WorldWideScience

Sample records for volume electrical resistivity

  1. Novel experimental design for high pressure-high temperature electrical resistance measurements in a "Paris-Edinburgh" large volume press

    Science.gov (United States)

    Matityahu, Shlomi; Emuna, Moran; Yahel, Eyal; Makov, Guy; Greenberg, Yaron

    2015-04-01

    We present a novel experimental design for high sensitivity measurements of the electrical resistance of samples at high pressures (0-6 GPa) and high temperatures (300-1000 K) in a "Paris-Edinburgh" type large volume press. Uniquely, the electrical measurements are carried out directly on a small sample, thus greatly increasing the sensitivity of the measurement. The sensitivity to even minor changes in electrical resistance can be used to clearly identify phase transitions in material samples. Electrical resistance measurements are relatively simple and rapid to execute and the efficacy of the present experimental design is demonstrated by measuring the electrical resistance of Pb, Sn, and Bi across a wide domain of temperature-pressure phase space and employing it to identify the loci of phase transitions. Based on these results, the phase diagrams of these elements are reconstructed to high accuracy and found to be in excellent agreement with previous studies. In particular, by mapping the locations of several well-studied reference points in the phase diagram of Sn and Bi, it is demonstrated that a standard calibration exists for the temperature and pressure, thus eliminating the need for direct or indirect temperature and pressure measurements. The present technique will allow simple and accurate mapping of phase diagrams under extreme conditions and may be of particular importance in advancing studies of liquid state anomalies.

  2. Quality control based on electrical resistivity measurements

    OpenAIRE

    Ferreira, Rui Miguel; Jalali, Said

    2006-01-01

    The electrical resistivity of concrete is one of the main parameters controlling the initiation and propagation of reinforcement corrosion. It is common knowledge that concrete electrical resistivity is mainly dependent on the w/c ratio (pore connectivity), volume and type of cement, temperature and the moisture. This research work studies the effect of specimen shape and temperature of measurement on electrical resistivity measurements of concrete using the four-point Werner electrode. In ad...

  3. Imaging water velocity and volume fraction distributions in water continuous multiphase flows using inductive flow tomography and electrical resistance tomography

    Science.gov (United States)

    Meng, Yiqing; Lucas, Gary P.

    2017-05-01

    This paper presents the design and implementation of an inductive flow tomography (IFT) system, employing a multi-electrode electromagnetic flow meter (EMFM) and novel reconstruction techniques, for measuring the local water velocity distribution in water continuous single and multiphase flows. A series of experiments were carried out in vertical-upward and upward-inclined single phase water flows and ‘water continuous’ gas-water and oil-gas-water flows in which the velocity profiles ranged from axisymmetric (single phase and vertical-upward multiphase flows) to highly asymmetric (upward-inclined multiphase flows). Using potential difference measurements obtained from the electrode array of the EMFM, local axial velocity distributions of the continuous water phase were reconstructed using two different IFT reconstruction algorithms denoted RT#1, which assumes that the overall water velocity profile comprises the sum of a series of polynomial velocity components, and RT#2, which is similar to RT#1 but which assumes that the zero’th order velocity component may be replaced by an axisymmetric ‘power law’ velocity distribution. During each experiment, measurement of the local water volume fraction distribution was also made using the well-established technique of electrical resistance tomography (ERT). By integrating the product of the local axial water velocity and the local water volume fraction in the cross section an estimate of the water volumetric flow rate was made which was compared with a reference measurement of the water volumetric flow rate. In vertical upward flows RT#2 was found to give rise to water velocity profiles which are consistent with the previous literature although the profiles obtained in the multiphase flows had relatively higher central velocity peaks than was observed for the single phase profiles. This observation was almost certainly a result of the transfer of axial momentum from the less dense dispersed phases to the water

  4. Electrical Resistivity Measurements: a Review

    Science.gov (United States)

    Singh, Yadunath

    World-wide interest on the use of ceramic materials for aerospace and other advanced engineering applications, has led to the need for inspection techniques capable of detecting unusually electrical and thermal anomalies in these compounds. Modern ceramic materials offer many attractive physical, electrical and mechanical properties for a wide and rapidly growing range of industrial applications; moreover specific use may be made of their electrical resistance, chemical resistance, and thermal barrier properties. In this review, we report the development and various techniques for the resistivity measurement of solid kind of samples.

  5. Electric power annual 1997. Volume 1

    Energy Technology Data Exchange (ETDEWEB)

    NONE

    1998-07-01

    The Electric Power Annual presents a summary of electric power industry statistics at national, regional, and State levels. The objective of the publication is to provide industry decisionmakers, government policy-makers, analysts, and the general public with data that may be used in understanding US electricity markets. The Electric Power Annual is prepared by the Electric Power Division; Office of Coal, Nuclear, Electric and Alternate Fuels; Energy Information Administration (EIA); US Department of Energy. Volume 1 -- with a focus on US electric utilities -- contains final 1997 data on net generation and fossil fuel consumption, stocks, receipts, and cost; preliminary 1997 data on generating unit capability, and retail sales of electricity, associated revenue, and the average revenue per kilowatthour of electricity sold (based on a monthly sample: Form EIA-826, ``Monthly Electric Utility Sales and Revenue Report with State Distributions``). Additionally, information on net generation from renewable energy sources and on the associated generating capability is included in Volume 1 of the EPA.

  6. Estimating soil suction from electrical resistivity

    Science.gov (United States)

    Piegari, E.; Di Maio, R.

    2013-09-01

    Soil suction and resistivity strongly depend on the degree of soil saturation and, therefore, both are used for estimating water content variations. The main difference between them is that soil suction is measured using tensiometers, which give point information, while resistivity is obtained by tomography surveys, which provide distributions of resistivity values in large volumes, although with less accuracy. In this paper, we have related soil suction to electrical resistivity with the aim of obtaining information about soil suction changes in large volumes, and not only for small areas around soil suction probes. We derived analytical relationships between soil matric suction and electrical resistivity by combining the empirical laws of van Genuchten and Archie. The obtained relationships were used to evaluate maps of soil suction values in different ashy layers originating in the explosive activity of the Mt Somma-Vesuvius volcano (southern Italy). Our findings provided a further example of the high potential of geophysical methods in contributing to more effective monitoring of soil stress conditions; this is of primary importance in areas where rainfall-induced landslides occur periodically.

  7. Electric power annual 1996. Volume 1

    Energy Technology Data Exchange (ETDEWEB)

    NONE

    1997-08-01

    The Electric Power Annual presents a summary of electric power industry statistics at national, regional, and State levels. The objective of the publication is to provide industry decisionmakers, government policy-makers, analysts, and the general public with data that may be used in understanding US electricity markets. The Electric Power Annual is prepared by the Coal and Electric Data and Renewables Division; Office of Coal, Nuclear, Electric and Alternate Fuels; Energy Information Administration (EIA); US Department of Energy. Volume 1--with a focus on US electric utilities--contains final 1996 data on net generation and fossil fuel consumption, stocks, receipts, and cost; preliminary 1996 data on generating unit capability, and retail sales of electricity, associated revenue, and the average revenue per kilowatthour of electricity sold. Additionally, information on net generation from renewable energy sources and on the associated generating capability is included in Volume 1 of the EPA. Data published in the Electric Power Annual Volume 1 are compiled from three statistical forms filed monthly and two forms filed annually by electric utilities. These forms are described in detail in the Technical Notes. 5 figs., 30 tabs.

  8. Electrical resistance tomography for imaging concrete structures

    Energy Technology Data Exchange (ETDEWEB)

    Buettner, M.; Ramirez, A.; Daily, W.

    1995-11-08

    Electrical Resistance Tomography (ERT) has been used to non-destructively examine the interior of reinforced concrete pillars in the laboratory during a water infiltration experiment. ERT is a technique for determining the electrical resistivity distribution within a volume from measurement of injected currents and the resulting electrical potential distribution on the surface. The transfer resistance (ratio of potential to injected current) data are inverted using an algorithm based on a finite element forward solution which is iteratively adjusted in a least squares sense until the measured and calculated transfer resistances agree to within some predetermined value. Laboratory specimens of concrete pillars, 61.0 cm (24 in) in length and 20.3 cm (8 in) on a side, were prepared with various combinations of steel reinforcing bars and voids (1.27 cm diameter) which ran along the length of the pillars. An array of electrodes was placed around the pillar to allow for injecting current and measuring the resulting potentials. After the baseline resistivity distribution was determined, water was added to a void near one comer of the pillar. ERT was used to determine the resistivity distribution of the pillar at regular time intervals as water was added. The ERT images show very clearly that the water was gradually imbibed into the concrete pillar during the course of the experiment. The resistivity decreased by nearly an order of magnitude near the point of water addition in the first hour, and by nearly two orders of magnitude by the end of the experiment. Other applications for this technology include monitoring of curing in concrete structures, detecting cracks in concrete structures, detecting rebar location and corrosion state, monitoring slope stability and the stability of footings, detecting and monitoring leaks from storage tanks, monitoring thermal processes during environmental remediation, and for detecting and monitoring contaminants in soil and groundwater.

  9. Electric power annual 1997. Volume 2

    Energy Technology Data Exchange (ETDEWEB)

    NONE

    1998-10-01

    The Electric Power Annual 1997, Volume 2 contains annual summary statistics at national, regional, and state levels for the electric power industry, including information on both electric utilities and nonutility power producers. Included are data for electric utility retail sales of electricity, associated revenue, and average revenue per kilowatthour of electricity sold; financial statistics; environmental statistics; power transactions; and demand-side management. Also included are data for US nonutility power producers on installed capacity; gross generation; emissions; and supply and disposition of energy. The objective of the publication is to provide industry decisionmakers, government policymakers, analysts, and the general public with historical data that may be used in understanding US electricity markets. 15 figs., 62 tabs.

  10. Determining the specific electric resistance of rock

    Energy Technology Data Exchange (ETDEWEB)

    Persad' ko, V.Ia.

    1982-01-01

    Data are presented on perfecting the method of laboratory determination of the specific electric resistance of a rock formation. The average error in determining the specific electric resistance of the core at various locations is no more than two percent with low resistance values (2-5 ohms).

  11. The electrical resistivity method in cased boreholes

    Energy Technology Data Exchange (ETDEWEB)

    Schenkel, C.J.

    1991-05-01

    The use of downhole current sources in resistivity mapping can greatly enhance the detection and delineation of subsurface features. The purpose of this work is to examine the resistivity method for current sources in wells cased with steel. The resistivity method in cased boreholes with downhole current sources is investigated using the integral equation (IE) technique. The casing and other bodies are characterized as conductivity inhomogeneities in a half-space. For sources located along the casing axis, an axially symmetric Green's function is used to formulate the surface potential and electric field (E-field) volume integral equations. The situations involving off-axis current sources and three-dimensional (3-D) bodies is formulated using the surface potential IE method. The solution of the 3-D Green's function is presented in cylindrical and Cartesian coordinate systems. The methods of moments is used to solve the Fredholm integral equation of the second kind for the response due to the casing and other bodies. The numerical analysis revealed that the current in the casing can be approximated by its vertical component except near the source and the axial symmetric approximation of the casing is valid even for the 3-D problem. The E-field volume IE method is an effective and efficient technique to simulate the response of the casing in a half-space, whereas the surface potential approach is computationally better when multiple bodies are involved. Analyzing several configurations of the current source indicated that the casing response is influenced by four characteristic factors: conduction length, current source depth,casing depth, and casing length. 85 refs., 133 figs., 11 tabs.

  12. Electric power annual 1998. Volume 1

    Energy Technology Data Exchange (ETDEWEB)

    NONE

    1999-04-01

    The purpose of this report, Electric Power Annual 1998 Volume 1 (EPAVI), is to provide a comprehensive overview of the electric power industry during the most recent year for which data have been collected, with an emphasis on the major changes that occurred. In response to the changes of 1998, this report has been expanded in scope. It begins with a general review of the year and incorporates new data on nonutility capacity and generation, transmission information, futures prices from the Commodity futures Trading commission, and wholesale spot market prices from the pennsylvania-new Jersey-Maryland Independent System Operator and the California Power Exchange. Electric utility statistics at the Census division and State levels on generation, fuel consumption, stocks, delivered cost of fossil fuels, sales to ultimate customers, average revenue per kilowatthour of electricity sold, and revenues from those retail sales can be found in Appendix A. The EPAVI is intended for a wide audience, including Congress, Federal and State agencies, the electric power industry, and the general public.

  13. Coke fouling monitoring by electrical resistivity

    Energy Technology Data Exchange (ETDEWEB)

    Bombardelli, Clovis; Mari, Livia Assis; Kalinowski, Hypolito Jose [Universidade Tecnologica Federal do Parana (UTFPR), Curitiba, PR (Brazil). Programa de Pos-Graduacao em Engenharia Eletrica e Informatica Industrial (CPGEI)

    2008-07-01

    An experimental method to simulate the growth of the coke fouling that occurs in the oil processing is proposed relating the thickness of the encrusted coke to its electrical resistivity. The authors suggest the use of the fouling electrical resistivity as a transducer element for determining its thickness. The sensor is basically two electrodes in an electrically isolated device where the inlay can happen in order to compose a purely resistive transducer. Such devices can be easily constructed in a simple and robust form with features capable to face the high temperatures and pressures found in relevant industrial processes. For validation, however, it is needed a relationship between the electrical resistivity and the fouling thickness, information not yet found in the literature. The present work experimentally simulates the growth of a layer of coke on an electrically insulating surface, equipped with electrodes at two extremities to measure the electrical resistivity during thermal cracking essays. The method is realized with a series of consecutive runs. The results correlate the mass of coke deposited and its electrical resistivity, and it can be used to validate the coke depositions monitoring employing the resistivity as a control parameter. (author)

  14. Observations on the electrical resistivity of steel fibre reinforced concrete

    DEFF Research Database (Denmark)

    Solgaard, Anders Ole Stubbe; Geiker, Mette Rica; Edvardsen, Carola;

    2014-01-01

    Steel fibre reinforced concrete (SFRC) is in many ways a well-known construction material, and its use has gradually increased over the last decades. The mechanical properties of SFRC are well described based on the theories of fracture mechanics. However, knowledge on other material properties......, including the electrical resistivity, is sparse. Among others, the electrical resistivity of concrete has an effect on the corrosion process of possible embedded bar reinforcement and transfer of stray current. The present paper provides experimental results concerning the influence of the fibre volume...

  15. Geological and Electrical Resistivity Sounding of Olokonla Area in ...

    African Journals Online (AJOL)

    Akorede

    polygon was also constructed based on the radial electrical sounding. The geoelectric ... KEYWORDS: Vertical electrical sounding, aquifer, electrical resistivity, anisotropy polygon, geological mapping, fracture pattern .... Introduction to.

  16. Finite element modeling for volume phantom in Electrical Impedance Tomography

    Directory of Open Access Journals (Sweden)

    I. O. Rybina

    2011-10-01

    Full Text Available Using surface phantom, "shadows" of currents, which flow below and under surface tomographic lays, include on this lay, that is cause of adding errors in reconstruction image. For processing modeling in studied object volume isotropic finite elements should be used. Cube is chosen for finite element modeling in this work. Cube is modeled as sum of six rectangular (in the base pyramids, each pyramid consists of four triangular pyramids (with rectangular triangle in the base and hypotenuse, which is equal to cube rib to provide its uniformity and electrical definition. In the case of modeling on frequencies higher than 100 kHz biological tissue resistivities are complex. In this case weight coefficient k will be complex in received cube electrical model (inverse conductivity matrix of the cube finite element.

  17. System for measuring electric resistance skin

    Directory of Open Access Journals (Sweden)

    V. P. Kutsenko

    2015-09-01

    Full Text Available Introduction. To measure the electrical resistance of leather frequently used system for applying testing signals from external current sources or voltage. Power testing signals the maximum limit, when they Electro studies still have a negative impact on the human body. Formulation of the problem. To achieve this task the authors conducted research and developed a system, which is based to measure electrical skin resistance (ESR responsible allocation and measurement noise variance bioelectric signal is proportional to the resistance area of research. Main body. The paper studied and developed a system, based on measuring electrical skin resistance on the identification and measurement of the noise variance from the BAP bioelectric signal that is proportional to the resistance of the investigation. A functional block diagram of an automated algorithm for converting the useful and noise signal BAP, whose range does not differ fundamentally from those of the intrinsic noise of the input elements in ESR. The proposed method will improve the accuracy of the measurements ESR without the use of test pacing signal. The simulation results and experimental studies correlate that confirms the adequacy of this method the results of experimental measurements. Conclusions. For noise voltage BAT can measure their electrical resistance without signals tested, external sources of electric current or voltage and thereby completely eliminate the harmful effect of probing. Thanks to one of the Inverting periodic noise voltages multiplied and simultaneous detection variable component switching frequency, provided the allocation and measurement noise voltage acupuncture points, which is proportional to the resistance, and the intensity of the same order or less than the intrinsic noise of the measuring system. Use as medical acupuncture needle electrodes allows to measure not only the skin but also deep resistivity, which reflects the physiological state of internal

  18. Electric Power annual 1996: Volume II

    Energy Technology Data Exchange (ETDEWEB)

    NONE

    1997-12-01

    This document presents a summary of electric power industry statistics. Data are included on electric utility retail sales of electricity, revenues, environmental information, power transactions, emissions, and demand-side management.

  19. Electric power annual 1994. Volume 2, Operational and financial data

    Energy Technology Data Exchange (ETDEWEB)

    NONE

    1995-11-28

    This year, the annual is published in two volumes. Volume I focused on US electric utilities and contained final 1994 data on net generation, fossil fuel consumption, stocks, receipts, and cost. This Volume II presents annual 1994 summary statistics for the electric power industry, including information on both electric utilities and nonutility power producers. Included are preliminary data for electric utility retail sales of electricity, associated revenue, and average revenue per kilowatthour of electricity sold (based on form EIA-861) and for electric utility financial statistics, environmental statistics, power transactions, and demand- side management. Final 1994 data for US nonutility power producers on installed capacity and gross generation, as well as supply and disposition information, are also provided in Volume II. Technical notes and a glossary are included.

  20. Electrical resistivity of thin bismuth films

    Science.gov (United States)

    Kumar, A.; Katyal, O. P.

    1990-05-01

    The effect of the film thickness of a bismuth film deposited on glass substrate on its electrical resistivity was investigated for films from 41 to 225 nm thickness, in the temperature range 77-350 K. Results show that the electrical resistivity decreases with increasing temperature and that, for films 98.3 and 225.9 nm thick there exists a minimum (between 260 and 350 K) in resistivity at some temperature, Tc. This minimum shifts toward higher temperature for thinner samples, and lies above 350 K. The thickness dependence of the bismuth film resistivity, obtained at 77, 150, and 300 K, can be explained by a modified Fuchs model, which takes into account the thickness dependence of carrier density.

  1. Invariant electrical resistivity of Co along the melting boundary

    Science.gov (United States)

    Ezenwa, Innocent C.; Secco, Richard A.

    2017-09-01

    The Earth's core is comprised mainly of Fe and Ni with some light alloying element(s) and the electrical resistivity behavior of these elements is an important property for characterizing geodynamo action, determining energy sources, and for understanding core thermal evolution. Knowledge of the electrical resistivity of solid and liquid transition metals with electronic structures similar to Fe reinforces our understanding of core properties. The electrical resistivity of high purity Co has been measured at pressures up to 5 GPa in a large volume press and at temperatures up to 100 K above the melting temperature. The results demonstrate that resistivity of Co is invariant along the melting boundary. This is interpreted in terms of the antagonistic effects of P-induced reduction in the amplitude of lattice vibrations tending to decrease resistivity, and the P-induced shift of the Fermi level closer to the d-resonance which tends to increase resistivity. We calculated the electronic thermal conductivity of Co using the Wiedemann-Franz law and show that it increases with pressure both in the solid and liquid states and decreases with temperature in the solid and increases in the liquid state. The pressure dependences of electrical resistivity and electronic thermal conductivity calculated from equations involving bulk modulus and the Gruneisen parameter are in reasonable agreement with values measured in this study. The constant resistivity of Co along its melting boundary found in our study portends similar behavior for its electronic structural analog, Fe. This prediction suggests that the electronic thermal conductivity of Fe at Earth's inner core boundary could be similar to its 1 atm value at the melting point. Using this value of thermal conductivity for the inner core boundary would admit thermal convection as an energy source for the geodynamo prior to the birth of the inner core.

  2. Electrical resistivity and phase transformation in steels

    Energy Technology Data Exchange (ETDEWEB)

    Mohanty, O.N.; Bhagat, A.N. [Tata Iron and Steel Company Limited, Jamshedpur (India)

    2003-01-01

    Changes in electrical resistance accompanying transformations in steels with magnetic change (e.g. {gamma} {yields} martensite/bainite) and without magnetic change (e.g. {gamma} {yields} {alpha}, above Curie temperature) have been examined; the former class affects the resistivity the latter does not. Next, while the efficacy of electrical resistivity measurement in capturing the well-known features of austenite stabilization (e.g. over - ageing, reversibility, and influence of prior martensite amount and so on) in high carbon steels has been reported in an earlier publication, new features (e.g. increase in resistance -increase at very low temperatures, change in temperature co-efficient of resistivity in the stabilized material etc.) are highlighted here. Finally, the work shows that a quantitative estimate of precipitation in the copper bearing, age-hardenable HSLA-100 steel during tempering can be done by continuous electrical resistivity measurement. These data also allow an in-depth kinetic analysis using the Johnson-Mehl-Avrami equation. (Abstract Copyright [2003], Wiley Periodicals, Inc.)

  3. Electric power annual 1995. Volume II

    Energy Technology Data Exchange (ETDEWEB)

    NONE

    1996-12-01

    This document summarizes pertinent statistics on various aspects of the U.S. electric power industry for the year and includes a graphic presentation. Data is included on electric utility retail sales and revenues, financial statistics, environmental statistics of electric utilities, demand-side management, electric power transactions, and non-utility power producers.

  4. electrical resistivity measurements of downscaled homogenous ...

    African Journals Online (AJOL)

    ES Obe

    Knowledge of electrical resistivity for reservoir rocks is crucial for a number of reservoir ... A better validation of micro-CT technique would be to use the same core size for ... forecasts. Nigerian Journal of Technology. Vol. 30, No. 2, June 2011.

  5. Temperature dependent electrical resistivity of liquid Sn

    Science.gov (United States)

    Prajapati, A. V.; Sonvane, Y. A.; Patel, H. P.; Thakor, P. B.

    2016-05-01

    The present paper deals with the effect of temperature variation on the electrical resistivity (ρ) of liquid Sn(Tin). We have used a new parameter free pseudopotential along with screening Taylor et al and Farid et al local field correction functions. The Percus-Yevick Hard Sphere (PYHS) reference system is used to describe structural information. Zeeman formula has been used for finding resistivity with the variation of temperature. The balanced harmonies between present data and experimental data have been achieved with a minimal deviation. So, we concluded that our newly constructed model potential is an effective one to produce the data of electrical resistivity of liquid Sn(Tin) as a function of temperature.

  6. Electric power annual 1995. Volume I

    Energy Technology Data Exchange (ETDEWEB)

    NONE

    1996-07-01

    The Electric Power Annual presents a summary of electric power industry statistics at national, regional, and State levels. The objective of the publication is to provide industry decisionmakers, government policymakers, analysts, and the general public with data that may be used in understanding U.S. electricity markets. The Electric Power Annual is prepared by the Coal and Electric Data and Renewables Division; Office of Coal, Nuclear, Electric and Alternate Fuels; Energy Information Administration (EIA); U.S. Department of Energy. In the private sector, the majority of the users of the Electric Power Annual are researchers and analysts and, ultimately, individuals with policy- and decisionmaking responsibilities in electric utility companies. Financial and investment institutions, economic development organizations interested in new power plant construction, special interest groups, lobbyists, electric power associations, and the news media will find data in the Electric Power Annual useful. In the public sector, users include analysts, researchers, statisticians, and other professionals with regulatory, policy, and program responsibilities for Federal, State, and local governments. The Congress and other legislative bodies may also be interested in general trends related to electricity at State and national levels. Much of the data in these reports can be used in analytic studies to evaluate new legislation. Public service commissions and other special government groups share an interest in State-level statistics. These groups can also compare the statistics for their States with those of other jurisdictions.

  7. Electrical resistance of a capillary endothelium

    Science.gov (United States)

    1981-01-01

    The electrical resistance of consecutive segments of capillaries has been determined by a method in which the microvessels were treated as a leaky, infinite cable. A two-dimensional analytical model to describe the potential field in response to intracapillary current injection was formulated. The model allowed determination of the electrical resistance from four sets of data: the capillary radius, the capillary length constant, the length constant in the mesentery perpendicular to the capillary, and the relative potential drop across the capillary wall. Of particular importance were the mesothelial membranes covering the mesenteric capillaries with resistances several times higher than that of the capillary endothelium. 27 frog mesenteric capillaries were characterized. The average resistance of the endothelium was 1.85 omega cm2, which compares well with earlier determinations of the ionic permeability of such capillaries. However, heterogeneity with respect to resistance was observed, that of 10 arterial capillaries being 3.0 omega cm2 as compared with 0.95 omega cm2 for 17 mid- and venous capillaries. The average in situ length constant was 99 micrometers for the arterial capillaries and 57 micrometers for the mid- and venous capillaries. It is likely that the ions that carry the current must move paracellularly, through junctions that are leaky to small solutes. PMID:7241087

  8. DOE Fundamentals Handbook: Electrical Science, Volume 3

    Energy Technology Data Exchange (ETDEWEB)

    1992-06-01

    The Electrical Science Fundamentals Handbook was developed to assist nuclear facility operating contractors provide operators, maintenance personnel, and the technical staff with the necessary fundamentals training to ensure a basic understanding of electrical theory, terminology, and application. The handbook includes information on alternating current (AC) and direct current (DC) theory, circuits, motors and generators; AC power and reactive components; batteries; AC and DC voltage regulators; transformers; and electrical test instruments and measuring devices. This information will provide personnel with a foundation for understanding the basic operation of various types of DOE nuclear facility electrical equipment.

  9. DOE Fundamentals Handbook: Electrical Science, Volume 4

    Energy Technology Data Exchange (ETDEWEB)

    1992-06-01

    The Electrical Science Fundamentals Handbook was developed to assist nuclear facility operating contractors provide operators, maintenance personnel, and the technical staff with the necessary fundamentals training to ensure a basic understanding of electrical theory, terminology, and application. The handbook includes information on alternating current (AC) and direct current (DC) theory, circuits, motors, and generators; AC power and reactive transformers; and electrical test components; batteries; AC and DC voltage regulators; instruments and measuring devices. This information will provide personnel with a foundation for understanding the basic operation of various types of DOE nuclear facility electrical equipment.

  10. DOE Fundamentals Handbook: Electrical Science, Volume 1

    Energy Technology Data Exchange (ETDEWEB)

    1992-06-01

    The Electrical Science Fundamentals Handbook was developed to assist nuclear facility operating contractors provide operators, maintenance personnel, and the technical staff with the necessary fundamentals training to ensure a basic understanding of electrical theory, terminology, and application. The handbook includes information on alternating current (AC) and direct current (DC) theory, circuits, motors, and generators; AC power and reactive components; batteries; AC and DC voltage regulators; transformers; and electrical test instruments and measuring devices. This information will provide personnel with a foundation for understanding the basic operation of various types of DOE nuclear facility electrical equipment.

  11. Electrical Resistance Tomography of Conductive Thin Films

    CERN Document Server

    Cultrera, Alessandro

    2016-01-01

    The Electrical Resistance Tomography (ERT) technique is applied to the measurement of sheet conductance maps of both uniform and patterned conductive thin films. Images of the sheet conductance spatial distribution, and local conductivity values are obtained. Test samples are tin oxide films on glass substrates, with electrical contacts on the sample boundary, some samples are deliberately patterned in order to induce null conductivity zones of known geometry while others contain higher conductivity inclusions. Four-terminal resistance measurements among the contacts are performed with a scanning setup. The ERT reconstruction is performed by a numerical algorithm based on the total variation regularization and the L-curve method. ERT correctly images the sheet conductance spatial distribution of the samples. The reconstructed conductance values are in good quantitative agreement with independent measurements performed with the van der Pauw and the four-point probe methods.

  12. Electrical resistance tomography of concrete structures

    Energy Technology Data Exchange (ETDEWEB)

    Daily, W.; Ramirez, A. [Lawrence Livermore National Lab., CA (United States); Binley, A.; Henry-Poulter, S. [Lancaster Univ. (United Kingdom). Dept. of Environmental Sciences

    1993-10-01

    The purpose of this work is to determine the feasibility of using Electrical resistance tomography (ERT) to nondestructively examine the interior of concrete structures such as bridge pillars and roadways. We report the results of experiments wherein ERT is used to image the two concrete specimens in the laboratory. Each specimen is 5 inches square and 12 inches long and contained steel reinforcing rods along its length. Twenty electrodes were placed on each sample and an-image of electrical resistivity distribution was generated from current and voltage measurements. We found that the images show the general location of the reinforcing steel and, what`s more important, delineate the absence of the steel. The method may therefore be useful for determining if such steel has been destroyed by corrosion, however to make it useful, the technique must have better resolution so that individual reinforcing steel units are resolved.

  13. Delineation of graves using electrical resistivity tomography

    Science.gov (United States)

    Nero, Callistus; Aning, Akwasi Acheampong; Danuor, Sylvester K.; Noye, Reginald M.

    2016-03-01

    A suspected old royal cemetery has been surveyed at the Kwame Nkrumah University of Science and Technology (KNUST) campus, Kumasi, Ghana using Electrical Resistivity Tomography (ERT) with the objective of detecting graves in order to make informed decisions with regard to the future use of the area. The survey was conducted on a 10,000 m2 area. Continuous Vertical Electrical Sounding (CVES) was combined with the roll along technique for 51 profiles with 1 m probe separation separated by 2 m. Inverted data results indicated wide resistivity variations ranging between 9.34 Ωm and 600 Ωm in the near surface. Such heterogeneity suggests a disturbance of the soil at this level. Both high (≥ 600 Ωm) and low resistivity (≤ 74.7 Ωm) anomalies, relative to background levels, were identified within the first 4 m of the subsurface. These were suspected to be burial tombs because of their rectangular geometries and resistivity contrasts. The results were validated with forward numerical modeling results. The study area is therefore an old cemetery and should be preserved as a cultural heritage site.

  14. DOE Fundamentals Handbook: Electrical Science, Volume 2

    Energy Technology Data Exchange (ETDEWEB)

    1992-06-01

    The Electrical Science Fundamentals Handbook was developed to assist nuclear facility operating contractors provide operators, maintenance personnel, and the technical staff with the necessary fundamentals training to ensure a basic understanding terminology, and application. The handbook includes information on alternating current (AC) and direct current (DC) theory, circuits, motors, and generators; AC power and reactive components; batteries; AC and DC voltage regulators; transformers; and electrical test instruments and measuring devices. This information will provide personnel with a foundation for understanding the basic operation of various types of DOE nuclear facility electrical equipment.

  15. Electrical resistivity measurements to predict abrasion resistance of rock aggregates

    Indian Academy of Sciences (India)

    Sair Kahraman; Mustafa Fener

    2008-04-01

    The prediction of Los Angeles (LA) abrasion loss from some indirect tests is useful for practical applications. For this purpose, LA abrasion, electrical resistivity, density and porosity tests were carried out on 27 different rock types. LA abrasion loss values were correlated with electrical resistivity and a good correlation between the two parameters was found. To see the effect of rock class on the correlation, regression analysis was repeated for igneous rocks, metamorphic rocks and sedimentary rocks, respectively. It was seen that correlation coefficients were increased for the rock classes. In addition, the data were divided into two groups according to porosity and density, respectively. After repeating regression analysis for these porosity and density groups, stronger correlations were obtained compared to the equation derived for all rocks. The validity of the derived equations was statistically tested and it was shown that all derived equations were significant. Finally, it can be said that all derived equations can alternatively be used for the estimation of LA abrasion loss from electrical resistivity.

  16. Complex Electrical Resistivity for Monitoring DNAPL Contamination

    Energy Technology Data Exchange (ETDEWEB)

    Stephen R. Brown; David Lesmes; John Fourkas

    2003-09-12

    Nearly all Department of Energy (DOE) facilities have landfills and buried waste areas. Of the various contaminants present at these sites, dense non-aqueous phase liquids (DNAPL) are particularly hard to locate and remove. There is an increasing need for external or non-invasive sensing techniques to locate DNAPLs in the subsurface and to track their spread and monitor their breakdown or removal by natural or engineered means. G. Olhoeft and colleagues have published several reports based on laboratory studies using the complex resistivity method which indicate that organic solvents, notably toluene, PCE, and TCE, residing in clay-bearing soils have distinctive electrical signatures. These results have suggested to many researchers the basis of an ideal new measurement technique for geophysical characterization of DNAPL pollution. Encouraged by these results we proposed to bring the field measurement of complex resistivity as a means of pollution characterization from the conceptual stage to practice. We planned to document the detectability of clay-organic solvent interactions with geophysical measurements in the laboratory, develop further understanding of the underlying physical and chemical mechanisms, and then apply these observations to develop field techniques. As with any new research endeavor we note the extreme importance of trying to reproduce the work of previous researchers to ensure that any effects observed are due to the physical phenomena occurring in the specimen and not due to the particular experimental apparatus or method used. To this end, we independently designed and built a laboratory system, including a sample holder, electrodes, electronics, and data analysis software, for the measurement of the complex electrical resistivity properties of soil contaminated with organic solvents. The capabilities and reliability of this technique were documented. Using various standards we performed measurement accuracy, repeatability, and noise immunity

  17. Influence of the Aggregate Volume on the Eleetrieal Resistivity and Properties of Portland Cement Concretes

    Institute of Scientific and Technical Information of China (English)

    WEI Xiaosheng; XIAO Lianzhen

    2011-01-01

    The electrical resistivity of concretes with various aggregate volume fractions (Va) of 0%-70%at water/cement (W/C) ratios of 0.4 and 0.5 during l day was monitored.It is found that the addition of normal aggregate to cement paste leads to a regular increase in concrete resistivity at each hydration stage and the electrical resistivity has a deeper increase for the lower W/C at a fixed aggregate volume fraction.The number of normalized resistivity (NR) of concrete to its paste matrix was introduced,which is only a function of aggregate volume fraction (Va).The quantitative relationships give an alternative method for the prediction of aggregate volume in the concrete.A logarithmic relation is established between the elastic modulus of concrete at 7 days or 28 days and the electrical resistivity of concrete at 1 day.The equations are obtained,the compressive strength of concrete at 7 days or 28 days can be determined by the electrical resistivity of concrete at 1 day and the used aggregate content in the concrete.The quantitative relationships give a non-destructive test (NDT) method for prediction of concrete elastic modulus and compressive strength.

  18. Correlation between Wear Resistance and Lifetime of Electrical Contacts

    Directory of Open Access Journals (Sweden)

    Jian Song

    2012-01-01

    Full Text Available Electrical contacts are usually plated in order to prevent corrosion. Platings of detachable electrical contacts experience wear because of the motion between contacts. Once the protecting platings have been worn out, electrical contacts will fail rapidly due to corrosion or fretting corrosion. Therefore the wear resistance of the platings is a very important parameter for the long lifetime of electrical contacts. Many measures which improve the wear resistance can diminish the conductivity of the platings. Due to the fact that platings of electrical contacts must have both a high wear resistance and a high electrical conductivity, the manufacturing of high performance platings of electrical contacts poses a great challenge. Our study shows firstly the correlation between the wear resistance of platings and lifetime of electrical contacts and then the measures, which improve the wear resistance without impairing the electrical performance of the contacts.

  19. Electrical Resistance Tomography imaging of concrete

    KAUST Repository

    Karhunen, Kimmo

    2010-01-01

    We apply Electrical Resistance Tomography (ERT) for three dimensional imaging of concrete. In ERT, alternating currents are injected into the target using an array of electrodes attached to the target surface, and the resulting voltages are measured using the same electrodes. These boundary measurements are used for reconstructing the internal (3D) conductivity distribution of the target. In reinforced concrete, the metallic phases (reinforcing bars and fibers), cracks and air voids, moisture gradients, and the chloride distribution in the matrix carry contrast with respect to conductivity. While electrical measurements have been widely used to characterize the properties of concrete, only preliminary results of applying ERT to concrete imaging have been published so far. The aim of this paper is to carry out a feasibility evaluation with specifically cast samples. The results indicate that ERT may be a feasible modality for non-destructive evaluation of concrete. © 2009 Elsevier Ltd. All rights reserved.

  20. Electrical Resistance Alloys and Low-Expansion Alloys

    DEFF Research Database (Denmark)

    Kjer, Torben

    1996-01-01

    The article gives an overview of electrical resistance alloys and alloys with low thermal expansion. The electrical resistance alloys comprise resistance alloys, heating alloys and thermostat alloys. The low expansion alloys comprise alloys with very low expansion coefficients, alloys with very low...

  1. Efficiency of a Marine Towed Electrical Resistivity Method

    Directory of Open Access Journals (Sweden)

    Chih-Wen Chiang

    2011-01-01

    Full Text Available In contrast to marine sediments, because of large electrical resistivity anomalies found in sulfide deposits and methane hydrates, resistivity measurements such as marine towed electrical resistivity (MTER might be a feasible method for discovering those natural minerals. To determine the feasibility of the MTER method we examined arrays consisting of a pole electrical dipole (PED, vertical electrical dipole (VED and horizontal electrical dipole (HED. The VED array showed a maximum difference in electric fields of 36 o/o and 105 o/o in the resistive and conductive models, respectively, while the PED and HED arrays yielded worse results of around 13 o/o to 19 o/o, respectively. The VED array showed a higher difference in electric fields than both the HED and PED arrays in the two models. Therefore, we suggest that a VED array with a large electrical current would be most conducive leading to the discovery of such minerals during MTER surveys.

  2. Sputter-Resistant Materials for Electric Propulsion Project

    Data.gov (United States)

    National Aeronautics and Space Administration — This SBIR Phase 2 project shall develop sputter-resistant materials for use in electric propulsion test facilities and for plume shields on spacecraft using electric...

  3. Repeatable change in electrical resistance of Si surface by mechanical and electrical nanoprocessing.

    Science.gov (United States)

    Miyake, Shojiro; Suzuki, Shota

    2014-01-01

    The properties of mechanically and electrically processed silicon surfaces were evaluated by atomic force microscopy (AFM). Silicon specimens were processed using an electrically conductive diamond tip with and without vibration. After the electrical processing, protuberances were generated and the electric current through the silicon surface decreased because of local anodic oxidation. Grooves were formed by mechanical processing without vibration, and the electric current increased. In contrast, mechanical processing with vibration caused the surface to protuberate and the electrical resistance increased similar to that observed for electrical processing. With sequential processing, the local oxide layer formed by electrical processing can be removed by mechanical processing using the same tip without vibration. Although the electrical resistance is decreased by the mechanical processing without vibration, additional electrical processing on the mechanically processed area further increases the electrical resistance of the surface.

  4. Effeet of Strain on the Electrical Resistance of Carbon Nanotube/Silicone Rubber Composites

    Institute of Scientific and Technical Information of China (English)

    ZENG You; LIU Huashi; CHEN Juan; GE Heyi

    2011-01-01

    Carbon nanotube (CNT) filled silicone rubber (SR) composites were synthesized by in situ polymerization.The effect of strain on the electrical resistance of the CNT/SR composites and the structure evolution of CNT networks during tensile deformation were investigated.The results showed that the CNT/SR composites had high sensitivity of resistance-strain response.In a wide strain range (0-125%),the change of resistivity could reach 107,which was closely associated with the evolution process of the conductive CNTnetwork structure.The volume expansion of the composites in the tensile process led to a gradual decrease in the volume fraction of CNTs with the strain increase.When CNT loading was lower than the percolation threshold,CNT network was in disconnected state with a rapid increase in electrical resistance of the composites.Furthermore,the CNT loading had remarkable effect on the sensitivity of resistance-strain response in the composites.

  5. Factors influencing electric utility expansion. Volume II

    Energy Technology Data Exchange (ETDEWEB)

    Masud, E. [ed.

    1977-01-01

    This report, Vol. 2, submitted by the General Electric Co., identifies factors that should be considered in planning interconnected systems and discusses how these factors relate to one another. The objective is to identify all the factors and classify them by their use and importance in arriving at a decision. Chapter 2 discusses the utility system and its system behavior characteristics, emphasizing behavior that affects the planning of the bulk-power generation and transmission system. Chapter 3 introduces interconnection planning by discussing the new system characteristics brought to operation and planning. Forty-two factors associated with cost, reliability, constraints, and coordination are related to each other by factor trees. Factor trees display the relationship of one factor such as reliability to more-detailed factors which in turn are further related to individual characteristics of facilities. These factor trees provide a structure to the presentation. A questionnaire including the 42 factors was completed by 52 system planners from utility companies and government authorities. The results of these questionnaires are tabulated and presented with pertinent discussion of each factor. Chapter 4 deals with generation planning, recognizing the existence of interconnections. Chapter 5 addresses transmission planning, questions related to reliability and cost measures and constraints, and factors related to both analytical techniques and planning procedures. The chapter ends with a discussion of combined generation-transmission planning. (MCW)

  6. Influence of Ultraviolet/Ozonolysis Treatment of Nanocarbon Filler on the Electrical Resistivity of Epoxy Composites.

    Science.gov (United States)

    Perets, Yulia; Matzui, Lyudmila; Vovchenko, Lyudmila; Ovsiienko, Irina; Yakovenko, Olena; Lazarenko, Oleksandra; Zhuravkov, Alexander; Brusylovets, Oleksii

    2016-12-01

    In the present work, we have investigated concentration and temperature dependences of electrical conductivity of graphite nanoplatelets/epoxy resin composites. The content of nanocarbon filler is varied from 0.01 to 0.05 volume fraction. Before incorporation into the epoxy resin, the graphite nanoplatelets were subjected to ultraviolet ozone treatment at 20-min ultraviolet exposure. The electric resistance of the samples was measured by two- or four-probe method and teraohmmeter E6-13. Several characterization techniques were employed to identify the mechanisms behind the improvements in the electrical properties, including SEM and FTIR spectrum analysis.It is established that the changes of the relative intensities of the bands in FTIR spectra indicate the destruction of the carboxyl group -COOH and group -OH. Electrical conductivity of composites has percolation character and graphite nanoplatelets (ultraviolet ozone treatment for 20 min) addition which leads to a decrease of percolation threshold 0.005 volume fraction and increase values of electrical conductivity (by 2-3 orders of magnitude) above the percolation threshold in comparison with composite materials-graphite nanoplatelets/epoxy resin. The changes of the value and behavior of temperature dependences of the electrical resistivity of epoxy composites with ultraviolet/ozone-treated graphite nanoparticles have been analyzed within the model of effective electrical conductivity. The model takes into account the own electrical conductivity of the filler and the value of contact electric resistance between the filler particles of the formation of continuous conductive pathways.

  7. A Review of Electrical Impedance Spectrometry Methods for Parametric Estimation of Physiologic Fluid Volumes

    Science.gov (United States)

    Dewberry, B.

    2000-01-01

    Electrical impedance spectrometry involves measurement of the complex resistance of a load at multiple frequencies. With this information in the form of impedance magnitude and phase, or resistance and reactance, basic structure or function of the load can be estimated. The "load" targeted for measurement and estimation in this study consisted of the water-bearing tissues of the human calf. It was proposed and verified that by measuring the electrical impedance of the human calf and fitting this data to a model of fluid compartments, the lumped-model volume of intracellular and extracellular spaces could be estimated, By performing this estimation over time, the volume dynamics during application of stimuli which affect the direction of gravity can be viewed. The resulting data can form a basis for further modeling and verification of cardiovascular and compartmental modeling of fluid reactions to microgravity as well as countermeasures to the headward shift of fluid during head-down tilt or spaceflight.

  8. TUTORIAL: Electrical resistance: an atomistic view

    Science.gov (United States)

    Datta, Supriyo

    2004-07-01

    This tutorial article presents a 'bottom-up' view of electrical resistance starting from something really small, like a molecule, and then discussing the issues that arise as we move to bigger conductors. Remarkably, no serious quantum mechanics is needed to understand electrical conduction through something really small, except for unusual things like the Kondo effect that are seen only for a special range of parameters. This article starts with energy level diagrams (section 2), shows that the broadening that accompanies coupling limits the conductance to a maximum of q2/h per level (sections 3, 4), describes how a change in the shape of the self-consistent potential profile can turn a symmetric current-voltage characteristic into a rectifying one (sections 5, 6), shows that many interesting effects in molecular electronics can be understood in terms of a simple model (section 7), introduces the non-equilibrium Green function (NEGF) formalism as a sophisticated version of this simple model with ordinary numbers replaced by appropriate matrices (section 8) and ends with a personal view of unsolved problems in the field of nanoscale electron transport (section 9). Appendix A discusses the Coulomb blockade regime of transport, while appendix B presents a formal derivation of the NEGF equations. MATLAB codes for numerical examples are listed in appendix C. (The appendices are available in the online version only.)

  9. Viscosity and electrical resistivity of Al-Li melts

    Science.gov (United States)

    Kononenko, V. I.; Razhabov, A. A.; Ryabina, A. V.

    2011-08-01

    The kinematic viscosity and electrical resistivity of Al-Li alloys in the liquid state are studied by a combined electrodeless method. Some theoretical calculations performed to determine the viscosity and electrical resistance by comparing the calculated and experimental data are estimated.

  10. Premixed combustion under electric field in a constant volume chamber

    KAUST Repository

    Cha, Min Suk

    2012-12-01

    The effects of electric fields on outwardly propagating premixed flames in a constant volume chamber were experimentally investigated. An electric plug, subjected to high electrical voltages, was used to generate electric fields inside the chamber. To minimize directional ionic wind effects, alternating current with frequency of 1 kHz was employed. Lean and rich fuel/air mixtures for both methane and propane were tested to investigate various preferential diffusion conditions. As a result, electrically induced instability showing cracked structure on the flame surface could be observed. This cracked structure enhanced flame propagation speed for the initial period of combustion and led to reduction in flame initiation and overall combustion duration times. However, by analyzing pressure data, it was found that overall burning rates are not much affected from the electric field for the pressurized combustion period. The reduction of overall combustion time is less sensitive to equivalence ratio for methane/air mixtures, whereas the results demonstrate pronounced effects on a lean mixture for propane. The improvement of combustion characteristics in lean mixtures will be beneficial to the design of lean burn engines. Two hypothetical mechanisms to explain the electrically induced instability were proposed: 1) ionic wind initiated hydrodynamic instability and 2) thermodiffusive instability through the modification of transport property such as mass diffusivity. © 2012 IEEE.

  11. Comparison of methods to quantify volume during resistance exercise.

    Science.gov (United States)

    McBride, Jeffrey M; McCaulley, Grant O; Cormie, Prue; Nuzzo, James L; Cavill, Michael J; Triplett, N Travis

    2009-01-01

    The purpose of this investigation was to compare 4 different methods of calculating volume when comparing resistance exercise protocols of varying intensities. Ten Appalachian State University students experienced in resistance exercise completed 3 different resistance exercise protocols on different days using a randomized, crossover design, with 1 week of rest between each protocol. The protocols included 1) hypertrophy: 4 sets of 10 repetitions in the squat at 75% of a 1-repetition maximum (1RM) (90-second rest periods); 2) strength: 11 sets of 3 repetitions at 90% 1RM (5-minute rest periods); and 3) power: 8 sets of 6 repetitions of jump squats at 0% 1RM (3-minute rest periods). The volume of resistance exercise completed during each protocol was determined with 4 different methods: 1) volume load (VL) (repetitions [no.] x external load [kg]); 2) maximum dynamic strength volume load (MDSVL) (repetitions [no.] x [body mass--shank mass (kg) + external load (kg)]); 3) time under tension (TUT) (eccentric time +milliseconds] + concentric time +milliseconds]); and 4) total work (TW) (force [N] x displacement [m]). The volumes differed significantly (p , 0.05) between hypertrophy and strength in comparison with the power protocol when VL and MDSVL were used to determine the volume of resistance exercise completed. Furthermore, significant differences in TUT existed between all 3 resistance exercise protocols. The TW calculated was not significantly different between the 3 protocols. These data imply that each method examined results in substantially different values when comparing various resistance exercise protocols involving different levels of intensity.

  12. Iron aluminide useful as electrical resistance heating elements

    Energy Technology Data Exchange (ETDEWEB)

    Sikka, V.K.; Deevi, S.C.; Fleischhauer, G.S.; Hajaligol, M.R.; Lilly, A.C. Jr.

    1999-11-02

    The invention relates generally to aluminum containing iron-base alloys useful as electrical resistance heating elements. The aluminum containing iron-base alloys have improved room temperature ductility, electrical resistivity, cyclic fatigue resistance, high temperature oxidation resistance, low and high temperature strength, and/or resistance to high temperature sagging. The alloy has an entirely ferritic microstructure which is free of austenite and includes, in weight %, over 4% Al, {le}1% Cr and either {ge}0.05% Zr or ZrO{sub 2} stringers extending perpendicular to an exposed surface of the heating element or {ge}0.1% oxide dispersoid particles. The alloy can contain 14--32% Al, {le}2% Ti, {le}2% Mo, {le}1% Zr, {le}1% C, {le}0.1% B, {le}30% oxide dispersoid and/or electrically insulating or electrically conductive covalent ceramic particles, {le}1% rare earth metal, {le}1% oxygen, {le}3% Cu, balance Fe.

  13. Iron aluminide useful as electrical resistance heating elements

    Energy Technology Data Exchange (ETDEWEB)

    Sikka, Vinod K. (Oak Ridge, TN); Deevi, Seetharama C. (Oak Ridge, TN); Fleischhauer, Grier S. (Midlothian, VA); Hajaligol, Mohammad R. (Richmond, VA); Lilly, Jr., A. Clifton (Chesterfield, VA)

    2001-01-01

    The invention relates generally to aluminum containing iron-base alloys useful as electrical resistance heating elements. The aluminum containing iron-base alloys have improved room temperature ductility, electrical resistivity, cyclic fatigue resistance, high temperature oxidation resistance, low and high temperature strength, and/or resistance to high temperature sagging. The alloy has an entirely ferritic microstructure which is free of austenite and includes, in weight %, over 4% Al, .ltoreq.1% Cr and either .gtoreq.0.05% Zr or ZrO.sub.2 stringers extending perpendicular to an exposed surface of the heating element or .gtoreq.0.1% oxide dispersoid particles. The alloy can contain 14-32% Al, .ltoreq.2% Ti, .ltoreq.2% Mo, .ltoreq.1% Zr, .ltoreq.1% C, .ltoreq.0.1% B, .ltoreq.30% oxide dispersoid and/or electrically insulating or electrically conductive covalent ceramic particles, .ltoreq.1% rare earth metal, .ltoreq.1% oxygen, .ltoreq.3% Cu, balance Fe.

  14. Iron aluminide useful as electrical resistance heating elements

    Energy Technology Data Exchange (ETDEWEB)

    Sikka, Vinod K. (Oak Ridge, TN); Deevi, Seetharama C. (Oak Ridge, TN); Fleischhauer, Grier S. (Midlothian, VA); Hajaligol, Mohammad R. (Richmond, VA); Lilly, Jr., A. Clifton (Chesterfield, VA)

    1999-01-01

    The invention relates generally to aluminum containing iron-base alloys useful as electrical resistance heating elements. The aluminum containing iron-base alloys have improved room temperature ductility, electrical resistivity, cyclic fatigue resistance, high temperature oxidation resistance, low and high temperature strength, and/or resistance to high temperature sagging. The alloy has an entirely ferritic microstructure which is free of austenite and includes, in weight %, over 4% Al, .ltoreq.1% Cr and either .gtoreq.0.05% Zr or ZrO.sub.2 stringers extending perpendicular to an exposed surface of the heating element or .gtoreq.0.1% oxide dispersoid particles. The alloy can contain 14-32% Al, .ltoreq.2% Ti, .ltoreq.2% Mo, .ltoreq.1% Zr, .ltoreq.1% C, .ltoreq.0.1% B, .ltoreq.30% oxide dispersoid and/or electrically insulating or electrically conductive covalent ceramic particles, .ltoreq.1% rare earth metal, .ltoreq.1% oxygen, .ltoreq.3% Cu, balance Fe.

  15. Mapping Contaminant Remediation with Electrical Resistivity Tomography

    Science.gov (United States)

    Gerhard, J.; Power, C.; Tsourlos, P.; Karaoulis, M.; Giannopoulos, A.; Soupios, P. M.; Simyrdanis, K.

    2014-12-01

    The remediation of sites contaminated with industrial chemicals - specifically dense non-aqueous phase liquids (DNAPLs) like coal tar and chlorinated solvents - represents a major geoenvironmental challenge. Remediation activities would benefit from a non-destructive technique to map the evolution of DNAPL mass in space and time. Electrical resistivity tomography (ERT) has long-standing potential in this context but has not yet become a common tool at DNAPL sites. This work evaluated the potential of time-lapse ERT for mapping DNAPL mass reduction in real time during remediation. Initially, a coupled DNAPL-ERT numerical model was developed for exploring this potential at the field scale, generating realistic DNAPL scenarios and predicting the response of an ERT survey. Also, new four-dimensional (4D) inversion algorithms were integrated for tracking DNAPL removal over time. 4D ERT applied at the surface for mapping an evolving DNAPL distribution was first demonstrated in a laboratory experiment. Independent simulation of the experiment demonstrated the reliability of the DNAPL-ERT model for simulating real systems. The model was then used to explore the 4D ERT approach at the field scale for a range of realistic DNAPL remediation scenarios. The approach showed excellent potential for mapping shallow DNAPL changes. However, remediation at depth was not as well resolved. To overcome this limitation, a new surface-to-horizontal borehole (S2HB) ERT configuration is proposed. A second laboratory experiment was conducted that demonstrated that S2HB ERT does better resolve changes in DNAPL distribution relative to surface ERT, particularly at depth. The DNAPL-ERT model was also used to demonstrate the improved mapping of S2HB ERT for field scale DNAPL scenarios. Overall, this work demonstrates that, with these innovations, ERT exhibits significant potential as a real time, non-destructive geoenvironmental remediation site monitoring tool.

  16. Electrical Resistivity and Thermodynamic Properties of Iron Under High Pressure

    Science.gov (United States)

    Hieu, Ho Khac; Hai, Tran Thi; Hong, Nguyen Thi; Sang, Ngo Dinh; Tuyen, Nguyen Viet

    2017-03-01

    In this work, the electrical resistivity and thermodynamic properties of iron under high pressure have been investigated by using the semi-empirical approach. The recently well-established Grüneisen parameter expressions have been applied to derive the Debye frequency and temperature under compression. Using these results combined with the Bloch-Grüneisen law, the resistivity of iron has also been determined up to Earth's core pressures. We show that the electrical resistivity diminished gradually with pressure and saturates at high pressure. Our model gives low electrical resistivity values which are in agreement with the recent experimental measurements. The low resistivity may be attributed to the well-known resistivity saturation effect at high temperature, which was not considered in earlier models of core conductivity.

  17. Influence of Ultraviolet/Ozonolysis Treatment of Nanocarbon Filler on the Electrical Resistivity of Epoxy Composites

    Science.gov (United States)

    Perets, Yulia; Matzui, Lyudmila; Vovchenko, Lyudmila; Ovsiienko, Irina; Yakovenko, Olena; Lazarenko, Oleksandra; Zhuravkov, Alexander; Brusylovets, Oleksii

    2016-08-01

    In the present work, we have investigated concentration and temperature dependences of electrical conductivity of graphite nanoplatelets/epoxy resin composites. The content of nanocarbon filler is varied from 0.01 to 0.05 volume fraction. Before incorporation into the epoxy resin, the graphite nanoplatelets were subjected to ultraviolet ozone treatment at 20-min ultraviolet exposure. The electric resistance of the samples was measured by two- or four-probe method and teraohmmeter E6-13. Several characterization techniques were employed to identify the mechanisms behind the improvements in the electrical properties, including SEM and FTIR spectrum analysis.

  18. State Waste Discharge Permit Application: Electric resistance tomography testing

    Energy Technology Data Exchange (ETDEWEB)

    1994-04-01

    This permit application documentation is for a State Waste Discharge Permit issued in accordance with requirements of Washington Administrative Code 173-216. The activity being permitted is a technology test using electrical resistance tomography. The electrical resistance tomography technology was developed at Lawrence Livermore National Laboratory and has been used at other waste sites to track underground contamination plumes. The electrical resistance tomography technology measures soil electrical resistance between two electrodes. If a fluid contaminated with electrolytes is introduced into the soil, the soil resistance is expected to drop. By using an array of measurement electrodes in several boreholes, the areal extent of contamination can be estimated. At the Hanford Site, the purpose of the testing is to determine if the electrical resistance tomography technology can be used in the vicinity of large underground metal tanks without the metal tank interfering with the test. It is anticipated that the electrical resistance tomography technology will provide a method for accurately detecting leaks from the bottom of underground tanks, such as the Hanford Site single-shell tanks.

  19. Characterization of electrical properties of resistance welding machines

    Institute of Scientific and Technical Information of China (English)

    Wu Pei; Shao Yingli; Wenqi Zhang; Niels Bay

    2008-01-01

    Due to the individual electrical and mechanical characteristics of resistance welding machines, choice of the right machine and welding parameters for an optimized production is often difficult. This is especially the case in projection welding of complex joints. In this paper, a new approach of characterizing the electrical properties of AC resistance welding machines is presented, involving testing and mathematical modelling of the weld current, the firing angle and the conduction angle of silicon controlled rectifiers with the aid of a series of proof resistances. The model predicts the weld current and the conduction angle (or heat setting) at each set current, when the workpiece resistance is given.

  20. Detection of sinkholes using 2D electrical resistivity imaging

    CSIR Research Space (South Africa)

    Van Schoor, Abraham M

    2002-07-01

    Full Text Available Sinkholes in dolomitic areas are notoriously difficult geophysical targets, and selecting an appropriate geophysical solution is not straightforward. Electrical resistivity imaging or tomography (RESTOM) is well suited to mapping sinkholes because...

  1. Use of electrical resistivity technique for engineering site ...

    African Journals Online (AJOL)

    ... of electrical resistivity technique for engineering site investigation: a case study ... The qualitative interpretation of the horizontal profiling delineated the contact ... this area; therefore the use of raft foundation and/or any other foundation that ...

  2. Repetitively Pulsed Electric Laser Acoustic Studies. Volume 1.

    Science.gov (United States)

    1983-09-01

    INGARD ET AL. SEP 83 UNCLASSIFIED APHAL-IR-83-2858-VOL-1 F336i5 86-C 2848 F/ 0/ 8, EEEmohEEEomhiE EohEEmhohEEEEE mhhhmmomhhlm...TR-83-2058, Vol 9, 0 REPETITIVELY PULSED ELECTRIC LASER ACOUSTIC STUDIES Volume I K. U. INGARD , CHARLES F. MCMILLAN uDEPARTMENT OF AERONAUTICS AND...CONTRACT OR GRANT NUMBER(s) K.U. Ingard and Charles F. McMillan F33615.80-C-2040 9. PERFORMING ORGANIZATION NAME AND ADDRESS 10. PROGRAM ELEMENT. PROJECT

  3. electrical resistivity tomography and magnetic surveys: applications ...

    African Journals Online (AJOL)

    Vertical Electrical Sounding (VES) and magnetic surveys have been used for the purpose. The ERT and VES results .... engineering and environmental applications cor- responding to ...... Bernard, J. (2003). Short notes on the principles of.

  4. Resistance switching induced by electric fields in manganite thin films

    Energy Technology Data Exchange (ETDEWEB)

    Villafuerte, M [Facultad de Ciencias Exactas y TecnologIa, Universidad Nacional de Tucuman, S. M. de Tucuman (Argentina); Juarez, G [Facultad de Ciencias Exactas y TecnologIa, Universidad Nacional de Tucuman, S. M. de Tucuman (Argentina); Duhalde, S [Dpto de Fisica, Facultad de IngenierIa, Universidad de Buenos Aires, Paseo Colon 850, 1063 Buenos Aires (Argentina); Golmar, F [Dpto de Fisica, Facultad de IngenierIa, Universidad de Buenos Aires, Paseo Colon 850, 1063 Buenos Aires (Argentina); Degreef, C L [Dpto de Fisica, Facultad de IngenierIa, Universidad de Buenos Aires, Paseo Colon 850, 1063 Buenos Aires (Argentina); Heluani, S P [Facultad de Ciencias Exactas y TecnologIa, Universidad Nacional de Tucuman, S. M. de Tucuman (Argentina)

    2007-04-15

    In this work, we investigate the polarity-dependent Electric Pulses Induced Resistive (EPIR) switching phenomenon in thin films driven by electric pulses. Thin films of {sub 0.5}Ca{sub 0.5}MnO{sub 3} (manganite) were deposited by PLD on Si substrate. The transport properties at the interface between the film and metallic electrode are characterized in order to study the resistance switching. Sample thermal treatment and electrical field history are important to be considered for get reproducible EPIR effect. Carriers trapping at the interfaces are considered as a possible explanation of our results.

  5. Electrical Resistance Measurement of an Individual Carbon Nanotube

    Institute of Scientific and Technical Information of China (English)

    LIU Jin-Ping; XIAO Cun-Ying; HUANG Xin-Tang

    2005-01-01

    @@ Aiming at the difficulty in the electrical resistance measurement, we develop a simple statistical model for the carbon nanotubes adequately dispersed in available insulated liquid and introduce the concept of "the most probability". Based on this model, we obtain the function between macroscopic resistance R and resistance of an individual nanotube, Ro, from which one can calculate the resistance of an individual nanotube by measuring the macroscopic resistance. By computational simulation, we prove the reliability of the model. Then, we analyse the feasibility of the model when applied to experiment.

  6. Study of electrical resistivity of lithium-indium thin films

    Science.gov (United States)

    Chandra, Gyanesh; Katyal, O. P.

    1984-12-01

    Experimental results are presented on the electrical resistivity of lithium-indium films. The resistivity has been studied as a function of temperature (150-300 K), thickness of the films (570-3300 Å) and concentration of Li (11.0-58.7 at. %). The resistivity is observed to be minimum for samples having a Li concentration of 25 and 50 at. %. In general, resistivity varies linearly with temperature but resistivity versus temperature plot shows two distinct regions which have different slopes, i.e., dρ/dT. The role of lithium in indium-lithium films is discussed.

  7. Four-terminal electrical testing device. [initiator bridgewire resistance

    Science.gov (United States)

    Robinson, Robert L. (Inventor); Graves, Thomas J. (Inventor); Hoffman, William C., III (Inventor)

    1987-01-01

    The invention relates to a four-terminal electrical connector device for testing and measuring unknown resistances of initiators used for starting pyrotechnic events aboard the space shuttle. The testing device minimizes contact resistance degradation effects and so improves the reliability of resistance measurements taken with the device. Separate and independent voltage sensing and current supply circuits each include a pair of socket contacts for mating engagement with the pins of the initiator. The unknown resistance that is measured by the device is the resistance of the bridgewire of the initiator which is required to be between 0.95 and 1.15 ohms.

  8. Electrical resistivity testing for as-built concrete performance assessment of chloride penetration resistance

    OpenAIRE

    Polder, R.B.; Peelen, W.H.A.

    2014-01-01

    The electrical resistivity of concrete can provide information about its transport properties, which is relevant for durability performance. For example, resistivity is inversely proportional to chloride diffusion, at least within similar concrete compositions. A methodology is proposed for on-site assessment of concrete cover resistance against chloride penetration, based on on-site resistivity testing. As such, resistivity testing can extend existing service life approaches to assessing on ...

  9. INORGANIC PLUME DELINEATION USING SURFACE HIGH RESOLUTION ELECTRICAL RESISTIVITY AT THE BC CRIBS & TRENCHES SITE HANFORD

    Energy Technology Data Exchange (ETDEWEB)

    BENECKE, M.W.

    2007-05-29

    A surface resistivity survey was conducted on the Hanford Site over a waste disposal trench that received a large volume of liquid inorganic waste. The objective of the survey was to map the extent of the plume that resulted from the disposal activities approximately 50 years earlier. The survey included six resistivity transects of at least 200m, where each transect provided two-dimensional profile information of subsurface electrical properties. The results of the survey indicated that a low resistivity plume resides at a depth of approximately 25-44 m below ground surface. The target depth was calibrated with borehole data of pore-water electrical conductivity. Due to the high correlation of the pore-water electrical conductivity to nitrate concentration and the high correlation of measured apparent resistivity to pore-water electrical conductivity, inferences were made that proposed the spatial distribution of the apparent resistivity was due to the distribution of nitrate. Therefore, apparent resistivities were related to nitrate, which was subsequently rendered in three dimensions to show that the nitrate likely did not reach the water table and the bounds of the highest concentrations are directly beneath the collection of waste sites.

  10. Effects of resistive bodies on DC electrical soundings

    Directory of Open Access Journals (Sweden)

    L. Alfano

    1996-06-01

    Full Text Available Some deep DC electrical soundings, performed in alpine and apenninic areas with the continuous polar dipole-dipole spread, show apparent resistivity curves with positive slopes. Measured values of apparent resistivity reach 30000 Wm. Applying the "surface charges" method we developed three dimensional mathematical models, by means of which we can state simple rules for determining the minimum extensions of the deep resistive bodies, fundamental information for a more precise interpretation of the field results.

  11. Slime thickness evaluation of bored piles by electrical resistivity probe

    Science.gov (United States)

    Chun, Ok-Hyun; Yoon, Hyung-Koo; Park, Min-Chul; Lee, Jong-Sub

    2014-09-01

    The bottoms of bored piles are generally stacked with soil particles, both while boreholes are being drilled, and afterward. The stacked soils are called slime, and when loads are applied on the pile, increase the pile settlement. Thus to guarantee the end bearing capacity of bored piles, the slime thickness should be precisely detected. The objective of this study is to suggest a new method for evaluating the slime thickness, using temperature compensated electrical resistivity. Laboratory studies are performed in advance, to estimate and compare the resolution of the electrical resistivity probe (ERP) and time domain reflectometry (TDR). The electrical properties of the ERP and TDR are measured using coaxial type electrodes and parallel type two-wire electrodes, respectively. Penetration tests, conducted in the fully saturated sand-clay mixtures, demonstrate that the ERP produces a better resolution of layer detection than TDR. Thus, field application tests using the ERP with a diameter of 35.7 mm are conducted for the investigation of slime thickness in large diameter bored piles. Field tests show that the slime layers are clearly identified by the ERP: the electrical resistivity dramatically increases at the interface between the slurry and slime layer. The electrical resistivity in the slurry layer inversely correlates with the amount of circulated water. This study suggests that the new electrical resistivity method may be a useful method for the investigation of the slime thickness in bored piles.

  12. Chronic lead exposure reduces junctional resistance at an electrical synapse.

    Science.gov (United States)

    Audesirk, G; Audesirk, T

    1984-01-01

    Both acute and chronic lead exposure have been found to inhibit transmission at chemical synapses, possibly by interfering with inward calcium current. We have found that chronic lead exposure slightly reduces input resistance and greatly reduces the junctional resistance between two strongly electrically coupled neurons in the pond snail Lymnaea stagnalis. The net effect is to increase the strength of electrical coupling. A reduction in gap junctional resistance would also be expected to increase the flow of small molecules between cells. However, Lucifer Yellow injections did not reveal dye-coupling between the cells. Lead exposure also increases the capacitance of the neurons.

  13. Equivalent Resistance in Pulse Electric Current Sintering

    Institute of Scientific and Technical Information of China (English)

    2002-01-01

    The sintering resistance for conductive TiB2 and non-conductive Al2O3 as well as empty die during pulse current sintering were investigated in this paper.Equivalent resistances were measured by current and valtage during sintering the conductive and non-conductive materials in the same conditions.It is found that the current paths for conductive are different from those for non-conductive materials.For non-conductive materials,sintering resistances are influenced by powder sizes and heating rates,which indicates that pulse current has some interaction with non-conductive powders.For conductive TiB2,sintering resistances are influenced by heating rates and ball-milling time,which indicates the effect of powders activated by spark.

  14. Electrical resistivity of coal-bearing rocks under high temperature and the detection of coal fires using electrical resistance tomography

    Science.gov (United States)

    Shao, Zhenlu; Wang, Deming; Wang, Yanming; Zhong, Xiaoxing; Tang, Xiaofei; Xi, Dongdong

    2016-02-01

    Coal fires are severe hazards to environment, health and safety throughout the world. Efficient and economical extinguishing of these fires requires that the extent of the subsurface coal fires should be delineated. Electrical and electromagnetic methods have been used to detect coal fires in recent years. However, the resistivity change of coal-bearing rocks at high temperature is rarely investigated. The resistivity characteristics of coal fires at different temperatures and depths are seldomly researched as well. In this paper, we present the results of measurements of several coal-bearing rocks' resistivity and permeability under high temperature. Two major causes for the change in resistivity with increasing temperature are recognized, there are the increase of charge carriers and thermal fracturing, of which the first one is probably the dominant cause. A set of 2-D simulations is carried out to compare the relation of resolution and efficiency of coal fires detection to temperature and depth when adopting the electrical resistance tomography. The simulation results show that the resolution and efficiency decrease with the decrease of temperature and the increase of depth. Finally, the electrical resistance tomography is used to delineate coal fires in the Anjialing Open Pit Mine. Most low-resistivity regions are verified as coal-fire areas according to the long-term monitoring of borehole temperature. The results indicate that the electrical resistance tomography can be used as a tool for the detection of coal fires.

  15. Microscopic histological characteristics of soft tissue sarcomas: analysis of tissue features and electrical resistance.

