously retract when the read voltage is removed, reducing the accumulation of mobile defects at the domain walls and potentially improving the device stability. Three-terminal memory devices produced 14 nA read currents at an operating voltage of 5 V, and operated up to T = 85 °C. The gap length can also be smaller than the film thickness, allowing the realization of ferroelectric memories with device dimensions far below 100 nm.

  4. Electrical resistivity measurements to predict abrasion resistance of ...

    Indian Academy of Sciences (India)

    WINTEC

    39⋅0. 2⋅29. 4⋅04. Figure 1. Resistivity measurement system. pore fluid salinity, pore fluid saturation, temperature and pressure were kept the same. Resistivity measurements were performed on cylindri- cal samples of 54⋅4 mm diameter and ~ 50 mm length. Axial end surfaces of the samples were ground flat and parallel.

  5. Fluid flow distribution optimization for minimizing the peak temperature of a tubular solar receiver

    International Nuclear Information System (INIS)

    Wei, Min; Fan, Yilin; Luo, Lingai; Flamant, Gilles

    2015-01-01

    High temperature solar receiver is a core component of solar thermal power plants. However, non-uniform solar irradiation on the receiver walls and flow maldistribution of heat transfer fluid inside the tubes may cause the excessive peak temperature, consequently leading to the reduced lifetime. This paper presents an original CFD (computational fluid dynamics)-based evolutionary algorithm to determine the optimal fluid distribution in a tubular solar receiver for the minimization of its peak temperature. A pressurized-air solar receiver comprising of 45 parallel tubes subjected to a Gaussian-shape net heat flux absorbed by the receiver is used for study. Two optimality criteria are used for the algorithm: identical outlet fluid temperatures and identical temperatures on the centerline of the heated surface. The influences of different filling materials and thermal contact resistances on the optimal fluid distribution and on the peak temperature reduction are also evaluated and discussed. Results show that the fluid distribution optimization using the algorithm could minimize the peak temperature of the receiver under the optimality criterion of identical temperatures on the centerline. Different shapes of optimal fluid distribution are determined for various filling materials. Cheap material with low thermal conductivity can also meet the peak temperature threshold through optimizing the fluid distribution. - Highlights: • A 3D pressurized-air solar receiver based on the tube-in-matrix concept is studied. • An original evolutionary algorithm is developed for fluid distribution optimization. • A new optimality criterion is proposed for minimizing the receiver peak temperature. • Different optimal fluid distributions are determined for various filling materials. • Filling material with high thermal conductivity is more favorable in practical use.

  6. Fluid Mechanics

    Science.gov (United States)

    Pnueli, David; Gutfinger, Chaim

    1997-01-01

    This text is intended for the study of fluid mechanics at an intermediate level. The presentation starts with basic concepts, in order to form a sound conceptual structure that can support engineering applications and encourage further learning. The presentation is exact, incorporating both the mathematics involved and the physics needed to understand the various phenomena in fluid mechanics. Where a didactical choice must be made between the two, the physics prevails. Throughout the book the authors have tried to reach a balance between exact presentation, intuitive grasp of new ideas, and creative applications of concepts. This approach is reflected in the examples presented in the text and in the exercises given at the end of each chapter. Subjects treated are hydrostatics, viscous flow, similitude and order of magnitude, creeping flow, potential flow, boundary layer flow, turbulent flow, compressible flow, and non-Newtonian flows. This book is ideal for advanced undergraduate students in mechanical, chemical, aerospace, and civil engineering. Solutions manual available.

  7. Electrical Conductivity.

    Science.gov (United States)

    Hershey, David R.; Sand, Susan

    1993-01-01

    Explains how electrical conductivity (EC) can be used to measure ion concentration in solutions. Describes instrumentation for the measurement, temperature dependence and EC, and the EC of common substances. (PR)

  8. Fluid dynamics

    CERN Document Server

    Ruban, Anatoly I

    This is the first book in a four-part series designed to give a comprehensive and coherent description of Fluid Dynamics, starting with chapters on classical theory suitable for an introductory undergraduate lecture course, and then progressing through more advanced material up to the level of modern research in the field. The present Part 1 consists of four chapters. Chapter 1 begins with a discussion of Continuum Hypothesis, which is followed by an introduction to macroscopic functions, the velocity vector, pressure, density, and enthalpy. We then analyse the forces acting inside a fluid, and deduce the Navier-Stokes equations for incompressible and compressible fluids in Cartesian and curvilinear coordinates. In Chapter 2 we study the properties of a number of flows that are presented by the so-called exact solutions of the Navier-Stokes equations, including the Couette flow between two parallel plates, Hagen-Poiseuille flow through a pipe, and Karman flow above an infinite rotating disk. Chapter 3 is d...

  9. Fundamental Issues of Nano-fluid Behavior

    International Nuclear Information System (INIS)

    Williams, Wesley C.

    2006-01-01

    This paper will elucidate some of the behaviors of nano-fluids other than the abnormal conductivity enhancement, which are of importance to the experimental and engineering use of nano-fluids. Nano-fluid is the common name of any sol colloid involving nano-scale (less than 100 nm) sized particles dispersed within a base fluid. It has been shown previously that the dispersion of nano-particulate metallic oxides into water can increase thermal conductivity up to 30-40% over that of the base fluid and anomalously more than the mere weighed average of the colloid. There is a great potential for the use of nano-fluids as a way to enhance fluid/thermal energy transfer systems. Due to the recentness of nano-fluid science, there are still many issues which have not been fully investigated. This paper should act as a primer for the basic understanding of nano-fluid behavior. Particle size and colloid stability are of key importance to the functionality of nano-fluids. The pH and concentration/loading of nano-fluids can alter the size of the nano-particles and also the stability of the fluids. It will be shown through experiment and colloid theory the importance of these parameters. Furthermore, most of the existing literature uses volume percentage as the measure of particle loading, which can often be misleading. There will be discussion of this and other misleading ideas in nano-fluid science. (author)

  10. Effect of Density and Resistivity Measurement for Foam Flooding Propagation in Static Condition

    Science.gov (United States)

    Irawan, S.; Permatasari, K. A.; Bayuaji, R.

    2017-11-01

    Foam flooding is one of the method that is currently used to optimize the amount of oil in sub surface. Foam flooding is used to overcome the weakness of water injection, gas injection, and water alternating gas injection. Foam is the mixture of gas, water and surfactant. Foam propagation plays an important part in porous medium, foam propagation is related to intrinsic properties of the fluids such as density and viscosity. Resistivity of the fluids should be taken also because in the end of the experiment, method that is used to track foam propagation in porous medium is resistivity measurement. The objectives of this experiment are to obtain fluid characterization and to understand the phenomena that is possibly occurred during foam injection in porous medium, specifically, to obtain the correlation between density and resistivity measurement. Foam is generated with several concentration of solutions which are various concentration of brine, various concentration of MFOMAX, oil, and distilled water. Several tests should be taken to observe the intrinsic properties of the fluids such as density test, viscosity test, resistivity and conductivity test. Based on the experiment, correlation between density of brine and brine concentration towards resistivity is inversely proportional. Correlation between density of fluid mix with MFOMAX and MFOMAX concentration towards resistivity is proportional.

  11. Measurements and theoretical modeling of effective thermal conductivity of particle beds under compression in air and vacuum

    Directory of Open Access Journals (Sweden)

    Jingwen Mo

    2017-09-01

    Full Text Available Effective thermal conductivity experiments were carried out with spherical particle beds under low and high compressive pressure loading in vacuum and air. A theoretical model was proposed for the effective thermal conductivity of particle beds based on the experimental results. The model incorporates heat conduction by particles including contact thermal resistance between particles, conduction through the gas in between particles, and radiation between particles, and includes two fitting parameters, namely the coefficient of heat conducted through the fluid, and the macro-contact thermal resistance. The predictions from the theoretical model satisfactorily match the experimental data for the bed effective thermal conductivity over the range of applied loading pressures on particles with different Young's modulus and the gas environment. The model can be used generally to describe the effect of compression stress or pressure on effective thermal conductivity of particle beds.

  12. Dynamic fluid loss characteristics of foam fracturing fluids

    Energy Technology Data Exchange (ETDEWEB)

    Harris, P.C.

    1982-09-01

    Dynamic fluid loss measurements were conducted on core samples ranging in permeability between 0.02 to 140 md. These tests were run to measure the effect of several parameters on the foam fluid loss coefficients. The parameters tested were: core permeability, gel concentration in the liquid phase, foam quality, temperature, core length and differential test pressure. The type of foam that is used in most conventional fracturing treatments is a wall building fluid. Although this foam has excellent inherent fluid loss properties, the fluid loss values reported in this paper more closely resemble those of conventional fracturing fluids than reported earlier. These values have been used in the successful design of field fracturing treatments. These data support the mechanism of two phase flow in porous media suggested by Holm. The fluid passing through the cores was rich in liquid phase with composition proportional to the viscosity of the liquid phase. The broad range of fluid loss coefficients for foam calculated in these tests are intermediate in value to those reported in similar tests by Blauer and Kohlhaas, who obtained lower values, and King, who obtained higher values.

  13. Controlled Source Electromagnetic Monitoring of Hydraulic Fracturing: Wellbore and Fluid Effects

    Science.gov (United States)

    Couchman, M. J.; Everett, M. E.

    2017-12-01

    As unconventional resources become increasingly important, we must tackle the issue of real-time monitoring of the efficiency of unconventional hydrocarbon extraction. Controlled Source Electromagnetics (CSEM) have been used primarily as a marine-based technique to monitor conventional oil bearing reservoirs with a strong resurgence the new millennium. Many of these studies revolving around detecting a thin resistive layer such as a reservoir at 1m - 3km depth. In these cases, the presence of the resistive layer is characterized by a jump in electric field amplitude recorded at the boundary between the layer and the host sediments. The lessons learned from these studies can be applied to terrestrial unconventional settings with appropriate modifications. The work shown here is a means develop methods which enable more reliable terrestrial CSEM monitoring of the flow of injected fluids associated with hydraulic fracturing of unconventional reservoirs and to detect subsurface fluids based on their CSEM signature and in turn, to infer the subsurface flow of electrically conductive injected fluids. The predictive model validated for various 1-D marine, and terrestrial cases focus on the mapping of fluid flow in from a horizontal wellbore in a uniform halfspace using an in-line Horizontal Electric Dipole (HED) with electric field amplitude recorded by an array of electric field sensors. The effect of the of the vertical and horizontal wellbores are documented taking into account the conductivity, size, and thickness of each wellbore. The fracturing fluids flow and conductivity are also taken into account throughout various stages of the fracturing process. In each case, the sensitivity at a location of the surface in-line electric field to a given resistive or conductive layer, due to a source is calculated.

  14. Monitoring percolation of a conductive tracer, as a proxy for nitrate transport, through glacial till and fractured sandstone in the vadose zone underlying a potato field, using 3D cross-hole electrical resistivity imaging

    Science.gov (United States)

    Wang, S.; Butler, K. E.; Serban, D.; Petersen, B.; Grimmett, M.

    2016-12-01

    Nitrate is a necessary nutrient for crops, but high surface water and groundwater concentrations can negatively affect aquatic ecosystem and human health. At AAFC-AAC Harrington Research Farm (PEI, Canada), 3D cross-hole electrical resistivity imaging (ERI) is being used to investigate the percolation of a conductive tracer (KCl) through a 17 m thick vadose zone as a proxy for the transport of nitrate under natural recharge conditions. The objectives are to investigate the effect of heterogeneity on transport pathways and infer how long it would take for changes in farming practices at the surface to affect nitrate loading to the underlying aquifer. The resistivity array consists of 96 permanently installed electrodes - 24 at 0.68 m spacing in each of three 16 m deep boreholes arranged in a triangle with 9 m sides, and 24 at 1 m spacing buried in shallow trenches connecting the boreholes. A background survey revealed five sub-horizontal layers of alternating resistivity in general agreement with the geology of 6 m soil and glacial till overburden overlying interbedded sandstone and shaley sandstone layers. On March 27th, 2015, 1.1 m of snow was removed from a 15.2 m2 area positioned symmetrically inside the triangular array and 100 kg of granular KCl was distributed on the ground surface. The removed snow was immediately replaced to await the spring thaw. Post-tracer surveys indicate tracer had percolated to depths of 1 m, 1.2 m, 3.0 m and 3.5 m by the 4th, 26th, 30th, and 46th days after tracer application. Its movement slowed significantly by early May, 2015, with the end of snow melt. Tracer spread laterally very slowly through the summer and early fall, 2015, but has remained within the triangular array. The shallow conductivity anomaly produced by the tracer diminished significantly over the winter and spring of 2016 but showed little evidence of bulk matrix flow below 3.5 m depth. It is speculated that fractures in the glacial till, too thin to be resolved by

  15. Fluid mechanics

    International Nuclear Information System (INIS)

    Paraschivoiu, I.; Prud'homme, M.; Robillard, L.; Vasseur, P.

    2003-01-01

    This book constitutes at the same time theoretical and practical base relating to the phenomena associated with fluid mechanics. The concept of continuum is at the base of the approach developed in this work. The general advance proceeds of simple balances of forces as into hydrostatic to more complex situations or inertias, the internal stresses and the constraints of Reynolds are taken into account. This advance is not only theoretical but contains many applications in the form of solved problems, each chapter ending in a series of suggested problems. The major part of the applications relates to the incompressible flows

  16. Fluid Sounds

    DEFF Research Database (Denmark)

    and in architectural design. Aesthetics, psychoacoustics, perception, and cognition are all present in this expanding field embracing such categories as soundscape composition, sound art, sonic art, sound design, sound studies and auditory culture. Of greatest significance to the overall field is the investigation...... of sound, site and the social, and how the spatial, the visual, and the bodily interact in sonic environments, how they are constructed and how they are entangled in other practices. With the Seismograf special issue Fluid Sounds, we bring this knowledge into the dissemination of audio research itself...

  17. Synthesis and characterization of silver doped hydroxyapatite nanocomposite coatings and evaluation of their antibacterial and corrosion resistance properties in simulated body fluid.

    Science.gov (United States)

    Mirzaee, Majid; Vaezi, Mohammadreza; Palizdar, Yahya

    2016-12-01

    Silver-doped hydroxyapatite (Ca10-xAgx(PO4)6(OH)2-x) films were synthesized and deposited on anodized titanium (Ti) using electrophoretic. The influence of different silver-dopant contents (X=0, 0.02, 0.05, 0.08 and 0.1) on the phase formation and microstructure of the powders were characterized by means of X-ray diffraction (XRD), transmission electron microscopy (TEM), X-ray photoelectron spectroscope (XPS), and Fourier transform infrared spectrum analysis (FT-IR). XRD analysis confirmed the formation of Hexagonal structure of hydroxyapatite (HAp) annealed at 600°C with a small shift in the major peak position toward lower angles with adding silver. FT-IR spectroscopy disclosed the presence of the different vibrational modes matching to phosphates and hydroxyl groups and the absence of any band characteristics to silver. XPS analysis showed that 75% and 23% of silver was in the chemical states of Ag(2+) and Ag(+), respectively. However, only about 2% of silver was in the Ag(0) state, resulting in the high quality of nanocomposite films. The anodization treatment improves the bond strength between the Ag doped HAp deposited layers on TiO2. HAp and silver doped HAp (X=0.05) are regarded to be hydrophilic due to a large number of -OH groups on the surface. The sample with content of silver (x=0.05) also showed excellent antimicrobial efficacy (>99% reduction in viable cells). Electrochemical reveals the passive current densities of the HAp coated anodized Ti are lower than those of silver doped HAp coated anodized Ti, leading to a slightly lower corrosion resistance. Copyright © 2016 Elsevier B.V. All rights reserved.

  18. Principles of fluid mechanics

    International Nuclear Information System (INIS)

    Kreider, J.F.

    1985-01-01

    This book is an introduction on fluid mechanics incorporating computer applications. Topics covered are as follows: brief history; what is a fluid; two classes of fluids: liquids and gases; the continuum model of a fluid; methods of analyzing fluid flows; important characteristics of fluids; fundamentals and equations of motion; fluid statics; dimensional analysis and the similarity principle; laminar internal flows; ideal flow; external laminar and channel flows; turbulent flow; compressible flow; fluid flow measurements

  19. Conducting Polymers

    Indian Academy of Sciences (India)

    backbone (by the process of doping) and make them electrically. Conducting Polymers. From a Laboratory Curiosity to the Market Place. S Ramakrishnan ..... switching occurs between transparent yellow and green in less than. 100ms. Thus, while these materials are yet to achieve the set target. (in terms of their life cycle) ...

  20. Conducting Polymers

    Indian Academy of Sciences (India)

    Home; Journals; Resonance – Journal of Science Education; Volume 16; Issue 12. Conducting Polymers - From a Laboratory Curiosity to the Market Place. S Ramakrishnan. Volume 16 Issue 12 December 2011 pp 1254-1265. Fulltext. Click here to view fulltext PDF. Permanent link:

  1. Conduct disorders

    NARCIS (Netherlands)

    Buitelaar, J.K.; Smeets, K.C.; Herpers, P.; Scheepers, F.; Glennon, J.; Rommelse, N.N.J.

    2013-01-01

    Conduct disorder (CD) is a frequently occurring psychiatric disorder characterized by a persistent pattern of aggressive and non-aggressive rule breaking antisocial behaviours that lead to considerable burden for the patients themselves, their family and society. This review paper updates diagnostic

  2. Materials processing using supercritical fluids

    Directory of Open Access Journals (Sweden)

    Orlović Aleksandar M.

    2005-01-01

    Full Text Available One of the most interesting areas of supercritical fluids applications is the processing of novel materials. These new materials are designed to meet specific requirements and to make possible new applications in Pharmaceuticals design, heterogeneous catalysis, micro- and nano-particles with unique structures, special insulating materials, super capacitors and other special technical materials. Two distinct possibilities to apply supercritical fluids in processing of materials: synthesis of materials in supercritical fluid environment and/or further processing of already obtained materials with the help of supercritical fluids. By adjusting synthesis parameters the properties of supercritical fluids can be significantly altered which further results in the materials with different structures. Unique materials can be also obtained by conducting synthesis in quite specific environments like reversed micelles. This paper is mainly devoted to processing of previously synthesized materials which are further processed using supercritical fluids. Several new methods have been developed to produce micro- and nano-particles with the use of supercritical fluids. The following methods: rapid expansion of supercritical solutions (RESS supercritical anti-solvent (SAS, materials synthesis under supercritical conditions and encapsulation and coating using supercritical fluids were recently developed.

  3. Magnetorheological Fluids and Elastomers

    Science.gov (United States)

    Ginder, John

    2002-03-01

    Magnetorheological (MR) materials possess mechanical or rheological properties that can be controlled by magnetic fields. MR fluids, perhaps the prototypical MR materials, comprise magnetically soft particles dispersed in polar or nonpolar liquids. The particles in these fluids align to form chains or more complex structures when a magnetic field is applied; these structures resist mechanical deformation, reversibly transforming the fluid into a weak viscoelastic solid. Other MR materials include magnetic powders, in which the magnetic particles are dispersed in air and which also become weak solids in an applied field. MR elastomers, a third class of these materials, contain magnetizable particles dispersed in elastomeric solids. These elastomers are magnetostrictive, possessing substantial field-induced modulus increases and elongations. The fascinating behavior of these materials, together with their many potential uses in the automobile and elsewhere, has motivated considerable scientific and technological progress over the last decade. While magnetic powders have been used in industrial applications for decades, the first components using MR fluids were marketed in the mid-1990s, and the first commercial automotive applications are imminent. In this presentation, I will survey the physical properties of MR materials and sketch our understanding of their origins, paying particular attention to the central role of field-induced interparticle magnetic forces and the nature and dynamics of the resulting microstructure. I will describe some possible automotive applications based on these materials, focusing on the material properties and component performance that is required. Finally, I will identify some of the open scientific and technical issues in this growing field.

  4. Universal penetration test apparatus with fluid penetration sensor

    Science.gov (United States)

    Johnson, P.W.; Stampfer, J.F.; Bradley, O.D.

    1999-02-02

    A universal penetration test apparatus is described for measuring resistance of a material to a challenge fluid. The apparatus includes a pad saturated with the challenge fluid. The apparatus includes a compression assembly for compressing the material between the pad and a compression member. The apparatus also includes a sensor mechanism for automatically detecting when the challenge fluid penetrates the material. 23 figs.

  5. Equilibrium temperature in a clump of bacteria heated in fluid.

    Science.gov (United States)

    Davey, K R

    1990-02-01

    A theoretical model was developed and used to estimate quantitatively the "worst case", i.e., the longest, time to reach equilibrium temperature in the center of a clump of bacteria heated in fluid. For clumps with 10 to 10(6) cells heated in vapor, such as dry and moist air, and liquid fluids such as purees and juices, predictions show that temperature equilibrium will occur with sterilization temperatures up to 130 degrees C in under 0.02 s. Model development highlighted that the controlling influence on time for heating up the clump is the surface convection thermal resistance and that the internal conduction resistance of the clump mass is negligible by comparison. The time for a clump to reach equilibrium sterilization temperature was therefore decreased with relative turbulence (velocity) of the heating fluid, such as occurs in many process operations. These results confirm widely held suppositions that the heat-up time of bacteria in vapor or liquid is not significant with usual sterilization times.

  6. Conducting Films

    Directory of Open Access Journals (Sweden)

    De Guzman Nathaniel

    2015-01-01

    Full Text Available Silver nanowires (Ag were successfully synthesized by a copper chloride (CuCl2-mediated polyol method at 155oC. Scanning electron microscopy (SEM and X-Ray diffraction were employed to investigate the morphology and structure of the Ag products, respectively. Without CuCl2, mostly nanoparticles were formed. On the other hand, Ag nanowires with an average length of about 18.8 m and an average diameter of about 96.3 nm were formed after addition of 1.6 M of CuCl2. This suggests that the morphology of the Ag nanowire can be tailored by varying the amount of CuCl2. Ag nanowire suspension in ethanol was evenly coated on cellulose acetate substrates using Meyer rod coating. The electrodes were annealed at 150°C for 30 min to remove the organic materials on the surface of the nanowires. A sheet resistance of <50 ohms/sq with an optical transmittance of 80% at 550nm was obtained for an electrode with a nanowire density of 0.1 mg/cm2.

  7. Gyroelastic fluids

    Energy Technology Data Exchange (ETDEWEB)

    Kerbel, G.D.

    1981-01-20

    A study is made of a scale model in three dimensions of a guiding center plasma within the purview of gyroelastic (also known as finite gyroradius-near theta pinch) magnetohydrodynamics. The (nonlinear) system sustains a particular symmetry called isorrhopy which permits the decoupling of fluid modes from drift modes. Isorrhopic equilibria are analyzed within the framework of geometrical optics resulting in (local) dispersion relations and ray constants. A general scheme is developed to evolve an arbitrary linear perturbation of a screwpinch equilibrium as an invertible integral transform (over the complete set of generalized eigenfunctions defined naturally by the equilibrium). Details of the structure of the function space and the associated spectra are elucidated. Features of the (global) dispersion relation owing to the presence of gyroelastic stabilization are revealed. An energy principle is developed to study the stability of the tubular screwpinch.

