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Sample records for surface impedance method

  1. Acoustic Impedance Measurement for Underground Surfaces.

    Science.gov (United States)

    Cockcroft, Paul William

    Available from UMI in association with The British Library. Requires signed TDF. This thesis investigates the measurement of acoustic impedance for surfaces likely to be found in underground coal mines. By introducing the concepts of industrial noise, the effects of noise on the ear and relevant legislation the need for the protection of workers can be appreciated. Representative acoustic impedance values are vital as input for existing computer models that predict sound levels in various underground environments. These enable the mining engineer to predict the noise level at any point within a mine in the vicinity of noisy machinery. The concepts of acoustic intensity and acoustic impedance are investigated and different acoustic impedance measurement techniques are detailed. The possible use of either an impedance tube or an intensity meter for these kinds of measurements are suggested. The problems with acoustic intensity and acoustic impedance measurements are discussed with reference to the restraints that an underground environment imposes on any measurement technique. The impedance tube method for work in an acoustics laboratory is shown and the theory explained, accompanied by a few representative results. The use of a Metravib intensity meter in a soundproof chamber to gain impedance values is explained in detail. The accompanying software for the analysis of the two measured pressure signals is shown as well as the actual results for a variety of test surfaces. The use of a Nagra IV-SJ tape recorder is investigated to determine the effect of recording on the measurement and subsequent analysis of the input signals, particularly with reference to the phase difference introduced between the two simultaneous pressure signals. The subsequent use of a Norwegian Electronic intensity meter, including a proposal for underground work, is shown along with results for tests completed with this piece of equipment. Finally, recommendations are made on how to link up

  2. Comparison of visual, impedance spectroscopy and laser fluorescence methods in detecting early carious lesions on occlusal surfaces

    Directory of Open Access Journals (Sweden)

    Chalas Renata

    2014-06-01

    Full Text Available The diagnostic management is a very important and integral part of the entire treatment process and has a direct influence on the decision-taking on the choice of the most appropriate form of therapy consistent with current knowledge. Knowledge of the morphology of hard dental tissues lesions has led to the development of quantitative methods for diagnosis and monitoring of dental caries, which enabled the implementation of appropriate treatments aimed at repairing than replacing damaged tissue. The aim of the study was to compare selected diagnostic methods: visual (ICDAS, impedance spectroscopy (CarieScan PRO and laser fluorescence (Diagnodent Pen in detecting caries in grooves on the chewing surfaces of molars and premolars. The obtained results indicated a high concordance of measurements performed with the Diagnodent Pen with the results of visual examination and a lower compliance of visual examination with the results obtained using the CarieScan PRO. A combination of visual and tactile method with tests using advanced technology provides greater opportunity to confirm the diagnosis of carious lesions requiring medical intervention.

  3. Retrieving complex surface impedances from statistical absorption coefficients

    DEFF Research Database (Denmark)

    Mondet, Boris Jean-Francois; Brunskog, Jonas; Jeong, Cheol-Ho

    2017-01-01

    coefficients, prior information about the absorber of interest can be used as constraints, which is shown to help determine the correct impedance from absorption coefficient. Further stability and sensitivity investigations indicate that the method presented constitutes an efficient solution to convert sound......In room acoustic simulations the surface materials are commonly represented with energy parameters, such as the absorption and scattering coefficients, which do not carry phase information. This paper presents a method to transform statistical absorption coefficients into complex surface impedances...... that the impedance found has a physical meaning and respects causality in the time domain. Known material models, such as Miki’s and Maa’s models, are taken as references to assess the validity of the suggested model. Due to the non-uniqueness of retrieving complex-valued impedances from real-valued absorption...

  4. Estimation of surface impedance using different types of microphone arrays

    DEFF Research Database (Denmark)

    Richard, Antoine Philippe André; Fernandez Grande, Efren; Brunskog, Jonas

    2017-01-01

    , the performances of a rigid spherical array and a double layer planar array are examined. The use of sparse array processing methods and conventional regulariation approaches are studied. In addition, the influence of the size of the sample on the surface impedance estimation is investigated using both...

  5. Enhanced Method for Cavity Impedance Calculations

    Energy Technology Data Exchange (ETDEWEB)

    Frank Marhauser, Robert Rimmer, Kai Tian, Haipeng Wang

    2009-05-01

    With the proposal of medium to high average current accelerator facilities the demand for cavities with extremely low Higher Order Mode (HOM) impedances is increasing. Modern numerical tools are still under development to more thoroughly predict impedances that need to take into account complex absorbing boundaries and lossy materials. With the usually large problem size it is preferable to utilize massive parallel computing when applicable and available. Apart from such computational issues, we have developed methods using available computer resources to enhance the information that can be extracted from a cavities? wakefield computed in time domain. In particular this is helpful for a careful assessment of the extracted RF power and the mitigation of potential beam break-up or emittance diluting effects, a figure of merit for the cavity performance. The method is described as well as an example of its implementation.

  6. Method for conducting nonlinear electrochemical impedance spectroscopy

    Science.gov (United States)

    Adler, Stuart B.; Wilson, Jamie R.; Huff, Shawn L.; Schwartz, Daniel T.

    2015-06-02

    A method for conducting nonlinear electrochemical impedance spectroscopy. The method includes quantifying the nonlinear response of an electrochemical system by measuring higher-order current or voltage harmonics generated by moderate-amplitude sinusoidal current or voltage perturbations. The method involves acquisition of the response signal followed by time apodization and fast Fourier transformation of the data into the frequency domain, where the magnitude and phase of each harmonic signal can be readily quantified. The method can be implemented on a computer as a software program.

  7. Bioelectrical Impedance Methods for Noninvasive Health Monitoring: A Review

    Science.gov (United States)

    Bera, Tushar Kanti

    2014-01-01

    Under the alternating electrical excitation, biological tissues produce a complex electrical impedance which depends on tissue composition, structures, health status, and applied signal frequency, and hence the bioelectrical impedance methods can be utilized for noninvasive tissue characterization. As the impedance responses of these tissue parameters vary with frequencies of the applied signal, the impedance analysis conducted over a wide frequency band provides more information about the tissue interiors which help us to better understand the biological tissues anatomy, physiology, and pathology. Over past few decades, a number of impedance based noninvasive tissue characterization techniques such as bioelectrical impedance analysis (BIA), electrical impedance spectroscopy (EIS), electrical impedance plethysmography (IPG), impedance cardiography (ICG), and electrical impedance tomography (EIT) have been proposed and a lot of research works have been conducted on these methods for noninvasive tissue characterization and disease diagnosis. In this paper BIA, EIS, IPG, ICG, and EIT techniques and their applications in different fields have been reviewed and technical perspective of these impedance methods has been presented. The working principles, applications, merits, and demerits of these methods has been discussed in detail along with their other technical issues followed by present status and future trends. PMID:27006932

  8. Surface impedance of travelling--Wave antenna in magnetized plasma

    International Nuclear Information System (INIS)

    Denisenko, I.B.; Ostrikov, K.N.

    1993-01-01

    Wave properties of metal antennas immersed in a magnetoactive plasma are intensively studied nowadays with the objects of radio communications in ionosphere, plasma heating, gas discharge technique. Many papers are devoted to studies of sheath waves (SW) in magnetoplasma, which are surface by nature and propagate along the metal-low-density sheath-plasma waveguide structure. The results of these papers suggest that the existence of these waves makes significant contribution in antenna impedance. Note that the impedance measurement is one of possible ways of experimental surface waves characterization. In the present report the surface impedance of travelling SW antenna immersed in magnetoactive plasma is calculated and its dependence on the waveguide structure parameters such as plasma density, external magnetic field H 0 and electrons collisional frequency values, sheath region width, conductivity of metal surface is studied. The calculations have been carried out in a quasiplane approximation, when antenna radius greatly exceeds the SW skin depth. Note that the finite conductivity of metal is necessary to be taken into account to provide a finite surface impedance value. The surface impedance is calculated in two cases, namely when SW propagate along (Ζ parallel ) and across (Ζ perpendicular ) the external magnetic field. The relation between the values Ζ parallel and Ζ perpendicular is obtained. This relation shows that the values Ζ parallel and Ζ parallel may satisfy both inequalities Ζ parallel much-gt Ζ perpendicular and Ζ perpendicular approx-gt Ζ perpendicular dependent on the parameters of the structure. The comparison of dispersion properties of the SW propagating along Η 0 with the experimental results is carried out. The results are shown to satisfactorily correspond to the experimental results

  9. Design methodology to enhance high impedance surfaces performances

    Directory of Open Access Journals (Sweden)

    M. Grelier

    2014-04-01

    Full Text Available A methodology is introduced for designing wideband, compact and ultra-thin high impedance surfaces (HIS. A parametric study is carried out to examine the effect of the periodicity on the electromagnetic properties of an HIS. This approach allows designers to reach the best trade-off for HIS performances.

  10. [Abdomen specific bioelectrical impedance analysis (BIA) methods for evaluation of abdominal fat distribution].

    Science.gov (United States)

    Ida, Midori; Hirata, Masakazu; Hosoda, Kiminori; Nakao, Kazuwa

    2013-02-01

    Two novel bioelectrical impedance analysis (BIA) methods have been developed recently for evaluation of intra-abdominal fat accumulation. Both methods use electrodes that are placed on abdominal wall and allow evaluation of intra-abdominal fat area (IAFA) easily without radiation exposure. Of these, "abdominal BIA" method measures impedance distribution along abdominal anterior-posterior axis, and IAFA by BIA method(BIA-IAFA) is calculated from waist circumference and the voltage occurring at the flank. Dual BIA method measures impedance of trunk and body surface at the abdominal level and calculates BIA-IAFA from transverse and antero-posterior diameters of the abdomen and the impedance of trunk and abdominal surface. BIA-IAFA by these two BIA methods correlated well with IAFA measured by abdominal CT (CT-IAFA) with correlatipn coefficient of 0.88 (n = 91, p obesity.

  11. Assessing human brain impedance using simultaneous surface and intracerebral recordings.

    Science.gov (United States)

    Ranta, Radu; Le Cam, Steven; Tyvaert, Louise; Louis-Dorr, Valérie

    2017-02-20

    Most of the literature on the brain impedance proposes a frequency-independent resistive model. Recently, this conclusion was tackled by a series of papers (Bédard et al., 2006; Bédard and Destexhe, 2009; Gomes et al., 2016), based on microscopic sale modeling and measurements. Our paper aims to investigate the impedance issue using simultaneous in vivo depth and surface signals recorded during intracerebral electrical stimulation of epileptic patients, involving a priori different tissues with different impedances. Our results confirm the conclusions from Logothethis et al. (2007): there is no evidence of frequency dependence of the brain tissue impedance (more precisely, there is no difference, in terms of frequency filtering, between the brain and the skull bone), at least at a macroscopic scale. In order to conciliate findings from both microscopic and macroscopic scales, we recall different neural/synaptic current generators' models from the literature and we propose an original computational model, based on fractional dynamics. Copyright © 2016 IBRO. Published by Elsevier Ltd. All rights reserved.

  12. Equivalent complex conductivities representing the effects of T-tubules and folded surface membranes on the electrical admittance and impedance of skeletal muscles measured by external-electrode method

    Science.gov (United States)

    Sekine, Katsuhisa

    2017-12-01

    In order to represent the effects of T-tubules and folded surface membranes on the electrical admittance and impedance of skeletal muscles measured by the external-electrode method, analytical relations for the equivalent complex conductivities of hypothetical smooth surface membranes were derived. In the relations, the effects of each tubule were represented by the admittance of a straight cable. The effects of the folding of a surface membrane were represented by the increased area of surface membranes. The equivalent complex conductivities were represented as summation of these effects, and the effects of the T-tubules were different between the transversal and longitudinal directions. The validity of the equivalent complex conductivities was supported by the results of finite-difference method (FDM) calculations made using three-dimensional models in which T-tubules and folded surface membranes were represented explicitly. FDM calculations using the equivalent complex conductivities suggested that the electrically inhomogeneous structure due to the existence of muscle cells with T-tubules was sufficient for explaining the experimental results previously obtained using the external-electrode method. Results of FDM calculations in which the structural changes caused by muscle contractions were taken into account were consistent with the reported experimental results.

  13. Validation of Standing Wave Liner Impedance Measurement Method, Phase I

    Data.gov (United States)

    National Aeronautics and Space Administration — Hersh Acoustical Engineering, Inc. proposes to establish the feasibility and practicality of using the Standing Wave Method (SWM) to measure the impedance of...

  14. Energy storage cell impedance measuring apparatus, methods and related systems

    Science.gov (United States)

    Morrison, John L.; Morrison, William H.; Christophersen, Jon P.

    2017-12-26

    Energy storage cell impedance testing devices, circuits, and related methods are disclosed. An energy storage cell impedance measuring device includes a sum of sinusoids (SOS) current excitation circuit including differential current sources configured to isolate a ground terminal of the differential current sources from a positive terminal and a negative terminal of an energy storage cell. A method includes applying an SOS signal comprising a sum of sinusoidal current signals to the energy storage cell with the SOS current excitation circuit, each of the sinusoidal current signals oscillating at a different one of a plurality of different frequencies. The method also includes measuring an electrical signal at a positive terminal and a negative terminal of the energy storage cell, and computing an impedance of the energy storage cell at each of the plurality of different frequencies using the measured electrical signal.

  15. An approach to the diagnosis of metabolic syndrome by the multi-electrode impedance method

    Science.gov (United States)

    Furuya, N.; Sakamoto, K.; Kanai, H.

    2010-04-01

    It is well known that metabolic syndrome can induce myocardial infarction and cerebral infarction. So, it is very important to measure the visceral fat volume. In the electric impedance method, information in the vicinity of the electrodes is strongly reflected. Therefore, we propose a new multi-electrode arrangement method based on the impedance sensitivity theorem to measure the visceral fat volume. This electrode arrangement is designed to enable high impedance sensitivity in the visceral and subcutaneous fat regions. Currents are simultaneously applied to several current electrodes on the body surface, and one voltage electrode pair is arranged on the body surface near the organ of interest to obtain the visceral fat information and another voltage electrode pair is arranged on the body surface near the current electrodes to obtain the subcutaneous fat information. A simulation study indicates that by weighting the impedance sensitivity distribution, as in our method, a high-sensitivity region in the visceral and the subcutaneous fat regions can be formed. In addition, it was confirmed that the visceral fat volume can be estimated by the measured impedance data.

  16. Absorption and impedance boundary conditions for phased geometrical-acoustics methods

    DEFF Research Database (Denmark)

    Jeong, Cheol-Ho

    2012-01-01

    Defining accurate acoustical boundary conditions is of crucial importance for room acoustic simulations. In predicting sound fields using phased geometrical acoustics methods, both absorption coefficients and surface impedances of the boundary surfaces can be used, but no guideline has been...... developed on which boundary condition produces accurate results. In this study, various boundary conditions in terms of normal, random, and field incidence absorption coefficients and normal incidence surface impedance are used in a phased beam tracing model, and the simulated results are validated...... with boundary element solutions. Two rectangular rooms with uniform and non-uniform absorption distributions are tested. Effects of the neglect of reflection phase shift are also investigated. It is concluded that the impedance, random incidence, and field incidence absorption boundary conditions produce...

  17. Normal incidence sound transmission loss evaluation by upstream surface impedance measurements.

    Science.gov (United States)

    Panneton, Raymond

    2009-03-01

    A method is developed to obtain the normal incidence sound transmission loss of noise control elements used in piping systems from upstream surface impedance measurements only. The noise control element may be a small material specimen in an impedance tube, a sealing part in an automotive hollow body network, an expansion chamber, a resonator, or a muffler. The developments are based on a transfer matrix (four-pole) representation of the noise control element and on the assumption that only plane waves propagate upstream and downstream the element. No assumptions are made on its boundary conditions, dimensions, shape, and material properties (i.e., the element may be symmetrical or not along its thickness, homogeneous or not, isotropic or not). One-load and two-load procedures are also proposed to identify the transfer matrix coefficients needed to obtain the true transmission loss of the tested element. The method can be used with a classical two-microphone impedance tube setup (i.e., no additional downstream tube and downstream acoustical measurements). The method is tested on three different noise control elements: two impedance tube multilayered specimens and one expansion chamber. The results found using the developed method are validated using numerical simulations.