    Science.gov (United States)

    Tosi, A L; Campana, L G; Dughiero, F; Forzan, M; Rastrelli, M; Sieni, E; Rossi, C R

    2017-07-01

    Tissue electrical conductivity is correlated with tissue characteristics. In this work, some soft tissue sarcomas (STS) excised from patients have been evaluated in terms of histological characteristics (cell size and density) and electrical resistance. The electrical resistance has been measured using the ex vivo study on soft tissue tumors electrical characteristics (ESTTE) protocol proposed by the authors in order to study electrical resistance of surgical samples excised by patients in a fixed measurement setup. The measurement setup includes a voltage pulse generator (700 V, 100 µs long at 5 kHz, period 200 µs) and an electrode with 7 needles, 20 mm-long, with the same distance arranged in a fixed hexagonal geometry. In the ESTTE protocol, the same voltage pulse sequence is applied to each different tumor mass and the corresponding resistance has been evaluated from voltage and current recorded by the equipment. For each tumor mass, a histological sample of the volume treated by means of voltage pulses has been taken for histological analysis. Each mass has been studied in order to identify the sarcoma type. For each histological sample, an image at 20× or 40× of magnification was acquired. In this work, the electrical resistance measured for each tumor has been correlated with tissue characteristics like the type, size and density of cells. This work presents a preliminary study to explore possible correlations between tissue characteristics and electrical resistance of STS. These results can be helpful to adjust the pulse voltage intensity in order to improve the electrochemotherapy efficacy on some histotype of STS.

  16. Influence of electrical resistivity and machining parameters on electrical discharge machining performance of engineering ceramics.

    Science.gov (United States)

    Ji, Renjie; Liu, Yonghong; Diao, Ruiqiang; Xu, Chenchen; Li, Xiaopeng; Cai, Baoping; Zhang, Yanzhen

    2014-01-01

    Engineering ceramics have been widely used in modern industry for their excellent physical and mechanical properties, and they are difficult to machine owing to their high hardness and brittleness. Electrical discharge machining (EDM) is the appropriate process for machining engineering ceramics provided they are electrically conducting. However, the electrical resistivity of the popular engineering ceramics is higher, and there has been no research on the relationship between the EDM parameters and the electrical resistivity of the engineering ceramics. This paper investigates the effects of the electrical resistivity and EDM parameters such as tool polarity, pulse interval, and electrode material, on the ZnO/Al2O3 ceramic's EDM performance, in terms of the material removal rate (MRR), electrode wear ratio (EWR), and surface roughness (SR). The results show that the electrical resistivity and the EDM parameters have the great influence on the EDM performance. The ZnO/Al2O3 ceramic with the electrical resistivity up to 3410 Ω·cm can be effectively machined by EDM with the copper electrode, the negative tool polarity, and the shorter pulse interval. Under most machining conditions, the MRR increases, and the SR decreases with the decrease of electrical resistivity. Moreover, the tool polarity, and pulse interval affect the EWR, respectively, and the electrical resistivity and electrode material have a combined effect on the EWR. Furthermore, the EDM performance of ZnO/Al2O3 ceramic with the electrical resistivity higher than 687 Ω·cm is obviously different from that with the electrical resistivity lower than 687 Ω·cm, when the electrode material changes. The microstructure character analysis of the machined ZnO/Al2O3 ceramic surface shows that the ZnO/Al2O3 ceramic is removed by melting, evaporation and thermal spalling, and the material from the working fluid and the graphite electrode can transfer to the workpiece surface during electrical discharge

  17. Influence of electrical resistivity and machining parameters on electrical discharge machining performance of engineering ceramics.

    Directory of Open Access Journals (Sweden)

    Renjie Ji

    Full Text Available Engineering ceramics have been widely used in modern industry for their excellent physical and mechanical properties, and they are difficult to machine owing to their high hardness and brittleness. Electrical discharge machining (EDM is the appropriate process for machining engineering ceramics provided they are electrically conducting. However, the electrical resistivity of the popular engineering ceramics is higher, and there has been no research on the relationship between the EDM parameters and the electrical resistivity of the engineering ceramics. This paper investigates the effects of the electrical resistivity and EDM parameters such as tool polarity, pulse interval, and electrode material, on the ZnO/Al2O3 ceramic's EDM performance, in terms of the material removal rate (MRR, electrode wear ratio (EWR, and surface roughness (SR. The results show that the electrical resistivity and the EDM parameters have the great influence on the EDM performance. The ZnO/Al2O3 ceramic with the electrical resistivity up to 3410 Ω·cm can be effectively machined by EDM with the copper electrode, the negative tool polarity, and the shorter pulse interval. Under most machining conditions, the MRR increases, and the SR decreases with the decrease of electrical resistivity. Moreover, the tool polarity, and pulse interval affect the EWR, respectively, and the electrical resistivity and electrode material have a combined effect on the EWR. Furthermore, the EDM performance of ZnO/Al2O3 ceramic with the electrical resistivity higher than 687 Ω·cm is obviously different from that with the electrical resistivity lower than 687 Ω·cm, when the electrode material changes. The microstructure character analysis of the machined ZnO/Al2O3 ceramic surface shows that the ZnO/Al2O3 ceramic is removed by melting, evaporation and thermal spalling, and the material from the working fluid and the graphite electrode can transfer to the workpiece surface during electrical

  18. Elastic and Electrical Properties Evaluation of Low Resistivity Pays in Malay Basin Clastics Reservoirs

    Science.gov (United States)

    Almanna Lubis, Luluan; Ghosh, Deva P.; Hermana, Maman

    2016-07-01

    The elastic and electrical properties of low resistivity pays clastics reservoirs in Malay Basin are strongly dependent on the complex nature of the clay content, either dispersed or laminated/layered. Estimating the hydrocarbon pore volume from conventional electrical log, i.e. resistivity log, is quite a challenge. The low elastic impedance contrast also found as one of the challenge thus create a problem to map the distribution of the low resistivity reservoirs. In this paper, we evaluate the electrical properties and elastic rock properties to discriminate the pay from the adjacent cap rock or shale. Forward modeling of well log responses including electrical properties are applied to analyze the nature of the possible pays on laminated reservoir rocks. In the implementation of rock properties analysis, several conventional elastic properties are comparatively analyzed for the sensitivity and feasibility analysis on each elastic parameters. Finally, we discussed the advantages of each elastic parameters in detail. In addition, cross-plots of elastic and electrical properties attributes help us in the clear separation of anomalous zone and lithologic properties of sand and shale facies over conventional elastic parameter crossplots attributes. The possible relationship on electrical and elastic properties are discussed for further studies.

  19. Control of combustion area using electrical resistivity method for underground coal gasification

    Institute of Scientific and Technical Information of China (English)

    Selivanova Tatiana; Grebenyuk Igor; Belov Alexey

    2012-01-01

    Underground coal gasification (UCG) is one of the clean technologies to collect heat energy and gases (hydrogen,methane,etc.) in an underground coal seam.It is necessary to further developing environmentally friendly UCG system construction.One of the most important UCG's problems is underground control of combustion area for efficient gas production,estimation of subsidence and gas leakage to the surface.For this objective,laboratory experiments were conducted according to the UCG model to identify the process of combustion cavity development by monitoring the electrical resistivity activity on the coal samples to setup fundamental data for the technology engineering to evaluate combustion area.While burning coal specimens,that had been sampled from various coal deposits,electrical resistivity was monitored.Symmetric four electrodes system (ABMN) of direct and low-frequency current electric resistance method was used.for laboratory resistivity measurement of rock samples.Made research and the results suggest that front-end of electro conductivity activity during heating and combusting of coal specimen depended on heating temperature.Combusting coal electro conductivity has complicated multistage type of change.Electrical resistivity method is expected to be a useful geophysical tool to for evaluation of combustion volume and its migration in the coal seam.

  20. Influence of Water Absorption on Volume Resistivity and the Dielectric Properties of Neat Epoxy Material

    KAUST Repository

    Sulaimani, Anwar Ali

    2014-07-15

    Influence of Water Absorption on the Dielectric Properties and Volume Resistivity of Neat Epoxy Material Anwar Ali Sulaimani Epoxy resins are widely used materials in the industry as electrical insulators, adhesives and in aircrafts structural components because of their high mechanical sti ness, strength and high temperature and chemical resistance properties. But still, the in uence of water uptake due to moisture adsorption is not fully understood as it detrimentally modi es the electrical and chemical properties of the material. Here, we investigate the in uence of water moisture uptake on the neat epoxy material by monitoring the change in the volume resistivity and dielectric properties of epoxy material at three di erent thickness con gurations: 0.250 mm, 0.50 mm and 1 mm thicknesses. Gravimetric analysis was done to monitor the mass uptake behaviour, Volume Resistivity was measured to monitor the change in conductivity of the material, and the dielectric properties were mapped to characterise the type of water mechanism available within the material during two ageing processes of sorption and desorption. Two-stage behaviours of di usion and reaction have been identi ed by the mass uptake analysis. Moreover, the plot of volume resistivity versus mass uptake has indi- cated a non-uniform relationship between the two quantities. However, the analysis of the dielectric spectrum at medium range of frequency and time has showed a change 5 in the dipolar activities and also showed the extent to which the water molecules can be segregated between bounding to the resin or existing as free water.

  1. RESEARCHES ON THE ELECTRICAL RESISTANCE OF CERVICAL MUCUS IN COWS

    Directory of Open Access Journals (Sweden)

    IZABELA MARTIN

    2013-12-01

    Full Text Available To succeed in artificial insemination and to produce the fecundation in cows it isnecessary to have knowledge about optimal time of ovulation. Such possibilityappears using the values of electrical resistance of cervical mucus. The smallestvalues are obtained during the ovulation due to the pH modification influenced by theestrogens. The purpose of the paper was to determine the electrical resistance of thecervical mucus in cows with clinical signs of estrus, depending on females’ age. Also,the electrical resistance of the cervical mucus in cows in different physiologicalstages (pregnant, no pregnant was measured. The ovulation detector DRAMINSKIwas used. This equipment allows to obtained a quickly and precise rapport on thephysiological stage of the cow. It can be detected the cow with atypical ovulation,irregular ovulation. This method improve the insemination efficiency, allowsdetecting early gestation period or the moment of ovulation. All these have a positiveinfluence on the development strategy of the farm and improve the economicperformances.

  2. Electrical Resistance and Magnetoresistance of Modified Carbon Nanotubes

    Directory of Open Access Journals (Sweden)

    T.A. Len

    2014-11-01

    Full Text Available The paper presents the results of the experimental studies of the magnetoresistance and electrical resistance of carbon nanotubes modified with iron and iron oxide. A comprehensive study of the processes, which act with change in the temperature of modified CNTs, is performed. Joint analysis of the structural studies and electrical transport characteristics is enabled to explain new and interesting results. It is established that modification with iron has little effect on the electrical resistance. On the other hand, modification is strongly reflected on the ferromagnetic resistance anisotropy. It is shown that the localization mechanism and anisotropic magnetoresistance are manifested in magnetoresistance. Anisotropic magnetoresistance arises due to the features of magnetization of ferromagnetic phase in an external magnetic field.

  3. Electrical resistance tomography to monitor vadose water movement

    Energy Technology Data Exchange (ETDEWEB)

    Ramirez, A.; Daily, W. (Lawrence Livermore National Lab., CA (United States)); LaBrecque, D. (Arizona Univ., Tucson, AZ (United States))

    1991-09-01

    We report results of one test in which Electrical Resistance Tomography (ERT) was used to map the changes in electrical resistivity in the vadose zone as a function of time while water infiltration occurred. The ERT images were used to infer shape and movement of the infiltration plume in the unsaturated soil. We supplied a continuous water source at a point about 10 feet below the surface (at the end of a shallow screened hole) for only a short time -- 2.5 hours. This pulsed source introduced a slug'' of water whose infiltration was followed to about 60 foot depth during a 23 hour period. The ERT images show resistivity decreases as the water content of the vadose zone increased while water was added to the soil; the resistivity of the soil later increased after the supply of water was cut-off and the induced soil moisture began to subside.

  4. Electrical resistance tomography experiments at the Oregon Graduate Institute

    Science.gov (United States)

    Daily, W.; Ramirez, A.; LaBrecque, D.; Barber, W.

    1995-04-01

    Three controlled experiments were conducted at the Oregon Graduate Institute (OGI) with the purpose of evaluating electrical resistance tomography for imaging underground processes associated with in-situ site assessment and remediation. The OGI facilities are unique: a double-wall tank 10 m square and 5 m deep, filled with river bottom sediments and instrumented for geophysical and hydrological studies. At this facility, liquid contaminants could be released into the confined soil at a scale sufficiently large to represent real-world physical phenomena. In the first test, images of electrical resistivity were made before and during a controlled spill of gasoline into a sandy soil. The primary purpose was to determine if electrical resistivity images could detect the hydrocarbon in either the vadose or saturated zone. Definite changes in electrical resistivity were observed in both the vadose and saturated soils. The effects were an increase in resistivity of as much as 10% above pre-release values. A single resistive anomaly was imaged, directly below the release point, principally within the vadose zone but extending below the phreatic surface. The anomaly remained identifiable in tomograms taken two days after the release ended with clear indications of lateral spreading along the water table. The second test involved electrical resistance measurements before, during, and after air sparging in a saturated soil. The primary purpose was to determine if the electrical images could be used to detect and delineate the extent of the zone influenced by sparging. The images showed an increase of about 20% in resistivity over background values within the sparged zone and the extent of the imaged zone agreed with that inferred from other information. Electrical resistivity tomography measurements were made under a simulated oil storage tank in the third test. Comparison of images taken before and during separate releases of brine and water showed effects of changes

  5. Electrical resistivity of thin metal films

    CERN Document Server

    Wissmann, Peter

    2007-01-01

    The aim of the book is to give an actual survey on the resistivity of thin metal and semiconductor films interacting with gases. We discuss the influence of the substrate material and the annealing treatment of the films, presenting our experimental data as well as theoretical models to calculate the scattering cross section of the conduction electrons in the frame-work of the scattering hypothesis. Main emphasis is laid on the comparison of gold and silver films which exhibit nearly the same lattice structure but differ in their chemical activity. In conclusion, the most important quantity for the interpretation is the surface charging z while the correlation with the optical data or the frustrated IR vibrations seems the show a more material-specific character. Z can be calculated on the basis of the density functional formalism or the self-consistent field approximation using Mulliken’s population analysis.

  6. Health Monitoring of TPS Structures by Measuring Their Electrical Resistance

    Science.gov (United States)

    Preci, Arianit; Herdrich, Georg; Steinbeck, Andreas; Auweter-Kurtz, Monika

    Health Monitoring in aerospace applications becomes an emerging technology leading to the development of systems capable of continuously monitoring structures for damage with minimal human intervention. A promising sensing method to be applied on hot structures and thermal protection systems is the electrical resistance measurement technique, which is barely investigated up to now. This method benefits from the advantageous characteristics of self-monitoring materials, such as carbon fiber-reinforced materials. By measuring the variation of the electrical resistance of these materials information on possibly present mechanical damage can be derived. In order to set up a database on electric properties of relevant materials under relevant conditions and to perform a proof-of-concept for this health monitoring method a facility has been laid out, which allows for the measurement of the electrical resistance of thermal protection system relevant materials at temperatures up to 2000°C. First preliminary measurements of the surface resistance of a graphite sample have been performed and are presented. It has been proven necessary to make some modifications to the setup. Therefore, the remaining measurements with graphite and C/C-SiC samples are subject of further investigation which will be performed in the future.

  7. Electrical resistivity testing for as-built concrete performance assessment of chloride penetration resistance

    NARCIS (Netherlands)

    Polder, R.B.; Peelen, W.H.A.

    2014-01-01

    The electrical resistivity of concrete can provide information about its transport properties, which is relevant for durability performance. For example, resistivity is inversely proportional to chloride diffusion, at least within similar concrete compositions. A methodology is proposed for on-site

  8. Electric Crosstalk Effect in Valence Change Resistive Random Access Memory

    Science.gov (United States)

    Sun, Jing; Wang, Hong; Wu, Shiwei; Song, Fang; Wang, Zhan; Gao, Haixia; Ma, Xiaohua

    2017-08-01

    Electric crosstalk phenomenon in valence change resistive switching memory (VCM) is systematically investigated. When a voltage is applied on the VCM device, an electric field is formed in the isolated region between the devices, which causes the oxygen vacancies in conductive filaments (CFs) to drift apart, leading to a consequent resistance degradation of the neighboring devices. The effects of distance between memory cells, electrodes widths and physical dimensions of CFs on the memory performance are investigated in this work. Furthermore, the strategies to mitigate electric crosstalk effects are developed. According to the simulation results, the crosstalk phenomenon can become more severe as the distance between memory cells or the electrode width decreases. In order to optimize the device performance, it is helpful to control the location of the break points of CFs in the device close to the top electrode. Alternatively, taking the integration density into account, switching materials with a small field accelerated parameter can also contribute to obtaining a stable performance.

  9. Insulin resistance and gray matter volume in neurodegenerative disease.

    Science.gov (United States)

    Morris, J K; Vidoni, E D; Perea, R D; Rada, R; Johnson, D K; Lyons, K; Pahwa, R; Burns, J M; Honea, R A

    2014-06-13

    The goal of this study was to compare insulin resistance in aging and aging-related neurodegenerative diseases, and to determine the relationship between insulin resistance and gray matter volume (GMV) in each cohort using an unbiased, voxel-based approach. Insulin resistance was estimated in apparently healthy elderly control (HC, n=21) and neurodegenerative disease (Alzheimer's disease (AD), n=20; Parkinson's disease (PD), n=22) groups using Homeostasis Model Assessment of Insulin Resistance 2 (HOMA2) and intravenous glucose tolerance test (IVGTT). HOMA2 and GMV were assessed within groups through General Linear Model multiple regression. We found that HOMA2 was increased in both AD and PD compared to the HC group (HC vs. AD, p=0.002, HC vs. PD, p=0.003), although only AD subjects exhibited increased fasting glucose (p=0.005). Furthermore, our voxel-based morphometry analysis revealed that HOMA2 was related to GMV in all cohorts in a region-specific manner (p<0.001, uncorrected). Significant relationships were observed in the medial prefrontal cortex (HC), medial temporal regions (AD), and parietal regions (PD). Finally, the directionality of the relationship between HOMA2 and GMV was disease-specific. Both HC and AD subjects exhibited negative relationships between HOMA2 and brain volume (increased HOMA2 associated with decreased brain volume), while a positive relationship was observed in PD. This cross-sectional study suggests that insulin resistance is increased in neurodegenerative disease, and that individuals with AD appear to have more severe metabolic dysfunction than individuals with PD or PD dementia.

  10. Evaluation and Ranking of Geothermal Resources for Electrical Generation or Electrical Offset in Idaho, Montana, Oregon and Washington. Volume II.

    Energy Technology Data Exchange (ETDEWEB)

    Bloomquist, R. Gordon

    1985-06-01

    This volume contains appendices on: (1) resource assessment - electrical generation computer results; (2) resource assessment summary - direct use computer results; (3) electrical generation (high temperature) resource assessment computer program listing; (4) direct utilization (low temperature) resource assessment computer program listing; (5) electrical generation computer program CENTPLANT and related documentation; (6) electrical generation computer program WELLHEAD and related documentation; (7) direct utilization computer program HEATPLAN and related documentation; (8) electrical generation ranking computer program GEORANK and related documentation; (9) direct utilization ranking computer program GEORANK and related documentation; and (10) life cycle cost analysis computer program and related documentation. (ACR)

  11. Electrical carotid sinus stimulation in treatment resistant arterial hypertension.

    Science.gov (United States)

    Jordan, Jens; Heusser, Karsten; Brinkmann, Julia; Tank, Jens

    2012-12-24

    Treatment resistant arterial hypertension is commonly defined as blood pressure that remains above goal in spite of the concurrent use of three antihypertensive agents of different classes. The sympathetic nervous system promotes arterial hypertension and cardiovascular as well as renal damage, thus, providing a logical treatment target in these patients. Recent physiological studies suggest that baroreflex mechanisms contribute to long-term control of sympathetic activity and blood pressure providing an impetus for the development of electrical carotid sinus stimulators. The concept behind electrical stimulation of baroreceptors or baroreflex afferent nerves is that the stimulus is sensed by the brain as blood pressure increase. Then, baroreflex efferent structures are adjusted to counteract the perceived blood pressure increase. Electrical stimulators directly activating afferent baroreflex nerves were developed years earlier but failed for technical reasons. Recently, a novel implantable device was developed that produces an electrical field stimulation of the carotid sinus wall. Carefully conducted experiments in dogs provided important insight in mechanisms mediating the depressor response to electrical carotid sinus stimulation. Moreover, these studies showed that the treatment success may depend on the underlying pathophysiology of the hypertension. Clinical studies suggest that electrical carotid sinus stimulation attenuates sympathetic activation of vasculature, heart, and kidney while augmenting cardiac vagal regulation, thus lowering blood pressure. Yet, not all patients respond to treatment. Additional clinical trials are required. Patients equipped with an electrical carotid sinus stimulator provide a unique opportunity gaining insight in human baroreflex physiology.

  12. Forensic Assessment on Ground Instability Using Electrical Resistivity Imaging (ERI)

    Science.gov (United States)

    Hazreek, Z. A. M.; Azhar, A. T. S.; Aziman, M.; Fauzan, S. M. S. A.; Ikhwan, J. M.; Aishah, M. A. N.

    2017-02-01

    Electrical resistivity imaging (ERI) was used to evaluate the ground settlement in local scale at housing areas. ERI and Borehole results were used to interpret the condition of the problematic subsurface profile due to its differential stiffness. Electrical resistivity of the subsurface profile was measured using ABEM SAS4000 equipment set. ERI results using electrical resistivity anomaly on subsurface materials resistivity shows the subsurface profile exhibited low (1 - 100 Ωm) and medium (> 100 Ωm) value (ERV) representing weak to firm materials. The occurrences of soft to medium cohesive material (SPT N value = 2 - 7) and stiff cohesive material (SPT N ≥ 8) in local scale has created inconsistency of the ground stability condition. Moreover, it was found that a layer of organic decayed wood (ERV = 43 ˜ 29 Ωm & SPT N = 15 ˜ 9) has been buried within the subsurface profile thus weaken the ground structure and finally promoting to the ground settlement. The heterogeneous of the subsurface material presented using integrated analysis of ERI and borehole data enabled ground settlement in this area to be evaluated. This is the major factor evaluating ground instability in the local scale. The result was applicable to assist in planning a strategy for sustainable ground improvement of local scale in fast, low cost, and large data coverage.

  13. Recent Advances in Electrical Resistance Preheating of Aluminum Reduction Cells

    Science.gov (United States)

    Ali, Mohamed Mahmoud; Kvande, Halvor

    2017-02-01

    There are two mainpreheating methods that are used nowadays for aluminum reduction cells. One is based on electrical resistance preheating with a thin bed of small coke and/or graphite particles between the anodes and the cathode carbon blocks. The other is flame preheating, where two or more gas or oil burners are used. Electrical resistance preheating is the oldest method, but is still frequently used by different aluminum producers. Many improvements have been made to this method by different companies over the last decade. In this paper, important points pertaining to the preparation and preheating of these cells, as well as measurements made during the preheating process and evaluation of the performance of the preheating, are illustrated. The preheating times of these cells were found to be between 36 h and 96 h for cell currents between 176 kA and 406 kA, while the resistance bed thickness was between 13 mm and 60 mm. The average cathode surface temperature at the end of the preheating was usually between 800°C and 950°C. The effect of the preheating methods on cell life is unclear and no quantifiable conclusions can be drawn. Some works carried out in the mathematical modeling area are also discussed. It is concluded that there is a need for more studies with real situations for preheated cells on the basis of actual measurements. The expected development in electrical resistance preheating of aluminum reduction cells is also summarized.

  14. Scenario Evaluator for Electrical Resistivity survey pre-modeling tool

    Science.gov (United States)

    Terry, Neil; Day-Lewis, Frederick D.; Robinson, Judith L.; Slater, Lee D; Halford, Keith J.; Binley, Andrew; Lane, John; Werkema, Dale

    2017-01-01

    Geophysical tools have much to offer users in environmental, water resource, and geotechnical fields; however, techniques such as electrical resistivity imaging (ERI) are often oversold and/or overinterpreted due to a lack of understanding of the limitations of the techniques, such as the appropriate depth intervals or resolution of the methods. The relationship between ERI data and resistivity is nonlinear; therefore, these limitations depend on site conditions and survey design and are best assessed through forward and inverse modeling exercises prior to field investigations. In this approach, proposed field surveys are first numerically simulated given the expected electrical properties of the site, and the resulting hypothetical data are then analyzed using inverse models. Performing ERI forward/inverse modeling, however, requires substantial expertise and can take many hours to implement. We present a new spreadsheet-based tool, the Scenario Evaluator for Electrical Resistivity (SEER), which features a graphical user interface that allows users to manipulate a resistivity model and instantly view how that model would likely be interpreted by an ERI survey. The SEER tool is intended for use by those who wish to determine the value of including ERI to achieve project goals, and is designed to have broad utility in industry, teaching, and research.

  15. Electrical resistance tomography for imaging the spatial distribution of moisture in pavement sections

    Energy Technology Data Exchange (ETDEWEB)

    Buettner, M.; Ramirez, A.; Daily, W.

    1995-11-08

    Electrical Resistance Tomography (ERT) was used to image spatial moisture distribution and movement in pavement sections during an infiltration test. ERT is a technique for determining the electrical resistivity distribution within a volume from measurement of injected currents and the resulting electrical potential distribution on the surface. The transfer resistance (ratio of potential to injected current) data are inverted using an algorithm based on a finite element forward solution which is iteratively adjusted in a least squares sense until the measured and calculated transfer resistances agree to within some predetermined value. Four arrays of ERT electrodes were installed in vertical drill holes 1.22 m (4 ft) placed at the comers of a square 61 cm (2 ft) on a side into a pavement section which is used for a truck scale ramp on U.S. Highway 99 just north of Sacramento, CA. Water was introduced slowly into the pavement through a shallow hole in the center of this pattern and ERT data were collected in various planes as the water infiltrated into the pavement and subgrade materials over a period of several hours. The ERT data were inverted, and the resulting images show (1) the basic structure of the pavement section and (2) the movement of water through the image planes as a function of time during infiltration. An interesting result is that the water does not appear to drain from the section toward the shoulder as had been expected based on the design.

  16. Measuring the electrical resistivity and contact resistance of vertical carbon nanotube bundles for application as interconnects

    Energy Technology Data Exchange (ETDEWEB)

    Chiodarelli, Nicolo' ; Li, Yunlong; Arstila, Kai; Richard, Olivier; Cott, Daire J; Heyns, Marc; De Gendt, Stefan; Groeseneken, Guido; Vereecken, Philippe M [IMEC, Kapeldreef 75, Leuven, B-3001 (Belgium); Masahito, Sugiura; Kashiwagi, Yusaku, E-mail: chiodarn@imec.be [Tokyo Electron Ltd, Technology Development Center, 650 Mitsuzawa, Hosaka-cho, Nirasaki, Yamanashi 407-0192 (Japan)

    2011-02-25

    Carbon nanotubes (CNT) are known to be materials with potential for manufacturing sub-20 nm high aspect ratio vertical interconnects in future microchips. In order to be successful with respect to contending against established tungsten or copper based interconnects, though, CNT must fulfil their promise of also providing low electrical resistance in integrated structures using scalable integration processes fully compatible with silicon technology. Hence, carefully engineered growth and integration solutions are required before we can fully exploit their potentialities. This work tackles the problem of optimizing a CNT integration process from the electrical perspective. The technique of measuring the CNT resistance as a function of the CNT length is here extended to CNT integrated in vertical contacts. This allows extracting the linear resistivity and the contact resistance of the CNT, two parameters to our knowledge never reported separately for vertical CNT contacts and which are of utmost importance, as they respectively measure the quality of the CNT and that of their metal contacts. The technique proposed allows electrically distinguishing the impact of each processing step individually on the CNT resistivity and the CNT contact resistance. Hence it constitutes a powerful technique for optimizing the process and developing CNT contacts of superior quality. This can be of relevant technological importance not only for interconnects but also for all those applications that rely on the electrical properties of CNT grown with a catalytic chemical vapor deposition method at low temperature.

  17. THE INVESTIGATION OF CONTACT RESISTANCE CHARACTERISTICS ON ELECTRICAL CONTACTS USED IN COAL MINES

    Institute of Scientific and Technical Information of China (English)

    郭凤仪; 王其平; 孙鹤旭; 乔和; 张静

    1997-01-01

    Based on the electrical contact and arc theory, the experiments on contact resistance characteristics of electrical contacts are carried out, by analyzing the experimental results, some conclusions of contact resistance characteristics have been obtained in this paper.

  18. Analysis and forecast of electrical distribution system materials. Final report. Volume III. Appendix

    Energy Technology Data Exchange (ETDEWEB)

    Love, C G

    1976-08-23

    These appendixes are referenced in Volume II of this report. They contain the detailed electrical distribution equipment requirements and input material requirements forecasts. Forecasts are given for three electric energy usage scenarios. Also included are data on worldwide reserves and demand for 30 raw materials required for the manufacture of electrical distribution equipment.

  19. Electric-field effects in resistive oxides: facts and artifacts

    Directory of Open Access Journals (Sweden)

    Reisner G. M.

    2013-01-01

    Full Text Available Striking non-linear conductivity effects induced by surprisingly low electric-fields in charge-ordered oxides, were reported variously as dielectric breakdown, charge-order collapse, depinning of charge-density-waves or other electronic effects. Our pulsed and d.c. I-V measurements on resistive oxides show that non-linear conductivity of electronic origin at low electric-fields is a rare phenomenon. In the majority of cases we detected no deviations from linearity in pulsed I-V characteristics under fields up to E ~ 500 V/cm. Current-controlled negative-differential-resistance (NDR and hysteresis were found in d.c. measurements at fields that decrease with increasing temperatures, a behavior typical of Joule heating in materials with negative temperature coefficient of resistivity. For the d.c. I-V characteristics of our samples exhibiting NDR, we found a rather unexpected correlation between ρ(Em - the resistivity at maximum field (at the onset of NDR and ρ(E=0 – the ohmic resistivity. The data points for ρ(Em versus ρ(E=0 obtained from such characteristics of 13 samples (8 manganites, 4 nickelates and one multiferroic at various ambient temperatures, plotted together on a log-log scale, follow closely a linear dependence with slope one that spans more than five orders of magnitude. This dependence is reproduced by several simple models.

  20. High precision measurement of electrical resistance across endothelial cell monolayers.

    Science.gov (United States)

    Tschugguel, W; Zhegu, Z; Gajdzik, L; Maier, M; Binder, B R; Graf, J

    1995-05-01

    Effects of vasoactive agonists on endothelial permeability was assessed by measurement of transendothelial electrical resistance (TEER) of human umbilical vein endothelial cells (HUVECs) grown on porous polycarbonate supports. Because of the low values of TEER obtained in this preparation (< 5 omega cm2) a design of an Ussing type recording chamber was chosen that provided for a homogeneous electric field across the monolayer and for proper correction of series resistances. Precision current pulses and appropriate rates of sampling and averaging of the voltage signal allowed for measurement of < 0.1 omega resistance changes of the endothelium on top of a 21 omega series resistance of the support and bathing fluid layers. Histamine (10 microM) and thrombin (10 U/ml) induced an abrupt and substantial decrease of TEER, bradykinin (1 microM) was less effective, PAF (380 nM) and LTC4 (1 microM) had no effect. TEER was also reduced by the calcium ionophore A-23187 (10 microM). The technique allows for measurements of TEER in low resistance monolayer cultures with high precision and time resolution. The results obtained extend previous observations in providing quantitative data on the increase of permeability of HUVECs in response to vasoactive agonists.

  1. Characterization of fracture aperture field heterogeneity by electrical resistance measurement.

    Science.gov (United States)

    Boschan, A; Ippolito, I; Chertcoff, R; Hulin, J P; Auradou, H

    2011-04-01

    We use electrical resistance measurements to characterize the aperture field in a rough fracture. This is done by performing displacement experiments using two miscible fluids of different electrical resistivity and monitoring the time variation of the overall fracture resistance. Two fractures have been used: their complementary rough walls are identical but have different relative shear displacements which create "channel" or "barrier" structures in the aperture field, respectively parallel or perpendicular to the mean flow velocity U(→). In the "channel" geometry, the resistance displays an initial linear variation followed by a tail part which reflects the velocity contrast between slow and fast flow channels. In the "barrier" geometry, a change in the slope between two linear zones suggests the existence of domains of different characteristic aperture along the fracture. These variations are well reproduced analytically and numerically using simple flow models. For each geometry, we present then a data inversion procedure that allows one to extract the key features of the heterogeneity from the resistance measurement. Copyright © 2010 Elsevier B.V. All rights reserved.

  2. Application of the Electrical Resistivity Tomography to the stone content estimation

    Science.gov (United States)

    Xie, Y.; Chanzy, André; Courdier, Florence; Mariotte, Nicolas; Rachedi, Sabrina

    2009-04-01

    Electrical Resistivity of the soil is regarded as a proxy for many soil properties as structure, moisture content or bedrock depth. The stone content is important for the trees as a large number of stones in the soil restrict the volume of soil that is available for roots to uptake water and nutrients. The potential of ERT for estimating the stone content is evaluated by regarding the stony soil as a two-exponent mixture with stones, which are less conductive, suspend in a conductive matrix. The resistivity of the two components was obtained separately by 2-electrode and 4-electrode methods. On the basis of the resistivity of the soils and the stones, the stone size effect on the effective resistivity was addressed using numerical modeling by Windows based resistivity modeling program RES2DINV and RES3DINV. The effective resistivity at different stone content was calculated by inverting the simulated potential which reproduces a linear panel experiment. The results demonstrate that stone size effect is not very significant. Field measurements were carried out at Mt-Ventoux and l'Issole, located in south of France in the Provence Region. The sites stand in Karstic terrain with soils having high and variable stone content and lying on a bed rock which can be found very close to the surface. Pits were dug and their stone content (volumetric fraction) was estimated. There is an apparent relation between the effective resistivity values extracted from the ERT inversion results and the stone content, the tendency are in good agreement with theoretical results. However, exceptions are found with relatively higher stone content and lower ER value, it can be explained by 3D effect from soil characteristics surrounding the pit. An error assessment in stone content is given according to the resistivity contrast between phases (stones and soil) and the variability in electric resistivity within each phase.

  3. Electrical Resistivity of an Elasmobranch's Ampullary Jelly in Varying Electric and Magnetic Fields

    Science.gov (United States)

    Brown, Brandon; Hughes, Mary E.

    2001-03-01

    The ampullae of Lorenzini are believed to function as the electroreceptive organs in elasmobranch fishes. Though the entire excised organs have been the subject of electrical transport measurements, the jelly that fills the ampullae -- composed primarily of glycoproteins with proteins and dissolved salts -- has received less scrutiny. The specific electromagnetic properties of the jelly contribute to electroreception, and we hope to supply useful parameters to modeling efforts via precise electrical characterization. We report preliminary resistivity measurements from ampullary jelly removed, post mortem, from an adult triaenodon obesus (white-tip reef shark). We present data over a broad range of applied electrical currents. We also present data of the resistivity as a function of applied magnetic field strength.

  4. Electrical resistivity of V-Cr-Ti alloys

    Energy Technology Data Exchange (ETDEWEB)

    Zinkle, S.J.; Gubbi, A.N.; Eatherly, W.S. [Oak Ridge National Lab., TN (United States)

    1997-04-01

    Room temperature electrical resistivity measurements have been performed on vanadium alloys containing 3-6%Cr and 3-6%Ti in order to evaluate the microstructural stability of these alloys. A nonlinear dependence on Cr and Ti concentration was observed, which suggests that either short range ordering or solute precipitation (perhaps in concert with interstitial solute clustering) has occurred in V-6Cr-6Ti.

  5. Development of a Landslide Monitoring System using Electrical Resistivity Tomography

    Science.gov (United States)

    Hen-Jones, R. M.; Hughes, P. N.; Glendinning, S.; Gunn, D.; Chambers, J.; Stirling, R.

    2015-12-01

    Current assessments of slope stability rely on the use of point sensors, the results of which are often difficult to interpret, have relatively high associated installation and maintenance costs, and do not provide large-area coverage. A new system is currently under development, based on the use of integrated geophysical - geotechnical sensors to monitor ground water conditions via electrical resistivity tomography. This study presents the results of an in-situ electrical resistivity tomography survey, gathered over a two year investigation period at a full-scale clay test embankment in Northumberland, UK. The 3D resistivity array comprised 288 electrodes, at 0.7m grid spacing, covering an area of approximately 90 m2. The first year of investigation involved baseline data collection, followed by a second year which saw a series of deliberate interventions targeted at weakening the slope, to determine whether corresponding geotechnical property changes would be reflected in resistivity images derived from ERT. These interventions included the manual extension of four tension cracks already present in the slope, and the installation of a sprinkler system, eight months later. Laboratory methods were employed to derive a system of equations for relating resistivity to geotechnical parameters more directly relevant to slope stability, including moisture content, suction and shear strength. These equations were then applied to resistivity data gathered over the baseline and intervention periods, yielding geotechnical images of the subsurface which compared well with in-situ geotechnical point sensors. During the intervention period, no slope movement was recorded, however, tensiometers at 0.5 m and 1.0 m depths showed elevated pore pressures, with positive pressures being recorded at depths less than 0.5 m. Resistivity images were successful in capturing the extension of the tension cracks, and in identifying the development of a potential shear failure plane as water

  6. Drought resistance of four grasses using pressure-volume curve

    Institute of Scientific and Technical Information of China (English)

    HE Xingdong; CONG Peifang; GAO Yubao; LU Jianguo; WANG Haitao; XUE Pingping; ZHANG Xu

    2007-01-01

    Pressure-volume curve (PV curve) technique is a major method for studying critical plant water potential and critical tissue water content when plasmolysis takes place.In the present study,a mathematical solution method is put forward to obtain parameters based on the PV curve.The calculated results for the parameters ofLolium perenne,Festuca arundinacea,Leymus chinensis and Stipa krylovii indicated that the mathematical solution method is convenient for actual research compared with the graphical method.Further analysis of the calculations suggested that drought resistance decreased in the following order:S.krylovii > F.arundinacea and L.chinensis > L.perenne.

  7. S/EV 92 (Solar and Electric Vehicles): Proceedings. Volume 1

    Energy Technology Data Exchange (ETDEWEB)

    1992-12-01

    Volume I of these proceedings presents current research on solar and electric powered vehicles. Both fundamental and advanced concepts concerning electric vehicles are presented. The use of photovoltaic cells in electric vehicles and in a broader sense as a means of power generation are discussed. Information on electric powered fleets and races is included. And policy and regulations, especially pertaining to air quality and air pollution abatement are presented.

  8. Low Temperature Electrical Resistivity Studies in Lead Thin Films

    Directory of Open Access Journals (Sweden)

    A.W. Manjunath

    2013-07-01

    Full Text Available Thin lead films of thickness, 100 nm, 150 nm, 200 nm and 250 nm have been deposited using electron beam evaporation technique at room temperature onto glass substrates under high vacuum conditions. Films were investigated for electrical resistivity at low temperatures from 77 K to 300 K. Resistivity variation with temperature indicates transition from metallic to semiconductor behavior. Transition tem-perature increased with increasing film thickness. Temperature coefficient of resistance in the metallic re-gion has been determined for all the four films. Using Arrhenius relation, activation energy for conduction in metallic region has been determined. Mott’s small polaron hopping model has been employed to deter-mine activation energy in the semiconducting region. In a film of 250 nm thick, deviation from Mott’s small polaron hopping model for below 100 K was noted and that has been considered under Mott’s variable range hopping model. The complete understanding of electrical properties of Pb films has been necessitat-ed by the fact that the band gap in CdS decreases when Pb is incorporated into it, which in turn can be used to fabricated large efficient solar cells. It is for the first time that lead films of the present thickness have been investigated for low temperature resistivity.

  9. 3D electrical resistivity inversion using prior spatial shape constraints

    Institute of Scientific and Technical Information of China (English)

    Li Shu-Cai; Nie Li-Chao; Liu Bin; Song Jie; Liu Zheng-Yu; Su Mao-Xin; Xu Lei

    2013-01-01

    To minimize the number of solutions in 3D resistivity inversion, an inherent problem in inversion, the amount of data considered have to be large and prior constraints need to be applied. Geological and geophysical data regarding the extent of a geological anomaly are important prior information. We propose the use of shape constraints in 3D electrical resistivity inversion. Three weighted orthogonal vectors (a normal and two tangent vectors) were used to control the resistivity differences at the boundaries of the anomaly. The spatial shape of the anomaly and the constraints on the boundaries of the anomaly are thus established. We incorporated the spatial shape constraints in the objective function of the 3D resistivity inversion and constructed the 3D resistivity inversion equation with spatial shape constraints. Subsequently, we used numerical modeling based on prior spatial shape data to constrain the direction vectors and weights of the 3D resistivity inversion. We established a reasonable range between the direction vectors and weights, and verified the feasibility and effectiveness of using spatial shape prior constraints in reducing excessive structures and the number of solutions. We applied the prior spatially shape-constrained inversion method to locate the aquifer at the Guangzhou subway. The spatial shape constraints were taken from ground penetrating radar data. The inversion results for the location and shape of the aquifer agree well with drilling data, and the number of inversion solutions is significantly reduced.

  10. Detecting Damage in Ceramic Matrix Composites Using Electrical Resistance

    Science.gov (United States)

    Smith, Craig E.; Gyekenyesi, Andrew

    2011-01-01

    The majority of damage in SiC/SiC ceramic matrix composites subjected to monotonic tensile loads is in the form of distributed matrix cracks. These cracks initiate near stress concentrations, such as 90 deg fiber tows or large matrix pores and continue to accumulate with additional stress until matrix crack saturation is achieved. Such damage is difficult to detect with conventional nondestructive evaluation techniques (immersion ultrasonics, x-ray, etc.). Monitoring a specimen.s electrical resistance change provides an indirect approach for monitoring matrix crack density. Sylramic-iBN fiber- reinforced SiC composites with a melt infiltrated (MI) matrix were tensile tested at room temperature. Results showed an increase in resistance of more than 500% prior to fracture, which can be detected either in situ or post-damage. A relationship between resistance change and matrix crack density was also determined.

  11. Detecting Cracks in Ceramic Matrix Composites by Electrical Resistance

    Science.gov (United States)

    Smith, Craig; Gyekenyesi, Andrew

    2011-01-01

    The majority of damage in SiC/SiC ceramic matrix composites subjected to monotonic tensile loads is in the form of distributed matrix cracks. These cracks initiate near stress concentrations, such as 90o fiber tows or large matrix pores and continue to accumulate with additional stress until matrix crack saturation is achieved. Such damage is difficult to detect with conventional nondestructive evaluation techniques (immersion ultrasonics, x-ray, etc.). Monitoring a specimen.s electrical resistance change provides an indirect approach for monitoring matrix crack density. Sylramic-iBN fiber- reinforced SiC composites with a melt infiltrated (MI) matrix were tensile tested at room temperature. Results showed an increase in resistance of more than 500% prior to fracture, which can be detected either in situ or post-damage. A relationship between resistance change and matrix crack density was also determined.

  12. Anomalous temperature dependence of the electrical resistivity of molten Sb

    Institute of Scientific and Technical Information of China (English)

    2001-01-01

    Using the d.c. four-probe method, the electrical resistivity of high-purity liquid Sb has been accurately measured as functions of temperature. It is observed that the resistivity of liquid Sb changes abnormally with increasing temperature, which is very different from that of simple liquid metals. Based on the reported structure factor at several temperatures, the results obtained in this work have been discussed and interpreted qualitatively according to Ziman theory. The analysis suggests that the existence of shortrange order structure near the melting point can account for the abnormal phenomenon observed in the resistivity of liquid Sb, in which semimetal-metal transaction takes place in the melting process. At the same time, the progress of the structure change of liquid Sb with temperature has also been pointed out.``

  13. Electrical resistivity tomography investigations on a paleoseismological trenching study

    Science.gov (United States)

    Berge, Meriç Aziz

    2014-10-01

    Two-dimensional electrical resistivity tomography (ERT) investigation was performed in a paleoseismological trenching study. Data acquisition strategies such as the selection of electrode configuration and electrode intervals of ERT application were investigated in this paper. The ERT results showed that the Wenner and Wenner-Schlumberger arrays yielded similar results for subsurface characteristics whereas the DD array provided slightly different results. The combined usage of these arrays produced satisfactory images of the subsurface resistivity distribution. In addition, the electrode spacing tests revealed that a suitable interpretation of subsurface geology can be obtained from a 5 m electrode interval. However, a suitable trenching location defined by successful 2D resistivity models was obtained for 1 m electrode spacing. Therefore, the comparison of the trench and ERT results was also possible. The results of trenching and ERT studies substantially support each other.

  14. Investigating preferential flow processes in soils using anisotropy in electrical resistivity

    Science.gov (United States)

    Al-Hazaimay, S.; Huisman, J. A.; Zimmermann, E.; Kemna, A.; Vereecken, H.

    2012-12-01

    Macropores occupy a small volume fraction of the pore space in the vadose zone. Water and solutes can quickly bypass the vadose zone through these macropores in a process known as macropore preferential flow. In the last few decades, many efforts were made to improve understanding the macropore preferential flow processes because of their importance in transporting agrochemicals and contaminants to the groundwater. Unfortunately, very few measurement methods provide insights into these preferential flow processes. In this context, the objective of this study is to evaluate whether anisotropy in electrical resistivity can be used to identify the existence of flow in macropores and perhaps even to characterize the exchange between macropores and bulk soil. In a first step, infiltration into a soil column with an artificial macropore was simulated using the HYDRUS software package that solves the pseudo three-dimensional axisymmetric Richards equation. The simulated temporal development of the resistivity anisotropy was obtained by solving the Poisson equation in MATLAB after converting the simulated water content distributions to electrical resistivity distributions. At the beginning of the simulation, a small anisotropy ratio was simulated because of the presence of the empty ('deactivated') macropore in the moist matrix. As soon as the infiltration process started, macropore flow occurred and both the horizontal and vertical resistivity decreased strongly. However, the vertical and horizontal resistivity reacted differently because of the presence of the conductive ('activated') macropore, which led to anisotropy in the resistivity. As soon as infiltration into the macropore stopped, water re-distributed from the macropore to the matrix domain and contrasts in electrical resistivity decreased within the column. To verify the simulation results in the laboratory, we measured the temporal dynamics of the anisotropy in resistivity during water infiltration into a soil

  15. Electrical Capacitance Volume Tomography with High-Contrast Dielectrics

    Science.gov (United States)

    Nurge, Mark

    2010-01-01

    The Electrical Capacitance Volume Tomography (ECVT) system has been designed to complement the tools created to sense the presence of water in nonconductive spacecraft materials, by helping to not only find the approximate location of moisture but also its quantity and depth. The ECVT system has been created for use with a new image reconstruction algorithm capable of imaging high-contrast dielectric distributions. Rather than relying solely on mutual capacitance readings as is done in traditional electrical capacitance tomography applications, this method reconstructs high-resolution images using only the self-capacitance measurements. The image reconstruction method assumes that the material under inspection consists of a binary dielectric distribution, with either a high relative dielectric value representing the water or a low dielectric value for the background material. By constraining the unknown dielectric material to one of two values, the inverse math problem that must be solved to generate the image is no longer ill-determined. The image resolution becomes limited only by the accuracy and resolution of the measurement circuitry. Images were reconstructed using this method with both synthetic and real data acquired using an aluminum structure inserted at different positions within the sensing region. The cuboid geometry of the system has two parallel planes of 16 conductors arranged in a 4 4 pattern. The electrode geometry consists of parallel planes of copper conductors, connected through custom-built switch electronics, to a commercially available capacitance to digital converter. The figure shows two 4 4 arrays of electrodes milled from square sections of copper-clad circuit-board material and mounted on two pieces of glass-filled plastic backing, which were cut to approximately square shapes, 10 cm on a side. Each electrode is placed on 2.0-cm centers. The parallel arrays were mounted with the electrode arrays approximately 3 cm apart. The open ends

  16. Changes in plasma volume and baroreflex function following resistance exercise

    Science.gov (United States)

    Ploutz, L. L.; Tatro, D. L.; Dudley, G. A.; Convertino, V. A.

    1993-01-01

    The dynamics of change in plasma volume (PV) and baroreflex responses have been reported over 24 h immediately following maximal cycle exercise. The purpose of this study was to determine if PV and baroreflex showed similar changes for 24 h after resistance exercise. Eight men were studied on 2 test days, 1 week apart. On 1 day, per cent change (% delta) in PV was estimated at 0,3, and 6 h after resistance exercise using haematocrit and haemoglobin. Baseline PV was measured 24 h after exercise using Evans blue dye. The carotid baroreceptor-cardiac reflex response was measured before, and 3, 6, 9, 12, and 24 h post-exercise. Each subject performed six sets of the bench press and leg press with 10 repetitions per set with a load that induced failure within each set. On a control day, the protocol was used without exercise. Plasma volume did not change during the control day. There was a 20% decrease in PV immediately post-exercise; the recovery of the PV was rapid and complete within 3 h. PV was 20% greater 24 h post-exercise than on the control day. There were no differences in any of the baroreflex measurements. Therefore, it is suggested that PV shifts may occur without altering baroreflex sensitivity.

  17. Connection equation and shaly-sand correction for electrical resistivity

    Science.gov (United States)

    Lee, Myung W.

    2011-01-01

    Estimating the amount of conductive and nonconductive constituents in the pore space of sediments by using electrical resistivity logs generally loses accuracy where clays are present in the reservoir. Many different methods and clay models have been proposed to account for the conductivity of clay (termed the shaly-sand correction). In this study, the connectivity equation (CE), which is a new approach to model non-Archie rocks, is used to correct for the clay effect and is compared with results using the Waxman and Smits method. The CE presented here requires no parameters other than an adjustable constant, which can be derived from the resistivity of water-saturated sediments. The new approach was applied to estimate water saturation of laboratory data and to estimate gas hydrate saturations at the Mount Elbert well on the Alaska North Slope. Although not as accurate as the Waxman and Smits method to estimate water saturations for the laboratory measurements, gas hydrate saturations estimated at the Mount Elbert well using the proposed CE are comparable to estimates from the Waxman and Smits method. Considering its simplicity, it has high potential to be used to account for the clay effect on electrical resistivity measurement in other systems.

  18. The study of mudrocks resistivity in Northwestern Peninsula Malaysia using electrical resistivity survey

    Science.gov (United States)

    Hisham, Hazrul; Muztaza, Nordiana Mohd; Jia, Teoh Ying

    2017-07-01

    Mudrock is a type of sedimentary rock whose original constituents are clays and muds. Mudrocks are fine grained siliciclastic which include mudstone and claystone depending on the grain size. The colour of mudstone is a function of its minerology content and geochemistry processes. One common sedimentary structure of mudrocks is lamination due to variations in grain size and composition changes. The importance of mudrocks is as a mixture for cement and to produce brick used for building structure. This research emphasizes on the resistivity value of mudrocks; claystone and mudstone which exist in northwestern of Peninsula Malaysia. Mudstone of Kubang Pasu Formation, red mudstone and grey mudstone of Chepor Member and claystone of Semanggol Formation were chose as the study area as each of the mudrock was formed in a different environmental condition. Electrical resistivity survey was conducted on top of the outcrops using Wenner - Schlumberger array with 1.5 m and 1 m electrode spacing with respect to localities. The data was processed using Res2Dinv software to get the inversion model resistivity and the results were imported to Surfer10 software for labelling purposes. The mudstone resistivity value of Kubang Pasu Formation formed by depositional of calm water gives resistivity value from 20 - 120 Ωm. The red mudstone of Chepor Member formed at high oxidation environment gives resistivity value of 15 - 100 Ωm contrast to grey mudstone which formed under low oxidizing condition gives 120 - 500 Ωm resistivity value. The claystone of Semanggol Formation formed from shallow depositional environment gives resistivity value from 400 - 1000 Ωm. As a conclusion, electrical resistivity survey was successfully applied in differentiating the type of mudrocks. Also, mudrocks formed from different depositional environment gives different values of resistivity.

  19. Detecting the Resistivity Distribution of Carbon Fiber Reinforced Concrete by Electrical Resistance Tomography Method

    Institute of Scientific and Technical Information of China (English)

    Xu Dongliang; Li Zhuoqiu; Song Xianhui; Lü Yong

    2006-01-01

    According to the principle of electrical resistance tomography (ERT), the resistivity distribution of the carbon fiber reinforced concrete (CFRC) in the sensing field can be measured by injecting exciting current and measuring the voltage on the sensor electrode arrays installed on the surface of the object Therefore, measurement of the resistivity distribution of CFRC is divided into first measuring the boundary conditions and then inversely computing the resistivity distribution. To reach this goal, an ERT system was constructed, which is composed of a sensor array unit, a data acquisition unit and an image reconstruction unit. Simulations of static ERT was performed on set-ups with many objects spread in a homogeneous background, and a simulation of dynamic ERT was also done on a rectangular board, the resistivity of which was changed within a small domain of it. Then, the resistivity distribution of a CFRC sample with a circlar hole as the target was detected by the ERT system. Simulation and experimental results show that the reconstructed ERT image reflects the resistivity distribution or the resistivity change of CFRC structure well. Especially, a small change in resistivity can be identified from the reconstructed images in the simulation of dynamic ERT images.

  20. Evaluation of the radiation resistance of electrical insulation materials

    Science.gov (United States)

    Perrin, Sh.; Schönbacher, H.; Tavlet, M.; Widler, R.

    2002-12-01

    The qualification of insulating materials for electrical cables is often accomplished according to the IEC 60544 standard of the International Electrotechnical Commission. The mechanical properties of the polymeric insulators are tested prior and after irradiation at relatively high dose rates. To assess the ageing of selected materials under realistic service conditions, usually at lower dose rate, an IEC Working Group has proposed extrapolation methods (IEC 61244-2), one of which is applied here for a cable sheathing material from Huber+Suhner. The method is found to be suitable to compare radiation resistance data of different materials irradiated under different conditions.

  1. Nuclear electric propulsion mission engineering study. Volume 2: Final report

    Science.gov (United States)

    1973-01-01

    Results of a mission engineering analysis of nuclear-thermionic electric propulsion spacecraft for unmanned interplanetary and geocentric missions are summarized. Critical technologies associated with the development of nuclear electric propulsion (NEP) are assessed, along with the impact of its availability on future space programs. Outer planet and comet rendezvous mission analysis, NEP stage design for geocentric and interplanetary missions, NEP system development cost and unit costs, and technology requirements for NEP stage development are studied.

  2. The influence of temperature on the electrical resistivity of the cellular polypropylene and the effect of activation energy.

    Science.gov (United States)

    Vila, Floran; Dhima, Pranvera; Mandija, Florian

    2013-01-01

    In this paper, we determine the surface and volume electrical resistivity of the 50 μm thick cellular polypropylen (VHD50), for the temperature range 393-453 K. For this we use a contemporary methodology, which consist of a voltage measurement across the sample, with a known current flowing through it. This methodology includes a three-electrode system, which allows us to estimate the resistivity of the samples, based on their corresponding total resistances. The electric fields applied for a time interval of 1 min are of the order of 200 kVm (-1). The order of magnitude of surface and volume electrical resistivity is 10(13) Ω and 10(11) Ωm, respectively. For both types of the resistivity, the temperature dependence is an increasing or decreasing exponential function, depending on the type of the activation energy, (its average value for the temperature range mentioned above is 41,20 kJmol (-1)), totally confirmed by the corresponding theoretical interpretation, conditioned by the ionic conduction. The methodology and equipment used, as well as the satisfying accordance with the results, found out directly or indirectly with the consulted literature, confirm the high accuracy of experimental measurements.

  3. Improvement of resistance to hydrogen induced cracking in electric resistance welded pipes fabricated with slit coils

    Science.gov (United States)

    Hong, Hyun Uk; Lee, Jong Bong; Choi, Ho Jin

    2009-02-01

    The optimization of electric resistance welding (ERW) conditions was studied to improve the resistance to hydrogen induced cracking (HIC) at the bondline in small diameter API X60 ERW pipes fabricated with slit coils. The results show that HIC is initiated preferentially at the elongated Si, Mn and Al-rich oxide inclusions, normally known as a penetrator on the bondline. However, no evidence was found of any centerline segregation effect. The HIC ratio increases with the fraction of penetrators at the bondline, regardless of the degrees of center segregation. Furthermore, for a satisfactory level of HIC resistance, the fraction of penetrators must be less than 0.03 % and most of the penetrators should be circular-shaped. The design of experimental (DOE) method was used to determine the optimum ERW condition for minimization of the penetrator ratio. Finally, guideline is suggested for the optimum ERW condition for achieving excellent HIC resistance.

  4. Nuclear electric propulsion mission engineering study. Volume 1: Executive summary

    Science.gov (United States)

    1973-01-01

    Results of a mission engineering analysis of nuclear-thermionic electric propulsion spacecraft for unmanned interplanetary and geocentric missions are summarized. Critical technologies associated with the development of nuclear electric propulsion (NEP) are assessed. Outer planet and comet rendezvous mission analysis, NEP stage design for geocentric and interplanetary missions, NEP system development cost and unit costs, and technology requirements for NEP stage development are studied. The NEP stage design provides both inherent reliability and high payload mass capability. The NEP stage and payload integration was found to be compatible with the space shuttle.

  5. Three dimensional modeling and inversion of Borehole-surface Electrical Resistivity Data

    Science.gov (United States)

    Zhang, Y.; Liu, D.; Liu, Y.; Qin, M.

    2013-12-01

    After a long time of exploration, many oil fields have stepped into the high water-cut period. It is sorely needed to determining the oil-water distribution and water flooding front. Borehole-surface electrical resistivity tomography (BSERT) system is a low-cost measurement with wide measuring scope and small influence on the reservoir. So it is gaining more and more application in detecting water flooding areas and evaluating residual oil distribution in oil fields. In BSERT system, current is connected with the steel casing of the observation well. The current flows along the long casing and transmits to the surface through inhomogeneous layers. Then received electric potential difference data on the surface can be used to inverse the deep subsurface resistivity distribution. This study presents the 3D modeling and inversion method of electrical resistivity data. In an extensive literature, the steel casing is treated as a transmission line current source with infinite small radius and constant current density. However, in practical multi-layered formations with different resistivity, the current density along the casing is not constant. In this study, the steel casing is modeled by a 2.5e-7 ohm-m physical volume that the casing occupies in the finite element mesh. Radius of the casing can be set to a little bigger than the true radius, and this helps reduce the element number and computation time. The current supply point is set on the center of the top surface of the physical volume. The homogeneous formation modeling result shows the same precision as the transmission line current source model. The multi-layered formation modeling result shows that the current density along the casing is high in the low-resistivity layer, and low in the high-resistivity layer. These results are more reasonable. Moreover, the deviated and horizontal well can be simulated as simple as the vertical well using this modeling method. Based on this forward modeling method, the

  6. Fault mechanism analysis and simulation for continuity resistance test of electrical components in aircraft engine

    Science.gov (United States)

    Shi, Xudong; Yin, Yaping; Wang, Jialin; Sun, Zhaorong

    2017-01-01

    A large number of electrical components are used in civil aircraft engines, whose electrical circuits are usually intricate and complicated. Continuity resistance is an important parameter for the operating state of electrical components. Electrical continuity fault has serious impact on the reliability of the aircraft engine. In this paper, mathematical models of electrical components are established, and simulation is made by Simulink to analyze the electrical continuity fault.

  7. Diagnosis of the heating effect on the electrical resistivity of Ouargla (Algeria) dunes sand using XRD patterns and FTIR spectra

    Science.gov (United States)

    Mechri, Mohammed Laïd; Chihi, Smaïl; Mahdadi, Naouia; Beddiaf, Samiha

    2017-01-01

    XRD patterns and FTIR spectra have shown that dunes sand of Ouargla's region, in its natural state, is formed of a high percentage of quartz, gypsum and very low percentage of kaolinite and hematite, in addition to some organic compounds. The electrical resistivity of the natural sand has been measured, it was 6 × 1014 Ω cm. Six samples of the sand were heated separately at 200, 400, 600, 800, 1000 and 1200 °C. The XRD patterns and FTIR spectra of these samples were carried out. On the other hand, the electrical resistivities of these samples have been measured. The change of the electrical resistivity with heat shows a nonlinear behavior. The heated sample of sand at 200 °C has lost some water. Most of the gypsum in the 200 °C heated sample has transformed into anhydrite, and the rest has transformed into bassanite, and its electrical resistivity has fallen down to 3.5 × 1014 Ω cm. By heating at 400 °C, the gypsum has lost all its water and it has transformed entirely to anhydrite, and its electrical resistivity became 6.75 × 1012 Ω cm, it has the lowest measured resistivity. At 600 °C and 800 °C, in addition to anhydrite, the kaolinite transformed to meta-kaolin due to the continuous breaking of OH bond and formation of water vapor, and the electrical resistivity increased to (1.5-1.9) × 1014 Ω cm. Heating at 1000 °C leads to the initiation of the interaction between anhydrite and quartz, the wollastonite appears, and the meta-kaolin transforms to aluminum-silicon and cristobalite. The wollastonite is a good electrical insulator. It raises the electrical resistivity of sand to 2.6 × 1014 Ω cm. The heating at 1200 °C makes all anhydrite to interact with quartz due to the increasing of volume of wollastonite, the anhydrite disappears completely, the quartz transforms into cristobalite. The cristobalite increases due to the dissociation of aluminium-silicon into mullite and cristobalite, as well as the transformation of quartz into cristobalite at

  8. Monitoring Damage Accumulation in Ceramic Matrix Composites Using Electrical Resistivity

    Science.gov (United States)

    Smith, Craig E.; Morscher, Gregory N.; Xia, Zhenhai H.

    2008-01-01

    The electric resistance of woven SiC fiber reinforced SiC matrix composites were measured under tensile loading conditions. The results show that the electrical resistance is closely related to damage and that real-time information about the damage state can be obtained through monitoring of the resistance. Such self-sensing capability provides the possibility of on-board/in-situ damage detection and accurate life prediction for high-temperature ceramic matrix composites. Woven silicon carbide fiber-reinforced silicon carbide (SiC/SiC) ceramic matrix composites (CMC) possess unique properties such as high thermal conductivity, excellent creep resistance, improved toughness, and good environmental stability (oxidation resistance), making them particularly suitable for hot structure applications. In specific, CMCs could be applied to hot section components of gas turbines [1], aerojet engines [2], thermal protection systems [3], and hot control surfaces [4]. The benefits of implementing these materials include reduced cooling air requirements, lower weight, simpler component design, longer service life, and higher thrust [5]. It has been identified in NASA High Speed Research (HSR) program that the SiC/SiC CMC has the most promise for high temperature, high oxidation applications [6]. One of the critical issues in the successful application of CMCs is on-board or insitu assessment of the damage state and an accurate prediction of the remaining service life of a particular component. This is of great concern, since most CMC components envisioned for aerospace applications will be exposed to harsh environments and play a key role in the vehicle s safety. On-line health monitoring can enable prediction of remaining life; thus resulting in improved safety and reliability of structural components. Monitoring can also allow for appropriate corrections to be made in real time, therefore leading to the prevention of catastrophic failures. Most conventional nondestructive

  9. Using Electrical Simulation Software to Understand Electrical Quantities in Resistive Circuits

    Directory of Open Access Journals (Sweden)

    André Schwantes

    2016-02-01

    Full Text Available This paper describes the development and application of a workshop presented for high school physics teachers, in order to apply the use of electrical simulation software for teaching the basics of resistive circuits. The workshop was developed aiming at the use of active learning strategies and the concepts of David Ausubel’s Meaningful Learning theory. These activities workshops were developed in a practical way, using the electrical simulation software to illustrate a scenario where students are encouraged to engage more actively in their learning. As a result of this workshop, an increase in the importance of the use of new technologies in the classroom was evidenced when used in accordance with the teaching-learning methodologies that promote a more active participation of students.

  10. RESISTANCE EFFECT OF ELECTRIC DOUBLE LAYER ON LIQUID FLOW IN MICROCHANNEL

    Institute of Scientific and Technical Information of China (English)

    GONG Lei; WU Jian-kang

    2006-01-01

    Poisson-Boltzmann equation for EDL (electric double layer) and NavierStokes equation for liquid flows were numerically solved to investigate resistance effect of electric double layer on liquid flow in microchannel. The dimension analysis indicates that the resistance effect of electric double layer can be estimated by an electric resistance number, which is proportional to the square of the liquid dielectric constant and the solid surface zeta potential, and inverse-proportional to the liquid dynamic viscosity, electric conductivity and the square of the channel width. An "electric current density balancing" (ECDB) condition was proposed to evaluate the flow-induced streaming potential,instead of conventional "electric current balancing" (ECB) condition which may induce spurious local backflow in neighborhood of the solid wall of the microchannel. The numerical results of the flow rate loss ratio and velocity profile are also given to demonstrate the resistance effect of electric double layer in microchannel.

  11. Estimating long-term durability parameters based on electrical resistivity measurements

    OpenAIRE

    Silva, Joel; Jalali, Said; Ferreira, Rui Miguel

    2006-01-01

    Concrete's electrical resistivity is one of the main parameters controlling the initiation and propagation of reinforcement corrosion. It is common knowledge that concrete electrical resistivity is mainly dependent on the porosity, temperature and the moisture content. This research work studies the possible relationship between concrete electrical resistivity and compressive strength of concrete. It is intended to evaluate the possibility of predicting the strength gain of concrete at a give...

  12. A new electric method for non-invasive continuous monitoring of stroke volume and ventricular volume-time curves

    Directory of Open Access Journals (Sweden)

    Konings Maurits K

    2012-08-01

    Full Text Available Abstract Background In this paper a new non-invasive, operator-free, continuous ventricular stroke volume monitoring device (Hemodynamic Cardiac Profiler, HCP is presented, that measures the average stroke volume (SV for each period of 20 seconds, as well as ventricular volume-time curves for each cardiac cycle, using a new electric method (Ventricular Field Recognition with six independent electrode pairs distributed over the frontal thoracic skin. In contrast to existing non-invasive electric methods, our method does not use the algorithms of impedance or bioreactance cardiography. Instead, our method is based on specific 2D spatial patterns on the thoracic skin, representing the distribution, over the thorax, of changes in the applied current field caused by cardiac volume changes during the cardiac cycle. Since total heart volume variation during the cardiac cycle is a poor indicator for ventricular stroke volume, our HCP separates atrial filling effects from ventricular filling effects, and retrieves the volume changes of only the ventricles. Methods ex-vivo experiments on a post-mortem human heart have been performed to measure the effects of increasing the blood volume inside the ventricles in isolation, leaving the atrial volume invariant (which can not be done in-vivo. These effects have been measured as a specific 2D pattern of voltage changes on the thoracic skin. Furthermore, a working prototype of the HCP has been developed that uses these ex-vivo results in an algorithm to decompose voltage changes, that were measured in-vivo by the HCP on the thoracic skin of a human volunteer, into an atrial component and a ventricular component, in almost real-time (with a delay of maximally 39 seconds. The HCP prototype has been tested in-vivo on 7 human volunteers, using G-suit inflation and deflation to provoke stroke volume changes, and LVot Doppler as a reference technique. Results The ex-vivo measurements showed that ventricular filling

  13. Site Characterization during Bridge Foundation Construction Using Electrical Resistivity Tomography

    Directory of Open Access Journals (Sweden)

    Aleksandra V. Varnavina

    2016-07-01

    Full Text Available A shallow underground water-filled cavity was encountered in limestone bedrock during the construction of a new column footing for the Gasconade River Bridge over Interstate 44. Five electrical resistivity tomography (ERT profiles and borehole control were acquired in immediate proximity to the existing and the new column footings in order to assess the integrity of the rock beneath the foundation columns and characterize the encountered cavity. Two parallel southwest- northeast trending fracture zones were identified on the acquired ERT profiles and competent rock was differentiated from more extensively fractured rock. The volumetric extent of the void was mapped based on the interpretation of the ERT, borehole and injected grout data. A conceptual model for the development of the water-filled cavity was proposed.

  14. A Prototype System for Time-Lapse Electrical Resistivity Tomographies

    Directory of Open Access Journals (Sweden)

    Raffaele Luongo

    2012-01-01

    Full Text Available A prototype system for time-lapse acquisition of 2D electrical resistivity tomography (ERT and time domain reflectometry (TDR measurements was installed in a test site affected by a landslide in Basilicata region (southern Italy. The aim of the system is to monitor in real-time the rainwater infiltration into the soil and obtain information about the variation of the water content in the first layers of the subsoil and the possible influence of this variation on landslide activity. A rain gauge placed in the test site gives information on the rainfall intensity and frequency and suggests the acquisition time interval. The installed system and the preliminary results are presented in this paper.

  15. Soil Moisture Monitoring using Surface Electrical Resistivity measurements

    Science.gov (United States)

    Calamita, Giuseppe; Perrone, Angela; Brocca, Luca; Straface, Salvatore

    2017-04-01

    The relevant role played by the soil moisture (SM) for global and local natural processes results in an explicit interest for its spatial and temporal estimation in the vadose zone coming from different scientific areas - i.e. eco-hydrology, hydrogeology, atmospheric research, soil and plant sciences, etc... A deeper understanding of natural processes requires the collection of data on a higher number of points at increasingly higher spatial scales in order to validate hydrological numerical simulations. In order to take the best advantage of the Electrical Resistivity (ER) data with their non-invasive and cost-effective properties, sequential Gaussian geostatistical simulations (sGs) can be applied to monitor the SM distribution into the soil by means of a few SM measurements and a densely regular ER grid of monitoring. With this aim, co-located SM measurements using mobile TDR probes (MiniTrase), and ER measurements, obtained by using a four-electrode device coupled with a geo-resistivimeter (Syscal Junior), were collected during two surveys carried out on a 200 × 60 m2 area. Two time surveys were carried out during which Data were collected at a depth of around 20 cm for more than 800 points adopting a regular grid sampling scheme with steps (5 m) varying according to logistic and soil compaction constrains. The results of this study are robust due to the high number of measurements available for either variables which strengthen the confidence in the covariance function estimated. Moreover, the findings obtained using sGs show that it is possible to estimate soil moisture variations in the pedological zone by means of time-lapse electrical resistivity and a few SM measurements.