  8. Gyroelastic fluids

    International Nuclear Information System (INIS)

    Kerbel, G.D.

    1981-01-01

    A study is made of a scale model in three dimensions of a guiding center plasma within the purview of gyroelastic (also known as finite gyroradius-near theta pinch) magnetohydrodynamics. The (nonlinear) system sustains a particular symmetry called isorrhopy which permits the decoupling of fluid modes from drift modes. Isorrhopic equilibria are analyzed within the framework of geometrical optics resulting in (local) dispersion relations and ray constants. A general scheme is developed to evolve an arbitrary linear perturbation of a screwpinch equilibrium as an invertible integral transform (over the complete set of generalized eigenfunctions defined naturally by the equilibrium). Details of the structure of the function space and the associated spectra are elucidated. Features of the (global) dispersion relation owing to the presence of gyroelastic stabilization are revealed. An energy principle is developed to study the stability of the tubular screwpinch

  9. Conductivity Probe

    Science.gov (United States)

    2008-01-01

    The Thermal and Electrical Conductivity Probe (TECP) for NASA's Phoenix Mars Lander took measurements in Martian soil and in the air. The needles on the end of the instrument were inserted into the Martian soil, allowing TECP to measure the propagation of both thermal and electrical energy. TECP also measured the humidity in the surrounding air. The needles on the probe are 15 millimeters (0.6 inch) long. The Phoenix Mission is led by the University of Arizona, Tucson, on behalf of NASA. Project management of the mission is by NASA's Jet Propulsion Laboratory, Pasadena, Calif. Spacecraft development is by Lockheed Martin Space Systems, Denver.

  10. Fluids of the lower crust and upper mantle: deep is different

    Science.gov (United States)

    Manning, C. E.

    2017-12-01

    Deep fluids are important for the evolution and properties of the lower crust and upper mantle in tectonically active settings. Uncertainty about their chemistry has led past workers to use upper crustal fluids as analogues. However, recent results show that fluids at >15 km differ fundamentally from shallow fluids and help explain high-pressure metasomatism and resistivity patterns. Deep fluids are comprised of four components: H2O, non-polar gases (chiefly CO2), salts (mostly alkali chlorides), and rock-derived solutes (dominated by aluminosilicates and related components). The first three generally define the solvent properties of the fluid, and models must account for observations that H2O activity may be quite low. The contrasting behavior of H2O-gas and H2O-salt mixtures yields immiscibility in the ternary system, which can lead to separation of two phases with fundamentally different chemical and transport properties. Thermodynamic modeling of equilibrium between rocks and H2O using simple ionic species known from shallow-crustal systems yields solutions possessing total dissolved solids and ionic strength that are too low to be consistent with experiments and resistivity surveys. Addition of CO2 further lowers bulk solubility and conductivity. Therefore, additional species must be present in H2O, and H2O-salt solutions likely explain much of the evidence for fluid action in high-P settings. At low salinity, H2O-rich fluids are powerful solvents for aluminosilicate rock components that are dissolved as previously unrecognized polymerized clusters. Experiments show that, near H2O-saturated melting, Al-Si polymers comprise >80% of solutes. The stability of these species facilitates critical critical mixing in rock-H2O systems. Addition of salt (e.g., NaCl) changes solubility patterns, but aluminosilicate contents remain high. Thermodynamic models indicate that the ionic strength of fluids with Xsalt = 0.05 to 0.4 and equilibrated with model crustal rocks have

  11. Measurement of thermal conductance

    International Nuclear Information System (INIS)

    Kuchnir, M.

    1977-01-01

    The 6-m long, 45-kG, warm-iron superconducting magnets envisioned for the Energy Doubler stage of the Fermilab accelerator require stiff supports with minimized thermal conductances in order to keep the refrigeration power reasonable. The large number of supports involved in the system required a careful study of their heat conduction from the room temperature wall to the intercepting refrigeration at 20 0 K and to the liquid helium. For this purpose the thermal conductance of this support was measured by comparing it with the thermal conductance of a copper strap of known geometry. An association of steady-state thermal analysis and experimental thermal conductivity techniques forms the basis of this method. An important advantage is the automatic simulation of the 20 0 K refrigeration intercept by the copper strap, which simplifies the apparatus considerably. This relative resistance technique, which uses electrical analogy as a guideline, is applicable with no restrictions for materials with temperature-independent thermal conductivity. For other materials the results obtained are functions of the specific temperature interval involved in the measurements. A comprehensive review of the literature on thermal conductivity indicates that this approach has not been used before. A demonstration of its self-consistency is stressed here rather than results obtained for different supports

  12. Thermophysical Properties of Fluids and Fluid Mixtures

    Energy Technology Data Exchange (ETDEWEB)

    Sengers, Jan V.; Anisimov, Mikhail A.

    2004-05-03

    The major goal of the project was to study the effect of critical fluctuations on the thermophysical properties and phase behavior of fluids and fluid mixtures. Long-range fluctuations appear because of the presence of critical phase transitions. A global theory of critical fluctuations was developed and applied to represent thermodynamic properties and transport properties of molecular fluids and fluid mixtures. In the second phase of the project, the theory was extended to deal with critical fluctuations in complex fluids such as polymer solutions and electrolyte solutions. The theoretical predictions have been confirmed by computer simulations and by light-scattering experiments. Fluctuations in fluids in nonequilibrium states have also been investigated.

  13. Electrokinetic effects and fluid permeability

    International Nuclear Information System (INIS)

    Berryman, J.G.

    2003-01-01

    Fluid permeability of porous media depends mainly on connectivity of the pore space and two physical parameters: porosity and a pertinent length-scale parameter. Electrical imaging methods typically establish connectivity and directly measure electrical conductivity, which can then often be related to porosity by Archie's law. When electrical phase measurements are made in addition to the amplitude measurements, information about the pertinent length scale can then be obtained. Since fluid permeability controls the ability to flush unwanted fluid contaminants from the subsurface, inexpensive maps of permeability could improve planning strategies for remediation efforts. Detailed knowledge of fluid permeability is also important for oil field exploitation, where knowledge of permeability distribution in three dimensions is a common requirement for petroleum reservoir simulation and analysis, as well as for estimates on the economics of recovery

  14. Automatic fluid dispenser

    Science.gov (United States)

    Sakellaris, P. C. (Inventor)

    1977-01-01

    Fluid automatically flows to individual dispensing units at predetermined times from a fluid supply and is available only for a predetermined interval of time after which an automatic control causes the fluid to drain from the individual dispensing units. Fluid deprivation continues until the beginning of a new cycle when the fluid is once again automatically made available at the individual dispensing units.

  15. Astrophysical fluid dynamics

    Science.gov (United States)

    Ogilvie, Gordon I.

    2016-06-01

    > These lecture notes and example problems are based on a course given at the University of Cambridge in Part III of the Mathematical Tripos. Fluid dynamics is involved in a very wide range of astrophysical phenomena, such as the formation and internal dynamics of stars and giant planets, the workings of jets and accretion discs around stars and black holes and the dynamics of the expanding Universe. Effects that can be important in astrophysical fluids include compressibility, self-gravitation and the dynamical influence of the magnetic field that is `frozen in' to a highly conducting plasma. The basic models introduced and applied in this course are Newtonian gas dynamics and magnetohydrodynamics (MHD) for an ideal compressible fluid. The mathematical structure of the governing equations and the associated conservation laws are explored in some detail because of their importance for both analytical and numerical methods of solution, as well as for physical interpretation. Linear and nonlinear waves, including shocks and other discontinuities, are discussed. The spherical blast wave resulting from a supernova, and involving a strong shock, is a classic problem that can be solved analytically. Steady solutions with spherical or axial symmetry reveal the physics of winds and jets from stars and discs. The linearized equations determine the oscillation modes of astrophysical bodies, as well as their stability and their response to tidal forcing.

  16. Conduct disorders.

    Science.gov (United States)

    Buitelaar, Jan K; Smeets, Kirsten C; Herpers, Pierre; Scheepers, Floor; Glennon, Jeffrey; Rommelse, Nanda N J

    2013-02-01

    Conduct disorder (CD) is a frequently occurring psychiatric disorder characterized by a persistent pattern of aggressive and non-aggressive rule breaking antisocial behaviours that lead to considerable burden for the patients themselves, their family and society. This review paper updates diagnostic and therapeutic approaches to CD in the light of the forthcoming DSM-5 definition. The diagnostic criteria for CD will remain unchanged in DSM-5, but the introduction of a specifier of CD with a callous-unemotional (CU) presentation is new. Linked to this, we discuss the pros and cons of various other ways to subtype aggression/CD symptoms. Existing guidelines for CD are, with few exceptions, already of a relatively older date and emphasize that clinical assessment should be systematic and comprehensive and based on a multi-informant approach. Non-medical psychosocial interventions are recommended as the first option for the treatment of CD. There is a role for medication in the treatment of comorbid syndromes and/or in case of insufficient response to psychosocial interventions and severe and dangerous aggressive and violent behaviours.

  17. Improvement in the mechanical properties, proton conductivity, and methanol resistance of highly branched sulfonated poly(arylene ether)/graphene oxide grafted with flexible alkylsulfonated side chains nanocomposite membranes

    Science.gov (United States)

    Liu, Dong; Peng, Jinhua; Li, Zhuoyao; Liu, Bin; Wang, Lei

    2018-02-01

    Sulfonated polymer/graphene oxide (GO) nanocomposites exhibit excellent properties as proton exchange membranes. However, few investigations on highly branched sulfonated poly(arylene ether)s (HBSPE)/GO nanocomposites as proton exchange membranes are reported. In order to obtain HBSPE-based nanocomposite membranes with better dispersibility and properties, a novel GO containing flexible alkylsulfonated side chains (SGO) is designed and prepared for the first time in this work. The HBSPE/SGO nanocomposite membranes with excellent dispersibility are successfully prepared. The properties of these membranes, including the mechanical properties, ion-exchange capacity, water uptake, proton conductivity, and methanol resistance, are characterized. The nanocomposite membranes exhibit higher tensile strength (32.67 MPa), higher proton conductivity (0.39 S cm-1 at 80 °C) and lower methanol permeability (4.89 × 10-7 cm2 s-1) than the pristine membrane. The nanocomposite membranes also achieve a higher maximum power density (82.36 mW cm-2) than the pristine membrane (67.85 mW cm-2) in single-cell direct methanol fuel cell (DMFC) tests, demonstrating their considerable potential for applications in DMFCs.

  18. Label-free viscosity measurement of complex fluids using reversal flow switching manipulation in a microfluidic channel.

    Science.gov (United States)

    Jun Kang, Yang; Ryu, Jeongeun; Lee, Sang-Joon

    2013-01-01

    The accurate viscosity measurement of complex fluids is essential for characterizing fluidic behaviors in blood vessels and in microfluidic channels of lab-on-a-chip devices. A microfluidic platform that accurately identifies biophysical properties of blood can be used as a promising tool for the early detections of cardiovascular and microcirculation diseases. In this study, a flow-switching phenomenon depending on hydrodynamic balancing in a microfluidic channel was adopted to conduct viscosity measurement of complex fluids with label-free operation. A microfluidic device for demonstrating this proposed method was designed to have two inlets for supplying the test and reference fluids, two side channels in parallel, and a junction channel connected to the midpoint of the two side channels. According to this proposed method, viscosities of various fluids with different phases (aqueous, oil, and blood) in relation to that of reference fluid were accurately determined by measuring the switching flow-rate ratio between the test and reference fluids, when a reverse flow of the test or reference fluid occurs in the junction channel. An analytical viscosity formula was derived to measure the viscosity of a test fluid in relation to that of the corresponding reference fluid using a discrete circuit model for the microfluidic device. The experimental analysis for evaluating the effects of various parameters on the performance of the proposed method revealed that the fluidic resistance ratio ( R J L / R L , fluidic resistance in the junction channel ( R J L ) to fluidic resistance in the side channel ( R L )) strongly affects the measurement accuracy. The microfluidic device with smaller R J L / R L values is helpful to measure accurately the viscosity of the test fluid. The proposed method accurately measured the viscosities of various fluids, including single-phase (Glycerin and plasma) and oil-water phase (oil vs. deionized water) fluids, compared with conventional

  19. Formation factor determinations by in-situ resistivity logging

    International Nuclear Information System (INIS)

    Loefgren, M.; Ohlsson, Y.; Neretnieks, I.

    2001-01-01

    Matrix diffusion in bedrock is traditionally studied by laboratory liquid diffusion experiments, which are time consuming and expensive. A new way of studying matrix diffusion is to measure the electrical resistivity of the rock. This could be done either in laboratories or in-situ. A fast method of obtaining a formation factor log, later used in matrix diffusion calculations, for an entire borehole is proposed. It is a standard procedure in geophysical well logging to measure rock resistivity and there are well-developed tools for this in the oil industry. The SKB, Sweden, uses boreholes with a small diameter (56 mm) and this reduces the options in choosing resistivity tools. Therefore they have so far relied on the Normal log that only gives quantitative measurements in special cases, after corrections are made. Modern tools, such as the slimhole Dual-Laterolog, are accurate with a high vertical resolution. The pore fluid resistivity is required when obtaining a formation factor log. In previous work the borehole fluid resistivity has been used. A new method measures the resistivity in groundwater from local fractures. These values seem more appropriate to use as new in-situ measurements show that there may be local groundwater resistivity differences. A preliminary study shows that the conductivity could be obtained in saline Swedish groundwater by measuring the chloride concentration only. Anomalies in the formation factor log have to be sorted out by using supporting core logging and non-electrical in-situ methods. Copyright (2001) Material Research Society

  20. Fluid Mechanics and Fluid Power (FMFP)

    Indian Academy of Sciences (India)

    Amitabh Bhattacharya

    decades, mainly due to the rapid improvement in computational efficiency, cameras, optics and instrumentation, both computational and experimental techniques have improved significantly, allowing researchers in Fluid Mechanics to build better mechanistic and analytical models for processes involving dynamics of fluids.

  1. Investigating the recording and accuracy of fluid balance monitoring ...

    African Journals Online (AJOL)

    ICU) showed that seven out of ten fluid balance calculations were incorrect. Objective. To identify and describe current clinical nursing practice in fluid balance monitoring and measurement accuracy in ICUs, conducted as part of a broader study ...

  2. Insulin Resistance is Associated with Increased Levels of Cerebrospinal Fluid Biomarkers of Alzheimer’s Disease and Reduced Memory Function in At-Risk Healthy Middle-Aged Adults

    Science.gov (United States)

    Hoscheidt, Siobhan M.; Starks, Erika J.; Oh, Jennifer M.; Zetterberg, Henrik; Blennow, Kaj; Krause, Rachel A.; Gleason, Carey E.; Puglielli, Luigi; Atwood, Craig S.; Carlsson, Cynthia M.; Asthana, Sanjay; Johnson, Sterling C.; Bendlin, Barbara B.

    2016-01-01

    Background Type 2 diabetes is associated with an increased risk for Alzheimer disease (AD). Regulation of normal insulin function may be important in reducing the prevalence of dementia due to AD, particularly in individuals who harbor genetic risk for or have a parental family history of AD. The relationship between insulin resistance (IR) and AD pathology remains poorly understood, particularly in midlife prior to the onset of clinical metabolic disease or cognitive decline. Objective We examined associations between IR as indexed by HOMA-IR, cerebral spinal fluid (CSF) biomarkers of AD pathology and memory in middle-aged adults enriched for AD. We postulated that higher HOMA-IR and APOE ε4 carriage would be associated with greater CSF AD pathology and poor memory performance. Methods Cognitively asymptomatic middle-aged adults (N=70, mean age=57.7 years) from the Wisconsin Alzheimer’s Disease Research Center with a parental family history of dementia due to AD underwent lumbar puncture, blood draw and neuropsychological testing. CSF AD biomarkers including soluble amyloid precursor protein β (sAPP-β), β–amyloid42 (Aβ42) and phosphorylated tau (P-tau181) were examined with respect to HOMA-IR and APOE ε4 status. Delayed memory performance was examined with respect to HOMA-IR, CSF AD biomarkers and APOE ε4 status. Results Higher HOMA-IR was associated with higher sAPP-β and Aβ42. APOE ε4 carriers had significantly higher levels of sAPP-α, sAPP-β and P-tau181/Aβ42 compared to noncarriers. The concurrent presence of higher HOMA-IR and CSF AD pathology predicted worse delayed memory performance. Conclusion Overall, the findings suggest that IR and APOE ε4 are contributing factors to the development of AD pathology in midlife, and provide support for targeting insulin function as a potentially modifiable risk factor for AD. PMID:27079723

  3. Fluid Mechanics and Fluid Power (FMFP)

    Indian Academy of Sciences (India)

    Amitabh Bhattacharya

    of renewable energy (e.g., via wind, hydrokinetic generators), creating low-cost healthcare (e.g., via point-of-care medical testing) and improvement of energy efficiency of fluid power systems, depends on improving our understanding of Fluid. Mechanics. Fluids are ubiquitous in both nature and technological applications, ...

  4. Thermal conductivity of granular porous media: A pore scale modeling approach

    Directory of Open Access Journals (Sweden)

    R. Askari

    2015-09-01

    Full Text Available Pore scale modeling method has been widely used in the petrophysical studies to estimate macroscopic properties (e.g. porosity, permeability, and electrical resistivity of porous media with respect to their micro structures. Although there is a sumptuous literature about the application of the method to study flow in porous media, there are fewer studies regarding its application to thermal conduction characterization, and the estimation of effective thermal conductivity, which is a salient parameter in many engineering surveys (e.g. geothermal resources and heavy oil recovery. By considering thermal contact resistance, we demonstrate the robustness of the method for predicting the effective thermal conductivity. According to our results obtained from Utah oil sand samples simulations, the simulation of thermal contact resistance is pivotal to grant reliable estimates of effective thermal conductivity. Our estimated effective thermal conductivities exhibit a better compatibility with the experimental data in companion with some famous experimental and analytical equations for the calculation of the effective thermal conductivity. In addition, we reconstruct a porous medium for an Alberta oil sand sample. By increasing roughness, we observe the effect of thermal contact resistance in the decrease of the effective thermal conductivity. However, the roughness effect becomes more noticeable when there is a higher thermal conductivity of solid to fluid ratio. Moreover, by considering the thermal resistance in porous media with different grains sizes, we find that the effective thermal conductivity augments with increased grain size. Our observation is in a reasonable accordance with experimental results. This demonstrates the usefulness of our modeling approach for further computational studies of heat transfer in porous media.

  5. Data processing for the fluid flow tomography method; Ryutai ryudo den`iho no data kaiseki

    Energy Technology Data Exchange (ETDEWEB)

    Ushijima, K.; Mizunaga, H.; Tanaka, T. [Kyushu University, Fukuoka (Japan). Faculty of Engineering; Hashimoto, K. [Kyushu Electric Power Co. Inc., Fukuoka (Japan)

    1997-05-27

    An automatic measurement system by means of conductive potential and self-potential methods (fluid flow tomography method) has been developed to measure the change of geothermal steam fluid during production and injection. For the fluid flow tomography method, the four-electrode configuration of the conductive potential method is adopted using the casing pipe of well as a current source. A lot of potential receiving electrodes are connected to the earth, preliminarily. The surface potential profile is measured, which is formed during the injection and production of the fluid through the well. Artificial and spontaneous potential profiles were continuously measured using this system during the hydraulic crushing tests at the test field of hot dry rock power generation at Ogachi-machi, Akita Prefecture. As a result of inversion analysis of self-potential data using a four-layer structural model of specific resistance, it was observed that the fluid injected at the depth of 711 m in the borehole permeated into the depth between 700 and 770 m in the south-eastern part of the well, and that the fractures propagated into the deeper part, gradually with the progress of hydraulic crushing test. 3 figs.

  6. Electrical resistivities of rocks from Chalk River

    International Nuclear Information System (INIS)

    Katsube, T.J.; Hume, J.P.

    1989-01-01

    Bulk rock resistivity and bulk surface resistivity measurements have been obtained for 40 gneissic rock samples from Chalk River, Ontario. Though bulk rock resistivity is a function of pore structure, pore-fluid resistivity and pore-surface resistivity, the amount of data documented for pore-surface resistivity is small compared to that for pore structure and pore-fluid resistivity. This study indicates that pore-surface resistivity has a significant effect on bulk rock resistivity. It is important that this fact be considered when interpreting resistivity data obtained by geophysical methods. In addition, a group of mafic gneiss samples had pore-surface resistivity values that were much lower than those reported for clays, glass beads or petroleum reservoir rocks. This is thought to be due to metallic minerals lining the pore walls. Other rock samples collected from the same area showed pore-surface resistivity value similar to those reported in the literature

  7. Electrical and Thermal Conductivity

    Science.gov (United States)

    Ventura, Guglielmo; Perfetti, Mauro

    After a Sect. 1.1 devoted to electrical conductivity and a section that deals with magnetic and dielectric losses ( 1.2 ), this chapter explores the theory of thermal conduction in solids. The examined categories of solids are: metals Sect. 1.3.2 , Dielectrics Sects. 1.3.3 and 1.3.4 and Nanocomposites Sect. 1.3.5 . In Sect. 1.3.6 the problem of thermal and electrical contact between materials is considered because contact resistance occurring at conductor joints in magnets or other high power applications can lead to undesirable electrical losses. At low temperature, thermal contact is also critical in the mounting of temperature sensors, where bad contacts can lead to erroneous results, in particular when superconductivity phenomena are involved.

  8. FORMATE-BASED FLUIDS: FORMULATION AND APPLICATION

    Directory of Open Access Journals (Sweden)

    Nediljka Gaurina-Međimurec

    2008-12-01

    Full Text Available Formate-based fluids has been successfully used in over hunders HPHT well operations since they introduced in field practice. They have many advantages when compared with conventional HPHT drilling and completion fluids such as: minimal formation damage, maintenance of additve properties at high temperatures, reduced hydraulic flow resistance, low potential for differential sticking, naturally lubricating, very low corrosion rates, biodegradable and pose little risk to the environment etc. Formate-based fluids can be applied during deep slim hole drilling, shale drilling, reservoir drilling, salt and gas hydrate formations drilling. The laboratory research was carried out to evaluate the rheological behavior of formate-based fluids as a function of temperature. Formate-based fluids were formulated using potassium formate brine, xanthan polymer, PAC, starch and calcium carbonate. Experimental results show that potassium formate improves the thermal stability of polymers.

  9. Analysis of giant electrorheological fluids.

    Science.gov (United States)

    Seo, Youngwook P; Seo, Yongsok

    2013-07-15

    The yield stress dependence on electric field strength for giant electrorheological (GER) fluids over the full range of electric fields was examined using Seo's scaling function which incorporated both the polarization and the conductivity models. If a proper scaling was applied to the yield stress data to collapse them onto a single curve, the Seo's scaling function could correctly fit the yield stress behavior of GER suspensions, even at very high electric field strengths. The model predictions were also compared with recently proposed Choi et al.'s model to allow a consideration of the universal framework of ER fluids. Copyright © 2013 Elsevier Inc. All rights reserved.