  18. Transverse impedance measurement using response matrix fit method at APS

    International Nuclear Information System (INIS)

    Sajaev, V.

    2007-01-01

    The Advanced Photon Source (APS) is a third-generation synchrotron light source based on a 7-GeV electron storage ring. In third-generation light sources the synchrotron radiation is mainly produced in undulators. In order to achieve high photon flux and tunability, the magnet gap in undulators has to be as small as possible. Therefore, the undulators are installed on dedicated small-gap insertion device (ID) vacuum chambers. APS has thirty-five 5-m-long straight sections available for undulators. At the time of the measurements, there were 31 straight sections occupied with various insertion devices, and 4 straight sections were still empty. Most of the ID vacuum chambers have a 8-mm in-vacuum gap, and two chambers have a 5-mm gap. These narrow-gap vacuum chambers are believed to be the main source of the transverse impedance of the machine. One can measure the combined impedance by measuring the transverse tune slope with single-bunch current. Comparing this slope before and after installation of the narrow-gap vacuum chamber, one can deduce the impedance of the chamber. It is difficult to accurately measure the change in the tune slope after one or a few new ID chambers are installed. If several identical ID vacuum chambers are installed over a period of time, then one can estimate the contribution of one ID chamber. Over the last few years there have been a number of attempts to measure the impedance of separate components of accelerators. Phase-advance measurements from beam position monitor (BPM) turn-by-turn histories were used at LEP to measure the impedance distribution around the ring. Researches at LEP were able to fit average impedance in the long sections of the LEP arc and determine the impedance of the rf sections. The method was tried at APS; however, the accuracy of the measurements was not enough to determine the small impedance of a single ID vacuum chamber. There is also a different approach that uses local orbit bumps to probe different parts

  19. A combination of transformation optics and surface impedance modulation to design compact retrodirective reflectors

    Science.gov (United States)

    Haddad, H.; Loison, R.; Gillard, R.; Harmouch, A.; Jrad, A.

    2018-02-01

    This study proposes a new approach to flatten retrodirective corner reflectors. The proposed method enables compact reflectors via Transformation Optics (TO) combined with Surface Impedance Modulation (SIM). This combination permits to relax the constraints on the anisotropic material resulting from the TO. Phase gradient approach is generalized to be used within anisotropic media and is implemented with SIM. Different reflector setups are designed, simulated and compared for fop = 8GHz using ANSYS® HFSS® in order to validate the use of such a combination.

  20. Surface impedance of superconductors in wide frequency ranges for wake field calculations

    International Nuclear Information System (INIS)

    Davidovskii, V.G.

    2006-01-01

    The problem of the surface impedance of superconductors in wide frequency ranges for calculations of wake fields, generated by bunches of charged particles moving axially inside a metallic vacuum chambers, is solved. The case of specular electron reflection at the superconductor surface is considered. The expression for the surface impedance of superconductors suitable for numerical computation is derived [ru

  1. Electrical impedance tomography spectroscopy method for characterising particles in solid-liquid phase

    Energy Technology Data Exchange (ETDEWEB)

    Zhao, Yanlin [Department of Thermal Energy Engineering, College of Mechanical and Transportation Engineering, China University of Petroleum, Beijing, 102249 (China); Wang, Mi [Institute of Particle Science and Engineering, School of Process, Environmental and Materials Engineering, University of Leeds, Leeds LS2 9JT (China); Yao, Jun [School of Energy Research, Xiamen University, Xiamen 361005 (China)

    2014-04-11

    Electrical impedance tomography (EIT) is one of the process tomography techniques to provide an on-line non-invasive imaging for multiphase flow measurement. With EIT measurements, the images of impedance real part, impedance imaginary part, phase angle, and magnitude can be obtained. However, most of the applications of EIT in the process industries rely on the conductivity difference between two phases in fluids to obtain the concentration profiles. It is not common to use the imaginary part or phase angle due to the dominant change in conductivity or complication in the use of other impedance information. In a solid-liquid two phases system involving nano- or submicro-particles, characterisation of particles (e.g. particle size and concentration) have to rely on the measurement of impedance phase angle or imaginary part. Particles in a solution usually have an electrical double layer associated with their surfaces and can form an induced electrical dipole moment due to the polarization of the electrical double layer under the influence of an alternating electric field. Similar to EIT, electrical impedance spectroscopy (EIS) measurement can record the electrical impedance data, including impedance real part, imaginary part and phase angle (θ), which are caused by the polarization of the electrical double layer. These impedance data are related to the particle characteristics e.g. particle size, particle and ionic concentrations in the aqueous medium, therefore EIS method provides a capability for characterising the particles in suspensions. Electrical impedance tomography based on EIS measurement or namely, electrical impedance tomography spectroscopy (EITS) could image the spatial distribution of particle characteristics. In this paper, a new method, including test set-up and data analysis, for characterisation of particles in suspensions are developed through the experimental approach. The experimental results on tomographic imaging of colloidal particles

  2. Full-wave analysis of superconducting microstrip lines on anisotropic substrates using equivalent surface impedance approach

    International Nuclear Information System (INIS)

    Lee, L.H.; Lyons, W.G.; Orlando, T.P.; Ali, S.M.

    1993-01-01

    A computationally efficient full-wave technique is developed to analyze single and coupled superconducting microstrip lines on anisotropic substrates. The optic axis of the dielectric is in the plane of the substrate at an arbitrary angle with respect to the propagation direction. A dyadic Green's function for layered, anisotropic media is used to formulate an integral equation for the current in the strips. To increase the efficiency of the method, the superconducting strips are replaced by equivalent surface impedances which account for the loss and kinetic inductance of the superconductors. The validity of this equivalent surface impedance (ESI) approach is verified by comparing the calculated complex propagation constant and characteristic impedance for superconducting microstrip lines on an isotropic substrate to measured results, and to numerical results by the more rigorous volume-integral equation method. The results calculated using the ESI approach for perfectly conducting coupled lines on an anisotropic substrate agree with the results by the finite-difference time-domain method. This efficient ESI technique is then used to study the effects of the optic axis orientation and the strip width on the characteristics of single and coupled superconducting microstrip lines on M-plane sapphire. The effects of the line separation and operating temperature on the coupled lines are also investigated

  3. Microwave surface impedance of MgB2 thin film

    International Nuclear Information System (INIS)

    Jin, B B; Klein, N; Kang, W N; Kim, Hyeong-Jin; Choi, Eun-Mi; Lee, Sung-I K; Dahm, T; Maki, K

    2003-01-01

    The microwave surface impedance Z s = R s + jωμ 0 λ was measured with dielectric resonator techniques for two c-axis-oriented MgB 2 thin films. The temperature dependence of the penetration depth λ measured with a sapphire resonator at 17.93 GHz can be well fitted from 5 K close to T c by the standard BCS integral expression assuming the reduced energy gap Δ(0)/kT c to be as low as 1.13 and 1.03 for the two samples. From these fits the penetration depth at zero temperatures was determined to be 102 nm and 107 nm, respectively. The results clearly indicate the s-wave nature of the order parameter. The temperature dependence of surface resistance R s , measured with a rutile dielectric resonator, shows an exponential behaviour below about T c /2 with a reduced energy gap being consistent with the one determined from the λ data. The R s value at 4.2 K was found to be as low as 19 μΩ at 7.2 GHz, which is comparable with that of a high-quality high-temperature thin film of YBa 2 Cu 3 O 7 . A higher-order mode at 17.9 GHz was employed to determine the frequency f dependence of R s ∝ f n(T) . Our results revealed a decrease of n with increasing temperature ranging from n = 2 below 8 K to n 1 from 13 to 34 K

  4. Effective wave tilt and surface impedance over a laterally inhomogeneous two-layer earth

    International Nuclear Information System (INIS)

    Hughes, W.J.; Wait, J.R.

    1975-01-01

    Using a perturbation method, the effect of a simple two-dimensional model on the electromagnetic fields at the surface of the Earth is considered for a postulated downcoming plane wave. The calculated change in the surface impedance and wave tilt due to lateral inhomogeneities is examined. It is found that the magnetic wave tilt (H/sub z//H/sub x/) is most seriously affected by such anomalies. This may have important consequences on electromagnetic probing of nonuniform portions of the Earth's crust

  5. Influence of convection at outer ceramic surfaces on the characterization of thermoelectric modules by impedance spectroscopy

    Science.gov (United States)

    Beltrán-Pitarch, Braulio; García-Cañadas, Jorge

    2018-02-01

    Impedance spectroscopy is a useful method for the characterization of thermoelectric (TE) modules. It can determine with high accuracy the module's dimensionless figure of merit (zT) as well as the average TE properties of the module's thermoelements. Interpretation of impedance results requires the use of a theoretical model (equivalent circuit), which provides the desired device parameters after a fitting is performed to the experimental results. Here, we extend the currently available equivalent circuit, only valid for adiabatic conditions, to account for the effect of convection at the outer surface of the module ceramic plates, which is the part of the device where convection is more prominent. This is performed by solving the heat equation in the frequency domain including convection heat losses. As a result, a new element (convection resistance) appears in the developed equivalent circuit, which starts to influence at mid-low frequencies, causing a decrease of the typically observed semicircle in the impedance spectrum. If this effect is not taken into account, an underestimation of the zT occurs when measurements are performed under room conditions. The theoretical model is validated by experimental measurements performed in a commercial module with and without vacuum. Interestingly, the use of the new equivalent circuit allows the determination of the convection heat transfer coefficient (h), if the module's Seebeck coefficient is known, and an impedance measurement in vacuum is performed, opening up the possibility to develop TE modules as h sensors. On the other hand, if h is known, all the properties of the module (zT, ohmic (internal) resistance, average Seebeck coefficient and average thermal conductivity of the thermoelements and thermal conductivity of the ceramics) can be obtained from one impedance measurement in vacuum and another measurement under room conditions.

  6. Iterative Reconstruction Methods for Hybrid Inverse Problems in Impedance Tomography

    DEFF Research Database (Denmark)

    Hoffmann, Kristoffer; Knudsen, Kim

    2014-01-01

    For a general formulation of hybrid inverse problems in impedance tomography the Picard and Newton iterative schemes are adapted and four iterative reconstruction algorithms are developed. The general problem formulation includes several existing hybrid imaging modalities such as current density...... impedance imaging, magnetic resonance electrical impedance tomography, and ultrasound modulated electrical impedance tomography, and the unified approach to the reconstruction problem encompasses several algorithms suggested in the literature. The four proposed algorithms are implemented numerically in two...

  7. Array of the two arc monopoles on a sphere with surface impedance

    OpenAIRE

    Dakhov, Viktor M.; Berdnik, Sergey L.; Blinova, Natalya K.; Penkin, Yu. M.

    2017-01-01

    The antenna array of two arc monopoles which are located parallel to the surface of a perfectly conducting or impedance sphere is considered. The influences of the phase of excitation of a monopole, the distance to the sphere surface, and sphere radius and its surface impedance on the directivity of the radiator are considered. It is shown that the radiation pattern of the antenna for antiphase excitation is highly directional and has a single maximum in the plane of arrangement of the emitters.

  8. Impedance spectroscopy studies of surface engineered TiO2 ...

    Indian Academy of Sciences (India)

    Administrator

    Abstract. Dielectric analysis of nanometre range size ceramic particles like TiO2 is very important in the understanding of the performance and design of their polymer nanocomposites for energy storage and other applications. In recent times, impedance spectroscopy is shown to be a very powerful tool to investigate the.

  9. Impedance spectroscopy studies of surface engineered TiO 2 ...

    Indian Academy of Sciences (India)

    Dielectric analysis of nanometre range size ceramic particles like TiO2 is very important in the understanding of the performance and design of their polymer nanocomposites for energy storage and other applications. In recent times, impedance spectroscopy is shown to be a very powerful tool to investigate the dielectric ...

  10. Impedance adaptation methods of the piezoelectric energy harvesting

    Science.gov (United States)

    Kim, Hyeoungwoo

    In this study, the important issues of energy recovery were addressed and a comprehensive investigation was performed on harvesting electrical power from an ambient mechanical vibration source. Also discussed are the impedance matching methods used to increase the efficiency of energy transfer from the environment to the application. Initially, the mechanical impedance matching method was investigated to increase mechanical energy transferred to the transducer from the environment. This was done by reducing the mechanical impedance such as damping factor and energy reflection ratio. The vibration source and the transducer were modeled by a two-degree-of-freedom dynamic system with mass, spring constant, and damper. The transmissibility employed to show how much mechanical energy that was transferred in this system was affected by the damping ratio and the stiffness of elastic materials. The mechanical impedance of the system was described by electrical system using analogy between the two systems in order to simply the total mechanical impedance. Secondly, the transduction rate of mechanical energy to electrical energy was improved by using a PZT material which has a high figure of merit and a high electromechanical coupling factor for electrical power generation, and a piezoelectric transducer which has a high transduction rate was designed and fabricated. The high g material (g33 = 40 [10-3Vm/N]) was developed to improve the figure of merit of the PZT ceramics. The cymbal composite transducer has been found as a promising structure for piezoelectric energy harvesting under high force at cyclic conditions (10--200 Hz), because it has almost 40 times higher effective strain coefficient than PZT ceramics. The endcap of cymbal also enhances the endurance of the ceramic to sustain ac load along with stress amplification. In addition, a macro fiber composite (MFC) was employed as a strain component because of its flexibility and the high electromechanical coupling

  11. Reduced-volume antennas with integrated high-impedance electromagnetic surfaces.

    Energy Technology Data Exchange (ETDEWEB)

    Forman, Michael A.

    2006-11-01

    Several antennas with integrated high-impedance surfaces are presented. The high-impedance surface is implemented as a composite right/left-handed (CRLH) metamaterial fabricated from a periodic structure characterized by a substrate, filled with an array of vertical vias and capped by capacitive patches. Omnidirectional antennas placed in close proximity to the high-impedance surface radiate hemispherically with an increase in boresight far-field pattern gain of up to 10 dB and a front-to-back ratio as high as 13 dB at 2.45 GHz. Several TEM rectangular horn antennas are realized by replacing conductor walls with high-impedance surfaces. The TEM horn antennas are capable of operating below the TE{sub 1,0} cutoff frequency of a standard all-metal horn antenna, enabling a reduction in antenna volume. Above the cutoff frequency the TEM horn antennas function similarly to standard rectangular horn antennas.

  12. Development of a pressure based room acoustic model using impedance descriptions of surfaces

    DEFF Research Database (Denmark)

    Marbjerg, Gerd Høy; Brunskog, Jonas; Jeong, Cheol-Ho

    2013-01-01

    and acoustic radiosity will account for the diffuse reflections. This paper presents the motivation for the new model in the form of results in literature, which show the importance of retaining the angle dependence and phase information in reflections along with simple examples of angle dependent reflection......If a simulation tool is to be used for the optimization of absorbent ceilings, it is important that the simulation tool includes a good description of the surface. This study therefore aims at developing a model which can describe surfaces by their impedance values and not just by their statistical...... absorption coefficient, thus retaining the phase and the angle dependence. The approach of the proposed model will be to calculate the pressure impulse response using a combination of the image source method and acoustic radiosity. The image source method will account for the specular reflections...