  16. Epikarstic storage and doline structural characterization with time-lapse geophysics (seismic refraction & electrical resistivity)

    Science.gov (United States)

    Valois, R.; Galibert, P.; Guérin, R.; Mendes, M.; Plagnes, V.

    2011-12-01

    Karst formations are one of the most challenging environments in terms of groundwater, engineering and environmental issues. Geophysical methods can provide useful subsurface information in karst regions concerning groundwater vulnerability assessment, exploitation or hazard estimation. First, dolines are studied as preferential pathways for the protection of karstic aquifer in south France. Geophysics helps to characterize lateral and underground morphologies of such objects and is able to detect doline hidden by the soil cover too. Electrical resistivity and seismic refraction tomographies provide information about dolines filling and could help to propose a genesis scenario. Time-lapse resistivity measurements show that the studied doline is more vulnerable to infiltration on its sides than at its centre. The epikarst could be defined as a perched aquifer above the massive carbonate rocks; it constitutes a highly fractured zone, which water stock capacities. So, the epikarst was investigated with 3D seismic refraction and results show an important velocity anisotropy linked to the fracturing and weathering of the dolostone. The 3D model presents also some large heterogeneities: a corridor with highly weathered dolostone and an unweathered pinnacle. The corridor is probably situated on vertical joints, which have conducted aggressive water. The associated weathering with residual weathered-rock keeping its initial volume could create a "ghost-rock" corridor. So, the epikarst in the dolostones of the Causse du Larzac (France) seems to be composed by "ghost-rock" developed around a specific direction of fractures. Time-lapse electrical resistivity and seismic refraction velocity were carried out on this epikarst to observe the influence of water saturation on the measurements. The results show important variations for both seismic and electrical methods and are localized in the first 6 m: in the weathered zone. So, time-lapse measurements could more easily identify

  17. Electric potential and apparent resistivity in rocks containing non-uniformly distributed cracks

    Institute of Scientific and Technical Information of China (English)

    2001-01-01

    In this paper, the formula of electric field distribution and ground apparent resistivity of high resistance rock medi-um containing low resistance crack are deduced and simulated. The result shows that interstitial parameters, such as buried depth, scale, strike, and real resistivity, etc, have influence on observation and computing result of apparent resistivity. This study provided a useful foundation for earthquake prediction using apparent resistivity method.

  18. Applications of electrical resistance tomography to subsurface environmental restoration

    Energy Technology Data Exchange (ETDEWEB)

    Ramirez, A.L. [Lawrence Livermore National Lab., CA (United States); Daily, W.D.

    1994-11-15

    We are developing a new imaging technique, Electrical Resistance Tomography (ERT), to map subsurface liquids as flow occurs during natural or clean-up processes and to map geologic structure. Natural processes (such as surface water infiltrating the vadose zone) and man-induced processes (such as tank leaks and clean-up processes such as steam injection), can create changes in a soil`s electrical properties that are readily measured. We have conducted laboratory and a variety of field experiments to investigate the capabilities and limitations of ERT for imaging underground structures and processes. In the last four years we have used ERT to successfully monitor several field processes including: a subsurface steam injection process (for VOC removal), an air injection process (below the water table) for VOC removal, water infiltration through the vadose zone, radio-frequency heating, ohmic heating, and tank and pond leaks. The information derived from ERT can be used by remediation projects to: detect and locate leaks, determine the effectiveness of clean-up processes, select appropriate clean-up alternatives, and to verify the installation and performance of subsurface barriers.

  19. Infiltration front monitoring using 3D Electrical Resistivity Tomography

    Science.gov (United States)

    Oxarango, Laurent; Audebert, Marine; Guyard, Helene; Clement, Remi

    2016-04-01

    The electrical resistivity tomography (ERT) geophysical method is commonly used to identify the spatial distribution of electrical resisitivity in the soil at the field scale. Recent progress in commercial acquisition systems allows repeating fast acquisitions (10 min) in order to monitor a 3D dynamic phenomenon. Since the ERT method is sensitive to moisture content variations, it can thus be used to delineate the infiltration shape during water infiltration. In heterogeneous conditions, the 3D infiltration shape is a crucial information because it could differ significantly from the homogeneous behavior. In a first step, the ERT method is validated at small scale ( 10m). Two examples of leachate injection monitoring in municipal solid waste landfills are used to put forward benefits and limitations of the ERT-MICS method. Effective infiltration porosities in a range between 3% and 8% support the assumption of a flow in heterogeneous media. Audebert, M., R. Clément, N. Touze-Foltz, T. Günther, S. Moreau, and C. Duquennoi (2014), Time-lapse ERT interpretation methodology for leachate injection monitoring based on multiple inversions and a clustering strategy (MICS), Journal of Applied Geophysics, 111, 320-333. Keywords: ERT, infiltration front, field survey

  20. Renewable Electricity Futures Study. Volume 1: Exploration of High-Penetration Renewable Electricity Futures

    Energy Technology Data Exchange (ETDEWEB)

    Mai, T.; Wiser, R.; Sandor, D.; Brinkman, G.; Heath, G.; Denholm, P.; Hostick, D.J.; Darghouth, N.; Schlosser, A.; Strzepek, K.

    2012-06-01

    The Renewable Electricity Futures (RE Futures) Study investigated the challenges and impacts of achieving very high renewable electricity generation levels in the contiguous United States by 2050. The analysis focused on the sufficiency of the geographically diverse U.S. renewable resources to meet electricity demand over future decades, the hourly operational characteristics of the U.S. grid with high levels of variable wind and solar generation, and the potential implications of deploying high levels of renewables in the future. RE Futures focused on technical aspects of high penetration of renewable electricity; it did not focus on how to achieve such a future through policy or other measures. Given the inherent uncertainties involved with analyzing alternative long-term energy futures as well as the multiple pathways that might be taken to achieve higher levels of renewable electricity supply, RE Futures explored a range of scenarios to investigate and compare the impacts of renewable electricity penetration levels (30%-90%), future technology performance improvements, potential constraints to renewable electricity development, and future electricity demand growth assumptions. RE Futures was led by the National Renewable Energy Laboratory (NREL) and the Massachusetts Institute of Technology (MIT).

  1. Renewable Electricity Futures Study. Volume 1. Exploration of High-Penetration Renewable Electricity Futures

    Energy Technology Data Exchange (ETDEWEB)

    Hand, M. M. [National Renewable Energy Lab. (NREL), Golden, CO (United States); Baldwin, S. [U.S. Dept. of Energy, Washington, DC (United States); DeMeo, E. [Renewable Energy Consulting, Chicago, IL (United States); Reilly, J. M. [Massachusetts Inst. of Technology (MIT), Cambridge, MA (United States); Mai, T. [National Renewable Energy Lab. (NREL), Golden, CO (United States); Arent, D. [Joint Inst. for Strategic Energy Analysis, Boulder, CO (United States); Porro, G. [National Renewable Energy Lab. (NREL), Golden, CO (United States); Meshek, M. [National Renewable Energy Lab. (NREL), Golden, CO (United States); Sandor, D. [National Renewable Energy Lab. (NREL), Golden, CO (United States)

    2012-06-15

    The Renewable Electricity Futures (RE Futures) Study investigated the challenges and impacts of achieving very high renewable electricity generation levels in the contiguous United States by 2050. The analysis focused on the sufficiency of the geographically diverse U.S. renewable resources to meet electricity demand over future decades, the hourly operational characteristics of the U.S. grid with high levels of variable wind and solar generation, and the potential implications of deploying high levels of renewables in the future. RE Futures focused on technical aspects of high penetration of renewable electricity; it did not focus on how to achieve such a future through policy or other measures. Given the inherent uncertainties involved with analyzing alternative long-term energy futures as well as the multiple pathways that might be taken to achieve higher levels of renewable electricity supply, RE Futures explored a range of scenarios to investigate and compare the impacts of renewable electricity penetration levels (30%–90%), future technology performance improvements, potential constraints to renewable electricity development, and future electricity demand growth assumptions. RE Futures was led by the National Renewable Energy Laboratory (NREL) and the Massachusetts Institute of Technology (MIT). Learn more at the RE Futures website. http://www.nrel.gov/analysis/re_futures/

  2. Renewable Electricity Futures Study. Volume 4: Bulk Electric Power Systems. Operations and Transmission Planning

    Energy Technology Data Exchange (ETDEWEB)

    Milligan, Michael [National Renewable Energy Lab. (NREL), Golden, CO (United States); Ela, Erik [National Renewable Energy Lab. (NREL), Golden, CO (United States); Hein, Jeff [National Renewable Energy Lab. (NREL), Golden, CO (United States); Schneider, Thomas [National Renewable Energy Lab. (NREL), Golden, CO (United States); Brinkman, Gregory [National Renewable Energy Lab. (NREL), Golden, CO (United States); Denholm, Paul [National Renewable Energy Lab. (NREL), Golden, CO (United States)

    2012-06-15

    The Renewable Electricity Futures (RE Futures) Study investigated the challenges and impacts of achieving very high renewable electricity generation levels in the contiguous United States by 2050. The analysis focused on the sufficiency of the geographically diverse U.S. renewable resources to meet electricity demand over future decades, the hourly operational characteristics of the U.S. grid with high levels of variable wind and solar generation, and the potential implications of deploying high levels of renewables in the future. RE Futures focused on technical aspects of high penetration of renewable electricity; it did not focus on how to achieve such a future through policy or other measures. Given the inherent uncertainties involved with analyzing alternative long-term energy futures as well as the multiple pathways that might be taken to achieve higher levels of renewable electricity supply, RE Futures explored a range of scenarios to investigate and compare the impacts of renewable electricity penetration levels (30%–90%), future technology performance improvements, potential constraints to renewable electricity development, and future electricity demand growth assumptions. RE Futures was led by the National Renewable Energy Laboratory (NREL) and the Massachusetts Institute of Technology (MIT). Learn more at the RE Futures website. http://www.nrel.gov/analysis/re_futures/

  3. Renewable Electricity Futures Study. Volume 4: Bulk Electric Power Systems: Operations and Transmission Planning

    Energy Technology Data Exchange (ETDEWEB)

    Milligan, M.; Ela, E.; Hein, J.; Schneider, T.; Brinkman, G.; Denholm, P.

    2012-06-01

    The Renewable Electricity Futures (RE Futures) Study investigated the challenges and impacts of achieving very high renewable electricity generation levels in the contiguous United States by 2050. The analysis focused on the sufficiency of the geographically diverse U.S. renewable resources to meet electricity demand over future decades, the hourly operational characteristics of the U.S. grid with high levels of variable wind and solar generation, and the potential implications of deploying high levels of renewables in the future. RE Futures focused on technical aspects of high penetration of renewable electricity; it did not focus on how to achieve such a future through policy or other measures. Given the inherent uncertainties involved with analyzing alternative long-term energy futures as well as the multiple pathways that might be taken to achieve higher levels of renewable electricity supply, RE Futures explored a range of scenarios to investigate and compare the impacts of renewable electricity penetration levels (30%-90%), future technology performance improvements, potential constraints to renewable electricity development, and future electricity demand growth assumptions. RE Futures was led by the National Renewable Energy Laboratory (NREL) and the Massachusetts Institute of Technology (MIT).

  4. Renewable Electricity Futures Study. Volume 3: End-Use Electricity Demand

    Energy Technology Data Exchange (ETDEWEB)

    Hostick, D.; Belzer, D.B.; Hadley, S.W.; Markel, T.; Marnay, C.; Kintner-Meyer, M.

    2012-06-01

    The Renewable Electricity Futures (RE Futures) Study investigated the challenges and impacts of achieving very high renewable electricity generation levels in the contiguous United States by 2050. The analysis focused on the sufficiency of the geographically diverse U.S. renewable resources to meet electricity demand over future decades, the hourly operational characteristics of the U.S. grid with high levels of variable wind and solar generation, and the potential implications of deploying high levels of renewables in the future. RE Futures focused on technical aspects of high penetration of renewable electricity; it did not focus on how to achieve such a future through policy or other measures. Given the inherent uncertainties involved with analyzing alternative long-term energy futures as well as the multiple pathways that might be taken to achieve higher levels of renewable electricity supply, RE Futures explored a range of scenarios to investigate and compare the impacts of renewable electricity penetration levels (30%-90%), future technology performance improvements, potential constraints to renewable electricity development, and future electricity demand growth assumptions. RE Futures was led by the National Renewable Energy Laboratory (NREL) and the Massachusetts Institute of Technology (MIT).

  5. Renewable Electricity Futures Study. Volume 3. End-Use Electricity Demand

    Energy Technology Data Exchange (ETDEWEB)

    Hostick, Donna [Pacific Northwest National Lab. (PNNL), Richland, WA (United States); Belzer, David B. [Pacific Northwest National Lab. (PNNL), Richland, WA (United States); Hadley, Stanton W. [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States); Markel, Tony [National Renewable Energy Lab. (NREL), Golden, CO (United States); Marnay, Chris [Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States); Kintner-Meyer, Michael [Pacific Northwest National Lab. (PNNL), Richland, WA (United States)

    2012-06-15

    The Renewable Electricity Futures (RE Futures) Study investigated the challenges and impacts of achieving very high renewable electricity generation levels in the contiguous United States by 2050. The analysis focused on the sufficiency of the geographically diverse U.S. renewable resources to meet electricity demand over future decades, the hourly operational characteristics of the U.S. grid with high levels of variable wind and solar generation, and the potential implications of deploying high levels of renewables in the future. RE Futures focused on technical aspects of high penetration of renewable electricity; it did not focus on how to achieve such a future through policy or other measures. Given the inherent uncertainties involved with analyzing alternative long-term energy futures as well as the multiple pathways that might be taken to achieve higher levels of renewable electricity supply, RE Futures explored a range of scenarios to investigate and compare the impacts of renewable electricity penetration levels (30%–90%), future technology performance improvements, potential constraints to renewable electricity development, and future electricity demand growth assumptions. RE Futures was led by the National Renewable Energy Laboratory (NREL) and the Massachusetts Institute of Technology (MIT). Learn more at the RE Futures website. http://www.nrel.gov/analysis/re_futures/

  6. Renewable Electricity Futures Study. Volume 2: Renewable Electricity Generation and Storage Technologies

    Energy Technology Data Exchange (ETDEWEB)

    Augustine, C.; Bain, R.; Chapman, J.; Denholm, P.; Drury, E.; Hall, D.G.; Lantz, E.; Margolis, R.; Thresher, R.; Sandor, D.; Bishop, N.A.; Brown, S.R.; Cada, G.F.; Felker, F.

    2012-06-01

    The Renewable Electricity Futures (RE Futures) Study investigated the challenges and impacts of achieving very high renewable electricity generation levels in the contiguous United States by 2050. The analysis focused on the sufficiency of the geographically diverse U.S. renewable resources to meet electricity demand over future decades, the hourly operational characteristics of the U.S. grid with high levels of variable wind and solar generation, and the potential implications of deploying high levels of renewables in the future. RE Futures focused on technical aspects of high penetration of renewable electricity; it did not focus on how to achieve such a future through policy or other measures. Given the inherent uncertainties involved with analyzing alternative long-term energy futures as well as the multiple pathways that might be taken to achieve higher levels of renewable electricity supply, RE Futures explored a range of scenarios to investigate and compare the impacts of renewable electricity penetration levels (30%-90%), future technology performance improvements, potential constraints to renewable electricity development, and future electricity demand growth assumptions. RE Futures was led by the National Renewable Energy Laboratory (NREL) and the Massachusetts Institute of Technology (MIT).

  7. Renewable Electricity Futures Study. Volume 2. Renewable Electricity Generation and Storage Technologies

    Energy Technology Data Exchange (ETDEWEB)

    Augustine, Chad [National Renewable Energy Lab. (NREL), Golden, CO (United States); Bain, Richard [National Renewable Energy Lab. (NREL), Golden, CO (United States); Chapman, Jamie [Texas Tech Univ., Lubbock, TX (United States); Denholm, Paul [National Renewable Energy Lab. (NREL), Golden, CO (United States); Drury, Easan [National Renewable Energy Lab. (NREL), Golden, CO (United States); Hall, Douglas G. [Idaho National Lab. (INL), Idaho Falls, ID (United States); Lantz, Eric [National Renewable Energy Lab. (NREL), Golden, CO (United States); Margolis, Robert [National Renewable Energy Lab. (NREL), Golden, CO (United States); Thresher, Robert [National Renewable Energy Lab. (NREL), Golden, CO (United States); Sandor, Debra [National Renewable Energy Lab. (NREL), Golden, CO (United States); Bishop, Norman A. [Knight Piesold, Denver, CO (United States); Brown, Stephen R. [HDR/DTA, Portland, ME (Untied States); Cada, Glenn F. [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States); Felker, Fort [National Renewable Energy Lab. (NREL), Golden, CO (United States); Fernandez, Steven J. [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States); Goodrich, Alan C. [National Renewable Energy Lab. (NREL), Golden, CO (United States); Hagerman, George [Virginia Polytechnic Inst. and State Univ. (Virginia Tech), Blacksburg, VA (United States); Heath, Garvin [National Renewable Energy Lab. (NREL), Golden, CO (United States); O' Neil, Sean [Ocean Renewable Energy Coalition, Portland, OR (United States); Paquette, Joshua [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States); Tegen, Suzanne [National Renewable Energy Lab. (NREL), Golden, CO (United States); Young, Katherine [National Renewable Energy Lab. (NREL), Golden, CO (United States)

    2012-06-15

    The Renewable Electricity Futures (RE Futures) Study investigated the challenges and impacts of achieving very high renewable electricity generation levels in the contiguous United States by 2050. The analysis focused on the sufficiency of the geographically diverse U.S. renewable resources to meet electricity demand over future decades, the hourly operational characteristics of the U.S. grid with high levels of variable wind and solar generation, and the potential implications of deploying high levels of renewables in the future. RE Futures focused on technical aspects of high penetration of renewable electricity; it did not focus on how to achieve such a future through policy or other measures. Given the inherent uncertainties involved with analyzing alternative long-term energy futures as well as the multiple pathways that might be taken to achieve higher levels of renewable electricity supply, RE Futures explored a range of scenarios to investigate and compare the impacts of renewable electricity penetration levels (30%–90%), future technology performance improvements, potential constraints to renewable electricity development, and future electricity demand growth assumptions. RE Futures was led by the National Renewable Energy Laboratory (NREL) and the Massachusetts Institute of Technology (MIT). Learn more at the RE Futures website. http://www.nrel.gov/analysis/re_futures/

  8. Contribution of 3-D electrical resistivity tomography for landmines detection

    Directory of Open Access Journals (Sweden)

    M. Metwaly

    2008-12-01

    Full Text Available Landmines are a type of inexpensive weapons widely used in the pre-conflicted areas in many countries worldwide. The two main types are the metallic and non-metallic (mostly plastic landmines. They are most commonly investigated by magnetic, ground penetrating radar (GPR, and metal detector (MD techniques. These geophysical techniques however have significant limitations in resolving the non-metallic landmines and wherever the host materials are conductive. In this work, the 3-D electric resistivity tomography (ERT technique is evaluated as an alternative and/or confirmation detection system for both landmine types, which are buried in different soil conditions and at different depths. This can be achieved using the capacitive resistivity imaging system, which does not need direct contact with the ground surface. Synthetic models for each case have been introduced using metallic and non-metallic bodies buried in wet and dry environments. The inversion results using the L1 norm least-squares optimization method tend to produce robust blocky models of the landmine body. The dipole axial and the dipole equatorial arrays tend to have the most favorable geometry by applying dynamic capacitive electrode and they show significant signal strength for data sets with up to 5% noise. Increasing the burial depth relative to the electrode spacing as well as the noise percentage in the resistivity data is crucial in resolving the landmines at different environments. The landmine with dimension and burial depth of one electrode separation unit is over estimated while the spatial resolutions decrease as the burial depth and noise percentage increase.

  9. Contribution of 3-D electrical resistivity tomography for landmines detection

    Science.gov (United States)

    Metwaly, M.; El-Qady, G.; Matsushima, J.; Szalai, S.; Al-Arifi, N. S. N.; Taha, A.

    2008-12-01

    Landmines are a type of inexpensive weapons widely used in the pre-conflicted areas in many countries worldwide. The two main types are the metallic and non-metallic (mostly plastic) landmines. They are most commonly investigated by magnetic, ground penetrating radar (GPR), and metal detector (MD) techniques. These geophysical techniques however have significant limitations in resolving the non-metallic landmines and wherever the host materials are conductive. In this work, the 3-D electric resistivity tomography (ERT) technique is evaluated as an alternative and/or confirmation detection system for both landmine types, which are buried in different soil conditions and at different depths. This can be achieved using the capacitive resistivity imaging system, which does not need direct contact with the ground surface. Synthetic models for each case have been introduced using metallic and non-metallic bodies buried in wet and dry environments. The inversion results using the L1 norm least-squares optimization method tend to produce robust blocky models of the landmine body. The dipole axial and the dipole equatorial arrays tend to have the most favorable geometry by applying dynamic capacitive electrode and they show significant signal strength for data sets with up to 5% noise. Increasing the burial depth relative to the electrode spacing as well as the noise percentage in the resistivity data is crucial in resolving the landmines at different environments. The landmine with dimension and burial depth of one electrode separation unit is over estimated while the spatial resolutions decrease as the burial depth and noise percentage increase.

  10. Estimation of tree root distribution using electrical resistivity tomography

    Science.gov (United States)

    Schmaltz, Elmar; Uhlemann, Sebastian

    2016-04-01

    Trees influence soil-mantled slopes mechanically by anchoring in the soil with coarse roots. Forest-stands play an important role in mechanical reinforcement to reduce the susceptibility to slope failures. However, the effect of stabilisation of roots is connected with the distribution of roots in the ground. The architecture and distribution of tree roots is diverse and strongly dependent on species, plant age, stand density, relief, nutrient supply as well as climatic and pedologic conditions. Particularly trees growing on inclined slopes show shape-shifting root systems. Geophysical techniques are commonly used to non-invasively study hydrological and geomorphological subsurface properties, by imaging contrasting physical properties of the ground. This also poses the challenge for geophysical imaging of root systems, as properties, such as electrical resistivity, of dry and wet roots fall within the range of soils. The objective of this study is whether electrical resistivity tomography (ERT) allows a reliable reproduction of root systems of alone-standing trees on diverse inclined slopes. In this regard, we set the focus on the branching of secondary roots of two common walnut trees (Juglans regia L.) that were not disturbed in the adjacencies and thus expected to develop their root systems unhindered. Walnuts show a taproot-cordate root system with a strong tap-root in juvenile age and a rising cordate rooting with increasing age. Hence, mature walnuts can exhibit a root system that appears to be deformed or shifted respectively when growing at hillslope locations. We employed 3D ERT centred on the tree stem, comprising dipole-dipole measurements on a 12-by-41 electrode grid with 0.5 m and 1.0m electrode spacing in x- and y-direction respectively. Data were inverted using a 3D smoothness constrained non-linear least-squares algorithm. First results show that the general root distribution can be estimated from the resistivity models and that shape

  11. Towards a Global Permafrost Electrical Resistivity Survey (GPERS) database

    Science.gov (United States)

    Lewkowicz, Antoni G.; Douglas, Thomas; Hauck, Christian

    2017-04-01

    Hundreds, and perhaps thousands, of Electrical Resistivity Tomography (ERT) surveys have been undertaken over the past two decades in permafrost areas in North America, Europe, and Asia. Two main types of ERT configurations have been conducted: galvanic surveys using metallic rods as conductors and capacitive-coupled surveys using towed cable arrays. ERT surveys have been carried out in regions with mountain permafrost, lowland permafrost, and coastal saline permafrost, and in undisturbed, naturally-disturbed (e.g. fire-affected), and anthropogenically-affected sites (e.g. around buildings and infrastructure). Some surveys are associated with local validation of frozen ground conditions, through borehole temperatures, frost probing or creep phenomena. Others are in locations without boreholes or with clast-rich or bedrock active layers which preclude this direct confirmation. Most surveys have been carried out individually on particular dates but there are increasing numbers of repeated ERT measurements being made to detect change, either at intervals using a fixed array of electrodes, or at high frequency with a fixed and automated measurement apparatus. Taken as a group, ERT profiles represent an untapped knowledge base relating to permafrost presence, absence, or partial presence (i.e. discontinuous permafrost), and in some cases to the thickness of permafrost and ice content. When combined with borehole information, ERT measurements can identify massive ice features and provides information on soil stratigraphy. The Global Permafrost Electrical Resistivity Survey (GPERS) database is planned as a freely available on-line repository of data from two-dimensional electrical resistivity surveys undertaken in permafrost regions. Its development is supported by the Permafrost Carbon Network and an application for an International Permafrost Association (IPA) Action Group is also underway. When the future GPERS records are compared with the GTN-P database it will be

  12. Crystallization Study of Cu56Zr7Ti37 Metallic Glass by Electrical Resistivity Measurement

    Institute of Scientific and Technical Information of China (English)

    Ansu J. Kailath; Kalpalata Dutta; Thomas C.Alex; Amitava Mitra

    2011-01-01

    In this paper, the crystallization behaviour of amorphous Cu56Zr7Ti37alloy using thermal electrical resistivity (TER) and differential scanning calorimetry (DSC) studies has been described. Isochronal TER and DSC measurements indicate that crystallization occurs in two stages. Isothermal crystallization studies of the alloy by TER show that the kinetics conforms to Johnson-Mehl-Avrami model. Avrami exponents derived from kinetics, between 1.1 and 1.2, imply that the crystallization processes are diffusion controlled with near zero nucleation. Activation energy has been found to increase with the transformed volume fraction. A plausible explanation has been presented by separating the contributions due to nucleation and crystal growth towards total activation energy.

  13. Pressure and temperature induced electrical resistance change in nano-carbon/epoxy composites

    NARCIS (Netherlands)

    Shen, J. T.; Buschhorn, S. T.; De Hosson, J. Th. M.; Schulte, K.; Fiedler, B.

    2015-01-01

    In this study, we investigate the changes of electrical resistance of the carbon black (CB) and carbon nanotube (CNT) filled epoxy composites upon compression, swelling and temperature variation. For all samples we observe a decrease of electrical resistance under compression, while an increase of

  14. Indications of vigor loss after fire in Caribbean pine (Pinus caribaea) from electrical resistance measurements

    Science.gov (United States)

    T.E. Paysen; A.L. Koonce; E. Taylor; M.O. Rodriquez

    2006-01-01

    In May 1993, electrical resistance measurements were performed on trees in burned and unburned stands of Caribbean pine (Pinus caribaea Mor.) in north-eastern Nicaragua to determine whether tree vigor was affected by fire. An Osmose model OZ-67 Shigometer with digital readout was used to collect the sample electrical resistance data. Computer-...

  15. Study of filled dolines by using 3D stereo image processing and electrical resistivity imaging

    Directory of Open Access Journals (Sweden)

    Mateja Breg Valjavec

    2014-01-01

    Full Text Available This article deals with doline degradation due to uncontrolled waste dumping in the past in the Logatec Polje in Slovenia. It introduces a concept for determining 3D geometric characteristics (shape, depth, radius, area, and volume of formerly concave landforms (i.e., recently filled dolines by using a combination of two methods: (1 photogrammetric stereo processing of archival aerial photographs and (2 electrical resistivity imaging (ERI. To represent, visualize, and study the characteristics of the former surface morphology (i.e., the dolines before they were filled, a digital terrain model (DTM for 1972 (DTM1972 was made using digital photogrammetry processing of five sequential archival aerial photographs (1972, © GURS. DTM1972 was visually and quantitatively compared with the DTM5 of the recent surface morfology (DTM5, © GURS, 2006 in order to define areas of manmade terrain differences. In general, a circular area with a higher terrain difference is an indicator of a filled doline. The calculated terrain differences also indicate the thickness of buried waste material. Three case-study dolines were selected for 3D geometric analysis and tested in the field using ERI. ERI was used to determine the genetic type of the original doline, to confirm that the buried material in the doline is actually waste, and to ascertain opportunities for further study of water pollution due to waste leakage. Based on a comparison among the ERI sections obtained using various electrode arrays, it was concluded that the basins are actually past concave landforms (i.e., dolines filled with mixed waste material having the lowest resistivity value (bellow 100 ohm-m, which differs measurably from the surrounding natural materials. The resistivity of hard stacked limestone is higher (above 1,000 ohm-m than resistivity of cracked carbonate rocks with cracks filled with loamy clay sediments while in loamy alluvial sediment resistivity falls below 150 ohm

  16. Electrical resistivity and dielectric properties of helical microorganism cells coated with silver by electroless plating

    Energy Technology Data Exchange (ETDEWEB)

    Cai, Jun, E-mail: jun_cai@buaa.edu.cn [Bionic and Micro/Nano/Bio Manufacturing Technology Research Center, School of Mechanical Engineering and Automation, Beihang University, Beijing 100191 (China); Lan, Mingming; Zhang, Deyuan; Zhang, Wenqiang [Bionic and Micro/Nano/Bio Manufacturing Technology Research Center, School of Mechanical Engineering and Automation, Beihang University, Beijing 100191 (China)

    2012-09-01

    Highlights: Black-Right-Pointing-Pointer We use the microorganism cells as forming templates to fabricate the bio-based conductive particles. Black-Right-Pointing-Pointer The microorganism cells selected as forming templates are Spirulina platens, which are of natural helical shape and high aspect ratio. Black-Right-Pointing-Pointer The sliver-coated Spirulina cells are a kind of lightweight conductive particles. Black-Right-Pointing-Pointer The composites containing sliver-coated Spirulina cells exhibit a lower percolation value. - Abstract: In this paper, microorganism cells (Spirulina platens) were used as forming templates for the fabrication of the helical functional particles by electroless silver plating process. The morphologies and ingredients of the coated Spirulina cells were analyzed with scanning electron microscopy and energy dispersive spectrometer. The crystal structures were characterized by employing the X-ray diffraction. The electrical resistivity and dielectric properties of samples containing different volume faction of sliver-coated Spirulina cells were measured and investigated by four-probe meter and vector network analyzer. The results showed that the Spirulina cells were successfully coated with a uniform silver coating and their initial helical shapes were perfectly kept. The electrical resistivity and dielectric properties of the samples had a strong dependence on the volume content of sliver-coated Spirulina cells and the samples could achieve a low percolation value owing to high aspect ratio and preferable helical shape of Spirulina cells. Furthermore, the conductive mechanism was analyzed with the classic percolation theory, and the values of {phi}{sub c} and t were obtained.

  17. Ultrahigh Oxidation Resistance and High Electrical Conductivity in Copper-Silver Powder

    Science.gov (United States)

    Li, Jiaxiang; Li, Yunping; Wang, Zhongchang; Bian, Huakang; Hou, Yuhang; Wang, Fenglin; Xu, Guofu; Liu, Bin; Liu, Yong

    2016-12-01

    The electrical conductivity of pure Cu powder is typically deteriorated at elevated temperatures due to the oxidation by forming non-conducting oxides on surface, while enhancing oxidation resistance via alloying is often accompanied by a drastic decline of electrical conductivity. Obtaining Cu powder with both a high electrical conductivity and a high oxidation resistance represents one of the key challenges in developing next-generation electrical transferring powder. Here, we fabricate a Cu-Ag powder with a continuous Ag network along grain boundaries of Cu particles and demonstrate that this new structure can inhibit the preferential oxidation in grain boundaries at elevated temperatures. As a result, the Cu-Ag powder displays considerably high electrical conductivity and high oxidation resistance up to approximately 300 °C, which are markedly higher than that of pure Cu powder. This study paves a new pathway for developing novel Cu powders with much enhanced electrical conductivity and oxidation resistance in service.

  18. Modelling the influence of steel fibres on the electrical resistivity of cementitious composites

    DEFF Research Database (Denmark)

    Solgaard, Anders Ole Stubbe; Michel, Alexander; Stang, Henrik

    2009-01-01

    work concerns the electrical resistivity of cementitious composites and some of the parameters influencing it in order to get a more thorough understanding of the factors governing the overall resistivity. The basis of the present study is an experimental investigation of the electrical resistivity...... the overall resistivity of the material and thereby the corrosion rate of the embedded reinforcement. To the knowledge of the authors, only preliminary studies have been made on the influence of corrosion of the reinforcement bars from the addition of the electrical conductive steel fibres. Thus the present......One of the governing factors on the corrosion of embedded reinforcement is the electrical resistivity of the concrete. The combination of steel fibres and conventional reinforcement bars has been used in a number of structures. However, the addition of electrical con-ductive fibres might influence...

  19. Effect of Metal Oxide on Electrical Resistivity of Conductive Wood Charcoal

    Institute of Scientific and Technical Information of China (English)

    2011-01-01

    To analyze the effect of metal oxide on electrical resistivity of conductive wood charcoal,wood powder of Masson pine was mixed with ferric oxide (Fe_2O_3) and nickel oxide (NiO), respectively,and then the mixed powders were carbonized at high temperature in a laboratory-scale tube furnace in a nitrogen atmosphere. DCY-3 resistivity tester was used to measure electrical resistivity of conductive wood charcoal. When carbonization temperature was 1200 ℃, the electrical resistivity of controlsamples, Fe_2O_3 (...

  20. Electrical resistivity characteristics of diesel oil-contaminated kaolin clay and a resistivity-based detection method.

    Science.gov (United States)

    Liu, Zhibin; Liu, Songyu; Cai, Yi; Fang, Wei

    2015-06-01

    As the dielectric constant and conductivity of petroleum products are different from those of the pore water in soil, the electrical resistivity characteristics of oil-contaminated soil will be changed by the corresponding oil type and content. The contaminated soil specimens were manually prepared by static compaction method in the laboratory with commercial kaolin clay and diesel oil. The water content and dry density of the first group of soil specimens were controlled at 10 % and 1.58 g/cm(3). Corresponding electrical resistivities of the contaminated specimens were measured at the curing periods of 7, 14, and 28 and 90, 120, and 210 days on a modified oedometer cell with an LCR meter. Then, the electrical resistivity characteristics of diesel oil-contaminated kaolin clay were discussed. In order to realize a resistivity-based oil detection method, the other group of oil-contaminated kaolin clay specimens was also made and tested, but the initial water content, oil content, and dry density were controlled at 0~18 %, 0~18 %, 1.30~1.95 g/cm(3), respectively. Based on the test data, a resistivity-based artificial neural network (ANN) was developed. It was found that the electrical resistivity of kaolin clay decreased with the increase of oil content. Moreover, there was a good nonlinear relationship between electrical resistivity and corresponding oil content when the water content and dry density were kept constant. The decreasing velocity of the electrical resistivity of oil-contaminated kaolin clay was higher before the oil content of 12 % than after 12 %, which indicated a transition of the soil from pore water-controlled into oil-controlled electrical resistivity characteristics. Through microstructural analysis, the decrease of electrical resistivity could be explained by the increase of saturation degree together with the collapse of the electrical double layer. Environmental scanning electron microscopy (ESEM) photos indicated that the diesel oil

  1. Electric-field-modulated nonvolatile resistance switching in VO₂/PMN-PT(111) heterostructures.

    Science.gov (United States)

    Zhi, Bowen; Gao, Guanyin; Xu, Haoran; Chen, Feng; Tan, Xuelian; Chen, Pingfan; Wang, Lingfei; Wu, Wenbin

    2014-04-09

    The electric-field-modulated resistance switching in VO2 thin films grown on piezoelectric (111)-0.68Pb(Mg1/3Nb2/3)O3-0.32PbTiO3 (PMN-PT) substrates has been investigated. Large relative change in resistance (10.7%) was observed in VO2/PMN-PT(111) hererostructures at room temperature. For a substrate with a given polarization direction, stable resistive states of VO2 films can be realized even when the applied electric fields are removed from the heterostructures. By sweeping electric fields across the heterostructure appropriately, multiple resistive states can be achieved. These stable resistive states result from the different stable remnant strain states of substrate, which is related to the rearrangements of ferroelectric domain structures in PMN-PT(111) substrate. The resistance switching tuned by electric field in our work may have potential applications for novel electronic devices.

  2. Electric field distribution in a finite-volume head model of deep brain stimulation.

    Science.gov (United States)

    Grant, Peadar F; Lowery, Madeleine M

    2009-11-01

    This study presents a whole-head finite element model of deep brain stimulation to examine the effect of electrical grounding, the finite conducting volume of the head, and scalp, skull and cerebrospinal fluid layers. The impedance between the stimulating and reference electrodes in the whole-head model was found to lie within clinically reported values when the reference electrode was incorporated on a localized surface in the model. Incorporation of the finite volume of the head and inclusion of surrounding outer tissue layers reduced the magnitude of the electric field and activating function by approximately 20% in the region surrounding the electrode. Localized distortions of the electric field were also observed when the electrode was placed close to the skull. Under bipolar conditions the effect of the finite conducting volume was shown to be negligible. The results indicate that, for monopolar stimulation, incorporation of the finite volume and outer tissue layers can alter the magnitude of the electric field and activating function when the electrode is deep within the brain, and may further affect the shape if the electrode is close to the skull.

  3. Measuring turbulence in a flotation cell using electrical resistance tomography

    Science.gov (United States)

    Meng, Jun; Xie, Weiguo; Runge, Kym; Bradshaw, Dee

    2015-11-01

    Measuring turbulence in an industrial flotation environment has long been problematic due to the opaque, aggressive, and abrasive three-phase environment in a flotation cell. One of the promising measurement techniques is electrical resistance tomography (ERT). By measuring the conductivity distribution across a measurement area, ERT has been adopted by many researchers to monitor and investigate many processes involving multiphase flows. In the research outlined in this paper, a compact ERT probe was built and then used to measure the conductivity distribution within a 60 l flotation cell operated with water and air. Two approaches were then developed to process the ERT data and estimate turbulence-related parameters. One is a conductivity variance method and the other is based on the Green-Kubo relations. Both rely on and use the fluctuation in the ERT measurement caused by bubbles moving through the measurement area changing the density of the fluid. The results from both approaches were validated by comparing the results produced by the ERT probe in a 60l flotation cell operated at different air rates and impeller speeds to that measured using an alternative turbulence measurement device. The second approach is considered superior to the first as the first requires the development of auxiliary information which would not usually be known for a new system.

  4. Electrical resistance sensors record spring flow timing, Grand Canyon, Arizona

    Science.gov (United States)

    Adams, E.A.; Monroe, S.A.; Springer, A.E.; Blasch, K.W.; Bills, D.J.

    2006-01-01

    Springs along the south rim of the Grand Canyon, Arizona, are important ecological and cultural resources in Grand Canyon National Park and are discharge points for regional and local aquifers of the Coconino Plateau. This study evaluated the applicability of electrical resistance (ER) sensors for measuring diffuse, low-stage (flow in the steep, rocky spring-fed tributaries of the south rim. ER sensors were used to conduct a baseline survey of spring flow timing at eight sites in three spring-fed tributaries in Grand Canyon. Sensors were attached to a nearly vertical rock wall at a spring outlet and were installed in alluvial and bedrock channels. Spring flow timing data inferred by the ER sensors were consistent with observations during site visits, with flow events recorded with collocated streamflow gauging stations and with local precipitation gauges. ER sensors were able to distinguish the presence of flow along nearly vertical rock surfaces with flow depths between 0.3 and 1.0 cm. Laboratory experiments confirmed the ability of the sensors to monitor the timing of diffuse flow on impervious surfaces. A comparison of flow patterns along the stream reaches and at springs identified the timing and location of perennial and intermittent flow, and periods of increased evapotranspiration.

  5. Less Invasive Corneal Transepithelial Electrical Resistance Measurement Method.

    Science.gov (United States)

    Uematsu, Masafumi; Mohamed, Yasser Helmy; Onizuka, Naoko; Ueki, Ryotaro; Inoue, Daisuke; Fujikawa, Azusa; Sasaki, Hitoshi; Kitaoka, Takashi

    2016-01-01

    To evaluate acute corneal permeability changes after instillation of benzalkonium chloride (BAC) using a newly developed in vivo less invasive corneal transepithelial electrical resistance (TER) measurement method in animals and humans. We previously developed an in vivo method for measuring corneal TER using intraocular electrodes in animals. This method can be used to precisely measure the decline of the corneal barrier function after instillation of BAC. To lessen the invasiveness of that procedure, we further refined the method for measuring the corneal TER by developing electrodes that could be placed on the surface of the cornea and in the conjunctival sac instead of inserting them into the anterior chamber. Corneal TER changes before and after exposure to 0.02% BAC were determined in this study using the new device in both rabbits and humans. There was a significant decrease in the corneal TER after exposure of the cornea to 0.02% BAC solution in both rabbits and humans (Pmeasurement method enables us for the first time to measure TER of the human cornea, allowing safe and reliable investigation of the direct effect of different eye drop treatments on the corneal epithelium. Copyright © 2016 Elsevier Inc. All rights reserved.

  6. An ICPSO-RBFNN nonlinear inversion for electrical resistivity imaging

    Institute of Scientific and Technical Information of China (English)

    江沸菠; 戴前伟; 董莉

    2016-01-01

    To improve the global search ability and imaging quality of electrical resistivity imaging(ERI) inversion, a two-stage learning ICPSO algorithm of radial basis function neural network (RBFNN) based on information criterion (IC) and particle swarm optimization (PSO) is presented. In the proposed method, IC is applied to obtain the hidden layer structure by calculating the optimal IC value automatically and PSO algorithm is used to optimize the centers and widths of the radial basis functions in the hidden layer. Meanwhile, impacts of different information criteria to the inversion results are compared, and an implementation of the proposed ICPSO algorithm is given. The optimized neural network has one hidden layer with 261 nodes selected by AKAIKE’s information criterion (AIC) and it is trained on 32 data sets and tested on another 8 synthetic data sets. Two complex synthetic examples are used to verify the feasibility and effectiveness of the proposed method with two learning stages. The results show that the proposed method has better performance and higher imaging quality than three-layer and four-layer back propagation neural networks (BPNNs) and traditional least square(LS) inversion.

  7. Effect of transcutaneous electrical muscle stimulation on muscle volume in patients with septic shock

    DEFF Research Database (Denmark)

    Poulsen, Jesper Brøndum; Møller, Kirsten; Jensen, Claus V

    2011-01-01

    Objective: Intensive care unit admission is associated with muscle wasting and impaired physical function. We investigated the effect of early transcutaneous electrical muscle stimulation on quadriceps muscle volume in patients with septic shock. Design: Randomized interventional study using...... randomization of the quadriceps muscles, transcutaneous electrical muscle stimulation was applied on the intervention side for 7 consecutive days and for 60 mins per day. All patients underwent computed tomographic scans of both thighs immediately before and after the 7-day treatment period. The quadriceps...... (interquartile range, 20–29), respectively. During the 7-day study period, the volume of the quadriceps muscle on the control thigh decreased by 16% (4–21%, p = .03) corresponding to a rate of 2.3% per day. The volume of the stimulated muscle decreased by 20% (3–25%, p = .04) corresponding to a rate of 2.9% per...

  8. Electrical Resistivity Measurement of Petroleum Coke Powder by Means of Four-Probe Method

    Science.gov (United States)

    Rouget, G.; Majidi, B.; Picard, D.; Gauvin, G.; Ziegler, D.; Mashreghi, J.; Alamdari, H.

    2017-07-01

    Carbon anodes used in Hall-Héroult electrolysis cells are involved in both electrical and chemical processes of the cell. Electrical resistivity of anodes depends on electrical properties of its constituents, of which carbon coke aggregates are the most prevalent. Electrical resistivity of coke aggregates is usually characterized according to the ISO 10143 standardized test method, which consists of measuring the voltage drop in the bed of particles between two electrically conducing plungers through which the current is also applied. Estimation of the electrical resistivity of coke particles from the resistivity of particle bed is a challenging task and needs consideration of the contribution of the interparticle void fraction and the particle/particle contact resistances. In this work, the bed resistivity was normalized by subtracting the interparticle void fraction. Then, the contact size was obtained from discrete element method simulation and the contact resistance was calculated using Holm's theory. Finally, the resistivity of the coke particles was obtained from the bed resistivity.

  9. Electrical Resistivity Measurement of Petroleum Coke Powder by Means of Four-Probe Method

    Science.gov (United States)

    Rouget, G.; Majidi, B.; Picard, D.; Gauvin, G.; Ziegler, D.; Mashreghi, J.; Alamdari, H.

    2017-10-01

    Carbon anodes used in Hall-Héroult electrolysis cells are involved in both electrical and chemical processes of the cell. Electrical resistivity of anodes depends on electrical properties of its constituents, of which carbon coke aggregates are the most prevalent. Electrical resistivity of coke aggregates is usually characterized according to the ISO 10143 standardized test method, which consists of measuring the voltage drop in the bed of particles between two electrically conducing plungers through which the current is also applied. Estimation of the electrical resistivity of coke particles from the resistivity of particle bed is a challenging task and needs consideration of the contribution of the interparticle void fraction and the particle/particle contact resistances. In this work, the bed resistivity was normalized by subtracting the interparticle void fraction. Then, the contact size was obtained from discrete element method simulation and the contact resistance was calculated using Holm's theory. Finally, the resistivity of the coke particles was obtained from the bed resistivity.

  10. Recovery of electrical resistance in copper films on polyethylene terephthalate subjected to a tensile strain

    Energy Technology Data Exchange (ETDEWEB)

    Glushko, O. [Department Materials Physics, Montanuniversität Leoben, Jahnstrasse 12, 8700 Leoben (Austria); Marx, V.M.; Kirchlechner, C. [Department Materials Physics, Montanuniversität Leoben, Jahnstrasse 12, 8700 Leoben (Austria); Max-Plank-Institut für Eisenforschung GmbH, Max-Planck-Strasse 1, 40237 Düsseldorf (Germany); Zizak, I. [Helmholtz-Zentrum Berlin for Materials and Energy, Albert-Einstein-Str. 15, D-12489 Berlin (Germany); Cordill, M.J. [Department Materials Physics, Montanuniversität Leoben, Jahnstrasse 12, 8700 Leoben (Austria); Erich Schmid Institute of Materials Science, Austrian Academy of Sciences, Jahnstrasse 12, 8700 Leoben (Austria)

    2014-02-03

    Substantial recovery (decrease) of electrical resistance during and after unloading is demonstrated for copper films on polyethylene terephthalate substrates subjected to a tensile strain with different peak values. Particularly, the films strained to 5% exhibit full resistance recovery after unloading despite clearly visible plastic deformation of the film. The recovery of electrical resistance in connection with the mechanical behavior of film/substrate couple is discussed with the help of in situ scanning electron microscopy and X-ray diffraction analysis. - Highlights: • Tensile tests on 200 nm Cu films on PET substrate are performed. • Electrical resistance is recorded in-situ during loading and unloading. • Significant recovery (decrease) of resistance is observed during and after unloading. • Films strained to 5% demonstrate full resistance recovery. • Viscoelastic relaxation of PET is responsible for recovery of Cu film resistance.

  11. In situ TEM imaging of defect dynamics under electrical bias in resistive switching rutile-TiO₂.

    Science.gov (United States)

    Kamaladasa, Ranga J; Sharma, Abhishek A; Lai, Yu-Ting; Chen, Wenhao; Salvador, Paul A; Bain, James A; Skowronski, Marek; Picard, Yoosuf N

    2015-02-01

    In this study, in situ electrical biasing was combined with transmission electron microscopy (TEM) in order to study the formation and evolution of Wadsley defects and Magnéli phases during electrical biasing and resistive switching in titanium dioxide (TiO2). Resistive switching devices were fabricated from single-crystal rutile TiO2 substrates through focused ion beam milling and lift-out techniques. Defect evolution and phase transformations in rutile TiO2 were monitored by diffraction contrast imaging inside the TEM during electrical biasing. Reversible bipolar resistive switching behavior was observed in these single-crystal TiO2 devices. Biased induced reduction reactions created increased oxygen vacancy concentrations to such an extent that shear faults (Wadsley defects) and oxygen-deficient phases (Magnéli phases) formed over large volumes within the TiO2 TEM specimen. Nevertheless, the observed reversible formation/dissociation of Wadsley defects does not appear to correlate to resistive switching phenomena at these length scales. These defect zones were found to reversibly reconfigure in a manner consistent with charged oxygen vacancy migration responding to the applied bias polarity.

  12. Method for the formation of cylindrical current and its application to evaluate electrical resistivity

    Science.gov (United States)

    Li, T.-C.; Chang, C.-S.; Liang, W.-L.; Tsai, W.-F.; Ai, C.-F.; Lin, J.-F.

    2012-07-01

    A cylindrical current method is developed to obtain a stable and precise electrical resistivity of a specimen with or without a coating film. The electrical resistivity of a standard silicon wafer doped with boron at a concentration can be measured using the proposed method if the experimental results of electrical voltage varying with the distance from the center line of the cylindrical current are available. A comparison of the electrical resistivity obtained using the present method and the theoretical reference value indicates that the proposed method produces reliable and precise measurements. Using four test samples, the experimental results of electrical resistivity measured by the present method are shown to be reproducible and more precise than those measured by the four-terminal sensing method and the van der Pauw method. The electrical voltage and current obtained at various distances from the center line of the cylindrical current are almost independent of the distance and the direction of measurements. The effect of specimen's crystallinity appears to be the governing factor of electrical resistivity. Electrical resistivity decreases with increasing crystallinity generally.

  13. Is pulmonary resistance constant, within the range of tidal volume ventilation, in patients with ARDS?

    Science.gov (United States)

    Mols, G; Kessler, V; Benzing, A; Lichtwarck-Aschoff, M; Geiger, K; Guttmann, J

    2001-02-01

    When managing patients with acute respiratory distress syndrome (ARDS), respiratory system compliance is usually considered first and changes in resistance, although recognized, are neglected. Resistance can change considerably between minimum and maximum lung volume, but is generally assumed to be constant in the tidal volume range (V(T)). We measured resistance during tidal ventilation in 16 patients with ARDS or acute lung injury by the slice method and multiple linear regression analysis. Resistance was constant within V(T) in only six of 16 patients. In the remaining patients, resistance decreased, increased or showed complex changes. We conclude that resistance within V(T) varies considerably from patient to patient and that constant resistance within V(T) is not always likely.

  14. Vertical electrical resistivity sounding (VERS) of tundra and forest tundra soils of Yamal region

    Science.gov (United States)

    Alekseev, Ivan; Kostecki, Jakub; Abakumov, Evgeny

    2017-01-01

    The aim of the study was to determine electrical resistivity peculiarities of tundra and forest tundra soils and soil-permafrost layers of the Yamal region. Measurements of electrical resistivity of soil and permafrost strata were performed with a portable device LandMapper (to a depth of 300-500 cm). These measurements allow determination of the values of apparent electrical resistivity of soils and permafrost at different depths and determination of the depths of the permafrost table on each key plot. It was found that there are several trends in vertical distribution of apparent electrical resistivity values. The first trend is a monotonous increase in electrical resistivity values to the depth. It may be explained by the increasing electrical resistivity within the soil depth in relation to the increase in permafrost density. The second trend is a sharp decrease replaced by a gradual increase in electrical resistivity values caused by changing of non-frozen friable debris to frozen massive crystalline rock. These differences were related to the type of landscape: flat lowlands composed of friable grounds underlain by permafrost or friable grounds with permafrost underlain by a rock crystalline layer.

  15. Measurement and modelling of moisture-electrical resistivity relationship of fine-grained unsaturated soils and electrical anisotropy

    Science.gov (United States)

    Merritt, A. J.; Chambers, J. E.; Wilkinson, P. B.; West, L. J.; Murphy, W.; Gunn, D.; Uhlemann, S.

    2016-01-01

    A methodology for developing resistivity-moisture content relationships of materials associated with a clayey landslide is presented. Key elements of the methodology include sample selection and preparation, laboratory measurement of resistivity with changing moisture content, and the derivation of models describing the relationship between resistivity and moisture content. Laboratory resistivity measurements show that the techniques utilised (samples and square array) have considerable potential as a means of electropetrophysical calibration of engineering soils and weak rock. Experimental electrical resistivity results show a hierarchy of values dependent on sample lithology, with silty clay exhibiting the lowest resistivities, followed by siltstones and sands, which return the highest resistivities. In addition, finer grained samples show a greater degree of anisotropy between measurement orientations than coarser grained samples. However, suitability of results in light of issues such as sample cracking and electrical conduction must be identified and accounted for if the results are to be accurately up-scaled to inverted model resistivity results. The existence of directional anisotropy makes model calibration curve selection more difficult due to variability in the range of measured laboratory resistances. The use of larger measurement array size means that experimental data will be more representative of bulk lithological properties. In addition, use of electrodes with a relatively high surface area (wide diameter) help maintain low contact resistances and repeat measurement error, relative to narrow electrodes. Variation exists between the fit of experimental data and petrophysical models. Model fit is best for clay-dominated samples but fits less well for sand-dominated samples. Waxman-Smits equation is appropriately applied in this investigation as all samples have considerable clay mineral content, as is shown in non-negligible CEC results. The

  16. A study of the effect of seasonal climatic factors on the electrical resistivity response of three experimental graves

    Science.gov (United States)

    Jervis, John R.; Pringle, Jamie K.

    2014-09-01

    Electrical resistivity surveys have proven useful for locating clandestine graves in a number of forensic searches. However, some aspects of grave detection with resistivity surveys remain imperfectly understood. One such aspect is the effect of seasonal changes in climate on the resistivity response of graves. In this study, resistivity survey data collected over three years over three simulated graves were analysed in order to assess how the graves' resistivity anomalies varied seasonally and when they could most easily be detected. Thresholds were used to identify anomalies, and the ‘residual volume' of grave-related anomalies was calculated as the area bounded by the relevant thresholds multiplied by the anomaly's average value above the threshold. The residual volume of a resistivity anomaly associated with a buried pig cadaver showed evidence of repeating annual patterns and was moderately correlated with the soil moisture budget. This anomaly was easiest to detect between January and April each year, after prolonged periods of high net gain in soil moisture. The resistivity response of a wrapped cadaver was more complex, although it also showed evidence of seasonal variation during the third year after burial. We suggest that the observed variation in the graves' resistivity anomalies was caused by seasonal change in survey data noise levels, which was in turn influenced by the soil moisture budget. It is possible that similar variations occur elsewhere for sites with seasonal climate variations and this could affect successful detection of other subsurface features. Further research to investigate how different climates and soil types affect seasonal variation in grave-related resistivity anomalies would be useful.

  17. Early Age Compressive Strength of Pastes by Electrical Resistivity Method and Maturity Method

    Institute of Scientific and Technical Information of China (English)

    XIAO Lianzhen; WEI Xiaosheng

    2011-01-01

    The compressive strength development of Portland cement pastes was investigated by the electrical resistivity method and the maturity method.The experiments were carried out on the cement pastes with different water-cement ratios at different curing temperatures.The results show that the application of the maturity method has limitation to obtain the strength.It is found that both of the compressive strength and the electrical resistivity follow hyperbolic trend for all the mixes.The hyperbolic equation of each mix is obtained to estimate the ultimate resistivity value which can probably be reached.The relationship between electrical resistivity and compressive strength of the cement pastes is established based on the test results and interpreted by the empirical Archie equation and a strength-porosity equation.The relationship between the electrical resistivity after temperature correction and the compressive strength was linear and independent of curing temperature and water-cement ratio.

  18. A one-dimensional model of solid-earth electrical resistivity beneath Florida

    Science.gov (United States)

    Blum, Cletus; Love, Jeffrey J.; Pedrie, Kolby; Bedrosian, Paul A.; Rigler, E. Joshua

    2015-11-19

    An estimated one-dimensional layered model of electrical resistivity beneath Florida was developed from published geological and geophysical information. The resistivity of each layer is represented by plausible upper and lower bounds as well as a geometric mean resistivity. Corresponding impedance transfer functions, Schmucker-Weidelt transfer functions, apparent resistivity, and phase responses are calculated for inducing geomagnetic frequencies ranging from 10−5 to 100 hertz. The resulting one-dimensional model and response functions can be used to make general estimates of time-varying electric fields associated with geomagnetic storms such as might represent induction hazards for electric-power grid operation. The plausible upper- and lower-bound resistivity structures show the uncertainty, giving a wide range of plausible time-varying electric fields.

  19. The influence of changes in water content on the electrical resistivity of a natural unsaturated loess

    CERN Document Server

    Munoz-Castelblanco, José; Delage, Pierre; Cui, Yu Jun

    2013-01-01

    Non-destructive methods of measuring water content in soils have been extensively developed in the last decades, especially in soil science. Among these methods, the measurements based on the electrical resistivity are simple and reliable thanks to the clear relationship between the water content and the electrical resistivity of soils. In this work, a new electrical resistivity probe was developed to monitor the change in local water content in the triaxial apparatus. The probe is composed of two-pair of electrodes, and an electrical current is induced through the soil at the vicinity of the contact between the probe and the specimen. Some experimental data on the changes in resistivity with the degree of saturation were obtained in specimens of a natural unsaturated loess from Northern France. Two theoretical models of resistivity were also used to analyze the obtained data. Results are finally discussed with respect to the loess's water retention properties.

  20. Carbon fiber polymer-matrix structural composites for electrical-resistance-based sensing

    Science.gov (United States)

    Wang, Daojun

    This dissertation has advanced the science and technology of electrical-resistance-based sensing of strain/stress and damage using continuous carbon fiber epoxy-matrix composites, which are widely used for aircraft structures. In particular, it has extended the technology of self-sensing of carbon fiber polymer-matrix composites from uniaxial longitudinal loading and flexural loading to uniaxial through-thickness loading and has extended the technology from structural composite self-sensing to the use of the composite (specifically a one-lamina composite) as an attached sensor. Through-thickness compression is encountered in the joining of composite components by fastening. Uniaxial through-thickness compression results in strain-induced reversible decreases in the through-thickness and longitudinal volume resistivities, due to increase in the fiber-fiber contact in the through-thickness direction, and minor-damage-induced irreversible changes in these resistivities. The Poisson effect plays a minor role. The effects in the longitudinal resistivity are small compared to those in the through-thickness direction, but longitudinal resistance measurement is more amenable to practical implementation in structures than through-thickness resistance measurement. The irreversible effects are associated with an increase in the through-thickness resistivity and a decrease in the longitudinal resistivity. The through-thickness gage factor is up to 5.1 and decreases with increasing compressive strain above 0.2%. The reversible fractional change in through-thickness resistivity per through-thickness strain is up to 4.0 and decreases with increasing compressive strain. The irreversible fractional change in through-thickness resistivity per unit through-thickness strain is around -1.1 and is independent of the strain. The sensing is feasible by measuring the resistance away from the stressed region, though the effectiveness is less than that at the stressed region. A one

  1. Electrical resistivity and piezoresistivity of Ni-CNT filled epoxy-based composites

    Science.gov (United States)

    Jiang, Jinbao; Xiao, Huigang; Li, Hui

    2013-04-01

    This paper investigates properties about electrical resistivity and piezoresistivity of multi-wall carbon nanotubes (MWCNTs)-filled epoxy-based composite and its further use for strain sensing. The MWCNTs dispersed epoxy resin, using MWCNTs in the amount of 1.5~3.0 vol.%, was first prepared by combined high-speed stirring and sonication methods. Then, the MWCNTs dispersed epoxy resin was cast into an aluminum mold to form specimens measuring 10×10×36 mm. After curing, DC electrical resistance measurements were performed along the longitudinal axis using the four-probe method, in which copper nets served as electrical contacts. The percolation threshold zone of resistivity was got as MWCNTs in the amount of 2.00-2.50 vol.%. Further compressive testing of these specimens was conducted with four-probe method for resistance measurements at the same time. Testing results show that the electrical resistivity of the composites changes with the strain's development, namely piezoresistivity. While for practical strain sensing use, signals of electric resistance and current in the acquisition circuits were both studied. Results show that the signal of current, compared with that of resistance, had better linear relationship with the compressive strain, better stability and longer effective section to reflect the whole deformation process of the specimens under pressure. Further works about the effects of low magnetic field on the electrical resistivity and piezoresistivity of Ni-CNTs filled epoxy-based composites were presented briefly at the end of the paper.

  2. Resistive memory effects in BiFeO3 single crystals controlled by transverse electric fields

    Science.gov (United States)

    Kawachi, S.; Kuroe, H.; Ito, T.; Miyake, A.; Tokunaga, M.

    2016-04-01

    The effects of electric fields perpendicular to the c-axis of the trigonal cell in single crystals of BiFeO3 are investigated through magnetization and resistance measurements. Magnetization and resistance exhibit hysteretic changes under applied electric fields, which can be ascribed to the reorientation of the magnetoelectric domains. Samples are repetitively switched between high- and low-resistance states by changing the polarity of the applied electric fields over 20 000 cycles at room temperature. These results demonstrate the potential of BiFeO3 for use in non-volatile memory devices.

  3. Synthesis and high-pressure electrical resistivity studies of Ti{sub 3}Al

    Energy Technology Data Exchange (ETDEWEB)

    Vennila, R. Selva [Department of Physics, Anna University, Chennai 600025 (India)]. E-mail: rsvennila@yahoo.co.in; Porchelvi, E. Elamurugu [Department of Physics, Anna University, Chennai 600025 (India); Joy, K.M. Freny [Department of Physics, Anna University, Chennai 600025 (India); Arun, T.K. Jaya [Department of Physics, Anna University, Chennai 600025 (India); Jaya, N. Victor [Department of Physics, Anna University, Chennai 600025 (India)

    2005-04-19

    Titanium aluminide (Ti{sub 3}Al) has been synthesized by a powder metallurgical method. X-ray diffraction studies show the formation of a single phase with hexagonal structure. Electrical resistivity studies were carried out by a four-probe technique both at high pressure and high temperature using a Bridgman Opposed Anvil High Pressure Device (OAHPD). The sample was studied up to a pressure and temperature of 10 GPa and 250 deg. C, respectively. The electrical resistivity is found to decrease with increasing pressure. The temperature effect causes an upward shift in the electrical resistivity in the range of pressure considered.

  4. Direct-current vertical electrical-resistivity soundings in the Lower Peninsula of Michigan

    Science.gov (United States)

    Westjohn, D.B.; Carter, P.J.

    1989-01-01

    Ninety-three direct-current vertical electrical-resistivity soundings were conducted in the Lower Peninsula of Michigan from June through October 1987. These soundings were made to assist in mapping the depth to brine in areas where borehole resistivity logs and water-quality data are sparse or lacking. The Schlumberger array for placement of current and potential electrodes was used for each sounding. Vertical electrical-resistivity sounding field data, shifted and smoothed sounding data, and electric layers calculated using inverse modeling techniques are presented. Also included is a summary of the near-surface conditions and depths to conductors and resistors for each sounding location.

  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. Optimization of the electric field distribution in a large volume tissue-equivalent proportional counter

    Energy Technology Data Exchange (ETDEWEB)

    Verma, P.K.; Waker, A.J. (Leeds Univ. (United Kingdom). Dept. of Medical Physics)

    1992-10-01

    Large volume tissue-equivalent proportional counters are of interest in radiation protection metrology, as the sensitivity in terms of counts per unit absorbed dose in these devices increases as the square of the counter diameter. Conventional solutions to the problem of maintaining a uniform electric field within a counter result in sensitive volume to total volume ratios which are unacceptably low when counter dimensions of the order of 15 cm diameter are considered and when overall compactness is an important design criterion. This work describes the design and optimization of an arrangement of field discs set at different potentials which enable sensitive volume to total volume ratios to approach unity. The method has been used to construct a 12.7 cm diameter right-cylindrical tissue-equivalent proportional counter in which the sensitive volume accounts for over 95% of the total device volume and the gas gain uniformity is maintained to within 3% along the entire length of the anode wire. (author).

  7. An Electric Field Volume Integral Equation Approach to Simulate Surface Plasmon Polaritons

    Directory of Open Access Journals (Sweden)

    R. Remis

    2013-02-01

    Full Text Available In this paper we present an electric field volume integral equation approach to simulate surface plasmon propagation along metal/dielectric interfaces. Metallic objects embedded in homogeneous dielectric media are considered. Starting point is a so-called weak-form of the electric field integral equation. This form is discretized on a uniform tensor-product grid resulting in a system matrix whose action on a vector can be computed via the fast Fourier transform. The GMRES iterative solver is used to solve the discretized set of equations and numerical examples, illustrating surface plasmon propagation, are presented. The convergence rate of GMRES is discussed in terms of the spectrum of the system matrix and through numerical experiments we show how the eigenvalues of the discretized volume scattering operator are related to plasmon propagation and the medium parameters of a metallic object.

  8. Effects of irradiation induced Cu clustering on Vickers hardness and electrical resistivity of Fe–Cu model alloys

    Energy Technology Data Exchange (ETDEWEB)

    Tobita, Tohru, E-mail: tobita.tohru@jaea.go.jp [Nuclear Safety Research Center, Japan Atomic Energy Agency, Tokai, Naka-gun, Ibaraki-prefecture 319-1195 (Japan); Nakagawa, Shou [Department of Materials Science, Osaka Prefecture University, Sakai-shi, Osaka 599-8531 (Japan); Takeuchi, Tomoaki; Suzuki, Masahide [Neutron Irradiation and Testing Reactor Center, Japan Atomic Energy Agency, Narita, Oarai, Higashiibaraki-gun, Ibaraki-prefecture 311-1393 (Japan); Ishikawa, Norito [Nuclear Science and Engineering Directorate, Japan Atomic Energy Agency, Tokai, Naka-gun, Ibaraki-prefecture 319-1195 (Japan); Chimi, Yasuhiro [Nuclear Safety Research Center, Japan Atomic Energy Agency, Tokai, Naka-gun, Ibaraki-prefecture 319-1195 (Japan); Saitoh, Yuichi [Department of Advanced Radiation Technology, Japan Atomic Energy Agency, Watanuki, Takasaki-shi, Gunma-prefecture 370-1292 (Japan); Soneda, Naoki; Nishida, Kenji; Ishino, Siori [Central Research Institute of Electric Power Industry, Komae-shi, Tokyo 201-8511 (Japan); Iwase, Akihiro [Department of Materials Science, Osaka Prefecture University, Sakai-shi, Osaka 599-8531 (Japan)

    2014-09-15

    Three kinds of Fe-based model alloys, Fe–0.018 atomic percent (at.%) Cu, Fe–0.53at.%Cu, and Fe–1.06at.%Cu were irradiated with 2 MeV electrons up to the dose of 2 × 10{sup −5} dpa at 250 °C. After the irradiation, the increase in Vickers hardness and the decrease in electrical resistivity were observed. The increase in hardness by electron irradiation is proportional to the product of the Cu contents and the square root of the electron dose. The decrease in electrical resistivity is proportional to the product of the square of Cu contents and the electron dose. Cu clustering in the materials with electron irradiation and thermal aging was observed by means of the Atom Probe Tomography (APT). The change in Vickers hardness and electrical resistivity is well correlated with micro-structure evolution related to the Cu clustering process. The irradiation hardening was proportional to the square root of volume fraction of the Cu clusters from early stage of irradiation.

  9. Evaluation on electrical resistivity of silicon materials after electron beam melting

    Indian Academy of Sciences (India)

    Hafiz Muhammad Noor Ul Huda Khan Asghar; Shuang Shi; Dachuan Jiang; Yi Tan

    2015-09-01

    This research deals with the study of electron beam melting (EBM) methodology utilized in melting silicon material and subsequently discusses on the effect of oxygen level on electrical resistivity change after EBM process. The oxygen content was reduced from 6.177 to less than 0.0517 ppmw when refining time exceeded 10 min with removal efficiency of more than 99.08%. The average value of electrical resistivity of silicon before EBM processing was recorded to be 2.25 cm but with the increase in melting time that was applied through EBM, the electrical resistivity was recorded to go high in the range of 4–13 cm for different regions. The electrical resistivity values were greater in the top and the bottom regions, whereas lowest in the central region at all conditions of melting time. It is the result of the evaporation of oxygen during melting process and the segregation of metal impurities during solidification.

  10. Pressure Induced Polymorphic Phase Transition of Natural Metamorphic Kalsilite; Electrical Resistivity and Infrared Spectroscopic Investigations

    Directory of Open Access Journals (Sweden)

    G. Parthasarathy

    2015-10-01

    Full Text Available We report here pressure dependence of the electrical resistivity of natural kalsilite (K0.998Na0.002Al0.998Fe0.002SiO4 from a granulite facies terrain in southern India. The electrical resistivity of kalsilite was measured with four probe technique up to 7.5 GPa at room temperature. The electrical resistivity decreases continuously with the increase of pressure up to 3.7 GPa, where there is a discontinuous drop in the electrical resistivity by 14%–16% indicating a first order transition. Further increase of pressure does not induce any phase transition up to 7.5 GPa at room temperature. Fourier transform infrared (FTIR spectroscopy of the kalsilite sample at various pressures indicates that the observed transition is reversible in nature.

  11. Using DC electrical resistivity tomography to quantify preferential flow in fractured rock environments

    CSIR Research Space (South Africa)

    May, F

    2011-09-01

    Full Text Available . This investigation aims to identify preferential flow paths in fractured rock environments. Time-lapse Electrical Resistivity Tomography (TLERT, Lund Imaging System), is regarded as a suitable method for identifying preferential water flow....