  10. Process fluid cooling system

    International Nuclear Information System (INIS)

    Farquhar, N.G.; Schwab, J.A.

    1977-01-01

    A system of heat exchangers is disclosed for cooling process fluids. The system is particularly applicable to cooling steam generator blowdown fluid in a nuclear plant prior to chemical purification of the fluid in which it minimizes the potential of boiling of the plant cooling water which cools the blowdown fluid

  11. Fluid mechanics in fluids at rest.

    Science.gov (United States)

    Brenner, Howard

    2012-07-01

    Using readily available experimental thermophoretic particle-velocity data it is shown, contrary to current teachings, that for the case of compressible flows independent dye- and particle-tracer velocity measurements of the local fluid velocity at a point in a flowing fluid do not generally result in the same fluid velocity measure. Rather, tracer-velocity equality holds only for incompressible flows. For compressible fluids, each type of tracer is shown to monitor a fundamentally different fluid velocity, with (i) a dye (or any other such molecular-tagging scheme) measuring the fluid's mass velocity v appearing in the continuity equation and (ii) a small, physicochemically and thermally inert, macroscopic (i.e., non-Brownian), solid particle measuring the fluid's volume velocity v(v). The term "compressibility" as used here includes not only pressure effects on density, but also temperature effects thereon. (For example, owing to a liquid's generally nonzero isobaric coefficient of thermal expansion, nonisothermal liquid flows are to be regarded as compressible despite the general perception of liquids as being incompressible.) Recognition of the fact that two independent fluid velocities, mass- and volume-based, are formally required to model continuum fluid behavior impacts on the foundations of contemporary (monovelocity) fluid mechanics. Included therein are the Navier-Stokes-Fourier equations, which are now seen to apply only to incompressible fluids (a fact well-known, empirically, to experimental gas kineticists). The findings of a difference in tracer velocities heralds the introduction into fluid mechanics of a general bipartite theory of fluid mechanics, bivelocity hydrodynamics [Brenner, Int. J. Eng. Sci. 54, 67 (2012)], differing from conventional hydrodynamics in situations entailing compressible flows and reducing to conventional hydrodynamics when the flow is incompressible, while being applicable to both liquids and gases.

  12. Videotapes and Movies on Fluid Dynamics and Fluid Machines

    OpenAIRE

    Carr, Bobbie; Young, Virginia E.

    1996-01-01

    Chapter 17 of Handbook of Fluid Dynamics and Fluid Machinery: Experimental and Computational Fluid Dynamics, Volume 11. A list of videorecordings and 16mm motion pictures about Fluid Dynamics and Fluid Machines.

  13. Combustion, Complex Fluids, and Fluid Physics Experiments on the ISS

    Science.gov (United States)

    Motil, Brian; Urban, David

    2012-01-01

    From the very first days of human spaceflight, NASA has been conducting experiments in space to understand the effect of weightlessness on physical and chemically reacting systems. NASA Glenn Research Center (GRC) in Cleveland, Ohio has been at the forefront of this research looking at both fundamental studies in microgravity as well as experiments targeted at reducing the risks to long duration human missions to the moon, Mars, and beyond. In the current International Space Station (ISS) era, we now have an orbiting laboratory that provides the highly desired condition of long-duration microgravity. This allows continuous and interactive research similar to Earth-based laboratories. Because of these capabilities, the ISS is an indispensible laboratory for low gravity research. NASA GRC has been actively involved in developing and operating facilities and experiments on the ISS since the beginning of a permanent human presence on November 2, 2000. As the lead Center both Combustion, Fluid Physics, and Acceleration Measurement GRC has led the successful implementation of an Acceleration Measurement systems, the Combustion Integrated Rack (CIR), the Fluids Integrated Rack (FIR) as well as the continued use of other facilities on the ISS. These facilities have supported combustion experiments in fundamental droplet combustion fire detection fire extinguishment soot phenomena flame liftoff and stability and material flammability. The fluids experiments have studied capillary flow magneto-rheological fluids colloidal systems extensional rheology pool and nucleate boiling phenomena. In this paper, we provide an overview of the experiments conducted on the ISS over the past 12 years. We also provide a look to the future development. Experiments presented in combustion include areas such as droplet combustion, gaseous diffusion flames, solid fuels, premixed flame studies, fire safety, and super critical oxidation processes. In fluid physics, experiments are discussed in

  14. Fluid flow through anisotropic porous medium

    International Nuclear Information System (INIS)

    Telles, A.S.; Massarani, G.

    1975-01-01

    Darcy's equation represents a simplified form of the equation of motion for the fluid flowing through a porous medium. The simplifications concern the elimination of the acceleration, the divergence of the extra stress terms, and the assumption of existence of a linear form in the velocity for the resistive force the fluid exerts upon the solid. This hypothesis may not be valid for all anisotropic media. In some instances, measurements of directional resistivity suggest existence of the resistivity tensor, leaving entirely open the question of symmetry. In connection with this important question, an experimental scheme for the determination of the antisymmetric part of this tensor is suggested. The conclusion is that material symmetries is the only macroscopic concept that imposes restrictions on the form of the resistivity and extra stress tensors [pt

  15. Fundamental Processes of Atomization in Fluid-Fluid Flows

    Science.gov (United States)

    McCready, M. J.; Chang, H.-C.; Leighton, D. T.

    2001-01-01

    This report outlines the major results of the grant "Fundamental Processes of Atomization in Fluid-Fluid Flows." These include: 1) the demonstration that atomization in liquid/liquid shear flow is driven by a viscous shear instability that triggers the formation of a long thin sheet; 2) discovery of a new mode of interfacial instability for oscillatory two-layer systems whereby a mode that originates within the less viscous liquid phase causes interfacial deformation as the oscillation proceeds; 3) the demonstration that rivulet formation from gravity front occurs because the local front shape specified by gravity and surface tension changes from a nose to a wedge geometry, thus triggering a large increase in viscous resistance; and 4) extension of the studies on nonlinear wave evolution on falling films and in stratified flow, particularly the evolution towards large-amplitude solitary waves that tend to generate drops.

  16. Crustal metamorphic fluid flux beneath the Dead Sea Basin: constraints from 2-D and 3-D magnetotelluric modelling

    Science.gov (United States)

    Meqbel, Naser; Weckmann, Ute; Muñoz, Gerard; Ritter, Oliver

    2016-12-01

    We report on a study to explore the deep electrical conductivity structure of the Dead Sea Basin (DSB) using magnetotelluric (MT) data collected along a transect across the DSB where the left lateral strike-slip Dead Sea transform (DST) fault splits into two fault strands forming one of the largest pull-apart basins of the world. A very pronounced feature of our 2-D inversion model is a deep, subvertical conductive zone beneath the DSB. The conductor extends through the entire crust and is sandwiched between highly resistive structures associated with Precambrian rocks of the basin flanks. The high electrical conductivity could be attributed to fluids released by dehydration of the uppermost mantle beneath the DSB, possibly in combination with fluids released by mid- to low-grade metamorphism in the lower crust and generation of hydrous minerals in the middle crust through retrograde metamorphism. Similar high conductivity zones associated with fluids have been reported from other large fault systems. The presence of fluids and hydrous minerals in the middle and lower crust could explain the required low friction coefficient of the DST along the eastern boundary of the DSB and the high subsidence rate of basin sediments. 3-D inversion models confirm the existence of a subvertical high conductivity structure underneath the DSB but its expression is far less pronounced. Instead, the 3-D inversion model suggests a deepening of the conductive DSB sediments off-profile towards the south, reaching a maximum depth of approximately 12 km, which is consistent with other geophysical observations. At shallower levels, the 3-D inversion model reveals salt diapirism as an upwelling of highly resistive structures, localized underneath the Al-Lisan Peninsula. The 3-D model furthermore contains an E-W elongated conductive structure to the northeast of the DSB. More MT data with better spatial coverage are required, however, to fully constrain the robustness of the above

  17. FOREWORD Fluid Mechanics and Fluid Power (FMFP)

    Indian Academy of Sciences (India)

    This section of the Special Issue carries selected articles from the Fluid Mechanics and Fluid. Power Conference held during 12–14 December 2013 at the National Institute of Technology,. Hamirpur (HP). The section includes three review articles and nine original research articles. These were selected on the basis of their ...

  18. Analytical solutions for heat conduction

    International Nuclear Information System (INIS)

    Fraley, S.K.

    1976-01-01

    Green's functions are found for steady state heat conduction in a composite rectangular parallelepiped (RPP) and in a composite right circular cylinder (RCC) assuming no contact resistance. These Green's functions may then be used to provide analytical solutions for arbitrary internal source distributions and surface temperature distributions within the RPP or RCC

  19. Microbial Metabolism in Serpentinite Fluids

    Science.gov (United States)

    Crespo-Medina, M.; Brazelton, W. J.; Twing, K. I.; Kubo, M.; Hoehler, T. M.; Schrenk, M. O.

    2013-12-01

    Serpentinization is the process in which ultramafic rocks, characteristic of the upper mantle, react with water liberating mantle carbon and reducing power to potenially support chemosynthetic microbial communities. These communities may be important mediators of carbon and energy exchange between the deep Earth and the surface biosphere. Our work focuses on the Coast Range Ophiolite Microbial Observatory (CROMO) in Northern California where subsurface fluids are accessible through a series of wells. Preliminary analyses indicate that the highly basic fluids (pH 9-12) have low microbial diversity, but there is limited knowledge about the metabolic capabilities of these communties. Metagenomic data from similar serpentine environments [1] have identified Betaproteobacteria belonging to the order Burkholderiales and Gram-positive bacteria from the order Clostridiales as key components of the serpentine microbiome. In an effort to better characterize the microbial community, metabolism, and geochemistry at CROMO, fluids from two representative wells (N08B and CSWold) were sampled during recent field campaigns. Geochemical characterization of the fluids includes measurements of dissolved gases (H2, CO, CH4), dissolved inorganic and organic carbon, volatile fatty acids, and nutrients. The wells selected can be differentiated in that N08B had higher pH (10-11), lower dissolved oxygen, and cell counts ranging from 105-106 cells mL-1 of fluid, with an abundance of the betaproteobacterium Hydrogenophaga. In contrast, fluids from CSWold have slightly lower pH (9-9.5), DO, and conductivity, as well as higher TDN and TDP. CSWold fluid is also characterized for having lower cell counts (~103 cells mL-1) and an abundance of Dethiobacter, a taxon within the phylum Clostridiales. Microcosm experiments were conducted with the purpose of monitoring carbon fixation, methanotrophy and metabolism of small organic compounds, such as acetate and formate, while tracing changes in fluid

  20. Fluid mechanics. 5. enlarged ed.

    International Nuclear Information System (INIS)

    Kalide, W.

    1980-01-01

    Originally written for students in the field of engineering, this book may also be of use in the engineering practice. The subject is presented with a view to practice. Fundamental theorems of fluid mechanics are presented without going too much into theory. The chapter on supersonic flow has been extended in the fifth edition as this is a field of great importance in engineering. The new chapter on gas dynamics takes account of these processes in turbine and compressure construction and aeronautical engineering. There is an appendix with material data, characteristic values, flow resistance coefficients, diagrams and two tables with rated pressure loss values for pipeline flow. (orig./GL)

  1. Fluid Behavior and Fluid-Solid Interactions in Nanoporous Media

    Science.gov (United States)

    Xu, H.

    2015-12-01

    Although shale oil/gas production in the US has increased exponentially, the low energy recovery is a daunting problem needed to be solved for its sustainability and continued growth, especially in light of the recent oil/gas price decline. This is apparently related to the small porosity (a few to a few hundred nm) and low permeability (10-16-10-20 m2) of tight shale formations. The fundamental question lies in the anomalous behavior of fluids in nanopores due to confinement effects, which, however, remains poorly understood. In this study, we combined experimental characterization and observations, particularly using small-angle neutron scattering (SANS), with pore-scale modeling using lattice Boltzmann method (LBM), to examine the fluid behavior and fluid-solid interactions in nanopores at reservoir conditions. Experimentally, we characterized the compositions and microstructures of a shale sample from Wolfcamp, Texas, using a variety of analytical techniques. Our analyses reveal that the shale sample is made of organic-matter (OM)-lean and OM-rich layers that exhibit different chemical and mineral compositions, and microstructural characteristics. Using the hydrostatic pressure system and gas-mixing setup we developed, in-situ SANS measurements were conducted at pressures up to 20 kpsi on shale samples imbibed with water or water-methane solutions. The obtained results indicate that capillary effect plays a significant role in fluid-nanopore interactions and the associated changes in nanopore structures vary with pore size and pressure. Computationally, we performed LBM modeling to simulate the flow behavior of methane in kerogen nanoporous structure. The correction factor, which is the ratio of apparent permeability to intrinsic permeability, was calculated. Our results show that the correction factor is always greater than one (non-continuum/non-Darcy effects) and increases with decreasing nanopore size, intrinsic permeability and pressure. Hence, the

  2. Electric fluid pump

    Science.gov (United States)

    Van Dam, Jeremy Daniel; Turnquist, Norman Arnold; Raminosoa, Tsarafidy; Shah, Manoj Ramprasad; Shen, Xiaochun

    2015-09-29

    An electric machine is presented. The electric machine includes a hollow rotor; and a stator disposed within the hollow rotor, the stator defining a flow channel. The hollow rotor includes a first end portion defining a fluid inlet, a second end portion defining a fluid outlet; the fluid inlet, the fluid outlet, and the flow channel of the stator being configured to allow passage of a fluid from the fluid inlet to the fluid outlet via the flow channel; and wherein the hollow rotor is characterized by a largest cross-sectional area of hollow rotor, and wherein the flow channel is characterized by a smallest cross-sectional area of the flow channel, wherein the smallest cross-sectional area of the flow channel is at least about 25% of the largest cross-sectional area of the hollow rotor. An electric fluid pump and a power generation system are also presented.

  3. Hydraulic Brake Fluid,

    Science.gov (United States)

    A hydraulic brake fluid consisting of diethylene glycol , monoethyl ether of diethylene glycol , and castor oil has been improved as described in the patent by adding the fluid tributyl ether of orthophosphoric acid.

  4. Lectures on fluid mechanics

    CERN Document Server

    Shinbrot, Marvin

    2012-01-01

    Readable and user-friendly, this high-level introduction explores the derivation of the equations of fluid motion from statistical mechanics, classical theory, and a portion of the modern mathematical theory of viscous, incompressible fluids. 1973 edition.

  5. Pleural fluid Gram stain

    Science.gov (United States)

    Gram stain of pleural fluid ... mixing it with a violet stain (called a Gram stain). A laboratory specialist uses a microscope to ... reveals an abnormal collection of pleural fluid. The Gram stain can help identify the bacteria that might ...

  6. Effects of fluid dynamics on cleaning efficacy of supercritical fluids

    Energy Technology Data Exchange (ETDEWEB)

    Phelps, M.R.; Willcox, W.A.; Silva, L.J.; Butner, R.S.

    1993-03-01

    Pacific Northwest Laboratory (PNL) and Boeing Aerospace Company are developing a process to clean metal parts using a supercritical solvent. This work is part of an effort to address issues inhibiting the rapid commercialization of Supercritical Fluid Parts Cleaning (SFPC). PNL assembled a SFPC test stand to observe the relationship between the fluid dynamics of the system and the mass transfer of a contaminant from the surface of a contaminated metal coupon into the bulk fluid. The bench-scale test stand consists of a Berty'' autoclave modified for these tests and supporting hardware to achieve supercritical fluids parts cleaning. Three separate sets of tests were conducted using supercritical carbon dioxide. For the first two tests, a single stainless steel coupon was cleaned with organic solvents to remove surface residue, doped with a single contaminant, and then cleaned in the SFPC test stand. Contaminants studied were Dow Corning 200 fluid (dimethylpolysiloxane) and Castle/Sybron X-448 High-temperature Oil (a polybutane/mineral oil mixture). A set of 5-minute cleaning runs was conducted for each dopant at various autoclave impeller speeds. Test results from the first two sets of experiments indicate that precision cleaning for difficult-to-remove contaminants can be dramatically improved by introducing and increasing turbulence within the system. Metal coupons that had been previously doped with aircraft oil were used in a third set of tests. The coupons were placed in the SFPC test stand and subjected to different temperatures, pressures, and run times at a constant impeller speed. The cleanliness of each part was measured by Optically Stimulated Electron Emission. The third set of tests show that levels of cleanliness attained with supercritical carbon dioxide compare favorably with solvent and aqueous cleaning levels.

  7. Effects of fluid dynamics on cleaning efficacy of supercritical fluids

    Energy Technology Data Exchange (ETDEWEB)

    Phelps, M.R.; Willcox, W.A.; Silva, L.J.; Butner, R.S.

    1993-03-01

    Pacific Northwest Laboratory (PNL) and Boeing Aerospace Company are developing a process to clean metal parts using a supercritical solvent. This work is part of an effort to address issues inhibiting the rapid commercialization of Supercritical Fluid Parts Cleaning (SFPC). PNL assembled a SFPC test stand to observe the relationship between the fluid dynamics of the system and the mass transfer of a contaminant from the surface of a contaminated metal coupon into the bulk fluid. The bench-scale test stand consists of a ``Berty`` autoclave modified for these tests and supporting hardware to achieve supercritical fluids parts cleaning. Three separate sets of tests were conducted using supercritical carbon dioxide. For the first two tests, a single stainless steel coupon was cleaned with organic solvents to remove surface residue, doped with a single contaminant, and then cleaned in the SFPC test stand. Contaminants studied were Dow Corning 200 fluid (dimethylpolysiloxane) and Castle/Sybron X-448 High-temperature Oil (a polybutane/mineral oil mixture). A set of 5-minute cleaning runs was conducted for each dopant at various autoclave impeller speeds. Test results from the first two sets of experiments indicate that precision cleaning for difficult-to-remove contaminants can be dramatically improved by introducing and increasing turbulence within the system. Metal coupons that had been previously doped with aircraft oil were used in a third set of tests. The coupons were placed in the SFPC test stand and subjected to different temperatures, pressures, and run times at a constant impeller speed. The cleanliness of each part was measured by Optically Stimulated Electron Emission. The third set of tests show that levels of cleanliness attained with supercritical carbon dioxide compare favorably with solvent and aqueous cleaning levels.

  8. The No-Slip Boundary Condition in Fluid Mechanics

    Indian Academy of Sciences (India)

    POiseuille flow, flow resistance. Before considering the case of fluids, i.e. gases and liquids,. ______ . ..... the cylinders. But it is very likely that he would have then guessed correctly that the drag would increase with the length. This historical note is added to emphasize how difficult it was to understand the motion of a fluid in ...

  9. Effects of pore fluids in the subsurface on ultrasonic wave propagation

    Energy Technology Data Exchange (ETDEWEB)

    Seifert, Patricia Katharina [Univ. of California, Berkeley, CA (United States)

    1998-05-01

    This thesis investigates ultrasonic wave propagation in unconsolidated sands in the presence of different pore fluids. Laboratory experiments have been conducted in the sub-MHz range using quartz sand fully saturated with one or two liquids. Elastic wave propagation in unconsolidated granular material is computed with different numerical models: in one-dimension a scattering model based on an analytical propagator solution, in two dimensions a numerical approach using the boundary integral equation method, in three dimensions the local flow model (LFM), the combined Biot and squirt flow theory (BISQ) and the dynamic composite elastic medium theory (DYCEM). The combination of theoretical and experimental analysis yields a better understanding of how wave propagation in unconsolidated sand is affected by (a) homogeneous phase distribution; (b) inhomogeneous phase distribution, (fingering, gas inclusions); (c) pore fluids of different viscosity; (d) wettabilities of a porous medium. The first study reveals that the main ultrasonic P-wave signatures, as a function of the fraction on nonaqueous-phase liquids in initially water-saturated sand samples, can be explained by a 1-D scattering model. The next study investigates effects of pore fluid viscosity on elastic wave propagation, in laboratory experiments conducted with sand samples saturated with fluids of different viscosities. The last study concentrates on the wettability of the grains and its effect on elastic wave propagation and electrical resistivity.

  10. Fluid dynamic transient analysis

    International Nuclear Information System (INIS)

    Vilhena Reigosa, R. de

    1992-01-01

    This paper describes the methodology adopted at NUCLEN for the fluid dynamic analyses for ANGRA 2. The fluid dynamic analysis allows, through computer codes to simulate and quantify the loads resulting from fluid dynamic transients caused by postulated ruptures or operational transients, in the piping of the safety systems and of the important operational systems. (author)

  11. Amniotic fluid water dynamics

    NARCIS (Netherlands)

    Beall, M. H.; van den Wijngaard, J. P. H. M.; van Gemert, M. J. C.; Ross, M. G.

    2007-01-01

    Water arrives in the mammalian gestation from the maternal circulation across the placenta. It then circulates between the fetal water compartments, including the fetal body compartments, the placenta and the amniotic fluid. Amniotic fluid is created by the flow of fluid from the fetal lung and

  12. Fundamental Fluid Mechanics

    Indian Academy of Sciences (India)

    BOOK I REVIEW. Fundamental Fluid. Mechanics. Good Text Book Material. V H Arakeri. Fluid Mechanics for Engineers. P N Chatterjee. MacMillan India Limited. Vol. 1, pp. 367. RS.143. Vo1.2, pp.306. RS.130. Fluid Mechanics for Engineers in two vol- umes by P N Chatterjee contains standard material for a first level ...

  13. Resistive ballooning modes in an axisymmetric toroidal plasma with long mean-free path

    International Nuclear Information System (INIS)

    Connor, J.W.; Chen, L.

    1984-08-01

    Tokamak devices normally operate at such high temperatures that the resistive fluid description is inappropriate. In particular, the collision frequency may be low enough for trapped particles to exist. However, on account of the high conductivity of such plasmas, one can identify two separate scale lengths when discussing resistive ballooning modes. By describing plasma motion on one of these, the connection length, in terms of kinetic theory the dynamics of trapped particles can be incorporated. On the resistive scale length, this leads to a description in terms of modified fluid equations in which trapped particle effects appear. The resulting equations are analyzed and the presence of trapped particles is found to modify the stability properties qualitatively

  14. TIGA-CUB - manualised psychoanalytic child psychotherapy versus treatment as usual for children aged 5-11 years with treatment-resistant conduct disorders and their primary carers: study protocol for a randomised controlled feasibility trial.