  13. Electromechanical impedance method to assess dental implant stability

    International Nuclear Information System (INIS)

    Tabrizi, Aydin; Rizzo, Piervincenzo; Ochs, Mark W

    2012-01-01

    The stability of a dental implant is a prerequisite for supporting a load-bearing prosthesis and establishment of a functional bone–implant system. Reliable and noninvasive methods able to assess the bone interface of dental and orthopedic implants (osseointegration) are increasingly demanded for clinical diagnosis and direct prognosis. In this paper, we propose the electromechanical impedance method as a novel approach for the assessment of dental implant stability. Nobel Biocare ® implants with a size of 4.3 mm diameter ×13 mm length were placed inside bovine bones that were then immersed in a solution of nitric acid to allow material degradation. The degradation simulated the inverse process of bone healing. The implant–bone systems were monitored by bonding a piezoceramic transducer (PZT) to the implants’ abutment and measuring the admittance of the PZT over time. It was found that the PZT’s admittance and the statistical features associated with its analysis are sensitive to the degradation of the bones and can be correlated to the loss of calcium measured by means of the atomic absorption spectroscopy method. The present study shows promising results and may pave the road towards an innovative approach for the noninvasive monitoring of dental implant stability and integrity. (paper)

  14. Electromechanical impedance method to assess dental implant stability

    Science.gov (United States)

    Tabrizi, Aydin; Rizzo, Piervincenzo; Ochs, Mark W.

    2012-11-01

    The stability of a dental implant is a prerequisite for supporting a load-bearing prosthesis and establishment of a functional bone-implant system. Reliable and noninvasive methods able to assess the bone interface of dental and orthopedic implants (osseointegration) are increasingly demanded for clinical diagnosis and direct prognosis. In this paper, we propose the electromechanical impedance method as a novel approach for the assessment of dental implant stability. Nobel Biocare® implants with a size of 4.3 mm diameter ×13 mm length were placed inside bovine bones that were then immersed in a solution of nitric acid to allow material degradation. The degradation simulated the inverse process of bone healing. The implant-bone systems were monitored by bonding a piezoceramic transducer (PZT) to the implants’ abutment and measuring the admittance of the PZT over time. It was found that the PZT’s admittance and the statistical features associated with its analysis are sensitive to the degradation of the bones and can be correlated to the loss of calcium measured by means of the atomic absorption spectroscopy method. The present study shows promising results and may pave the road towards an innovative approach for the noninvasive monitoring of dental implant stability and integrity.

  15. A cell viability assessment method based on area-normalized impedance spectrum (ANIS).

    Science.gov (United States)

    Zhang, Rongbiao; Wei, Mingji; Chen, Shuohuan; Li, Guoxiao; Zhang, Fei; Yang, Ning; Huang, Linkui

    2018-03-21

    Impedance measurement of cells using electric cell-substrate impedance sensing (ECIS) is widely accepted as an effective method to assess cell status. However, the sensitive frequency drifts over time with the changes of culture condition according to the built circuit model and experimental results. The area-normalized impedance spectrum (ANIS) method, which uses normalized area of impedance spectrum in a certain interval to assess cell viability, was proposed in this paper to solve the problem. The certain interval is calculated due to the threshold Z th , which is determined by 2% decline of the maximum impedance. Stabilities of two methods were analyzed by normalizing the area and impedance, showing that the normalized impedance fluctuated like a wave, while the normalized area was smoother. In addition, Cell Count Kit-8 (CCK-8) assay was carried out proving that the correlation index of ANIS method increases by 2.4% compared with impedance sensing method, and the maximum error of ANIS method decreases by 4%. Comparison analysis of two methods with random measurement noise was also discussed in this paper, and the results showed that the ANIS method was less affected by measurement noise than impedance sensing method. It demonstrated that the ANIS method is a more stable and accurate method to assess cell viability. Copyright © 2018 Elsevier B.V. All rights reserved.

  16. Ultrahigh impedance method to assess electrostatic accelerator performance

    Directory of Open Access Journals (Sweden)

    Nikolai R. Lobanov

    2015-06-01

    Full Text Available This paper describes an investigation of problem-solving procedures to troubleshoot electrostatic accelerators. A novel technique to diagnose issues with high-voltage components is described. The main application of this technique is noninvasive testing of electrostatic accelerator high-voltage grading systems, measuring insulation resistance, or determining the volume and surface resistivity of insulation materials used in column posts and acceleration tubes. In addition, this technique allows verification of the continuity of the resistive divider assembly as a complete circuit, revealing if an electrical path exists between equipotential rings, resistors, tube electrodes, and column post-to-tube conductors. It is capable of identifying and locating a “microbreak” in a resistor and the experimental validation of the transfer function of the high impedance energy control element. A simple and practical fault-finding procedure has been developed based on fundamental principles. The experimental distributions of relative resistance deviations (ΔR/R for both accelerating tubes and posts were collected during five scheduled accelerator maintenance tank openings during 2013 and 2014. Components with measured ΔR/R>±2.5% were considered faulty and put through a detailed examination, with faults categorized. In total, thirty four unique fault categories were identified and most would not be identifiable without the new technique described. The most common failure mode was permanent and irreversible insulator current leakage that developed after being exposed to the ambient environment. As a result of efficient in situ troubleshooting and fault-elimination techniques, the maximum values of |ΔR/R| are kept below 2.5% at the conclusion of maintenance procedures. The acceptance margin could be narrowed even further by a factor of 2.5 by increasing the test voltage from 40 V up to 100 V. Based on experience over the last two years, resistor and

  17. Measurement of longitudinal impedance for a KAON test pipe model with TSD-calibration method

    International Nuclear Information System (INIS)

    Yin, Y.; Oram, C.; Ilinsky, N.; Reinhardt-Nikulin, P.

    1991-05-01

    We report measurements of longitudinal impedances for a KAON factory beam pipe model by means of the TSD-calibration method. The experimental method and the results are discussed. The frequency band is from 48 MHz up to 900 MHz, within which range the method produces measured impedances accurate enough to be useful in indicating whether a test pipe will have a suitably low impedance. (Author) 9 refs., 7 figs

  18. Microwave effective surface impedance of structures including a high-Tc superconducting film

    International Nuclear Information System (INIS)

    Hartemann, P.

    1992-01-01

    The microwave effective surface impedances of different stacks made of high-temperature superconducting films, dielectric materials and bulk normal metals were computed. The calculations were based on the two-fluid model of superconductors and the conventional transmission line theory. These effective impedances are compared to the calculated intrinsic surface impedances of the stacked superconducting films. The considered superconducting material has been the oxide YBa 2 Cu 3 O 7 epitaxially grown on crystalline substrates (MgO, LaAlO 3 , SrTiO 3 ), the film thickness ranging from a few nm to 1μm. Discrepancies between the effective surface resistances or reactances and the corresponding intrinsic values were determined at 10 GHz for non resonant or resonant structures. At resonance the surface resistance discrepancy exhibits a sharp peak which reaches 10 4 or more in relative value according to the geometry and the used materials. Obviously the effective surface reactance shows also huge variations about the resonance and may be negative. Moreover geometries allowing to obtain an effective resistance smaller than the film intrinsic value have been found. The effects of the resonance phenomenon on the electromagnetic wave reflectivity and reflection phase shift are investigated. Therefore the reported theoretical results demonstrate that the effective surface impedance of YBCO films with a thickness smaller than 500 nm can be very different from the intrinsic film impedance according to the structures. (Author). 3 refs., 10 figs., 2 tabs

  19. Self-focusing of electromagnetic surface waves on a nonlinear impedance surface

    Energy Technology Data Exchange (ETDEWEB)

    Luo, Zhangjie, E-mail: zhangjie-luo-cn@126.com [College of Electronics and Information Engineering, Sichuan University, Chengdu 610064 (China); Applied Electromagnetics Group, Electrical and Computer Engineering Department, University of California, San Diego, California 92093 (United States); Chen, Xing [College of Electronics and Information Engineering, Sichuan University, Chengdu 610064 (China); Long, Jiang; Quarfoth, Ryan; Sievenpiper, Daniel, E-mail: dsievenpiper@eng.ucsd.edu [Applied Electromagnetics Group, Electrical and Computer Engineering Department, University of California, San Diego, California 92093 (United States)

    2015-05-25

    The self-focusing effect of optical beams has been a popular topic of study for quite a while, but such a nonlinear phenomenon at microwave frequencies has never been realized, partially due to the underdevelopment of nonlinear material. In this research, self-focused electromagnetic (EM) surface waves are demonstrated on a circuit-based, power-dependent impedance surface. The formation of a self-focused beam is investigated using a series of discrete-time simulations, and the result is further validated in measurement. It is experimentally observed that, in contrast to the normal scattering of low-power surface waves, high-power waves propagate through the surface while maintaining narrow beam width, and even converge extremely tightly to create a hot spot with higher power. The result is essentially a nonlinear effect of the surface that compensates for the natural tendency of surface waves to diffract. This intriguing experiment can be extended to various potential EM applications such as power-dependent beam steering antennas and nonlinear microwave propagation or dissipation.

  20. Application of impedance spectroscopy method for analysis of benzanol fuels

    Directory of Open Access Journals (Sweden)

    Mamykin A. V.

    2015-06-01

    Full Text Available The authors have developed a method for express control of three component «gasoline-alcohol-water» fuel mixtures based on the spectral impedance investigation of benzanol mixture in the frequency range of 500 Hz — 10 kHz. A correlation dependence between the dielectric constant and the specific resistance of the fuel mixture on content of ethanol and water in the mixture has been found. On the basis of this dependence a calibration nomogram to quantify the gasoline and water-alcohol components content in the test benzanol fuel in the actual range of concentrations has been formed. The nomogram allows determining the water-alcohol and gasoline parts in the analyzed fuel with an error of no more than 1% vol., while the strength of water-alcohol solution is determined with an error of no more than 0.8% vol. The obtained nomogram can also give information about critical water content in the benzanol fuel to prevent its eventual phase separation. It is shown that the initial component composition of different gasoline brands has no significant effect on the electrical characteristics of the studied benzanol fuels, which makes the evaluation of alcohol and water content in the fuel sufficiently accurate. for practical applications.

  1. INVESTIGATION OF CEMENT CONCRETE CONGLOMERATE SOLIDIFICATION PROCESS BY IMPEDANCE SPECTROSCOPY METHOD

    Directory of Open Access Journals (Sweden)

    S. N. Bandarenka

    2015-01-01

    Full Text Available One of the most prospective directions in preservation  and increase of service live of  road pavements is a construction of  automobile roads with cement concrete surface. Modern tendencies for provision of road construction quality presuppose a necessity to control processes of solidification and subsequent destruction of the material while forming and using cement concrete conglomerate being considered as a basic element of the road surface.  Multiyear practical experience of  automobile road operation using cement concrete pavements reveals an importance for monitoring  such processes as formation and destruction of cement concrete materials. An impedance spectroscopy method has been tried out and proposed as a tool for solution of the given problem.Experimental samples of cement concrete have been prepared for execution of tests, graded silica sand and granite chippings with particle size from 0.63 to 2.5 mm have been used as a fine aggregate in the samples. Dependencies of resistance (impedance on AC-current frequency  have been studied for samples of various nature and granulometric composition. The Gamry  G300 potentiostat has been used for measurement of complex impedance value. A spectrum analysis and calculation of equivalent circuit parameters calculation have been carried out while using EIS Spectrum Analyzer program.Comparison of impedance spectra for the prepared cement concrete samples have made it possible to reveal tendencies in changing spectrum parameters during solidification and subsequent contact with moisture in respect of every type of the sample. An equivalent electrical circuit has been developed that  characterizes physical and chemical processes which are accompanied by charge transfer in cement concrete conglomerate. The paper demonstrates a possibility to use an impedance spectroscopy for solution of a number of actual problems in the field of cement concrete technology problems. Particularly, the problems

  2. High transmission acoustic focusing by impedance-matched acoustic meta-surfaces

    KAUST Repository

    Al Jahdali, Rasha

    2016-01-19

    Impedance is an important issue in the design of acoustic lenses because mismatched impedance is detrimental to real focusing applications. Here, we report two designs of acoustic lenses that focus acoustic waves in water and air, respectively. They are tailored by acoustic meta-surfaces, which are rigid thin plates decorated with periodically distributed sub-wavelength slits. Their respective building blocks are constructed from the coiling-up spaces in water and the layered structures in air. Analytic analysis based on coupled-mode theory and transfer matrix reveals that the impedances of the lenses are matched to those of the background media. With these impedance-matched acoustic lenses, we demonstrate the acoustic focusing effect by finite-element simulations.

  3. Electrochemical Impedance and Polarization Corrosion Studies of Tantalum Surface Modified by DC Plasma Electrolytic Oxidation

    Directory of Open Access Journals (Sweden)

    Maciej Sowa

    2018-04-01

    Full Text Available Tantalum has recently become an actively researched biomaterial for the bone reconstruction applications because of its excellent corrosion resistance and successful clinical records. However, a bare Ta surface is not capable of directly bonding to the bone upon implantation and requires some method of bioactivation. In this study, this was realized by direct current (DC plasma electrolytic oxidation (PEO. Susceptibility to corrosion is a major factor determining the service-life of an implant. Therefore, herein, the corrosion resistance of the PEO coatings on Ta was investigated in Ringer’s solution. The coatings were formed by galvanostatic anodization up to 200, 300 and 400 V, after which the treatment was conducted potentiostatically until the total process time amounted to 5 min. Three solutions containing Ca(H2PO22, Ca(HCOO2 and Mg(CH3COO2 were used in the treatment. For the corrosion characterization, electrochemical impedance spectroscopy and potentiodynamic polarization techniques were chosen. The coatings showed the best corrosion resistance at voltages low enough so that the intensive sparking was absent, which resulted in the formation of thin films. The impedance data were fitted to the equivalent electrical circuits with two time constants, namely R(Q[R(QR] and R(Q[R(Q[RW

  4. Impedance spectroscopy studies of surface engineered TiO2 ...

    Indian Academy of Sciences (India)

    Administrator

    earlier work where various functionalized aromatic orga- nophosphates were used, here different organophosphate ligand molecules containing linear, aromatic and extended aromatic chemical groups were employed. Figure 1 shows the chemical structures of organophosphate ligands that were examined as filler surface ...

  5. Surface properties of topological insulator Bi2Se3 nanoparticles separated by impedance spectroscopy

    Science.gov (United States)

    Choi, Dong Min; Lee, Kyu Won; Jeon, Gi Wan; Kim, Do Wan; Lee, Cheol Eui

    2017-06-01

    We have separated the surface and bulk electrical properties of the Bi2Se3 nanoparticles by means of impedance spectroscopy. An equivalent circuit analysis of the complex impedance data comprising two separate resistance components, RB and RS, and two separate inductance components, LB and LS, enabled us to separate the bulk and surface properties of the topological insulator. One of the resistance components, RS, attributed to the surface, showed no temperature dependence, whereas the other, RB, attributed to the bulk, showed a weak metallic behavior. With increasing surface-to-bulk ratio by mixing with insulating Al2O3 nanoparticles up to the ratio of 1:1, the surface resistivity showed decrease up to ˜70%, whereas the bulk resistivity showed increase up to ˜150%. While the bulk state showed increasing electrical resistivity up to 200% with aging up to 30 days, the surface state resistivity did not show an aging effect.

  6. Error Correction of EMTDC Line and Cable Series Impedance Calculations Compared to Traditional Methods

    DEFF Research Database (Denmark)

    Sørensen, Stefan; Nielsen, Hans Ove

    2002-01-01

    In this paper we present comparison of different line and cable series impedance calculation methods, where the correction of a discovered PSCAD/EMIDC v.3.0.8 calculation error of the cable series impedance results n deviation under 0.1% instead of the previous method which gave approximately 10%......% deviation to other methods. The correction is done by adjusting he earth return path impedance for the cable model, and will thereby form the basis for a future comparison with measured data from a real full scale earth fault experiment on a mixed line and cable network.......In this paper we present comparison of different line and cable series impedance calculation methods, where the correction of a discovered PSCAD/EMIDC v.3.0.8 calculation error of the cable series impedance results n deviation under 0.1% instead of the previous method which gave approximately 10...