  12. Electrical Resistance and Microstructure of Latex Modified Carbon Fiber Reinforced Cement Composites

    Institute of Scientific and Technical Information of China (English)

    WEI Jian; CHENG Feng; YUAN Hudie

    2012-01-01

    The electrical resistance,flexural strength,and microstructure of carbon fiber reinforced cement composites (CFRC) were improved greatly by adding water-redispersible latex powder.The electrical resistance of CFRC was investigated by two-probe method.The input range of CFRC based strain sensors was therefore increased,whereas electrical resistance was increased and remained in the perfect range of CFRC sensors.The analysis of scanning electron microscopy indicated that elastic latex bridges and a latex layer existed among the interspaces of the adjacent cement hydration products which were responsible for the enhancement of the flexural strength and electrical resistance.The formation mechanism of the elastic latex bridges was also discussed in detail.The continuous moving of two opposite interfaces of the latex solution-air along the interspaces of the adjacent hydrated crystals or colloids was attributed to the formation of the elastic latex bridges.

  13. Evaluation of Microscopic Degradation of Copper and Copper Alloy by Electrical Resistivity Measurement

    Energy Technology Data Exchange (ETDEWEB)

    Kim, Chung Seok [Hanyang University, Seoul (Korea, Republic of); Nahm, Seung Hoon [Korea Research Institute of Standards and Science, Daejeon (Korea, Republic of); Hyun, Chang Young [Seoul National University of Science and Technology, Seoul (Korea, Republic of)

    2010-10-15

    In the present study, the microscopic degradation of copper and copper and alloy subjected to cyclic deformation has been evaluated by the electrical resistivity measurement using the DC four terminal potential method. The copper (Cu) and copper alloy (Cu-35Zn), whose stacking fault energy is much different each other, were cyclically deformed to investigate the response of the electrical resistivity to different dislocation substructures. Dislocation cell substructure was developed in the Cu, while the planar array of dislocation structure was developed in the Cu-35Zn alloy increasing dislocation density with fatigue cycles. The electrical resistivity increased rapidly in the initial stage of fatigue deformation in both materials. Moreover, after the fatigue test it increased by about 7 % for the Cu and 6.5 % for the Cu-35Zn alloy, respectively. From these consistent results, it may be concluded that the dislocation cell structure responds to the electrical resistivity more sensitively than the planar array dislocation structure evolved during cyclic fatigue

  14. Electron–electron interactions and the electrical resistivity of lithium at low temperatures

    Indian Academy of Sciences (India)

    O N Awasthi; V K Pundhir

    2007-01-01

    The electron–electron interactions in lithium metal have been examined keeping in view the recent developments. The contribution of the electron–electron Umklapp scattering processes in the electrical resistivity of lithium at low temperatures has been evaluated using a simplified spherical Fermi surface model with isotropic transition probability. Our values of the electrical resistivity so obtained compare fairly well with the experimental results for lithium.

  15. Calculation formula for apparent electrical resistivity of high porosity metal materials

    Institute of Scientific and Technical Information of China (English)

    刘培生; 付超; 李铁藩

    1999-01-01

    A geometrical model has been established based on the structure feature of high porosity metal materials,the mathematical relationship between electrical resistivity and porosity for high porosity materials with even structure has then been deduced conveniently, and the formula for calculating the electrical resistivity of high porosity materials through porosity, which is easy to know, has been acquired further. Besides, the theoretical formula was verified to coincide with the test results well by the application taking nickel foam as an example.

  16. Electrical resistivity measurement to predict uniaxial compressive and tensile strength of igneous rocks

    Indian Academy of Sciences (India)

    Sair Kahraman; Tekin Yeken

    2010-12-01

    Electrical resistivity values of 12 different igneous rocks were measured on core samples using a resistivity meter in the laboratory. The resistivity tests were conducted on the samples fully saturated with brine (NaCl solution) and the uniaxial compressive strength (UCS), Brazilian tensile strength, density and porosity values of the samples were determined in the laboratory. The test results were evaluated using simple and multiple regression analysis. It was seen that the UCS and tensile strength values were linearly correlated with the electrical resistivity. The correlation coefficients are generally higher for the multiple regression models than that of the simple regression models. It was concluded that the UCS and tensile strength of igneous rocks can be estimated from electrical resistivity. However, the derived relations are purely empirical and they should be checked for other igneous rocks. The effect of rock types such as sedimentary and metamorphic rocks on the derived equations also needs to be investigated.

  17. Using different ELECTRE methods in strategic planning in the presence of human behavioral resistance

    Directory of Open Access Journals (Sweden)

    A. S. Milani

    2006-01-01

    Full Text Available In the multicriteria strategic planning of an organization, management should often be aware of employees' resistance to change before making new decisions; otherwise, a chosen strategy, though technologically acceptable, may not be efficient in the long term. This paper, using a sample case study within an organization, shows how different versions of ELECTRE methods can be used in choosing efficient strategies that account for both human behavioral resistance and technical elements. The effect of resistance from each subsystem of the organization is studied to ensure the reliability of the chosen strategy. The comparison of results from a select number of compensatory and noncompensatory models (ELECTRE I, III, IV, IS; TOPSIS; SAW; MaxMin suggests that when employee resistance is a decision factor in the multicriteria strategic planning problem, the models can yield low-resistance strategies; however, ELECTRE seems to show more reasonable sensitivity.

  18. Modeling of electrical impedance tomography to detect breast cancer by finite volume methods

    Science.gov (United States)

    Ain, K.; Wibowo, R. A.; Soelistiono, S.

    2017-05-01

    The properties of the electrical impedance of tissue are an interesting study, because changes of the electrical impedance of organs are related to physiological and pathological. Both physiological and pathological properties are strongly associated with disease information. Several experiments shown that the breast cancer has a lower impedance than the normal breast tissue. Thus, the imaging based on impedance can be used as an alternative equipment to detect the breast cancer. This research carries out by modelling of Electrical Impedance Tomography to detect the breast cancer by finite volume methods. The research includes development of a mathematical model of the electric potential field by 2D Finite Volume Method, solving the forward problem and inverse problem by linear reconstruction method. The scanning is done by 16 channel electrode with neighbors method to collect data. The scanning is performed at a frequency of 10 kHz and 100 kHz with three objects numeric includes an anomaly at the surface, an anomaly at the depth and an anomaly at the surface and at depth. The simulation has been successfully to reconstruct image of functional anomalies of the breast cancer at the surface position, the depth position or a combination of surface and the depth.

  19. Association of Obesity-Mediated Insulin Resistance and Hypothalamic Volumes: Possible Sex Differences

    Directory of Open Access Journals (Sweden)

    Jenny Ha

    2013-01-01

    Full Text Available The hypothalamus is important in hunger and metabolism. Although a lot is known about the basic role of the human hypothalamus, less is known about how the in vivo volume is affected in obesity, particularly among adolescents. Based on pediatric body mass index percentiles, 95 participants were assigned to lean or obese groups. All subjects had medical evaluations, including fasting blood tests, to assess insulin sensitivity and circulating CRP and neurotrophins (NGF and BDNF and an MRI of the brain. Hypothalamic volumes were measured by a segmentation method combining manual and automated steps. Overall, obese participants had descriptively smaller hypothalamic volumes, although this difference did not reach statistical significance; however, among obese participants, females had significantly smaller hypothalamic volumes than their male counterparts. There was a significant interaction between insulin resistance and sex on hypothalamus volume; obese females with significant insulin resistance have smaller hypothalamic volumes than obese males. Obese adolescents had higher circulating CRP and neurotrophin levels. Furthermore, among obese females, BDNF concentrations were inversely associated with hypothalamus volumes (r=−0.48. Given this negative association between BDNF and hypothalamus volumes among obese insulin-resistant females, elevated neurotrophin levels may suggest an attempt at protective compensation.

  20. Temperature dependence of the electrical resistance of sound and carious teeth

    NARCIS (Netherlands)

    Huysmans, MCDNJM; Longbottom, C; Christie, AM; Bruce, PG; Shellis, RP

    2000-01-01

    Temperature variations are expected to influence measurement error in electrical resistance of teeth. It was the aim of this study to determine the changes in electrical behavior of extracted human teeth due to temperature changes in the range of room temperature to intra-oral temperature. Nine extr

  1. Simple and stable transendothelial electrical resistance measurement in organs-on-chips

    NARCIS (Netherlands)

    van der Helm, Marieke Willemijn; Odijk, Mathieu; Frimat, Jean-Philippe; Eijkel, Jan C.T.; van den Berg, Albert; Segerink, Loes Irene

    2015-01-01

    Measuring transendothelial electrical resistance (TEER) is a popular way to monitor cellular barrier tightness in organs-on-chips. However, in these devices integrated electrodes often block sight on the cells and the measured part often includes fluid-filled channels with variable resistance.

  2. Evaluation of electrical resistivity anisotropy in geological mapping ...

    African Journals Online (AJOL)

    user

    Full Length Research Paper. Evaluation of ... Average annual rainfall for a thirty year record in the area is about 1270 .... layers; the first layer is the resistivity top soil and has resistivity range ... calculation of the reflection coefficient is the fractured .... J. NAH, 9: 41-50. ... Techniques of water resources investigations of the US.

  3. Direct localised measurement of electrical resistivity profile in rat and embryonic chick retinas using a microprobe

    Directory of Open Access Journals (Sweden)

    Harald van Lintel

    2010-01-01

    Full Text Available We report an alternative technique to perform a direct and local measurement of electrical resistivities in a layered retinal tissue. Information on resistivity changes along the depth in a retina is important for modelling retinal stimulation by retinal prostheses. Existing techniques for resistivity-depth profiling have the drawbacks of a complicated experimental setup, a less localised resistivity probing and/or lower stability for measurements. We employed a flexible microprobe to measure local resistivity with bipolar impedance spectroscopy at various depths in isolated rat and chick embryo retinas for the first time. Small electrode spacing permitted high resolution measurements and the probe flexibility contributed to stable resistivity profiling. The resistivity was directly calculated based on the resistive part of the impedance measured with the Peak Resistance Frequency (PRF methodology. The resistivity-depth profiles for both rat and chick embryo models are in accordance with previous mammalian and avian studies in literature. We demonstrate that the measured resistivity at each depth has its own PRF signature. Resistivity profiles obtained with our setup provide the basis for the construction of an electric model of the retina. This model can be used to predict variations in parameters related to retinal stimulation and especially in the design and optimisation of efficient retinal implants.

  4. Electric fields, weighting fields, signals and charge diffusion in detectors including resistive materials

    CERN Document Server

    AUTHOR|(CDS)2067623

    2016-01-01

    In this report we discuss static and time dependent electric fields in detector geometries with an arbitrary number of parallel layers of a given permittivity and weak conductivity. We derive the Green's functions i.e. the field of a point charge, as well as the weighting fields for readout pads and readout strips in these geometries. The effect of 'bulk' resistivity on electric fields and signals is investigated. The spreading of charge on thin resistive layers is also discussed in detail, and the conditions for allowing the effect to be described by the diffusion equation is discussed. We apply the results to derive fields and induced signals in Resistive Plate Chambers, Micromega detectors including resistive layers for charge spreading and discharge protection as well as detectors using resistive charge division readout like the MicroCAT detector. We also discuss in detail how resistive layers affect signal shapes and increase crosstalk between readout electrodes.

  5. Electrical resistance of CNT-PEEK composites under compression at different temperatures

    Directory of Open Access Journals (Sweden)

    Mohiuddin Mohammad

    2011-01-01

    Full Text Available Abstract Electrically conductive polymers reinforced with carbon nanotubes (CNTs have generated a great deal of scientific and industrial interest in the last few years. Advanced thermoplastic composites made of three different weight percentages (8%, 9%, and 10% of multiwalled CNTs and polyether ether ketone (PEEK were prepared by shear mixing process. The temperature- and pressure-dependent electrical resistance of these CNT-PEEK composites have been studied and presented in this paper. It has been found that electrical resistance decreases significantly with the application of heat and pressure.

  6. HIGH-VOLUME RESISTANCE TRAINING SESSION ACUTELY DIMINISHES RESPIRATORY MUSCLE STRENGTH

    Directory of Open Access Journals (Sweden)

    Daniel A. Hackett

    2012-03-01

    Full Text Available This study investigated the effect of a high-volume compared to a low-volume resistance training session on maximal inspiratory pressure (MIP and maximal expiratory pressure (MEP. Twenty male subjects with resistance training experience (6.2 ± 3.2 y, in a crossover trial, completed two resistance training protocols (high-volume: 5 sets per exercise; low-volume: 2 sets per exercise and a control session (no exercise on 3 separate occasions. MIP and MEP decreased by 13.6% (p < 0.01 and 14.7% (p < 0.01 respectively from pre-session MIP and MEP, following the high-volume session. MIP and MEP were unaffected following the low-volume or the control sessions. MIP returned to pre-session values after 40 minutes, whereas MEP remained significantly reduced after 60 minutes post-session by 9.2% compared to pre-session (p < 0.01. The findings suggest that the high-volume session significantly decreased MIP and MEP post-session, implicating a substantially increased demand on the respiratory muscles and that adequate recovery is mandatory following this mode of training.

  7. Application of electrical resistivity imaging on Divaška jama cave

    Directory of Open Access Journals (Sweden)

    Andrej Mihevc

    2011-12-01

    Full Text Available Electrical resistivity imaging (ERI is a widely used tool in geophysical survey of various subsurface structures. To establish its applicability for karst subsurface, ERI was conducted in Divača karst above caves of Trhlovca and Divaška jama and in its continuation as denuded cave on slopes of Radvanj collapse doline. Empty cave passages were not detected with ERI as electrical resistivity difference between voids and highly resistive carbonate bedrock is too small. On the other hand, denuded caves and cave sections, filled with loamy material, can be clearly distinguished.

  8. Electrical properties of deuteron irradiated high resistivity silicon

    Energy Technology Data Exchange (ETDEWEB)

    Krupka, Jerzy, E-mail: krupka@imio.pw.edu.pl [Insitute of Microelectronics and Optoelectronics, Warsaw University of Technology, Koszykowa 75, 00-662 Warsaw (Poland); Karcz, Waldemar [H. Niewodniczański Institute of Nuclear Physics Polish Academy of Science, Cracow (Poland); Joint Institute for Nuclear Research, Joliot-Curie 6, 141980 Dubna (Russian Federation); Avdeyev, Sergej P. [Joint Institute for Nuclear Research, Joliot-Curie 6, 141980 Dubna (Russian Federation); Kamiński, Paweł; Kozłowski, Roman [Institute of Electronic Materials Technology, Wólczyńska 133, 01-919 Warsaw (Poland)

    2014-04-01

    We have investigated resistivity changes introduced on the high-resistivity p-type silicon wafer by the irradiation with deuteron beam with an energy of 4.4 GeV performed in the NUCLOTRON superconducting accelerator. Two contactless techniques were used for the measurements of resistivity changes: namely the microwave split post dielectric resonator (SPDR) technique and capacitance measurements in the frequency domain. The first technique allows resistivity measurements in the plane of the wafer, while the second one in the direction perpendicular to the wafer. The resistivity map obtained with the SPDR technique enabled us to obtain a permanent fingerprint of the accelerator beam intensity profile. It has been shown that after the irradiation, the material resistivity increased to ∼3.9 × 10{sup 5} Ω cm in the wafer region exposed to the maximum beam intensity. Complementary studies of the properties and concentrations of radiation deep-level defects were performed by the high-resolution photo-induced current transient spectroscopy (HRPITS). These studies have shown that the irradiation of the high resistivity silicon with 4.4-GeV deuterons results in the formation of several types of deep-level defects responsible for the charge compensation.

  9. Thickness effect on electric resistivity on polystyrene and carbon black- based composites

    Energy Technology Data Exchange (ETDEWEB)

    Hernandez-Lopez, S; Vigueras-Santiago, E [Laboratorio de Investigacion y Desarrollo de Materiales Avanzados (LIDMA) Facultad de Quimica, Paseo Colon Esquina con Paseo Tollocan, s/n, CP 50000, Toluca (Mexico); Mayorga-Rojas, M; Reyes-Contreras, D, E-mail: eviguerass@uaemex.m [Facultad de Ciencias, Universidad Autonoma del Estado de Mexico. Av. Instituto Literario 100 Ote. C. P. 50000, Toluca (Mexico)

    2009-05-01

    Changes on electrical resistivity were experimentally studied for polystyrene and carbon black-based composites respect to the temperature. 22% w/w carbon black composite films at 30{mu}m, 2mm y 1cm thick were submitted to thermal heating-cooling cycles from room temperature to 100 deg. C, slightly up to T{sub g} of the composite. For each cycle changes on electrical resistivity constituent a hysteresis loop that depends on the sample thickness. The changes during the heating stage could be explained as a consequence of the thermal expansion and mobility of the polymer chains at T{sub g}, producing a disconnecting of the electrical contacts among carbon black particles and an important increasing (200%) of the electrical resistivity. For each cycle, the hysteresis loop was observed in thicker samples, whereas for 30 mu m thickness sample the hysteresis loop was lost after four cycles.

  10. Application of column tests and electrical resistivity methods for leachate transport monitoring

    Directory of Open Access Journals (Sweden)

    Wychowaniak Dorota

    2015-09-01

    Full Text Available Development of the human civilization leads to the pollution of environment. One of the contamination which are a real threat to soil and groundwater are leachates from landfills. In this paper the solute transport through soil was considered. For this purpose, the laboratory column tests of chlorides tracer and leachates transport on two soil samples have been carried out. Furthermore, the electrical resistivity method was applied as auxiliary tool to follow the movements of solute through the soil column what allowed to compare between the results obtained with column test method and electrical resistivity measurements. Breakthrough curves obtained by conductivity and resistivity methods represents similar trends which leads to the conclusion about the suitability of electrical resistivity methods for contamination transport monitoring in soil-water systems.

  11. Evaluation of Impact Damage Tolerance in Carbon Fabric/epoxy-matrix Composites by Electrical Resistance Measurement

    Institute of Scientific and Technical Information of China (English)

    LI Zhipeng; XIE Xiaolin; HONG Zhen; LU Chao; WANG Gaochao

    2012-01-01

    Impact damage tolerance is provided in intensity design on composites.The compression intensity of impacted composites requires more than 60% of its original intensity.The influence of impact on compressive intensity and electrical resistance of carbon fabric/epoxy-matrix composites was studied in this paper.The experimental results shows that impact can cause damage in composites,degenerate compressive intensity,and increase resistance.The electrical resistance change rate was used as an evaluation indicator of impact damage tolerance of composites.Impact damage,which results from the applying process of composites,can be identified in time by electrical resistance measurement.So,the safety performance of composites can also be improved.

  12. The effect of mechanical stress on electric resistance of nanographite-epoxy composites

    Science.gov (United States)

    Vovchenko, L.; Lazarenko, A.; Matzui, L.; Zhuravkov, A.

    2012-03-01

    The in-plane electric resistance Ra of composite materials (CMs) thermoexfoliated graphite(TEG)-epoxy resin(ED) under compression along compacting C-axis has been investigated by four-probe method. TEG content was 5-75 wt%. It was shown that specimens prepared by cold pressing are denser and reveal lower values of electric resistivity in comparison with specimens prepared by pouring. It was found that compression of the specimens leads to plastic deformation of specimens (εpl) and essential irreversible decrease of electric resistance during the first cycle of loading (up to 50 MPa), especially for the poured specimens with low density. Within the proposed model the contact resistance Rk between graphite particles in CM has been evaluated and it was shown that it increased with the decrease in TEG content in CM and depends on compacting method of CMs and the dispersity of graphite filler.

  13. Simulation method for cardiac stroke volume estimation by intracardiac electrical impedance measurement.

    Science.gov (United States)

    Barak, C; Leviatan, Y; Inbar, G F; Hoekstein, K N

    1992-09-01

    Using the electrical impedance measurement technique to investigate stroke volume estimation, three models of the ventricle were simulated. A four-electrode impedance catheter was used; two electrodes to set up an electric field in the model and the other two to measure the potential difference. A new approach, itself an application of the quasi-static case of a method used to solve electromagnetic field problems, was used to solve the electric field in the model. The behaviour of the estimation is examined with respect to the electrode configuration on the catheter and to catheter location with respect to the ventricle walls. Cardiac stroke volume estimation was found to be robust to catheter location generating a 10 per cent error for an offset of 40 per cent of the catheter from the chamber axis and rotation of 20 degrees with respect to the axis. The electrode configuration has a dominant effect on the sensitivity and accuracy of the estimation. Certain configurations gave high accuracy, whereas in others high sensitivity was found with lower accuracy. This led to the conclusion that the electrode configuration should be carefully chosen according to the desired criteria.

  14. Wind-electric icemaking project: Analysis and dynamometer testing. Volume 1

    Energy Technology Data Exchange (ETDEWEB)

    Holz, R; Gervorgian, V; Drouilhet, S; Muljadi, E

    1998-07-01

    The wind/hybrid systems group at the National Renewable Energy Laboratory has been researching the most practical and cost-effective methods for producing ice from off-grid wind-electric power systems. The first phase of the project, conducted in 1993--1994, included full-scale dynamometer and field testing of two different electric ice makers directly connected to a permanent magnet alternator. The results of that phase were encouraging and the second phase of the project was launched in which steady-state and dynamic numerical models of these systems were developed and experimentally validated. The third phase of the project was the dynamometer testing of the North Star ice maker, which is powered by a 12-kilowatt Bergey Windpower Company, Inc., alternator. This report describes both the second and third project phases. Also included are detailed economic analyses and a discussion of the future prospects of wind-electric ice-making systems. The main report is contained in Volume 1. Volume 2 consists of the report appendices, which include the actual computer programs used in the analysis and the detailed test results.

  15. Environmental control implications of generating electric power from coal. Technology status report. Volume II

    Energy Technology Data Exchange (ETDEWEB)

    None

    1976-12-01

    This is the first in a series of reports evaluating environmental control technologies applicable to the coal-to-electricity process. The technologies are described and evaluated from an engineering and cost perspective based upon the best available information obtained from utility experience and development work in progress. Environmental control regulations and the health effects of pollutants are also reviewed. Emphasis is placed primarily upon technologies that are now in use. For SO/sub 2/ control, these include the use of low sulfur coal, cleaned coal, or flue-gas desulfurization systems. Electrostatic precipitators and fabric filters used for the control of particulate matter are analyzed, and combustion modifications for NO/sub x/ control are described. In each area, advanced technologies still in the development stage are described briefly and evaluated on the basis of current knowledge. Fluidized-bed combustion (FBC) is a near-term technology that is discussed extensively in the report. The potential for control of SO/sub 2/ and NO/sub x/ emissions by use of FBC is analyzed, as are the resulting solid waste disposal problems, cost estimates, and its potential applicability to electric utility systems. Volume II presents the detailed technology analyses complete with reference citations. This same material is given in condensed form in Volume I without references. A brief executive summary is also given in Volume I.

  16. Finite-volume corrections to electromagnetic masses for larger-than-physical electric charges

    Science.gov (United States)

    Matzelle, Matthew E.; Tiburzi, Brian C.

    2017-05-01

    The numerical value of the fine-structure constant generally leads to small isospin-breaking effects due to electromagnetism in QCD. This smallness complicates determining isospin breaking from lattice QCD computations that include electromagnetism. One solution to this problem consists of performing computations using larger-than-physical values of the electric charge, and subsequently extrapolating (or interpolating) to the physical value of the fine-structure constant. Motivated by recent lattice QCD +QED computations of electromagnetic masses employing this setup, we consider finite-volume effects arising from the use of larger-than-physical electric charges. A modified power-counting scheme, which is based on treating the fine-structure constant as larger than its physical value, is explored. Results for perturbative QED corrections, however, are surprising. Within the framework of nonrelativistic QED, multiloop diagrams exhibit a momentum factorization property that produces exact cancellations. We determine that power-law finite-volume effects vanish at the leading two- and three-loop order, as well as the next-to-leading two-loop order. For larger-than-physical charges, we consequently expect no appreciable volume corrections beyond leading-order QED.

  17. Thermal treatment of low permeability soils using electrical resistance heating

    Energy Technology Data Exchange (ETDEWEB)

    Udell, K.S. [Univ. of California, Berkeley, CA (United States)

    1996-08-01

    The acceleration of recovery rates of second phase liquid contaminants from the subsurface during gas or water pumping operations is realized by increasing the soil and ground water temperature. Electrical heating with AC current is one method of increasing the soil and groundwater temperature and has particular applicability to low permeability soils. Several mechanisms have been identified that account for the enhanced removal of the contaminants during electrical heating. These are vaporization of liquid contaminants with low boiling points, temperature-enhanced evaporation rates of semi-volatile components, and removal of residual contaminants by the boiling of residual water. Field scale studies of electrical heating and fluid extraction show the effectiveness of this technique and its applicability to contaminants found both above and below the water table and within low permeability soils. 10 refs., 8 figs.

  18. Electrical resistivity tomography as monitoring tool for unsaturated zone transport: an example of preferential transport of deicing chemicals.

    Science.gov (United States)

    Wehrer, Markus; Lissner, Heidi; Bloem, Esther; French, Helen; Totsche, Kai Uwe

    2014-01-01

    Non-invasive spatially resolved monitoring techniques may hold the key to observe heterogeneous flow and transport behavior of contaminants in soils. In this study, time-lapse electrical resistivity tomography (ERT) was employed during an infiltration experiment with deicing chemical in a small field lysimeter. Deicing chemicals like potassium formate, which frequently impact soils on airport sites, were infiltrated during snow melt. Chemical composition of seepage water and the electrical response was recorded over the spring period 2010. Time-lapse electrical resistivity tomographs are able to show the infiltration of the melt water loaded with ionic constituents of deicing chemicals and their degradation product hydrogen carbonate. The tomographs indicate early breakthrough behavior in parts of the profile. Groundtruthing with pore fluid conductivity and water content variations shows disagreement between expected and observed bulk conductivity. This was attributed to the different sampling volume of traditional methods and ERT due to a considerable fraction of immobile water in the soil. The results show that ERT can be used as a soil monitoring tool on airport sites if assisted by common soil monitoring techniques.

  19. Core-scale electrical resistivity tomography (ERT) monitoring of CO2-brine mixture in Fontainebleau sandstone

    Science.gov (United States)

    Bosch, David; Ledo, Juanjo; Queralt, Pilar; Bellmunt, Fabian; Luquot, Linda; Gouze, Philippe

    2016-07-01

    The main goal of the monitoring stage of Carbon Capture and Storage (CCS) is to obtain an accurate estimation of the subsurface CO2 accumulation and to detect any possible leakage. Laboratory experiments are necessary to investigate the small scale processes governing the CO2-brine-rock interaction. They also provide a means to calibrate the results coming from field scale geophysical methods. In this work we set up an experimental system which is able to perform Electrical Resistivity Tomography (ERT) measurements on centimeter-scale rock samples at various P-T conditions. We present the results of two new experiments related to CO2 monitoring, performed on a cylindrical (4 × 8 cm) Fontainebleau rock sample. In the first one, we have quantified the CO2 saturation at different volume fractions, representing zones from a deep saline aquifer with varying degrees of saturation. In the second one, we have monitored and quantified the effect of CO2 dissolution in the brine at a pressure of 40 bar during eight days, emulating the invasion of CO2 into a shallow aquifer. Results highlight the importance of accounting for the contribution of surface conductivity in highly CO2-saturated regions, even in clay-free rocks, and also for brine conductivity variation due to CO2 dissolution. Ignoring any of these effects will end up in a CO2 saturation underestimation. We present a modified CO2 saturation equation to account for these two influences.

  20. Statistical analysis of electrical resistivity as a tool for estimating cement type of 12-year-old concrete specimens

    NARCIS (Netherlands)

    Polder, R.B.; Morales-Napoles, O.; Pacheco, J.

    2012-01-01

    Statistical tests on values of concrete resistivity can be used as a fast tool for estimating the cement type of old concrete. Electrical resistivity of concrete is a material property that describes the electrical resistance of concrete in a unit cell. Influences of binder type, water-to-binder rat

  1. Gas productivity related to cleat volumes derived from focused resistivity tools in coalbed methane (CBM) fields

    Energy Technology Data Exchange (ETDEWEB)

    Yang, Y.H.; Peeters, M.; Cloud, T.A.; Van Kirk, C.W. [Kerr McGee Rocky Mountain Corporation, Denver, CO (United States)

    2006-06-15

    Cleats are critical for coal-bed methane (CBM) production, but operators usually lack a viable method to determine productivity except for costly well tests. Wireline logs, run over the CBM deposits of the Drunkards Wash Unit located in the Uinta Basin of Utah, were used to develop a new method to relate productivity to the cleat volume. The latter is derived from a focused resistivity log and the wellbore-fluid resistivity. Induction tools are unsuitable for this method, because they are dominated by borehole effects in high resistivity coals and low resistivity mud. Moreover, they read too deep to be significantly affected by the substitution of formation fluid by borehole fluid in the cleats on which the method is based. The method was demonstrated by relating cleat volume to CBM gas productivity in 24 wells, an exercise that clearly separated good from poor producers.

  2. Ion acoustic instability of HPT particles, FAC density, anomalous resistivity and parallel electric field in the auroral region

    Indian Academy of Sciences (India)

    C S Jayasree; G Renuka; C Venugopal

    2003-12-01

    During the magnetic storm of 21st March 1990, the DE-1 spacecraft encountered the auroral region at high invariant latitude at altitudes ranging from a few thousand kilometers in the ionosphere to many earth radii in the magnetosphere. The magnetic field perturbations interpretable as field aligned current (FAC) layers and the electrostatic turbulence possibly due to electrostatic ion acoustic instability driven by these currents are shown. The critical drift velocity of Hot Plasma Torus (HPT) electrons and the growth rate of ion acoustic wave as a function of electron to ion temperature ratio (/) for low and high current densities and energy of HPT electrons are found out. The intense FAC destabilizes the ion acoustic wave and the resultant electrostatic turbulence creates an anomalous resistivity. The current driven resistivity produces parallel electric field and high power dissipation. The anomalous resistivity , potential differnece along the auroral field lines ∥, intensity of electric field turbulence ∥ and power produced per unit volume are computed. It is found that the change in westward magnetic perturbation increases ∥; ; ∥ ;∥ and . Hence HPT electrons are heated and accelerated due to power dissipation during magnetically active periods in the auroral region. Concerning, applications, such HPT electrons can be used in particle accelerators like electron ring accelerator, smokatron etc.

  3. Modeling Fluid Flow and Electrical Resistivity in Fractured Geothermal Reservoir Rocks

    Energy Technology Data Exchange (ETDEWEB)

    Detwiler, R L; Roberts, J J; Ralph, W; Bonner, B P

    2003-01-14

    Phase change of pore fluid (boiling/condensing) in rock cores under conditions representative of geothermal reservoirs results in alterations of the electrical resistivity of the samples. In fractured samples, phase change can result in resistivity changes that are more than an order of magnitude greater than those measured in intact samples. These results suggest that electrical resistivity monitoring may provide a useful tool for monitoring the movement of water and steam within fractured geothermal reservoirs. We measured the electrical resistivity of cores of welded tuff containing fractures of various geometries to investigate the resistivity contrast caused by active boiling and to determine the effects of variable fracture dimensions and surface area on water extraction. We then used the Nonisothermal Unsaturated Flow and Transport model (NUFT) (Nitao, 1998) to simulate the propagation of boiling fronts through the samples. The simulated saturation profiles combined with previously reported measurements of resistivity-saturation curves allow us to estimate the evolution of the sample resistivity as the boiling front propagates into the rock matrix. These simulations provide qualitative agreement with experimental measurements suggesting that our modeling approach may be used to estimate resistivity changes induced by boiling in more complex systems.

  4. Independent Orbiter Assessment (IOA): Analysis of the Electrical Power Distribution and Control Subsystem, Volume 2

    Science.gov (United States)

    Schmeckpeper, K. R.

    1987-01-01

    The results of the Independent Orbiter Assessment (IOA) of the Failure Modes and Effects Analysis (FMEA) and Critical Items List (CIL) are presented. The IOA approach features a top-down analysis of the hardware to determine failure modes, criticality, and potential critical items. To preserve independence, this analysis was accomplished without reliance upon the results contained within the NASA FMEA/CIL documentation. This report documents the independent analysis results corresponding to the Orbiter Electrical Power Distribution and Control (EPD and C) hardware. The EPD and C hardware performs the functions of distributing, sensing, and controlling 28 volt DC power and of inverting, distributing, sensing, and controlling 117 volt 400 Hz AC power to all Orbiter subsystems from the three fuel cells in the Electrical Power Generation (EPG) subsystem. Volume 2 continues the presentation of IOA analysis worksheets and contains the potential critical items list.

  5. Parallel PWTD-Accelerated Explicit Solution of the Time Domain Electric Field Volume Integral Equation

    KAUST Repository

    Liu, Yang

    2016-03-25

    A parallel plane-wave time-domain (PWTD)-accelerated explicit marching-on-in-time (MOT) scheme for solving the time domain electric field volume integral equation (TD-EFVIE) is presented. The proposed scheme leverages pulse functions and Lagrange polynomials to spatially and temporally discretize the electric flux density induced throughout the scatterers, and a finite difference scheme to compute the electric fields from the Hertz electric vector potentials radiated by the flux density. The flux density is explicitly updated during time marching by a predictor-corrector (PC) scheme and the vector potentials are efficiently computed by a scalar PWTD scheme. The memory requirement and computational complexity of the resulting explicit PWTD-PC-EFVIE solver scale as ( log ) s s O N N and ( ) s t O N N , respectively. Here, s N is the number of spatial basis functions and t N is the number of time steps. A scalable parallelization of the proposed MOT scheme on distributed- memory CPU clusters is described. The efficiency, accuracy, and applicability of the resulting (parallelized) PWTD-PC-EFVIE solver are demonstrated via its application to the analysis of transient electromagnetic wave interactions on canonical and real-life scatterers represented with up to 25 million spatial discretization elements.

  6. Experimental determination of the electrical resistivity of iron at Earth’s core conditions

    Science.gov (United States)

    Ohta, Kenji; Kuwayama, Yasuhiro; Hirose, Kei; Shimizu, Katsuya; Ohishi, Yasuo

    2016-06-01

    Earth continuously generates a dipole magnetic field in its convecting liquid outer core by a self-sustained dynamo action. Metallic iron is a dominant component of the outer core, so its electrical and thermal conductivity controls the dynamics and thermal evolution of Earth’s core. However, in spite of extensive research, the transport properties of iron under core conditions are still controversial. Since free electrons are a primary carrier of both electric current and heat, the electron scattering mechanism in iron under high pressure and temperature holds the key to understanding the transport properties of planetary cores. Here we measure the electrical resistivity (the reciprocal of electrical conductivity) of iron at the high temperatures (up to 4,500 kelvin) and pressures (megabars) of Earth’s core in a laser-heated diamond-anvil cell. The value measured for the resistivity of iron is even lower than the value extrapolated from high-pressure, low-temperature data using the Bloch-Grüneisen law, which considers only the electron-phonon scattering. This shows that the iron resistivity is strongly suppressed by the resistivity saturation effect at high temperatures. The low electrical resistivity of iron indicates the high thermal conductivity of Earth’s core, suggesting rapid core cooling and a young inner core less than 0.7 billion years old. Therefore, an abrupt increase in palaeomagnetic field intensity around 1.3 billion years ago may not be related to the birth of the inner core.

  7. Assessment of groundwater vulnerability to leachate infiltration using electrical resistivity method

    Science.gov (United States)

    Mosuro, G. O.; Omosanya, K. O.; Bayewu, O. O.; Oloruntola, M. O.; Laniyan, T. A.; Atobi, O.; Okubena, M.; Popoola, E.; Adekoya, F.

    2016-02-01

    This aim of this work is to assess the degree of leachate infiltration at a dumpsite in Agbara industrial estate, Southwestern Nigeria using electrical resistivity techniques. Around the dumpsite were 45 vertical electrical sounding (VES) stations and 3 electrical resistivity tomography profiles. Current electrode spread varied from 300 to 600 m for the electrical sounding. Electrode configuration includes Schlumberger and Wenner array for sounding and profiling. The state of leachate contamination was tested using parameters such as aquifer vulnerability index, overburden protective capacity and longitudinal unit conductance (Si) derived from the apparent resistivity values. Four principal geoelectric layers inferred from the VES data include the topsoil, sand, clayey sand, and clay/shale. Resistivity values for these layers vary from 3 to 1688, 203 to 3642 123 to 388, and 67 to 2201 Ω m with corresponding thickness of 0.8-2.4, 2.5-140, 3-26 m and infinity, respectively. The leachate plume occurs at a maximum depth of 10 m on the 2-D inverse models of real electrical resistivity with an average depth of infiltration being 6 m in the study area. The correlation between longitudinal conductance and overburden protective capacity show that aquifers around the dumpsite have poor protective capacity and are vulnerable to leachate contamination. Leachate infiltration is favored by the absence of lithological barriers such as clay which in the study area are either mixed with sand or positioned away from the aquifer.

  8. Assessment of groundwater vulnerability to leachate infiltration using electrical resistivity method

    Science.gov (United States)

    Mosuro, G. O.; Omosanya, K. O.; Bayewu, O. O.; Oloruntola, M. O.; Laniyan, T. A.; Atobi, O.; Okubena, M.; Popoola, E.; Adekoya, F.

    2017-09-01

    This aim of this work is to assess the degree of leachate infiltration at a dumpsite in Agbara industrial estate, Southwestern Nigeria using electrical resistivity techniques. Around the dumpsite were 45 vertical electrical sounding (VES) stations and 3 electrical resistivity tomography profiles. Current electrode spread varied from 300 to 600 m for the electrical sounding. Electrode configuration includes Schlumberger and Wenner array for sounding and profiling. The state of leachate contamination was tested using parameters such as aquifer vulnerability index, overburden protective capacity and longitudinal unit conductance (S i) derived from the apparent resistivity values. Four principal geoelectric layers inferred from the VES data include the topsoil, sand, clayey sand, and clay/shale. Resistivity values for these layers vary from 3 to 1688, 203 to 3642 123 to 388, and 67 to 2201 Ω m with corresponding thickness of 0.8-2.4, 2.5-140, 3-26 m and infinity, respectively. The leachate plume occurs at a maximum depth of 10 m on the 2-D inverse models of real electrical resistivity with an average depth of infiltration being 6 m in the study area. The correlation between longitudinal conductance and overburden protective capacity show that aquifers around the dumpsite have poor protective capacity and are vulnerable to leachate contamination. Leachate infiltration is favored by the absence of lithological barriers such as clay which in the study area are either mixed with sand or positioned away from the aquifer.

  9. The relaxation effects of the volume properties of electrically conducting viscoelastic material

    Energy Technology Data Exchange (ETDEWEB)

    Ezzat, Magdy A. [Faculty of Education, Department of Mathematics, Alexandria University, Alexandria (Egypt)]. E-mail: m_ezzat2000@Yahoo.com

    2006-06-15

    A new model of the equations of generalized thermo-viscoelasticity for an electrically conducting isotropic media permeated by a primary uniform magnetic field, taking into consideration the rheological properties of the volume, is given. The formulation is applied to both generalizations, Lord-Shulman theory and the Green-Lindsay theory, as well as to the coupled theory. The state space approach is adopted for the solution of one-dimensional problems in the absence or presence of heat sources. The Laplace-transform technique is used. A numerical method is employed for the inversion of the Laplace transforms. Numerical results for the stress distribution are given and illustrated graphically for each problem. Comparisons are made with the results predicted by the three theories, or ignoring the viscous effects of the volume. Also, the effect of the magnetic field is studied. It is found that the consideration of these effects is to decrease the thermal stresses.

  10. A Calderón multiplicative preconditioner for coupled surface-volume electric field integral equations

    KAUST Repository

    Bagci, Hakan

    2010-08-01

    A well-conditioned coupled set of surface (S) and volume (V) electric field integral equations (S-EFIE and V-EFIE) for analyzing wave interactions with densely discretized composite structures is presented. Whereas the V-EFIE operator is well-posed even when applied to densely discretized volumes, a classically formulated S-EFIE operator is ill-posed when applied to densely discretized surfaces. This renders the discretized coupled S-EFIE and V-EFIE system ill-conditioned, and its iterative solution inefficient or even impossible. The proposed scheme regularizes the coupled set of S-EFIE and V-EFIE using a Calderón multiplicative preconditioner (CMP)-based technique. The resulting scheme enables the efficient analysis of electromagnetic interactions with composite structures containing fine/subwavelength geometric features. Numerical examples demonstrate the efficiency of the proposed scheme. © 2006 IEEE.

  11. Electric and Hybrid Vehicle System Research and Development Project: Hybrid Vehicle Potential Assessment. Volume 1. Summary

    Energy Technology Data Exchange (ETDEWEB)

    Surber, F.T.

    1979-09-30

    The results of investigations conducted under Ce Hybrid Vehicle Potential Assessment Task are reported in 10 volumes. This volume contains an overview of the study and its results. The purpose of the overall study was to determine if the petroleum fuel savings achievable through the use of hybrid electric vehicles is worth the R and D expenditures needed to develop the hybrid vehicles and to determine R and D priorities. It was concluded that by the year 2010 hybrid vehicles could replace 80% of the automotive power that would otherwise be produced from petroleum fuels; the public should not suffer any mobility loss through the use of hybrid vehicles; high initial and life-cycle costs are a limiting factor; and R and D funds should be spent for systems design and the development of low-cost batteries and controllers. (LCL)

  12. Time-lapse electrical resistivity tomography: a powerful tool for landslide monitoring?

    Science.gov (United States)

    Perrone, A.

    2011-12-01

    The extreme rainfall events and the quick snowmelt occurrences play an important role in the triggering of the landslides. The occurrence of one of these factors can determine the variation of water content in the first layers of the subsoil and as a consequence a quick soil saturation inducing both an increase in pore-water pressures and the overloaded of the slopes progressively collapsing. The electrical resistivity, self-potential, electromagnetic induction and GPR methods can be considered as the most appropriate for assessing the presence of water in the underground. Such methods allow us to study the behavior of water content over much wider and deeper areas than those offered by traditional methods (thermo-gravimetric, tensiometric, TDR, etc) based on spot measures and concerning small volumes. In particular, the Electrical Resistivity Tomography (ERT), which has already proved to be a powerful tool both for the geometrical reconstruction of a landslide body (location of sliding surface, estimation of the thickness of the slide material) and the individuation of high water content areas, can be considered as an alternative tool to be employed for a qualitative and quantitative water content monitoring in the first layers of the subsoil. Indeed, time-lapse 2D ERT can be tested in order to gather information on the temporal and spatial patterns of water infiltration processes and water content variation. This work reports the preliminary results from a new prototype system planned to obtain time-lapse 2D ERTs, TDR and precipitation measurements in two landslide areas located in the Southern Apennine chain (Italy). The system was planned with the aim to estimate the variation of the resistivity parameter on a long period considering the water content variation, the rain water infiltration and the seasonal changes. The prototype system, linked to a pc used for storing data and managing the time interval acquisition, consists of: a resistivimeter connected to a

  13. Standard technical specifications General Electric plants, BWR/6. Volume 1, Revision 1

    Energy Technology Data Exchange (ETDEWEB)

    NONE

    1995-04-01

    This report documents the results of the combined effort of the NRC and the industry to produce improved Standard Technical Specifications (STS), Revision 1 for General Electric BWR/6 Plants. The changes reflected in Revision 1 resulted from the experience gained from license amendment applications to convert to these improved STS or to adopt partial improvements to existing technical specifications. This NUREG is the result of extensive public technical meetings and discussions between the Nuclear Regulatory Commission (NRC) staff and various nuclear power plant licensees, Nuclear Steam Supply System (NSSS) Owners Groups, NSSS vendors, and the Nuclear Energy Institute (NEI). The improved STS were developed based on the criteria in the Final Commission Policy Statement on Technical Specifications Improvements for Nuclear Power Reactors, dated July 22, 1993. The improved STS will be used as the basis for individual nuclear power plant licensees to develop improved plant-specific technical specifications. This report contains three volumes. Volume 1 contains the Specifications for all chapters and sections of the improved STS. Volume 2 contains the Bases for Chapters 2.0 and 3.0, and Sections 3.1--3.3 of the improved STS. Volume 3 contains the Bases for Sections 3.4--3.10 of the improved STS.

  14. On the Modeling of Electrical Effects Experienced by Space Explorers During Extra Vehicular Activities: Intracorporal Currents, Resistances, and Electric Fields

    Science.gov (United States)

    Cela, Carlos J.; Loizos, Kyle; Lazzi, Gianluca; Hamilton, Douglas; Lee, Raphael C.

    2011-01-01

    Recent research has shown that space explorers engaged in Extra Vehicular Activities (EVAs) may be exposed, under certain conditions, to undesired electrical currents. This work focuses on determining whether these undesired induced electrical currents could be responsible for involuntary neuromuscular activity in the subjects, possibly caused by either large diameter peripheral nerve activation or reflex activity from cutaneous afferent stimulation. An efficient multiresolution variant of the admittance method along with a millimeter-resolution model of a male human body were used to calculate induced electric fields, resistance between contact electrodes used to simulate the potential exposure condition, and currents induced in the human body model. Results show that, under realistic exposure conditions using a 15V source, current density magnitudes and total current injected are well above previously reported startle reaction thresholds. This indicates that, under the considered conditions, the subjects could experience involuntary motor response.

  15. Permanent electrical resistivity measurements for monitoring water circulation in clayey landslides

    Science.gov (United States)

    Gance, J.; Malet, J.-P.; Supper, R.; Sailhac, P.; Ottowitz, D.; Jochum, B.

    2016-03-01

    Landslides developed on clay-rich slopes are controlled by the soil water regime and the groundwater circulation. Spatially-distributed and high frequency observations of these hydrological processes are important for improving our understanding and prediction of landslide triggering. This work presents observed changes in electrical resistivity monitored at the Super-Sauze clayey landslide with the GEOMON 4D resistivity instrument installed permanently on-site for a period of one year. A methodological framework for processing the raw measurement is proposed. It includes the filtering of the resistivity dataset, the correction of the effects of non-hydrological factors (sensitivity of the device, sensitivity to soil temperature and fluid conductivity, presence of fissures in the topsoil) on the filtered resistivity values. The interpretation is based on a statistical analysis to define possible relationships between the rainfall characteristics, the soil hydrological observations and the soil electrical resistivity response. During the monitoring period, no significant relationships between the electrical response and the measured hydrological parameters are evidenced. We discuss the limitations of the method due to the effect of heat exchange between the groundwater, the vadose zone water and the rainwater that hides the variations of resistivity due to variations of the soil water content. We demonstrate that despite the absence of hydrogeophysical information for the vadose zone, the sensitivity of electrical resistivity monitoring to temperature variations allows imaging water fluxes in the saturated zone and highlighting the existence of matrix and preferential flows that does not occur at the same time and for the same duration. We conclude on the necessity to combine electrical resistivity measurements with distributed soil temperature measurements.

  16. Relationship between electrical skin resistance and rectal temperature in man during physical exercise.

    Science.gov (United States)

    Grucza, R

    1984-01-01

    Electrical skin resistance (ESR) and rectal temperature (Tre) were examined in 13 unacclimated human subjects performing bicycle exercise at an intensity of 50% VO2max. After the beginning of exercise the electrical skin resistance decreased according to an exponential curve with a delay of 4 min and time constant of 9 min. The dynamic parameters of ESR were shorter than those reported for sweating. Statistical analysis showed a correlation between individual time constants of ESR and increases in rectal temperature of the subjects (r = 0.705, p less than 0.01). It is concluded that measurement of dynamics of the electrical skin resistance may be useful for estimation of thermal effects in exercising subjects.

  17. Understanding Electrical Conduction States in WO3 Thin Films Applied for Resistive Random-Access Memory

    Science.gov (United States)

    Ta, Thi Kieu Hanh; Pham, Kim Ngoc; Dao, Thi Bang Tam; Tran, Dai Lam; Phan, Bach Thang

    2016-05-01

    The electrical conduction and associated resistance switching mechanism of top electrode/WO3/bottom electrode devices [top electrode (TE): Ag, Ti; bottom electrode (BE): Pt, fluorine-doped tin oxide] have been investigated. The direction of switching and switching ability depended on both the top and bottom electrode material. Multiple electrical conduction mechanisms control the leakage current of such switching devices, including trap-controlled space-charge, ballistic, Ohmic, and Fowler-Nordheim tunneling effects. The transition between electrical conduction states is also linked to the switching (SET-RESET) process. This is the first report of ballistic conduction in research into resistive random-access memory. The associated resistive switching mechanisms are also discussed.

  18. Hydrogeological characterisation using cross-borehole ground penetration radar and electrical resistivity tomography

    DEFF Research Database (Denmark)

    Zibar, Majken Caroline Looms

    2007-01-01

    . The methods provided estimates of soil moisture content and electrical resistivity variations among 12 m deep boreholes located 5 – 7 m apart. The moisture content change following natural precipitation was observed to be practically negligible, providing minimal information to constrain the dynamic...... was characterized by ~30 m thick unsaturated zone consisting mainly of sands of varying coarseness. Following an instrumentation of 16 boreholes two geophysical methods (cross-borehole ground penetrating radar and electrical resistivity tomography) were applied during natural precipitation and forced infiltration...... properties of the subsurface. On the other hand, volumetric moisture content variations of up to 5% were observed during a 20-day long forced infiltration experiment. The cross-borehole electrical resistance tomography and ground penetrating radar data collected during this experiment were subsequently...

  19. Electrical resistivity of nanoporous gold modified with thiol self-assembled monolayers

    Science.gov (United States)

    Hakamada, Masataka; Kato, Naoki; Mabuchi, Mamoru

    2016-11-01

    The electrical resistivity of nanoporous gold (NPG) modified with thiol self-assembled monolayers (SAMs) has been measured at 298 K using a four-probe method. We found that the adsorption of thiol SAMs increases the electrical resistivity of NPG by up to 22.2%. Dependence of the electrical resistivity on the atmosphere (air or water) was also observed in SAMs-modified NPG, suggesting that the electronic states of the tail groups affect the electrons of the binding sulfur and adjacent surface gold atoms. The present results suggest that adsorption of thiol molecules can influence the behavior of the conducting electrons in NPG and that modification of NPG with SAMs may be useful for environmental sensing.

  20. SiC fiber with low electrical resistivity and oxygen content

    Institute of Scientific and Technical Information of China (English)

    2010-01-01

    A new SiC fiber was prepared by the pyrolysis of polycarbosilane(PCS) fiber cured with unsaturated hydrocarbons.The fiber,with oxygen content of 4-6 wt%,offers high tensile strength of 2.5-2.8 GPa.The electrical resistivity of the fiber is only about 0.5 Ω·cm,much lower than general SiC fiber obtained from traditional air curing process.Degradation of mechanical property in argon and air at high temperature is retarded by 200-300℃ with respect to the Nicalon NL-202 fiber.The low electrical resistivity of the fiber exhibits excellent thermal stability,it almost remains 0.4-0.8 Ω·cm after thermal exposure test from the room temperature to 1600℃ in argon.The low electrical resistivity mainly attribute to an excess carbon layer which is about 50 nm in the circular outer part.

  1. Hydrogeological characterisation using cross-borehole ground penetration radar and electrical resistivity tomography

    DEFF Research Database (Denmark)

    Zibar, Majken Caroline Looms

    2007-01-01

    . The methods provided estimates of soil moisture content and electrical resistivity variations among 12 m deep boreholes located 5 – 7 m apart. The moisture content change following natural precipitation was observed to be practically negligible, providing minimal information to constrain the dynamic...... was characterized by ~30 m thick unsaturated zone consisting mainly of sands of varying coarseness. Following an instrumentation of 16 boreholes two geophysical methods (cross-borehole ground penetrating radar and electrical resistivity tomography) were applied during natural precipitation and forced infiltration...... properties of the subsurface. On the other hand, volumetric moisture content variations of up to 5% were observed during a 20-day long forced infiltration experiment. The cross-borehole electrical resistance tomography and ground penetrating radar data collected during this experiment were subsequently...

  2. Categorical modeling on electrical anomaly of room-and-pillar coal mine fires and application for field electrical resistivity tomography

    Science.gov (United States)

    Song, Wujun; Wang, Yanming; Shao, Zhenlu

    2017-01-01

    In order to improve the accuracy of fire area delineation in coalfield with electrical prospecting, the categorical geoelectric models of coal fires are established according to geological and mining conditions. The room-and-pillar coal mine fires are divided into three types which are coal seam fire, goaf fire and subsidence area fire, respectively, and forward electrical simulations and inversion analysis of each type of coal fire are implemented. Simulation results show that the resistance anomalies of goaf fires exist around one and a half to two times higher than background field, in contrast, coal seam and subsidence area fires performance low resistivity response which are roughly half to two-third of background field resistivity, respectively. Identification of different fire types and delineation of coal fire areas are further presented. The inversion results which are validated by borehole survey prove that the presented method could eliminate the omission of coal fires with high resistance anomaly and provide a novel reference for fire extinguishing in the future.

  3. Reasons for the weak correlation between prostate volume and urethral resistance parameters in patients with prostatism

    NARCIS (Netherlands)

    J.L.H.R. Bosch (Ruud); R. Kranse (Ries); R. van Mastrigt (Ron); F.H. Schröder (Fritz); W.K. Mebust (W.)

    1995-01-01

    textabstractIn an attempt to increase our understanding of the clinical syndrome of benign prostatic hyperplasia (BPH) an analysis was made of the association between prostate volume as measured by transrectal ultrasound and several reported urodynamically determined urethral resistance parameters.

  4. Creatine Kinase Activity Weakly Correlates to Volume Completed Following Upper Body Resistance Exercise

    Science.gov (United States)

    Machado, Marco; Willardson, Jeffrey M.; Silva, Dailson P.; Frigulha, Italo C.; Koch, Alexander J.; Souza, Sergio C.

    2012-01-01

    In the current study, we examined the relationship between serum creatine kinase (CK) activity following upper body resistance exercise with a 1- or 3-min rest between sets. Twenty men performed two sessions, each consisting of four sets with a 10-repetition maximum load. The results demonstrated significantly greater volume for the 3-min…

  5. Creatine Kinase Activity Weakly Correlates to Volume Completed Following Upper Body Resistance Exercise

    Science.gov (United States)

    Machado, Marco; Willardson, Jeffrey M.; Silva, Dailson P.; Frigulha, Italo C.; Koch, Alexander J.; Souza, Sergio C.

    2012-01-01

    In the current study, we examined the relationship between serum creatine kinase (CK) activity following upper body resistance exercise with a 1- or 3-min rest between sets. Twenty men performed two sessions, each consisting of four sets with a 10-repetition maximum load. The results demonstrated significantly greater volume for the 3-min…

  6. Fully Electrical Modeling of Thermoelectric Generators with Contact Thermal Resistance Under Different Operating Conditions

    Science.gov (United States)

    Siouane, Saima; Jovanović, Slaviša; Poure, Philippe

    2017-01-01

    The Seebeck effect is used in thermoelectric generators (TEGs) to supply electronic circuits by converting the waste thermal into electrical energy. This generated electrical power is directly proportional to the temperature difference between the TEG module's hot and cold sides. Depending on the applications, TEGs can be used either under constant temperature gradient between heat reservoirs or constant heat flow conditions. Moreover, the generated electrical power of a TEG depends not only on these operating conditions, but also on the contact thermal resistance. The influence of the contact thermal resistance on the generated electrical power have already been extensively reported in the literature. However, as reported in Park et al. (Energy Convers Manag 86:233, 2014) and Montecucco and Knox (IEEE Trans Power Electron 30:828, 2015), while designing TEG-powered circuit and systems, a TEG module is mostly modeled with a Thévenin equivalent circuit whose resistance is constant and voltage proportional to the temperature gradient applied to the TEG's terminals. This widely used simplified electrical TEG model is inaccurate and not suitable under constant heat flow conditions or when the contact thermal resistance is considered. Moreover, it does not provide realistic behaviour corresponding to the physical phenomena taking place in a TEG. Therefore, from the circuit designer's point of view, faithful and fully electrical TEG models under different operating conditions are needed. Such models are mainly necessary to design and evaluate the power conditioning electronic stages and the maximum power point tracking algorithms of a TEG power supply. In this study, these fully electrical models with the contact thermal resistance taken into account are presented and the analytical expressions of the Thévenin equivalent circuit parameters are provided.

  7. Fully Electrical Modeling of Thermoelectric Generators with Contact Thermal Resistance Under Different Operating Conditions

    Science.gov (United States)

    Siouane, Saima; Jovanović, Slaviša; Poure, Philippe

    2016-09-01

    The Seebeck effect is used in thermoelectric generators (TEGs) to supply electronic circuits by converting the waste thermal into electrical energy. This generated electrical power is directly proportional to the temperature difference between the TEG module's hot and cold sides. Depending on the applications, TEGs can be used either under constant temperature gradient between heat reservoirs or constant heat flow conditions. Moreover, the generated electrical power of a TEG depends not only on these operating conditions, but also on the contact thermal resistance. The influence of the contact thermal resistance on the generated electrical power have already been extensively reported in the literature. However, as reported in Park et al. (Energy Convers Manag 86:233, 2014) and Montecucco and Knox (IEEE Trans Power Electron 30:828, 2015), while designing TEG-powered circuit and systems, a TEG module is mostly modeled with a Thévenin equivalent circuit whose resistance is constant and voltage proportional to the temperature gradient applied to the TEG's terminals. This widely used simplified electrical TEG model is inaccurate and not suitable under constant heat flow conditions or when the contact thermal resistance is considered. Moreover, it does not provide realistic behaviour corresponding to the physical phenomena taking place in a TEG. Therefore, from the circuit designer's point of view, faithful and fully electrical TEG models under different operating conditions are needed. Such models are mainly necessary to design and evaluate the power conditioning electronic stages and the maximum power point tracking algorithms of a TEG power supply. In this study, these fully electrical models with the contact thermal resistance taken into account are presented and the analytical expressions of the Thévenin equivalent circuit parameters are provided.

  8. Relationship of electrical resistance end morphological changes thigh rats after modeling of open fracture (experimental study

    Directory of Open Access Journals (Sweden)

    Pavlova T.M.

    2016-06-01

    Full Text Available Background. Due to the development of industry, increasing number of vehicles on the roads rate of traumatic injuries among adult population causing disability and mortality is still high in all countries of the world. Among all fractures of long bones open diaphyseal fractures ranges from 28% to 53%. Objective. To study the relationship of electrical resistance and morphological features of the femur of white male rats after modeling the open fracture. Methods. Studies were conducted on white male rats aged about 3 months. Digital multimeter UT70B was used to measure the electrical resistance of bones in experimental animals after 1 and 3 hours of experimental modeling of opened bone fracture. Histological and electron microscopic studies were performed to evaluate bone structure. Results. 1 hour after modeling an open bone fracture it was detected the presence of empty lacunae or gaps filled with detritus. 3 hours after the experiment cellular density in the first studied area was reduced 4.1 times, in the second area - 3.2 times comparing with the control. Conclusion. These histological examination and study of the electrical resistance of bone fragments after re-fracture (with or without coagulation fragments indicate similar changes in direction of the bone. Electrical resistance after testing in the clinical setting can be used for testing the bone fragments after an open fracture to assess viability. We have developed a technique for evaluation the electrical resistance making it possible to predict the viability of bone tissue with opened diaphyseal fractures of extremities on early stages. Citation: Pavlova TM, Berezka MI. [Relationship of electrical resistance end morphological changes thigh rats after mod-eling of open fracture (experimental study]. Morphologia. 2016;10(2:31-9. Ukrainian.

  9. General Relationship between Field Electrical Resistivity Value (ERV and Basic Geotechnical Properties (BGP

    Directory of Open Access Journals (Sweden)

    Mohd Hazreek Zainal Abidin

    2014-09-01

    Full Text Available Electrical resistivity technique is a popular alternative method used in geotechnical soil investigations. Most past applications have been particularly in the area of subsurface ground investigations such as to locate boulder, bedrock, water table, etc. Traditionally, this method was performed by a geophysicist expert for data acquisition, processing and interpretation. The final outcome from the electrical resistivity technique was an anomaly image which used to describe and conclude the particular soil condition measured. The anomalies highlighted uncertainties on the nature of soil that was often variable and depended on each particular site condition that gave a site dependent soil electrical resistivity value (ERV. Hence, this study demonstrates a relationship between ERV (ρ and some of the basic geotechnical properties (BGP such as soil moisture content (w, grain size of geomaterial (CS or FS, density (ρbulk and ρdry, porosity (η, void ratio (e and Atterberg limit (AL. Different soil samples were collected and tested under field and laboratory conditions to determine basic geotechnical properties immediately after the field electrical resistivity method was performed. It was found that the electrical resistivity value was different for number of soils tested and was relatively subjective to variations in the geotechnical properties. In other words, electrical resistivity value was greatly influenced by the geotechnical properties as the ERV was higher due to the lower moisture content, void ratio and porosity with a higher value of soil density and vice versa. The relationship of ERV and BGP can be described by ρ α 1/w, ρ α CS, ρ α 1/FS, ρ α ρbulk/dry and ρ α 1/AL. Hence, it was shown that behaviour of ERV was significantly influenced by the variation of basic soil properties and thus applicable to support and enhance the conventional stand alone anomaly outcome which is traditionally used for interpretation purposes.

  10. The influence of temperature and grain boundary volume on the resistivity of nanocrystalline nickel

    Energy Technology Data Exchange (ETDEWEB)

    Darnbrough, J. E., E-mail: J.E.Darnbrough@bristol.ac.uk; Flewitt, P. E. J. [Interface Analysis Centre, School of Physics, University of Bristol, H. H. Wills Physics Laboratory, Tyndall Avenue, Bristol, BS8 1TL (United Kingdom); Roebuck, B. [National Physical Laboratory, Hampton Rd, Teddington, Middlesex, TW11 0LW (United Kingdom)

    2015-11-14

    The thermal stability and modes of recrystallisation of nanocrystalline nickel has been observed through a conduction-based non-destructive test. Resistivity measurements have been utilised to quantify grain boundary volume fraction and microstructure. This observation makes clear the distinction of the factors that contribute to resistivity and demonstrates that these contributions are related to microstructure, either directly or in-directly. In static systems, the contribution of ordered grains and low-order grain boundary atomic arrangements in small grained material has been measured and correlated with resistivity. Measurements of in-situ resistivity conducted at high temperature gives changes with time which are related to grain growth, during heat treatment. This shows that resistivity can be used as a technique for observing the microstructure and grain growth of small grained material.

  11. The electrical resistance of PuSb under high pressure

    Energy Technology Data Exchange (ETDEWEB)

    Link, P. (European Commission, Joint Research Centre, Institute for Transuranium Elements, Postfach 2340, D76125 Karlsruhe (Germany)); Benedict, U. (European Commission, Joint Research Centre, Institute for Transuranium Elements, Postfach 2340, D76125 Karlsruhe (Germany)); Wittig, J. (Institut fuer Festkoerperforschung, Forschungszentrum Juelich, D52425 Juelich (Germany)); Wuehl, H. (Institut fuer Experimentelle Kernphysik, Universitaet Karlsruhe, D76128 Karlsruhe (Germany)); Rebizant, J. (European Commission, Joint Research Centre, Institute for Transuranium Elements, Postfach 2340, D76125 Karlsruhe (Germany)); Spirlet, J.C. (European Commission, Joint Research Centre, Institute for Transuranium Elements, Postfach 2340, D76125 Karlsruhe (Germany))

    1994-10-01

    A new experimental set-up with a Bridgman-type high pressure cell in a closed containment allows resistance measurements on highly radioactive materials. We present results of high pressure, low temperature studies on PuSb single crystals in the pressure range to 25 GPa and at temperatures between 1.3 K and 300 K. As pressure on PuSb is increased, its Neel temperature and the transition temperature to the ferromagnetic ground state are increased. In the pressure range from 10 to 15 GPa, we observed a strong decrease in the resistance associated with the crystallographic phase transition from the B1 (NaCl) to the B2 (CsCl) structure. The high pressure phase appears to be non-magnetic. ((orig.))

  12. Guanacaste Geothermal Project. Technical prefeasibility report. Annex C. Electric resistivity

    Energy Technology Data Exchange (ETDEWEB)

    1976-12-01

    This report is the third of six annexes to the Summary Report on the First Phase of the Guanacaste Geothermal Project. The studies covered an area of 500 km/sup 2/ on the SW flanks of the Rincon de la Vieja and Miravalles volcanoes of the Guanacaste Volcanic Range in NW Costa Rica, and were aimed at locating zones of high geothermal gradient, and reconstruction of the stratigraphic column. The formations in the area under study can be grouped into six resistivity ranges, varying from less than 5 to more than 200 ohm-meters. Values from 200 to as high as 30,000 ohm-meters generally correspond to fractured and porous lavas, their fracturing and porosity, as well as their drainability, increasing with resistivity. The values above 100 ohm-meters were recorded in zones of recent lava flows, in spurs of the volcanoes Rincon de la Vieja and Santa Maria, and in the slopes of the Miravalles volcano, and correspond to shallow formations (maximum depths of 150 meters) which may constitute recharge zones for the underground aquifiers. The values in the 100 to 200 ohm-meter range were generally recorded directly under layers constituted by drained, porous lavas, or under shallow layers where no recent lavas are present. The third group comprises materials with resistivities in the 25 to 100 ohm-meter range, occurring at two different depth levels: a deep one (more than 1000 meters) and a shallow one (less than 400 meters). Resistivities less than 25 ohm-meters were recorded at depths of 250 meters and more, and may correspond to material typical of the Aguacate formation, which probably constitutes the reservoir rock of the geothermal fluids. In order to locate the zones of most geothermal interest, this range was classified into the three remaining of the six groups, viz 10 to 25, 5 to 10, and less than 5 ohm-meters, the last group appearing to be that of greatest geothermal potential.

  13. QUANTUM FLUCTUATIONS IN MESOSCOPIC RESISTANCE INDUCTANCE-CAPACITANCE ELECTRIC CIRCUITS AT FINITE TEMPERATURE

    Institute of Scientific and Technical Information of China (English)

    LIANG XIAN-TING; FAN HONG-YI

    2001-01-01

    By using the charge and current in a quantization resistance-inductance-capacitance (RLC) electric circuit, we construct a pair of canonical variables. Using this pair of variables and the thermal field dynamics, we obtain the fluctuations of charge and current in the RLC electric circuit at finite temperatures. It is shown that the fluctuations increase with increasing temperature and decrease with prolonging of time.

  14. Electron Acceleration by Cascading Reconnection in the Solar Corona. II. Resistive Electric Field Effects

    Science.gov (United States)

    Zhou, X.; Büchner, J.; Bárta, M.; Gan, W.; Liu, S.

    2016-08-01

    We investigate electron acceleration by electric fields induced by cascading reconnections in current sheets trailing coronal mass ejections via a test particle approach in the framework of the guiding-center approximation. Although the resistive electric field is much weaker than the inductive electric field, the electron acceleration is still dominated by the former. Anomalous resistivity η is switched on only in regions where the current carrier’s drift velocity is large enough. As a consequence, electron acceleration is very sensitive to the spatial distribution of the resistive electric fields, and electrons accelerated in different segments of the current sheet have different characteristics. Due to the geometry of the 2.5-dimensional electromagnetic fields and strong resistive electric field accelerations, accelerated high-energy electrons can be trapped in the corona, precipitating into the chromosphere or escaping into interplanetary space. The trapped and precipitating electrons can reach a few MeV within 1 s and have a very hard energy distribution. Spatial structure of the acceleration sites may also introduce breaks in the electron energy distribution. Most of the interplanetary electrons reach hundreds of keV with a softer distribution. To compare with observations of solar flares and electrons in solar energetic particle events, we derive hard X-ray spectra produced by the trapped and precipitating electrons, fluxes of the precipitating and interplanetary electrons, and electron spatial distributions.

  15. Influence of accompanying substances of hemp fibres on their electric resistance

    Directory of Open Access Journals (Sweden)

    Pejić Biljana

    2006-01-01

    Full Text Available Hemp fibres belong to the group of natural, cellulose bast fibres. These fibres have exceptional properties such as: antimicrobial effect, absence of allergy effect, extraordinary sorption properties, good electro-physical properties (small static electricity in regard to other cellulose fibres as well as high values of breaking strength (the natural fibre with the highest strength. However, hemp fibres have some defects: heterogeneous chemical composition, large quantity of accompanying substances (lignin pectins, waxes and unsatisfactory fineness and eveness. It is possible to a great extent to eliminate or reduce, the defects of hemp fibres by of appropriate modification treatments. In order to determine the appropriate modification treatment of hemp fibres, the dependences between the chemical composition, fineness and electric resistance of hemp fibres were presented in this paper. In the experimental part of the paper, by the application of a procedure for the determination of the chemical composition, the accompanying supstances of hemp fibres were gradually removed. After each phase some fibrous substrates were separated. After that the fineness and electric resistance were determined. This experiment was conducted in order to define the influence of each component of hemp fibres on the fineness and electric resistance. In this paper, hemp fibres were modified by an aqueous solution of sodium hydroxide, under different conditions of modification. The influence of modification conditions on the fineness and electric resistance were studied.

  16. Investigations of temperature dependences of electrical resistivity and specific heat capacity of metals

    Energy Technology Data Exchange (ETDEWEB)

    Eser, Erhan, E-mail: eserphy@gmail.com [Department of Physics, Polatlı Faculty of Arts and Sciences, Gazi University, Polatlı, Ankara (Turkey); Koç, Hüseyin [Department of Electrical and Electronics Engineering, Faculty of Engineering, Muş Alparslan University, Muş (Turkey)

    2016-07-01

    In this study, we calculated the electrical resistivity and heat capacities of some ideal metals (Cu, Pt, and Pd) using a method that it employs the statistical model and Debye functions. The method is used to provide a simple and reliable analytical procedure for wide temperature range. The results obtained for the electrical resistivity and heat capacity have been compared with the results in literature. The results obtained at low temperature are in excellent agreement with experimental and theoretical results. Finally the used approximation and analytical method are a useful approach to calculate thermophysical properties of metals.