    Science.gov (United States)

    Edginton, Elizabeth; Walwyn, Rebecca; Burton, Kayleigh; Cicero, Robert; Graham, Liz; Reed, Sadie; Tubeuf, Sandy; Twiddy, Maureen; Wright-Hughes, Alex; Ellis, Lynda; Evans, Dot; Hughes, Tom; Midgley, Nick; Wallis, Paul; Cottrell, David

    2017-09-15

    The National Institute for Health and Care Excellence (NICE) recommends evidence-based parenting programmes as a first-line intervention for conduct disorders (CD) in children aged 5-11 years. As these are not effective in 25-33% of cases, NICE has requested research into second-line interventions. Child and Adolescent Psychotherapists (CAPTs) address highly complex problems where first-line treatments have failed and there have been small-scale studies of Psychoanalytic Child Psychotherapy (PCP) for CD. A feasibility trial is needed to determine whether a confirmatory trial of manualised PCP (mPCP) versus Treatment as Usual (TaU) for CD is practicable or needs refinement. The aim of this paper is to publish the abridged protocol of this feasibility trial. TIGA-CUB (Trial on improving Inter-Generational Attachment for Children Undergoing Behaviour problems) is a two-arm, pragmatic, parallel-group, multicentre, individually randomised (1:1) controlled feasibility trial (target n = 60) with blinded outcome assessment (at 4 and 8 months), which aims to develop an optimum practicable protocol for a confirmatory, pragmatic, randomised controlled trial (RCT) (primary outcome: child's behaviour; secondary outcomes: parental reflective functioning and mental health, child and parent quality of life), comparing mPCP and TaU as second-line treatments for children aged 5-11 years with treatment-resistant CD and inter-generational attachment difficulties, and for their primary carers. Child-primary carer dyads will be recruited following a referral to, or re-referral within, National Health Service (NHS) Child and Adolescent Mental Health Services (CAMHS) after an unsuccessful first-line parenting intervention. PCP will be delivered by qualified CAPTs working in routine NHS clinical practice, using a trial-specific PCP manual (a brief version of established PCP clinical practice). Outcomes are: (1) feasibility of recruitment methods, (2) uptake and follow-up rates, (3

  15. Bifurcated SEN with Fluid Flow Conditioners

    Directory of Open Access Journals (Sweden)

    F. Rivera-Perez

    2014-01-01

    Full Text Available This work evaluates the performance of a novel design for a bifurcated submerged entry nozzle (SEN used for the continuous casting of steel slabs. The proposed design incorporates fluid flow conditioners attached on SEN external wall. The fluid flow conditioners impose a pseudosymmetric pattern in the upper zone of the mold by inhibiting the fluid exchange between the zones created by conditioners. The performance of the SEN with fluid flow conditioners is analyzed through numerical simulations using the CFD technique. Numerical results were validated by means of physical simulations conducted on a scaled cold water model. Numerical and physical simulations confirmed that the performance of the proposed SEN is superior to a traditional one. Fluid flow conditioners reduce the liquid free surface fluctuations and minimize the occurrence of vortexes at the free surface.

  16. Nanostructured conductive polymeric materials

    Science.gov (United States)

    Al-Saleh, Mohammed H.

    Conductive polymer composites (CPCs) are a suitable alternative to metals in many applications due to their light-weight, corrosion resistance, low cost, ease of processing and design flexibility. CPCs have been formulated using different types of conductive fillers. In this PhD thesis, the focus is on CPCs for electrostatic discharge (ESD) protection and electromagnetic interference (EMI) attenuation. Despite the versatility of conductive fillers, carbon black (CB) has been the dominant filler to make CPCs for ESD protection applications because CB/polymer composites have a cost advantage over all other CPCs. For EMI shielding, stainless steel fibres and metal coated fibers are the preferred fillers, however CPCs made of those fibers are not the dominant EMI shielding materials. Metal coated and polymer plated polymers are the most widely used EMI shielding options. The limited use of CPCs in the EMI shielding market is because the high filler loading required to formulate a composite with an adequate level of shielding remarkably increases the composite price. In order to increase the competitiveness of CPCs, percolation threshold should be minimized as much as possible and composites with high EMI shielding capabilities at low filler loading should be formulated because all conductive fillers are expensive compared to polymers. In this thesis, two different methodologies to reduce percolation threshold in CPCs have been successfully developed and a CPC with exceptional EMI shielding capability has been formulated using copper nanowires as conductive filler. The first percolation threshold reduction technique is based on the selective localization of CB at the interface of immiscible polymer blend. The technique requires adding a copolymer that prefers the blend's interface and for which CB nanoparticles has the highest affinity. The second method is based on producing a CPC powder and then using this powder as a conductive filler to produce composite by dry

  17. Fluid inclusion geothermometry

    Science.gov (United States)

    Cunningham, C.G.

    1977-01-01

    Fluid inclusions trapped within crystals either during growth or at a later time provide many clues to the histories of rocks and ores. Estimates of fluid-inclusion homogenization temperature and density can be obtained using a petrographic microscope with thin sections, and they can be refined using heating and freezing stages. Fluid inclusion studies, used in conjunction with paragenetic studies, can provide direct data on the time and space variations of parameters such as temperature, pressure, density, and composition of fluids in geologic environments. Changes in these parameters directly affect the fugacity, composition, and pH of fluids, thus directly influencing localization of ore metals. ?? 1977 Ferdinand Enke Verlag Stuttgart.

  18. Numerical analysis of fractional MHD Maxwell fluid with the effects of convection heat transfer condition and viscous dissipation

    Science.gov (United States)

    Bai, Yu; Jiang, Yuehua; Liu, Fawang; Zhang, Yan

    2017-12-01

    This paper investigates the incompressible fractional MHD Maxwell fluid due to a power function accelerating plate with the first order slip, and the numerical analysis on the flow and heat transfer of fractional Maxwell fluid has been done. Moreover the deformation motion of fluid micelle is simply analyzed. Nonlinear velocity equation are formulated with multi-term time fractional derivatives in the boundary layer governing equations, and convective heat transfer boundary condition and viscous dissipation are both taken into consideration. A newly finite difference scheme with L1-algorithm of governing equations are constructed, whose convergence is confirmed by the comparison with analytical solution. Numerical solutions for velocity and temperature show the effects of pertinent parameters on flow and heat transfer of fractional Maxwell fluid. It reveals that the fractional derivative weakens the effects of motion and heat conduction. The larger the Nusselt number is, the greater the heat transfer capacity of fluid becomes, and the temperature gradient at the wall becomes more significantly. The lower Reynolds number enhances the viscosity of the fluid because it is the ratio of the viscous force and the inertia force, which resists the flow and heat transfer.

  19. Numerical analysis of fractional MHD Maxwell fluid with the effects of convection heat transfer condition and viscous dissipation

    Directory of Open Access Journals (Sweden)

    Yu Bai

    2017-12-01

    Full Text Available This paper investigates the incompressible fractional MHD Maxwell fluid due to a power function accelerating plate with the first order slip, and the numerical analysis on the flow and heat transfer of fractional Maxwell fluid has been done. Moreover the deformation motion of fluid micelle is simply analyzed. Nonlinear velocity equation are formulated with multi-term time fractional derivatives in the boundary layer governing equations, and convective heat transfer boundary condition and viscous dissipation are both taken into consideration. A newly finite difference scheme with L1-algorithm of governing equations are constructed, whose convergence is confirmed by the comparison with analytical solution. Numerical solutions for velocity and temperature show the effects of pertinent parameters on flow and heat transfer of fractional Maxwell fluid. It reveals that the fractional derivative weakens the effects of motion and heat conduction. The larger the Nusselt number is, the greater the heat transfer capacity of fluid becomes, and the temperature gradient at the wall becomes more significantly. The lower Reynolds number enhances the viscosity of the fluid because it is the ratio of the viscous force and the inertia force, which resists the flow and heat transfer.

  20. Spinning fluids reactor

    Science.gov (United States)

    Miller, Jan D; Hupka, Jan; Aranowski, Robert

    2012-11-20

    A spinning fluids reactor, includes a reactor body (24) having a circular cross-section and a fluid contactor screen (26) within the reactor body (24). The fluid contactor screen (26) having a plurality of apertures and a circular cross-section concentric with the reactor body (24) for a length thus forming an inner volume (28) bound by the fluid contactor screen (26) and an outer volume (30) bound by the reactor body (24) and the fluid contactor screen (26). A primary inlet (20) can be operatively connected to the reactor body (24) and can be configured to produce flow-through first spinning flow of a first fluid within the inner volume (28). A secondary inlet (22) can similarly be operatively connected to the reactor body (24) and can be configured to produce a second flow of a second fluid within the outer volume (30) which is optionally spinning.

  1. Intravenous fluids: balancing solutions.

    Science.gov (United States)

    Hoorn, Ewout J

    2017-08-01

    The topic of intravenous (IV) fluids may be regarded as "reverse nephrology", because nephrologists usually treat to remove fluids rather than to infuse them. However, because nephrology is deeply rooted in fluid, electrolyte, and acid-base balance, IV fluids belong in the realm of our specialty. The field of IV fluid therapy is in motion due to the increasing use of balanced crystalloids, partly fueled by the advent of new solutions. This review aims to capture these recent developments by critically evaluating the current evidence base. It will review both indications and complications of IV fluid therapy, including the characteristics of the currently available solutions. It will also cover the use of IV fluids in specific settings such as kidney transplantation and pediatrics. Finally, this review will address the pathogenesis of saline-induced hyperchloremic acidosis, its potential effect on outcomes, and the question if this should lead to a definitive switch to balanced solutions.

  2. Microscope-Based Fluid Physics Experiments in the Fluids and Combustion Facility on ISS

    Science.gov (United States)

    Doherty, Michael P.; Motil, Susan M.; Snead, John H.; Malarik, Diane C.

    2000-01-01

    At the NASA Glenn Research Center, the Microgravity Science Program is planning to conduct a large number of experiments on the International Space Station in both the Fluid Physics and Combustion Science disciplines, and is developing flight experiment hardware for use within the International Space Station's Fluids and Combustion Facility. Four fluids physics experiments that require an optical microscope will be sequentially conducted within a subrack payload to the Fluids Integrated Rack of the Fluids and Combustion Facility called the Light Microscopy Module, which will provide the containment, changeout, and diagnostic capabilities to perform the experiments. The Light Microscopy Module is planned as a fully remotely controllable on-orbit microscope facility, allowing flexible scheduling and control of experiments within International Space Station resources. This paper will focus on the four microscope-based experiments, specifically, their objectives and the sample cell and instrument hardware to accommodate their requirements.

  3. Electrically Conductive Anodized Aluminum Surfaces

    Science.gov (United States)

    Nguyen, Trung Hung

    2006-01-01

    Anodized aluminum components can be treated to make them sufficiently electrically conductive to suppress discharges of static electricity. The treatment was conceived as a means of preventing static electric discharges on exterior satin-anodized aluminum (SAA) surfaces of spacecraft without adversely affecting the thermal-control/optical properties of the SAA and without need to apply electrically conductive paints, which eventually peel off in the harsh environment of outer space. The treatment can also be used to impart electrical conductivity to anodized housings of computers, medical electronic instruments, telephoneexchange equipment, and other terrestrial electronic equipment vulnerable to electrostatic discharge. The electrical resistivity of a typical anodized aluminum surface layer lies between 10(exp 11) and 10(exp 13) Omega-cm. To suppress electrostatic discharge, it is necessary to reduce the electrical resistivity significantly - preferably to surface becomes covered and the pores in the surface filled with a transparent, electrically conductive metal oxide nanocomposite. Filling the pores with the nanocomposite reduces the transverse electrical resistivity and, in the original intended outer-space application, the exterior covering portion of the nanocomposite would afford the requisite electrical contact with the outer-space plasma. The electrical resistivity of the nanocomposite can be tailored to a value between 10(exp 7) and 10(exp 12) Omega-cm. Unlike electrically conductive paint, the nanocomposite becomes an integral part of the anodized aluminum substrate, without need for adhesive bonding material and without risk of subsequent peeling. The electrodeposition process is compatible with commercial anodizing production lines. At present, the electronics industry uses expensive, exotic, electrostaticdischarge- suppressing finishes: examples include silver impregnated anodized, black electroless nickel, black chrome, and black copper. In

  4. Dynamic Characteristics of Magneto-Fluid Supports

    Directory of Open Access Journals (Sweden)

    V. A. Chernobai

    2008-01-01

    Full Text Available The paper considers a vibro-protective magneto-fluid support that uses elastic properties of magnetic fluid with a free surface in magnetic field.The paper has experimentally revealed that the analyzed structure is characterized by better noise absorbing characteristics.The conducted experiments have made it possible to conclude that there is a possibility to use vibro-protective magneto-fluid supports within the frequency range from 0 to 300 Hz, amplitudes up to 2 mm and unit load up to 2,5 · 10 4 Н/м².

  5. Intravenous fluids in acute decompensated heart failure.

    Science.gov (United States)

    Bikdeli, Behnood; Strait, Kelly M; Dharmarajan, Kumar; Li, Shu-Xia; Mody, Purav; Partovian, Chohreh; Coca, Steven G; Kim, Nancy; Horwitz, Leora I; Testani, Jeffrey M; Krumholz, Harlan M

    2015-02-01

    This study sought to determine the use of intravenous fluids in the early care of patients with acute decompensated heart failure (HF) who are treated with loop diuretics. Intravenous fluids are routinely provided to many hospitalized patients. We conducted a retrospective cohort study of patients admitted with HF to 346 hospitals from 2009 to 2010. We assessed the use of intravenous fluids during the first 2 days of hospitalization. We determined the frequency of adverse in-hospital outcomes. We assessed variation in the use of intravenous fluids across hospitals and patient groups. Among 131,430 hospitalizations for HF, 13,806 (11%) were in patients treated with intravenous fluids during the first 2 days. The median volume of administered fluid was 1,000 ml (interquartile range: 1,000 to 2,000 ml), and the most commonly used fluids were normal saline (80%) and half-normal saline (12%). Demographic characteristics and comorbidities were similar in hospitalizations in which patients did and did not receive fluids. Patients who were treated with intravenous fluids had higher rates of subsequent critical care admission (5.7% vs. 3.8%; p fluid treatment varied widely across hospitals (range: 0% to 71%; median: 12.5%). Many patients who are hospitalized with HF and receive diuretics also receive intravenous fluids during their early inpatient care, and the proportion varies among hospitals. Such practice is associated with worse outcomes and warrants further investigation. Copyright © 2015 American College of Cardiology Foundation. Published by Elsevier Inc. All rights reserved.

  6. Status of surface conduction in topological insulators

    International Nuclear Information System (INIS)

    Barua, Sourabh; Rajeev, K. P.

    2014-01-01

    In this report, we scrutinize the thickness dependent resistivity data from the recent literature on electrical transport measurements in topological insulators. A linear increase in resistivity with increase in thickness is expected in the case of these materials since they have an insulating bulk and a conducting surface. However, such a trend is not seen in the resistivity versus thickness data for all the cases examined, except for some samples, where it holds for a range of thickness

  7. Spatial statistics of magnetic field in two-dimensional chaotic flow in the resistive growth stage

    Energy Technology Data Exchange (ETDEWEB)

    Kolokolov, I.V., E-mail: igor.kolokolov@gmail.com [Landau Institute for Theoretical Physics RAS, 119334, Kosygina 2, Moscow (Russian Federation); NRU Higher School of Economics, 101000, Myasnitskaya 20, Moscow (Russian Federation)

    2017-03-18

    The correlation tensors of magnetic field in a two-dimensional chaotic flow of conducting fluid are studied. It is shown that there is a stage of resistive evolution where the field correlators grow exponentially with time. The two- and four-point field correlation tensors are computed explicitly in this stage in the framework of Batchelor–Kraichnan–Kazantsev model. They demonstrate strong temporal intermittency of the field fluctuations and high level of non-Gaussianity in spatial field distribution.

  8. Fluid involvement in normal faulting

    Science.gov (United States)

    Sibson, Richard H.

    2000-04-01

    Evidence of fluid interaction with normal faults comes from their varied role as flow barriers or conduits in hydrocarbon basins and as hosting structures for hydrothermal mineralisation, and from fault-rock assemblages in exhumed footwalls of steep active normal faults and metamorphic core complexes. These last suggest involvement of predominantly aqueous fluids over a broad depth range, with implications for fault shear resistance and the mechanics of normal fault reactivation. A general downwards progression in fault rock assemblages (high-level breccia-gouge (often clay-rich) → cataclasites → phyllonites → mylonite → mylonitic gneiss with the onset of greenschist phyllonites occurring near the base of the seismogenic crust) is inferred for normal fault zones developed in quartzo-feldspathic continental crust. Fluid inclusion studies in hydrothermal veining from some footwall assemblages suggest a transition from hydrostatic to suprahydrostatic fluid pressures over the depth range 3-5 km, with some evidence for near-lithostatic to hydrostatic pressure cycling towards the base of the seismogenic zone in the phyllonitic assemblages. Development of fault-fracture meshes through mixed-mode brittle failure in rock-masses with strong competence layering is promoted by low effective stress in the absence of thoroughgoing cohesionless faults that are favourably oriented for reactivation. Meshes may develop around normal faults in the near-surface under hydrostatic fluid pressures to depths determined by rock tensile strength, and at greater depths in overpressured portions of normal fault zones and at stress heterogeneities, especially dilational jogs. Overpressures localised within developing normal fault zones also determine the extent to which they may reutilise existing discontinuities (for example, low-angle thrust faults). Brittle failure mode plots demonstrate that reactivation of existing low-angle faults under vertical σ1 trajectories is only likely if

  9. Fluid breakup in carbon nanotubes: An explanation of ultrafast ion transport

    Science.gov (United States)

    Gao, Xiang; Zhao, Tianshou; Li, Zhigang

    2017-09-01

    Ultrafast ion transport in carbon nanotubes (CNTs) has been experimentally observed, but the underlying mechanism is unknown. In this work, we investigate ion transport in CNTs through molecular dynamics (MD) simulations. It is found that the flow in CNTs undergoes a transition from the passage of a continuous liquid chain to the transport of isolated ion-water clusters as the CNT length or the external electric filed strength is increased. The breakup of the liquid chain in CNTs greatly reduces the resistance caused by the hydrogen bonds of water and significantly enhances the ionic mobility, which explains the two-order-magnitude enhancement of ionic conductance in CNTs reported in the literature. A theoretical criterion for fluid breakup is proposed, which agrees well with MD results. The fluid breakup phenomenon provides new insights into enhancing ion transport in nanoconfinements.

  10. Fiber optic fluid detector

    Science.gov (United States)

    Angel, S. Michael

    1989-01-01

    Particular gases or liquids are detected with a fiber optic element (11, 11a to 11j) having a cladding or coating of a material (23, 23a to 23j) which absorbs the fluid or fluids and which exhibits a change of an optical property, such as index of refraction, light transmissiveness or fluoresence emission, for example, in response to absorption of the fluid. The fluid is sensed by directing light into the fiber optic element and detecting changes in the light, such as exit angle changes for example, that result from the changed optical property of the coating material. The fluid detector (24, 24a to 24j) may be used for such purposes as sensing toxic or explosive gases in the atmosphere, measuring ground water contamination or monitoring fluid flows in industrial processes, among other uses.

  11. Metalworking and machining fluids

    Science.gov (United States)

    Erdemir, Ali; Sykora, Frank; Dorbeck, Mark

    2010-10-12

    Improved boron-based metal working and machining fluids. Boric acid and boron-based additives that, when mixed with certain carrier fluids, such as water, cellulose and/or cellulose derivatives, polyhydric alcohol, polyalkylene glycol, polyvinyl alcohol, starch, dextrin, in solid and/or solvated forms result in improved metalworking and machining of metallic work pieces. Fluids manufactured with boric acid or boron-based additives effectively reduce friction, prevent galling and severe wear problems on cutting and forming tools.

  12. Electrically conductive polymer concrete coatings

    Science.gov (United States)

    Fontana, Jack J.; Elling, David; Reams, Walter

    1990-01-01

    A sprayable electrically conductive polymer concrete coating for vertical d overhead applications is described. The coating is permeable yet has low electrical resistivity (concrete substrates, and good weatherability. A preferred formulation contains about 60 wt % calcined coke breeze, 40 wt % vinyl ester with 3.5 wt % modified bentonite clay. Such formulations apply evenly and provide enough rigidity for vertical or overhead structures so there is no drip or sag.

  13. Fluctuation conductivity in cuprate superconductors

    Indian Academy of Sciences (India)

    Abstract. We have measured the in-plane resistivity of Bi2Sr2CaCu2O8+δ and Tl2Ba2. CaCu2O8+δ single crystals in the temperature range 70–300 K. The thermodynamic fluctuations in the conductivity of both the samples start around ∼ 125 K. We find the Lawrence and Doniach [1] model to be inadequate to describe the ...

  14. Electrorheological fluids and methods

    Science.gov (United States)

    Green, Peter F.; McIntyre, Ernest C.

    2015-06-02

    Electrorheological fluids and methods include changes in liquid-like materials that can flow like milk and subsequently form solid-like structures under applied electric fields; e.g., about 1 kV/mm. Such fluids can be used in various ways as smart suspensions, including uses in automotive, defense, and civil engineering applications. Electrorheological fluids and methods include one or more polar molecule substituted polyhedral silsesquioxanes (e.g., sulfonated polyhedral silsesquioxanes) and one or more oils (e.g., silicone oil), where the fluid can be subjected to an electric field.

  15. Plasmas and fluids

    International Nuclear Information System (INIS)

    Anon.

    1986-01-01

    Plasma and fluid physics includes the fields of fusion research and space investigation. This book discusses the most important advances in these areas over the past decade and recommends a stronger commitment to basic research in plasma and fluid physics. The book recommends that plasma and fluid physics be included in physics curriculums because of their increasing importance in energy and defense. The book also lists recent accomplishments in the fields of general plasma physics, fusion plasma confinement and heating, space and astrophysical plasmas, and fluid physics and lists research opportunities in these areas. A funding summary explains how research monies are allocated and suggests ways to improve their effectiveness

  16. The Fluids RAP

    Science.gov (United States)

    Nedyalkov, Ivaylo

    2016-11-01

    After fifteen years of experience in rap, and ten in fluid mechanics, "I am coming here with high-Reynolds-number stamina; I can beat these rap folks whose flows are... laminar." The rap relates fluid flows to rap flows. The fluid concepts presented in the song have varying complexity and the listeners/viewers will be encouraged to read the explanations on a site dedicated to the rap. The music video will provide an opportunity to share high-quality fluid visualizations with a general audience. This talk will present the rap lyrics, the vision for the video, and the strategy for outreach. Suggestions and comments will be welcomed.