  7. The Impedance Due to the Roughness of Metallic Surface

    Energy Technology Data Exchange (ETDEWEB)

    Bane, Karl L.F.; Chao, Alex W.; Ng, Cho-K.; /SLAC

    2011-08-26

    In some future accelerator designs, such as that of the Linear Coherent Light Source (LCLS), the bunch is very short, with an rms length on the order of 10's of microns, and the effective skin depth of the vacuum chamber walls can be very small compared to 1 micron. If the skin depth is small compared to the scale of the surface roughness then the wakefield due to the walls will be dominated by the roughness, and not by the wall resistance. To estimate the wakefields of a rough, metallic surface we begin with a simple, analytical model. Then we apply the MAFIA 3-dimensional, time-domain computer module, T3 to check and find the correct coefficient for the model.

  8. Accurate position estimation methods based on electrical impedance tomography measurements

    Science.gov (United States)

    Vergara, Samuel; Sbarbaro, Daniel; Johansen, T. A.

    2017-08-01

    Electrical impedance tomography (EIT) is a technology that estimates the electrical properties of a body or a cross section. Its main advantages are its non-invasiveness, low cost and operation free of radiation. The estimation of the conductivity field leads to low resolution images compared with other technologies, and high computational cost. However, in many applications the target information lies in a low intrinsic dimensionality of the conductivity field. The estimation of this low-dimensional information is addressed in this work. It proposes optimization-based and data-driven approaches for estimating this low-dimensional information. The accuracy of the results obtained with these approaches depends on modelling and experimental conditions. Optimization approaches are sensitive to model discretization, type of cost function and searching algorithms. Data-driven methods are sensitive to the assumed model structure and the data set used for parameter estimation. The system configuration and experimental conditions, such as number of electrodes and signal-to-noise ratio (SNR), also have an impact on the results. In order to illustrate the effects of all these factors, the position estimation of a circular anomaly is addressed. Optimization methods based on weighted error cost functions and derivate-free optimization algorithms provided the best results. Data-driven approaches based on linear models provided, in this case, good estimates, but the use of nonlinear models enhanced the estimation accuracy. The results obtained by optimization-based algorithms were less sensitive to experimental conditions, such as number of electrodes and SNR, than data-driven approaches. Position estimation mean squared errors for simulation and experimental conditions were more than twice for the optimization-based approaches compared with the data-driven ones. The experimental position estimation mean squared error of the data-driven models using a 16-electrode setup was less

  9. Accurate position estimation methods based on electrical impedance tomography measurements

    International Nuclear Information System (INIS)

    Vergara, Samuel; Sbarbaro, Daniel; Johansen, T A

    2017-01-01

    Electrical impedance tomography (EIT) is a technology that estimates the electrical properties of a body or a cross section. Its main advantages are its non-invasiveness, low cost and operation free of radiation. The estimation of the conductivity field leads to low resolution images compared with other technologies, and high computational cost. However, in many applications the target information lies in a low intrinsic dimensionality of the conductivity field. The estimation of this low-dimensional information is addressed in this work. It proposes optimization-based and data-driven approaches for estimating this low-dimensional information. The accuracy of the results obtained with these approaches depends on modelling and experimental conditions. Optimization approaches are sensitive to model discretization, type of cost function and searching algorithms. Data-driven methods are sensitive to the assumed model structure and the data set used for parameter estimation. The system configuration and experimental conditions, such as number of electrodes and signal-to-noise ratio (SNR), also have an impact on the results. In order to illustrate the effects of all these factors, the position estimation of a circular anomaly is addressed. Optimization methods based on weighted error cost functions and derivate-free optimization algorithms provided the best results. Data-driven approaches based on linear models provided, in this case, good estimates, but the use of nonlinear models enhanced the estimation accuracy. The results obtained by optimization-based algorithms were less sensitive to experimental conditions, such as number of electrodes and SNR, than data-driven approaches. Position estimation mean squared errors for simulation and experimental conditions were more than twice for the optimization-based approaches compared with the data-driven ones. The experimental position estimation mean squared error of the data-driven models using a 16-electrode setup was less

  10. Structure Irregularity Impedes Drop Roll-Off at Superhydrophobic Surfaces

    DEFF Research Database (Denmark)

    Larsen, Simon Tylsgaard; Andersen, Nis Korsgaard; Søgaard, Emil

    2014-01-01

    -off angles is found to be caused by a decrease of the receding contact angle, which in turn is caused by an increase of the triple phase contact line of the drops for those more irregular surfaces. To understand the observation, we propose to treat the microdrops as rigid bodies and apply a torque balance...... between the torque exerted by the projected gravity force and the torque exerted by the adhesion force acting along the triple line on the receding side of the drop. This simple model provides a proper order of magnitude estimate of the measured effects....

  11. Rotational electrical impedance tomography using electrodes with limited surface coverage provides window for multimodal sensing

    Science.gov (United States)

    Lehti-Polojärvi, Mari; Koskela, Olli; Seppänen, Aku; Figueiras, Edite; Hyttinen, Jari

    2018-02-01

    Electrical impedance tomography (EIT) is an imaging method that could become a valuable tool in multimodal applications. One challenge in simultaneous multimodal imaging is that typically the EIT electrodes cover a large portion of the object surface. This paper investigates the feasibility of rotational EIT (rEIT) in applications where electrodes cover only a limited angle of the surface of the object. In the studied rEIT, the object is rotated a full 360° during a set of measurements to increase the information content of the data. We call this approach limited angle full revolution rEIT (LAFR-rEIT). We test LAFR-rEIT setups in two-dimensional geometries with computational and experimental data. We use up to 256 rotational measurement positions, which requires a new way to solve the forward and inverse problem of rEIT. For this, we provide a modification, available for EIDORS, in the supplementary material. The computational results demonstrate that LAFR-rEIT with eight electrodes produce the same image quality as conventional 16-electrode rEIT, when data from an adequate number of rotational measurement positions are used. Both computational and experimental results indicate that the novel LAFR-rEIT provides good EIT with setups with limited surface coverage and a small number of electrodes.

  12. Cable Overheating Risk Warning Method Based on Impedance Parameter Estimation in Distribution Network

    Science.gov (United States)

    Yu, Zhang; Xiaohui, Song; Jianfang, Li; Fei, Gao

    2017-05-01

    Cable overheating will lead to the cable insulation level reducing, speed up the cable insulation aging, even easy to cause short circuit faults. Cable overheating risk identification and warning is nessesary for distribution network operators. Cable overheating risk warning method based on impedance parameter estimation is proposed in the paper to improve the safty and reliability operation of distribution network. Firstly, cable impedance estimation model is established by using least square method based on the data from distribiton SCADA system to improve the impedance parameter estimation accuracy. Secondly, calculate the threshold value of cable impedance based on the historical data and the forecast value of cable impedance based on the forecasting data in future from distribiton SCADA system. Thirdly, establish risks warning rules library of cable overheating, calculate the cable impedance forecast value and analysis the change rate of impedance, and then warn the overheating risk of cable line based on the overheating risk warning rules library according to the variation relationship between impedance and line temperature rise. Overheating risk warning method is simulated in the paper. The simulation results shows that the method can identify the imedance and forecast the temperature rise of cable line in distribution network accurately. The result of overheating risk warning can provide decision basis for operation maintenance and repair.

  13. IMPEDANCE METHOD OF MEASURING OF THE TITRATABLE ACIDITY OF YOGURT

    Directory of Open Access Journals (Sweden)

    Miroslav Vasilev

    2016-10-01

    Full Text Available In the present work are analyzed studies related to changes in the active impedance component of the dairy environment caused by the flow of lactic fermentation and coagulation of casein in milk. The aim of this work was to determine the relationship between the relative change of titratable acidity and the relative change of active impedance component of the dairy environment with lactic fermentation, causing coagulation of the casein in milk. . The data were interpolated with cubic spline, visualizing how when the fat content increases, the electrical resistance increases too. All data, collected during the tests would complement and be used for solving the optimization problem to determine the time of completion of the coagulation in future work.

  14. An Analytical Method of Auxiliary Sources Solution for Plane Wave Scattering by Impedance Cylinders

    DEFF Research Database (Denmark)

    Larsen, Niels Vesterdal; Breinbjerg, Olav

    2004-01-01

    Analytical Method of Auxiliary Sources solutions for plane wave scattering by circular impedance cylinders are derived by transformation of the exact eigenfunction series solutions employing the Hankel function wave transformation. The analytical Method of Auxiliary Sources solution thus obtained...

  15. Development of Computational Method of Impedance with respect to Vertical and Rotatory Symmetric Grounding Electrodes

    Science.gov (United States)

    Tanabe, Kazuo; Kawamoto, Tadashi

    It is needed to study the transient performance of grounding systems for lightning surges to ensure the electromagnetic compatibility (EMC) of sensitive electronics such as information devices and digital relays in substations and/or residential houses. Therefore, an easy method of estimating frequency response to represent the transient performance of grounding systems and its incorporation into Electromagnetic Transient Program (EMTP) are highly desired. EMTP based on circuit theory has been applied to resolve the transient performance of electrical apparatus consisting of cables and conductors which are parallel to the ground surface, in which the propagation of TEM waves that are plane waves is implicated, and devices such as surge arresters represented by lumped elements. However, conductors which are vertical to the ground surface have not been modeled because TM waves propagate on such conductors and the characteristics in early time, when the approximation of plane waves is not adapted, are required. In this paper, for the vertical and rotatory symmetric grounding electrodes, we propose a computational method for the impedance, which is defined as the complex ratio of the potential of its top at the ground surface to the current flowing into it in the frequency domain. The potential is derived from the integral of the horizontal component of electric fields along the path reaching the electrode on the ground surface because the potential could be uniquely defined in the case of a horizontal plane by considering the electromagnetic field in the configuration discussed here. We then calculated the potential of the electrode and current flowing into it in the time domain by computational analysis of transient performance based on the FD-TD method (CATP) and the impedance up to 20MHz in the frequency domain were derived using the Fourier transforms of the potential and current in the time domain.

  16. Fundamental impedance identification method for grid-connected voltage source inverters

    DEFF Research Database (Denmark)

    Sun, Xiaofeng; Chen, J.; Guerrero, Josep M.

    2014-01-01

    Considering the importance of line fundamental impedance from the inverter to the point of common coupling (PCC) in microgrids, this study analyses the influence of fundamental impedance on system stability. Line fundamental impedance values not only apply to decoupled droop control, which can...... realise accurate control between active and reactive power, but also regulate the droop coefficient to eliminate system circulation, realise power sharing and improve system stability when a multi-distributed generation system operates in parallel. Moreover, the PCC can sense grid fault on the basis...... of variations in fundamental impedance. A novel fundamental impedance identification method that adopts a constant power control strategy by varying the active and reactive powers in the grid-connected mode is proposed. In addition, the proposed method has online real-time calculation capability. This strategy...

  17. An electrochemical study of corrosion protection by primer-topcoat systems on 4130 steel with ac impedance and dc methods

    Science.gov (United States)

    Mendrek, M. J.; Higgins, R. H.; Danford, M. D.

    1988-01-01

    To investigate metal surface corrosion and the breakdown of metal protective coatings, the ac impedance method is applied to six systems of primer coated and primer topcoated 4130 steel. Two primers were used: a zinc-rich epoxy primer and a red lead oxide epoxy primer. The epoxy-polyamine topcoat was used in four of the systems. The EG and G-PARC Model 368 ac impedance measurement system, along with dc measurements with the same system using the polarization resistance method, were used to monitor changing properties of coated 4230 steel disks immersed in 3.5 percent NaCl solutions buffered at pH 5.4 over periods of 40 to 60 days. The corrosion system can be represented by an electronic analog called an equivalent circuit consisting of resistors and capacitors in specific arrangements. This equivalent circuit parallels the impedance behavior of the corrosion system during a frequency scan. Values for the resistors and capacitors, that can be assigned in the equivalent circuit following a least-squares analysis of the data, describe changes that occur on the corroding metal surface and in the protective coatings. Two equivalent circuits have been determined that predict the correct Bode phase and magnitude of the experimental sample at different immersion times. The dc corrosion current density data are related to equivalent circuit element parameters. Methods for determining corrosion rate with ac impedance parameters are verified by the dc method.

  18. Visceral fat estimation method by bioelectrical impedance analysis and causal analysis

    Science.gov (United States)

    Nakajima, Hiroshi; Tasaki, Hiroshi; Tsuchiya, Naoki; Hamaguchi, Takehiro; Shiga, Toshikazu

    2011-06-01

    It has been clarified that abdominal visceral fat accumulation is closely associated to the lifestyle disease and metabolic syndrome. The gold standard in medical fields is visceral fat area measured by an X-ray computer tomography (CT) scan or magnetic resonance imaging. However, their measurements are high invasive and high cost; especially a CT scan causes X-ray exposure. They are the reasons why medical fields need an instrument for viscera fat measurement with low invasive, ease of use, and low cost. The article proposes a simple and practical method of visceral fat estimation by employing bioelectrical impedance analysis and causal analysis. In the method, abdominal shape and dual impedances of abdominal surface and body total are measured to estimate a visceral fat area based on the cause-effect structure. The structure is designed according to the nature of abdominal body composition to be fine-tuned by statistical analysis. The experiments were conducted to investigate the proposed model. 180 subjects were hired to be measured by both a CT scan and the proposed method. The acquired model explained the measurement principle well and the correlation coefficient is 0.88 with the CT scan measurements.

  19. Graphene as a high impedance surface for ultra-wideband electromagnetic waves

    Energy Technology Data Exchange (ETDEWEB)

    Aldrigo, Martino; Costanzo, Alessandra [Department of Electrical, Electronic, and Information Engineering “Guglielmo Marconi” – DEI, University of Bologna, Viale del Risorgimento, 2, 40132 Bologna (Italy); Dragoman, Mircea [National Institute for Research and Development in Microtechnology (IMT), P.O. Box 38-160, 023573 Bucharest (Romania); Dragoman, Daniela [Department of Physics, University of Bucharest, P.O. Box MG-11, 077125 Bucharest (Romania)

    2013-11-14

    The metals are regularly used as reflectors of electromagnetic fields emitted by antennas ranging from microwaves up to THz. To enhance the reflection and thus the gain of the antenna, metallic high impedance surfaces (HIS) are used. HIS is a planar array of continuous metallic periodic cell surfaces able to suppress surface waves, which cause multipath interference and backward radiation in a narrow bandwidth near the cell resonance. Also, the image currents are reduced, and therefore the antenna can be placed near the HIS. We demonstrate that graphene is acting as a HIS surface in a very large bandwidth, from microwave to THz, suppressing the radiation leakages better than a metal.

  20. Cranial impedance plethysmography-rheoncephalography as a method of detection of cerebrovascular disease.

    Science.gov (United States)

    1965-01-01

    Rheoencephalography, the monitoring of cerebral blood flow by impedance methods, has been used successfully in clinical medicine in Europe and Russia but not in the United States. Three cases are presented to demonstrate the potential value of this m...