  17. Temperature dependent electrical resistivity of gallium and antimony in a liquid form

    Science.gov (United States)

    Prajapati, A. V.; Sonvane, Y. A.; Thakor, P. B.

    2016-05-01

    Present paper deals with the effects of temperature variation on the electrical resistivity (Ω) of liquid Gallium (Ga), and Antimony (Sb). We have used a new parameter free pseudopotential with a Zeeman formula for finding it. To see the effects of screening Farid et al local field correction function is used with the Charged Hard Sphere (CHS) reference system. Analysis and comparison between the plotted graphs, based on present computed data and other experimental data defines and conclude that our newly constructed model potential is an effective one to produce the data for the temperature dependent electrical resistivity of some liquid semiconductors.

  18. 3-D time-lapse electrical resistivity monitoring of injected CO2 in a shallow aquifer

    DEFF Research Database (Denmark)

    Doetsch, Joseph A. J.A.; Auken, Esben; Christiansen, Anders Vest C A.V.C.;

    2013-01-01

    Contamination of potable groundwater by leaking CO2 is a potential risk of carbon sequestration. With the help of a field experiment, we investigate if surface electrical resistivity tomography (ERT) can detect dissolved CO2 in a shallow aquifer. For this purpose, we injected CO2 at a depth of 5...... inversion reveals the geology at the site consisting of aeolian sands near the surface and glacial sands below 5 m depth. Time-lapse inversions clearly image the dissolved CO2 plume with decreased electrical resistivity values. We can follow the CO2 plume as it spreads and moves with the groundwater...

  19. Evaluation of atmospheric corrosion on electroplated zinc and zinc nickel coatings by Electrical Resistance (ER) Monitoring

    DEFF Research Database (Denmark)

    Møller, Per

    2013-01-01

    ER (Electrical Resistance) probes provide a measurement of metal loss, measured at any time when a metal is exposed to the real environment. The precise electrical resistance monitoring system can evaluate the corrosion to the level of nanometers, if the conductivity is compensated for temperature...... for the automotive industry, off-shore construction or component and devices used in harsh industrial environments. The ER monitoring makes it possible to study the corrosion rate on-line in remote locations as a function of temperature, relative humidity and changes in the composition of the atmosphere. Different...

  20. Effects of electrical resistance on the spontaneous combustion tendency of coal and the interaction matrix concept

    Institute of Scientific and Technical Information of China (English)

    2006-01-01

    There have been several developments in determining the spontaneous combustion liability of coal. Most of the methods of concern have purely been based on the internal properties of the coal itself. The relation between the crossing-point method and the electrical resistance of coal was examined here to outline the spontaneous combustion tendency of coal. The electrical resistance property of coal was looked into as a decision-making parameter of the interaction matrix concept for the final decision on the spontaneous combustion tendency.

  1. Developing an artificial neural network model for predicting concrete’s compression strength and electrical resistivity

    Directory of Open Access Journals (Sweden)

    Juan Manuel Lizarazo Marriaga

    2010-04-01

    Full Text Available The present study was conducted for predicting the compressive strength of concrete based on unit weight ultrasonic and pulse velocity (UPV for 41 different concrete mixtures. This research emerged from the need for a rapid test for predicting concrete’s compressive strength. The research was also conducted for predicting concrete’s electrical resistivity based on unit weight ultrasonic, pulse velocity (UPV and compressive strength with the same mixes. The prediction was made using simple regression analysis and artificial neural networks. The results revealed that artificial neural networks can be used for effectively predicting compressive strength and electrical resistivity.

  2. Evaluation of atmospheric corrosion on electroplated zinc and zinc nickel coatings by Electrical Resistance (ER) Monitoring

    DEFF Research Database (Denmark)

    Møller, Per

    2013-01-01

    ER (Electrical Resistance) probes provide a measurement of metal loss, measured at any time when a metal is exposed to the real environment. The precise electrical resistance monitoring system can evaluate the corrosion to the level of nanometers, if the conductivity is compensated for temperature...... and magnetic fields. With this technique very important information about the durability of a new conversion coatings for aluminum, zinc and zinc alloys exposed to unknown atmospheric conditions can be gathered. This is expected to have a major impact on a number of industrial segments, such as test cars...

  3. Multi-Electrode Resistivity Probe for Investigation of Local Temperature Inside Metal Shell Battery Cells via Resistivity: Experiments and Evaluation of Electrical Resistance Tomography

    Directory of Open Access Journals (Sweden)

    Xiaobin Hong

    2015-01-01

    Full Text Available Direct Current (DC electrical resistivity is a material property that is sensitive to temperature changes. In this paper, the relationship between resistivity and local temperature inside steel shell battery cells (two commercial 10 Ah and 4.5 Ah lithium-ion cells is innovatively studied by Electrical Resistance Tomography (ERT. The Schlumberger configuration in ERT is applied to divide the cell body into several blocks distributed in different levels, where the apparent resistivities are measured by multi-electrode surface probes. The investigated temperature ranges from −20 to 80 °C. Experimental results have shown that the resistivities mainly depend on temperature changes in each block of the two cells used and the function of the resistivity and temperature can be fitted to the ERT-measurement results in the logistical-plot. Subsequently, the dependence of resistivity on the state of charge (SOC is investigated, and the SOC range of 70%–100% has a remarkable impact on the resistivity at low temperatures. The proposed approach under a thermal cool down regime is demonstrated to monitor the local transient temperature.

  4. Anomalous behavior of electrical resistivity in NdFe{sub 11}Ti

    Energy Technology Data Exchange (ETDEWEB)

    Tajabor, N.; Alinejad, M.R. [Department of Physics, Faculty of Science, Ferdowsi University of Mashhad (Iran); Amirabadizadeh, A. [Department of Physics, Faculty of Science, Ferdowsi University of Mashhad (Iran); Department of Physics, Faculty of Science, University of Birjand, Birjand (Iran); Pourarian, F. [Carnegie Mellon Research Institute, Carnegie Mellon University, Pittsburgh, Pennsylvania, 15219 (United States)

    2004-05-01

    The electrical resistivity, {rho}, and temperature derivative of resistivity (d/dT) of polycrystalline NdFe{sub 11}Ti are investigated. The resistivity exhibits an anomalous behavior at about 160 K and 220 K. These anomalies attributed to spin reorientation phenomena originate from two magnetic phase transition. A modified theoretical model for electrical resistivity, {rho} and d{rho}/dT, behavior in the spin reorientation temperature (T{sub SR}) region is presented. The results suggest that the average magnetic moment at T{sub SR1} {proportional_to}160 K is aligned along a cone angle and at T{sub SR2} {proportional_to}220 K along c-axis. The temperature dependence of ac-susceptibility, {chi}{sub ac}(T), is presented. The results show the existence of the spin reorientation related to a magnetic phase transition. (copyright 2004 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim) (orig.)

  5. Evaluation of physico-mechanical properties of clayey soils using electrical resistivity imaging technique

    Science.gov (United States)

    Kibria, Golam

    Resistivity imaging (RI) is a promising approach to obtaining continuous profile of soil subsurface. This method offers simple technique to identify moisture variation and heterogeneity of the investigated area. However, at present, only qualitative information of subsurface can be obtained using RI. A study on the quantification of geotechnical properties has become important for rigorous use of this method in the evaluation of geohazard potential and construction quality control of landfill liner system. Several studies have been performed to describe electrical resistivity of soil as a function of pore fluid conductivity and surface conductance. However, characterization tests on pore water and surface charge are not typically performed in a conventional geotechnical investigation. The overall objective of this study is to develop correlations between geotechnical parameters and electrical resistivity of soil, which would provide a mean to estimate geotechnical properties from RI. As a part of the study, multiple regression analyses were conducted to develop practically applicable models correlating resistivity with influential geotechnical parameters. The soil samples considered in this study were classified as highly plastic clay (CH) and low plasticity clay (CL) according to Unified Soil Classification System (USCS). Based on the physical tests, scanning electron microscope (SEM), and energy dispersive X-ray spectroscopy (EDS) analysis, kaolinite was identified as the dominant mineral with some traces of magnesium, calcium, potassium, and iron. Electrical resistivity tests were conducted on compacted clays and undisturbed samples under varied geotechnical conditions. The experimental results indicated that the degree of saturation substantially influenced electrical resistivity. Electrical resistivity decreased as much as 11 times from initial value for the increase of degree of saturation from 23 to 100% in the laboratory tests on compacted clays. In case of

  6. Acidic Barren Slope Profiling using Electrical Resistivity Imaging (ERI) at Ayer Hitam area Johor, Malaysia

    Science.gov (United States)

    Azhar, A. T. S.; Hazreek, Z. A. M.; Aziman, M.; Haimi, D. S.; Hafiz, Z. M.

    2016-04-01

    Recently, non-destructive method such as the electrical resistivity technique has become increasingly popular in engineering, environmental, mining and archeological studies nowadays. This method was popular in subsurface profiling due to its ability to replicate the images of the subsurface indirectly. The soil slope found in Batu Pahat, specifically in Ayer Hitam, is known to be problematic due to its barren condition. This location is believed to contain futile soil due to its difficulty in supporting the growth of vegetations. In the past, acidic barren slope assessment using non-destructive method was rarely being used due to several reasons related to the equipment and knowledge constraints. Hence, this study performed an electrical resistivity imaging using ABEM Terrameter LS in order to investigate the acidic barren slope conditions. Field data acquisition was based on Schlumberger and Wenner arrays while RES2DINV software was used to analyze and generate a 2-D model of the problematic subsurface profile. Based on electrical resistivity results, it was found that the acidic barren slope studied consists of two main zones representing residual soil (electrical resistivity value = 10 - 600 Ωm) and shale (electrical resistivity value = 20 - 2000 Ωm). The results of resistivity value were correlated with the physical mapping and the in situ mackintosh probe test for verification purposes. It was found that the maximum depth of the mackintosh probe test was 1.8 m due to its ground penetration limitation. However, the results of the resistivity section managed to achieve greater depth up to 40 m. Hence, the correlation between electrical resistivity and mackintosh probe results can only be performed at certain depth of the acidic barren slope profile in contrast with the physical mapping which able to define the whole section of the barren soil slope structure. Finally, a good match of electrical resistivity results calibrated with mackintosh and physical

  7. Combined effects of fretting and pollutant particles on the contact resistance of the electrical connectors

    Directory of Open Access Journals (Sweden)

    Zhigang Kong

    2017-06-01

    Full Text Available Usually, when electrical connectors operate in vibration environments, fretting will be produced at the contact interfaces. In addition, serious environmental pollution particles will affect contact resistance of the connectors. The fretting will worsen the reliability of connectors with the pollutant particles. The combined effects of fretting and quartz particles on the contact resistance of the gold plating connectors are studied with a fretting test system. The results show that the frequencies have obvious effect on the contact resistance. The higher the frequency, the higher the contact resistance is. The quartz particles cause serious wear of gold plating, which make the nickel and copper layer exposed quickly to increase the contact resistance. Especially in high humidity environments, water supply certain adhesion function and make quartz particles easy to insert or cover the contact surfaces, and even cause opening resistance.

  8. Estimation of heavy metal-contaminated soils' mechanical characteristics using electrical resistivity.

    Science.gov (United States)

    Chu, Ya; Liu, Songyu; Wang, Fei; Cai, Guojun; Bian, Hanliang

    2017-05-01

    Under the process of urbanization in China, more and more attention has been paid to the reuse of heavy metal-contaminated sites. The shear characteristics of heavy metal-contaminated soils are investigated by electrical detection in this paper. Three metal ions (Zn(2+), Cd(2+), and Pb(2+)) were used, the metal concentrations of which are 50, 166.67, 500, 1666.67, and 5000 mg/kg, respectively. Direct shear tests were used to investigate the influence of heavy metal ions on the shear characters of soil samples. It is found that with the addition of heavy metal ions, the shear strength, cohesion, and friction angle of contaminated soils are higher than the control samples. The higher concentration of heavy metal ions penetrated in soils, the higher these engineering characteristics of contaminated soils observed. In addition, an electrical resistivity detection machine is used to evaluate the shear characteristics of contaminated soils. The electrical resistivity test results show that there is a decreasing tendency of resistivity with the increase of heavy metal ion concentrations in soils. Compared with the electrical resistivity and the shear characteristics of metal-contaminated soils, it is found that, under fixed compactness and saturation, shear strength of metal-contaminated soils decreased with the increase of resistivity. A basic linear relationship between C/log(N + 10) and resistivity can be observed, and there is a basic linear relationship between φ/log(N + 10) and resistivity. Besides, a comparison of the measured and predicted shear characteristics shows a high accuracy, indicating that the resistivity can be used to evaluate the shear characteristics of heavy metal contaminated soils.

  9. Electrical test methods for on-line fuel cell ohmic resistance measurement

    Science.gov (United States)

    Cooper, K. R.; Smith, M.

    The principles and trade-offs of four electrical test methods suitable for on-line measurement of the ohmic resistance (R Ω) of fuel cells is presented: current interrupt, AC resistance, high frequency resistance (HFR), and electrochemical impedance spectroscopy (EIS). The internal resistance of a proton exchange membrane (PEM) fuel cell determined with the current interrupt, HFR and EIS techniques is compared. The influence of the AC amplitude and frequency of the HFR measurement on the observed ohmic resistance is examined, as is the ohmic resistance extracted from the EIS data by modeling the spectra with a transmission line model for porous electrodes. The ohmic resistance of a H 2/O 2 PEM fuel cell determined via the three methods was within 10-30% of each other. The current interrupt technique consistently produced measured cell resistances that exceeded those of the other two techniques. For the HFR technique, the frequency at which the measurement was conducted influenced the measured resistance (i.e., higher frequency providing smaller R Ω), whereas the AC amplitude did not effect the observed value. The difference in measured ohmic resistance between these techniques exceeds that reasonably accounted for by measurement error. The source of the discrepancy between current interrupt and impedance-based methods is attributed to the difference in the response of a non-uniformly polarized electrode, such as a porous electrode with non-negligible ohmic resistance, to a large perturbation (current interrupt event) as compared to a small perturbation (impedance measurement).

  10. Electrical power free, low dead volume, pressure-driven pumping for microfluidic applications.

    Science.gov (United States)

    Moscovici, Mario; Chien, Wei-Yin; Abdelgawad, Mohamed; Sun, Yu

    2010-10-13

    This paper presents a simple-to-construct, low dead volume pump capable of generating a wide range of positive and negative pressures for microfluidic applications. The pump generates pressure or vacuum by changing the volume of air confined inside a syringe and is able to generate pressures between -95 and +300 kPa with a resolution as high as 1 Pa. Different from syringe pumps and electrokinetic pumping, which are capable of controlling flow rates only, our pump can be used to generate constant flow rates or constant pressures, which are required for certain applications such as the aspiration of biological cells for biophysical characterization. Compared to syringe pumps, the new pump has almost zero dead volume and does not exhibit pulsatile flows. Additionally, the system does not require electrical power and is cost effective (∼$100). To demonstrate the capabilities of the pump, we used it to aspirate osteoblasts (MC3T3-E1 cells) and to determine Young's modulus of the cells, to generate a concentration gradient, and to produce variable-sized droplets in microchannels using hydrodynamic focusing.

  11. Transient contact resistance in electrical connections with flat pins

    Directory of Open Access Journals (Sweden)

    Merlyan S. V.

    2013-06-01

    Full Text Available On the basis of experimental research, the authors have obtained dependences allowing to find promptly and with a small amount of calculations the optimum pressure value for elastic elements of flat contacts with different coatings (tin-bismuth, nickel, palladium, silver, gold, using the preset value of contact resistance Rпер. Moreover, the obtained results of estimation of quantity and stability of Rпер allow to choose the optimal coating according to the operating conditions of the contacts.

  12. Application of Electrical Resistivity Tomography for Detecting Root Biomass in Coffee Trees

    Directory of Open Access Journals (Sweden)

    Carlos Mauricio Paglis

    2013-01-01

    Full Text Available Roots play an important role in plants and are responsible for several functions; among them are anchorage and nutrient and water absorption. Several methodologies are being tested and used to study plant root systems in order to avoid destructive root sampling. Electrical resistivity tomography is among these methodologies. The aim of this preliminary study was to use electrical resistivity for detecting root biomass in coffee trees. Measurements were performed in a soil transect with an ABM AL 48-b resistivimeter with a pole-dipole configuration. The tomograms indicated variability in soil resistivity values ranging from 120 to 1400 Ω·m−1. At the first 0.30 cm soil layer, these values were between 267 and 952 Ω·m−1. Oriented by this result, root samples were taken at 0.10, 0.20, and 0.30 m depths within 0.50 m intervals along the soil transect to compare soil resistivity with root mass density (RMD. RMD data, up to this depth, varied from 0.000019 to 0.009469 Mg·m−3, showing high spatial variability and significant relationship to the observed values of soil resistivity. These preliminary results showed that the electrical resistivity tomography can contribute to root biomass studies in coffee plants; however, more experiments are necessary to confirm the found results in Brazil coffee plantations.

  13. CONSUMPTION VOLUMES TECHNOLOGY OF ELECTRICITY AND HEAT BY DEPARTMENTS OF THE UNIVERSITY

    Directory of Open Access Journals (Sweden)

    O. M. Pshinko

    2015-01-01

    Full Text Available Purpose. Efficient use of natural energy resources is one of the priorities of the state policy in the sphere of universities and institutions of the Ministry of Education and Science of Ukraine. Besides search and development the new efficient and clean energy systems it is necessary to implement optimal management of the development and operation of existing facilities, reducing their energy costs. Purpose of this work is to develop consumption volume technology of electricity and heat by scientific departments of Dnipropetrovsk National University of Railway Transport named after Academician V. Lazaryan (DNURT for further finding the ways to reduce energy consumption. The problem is due to the specifics of University’s energy scheme. There is a difficulty for the installation of energy meters and data acquisition about their use in individual branches and structural units. At the same time it is impossible to assess qualitatively the energy position of scientific departments. Methodology. The method to determine the electricity and heat consumption for space heating of scientific departments at the university is based on «The intersectoral rules of electricity and heat energy for institutions and public sector organizations in Ukraine» and «Codes and regulations on rationing of fuel and heat energy for heating the residential buildings as well as for economic needs in Ukraine». Findings. Developed determining expenditure technology of electricity and heat for heating by scientific departments at the DNURT named after Academician V. Lazaryan allows obtaining data on energy consumption in individual units without direct measure and analyzing the effectiveness of energy saving technologies. Originality. It is represented by energy costs in the form of two components and these components are defined on the basis of the energy audit. This enables the energy inputs to implement energy efficiency measures in the research departments of the

  14. Spatial variability of soil water conductivities obtained with classical laboratory methods and their relation to electrical resistivity measurements

    Science.gov (United States)

    Dathe, Annette; Nemes, Attila; Bloem, Esther; Patterson, Matthew; Giménez, Daniel; Szõcs, Júlia; Koestel, Johannes; Jarvis, Nicholas

    2017-04-01

    Soil water conductivity plays a critical role when estimating water transport using the Richard's equation. Modelers often take one value of the saturated hydraulic conductivity (Ksat) per soil layer and that value is decreased for unsaturated conditions following the equations of Mualem and van Genuchten. This approach can lead to inconsistencies between model and natural soil, because in the field Ksat can vary by several orders of magnitude on short (centimeter) distances and Ksat often expresses water movement through macropores which cannot be downscaled without caution towards matrix flux. To improve existing knowledge we established a field experiment on an agriculturally used silty clay loam (Stagnosol) in SE Norway. More than 100 undisturbed soil samples were taken to determine soil water retention, saturated and unsaturated hydraulic conductivities and bulk density in the laboratory. A subset of these samples was scanned at the computer tomography facility at the Swedish University of Agricultural Sciences in Uppsala with special emphasis on characterizing macroporosity. Centimeter to decimeter scale heterogeneities were investigated in the field by using electrical resistivity tomography (ERT) in a quasi-3D and a real 3D approach. The latter covered the soil volume of 2x1x1 m where the soil samples were taken. We will present comparisons between hydraulic conductivities obtained in the laboratory using different methods, and between laboratory hydraulic conductivity results and electrical resistivities obtained in the field.

  15. Electrical Resistivity Tomography in the characterisation of wetting patterns of historical masonry

    Science.gov (United States)

    López-González, Laura; Gomez-Heras, Miguel; Ortiz de Cosca, Raquel Otero; García-Morales, Soledad

    2016-04-01

    Electrical Resistivity Tomography (ERT) is a geophysical technique widely used to identify subsurface structures based on electrical resistivity measurements made at the surface. In recent years this technique has been used for surveying historic buildings and characterise the subsurface of walls by using non-invasive EKG electrodes. This methods is used to locate wet areas based on the lower electrical resistivity wet materials have in relation to dry ones. A good knowledge of the wetting patterns of historic buildings during, for example, rainfalls is crucial to understand the decay processes that take place in the building and plan interventions. This paper presents results of transects of Electric Resistivity Tomography of walls of the Monastery of Santa Maria de Mave (Palencia, Spain), a 9th century Romanesque building, during rainfall. ERT transects were performed with a GeoTom device (Geolog2000) in areas with and without buttresses to understand how this architectural detail affected the wetting dynamics of the building. The ERT results were integrated with other resistivity-based techniques and Thermohygrometric survey in a GIS and showed how lower resistivity surface measurements ERT correspond with areas of higher humidity. Resistivity-based techniques measured and evaporation focal points take in the interior of the building mark the outer ground level. The highest moisture content measurements do not always correspond to the visibly most damaged areas of the wall. The consecutive ERT transects show the wall getting wetter as rainfall progresses. The comparison of the measurements obtained of a wall affected by water obtained with GIS mapping, allowed to quickly studying the development of moisture in the wall over time, which is essential for a correct diagnosis of the building. Research funded by Madrid's Regional Government project Geomateriales 2 S2013/MIT-2914

  16. Constraining Water Quality Models With Electrical Resistivity Tomography (ERT)

    Science.gov (United States)

    Bentley, L. R.; Gharibi, M.; Mrklas, O.; Lunn, S. D.

    2001-12-01

    Water quality models are difficult to constrain with piezometer data alone because the data are spatially sparse. Since the electrical conductivity (EC) of water is often correlated with water quality, geophysical measurements of electrical conductivity may provide densely sampled secondary data for constraining water quality models. We present a quantitative interpretation protocol for interpreting EC derived from surface ERT results. A standard temperature is selected that is in the range of the in situ field temperatures, and laboratory measurements establish a functional relationship between water EC and temperature. Total meq/l of charge are often strongly correlated with water EC at the standard temperature. Laboratory data is used to develop a correlation model between indicator parameters or water chemistry evolution and total meq/l of charge. Since the solid phase may contain a conductive clay fraction, a site specific calibrated Waxman-Smits rock physics model is used to estimate groundwater EC from bulk EC derived from ERT inversions. The groundwater EC at in situ temperature is converted to EC at the standard temperature, and the total meq/l is estimated using the laboratory-established correlation. The estimated meq/l can be used as soft information to map distribution of water quality or to estimate changes to water chemistry with time. We apply the analysis to a decommissioned sour gas plant undergoing remediation. Background bulk EC is high (50 to 100 mS/m) due to the clay content of tills. The highest values of groundwater EC are mainly due to acetic acid, which is a degradation product of amines and glycols. Acetic acid degrades readily under aerobic conditions, lowering the EC of pore waters. The calibrated Waxman-Smits model predicts that a reduction of groundwater EC from 1600 mS/m to 800mS/m will result in a reduction of bulk EC from 150 mS/m to 110 mS/m. Groundwater EC values both increase and decrease with time due to site heterogeneity, and

  17. Direct quantification of transendothelial electrical resistance in organs-on-chips

    NARCIS (Netherlands)

    Helm, van der Marinke W.; Odijk, M.; Frimat, Jean-Philippe; Meer, van der Andries D.; Eijkel, Jan C.T.; Berg, van den Albert; Segerink, Loes I.

    2016-01-01

    Measuring transendothelial or transepithelial electrical resistance (TEER) is a widely used method to monitor cellular barrier tightness in organs-on-chips. Unfortunately, integrated electrodes close to the cellular barrier hamper visual inspection of the cells or require specialized cleanroom proce

  18. 30 CFR 7.407 - Test for flame resistance of electric cables and cable splices.

    Science.gov (United States)

    2010-07-01

    ... 3 feet in length, by removing 5 inches of jacket material and 21/2 inches of conductor insulation... material and 21/2 inches of conductor insulation. The type, amperage, voltage rating, and construction of... 30 Mineral Resources 1 2010-07-01 2010-07-01 false Test for flame resistance of electric...

  19. Effect of pressure on electrical resistance of WSe2 single crystal

    Indian Academy of Sciences (India)

    Rajiv Vaidya; Neha Bhatt; S G Patel; A R Jani; Alka B Garg; V Vijayakumar; B K Godwal

    2003-07-01

    The results of electrical resistance measurements under pressure on single crystals of WSe2 are reported. Measurements up to 8.5 GPa are carried out using Bridgman anvil set up and beyond it using diamond anvil cell (DAC) up to a pressure of 27 GPa. There is no clear indication of any phase transition till the highest pressure is reached in these measurements.

  20. Procedures and criteria for increasing the earthquake resistance level of electrical substations and special installations

    Energy Technology Data Exchange (ETDEWEB)

    Couch, R.W.; Deacon, R.J.

    1973-09-30

    This report defines a procedure and provides basic information needed to determine the modifications required to make electrical substations and special installations of the Bonneville Power Administration (BPA) more resistant to strong earthquake ground motion. It also provides a procedure for developing an effective plan for establishing the sequence, or priority, of providing the required modifications.

  1. Electrical resistance of thin magnesium layers deposited at 4. 2K

    Energy Technology Data Exchange (ETDEWEB)

    Belzons, M.; Blanc, R.; Payan, R.

    1976-10-11

    Electrical resistance of thin magnesium layers deposited on a cold substrate under ultra-vacuum conditions has been studied as a function of T. Results are compared with those on bulk and with data obtained by Reale (1975) on films prepared in similar conditions. Behavior reported by Reale was not confirmed.

  2. Ion Permeability of Artificial Membranes Evaluated by Diffusion Potential and Electrical Resistance Measurements

    Science.gov (United States)

    Shlyonsky, Vadim

    2013-01-01

    In the present article, a novel model of artificial membranes that provides efficient assistance in teaching the origins of diffusion potentials is proposed. These membranes are made of polycarbonate filters fixed to 12-mm plastic rings and then saturated with a mixture of creosol and "n"-decane. The electrical resistance and potential…

  3. An experimentally validated contactless acoustic energy transfer model with resistive-reactive electrical loading

    Science.gov (United States)

    Shahab, S.; Gray, M.; Erturk, A.

    2015-04-01

    This paper investigates analytical modeling and experimental validation of Ultrasonic Acoustic Energy Transfer (UAET) for low-power electricity transfer to exploit in wireless applications ranging from medical implants to underwater sensor systems. A piezoelectric receiver bar is excited by incident acoustic waves originating from a source of known strength located at a specific distance from the receiver. The receiver is a free-free piezoelectric cylinder operating in the 33- mode of piezoelectricity with a fundamental resonance frequency above the audible frequency range. In order to extract the electrical power output, the piezoelectric receiver bar is shunted to a generalized resistive-reactive circuit. The goal is to quantify the electrical power delivered to the load (connected to the receiver) in terms of the source strength. Experimental validations are presented along with parameter optimization studies. Sensitivity of the electrical power output to the excitation frequency in the neighborhood of the receiver's underwater resonance frequency, source-to-receiver distance, and source-strength level are reported. Resistive and resistive-reactive electrical loading cases are discussed for performance enhancement and frequency-wise robustness. Simulations and experiments reveal that the presented multiphysics analytical model for UAET can be used to predict the coupled system dynamics with very good accuracy.

  4. Low-load high volume resistance exercise stimulates muscle protein synthesis more than high-load low volume resistance exercise in young men.

    Directory of Open Access Journals (Sweden)

    Nicholas A Burd

    Full Text Available BACKGROUND: We aimed to determine the effect of resistance exercise intensity (%1 repetition maximum-1RM and volume on muscle protein synthesis, anabolic signaling, and myogenic gene expression. METHODOLOGY/PRINCIPAL FINDINGS: Fifteen men (21+/-1 years; BMI=24.1+/-0.8 kg/m2 performed 4 sets of unilateral leg extension exercise at different exercise loads and/or volumes: 90% of repetition maximum (1RM until volitional failure (90FAIL, 30% 1RM work-matched to 90%FAIL (30WM, or 30% 1RM performed until volitional failure (30FAIL. Infusion of [ring-13C6] phenylalanine with biopsies was used to measure rates of mixed (MIX, myofibrillar (MYO, and sarcoplasmic (SARC protein synthesis at rest, and 4 h and 24 h after exercise. Exercise at 30WM induced a significant increase above rest in MIX (121% and MYO (87% protein synthesis at 4 h post-exercise and but at 24 h in the MIX only. The increase in the rate of protein synthesis in MIX and MYO at 4 h post-exercise with 90FAIL and 30FAIL was greater than 30WM, with no difference between these conditions; however, MYO remained elevated (199% above rest at 24 h only in 30FAIL. There was a significant increase in AktSer473 at 24h in all conditions (P=0.023 and mTORSer2448 phosphorylation at 4 h post-exercise (P=0.025. Phosporylation of Erk1/2Tyr202/204, p70S6KThr389, and 4E-BP1Thr37/46 increased significantly (P<0.05 only in the 30FAIL condition at 4 h post-exercise, whereas, 4E-BP1Thr37/46 phosphorylation was greater 24 h after exercise than at rest in both 90FAIL (237% and 30FAIL (312% conditions. Pax7 mRNA expression increased at 24 h post-exercise (P=0.02 regardless of condition. The mRNA expression of MyoD and myogenin were consistently elevated in the 30FAIL condition. CONCLUSIONS/SIGNIFICANCE: These results suggest that low-load high volume resistance exercise is more effective in inducing acute muscle anabolism than high-load low volume or work matched resistance exercise modes.

  5. Factors affecting gas migration and contaminant redistribution in heterogeneous porous media subject to electrical resistance heating.

    Science.gov (United States)

    Munholland, Jonah L; Mumford, Kevin G; Kueper, Bernard H

    2016-01-01

    A series of intermediate-scale laboratory experiments were completed in a two-dimensional flow cell to investigate gas production and migration during the application of electrical resistance heating (ERH) for the removal of dense non-aqueous phase liquids (DNAPLs). Experiments consisted of heating water in homogeneous silica sand and heating 270 mL of trichloroethene (TCE) and chloroform (CF) DNAPL pools in heterogeneous silica sands, both under flowing groundwater conditions. Spatial and temporal distributions of temperature were measured using thermocouples and observations of gas production and migration were collected using front-face image capture throughout the experiments. Post-treatment soil samples were collected and analyzed to assess DNAPL removal. Results of experiments performed in homogeneous sand subject to different groundwater flow rates showed that high groundwater velocities can limit subsurface heating rates. In the DNAPL pool experiments, temperatures increased to achieve DNAPL-water co-boiling, creating estimated gas volumes of 131 and 114 L that originated from the TCE and CF pools, respectively. Produced gas migrated vertically, entered a coarse sand lens and subsequently migrated laterally beneath an overlying capillary barrier to outside the heated treatment zone where 31-56% of the original DNAPL condensed back into a DNAPL phase. These findings demonstrate that layered heterogeneity can potentially facilitate the transport of contaminants outside the treatment zone by mobilization and condensation of gas phases during ERH applications. This underscores the need for vapor phase recovery and/or control mechanisms below the water table during application of ERH in heterogeneous porous media during the co-boiling stage, which occurs prior to reaching the boiling point of water. Copyright © 2015 Elsevier B.V. All rights reserved.

  6. Crustal magma pathway beneath Aso caldera inferred from three-dimensional electrical resistivity structure

    Science.gov (United States)

    Hata, Maki; Takakura, Shinichi; Matsushima, Nobuo; Hashimoto, Takeshi; Utsugi, Mitsuru

    2016-10-01

    At Naka-dake cone, Aso caldera, Japan, volcanic activity is raised cyclically, an example of which was a phreatomagmatic eruption in September 2015. Using a three-dimensional model of electrical resistivity, we identify a magma pathway from a series of northward dipping conductive anomalies in the upper crust beneath the caldera. Our resistivity model was created from magnetotelluric measurements conducted in November-December 2015; thus, it provides the latest information about magma reservoir geometry beneath the caldera. The center of the conductive anomalies shifts from the north of Naka-dake at depths >10 km toward Naka-dake, along with a decrease in anomaly depths. The melt fraction is estimated at 13-15% at 2 km depth. Moreover, these anomalies are spatially correlated with the locations of earthquake clusters, which are distributed within resistive blocks on the conductive anomalies in the northwest of Naka-dake but distributed at the resistive sides of resistivity boundaries in the northeast.

  7. Monitoring six-phase ohmic heating of contaminated soils using electrical resistance tomography

    Energy Technology Data Exchange (ETDEWEB)

    Ramirez, A.L.; Daily, W.D.

    1994-09-01

    Electrical resistance tomography (ERT) was used to monitor six-phase ohmic heating used for the insitu remediation of volatile organic compounds from subsurface water and soil at the Savannah River Site, near Aiken, South Carolina. The changes in electrical conductivity caused by six-phase ohmic-heating in a clay layer located in the vadose zone were monitored during a period of approximately 2 months, before, during and after heating. From an array of electrodes located in 4 boreholes, we collected electrical resistivity data between five pairs of adjacent holes pairs. This data was used to calculate tomographs which showed the electrical conductivity changes along five vertical planes. The difference tomographs show the combined effects of moisture redistribution and heating caused by six-phase heating and vapor extraction. The tomographs show that most of the clay layer increased in electrical conductivity during the first 3 weeks of the 4 week long heating phase. At this time, the electrical conductivities near the center of the heating array were twice as large as the pre-heat conductivities. Then the electrical conductivity started to decrease for portions of the clay layer closest to the vapor extraction well. We propose that the conductivity decreases are due to the removal of moisture by the heating and vacuum extraction. Parts of the clay layer near the extraction well reached electrical conductivities as low as 40% of the pre-heating values. We propose that these regions of lower than ambient electrical conductivities are indicators of regions where the vapor removal by vacuum extraction was most effective. At the end of the heating phase, our estimates suggest that the clay saturation may have dropped to as low as 10% based on the observed conductivity changes.

  8. Geophysical investigation of earth dam using the electrical tomography resistivity technique

    Directory of Open Access Journals (Sweden)

    Pedro Lemos Camarero

    Full Text Available Abstract Dams are structures that dam rivers and streams for a variety of purposes. These structures often need to be sturdy to withstand the force of the impoundment and the high values of accumulated water load. The constant maintenance of these structures is essential, since a possible accident can lead to damage of catastrophic proportions. This research presents an alternative cheap and quick application for investigating water seepage in earth dams, through the application of the DC resistivity geophysical method from the electrical resistivity tomography (ERT technique in Wenner array. Three ERT lines were placed parallel to the longitudinal axis of a dam formed by clay soil from the decomposition of diabase. The data are presented in 2D and pseudo-3D geophysical images with electrical resistivity values modeled. Based on the physical principle of electrolytic conduction, that is, decrease in electrical resistance in materials or siliceous minerals in moisture conditions as compared to the material in the dry state, the results revealed low-resistivity zones restricted to some points, associated with water infiltration in the transverse direction of the dam. The absence of evidence as water upwelling on the front of the dam together with geophysical evidence indicate saturation restricted to some points and low probability at the present time, for installation of piping processes.

  9. Evaluation of metal-nanowire electrical contacts by measuring contact end resistance.

    Science.gov (United States)

    Park, Hongsik; Beresford, Roderic; Ha, Ryong; Choi, Heon-Jin; Shin, Hyunjung; Xu, Jimmy

    2012-06-22

    It is known, but often unappreciated, that the performance of nanowire (NW)-based electrical devices can be significantly affected by electrical contacts between electrodes and NWs, sometimes to the extent that it is really the contacts that determine the performance. To correctly understand and design NW device operation, it is thus important to carefully measure the contact resistance and evaluate the contact parameters, specific contact resistance and transfer length. A four-terminal pattern or a transmission line model (TLM) pattern has been widely used to measure contact resistance of NW devices and the TLM has been typically used to extract contact parameters of NW devices. However, the conventional method assumes that the electrical properties of semiconducting NW regions covered by a metal are not changed after electrode formation. In this study, we report that the conventional methods for contact evaluation can give rise to considerable errors because of an altered property of the NW under the electrodes. We demonstrate that more correct contact resistance can be measured from the TLM pattern rather than the four-terminal pattern and correct contact parameters including the effects of changed NW properties under electrodes can be evaluated by using the contact end resistance measurement method.

  10. Electrical resistivity and ultrasonic measurements during sequential fracture test of cementitious composite

    Directory of Open Access Journals (Sweden)

    V. Veselý

    2014-10-01

    Full Text Available Cracks in cover of reinforced and pre-stressed concrete structures significantly influence the ingress of deleterious species causing decrease in durability of these structures. The paper is focused on the effect of fracture process on two selected physical parameters of concrete – the electrical resistivity and the ultrasonic pulse passing time – which might be employed as the quality indicator of concrete cover within (nondestructive procedure(s of assessment of the structural durability. The concrete electrical resistivity and ultrasonic passing time were investigated here with respect to two variants of treatment of the test specimens’ surface (the pre-dried surface and the wet surface. Test configuration of three-point bending of notched beam was utilized to control the crack propagation; the fracture process passed through several loading–unloading sequences between which the electrical resistivity and ultrasonic passing time readings over the fractured region were performed. Equivalent elastic crack model was used for estimation of the fracture advance (described via the effective crack length at the loading stages corresponding to the resistivity and ultrasonic measurements. Relationships between changes of both the concrete resistivity and ultrasonic pulse passing time and the effective crack length is determined and discussed.

  11. Hydrogeophysical Characterization of shallow karst using electrical resistivity tomography (ERT) in a limestone mining area

    Science.gov (United States)

    Sun, H.; Qi, Z.; Li, X., Sr.; Ma, X.; Xue, Y.; Zhang, Q.; Zhang, X.

    2016-12-01

    Karst is a kind of geological phenomenon under the chemical erosion process from water to soluble rock, such as limestone, gypsum, salt rock etc. Karst is widely distributed around the world and also in southwest of China. The Guangxi area is famous as the highly degree of karstification due to long time groundwater erosion and the development of fracture network. The hydrogeological units become complex involving subsurface karst pipes, caves, eroded groove, etc. Moreover, the complex system is hard to evaluate. The karst collapse may cause many kind of disaster which will influence the human activities. Classical hydrogeological methods, such as pumping tests and tracer tests, to estimate the hydraulic conductivity distribution in an aquifer are hard to finish in some condition with large area and high resolution required. Because a large number of wells are needed, which is uncommon because of the high drilling costs. However, geophysical method is cost-effective in mapping underground structures. And geophysical imaging is highly linked with the subsurface hydrological parameters. Electrical resistivity tomography (ERT) is a widely used geophysical method in environmental and engineering applications. It detect and identify targets with different resistivity to the background by measuring the potential difference between different electric nodes. When the target has lower resistivity than the background, such as water resource, karst, evaluation of marine transgression etc., the acquired data show higher voltage corresponding to low resistivity. While when the target has higher resistivity than the background, such as empty holes, sliding surface for dry landslide and archaeological geophysics etc., the acquired data show opposite phenomenon. One can obtain the real resistivity profile of the subsurface by inverting the acquired data. We study the characterization of shallow karst using electrical resistivity tomography (ERT) which is the most cost effective

  12. Correlation between Electrical Resistivity, Particle Dissolution, Precipitation of Dispersoids, and Recrystallization Behavior of AA7020 Aluminum Alloy

    NARCIS (Netherlands)

    Eivani, A.R.; Ahmed, H.; Zhou, J.; Duszczyk, J.

    2009-01-01

    This research concerns the effect of homogenization treatment on the electrical resistivity of AA7020 aluminum alloy variants with different Zr and Cr contents. Small changes in the Zr and Cr contents of the as-cast alloy increase the electrical resistivity significantly. After employing various

  13. Evaluation of sugar yeast consumption by measuring electrical medium resistance

    Directory of Open Access Journals (Sweden)

    Martin Lucas Zamora

    2013-12-01

    Full Text Available The real-time monitoring of alcoholic fermentation (sugar consumption is very important in industrial processes. Several techniques (i.e., using a biosensor have been proposed to realize this goal. In this work, we propose a new method to follow sugar yeast consumption. This novel method is based on the changes in the medium resistance (Rm that are induced by the CO2 bubbles produced during a fermentative process. We applied a 50-mV and 700-Hz signal to 75 ml of a yeast suspension in a tripolar cell. A gold electrode was used as the working electrode, whereas an Ag/AgCl electrode and a stainless-steel electrode served as the reference and counter electrodes, respectively. We then added glucose to the yeast suspension and obtained a 700% increase in the Rm after 8 minutes. The addition of sucrose instead of glucose as the carbon source resulted in a 1200% increase in the Rm. To confirm that these changes are the result of CO2 bubbles in the fermentation medium, we designed a tetrapolar cell in which CO2 gas was insufflated at the bottom of the cell and concluded that the changes were due to CO2 bubbles produced during the fermentation. Consequently, this new method is a low-cost and rapid technology to follow the sugar consumption in yeast.

  14. Monitoring CO2 migration in a shallow sand aquifer using 3D crosshole electrical resistivity tomography

    DEFF Research Database (Denmark)

    Yang, Xianjin; Lassen, Rune Nørbæk; Jensen, Karsten Høgh;

    2015-01-01

    Three-dimensional (3D) crosshole electrical resistivity tomography (ERT) was used to monitor a pilot CO2 injection experiment at Vrøgum, western Denmark. The purpose was to evaluate the effectiveness of the ERT method for detection of small electrical conductivity (EC) changes during the first 2....... The combined HBB and VBB data sets were inverted using a difference inversion algorithm for cancellation of coherent noises and enhanced resolution of small changes. ERT detected the small bulk EC changes (resistive gaseous CO2. The primary factors that control...... bulk EC changes may be caused by limited and variable ERT resolution, low ERT sensitivity to resistive anomalies and uncalibrated CO2 gas saturation. ERT data show a broader CO2 plume while water sample EC had higher fine-scale variability. Our ERT electrode configuration can be optimized for more...

  15. Electrical Resistivity of Na-K Binary Liquid Alloy Using Ab-Initio Pseudopotentials

    Institute of Scientific and Technical Information of China (English)

    Anil Thakur; P. K. Ahluwalia

    2005-01-01

    @@ The study of electrical resistivity of simple binary liquid alloy Na-K is presented as a function of concentration.Hard sphere diameters of sodium (Na) and potassium (K) are obtained through the inter ionic pair potentials evaluated using Troullier and Martins ab-initio pseudopotentials, which have been used to calculate partial structure factors S(q). The Ziman formula for calculating resistivity of binary liquid alloys has been used. Form factors are calculated using ab-initio pseudopotentials. The results suggest that the first principle approach for calculating pseudopotentials with in the frame work of Ziman formalism is quite successful in explaining the electrical resistivity data of compound forming binary liquid alloys.

  16. Electrical resistivity of NaPb compound-forming liquid alloy using ab initio pseudopotentials

    Indian Academy of Sciences (India)

    Anil Thakur; N S Negi; P K Ahluwalla

    2005-08-01

    The study of electrical resistivity of compound-forming liquid alloy, NaPb, is presented as a function of concentration. Hard sphere diameters of Na and Pb are obtained through the interionic pair potentials evaluated using Troullier and Martins ab initio pseudopotential, which have been used to calculate the partial structure factors (). Considering the liquid alloy to be a ternary mixture, Ziman formula, modified for complex formation has been used for calculating resistivity of binary liquid alloys. Form factors are calculated using ab initio pseudopotentials. The results suggest that Ziman formalism, when used with ab initio pseudopotentials, are quite successful in explaining the electrical resistivity data of compound-forming binary liquid alloys.

  17. Respiratory-gated electrical impedance tomography: a potential technique for quantifying stroke volume

    Science.gov (United States)

    Arshad, Saaid H.; Murphy, Ethan K.; Halter, Ryan J.

    2016-03-01

    Telemonitoring is becoming increasingly important as the proportion of the population living with cardiovascular disease (CVD) increases. Currently used health parameters in the suite of telemonitoring tools lack the sensitivity and specificity to accurately predict heart failure events, forcing physicians to play a reactive versus proactive role in patient care. A novel cardiac output (CO) monitoring device is proposed that leverages a custom smart phone application and a wearable electrical impedance tomography (EIT) system. The purpose of this work is to explore the potential of using respiratory-gated EIT to quantify stroke volume (SV) and assess its feasibility using real data. Simulations were carried out using the 4D XCAT model to create anatomically realistic meshes and electrical conductivity profiles representing the human thorax and the intrathoracic tissue. A single 5-second period respiration cycle with chest/lung expansion was modeled with end-diastole (ED) and end-systole (ES) heart volumes to evaluate how effective EIT-based conductivity changes represent clinically significant differences in SV. After establishing a correlation between conductivity changes and SV, the applicability of the respiratory-gated EIT was refined using data from the PhysioNet database to estimate the number of useful end-diastole (ED) and end-systole (ES) heart events attained over a 3.3 minute period. The area associated with conductivity changes was found to correlate to SV with a correlation coefficient of 0.92. A window of 12.5% around peak exhalation was found to be the optimal phase of the respiratory cycle from which to record EIT data. Within this window, ~47 useable ED and ES were found with a standard deviation of 28 using 3.3 minutes of data for 20 patients.

  18. Savannah River Plant, Project 8980: Engineering and design history of power and electrical facilities. Volume 6

    Energy Technology Data Exchange (ETDEWEB)

    1957-01-01

    This section of the Engineering-and Design History presents a comprehensive account of the planning and extensive evaluation of the problems involved in reaching basic decisions for the design and installation of power facilities at the Savannah River Plant. The problems were complicated by the urgency of Pro. viding early start-up of facilities at a time when critical material shortages were acute, combined with basic requirements for reliable operation and unusual degrees of flexibility to meet a variety of production demands. Part I describes in detail the steam and water facilities, alternative schemes, and other considerations which were evaluated as a prelude to the final design of equipment and facilities. Included are discussions relating to steam boiler installations, electric power generation, diesel engine plants, mater supply for cooling, process and domestic use, and the numerous water treatment procedures employed for specific application. A comprehensive description of the development and design of electric power facilities is presented in Part II of this volume.

  19. Rough surface electrical contact resistance considering scale dependent properties and quantum effects

    Energy Technology Data Exchange (ETDEWEB)

    Jackson, Robert L., E-mail: jackson@auburn.edu [Department of Mechanical Engineering, Auburn University, Auburn, Alabama 36849 (United States); Crandall, Erika R.; Bozack, Michael J. [Department of Physics, Auburn University, Auburn, Alabama 36849 (United States)

    2015-05-21

    The objective of this work is to evaluate the effect of scale dependent mechanical and electrical properties on electrical contact resistance (ECR) between rough surfaces. This work attempts to build on existing ECR models that neglect potentially important quantum- and size-dependent contact and electrical conduction mechanisms present due to the asperity sizes on typical surfaces. The electrical conductance at small scales can quantize or show a stepping trend as the contact area is varied in the range of the free electron Fermi wavelength squared. This work then evaluates if these effects remain important for the interface between rough surfaces, which may include many small scale contacts of varying sizes. The results suggest that these effects may be significant in some cases, while insignificant for others. It depends on the load and the multiscale structure of the surface roughness.

  20. Identification of electrical resistance of fresh state concrete for nondestructive setting process monitoring

    Energy Technology Data Exchange (ETDEWEB)

    Shin, Sung Woo [Dept. of Safety Engineering, Pukyong National University, Busan (Korea, Republic of)

    2015-12-15

    Concrete undergoes significant phase changes from liquid to solid states as hydration progresses. These phase changes are known as the setting process. A liquid state concrete is electrically conductive because of the presence of water and ions. However, since the conductive elements in the liquid state of concrete are consumed to produce non-conductive hydration products, the electrical conductivity of hydrating concrete decreases during the setting process. Therefore, the electrical properties of hydrating concrete can be used to monitor the setting process of concrete. In this study, a parameter identification method to estimate electrical parameters such as ohmic resistance of concrete is proposed. The effectiveness of the proposed method for monitoring the setting process of concrete is experimentally validated.

  1. Bacterial spore heat resistance correlated with water content, wet density, and protoplast/sporoplast volume ratio.

    Science.gov (United States)

    Beaman, T C; Greenamyre, J T; Corner, T R; Pankratz, H S; Gerhardt, P

    1982-05-01

    Five types of dormant Bacillus spores, between and within species, were selected representing a 600-fold range in moist-heat resistance determined as a D100 value. The wet and dry density and the solids and water content of the entire spore and isolated integument of each type were determined directly from gram masses of material, with correction for interstitial water. The ratio between the volume occupied by the protoplast (the structures bounded by the inner pericytoplasm membrane) and the volume occupied by the sporoplast (the structures bounded by the outer pericortex membrane) was calculated from measurements made on electron micrographs of medially thin-sectioned spores. Among the various spore types, an exponential increase in the heat resistance correlated directly with the wet density and inversely with the water content and with the protoplast/sporoplast volume ratio. Altogether with results supported a hypothesis that the extent of heat resistance is based in whole or in part on the extent of dehydration and diminution of the protoplast in the dormant spore, without implications about physiological mechanisms for attaining this state.

  2. Resistance to Corrosion of Reinforcement of High Volume Fly Ash Concrete

    Energy Technology Data Exchange (ETDEWEB)

    Kwon, S. O.; Bae, S. H.; Lee, H. J. [Andong National University, Andong (Korea, Republic of); Lee, K. M. [Sungkyunkwan University, Suwon (Korea, Republic of); Jung, S. H. [Korea Confirmity Laboratories, Seoul (Korea, Republic of)

    2014-12-15

    Due to the increasing of interest about the eco-friendly concrete, it is increased to use concretes containing by-products of industry such as fly ash(FA), ground granulated blast furnace slag(GGBFS), silica fume(SF), and etc. Especially, these are well known for improving the resistances to reinforcement corrosion in concrete and decreasing chloride ion penetration. The purpose of this experimental research is to evaluate the resistance against corrosion of reinforcement of high volume fly ash(HVFA) concrete which is replaced with high volume fly ash for cement volume. For this purpose, the concrete test specimens were made for various strength level and replacement ratio of FA, and then the compressive strength and diffusion coefficient for chloride ion of them were measured for 28, 91, and 182 days, respectively. Also, corrosion monitoring by half cell potential method was carried out for the made lollypop concrete test specimens to detect the time of corrosion initiation for reinforcement in concrete. As a result, it was observed from the test results that the compressive strength of HVFA concrete was decreased with increasing replacement ratio of FA but long-term resistances against reinforcement corrosion and chloride ion penetration of that were increased.

  3. Electrical and magneto-resistance of Co/CNT/Epoxy thin film for strain and magnetic field sensing

    Science.gov (United States)

    Anand, Sandeep V.; Isaac, Rejin; Roy Mahapatra, D.

    2009-03-01

    Cobalt and iron nanoparticles are doped in carbon nanotube (CNT)/polymer matrix composites and studied for strain and magnetic field sensing properties. Characterization of these samples is done for various volume fractions of each constituent (Co and Fe nanoparticles and CNTs) and also for cases when only either of the metallic components is present. The relation between the magnetic field and polarization-induced strain are exploited. The electronic bandgap change in the CNTs is obtained by a simplified tight-binding formulation in terms of strain and magnetic field. A nonlinear constitutive model of glassy polymer is employed to account for (1) electric bias field dependent softening/hardening (2) CNT orientations as a statistical ensemble and (3) CNT volume fraction. An effective medium theory is then employed where the CNTs and nanoparticles are treated as inclusions. The intensity of the applied magnetic field is read indirectly as the change in resistance of the sample. Very small magnetic fields can be detected using this technique since the resistance is highly sensitive to strain. Its sensitivity due to the CNT volume fraction is also discussed. The advantage of this sensor lies in the fact that it can be molded into desirable shape and can be used in fabrication of embedded sensors where the material can detect external magnetic fields on its own. Besides, the stress-controlled hysteresis of the sample can be used in designing memory devices. These composites have potential for use in magnetic encoders, which are made of a magnetic field sensor and a barcode.

  4. Time-lapse electrical resistivity anomalies due to contaminant transport around landfills

    Directory of Open Access Journals (Sweden)

    J. Yang

    2007-06-01

    Full Text Available The extent of landfill leachate can be delineated by geo-electrical imaging as a response to the varying electrical resistivity in the contaminated area. This research was based on a combination of hydrogeological numerical simulation followed by geophysical forward and inversion modeling performed to evaluate the migration of a contaminant plume from a landfill. As a first step, groundwater flow and contaminant transport was simulated using the finite elements numerical modeling software FEFLOW. The extent of the contaminant plume was acquired through a hydrogeological model depicting the distributions of leachate concentration in the system. Next, based on the empirical relationship between the concentration and electrical conductivity of the leachate in the porous media, the corresponding geo-electrical structure was derived from the hydrogeological model. Finally, forward and inversion computations of geo-electrical anomalies were performed using the finite difference numerical modeling software DCIP2D/DCIP3D. The image obtained by geophysical inversion of the electric data was expected to be consistent with the initial hydrogeological model, as described by the distribution of leachate concentration. Numerical case studies were conducted for various geological conditions, hydraulic parameters and electrode arrays, from which conclusions were drawn regarding the suitability of the methodology to assess simple to more complex geo-electrical models. Thus, optimal mapping and monitoring configurations were determined.

  5. Correlation of electrical resistivity imaging, push-tool and groundwater electrical conductivity at a heterogeneous field site

    Energy Technology Data Exchange (ETDEWEB)

    Rayner, S.F.; Bentley, L.R.; Robillard, J.M. [Calgary Univ., AB (Canada)

    2003-07-01

    This paper describes the collection of data at a decommissioned sour gas plant, located on a topographic high in central Alberta. The information collected included: push-tool electrical conductivity (EC), three-dimensional electrical resistivity imaging (3D-ERI) and groundwater sample electrical conductivity. There was no correlation between the inverted ERI conductivity values and groundwater EC values, despite the existence of strong correlation between the inverted ERI conductivity values and upscaled push-tool EC. The most probable cause for the lack of correlation between the ERI and groundwater EC values is subsurface heterogeneity. There is a possibility that the EC of the mobile groundwater within the fractures and sand lenses are different than that of the relatively immobile matrix pore water, due to remediation activities. The entrance of the groundwater from piezometers is from high permeability zones (like sand lenses and fractures) within the screened interval. The ERI data mostly likely does not specifically identify the conductivity of the groundwater within these fractures and thin sand lenses. As a result, the manner in which ERI and groundwater data are interpreted in terms of subsurface geochemistry is affected. 4 refs., 4 figs.

  6. Early-age Electrical Resistivity and Reactive Capacity of Mineral Admixtures in Mortars

    Institute of Scientific and Technical Information of China (English)

    LIANG Wenquan; HE Zhen; ZHANG Yongchuan; CHEN Meizhu; YANG Huaquan

    2006-01-01

    A non-contacting electrical resistivity measurement device was used to investigate the effect of different types and contents of mineral admixtures on the hydration performance of mortars during early age. The experimental results show that the changes of measured resistivity with time of hydration can be used to describe the hydration characteristics of cement- based materials, as well as the physical and chemical behavior of fly ash; blast furnace slag and silica fume at the very early ages. With an increasing replacement ratio of mineral admixtures, for the specimens blended with fly ash or slag, the resistivity increases firstly, then the following flatting period extends and after setting the resistivity increasing becomes slow and consequently a lower resistivity value at 24 hours occurs. This is due to the dilution effect and lower pozzolanic/ hydraulic activity of fly ash and slag. However, for the samples incorporated with silica fume, the resistivity value through 24 hours is lower with shorter flatting period and larger slope in the resistivity curves, which is because of its particle size effect and higher pozzolanic activity of silica fume. Moreover, non-contacting resistivity measurement might provide a helpful information to predict the long term performance including the durability of cement-based materials at early ages.

  7. Electrical Resistance of the Solder Connections for the Consolidation of the LHC Main Interconnection Splices

    CERN Document Server

    Lutum, R; Scheuerlein, C

    2013-01-01

    For the consolidation of the LHC 13 kA main interconnection splices, shunts will be soldered onto each of the 10170 splices. The solder alloy selected for this purpose is Sn60Pb40. In this context the electrical resistance of shunt to busbar lap splices has been measured in the temperature range from RT to 20 K. A cryocooler set-up has been adapted such that a test current of 150 A could be injected for accurate resistance measurements in the low nΩ range. To study the influence of the solder bulk resistivity on the overall splice resistance, connections produced with Sn96Ag4 and Sn77.2In20Ag2.8 have been studied as well. The influence of the Sn60Pb40 solder resistance is negligible when measuring the splice resistance in a longitudinal configuration over a length of 6 cm. In a transverse measurement configuration the splice resistance is significantly influenced by the solder. The connections prepared with Sn77.2In20Ag2.8 show significantly higher resistance values, as expected from the relatively high sol...

  8. Inspection of earthen embankment dams using time lapse electrical resistivity tomography

    Science.gov (United States)

    Case, Jared S.

    According to the National Inventory of Dams (NID), the number of dams across the United States is approximately 85,000. Many of these dams are more than 50 years old and need vast attention to ensure their safety. It is difficult to obtain a full assessment of the dam just by visual inspections alone. This is because many problems associated with dam failure occur internally, which makes it difficult to be observed by the dam inspectors. Examples of these flaws are piping and seepage (flow of water through or around dam walls). It is in this area where geophysical methods can aid in obtaining a more confident evaluation of a dam's integrity. Electrical resistivity is one geophysical technique that would be useful in detecting internal flaws associated with seepage and piping because it is sensitive to moisture changes. A study is being conducted to examine the feasibility of electrical resistivity tomography (ERT) to map and monitor internal compromised zones within earthen embankment dams. Two quarter-scaled earthen embankment dams were built at the United States Department of Agriculture (USDA) Agriculture Research Service (ARS) Hydraulics and Engineering Research Unit (HERU) in Stillwater, Oklahoma. These two dams were constructed with known internal compromised zones that are susceptible to seepage and piping. Electrical resistivity surveys were conducted on the completed dams using a 56 electrode dipole-dipole array. The collected data was then processed using electrical resistivity tomography (ERT) imaging software and evidence of these two compromised zones was easily visible. Also, additional surveys were conducted in order to monitor the changes in electrical signatures associated with changes in these zones due to filling of the reservoir and environmental/climate changes.

  9. A thermomechanical study of the electrical resistance of Cu lead interconnections

    Science.gov (United States)

    Liu, D. S.; Chen, C. Y.; Chao, Y. C.

    2006-05-01

    The choice of liquid crystal display (LCD) driver packaging technology significantly influences the display performance of flat panel displays. Tape automated bonding (TAB) is generally the method of choice for connecting the LCD and the LCD driver circuit in flat panel displays. To achieve a finer pitch, an easier assembly, and a greater connection reliability, the design of the inner Cu lead must not only consider thermomechanical failure aspects, but must also maintain an acceptable joint resistance. This paper proposes an analytical model to predict the unit change in resistance of the copper foils used for TAB inner lead interconnections under various thermal environments and stressstrain states. The analytical model is based on a constitutive equation of the copper foil and the working principle of strain gages. Copper foil specimens are tensile tested at temperatures of 25°C, 50°C, 75°C, and 100°C at strain rates of 0.2/min. and 0.5/min., respectively, to confirm the validity of the developed analytical model. The numerical results and the experimental data are found to be in good agreement. Hence, the analytical method provides the means of predicting the thermal effect on the electrical and mechanical properties of the copper foils. Finally, by implementing finite-element method (FEM) solutions in the developed analytical model, this study constructs electrical resistance design charts to predict the variation in the electrical resistance of the copper foils under different thermal-mechanical conditions.

  10. Surface Morphology and Electrical Resistivity in Polycrystalline Au/Cu/Si(100 System

    Directory of Open Access Journals (Sweden)

    T. E. Novelo

    2017-01-01

    Full Text Available This work describes the analysis of morphology and electrical resistivity (ρ obtained in the Au/Cu/Si system. The Au/Cu bilayers were deposited by thermal evaporation technique with thicknesses from 50 to 250 nm on SiOx/Si(100 substrates. The Au : Cu concentration ratio of the samples was of 25 : 75 at%. The bilayers were annealed into a vacuum oven with argon atmosphere at 660 K for one hour. The crystalline structures of AuCu and CuSi alloys were confirmed by X-ray diffraction analysis. The scanning electron microscopy (SEM, the atomic force microscopy (AFM, and the energy dispersive spectroscopy (EDS were used to study the morphology, final thickness, and the atomic concentration of the alloys formed, respectively. The four-point probe technique was used to measure the electrical resistivity (ρ in the prepared alloys as a function of thickness. The ρ value was measured and it was numerically compared with the Fuchs–Sondheimer (FS and the Mayadas–Shatzkes (MS models of resistivity. Results show values of electrical resistivity between 0.9 and 1.9 μΩ-cm. These values are four times smaller than the values of the AuCu systems reported in literature.

  11. Influence of plant roots on electrical resistivity measurements of cultivated soil columns

    Science.gov (United States)

    Maloteau, Sophie; Blanchy, Guillaume; Javaux, Mathieu; Garré, Sarah

    2016-04-01

    Electrical resistivity methods have been widely used for the last 40 years in many fields: groundwater investigation, soil and water pollution, engineering application for subsurface surveys, etc. Many factors can influence the electrical resistivity of a media, and thus influence the ERT measurements. Among those factors, it is known that plant roots affect bulk electrical resistivity. However, this impact is not yet well understood. The goals of this experiment are to quantify the effect of plant roots on electrical resistivity of the soil subsurface and to map a plant roots system in space and time with ERT technique in a soil column. For this research, it is assumed that roots system affect the electrical properties of the rhizosphere. Indeed the root activity (by transporting ions, releasing exudates, changing the soil structure,…) will modify the rhizosphere electrical conductivity (Lobet G. et al, 2013). This experiment is included in a bigger research project about the influence of roots system on geophysics measurements. Measurements are made on cylinders of 45 cm high and a diameter of 20 cm, filled with saturated loam on which seeds of Brachypodium distachyon (L.) Beauv. are sowed. Columns are equipped with electrodes, TDR probes and temperature sensors. Experiments are conducted at Gembloux Agro-Bio Tech, in a growing chamber with controlled conditions: temperature of the air is fixed to 20° C, photoperiod is equal to 14 hours, photosynthetically active radiation is equal to 200 μmol m-2s-1, and air relative humidity is fixed to 80 %. Columns are fully saturated the first day of the measurements duration then no more irrigation is done till the end of the experiment. The poster will report the first results analysis of the electrical resistivity distribution in the soil columns through space and time. These results will be discussed according to the plant development and other controlled factors. Water content of the soil will also be detailed

  12. Monitoring CO2 migration in a shallow sand aquifer using 3D crosshole electrical resistivity tomography

    DEFF Research Database (Denmark)

    Yang, Xianjin; Lassen, Rune Nørbæk; Jensen, Karsten Høgh;

    2015-01-01

    Three-dimensional (3D) crosshole electrical resistivity tomography (ERT) was used to monitor a pilot CO2 injection experiment at Vrøgum, western Denmark. The purpose was to evaluate the effectiveness of the ERT method for detection of small electrical conductivity (EC) changes during the first 2...... the migration of a CO2 plume consist of buoyancy of gaseous CO2, local heterogeneity, groundwater flow and external pressure exerted by the injector. The CO2 plume at the Vrøgum site migrated mostly upward due to buoyancy and it also skewed toward northeastern region by overcoming local groundwater flow...

  13. Resistance exercise with different volumes: blood pressure response and forearm blood flow in the hypertensive elderly

    Science.gov (United States)

    Brito, Aline de Freitas; de Oliveira, Caio Victor Coutinho; Brasileiro-Santos, Maria do Socorro; Santos, Amilton da Cruz

    2014-01-01

    Background The purpose of this study was to evaluate the effect of two sessions of resistance exercise with different volumes on post-exercise hypotension, forearm blood flow, and forearm vascular resistance in hypertensive elderly subjects. Methods The study was conducted with ten hypertensive elderly (65±3 years, 28.7±3 kg/m2) subjected to three experimental sessions, ie, a control session, exercise with a set (S1), and exercise with three sets (S3). For each session, the subjects were evaluated before and after intervention. In the pre-intervention period, blood pressure, forearm blood flow, and forearm vascular resistance were measured after 10 minutes of rest in the supine position. Thereafter, the subjects were taken to the gym to perform their exercise sessions or remained at rest during the same time period. Both S1 and S3 comprised a set of ten repetitions of ten exercises, with an interval of 90 seconds between exercises. Subsequently, the measurements were again performed at 10, 30, 50, 70, and 90 minutes of recovery (post-intervention) in the supine position. Results Post-exercise hypotension was greater in S3 than in S1 (systolic blood pressure, −26.5±4.2 mmHg versus −17.9±4.7 mmHg; diastolic blood pressure, −13.8±4.9 mmHg versus −7.7±5 mmHg, P<0.05). Similarly, forearm blood flow and forearm vascular resistance changed significantly in both sessions with an increase and decrease, respectively, that was more evident in S3 than in S1 (P<0.05). Conclusion Resistance exercises with higher volume were more effective in causing post-exercise hypotension, being accompanied by an increase in forearm blood flow and a reduction of forearm vascular resistance. PMID:25540580

  14. Monitoring radio-frequency heating of contaminated soils using electrical resistance tomography

    Energy Technology Data Exchange (ETDEWEB)

    Ramirez, A.L.; Daily, W.D.

    1993-09-01

    Electrical resistance tomography (ERT) was used to monitor a radio-frequency heating process for the insitu remediation of volatile organic compounds from subsurface water and soil at the Savannah River Site, near Aiken, South Carolina. A dipole antenna located in a horizontal well in the unsaturated zone was used to heat a contaminated clay layer. The heat-induced changes were tomographically imaged by their effects on the formation electrical resistivity. The resistivity changes observed appear to be related to heating and vaporization of the pore water, formation of steam condensate, and infiltration of rainwater through the heated zones and adjacent areas. There is a clear asymmetry downward in the resistivity decreases associated with the heating process. The resistivity decreases observed in the vicinity of the heating well are believed to be caused by the heating and downward migration of warm water originally located within a radius of a few feet around the heating well; the magnitude of the change is between 10--20%. The decreasing resistivity implies an increasing rate of radio wave attenuation as heating progressed; therefore, the rate of energy deposition around the heating well increased while the penetration distance of the radio waves decreased. Saturation changes in the clay near the antenna during heating were estimated to be 50--55% based on the observed resistivity decreases. Resistivity changes observed at distances greater than 3 meters to one side of the antenna appear to be related to rainwater infiltration. We propose that gaps in near surface clay layers allow rainwater to migrate downward and reach the top of clay rich zone penetrated by the antenna borehole. The water may then accumulate along the top of the clay.

  15. Muscle Volume Increases Following 16 Weeks of Resistive Exercise Training with the Advanced Resistive Exercise Device (ARED) and Free Weights

    Science.gov (United States)

    Nash, R. E.; Loehr, J. A.; Lee, S. M. C.; English, K. L.; Evans, H.; Smith, S. A.; Hagan, R. D.

    2009-01-01

    Space flight-induced muscle atrophy, particularly in the postural and locomotorymuscles, may impair task performance during long-duration space missions and planetary exploration. High intensity free weight (FW) resistive exercise training has been shown to prevent atrophy during bed rest, a space flight analog. NASA developed the Advanced Resistive Exercise Device (ARED) to simulate the characteristics of FW exercise (i.e. constant mass, inertial force) and to be used as a countermeasure during International Space Station (ISS) missions. PURPOSE: To compare the efficacy of ARED and FW training to induce hypertrophy in specific muscle groups in ambulatory subjects prior to deploying ARED on the ISS. METHODS: Twenty untrained subjects were assigned to either the ARED (8 males, 3 females) or FW (6 males, 3 females) group and participated in a periodizedtraining protocol consisting of squat (SQ), heel raise (HR), and deadlift(DL) exercises 3 d wk-1 for 16 wks. SQ, HR, and DL muscle strength (1RM) was measured before, after 8 wks, and after 16 wks of training to prescribe exercise and measure strength changes. Muscle volume of the vastigroup (V), hamstring group (H), hip adductor group (ADD), medial gastrocnemius(MG), lateral gastrocnemius(LG), and deep posterior muscles including soleus(DP) was measured using MRI pre-and post-training. Consecutive cross-sectional images (8 mm slices with a 2 mm gap) were analyzed and summed. Anatomical references insured that the same muscle sections were analyzed pre-and post-training. Two-way repeated measures ANOVAs (pmuscle strength and volume between training devices. RESULTS: SQ, HR, and DL 1RM increased in both FW (SQ: 49+/-6%, HR: 12+/-2%, DL: 23+/-4%) and ARED (SQ: 31+/-4%, HR: 18+/-2%, DL: 23+/-3%) groups. Both groups increased muscle volume in the V (FW: 13+/-2%, ARED: 10+/-2%), H (FW: 3+/-1%, ARED: 3+/-1 %), ADD (FW: 15=/-2%, ARED: 10+/-1%), LG (FW: 7+/-2%, ARED: 4+/-1%), MG (FW: 7+/-2%, ARED: 5+/-2%), and DP (FW: 2

  16. ENVIRONMENTAL MONITORING OF LEAKS USING TIME LAPSED LONG ELECTRODE ELECTRICAL RESISTIVITY

    Energy Technology Data Exchange (ETDEWEB)

    MYERS DA; RUCKER DF; FINK JB; LOKE MH

    2009-12-16

    Highly industrialized areas pose challenges for surface electrical resistivity characterization due to metallic infrastructure. The infrastructure is typically more conductive than the desired targets and will mask the deeper subsurface information. These challenges may be minimized if steel-cased wells are used as long electrodes in the area near the target. We demonstrate a method of using long electrodes to electrically monitor a simulated leak from an underground storage tank with both synthetic examples and a field demonstration. The synthetic examples place a simple target of varying electrical properties beneath a very low resistivity layer. The layer is meant to replicate the effects of infrastructure. Both surface and long electrodes are tested on the synthetic domain. The leak demonstration for the field experiment is simulated by injecting a high conductivity fluid in a perforated well within the S tank farm at Hanford, and the resistivity measurements are made before and after the leak test. All data are processed in four dimensions, where a regularization procedure is applied in both the time and space domains. The synthetic test case shows that the long electrode ERM could detect relative changes in resistivity that are commensurate with the differing target properties. The surface electrodes, on the other hand, had a more difficult time matching the original target's footprint. The field results shows a lowered resistivity feature develop south of the injection site after cessation of the injections. The time lapsed regularization parameter has a strong influence on the differences in inverted resistivity between the pre and post injection datasets, but the interpretation of the target is consistent across all values of the parameter. The long electrode ERM method may provide a tool for near real-time monitoring of leaking underground storage tanks.