  17. Fluid dynamics transactions

    CERN Document Server

    Fiszdon, W

    1965-01-01

    Fluid Dynamics Transactions, Volume 2 compiles 46 papers on fluid dynamics, a subdiscipline of fluid mechanics that deals with fluid flow. The topics discussed in this book include developments in interference theory for aeronautical applications; diffusion from sources in a turbulent boundary layer; unsteady motion of a finite wing span in a compressible medium; and wall pressure covariance and comparison with experiment. The certain classes of non-stationary axially symmetric flows in magneto-gas-dynamics; description of the phenomenon of secondary flows in curved channels by means of co

  18. Sphere based fluid systems

    Science.gov (United States)

    Elleman, Daniel D. (Inventor); Wang, Taylor G. (Inventor)

    1989-01-01

    Systems are described for using multiple closely-packed spheres. In one system for passing fluid, a multiplicity of spheres lie within a container, with all of the spheres having the same outside diameter and with the spheres being closely nested in one another to create multiple interstitial passages of a known size and configuration and smooth walls. The container has an inlet and outlet for passing fluid through the interstitial passages formed between the nested spheres. The small interstitial passages can be used to filter out material, especially biological material such as cells in a fluid, where the cells can be easily destroyed if passed across sharp edges. The outer surface of the spheres can contain a material that absorbs a constitutent in the flowing fluid, such as a particular contamination gas, or can contain a catalyst to chemically react the fluid passing therethrough, the use of multiple small spheres assuring a large area of contact of these surfaces of the spheres with the fluid. In a system for storing and releasing a fluid such as hydrogen as a fuel, the spheres can include a hollow shell containing the fluid to be stored, and located within a compressable container that can be compressed to break the shells and release the stored fluid.

  19. Theoretical Fluid Dynamics

    CERN Document Server

    Shivamoggi, Bhimsen K

    1998-01-01

    "Although there are many texts and monographs on fluid dynamics, I do not know of any which is as comprehensive as the present book. It surveys nearly the entire field of classical fluid dynamics in an advanced, compact, and clear manner, and discusses the various conceptual and analytical models of fluid flow." - Foundations of Physics on the first edition. Theoretical Fluid Dynamics functions equally well as a graduate-level text and a professional reference. Steering a middle course between the empiricism of engineering and the abstractions of pure mathematics, the author focuses

  20. Selection of fluids for tritium pumping systems

    International Nuclear Information System (INIS)

    Chastagner, P.

    1984-02-01

    The degradation characteristics of three types of vacuum pump fluids, polyphenyl ethers, perfluoropolyethers and hydrocarbon oils were reviewed. Fluid selection proved to be a critical factor in the long-term performance of tritium pumping systems and subsequent tritium recovery operations. Thermal degradation and tritium radiolysis of pump fluids produce contaminants which can damage equipment and interfere with tritium recovery operations. General characteristics of these fluids are as follows: polyphenyl ether has outstanding radiation resistance, is very stable under normal diffusion pump conditions, but breaks down in the presence of oxygen at anticipated operating temperatures. Perfluoropolyether fluids are very stable and do not react chemically with most gases. Thermal and mechanical degradation products are inert, but the radiolysis products are very corrosive. Most of the degradation products of hydrogen oils are volatile and the principal radiolysis product is methane. Our studies show that polyphenyl ethers and hydrocarbon oils are the preferred fluids for use in tritium pumping systems. No corrosive materials are formed and most of the degradation products can be removed with suitable filter systems

  1. Physical-Statistical Model of Thermal Conductivity of Nanofluids

    Directory of Open Access Journals (Sweden)

    B. Usowicz

    2014-01-01

    Full Text Available A physical-statistical model for predicting the effective thermal conductivity of nanofluids is proposed. The volumetric unit of nanofluids in the model consists of solid, liquid, and gas particles and is treated as a system made up of regular geometric figures, spheres, filling the volumetric unit by layers. The model assumes that connections between layers of the spheres and between neighbouring spheres in the layer are represented by serial and parallel connections of thermal resistors, respectively. This model is expressed in terms of thermal resistance of nanoparticles and fluids and the multinomial distribution of particles in the nanofluids. The results for predicted and measured effective thermal conductivity of several nanofluids (Al2O3/ethylene glycol-based and Al2O3/water-based; CuO/ethylene glycol-based and CuO/water-based; and TiO2/ethylene glycol-based are presented. The physical-statistical model shows a reasonably good agreement with the experimental results and gives more accurate predictions for the effective thermal conductivity of nanofluids compared to existing classical models.

  2. Complexity in fluids

    International Nuclear Information System (INIS)

    Bayly, B.

    1991-01-01

    Fluids are basically very simple things. The fluids encountered all the time - air, water, milk, coffee, etc. - are undramatic. One blob of a given fluid looks much like any other, except for such gross properties as volume or mass. Of course, blobs of fluid come in different shapes. However, it's easy to change the shape of a blob of fluid, with the result that we rarely think of the shape of a fluid blob as a defining property. In fact, a blob that starts with one shape can be deformed into almost any other shape, with arbitrarily small input of energy. When one talks about lumps of a solid, in contrast, shape is important. This is because it takes work, i.e., energy, to change the shape of a solid. Making a small deformation from some rest configuration takes a small amount of energy, and a large deformation takes a lot of energy. Sometimes, as in idealized elastic systems, the required energy goes to infinity as the deformation becomes unbounded. Real solids usually break if you deform them enough; all subsequent deformations cost no energy. Basically, a finite deformation requires finite energy. Complexity arises in fluid systems because the shape of a blob of fluid is indeterminate. Nothing prevents an initially simple fluid blob from deforming into the weirdest shape imaginable. It is the absence of any kind of blob-shape constraint that allows complexity to enter fluid science. During these lectures the author briefly describes a few areas in which complexity arises and has to be dealt with. These lectures will be roughly divided as follows: (1) physical and mathematical description of fluids and flows; (2) flow transport and ergodic theory; (3) magnetic dynamos and related problems; (4) flow instabilities; (5) turbulence

  3. Pool boiling performance of NovecTM 649 engineered fluid

    International Nuclear Information System (INIS)

    Forrest, Eric; Buongiorno, Jacopo; McKrell, Thomas; Hu, Lin-Wen

    2009-01-01

    A new fluorinated ketone, C 2 F 5 C(O)CF(CF 3 ) 2 , is currently being considered as an environmentally friendly alternative for power electronics cooling applications due to its high dielectric strength and low global warming potential (GWP). Sold commercially by the 3M Company as Novec TM 649 Engineered Fluid, C 2 F 5 C(O)CF(CF 3 ) 2 exhibits very low acute toxicity while maintaining long-term stability. To assess the general two-phase heat transfer performance of Novec TM 649, pool boiling tests were conducted by resistively heating a 0.01 in. diameter nickel wire at the fluid's atmospheric saturation temperature of 49 deg C. The nucleate boiling heat transfer coefficient and critical heat flux (CHF) obtained for the fluorinated ketone compare favorably with results obtained for FC-72, a fluorocarbon widely used for the direct cooling of electronic devices. Initial results indicate that Novec TM 649 may prove to be a viable alternative to FC-72 and other halo alkanes for the cooling of high power density electronic devices. (author)

  4. Fluid loading responsiveness

    NARCIS (Netherlands)

    Geerts, Bart

    2011-01-01

    Patients in the intensive care unit (ICU) and in the peri-operative phase are dependent on physicians and nurses for their fluid intake. Volume status optimization is required to maximize oxygen delivery to vital organs. Unnecessary fluid administration can, however, lead to general and pulmonary

  5. Fluid Statics and Archimedes

    Indian Academy of Sciences (India)

    stationary fluid only normal stress (pressure) is present and tangential stresses are absent. In this article we ... delayed the discovery of the principle by a few centuries! Archimedes formulated his laws on buoyancy ... stress in the study of mechanics of solids and fluids (see Boxl). Just as temperature and density, stress can ...

  6. Applications of fluid dynamics

    International Nuclear Information System (INIS)

    Round, G.R.; Garg, V.K.

    1986-01-01

    This book describes flexible and practical approach to learning the basics of fluid dynamics. Each chapter is a self-contained work session and includes a fluid dynamics concept, an explanation of the principles involved, an illustration of their application and references on where more detailed discussions can be found

  7. Tumor interstitial fluid

    DEFF Research Database (Denmark)

    Gromov, Pavel; Gromova, Irina; Olsen, Charlotta J.

    2013-01-01

    Tumor interstitial fluid (TIF) is a proximal fluid that, in addition to the set of blood soluble phase-borne proteins, holds a subset of aberrantly externalized components, mainly proteins, released by tumor cells and tumor microenvironment through various mechanisms, which include classical secr...

  8. Peritoneal fluid culture

    Science.gov (United States)

    Culture - peritoneal fluid ... sent to the laboratory for Gram stain and culture. The sample is checked to see if bacteria ... The peritoneal fluid culture may be negative, even if you have ... diagnosis of peritonitis is based on other factors, in addition ...

  9. Time Independent Fluids

    Science.gov (United States)

    Collyer, A. A.

    1973-01-01

    Discusses theories underlying Newtonian and non-Newtonian fluids by explaining flow curves exhibited by plastic, shear-thining, and shear-thickening fluids and Bingham plastic materials. Indicates that the exact mechanism governing shear-thickening behaviors is a problem of further study. (CC)

  10. Simulation of a pulsatile total artificial heart: Development of a partitioned Fluid Structure Interaction model

    Science.gov (United States)

    Sonntag, Simon J.; Kaufmann, Tim A. S.; Büsen, Martin R.; Laumen, Marco; Linde, Torsten; Schmitz-Rode, Thomas; Steinseifer, Ulrich

    2013-04-01

    Heart disease is one of the leading causes of death in the world. Due to a shortage in donor organs artificial hearts can be a bridge to transplantation or even serve as a destination therapy for patients with terminal heart insufficiency. A pusher plate driven pulsatile membrane pump, the Total Artificial Heart (TAH) ReinHeart, is currently under development at the Institute of Applied Medical Engineering of RWTH Aachen University.This paper presents the methodology of a fully coupled three-dimensional time-dependent Fluid Structure Interaction (FSI) simulation of the TAH using a commercial partitioned block-Gauss-Seidel coupling package. Partitioned coupling of the incompressible fluid with the slender flexible membrane as well as a high fluid/structure density ratio of about unity led inherently to a deterioration of the stability (‘artificial added mass instability’). The objective was to conduct a stable simulation with high accuracy of the pumping process. In order to achieve stability, a combined resistance and pressure outlet boundary condition as well as the interface artificial compressibility method was applied. An analysis of the contact algorithm and turbulence condition is presented. Independence tests are performed for the structural and the fluid mesh, the time step size and the number of pulse cycles. Because of the large deformation of the fluid domain, a variable mesh stiffness depending on certain mesh properties was specified for the fluid elements. Adaptive remeshing was avoided. Different approaches for the mesh stiffness function are compared with respect to convergence, preservation of mesh topology and mesh quality. The resulting mesh aspect ratios, mesh expansion factors and mesh orthogonalities are evaluated in detail. The membrane motion and flow distribution of the coupled simulations are compared with a top-view recording and stereo Particle Image Velocimetry (PIV) measurements, respectively, of the actual pump.

  11. A lattice model exhibiting radiation-induced anomalous conductivity

    OpenAIRE

    Kimball, J. C.; Lee, Keeyung

    2003-01-01

    A lattice-based model exhibits an unusual conductivity when it is subjected to both a static magnetic field and electromagnetic radiation. This conductivity anomaly may explain some aspects of the recently observed "zero-resistance states". PACS: 72.40+w, 73.40-c, 73.63 Keywords: Zero-resistance states, negative conductivity, lattice model

  12. Clinical significance of methicillin-resistant coagulase-negative staphylococci obtained from sterile specimens.

    Science.gov (United States)

    Tashiro, Masato; Izumikawa, Koichi; Ashizawa, Nobuyuki; Narukawa, Munetoshi; Yamamoto, Yoshihiro

    2015-01-01

    Distinguishing true coagulase-negative staphylococci bacteremia from contamination remains a challenge. We conducted a retrospective analysis of 183 patients with methicillin-resistant coagulase-negative staphylococci (MR-CoNS)-positive and methicillin-resistant Staphylococcus aureus-positive cultures obtained from sterile sites such as blood, synovial fluid, ascitic fluid, and cerebrospinal fluid. Of the 209 MR-CoNS isolates, 83 (39.7%) were considered infection associated, and 126 (60.3%) were considered contamination. MR-CoNS isolates cultured from synovial fluid were more likely to be infection associated (P = 0.009). The median interval from insertion of a central venous catheter to onset of infection tended to be longer in MR-CoNS infection cases than in methicillin-resistant S. aureus infection cases (41 days versus 14 days, P = 0.055). In conclusion, our results suggest that the proportion of cases of true MR-CoNS infection may be higher than previously reported. Copyright © 2015 Elsevier Inc. All rights reserved.

  13. Application of supercritical fluid in nanolithographic processes.

    Science.gov (United States)

    Zhou, Jijie

    2010-06-01

    The supercritical state provides an energetic environment in which high-aspect-ratio or active surface structures can be reacted, swelled, cleaned, or coated. Due to both low viscosity and low interfacial tension, reagent, solvent, rinsing and drying media of supercritical fluids can be efficiently delivered into the nanointerstices of a substrate. This article summarizes recent patents in the field of using supercritical fluids in nanolithographic processing methods such as drying, removal of lithographic resist, and formation of hybrid structures. Some of our recent efforts on restoring the collapsed on-chip nanotube arrays, and synthesizing zeolite-polymer hybrid membrane materials are exemplified as applications of supercritical fluids. Introducing supercritical effects may guide sustainable technologies for the development of green processes.

  14. Performance Evaluation of Strain Gauge Printed Using Automatic Fluid Dispensing System on Conformal Substrates

    Science.gov (United States)

    Khairilhijra Khirotdin, Rd.; Faridzuan Ngadiron, Mohamad; Adzeem Mahadzir, Muhammad; Hassan, Nurhafizzah

    2017-08-01

    Smart textiles require flexible electronics that can withstand daily stresses like bends and stretches. Printing using conductive inks provides the flexibility required but the current printing techniques suffered from ink incompatibility, limited of substrates to be printed with and incompatible with conformal substrates due to its rigidity and low flexibility. An alternate printing technique via automatic fluid dispensing system is proposed and its performances on printing strain gauge on conformal substrates were evaluated to determine its feasibility. Process parameters studied including printing speed, deposition height, curing time and curing temperature. It was found that the strain gauge is proven functional as expected since different strains were induced when bent on variation of bending angles and curvature radiuses from designated bending fixtures. The average change of resistances were doubled before the strain gauge starts to break. Printed strain gauges also exhibited some excellence elasticity as they were able to resist bending up to 70° angle and 3 mm of curvature radius.

  15. Flow Diode and Method for Controlling Fluid Flow Origin of the Invention

    Science.gov (United States)

    Dyson, Rodger W (Inventor)

    2015-01-01

    A flow diode configured to permit fluid flow in a first direction while preventing fluid flow in a second direction opposite the first direction is disclosed. The flow diode prevents fluid flow without use of mechanical closures or moving parts. The flow diode utilizes a bypass flowline whereby all fluid flow in the second direction moves into the bypass flowline having a plurality of tortuous portions providing high fluidic resistance. The portions decrease in diameter such that debris in the fluid is trapped. As fluid only travels in one direction through the portions, the debris remains trapped in the portions.

  16. Swimming in a granular frictional fluid

    Science.gov (United States)

    Goldman, Daniel

    2012-02-01

    X-ray imaging reveals that the sandfish lizard swims within granular media (sand) using axial body undulations to propel itself without the use of limbs. To model the locomotion of the sandfish, we previously developed an empirical resistive force theory (RFT), a numerical sandfish model coupled to an experimentally validated Discrete Element Method (DEM) model of the granular medium, and a physical robot model. The models reveal that only grains close to the swimmer are fluidized, and that the thrust and drag forces are dominated by frictional interactions among grains and the intruder. In this talk I will use these models to discuss principles of swimming within these granular ``frictional fluids". The empirical drag force laws are measured as the steady-state forces on a small cylinder oriented at different angles relative to the displacement direction. Unlike in Newtonian fluids, resistive forces are independent of speed. Drag forces resemble those in viscous fluids while the ratio of thrust to drag forces is always larger in the granular media than in viscous fluids. Using the force laws as inputs, the RFT overestimates swimming speed by approximately 20%. The simulation reveals that this is related to the non-instantaneous increase in force during reversals of body segments. Despite the inaccuracy of the steady-state assumption, we use the force laws and a recently developed geometric mechanics theory to predict optimal gaits for a model system that has been well-studied in Newtonian fluids, the three-link swimmer. The combination of the geometric theory and the force laws allows us to generate a kinematic relationship between the swimmer's shape and position velocities and to construct connection vector field and constraint curvature function visualizations of the system dynamics. From these we predict optimal gaits for forward, lateral and rotational motion. Experiment and simulation are in accord with the theoretical prediction, and demonstrate that

  17. Entropy generation by nanofluid with variable thermal conductivity ...

    African Journals Online (AJOL)

    The entropy generation by nanofluid with variable thermal conductivity and viscosity of assisted convective flow across a riser pipe of a horizontal flat plate solar collector is investigated numerically. The water based nanofluid with copper nanoparticles is used as the working fluid inside the fluid passing riser pipe.

  18. Low Conductivity Thermal Barrier Coatings

    Science.gov (United States)

    Zhu, Dong-Ming

    2005-01-01

    Thermal barrier coatings will be more aggressively designed to protect gas turbine engine hot-section components in order to meet future engine higher fuel efficiency and lower emission goals. In this presentation, thermal barrier coating development considerations and requirements will be discussed. An experimental approach is established to monitor in real time the thermal conductivity of the coating systems subjected to high-heat-flux, steady-state and cyclic temperature gradients. Advanced low conductivity thermal barrier coatings have also been developed using a multi-component defect clustering approach, and shown to have improved thermal stability. The durability and erosion resistance of low conductivity thermal barrier coatings have been improved utilizing advanced coating architecture design, composition optimization, in conjunction with more sophisticated modeling and design tools.

  19. Ion conductivity of nasicon ceramics

    International Nuclear Information System (INIS)

    Hoj, J.W.; Engell, J.

    1989-01-01

    The Nasicon ss ,Na 1 + X Zr 2 Si X P 3 - X O 12 o , X , 3, includes some of the best solid state sodium conductors known today. Compositions in the interval 1.6 , X , 2.6 show conductivities comparable to the best β double-prime-alumina ceramics. It is well known that the ion conductivity of β-alumina is strongly dependent on the texture of the ceramic. Here a similar behavior is reported for Nasicon ceramics. Ceramics of the bulk composition Na 2.94 Zr 1.49 Si 2.20 P 0.80 O 10.85 were prepared by a gel method. The final ceramics consist of Nasicon crystals with x = 2.14 and a glass phase. The grain size and texture of the ceramics were controlled by varying the thermal history of the gel based raw materials and the sintering conditions. The room temperature resistivity of the resulting ceramics varies from 3.65*10 3 ohm cm to 1.23*10 3 ohm cm. Using the temperature comparison method and estimates of the area of grain boundaries in the ceramics, the resistivity of the Nasicon phase is estimated to be 225 ohm cm at 25 degrees C. B 2 O 3 - or Al 2 O 3 -doping of the glass bearing Nasicon ceramic lower the room temperature resistivity by a factor 2 to 5. The dopants do not substitute into the Nasicon phase in substantial amounts

  20. The forward undulatory locomotion of Ceanorhabditis elegans in viscoelastic fluids

    Science.gov (United States)

    Shen, Amy; Ulrich, Xialing

    2013-11-01

    Caenorhabditis elegans is a soil dwelling roundworm that has served as model organisms for studying a multitude of biological and engineering phenomena. We study the undulatory locomotion of nematode in viscoelastic fluids with zero-shear viscosity varying from 0.03-75 Pa .s and relaxation times ranging from 0-350 s. We observe that the averaged normalized wavelength of swimming worm is essentially the same as that in Newtonian fluids. The undulatory frequency f shows the same reduction rate with respect to zero-shear viscosity in viscoelastic fluids as that found in the Newtonian fluids, meaning that the undulatory frequency is mainly controlled by the fluid viscosity. However, the moving speed Vm of the worm shows more distinct dependence on the elasticity of the fluid and exhibits a 4% drop with each 10-fold increase of the Deborah number De, a dimensionless number characterizing the elasticity of a fluid. To estimate the swimming efficiency coefficient and the ratio K =CN /CL of resistive coefficients of the worm in various viscoelastic fluids, we show that whereas it would take the worm around 7 periods to move a body length in a Newtonian fluid, it would take 27 periods to move a body length in a highly viscoelastic fluid.

  1. Carbon dioxide-based supercritical fluids as IC manufacturing solvents

    Energy Technology Data Exchange (ETDEWEB)

    Rubin, J.B.; Davenhall, L.B.; Taylor, C.M.V.; Sivils, L.D.; Pierce, T.; Tiefert, K.

    1999-05-11

    The production of integrated circuits (IC's) involves a number of discrete steps which utilize hazardous or regulated solvents and generate large waste streams. ES&H considerations associated with these chemicals have prompted a search for alternative, more environmentally benign solvent systems. An emerging technology for conventional solvent replacement is the use of supercritical fluids based on carbon dioxide (CO{sub 2}). Research work, conducted at Los Alamos in conjunction with the Hewlett-Packard Company, has lead to the development of a CO{sub 2}-based supercritical fluid treatment system for the stripping of hard-baked photoresists. This treatment system, known as Supercritical CO{sub 2} Resist Remover, or CORR, uses a two-component solvent composed of a nonhazardous, non-regulated compound, dissolved in supercritical CO{sub 2}. The solvent/treatment system has been successfully tested on metallized Si wafers coated with negative and positive photoresist, the latter both before and after ion-implantation. A description of the experimental data will be presented. Based on the initial laboratory results, the project has progressed to the design and construction of prototype, single-wafer photoresist-stripping equipment. The integrated system involves a closed-loop, recirculating cycle which continuously cleans and regenerates the CO{sub 2}, recycles the dissolved solvent, and separates and concentrates the spent resist. The status of the current design and implementation strategy of a treatment system to existing IC fabrication facilities will be discussed. Additional remarks will be made on the use of a SCORR-type system for the cleaning of wafers prior to processing.

  2. Resistance-resistant antibiotics.

    Science.gov (United States)

    Oldfield, Eric; Feng, Xinxin

    2014-12-01

    New antibiotics are needed because drug resistance is increasing while the introduction of new antibiotics is decreasing. We discuss here six possible approaches to develop 'resistance-resistant' antibiotics. First, multitarget inhibitors in which a single compound inhibits more than one target may be easier to develop than conventional combination therapies with two new drugs. Second, inhibiting multiple targets in the same metabolic pathway is expected to be an effective strategy owing to synergy. Third, discovering multiple-target inhibitors should be possible by using sequential virtual screening. Fourth, repurposing existing drugs can lead to combinations of multitarget therapeutics. Fifth, targets need not be proteins. Sixth, inhibiting virulence factor formation and boosting innate immunity may also lead to decreased susceptibility to resistance. Although it is not possible to eliminate resistance, the approaches reviewed here offer several possibilities for reducing the effects of mutations and, in some cases, suggest that sensitivity to existing antibiotics may be restored in otherwise drug-resistant organisms. Copyright © 2014 Elsevier Ltd. All rights reserved.