  1. A Method of Function Space for Vertical Impedance Function of a Circular Rigid Foundation on a Transversely Isotropic Ground

    Directory of Open Access Journals (Sweden)

    Morteza Eskandari-Ghadi

    2014-06-01

    Full Text Available This paper is concerned with investigation of vertical impedance function of a surface rigid circular foundation resting on a semi-infinite transversely isotropic alluvium. To this end, the equations of motion in cylindrical coordinate system, which because of axissymmetry are two coupled equations, are converted into one partial differential equation using a method of potential function. The governing partial differential equation for the potential function is solved via implementing Hankel integral transforms in radial direction. The vertical and radial components of displacement vector are determined with the use of transformed displacement-potential function relationships. The mixed boundary conditions at the surface are satisfied by specifying the traction between the rigid foundation and the underneath alluvium in a special function space introduced in this paper, where the vertical displacements are forced to satisfy the rigid boundary condition. Through exercising these restraints, the normal traction and then the vertical impedance function are obtained. The results are then compared with the existing results in the literature for the simpler case of isotropic half-space, which shows an excellent agreement. Eventually, the impedance functions are presented in terms of dimensionless frequency for different materials. The method presented here may be used to obtain the impedance function in any other direction as well as in buried footing in layered media.

  2. Electrochemical Impedance Response of the surface treated FMS in Liquid Sodium Environment

    International Nuclear Information System (INIS)

    Lee, Jeong Hyeon; Shin, Sang Hun; Kim, Ji Hyun

    2014-01-01

    HT9 and Gr.92 are known as compatible in sodium environment because the usual refueling time of SFRs is designed about 54 months. It is very important to investigate the corrosion-related behavior such as surface corrosion rate, carburization, decarburization and mechanical properties for its operation time. SiC and Si 3 N 4 CVD coating for decarburization barrier on the surface of FMS is considered in this study. The decarburization process where dissolved carbon near the specimen surface disused in to the liquid sodium. This process can originate from the difference between dissolved carbon in the material and liquid sodium. A compatibility test the cladding tube revealed that a decrease of the mechanical property instigated by the aging proves governed the whole mechanical property. To monitor the corrosion behavior of these candidate materials in sodium environment, Electrochemical Impedance Spectroscopy (EIS) method is first introduced and investigated in this study. The compatibility of cladding and structural materials with sodium has to be carefully investigated, as sodium could promote corrosion of cladding and structural materials in two ways. One is produced by the dissolution of alloy constituents into the sodium, and the other is produced through a chemical reaction with impurities (especially oxygen and carbon) in the sodium environment. EIS test with pre-oxidized Gr. 92 specimen in 200 .deg. C liquid sodium environment was carried out in this study. A clear Nyquist and Bode plots were obtained in liquid metal environment and the resistance of sodium and the oxide, and the capacitance of the oxide were measured from this result

  3. Impedance spectroscopy as a method for evaluation of lithium-thionyl chloride cells

    Energy Technology Data Exchange (ETDEWEB)

    Kanevskii, L.S.; Bagotzky, V.S.; Nizhnikovskii, E.A. [Frumkin Institute of Electrochemistry, Moscow (Russian Federation)

    1995-04-01

    Impedance spectroscopy was evaluated as a method for ascertaining the state of constituent components of Li-thionyl chloride cells. No unambiguous correlation between impedance characteristics and residual capacity was detected as a result of investigation of a large population of different size and capacity Li-thionyl chloride cells. Impedance studies of nonpolarized lithium electrodes in operating cells resulted in a conclusion that the diagnostics of Li-thionyl chloride cells is extremely difficult, due to the specific nature of lithium passivation in operating cells and the influence on this process exerted by sulfur dioxide generated during discharge.

  4. Evaluating surface protonic transport on cerium oxide via electrochemical impedance spectroscopy measurement

    Science.gov (United States)

    Manabe, Ryo; Stub, Sindre Østby; Norby, Truls; Sekine, Yasushi

    2018-02-01

    Surface protonic transport on cerium oxide (CeO2) was investigated using electrochemical impedance spectroscopy (EIS). CeO2 pellets showing low relative density: approximately 60%, was prepared for the purpose. The structure and morphology of the prepared CeO2 pellets were confirmed from XRD and SEM measurements. Results show that the pellets had a pure cubic phase, with open pores on which water can be adsorbed. Electrochemical impedance spectroscopy measurements were taken to evaluate the surface protonic transport on CeO2 as a function of temperature and as a function of partial pressure of water (PH2O) at 400 °C. Investigations of the temperature dependence of the conductivity revealed that only the conductivities of surface grain bulk (σintra) and surface grain boundary (σinter) increased with decreasing temperatures under wet conditions (PH2O = 0.026 atm). The PH2O dependence of surface conductivities (σintra and σinter) revealed that σintra increases strongly with PH2O at 400 °C. These findings provide evidence that water adsorbates play an important role in surface protonic transport on CeO2 at low temperatures. Surface protonic transport at low temperatures can contribute to the expansion of applications for electrical and catalytic processes.

  5. Estimating the absorptive root area in Norway spruce by using the common direct and indirect earth impedance methods

    Czech Academy of Sciences Publication Activity Database

    Čermák, J.; Cudlín, Pavel; Gebauer, R.; Borja, I.; Martinková, M.; Staněk, Z.; Koller, J.; Neruda, J.; Nadezhdina, N.

    2013-01-01

    Roč. 372, 1-2 (2013), s. 401-415 ISSN 0032-079X R&D Projects: GA MŠk(CZ) ED1.1.00/02.0073; GA MŠk OC10023 Institutional support: RVO:67179843 Keywords : Active absorptive fine root area index * Fine root surface * Modified earth impedance * Picea abies * Root research methods Subject RIV: EH - Ecology, Behaviour Impact factor: 3.235, year: 2013

  6. System-on-chip integration of a new electromechanical impedance calculation method for aircraft structure health monitoring.

    Science.gov (United States)

    Boukabache, Hamza; Escriba, Christophe; Zedek, Sabeha; Medale, Daniel; Rolet, Sebastien; Fourniols, Jean Yves

    2012-10-11

    The work reported on this paper describes a new methodology implementation for active structural health monitoring of recent aircraft parts made from carbon-fiber-reinforced polymer. This diagnosis is based on a new embedded method that is capable of measuring the local high frequency impedance spectrum of the structure through the calculation of the electro-mechanical impedance of a piezoelectric patch pasted non-permanently onto its surface. This paper involves both the laboratory based E/M impedance method development, its implementation into a CPU with limited resources as well as a comparison with experimental testing data needed to demonstrate the feasibility of flaw detection on composite materials and answer the question of the method reliability. The different development steps are presented and the integration issues are discussed. Furthermore, we present the unique advantages that the reconfigurable electronics through System-on-Chip (SoC) technology brings to the system scaling and flexibility. At the end of this article, we demonstrate the capability of a basic network of sensors mounted onto a real composite aircraft part specimen to capture its local impedance spectrum signature and to diagnosis different delamination sizes using a comparison with a baseline.

  7. System-on-Chip Integration of a New Electromechanical Impedance Calculation Method for Aircraft Structure Health Monitoring

    Directory of Open Access Journals (Sweden)

    Daniel Medale

    2012-10-01

    Full Text Available The work reported on this paper describes a new methodology implementation for active structural health monitoring of recent aircraft parts made from carbon-fiber-reinforced polymer. This diagnosis is based on a new embedded method that is capable of measuring the local high frequency impedance spectrum of the structure through the calculation of the electro-mechanical impedance of a piezoelectric patch pasted non-permanently onto its surface. This paper involves both the laboratory based E/M impedance method development, its implementation into a CPU with limited resources as well as a comparison with experimental testing data needed to demonstrate the feasibility of flaw detection on composite materials and answer the question of the method reliability. The different development steps are presented and the integration issues are discussed. Furthermore, we present the unique advantages that the reconfigurable electronics through System-on-Chip (SoC technology brings to the system scaling and flexibility. At the end of this article, we demonstrate the capability of a basic network of sensors mounted onto a real composite aircraft part specimen to capture its local impedance spectrum signature and to diagnosis different delamination sizes using a comparison with a baseline.

  8. Finite element computation of elliptical vocal tract impedances using the two-microphone transfer function method.

    Science.gov (United States)

    Arnela, Marc; Guasch, Oriol

    2013-06-01

    A two-microphone transfer function (TMTF) method is adapted to a numerical framework to compute the radiation and input impedances of three-dimensional vocal tracts of elliptical cross-section. In its simplest version, the TMTF method only requires measuring the acoustic pressure at two points in an impedance duct and the postprocessing of the corresponding transfer function. However, some considerations are to be taken into account when using the TMTF method in the numerical context, which constitute the main objective of this paper. In particular, the importance of including absorption at the impedance duct walls to avoid lengthy numerical simulations is discussed and analytical complex axial wave numbers for elliptical ducts are derived for this purpose. It is also shown how the direct impedance of plane wave propagation can be computed beyond the TMTF maximum threshold frequency by appropriate location of the virtual microphones. Virtual microphone spacing is also discussed on the basis of the so-called singularity factor. Numerical examples include the computation of the radiation impedance of vowels /a/, /i/, and /u/ and the input impedance of vowel /a/, for simplified vocal tracts of circular and elliptical cross-sections.

  9. [Measuring bioelectric myocardial impedance as a noninvasive method for diagnosis of graft rejection after heart transplantation].

    Science.gov (United States)

    Pfitzmann, R; Müller, J; Grauhan, O; Cohnert, T; Hetzer, R

    1998-04-01

    12 beagle dogs underwent neck-heart transplantation and were immunosuppressed with cyclosporine and methylprednisolone. Intramyocardial impedance was determined twice daily with four screw-in electrodes in the right and left ventricle. Transmyocardial biopsies and the intra-myocardial electrogram (IMEG) were performed as reference methods. 19 rejection episodes were induced. When acute rejection was seen in histology the animals were treated with pulsed 125 mg methylprednisolone over 5 consecutive days and immunosuppression was raised to sufficient levels. Successful treatment of rejection was controlled by biopsy. All hearts showed a uniform decrease of impedance of about 28.3% +/- 5.5% immediately after implantation, then reaching a stable plateau after 7 to 8 days. Impedance values then remained unchanged as long as rejection was absent. Biopsy findings of grade 1A to 1B (ISHLT) were accompanied by a statistically significant increase of impedance of 12.2% +/- 2.5%, of grade 2 to 3A of 19.2% +/- 3.2%, and of grade 3B to 4 of 27.0% +/- 2.9%. Sensitivity was 95%, specificity 91%. Successful treatment of rejection led to a uniform decrease of impedance to intramyocardial impedance for high frequencies can reliably indicate alterations of the cell membrane and the intracellular space during acute cardiac allograft rejection. The amount of increase of impedance is a reliable noninvasive parameter to graduate acute cardiac allograft rejection. The success of treatment of rejection can also be monitored by impedance. This noninvasive method is applicable for telemetric rejection monitoring via an implantable device, which would allow continuous rejection surveillance of a patient at home without hospital admission.

  10. A Calculation Method of Electric Distance and Subarea Division Application Based on Transmission Impedance

    Science.gov (United States)

    Fang, G. J.; Bao, H.

    2017-12-01

    The widely used method of calculating electric distances is sensitivity method. The sensitivity matrix is the result of linearization and based on the hypothesis that the active power and reactive power are decoupled, so it is inaccurate. In addition, it calculates the ratio of two partial derivatives as the relationship of two dependent variables, so there is no physical meaning. This paper presents a new method for calculating electrical distance, namely transmission impedance method. It forms power supply paths based on power flow tracing, then establishes generalized branches to calculate transmission impedances. In this paper, the target of power flow tracing is S instead of Q. Q itself has no direction and the grid delivers complex power so that S contains more electrical information than Q. By describing the power transmission relationship of the branch and drawing block diagrams in both forward and reverse directions, it can be found that the numerators of feedback parts of two block diagrams are all the transmission impedances. To ensure the distance is scalar, the absolute value of transmission impedance is defined as electrical distance. Dividing network according to the electric distances and comparing with the results of sensitivity method, it proves that the transmission impedance method can adapt to the dynamic change of system better and reach a reasonable subarea division scheme.

  11. A New Method of On-line Grid Impedance Estimation for PV Inverter

    DEFF Research Database (Denmark)

    Teodorescu, Remus; Asiminoaei, Lucian; Blaabjerg, Frede

    2004-01-01

    for on-line measuring the grid impedance is presented. The presented method requires no extra hardware being accommodated by typical PV inverters, sensors and CPU, to provide a fast and low cost approach of on-line impedance measurement. By injecting a non-characteristic harmonic current and measuring......The recent increase in photo-voltaic (PV) installations calls for new and better power quality requirements with respect to connection to the grid supply. Therefore, different methods are typically used for continuous grid monitoring, usually by using external devices. In this paper a new method...... the voltage grid response it is possible to evaluate the grid impedance. Practical test on an existing PV inverter validate the new method....

  12. Method for Impeding Degradation of Porous Silicon Structures

    Science.gov (United States)

    Vilentchouk, Biana Godin; Ferrari, Mauro

    2011-01-01

    This invention relates to surface modification of porosified silicon (pSi) structures with poly(alkylene) glycols for the purpose of controlled degradation of the silicon matrix and tailored release of encapsulated substances for biomedical applications. The pSi structures are currently used in diverse biomedical applications including bio-molecular screening, optical bio-sensoring, and drug delivery by means of injectable/orally administered carriers and implantable devices. The size of the pores and the surface chemistry of the pSi structure can be controlled during the microfabrication process and thereafter. A fine regulation of the degradation kinetics of mesoporous silicon structures is of fundamental importance. Polyethylene glycols (PEGs) represent the major category of surface modifying agents used in classical drug delivery systems and in pharmaceutical dosage forms. PEGylation enables avoidance of RES uptake, thus prolonging circulation time of intravenously injectable nanovectors. PEG molecules demonstrate little toxicity and immunogenicity, and are cleared from the body through the urine (molecular weight, MW less than 30 kDa) or in the feces (MW greater than 30kDa). The invention focuses on the possibility of finely tuning the degradation kinetics of the pSi nanovectors and other structures through surface conjugation of PEGs with various backbone lengths/MWs. To prove the concept, pSi nanovectors were covalently conjugated to seven PEGs with MW from 245 to 5,000 Da and their degradation kinetics in physiologically relevant media (phosphate buffer saline, PBS pH7.4, and fetal bovine serum) was assessed by the elemental analysis of the Si using inductive coupled plasma atomic emission spectroscopy (ICP-AES). The conjugation of the PEG with lowest MW to the nanovectors surface did not induce any change in the degradation kinetics in serum, but inhibited degradation and consequently the release of orthosilicic acid into buffer. When PEGs with the longer

  13. On the Use of Experimental Methods to Improve Confidence in Educed Impedance

    Science.gov (United States)

    Jones, Michael G.; Watson, Willie R.

    2011-01-01

    Results from impedance eduction methods developed by NASA Langley Research Center are used throughout the acoustic liner community. In spite of recent enhancements, occasional anomalies persist with these methods, generally at frequencies where the liner produces minimal attenuation. This investigation demonstrates an experimental approach to educe impedance with increased confidence over a desired frequency range, by combining results from successive tests with different cavity depths. A series of tests is conducted with three wire-mesh facesheets, for which the results should be weakly dependent on source sound pressure level and mean grazing flow speed. First, a raylometer is used to measure the DC flow resistance of each facesheet. These facesheets are then mounted onto a frame and a normal incidence tube is used to determine their respective acoustic impedance spectra. A comparison of the acoustic resistance component with the DC flow resistance for each facesheet is used to validate the measurement process. Next, each facesheet is successively mounted onto three frames with different cavity depths, and a grazing flow impedance tube is used to educe their respective acoustic impedance spectra with and without mean flow. The no-flow results are compared with those measured in the normal incidence tube to validate the impedance eduction method. Since the anti-resonance frequency varies with cavity depth, each sample provides robust results over a different frequency range. Hence, a combination of results can be used to determine the facesheet acoustic resistance. When combined with the acoustic reactance, observed to be weakly dependent on the source sound pressure level and grazing flow Mach number, the acoustic impedance can be educed with increased confidence. Representative results of these tests are discussed, and the complete database is available in electronic format upon request.