  17. Manufacturing cost analysis of a parabolic dish concentrator (General Electric design) for solar thermal electric power systems in selected production volumes

    Science.gov (United States)

    1981-01-01

    The manufacturing cost of a General Electric 12 meter diameter concentrator was estimated. This parabolic dish concentrator for solar thermal system was costed in annual production volumes of 100 - 1,000 - 5,000 - 10,000 - 50,000 100,000 - 400,000 and 1,000,000 units. Presented for each volume are the costs of direct labor, material, burden, tooling, capital equipment and buildings. Also presented is the direct labor personnel and factory space requirements. All costs are based on early 1981 economics.

  18. Monitoring of olive oil mills' wastes using electrical resistivity tomography techniques

    Science.gov (United States)

    Simyrdanis, Kleanthis; Papadopoulos, Nikos; Kirkou, Stella; Sarris, Apostolos; Tsourlos, Panagiotis

    2014-08-01

    Olive oil mills' wastes (OOMW) are one of the byproducts of the oil production that can lead to serious environmental pollution when they are deposited in ponds dug on the ground surface. Electrical Resistivity Tomography (ERT) method can provide a valuable tool in order to monitor through time the physical flow of the wastes into the subsurface. ERT could potentially locate the electrical signature due to lower resistivity values resulting from the leakage of OOMW to the subsurface. For this purpose, two vertical boreholes were installed (12m depth, 9 m apart) in the vicinity of an existing pond which is filled with OOMW during the oil production period. The test site is situated in Saint Andreas village about 15km south of the city of Rethymno (Crete, Greece). Surface ERT measurements were collected along multiple lines in order to reconstruct the subsurface resistivity models. Data acquisition was performed with standard and optimized electrode configuration protocols. The monitoring survey includes the ERT data collection for a period of time. The study was initiated before the OOMW were deposited in the pond, so resistivity fluctuations are expected due to the flow of OOMW in the porous subsurface media through time. Preliminary results show the good correlation of the ERT images with the drilled geological formations and the identification of low resistivity subsurface zone that could be attributed to the flow of the wastes within the porous layers.

  19. Electrical Resistance Behavior of Vinylester Composites Filled with Glass-carbon Hybrid Fibers

    Institute of Scientific and Technical Information of China (English)

    WANG Jun; ZHANG Lianmeng; XU Renxin; DUAN Huajun; YANG Xiaoli; WANG Xiang

    2009-01-01

    Vinylester (bismethacryloxy derivative of a bisphenol-A type EP resin, VE) composites with glass-carbon hybrid fibers (CF-GF) weight fraction of 50%, were prepared by the compress molding method. The distribution of carbon fiber in the hybrids was observed by stereomicroscope. The electrical resistance behavior of the composites filled with different carbon fiber (CF) weight contents (0.5% to 20%) was studied. The experimental results show that the electrical resistance behaviors of CF-GF/VE composites are different with those of CF/VE composites because carbon fibers' conducting networks are broken by the glass fibers in the CF-GF/VE composites. The carbon fibers distribute uniformly in the networks of glass fibers (GF) like single silk and form the semi-continuous conducting networks. Composite filled with GF-CF hybrid has a higher percolation threshold than that filled with pure CF. At that time, the resistivity of CF-GF/VE composites varies little with the temperature increasing. The temperature coefficient of resistivity in GF-CF/VE composite is less than 317 ppm and the variation of the resistivity after ten thermal cycles from 20 ℃to 240 ℃ is less than 1.96%.

  20. Electrical Resistivity Monitoring of an Active Hydrothermal Degassing Area at Solfatara, Phlegrean Fields.

    Science.gov (United States)

    Vandemeulebrouck, J.; Byrdina, S.; Grangeon, J.; Lebourg, T.; Bascou, P.; Mangiacapra, A.

    2015-12-01

    Campi Flegrei caldera (CFc) is an active volcanic complex covering a ~100 km² densely populated area in the western part of Naples (Italy) that is presently showing clear signs of unrest. Solfatara volcano, a tuff cone crater formed ~4000 yrs B.P. ago by phreato-magmatic eruptions represents the main degassing outflow of CFc. Magmatic gases which are exsolved from a ~8 km deep magmatic reservoir mix at 4 km depth with meteoric hydrothermal fluids then reach the surface in the Solfatara area. These hydrothermal and magmatic gases, mainly H2O and CO2, are released through both diffuse degassing structures and fumaroles. In the frame of the MedSuv (Mediterranean Supervolcanoes) FP7 european project , we are performing a time-lapse electrical resistivity monitoring of an active degassing area of Solfatara. Using a 500-m-long cable and 48 electrodes, an electrical resistivity tomography (ERT) is performed on a two-day basis since May 2013. The time-lapse inversion of the ERT gives an image of the temporal variations of resistivity up to 100 m depth that can be compared with the variations of ground deformation, CO2 flux, soil temperature and seismic ambient noise. Resistivity variations can originate from fluid composition, gas ratio and temperature. For example, the abrupt change of resistivity that was observed mid-2014 during a period of uplift and gas flux increase, could be associated with the rise of hydrothermal fluids.

  1. Lembang fault plane identification using electrical resistivity method for disaster mitigation

    Science.gov (United States)

    Maulinadya, S.; Ramadhan, M. Lutfi; N. Wening, F.; Pinehas, D.; Widodo

    2017-07-01

    Lembang Fault is an active fault lies from West to East located 10 kilometers in north of Bandung. It is a normal fault that its foot wall raises 40-450 meters above the ground. Its location that is not so far from Bandung, which is densely populated and frequently visited by tourists, makes Lembang Fault a threat if it becomes suddenly active. Its movement can cause earthquakes that can result in fatalities. Therefore, act of mitigation is necessary, such as educating people about Lembang Fault and its potential to cause disaster. The objective of this study is to find Lembang Fault plane below the surface with geo electrical mapping method and vertical elect rical sounding method around Ciwarega and The Peak, Lembang (west side of Lembang Fault). Both of these methods are using electricity current to measure rock resistivity. Currents are injected to the ground and potential differences are measured. According to Ohm's Law, resistivity can be calculated so that resistivity distribution can be obtained. In this study, high resistivity contrast is obtained; it is about 1400-5000 Ohm.m. This resistivity contrast can be caused by lateral lithology difference resulted by fault existence. This proves that there is actually a fault in Lembang that potentially cause disasters like earthquakes.

  2. RSRM top hat cover simulator lightning test, volume 2. Appendix A: Resistance measurements. Appendix B: Lightning test data plots

    Science.gov (United States)

    1990-01-01

    Resistance measurements are given in graphical for when a simulated lightning discharge strikes on an exposed top hat cover simulator. The test sequence was to measure the electric and magnetic fields induced inside a redesigned solid rocket motor case.

  3. Clopidogrel resistance of patients with coronary artery disease and its correlation with platelet count and mean platelet volume

    Institute of Scientific and Technical Information of China (English)

    李蕾

    2013-01-01

    Objective To explore the association between clopidogrel resistance(CR)as assessed by whole blood electrical impedance aggregometry(EIA) and platelet parameters.Methods The prospective study comprised 152 patients

  4. Effect of decreasing electrical resistance in Characeae cell membranes caused by the flow of alternating current

    Directory of Open Access Journals (Sweden)

    Edward Śpiewla

    2014-02-01

    Full Text Available By means of the techniques of external electrodes and microelectrodes, it was found that evanescent flow of an alternating current through plasmalemma of Characeae cells neutralises oscillatory change in their electrical resistance and reversibly diminishes its value. This effect is particularly significant in the case of "high resistance cells", but it weakens with increasing temperature. The value of the estimated activation energy indicates that, after flow of the alternating current through the membrane, a rapid increase in the conductivity may be caused by an increase in conductivity of potassium channels. This result seems to support the hypothesis of electroconformational feedback.

  5. A model of the electrical volume conductor in the region of the eye in the ELF range.

    Science.gov (United States)

    Lindenblatt, G; Silny, J

    2001-11-01

    Electrical and magnetic phosphenes are irritations of the eye caused by electric currents or magnetic fields. These are well known effects initially investigated in the early 1900s. Available estimations of the current densities in the eye, based on the assumption of a homogeneous volume conductor, show low thresholds. These outdated thresholds are still an important cornerstone when justifying today's limit values for extremely low-frequency (ELF) fields specified by statutory regulations. In vitro measurements of the complex conductivity of cattle eye are carried out for the ELF range (5-2000 Hz) separated for the different tissues of the eyeball. They do not show peculiarities at 20 Hz which is the threshold minimum for the phosphene generation. The reported conductivity data of the eye region show variations of two orders of magnitude regarding the electrical conductivity of the individual tissue layers. Starting with these new data, a model of the orbita is introduced describing the eye and its periphery as an electrically inhomogeneous volume conductor. This model contains small-scale structures which are expected to behave as good electrical conductors yielding regions of higher field values within the eye. Therefore, earlier models assuming a homogeneous volume conductor can be regarded as oversimplistic.

  6. The electric energy and the environment in Mexico. Volume 3; Energia electrica y medio ambiente en Mexico. Volumen 3

    Energy Technology Data Exchange (ETDEWEB)

    Quintanilla Martinez, Juan [eds.] [Universidad Nacional Autonoma de Mexico, Mexico, D. F. (Mexico)

    1997-12-31

    This document is the third one of three volumes of the 1. Seminar on the Current Conditions and Perspectives of the Electric Sector in Mexico, organized by the Programa Universitario de Energia and the Instituto de Investigaciones Economicas (University Program of Energy and the Institute of Economic Research), both of them agencies of the Universidad Autonoma de Mexico (UNAM). The titles of the three volumes are the following: Volume 1.- The opening of the Mexican Electric Sector to foreign investment. Volume 2.- Concrete innovation and technological learning experiences at the Luz y Fuerza del Centro enterprise. Volume 3.- The Electric Energy and the Environment in Mexico. This third volume covers the following subjects: Hydroelectricity, land use and water managing; the electric generation in Mexico and its environmental impact, the nuclear electricity and the handling of radioactive materials; the exposure to electromagnetic fields and its association with children`s leukemia; the energy in Mexico and the sustainable development; potential of electricity generation in large scale with wind power in Mexico; towards a scheme of distributed electric power generation with non-conventional energies and renewable energy sources in Mexico in the 21Century. These documents were elaborated by specialists of the electric sector, from the sector itself as well as from private and public academic entities [Espanol] Este documento constituye el tercero de tres volumenes del Primer Seminario sobre Situacion y Perspectivas del Sector Electrico en Mexico, organizado por el Programa Universitario de Energia y el Instituto de Investigaciones Economicas, ambas dependencias de la Universidad Nacional Autonoma de Mexico (UNAM). Los titulos de los tres volumenes son los siguientes: volumen 1: La apertura externa del sector electrico mexicano, volumen 2: Experiencias concretas de innovacion y aprendizaje tecnologico en la empresa Luz y Fuerza del Centro, volumen 3: Energia electrica

  7. Electrical resistivity of rock and its correlation to engineering properties; Ganseki {center{underscore}dot} ganban no hiteiko to sono kogakuteki seishitsu tono kankei ni tsuite

    Energy Technology Data Exchange (ETDEWEB)

    Nishimaki, Hitoshi; Sekine, Ichiro [Toda Corp., Tokyo (Japan); Saito, Akira [Mitsui Mineral Development Engineering Corp., Tokyo (Japan); Yoshinaka, Ryunoshin [Saitama University, Saitama (Japan). Faculty of Engineering

    1999-04-01

    In order to interpret resistivity profiles derived from electrical and electromagnetic surveys, it is necessary to study the correlation between electrical resistivity of rock and engineering properties. In this paper, we investigate the electrical resistivity of rock and its correlation to engineering properties. The experiments reveal the importance of electric surface conduction for studying those problems. These results suggest that resistivity measurements can be used as a quantitative guide in evaluating an area as to its engineering properties. (author)

  8. Hyperbolic Method to Analyze the Electrical Resistivity Curve of Portland Cements with Superplasticizer

    Institute of Scientific and Technical Information of China (English)

    WEI Xiaosheng; XIAO Lianzhen; LI Zongjin

    2008-01-01

    Electrical measurement was employed to investigate the early hydration characteristics of cement pastes with different dosages of superplasticizer in the same W/C ratio. The hyperbolic method was applied to analyze the electrical resistivity development. The peak point (Ph) on the hyperbolic curve could be easily read. The time (th) to reach the point Ph had strong relations with the setting time. th was delayed with the increment of the dosage of superplasticizer. The time th was used to plot the relationship between the initial setting time and final setting time. The hyperbolic equation was established to predict the ultimate resistivity.The retardation effect of the superplasticizer was confirmed in the same W/C ratio by setting time and isothermal heat eyolution.

  9. Estimation of Recharge from Long-Term Monitoring of Saline Tracer Transport Using Electrical Resistivity Tomography

    DEFF Research Database (Denmark)

    Haarder, Eline Bojsen; Jensen, Karsten Høgh; Binley, Andrew;

    2015-01-01

    The movement of a saline tracer added to the soil surface was monitored in the unsaturated zone using cross-borehole electrical resistivity tomography (ERT) and subjected to natural rainfall conditions. The ERT data were inverted and corrected for subsurface temperature changes, and spatial moment...... methods. In September 2011, a saline tracer was added across a 142-m2 area at the surface at an application rate mimicking natural infiltration. The movement of the saline tracer front was monitored using cross-borehole electrical resistivity tomography (ERT); data were collected on a daily to weekly...... basis and continued for 1 yr after tracer application. The ERT data were inverted and corrected for temperature changes in the subsurface, and spatial moment analysis was used to calculate the tracer mass, position of the center of mass, and thereby the downwardly recharging flux. The recovered mass...

  10. Electrical resistance load effect on magnetoelectric coupling of magnetostrictive/piezoelectric laminated composite

    Energy Technology Data Exchange (ETDEWEB)

    Wang, Yaojin, E-mail: wangyaojin@hotmail.co [Key Laboratory of Inorganic Functional Material and Device, Shanghai Institute of Ceramics, Chinese Academy of Sciences, 215 Chengbei Road, Jiading, Shanghai 201800 (China); Graduate University of the Chinese Academy of Sciences, Beijing 100049 (China); Zhao, Xiangyong [Key Laboratory of Inorganic Functional Material and Device, Shanghai Institute of Ceramics, Chinese Academy of Sciences, 215 Chengbei Road, Jiading, Shanghai 201800 (China); Jiao, Jie; Liu, Linhua [Key Laboratory of Inorganic Functional Material and Device, Shanghai Institute of Ceramics, Chinese Academy of Sciences, 215 Chengbei Road, Jiading, Shanghai 201800 (China); Graduate University of the Chinese Academy of Sciences, Beijing 100049 (China); Di, Wenning; Luo, Haosu [Key Laboratory of Inorganic Functional Material and Device, Shanghai Institute of Ceramics, Chinese Academy of Sciences, 215 Chengbei Road, Jiading, Shanghai 201800 (China); Or, Siu Wing, E-mail: eeswor@polyu.edu.h [Department of Electrical Engineering, The Hong Kong Polytechnic University, Hung Hom, Kowloon (Hong Kong)

    2010-06-25

    The effect of electrical resistance load on the magnetoelectric (ME) coupling of laminated composite of Tb{sub 0.3}Dy{sub 0.7}Fe{sub 1.92} (Terfenol-D) magnetostrictive alloy and 0.7Pb (Mg{sub 1/3}Nb{sub 2/3})O{sub 3}-0.3PbTiO{sub 3} (PMN-PT) piezoelectric single crystal is investigated at both non-resonance and resonance frequencies. The results show that (i) the ME coefficient and ME resonance frequency increase with the increase in electrical resistance load, and (ii) the maximum ME power occurs in open-circuit condition. The present study provides the basis for the design of ME sensors and their signal-processing and electronic circuits.

  11. Research on Image Reconstruction Algorithms for Tuber Electrical Resistance Tomography System

    Directory of Open Access Journals (Sweden)

    Jiang Zili

    2016-01-01

    Full Text Available The application of electrical resistance tomography (ERT technology has been expanded to the field of agriculture, and the concept of TERT (Tuber Electrical Resistance Tomography is proposed. On the basis of the research on the forward and the inverse problems of the TERT system, a hybrid algorithm based on genetic algorithm is proposed, which can be used in TERT system to monitor the growth status of the plant tubers. The image reconstruction of TERT system is different from the conventional ERT system for two phase-flow measurement. Imaging of TERT needs more precision measurement and the conventional ERT cares more about the image reconstruction speed. A variety of algorithms are analyzed and optimized for the purpose of making them suitable for TERT system. For example: linear back projection, modified Newton-Raphson and genetic algorithm. Experimental results showed that the novel hybrid algorithm is superior to other algorithm and it can effectively improve the image reconstruction quality.

  12. Coupled stress-strain and electrical resistivity measurements on copper based shape memory single crystals

    Directory of Open Access Journals (Sweden)

    Gonzalez Cezar Henrique

    2004-01-01

    Full Text Available Recently, electrical resistivity (ER measurements have been done during some thermomechanical tests in copper based shape memory alloys (SMA's. In this work, single crystals of Cu-based SMA's have been studied at different temperatures to analyse the relationship between stress (s and ER changes as a function of the strain (e. A good consistency between ER change values is observed in different experiments: thermal martensitic transformation, stress induced martensitic transformation and stress induced reorientation of martensite variants. During stress induced martensitic transformation (superelastic behaviour and stress induced reorientation of martensite variants, a linear relationship is obtained between ER and strain as well as the absence of hys teresis. In conclusion, the present results show a direct evidence of martensite electrical resistivity anisotropy.

  13. Electron scattering characteristics of polycrystalline metal transition films by in-situ electrical resistance measurements

    Energy Technology Data Exchange (ETDEWEB)

    Trindade, I.G. [Faculdade de Ciencias da Universidade do Porto, Physics Department, Rua do Campo Alegre 687, 4169-007 Porto (Portugal); IFIMUP and IN, Rua do Campo Alegre 687, 4169-007 Porto (Portugal)], E-mail: i_trindade@msn.com; Leitao, D. [IFIMUP and IN, Rua do Campo Alegre 687, 4169-007 Porto (Portugal); Fermento, R. [Instituto de Microelectronica de Madrid, Isaac Newton 8, 28760 Tres Cantos, Madrid (Spain); Pogorelev, Y.; Sousa, J.B. [Faculdade de Ciencias da Universidade do Porto, Physics Department, Rua do Campo Alegre 687, 4169-007 Porto (Portugal); IFIMUP and IN, Rua do Campo Alegre 687, 4169-007 Porto (Portugal)

    2009-08-15

    In-situ electrical resistance measurements were performed to obtain the scattering characteristics of very thin polycrystalline metal transition magnetic alloys grown by ion beam deposition (IBD) on specific underlayers. The experimental curves show size effects at small film thicknesses and important differences between Co{sub 85}Fe{sub 15} and Ni{sub 81}Fe{sub 19} thin layers grown on identical underlayers of Ta70 A/Ru13 A. The largest difference was observed in Ni{sub 81}Fe{sub 19} films grown on underlayers of amorphous Ta70 A. The experimental curves of electrical resistivity/conductivity variation with layer thickness were well fit within the Mayadas and Shatzkes (M-S) model, assuming specific formulations for grain growth with layer thickness.

  14. Electrical Resistance and Transport Numbers of Ion-Exchange Membranes Used in Electrodialytic Soil Remediation

    DEFF Research Database (Denmark)

    Hansen, Henrik; Ottosen, Lisbeth M.; Villumsen, Arne

    1999-01-01

    causes damage to the membrane. This work presents the result from transport number and electrical resistance measurements done on four sets of ion-exchange membranes (Ionics, Inc. CR67 HMR412 cation-exchange membranes and Ionics, Inc. AR204 SXZR anion-exchange membranes), which have been used in four......Electrodialytic soil remediation is a recently developed method to decontaminate heavy metal polluted soil using ion-exchange membranes. In this method one side of the ion-exchange membrane is in direct contact with the polluted soil. It is of great importance to know if this contact with the soil...... different electrodialytic soil remediation experiments. The experiments showed that after the use in electrodialytic soil remediation, the ion-exchange membranes had transport numbers in the same magnitude as new membranes. The electrical resistance for six membranes did not differ from that of new...

  15. Electrical resistivity of yttrium single crystals in the range 4. 2--300 K

    Energy Technology Data Exchange (ETDEWEB)

    Volkenshtein, N.V.; Dyakina, V.P.; Kumin, P.R.; Startsev, V.E.; Volkov, V.T.; Nikiforova, T.V.

    1984-08-01

    The electrical resistivity of pure yttrium single crystals (rho/sub 273.2//rho/sub 4.2/approx. =700) oriented along the <0001> and <1010> axes has been investigated in the temperature range 4.2--300 K. It was established that the scattering of electrons by phonons is described by the Bloch--Grueneisen function for both orientations over the whole temperature range, with the parameter THETA/sub R/ equal to the Debye temperature THETA/sub D/. It was found that a contribution to rho(T) quadratic in the temperature is two orders of magnitude greater than in other transition metals. It is shown that the anisotropy in the electrical resistivity of yttrium at Tapprox.THETA/sub D/ is completely determined by the anisotropy of its Fermi surface.

  16. Does Changes in the Electrical Resistance of an Acupuncture Meridian Predict Pain Intensity Following Orthopedic Surgery?

    OpenAIRE

    Rezvani, Mehran; Alebouyeh, Mahmoud-Reza; Imani, Farnad; Entezary, Saeid Reza; Mohseni, Masood

    2013-01-01

    Background Several methods for assessment of severity of pain have been proposed but all of them are subjective. Objectives This study evaluated the association concerning changes in electrical resistance (ER) between two acupuncture points and severity of postoperative pain in order to define an objective measurement of pain. Patients and Methods In a cross-sectional study, 50 patients undergoing lower extremity orthopedic surgery with postoperative moderate to severe pain (VAS > 4,) were co...

  17. High pressure electrical resistivity study on nonlinear bis thiourea cadmium chloride (BTCC) single crystal

    Energy Technology Data Exchange (ETDEWEB)

    Ariponnammal, S.; Radhika, S. [Department of Physics, Gandhigram Rural Institute, Deemed University, Gandhigram - 624 302, Dindigul District, Tamil Nadu (India); Selva Vennila, R. [Department of Physics, Anna University, Chennai - 600 025 (India); Arumugam, S. [Department of Physics, Bharathidasan University, Trichy (India)

    2005-09-01

    The Bis Thiourea Cadmium Chloride (BTCC) crystals have been crystallized by slow evaporation technique. The lattice parameters of the grown crystals have been determined by the Energy dispersive x-ray diffraction technique (EDXRD) and the structure has been confirmed. The high pressure electrical resistivity study have been carried out on this crystal and the results have been reported here. (copyright 2005 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim) (orig.)

  18. High temperature static strain measurement with an electrical resistance strain gage

    Science.gov (United States)

    Lei, Jih-Fen

    1992-01-01

    An electrical resistance strain gage that can supply accurate static strain measurement for NASP application is being developed both in thin film and fine wire forms. This gage is designed to compensate for temperature effects on substrate materials with a wide range of thermal expansion coefficients. Some experimental results of the wire gage tested on one of the NASP structure materials, i.e., titanium matrix composites, are presented.

  19. Multidimensional electrical resistivity survey for bedrock detection at the Rieti Plain (Central Italy)

    Science.gov (United States)

    Cardarelli, Ettore; De Donno, Giorgio

    2017-06-01

    The combined use of 1D, 2D and 3D electrical resistivity methods for estimating bedrock depth is presented with an application to a case study located in Central Italy. The site is a narrow basin where two boreholes were drilled reaching the bedrock, which had the greatest depth in the center of the basin. Six vertical electrical soundings were executed along a basin cross-section in order to have a preliminary 1D reconstruction of the bedrock and the overlying alluvial deposits. Inverted resistivity models, show bedrock depths in accordance with the borehole data and a complex subsurface layering of the overburden deposits to be further investigated with 2D and 3D electrical resistivity tomography. Four additional electrical lines, acquired using a pole-dipole array and directed normally to the alignment of the vertical soundings, confirm the 1D results in regards to the bedrock depths, adding additional information about the continuity of the bedrock within the basin, and giving a high resolution image of the shallower sediments. Through the tomographic inversion of 3D data we were able to reconstruct a volumetric image of the carbonate formation at the study site. Finally, the tomographic models have been validated through the inversion of a synthetic dataset, with the aim to attain a final model, whose synthetic model is comparable with the field one. The final model, estimated using an iterative procedure that minimises the absolute difference between field and synthetic models, has retrieved a bedrock resistivity one order of magnitude higher than that obtained from field data inversion.

  20. Electrical Resistivity Investigations of the Kurşunlu (Manisa/Turkey) Geothermal Area

    Science.gov (United States)

    Sarı, Coşkun; Timur, Emre

    2016-04-01

    It is of considerable importance to explore the geological structure around active faults, especially near-surface unconsolidated layers, to estimate the faults' activity. There are numerous case studies to investigate geothermal reservoirs and surrounding active faults using geophysical exploration methods; however, only a few cases have been verified in detail by comparison with other geological information. Electrical resistivity data provide a substantial contribution to the geophysical mapping and monitoring of geothermal reservoirs. We applied electrical methods, which can be effective for exploring to several hundred meters depth, to reveal geological structures covered by thick Quaternary alluvium formations. Geothermal activity around city of Manisa in Gediz Graben (Western Turkey) has been investigated by many researchers and many geothermal boreholes were drilled in order to produce electricity and for heating purposes. The Kurşunlu geothermal area is with the southern side of the Gediz Graben in 2 km west of Salihli, Manisa, Turkey. According to rising demand on thermal water around Salihli, geophysical studies were performed using the Vertical Electrical Sounding (VES) measurements at 16 stations around the area of Kurşunlu hot springs, and they were interpreted using both one and two-dimensional modelling. Vertical and horizontal resistivity sections were mapped, and it was determined that two low-resistivity layers exist both in the North (stations 1,2 and 4) and the South (stations 6 and 10) part of the survey area. As a result of the studies, the boundaries of the low-resistivity layer were mapped and test drilling locations were recommended.

  1. [Testing the electric resistance as an objective diagnostic test in dental pulp diseases].

    Science.gov (United States)

    Constantin, I; Severineanu, V; Tudose, N

    1976-01-01

    The authors test by means of a measuring device of high precision the resistence of health or sick human pulpa, comparing it to them of gums, excluding in the same time the sensibility of the patient in question. The authors corroborate the obtained dates with clinical symptomatology and the histopathological photos, discussing the possibility of objective electrical test as an expedient in the diagnosis of pulpa-affections.

  2. Shallow electrical resistivity imaging of the Limón fault, Chagres River Watershed, Panama Canal

    Science.gov (United States)

    Mojica, Alexis; Pérez, Tatiana; Toral, Jaime; Miranda, Roberto; Franceschi, Pastora; Calderón, Carlos; Vergara, Fidedigna

    2017-03-01

    The aim of this study was the use of electrical resistivity imaging to investigate the geometry of the southwest portion of one of the most important geologic fault zones of the Panama Canal Watershed: the Limón fault. This fault is characterized by its juxtaposition of pre-Tertiary andesitic basalt (Playa Venado Formation) against late Oligocene Tertiary sediments (Caimito Formation). In this zone, four 2D electrical resistivity tomography profiles were conducted perpendicular to the fault trace: T-1, T-2, T-3 and T-4. The T-1, T-3, and T-4 profiles were long profiles (235 m for the first two and 215 m for the last one), with a goal of determining the depth of the geologic boundary between the sedimentary and andesitic deposits. The T-2 profile was a short profile (23.5 m), with the objective of calibrating the results with data provided by the paleoseismic trenching previously developed in the area of interest. For these tests, two electrode arrays of types Wenner-Schlumberger and Dipole-Dipole, were used. For the inversion routine, two regularized least-squares methods were used: the smoothness-constrained method and robust inversion. The long electrical resistivity tomography profiles were able to identify a set of electrical anomalies associated with the andesitic basalt and the Tertiary sediments and with that, the contact geometry between these formations. In these profiles, fault angle measurements ranged from 60° to 80° with respect to the ground surface. In the T-2 profile, the electrical anomalies showed a good association with the results of the paleoseismic study. This allowed identification of the colluvium and alluvium covering the gravel and sand debris that mark the gradual transition to the soils of the Caimito Formation. Finally, a set of 2D synthetic models was developed for each of the T-1, T-3, and T-4 profiles with the objective of optimizing interpretation of the field results.

  3. Sinop Province, Şahintepesi Region, Bayraktepe Tumulus' Display With Electrical Resistivity Tomography

    Science.gov (United States)

    Yıldırım, Şahin; Ahmet Yüksel, Fethi; Avcı, Kerim; Ziya Görücü, Mahmut

    2017-04-01

    Paphlagonia is located on the Boztepe Foreland (Sinop Foreland) and its peninsula, which extends northwards along the coastal lane of the Black Sea. Sinop is at the northernmost tip of Turkey, in the middle of the Black Sea region. Archaeological excavations of the entire Sinop province have uncovered artifacts from the Bronze Age dating back to 3000 BC. Most ancient sources indicate that Mithridates is buried in Sinop. It is alleged that the Tumuli on the crest of the historical peninsula, called Boztepe in Sinop, could be the resting spot of Mithridates. There are three tumuli in this area known as Şahin Tepesi Mevkii (Şahin Hill Site). In order to determine the location of the burial chamber of the tomb, Electrical Resistivity Tomography (ERT) measurement methods were used, which is a geophysical method capable of three dimensional (3D) measurement and evaluation. In the area of the tumulus, measurements were made in a 57 electrode array using a 42 x 36 m (total 1512 m2) spread electrode pattern with 6m spacing. In the study, an AGI brand SuperString R1 Resistivity device and equipment were used. Resistivity data were interpreted using AGI Earthimag 3D software. From the geoelectric resistivity data, 2D and 3D images were obtained as a result of data processing. In the tumulus area smooth geometrical forms and individual high-amplitude anomalies were visualized, that could be attributed to structural remains and the presence of archaeological materials. These anomalies were plotted on the gridded location plan of the excavation area. Within the artificial hill forming the tumulus, with regards to the natural geological units, anomalies such as very high resistivity, linear elongations, angular rotations, curves, etc. (stone wall, hollow room) that are caused by architectural elements were observed. These geometrically shaped, very highly resistive, anomalies should be checked. Keywords: Sinope, Tumulus, Electrical Resistivity Tomography, Archaeo-geophysics

  4. Comparison of the effects of electrical stimulation and cold-water immersion on muscle soreness after resistance exercise.

    Science.gov (United States)

    Jajtner, Adam R; Hoffman, Jay R; Gonzalez, Adam M; Worts, Phillip R; Fragala, Maren S; Stout, Jeffrey R

    2015-05-01

    Resistance training is a common form of exercise for competitive and recreational athletes. Enhancing recovery from resistance training may improve the muscle-remodeling processes, stimulating a faster return to peak performance. To examine the effects of 2 different recovery modalities, neuromuscular electrical stimulation (NMES) and cold-water immersion (CWI), on performance and biochemical and ultrasonographic measures. Thirty resistance-trained men (23.1 ± 2.9 y, 175.2 ± 7.1 cm, 82.1 ± 8.4 kg) were randomly assigned to NMES, CWI, or control (CON). All participants completed a high-volume lower-body resistance-training workout on d 1 and returned to the human performance laboratory 24 (24H) and 48 h (48 H) postexercise for follow-up testing. Blood samples were obtained preexercise (PRE) and immediately (IP), 30 min (30 P), 24 h (24H), and 48 h (48 H) post. Subjects were examined for performance changes in the squat exercise (total repetitions and average power per repetition), biomarkers of inflammation, and changes in cross-sectional area and echo intensity (EI) of the rectus femoris (RF) and vastus lateralis muscles. No differences between groups were observed in the number of repetitions (P = .250; power: P = .663). Inferential-based analysis indicated that increases in C-reactive protein concentrations were likely increased by a greater magnitude after CWI compared with CON, while NMES possibly decreased more than CON from IP to 24H. Increases in interleukin-10 concentrations between IP and 30 P were likely greater in CWI than NMES but not different from CON. Inferential-based analysis of RF EI indicated a likely decrease for CWI between IP and 48 H. No other differences between groups were noted in any other muscle-architecture measures. Results indicated that CWI induced greater increases in pro- and anti-inflammatory markers, while decreasing RF EI, suggesting that CWI may be effective in enhancing short-term muscle recovery after high-volume bouts of

  5. Sensitivity of crumb rubber particle sizes on electrical resistance of rubberised concrete

    Directory of Open Access Journals (Sweden)

    Sakdirat Kaewunruen

    2016-12-01

    Full Text Available Railway track components often suffer from high aggressive loading and vibrating conditions of railway environment, causing high maintenance costs due to impact damage, rail seat abrasion and excessive noise and vibration to surrounding equipment. Thus, it is essential to have novel improvement of material capabilities in order to solve or reduce these problems. A nanoengineered improvement method for concrete material using crumb rubber has been recently introduced to railway applications. However, for modern electrified railway tracks, structural materials will need to provide electrical and signal insulation for effective operations of track circuits and electrification. This paper firstly highlights the importance of the particle sizes of crumb rubbers on the electrical resistivity of the concrete modified by crumbed rubbers. It shows that microscale crumb rubbers induce lesser electrical conduction capacity than nanoscale crumb rubber.

  6. High resistance to sulfur poisoning of Ni with copper skin under electric field

    Science.gov (United States)

    Xu, Xiaopei; Zhang, Yanxing; Yang, Zongxian

    2017-02-01

    The effects of sulfur poisoning on the (1 0 0), (1 1 0) and (1 1 1) surfaces of pure Ni and Cu/Ni alloy are studied in consideration of the effect of electric field. The effects of Cu dopants on the S poisoning characteristics are analyzed by the means of the density functional theory results in combination with thermodynamics data using the ab initio atomistic thermodynamic method. When the Cu concentration increases to 50% on the surface layer of the Cu/Ni alloy, the (1 1 0) surface becomes the most vulnerable to the sulfur poisoning. Ni with a copper skin can mostly decrease the sulfur poisoning effect. Especially under the electric field of 1.0 V/Å, the sulfur adsorption and phase transition temperature can be further reduced. We therefore propose that Ni surfaces with copper skin can be very effective to improve the resistance to sulfur poisoning of the Ni anode under high electric field.

  7. A Comparison of Increases in Volume Load Over 8 Weeks of Low-Versus High-Load Resistance Training

    OpenAIRE

    Schoenfeld; Ogborn; Contreras,, J. g.; Cappaert; Silva Ribeiro; Alvar; Vigotsky

    2016-01-01

    Background It has been hypothesized that the ability to increase volume load (VL) via a progressive increase in the magnitude of load for a given exercise within a given repetition range could enhance the adaptive response to resistance training. Objectives The purpose of this study was to compare changes in volume load (VL) over eight weeks of resistance training (RT) in high-versus low-load protocols. ...

  8. Electrical resistance stability of high content carbon fiber reinforced cement composite

    Institute of Scientific and Technical Information of China (English)

    YANG Zai-fu; TANG Zu-quan; LI Zhuo-qiu; QIAN Jue-shi

    2005-01-01

    The influences of curing time, the content of free evaporable water in cement paste, environmental temperature, and alternative heating and cooling on the electrical resistance of high content carbon fiber reinforced cement (CFRC) paste are studied by experiments with specimens of Portland cement 42.5 with 10 mm PAN-based carbon fiber and methylcellulose. Experimental results indicate that the electrical resistance of CFRC increases relatively by 24% within a hydration time of 90 d and almost keeps constant after 14 d, changes hardly with the mass loss of free evaporable water in the concrete dried at 50℃C, increases relatively by 4% when ambient temperature decreases from 15℃ to-20℃, and decreases relatively by 13% with temperature increasing by 88℃. It is suggested that the electric resistance of the CFRC is stable, which is testified by the stable power output obtained by electrifying the CFRC slab with a given voltage. This implies that such kind of high content carbon fiber reinforced cement composite is potentially a desirable electrothermal material for airfield runways and road surfaces deicing.

  9. Annealing effects on the electrical resistivity of AuAl thin films alloys

    Energy Technology Data Exchange (ETDEWEB)

    Maldonado, R.D., E-mail: rubdoming@live.com.mx [Centro de Investigacion y de Estudios Avanzados del IPN Unidad Merida, Depto. de Fisica Aplicada, Km. 6 Antigua Carretera a Progreso 97310, Merida, Yucatan (Mexico); Oliva, A.I.; Corona, J.E. [Centro de Investigacion y de Estudios Avanzados del IPN Unidad Merida, Depto. de Fisica Aplicada, Km. 6 Antigua Carretera a Progreso 97310, Merida, Yucatan (Mexico)

    2009-08-15

    Au/Al bilayer (50-250-nm thickness) thin films were deposited by thermal evaporation on p-type silicon (1 0 0) substrates. The formed Au/Al/Si systems were annealed from room temperature (RT) to 400 deg. C to form AuAl/Si alloys. Two groups of AuAl alloys were analyzed. The first group was prepared as a function of the atomic concentration and the second group was prepared as a function of thickness. The morphology and crystalline structure of the alloys were analyzed by AFM and X-ray diffraction techniques, respectively. The electrical resistivities of the AuAl alloys were measured by the four-probe technique. The first group of thin AuAl alloys presented segregations as a consequence of the annealing treatment and the atomic concentration; meanwhile, the electrical resistivity showed abrupt changes as a consequence of changing the atomic concentration. In the second group a monotonically increment in the grain size was found meanwhile for thickness below 100 nm the electrical resistivity presented important differences as compared with the before annealing process.

  10. Network modelling of wettability and pore geometry effects on electrical resistivity and capillary pressure

    Energy Technology Data Exchange (ETDEWEB)

    Man, H.N.; Jing, X.D. [Centre for Petroleum Studies, T.H. Huxley School, Imperial College of Science, Technology and Medicine, Prince Consort Road, London (United Kingdom)

    1999-12-01

    Recent research efforts have focused on using simple non-circular cross-sectional pore shapes to honour the physics observed at the pore scale. For example, there is evidence to suggest variations of wettability occur at this level. These pores can exhibit water-wet and oil-wet regions, depending on the physics of wetting films, and hence the porous medium maybe of mixed-wettability character. For low water saturations, electrical resistivity cannot be physically simulated at the pore scale using cylindrical tubes, even though wetting film thickness' and pore constrictions are taken into account. A three-dimensional network model that investigates the petrophysical characteristics, electrical resistivity and capillary pressure, is presented. The influence of saturation history is also modelled. Key pore geometrical attributes such as pore shape, aspect ratio, pore coordination number (pore connectivity) and pore size distribution are included in the model. In addition, pore constrictions are introduced which may result in phase trapping via snap-off within the tube itself. Analysis of our developing network model starting from representing the pore shape as circular is presented. Using a simple non-circular cross-sectional pore shape we show bulk water retained in the crevices give rise to predictions that are in close agreement with electrical resistivity and capillary pressure trends observed in experiments. Numerical results are presented and compared with experimental data.

  11. Influence of salinity and moisture content in electrical resistivity tomography readings in geomaterials used in construction

    Science.gov (United States)

    Gomez-Heras, Miguel; Fort, Rafael; Garcia Morales, Soledad

    2014-05-01

    Wetness and salts are among the main agents hindering the performance of any porous building material. There are a number of techniques based on electrical properties for the detection of these agents in buildings, such as portable moisture meters and electric resistivity tomography (ERT). These methods are used to locate wet areas based on the lower electrical resistivity wet materials have in relation to dry ones. However, as both moisture and salts contribute to low resistivity readings, the ERT readings may have a degree of uncertainty. This research aims to study the contribution of salinity and moisture content on the readings of ERT by testing laminated gypsum boards in the laboratory with solutions with different compositions (i.e. sodium chloride, magnesium sulphate and a mixture of both) and concentrations of salts. An industrial product, such as the laminated gypsum board, was chosen to minimize the effects that heterogeneities in composition and physical properties could have in the ERT readings and facilitate the interpretation of the wetness/salt content difference. Gypsum board was soaked with a fixed amount of the chosen solutions and several ERT transects were performed with a GeoTom device (Geolog2000) while drying. Results show the influence salinity of solutions have in drying process, and how the salt content remaining within the pores of geomaterials impact on ERT results. Research funded by Geomateriales (S2009/MAT-16) and CEI Moncloa (UPM, UCM, CSIC) through a PICATA contract and the equipment from RedLAbPAt Network

  12. Electrical Resistivity Investigation of Gas Hydrate Distribution in Mississippi Canyon Block 118, Gulf of Mexico

    Energy Technology Data Exchange (ETDEWEB)

    Dunbar, John

    2012-12-31

    Electrical methods offer a geophysical approach for determining the sub-bottom distribution of hydrate in deep marine environments. Methane hydrate is essentially non-conductive. Hence, sediments containing hydrate are more resistive than sediments without hydrates. To date, the controlled source electromagnetic (CSEM) method has been used in marine hydrates studies. This project evaluated an alternative electrical method, direct current resistivity (DCR), for detecting marine hydrates. DCR involves the injection of direct current between two source electrodes and the simultaneous measurement of the electric potential (voltage) between multiple receiver electrodes. The DCR method provides subsurface information comparable to that produced by the CSEM method, but with less sophisticated instrumentation. Because the receivers are simple electrodes, large numbers can be deployed to achieve higher spatial resolution. In this project a prototype seafloor DCR system was developed and used to conduct a reconnaissance survey at a site of known hydrate occurrence in Mississippi Canyon Block 118. The resulting images of sub-bottom resistivities indicate that high-concentration hydrates at the site occur only in the upper 50 m, where deep-seated faults intersect the seafloor. Overall, there was evidence for much less hydrate at the site than previously thought based on available seismic and CSEM data alone.

  13. A setup for measuring the Seebeck coefficient and the electrical resistivity of bulk thermoelectric materials

    Science.gov (United States)

    Fu, Qiang; Xiong, Yucheng; Zhang, Wenhua; Xu, Dongyan

    2017-09-01

    This paper presents a setup for measuring the Seebeck coefficient and the electrical resistivity of bulk thermoelectric materials. The sample holder was designed to have a compact structure and can be directly mounted in a standard cryostat system for temperature-dependent measurements. For the Seebeck coefficient measurement, a thin bar-shaped sample is mounted bridging two copper bases; and two ceramic heaters are used to generate a temperature gradient along the sample. Two type T thermocouples are used to determine both temperature and voltage differences between two widely separated points on the sample. The thermocouple junction is flattened into a disk and pressed onto the sample surface by using a spring load. The flexible fixation method we adopted not only simplifies the sample mounting process but also prevents thermal contact deterioration due to the mismatch of thermal expansion coefficients between the sample and other parts. With certain modifications, the sample holder can also be used for four-probe electrical resistivity measurements. High temperature measurements are essential for thermoelectric power generation. The experimental system we developed is capable of measuring the Seebeck coefficient and the electrical resistivity of bulk thermoelectric materials in a wide temperature range from 80 to 500 K, which can be further extended to even higher temperatures. Measurements on two standard materials, constantan and nickel, confirmed the accuracy and the reliability of the system.

  14. Spatial filtering of electrical resistivity and slope intensity: Enhancement of spatial estimates of a soil property

    Science.gov (United States)

    Bourennane, Hocine; Hinschberger, Florent; Chartin, Caroline; Salvador-Blanes, Sébastien

    2017-03-01

    To best utilize the electrical resistivity data and slope intensity derived from a Digital Elevation Model, the kriging spatial components technique was applied to separate the nuggets and small- and large-scale structures for both resistivity and slope intensity data. The spatial structures in the resistivity and slope intensity data, which are poorly correlated with soil thickness (ST), are then filtered out prior to integrating the resistivity data and slope intensity into soil thickness estimation over a 12 ha area located in the south-western Parisian Basin (France). ST was measured at 650 locations over the study area by manual augering. Twenty percent of the observations (131 points) were randomly selected to constitute the validation dataset. The remaining 80% of the dataset (519 points) was used as the prediction dataset. The resistivity data represent a set of 7394 measurement points for each of the three investigated depths over the study area. The methodology involves successively (1) a principal component analysis (PCA) on the electrical measurements and (2) a geostatistical filtering of the small-scale component and noise in the first component (PC1) of the PCA. The results show that the correlation between ST and PC1 is greatly improved when the small-scale component and noise are filtered out, and similarly, the correlation between ST and slope intensity is greatly improved once the geostatistical filtering is carried out on the slope data. Thus, the large scales of both slope intensity and the electrical resistivity's PC1 were used as external drifts to predict ST over the entire study area. This prediction was compared with ordinary kriging and kriging either with a large scale of slope intensity or with a large scale of the electrical resistivity's PC1 taken as an external drift. The first prediction of ST by ordinary kriging, which was considered as our reference, was also compared to those achieved by kriging using the raw secondary variables

  15. Lung volumes and airway resistance in patients with a possible restrictive pattern on spirometry.

    Science.gov (United States)

    Schultz, Kenia; D'Aquino, Luiz Carlos; Soares, Maria Raquel; Gimenez, Andrea; Pereira, Carlos Alberto de Castro

    2016-01-01

    Many patients with proportional reductions in FVC and FEV1 on spirometry show no reduction in TLC. The aim of this study was to evaluate the role that measuring lung volumes and airway resistance plays in the correct classification of patients with a possible restrictive pattern on spirometry. This was a prospective study involving adults with reduced FVC and FEV1, as well as an FEV1/FV(C) ratio within the predicted range. Restrictive lung disease (RLD) was characterized by TLC below the 5th percentile, as determined by plethysmography. Obstructive lung disease (OLD) was characterized by high specific airway resistance, significant changes in post-bronchodilator FEV1, or an FEF25-75% espirometria não têm CPT reduzida. O objetivo deste estudo foi avaliar o papel da medida dos volumes pulmonares e da resistência das vias aéreas para a classificação correta de pacientes com possível restrição à espirometria. Estudo prospectivo de adultos com CVF e VEF1 reduzidos e relação VEF1/CV(F) na faixa prevista. Distúrbio ventilatório restritivo (DVR) foi definido por CPT espirometria. A obstrução ao fluxo aéreo é comum nesses casos.

  16. NUMERICAL SIMULATION OF ELECTRICAL IMPEDANCE TOMOGRAPHY PROBLEM AND STUDY OF APPROACH BASED ON FINITE VOLUME METHOD

    Directory of Open Access Journals (Sweden)

    Ye. S. Sherina

    2014-01-01

    Full Text Available This research has been aimed to carry out a study of peculiarities that arise in a numerical simulation of the electrical impedance tomography (EIT problem. Static EIT image reconstruction is sensitive to a measurement noise and approximation error. A special consideration has been given to reducing of the approximation error, which originates from numerical implementation drawbacks. This paper presents in detail two numerical approaches for solving EIT forward problem. The finite volume method (FVM on unstructured triangular mesh is introduced. In order to compare this approach, the finite element (FEM based forward solver was implemented, which has gained the most popularity among researchers. The calculated potential distribution with the assumed initial conductivity distribution has been compared to the analytical solution of a test Neumann boundary problem and to the results of problem simulation by means of ANSYS FLUENT commercial software. Two approaches to linearized EIT image reconstruction are discussed. Reconstruction of the conductivity distribution is an ill-posed problem, typically requiring a large amount of computation and resolved by minimization techniques. The objective function to be minimized is constructed of measured voltage and calculated boundary voltage on the electrodes. A classical modified Newton type iterative method and the stochastic differential evolution method are employed. A software package has been developed for the problem under investigation. Numerical tests were conducted on simulated data. The obtained results could be helpful to researches tackling the hardware and software issues for medical applications of EIT.

  17. Independent Orbiter Assessment (IOA): Assessment of the electrical power distribution and control subsystem, volume 1

    Science.gov (United States)

    Schmeckpeper, K. R.

    1988-01-01

    The results of the Independent Orbiter Assessment (IOA) of the Failure Modes and Effects Analysis (FMEA) and Critical Items List (CIL) are presented. The IOA first completed an analysis of the Electrical Power Distribution and Control (EPD and C) hardware, generating draft failure modes and potential critical items. To preserve independence, this analysis was accomplished without reliance upon the results contained within the NASA FMEA/CIL documentation. The IOA results were then compared to the NASA FMEA/CIL baseline with proposed Post 51-L updates included. A resolution of each discrepancy from the comparison is provided through additional analysis as required. This report documents the results of that comparison for the Orbiter EPD and C hardware. The IOA product for the EPD and C analysis consisted of 1671 failure mode analysis worksheets that resulted in 468 potential critical items being identified. Comparison was made to the proposed NASA Post 51-L baseline which consisted of FMEAs and 158 CIL items. Volume 1 contains the EPD and C subsystem description, analysis results, ground rules and assumptions, and some of the IOA worksheets.

  18. Electrical capacitance volume tomography for measurement soil water infiltration in vessel experiments

    Institute of Scientific and Technical Information of China (English)

    Muhammad Mukhlisin; Marlin Ramadhan Baidillah; Mohd Raihan Taha

    2014-01-01

    Electrical capacitance volume tomography (ECVT) is a recently-developed technique for real-time, non-invasive 3D monitoring of processes involving materials with strong contrasts in dielectric permittivity. This work is first application of the method to visualization of water flow in soil. We describe the principles behind the method, and then demonstrate its use with a simple laboratory infiltration experiment. 32 ECVT sensors were installed on the sides of an empty PVC column. Water was poured into the column at a constant rate, and ECVT data were collected every second. The column was then packed with dry sand and again supplied with water at a constant rate with data collected every second. Data were analyzed to give bulk average water contents, which proved consistent with the water supply rates. Data were also analyzed to give 3D images (216 voxels) allowing visualization of the water distribution during the experiments. Result of this work shows that water infiltration into the soil, wall flow, progress of the unstable wetting front and the final water distribution are clearly visible.

  19. Influence of Different Geometric Representations of the Volume Conductor on Nerve Activation during Electrical Stimulation

    Directory of Open Access Journals (Sweden)

    José Gómez-Tames

    2014-01-01

    Full Text Available Volume conductor models with different geometric representations, such as the parallel layer model (PM, the cylindrical layer model (CM, or the anatomically based model (AM, have been employed during the implementation of bioelectrical models for electrical stimulation (FES. Evaluating their strengths and limitations to predict nerve activation is fundamental to achieve a good trade-off between accuracy and computation time. However, there are no studies aimed at clarifying the following questions. (1 Does the nerve activation differ between CM and PM? (2 How well do CM and PM approximate an AM? (3 What is the effect of the presence of blood vessels and nerve trunk on nerve activation prediction? Therefore, in this study, we addressed these questions by comparing nerve activation between CM, PM, and AM models by FES. The activation threshold was used to evaluate the models under different configurations of superficial electrodes (size and distance, nerve depths, and stimulation sites. Additionally, the influences of the sciatic nerve, femoral artery, and femoral vein were inspected for a human thigh. The results showed that the CM and PM had a high error rate, but the variation of the activation threshold followed the same tendency for electrode size and interelectrode distance variation as AM.

  20. Reorientation dynamics of nematics encapsulated in microscopic volumes in a strong electric field

    Science.gov (United States)

    Zakharov, A. V.; Vakulenko, A. A.; Pasechnik, S. V.

    2016-09-01

    We theoretically describe a new regime of reorientation of the director field widehat n and velocity v of a nematic liquid crystal (LC) encapsulated in a rectangular cell under the action of strong electric field E directed at angle α ( π/2) to the horizontal surfaces bounding the LC cell. The numerical calculations in the framework of nonlinear generalization of the classical Eriksen-Leslie theory showed that at certain relations between the torques and momenta affecting the unit LC volume and E ≫ E th, transition periodic structures can arise during reorientation of widehat n, if the corresponding distortion mode has the fastest response and, thus, suppresses all the rest of the modes, including uniform ones. The position of sites of these periodic structures is affected by the value of field E, angle α, and the character of anchoring of LC molecules to the bounding surfaces. The calculations performed for the nematic formed by 4-n-penthyl-4'-cyanobiphenyl showed that several vortexes can form in an LC cell under the action of reorientation of the nematic field; the boundaries of these vortexes are determined by the positions of periodic structure sites.

  1. Delineating The Subsurface Structures Using Electrical Resistivity Sounding In Some Part Of Willeton Perth Western Australia

    Directory of Open Access Journals (Sweden)

    Okan Evans Onojasun

    2015-08-01

    Full Text Available Abstract Geophysical survey using electrical resistivity methods has been carried out within the industrial area of Willeton Perth Western Australia with the view to delineate the geoelectric characteristics of the basement complex and evaluate the groundwater potential in the area. Vertical electrical sounding with ABEM SAS 3000 Terrameter and Schlumberger electrode configuration were employed for data acquisition. Apparent resistivity values obtained from the field measurements were plotted against half current electrodes spacing on a log-log graph while a model was suggested to fit the resistivity distribution presented in the sounding. The results from the modelling were finally iterated to the lowest Root Mean Square RMS percentage error using computer software A 7 point filter derived by Guptasarma to calculate a forward model. Analysis of the results showed that the study area has fairly homogenous subsurface stratification with four distinct subsurface layers above the depth of 37m. The four subsurface layers comprises top soil mainly of unconsolidated and sand containing organic matter unsaturated sand layer with consolidated and highly resistive water saturated sand layer with highly water saturated soil and the sub-stratum layer consisting of clay material. The aquifer performance is best at about 32m hence it is suggested that boreholes for sustainable water supply in this area should be drilled to about 32 m to hit prolific aquifer.

  2. Monitoring crack development in fiber concrete beam by using electrical resistivity imaging

    Science.gov (United States)

    Wiwattanachang, N.; Giao, P. H.

    2011-10-01

    Accurate detection of damaged concrete zones plays an important role in selecting the proper remedial technique. This study presents results from an application of the electrical imaging method to monitor the development of cracks in fiber concrete beams. The study showed that resistivity measurements on the concrete specimens were able to detect the increase of concrete resistivity with the curing time that reached about 65 Ωm after 28 days of curing. A similar development trend of concrete compressive strength was also found. Two types of cracks were investigated, i.e., artificial cracks made of plastic sheets inserted in concrete and cracks developed during a four-step loading test. A mini-electric imaging survey with Wenner array was conducted on the tension face of the beams. To deal with the effect of the beam size new procedures to correct resistivity measurements before inversion were proposed and successfully applied in this study. The results indicated that both crack direction and depth could be accurately determined in the inverted resistivity sections.

  3. Interpretation of dipole-dipole electrical resistivity survey, Colado geothermal area, Pershing County, Nevada

    Science.gov (United States)

    Mackelprang, C. E.

    1980-09-01

    An electrical resistivity survey in the Colado geothermal area, Pershing County, Nevada has defined areas of low resistivity on each of five lines surveyed. Some of these areas appear to be fault controlled. Thermal fluids encountered in several drill holes support the assumption that the hot fluids may be associated with areas of low resistivity. The evidence of faulting as interpreted from modeling of the observed resistivity data is therefore particularly significant since these structures may be the conduits for the thermal fluids. Sub-alluvial fault zones are interpreted to occur between stations 0-5 NW on Line D and on Line A between stations 4 NW and 4 SE. Fault zones are also interpreted on Line C near stations 1 NW, 1 SE, and 3 SE, and on Line E between stations 2-4 NW and near 1 SE. No faulting is evident under the alluvial cover on the southwest end of Line B. A deep conductive zone is noted within the mountain range on two resistivity lines. There is no definite indication that thermal fluids are associated with this resistivity feature.

  4. Application of 2D electrical resistivity tomography to engineering projects: Three case studies

    Directory of Open Access Journals (Sweden)

    Rungroj Arjwech

    2015-12-01

    Full Text Available Electrical resistivity tomography (ERT is a non-invasive geophysical method of primary interest for addressing subsurface engineering problems. The method is based on the assumption that subsurface geological materials have significant resistivity contrasts that can be identified based on measurements on the surface. This paper presents three different case studies that have been carried out at different sites. The first case study visualizes the contrast between high resistivity zones of hard bedrocks and low resistivity zones of weathered rocks. Similar to the first case study, the second case study shows high resistivity contrasts that clearly distinguishes the shape of a footing located within the surrounding materials. The third case study shows no clear low resistivity zone that can be identified as a leaking zone. The 2D ERT survey method used in these three investigations has been shown to be useful as a cost-effective and rapid method to obtain wide area subsurface information that is relevant for subsurface engineering problems.

  5. Imaging Rainfall Infiltration Processes with the Time-Lapse Electrical Resistivity Imaging Method

    Science.gov (United States)

    Zhang, Gang; Zhang, Gui-Bin; Chen, Chien-chih; Chang, Ping-Yu; Wang, Tzu-Pin; Yen, Horng-Yuan; Dong, Jia-Jyun; Ni, Chuen-Fa; Chen, Su-Chin; Chen, Chao-Wei; Jia, Zheng-yuan

    2016-06-01

    Electrical Resistivity Imaging (ERI) was carried out continuously for 10 days to map the subsurface resistivity distribution along a potentially hazardous hillslope at the Jieshou Junior High School in Taoyuan, Taiwan. The reliability of the inverted resistivity structures down to about 25 m depth was examined with synthetic modeling using the same electrode arrangements installed on land surface as in field surveys, together with a DOI (depth-of-investigation) index calculated from the ERI data. The subsurface resistivity distribution is consistent with results from well logging. These ERI recordings were taken daily and provided highly resolved imagery of the resistivity distribution underground and illustrated the dynamical fluid-flow behavior due to heavy rainfall infiltration. Using Archie's law, the resistivity distribution was transformed into a map of relative water saturation (RWS), which is strongly correlated with the rainfall infiltration process. We then found that the averaged RWS is significantly correlated with daily precipitation. Our observations indicate that time-lapse ERI is effective in monitoring subterraneous rainfall infiltration; moreover, the preferential flow paths can be delineated according to the changes in averaged RWS derived from the ERI data.

  6. Test facility for simultaneous measurement of electrical and thermal contact resistance

    Science.gov (United States)

    Misra, Prashant; Nagaraju, J.

    2004-08-01

    A test setup has been developed for simultaneously evaluating the electrical contact resistance (ECR) and thermal contact resistance/conductance (TCR/TCC) across meta-metal contacts at different contact pressures and mean interface temperatures. ECR and TCC across brass-brass contacts in vacuum have been measured simultaneously at different contact pressures and mean interface temperatures. The results obtained are found to be in agreement with the theoretical models available in the literature for ECR and TCC, independently from each other. The maximum absolute uncertainties in the measurement of ECR and TCC with the present setup are estimated to be ±0.003% and ±4.4%, respectively. Apart from contact resistance measurements, the setup is also used to determine thermal conductivity of unknown materials viz., oxygen-free high-conductivity copper and brass, at different temperatures.

  7. Preparation and Properties of High Hardness and Oxidation Resisting Coating Using Electric Arc Spray

    Institute of Scientific and Technical Information of China (English)

    LIZhuo-xin; CUILi; WANGJiang-ping; TANGChun-tian

    2004-01-01

    A coating with high hardness, wear and oxidation resistance was prepared by electric arc spray. The hardness, bonding strength, abrasive wear and values of porosity and oxidation resistance of the coating were investigated. The microstructures and function of Cr3C2 of the coating were analyzed. The results showed surface Rockness Hardness HR30 reached 72.5 and average bond strength reached 49.1Mpa. Also porosity value was less than 2%. In addition, it was found from the comparison between the coating and 45CT coating that, oxidation resistance of the coating was less than that of 45CT, but the abrasive wear of the coating was obvious better than that of 45CT.

  8. Preparation and Properties of High Hardness and Oxidation Resisting Coating Using Electric Arc Spray

    Institute of Scientific and Technical Information of China (English)

    LI Zhuo-xin; CUI Li; WANG Jiang-ping; TANG Chun-tian

    2004-01-01

    A coating with high hardness, wear and oxidation resistance was prepared by electric arc spray. The hardness,bonding strength, abrasive wear and values of porosity and oxidation resistance of the coating were investigated. The microstructures and function of Cr3C2 of the coating were analyzed. The results showed surface Rockness Hardness HR30 reached 72.5 and average bond strength reached 49.1Mpa. Also porosity value was less than 2%. In addition, it was found from the comparison between the coating and 45CT coating that, oxidation resistance of the coating was less than that of 45CT, but the abrasive wear of the coating was obvious better than that of 45CT.

  9. Probabilistic inversion of electrical resistivity data from bench-scale experiments: On model parameterization for CO2 sequestration monitoring

    Science.gov (United States)

    Breen, S. J.; Lochbuehler, T.; Detwiler, R. L.; Linde, N.

    2013-12-01

    Electrical resistivity tomography (ERT) is a well-established method for geophysical characterization and has shown potential for monitoring geologic CO2 sequestration, due to its sensitivity to electrical resistivity contrasts generated by liquid/gas saturation variability. In contrast to deterministic ERT inversion approaches, probabilistic inversion provides not only a single saturation model but a full posterior probability density function for each model parameter. Furthermore, the uncertainty inherent in the underlying petrophysics (e.g., Archie's Law) can be incorporated in a straightforward manner. In this study, the data are from bench-scale ERT experiments conducted during gas injection into a quasi-2D (1 cm thick), translucent, brine-saturated sand chamber with a packing that mimics a simple anticlinal geological reservoir. We estimate saturation fields by Markov chain Monte Carlo sampling with the MT-DREAM(ZS) algorithm and compare them quantitatively to independent saturation measurements from a light transmission technique, as well as results from deterministic inversions. Different model parameterizations are evaluated in terms of the recovered saturation fields and petrophysical parameters. The saturation field is parameterized (1) in cartesian coordinates, (2) by means of its discrete cosine transform coefficients, and (3) by fixed saturation values and gradients in structural elements defined by a gaussian bell of arbitrary shape and location. Synthetic tests reveal that a priori knowledge about the expected geologic structures (as in parameterization (3)) markedly improves the parameter estimates. The number of degrees of freedom thus strongly affects the inversion results. In an additional step, we explore the effects of assuming that the total volume of injected gas is known a priori and that no gas has migrated away from the monitored region.

  10. Resistance exercise with different volumes: blood pressure response and forearm blood flow in the hypertensive elderly

    Directory of Open Access Journals (Sweden)

    Brito AF

    2014-12-01

    Full Text Available Aline de Freitas Brito,1 Caio Victor Coutinho de Oliveira,2 Maria do Socorro Brasileiro-Santos,1 Amilton da Cruz Santos1 1Physical Education Department, 2Research Laboratory for Physical Training Applied to Performance and Health, Federal University of Paraíba, João Pessoa, Brazil Background: The purpose of this study was to evaluate the effect of two sessions of resistance exercise with different volumes on post-exercise hypotension, forearm blood flow, and forearm vascular resistance in hypertensive elderly subjects.Methods: The study was conducted with ten hypertensive elderly (65±3 years, 28.7±3 kg/m2 subjected to three experimental sessions, ie, a control session, exercise with a set (S1, and exercise with three sets (S3. For each session, the subjects were evaluated before and after intervention. In the pre-intervention period, blood pressure, forearm blood flow, and forearm vascular resistance were measured after 10 minutes of rest in the supine position. Thereafter, the subjects were taken to the gym to perform their exercise sessions or remained at rest during the same time period. Both S1 and S3 comprised a set of ten repetitions of ten exercises, with an interval of 90 seconds between exercises. Subsequently, the measurements were again performed at 10, 30, 50, 70, and 90 minutes of recovery (post-intervention in the supine position.Results: Post-exercise hypotension was greater in S3 than in S1 (systolic blood pressure, −26.5±4.2 mmHg versus −17.9±4.7 mmHg; diastolic blood pressure, −13.8±4.9 mmHg versus −7.7±5 mmHg, P<0.05. Similarly, forearm blood flow and forearm vascular resistance changed significantly in both sessions with an increase and decrease, respectively, that was more evident in S3 than in S1 (P<0.05.Conclusion: Resistance exercises with higher volume were more effective in causing post-exercise hypotension, being accompanied by an increase in forearm blood flow and a reduction of forearm vascular

  11. Effects of load-volume on EPOC after acute bouts of resistance training in resistance-trained men.

    Science.gov (United States)

    Abboud, George J; Greer, Beau K; Campbell, Sara C; Panton, Lynn B

    2013-07-01

    Recent investigations have shown excess postexercise oxygen consumption (EPOC) to be elevated for up to 48 hours in both untrained and trained subjects after resistance training (RT). The purpose of this study was to investigate the effect of load-volume on EPOC. Eight trained men (aged 22 ± 3 years) participated in 2 randomized RT bouts separated by at least 1 week with total load-volumes of 10,000 and 20,000 kg, respectively. Intensity of RT (85% 1 repetition maximum) did not differ between trials. Exercise energy expenditure and resting metabolic rate (RMR) were measured by indirect calorimetry at 8.5 hours before, 1.5 hours before, and during RT bouts and 12, 24, 36, and 48 hours after exercise. Creatine kinase (CK) was measured before and after RT, and 12, 24, 36, and 48 hours postexercise; ratings of perceived muscle soreness were measured on a similar time course save the immediate postexercise time point. Analysis of variance with repeated measures was used to analyze dependent variables. During the 20,000 kg trial, subjects expended significantly (p EPOC above baseline RMR.

  12. Resistance exercise with different volumes: blood pressure response and forearm blood flow in the hypertensive elderly.

    Science.gov (United States)

    Brito, Aline de Freitas; de Oliveira, Caio Victor Coutinho; Brasileiro-Santos, Maria do Socorro; Santos, Amilton da Cruz

    2014-01-01

    The purpose of this study was to evaluate the effect of two sessions of resistance exercise with different volumes on post-exercise hypotension, forearm blood flow, and forearm vascular resistance in hypertensive elderly subjects. The study was conducted with ten hypertensive elderly (65±3 years, 28.7±3 kg/m(2)) subjected to three experimental sessions, ie, a control session, exercise with a set (S1), and exercise with three sets (S3). For each session, the subjects were evaluated before and after intervention. In the pre-intervention period, blood pressure, forearm blood flow, and forearm vascular resistance were measured after 10 minutes of rest in the supine position. Thereafter, the subjects were taken to the gym to perform their exercise sessions or remained at rest during the same time period. Both S1 and S3 comprised a set of ten repetitions of ten exercises, with an interval of 90 seconds between exercises. Subsequently, the measurements were again performed at 10, 30, 50, 70, and 90 minutes of recovery (post-intervention) in the supine position. Post-exercise hypotension was greater in S3 than in S1 (systolic blood pressure, -26.5±4.2 mmHg versus -17.9±4.7 mmHg; diastolic blood pressure, -13.8±4.9 mmHg versus -7.7±5 mmHg, Pexercises with higher volume were more effective in causing post-exercise hypotension, being accompanied by an increase in forearm blood flow and a reduction of forearm vascular resistance.

  13. Evaluation of Cementation of the Loma Blanca Fault Zone Utilizing Electrical Resistivity

    Science.gov (United States)

    Barnes, H.; Spinelli, G. A.; Mozley, P.; Hinojosa, J. R.

    2016-12-01

    Fault-zones are an important control on fluid flow, affecting groundwater supply, hydrocarbon/contaminant migration, and waste/carbon storage. However, current models of fault seal are inadequate, primarily focusing on juxtaposition and entrainment effects, despite the recognition that fault-zone cementation is common and can dramatically reduce permeability. We map cementation patterns of the variably cemented Loma Blanca fault from the land surface to 40 m depth, using electrical resistivity and induced polarization (IP) data from 7 parallel two-dimensional transects running orthogonal to the strike of the fault and 4 three-dimensional grids centered on exposures of the fault at the land surface. Inversions of the 3-D resistivity surveys indicate a low resistivity anomaly in the cemented portions of the fault and within the adjacent footwall; these anomalies are present in the unsaturated zone. This low resistivity signature may be an indication of a higher degree of fluid saturation resulting from greater capillary forces, both in the cemented fault (due to reduced pore sizes within the cemented material) and in the footwall (possibly due to smaller grain size). These mechanisms for generating low resistivity anomalies in both the cemented fault zone and in the footwall, suggest that the low resistivity anomalies likely correspond to regions with low permeability. In areas where no cement is exposed at the surface, we use the low resistivity signature to determine the extent of cementation at depth. The ability to characterize spatial variations in the degree of fault zone cementation with resistivity and IP has exciting implications for improving predictive models of the hydrogeologic impacts of cementation within faults.

  14. The `L' Array, a method to model 3D Electrical Resistivity Tomography (ERT) data

    Science.gov (United States)

    Chavez Segura, R. E.; Chavez-Hernandez, G.; Delgado, C.; Tejero-Andrade, A.