  3. FRACTURING FLUID CHARACTERIZATION FACILITY

    Energy Technology Data Exchange (ETDEWEB)

    Subhash Shah

    2000-08-01

    Hydraulic fracturing technology has been successfully applied for well stimulation of low and high permeability reservoirs for numerous years. Treatment optimization and improved economics have always been the key to the success and it is more so when the reservoirs under consideration are marginal. Fluids are widely used for the stimulation of wells. The Fracturing Fluid Characterization Facility (FFCF) has been established to provide the accurate prediction of the behavior of complex fracturing fluids under downhole conditions. The primary focus of the facility is to provide valuable insight into the various mechanisms that govern the flow of fracturing fluids and slurries through hydraulically created fractures. During the time between September 30, 1992, and March 31, 2000, the research efforts were devoted to the areas of fluid rheology, proppant transport, proppant flowback, dynamic fluid loss, perforation pressure losses, and frictional pressure losses. In this regard, a unique above-the-ground fracture simulator was designed and constructed at the FFCF, labeled ''The High Pressure Simulator'' (HPS). The FFCF is now available to industry for characterizing and understanding the behavior of complex fluid systems. To better reflect and encompass the broad spectrum of the petroleum industry, the FFCF now operates under a new name of ''The Well Construction Technology Center'' (WCTC). This report documents the summary of the activities performed during 1992-2000 at the FFCF.

  4. Endurance Pump Tests With Fresh and Purified MIL-PRF-83282 Hydraulic Fluid

    National Research Council Canada - National Science Library

    Sharma, Shashi

    1999-01-01

    .... Two endurance pump tests were conducted with F-16 aircraft hydraulic pumps, using both fresh and purified MIL-PRF-83282 hydraulic fluid, to determine if fluid purification had any adverse effect on pump life...

  5. Cerebral spinal fluid (CSF) collection

    Science.gov (United States)

    ... ency/article/003428.htm Cerebral spinal fluid (CSF) collection To use the sharing features on this page, please enable JavaScript. Cerebrospinal fluid (CSF) collection is a test to look at the fluid ...

  6. Fluid movement and creativity.

    Science.gov (United States)

    Slepian, Michael L; Ambady, Nalini

    2012-11-01

    Cognitive scientists describe creativity as fluid thought. Drawing from findings on gesture and embodied cognition, we hypothesized that the physical experience of fluidity, relative to nonfluidity, would lead to more fluid, creative thought. Across 3 experiments, fluid arm movement led to enhanced creativity in 3 domains: creative generation, cognitive flexibility, and remote associations. Alternative mechanisms such as enhanced mood and motivation were also examined. These results suggest that creativity can be influenced by certain types of physical movement. (PsycINFO Database Record (c) 2012 APA, all rights reserved).

  7. Fundamentals of fluid lubrication

    Science.gov (United States)

    Hamrock, Bernard J.

    1991-01-01

    The aim is to coordinate the topics of design, engineering dynamics, and fluid dynamics in order to aid researchers in the area of fluid film lubrication. The lubrication principles that are covered can serve as a basis for the engineering design of machine elements. The fundamentals of fluid film lubrication are presented clearly so that students that use the book will have confidence in their ability to apply these principles to a wide range of lubrication situations. Some guidance on applying these fundamentals to the solution of engineering problems is also provided.

  8. Synthetic Base Fluids

    Science.gov (United States)

    Brown, M.; Fotheringham, J. D.; Hoyes, T. J.; Mortier, R. M.; Orszulik, S. T.; Randles, S. J.; Stroud, P. M.

    The chemical nature and technology of the main synthetic lubricant base fluids is described, covering polyalphaolefins, alkylated aromatics, gas-to-liquid (GTL) base fluids, polybutenes, aliphatic diesters, polyolesters, polyalkylene glycols or PAGs and phosphate esters.Other synthetic lubricant base oils such as the silicones, borate esters, perfluoroethers and polyphenylene ethers are considered to have restricted applications due to either high cost or performance limitations and are not considered here.Each of the main synthetic base fluids is described for their chemical and physical properties, manufacture and production, their chemistry, key properties, applications and their implications when used in the environment.

  9. Stability of fault submitted to fluid injections

    Science.gov (United States)

    Brantut, N.; Passelegue, F. X.; Mitchell, T. M.

    2017-12-01

    Elevated pore pressure can lead to slip reactivation on pre-existing fractures and faults when the coulomb failure point is reached. From a static point of view, the reactivation of fault submitted to a background stress (τ0) is a function of the peak strength of the fault, i.e. the quasi-static effective friction coefficient (µeff). However, this theory is valid only when the entire fault is affected by fluid pressure, which is not the case in nature, and during human induced-seismicity. In this study, we present new results about the influence of the injection rate on the stability of faults. Experiments were conducted on a saw-cut sample of westerly granite. The experimental fault was 8 cm length. Injections were conducted through a 2 mm diameter hole reaching the fault surface. Experiments were conducted at four different order magnitudes fluid pressure injection rates (from 1 MPa/minute to 1 GPa/minute), in a fault system submitted to 50 and 100 MPa confining pressure. Our results show that the peak fluid pressure leading to slip depends on injection rate. The faster the injection rate, the larger the peak fluid pressure leading to instability. Wave velocity surveys across the fault highlighted that decreasing the injection-rate leads to an increase of size of the fluid pressure perturbation. Our result demonstrate that the stability of the fault is not only a function of the fluid pressure requires to reach the failure criterion, but is mainly a function of the ratio between the length of the fault affected by fluid pressure and the total fault length. In addition, we show that the slip rate increases with the background effective stress and with the intensity of the fluid pressure pertubation, i.e. with the excess shear stress acting on the part of the fault pertubated by fluid injection. Our results suggest that crustal fault can be reactivated by local high fluid overpressures. These results could explain the "large" magnitude human-induced earthquakes

  10. Electrical Conduction and Superconductivity

    Indian Academy of Sciences (India)

    resistivity of a superconductor changes with temperature.) While discussing electrical resistance in metals we came across the role of lattice. But the electron which gets scattered to another state of lower energy at the same time excites a certain mode of lattice vibration (phonon) having a certain momentum and energy.

  11. Flexible CFD meshing strategy for prediction of ship resistance and propulsion performance

    Directory of Open Access Journals (Sweden)

    Jeong Hwa Seo

    2010-09-01

    Full Text Available In the present study, we conducted resistance test, propeller open water test and self-propulsion test for a ship's resistance and propulsion performance, using computational fluid dynamics techniques, where a Reynolds-averaged Navier-Stokes equations solver was employed. For convenience of mesh generation, unstructured meshes were used in the bow and stern region of a ship, where the hull shape is formed of delicate curved surfaces. On the other hand, structured meshes were generated for the middle part of the hull and the rest of the domain, i.e., the region of relatively simple geometry. To facilitate the rotating propeller for propeller open water test and self-propulsion test, a sliding mesh technique was adopted. Free-surface effects were included by employing the volume of fluid method for multi-phase flows. The computational results were validated by comparing with the existing experimental data.

  12. Multidimensional Heat Conduction

    DEFF Research Database (Denmark)

    Rode, Carsten

    1998-01-01

    Analytical theory of multidimensional heat conduction. General heat conduction equation in three dimensions. Steay state, analytical solutions. The Laplace equation. Method of separation of variables. Principle of superposition. Shape factors. Transient, multidimensional heat conduction....

  13. Pericardial fluid culture

    Science.gov (United States)

    ... to identify organisms that cause infection. Pericardial fluid gram stain is a related topic. How the Test is ... member of Hi-Ethics and subscribes to the principles of the Health on the Net Foundation (www. ...

  14. Polymer Fluid Dynamics.

    Science.gov (United States)

    Bird, R. Byron

    1980-01-01

    Problems in polymer fluid dynamics are described, including development of constitutive equations, rheometry, kinetic theory, flow visualization, heat transfer studies, flows with phase change, two-phase flow, polymer unit operations, and drag reduction. (JN)

  15. Modeling Fluid Structure Interaction

    National Research Council Canada - National Science Library

    Benaroya, Haym

    2000-01-01

    The principal goal of this program is on integrating experiments with analytical modeling to develop physics-based reduced-order analytical models of nonlinear fluid-structure interactions in articulated naval platforms...

  16. Windshield washer fluid

    Science.gov (United States)

    ... fluid is a brightly colored liquid made of methanol, a poisonous alcohol. Sometimes, small amounts of other toxic alcohols, such as ethylene glycol, are added to the mixture. Some young children ...

  17. Cerebrospinal fluid dynamics study in communicating hydrocephalus.

    Science.gov (United States)

    Ramesh, Vengalathur Ganesan; Narasimhan, Vidhya; Balasubramanian, Chandramouli

    2017-01-01

    Communicating hydrocephalus often poses a challenge in diagnosis and management decisions. The objective of this study is to measure the opening pressure (P o ), pressure volume index (PVI), and cerebrospinal fluid outflow resistance (R out ), in patients with communicating hydrocephalus using bolus lumbar injection method and to evaluate its diagnostic and prognostic value. The study was conducted in 50 patients with communicating hydrocephalus, including normal pressure hydrocephalus (NPH) (19), post-meningitic hydrocephalus (23) and post-traumatic hydrocephalus (8). An improvised bolus lumbar injection method [the Madras Institute of Neurology (MIN) method] was used. In the NPH Group, the CSF dynamics studies correlated well with the clinico-radiological classification. The prediction of shunt responsiveness by CSF dynamics studies correlated with good outcome in 87.5%. In the post-meningitic hydrocephalus group, the value of CSF dynamics studies in predicting patients needing shunt was 89.5%. The CSF dynamics studies detected patients who needed shunt earlier than clinical or radiological indications. In the post-traumatic hydrocephalus group, 62.5% of patients improved with the treatment based on CSF dynamics studies. The improvised bolus lumbar injection method (MIN method) is a very simple test with fairly reliable and reproducible results. Study of CSF dynamics is a valuable tool in communicating hydrocephalus for confirmation of diagnosis and predicting shunt responsiveness. This is the first time that the value of CSF dynamics has been studied in patients with post-meningitic hydrocephalus. It was also useful for early selection of cases for shunting and for identifying patients with atrophic ventriculomegaly, thereby avoiding unnecessary shunt.

  18. Amniotic fluid inflammatory cytokines

    DEFF Research Database (Denmark)

    Abdallah, Morsi; Larsen, Nanna; Grove, Jakob

    2013-01-01

    The aim of the study was to analyze cytokine profiles in amniotic fluid (AF) samples of children developing autism spectrum disorders (ASD) and controls, adjusting for maternal autoimmune disorders and maternal infections during pregnancy.......The aim of the study was to analyze cytokine profiles in amniotic fluid (AF) samples of children developing autism spectrum disorders (ASD) and controls, adjusting for maternal autoimmune disorders and maternal infections during pregnancy....

  19. [Diagnosis: synovial fluid analysis].

    Science.gov (United States)

    Gallo Vallejo, Francisco Javier; Giner Ruiz, Vicente

    2014-01-01

    Synovial fluid analysis in rheumatological diseases allows a more accurate diagnosis in some entities, mainly infectious and microcrystalline arthritis. Examination of synovial fluid in patients with osteoarthritis is useful if a differential diagnosis will be performed with other processes and to distinguish between inflammatory and non-inflammatory forms. Joint aspiration is a diagnostic and sometimes therapeutic procedure that is available to primary care physicians. Copyright © 2014 Elsevier España, S.L. All rights reserved.

  20. Guttation fluid as a physiological marker for selection of nitrogen ...

    African Journals Online (AJOL)

    FRI Man

    2013-10-30

    Oct 30, 2013 ... A field experiment was conducted during the rainy season of 2008 and 2009 to use guttation fluid as a physiological marker for the screening of more nitrogen efficient rice genotypes on the basis of relationship between Guttation Fluid (GF) oozed by leaf tip and nitrogen use efficiency (NUE), grain.

  1. Fullerol ionic fluids

    KAUST Repository

    Fernandes, Nikhil

    2010-01-01

    We report for the first time an ionic fluid based on hydroxylated fullerenes (fullerols). The ionic fluid was synthesized by neutralizing the fully protonated fullerol with an amine terminated polyethylene/polypropylene oxide oligomer (Jeffamine®). The ionic fluid was compared to a control synthesized by mixing the partially protonated form (sodium form) of the fullerols with the same oligomeric amine in the same ratio as in the ionic fluids (20 wt% fullerol). In the fullerol fluid the ionic bonding significantly perturbs the thermal transitions and melting/crystallization behavior of the amine. In contrast, both the normalized heat of fusion and crystallization of the amine in the control are similar to those of the neat amine consistent with a physical mixture of the fullerols/amine with minimal interactions. In addition to differences in thermal behavior, the fullerol ionic fluid exhibits a complex viscoelastic behavior intermediate between the neat Jeffamine® (liquid-like) and the control (solid-like). © 2010 The Royal Society of Chemistry.

  2. Analysis of anaerobic product properties in fluid and aggressive environments

    OpenAIRE

    Goncharov, A.; Tulinov, A.

    2008-01-01

    The article presents the results of experiments involved in investigation of properties of some domestic and foreign-made anaerobic materials in components and units operating in fluid and aggressive environments. These experiments determined the strength and swell values of anaerobic products in the sea water, fuel and oil, and confirmed their anticorrosion properties. The experiments demonstrated high resistance of anaerobic products to various fluids and aggressive environments, which make...

  3. 1D multi-fluid plasma models

    International Nuclear Information System (INIS)

    Bachmann, P.; Suender, D.

    1998-01-01

    1D and time-dependent multi-fluid plasma models are derived from multi-fluid MHD equations. Including neutral particles and their ionization stages as fluids increases the number of equations to be solved and the indeterminacy of the results considerably. For this reason, especially for the case of high-Z materials, the impurities are described by distinct approaches without restricting the impurity densities to be small compared with the hydrogen plasma density. Using the approach of the average ion model, neglecting the effect of the neutral particles, equalizing the plasma temperatures and adopting the condition of quasi-neutrality, we arrive at a three-fluid description and analyze wave front solution of the self-consistent system of equations obtained. This system is reduced to a two-fluid description assuming the flow velocities of the electrons and ions to be equal. This model can be reduced further to a currentless, modified one-fluid approach if the impurity density in dependence on the model functions is known. Introducing Lagrangian coordinates and assuming a constant total pressure a single reaction-diffusion equation for the temperature is obtained. A differential equation for the impurity density in dependence of the temperature has to be included. It determines the influence of the impurities on the reaction-diffusion process which affect not only the radiation loss but also the heat conduction. This is demonstrated for carbon, beryllium and high-Z impurities. (orig.)

  4. statistical fluid theory for associating fluids containing alternating ...

    Indian Academy of Sciences (India)

    Abstract. Statistical associating fluid theory of homonuclear dimerized chain fluids and homonuclear monomer-dimer mixture chain fluids are extended to fluids containing al- ternating heteronuclear chain molecules separately. The proposed models account for the appropriate site-site correlation functions at contact.

  5. Surface and bulk conductivity of vanadium dioxide

    Science.gov (United States)

    Tutov, E. A.; Manannikov, A. V.; Al-Khafaji, H. I.; Zlomanov, V. P.

    2017-03-01

    The dc and ac resistances of a TR-68 thermistor based on the vanadium dioxide film have been measured and the temperature dependence of the resistance in the semiconductor-metal transition region under adsorption has been studied. The energy band model has been proposed, which explains the anomalous response to adsorption of donor gases by the inversion of the conductivity type of vanadium dioxide surface layers.

  6. Corrosion Protection of Electrically Conductive Surfaces

    Directory of Open Access Journals (Sweden)

    Jian Song

    2012-11-01

    Full Text Available The basic function of the electrically conductive surface of electrical contacts is electrical conduction. The electrical conductivity of contact materials can be largely reduced by corrosion and in order to avoid corrosion, protective coatings must be used. Another phenomenon that leads to increasing contact resistance is fretting corrosion. Fretting corrosion is the degradation mechanism of surface material, which causes increasing contact resistance. Fretting corrosion occurs when there is a relative movement between electrical contacts with surfaces of ignoble metal. Avoiding fretting corrosion is therefore extremely challenging in electronic devices with pluggable electrical connections. Gold is one of the most commonly used noble plating materials for high performance electrical contacts because of its high corrosion resistance and its good and stable electrical behavior. The authors have investigated different ways to minimize the consumption of gold for electrical contacts and to improve the performance of gold plating. Other plating materials often used for corrosion protection of electrically conductive surfaces are tin, nickel, silver and palladium. This paper will deal with properties and new research results of different plating materials in addition to other means used for corrosion protection of electrically conductive surfaces and the testing of corrosion resistance of electrically conductive surfaces.

  7. Thermal conductivity model for nanofiber networks

    Science.gov (United States)

    Zhao, Xinpeng; Huang, Congliang; Liu, Qingkun; Smalyukh, Ivan I.; Yang, Ronggui

    2018-02-01

    Understanding thermal transport in nanofiber networks is essential for their applications in thermal management, which are used extensively as mechanically sturdy thermal insulation or high thermal conductivity materials. In this study, using the statistical theory and Fourier's law of heat conduction while accounting for both the inter-fiber contact thermal resistance and the intrinsic thermal resistance of nanofibers, an analytical model is developed to predict the thermal conductivity of nanofiber networks as a function of their geometric and thermal properties. A scaling relation between the thermal conductivity and the geometric properties including volume fraction and nanofiber length of the network is revealed. This model agrees well with both numerical simulations and experimental measurements found in the literature. This model may prove useful in analyzing the experimental results and designing nanofiber networks for both high and low thermal conductivity applications.

  8. Thermal conductivity model for nanofiber networks

    Energy Technology Data Exchange (ETDEWEB)

    Zhao, Xinpeng [Department of Mechanical Engineering, University of Colorado, Boulder, Colorado 80309, USA; Huang, Congliang [Department of Mechanical Engineering, University of Colorado, Boulder, Colorado 80309, USA; School of Electrical and Power Engineering, China University of Mining and Technology, Xuzhou 221116, China; Liu, Qingkun [Department of Physics, University of Colorado, Boulder, Colorado 80309, USA; Smalyukh, Ivan I. [Department of Physics, University of Colorado, Boulder, Colorado 80309, USA; Materials Science and Engineering Program, University of Colorado, Boulder, Colorado 80309, USA; Yang, Ronggui [Department of Mechanical Engineering, University of Colorado, Boulder, Colorado 80309, USA; Materials Science and Engineering Program, University of Colorado, Boulder, Colorado 80309, USA; Buildings and Thermal Systems Center, National Renewable Energy Laboratory, Golden, Colorado 80401, USA

    2018-02-28

    Understanding thermal transport in nanofiber networks is essential for their applications in thermal management, which are used extensively as mechanically sturdy thermal insulation or high thermal conductivity materials. In this study, using the statistical theory and Fourier's law of heat conduction while accounting for both the inter-fiber contact thermal resistance and the intrinsic thermal resistance of nanofibers, an analytical model is developed to predict the thermal conductivity of nanofiber networks as a function of their geometric and thermal properties. A scaling relation between the thermal conductivity and the geometric properties including volume fraction and nanofiber length of the network is revealed. This model agrees well with both numerical simulations and experimental measurements found in the literature. This model may prove useful in analyzing the experimental results and designing nanofiber networks for both high and low thermal conductivity applications.

  9. Motions of elastic solids in fluids under vibration

    DEFF Research Database (Denmark)

    Sorokin, V. S.; Blekhman, I. I.; Thomsen, Jon Juel

    2010-01-01

    Motion of a rigid or deformable solid in a viscous incompressible fluid and corresponding fluid–solid interactions are considered. Different cases of applying high frequency vibrations to the solid or to the surrounding fluid are treated. Simple formulas for the mean velocity of the solid...... are derived, under the assumption that the regime of the fluid flow induced by its motion is turbulent and the fluid resistance force is nonlinearly dependent on its velocity. It is shown that vibrations of a fluid’s volume slow down the motion of a submerged solid. This effect is much pronounced in the case...... of a deformable solid (i.e., gas bubble) exposed to near-resonant excitation. The results are relevant to the theory of gravitational enrichment of raw materials, and also contribute to the theory of controlled locomotion of a body with an internal oscillator in continuous deformable (solid or fluid) media....

  10. Two-phase cooling fluids; Les fluides frigoporteurs diphasiques

    Energy Technology Data Exchange (ETDEWEB)

    Lallemand, A. [Institut National des Sciences Appliquees (INSA), 69 - Lyon (France)

    1997-12-31

    In the framework of the diminution of heat transfer fluid consumption, the concept of indirect refrigerating circuits, using cooling intermediate fluids, is reviewed and the fluids that are currently used in these systems are described. Two-phase cooling fluids advantages over single-phase fluids are presented with their thermophysical characteristics: solid fraction, two-phase mixture enthalpy, thermal and rheological properties, determination of heat and mass transfer characteristics, and cold storage through ice slurry

  11. Viscous Flow with Large Fluid-Fluid Interface Displacement

    DEFF Research Database (Denmark)

    Rasmussen, Henrik Koblitz; Hassager, Ole; Saasen, Arild

    1998-01-01

    The arbitrary Lagrange-Euler (ALE) kinematic description has been implemented in a 3D transient finite element program to simulate multiple fluid flows with fluid-fluid interface or surface displacements. The description of fluid interfaces includes variable interfacial tension, and the formulation...... is useful in the simulation of low and intermediate Reynolds number viscous flow. The displacement of two immiscible Newtonian fluids in a vertical (concentric and eccentric) annulus and a (vertical and inclined)tube is simulated....

  12. Fluid and structural-dynamic piping system analysis

    International Nuclear Information System (INIS)

    Korthauer, H.J.; Lange, H.; Rychlik, G.

    1993-01-01

    By means of the fluid and structural-dynamic analyses conducted, the cooling system was qualified for all fluid-dynamic processes in normal and anomalous operation and in case of accidents. The boundary conditions assumed by us for the fluid and structural-dynamic analyses were confirmed by the forces and movements measured time for some operating conditions as a function of time. Expensive hardware measures such as additional supports or replacement of Tees were not necessary as we combined the fluid and structural-dynamic analyses and then demonstrated safety of the supports, connected components and some of the piping elements as such. (author)

  13. [Research activities in applied mathematics, fluid mechanics, and computer science

    Science.gov (United States)

    1995-01-01

    This report summarizes research conducted at the Institute for Computer Applications in Science and Engineering in applied mathematics, fluid mechanics, and computer science during the period April 1, 1995 through September 30, 1995.

  14. Research in Applied Mathematics, Fluid Mechanics and Computer Science

    Science.gov (United States)

    1999-01-01

    This report summarizes research conducted at the Institute for Computer Applications in Science and Engineering in applied mathematics, fluid mechanics, and computer science during the period October 1, 1998 through March 31, 1999.

  15. Microsecond-conduction-time POS experiments

    International Nuclear Information System (INIS)

    Weber, B.V.; Boller, J.R.; Commisso, R.J.; Grossman, J.M.; Kellogg, J.C.; Ottinger, P.F.; Cooperstein, G.; Goodrich, P.J.; Hinshelwood, D.D.