  14. Electrothermal Impedance Spectroscopy as a Cost Efficient Method for Determining Thermal Parameters of Lithium Ion Batteries

    DEFF Research Database (Denmark)

    Swierczynski, Maciej Jozef; Stroe, Daniel Loan; Stanciu, Tiberiu

    -ion battery cells and battery packs is gaining importance. Equivalent thermal circuits’ models have proven to be relatively accurate with low computational burden for the price of low spatial resolution; nevertheless, they usually require expensive equipment for parametrization. Recent research initiated...... by Barsoukov et al. proposed electrothermal impedance spectroscopy (ETIS) as a novel and non-destructive method of characterizing the thermal properties of batteries by defining frequency dependent thermal impedance. This paper aims to systematize the state of knowledge about ETIS, presents measurement methods...

  15. An Impedance-Based Stability Analysis Method for Paralleled Voltage Source Converters

    DEFF Research Database (Denmark)

    Wang, Xiongfei; Blaabjerg, Frede; Loh, Poh Chiang

    2014-01-01

    This paper analyses the stability of paralleled voltage source converters in AC distributed power systems. An impedance-based stability analysis method is presented based on the Nyquist criterion for multiloop system. Instead of deriving the impedance ratio as usual, the system stability...... of converter and the passive network can also be predicted by the Nyquist diagrams. This method is applied to evaluate the current and voltage controller interactions of converters in both grid-connected and islanded operations. Simulations and experimental results verify the effectiveness of theoretical...... analysis....

  16. Studies of the Synchronous Sensing Method in the Microfluidic Cell Impedance Detection

    Directory of Open Access Journals (Sweden)

    Jie DAI

    2014-01-01

    Full Text Available Microfluidic impedance sensors play a significant role in point-of-care applications, clinical tests and laboratory studies. Instead of the traditional signal process method with the envelope detector, filter banks and multistage amplifier, we have reported a new implement using synchronous sampling and orthogonal detecting. By studying the intensity and phase modulation in the cell impedance sensing progress, we have calculated the SNR of the new method compare with the raw data. Base on the physical model and the calculation, we have demonstrated a simulation result which shows a capability to detect the signal of 1um cell in a noisy environment.

  17. Electrical impedance tomography methods for miniaturised 3D systems

    DEFF Research Database (Denmark)

    Canali, Chiara; Aristovich, K.; Ceccarelli, Lorenzo

    2016-01-01

    chambers (Ø 10 mm), each having eight gold plated needle electrodes vertically integrated along the chamber perimeter. As first method, the adjacent electrode configuration was tested solving the computationally simple back-projection algorithm using Comsol Multiphysics in time-difference EIT (t...

  18. Accuracy of Platelet Counting by Optical and Impedance Methods in Patients with Thrombocytopaenia and Microcytosis

    Directory of Open Access Journals (Sweden)

    Mohamed-Rachid Boulassel

    2015-11-01

    Full Text Available Objectives: Obtaining accurate platelet counts in microcytic blood samples is challenging, even with the most reliable automated haematology analysers. The CELL-DYN™ Sapphire (Abbott Laboratories, Chicago, Illinois, USA analyser uses both optical density and electronic impedance methods for platelet counting. This study aimed to evaluate the accuracy of optical density and electrical impedance methods in determining true platelet counts in thrombocytopaenic samples with microcytosis as defined by low mean corpuscular volume (MCV of red blood cells. Additionally, the impact of microcytosis on platelet count accuracy was evaluated. Methods: This study was carried out between February and December 2014 at the Haematology Laboratory of the Sultan Qaboos University Hospital in Muscat, Oman. Blood samples were collected and analysed from 189 patients with thrombocytopaenia and MCV values of <76 femtolitres. Platelet counts were tested using both optical and impedance methods. Stained peripheral blood films for each sample were then reviewed as a reference method to confirm platelet counts. Results: The platelet counts estimated by the impedance method were on average 30% higher than those estimated by the optical method (P <0.001. The estimated intraclass correlation coefficient was 0.52 (95% confidence interval: 0.41–0.62, indicating moderate reliability between the methods. The degree of agreement between methods ranged from -85.5 to 24.3 with an estimated bias of -30, suggesting that these methods generate different platelet results. Conclusion: The impedance method significantly overestimated platelet counts in microcytic and thrombocytopaenic blood samples. Further attention is therefore needed to improve the accuracy of platelet counts, particularly for patients with conditions associated with microcytosis.

  19. Nonlinear surface impedance of YBCO thin films: Measurements, modeling, and effects in devices

    International Nuclear Information System (INIS)

    Oates, D.E.; Koren, G.; Polturak, E.

    1995-01-01

    High-T c thin films continue to be of interest for passive device applications at microwave frequencies, but nonlinear effects may limit the performance. To understand these effects we have measured the nonlinear effects may limit the performance. To understand these effects we have measured the nonlinear surface impedance Z s in a number of YBa 2 Cu 3 O 7-x thin films as a function of frequency from 1 to 18 GHz, rf surface magnetic field H rf to 1500 Oe, and temperature from 4 K to T c . The results at low H rf are shown to agree quantitatively with a modified coupled-grain model and at high H rf with hysteresis-loss calculations using the Bean critical-state model applied to a thin strip. The loss mechanisms are extrinsic properties resulting from defects in the films. We also report preliminary measurements of the nonlinear impedance of Josephson junctions, and the results are related to the models of nonlinear Z s . The implications of nonlinear Z s for devices are discussed using the example of a five-pole bandpass filter

  20. New equivalent-electrical circuit model and a practical measurement method for human body impedance.

    Science.gov (United States)

    Chinen, Koyu; Kinjo, Ichiko; Zamami, Aki; Irei, Kotoyo; Nagayama, Kanako

    2015-01-01

    Human body impedance analysis is an effective tool to extract electrical information from tissues in the human body. This paper presents a new measurement method of impedance using armpit electrode and a new equivalent circuit model for the human body. The lowest impedance was measured by using an LCR meter and six electrodes including armpit electrodes. The electrical equivalent circuit model for the cell consists of resistance R and capacitance C. The R represents electrical resistance of the liquid of the inside and outside of the cell, and the C represents high frequency conductance of the cell membrane. We propose an equivalent circuit model which consists of five parallel high frequency-passing CR circuits. The proposed equivalent circuit represents alpha distribution in the impedance measured at a lower frequency range due to ion current of the outside of the cell, and beta distribution at a high frequency range due to the cell membrane and the liquid inside cell. The calculated values by using the proposed equivalent circuit model were consistent with the measured values for the human body impedance.

  1. Method, system and computer-readable media for measuring impedance of an energy storage device

    Science.gov (United States)

    Morrison, John L.; Morrison, William H.; Christophersen, Jon P.; Motloch, Chester G.

    2016-01-26

    Real-time battery impedance spectrum is acquired using a one-time record. Fast Summation Transformation (FST) is a parallel method of acquiring a real-time battery impedance spectrum using a one-time record that enables battery diagnostics. An excitation current to a battery is a sum of equal amplitude sine waves of frequencies that are octave harmonics spread over a range of interest. A sample frequency is also octave and harmonically related to all frequencies in the sum. A time profile of this sampled signal has a duration that is a few periods of the lowest frequency. A voltage response of the battery, average deleted, is an impedance of the battery in a time domain. Since the excitation frequencies are known and octave and harmonically related, a simple algorithm, FST, processes the time profile by rectifying relative to sine and cosine of each frequency. Another algorithm yields real and imaginary components for each frequency.

  2. Simple method of determining plasma impedance of streamer discharge in atmospheric air.

    Science.gov (United States)

    Okano, Daisuke

    2011-12-01

    For atmospheric streamer discharges using a lightning impulse generator, we demonstrate a method of determining the plasma impedance in a streamer region by analyzing the periodic attenuated discharge waveforms having high-frequency components. When the streamer region in the plasma can be treated as an equivalent series circuit model including resistance and inductance elements, the regression waveforms obtained by reducing and smoothing the discharge waveforms are analyzed in the equivalent circuit. We found that the streamer resistance increased exponentially with time after the discharge, whereas the streamer inductance and series impedance were constant at 4.0 Ω for longer than the first period of the discharge waveforms. Moreover, the slope of the regression curve increases more rapidly for the positive streamer resistance than for the negative resistance. Finally, the absolute values of the streamer impedance versus time were 3.3-19 Ω and 3.5-9.0 Ω for positive and negative discharges, respectively.

  3. The New Method of the PV Panels Fault Detection Using Impedance Spectroscopy

    DEFF Research Database (Denmark)

    Symonowicz, Joanna Karolina; Riedel, Nicholas; Thorsteinsson, Sune

    The aim of our project is to develop a new method for photovoltaic (PV) panel fault detection based on analyzing impedance spectroscopy (IS) spectra. Although this technique was successful in assessing the state of degradation of fuel cells and batteries, it has never been applied to PV cells...

  4. Application of the Method of Auxiliary Sources for the Analysis of Electromagnetic Scattering by Impedance Spheres

    DEFF Research Database (Denmark)

    Karamehmedovic, Mirza; Breinbjerg, Olav

    2002-01-01

    The Method of Auxiliary Sources (MAS) is applied to 3D scattering problems involving spherical impedance scatterers. The MAS results are compared with the reference spherical wave expansion (SWE) solution. It is demonstrated that good agreement is achieved between the MAS and SWE results....

  5. A study of double stranded DNA adsorption on aluminum surface by means of electrochemical impedance spectroscopy.

    Science.gov (United States)

    Heli, H

    2014-04-01

    Immobilization of DNA on the solid surfaces is one of the goals in bio- and nano-technologies. Adsorption of double stranded DNA on the surface of aluminum was electrochemically studied by means of impedance spectroscopy. Nyquist diagram of aluminum in a tris (hydroxymethyl) ammoniummethane-HCl (Tris-HCl) buffer solution, pH 7.4 consisted of two overlapped capacitive semicircles. The high-frequency semicircle was related to the passivity of Cl(-)-containing aluminum species in the oxide layer, and low-frequency semicircle was attributed to metal dissolution. When DNA was added to the Tris-HCl buffer solution, Nyquist diagrams represented an inductive loop at low frequencies due to the adsorption of DNA on the pre-covered aluminum surface by hydroxy-contained species. The DNA adsorption on the aluminum surface was also confirmed by X-ray photoelectron spectroscopy. Open circuit potential variation with time also indicated the chemical adsorption of DNA on the aluminum surface. Copyright © 2014 Elsevier B.V. All rights reserved.

  6. Surface impedance tensor in amorphous wires with helical anisotropy: Magnetic hysteresis and asymmetry

    International Nuclear Information System (INIS)

    Makhnovskiy, D. P.; Panina, L. V.; Mapps, D. J.

    2001-01-01

    This article concerns the investigation of the magnetic behavior of the surface impedance tensor cflx var-sigma in CoSiB amorphous wires having a residual torsion stress and a helical anisotropy. The full tensor cflx var-sigma involving three different components is found by measuring the S 21 parameter at a required excitation with a Hewlett-Packard network/spectrum analyzer at MHz frequencies. In general, the impedance plots versus axial magnetic field H ex exhibit a hysteresis related to that for the case of static magnetization. The diagonal components of cflx var-sigma (longitudinal var-sigma zz and circular var-sigma v ar-phi v ar-phi) show a sharp peak in a narrow field interval where the domain walls form and contribute to the ac magnetization dynamics. This peak is not seen for the off-diagonal component var-sigma zv ar-phi (var-sigma v ar-phi z ) since the existence of the domain structure suppresses it. Applying a dc bias current results in a gradual transition to a nonhysteretic asymmetrical behavior with an enhanced sensitivity. The portions of the experimental plots associated with the rotational dynamic process are in qualitative agreement with the theory based on a single-domain model. [copyright] 2001 American Institute of Physics

  7. Impedance measurement of irradiated potatoes: a method to identify radiation processing

    International Nuclear Information System (INIS)

    Mastro, N.L. del; Villavicencio, A.L.C.H.

    1992-01-01

    The potato is firmly established in many parts of the world as a major staple food. Then, radiation processing of potato is approved in many countries for sprouting inhibition and extension of shelf life in a dose range from about 0.01 to 0.15 kGy of 60 Co. The use of electrical conductance methods for the detection of Salmonella, some virus or the action of herbicides on plant has been reported and differences have been observed between instruments in respect of the magnitude of conductance change or rates of change in conductance response. A reliable technique to identify potatoes or other food products has not been established so far, though several methods have been reported. Electrical impedance might thus serve for characterization of unirradiated and irradiated tissues and cells. In this work, potato tubers from an European variety, named Bintje, grown in Sao Paulo State were employed. Potatoes were punctured with steel electrodes and impedance measured at different frequencies (1 k Hz-100 k Hz) by passing 3-5 m A alternating current through it. The impedance ratio of 50 k Hz/5 k Hz calculated from ten replicate samples decreases with the increment of the dose when doses of O 0.75 and 0.15 kGy from a Gamma Cell 220 were utilized. The impedance measurement were slightly affected by the place of puncture. (author)

  8. Method and device for bio-impedance measurement with hard-tissue applications.

    Science.gov (United States)

    Guimerà, A; Calderón, E; Los, P; Christie, A M

    2008-06-01

    Bio-impedance measurements can be used to detect and monitor several properties of living hard-tissues, some of which include bone mineral density, bone fracture healing or dental caries detection. In this paper a simple method and hardware architecture for hard tissue bio-impedance measurement is proposed. The key design aspects of such architecture are discussed and a commercial handheld ac impedance device is presented that is fully certified to international medical standards. It includes a 4-channel multiplexer and is capable of measuring impedances from 10 kOmega to 10 MOmega across a frequency range of 100 Hz to 100 kHz with a maximum error of 5%. The device incorporates several user interface methods and a Bluetooth link for bi-directional wireless data transfer. Low-power design techniques have been implemented, ensuring the device exceeds 8 h of continuous use. Finally, bench test results using dummy cells consisting of parallel connected resistors and capacitors, from 10 kOmega to 10 MOmega and from 20 pF to 100 pF, are discussed.

  9. Method and device for bio-impedance measurement with hard-tissue applications

    International Nuclear Information System (INIS)

    Guimerà, A; Calderón, E; Los, P; Christie, A M

    2008-01-01

    Bio-impedance measurements can be used to detect and monitor several properties of living hard-tissues, some of which include bone mineral density, bone fracture healing or dental caries detection. In this paper a simple method and hardware architecture for hard tissue bio-impedance measurement is proposed. The key design aspects of such architecture are discussed and a commercial handheld ac impedance device is presented that is fully certified to international medical standards. It includes a 4-channel multiplexer and is capable of measuring impedances from 10 kΩ to 10 MΩ across a frequency range of 100 Hz to 100 kHz with a maximum error of 5%. The device incorporates several user interface methods and a Bluetooth link for bi-directional wireless data transfer. Low-power design techniques have been implemented, ensuring the device exceeds 8 h of continuous use. Finally, bench test results using dummy cells consisting of parallel connected resistors and capacitors, from 10 kΩ to 10 MΩ and from 20 pF to 100 pF, are discussed

  10. Experimental test of proximity effect theories by surface impedance measurements on the Pb-Sn system

    International Nuclear Information System (INIS)

    Hook, J.R.; Battilana, J.A.

    1976-01-01

    The proximity effect in the Pb-Sn system in zero magnetic field has been studied by measuring the surface impedance at 3 GHz of a thin film of tin evaporated on to a bulk lead substrate. The results are compared with the predictions of theories of the proximity effect. It is found that good agreement can be obtained by using a theory due to Hook and Waldram of the spatial variation of the superconducting order parameter Δ inside each metal together with suitable boundary conditions on Δ at the interface between the metals. The required boundary conditions are a generalization to the case of non-zero electron reflection at the interface of the boundary conditions given by Zaitsev for the Ginsburg-Landau equation. (author)

  11. Surface impedance formalism for a metallic beam pipe with small corrugations

    Directory of Open Access Journals (Sweden)

    G. Stupakov

    2012-12-01

    Full Text Available A metallic pipe with wall corrugations is of special interest in light of recent proposals to use such a pipe for the generation of terahertz radiation and for energy dechirping of electron bunches in free electron lasers. In this paper we calculate the surface impedance of a corrugated metal wall and show that it can be reduced to that of a thin layer with dielectric constant ϵ and magnetic permeability μ. We develop a technique for the calculation of these constants, given the geometrical parameters of the corrugations. We then calculate, for the specific case of a round metallic pipe with small corrugations, the frequency and strength of the resonant mode excited by a relativistic beam. Our analytical results are compared with numerical simulations, and are shown to agree well. They are also shown to be more accurate when compared to the earlier used analytical model.