    2010-12-01

    The electrical resistivity tomography (ERT) is a method designed to calculate the distribution of apparent electrical resistivities in the subsoil by means of a great number of observations with the aim of determining an electrical image displaying the distribution of true resistivities in the subsoil. Such process can be carried out to define 2D or 3D models of the subsurface. For a 3D ERT, usually, the electrodes are placed in a squared grid keeping the distance between adjacent electrodes constant in the x and y directions. Another design employed, consists of a series of parallel lines whose space inter-lines must be smaller or equal to four times the electrode separation. The most common electrode arrays frequently employed for this type of studies are the pole-pole, pole-dipole and dipole-dipole. Unfortunately, ERT surface sampling schemes are limited by physical conditions or obstacles, like buildings, highly populated urban zones, and geologic/topographic features, where the lines of electrodes cannot be set. However, it is always necessary to characterize the subsoil beneath such anthropogenic or natural features. The ‘L’ shaped array has the main purpose to overcome such difficulties by surrounding the study area with a square of electrode lines. The measurements are obtained by switching automatically current and potential electrodes from one line to the other. Each observation adds a level of information, from one profile to the other. Once the total levels of data are completed, the opposite ‘L’ array can be measured following the same process. The complete square is computed after the parallel profiles are observed as well. At the end, the computed resistivities are combined to form a 3D matrix of observations. Such set of data can be inverted to obtain the true resistivity distribution at depth in the form of a working cube, which can be interpreted. The method was tested with theoretical models, which included a set of two resistive cubes

  15. Electrical Resistance Measurement of Glass Transition and Crystallization Characteristics of Zr-Al-Cu-Ni Metallic Glasses

    Institute of Scientific and Technical Information of China (English)

    2002-01-01

    In this paper, glass transition and thermal stability of the Zr-Al-Cu-Ni metallic glasses were investigated by using electrical resistance measurement (ERM), DSC and X-ray diffraction techniques. The experimental results show that the ERM is capable of detecting the glass transition of the amorphous alloys and can help to distinguish the crystallization products of the Zr-Al-Cu-Ni metallic glasses owing to the difference of the electrical resistivity between the precipitation phases.

  16. Emissions of greenhouse gases from the use of transportation fuels and electricity. Volume 2: Appendixes A--S

    Energy Technology Data Exchange (ETDEWEB)

    DeLuchi, M.A. [Argonne National Lab., IL (United States)]|[Univ. of California, Davis, CA (United States). Inst. of Transportation Studies

    1993-11-01

    This volume contains the appendices to the report on Emission of Greenhouse Gases from the Use of Transportation Fuels and Electricity. Emissions of methane, nitrous oxide, carbon monoxide, and other greenhouse gases are discussed. Sources of emission including vehicles, natural gas operations, oil production, coal mines, and power plants are covered. The various energy industries are examined in terms of greenhouse gas production and emissions. Those industries include electricity generation, transport of goods via trains, trucks, ships and pipelines, coal, natural gas and natural gas liquids, petroleum, nuclear energy, and biofuels.

  17. Electrical Capacitance Volume Tomography for the Packed Bed Reactor ISS Flight Experiment

    Science.gov (United States)

    Marashdeh, Qussai; Motil, Brian; Wang, Aining; Liang-Shih, Fan

    2013-01-01

    Fixed packed bed reactors are compact, require minimum power and maintenance to operate, and are highly reliable. These features make this technology a highly desirable unit operation for long duration life support systems in space. NASA is developing an ISS experiment to address this technology with particular focus on water reclamation and air revitalization. Earlier research and development efforts funded by NASA have resulted in two hydrodynamic models which require validation with appropriate instrumentation in an extended microgravity environment. To validate these models, the instantaneous distribution of the gas and liquid phases must be measured.Electrical Capacitance Volume Tomography (ECVT) is a non-invasive imaging technology recently developed for multi-phase flow applications. It is based on distributing flexible capacitance plates on the peripheral of a flow column and collecting real-time measurements of inter-electrode capacitances. Capacitance measurements here are directly related to dielectric constant distribution, a physical property that is also related to material distribution in the imaging domain. Reconstruction algorithms are employed to map volume images of dielectric distribution in the imaging domain, which is in turn related to phase distribution. ECVT is suitable for imaging interacting materials of different dielectric constants, typical in multi-phase flow systems. ECVT is being used extensively for measuring flow variables in various gas-liquid and gas-solid flow systems. Recent application of ECVT include flows in risers and exit regions of circulating fluidized beds, gas-liquid and gas-solid bubble columns, trickle beds, and slurry bubble columns. ECVT is also used to validate flow models and CFD simulations. The technology is uniquely qualified for imaging phase concentrations in packed bed reactors for the ISS flight experiments as it exhibits favorable features of compact size, low profile sensors, high imaging speed, and

  18. A Method for Measuring the Volume of Transdermally Extracted Interstitial Fluid by a Three-Electrode Skin Resistance Sensor

    Directory of Open Access Journals (Sweden)

    Dachao Li

    2014-04-01

    Full Text Available It is difficult to accurately measure the volume of transdermally extracted interstitial fluid (ISF, which is important for improving blood glucose prediction accuracy. Skin resistance, which is a good indicator of skin permeability, can be used to determine the volume of extracted ISF. However, it is a challenge to realize in vivo longitudinal skin resistance measurements of microareas. In this study, a three-electrode sensor was presented for measuring single-point skin resistance in vivo, and a method for determining the volume of transdermally extracted ISF using this sensor was proposed. Skin resistance was measured under static and dynamic conditions. The correlation between the skin resistance and the permeation rate of transdermally extracted ISF was proven. The volume of transdermally extracted ISF was determined using skin resistance. Factors affecting the volume prediction accuracy of transdermally extracted ISF were discussed. This method is expected to improve the accuracy of blood glucose prediction, and is of great significance for the clinical application of minimally invasive blood glucose measurement.

  19. 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.

  20. Four-point probe electrical resistivity scanning system for large area conductivity and activation energy mapping.

    Science.gov (United States)

    Shimanovich, Klimentiy; Bouhadana, Yaniv; Keller, David A; Rühle, Sven; Anderson, Assaf Y; Zaban, Arie

    2014-05-01

    The electrical properties of metal oxides play a crucial role in the development of new photovoltaic (PV) systems. Here we demonstrate a general approach for the determination and analysis of these properties in thin films of new metal oxide based PV materials. A high throughput electrical scanning system, which facilitates temperature dependent measurements at different atmospheres for highly resistive samples, was designed and constructed. The instrument is capable of determining conductivity and activation energy values for relatively large sample areas, of about 72 × 72 mm(2), with the implementation of geometrical correction factors. The efficiency of our scanning system was tested using two different samples of CuO and commercially available Fluorine doped tin oxide coated glass substrates. Our high throughput tool was able to identify the electrical properties of both resistive metal oxide thin film samples with high precision and accuracy. The scanning system enabled us to gain insight into transport mechanisms with novel compositions and to use those insights to make smart choices when choosing materials for our multilayer thin film all oxide photovoltaic cells.

  1. Stable hole doping of graphene for low electrical resistance and high optical transparency

    Energy Technology Data Exchange (ETDEWEB)

    Tongay, S; Berke, K; Nasrollahi, Z; Tanner, D B; Hebard, A F [Department of Physics, University of Florida, Gainesville, FL 32611 (United States); Lemaitre, M; Appleton, B R, E-mail: tongay@phys.ufl.edu, E-mail: afh@phys.ufl.edu, E-mail: appleton@eng.ufl.edu [Department of Material Science and Engineering, University of Florida, Gainesville, FL 32611 (United States)

    2011-10-21

    We report on the p doping of graphene with the polymer TFSA ((CF{sub 3}SO{sub 2}){sub 2}NH). Modification of graphene with TFSA decreases the graphene sheet resistance by 70%. Through such modification, we report sheet resistance values as low as 129 {Omega}, thus attaining values comparable to those of indium-tin oxide (ITO), while displaying superior environmental stability and preserving electrical properties over extended time scales. Electrical transport measurements reveal that, after doping, the carrier density of holes increases, consistent with the acceptor nature of TFSA, and the mobility decreases due to enhanced short-range scattering. The Drude formula predicts that competition between these two effects yields an overall increase in conductivity. We confirm changes in the carrier density and Fermi level of graphene through changes in the Raman G and 2D peak positions. Doped graphene samples display high transmittance in the visible and near-infrared spectrum, preserving graphene's optical properties without any significant reduction in transparency, and are therefore superior to ITO films in the near infrared. The presented results allow integration of doped graphene sheets into optoelectronics, solar cells, and thermoelectric solar cells as well as engineering of the electrical characteristics of various devices by tuning the Fermi level of graphene.

  2. Electrical limit of silver nanowire electrodes: Direct measurement of the nanowire junction resistance

    KAUST Repository

    Selzer, Franz

    2016-04-19

    We measure basic network parameters of silvernanowire (AgNW) networks commonly used as transparent conductingelectrodes in organic optoelectronic devices. By means of four point probing with nanoprobes, the wire-to-wire junction resistance and the resistance of single nanowires are measured. The resistanceRNW of a single nanowire shows a value of RNW=(4.96±0.18) Ω/μm. The junction resistanceRJ differs for annealed and non-annealed NW networks, exhibiting values of RJ=(25.2±1.9) Ω (annealed) and RJ=(529±239) Ω (non-annealed), respectively. Our simulation achieves a good agreement between the measured network parameters and the sheet resistanceRS of the entire network. Extrapolating RJ to zero, our study show that we are close to the electrical limit of the conductivity of our AgNW system: We obtain a possible RS reduction by only ≈20% (common RS≈10 Ω/sq). Therefore, we expect further performance improvements in AgNW systems mainly by increasing NW length or by utilizing novel network geometries.

  3. Evaluation of the Mechanical Properties of Gray Cast Iron Using Electrical Resistivity Measurement

    Directory of Open Access Journals (Sweden)

    Bieroński M.

    2016-12-01

    Full Text Available In this paper an attempt to determine the relationship between the electrical resistivity and the tensile strength and hardness of cast iron of carbon equivalent in the range from 3.93% to 4.48%. Tests were performed on the gray cast iron for 12 different melts with different chemical composition. From one melt poured 6 samples. Based on the study of mechanical and electro-resistive determined variation characteristics of tensile strength, hardness and resistivity as a function of the carbon equivalent. Then, regression equations were developed as power functions describing the relationship between the resistivity of castings and their tensile strength and hardness. It was found a high level of regression equations to measuring points, particularly with regard to the relationship Rm=f(ρ. The obtained preliminary results indicate the possibility of application of the method of the resistance to rapid diagnostic casts on the production line, when we are dealing with repeatable production, in this case non variable geometry of the product for which it has been determinated before a regression equation.

  4. Space vehicle electrical power processing distribution and control study. Volume 1: Summary

    Science.gov (United States)

    Krausz, A.

    1972-01-01

    A concept for the processing, distribution, and control of electric power for manned space vehicles and future aircraft is presented. Emphasis is placed on the requirements of the space station and space shuttle configurations. The systems involved are referred to as the processing distribution and control system (PDCS), electrical power system (EPS), and electric power generation system (EPGS).

  5. Column flotation monitoring based on electrical capacitance volume tomography: A preliminary study

    Science.gov (United States)

    Haryono, Didied; Harjanto, Sri; Nugraha, Harisma; Huda, Mahfudz Al; Taruno, Warsito Purwo

    2017-01-01

    A preliminary study of column flotation monitoring process using electrical capacitance volume tomography (ECVT) was conducted. ECVT was one of the monitoring systems which based on the capacitance measurement. It was used to understand the phenomenon that occurs inside the column in a three-dimensional (3-D) image. A linear back projection (LBP) algorithm technique was used to reconstruct the 3-D ECVT images from all measurement data obtained in this study. As a preliminary study, the effect of gas injection in the two-phase (liquid and gas) system was conducted. This study is conducted to assess the possibility of ECVT system in the monitoring of column flotation process. The experiments were conducted by using column flotation with 5 cm diameter and 150 cm height in which a sparger was installed at the bottom of column to inject air inside the column. 32-CH rectangular ECVT sensor was installed at 13 cm above the sparger and placed around the column. The gas injection variations used were 2-7 l/min with interval 1 l/min and all experiments were conducted at room temperature. Based on the signal and image analysis, the signals and 3-D ECVT images showed differences when the gas injection was varied. An increase in gas injection will decrease the fluctuation of signal intensity which correlates to the 3-D ECVT images. Average signals obtained by ECVT when given gas injection variations were in the range of 440.09 to 453.62 mV from high to low gas injection. Based on these results, ECVT has a prospect as an imaging tool to monitor the column flotation process. And also, hopefully, based on the analysis of 3-D images generated by ECVT system, the metallurgical performance would be analyzed in the further researches.

  6. Changes in perceived recovery status scale following high-volume muscle damaging resistance exercise.

    Science.gov (United States)

    Sikorski, Eric M; Wilson, Jacob M; Lowery, Ryan P; Joy, Jordan M; Laurent, C Matthew; Wilson, Stephanie M-C; Hesson, Domini; Naimo, Marshall A; Averbuch, Brian; Gilchrist, Phil

    2013-08-01

    Currently no research has investigated the relationship between muscle damage, hormonal status, and perceived recovery scale (PRS). Therefore, the purpose of this study was to determine the effects of a high-volume training session on PRS and to determine the relationship between levels of testosterone, cortisol, and creatine kinase (CK) and PRS. Thirty-five trained subjects (21.3 ± 1.9 years) were recruited. All subjects participated in a high-volume resistance training session consisting of 3 sets of full squats, bench press, deadlifts, pullups, dips, bent over rows, shoulder press, and barbell curls and extensions. Pre-PRS and post-PRS measurements (0-10), soreness, CK, cortisol, and testosterone were measured before and 48 hours after training. Perceived recovery scale declined from 8.6 ± 2.3 to 4.2 ± 1.85 (p Creatine kinase significantly increased from pre- to postworkout (189.4 ± 100.2 to 512 ± 222.7 U/L). Cortisol, testosterone, and free testosterone did not change. There was an inverse relationship between CK and PRS (r = 0.58, p resistance exercise lowers PRS scores. These changes are partly explained by a rise in serum indices of muscle damage. Moreover, free testosterone seems to have a positive relationship with PRS.

  7. Temperature and volumetric water content petrophysical relationships in municipal solid waste for the interpretation of bulk electrical resistivity data

    Science.gov (United States)

    Pilawski, Tamara; Dumont, Gaël; Nguyen, Frédéric

    2015-04-01

    Landfills pose major environmental issues including long-term methane emissions, and local pollution of soil and aquifers but can also be seen as potential energy resources and mining opportunities. Water content in landfills determine whether solid fractions can be separated and recycled, and controls the existence and efficiency of natural or enhanced biodegradation. Geophysical techniques, such as electrical and electromagnetic methods have proven successful in the detection and qualitative investigation of sanitary landfills. However, their interpretation in terms of quantitative water content estimates makes it more challenging due to the influence of parameters such as temperature, compaction, waste composition or pore fluid. To improve the confidence given to bulk electrical resistivity data and to their interpretation, we established temperature and volumetric water content petrophysical relationships that we tested on field and laboratory electrical resistivity measurements. We carried out two laboratory experiments on leachates and waste samples from a landfill located in Mont-Saint-Guibert, Belgium. We determined a first relationship between temperature and electrical resistivity with pure and diluted leachates by progressively increasing the temperature from 5°C to 65°C, and then cooling down to 5°C. The second relationship was obtained by measuring electrical resistivity on waste samples of different volumetric water contents. First, we used the correlations obtained from the experiments to compare electrical resistivity measurements performed in a landfill borehole and on reworked waste samples excavated at different depths. Electrical resistivities were measured every 20cm with an electromagnetic logging device (EM39) while a temperature profile was acquired with optic fibres. Waste samples were excavated every 2m in the same borehole. We filled experimental columns with these samples and measured electrical resistivities at laboratory temperature

  8. Electrical resistivity of NiFe2O4 ceramic and NiFe2O4 based cermets

    Institute of Scientific and Technical Information of China (English)

    田忠良; 赖延清; 李劼; 张刚; 刘业翔

    2004-01-01

    NiFe2O4 ceramic and NiFe2O4 based cermets, expected to be used as the inert anodes in aluminum electrolysis, were prepared and their electrical resistivities were measured at different temperatures. The effects of temperature and composition on their electrical resistivities were investigated. The results indicate that the electrical resistivities of NiFe2O4 based cermets mainly depend on temperature, resistivity of ceramic matrix, composition and dispersion of the metal phase among ceramic matrix. The electrical resistivity of NiFe2O4 ceramic decreases from 10. 094 Ω · cm to 0. 475 Ω · em with increasing temperature from 573 K to 1 233 K. The electrical resistivities of NiFe2O4 based cermets are greatly lowered, but decrease with increasing the temperature with similar trend compared to that of NiFe2O4 ceramic. The resistivities of NiFe2O4 based cermets containing 5 % Ni, 5 % Cu and 5 % CuNi alloy are 0. 046 8, 0.066 8 and 0. 0532 Ω · cm at 1 233 K, respectively, which are all acceptable as inert anode materials compared to that of the current carbon anode used for aluminum electrolysis.

  9. 树脂基体对导电胶体积电阻率的影响%Effect of resin matrix on volume resistivity of conductive adhesive

    Institute of Scientific and Technical Information of China (English)

    银锐明; 王刘功; 杨华荣; 刘飘; 侯清麟; 李静; 陈琳璋

    2013-01-01

    Taking epoxy resin and Aradur9506 as curing agent and flake silver powders, electrical conductive adhesives were prepared. The effects of the functional groups of epoxy resin and the addition of curing agent in isothermal cure on the resistivity of the ECA were investigated by FT-IR method, scanning electron microscopy(SEM)and other means. The results show that the volume resistivity decreases with the increase of the number of epoxy functional groups, and the biggest volume resistivity is 1.299×10-4 Ω·cm when four functional groups of the epoxy resin are chosen.The volume resistivity firstly decreases and then increases with the increase of curing agent, and reaches the lowest resistivity of 3.112×10-4 Ω·cm when the mass ratio of epoxy resin and curing agent is 25:5. The volume resistivity is proportional with the curing shrinkage.The higher the shrinkage of the matrix curing, the lower the resistivity.%以环氧树脂、胺类固化剂Aradur9506和片状银粉为原料制配导电胶,通过红外光谱(FT-IR)、扫描电镜(SEM)等方法进行测试,研究等温固化过程中环氧树脂的官能团数量以及固化剂添加量对导电胶体积电阻率的影响,并探讨其影响机理.研究结果表明:随着环氧树脂官能团数目的增加,体积电阻率逐渐降低,其中四官能团的环氧树脂时体积电阻率最低,为1.299×10-4Ω·cm;随着固化剂质量的增加,体积电阻率呈现先下降后上升的趋势,当环氧树脂与固化剂质量比为25∶5时,体积电阻率最低,为3.112×10-4 Ω·cm;体积电阻率与树脂基体的固化收缩率呈反比例关系,固化收缩率越大,体积电阻率越低.

  10. Use of body plethysmography to measure effect of bimaxillary orthognathic surgery on airway resistance and lung volumes.

    Science.gov (United States)

    Rezaeetalab, Fariba; Kazemian, Mozhgan; Vaezi, Touraj; Shaban, Barratollah

    2015-12-01

    Bimaxillary orthognathic surgery can cause changes to respiration and the airways. We used body plethysmography to evaluate its effect on airway resistance and lung volumes in 20 patients with class III malocclusions (8 men and 12 women, aged 17 - 32 years). Lung volumes (forced vital capacity; forced inspiratory volume/one second; forced expiratory volume/one second: forced vital capacity; peak expiratory flow; maximum expiratory flow 25-75; maximum inspiratory flow; total lung capacity; residual volume; residual volume:total lung capacity), and airway resistance were evaluated one week before, and six months after, operation. Bimaxillary operations to correct class III malocclusions significantly increased airway resistance, residual volume, total lung capacity, and residual volume:total lung capacity. Other variables also changed after operation but not significantly so. Orthognathic operations should be done with caution in patients who have pre-existing respiratory diseases. Copyright © 2015 The British Association of Oral and Maxillofacial Surgeons. Published by Elsevier Ltd. All rights reserved.

  11. Time-Lapse Electrical Resistivity Investigations for Imaging the Grouting Injection in Shallow Subsurface Cavities

    Directory of Open Access Journals (Sweden)

    Muhammad Farooq

    2014-01-01

    Full Text Available The highway of Yongweol-ri, Muan-gun, south-western part of the South Korean Peninsula, is underlain by the abandoned of subsurface cavities, which were discovered in 2005. These cavities lie at shallow depths with the range of 5∼15 meters below the ground surface. Numerous subsidence events have repeatedly occurred in the past few years, damaging infrastructure and highway. As a result of continuing subsidence issues, the Korean Institute of Geosciences and Mineral Resources (KIGAM was requested by local administration to resolve the issue. The KIGAM used geophysical methods to delineate subsurface cavities and improve more refined understanding of the cavities network in the study area. Cement based grouting has been widely employed in the construction industry to reinforce subsurface ground. In this research work, time-lapse electrical resistivity surveys were accomplished to monitor the grouting injection in the subsurface cavities beneath the highway, which have provided a quasi-real-time monitoring for modifying the subsurface cavities related to ground reinforcement, which would be difficult with direct methods. The results obtained from time-lapse electrical resistivity technique have satisfactory imaged the grouting injection experiment in the subsurface cavities beneath the highway. Furthermore, the borehole camera confirmed the presence of grouting material in the subsurface cavities, and hence this procedure increases the mechanical resistance of subsurface cavities below the highway.

  12. Electrical Resistivity Imaging of Seawater Intrusion into the Monterey Bay Aquifer System.

    Science.gov (United States)

    Pidlisecky, A; Moran, T; Hansen, B; Knight, R

    2016-03-01

    We use electrical resistivity tomography to obtain a 6.8-km electrical resistivity image to a depth of approximately 150 m.b.s.l. along the coast of Monterey Bay. The resulting image is used to determine the subsurface distribution of saltwater- and freshwater-saturated sediments and the geologic controls on fluid distributions in the region. Data acquisition took place over two field seasons in 2011 and 2012. To maximize our ability to image both vertical and horizontal variations in the subsurface, a combination of dipole-dipole, Wenner, Wenner-gamma, and gradient measurements were made, resulting in a large final dataset of approximately 139,000 data points. The resulting resistivity section extends to a depth of 150 m.b.s.l., and is used, in conjunction with the gamma logs from four coastal monitoring wells to identify four dominant lithologic units. From these data, we are able to infer the existence of a contiguous clay layer in the southern portion of our transect, which prevents downward migration of the saltwater observed in the upper 25 m of the subsurface to the underlying freshwater aquifer. The saltwater and brackish water in the northern portion of the transect introduce the potential for seawater intrusion into the hydraulically connected freshwater aquifer to the south, not just from the ocean, but also laterally from north to south.

  13. Imaging pathways in fractured rock using three-dimensional electrical resistivity tomography

    Science.gov (United States)

    Robinson, Judith; Slater, Lee; Johnson, Timothy B.; Shapiro, Allen M.; Tiedeman, Claire R.; Ntlargiannis, Dimitrios; Johnson, Carole D.; Day-Lewis, Frederick D.; Lacombe, Pierre; Imbrigiotta, Thomas; Lane, Jr., John W.

    2016-01-01

    Major challenges exist in delineating bedrock fracture zones because these cause abrupt changes in geological and hydrogeological properties over small distances. Borehole observations cannot sufficiently capture heterogeneity in these systems. Geophysical techniques offer the potential to image properties and processes in between boreholes. We used three-dimensional cross borehole electrical resistivity tomography (ERT) in a 9 m (diameter) × 15 m well field to capture high-resolution flow and transport processes in a fractured mudstone contaminated by chlorinated solvents, primarily trichloroethylene. Conductive (sodium bromide) and resistive (deionized water) injections were monitored in seven boreholes. Electrode arrays with isolation packers and fluid sampling ports were designed to enable acquisition of ERT measurements during pulsed tracer injections. Fracture zone locations and hydraulic pathways inferred from hydraulic head drawdown data were compared with electrical conductivity distributions from ERT measurements. Static ERT imaging has limited resolution to decipher individual fractures; however, these images showed alternating conductive and resistive zones, consistent with alternating laminated and massive mudstone units at the site. Tracer evolution and migration was clearly revealed in time-lapse ERT images and supported by in situ borehole vertical apparent conductivity profiles collected during the pulsed tracer test. While water samples provided important local information at the extraction borehole, ERT delineated tracer migration over spatial scales capturing the primary hydrogeological heterogeneity controlling flow and transport. The fate of these tracer injections at this scale could not have been quantified using borehole logging and/or borehole sampling methods alone.

  14. Electrical Resistivity Tomography (ERT) Applied to Karst Carbonate Aquifers: Case Study from Amdoun, Northwestern Tunisia

    Science.gov (United States)

    Redhaounia, Belgacem; Ilondo, Batobo Ountsche; Gabtni, Hakim; Sami, Khomsi; Bédir, Mourad

    2016-04-01

    The Amdoun region is characterized by a high degree of karstification due to the climate impact (±1500 mm year-1) and the development of fracture network. Survey using electrical resistivity tomography (ERT) is deployed to provide a cost-effective characterization of the subsurface karst environments. A total of seven ERT profiles with lengths of 315 m were evaluated at the Béja governorate (NW Tunisia). The area represents a small syncline of Boudabbous limestone rocks (Lower Eocene), which is covered by a thin layer of clay. In this study, an ERT survey was conducted to examine the spatial distribution and shape of underground cavities in the karst area in Jebel Sabah anticline and Aïn Sallem-Zahret Medien syncline. In this study, geological, hydro-geological and electrical resistivity tomography (ERT) methods were applied to determine the geometry of the perched aquifer in the Amdoun region (NW Tunisia). The area is characterized by fractured and karstic limestone aquifer of Late Cretaceous (Abiod Fm.) and Lower Eocene (Boudabbous Fm.). The aquifers have a karstic functioning and drain aquifers of economical interest, despite some wells exploiting them. Seven resistivity profiles were conducted along the survey area at three sites. The orientation, extension and the degree of inclination of those profiles are shown in the location map. The correct resistivity data were interpreted using Earth Imager 2D software. The results of the interpreted geo-electrical sections showed that the resistivity of the carbonate aquifer varied between 2.5 to over 5794 Ωm. The thickness of the perched aquifer ranged from 15 to 50 m, while its depth from the surface lies between 10 and 60 m. The ERT not only provided precise near surface information, but was also very useful for establishing the 3D geometry and the position of several potential cavities and karts. The results show the presence of small to large isolated cavities at various depths. The low resistivity of cavities

  15. Lung volumes and airway resistance in patients with a possible restrictive pattern on spirometry

    Science.gov (United States)

    Schultz, Kenia; D'Aquino, Luiz Carlos; Soares, Maria Raquel; Gimenez, Andrea; Pereira, Carlos Alberto de Castro

    2016-01-01

    ABSTRACT Objective: Many patients with proportional reductions in FVC and FEV1 on spirometry show no reduction in TLC. The aim of this study was to evaluate the role that measuring lung volumes and airway resistance plays in the correct classification of patients with a possible restrictive pattern on spirometry. Methods: This was a prospective study involving adults with reduced FVC and FEV1, as well as an FEV1/FV(C) ratio within the predicted range. Restrictive lung disease (RLD) was characterized by TLC below the 5th percentile, as determined by plethysmography. Obstructive lung disease (OLD) was characterized by high specific airway resistance, significant changes in post-bronchodilator FEV1, or an FEF25-75% < 50% of predicted, together with a high RV/TLC ratio. Nonspecific lung disease (NLD) was characterized by TLC within the predicted range and no obstruction. Combined lung disease (CLD) was characterized by reduced TLC and findings indicative of airflow obstruction. Clinical diagnoses were based on clinical suspicion, a respiratory questionnaire, and the review of tests of interest. Results: We included 300 patients in the study, of whom 108 (36%) were diagnosed with RLD. In addition, 120 (40%) and 72 (24%) were diagnosed with OLD/CLD and NLD, respectively. Among the latter, 24 (33%) were clinically diagnosed with OLD. In this sample, 151 patients (50.3%) were obese, and obesity was associated with all patterns of lung disease. Conclusions: Measuring lung volumes and airway resistance is often necessary in order to provide an appropriate characterization of the pattern of lung disease in patients presenting with a spirometry pattern suggestive of restriction. Airflow obstruction is common in such cases. PMID:27812633

  16. A method to improve tree water use estimates by distinguishing sapwood from heartwood using Electrical Resistivity Tomography

    Science.gov (United States)

    Guyot, A.; Ostergaard, K.; Lenkopane, M.; Fan, J.; Lockington, D. A.

    2011-12-01

    Estimating whole-plant water use in trees requires reliable and accurate methods. Measuring sap velocity and extrapolating to tree water use is seen as the most commonly used. However, deducing the tree water use from sap velocity requires an estimate of the sapwood area. This estimate is the highest cause of uncertainty, and can reach more than 50 % of the uncertainty in the estimate of water use per day. Here, we investigate the possibility of using Electrical Resistivity Tomography to evaluate the sapwood area distribution in a plantation of Pinus elliottii. Electric resistivity tomographs of Pinus elliottii show a very typical pattern of electrical resistivity, which is highly correlated to sapwood and heartwood distribution. To identify the key factors controlling the variation of electrical resistivity, cross sections at breast height for ten trees have been monitored with electrical resistivity tomography. Trees have been cut down after the experiment to identify the heartwood/sapwood boundaries and to extract wood and sap samples. pH, electrolyte concentration and wood moisture content have then been analysed for these samples. Results show that the heartwood/sapwood patterns are highly correlated with electrical resistivity, and that the wood moisture content is the most influencing factor controlling the variability of the patterns. These results show that electric resistivity tomography could be used as a powerful tool to identify the sapwood area, and thus be used in combination with sapflow sensors to map tree water use at stand scale. However, if Pinus elliottii shows typical patterns, further work is needed to identify to see if there are species - specific characterictics as shown in previous works (, electrolyte gradients from the bark to the heartwood). Also, patterns of high resistivity in between needles positions, which are not correlated with either wood moisture content or sapwood, appear to be artifacts. Thus, inversion methods have also to

  17. Characterizing root system characteristics with Electrical resistivity Tomography: a virtual rhizotron simulation

    Science.gov (United States)

    Rao, Sathyanarayan; Ehosioke, Solomon; Lesparre, Nolwenn; Nguyen, Frédéric; Javaux, Mathieu

    2017-04-01

    Electrical Resistivity Tomography (ERT) is more and more used for monitoring soil water content in a cropped soil. Yet, the impact of roots on the signal is often neglected and a topic of controversy. In several studies related to soil-root system, it has been showed that the measured root mass density statistically correlates with the electrical conductivity (EC) data obtained from ERT. In addition, some studies suggest that some roots are more electrically conductive than soil for most water content. Thus, higher EC of roots suggest that it might have a measurable impact on ERT signals. In this work, virtual rhizotrons are simulated using the software package called R-SWMS that solves water and solute transport in plant root-soil system, including root growth. The distribution of water content obtained from R-SWMS simulation is converted into EC data using pedo-physical models. The electrical properties of roots and rhizosphere are explicitly included in the EC data to form a conductivity map (CM) with a very detailed spatial resolution. Forward ERT simulations is then carried out for CM generated for various root architectures and soil conditions to study the impact of roots on ERT forward (current and voltage patterns) and inverse solutions. It is demonstrated that under typical injection schemes with lateral electrodes, root system is hardly measurable. However, it is showed that adding electrodes and constraints on the ERT inversion based on root architecture help quantifying root system mass and extent.

  18. Surface and subsurface damage detection in cement-based materials using electrical resistance tomography

    Science.gov (United States)

    Ruan, T.; Poursaee, A.

    2016-04-01

    Cement-based materials are widely used in infrastructure facilities. However, often the degradation of structures leads to the failures earlier than designed service life. Thus, non-destructive testing techniques are urgently needed to evaluate the health information of the structures. In this paper, the implementation of Electrical Resistance Tomography (ERT) was investigated. This low cost, radiation free and easy to perform modality is based on measuring the electrical properties of the material under test and using that to evaluate the existence of defects in that material. It uses a set of boundary potentials and injected current to reconstruct the conductivity distribution. An automatic measurement system was developed and surface damages as well as subsurface damages on mortar specimens were investigated. The reconstructed images were capable to show the presence and the location of the damages.

  19. Skid resistance performance of asphalt wearing courses with electric arc furnace slag aggregates.

    Science.gov (United States)

    Kehagia, Fotini

    2009-05-01

    Metallurgical slags are by-products of the iron and steel industry and are subdivided into blast furnace slag and steel slag according to the different steel-producing processes. In Greece, slags are mostly produced from steelmaking using the electric arc furnace process, and subsequently are either disposed in a random way or utilized by the cement industry. Steel slag has been recently used, worldwide, as hard aggregates in wearing courses in order to improve the skidding resistance of asphalt pavements. At the Highway Laboratory, Department of Civil Engineering of Aristotle University of Thessaloniki research has been carried out in the field of steel slags, and especially in electric arc furnace (EAF) slag, to evaluate their possible use in highway engineering. In this paper, the recent results of anti-skidding performance of steel slag aggregates in highway pavements are presented.

  20. Optical Absorption and Electric Resistivity of an l-Cysteine Film

    Science.gov (United States)

    Kamada, Masao; Hideshima, Takuya; Azuma, Junpei; Yamamoto, Isamu; Imamura, Masaki; Takahashi, Kazutoshi

    2016-12-01

    The optical and electric properties of an l-cysteine film have been investigated to understand its applicability to bioelectronics. The fundamental absorption is the allowed transition having the threshold at 5.8 eV and the absorption is due to the charge-transfer type transition from sulfur-3sp to oxygen-2p and/or carbon-2p states, while absorptions more than 9 eV can be explained with intra-atomic transitions in the functional groups. The electric resistivity is 2.0 × 104 Ω m at room temperature and increases as the sample temperature decreases. The results indicate that the l-cysteine film is a p-type semiconductor showing the hole conduction caused by the sulfur-3sp occupied states and unknown impurity or defect states as acceptors. The electron affinity of the l-cysteine film is derived as ≦-0.3 eV.

  1. Electrical resistivity imaging in transmission between surface and underground tunnel for fault characterization

    Science.gov (United States)

    Lesparre, N.; Boyle, A.; Grychtol, B.; Cabrera, J.; Marteau, J.; Adler, A.

    2016-05-01

    Electrical resistivity images supply information on sub-surface structures and are classically performed to characterize faults geometry. Here we use the presence of a tunnel intersecting a regional fault to inject electrical currents between surface and the tunnel to improve the image resolution at depth. We apply an original methodology for defining the inversion parametrization based on pilot points to better deal with the heterogeneous sounding of the medium. An increased region of high spatial resolution is shown by analysis of point spread functions as well as inversion of synthetics. Such evaluations highlight the advantages of using transmission measurements by transferring a few electrodes from the main profile to increase the sounding depth. Based on the resulting image we propose a revised structure for the medium surrounding the Cernon fault supported by geological observations and muon flux measurements.

  2. The electric properties and the current-controlled differential negative resistance of cBN crystal

    Institute of Scientific and Technical Information of China (English)

    2008-01-01

    The electric properties of nonintentionally doped n-cubic boron nitride(cBN) crystal are investigated.The cBN crystal was transformed from hexagonal-boron nitride(h-BN) under high pressure(HP) and high temperature(HT) using magnesium powder as catalyst.At room temperature,the current-voltage(I-V) characteristics of cBN crystal are measured and found to be nonlinear.When the electric field is in the range of(1―1.5)×105 V/cm,the avalanche breakdown occurs inside the whole cBN crystal.At this same time,the bright blue-violet with the wavelength of 380―400 nm from the cBN crystal is observed.When measuring the I-V curve after breakdown of cBN crystal,the current-controlled differential negative resistance phenomenon is observed.The breakdown is repeatable.

  3. Electrical nanocharacterization of copper tetracyanoquinodimethane layers dedicated to resistive random access memories

    Science.gov (United States)

    Deleruyelle, Damien; Muller, Christophe; Amouroux, Julien; Müller, Robert

    2010-06-01

    The local electrical properties of copper tetracyanoquinodimethane (CuTCNQ)/HfO2/Pt stacks were investigated thanks to conductive-atomic force microscopy (AFM) measurements. Local I-V and I-t spectroscopy evidenced repeatable and reversible bipolar electrical switching (SET and RESET operations) at the nanometer scale beneath the AFM tip. Experimental results suggest that resistive switching is due to the creation/dissolution of conductive filaments bridging the CuTCNQ surface to the AFM tip. A physical model based on the migration of Cu+ ions within a nanogap and the growth of a conductive filament shows an excellent agreement with the experimental results during SET operation achieved at nanoscale.

  4. Electrical resistivity of TiH/sub x/ and TiH/sub x//KC10/sub 4/

    Energy Technology Data Exchange (ETDEWEB)

    White, K.; Reed, J.W.; Love, C.M.; Glaub, J.E.; Holy, J.A.

    1979-03-16

    Various factors affecting the electrical resistivity of the pyrotechnic pressed powder TiH/sub x//KC10/sub 4/, which is sensitive to hot wire ignition yet quite spark insensitive, were evaluated. The electrical resistivity of the TiH/sub x/ and TiH/sub x//KC10/sub 4/ were correlated with their pressing pressure, stoichiometry, powder surface area, and temperature (from below liquid nitrogen temperature to 500 K). Data show resistivity increasing with x and surface area, and decreasing non-linearly with pressing pressure. It was concluded that temperature coefficient of resistivity depends upon powder surface features. In addition, it was found that electrostatic discharge lowers TiH/sub x/ and TiH/sub x//KC10/sub 4/ pellet resistivity and that the effect is larger for pellets with higher initial resistivity.

  5. Electrical resistivity tomography (ERT surveys on glacial deposits in Romanian Carpathians

    Directory of Open Access Journals (Sweden)

    Andrei ZAMOSTEANU

    2014-11-01

    Full Text Available The study presents preliminary results regarding the use of electrical resistivity surveys in the assessment of the internal structure of the glacial deposits from the Romanian Carpathians.ERT is a geophysical method used to quantify changes in electrical resistivity of the ground towards passing electric current across an array of electrodes and simultaneous measurement of the induced potential gradient. Using specific software the measurements are further processed and correlated with the topography in order to obtain bedrock resistivity features. Therefore, the method is useful to evaluate the characteristics of geological strata and is widely used for mapping shallow subsurface geological structures. In the mountain regions ERT studies have been applied in different glacial and periglacial geomorphological studies - for permafrost detection (in Romanian Carpathians - Urdea et. al., 2008; Vespremeanu-Stroe et al., 2012, slope deformation analysis, the assessment of slip surface depths, sediment thickness, groundwater levels etc. One of the most commonly 2-D array used is the Wenner electrode configuration, which is moderately sensitive to both horizontal and vertical ground structures.Due to their elevations and Pleistocene’s climatic conditions, the Romanian Carpathians have been partially affected by Quaternary glaciations. The glaciers descended to about 1050-1200 m a.s.l. (Urdea and Reurther, 2009 in the Transylvanian Alps and Rodna Mountains (Eastern Carpathians carving a large number of U-shaped valleys and glacial cirques (Mîndrescu, 2006 and forming accumulations of unconsolidated glacial debris (moraines. Our study areas are two sites located in the northern (Rodna Mts. and southern (Iezer Păpuşa Mts. part of the mountain range.

  6. Modelling of snowmelt infiltration in heterogeneous seasonally-frozen soil monitored by electrical resistivity measurements

    Science.gov (United States)

    French, H. K.; Binley, A. M.; Voss, C.

    2016-12-01

    Infiltration during snowmelt can be highly heterogeneous due to the formation of ice on the ground surface below the snow cover. In situations where snow is contaminated, such as along highways and airports due to de-icing agents, it is important to predict the zone of infiltration, because this will determine the retention time and potential for degradation in the unsaturated zone. In 2001, infiltration during snowmelt was monitored over a small area (4m2) using time-lapse electrical resistivity monitoring at Gardermoen, Norway. Data revealed a spatio-temporal variable infiltration pattern related to micro topography of the ground surface (French and Binley, 2004). In this study, we want to test the suitability of a newly developed numerical model for water and heat transport including phase change in a variably saturated soil against field observations. Monitored weather and snow data defined the boundary conditions of a simulated unsaturated profile with seasonal freezing. The dependency of capillary pressure and permeability on water saturation is taken from van Genuchten equation with the addition of a scaling parameter, to account for the heterogeneity of the hydraulic permeability. Soil physical data and heterogeneity (variance and correlation structure of the permeability) was based on local soil measurements. The available amount of meltwater for infiltration over the area was based on average snowmelt measurements at the site. Different infiltration scenarios were tested. Soil temperatures, TDR measurements of soil moisture, a tracer experiment conducted at an adjacent site and changes in electrical resistivity were used to validate the model of infiltration and thawing. The model was successful in reproducing the thawing and soil moisture patterns observed in the soil, and hence looks like a promising tool for predicting snowmelt infiltration and melting of ground frost in a sandy unsaturated soil. ReferencesFrench, H.K. and Binley, A. (2004) Snowmelt

  7. A novel in vivo corneal trans-epithelial electrical resistance measurement device.

    Science.gov (United States)

    Uematsu, Masafumi; Mohamed, Yasser Helmy; Onizuka, Naoko; Ueki, Ryotaro; Inoue, Daisuke; Fujikawa, Azusa; Kitaoka, Takashi

    2015-01-01

    To develop a device that is capable of easily measuring corneal transepithelial electrical resistance (TER) and changes in the corneal barrier function. We had previously developed an in vivo method for measuring corneal TER using intraocular electrode. This method can be used to precisely measure the decline of the corneal barrier function after instillation of benzalkonium chloride (BAC). In order to lessen the invasiveness of that procedure, we further refined the method for measuring the corneal TER by developing electrodes that could be placed on the cornea and in the conjunctival sac instead of inserting them into the anterior chamber. TER was then calculated by subtracting the electrical resistance, which lacked the corneal epithelial input, from the whole electrical resistance that was measured between the electrodes. Slit lamp examination and scanning electron microscopy (SEM) were used to determine safety of the new device. Corneal TER changes after exposure to 0.02% BAC were determined using the new device as well as SEM and transmission electron microscopy (TEM). Slit lamp examination before and after exposure of rabbits' corneas to the sensor confirmed safety of the device. SEM examination revealed no difference of the corneal epithelium which exposed to the new device with normal corneas. SEM and TEM pictures revealed damaged microvilli and tight junctions after instillation of 0.02% BAC. TER change after treatment with 0.02%BAC was similar to those determined by the established anterior chamber method. We succeeded to develop a less invasive device for corneal TER measurement in vivo in animals. This new device may be applicable in the future for clinical use in humans. Copyright © 2015 Elsevier Inc. All rights reserved.

  8. Saline tracer visualized with three-dimensional electrical resistivity tomography: Field-scale spatial moment analysis

    Science.gov (United States)

    Singha, Kamini; Gorelick, Steven M.

    2005-01-01

    Cross-well electrical resistivity tomography (ERT) was used to monitor the migration of a saline tracer in a two-well pumping-injection experiment conducted at the Massachusetts Military Reservation in Cape Cod, Massachusetts. After injecting 2200 mg/L of sodium chloride for 9 hours, ERT data sets were collected from four wells every 6 hours for 20 days. More than 180,000 resistance measurements were collected during the tracer test. Each ERT data set was inverted to produce a sequence of 3-D snapshot maps that track the plume. In addition to the ERT experiment a pumping test and an infiltration test were conducted to estimate horizontal and vertical hydraulic conductivity values. Using modified moment analysis of the electrical conductivity tomograms, the mass, center of mass, and spatial variance of the imaged tracer plume were estimated. Although the tomograms provide valuable insights into field-scale tracer migration behavior and aquifer heterogeneity, standard tomographic inversion and application of Archie's law to convert electrical conductivities to solute concentration results in underestimation of tracer mass. Such underestimation is attributed to (1) reduced measurement sensitivity to electrical conductivity values with distance from the electrodes and (2) spatial smoothing (regularization) from tomographic inversion. The center of mass estimated from the ERT inversions coincided with that given by migration of the tracer plume using 3-D advective-dispersion simulation. The 3-D plumes seen using ERT exhibit greater apparent dispersion than the simulated plumes and greater temporal spreading than observed in field data of concentration breakthrough at the pumping well.

  9. Comparing spatial series of soil bulk electrical conductivity as obtained by Time Domain Reflectometry and Electrical Resistivity Tomography

    Science.gov (United States)

    Saeed, Ali; Dragonetti, Giovanna; Comegna, Allessandro; Garre, Sarah; Lamaddalena, Nicola; Coppola, Antonio

    2016-04-01

    Conventional ground survey of soil root zone salinity by direct soil sampling are time consuming, costly and destructive. Alternatively, soil salinity can be evaluated by measuring the bulk electrical conductivity, σb, in the field. This approach is faster and cheaper, and allows a more intensive surveying. Measurements of σb can be made either in situ or with remote devices. Time domain reflectometry (TDR) sensors allow simultaneous measurements of water content, θ, and σb. They may be calibrated for estimating the electrical conductivity of the soil solution (σw). However, they have a relatively small observation window and thus they are thought to only provide local-scale measurements. The spatial range of the sensors is limited to tens of centimeters and extension of the information to a large area can be problematic. Also, information on the vertical distribution of the σb soil profile may only be obtained by installing sensors at different depths. In this sense, the TDR may be considered as an invasive technique. Compared to the TDR, other geophysical methods based for example on the Electrical Resistivity Tomography (ERT) techniques represent an alternative in respect to those traditional for soil salinity characterization. In order to deduce the actual distribution of the bulk electrical conductivity, σb, in the soil profile, one needs to invert the signal coming from ERT sensors. The latter, in turn, depends on the specific depth distribution of the σb, as well as on the electrical configuration of the sensor used. With these premises, the main aim of this study is to estimate the vertical σb distribution starting from resistivity data series measured using the ERT method under different salinity conditions and using TDR data as ground-truth data for calibration and validation of the ERT sensor. This way, limited measured TDR data may be used for translating extensive ERT apparent electrical conductivity, σa, measurements to estimate depth

  10. Volume electric dipole origin of second-harmonic generation from metallic membrane with non-centrosymmetry patterns

    CERN Document Server

    Zeng, Yong

    2009-01-01

    In this article, we analytically study second harmonic (SH) generation from thin metallic films with subwavelength, non-centrosymmetry patterns. Because the thickness of the film is much smaller than the SH wavelength, retardation effects are negligible. The far-field SH intensities are thus dominated by an effective electric dipole. These analytical observations are further justified numerically by studying the effect of polarization of the fundamental field on both the SH signal and the electric dipole. It is demonstrated that bulk SH polarization density is comparable with its surface counterpart. The electric dipole, consequently, originates from the entire {volume of the metallic membrane, in contrast to the fact that SH generation from metal surface is generally dominated by a surface dipole.

  11. Electrical Resistivity Peculiarities of the Nanograined Bi2Te3 Material

    Directory of Open Access Journals (Sweden)

    O.N. Ivanov

    2015-12-01

    Full Text Available The hot quasiisostaic pressure method was applied to sinter the nanograined Bi2Te3 material. The samples with various mean grain size of 64, 61, 56 and 51 nm were prepared by changing the pressure of sintering. It was found that the specific electrical resistivity of the material under study increases when the mean grain size decreases. The Hall effect was measured to extract the concentration and mobility values of the charge carries. It was found that the electron concentration decreases as the mean grain size decreases while the electron mobility has extreme dependence on the grain size.

  12. Advanced design of conductive polymeric arrays with controlled electrical resistance using direct laser interference patterning

    Energy Technology Data Exchange (ETDEWEB)

    Lasagni, A.F. [Saarland University, Department of Materials Science, Chair of Functional Materials, Building C 6.3, 7. Stock, P.O. Box 15 11 50, Saarbruecken (Germany); George W. Woodruff School of Mechanical Engineering, Georgia Institute of Technology, Atlanta, GA (United States); Acevedo, D.F. [Saarland University, Department of Materials Science, Chair of Functional Materials, Building C 6.3, 7. Stock, P.O. Box 15 11 50, Saarbruecken (Germany); Universidad Nacional de Rio Cuarto, Departamento de Quimica, Cordoba (Argentina); Barbero, C.A. [Universidad Nacional de Rio Cuarto, Departamento de Quimica, Cordoba (Argentina); Muecklich, F. [Saarland University, Department of Materials Science, Chair of Functional Materials, Building C 6.3, 7. Stock, P.O. Box 15 11 50, Saarbruecken (Germany)

    2008-06-15

    In this work, we report a simple method for the fabrication of regular conducting polyaniline periodic arrays on large areas of glass or gold substrates using direct laser interference patterning. Additionally, by controlling the laser intensity it is possible to precisely tune the width of the periodic arrays and consequently the electrical resistance of the polyaniline strips. The periodic arrays were characterized using scanning electron microscopy, white light interferometry and cyclic voltametry. The great importance of the method reported lies both in its versatility and the ability to control the properties of the modified polymer electrodes with high precision. This is important for prospective applications such as electrochemical sensors. (orig.)

  13. Eradication of multidrug-resistant A. baumannii in burn wounds by antiseptic pulsed electric field.

    Science.gov (United States)

    Golberg, Alexander; Broelsch, G Felix; Vecchio, Daniela; Khan, Saiqa; Hamblin, Michael R; Austen, William G; Sheridan, Robert L; Yarmush, Martin L

    2014-06-01

    Emerging bacterial resistance to multiple drugs is an increasing problem in burn wound management. New non-pharmacologic interventions are needed for burn wound disinfection. Here we report on a novel physical method for disinfection: antiseptic pulsed electric field (PEF) applied externally to the infected burns. In a mice model, we show that PEF can reduce the load of multidrug resistant Acinetobacter baumannii present in a full thickness burn wound by more than four orders of magnitude, as detected by bioluminescence imaging. Furthermore, using a finite element numerical model, we demonstrate that PEF provides non-thermal, homogeneous, full thickness treatment for the burn wound, thus, overcoming the limitation of treatment depth for many topical antimicrobials. These modeling tools and our in vivo results will be extremely useful for further translation of the PEF technology to the clinical setting, as they provide the essential elements for planning of electrode design and treatment protocol.

  14. Electric Field Control of the Resistance of Multiferroic Tunnel Junctions with Magnetoelectric Antiferromagnetic Barriers

    Science.gov (United States)

    Merodio, P.; Kalitsov, A.; Chshiev, M.; Velev, J.

    2016-06-01

    Based on model calculations, we predict a magnetoelectric tunneling electroresistance effect in multiferroic tunnel junctions consisting of ferromagnetic electrodes and magnetoelectric antiferromagnetic barriers. Switching of the antiferromagnetic order parameter in the barrier in applied electric field by means of the magnetoelectric coupling leads to a substantial change of the resistance of the junction. The effect is explained in terms of the switching of the orientations of local magnetizations at the barrier interfaces affecting the spin-dependent interface transmission probabilities. Magnetoelectric multiferroic materials with finite ferroelectric polarization exhibit an enhanced resistive change due to polarization-induced spin-dependent screening. These results suggest that devices with active barriers based on single-phase magnetoelectric antiferromagnets represent an alternative nonvolatile memory concept.

  15. Critical behavior of electrical resistivity in amorphous Fe–Zr alloys

    Indian Academy of Sciences (India)

    A Perumal

    2001-04-01

    Electrical resistivity (ρ) of the amorphous (a-)Fe100-Zr ( = 8.5, 9.5 and 10) alloys has been measured in the temperature range 77 to 300 K, which embraces the second-order magnetic phase transition at the Curie temperature point . Analysis of the resistivity data particularly in the critical region reveals that these systems have a much wider range of critical region compared to other crystalline ferromagnetic materials. The value of and specific heat critical exponent, has the same values as those determined from our earlier magnetic measurements. The value of for all the present investigated alloys are in close agreement with the values predicted for three-dimensional (3D) Heisenberg ferromagnet systems, which gives contradiction to the earlier results on similar alloys. It is observed from the analysis that the presence of quenched disorder does not have any influence on critical behavior.

  16. Research on temperature control with numerical regulators in electric resistance furnaces with indirect heating

    Science.gov (United States)

    Diniş, C. M.; Popa, G. N.; Iagăr, A.

    2016-02-01

    The paper is an analysis of two-positions (hysteresis) regulators, self-tuned PID controller and PID controller for temperature control used for indirect heat resistance furnaces. For PID controller was used three methods of tuning: Ziegler-Nichols step response model, Cohen-Coon tuning rules and Ziegler-Nichols tuning rules. In experiments it used an electric furnace with indirect heating with active power of resistance of 1 kW/230V AC and a numerical temperature regulator AT-503 type (ANLY). It got a much better temperature control when using the Cohen-Coon tuning rules method than those of Ziegler-Nichols step response method and Ziegler-Nichols tuning rules method.

  17. Effect of atomic order on the electrical resistivity of CoxFe100-x alloys

    Science.gov (United States)

    Freitas, P. P.; Berger, L.

    1988-04-01

    We measured the electrical resistivity at 4.2 K of a series of CoxFe100-x alloys in the ordered and disordered state. For 30dTQ has a strong negative anomaly at To. At high temperatures and in equilibrium, ρ(T) decreases upon ordering and dρ/dT has a positive anomaly at To. This crossover from a gap-dominated to a relaxation-time-dominated critical behavior is induced by increasing the measuring temperature T, therefore exciting electrons across the energy gap. From the dependence of ρ(TQ,T) on T we estimate the gap width to be around 45 meV. For x=50 at.% Co both ρ(TQ,4.2 K) and ρ(T) decrease upon ordering. Here the gapless behavior of the resistivity is due to the particular topology of the Fermi surface.

  18. Improved measurements of the apparent resistivity for small depths in Vertical Electrical Soundings

    Science.gov (United States)

    Faleiro, E.; Asensio, G.; Moreno, J.

    2016-08-01

    In this work, a full simulation of a Vertical Electrical Sounding of a multilayer soil using a Wenner array is performed when both the active and the measurement electrodes consist of bare rod length L buried vertically at ground level. The apparent resistivity is calculated for a wide range of values of the separation between the electrodes using the values of the potential between the measuring electrode and a proposed function that characterizes the behavior of the electrodes used which substantially improves the measurements for small depths. The results allow comparing the values of apparent resistivity obtained by known calculation expressions with the results found by using a characteristic function of the electrodes, which is proposed in this paper. In order to obtain a complete vertical sounding of the soil, the convenience of using adapted methods to the type of electrode used in the sounding is discussed.

  19. Electrical resistivity and geotechnical assessment of subgrade soils in southwestern part of Nigeria

    Science.gov (United States)

    Adebisi, N. O.; Ariyo, S. O.; Sotikare, P. B.

    2016-07-01

    The subgrade soils in areas underlain by the slightly Migmatized to Non-migmatized Metasedimentary and Metaigneous rocks of Southwestern Nigeria have been considerably investigated. However, a serious research which employs electrical resistivity method for insight into the profile development, as well as estimation of resistance to deformation for predicting the stability of flexible highway pavements is yet to be carried out. In this study, Vertical Electrical Sounding (VES) were carried out after a reconnaissance survey based on stable and unstable locations on the road. Index and strength tests related to road construction were also carried out on bulk samples obtained from stable and failed (unstable) locations of the Ago-Iwoye/Ishara highway. Results show mostly three (3) layers in the profiles with H, HK, and HKH curve types. The subgrade soils below the stable locations have better vertical and interval variations in the resistivities (89-1095 Ωm) to a depth of 3.4 m as against those from the failed portions. Those from the stable locations also have higher specific gravity (2.72), low-medium plasticity and A-2-6 kaolinitic clayey soils with higher compacted density (2090 kg/m3) compared to subgrade soils from the failed locations. On the basis of Califonia Bearing Ratio (CBR), subgrade soils at stable locations have greater strength than those obtained from failed locations. Estimated resistance to deformation (R-value) and resilient modulus (MR) proved to be the overriding parameters for predicting the stability of the flexible highway pavements.

  20. High resolution electrical resistivity tomography of golf course greens irrigated with reclaimed wastewater: Hydrological approach

    Science.gov (United States)

    Tapias, Josefina C.; Lovera, Raúl; Himi, Mahjoub; Gallardo, Helena; Sendrós, Alexandre; Marguí, Eva; Queralt, Ignasi; Casas, Albert

    2014-05-01

    Actually, there are over 300 golf courses and more than three thousand licensed players in Spain. For this reason golf cannot be considered simply a hobby or a sport, but a very significant economic activity. Considered as one of the most rapidly expanding land-use and water demanding business in the Mediterranean, golf course development generates controversy. In the recent years there has been a considerable demand for golf courses to adopt environmentally sustainable strategies and particularly water authorities are forcing by law golf managers to irrigate with alternative water resources, mainly reclaimed wastewater. Watering practices must be based on soil properties that are characterized by samples removed from the different zones of the golf course and submitted to an accredited physical soil testing laboratory. Watering schedules are critical on greens with poor drainage or on greens with excessively high infiltration rates. The geophysical survey was conducted over the greens of the Girona Golf Club. Eighteen electrical resistivity tomographies were acquired using a mixed Wenner-Schlumberger configuration with electrodes placed 0.5 meter apart. Small stainless-steel nails were used as electrodes to avoid any damage in the fine turfgrass of greens The resistivity meter was set for systematically and automatically selects current electrodes and measurement electrodes to sample apparent resistivity values. Particle size analysis (PSA) has been performed on soil materials of any putting green. The PSA analysis has been composed of two distinct phases. The first has been the textural analysis of the soils for determining the content of sand, silt, and clay fraction via the use of a stack of sieves with decreasing sized openings from the top sieve to the bottom. Subsequently, the hydraulic conductivity of the substrates has been evaluated by means of Bredding and Hazen empirical relationships. The results of this research show that the electrical resistivity

  1. Static resistivity image of a cubic saline phantom in magnetic resonance electrical impedance tomography (MREIT).

    Science.gov (United States)

    Lee, Byung Il; Oh, Suk Hoon; Woo, Eung Je; Lee, Soo Yeol; Cho, Min Hyeong; Kwon, Ohin; Seo, Jin Keun; Baek, Woon Sik

    2003-05-01

    In magnetic resonance electrical impedance tomography (MREIT) we inject currents through electrodes placed on the surface of a subject and try to reconstruct cross-sectional resistivity (or conductivity) images using internal magnetic flux density as well as boundary voltage measurements. In this paper we present a static resistivity image of a cubic saline phantom (50 x 50 x 50 mm3) containing a cylindrical sausage object with an average resistivity value of 123.7 ohms cm. Our current MREIT system is based on an experimental 0.3 T MRI scanner and a current injection apparatus. We captured MR phase images of the phantom while injecting currents of 28 mA through two pairs of surface electrodes. We computed current density images from magnetic flux density images that are proportional to the MR phase images. From the current density images and boundary voltage data we reconstructed a cross-sectional resistivity image within a central region of 38.5 x 38.5 mm2 at the middle of the phantom using the J-substitution algorithm. The spatial resolution of the reconstructed image was 64 x 64 and the reconstructed average resistivity of the sausage was 117.7 ohms cm. Even though the error in the reconstructed average resistivity value was small, the relative L2-error of the reconstructed image was 25.5% due to the noise in measured MR phase images. We expect improvements in the accuracy by utilizing an MRI scanner with higher SNR and increasing the size of voxels scarifying the spatial resolution.

  2. Trilogy possible meteorite impact crater at Bukit Bunuh, Malaysia using 2-D electrical resistivity imaging

    Science.gov (United States)

    Jinmin, M.; Rosli, S.; Nordiana, M. M.; Mokhtar, S.

    2017-07-01

    Bukit Bunuh situated in Lenggong (Perak) is one of Malaysia's most important areas for archeology that revealed many traces of Malaysia's prehistory. Geophysical method especially 2-D electrical resistivity imaging method is non-destructive which is applied in geo-subsurface study for meteorite impact. The study consists of two stages which are regional and detail study with a total of fourteen survey lines. The survey lines were conducted using Pole-dipole array with 5 m minimum electrode spacing. The results of each stage are correlated and combined to produce detail subsurface resistivity distribution of the study area. It shows that the area consists of two main layers which are overburden and granitic bedrock. The first layer is overburden mix with boulders with resistivity value of 10-800 Ωm while the second layer is granitic bedrock with resistivity value of >1500 Ωm. This study also shows few spotted possibility of uplift (rebound) due to the high impact which suspected from meteorite. A lot of fracture were found within the survey area which could be one of the effect of meteorite impact. The result suggest that Bukit Bunuh is under layer by a complex crater with diameter of crater rim is approximately 5-6 km.

  3. Investigation of the Interaction between Perovskite Films with Moisture via in Situ Electrical Resistance Measurement.

    Science.gov (United States)

    Hu, Long; Shao, Gang; Jiang, Tao; Li, Dengbing; Lv, Xinlin; Wang, Hongya; Liu, Xinsheng; Song, Haisheng; Tang, Jiang; Liu, Huan

    2015-11-18

    Organometal halide perovskites have recently emerged as outstanding semiconductors for solid-state optoelectronic devices. Their sensitivity to moisture is one of the biggest barriers to commercialization. In order to identify the effect of moisture in the degradation process, here we combined the in situ electrical resistance measurement with time-resolved X-ray diffraction analysis to investigate the interaction of CH3NH3PbI(3-x)Cl(x) perovskite films with moisture. Upon short-time exposure, the resistance of the perovskite films decreased and it could be fully recovered, which were ascribed to a mere chemisorption of water molecules, followed by the reversible hydration into CH3NH3PbI(3-x)Cl(x)·H2O. Upon long-time exposure, however, the resistance became irreversible due to the decomposition into PbI2. The results demonstrated the formation of monohydrated intermediate phase when the perovskites interacted with moisture. The role of moisture in accelerating the thermal degradation at 85 °C was also demonstrated. Furthermore, our study suggested that the perovskite films with fewer defects may be more inherently resistant to moisture.

  4. Urban archaeological investigations using surface 3D Ground Penetrating Radar and Electrical Resistivity Tomography methods

    Science.gov (United States)

    Papadopoulos, Nikos; Sarris, Apostolos; Yi, Myeong-Jong; Kim, Jung-Ho

    2009-02-01

    Ongoing and extensive urbanisation, which is frequently accompanied with careless construction works, may threaten important archaeological structures that are still buried in the urban areas. Ground Penetrating Radar (GPR) and Electrical Resistivity Tomography (ERT) methods are most promising alternatives for resolving buried archaeological structures in urban territories. In this work, three case studies are presented, each of which involves an integrated geophysical survey employing the surface three-dimensional (3D) ERT and GPR techniques, in order to archaeologically characterise the investigated areas. The test field sites are located at the historical centres of two of the most populated cities of the island of Crete, in Greece. The ERT and GPR data were collected along a dense network of parallel profiles. The subsurface resistivity structure was reconstructed by processing the apparent resistivity data with a 3D inversion algorithm. The GPR sections were processed with a systematic way, applying specific filters to the data in order to enhance their information content. Finally, horizontal depth slices representing the 3D variation of the physical properties were created. The GPR and ERT images significantly contributed in reconstructing the complex subsurface properties in these urban areas. Strong GPR reflections and high-resistivity anomalies were correlated with possible archaeological structures. Subsequent excavations in specific places at both sites verified the geophysical results. The specific case studies demonstrated the applicability of ERT and GPR techniques during the design and construction stages of urban infrastructure works, indicating areas of archaeological significance and guiding archaeological excavations before construction work.

  5. ENVIRONMENTAL MONITORING OF LEAKS USING TIME LAPSED LONG ELECTRODE ELECTRICAL RESISTIVITY

    Energy Technology Data Exchange (ETDEWEB)

    RUCKER DF; FINK JB; LOKE MH; MYERS DA

    2009-11-05

    Highly industrialized areas pose significant challenges for surface based electrical resistivity characterization and monitoring due to the high degree of metallic infrastructure. The infrastructure is typically several orders of magnitude more conductive than the desired targets, preventing the geophysicist from obtaining a clear picture of the subsurface. These challenges may be minimized if steel-cased wells are used as long electrodes. We demonstrate a method of using long electrodes in a complex nuclear waste facility to monitor a simulated leak from an underground storage tank. The leak was simulated by injecting high conductivity fluid in a perforated well and the resistivity measurements were made before and after the leak test. The data were processed in four dimensions, where a regularization procedure was applied in both the time and space domains. The results showed a lowered resistivity feature develop south of the injection site. The time lapsed regularization parameter had a strong influence on the differences in inverted resistivity between the pre and post datasets, potentially making calibration of the results to specific hydrogeologic parameters difficult.

  6. Saturation of electrical resistivity of solid iron at Earth's core conditions.

    Science.gov (United States)

    Pozzo, Monica; Alfè, Dario

    2016-01-01

    We report on the temperature dependence of the electrical resistivity of solid iron at high pressure, up to and including conditions likely to be found at the centre of the Earth. We have extended some of the calculations of the resistivities of pure solid iron we recently performed at Earth's core conditions (Pozzo et al. in Earth Planet Sci Lett 393:159-164, 2014) to lower temperature. We show that at low temperature the resistivity increases linearly with temperature, and saturates at high temperature. This saturation effect is well known as the Mott-Ioffe-Regel limit in metals, but has been largely ignored to estimate the resistivity of iron at Earth's core conditions. Recent experiments (Gomi et al. in Phys Earth Planet Int 224:88-103, 2013) coupled new high pressure data and saturation to predict the resitivity of iron and iron alloys at Earth's core conditions, and reported values up to three times lower than previous estimates, confirming recent first principles calculations (de Koker et al. in Proc Natl Acad Sci 109:4070-4073, 2012; Pozzo et al. in Nature 485:355-358, 2012, Phys Rev B 87:014110-10, 2013, Earth Planet Sci Lett 393:159-164, 2014; Davies et al. in Nat Geosci 8:678-685, 2015). The present results support the saturation effect idea.

  7. Electrical resistivity dip in Sb x V y Mo z O t phases

    Science.gov (United States)

    Groń, T.; Filipek, E.; Mazur, S.; Duda, H.; Pacyna, A. W.; Mydlarz, T.; Bärner, K.

    2010-07-01

    Electrical resistivity dips have been discovered in the temperature range 100-500 K both in the SbVO4.96 matrix and the Sb x V y Mo z O t phases for 10 mol% solubility of MoO3 in SbVO5. As the Sb content increases and simultaneously the V content decreases, the value of the resistivity at the dip, ρ d, decreases and shifts the dip to higher temperatures. The magnetic measurements showed a spontaneous magnetization and parasitic magnetism of the solid solutions under study. Characteristic for parasitic magnetism is a small value of the magnetic moment, here 0.014 μ B/f.u. at 4.2 K and at a magnetic field of 14 T as well as a small value of the mass susceptibility, here 10-5 cm3/g. The value of the Néel temperature, T N ≤ 8 K, and the Curie-Weiss temperature, θ CW ≤ -208 K, indicate a collinear antiferromagnetic (AFM) order. We suggest that neither the magnetism nor the Mo-content can be correlated with the resistivity anomalies. Therefore, these effects may rather be interpreted in terms of a small-polaron gas in the resistivity dip area. Alternatively, they could mark a lattice/electronic entropy-driven incomplete metal-insulator transition.

  8. Modelling the electrical resistivity response to CO2 plumes generated in a laboratory, cylindrical sandbox

    Science.gov (United States)

    Kremer, T.; Maineult, A. J.; Binley, A.; Vieira, C.; Zamora, M.