    1993-01-01

    Experiments have been performed to improve tHe understanding of the μs-conduction-time plasma opening switch (POS). Measurements with a He-Ne laser interferometer show that the line-integrated plasma density reaches a peak value during conduction, then decreases to a relatively small value before opening begins. During opening, the density is low over a large fraction of the electrode gap, but is relatively high at both electrodes, indicating that opening actually occurs in the middle of the electrode gap. The dependence of conduction current and conduction time on density and other POS parameters (radius, length, and current waveform) indicate that conduction is controlled by hydrodynamic displacement and distortion of the plasma, resulting in a low density region where opening occurs, possibly by erosion. Experiments with electron-beam diode loads have been performed for a variety of load and POS configurations. Assuming the POS gap at peak power equals the radial extent of the electron orbits, the calculated switch gap is about 2-3 mm over a wide range of load impedances, conduction currents, and center conductor radii. Increased load power requires increasing the (effective) gap size. Fluid and PIC codes may be suitable to simulate the conduction and opening phases, respectively, and a combined fluid/particle model could indicate promising methods for increasing the output power using a POS

  16. Detecting subsurface fluid leaks in real-time using injection and production rates

    Science.gov (United States)

    Singh, Harpreet; Huerta, Nicolas J.

    2017-12-01

    CO2 injection into geologic formations for either enhanced oil recovery or carbon storage introduces a risk for undesired fluid leakage into overlying groundwater or to the surface. Despite decades of subsurface CO2 production and injection, the technologies and methods for detecting CO2 leaks are still costly and prone to large uncertainties. This is especially true for pressure-based monitoring methods, which require the use of simplified geological and reservoir flow models to simulate the pressure behavior as well as background noise affecting pressure measurements. In this study, we propose a method to detect the time and volume of fluid leakage based on real-time measurements of well injection and production rates. The approach utilizes analogies between fluid flow and capacitance-resistance modeling. Unlike other leak detection methods (e.g. pressure-based), the proposed method does not require geological and reservoir flow models to simulate the behavior that often carry significant sources of uncertainty; therefore, with our approach the leak can be detected with greater certainty. The method can be applied to detect when a leak begins by tracking a departure in fluid production rate from the expected pattern. The method has been tuned to detect the effect of boundary conditions and fluid compressibility on leakage. To highlight the utility of this approach we use our method to detect leaks for two scenarios. The first scenario simulates a fluid leak from the storage formation into an above-zone monitoring interval. The second scenario simulates intra-reservoir migration between two compartments. We illustrate this method to detect fluid leakage in three different reservoirs with varying levels of geological and structural complexity. The proposed leakage detection method has three novelties: i) requires only readily-available data (injection and production rates), ii) accounts for fluid compressibility and boundary effects, and iii) in addition to

  17. Long-term autonomous resistivity monitoring of oil-contaminated sediments from the Deepwater Horizon spill

    Science.gov (United States)

    Heenan, J. W.; Slater, L. D.; Ntarlagiannis, D.; Atekwana, E. A.; Ross, C.; Nolan, J. T.; Atekwana, E. A.; Werkema, D. D.; Fathepure, B.

    2012-12-01

    outside of the contaminated location exhibit relatively uniform resistivity or show clear evidence of seasonal effect. Temperature-corrected resistivity changes show no direct correlation with pore fluid specific conductance changes, suggesting that specific conductance changes (e.g. due to tides) have little influence on imaged resistivity structure. Microbial data suggest that resistivity changes within the contaminated location resulted from biodegradation, showing the presence of native populations capable of degrading aromatic hydrocarbons at salinities ranging from 6 to 15 % NaCl within the contaminated location. Aqueous geochemical measurements performed on samples from the site further indicate that at depth intervals coincident with the resistivity anomaly, marked increases in the concentration of dissolved inorganic carbon (DIC) were observed suggesting biodegradation of petroleum hydrocarbon although other DIC generating processes such as organic matter degradation coupled to sulfate and iron reduction were also prominent. This experiment demonstrates the potential viability of long-term autonomous electrical monitoring as a means of decreasing the frequency of more costly and invasive chemical analysis of natural attenuation.

  18. High-order Two-Fluid Plasma Solver for Direct Numerical Simulations of Magnetic Flows with Realistic Transport Phenomena

    Science.gov (United States)

    Li, Zhaorui; Livescu, Daniel

    2017-11-01

    The two-fluid plasma equations with full transport terms, including temperature and magnetic field dependent ion and electron viscous stresses and heat fluxes, frictional drag force, and ohmic heating term have been solved by using the sixth-order non-dissipative compact scheme for plasma flows in several different regimes. In order to be able to fully resolve all the dynamically relevant time and length scales while maintaining computational feasibility, the assumptions of infinite speed of light and negligible electron inertia have been made. The accuracy and robustness of this two-fluid plasma solver in handling plasma flows have been tested against a series of canonical problems, such as Alfven-Whistler dispersion relation, electromagnetic plasma shock, magnetic reconnection, etc. For all test cases, grid convergence tests have been conducted to achieve fully resolved results. The roles of heat flux, viscosity, resistivity, Hall and Biermann battery effects, are investigated for the canonical flows studied.

  19. Using electrical resistance tomography to map subsurface temperatures

    Science.gov (United States)

    Ramirez, Abelardo L.; Chesnut, Dwayne A.; Daily, William D.

    1994-01-01

    A method is provided for measuring subsurface soil or rock temperatures remotely using electrical resistivity tomography (ERT). Electrical resistivity measurements are made using electrodes implanted in boreholes driven into the soil and/or at the ground surface. The measurements are repeated as some process changes the temperatures of the soil mass/rock mass. Tomographs of electrical resistivity are calculated based on the measurements using Poisson's equation. Changes in the soil/rock resistivity can be related to changes in soil/rock temperatures when: (1) the electrical conductivity of the fluid trapped in the soil's pore space is low, (2) the soil/rock has a high cation exchange capacity and (3) the temperature changes are sufficiently high. When these three conditions exist the resistivity changes observed in the ERT tomographs can be directly attributed to changes in soil/rock temperatures. This method provides a way of mapping temperature changes in subsurface soils remotely. Distances over which the ERT method can be used to monitor changes in soil temperature range from tens to hundreds of meters from the electrode locations.

  20. Selected topics of fluid mechanics

    Science.gov (United States)

    Kindsvater, Carl E.

    1958-01-01

    the Euler, Froude, Reynolds, Weber, and Cauchy numbers are defined as essential tools for interpreting and using experimental data. The derivations of the energy and momentum equations are treated in detail. One-dimensional equations for steady nonuniform flow are developed, and the restrictions applicable to the equations are emphasized. Conditions of uniform and gradually varied flow are discussed, and the origin of the Chezy equation is examined in relation to both the energy and the momentum equations. The inadequacy of all uniform-flow equations as a means of describing gradually varied flow is explained. Thus, one of the definitive problems of river hydraulics is analyzed in the light of present knowledge. This report is the outgrowth of a series of short schools conducted during the spring and summer of 1953 for engineers of the Surface Water Branch, Water Resources Division, U. S. Geological Survey. The topics considered are essentially the same as the topics selected for inclusion in the schools. However, in order that they might serve better as a guide and outline for informal study, the arrangement of the writer's original lecture notes has been considerably altered. The purpose of the report, like the purpose of the schools which inspired it, is to build a simple but strong framework of the fundamentals of fluid mechanics. It is believed that this framework is capable of supporting a detailed analysis of most of the practical problems met by the engineers of the Geological Survey. It is hoped that the least accomplishment of this work will be to inspire the reader with the confidence and desire to read more of the recent and current technical literature of modern fluid mechanics.

  1. Groundwater redox conditions and conductivity in a contaminant plume from geoelectrical investigations

    Directory of Open Access Journals (Sweden)

    V. Naudet

    2004-01-01

    Full Text Available Accurate mapping of the electrical conductivity and of the redox potential of the groundwater is important in delineating the shape of a contaminant plume. A map of redox potential in an aquifer is indicative of biodegradation of organic matter and of concentrations of redox-active components; a map of electrical conductivity provides information on the mineralisation of the groundwater. Both maps can be used to optimise the position of pumping wells for remediation. The self-potential method (SP and electrical resistivity tomography (ERT have been applied to the contaminant plume associated with the Entressen landfill in south-east France. The self-potential depends on groundwater flow (electrokinetic contribution and redox conditions ('electro-redox' contribution. Using the variation of the piezometric head in the aquifer, the electrokinetic contribution is removed from the SP signals. A good linear correlation (R2=0.85 is obtained between the residual SP data and the redox potential values measured in monitoring wells. This relationship is used to draw a redox potential map of the overall contaminated site. The electrical conductivity of the subsoil is obtained from 3D-ERT analysis. A good linear correlation (R2=0.91 is observed between the electrical conductivity of the aquifer determined from the 3D-ERT image and the conductivity of the groundwater measured in boreholes. This indicates that the formation factor is nearly homogeneous in the shallow aquifer at the scale of the ERT. From this correlation, a map of the pore water conductivity of the aquifer is obtained. Keywords: self-potential, redox potential, electrical resistivity tomography, fluid conductivity, contaminant plume

  2. Characterization of the Mechanical Properties of Electrorheological Fluids Made of Starch and Silicone Fluid

    Science.gov (United States)

    Vieira, Sheila Lopes; de Arruda, Antonio Celso Fonseca

    In the majority of published articles on the topic, ER fluids have been studied as if they were viscous liquids. In this work, electrorheological fluids were characterized as solids and their mechanical properties were determined. The results infer that ER materials are controllably resistant to compression, tensile and shear stress, in this order of magnitude. More precisely, fluids made of starch have elasticity modulus similar to that of rubber, they have tensile strength 103 to 5×104 times lower than that of low density polyethylene (LDPE), static yield stress 4×104 to 8×105 times lower than that of acrylonitrile-butadiene-styrene terpolymer (ABS) and fatigue life similar to some polymers like polyethylene(PE) and polypropylene (PP).

  3. Determining solid-fluid interface temperature distribution during phase change of cryogenic propellants using transient thermal modeling

    Science.gov (United States)

    Bellur, K.; Médici, E. F.; Hermanson, J. C.; Choi, C. K.; Allen, J. S.

    2018-04-01

    Control of boil-off of cryogenic propellants is a continuing technical challenge for long duration space missions. Predicting phase change rates of cryogenic liquids requires an accurate estimation of solid-fluid interface temperature distributions in regions where a contact line or a thin liquid film exists. This paper described a methodology to predict inner wall temperature gradients with and without evaporation using discrete temperature measurements on the outer wall of a container. Phase change experiments with liquid hydrogen and methane in cylindrical test cells of various materials and sizes were conducted at the Neutron Imaging Facility at the National Institute of Standards and Technology. Two types of tests were conducted. The first type of testing involved thermal cycling of an evacuated cell (dry) and the second involved controlled phase change with cryogenic liquids (wet). During both types of tests, temperatures were measured using Si-diode sensors mounted on the exterior surface of the test cells. Heat is transferred to the test cell by conduction through a helium exchange gas and through the cryostat sample holder. Thermal conduction through the sample holder is shown to be the dominant mode with the rate of heat transfer limited by six independent contact resistances. An iterative methodology is employed to determine contact resistances between the various components of the cryostat stick insert, test cell and lid using the dry test data. After the contact resistances are established, inner wall temperature distributions during wet tests are calculated.

  4. Rheology of Active Fluids

    Science.gov (United States)

    Saintillan, David

    2018-01-01

    An active fluid denotes a viscous suspension of particles, cells, or macromolecules able to convert chemical energy into mechanical work by generating stresses on the microscale. By virtue of this internal energy conversion, these systems display unusual macroscopic rheological signatures, including a curious transition to an apparent superfluid-like state where internal activity exactly compensates viscous dissipation. These behaviors are unlike those of classical complex fluids and result from the coupling of particle configurations with both externally applied flows and internally generated fluid disturbances. Focusing on the well-studied example of a suspension of microswimmers, this review summarizes recent experiments, models, and simulations in this area and highlights the critical role played by the rheological response of these active materials in a multitude of phenomena, from the enhanced transport of passive suspended objects to the emergence of spontaneous flows and collective motion.

  5. EXPERIMENTAL INVESTIGATION TO STUDY THE VISCOSITY AND DISPERSION OF CONDUCTIVE AND NON-CONDUCTIVE NANOPOWDERS’ BLENDED DIELECTRICS

    Directory of Open Access Journals (Sweden)

    K. Santarao

    2017-03-01

    Full Text Available Nano fluids are nanotechnology-based colloidal dispersions engineered by stably suspending nanoparticles. The characteristics of nano fluids such as thermal and electrical conductivities, viscosity, specific heat, dispersion etc. were studied and analyzed by earlier researches at different particle concentrations with different nano fluids. It was established that nano fluids have a significant impact on the process due the improvised characteristics. nano fluid viscosity and dispersion deserve the same attention as thermal conductivity in cases of nano dielectric fluids that are used in EDM as they influence the MRR. In this work, The viscosity and dispersion of the conductive and nonconductive nano powders blended dielectrics are investigated as a function of volume fraction so as to evaluate the behavior of these nano fluids at different particle volume concentrations. Kerosene and deionized water based nano fluids blended with conductive (SiC and non-conductive (boric acid nano particles are selected for the current study. It is observed that as the percentage volume fraction of Nano particles (both SiC and boric acid increased, the viscosity was found increasing when blended with DI water. But the viscosity behavior with Kerosene blended with SiC and boric acid is not same. The existing experimental results about the nano fluids viscosity shows clearly that viscosity have a specific trend in variation with an increase of volume concentration. Boric acid blended with DIW and Kerosene shows similar trend in dispersion. However, in case of SiC blended with DIW and Kerosene showed some contradictory results giving scope for further investigation. The outcome of these experimental investigations will augment the works that are going on in studying its influence on MRR in EDM processes using nano blended dielectric medium.

  6. Complex conductivity of soils

    DEFF Research Database (Denmark)

    Revil, A.; Coperey, A.; Shao, Z.

    2017-01-01

    The complex conductivity of soil remains poorly known despite the growing importance of this method in hyrogeophysics. In order to fill this gap of knowledge, we investigate the complex conductivity of 71 soils samples (including 4 peat samples) and one clean sand in the frequency range 0.1 Hertz...... to 45 kHz. The soil samples are saturated with 6 different NaCl brines with conductivities (0.031, 0.53, 1.15, 5.7, 14.7, and 22 S m-1, NaCl, 25°C) in order to determine their intrinsic formation factor and surface conductivity. This dataset is used to test the predictions of the dynamic Stern...... polarization model of porous media in terms of relationship between the quadrature conductivity and the surface conductivity. We also investigate the relationship between the normalized chargeability (the difference of in phase conductivity between two frequencies) and the quadrature conductivity...

  7. Cardiac conduction system

    Science.gov (United States)

    The cardiac conduction system is a group of specialized cardiac muscle cells in the walls of the heart that send signals to the ... contract. The main components of the cardiac conduction system are the SA node, AV node, bundle of ...

  8. Computational fluid dynamics

    CERN Document Server

    Magoules, Frederic

    2011-01-01

    Exploring new variations of classical methods as well as recent approaches appearing in the field, Computational Fluid Dynamics demonstrates the extensive use of numerical techniques and mathematical models in fluid mechanics. It presents various numerical methods, including finite volume, finite difference, finite element, spectral, smoothed particle hydrodynamics (SPH), mixed-element-volume, and free surface flow.Taking a unified point of view, the book first introduces the basis of finite volume, weighted residual, and spectral approaches. The contributors present the SPH method, a novel ap

  9. Mechanics of fluid flow

    CERN Document Server

    Basniev, Kaplan S; Chilingar, George V 0

    2012-01-01

    The mechanics of fluid flow is a fundamental engineering discipline explaining both natural phenomena and human-induced processes, and a thorough understanding of it is central to the operations of the oil and gas industry.  This book, written by some of the world's best-known and respected petroleum engineers, covers the concepts, theories, and applications of the mechanics of fluid flow for the veteran engineer working in the field and the student, alike.  It is a must-have for any engineer working in the oil and gas industry.

  10. Developing seamless method to calculate heat convection and conduction on cartesian grid

    International Nuclear Information System (INIS)

    Tanno, I.; Morinishi, K.; Matsuno, K.; Nishida, H.

    2005-01-01

    In these days, studying and developing algorithms which calculate fluid flows which have interfaces or bodies on cartesian grid become trend of computational fluid dynamics area. In this paper, we propose Virtual Flux Method (VFM) which calculates heat and fluid flow around interfaces or bodies on cartesian grid. This method enables to seamlessly calculate heat convection on the surface of the bodies and fluid and heat conduction inside bodies. In three dimensional calculations of shell and tube type heat exchangers, there is a possibility that fluid inside and outside tubes and heat flow between these fluid and tube bodies are calculated without any kind of extra algorithms but VFM. (author)

  11. Calculating lattice thermal conductivity: a synopsis

    Science.gov (United States)

    Fugallo, Giorgia; Colombo, Luciano

    2018-04-01

    We provide a tutorial introduction to the modern theoretical and computational schemes available to calculate the lattice thermal conductivity in a crystalline dielectric material. While some important topics in thermal transport will not be covered (including thermal boundary resistance, electronic thermal conduction, and thermal rectification), we aim at: (i) framing the calculation of thermal conductivity within the general non-equilibrium thermodynamics theory of transport coefficients, (ii) presenting the microscopic theory of thermal conduction based on the phonon picture and the Boltzmann transport equation, and (iii) outlining the molecular dynamics schemes to calculate heat transport. A comparative and critical addressing of the merits and drawbacks of each approach will be discussed as well.

  12. Two-Fluid Mathematical Models for Blood Flow in Stenosed Arteries: A Comparative Study

    Directory of Open Access Journals (Sweden)

    Sankar DS

    2009-01-01

    Full Text Available The pulsatile flow of blood through stenosed arteries is analyzed by assuming the blood as a two-fluid model with the suspension of all the erythrocytes in the core region as a non-Newtonian fluid and the plasma in the peripheral layer as a Newtonian fluid. The non-Newtonian fluid in the core region of the artery is assumed as a (i Herschel-Bulkley fluid and (ii Casson fluid. Perturbation method is used to solve the resulting system of non-linear partial differential equations. Expressions for various flow quantities are obtained for the two-fluid Casson model. Expressions of the flow quantities obtained by Sankar and Lee (2006 for the two-fluid Herschel-Bulkley model are used to get the data for comparison. It is found that the plug flow velocity and velocity distribution of the two-fluid Casson model are considerably higher than those of the two-fluid Herschel-Bulkley model. It is also observed that the pressure drop, plug core radius, wall shear stress and the resistance to flow are significantly very low for the two-fluid Casson model than those of the two-fluid Herschel-Bulkley model. Hence, the two-fluid Casson model would be more useful than the two-fluid Herschel-Bulkley model to analyze the blood flow through stenosed arteries.

  13. Amniotic fluid embolism mortality rate.

    Science.gov (United States)

    Benson, Michael D

    2017-11-01

    The objective of this study was to determine the mortality rate of amniotic fluid embolism (AFE) using population-based studies and case series. A literature search was conducted using the two key words: 'amniotic fluid embolism (AFE)' AND 'mortality rate'. Thirteen population-based studies were evaluated, as well as 36 case series including at least two patients. The mortality rate from population-based studies varied from 11% to 44%. When nine population-based studies with over 17 000 000 live births were aggregated, the maternal mortality rate was 20.4%. In contrast, the mortality rate of AFE in case series varies from 0% to 100% with numerous rates in between. The AFE mortality rate in population-based studies varied from 11% to 44% with the best available evidence supporting an overall mortality rate of 20.4%. Data from case series should no longer be used as a basis for describing the lethality of AFE. © 2017 Japan Society of Obstetrics and Gynecology.

  14. Bone Conduction: Anatomy, Physiology, and Communication

    Science.gov (United States)

    2007-05-01

    Society of America 1956, 28, 1277-1284. Franke, E.; Gierke , H.; von Grossman, F.; Wittern, W. The Jaw Motions Relative to the Skull and their...Studies by von Bekesy in 1930s were conducted in cadavers rather than in live humans. The mechanical properties can account for the slope of the...one who suffers from a genetic disease caused by the accumulation of a watery fluid within the brain. There are 14 facial bones on the human skull

  15. Management of Conductive Hearing Loss in Children.

    Science.gov (United States)

    Dougherty, William; Kesser, Bradley W

    2015-12-01

    Conductive hearing loss (CHL), far more common than sensorineural hearing loss in children, can be acquired or congenital, can range from mild to moderately severe, and can be caused by a simple cerumen impaction, middle ear fluid, or complex middle ear abnormalities with or without the absence of the ear canal (congenital aural atresia). This article presents evidence-based recommendations for the evaluation and management of the child with both acquired and congenital CHL. Copyright © 2015 Elsevier Inc. All rights reserved.

  16. Endurance Pump Test with MIL-PRF-83282 Hydraulic Fluid, Purified with Malabar Purifier

    National Research Council Canada - National Science Library

    Sharma, Shashi

    2004-01-01

    .... Endurance aircraft hydraulic pump tests under carefully controlled conditions were previously conducted using hydraulic fluid purified with a rotating-disk and vacuum type purifier, the portable...

  17. Conducting polymer materials

    Directory of Open Access Journals (Sweden)

    Jovanović Slobodan M.

    2003-01-01

    Full Text Available Conducting polymers represent a very interesting group of polymer materials Investigation of the synthesis, structure and properties of these materials has been the subject of considerable research efforts in the last twenty years. A short presentating of newer results obtained by investigating of the synthesis, structure and properties of two basic groups of conducting polymers: a conducting polymers the conductivity of which is the result of their molecular structure, and b conducting polymer composites (EPC, is given in this paper. The applications and future development of this group of polymer materials is also discussed.