  12. RF Surface Impedance Characterization of Potential New Materials for SRF-based Accelerators

    International Nuclear Information System (INIS)

    In the development of new superconducting materials for possible use in SRF-based accelerators, it is useful to work with small candidate samples rather than complete resonant cavities. The recently commissioned Jefferson Lab RF Surface Impedance Characterization (SIC) system can presently characterize the central region of 50 mm diameter disk samples of various materials from 2 to 40 K exposed to RF magnetic fields up to 14 mT at 7.4 GHz. We report the recent measurement results of bulk Nb, thin film Nb on Cu and sapphire substrates, Nb 3 Sn sample, and thin film MgB 2 on sapphire substrate provided by colleagues at JLab and Temple University

  13. Voltammetric and impedance behaviours of surface-treated nano-crystalline diamond film electrodes

    Directory of Open Access Journals (Sweden)

    F. B. Liu

    2015-04-01

    Full Text Available The electrochemical performances of hydrogen- and oxygen-terminated nano-crystalline diamond film electrodes were investigated by cyclic voltammetry and AC impedance spectroscopy. In addition, the surface morphologies, phase structures, and chemical states of the two diamond films were analysed by scanning probe microscopy, Raman spectroscopy, and X-ray photoelectron spectroscopy, respectively. The results indicated that the potential window is narrower for the hydrogen-terminated nano-crystalline diamond film than for the oxygen-terminated one. The diamond film resistance and capacitance of oxygen-terminated diamond film are much larger than those of the hydrogen-terminated diamond film, and the polarization resistances and double-layer capacitance corresponding to oxygen-terminated diamond film are both one order of magnitude larger than those corresponding to the hydrogen-terminated diamond film. The electrochemical behaviours of the two diamond film electrodes are discussed.

  14. Electrochemical impedance spectroscopy and Surface Studies of Steel Corrosion by Sulphate-Reducing Bacteria

    International Nuclear Information System (INIS)

    Fathul Karim Sahrani; Zaharah Ibrahim; Madzlan Aziz; Adibah Yahya

    2009-01-01

    Sulphate-reducing bacteria (SRB), implicated in microbiologically influenced corrosion were isolated from the deep subsurface at the vicinity of Pasir Gudang, Johor, Malaysia. Electrochemical impedance spectroscopic (EIS) study was carried out to determine the polarization resistance in various types of culturing solutions, with SRB1, SRB2, combination of SRB1 and SRB2 and without SRBs inoculated (control). EIS results showed that in the presence of SRB1, SRB2 and mixed culture SRB1 and SRB2, polarisation resistance values were 7170, 6370 and 7190 ohms respectively compared to that of control, 92400 ohm. X-ray analysis (EDS) of the specimens indicated high sulphur content in the medium containing SRBs. Localized corrosion was observed on the metal surface which was associated with the SRB activity. (author)

  15. Development and Demonstration of Measurement-Time Efficient Methods for Impedance Spectroscopy of Electrode and Sensor Arrays

    OpenAIRE

    Cooper, Kevin R.; Smith, Matthew; Johnson, Derek

    2008-01-01

    The development of impedance-based array devices is hindered by a lack of robust platforms and methods upon which to evaluate and interrogate sensors. One aspect to be addressed is the development of measurement-time efficient techniques for broadband impedance spectroscopy of large electrode arrays. The objective of this work was to substantially increase the low frequency impedance measurement throughput capability of a large channel count array analyzer by developing true parallel measurem...

  16. A study on calculation method for mechanical impedance of air spring

    International Nuclear Information System (INIS)

    Changgeng, Shuai; Penghui, Li; Rustighi, Emiliano

    2016-01-01

    This paper proposes an approximate analytic method of obtaining the mechanical impedance of air spring. The sound pressure distribution in cylindrical air spring is calculated based on the linear air wave theory. The influences of different boundary conditions on the acoustic pressure field distribution in cylindrical air spring are analysed. A 1-order ordinary differential matrix equation for the state vector of revolutionary shells under internal pressure is derived based on the non-moment theory of elastic thin shell. Referring to the transfer matrix method, a kind of expanded homogeneous capacity high precision integration method is introduced to solve the non-homogeneous matrix differential equation. Combined the solved stress field of shell with the calculated sound pressure field in air spring under the displacement harmonic excitation, the approximate analytical expression of the input and transfer mechanical impedance for the air spring can be achieved. The numerical simulation with the Comsol Multiphysics software verifies the correctness of theoretical analysis result. (paper)

  17. Voltage Based Detection Method for High Impedance Fault in a Distribution System

    Science.gov (United States)

    Thomas, Mini Shaji; Bhaskar, Namrata; Prakash, Anupama

    2016-09-01

    High-impedance faults (HIFs) on distribution feeders cannot be detected by conventional protection schemes, as HIFs are characterized by their low fault current level and waveform distortion due to the nonlinearity of the ground return path. This paper proposes a method to identify the HIFs in distribution system and isolate the faulty section, to reduce downtime. This method is based on voltage measurements along the distribution feeder and utilizes the sequence components of the voltages. Three models of high impedance faults have been considered and source side and load side breaking of the conductor have been studied in this work to capture a wide range of scenarios. The effect of neutral grounding of the source side transformer is also accounted in this study. The results show that the algorithm detects the HIFs accurately and rapidly. Thus, the faulty section can be isolated and service can be restored to the rest of the consumers.

  18. Determination of abdominal fat thickness using dual electrode separation in the focused impedance method (FIM)

    International Nuclear Information System (INIS)

    Surovy, Nusrat Jahan; Billah, Md Masum; Haowlader, Salahuddin; Al-Quaderi, Golam Dastegir; Rabbani, K Siddique-e

    2012-01-01

    Subcutaneous fat layer thickness in the abdomen is a risk indicator of several diseases and disorders like diabetes and heart problems and could be used as a measure of fitness. Skinfold measurement using mechanical calipers is simple but prone to error. Ultrasound scanning techniques are yet to be established as accurate methods for this purpose. magnetic resonance imaging (MRI) and computed tomography (CT) scans can provide the answer but are expensive and not available widely. Some initiatives were made earlier to use electrical impedance to this end, but had inadequacies. In the first part of this paper, a 4-electrode focused impedance method (FIM) with different electrode separations has been studied for its possible use in the determination of abdominal fat thickness in a localized region. For this, a saline phantom was designed to provide different electrode separations and different layers of resistive materials adjacent to the electrodes. The background saline simulated the internal organs having low impedance while the resistive layers simulated the subcutaneous fat. The plot of the measured impedance with electrode separation had different ‘slopes’ for different thicknesses of resistive layers, which offered a method to obtain an unknown thickness of subcutaneous fat layer. In the second part, measurements were performed on seven human subjects using two electrode separations. Fat layer thickness was measured using mechanical calipers. A plot of the above ‘slope’ against fat thickness could be fitted using a straight line with an R 2 of 0.93. Then this could be used as a calibration curve for the determination of unknown fat thickness. Further work using more accurate CT and MRI measurements would give a better calibration curve for practical use of this non-invasive and low-cost technique in abdominal fat thickness measurement. (paper)

  19. A new lithium-ion battery internal temperature on-line estimate method based on electrochemical impedance spectroscopy measurement

    Science.gov (United States)

    Zhu, J. G.; Sun, Z. C.; Wei, X. Z.; Dai, H. F.

    2015-01-01

    The power battery thermal management problem in EV (electric vehicle) and HEV (hybrid electric vehicle) has been widely discussed, and EIS (electrochemical impedance spectroscopy) is an effective experimental method to test and estimate the status of the battery. Firstly, an electrochemical-based impedance matrix analysis for lithium-ion battery is developed to describe the impedance response of electrochemical impedance spectroscopy. Then a method, based on electrochemical impedance spectroscopy measurement, has been proposed to estimate the internal temperature of power lithium-ion battery by analyzing the phase shift and magnitude of impedance at different ambient temperatures. Respectively, the SoC (state of charge) and temperature have different effects on the impedance characteristics of battery at various frequency ranges in the electrochemical impedance spectroscopy experimental study. Also the impedance spectrum affected by SoH (state of health) is discussed in the paper preliminary. Therefore, the excitation frequency selected to estimate the inner temperature is in the frequency range which is significantly influenced by temperature without the SoC and SoH. The intrinsic relationship between the phase shift and temperature is established under the chosen excitation frequency. And the magnitude of impedance related to temperature is studied in the paper. In practical applications, through obtaining the phase shift and magnitude of impedance, the inner temperature estimation could be achieved. Then the verification experiments are conduced to validate the estimate method. Finally, an estimate strategy and an on-line estimation system implementation scheme utilizing battery management system are presented to describe the engineering value.

  20. Accuracy of acoustic ear canal impedances: finite element simulation of measurement methods using a coupling tube.

    Science.gov (United States)

    Schmidt, Sebastian; Hudde, Herbert

    2009-06-01

    Acoustic impedances measured at the entrance of the ear canal provide information on both the ear canal geometry and the terminating impedance at the eardrum, in principle. However, practical experience reveals that measured results in the audio frequency range up to 20 kHz are frequently not very accurate. Measurement methods successfully tested in artificial tubes with varying area functions often fail when applied to real ear canals. The origin of these errors is investigated in this paper. To avoid mixing of systematical and other errors, no real measurements are performed. Instead finite element simulations focusing on the coupling between a connecting tube and the ear canal are regarded without simulating a particular measuring method in detail. It turns out that realistic coupling between the connecting tube and the ear canal causes characteristic shifts of the frequencies of measured pressure minima and maxima. The errors in minima mainly depend on the extent of the area discontinuity arising at the interface; the errors in maxima are determined by the alignment of the tube with respect to the ear canal. In summary, impedance measurements using coupling tubes appear questionable beyond 3 kHz.

  1. Measurement of the specific surface area of loose copper deposit by electrochemical methods

    Directory of Open Access Journals (Sweden)

    E. A. Dolmatova

    2016-07-01

    Full Text Available In the work the surface area of the electrode with dispersed copper deposit obtained within 30 seconds was evaluated by techniques of chronopotentiometry (CPM and impedance spectroscopy. In method CPM the electrode surface available for measurement depends on the value of the polarizing current. At high currents during the transition time there is a change of surface relief that can not determine the full surface of loose deposit. The electrochemical impedance method is devoid of this shortcoming since the measurements are carried out in indifferent electrolyte in the absence of current. The area measured by the impedance is tens of times higher than the value obtained by chronopotentiometry. It is found that from a solution containing sulfuric acid the deposits form with a high specific surface area. Based on these data it was concluded that the method of impedance spectroscopy can be used to measure in situ the surface area of the dispersed copper deposits.

  2. Unraveling surface and bulk trap states in lead halide perovskite solar cells using impedance spectroscopy

    Science.gov (United States)

    Han, Changfeng; Wang, Kai; Zhu, Xixiang; Yu, Haomiao; Sun, Xiaojuan; Yang, Qin; Hu, Bin

    2018-03-01

    Organic-inorganic hybrid perovskites (OIHPs) have been widely recognized as an excellent candidate for next-generation photovoltaic materials because of their highly efficient power conversion. Acquiring a complete understanding of trap states and dielectric properties in OIHP-based solar cells at the steady state is highly desirable in order to further explore and improve their optoelectronic functionalities and properties. We report CH3NH3PbI3-x Cl x -based planar solar cells with a power conversion efficiency (PCE) of 15.8%. The illumination intensity dependence of the current density-voltage (J-V) revealed the presence of trap-assisted recombination at low fluences. Non-destructive ac impedance spectroscopy (ac-IS) was applied to characterize the device at the steady state. The capacitance-voltage (C-V) spectra exhibited some distinct variations at a wide range of ac modulation frequencies with and without photo-excitations. Since the frequency-dependent chemical capacitance ({{C}μ }) is concerned with the surface and bulk related density of states (DOS) in CH3NH3PbI3-x Cl x , we verified this by fitting the corresponding DOS by a Gaussian distribution function. We ascertained that the electronic sub-gap trap states present in the solution processed CH3NH3PbI3-x Cl x and their distribution differs from the surface to the bulk. In fact, we demonstrated that both surfaces that were adjacent to the electron and hole transport layers featured analogous DOS. Despite this, photo- and bias-induced giant dielectric responses (i.e. both real and imaginary parts) were detected. A remarkable reduction of {{C}μ } at higher frequencies (i.e. more than 100 kHz) was ascribed to the effect of dielectric loss in CH3NH3PbI3-x Cl x .

  3. Tongue electrical impedance in amyotrophic lateral sclerosis modeled using the finite element method.

    Science.gov (United States)

    Pacheck, Adam; Mijailovic, Alex; Yim, Sung; Li, Jia; Green, Jordan R; McIlduff, Courtney E; Rutkove, Seward B

    2016-03-01

    Electrical impedance myography (EIM) of the tongue has demonstrated alterations in patients with amyotrophic lateral sclerosis (ALS) compared to normal subjects. Whether these differences are due to reduced tongue size or diseased-associated alterations in the electrical characteristics of intrinsic tongue muscles is uncertain. We employed computer simulations using the finite element method, inputting data from healthy and ALS mouse muscle, to help answer that question, comparing our modeled results to human data. The models revealed that much of the electrical current flows superficially in the tongue and that tongue thickness only begins to have a major impact on the measured impedance when substantial atrophy is present. Modeled values paralleled the human tongue data. These findings suggest that the observed changes in tongue impedance in ALS are mainly due to alterations in the electrical properties of the tongue and are not a mere consequence of tongue volume loss. Further development of EIM for evaluation of bulbar dysfunction in ALS may provide useful information on drug efficacy and could serve as a biomarker in future clinical trials. Copyright © 2015 International Federation of Clinical Neurophysiology. Published by Elsevier Ireland Ltd. All rights reserved.

  4. Interaction of metal ions and DNA films on gold surfaces: an electrochemical impedance study.

    Science.gov (United States)

    Bin, Xiaomin; Kraatz, Heinz-Bernhard

    2009-07-01

    Electrochemical impedance spectroscopy (EIS) has been used to investigate the effects of a number of metal ions with DNA films on gold surfaces exploiting [Fe(CN)6](3-/4-) as a solution-based redox probe. Alkaline earth metal ions Mg2+, Ca2+, trivalent Al3+, La3+ and divalent transition metal ions Ni2+, Cu2+, Cd2+ and Hg2+ have been selected in this study and the results are compared with previous studies on the effects of Zn2+ on the EIS of DNA films. All experimental results were evaluated with the help of equivalent circuits which allowed the extraction of resistive and capacitive components. For all metal ions studied here, addition of the metal ions causes a decrease in the charge transfer resistance. The difference of charge transfer resistance (DeltaR(ct)) of ds-DNA films in the presence and absence of the various metal ions is different and particular to any given metal ion. In addition, we studied the EIS of ds-DNA films containing a single A-C mismatch in the presence and absence of Ca2+, Zn2+, Cd2+ and Hg2+. DeltaR(ct) values for ds-DNA films with a single A-C mismatch is smaller than those of fully matched ds-DNA films.

  5. Characteristics of surface sound pressure and absorption of a finite impedance strip for a grazing incident plane wave.