    2012-12-01

    CO2 capture and storage into deep geological formations is one of the main solutions proposed to reduce the concentration of anthropic CO2 in the atmosphere. The monitoring of injection sites is a crucial issue to assess for the long term viability of CO2 storage. With the intention of detecting potential leakages, we are investigating the possibility of using electrical resistivity tomography (ERT) techniques to detect CO2 transfers in the shallow sub-surface. ERT measurements were performed during a CO2 injection in a cylindrical tank filled with Fontainebleau sand and saturated with water. Several measurements protocols were tested. The inversion of the resistances measured with the software R3T (Binley and Kemna (2005)) clearly showed that the CO2 injection induces significant changes in the resistivity distribution of the medium, and that ERT has a promising potential for the detection and survey of CO2 transfers through unconsolidated saturated media. We modeled this experiment using Matlab by building a 3D cellular automaton that describes the CO2 spreading, following the geometric and stochastic approach described by Selker et al. (2007). The CO2 circulation is described as independents, circular and continuous gas channels whose horizontal spread depends on a Gaussian probability law. From the channel distribution we define the corresponding gas concentration distribution and calculate the resistivity of the medium by applying Archie's law for unsaturated conditions. The forward modelling was performed with the software R3T to convert the resistivity distribution into resistances values, each corresponding to one of the electrode arrays used in the experimental measurements. Modelled and measured resistances show a good correlation, except for the electrode arrays located at the top or the bottom of the tank. We improved the precision of the model by considering the effects due to CO2 dissolution in the water which increases the conductivity of the

  9. Quantitative impact of hydrothermal alteration on electrical resistivity in geothermal systems from a joint analysis of laboratory measurements and borehole data in Krafla area, N-E Iceland

    Science.gov (United States)

    Lévy, Léa; Páll Hersir, Gylfi; Flóvenz, Ólafur; Gibert, Benoit; Pézard, Philippe; Sigmundsson, Freysteinn; Briole, Pierre

    2016-04-01

    Rock permeability and fluid temperature are the two most decisive factors for a successful geothermal drilling. While those parameters are only measured from drilling, they might be estimated on the basis of their impact on electrical resistivity that might be imaged from surface soundings, for example through TEM (Transient Electro Magnetic) down to one km depth. The electrical conductivity of reservoir rocks is the sum of a volume term depending on fluid parameters and a surface term related to rock alteration. Understanding the link between electrical resistivity and geothermal key parameters requires the knowledge of hydrothermal alteration and its petrophysical signature with the Cation Exchange Capacity (CEC). Fluid-rock interactions related to hydrothermal circulation trigger the precipitation of alteration minerals, which are both witnesses of the temperature at the time of reaction and new paths for the electrical current. Alteration minerals include zeolites, smectites, chlorites, epidotes and amphiboles among which low temperatures parageneses are often the most conductive. The CEC of these mineral phases contributes to account for surface conductivity occuring at the water-rock interface. In cooling geothermal systems, these minerals constitute in petrophysical terms and from surface electrical conduction a memory of the equilibrium phase revealed from electrical probing at all scales. The qualitative impact of alteration minerals on resistivity structure has been studied over the years in the Icelandic geothermal context. In this work, the CEC impact on pore surfaces electrical conductivity is studied quantitatively at the borehole scale, where several types of volcanic rocks are mixed together, with various degrees of alteration and porosity. Five boreholes located within a few km at the Krafla volcano, Northeast Iceland, constitute the basis for this study. The deepest and reference hole, KJ-18, provides cuttings of rock and logging data down to 2215

  10. Sphaeropsidin A shows promising activity against drug-resistant cancer cells by targeting regulatory volume increase

    Science.gov (United States)

    Mathieu, Véronique; Chantôme, Aurélie; Lefranc, Florence; Cimmino, Alessio; Miklos, Walter; Paulitschke, Verena; Mohr, Thomas; Maddau, Lucia; Kornienko, Alexander; Berger, Walter; Vandier, Christophe; Evidente, Antonio; Delpire, Eric; Kiss, Robert

    2016-01-01

    Despite the recent advances in the treatment of tumors with intrinsic chemotherapy resistance, such as melanoma and renal cancers, their prognosis remains poor and new chemical agents with promising activity against these cancers are urgently needed. Sphaeropsidin A, a fungal metabolite whose anticancer potential had previously received little attention, was isolated from Diplodia cupressi and found to display specific anticancer activity in vitro against melanoma and kidney cancer subpanels in the National Cancer Institute (NCI) 60-cell line screen. The NCI data revealed a mean LC50 of ca. 10 μM and a cellular sensitivity profile that did not match that of any other agent in the 765,000 compound database. Subsequent mechanistic studies in melanoma and other multidrug-resistant in vitro cancer models showed that sphaeropsidin A can overcome apoptosis as well as multidrug resistance by inducing a marked and rapid cellular shrinkage related to the loss of intracellular Cl− and the decreased HCO3− concentration in the culture supernatant. These changes in ion homeostasis and the absence of effects on the plasma membrane potential were attributed to the sphaeropsidin A-induced impairment of regulatory volume increase (RVI). Preliminary results also indicate that depending on the type of cancer, the sphaeropsidin A effects on RVI could be related to Na–K–2Cl electroneutral cotransporter or Cl−/HCO3− anion exchanger(s) targeting. This study underscores the modulation of ion-transporter activity as a promising therapeutic strategy to combat drug-resistant cancers and identifies the fungal metabolite, sphaeropsidin A, as a lead to develop anticancer agents targeting RVI in cancer cells. PMID:25868554

  11. Electrical Resistivity Imaging of a Thin Clayey Aquitard Developed on Basement Rocks in Parts of Adekunle Ajasin University Campus, Akungba-Akoko, South-western Nigeria

    Directory of Open Access Journals (Sweden)

    Muslim B Aminu

    2015-05-01

    Full Text Available In this study, 2-dimensional electrical resistivity surveying has been used to reveal the nature and development of a thin clayey aquitard on basement complex rocks of the Adekunle Ajasin University campus, Akungba-Akoko south-western Nigeria. The aim was to evaluate the occurrence, geometry and groundwater viability of this clayey aquitard as an alternative source of water supply on the Campus. Prior, a hand-dug well, which supplied moderate volumes of water all year round, had been abstracting water from this aquitard. Three east-west geo-electric traverses were surveyed using the dipole-dipole array configuration with an electrode separation of 5 m and a maximum dipole length of 45 m. Each of the three traverses was 60 m long. The observed field data were inverted for subsurface 2D resistivity structure using a commercially available 2.5D finite element modelling inversion software. The clayey aquitard is imaged to exist as low resistivity response patterns which have developed in elongated trough-like depressions created as a result of deep weathering of the feldspar and amphibolite-rich sections of the basement rocks of the area. This clayey layer reaches a thickness of 10 m at the southern end of the survey and in some sections is compartmentalised into segments by basement rocks which have better resisted weathering. Where the topographic slope of the ground surface is low enough as to allow the accumulation of run-off, the clayey aquitard develops into visible marshy swamps. Although, clayey aquitards of this nature supply water at low rates, their capacity to store high volumes and to be available all-year-round could prove essential to ameliorating acute water shortages experienced in the area during the dry season.DOI: http://dx.doi.org/10.5755/j01.erem.71.1.9016

  12. Multiple pulse-heating experiments with different current to determine total emissivity, heat capacity, and electrical resistivity of electrically conductive materials at high temperatures.

    Science.gov (United States)

    Watanabe, Hiromichi; Yamashita, Yuichiro

    2012-01-01

    A modified pulse-heating method is proposed to improve the accuracy of measurement of the hemispherical total emissivity, specific heat capacity, and electrical resistivity of electrically conductive materials at high temperatures. The proposed method is based on the analysis of a series of rapid resistive self-heating experiments on a sample heated at different temperature rates. The method is used to measure the three properties of the IG-110 grade of isotropic graphite at temperatures from 850 to 1800 K. The problem of the extrinsic heating-rate effect, which reduces the accuracy of the measurements, is successfully mitigated by compensating for the generally neglected experimental error associated with the electrical measurands (current and voltage). The results obtained by the proposed method can be validated by the linearity of measured quantities used in the property determinations. The results are in reasonably good agreement with previously published data, which demonstrate the suitability of the proposed method, in particular, to the resistivity and total emissivity measurements. An interesting result is the existence of a minimum in the emissivity of the isotropic graphite at around 1120 K, consistent with the electrical resistivity results.

  13. The (RH+t) aging correlation. Electrical resistivity of PVB at various temperatures and relative humidities

    Science.gov (United States)

    Cuddihy, E. F.

    1985-01-01

    Electrical products having organic materials functioning as pottants, encapsulants, and insulation coatings are commonly exposed to elevated conditions of temperature and humidity. In order to assess service life potential from this method of accelerated aging, it was empirically observed that service life seems proportional to an aging correlation which is the sum of temperature in degrees Celsius (t), and the relative humidity (RH) expressed in percent. Specifically, the correlation involves a plot of time-to-failure on a log scale versus the variable RH + T plotted on a linear scale. A theoretical foundation is provided for this empirically observed correlation by pointing out that the correlation actually involves a relationship between the electrical resistivity (or conductivity) of the organic material, and the variable RH + t. If time-to-failure is a result of total number of coulombs conducted through the organic material, then the correlation of resistivity versus RH + t is synonymous with the empirical correlation of time-to-failure versus RH + t.

  14. Enhanced Strain-Dependent Electrical Resistance of Polyurethane Composites with Embedded Oxidized Multiwalled Carbon Nanotube Networks

    Directory of Open Access Journals (Sweden)

    R. Benlikaya

    2013-01-01

    Full Text Available The effect of different chemical oxidation of multiwalled carbon nanotubes with H2O2, HNO3, and KMnO4 on the change of electrical resistance of polyurethane composites with embedded oxidized nanotube networks subjected to elongation and bending has been studied. The testing has shown about twenty-fold increase in the electrical resistance for the composite prepared from KMnO4 oxidized nanotubes in comparison to the composites prepared from the pristine and other oxidized nanotubes. The evaluated sensitivity of KMnO4 treated composite in terms of the gauge factor increases with strain to nearly 175 at the strain 11%. This is a substantial increase, which ranks the composite prepared from KMnO4 oxidized nanotubes among materials as strain gauges with the highest electromechanical sensitivity. The observed differences in electromechanical properties of the composites are discussed on basis of their structure which is examined by the measurements of Fourier transform infrared spectroscopy, X-ray photoelectron spectroscopy, and scanning electron microscope. The possible practical use of the composites is demonstrated by monitoring of elbow joint flexion during two different physical exercises.

  15. Electrical Resistance and Acoustic Emission Measurements for Monitoring the Structural Behavior of CFRP Laminate

    KAUST Repository

    Zhou, Wei

    2015-07-12

    Electrical resistance and acoustic emission (AE) measurement are jointly used to monitor the degradation in CFRP laminates subjected to tensile tests. The objective of this thesis is to perform a synergertic analysis between a passive and an active methods to better access how these perform when used for Structural Health Moni- toring (SHM). Laminates with three different stacking sequences: [0]4, [02/902]s and [+45/ − 45]2s are subjected to monotonic and cyclic tensile tests. In each laminate, we carefully investigate which mechanisms of degradation can or cannot be detect- ed by each technique. It is shown that most often, that acoustic emission signals start before any electrical detection is possible. This is is explained based on the redundance of the electrical network that makes it less sensitive to localized damages. Based on in depth study of AE signals clustering, a new classification is proposed to recognize the different damage mechanims based on only two parameters: the RA (rise time/amplitude) and the duration of the signal.

  16. Monitoring solute fluxes: Integrating electrical resistivity with multi-compartment sampler techniques

    Science.gov (United States)

    Bloem, Esther; Fernandez, Perrine; French, Helen K.

    2016-04-01

    The impact of agriculture, industry, airport activities on soil and water quality is strongly influenced by soil heterogeneity. To improve risk assessment, monitoring, and treatment strategies, we require a better understanding of the effect of soil heterogeneity on contaminant movement and better methods for monitoring heterogeneous contaminated transport. Sufficient characterization of spatial and temporal distribution of contaminant transport requires measurements of water and solute fluxes at multiple locations with a high temporal resolution. During this presentation, we will show a newly developed instrument, which combines multi-compartment sampling with electrical resistivity measurements, to observe spatial and temporal fluxes of contaminants. Solute monitoring is often limited to observations of resident concentrations, while flux concentrations govern the movement of solutes in soils. Bloem et al. (2010) developed a multi-compartment sampler (MCS) which is capable of measuring fluxes at a high spatial resolution under natural conditions. The sampler is divided into 100 separate compartments of 31 by 31 mm. Flux data can be recorded at a high time resolution (every 5 minutes). Tracer leaching can be monitored by frequently sampling the collected leachate while leaving the sampler buried in situ. To optimize the monitoring of tracer leaching and measure real solute fluxes the multi-compartment sampler has been extended with 121 electrodes. The electrodes are mounted at each corner of each compartment to measure the electrical conductivity above each compartment while water percolates through the compartments. By using different electrode couples, the setup can also be used to image above the multi-compartment sampler. The instrument can be used for detailed studies both in the laboratory and in the field. For laboratory experiments a transparent column is used which fits perfect on top of the MCS. We present a selection of the integrated electrical

  17. Study on the electrical resistance of the sleeper-fastening elements system in railway tracks

    Directory of Open Access Journals (Sweden)

    Barroso, F. J.

    2012-09-01

    Full Text Available The electrical resistance of the sleeper-fastening elements system in a wet railway track is a very important parameter. This is because the rails are electric conductors in the circuit of signaling and traction systems. This electrical resistance, defined as a characteristic value of the sleeper-fastening elements-water system is a measurand obtained with reference measurement procedures as described in international standards. But it is subject to many kinds of undefinitions that result in a very high dispersion. In this work the dependence of this parameter on variables such as the water conductivity, the temperature and the relative humidity is shown, and several ways to reduce it to minimum values are also established.En vías de ferrocarril sometidas a condiciones medioambientales desfavorables la resistencia eléctrica del conjunto formado por una traviesa y el sistema de sujeción del raíl es un parámetro muy importante. Esto se debe a que los raíles actúan como conductores eléctricos en los sistemas de señalización y tracción. Esta resistencia eléctrica, definida como un valor característico del sistema traviesa-elementos de sujeción-agua se mide con procedimientos normalizados. Sin embargo estos procedimientos están sujetos a ciertas indefiniciones que provocan una elevada dispersión. En este trabajo se estudia la dependencia de este parámetro en variables tales como la conductividad del agua, la temperatura y la humedad relativa, y se establecen estrategias para reducir dicha dispersión a valores mínimos.

  18. Investigating Algal Reefs in Xinwu, Taiwan, by using Electrical Resistivity Tomography Method

    Science.gov (United States)

    Wu, Ping-Yun; Chen, Chien-Chih

    2017-04-01

    The Guanxin algal reef, which is locating along the coastal line of Guanyin and Xinwu districts in the Taoyuan city, is the biggest and most complete algal reef in Taiwan. It is consisted of the calcified crustose coralline algae and is one of the most important ecosystems on the northwestern coast. Algal reefs grow extremely slow and expand only 0.1 to 80 mm annually; as a result, any investigation in the algal reef area must be implemented very carefully to reduce potential influence on the environment. Reefs have special electrical property; therefore, it is suitable for applications of electrical exploration methods. The Electrical Resistivity Tomography (ERT) is a fast, non-destructive, and inexpensive surficial geophysical survey method, and therefore it is widely used to investigate reefs. In this study, we used ERT method to investigate the location, distribution area and depth of algal reefs in order to provide a reliable reference of coastal engineering and the establishment of ecosystem refuge. The study area is from the south coast of Fulin river to the south coast of Guanyin river. There are four ERT survey lines, three of them are 960m long and parallel to the shoreline, and the other one is 240m long and perpendicular to others. According to the Archie's Law, we calculated the porosity from the resistivity profile to estimate the depth of reefs beneath each survey line and verified the estimates with the data obtained from drilling well. The results show that the upper boundary of the algal reefs is 0-1.5m deep (there are sands above), and the lower boundary is 4-6m deep (there are gravels below) in the study area. In addition, all profiles obtained from the north-south survey lines show that the depth of the algal reef becomes shallower in the range of 100m in the southernmost end, which indicate the southern boundary of the reef distribution.

  19. An experimental and computational investigation of electrical resistivity imaging for prediction ahead of tunnel boring machines

    Science.gov (United States)

    Schaeffer, Kevin P.

    Tunnel boring machines (TBMs) are routinely used for the excavation of tunnels across a range of ground conditions, from hard rock to soft ground. In complex ground conditions and in urban environments, the TBM susceptible to damage due to uncertainty of what lies ahead of the tunnel face. The research presented here explores the application of electrical resistivity theory for use in the TBM tunneling environment to detect changing conditions ahead of the machine. Electrical resistivity offers a real-time and continuous imaging solution to increase the resolution of information along the tunnel alignment and may even unveil previously unknown geologic or man-made features ahead of the TBM. The studies presented herein, break down the tunneling environment and the electrical system to understand how its fundamental parameters can be isolated and tested, identifying how they influence the ability to predict changes ahead of the tunnel face. A proof-of-concept, scaled experimental model was constructed in order assess the ability of the model to predict a metal pipe (or rod) ahead of face as the TBM excavates through a saturated sand. The model shows that a prediction of up to three tunnel diameters could be achieved, but the unique presence of the pipe (or rod) could not be concluded with certainty. Full scale finite element models were developed in order evaluate the various influences on the ability to detect changing conditions ahead of the face. Results show that TBM/tunnel geometry, TBM type, and electrode geometry can drastically influence prediction ahead of the face by tens of meters. In certain conditions (i.e., small TBM diameter, low cover depth, large material contrasts), changes can be detected over 100 meters in front of the TBM. Various electrode arrays were considered and show that in order to better detect more finite differences (e.g., boulder, lens, pipe), the use of individual cutting tools as electrodes is highly advantageous to increase spatial

  20. Resistance modulation in VO2 nanowires induced by an electric field via air-gap gates

    Science.gov (United States)

    Kanki, Teruo; Chikanari, Masashi; Wei, Tingting; Tanaka, Hidekazu; The Institute of Scientific; Industrial Research Team

    Vanadium dioxide (VO2) shows huge resistance change with metal-insulator transition (MIT) at around room temperature. Controlling of the MIT by applying an electric field is a topical ongoing research toward the realization of Mott transistor. In this study, we have successfully switched channel resistance of VO2 nano-wire channels by a pure electrostatic field effect using a side-gate-type field-effect transistor (SG-FET) viaair gap and found that single crystalline VO2 nanowires and the channels with narrower width enhance transport modulation rate. The rate of change in resistance ((R0-R)/R, where R0 and R is the resistance of VO2 channel with off state and on state gate voltage (VG) , respectively) was 0.42 % at VG = 30 V in in-plane poly-crystalline VO2 channels on Al2O3(0001) substrates, while the rate in single crystalline channels on TiO2 (001) substrates was 3.84 %, which was 9 times higher than that using the poly-crystalline channels. With reducing wire width from 3000 nm to 400 nm of VO2 on TiO2 (001) substrate, furthermore, resistance modulation ratio enhanced from 0.67 % to 3.84 %. This change can not be explained by a simple free-electron model. In this presentation, we will compare the electronic properties between in-plane polycrystalline VO2 on Al2O3 (0001) and single crystalline VO2 on TiO2 (001) substrates, and show experimental data in detail..

  1. Electrical resistivity tomography applied to a complex lava dome: 2D and 3D models comparison

    Science.gov (United States)

    Portal, Angélie; Fargier, Yannick; Lénat, Jean-François; Labazuy, Philippe

    2015-04-01

    The study of volcanic domes growth (e.g. St. Helens, Unzen, Montserrat) shows that it is often characterized by a succession of extrusion phases, dome explosions and collapse events. Lava dome eruptive activity may last from days to decades. Therefore, their internal structure, at the end of the eruption, is complex and includes massive extrusions and lava lobes, talus and pyroclastic deposits as well as hydrothermal alteration. The electrical resistivity tomography (ERT) method, initially developed for environmental and engineering exploration, is now commonly used for volcano structure imaging. Because a large range of resistivity values is often observed in volcanic environments, the method is well suited to study the internal structure of volcanic edifices. We performed an ERT survey on an 11ka years old trachytic lava dome, the Puy de Dôme volcano (French Massif Central). The analysis of a recent high resolution DEM (LiDAR 0.5 m), as well as other geophysical data, strongly suggest that the Puy de Dôme is a composite dome. 11 ERT profiles have been carried out, both at the scale of the entire dome (base diameter of ~2 km and height of 400 m) on the one hand, and at a smaller scale on the summit part on the other hand. Each profile is composed of 64 electrodes. Three different electrode spacing have been used depending on the study area (35 m for the entire dome, 10 m and 5 m for its summit part). Some profiles were performed with half-length roll-along acquisitions, in order to keep a good trade-off between depth of investigation and resolution. Both Wenner-alpha and Wenner-Schlumberger protocols were used. 2-D models of the electrical resistivity distribution were computed using RES2DINV software. In order to constrain inversion models interpretation, the depth of investigation (DOI) method was applied to those results. It aims to compute a sensitivity index on inversion results, illustrating how the data influence the model and constraining models

  2. 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.

  3. Sulfate resistance of concrete containing high volume of mineral admixtures[ACI SP-234-37

    Energy Technology Data Exchange (ETDEWEB)

    Irassar, E.F. [Buenos Aires Central State Univ., Olavarria (Argentina). Dept. of Civil Engineering; Batic, O.R. [La Plata Univ., (Argentina)]|[Commission of Scientific Research of Buenos Aires (Argentina); Di Maio, A. [La Plata Technilogical Univ. (Argentina)]|[CONICET-LEMIT (Argentina); Ponce, J.M. [LEMIT-CIC (Argentina)]|[La Plata Univ. (Argentina). Faculty of Natural Sciences

    2006-07-01

    Various physical and chemical processes that influence the durability of concrete structures were discussed. For underground or on grade structures, the durability of concrete depends on the chemical composition of concrete and the concentration of ionic species present in the soil or groundwater, the permeability of soil, exposition to water, the flow of water, and the shape and size of structure. It also depends on the quality of concrete in terms of compaction, water to cementitious ratio, cementitious content, type of cementitious materials, and curing process. The rate and course of concrete deterioration also depends on environmental conditions such as low temperature, temperature cycles between day and night, and the relative humidity of ambient air. Durable foundations in a sulfate environment require a low permeability concrete in order to assure good compaction and curing procedures. The type of cementitious material is also important in preventing deterioration. This paper summarized 15 years of results related to the effect of high volume mineral admixtures on the sulfate resistance of concrete. A mechanism of concrete degradation was presented based on macroscopic and microscopic behaviour. The physical and chemical attack produced by sulfate soils was emphasized. The presentation outlined the materials used, mixture proportions, curing, exposure conditions, inspection, compressive strength test methods and microstructural analyses. It was shown that a combination of portland cement with a high volume of appropriate fly ash, natural pozzolan or granulated blast-furnace slag provides an excellent performance for concrete structures buried in harsh alkali sulfate soils. Concretes with high volume of mineral admixtures are more susceptible to the physical salt attack caused by cycles of wetting and drying that produce progressive scaling and mass loss. 21 refs., 3 tabs., 11 figs.

  4. Imaging Saltwater Intrusion Along the Coast of Monterey Bay Using Long-Offset Electrical Resistivity Tomography

    Science.gov (United States)

    Goebel, M.; Knight, R. J.; Pidlisecky, A.

    2016-12-01

    Coastal regions represent a complex dynamic interface where saltwater intrusion moves seawater landward and groundwater discharge moves freshwater seaward. These processes can have a dramatic impact on water quality, affecting both humans and coastal ecosystems. The ability to map the subsurface distribution of fresh and salt water is a critical step in predicting and managing water quality in coastal regions. This is commonly accomplished using wells, which are expensive and provide point information, which may fail to capture the spatial complexity in subsurface conditions. We present an alternate method for acquiring data, long-offset Electrical Resistivity Tomography (ERT), which is non-invasive, cost effective, and can address the problem of poor spatial sampling. This geophysical method can produce continuous profiles of subsurface electrical resistivity to a depth of 300 m, with spatial resolution on the order of tens of meters. Our research focuses on the Monterey Bay region, where sustained groundwater extraction over the past century has led to significant saltwater intrusion. ERT was acquired along 40 kilometers of the coast using the roll along method, allowing for continuous overlap in data acquisition. Electrodes were spaced every 22.2 m, with a total of 81 electrodes along the 1.8 km active cable length. The data show a complex distribution of fresh and salt water, influenced by geology, groundwater pumping, recharge, and land-use. While the inverted ERT resistivity profiles correspond well with existing data sets and geologic interpretations in the region, the spatial complexity revealed through the ERT data goes beyond what is known from traditional data sources alone. This leads us to conclude that this form of data can be extremely useful in informing and calibrating groundwater flow models, making targeted management decisions, and monitoring changes in subsurface salinities over time.

  5. Near-Surface Fault Structures of the Seulimuem Segment Based on Electrical Resistivity Model

    Science.gov (United States)

    Ismail, Nazli; Yanis, Muhammad; Idris, Syafrizal; Abdullah, Faisal; Hanafiah, Bukhari

    2017-05-01

    The Great Sumatran Fault (GSF) system is arc-parallel strike-slip fault system along the volcanic front related to the oblique subduction of the oceanic Indo-Australian plate. Large earthquakes along the southern GSF since 1892 have been reported, but the Seulimuem segment at the northernmost Sumatran has not produced large earthquakes in the past 100 years. The 200-km-long segment is considered to be a seismic gap. Detailed geological study of the fault and thus its surface trace locations, late Quaternary slip rate, and rupture history are urgently needed for earthquake disaster mitigation in the future. However, finding a suitable area for paleoseismic trenching is an obstacle when the fault traces are not clearly shown on the surface. We have conducted geoelectrical measurement in Lamtamot area of Aceh Besar District in order to locate the fault line for paleoseismic excavation. Apparent resistivity data were collected along 40 m profile parallel to the planned trenching site. The 2D electrical resistivity model provided evidence of some resistivity anomalies by high lateral contrast. This anomaly almost coincides with the topographic scarp which is modified by agriculture on the surface at the northern part of Lamtamot. The steep dipping electrical contrast may correspond to a fault. However, the model does not resolve well evidences from minor faults that can be related to the presence of surface ruptures. A near fault paleoseismic investigation requires trenching across the fault in order to detect and analyze the geological record of the past large earthquakes along the Seulimuem segment.

  6. Acute Response to Unilateral Unipolar Electrical Carotid Sinus Stimulation in Patients With Resistant Arterial Hypertension.

    Science.gov (United States)

    Heusser, Karsten; Tank, Jens; Brinkmann, Julia; Menne, Jan; Kaufeld, Jessica; Linnenweber-Held, Silvia; Beige, Joachim; Wilhelmi, Mathias; Diedrich, André; Haller, Hermann; Jordan, Jens

    2016-03-01

    Bilateral bipolar electric carotid sinus stimulation acutely reduced muscle sympathetic nerve activity (MSNA) and blood pressure (BP) in patients with resistant arterial hypertension but is no longer available. The second-generation device uses a smaller unilateral unipolar disk electrode to reduce invasiveness while saving battery life. We hypothesized that the second-generation device acutely lowers BP and MSNA in treatment-resistant hypertensive patients. Eighteen treatment-resistant hypertensive patients (9 women/9 men; 53±11 years; 33±5 kg/m(2)) on stable medications have been included in the study. We monitored finger and brachial BP, heart rate, and MSNA. Without stimulation, BP was 165±31/91±18 mm Hg, heart rate was 75±17 bpm, and MSNA was 48±14 bursts per minute. Acute stimulation with intensities producing side effects that were tolerable in the short term elicited interindividually variable changes in systolic BP (-16.9±15.0 mm Hg; range, 0.0 to -40.8 mm Hg; P=0.002), heart rate (-3.6±3.6 bpm; P=0.004), and MSNA (-2.0±5.8 bursts per minute; P=0.375). Stimulation intensities had to be lowered in 12 patients to avoid side effects at the expense of efficacy (systolic BP, -6.3±7.0 mm Hg; range, 2.8 to -14.5 mm Hg; P=0.028 and heart rate, -1.5±2.3 bpm; P=0.078; comparison against responses with side effects). Reductions in diastolic BP and MSNA (total activity) were correlated (r(2)=0.329; P=0.025). In our patient cohort, unilateral unipolar electric baroreflex stimulation acutely lowered BP. However, side effects may limit efficacy. The approach should be tested in a controlled comparative study.

  7. Subsonic Ultra Green Aircraft Research: Phase 2. Volume 2; Hybrid Electric Design Exploration

    Science.gov (United States)

    Bradley, Marty K.; Droney, Christopher K.

    2015-01-01

    This report summarizes the hybrid electric concept design, analysis, and modeling work accomplished by the Boeing Subsonic Ultra Green Aircraft Research (SUGAR) team, consisting of Boeing Research and Technology, Boeing Commercial Airplanes, General Electric, and Georgia Tech.Performance and sizing tasks were conducted for hybrid electric versions of a conventional tube-and-wing aircraft and a hybrid wing body. The high wing Truss Braced Wing (TBW) SUGAR Volt was updated based on results from the TBW work (documented separately) and new engine performance models. Energy cost and acoustic analyses were conducted and technology roadmaps were updated for hybrid electric and battery technology. NOx emissions were calculated for landing and takeoff (LTO) and cruise. NPSS models were developed for hybrid electric components and tested using an integrated analysis of superconducting and non-superconducting hybrid electric engines. The hybrid electric SUGAR Volt was shown to produce significant emissions and fuel burn reductions beyond those achieved by the conventionally powered SUGAR High and was able to meet the NASA goals for fuel burn. Total energy utilization was not decreased but reduced energy cost can be achieved for some scenarios. The team was not able to identify a technology development path to meet NASA's noise goals

  8. Effects of Soil Moisture Content on Groundwater Electrical Resistivity Values in Irrigation Paddy Scheme, Tanjong Karang, Malaysia

    Directory of Open Access Journals (Sweden)

    Nurmala Sari

    2014-01-01

    Full Text Available Electrical Resistivity Tomography (ERT analyses have been conducted in Irrigation Paddy Scheme, Tanjong Karang, Malaysia as part of investigation on groundwater potential aquifer to provide an alternative water resource for paddy irrigation. Based on recent studies on groundwater resistivity in paddy field, irrigation system mentioned as soil moisture content was observed to affect the value of electrical resistivity and subsurface geological profile resulted from ERT analysis. The objective of this study was to proof any correlation between soil moisture content and electrical resistivity values and to determine at what level of soil moisture content which will be the best condition to conduct ERT survey. ERT analysis was conducted by using ABEM Terrameter SAS 4000 of Wenner-Schlumberger array with 5.0 meter and 10.0 meter for minimum and maximum electrode spacing. Visually, based on subsurface geological profile resulted from ERT analysis soil moisture content affected (changed electrical resistivity values. With all different treatments of soil moisture ranged from 16.96% to 27.50%, electrical resistivity values decreased in certain points and in certain depth along with the increase of soil moisture content. This was proofed by ANOVA and Duncan’s multiple range tests showing that Pr > F value was less than 0.0001. Further on Chi-square test showed that at soil moisture level of 22.54%, it was the best condition which gave more correct counts of electrical resistivity values compared to well lithology. This was assumed to be the best condition to conduct ERT survey.

  9. Developing hydropower in Washington state. Volume 2: An electricity marketing manual

    Science.gov (United States)

    James, J. W.; McCoy, G. A.

    1982-03-01

    An electricity marketing manual for the potential small and micro-hydroelectric project developer within the state of Washington is presented. Public utility regulatory policies (PURPA) requires electric utilities to interconnect with and pay a rate based on their full avoided costs for the purchase of electrical output from qualifying small power production facilities. The determination of avoided costs, as business organizational considerations, utility interface concerns, interconnection requirements, metering options, and liability and wheeling are discussed. The utility responses are summarized, legislation which is of importance to hydropower developers and the powers and functions of the authorities responsible for enforcing the mandate of PURPA are described.

  10. In situ measurement system of electric resistivity for outcrop investigation; Roto de shiyodekiru denkihi teiko keisoku system

    Energy Technology Data Exchange (ETDEWEB)

    Nakagawa, K.; Tamura, T. [Osaka City Univ., Osaka (Japan). Faculty of Science; Morikawa, T. [Osaka Prefectural Government, Osaka (Japan)

    1997-05-27

    A simplified electrical resistivity measuring device has been developed as a trial for field and laboratory uses, and some measurements were conducted. For this device, four probe electrodes are penetrated in the clay specimen, to calculate the resistivity from the voltage between both ends of the reference resistance connected with current electrodes in a series and the voltage between intermediate two voltage electrodes. It can be used in the field measurements. For the measurements, specimens of marine and lacustrine clayey sediments with clear stratigraphic levels in southern Osaka Group were used. In the laboratory, in addition to basic physical tests, diatom analysis and measurements of conductivity of clay suspension were also conducted. As a result of the experiments, the electric resistivity of marine clay obtained at the outcrop was lower than lacustrine clay as expected. The value of the former was a half of that of the latter. The frequency dependence in the high frequency region above 1 MHz was the reverse. The difference in electrical resistivity values between non-agitated specimens was about four times. The electrical resistivity of clay suspensions varied in two orders. 3 refs., 9 figs.

  11. Electrical Resistance of SiC/SiC Ceramic Matrix Composites for Damage Detection and Life-Prediction

    Science.gov (United States)

    Smith, Craig; Morscher, Gregory; Xia, Zhenhai

    2009-01-01

    Ceramic matrix composites (CMC) are suitable for high temperature structural applications such as turbine airfoils and hypersonic thermal protection systems due to their low density high thermal conductivity. The employment of these materials in such applications is limited by the ability to accurately monitor and predict damage evolution. Current nondestructive methods such as ultrasound, x-ray, and thermal imaging are limited in their ability to quantify small scale, transverse, in-plane, matrix cracks developed over long-time creep and fatigue conditions. CMC is a multifunctional material in which the damage is coupled with the material s electrical resistance, providing the possibility of real-time information about the damage state through monitoring of resistance. Here, resistance measurement of SiC/SiC composites under mechanical load at both room temperature monotonic and high temperature creep conditions, coupled with a modal acoustic emission technique, can relate the effects of temperature, strain, matrix cracks, fiber breaks, and oxidation to the change in electrical resistance. A multiscale model can in turn be developed for life prediction of in-service composites, based on electrical resistance methods. Results of tensile mechanical testing of SiC/SiC composites at room and high temperatures will be discussed. Data relating electrical resistivity to composite constituent content, fiber architecture, temperature, matrix crack formation, and oxidation will be explained, along with progress in modeling such properties.

  12. Landslide Monitoring in Southwestern China via Time-lapse Electrical Resistivity Tomography

    Science.gov (United States)

    Xu, D.; Hu, X.; Shan, C.

    2016-12-01

    The dynamic monitoring of landslides in engineering geology has focused on the correlation among landslide stability, rainwater infiltration, and subsurface hydrogeology. However, the understanding of this complicated correlation is still poor and inadequate. Thus, in this study, we investigated a typical landslide in southwestern China via time-lapse electrical resistivity tomography (TLERT) in November 2013, August 2014 and May 2016. From the data, shallow sediments showed short-term resistivity variability due to evaporation and rainfall, whereas deep zone exhibited seasonal fluctuations related to dry season, rainy season and snow melting during springtime. We also studied landslide mechanisms based on the spatiotemporal characteristics of surface water infiltration and flow within the landslide body. Combined with borehole data, inverted resistivity models accurately defined the interface between Quaternary sediments and bedrock. Preferential flow pathways attributed to fracture zones and fissures were also delineated. In addition, we found that surface water permeates through these pathways into the slipping mass and drains away as fissure water in the fractured bedrock, probably causing the weakly weathered layer to gradually soften and erode, eventually leading to a landslide. Clearly, TLERT dynamic monitoring can provide precursory information of critical sliding and can be used in landslide stability analysis and prediction.

  13. An analytical model and parametric study of electrical contact resistance in proton exchange membrane fuel cells

    Science.gov (United States)

    Wu, Zhiliang; Wang, Shuxin; Zhang, Lianhong; Hu, S. Jack

    This paper presents an analytical model of the electrical contact resistance between the carbon paper gas diffusion layers (GDLs) and the graphite bipolar plates (BPPs) in a proton exchange membrane (PEM) fuel cell. The model is developed based on the classical statistical contact theory for a PEM fuel cell, using the same probability distributions of the GDL structure and BPP surface profile as previously described in Wu et al. [Z. Wu, Y. Zhou, G. Lin, S. Wang, S.J. Hu, J. Power Sources 182 (2008) 265-269] and Zhou et al. [Y. Zhou, G. Lin, A.J. Shih, S.J. Hu, J. Power Sources 163 (2007) 777-783]. Results show that estimates of the contact resistance compare favorably with experimental data by Zhou et al. [Y. Zhou, G. Lin, A.J. Shih, S.J. Hu, J. Power Sources 163 (2007) 777-783]. Factors affecting the contact behavior are systematically studied using the analytical model, including the material properties of the two contact bodies and factors arising from the manufacturing processes. The transverse Young's modulus of chopped carbon fibers in the GDL and the surface profile of the BPP are found to be significant to the contact resistance. The factor study also sheds light on the manufacturing requirements of carbon fiber GDLs for a better contact performance in PEM fuel cells.

  14. An analytical model and parametric study of electrical contact resistance in proton exchange membrane fuel cells

    Energy Technology Data Exchange (ETDEWEB)

    Wu, Zhiliang; Wang, Shuxin; Zhang, Lianhong [School of Mechanical Engineering, Tianjin University, Tianjin 300072 (China); Hu, S. Jack [Department of Mechanical Engineering, The University of Michigan, Ann Arbor, MI 48109-2125 (United States)

    2009-04-15

    This paper presents an analytical model of the electrical contact resistance between the carbon paper gas diffusion layers (GDLs) and the graphite bipolar plates (BPPs) in a proton exchange membrane (PEM) fuel cell. The model is developed based on the classical statistical contact theory for a PEM fuel cell, using the same probability distributions of the GDL structure and BPP surface profile as previously described in Wu et al. [Z. Wu, Y. Zhou, G. Lin, S. Wang, S.J. Hu, J. Power Sources 182 (2008) 265-269] and Zhou et al. [Y. Zhou, G. Lin, A.J. Shih, S.J. Hu, J. Power Sources 163 (2007) 777-783]. Results show that estimates of the contact resistance compare favorably with experimental data by Zhou et al. [Y. Zhou, G. Lin, A.J. Shih, S.J. Hu, J. Power Sources 163 (2007) 777-783]. Factors affecting the contact behavior are systematically studied using the analytical model, including the material properties of the two contact bodies and factors arising from the manufacturing processes. The transverse Young's modulus of chopped carbon fibers in the GDL and the surface profile of the BPP are found to be significant to the contact resistance. The factor study also sheds light on the manufacturing requirements of carbon fiber GDLs for a better contact performance in PEM fuel cells. (author)

  15. Fabrication of pixilated architecture large panel organic flexible solar cell by reducing bulk electrical resistance

    Science.gov (United States)

    Panag, Jasmeet Singh

    This study investigates experimentally the photovoltaic behavior and performance of a new pixilated architecture of large organic photovoltaic panels made of a large array of high-aspect ratio three-dimensional pillars surrounded by a matrix of polymer photoactive material. A least addressed problem in organic and thin-film solar cells is the high bulk resistance of cathodic and anodic layers that result in drastic reduction of currents and power conversion efficiency (PCE). For such panels to be practical and commercially competitive, this huge bulk-resistance has to be minimized as much as possible. In this study, therefore, we introduce a new novel architecture that essentially compartmentalizes large panels into smaller modules that are connected to each other in a parallel fashion. In this architecture, the metal cathode layer is applied on the top as a series of lines whereas the anodic layer is independently connected to the pixilated cells at the bottom. As a result, these modules act like independent pixel cells wherein the damage from process and operation is limited individual pixel cells. The factors considered in validating the pixilated architecture presented here consisted of effect of number of pixels on efficiency and bulk electrical resistance. In addition, the study shows that pixilated architecture offers more uniform photoactive layers, and hence better photovoltaic performance because of the compartmentalization.

  16. Small scale monitoring of a bioremediation barrier using miniature electrical resistivity tomography

    Science.gov (United States)

    Sentenac, Philippe; Hogson, Tom; Keenan, Helen; Kulessa, Bernd

    2015-04-01

    The aim of this study was to assess, in the laboratory, the efficiency of a barrier of oxygen release compound (ORC) to block and divert a diesel plume migration in a scaled aquifer model using miniature electrical resistivity tomography (ERT) as the monitoring system. Two plumes of contaminant (diesel) were injected in a soil model made of local sand and clay. The diesel plumes migration was imaged and monitored using a miniature resistivity array system that has proved to be accurate in soil resistivity variations in small-scaled models of soil. ERT results reflected the lateral spreading and diversion of the diesel plumes in the unsaturated zone. One of the contaminant plumes was partially blocked by the ORC barrier and a diversion and reorganisation of the diesel in the soil matrix was observed. The technique of time-lapse ERT imaging showed that a dense non-aqueous phase liquid (DNAPL) contaminant like diesel can be monitored through a bioremediation barrier and the technique is well suited to monitor the efficiency of the barrier. Therefore, miniature ERT as a small-scale modelling tool could complement conventional techniques, which require more expensive and intrusive site investigation prior to remediation.

  17. Electrical resistivity of substitutionally disordered hcp Fe-Si and Fe-Ni alloys: Chemically-induced resistivity saturation in the Earth's core

    Science.gov (United States)

    Gomi, Hitoshi; Hirose, Kei; Akai, Hisazumi; Fei, Yingwei

    2016-10-01

    The thermal conductivity of the Earth's core can be estimated from its electrical resistivity via the Wiedemann-Franz law. However, previously reported resistivity values are rather scattered, mainly due to the lack of knowledge with regard to resistivity saturation (violations of the Bloch-Grüneisen law and the Matthiessen's rule). Here we conducted high-pressure experiments and first-principles calculations in order to clarify the relationship between the resistivity saturation and the impurity resistivity of substitutional silicon in hexagonal-close-packed (hcp) iron. We measured the electrical resistivity of Fe-Si alloys (iron with 1, 2, 4, 6.5, and 9 wt.% silicon) using four-terminal method in a diamond-anvil cell up to 90 GPa at 300 K. We also computed the electronic band structure of substitutionally disordered hcp Fe-Si and Fe-Ni alloy systems by means of Korringa-Kohn-Rostoker method with coherent potential approximation (KKR-CPA). The electrical resistivity was then calculated from the Kubo-Greenwood formula. These experimental and theoretical results show excellent agreement with each other, and the first principles results show the saturation behavior at high silicon concentration. We further calculated the resistivity of Fe-Ni-Si ternary alloys and found the violation of the Matthiessen's rule as a consequence of the resistivity saturation. Such resistivity saturation has important implications for core dynamics. The saturation effect places the upper limit of the resistivity, resulting in that the total resistivity value has almost no temperature dependence. As a consequence, the core thermal conductivity has a lower bound and exhibits a linear temperature dependence. We predict the electrical resistivity at the top of the Earth's core to be 1.12 ×10-6 Ωm, which corresponds to the thermal conductivity of 87.1 W/m/K. Such high thermal conductivity suggests high isentropic heat flow, leading to young inner core age (<0.85 Gyr old) and high initial

  18. National Economic Value Assessment of Plug-in Electric Vehicles: Volume I

    Energy Technology Data Exchange (ETDEWEB)

    Melaina, Marc [National Renewable Energy Lab. (NREL), Golden, CO (United States); Bush, Brian [National Renewable Energy Lab. (NREL), Golden, CO (United States); Eichman, Joshua [National Renewable Energy Lab. (NREL), Golden, CO (United States); Wood, Eric [National Renewable Energy Lab. (NREL), Golden, CO (United States); Stright, Dana [National Renewable Energy Lab. (NREL), Golden, CO (United States); Krishnan, Venkat [National Renewable Energy Lab. (NREL), Golden, CO (United States); Keyser, David [National Renewable Energy Lab. (NREL), Golden, CO (United States); Mai, Trieu [National Renewable Energy Lab. (NREL), Golden, CO (United States); McLaren, Joyce [National Renewable Energy Lab. (NREL), Golden, CO (United States)

    2016-12-01

    The adoption of plug-in electric vehicles (PEVs) can reduce household fuel expenditures by substituting electricity for gasoline while reducing greenhouse gas emissions and petroleum imports. A scenario approach is employed to provide insights into the long-term economic value of increased PEV market growth across the United States. The analytic methods estimate fundamental costs and benefits associated with an economic allocation of PEVs across households based upon household driving patterns, projected vehicle cost and performance attributes, and simulations of a future electricity grid. To explore the full technological potential of PEVs and resulting demands on the electricity grid, very high PEV market growth projections from previous studies are relied upon to develop multiple future scenarios.

  19. The record of electrical and communication engineering conversazione Tohoku University Volume 63, No. 3

    Science.gov (United States)

    1995-05-01

    English abstracts contained are from papers authored by the research staff of the Research Institute of Electrical Communication and the departments of Electrical Engineering, Electrical Communications, Electronic Engineering, and Information Engineering, Tohoku University, which originally appeared in scientific journals in 1994. The abstracts are organized under the following disciplines: electromagnetic theory; physics; fundamental theory of information; communication theory and systems; signal and image processing; systems control; computers; artificial intelligence; recording; acoustics and speech; ultrasonic electronics; antenna, propagation, and transmission; optoelectronics and optical communications; quantum electronics; superconducting materials and applications; magnetic materials and magnetics; semiconductors; electronic materials and parts; electronic devices and integrated circuits; electronic circuits; medical electronics and bionics; measurements and applied electronics; electric power; and miscellaneous.

  20. Sensitivity of Deep-Towed Marine Electrical Resistivity Imaging Using Two-Dimensional Inversion: A Case Study on Methane Hydrate

    Directory of Open Access Journals (Sweden)

    Chih-Wen Chiang

    2012-01-01

    Full Text Available Uncertain physical properties of methane hydrate (MH above a bottom simulating reflector should be estimated for detecting MH-bearing formations. In contrast to general marine sediments, MH-bearing formations have a relatively high electrical resistivity. Therefore, marine electrical resistivity imaging (MERI is a well-suited method for MH exploration. The authors conducted sensitivity testing of sub-seafloor MH exploration using a two-dimensional (2D inversion algorithm with the Wenner, Pole-Dipole (PD and Dipole-Dipole (DD arrays. The results of the Wenner electrode array show the poorest resolution in comparison to the PD and DD arrays. The results of the study indicate that MERI is an effective geophysical method for exploring the sub-seafloor electrical structure and specifically for delineating resistive anomalies that may be present because of MH-bearing formations at a shallow depth beneath the seafloor.

  1. Electrical Resistance of Nb3Sn/Cu Splices Produced by Electromagnetic Pulse Technology and Soft Soldering

    CERN Document Server

    Schoerling, D; Scheuerlein, C; Atieh, S; Schaefer, R

    2011-01-01

    The electrical interconnection of Nb3Sn/Cu strands is a key issue for the construction of Nb3Sn based damping ring wigglers and insertion devices for third generation light sources. We compare the electrical resistance of Nb3Sn/Cu splices manufactured by solid state welding using Electromagnetic Pulse Technology (EMPT) with that of splices produced by soft soldering with two different solders. The resistance of splices produced by soft soldering depends strongly on the resistivity of the solder alloy at the operating temperature. By solid state welding splice resistances below 10 nOhm can be achieved with 1 cm strand overlap length only, which is about 4 times lower than the resistance of Sn96Ag4 soldered splices with the same overlap length. The comparison of experimental results with Finite Element simulations shows that the electrical resistance of EMPT welded splices is determined by the resistance of the stabilizing copper between the superconducting filaments and confirms that welding of the strand matr...

  2. Microgravity and Electrical Resistivity Techniques for Detection of Caves and Clandestine Tunnels

    Science.gov (United States)

    Crawford, N. C.; Croft, L. A.; Cesin, G. L.; Wilson, S.

    2006-05-01

    The Center for Cave and Karst Studies, CCKS, has been using microgravity to locate caves from the ground's surface since 1985. The geophysical subsurface investigations began during a period when explosive and toxic vapors were rising from the karst aquifer under Bowling Green into homes, businesses, and schools. The USEPA provided the funding for this Superfund Emergency, and the CCKS was able to drill numerous wells into low-gravity anomalies to confirm and even map the route of caves in the underlying limestone bedrock. In every case, a low-gravity anomaly indicated a bedrock cave, a cave with a collapsed roof or locations where a bedrock cave had collapsed and filled with alluvium. At numerous locations, several wells were cored into microgravity anomalies and in every case, additional wells were drilled on both sides of the anomalies to confirm that the technique was in fact reliable. The wells cored on both sides of the anomalies did not intersect caves but instead intersected virtually solid limestone. Microgravity also easily detected storm sewers and even sanitary sewers, sometimes six meters (twenty feet) beneath the surface. Microgravity has also been used on many occasions to investigate sinkhole collapses. It identified potential collapse areas by detecting voids in the unconsolidated material above bedrock. The system will soon be tested over known tunnels and then during a blind test along a section of the U.S. border at Nogales, Arizona. The CCKS has experimented with other geophysical techniques, particularly ground penetrating radar, seismic and electrical resistivity. In the late 1990s the CCKS started using the Swift/Sting resistivity meter to perform karst geophysical subsurface investigations. The system provides good depth to bedrock data, but it is often difficult to interpret bedrock caves from the modeled data. The system typically used now by the CCKS to perform karst subsurface investigations is to use electrical resistivity traverses

  3. On the computation of a retina resistivity profile for applications in multi-scale modeling of electrical stimulation and absorption

    Science.gov (United States)

    Loizos, Kyle; RamRakhyani, Anil Kumar; Anderson, James; Marc, Robert; Lazzi, Gianluca

    2016-06-01

    This study proposes a methodology for computationally estimating resistive properties of tissue in multi-scale computational models, used for studying the interaction of electromagnetic fields with neural tissue, with applications to both dosimetry and neuroprosthetics. Traditionally, models at bulk tissue- and cellular-level scales are solved independently, linking resulting voltage from existing resistive tissue-scale models as extracellular sources to cellular models. This allows for solving the effects that external electric fields have on cellular activity. There are two major limitations to this approach: first, the resistive properties of the tissue need to be chosen, of which there are contradicting measurements in literature; second, the measurements of resistivity themselves may be inaccurate, leading to the mentioned contradicting results found across different studies. Our proposed methodology allows for constructing computed resistivity profiles using knowledge of only the neural morphology within the multi-scale model, resulting in a practical implementation of the effective medium theory; this bypasses concerns regarding the choice of resistive properties and accuracy of measurement setups. A multi-scale model of retina is constructed with an external electrode to serve as a test bench for analyzing existing and resulting resistivity profiles, and validation is presented through the reconstruction of a published resistivity profile of retina tissue. Results include a computed resistivity profile of retina tissue for use with a retina multi-scale model used to analyze effects of external electric fields on neural activity.

  4. Exploration of resistive targets within shallow marine environments using the circular electrical dipole and the differential electrical dipole methods: a time-domain modelling study

    Science.gov (United States)

    Haroon, Amir; Mogilatov, Vladimir; Goldman, Mark; Bergers, Rainer; Tezkan, Bülent

    2016-05-01

    Two novel transient controlled source electromagnetic methods called circular electrical dipole (CED) and differential electrical dipole (DED) are theoretically analysed for applications in shallow marine environments. 1-D and 3-D time-domain modelling studies are used to investigate the detectability and applicability of the methods when investigating resistive layers/targets representing hydrocarbon-saturated formations. The results are compared to the conventional time-domain horizontal electrical dipole (HED) and vertical electrical dipole (VED) sources. The applied theoretical modelling studies demonstrate that CED and DED have higher signal detectability towards resistive targets compared to TD-CSEM, but demonstrate significantly poorer signal amplitudes. Future CED/DED applications will have to solve this issue prior to measuring. Furthermore, the two novel methods have very similar detectability characteristics towards 3-D resistive targets embedded in marine sediments as VED while being less susceptible towards non-verticality. Due to the complex transmitter design of CED/DED the systems are prone to geometrical errors. Modelling studies show that even small transmitter inaccuracies have strong effects on the signal characteristics of CED making an actual marine application difficult at the present time. In contrast, the DED signal is less affected by geometrical errors in comparison to CED and may therefore be more adequate for marine applications.

  5. Consolidation of iron powder by electrical resistance sintering; Consolidacion de polvo de hierro mediante sinterizacion por resistencia electrica

    Energy Technology Data Exchange (ETDEWEB)

    Montes, J. M.; Rodriguez, J. A.; Herrera, E. J.

    2003-07-01

    A particular kind of hot pressing, in which the powder mass, subjected to pressure, is simultaneously heated by passing through a high-intensity electrical current is described and analysed. Commercial iron powder was used for the experimental work. Special emphasis is given to the densification kinetics. A qualitative microscopic interpretation of densification rate is suggested, based on the hypothesis of partial formation and rapid solidification of liquid phase. This interpretation is supported by the evolution of global porosity and electrical resistance of specimens during the electrical sintering process. The microstructural characteristics of compacts consolidated in the conventional way (cold pressing and furnace sintering) and by electrical resistance sintering are compared. (Author) 18 refs.

  6. Role of volume-regulated and calcium-activated anion channels in cell volume homeostasis, cancer and drug resistance

    DEFF Research Database (Denmark)

    Hoffmann, Else Kay; Sørensen, Belinda Halling; Sauter, Daniel Rafael Peter

    2015-01-01

    to be an essential component of both VRAC and VSOAC. Reduced VRAC and VSOAC activities are seen in drug resistant cancer cells. ANO1 is a calcium-activated chloride channel expressed on the plasma membrane of e.g. secretory epithelia. ANO1 is amplified and highly expressed in a large number of carcinomas. The gene...... functions as well as their role in cancer and drug resistance....

  7. Comparison of combined-field and electric-field volume integral equations for modelling double-negative metematerial antennas and scatterers

    DEFF Research Database (Denmark)

    Kim, Oleksiy S.; Breinbjerg, Olav

    2008-01-01

    Two volume integral equation formulations for modelling magneto-dielectric objects are compared in terms of accuracy and computational efficiency. The first is the combined-field integral equation (CFVIE), in which the unknown quantities are both the electric and magnetic fields, while the second...... is the electric-field integral equation (EFVIE) with a single unknown quantity - the electric field. A resonant double-negative metamaterial spherical shell is analysed as an example....

  8. Comparison of combined-field and electric-field volume integral equations for modelling double-negative metematerial antennas and scatterers

    DEFF Research Database (Denmark)

    Kim, Oleksiy S.; Breinbjerg, Olav

    2008-01-01

    Two volume integral equation formulations for modelling magneto-dielectric objects are compared in terms of accuracy and computational efficiency. The first is the combined-field integral equation (CFVIE), in which the unknown quantities are both the electric and magnetic fields, while the second...... is the electric-field integral equation (EFVIE) with a single unknown quantity - the electric field. A resonant double-negative metamaterial spherical shell is analysed as an example....

  9. Electrical Resistivity and Seismic Surveys at the Nevada Test Site, Nevada, April 2007

    Energy Technology Data Exchange (ETDEWEB)

    Seth S. Haines; Bethany L. Burton; Donald S. Sweetkind; Theodore H. Asch

    2009-03-30

    In April 2007, the USGS collected direct-current (DC) electrical resistivity data and shear- (S) and compressional- (P) wave seismic data to provide new detail of previously mapped, overlapping fault splays at two administrative areas in the Nevada Test Site (NTS). In NTS Area 7, we collected two-dimensional DC resistivity data along a transect crossing the Yucca Fault parallel to, and between, two transects along which resistivity data were collected in a previous study in 2006. In addition, we collected three-dimensional DC resistivity data in a grid that overlies part of the 2007 transect. The DC resistivity data show that the fault has a footwall that is more conductive than the hanging wall and an along-strike progression of the fault in a location where overlapping splays are present. Co-located with the northernmost of the two 2006 DC resistivity transects, we acquired S- and P-wave seismic data for both reflection and refraction processing. The S-wave data are corrupted by large amounts of converted (P-wave) energy likely due to the abundance of fractured caliche in the shallow subsurface. The P-wave data show minimal reflected energy, but they show clear refracted first arrivals. We have inverted these first arrival times to determine P-wave seismic velocity models. The seismic model for the transect in Area 7 shows low velocities extending to the base of the model at the location of the Yucca Fault, as well as low velocities at the eastern end of the transect, in the vicinity of the adjacent crater. These new surveys provide further detail about the geometry of the Yucca Fault in this location where it shows two overlapping splays. We collected P- and S-wave seismic data along a transect in the southern part of NTS Area 2, corresponding with the location of a 2006 DC resistivity transect that targeted a set of small faults identified with field mapping. Again, the S-wave data are difficult to interpret. The P-wave data show clear first arrivals that we

  10. Electrical Resistivity and Seismic Surveys at the Nevada Test Site, Nevada, April 2007

    Science.gov (United States)

    Haines, Seth S.; Burton, Bethany L.; Sweetkind, Donald S.; Asch, Theodore H.

    2008-01-01

    In April 2007, the USGS collected direct-current (DC) electrical resistivity data and shear- (S) and compressional- (P) wave seismic data to provide new detail of previously mapped, overlapping fault splays at two administrative areas in the Nevada Test Site (NTS). In NTS Area 7, we collected two-dimensional DC resistivity data along a transect crossing the Yucca Fault parallel to, and between, two transects along which resistivity data were collected in a previous study in 2006. In addition, we collected three-dimensional DC resistivity data in a grid that overlies part of the 2007 transect. The DC resistivity data show that the fault has a footwall that is more conductive than the hanging wall and an along-strike progression of the fault in a location where overlapping splays are present. Co-located with the northernmost of the two 2006 DC resistivity transects, we acquired S- and P-wave seismic data for both reflection and refraction processing. The S-wave data are corrupted by large amounts of converted (P-wave) energy likely due to the abundance of fractured caliche in the shallow subsurface. The P-wave data show minimal reflected energy, but they show clear refracted first arrivals. We have inverted these first arrival times to determine P-wave seismic velocity models. The seismic model for the transect in Area 7 shows low velocities extending to the base of the model at the location of the Yucca Fault, as well as low velocities at the eastern end of the transect, in the vicinity of the adjacent crater. These new surveys provide further detail about the geometry of the Yucca Fault in this location where it shows two overlapping splays. We collected P- and S-wave seismic data along a transect in the southern part of NTS Area 2, corresponding with the location of a 2006 DC resistivity transect that targeted a set of small faults identified with field mapping. Again, the S-wave data are difficult to interpret. The P-wave data show clear first arrivals that we

  11. Coexistence of electric field controlled ferromagnetism and resistive switching for TiO{sub 2} film at room temperature

    Energy Technology Data Exchange (ETDEWEB)

    Ren, Shaoqing; Qin, Hongwei; Bu, Jianpei; Zhu, Gengchang; Xie, Jihao; Hu, Jifan, E-mail: hujf@sdu.edu.cn, E-mail: hu-jf@vip.163.com [School of Physics, State Key Laboratory for Crystal Materials, Shandong University, Jinan 250100 (China)

    2015-08-10

    The Ag/TiO{sub 2}/Nb:SrTiO{sub 3}/Ag device exhibits the coexistence of electric field controlled ferromagnetism and resistive switching at room temperature. The bipolar resistive switching in Ag/TiO{sub 2}/Nb:SrTiO{sub 3}/Ag device may be dominated by the modulation of Schottky-like barrier with the electron injection-trapped/detrapped process at the interface of TiO{sub 2}/Nb:SrTiO{sub 3}. We suggest that the electric field-induced magnetization modulation originates mainly from the creation/annihilation of lots of oxygen vacancies in TiO{sub 2}.

  12. Ez-response as a monitor of a Baikal rift fault electrical resistivity: 3D modelling studies

    Directory of Open Access Journals (Sweden)

    I. L. Trofimov

    2004-06-01

    Full Text Available 3D numerical studies have shown that the vertical voltage above the Baikal deep-water fault is detectable and that respective transfer functions, Ez-responses, are sensitive to the electrical resistivity changes of the fault, i.e. these functions appear actually informative with respect to the resistivity «breath» of the fault. It means that if the fault resistivity changed, conventional electromagnetic instruments would be able to detect this fact by measurement of the vertical electric field, Ez, or the vertical electric voltage just above the fault as well as horizontal magnetic field on the shore. Other electromagnetic field components (Ex, Ey, Hz do not seem to be sensitive to the resistivity changes in such a thin fault (as wide as 500 m. On the other hand, such changes are thought to be able to indicate a change of a stress state in the earthquake preparation zone. Besides, the vertical profile at the bottom of Lake Baikal is suitable for electromagnetic monitoring of the fault electrical resistivity changes. Altogether, the vertical voltage above the deep-water fault might be one of earthquake precursors.

  13. Crack density and electrical resistance in indium-tin-oxide/polymer thin films under cyclic loading

    KAUST Repository

    Mora Cordova, Angel

    2014-11-01

    Here, we propose a damage model that describes the degradation of the material properties of indium-tin-oxide (ITO) thin films deposited on polymer substrates under cyclic loading. We base this model on our earlier tensile test model and show that the new model is suitable for cyclic loading. After calibration with experimental data, we are able to capture the stress-strain behavior and changes in electrical resistance of ITO thin films. We are also able to predict the crack density using calibrations from our previous model. Finally, we demonstrate the capabilities of our model based on simulations using material properties reported in the literature. Our model is implemented in the commercially available finite element software ABAQUS using a user subroutine UMAT.[Figure not available: see fulltext.].

  14. Estimating the Condition of the Heat Resistant Lining in an Electrical Reduction Furnace

    Directory of Open Access Journals (Sweden)

    Jan G. Waalmann

    1988-01-01

    Full Text Available This paper presents a system for estimating the condition of the heat resistant lining in an electrical reduction furnace for ferrosilicon. The system uses temperature measured with thermocouples placed on the outside of the furnace-pot. These measurements are used together with a mathematical model of the temperature distribution in the lining in a recursive least squares algorithm to estimate the position of 'the transformation front'. The system is part of a monitoring system which is being developed in the AIP-project: 'Condition monitoring of strongly exposed process equipment in thc ferroalloy industry'. The estimator runs on-line, and results arc presented in colour-graphics on a display unit. The goal is to locate the transformation front with an accuracy of +- 5cm.

  15. Electrical resistivity and structural heredity of hypereutectic Al-Si alloy melt

    Institute of Scientific and Technical Information of China (English)

    李培杰; 熊玉华; 张燕飞; 曾大本

    2003-01-01

    The variation rule of the sensitive physical properties of Al-16%Si alloy melt was studied. The results show that within a certain temperature range, the electrical resistivity of Al-16%Si alloy melt changes abruptly in the forms of inflection points or platforms, which is ascribed to the changes in the internal microstructure of the melt. Based on this rule, the variation characteristics of microstructure can be revealed. When remelting and overheating Al-16%Si alloy to 1050℃, the hereditary effects of different original structure on solidification structure after remelting can be eliminated, which can provide scientific foundation for properly controlling the hereditary factors transmitting the structural information of melt.

  16. Temperature dependencies of electrical resistivity and thermoelectric power of SnTe thin films

    Science.gov (United States)

    Rogacheva, Elena I.; Nashchekina, Olga N.; Korzh, Irina A.; Voinova, Lidiya G.; Krivulkin, Igor M.

    2001-02-01

    The temperature dependences of electrical resistivity (rho) and thermoelectric power S for the SnTe polycrystalline thin films with charge carrier concentration of (3 - 5)(DOT)1021 cm-3 have been obtained in the range of 80 - 300 K. It was established that the (rho) (T) and S (T) dependences had non-monotonous character. In the temperature range of (80 - 150) K series of peculiarities in the form of steps and plateaux were observed most distinctly. Assumptions about the nature of these anomalies were made. The possible reasons for appearance of numerous temperature peculiarities are system's passing through different quantum states; the processes of self-organization taking place in an open system (heated thin film) at definite levels of excitation (certain temperatures); microdomain structure of thin films; relaxation processes. The pronounced anomalies observed in the temperature ranges of 135 - 150 and 190 - 200 K were attributed to phase transitions caused by redistribution of non-stoichiometric defects.

  17. Magnetic Properties and Electrical Resistivity of Zr4+ Substituted Li-Zn Ferrite

    Directory of Open Access Journals (Sweden)

    A. A. Sattar

    2007-01-01

    Full Text Available The effect of Zr-substitution on the physical and magnetic properties of Li0.3+0.5xZn0.4ZrxFe2.3-1.5xO4 ferrites (x=0.0, 0.01, 0.02, 0.03 and 0.05, prepared by the standard ceramic method, has been studied. It is found that the saturation magnetization increases up to x=0.02 and then it decreases. On the other hand, the initial permeability increased while the Curie temperature remained almost constant with increasing x. The behavior of coercivity and remanence ratio was discussed. The composition dependence of the dc electrical resistivity is found to support the hopping conduction mechanism.

  18. Technique for anisotropic extension of organic crystals: Application to temperature dependence of electrical resistance

    Science.gov (United States)

    Yamamoto, Takashi; Kato, Reizo; Yamamoto, Hiroshi M.; Fukaya, Atsuko; Yamasawa, Kenji; Takahashi, Ichiro; Akutsu, Hiroki; Akutsu-Sato, Akane; Day, Peter

    2007-08-01

    We have developed a technique for the anisotropic extension of fragile molecular crystals. The pressure medium and the instrument, which extends the pressure medium, are both made from epoxy resin. Since the thermal contraction of our instrument is identical to that of the pressure medium, the strain applied to the pressure medium has no temperature dependence down to 2K. Therefore, the degree of extension applied to the single crystal at low temperatures is uniquely determined from the degree of extension in the pressure medium and thermal contractions of the epoxy resin and the single crystal at ambient pressure. Using this novel instrument, we have measured the temperature dependence of the electrical resistance of metallic, superconducting, and insulating materials. The experimental results are discussed from the viewpoint of the extension (compression) of the lattice constants along the parallel (perpendicular) direction.

  19. Method for reducing formation of electrically resistive layer on ferritic stainless steels

    Energy Technology Data Exchange (ETDEWEB)

    Rakowski, James M.

    2017-02-28

    A method of reducing the formation of electrically resistive scale on a an article comprising a silicon-containing ferritic stainless subjected to oxidizing conditions in service includes, prior to placing the article in service, subjecting the article to conditions under which silica, which includes silicon derived from the steel, forms on a surface of the steel. Optionally, at least a portion of the silica is removed from the surface to placing the article in service. A ferritic stainless steel alloy having a reduced tendency to form silica on at least a surface thereof also is provided. The steel includes a near-surface region that has been depleted of silicon relative to a remainder of the steel.

  20. Forward problem studies of electrical resistance tomography system on concrete materials

    Science.gov (United States)

    Ang, Vernoon; Rahiman, M. H. F.; Rahim, R. A.; Aw, S. R.; Wahab, Y. A.; Thomas W. K., T.; Siow, L. T.

    2017-03-01

    Electrical resistance tomography (ERT) is well known as non-invasive imaging technique, inexpensive, radiation free, visualization measurements of the multiphase flows and frequently applied in geophysical, medical and Industrial Process Tomography (IPT) applications. Application of ERT in concrete is a new exploration field, which can be used in monitoring and detecting the health and condition of concrete without destroying it. In this paper, ERT model under the condition of concrete is studied in which the sensitivity field model is produced and simulated by using COMSOL software. The affects brought by different current injection values with different concrete conductivity are studied in detail. This study able to provide the important direction for the further study of inverse problem in ERT system. Besides, the results of this technique hopefully can open a new exploration in inspection method of concrete structures in order to maintain the health of the concrete structure for civilian safety.

  1. Microstructural characterization and hardness properties of electric resistance welding titanium joints for dental applications.

    Science.gov (United States)

    Ceschini, Lorella; Boromei, Iuri; Morri, Alessandro; Nardi, Diego; Sighinolfi, Gianluca; Degidi, Marco

    2015-06-01

    The electric resistance welding procedure is used to join a titanium bar with specific implant abutments in order to produce a framework directly in the oral cavity of the patient. This investigation studied the effects of the welding process on microstructure and hardness properties of commercially pure (CP2 and CP4) Ti components. Different welding powers and cooling procedures were applied to bars and abutments, normally used to produce the framework, in order to simulate the clinical intraoral welding procedure. The analyses highlighted that the joining process did not induce appreciable changes in the geometry of the abutments. However, because of unavoidable microstructural modifications in the welded zones, the hardness decreased to values lower than those of the unwelded CP2 and CP4 Ti grades, irrespective of the welding environments and parameters.

  2. An antireflection transparent conductor with ultralow optical loss (<2 %) and electrical resistance (<6 Ω sq-1)

    Science.gov (United States)

    Maniyara, Rinu Abraham; Mkhitaryan, Vahagn K.; Chen, Tong Lai; Ghosh, Dhriti Sundar; Pruneri, Valerio

    2016-12-01

    Transparent conductors are essential in many optoelectronic devices, such as displays, smart windows, light-emitting diodes and solar cells. Here we demonstrate a transparent conductor with optical loss of ~1.6%, that is, even lower than that of single-layer graphene (2.3%), and transmission higher than 98% over the visible wavelength range. This was possible by an optimized antireflection design consisting in applying Al-doped ZnO and TiO2 layers with precise thicknesses to a highly conductive Ag ultrathin film. The proposed multilayer structure also possesses a low electrical resistance (5.75 Ω sq-1), a figure of merit four times larger than that of indium tin oxide, the most widely used transparent conductor today, and, contrary to it, is mechanically flexible and room temperature deposited. To assess the application potentials, transparent shielding of radiofrequency and microwave interference signals with ~30 dB attenuation up to 18 GHz was achieved.

  3. Application of Electrical Resistivity Tomography Technique for Characterizing Leakage Problem in Abu Baara Earth Dam, Syria

    Directory of Open Access Journals (Sweden)

    Walid Al-Fares

    2014-01-01

    Full Text Available Electrical Resistivity Tomography (ERT survey was carried out at Abu Baara earth dam in northwestern Syria, in order to delineate potential pathways of leakage occurring through the subsurface structure close to the dam body. The survey was performed along two straight measuring profiles of 715 and 430 m length in up- and downstream sides of the dam’s embankment. The analysis of the inverted ERT sections revealed the presence of fractured and karstified limestone rocks which constitute the shallow bedrock of the dam reservoir. Several subsurface structural anomalies were identified within the fractured bedrock, most of which are associated with probable karstic cavities, voids, and discontinuity features developed within the carbonates rocks. Moreover, results also showed the occurrence of a distinguished subsiding structure coinciding with main valley course. Accordingly, it is believed that the bedrock and the other detected features are the main potential causes of water leakage from the dam’s reservoir.

  4. Demonstration of combined zero-valent iron and electrical resistance heating for in situ trichloroethene remediation.

    Science.gov (United States)

    Truex, M J; Macbeth, T W; Vermeul, V R; Fritz, B G; Mendoza, D P; Mackley, R D; Wietsma, T W; Sandberg, G; Powell, T; Powers, J; Pitre, E; Michalsen, M; Ballock-Dixon, S J; Zhong, L; Oostrom, M

    2011-06-15

    The effectiveness of in situ treatment using zero-valent iron (ZVI) for nonaqueous phase or significant sediment-associated contaminant mass can be limited by relatively low rates of mass transfer to bring contaminants in contact with the reactive media. For a field test in a trichloroethene (TCE) source area, combining moderate-temperature subsurface electrical resistance heating with in situ ZVI treatment was shown to accelerate TCE treatment by a factor of about 4 based on organic daughter products and a factor about 8 based on chloride concentrations. A mass-discharge-based analysis was used to evaluate reaction, dissolution, and volatilization processes at ambient groundwater temperature (~10 °C) and as temperature was increased up to about 50 °C. Increased reaction and contaminant dissolution were observed with increased temperature, but vapor- or aqueous-phase migration of TCE out of the treatment zone was minimal during the test because reactions maintained low aqueous-phase TCE concentrations.