  18. "Nanotechnology Enabled Advanced Industrial Heat Transfer Fluids"

    Energy Technology Data Exchange (ETDEWEB)

    Dr. Ganesh Skandan; Dr. Amit Singhal; Mr. Kenneth Eberts; Mr. Damian Sobrevilla; Prof. Jerry Shan; Stephen Tse; Toby Rossmann

    2008-06-12

    ABSTRACT Nanotechnology Enabled Advanced industrial Heat Transfer Fluids” Improving the efficiency of Industrial Heat Exchangers offers a great opportunity to improve overall process efficiencies in diverse industries such as pharmaceutical, materials manufacturing and food processing. The higher efficiencies can come in part from improved heat transfer during both cooling and heating of the material being processed. Additionally, there is great interest in enhancing the performance and reducing the weight of heat exchangers used in automotives in order to increase fuel efficiency. The goal of the Phase I program was to develop nanoparticle containing heat transfer fluids (e.g., antifreeze, water, silicone and hydrocarbon-based oils) that are used in transportation and in the chemical industry for heating, cooling and recovering waste heat. Much work has been done to date at investigating the potential use of nanoparticle-enhanced thermal fluids to improve heat transfer in heat exchangers. In most cases the effect in a commercial heat transfer fluid has been marginal at best. In the Phase I work, we demonstrated that the thermal conductivity, and hence heat transfer, of a fluid containing nanoparticles can be dramatically increased when subjected to an external influence. The increase in thermal conductivity was significantly larger than what is predicted by commonly used thermal models for two-phase materials. Additionally, the surface of the nanoparticles was engineered so as to have a minimal influence on the viscosity of the fluid. As a result, a nanoparticle-laden fluid was successfully developed that can lead to enhanced heat transfer in both industrial and automotive heat exchangers

  19. Electrical and Thermal Conductivity and Conduction Mechanism of Ge2Sb2Te5 Alloy

    Science.gov (United States)

    Lan, Rui; Endo, Rie; Kuwahara, Masashi; Kobayashi, Yoshinao; Susa, Masahiro

    2017-11-01

    Ge2Sb2Te5 alloy has drawn much attention due to its application in phase-change random-access memory and potential as a thermoelectric material. Electrical and thermal conductivity are important material properties in both applications. The aim of this work is to investigate the temperature dependence of the electrical and thermal conductivity of Ge2Sb2Te5 alloy and discuss the thermal conduction mechanism. The electrical resistivity and thermal conductivity of Ge2Sb2Te5 alloy were measured from room temperature to 823 K by four-terminal and hot-strip method, respectively. With increasing temperature, the electrical resistivity increased while the thermal conductivity first decreased up to about 600 K then increased. The electronic component of the thermal conductivity was calculated from the Wiedemann-Franz law using the resistivity results. At room temperature, Ge2Sb2Te5 alloy has large electronic thermal conductivity and low lattice thermal conductivity. Bipolar diffusion contributes more to the thermal conductivity with increasing temperature. The special crystallographic structure of Ge2Sb2Te5 alloy accounts for the thermal conduction mechanism.

  20. Fluid Mechanics Optimising Organic Synthesis

    Science.gov (United States)

    Leivadarou, Evgenia; Dalziel, Stuart

    2015-11-01

    The Vortex Fluidic Device (VFD) is a new ``green'' approach in the synthesis of organic chemicals with many industrial applications in biodiesel generation, cosmetics, protein folding and pharmaceutical production. The VFD is a rapidly rotating tube that can operate with a jet feeding drops of liquid reactants to the base of the tube. The aim of this project is to explain the fluid mechanics of the VFD that influence the rate of reactions. The reaction rate is intimately related to the intense shearing that promotes collision between reactant molecules. In the VFD, the highest shears are found at the bottom of the tube in the Rayleigh and the Ekman layer and at the walls in the Stewardson layers. As a step towards optimising the performance of the VFD we present experiments conducted in order to establish the minimum drop volume and maximum rotation rate for maximum axisymmetric spreading without fingering instability. PhD candidate, Department of Applied Mathematics and Theoretical Physics.

  1. Fundamental Fluid Mechanics

    Indian Academy of Sciences (India)

    umes by P N Chatterjee contains standard material for a first level course in fluid me- chanics for Civil, Mechanical, Aeronautical and Chemical Engineering students. It is however not suitable for Applied Science students like those majoring in Physics or. Mathematics and is not a good reference book for practising ...

  2. Relativistic viscoelastic fluid mechanics.

    Science.gov (United States)

    Fukuma, Masafumi; Sakatani, Yuho

    2011-08-01

    A detailed study is carried out for the relativistic theory of viscoelasticity which was recently constructed on the basis of Onsager's linear nonequilibrium thermodynamics. After rederiving the theory using a local argument with the entropy current, we show that this theory universally reduces to the standard relativistic Navier-Stokes fluid mechanics in the long time limit. Since effects of elasticity are taken into account, the dynamics at short time scales is modified from that given by the Navier-Stokes equations, so that acausal problems intrinsic to relativistic Navier-Stokes fluids are significantly remedied. We in particular show that the wave equations for the propagation of disturbance around a hydrostatic equilibrium in Minkowski space-time become symmetric hyperbolic for some range of parameters, so that the model is free of acausality problems. This observation suggests that the relativistic viscoelastic model with such parameters can be regarded as a causal completion of relativistic Navier-Stokes fluid mechanics. By adjusting parameters to various values, this theory can treat a wide variety of materials including elastic materials, Maxwell materials, Kelvin-Voigt materials, and (a nonlinearly generalized version of) simplified Israel-Stewart fluids, and thus we expect the theory to be the most universal description of single-component relativistic continuum materials. We also show that the presence of strains and the corresponding change in temperature are naturally unified through the Tolman law in a generally covariant description of continuum mechanics.

  3. Incompressible ionized fluid mixtures

    Czech Academy of Sciences Publication Activity Database

    Roubíček, Tomáš

    2006-01-01

    Roč. 17, č. 7 (2006), s. 493-509 ISSN 0935-1175 Institutional research plan: CEZ:AV0Z10750506 Keywords : chemically reacting fluids * Navier-Stokes * Nernst-Planck * Possion equation s * heat equation s Subject RIV: BA - General Mathematics Impact factor: 0.954, year: 2006

  4. Bouncy Fluid Jets

    Science.gov (United States)

    Wadhwa, Navish; Jung, Sunghwan; Vlachos, Pavlos

    2012-11-01

    Contrary to intuition, free fluid jets can sometimes ``bounce'' off each other upon collision, due to an entrained air film that keeps them separated. So far, there have only been a few descriptive studies of bouncing jets, since the first recorded observation by Rayleigh more than a century ago. We present a quantitative investigation of non-coalescence in jets of same fluid upon an oblique collision. Using a simple experimental set-up, we carried out a parametric study of the bouncing jets by varying the jet diameter, velocity, angle of inclination and fluid viscosity. Our results reveal a scaling law for the contact time of bouncing jets. We further investigate the transition of colliding jets from non-coalescence to coalescence, which seems to be caused by instability of the fluid interface. A dimensionless parameter, which is a function of the Normal Weber Number, Normal Reynolds Number and the angle of inclination of the jets, quantitatively dictates the transition. Presently at Department of Physics, Danish Technical University, Denmark.

  5. Relativistic viscoelastic fluid mechanics

    International Nuclear Information System (INIS)

    Fukuma, Masafumi; Sakatani, Yuho

    2011-01-01

    A detailed study is carried out for the relativistic theory of viscoelasticity which was recently constructed on the basis of Onsager's linear nonequilibrium thermodynamics. After rederiving the theory using a local argument with the entropy current, we show that this theory universally reduces to the standard relativistic Navier-Stokes fluid mechanics in the long time limit. Since effects of elasticity are taken into account, the dynamics at short time scales is modified from that given by the Navier-Stokes equations, so that acausal problems intrinsic to relativistic Navier-Stokes fluids are significantly remedied. We in particular show that the wave equations for the propagation of disturbance around a hydrostatic equilibrium in Minkowski space-time become symmetric hyperbolic for some range of parameters, so that the model is free of acausality problems. This observation suggests that the relativistic viscoelastic model with such parameters can be regarded as a causal completion of relativistic Navier-Stokes fluid mechanics. By adjusting parameters to various values, this theory can treat a wide variety of materials including elastic materials, Maxwell materials, Kelvin-Voigt materials, and (a nonlinearly generalized version of) simplified Israel-Stewart fluids, and thus we expect the theory to be the most universal description of single-component relativistic continuum materials. We also show that the presence of strains and the corresponding change in temperature are naturally unified through the Tolman law in a generally covariant description of continuum mechanics.

  6. Cryogenic Fluid Management Facility

    Science.gov (United States)

    Eberhardt, R. N.; Bailey, W. J.

    1985-01-01

    The Cryogenic Fluid Management Facility is a reusable test bed which is designed to be carried within the Shuttle cargo bay to investigate the systems and technologies associated with the efficient management of cryogens in space. Cryogenic fluid management consists of the systems and technologies for: (1) liquid storage and supply, including capillary acquisition/expulsion systems which provide single-phase liquid to the user system, (2) both passive and active thermal control systems, and (3) fluid transfer/resupply systems, including transfer lines and receiver tanks. The facility contains a storage and supply tank, a transfer line and a receiver tank, configured to provide low-g verification of fluid and thermal models of cryogenic storage and transfer processes. The facility will provide design data and criteria for future subcritical cryogenic storage and transfer system applications, such as Space Station life support, attitude control, power and fuel depot supply, resupply tankers, external tank (ET) propellant scavenging, and ground-based and space-based orbit transfer vehicles (OTV).

  7. Fluids in metamorphic rocks

    NARCIS (Netherlands)

    Touret, J.L.R.

    2001-01-01

    Basic principles for the study of fluid inclusions in metamorphic rocks are reviewed and illustrated. A major problem relates to the number of inclusions, possibly formed on a wide range of P-T conditions, having also suffered, in most cases, extensive changes after initial trapping. The

  8. Charged fluids with symmetries

    Indian Academy of Sciences (India)

    metric tensor field and generate constants of the motion along null geodesics for massless particles. Conformal symmetries arise in various physical applications. The existence of conformal symmetries in relativistic cosmological models, with restrictions on the matter content and fluid four-velocity, have been extensively ...

  9. Heuristic optimality criterion algorithm for shape design of fluid flow

    Science.gov (United States)

    Wang, Limin; Fan, Yilin; Luo, Lingai

    2010-10-01

    This paper presents a heuristic optimality criterion algorithm for shape design of fluid flow. In this algorithm, the lattice Boltzmann method (LBM) is utilized to calculate the flow field of a fluid domain which is divided into elemental cells. A heuristic optimality criterion is applied for cells at the solid-fluid interface, i.e. the dynamic pressure for fluid cells and the viscous stress on their neighboring solid cells. An automatic program is processed step by step to exchange the positions of solid and fluid cells identified by the optimality criterion, with the objective of decreasing the flow resistance at the constraint of constant fluid volume. To illustrate the procedure of this algorithm for shape design of fluid flow, two simple examples are presented: one with fluid flowing through a right angle elbow and the other through a converging T-junction. Numerical results show that this algorithm can successfully reduce the total pressure drop of the system, demonstrating its potential applications in engineering optimal design.

  10. Materials and methods for autonomous restoration of electrical conductivity

    Science.gov (United States)

    Blaiszik, Benjamin J; Odom, Susan A; Caruso, Mary M; Jackson, Aaron C; Baginska, Marta B; Ritchey, Joshua A; Finke, Aaron D; White, Scott R; Moore, Jeffrey S; Sottos, Nancy R; Braun, Paul V; Amine, Khalil

    2014-03-25

    An autonomic conductivity restoration system includes a solid conductor and a plurality of particles. The particles include a conductive fluid, a plurality of conductive microparticles, and/or a conductive material forming agent. The solid conductor has a first end, a second end, and a first conductivity between the first and second ends. When a crack forms between the first and second ends of the conductor, the contents of at least a portion of the particles are released into the crack. The cracked conductor and the released contents of the particles form a restored conductor having a second conductivity, which may be at least 90% of the first conductivity.

  11. Exploration of Fluid Dynamics in Perioperative Patients Using Bioimpedance Analysis.

    Science.gov (United States)

    Chong, Jae Uk; Nam, Sangguen; Kim, Hee Jung; Lee, Rami; Choi, Yunjung; Lee, Jae Gil; Kim, Kyung Sik

    2016-05-01

    Perioperative fluid restriction is advocated to reduce complications after major surgeries. Current methods of monitoring body fluids rely on indirect volume markers that may at times be inadequate. In our study, bioimpedance analysis (BIA) was used to explore fluid dynamics, in terms of intercompartmental shift, of perioperative patients undergoing operation for hepato-pancreato-biliary (HPB) diseases. A retrospective review was conducted, examining 36 patients surgically treated for HPB diseases between March 2010 and August 2012. Body fluid compartments were estimated via BIA at baseline (1 day prior to surgery), immediately after surgery, and on postoperative day 1, recording fluid balance during and after procedures. Patients were stratified by net fluid status as balanced (≤500 mL) or imbalanced (>550 mL) and outcomes of BIA compared. Mean net fluid balance volumes in balanced (n = 16) and imbalanced (n = 20) patient subsets were 231.41 ± 155.44 and 1050.18 ± 548.77 mL, respectively. Total body water (TBW) (p = 0.091), extracellular water (ECW) (p = 0.125), ECW/TBW (p = 0.740), and intracellular water (ICW) (p = 0.173) did not fluctuate significantly in fluid-balanced patients. Although TBW (p = 0.069) in fluid-imbalanced patients did not change significantly (relative to baseline), ECW (p = 0.001), ECW/TBW (p = 0.019), and ICW (p = 0.012) showed significant postoperative increases. The exploration of fluid dynamics using BIA has shown importance of balanced fluid management during perioperative period. Increased ECW/TBW in fluid-imbalanced patients suggests possible causality for the development of ascites or fluid collections during postoperative period in patients undergoing HPB operations.

  12. Cu/Zn Thermal Conductivity: Experimental And ANFIS Modelling

    Directory of Open Access Journals (Sweden)

    Zaid S. Kareem

    2018-01-01

    Full Text Available Nanofluids are fluids within which particles of nanometre sizes are suspended. In terms of thermal characteristics, nanofluids have a greater heat transfer coefficient and thermal conductivity than other traditional fluids. Bimetallic core/shell Cu/Zn particles of nanometre sizes are novel invented nanoparticle materials with considerable variations in its applications. The particles of nanometre size were suspended in a base fluid for the preparation of nanofluids for different volume fractions. A coated transitory hot wire device were built and standardized and this was subsequently employed for the determination of heat conductivities of the nanofluids for bimetallic ratios, volume fraction, base fluid temperatures and base fluids thermal conductivity. The Adaptive neuro fuzzy inference system (ANFIS model was subsequently employed for modelling the determined results generated. A random test of 20% from various nanofluids showed a deviation less than 1% between measured and modeled results. It was inferred that heat conductivities increase with increase in the particle volume concentrations, especially when the later one at value of 1, the heat conductivities ratio approach to 1.35. Nevertheless, the shape and the method of preparing the particles of nanometre size reveals anomalous enhancements in heat conductivities of bimetallic compared to monocular metallic nanofluids.

  13. Regional two-dimensional magnetotelluric profile in West Bohemia/Vogtland reveals deep conductive channel into the earthquake swarm region

    Science.gov (United States)

    Muñoz, Gerard; Weckmann, Ute; Pek, Josef; Kováčiková, Světlana; Klanica, Radek

    2018-03-01

    The West Bohemia/Vogtland region, characterized by the intersection of the Eger (Ohře) Rift and the Mariánské Lázně fault, is a geodynamically active area exhibiting repeated occurrence of earthquake swarms, massive CO2 emanations and mid Pleistocene volcanism. The Eger Rift is the only known intra-continental region in Europe where such deep seated, active lithospheric processes currently take place. We present an image of electrical resistivity obtained from two-dimensional inversion of magnetotelluric (MT) data acquired along a regional profile crossing the Eger Rift. At the near surface, the Cheb basin and the aquifer feeding the mofette fields of Bublák and Hartoušov have been imaged as part of a region of very low resistivity. The most striking resistivity feature, however, is a deep reaching conductive channel which extends from the surface into the lower crust spatially correlated with the hypocentres of the seismic events of the Nový Kostel Focal Zone. This channel has been interpreted as imaging a pathway from a possible mid-crustal fluid reservoir to the surface. The resistivity model reinforces the relation between the fluid circulation along deep-reaching faults and the generation of the earthquakes. Additionally, a further conductive channel has been revealed to the south of the profile. This other feature could be associated to fossil hydrothermal alteration related to Mýtina and/or Neualbenreuth Maar structures or alternatively could be the signature of a structure associated to the suture between the Saxo-Thuringian and Teplá-Barrandian zones, whose surface expression is located only a few kilometres away.

  14. Electrical Conduction and Superconductivity

    Indian Academy of Sciences (India)

    Superconductivity, the awe-inspiring word came into existence when KamerIingh Onnes (Box 1) discovered a new phenom- enon in 1911. When he cooled a sample of liquid metal mercury, it lost its electrical resistance at temperatures close to 0 K. Years of careful experimentation at Leiden preceded his success in the.

  15. Variation of thermal conductivity of DPPC lipid bilayer membranes around the phase transition temperature.

    Science.gov (United States)

    Youssefian, Sina; Rahbar, Nima; Lambert, Christopher R; Van Dessel, Steven

    2017-05-01

    Given their amphiphilic nature and chemical structure, phospholipids exhibit a strong thermotropic and lyotropic phase behaviour in an aqueous environment. Around the phase transition temperature, phospholipids transform from a gel-like state to a fluid crystalline structure. In this transition, many key characteristics of the lipid bilayers such as structure and thermal properties alter. In this study, we employed atomistic simulation techniques to study the structure and underlying mechanisms of heat transfer in dipalmitoylphosphatidylcholine (DPPC) lipid bilayers around the fluid-gel phase transformation. To investigate this phenomenon, we performed non-equilibrium molecular dynamics simulations for a range of different temperature gradients. The results show that the thermal properties of the DPPC bilayer are highly dependent on the temperature gradient. Higher temperature gradients cause an increase in the thermal conductivity of the DPPC lipid bilayer. We also found that the thermal conductivity of DPPC is lowest at the transition temperature whereby one lipid leaflet is in the gel phase and the other is in the liquid crystalline phase. This is essentially related to a growth in thermal resistance between the two leaflets of lipid at the transition temperature. These results provide significant new insights into developing new thermal insulation for engineering applications. © 2017 The Authors.

  16. A new converter for improving efficiency of multi-actuators fluid power system

    Energy Technology Data Exchange (ETDEWEB)

    Xue, Yong; Shang, JianZhong; Yang, JunHong; Wang Zhuo [National University of Defense Technology, Changsha (China)

    2016-05-15

    This paper is concerned with the application of energy efficient fluid power in mobile robots system and proposes a new fluid power converter system which is analogous to a boost converter in power electronics. The fluid power converter system is based on the principle of pulse-width modulation. The fluid power converter has an effect akin to an electrical switched inductance transformer, wherein the output pressure or flow rate can be stepped up or down. Using an inductive reactance device (an inertia mass-block), the output flow and pressure can be varied to meet the load by a means that does not rely on dissipation of power (the resistance control). The simulation model based on the mathematics models of the components is built to analyse the performance of the fluid power converter. It is clearly shown that the fluid power converter has higher energy efficiency than conventional resistance control manners.

  17. Assessment of pollution near landfill site in Nagpur, India by resistivity imaging and GPR.

    Science.gov (United States)

    Pujari, Paras R; Pardhi, Pawan; Muduli, Pradipta; Harkare, Prajakta; Nanoti, Madan V

    2007-08-01

    Groundwater pollution in the vicinity of a landfill site in Nagpur, India is assessed with the help of resistivity imaging and GPR tools. The resistivity imaging survey indicates high conductive anomalies in the topsoil as well as the underlying fractured rocks. Significant reflections from the GPR records known as radargrams are extracted with the help of maximum peak module and Hilbert transform module in RADAN 6. These reflections can be attributed to presence of fractures, which are potential pathways for migration of the fluid. The geophysical findings are strengthened by the results of groundwater analysis from wells located close to the profile where resistivity and GPR survey have been carried out. The study has indicated the vulnerability of the unconfined aquifer underlying the predominantly clay layer.

  18. Further elucidation of nanofluid thermal conductivity measurement using a transient hot-wire method apparatus

    Science.gov (United States)

    Yoo, Donghoon; Lee, Joohyun; Lee, Byeongchan; Kwon, Suyong; Koo, Junemo

    2018-02-01

    The Transient Hot-Wire Method (THWM) was developed to measure the absolute thermal conductivity of gases, liquids, melts, and solids with low uncertainty. The majority of nanofluid researchers used THWM to measure the thermal conductivity of test fluids. Several reasons have been suggested for the discrepancies in these types of measurements, including nanofluid generation, nanofluid stability, and measurement challenges. The details of the transient hot-wire method such as the test cell size, the temperature coefficient of resistance (TCR) and the sampling number are further investigated to improve the accuracy and consistency of the measurements of different researchers. It was observed that smaller test apparatuses were better because they can delay the onset of natural convection. TCR values of a coated platinum wire were measured and statistically analyzed to reduce the uncertainty in thermal conductivity measurements. For validation, ethylene glycol (EG) and water thermal conductivity were measured and analyzed in the temperature range between 280 and 310 K. Furthermore, a detailed statistical analysis was conducted for such measurements, and the results confirmed the minimum number of samples required to achieve the desired resolution and precision of the measurements. It is further proposed that researchers fully report the information related to their measurements to validate the measurements and to avoid future inconsistent nanofluid data.

  19. Universality of DC electrical conductivity from holography

    Energy Technology Data Exchange (ETDEWEB)

    Ge, Xian-Hui, E-mail: gexh@shu.edu.cn [Shanghai Key Laboratory of High Temperature Superconductors, Department of Physics, Shanghai University, Shanghai, 200444 (China); Department of Physics, University of California, San Diego, CA92122 (United States); Sin, Sang-Jin, E-mail: sjsin@hangyang.ac.kr [Department of Physics, Hanyang University, Seoul 133-791 (Korea, Republic of); Wu, Shao-Feng, E-mail: sfwu@shu.edu.cn [Department of Physics, Shanghai University, Shanghai, 200444 (China)

    2017-04-10

    We propose a universal formula of dc electrical conductivity in rotational- and translational-symmetries breaking systems via the holographic duality. This formula states that the ratio of the determinant of the dc electrical conductivities along any spatial directions to the black hole area density in zero-charge limit has a universal value. As explicit illustrations, we give several examples elucidating the validation of this formula: We construct an anisotropic black brane solution, which yields linear in temperature for the in-plane resistivity and insulating behavior for the out-of-plane resistivity; We also construct a spatially isotropic black brane solution that both the linear-T and quadratic-T contributions to the resistivity can be realized.

  20. Long-term dipole-dipole resistivity monitoring at the Cerro Prieto geothermal field

    Energy Technology Data Exchange (ETDEWEB)

    Wilt, M.; Goldstein, N.E.; Sasaki, Y.

    1984-04-01

    Dipole-dipole resistivity measurements for the combined purposes of reservoir delineation and reservoir monitoring were first made at Cerro Prieto in 1978 and have continued on approximately an annual basis since then. Two 20 km-long dipole-dipole lines with permanently emplaced electrodes at 1-km spacings were established over the field area. Resistivity remeasurements have been made on one line at 6- to 18-month intervals using a 25 kW generator capable of up to 80A output and a microprocessor-controlled signal-averaging receiver. This high-power, low-noise system provides highly accurate measurements even at large transmitter receiver separations. Standard error calculations for collected data indicate errors less than 5% for all points. Results from four years of monitoring (1979-1983) indicate a 5% average annual increase in apparent resistivity over the present production area, and larger decreases in apparent resistivity in the region to the east. The increase in resistivity in the production zone is most likely due to dilution of reservoir fluids with fresher water, as evidenced by a drop in chloride content of produced waters. The area of decreasing resistivity east of the reservoir is associated with a steeply dipping conductive body, a zone of higher thermal gradients and an increase in shale thickness in the section. Decreasing resistivity in this area may be caused by an influx of high temperature, saline water from depths of 3/sup +/ km through a sandy gap in the shales.