    Science.gov (United States)

    Sum, K S; Pan, J

    2007-07-01

    Distributions of sound pressure and intensity on the surface of a flat impedance strip flush-mounted on a rigid baffle are studied for a grazing incident plane wave. The distributions are obtained by superimposing the unperturbed wave (the specularly reflected wave as if the strip is rigid plus the incident wave) with the radiated wave from the surface vibration of the strip excited by the unperturbed pressure. The radiated pressure interferes with the unperturbed pressure and distorts the propagating plane wave. When the plane wave propagates in the baffle-strip-baffle direction, it encounters discontinuities in acoustical impedance at the baffle-strip and strip-baffle interfaces. The radiated pressure is highest around the baffle-strip interface, but decreases toward the strip-baffle interface where the plane wave distortion reduces accordingly. As the unperturbed and radiated waves have different magnitudes and superimpose out of phase, the surface pressure and intensity increase across the strip in the plane wave propagation direction. Therefore, the surface absorption of the strip is nonzero and nonuniform. This paper provides an understanding of the surface pressure and intensity behaviors of a finite impedance strip for a grazing incident plane wave, and of how the distributed intensity determines the sound absorption coefficient of the strip.

  6. Resistive wall impedance of the LHC beam screen without slots calculated by boundary element method

    CERN Document Server

    Tsutsui, H

    2002-01-01

    In order to calculate the resistive wall impedance of the LHC beam screen without slots, the Boundary Element Method (BEM) is used. The result at 1 GHz is Re(ZL/L) = 6.689×10−3 Ω/m, Re(Zx/L) = 1.251 Ω/m2, Re(Zy/L) = 1.776 Ω/m2, andRe(2Z0,2 cos/kL) = −0.525 Ω/m2, assuming σ = 5.8 × 109 /Ωm.

  7. Electrothermal impedance spectroscopy as a cost efficient method for determining thermal parameters of lithium ion batteries

    DEFF Research Database (Denmark)

    Swierczynski, Maciej Jozef; Stroe, Daniel Loan; Stanciu, Tiberiu

    2017-01-01

    , thermal modelling of lithium-ion battery cells and battery packs is gaining importance. Equivalent thermal circuits' models have proven to be relatively accurate with a low computational burden for the price of low spatial resolution; nevertheless, they usually require expensive equipment...... for thermal characterization of batteries. The scientific intention of this paper is to collect and systematize the state of knowledge about electrothermal impedance spectroscopy and present different measurement methods on the example of a high-power lithium battery cell and finally to discuss the prospect....

  8. Improving the Stability and Accuracy of Power Hardware-in-the-Loop Simulation Using Virtual Impedance Method

    Directory of Open Access Journals (Sweden)

    Xiaoming Zha

    2016-11-01

    Full Text Available Power hardware-in-the-loop (PHIL systems are advanced, real-time platforms for combined software and hardware testing. Two paramount issues in PHIL simulations are the closed-loop stability and simulation accuracy. This paper presents a virtual impedance (VI method for PHIL simulations that improves the simulation’s stability and accuracy. Through the establishment of an impedance model for a PHIL simulation circuit, which is composed of a voltage-source converter and a simple network, the stability and accuracy of the PHIL system are analyzed. Then, the proposed VI method is implemented in a digital real-time simulator and used to correct the combined impedance in the impedance model, achieving higher stability and accuracy of the results. The validity of the VI method is verified through the PHIL simulation of two typical PHIL examples.

  9. Soil-structure interaction - a general method to calculate soil impedance

    International Nuclear Information System (INIS)

    Farvacque, M.; Gantenbein, F.

    1983-01-01

    A correct analysis of the seismic response of nuclear power plant buildings needs to take into account the soil structure interaction. The most classical and simple method consists in characterizing the soil by a stiffness and a damping function for each component of the translation and rotation of the foundation. In a more exact way an impedance function of the frequency may be introduced. Literature provides data to estimate these coefficients for simple soil and foundation configurations and using linear hypothesis. This paper presents a general method to calculate soil impedances which is based on the computation of the impulsive response of the soil using an axisymmetric 2D finite element Code (INCA). The Fourier transform of this response is made in the time interval before the return of the reflected waves on the boundaries of the F.E. domain. This procedure which limits the perturbing effects of the reflections is improved by introducing absorbing boundary elements. A parametric study for homogeneous and layered soils has been carried out using this method. (orig.)

  10. Evaluation of segmental body composition by gender in obese children using bioelectric impedance analysis method

    Directory of Open Access Journals (Sweden)

    İhsan Çetin

    2015-12-01

    Full Text Available Objective: In this study, it was aimed to evaluate segmental body composition of children diagnosed with obesity using bioelectrical impedance analysis method in terms of different gender. Methods: 48 children, aged between 6-15 years, 21 of whom were boys while 27 were girls, diagnosed with obesity in Erciyes University Medical Faculty Department of Pediatric Endocrinology Outpatient Clinic were included in our study from April to June in 2011. Those over 95 percentile were defined as obese group. Tanita BC-418 device was used to analyze the body composition. Results: As a result of bioelectrical impedance analysis, lean body mass and body muscle mass were found to be statistically significantly higher in obese girls compared with obese boys. However, lean mass of the left arm, left leg muscle mass and basal metabolic rate were found to be statistically significantly lower in obese girls compared with obese boys. Conclusion: Consequently, it may be suggest that segmental analysis, where gender differences are taken into account, can provide proper exercise pattern and healthy way of weight loss in children for prevention of obesity and associated diseases including obesity and type 2 diabetics and cardiovascular diseases.

  11. Hybrid islanding detection method by using grid impedance estimation in parallel-inverters-based microgrid

    DEFF Research Database (Denmark)

    Ghzaiel, Walid; Jebali-Ben Ghorbal, Manel; Slama-Belkhodja, Ilhem

    2014-01-01

    This paper presents a hybrid islanding detection algorithm integrated on the distributed generation unit more close to the point of common coupling of a Microgrid based on parallel inverters where one of them is responsible to control the system. The method is based on resonance excitation under...... parameters, both resistive and inductive parts, from the injected resonance frequency determination. Finally, the inverter will disconnect the microgrid from the faulty grid and reconnect the parallel inverter system to the controllable distributed system in order to ensure high power quality. This paper...... shows that grid impedance variation detection estimation can be an efficient method for islanding detection in microgrid systems. Theoretical analysis and simulation results are presented to validate the proposed method....

  12. New method of silicon photovoltaic panel fault detection using impedance spectroscopy

    DEFF Research Database (Denmark)

    Symonowicz, Joanna Karolina; Riedel, Nicholas; Thorsteinsson, Sune

    2017-01-01

    The aim of our project is to develop a new method for photovoltaic (PV) panel fault detection based on analysing its impedance spectra (IS). Although this technique was successful in assessing the state of degradation of fuel cells and batteries [1, 2], it has never been applied to PV cells...... on a wide scale. In this paper, we show that, unlike current-voltage (I-V) tests, the IS method is capable of early detection of changes in PV panel parameters due to microcracks and potential-induced degradation (PID). Although our measurements are only successful under dark conditions, the results...... are similar for both laboratory environment and for outdoor tests in various weather conditions. A fully developed IS technique, accounting for all kinds of most common PV panel degradation types, would surpass the existing PV fault detection methods then it comes to cost and accuracy [3,4]....

  13. Shear-wave seismic reflection imaging and impedance inversion for a near-surface point-bar

    Science.gov (United States)

    Benton, N. W.; Morrison, M.; Lorenzo, J. M.; Odom, B.; Clift, P. D.; Olson, E.; Gostic, A.

    2017-12-01

    Imaging and inversion of SH-waves are useful to detect, map, and quantitatively characterize near-surface point-bar strata. We conduct a horizontally-polarized (SH) reflection survey across and along a near-surface (9 - 40 m) downstream point-bar. We invert for shear-impedance profiles and correlate our interpretation to electrical conductivity (EC) logs in adjacent wells to study the internal architecture and lithology of point-bars. We acquire two common-midpoint (CMP) SH-wave seismic reflection lines at False River (Point Coupee Parish, Louisiana). A 104 m long seismic line (L1) is oriented orthogonal (NW - SE) to point-bar strike. A second line (L2) is 48 m long and set parallel to point-bar strike (NE - SW). Two EC wells lie 33 m apart. Both wells are parallel with respect to the L1 survey and offset from it by 15 m. EC log measurements range from 1 - 25 m depth. Interference of Love-waves prevents seismic imaging at depths less than 9 m. The L1 and L2 data sets are inverted for shear-impedance using a model-based band-limited impedance (BLIMP) algorithm that incorporates a low-frequency velocity model. This model is also used for the depthing processing. The L1 cross-section shows coherent dipping reflection events ( 4 - 7º) from 0.15 - 0.35 s (10 - 40 m). The corresponding shear-impedance profile also reveals coherent and dipping impedance contrasts that grow in magnitude with increasing depth. The L2 cross-section shows comparatively less dip ( 1º) as well as sharper and shallower continuity of reflection events (0.1 - 0.28 s TWT or 9 - 25 m). Depth-converted (TVD) seismic amplitudes and impedance values correlate to near-surface point-bar geology via superposition of log data. The first well (W5) shows distinct EC local maxima (+50 - 70 mS/m) at 14.5 and 15.5 m depth that correlate well with the seismic amplitudes and impedance values from both L1 and L2 data sets. The second well (W7) shows comparatively lower local maxima (+40 - 60 mS/m) but at greater

  14. 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.

  15. Body composition measures of obese adolescents by the deuterium oxide dilution method and by bioelectrical impedance.

    Science.gov (United States)

    Resende, C M M; Camelo Júnior, J S; Vieira, M N C M; Ferriolli, E; Pfrimer, K; Perdoná, G S C; Monteiro, J P

    2011-11-01

    The objectives of the present study were to describe and compare the body composition variables determined by bioelectrical impedance (BIA) and the deuterium dilution method (DDM), to identify possible correlations and agreement between the two methods, and to construct a linear regression model including anthropometric measures. Obese adolescents were evaluated by anthropometric measures, and body composition was assessed by BIA and DDM. Forty obese adolescents were included in the study. Comparison of the mean values for the following variables: fat body mass (FM; kg), fat-free mass (FFM; kg), and total body water (TBW; %) determined by DDM and by BIA revealed significant differences. BIA overestimated FFM and TBW and underestimated FM. When compared with data provided by DDM, the BIA data presented a significant correlation with FFM (r = 0.89; P obese adolescents determined by DDM can be predicted by using the measures provided by BIA through a regression equation.

  16. Electrochemical impedance spectroscopy of polycrystalline boron doped diamond layers with hydrogen and oxygen terminated surface

    Czech Academy of Sciences Publication Activity Database

    Vlčková Živcová, Zuzana; Petrák, Václav; Frank, Otakar; Kavan, Ladislav

    2015-01-01

    Roč. 55, MAY 2015 (2015), s. 70-76 ISSN 0925-9635 R&D Projects: GA ČR GA13-31783S Institutional support: RVO:61388955 ; RVO:68378271 Keywords : Boron doped diamond * Electrochemical impedance spectroscopy * Aqueous electrolyte solution Subject RIV: CG - Electrochemistry Impact factor: 2.125, year: 2015

  17. Evaluation of different methods for measuring the impedance of Lithium-ion batteries during ageing

    DEFF Research Database (Denmark)

    Stroe, Daniel Loan; Swierczynski, Maciej Jozef; Stroe, Ana-Irina

    2015-01-01

    The impedance represents one of the most important performance parameters of the Lithium-ion batteries since it used for power capability calculations, battery pack and system design, cooling system design and also for state-of-health estimation. In the literature, different approaches are presen......The impedance represents one of the most important performance parameters of the Lithium-ion batteries since it used for power capability calculations, battery pack and system design, cooling system design and also for state-of-health estimation. In the literature, different approaches...... are presented for measuring the impedance of Lithium-ion batteries and electrochemical impedance spectroscopy and dc current pulses are the most used ones; each of these approaches has its own advantages and drawbacks. The goal of this paper is to investigate which of the most encountered impedance measurement...... approaches is the most suitable for measuring the impedance of Lithium-ion batteries during ageing....

  18. The Surface Adsorption of Hydride Ions and Hydrogen Atoms on Zn Studied by Electrochemical Impedance Spectroscopy with a Non-Equilibrium Thermodynamic Formulation

    Science.gov (United States)

    Nakajima, Hironori; Nohira, Toshiyuki; Ito, Yasuhiko; Kjelstrup, Signe; Bedeaux, Dick

    2006-09-01

    We show that non-equilibrium thermodynamics theory for surfaces combined with electrochemical impedance spectroscopy can be used to derive the excess surface concentrations of reactants and products of an electrochemical reaction at an electrode. We predict the equivalent circuit for a postulated reaction using this theory, and derive expressions for the excess surface concentrations. The method is illustrated with experimental data for the following hydride reaction to hydrogen at a Zn anode in a molten eutectic mixture of LiCl and KCl at 673 K: The results support a two-step mechanism for hydrogen evolution via the hydrogen atom. We calculate the excess surface concentrations of the hydride ions and the hydrogen atoms at the metal surface, and find that the hydride ions cover a fraction of the surface while the hydrogen atoms are present in large excess. The excess surface concentration of the hydride ions varies largely with the polarized state of the surface, and so does its mean activity coefficient at the surface. The results contribute to a better understanding of the system in question. The method is general and is expected to give similar information for other electrodes.

  19. Density, ultrasound velocity, acoustic impedance, reflection and absorption coefficient determination of liquids via multiple reflection method.

    Science.gov (United States)

    Hoche, S; Hussein, M A; Becker, T

    2015-03-01

    The accuracy of density, reflection coefficient, and acoustic impedance determination via multiple reflection method was validated experimentally. The ternary system water-maltose-ethanol was used to execute a systematic, temperature dependent study over a wide range of densities and viscosities aiming an application as inline sensor in beverage industries. The validation results of the presented method and setup show root mean square errors of: 1.201E-3 g cm(-3) (±0.12%) density, 0.515E-3 (0.15%) reflection coefficient and 1.851E+3 kg s(-1) m(-2) (0.12%) specific acoustic impedance. The results of the diffraction corrected absorption showed an average standard deviation of only 0.12%. It was found that the absorption change shows a good correlation to concentration variations and may be useful for laboratory analysis of sufficiently pure liquids. The main part of the observed errors can be explained by the observed noise, temperature variation and the low signal resolution of 50 MHz. In particular, the poor signal-to-noise ratio of the second reflector echo was found to be a main accuracy limitation. Concerning the investigation of liquids the unstable properties of the reference material PMMA, due to hygroscopicity, were identified to be an additional, unpredictable source of uncertainty. While dimensional changes can be considered by adequate methodology, the impact of the time and temperature dependent water absorption on relevant reference properties like the buffer's sound velocity and density could not be considered and may explain part of the observed deviations. Copyright © 2014 Elsevier B.V. All rights reserved.

  20. A shape-based quality evaluation and reconstruction method for electrical impedance tomography

    International Nuclear Information System (INIS)

    Antink, Christoph Hoog; Pikkemaat, Robert; Leonhardt, Steffen; Malmivuo, Jaakko

    2015-01-01

    Linear methods of reconstruction play an important role in medical electrical impedance tomography (EIT) and there is a wide variety of algorithms based on several assumptions. With the Graz consensus reconstruction algorithm for EIT (GREIT), a novel linear reconstruction algorithm as well as a standardized framework for evaluating and comparing methods of reconstruction were introduced that found widespread acceptance in the community.In this paper, we propose a two-sided extension of this concept by first introducing a novel method of evaluation. Instead of being based on point-shaped resistivity distributions, we use 2759 pairs of real lung shapes for evaluation that were automatically segmented from human CT data. Necessarily, the figures of merit defined in GREIT were adjusted. Second, a linear method of reconstruction that uses orthonormal eigenimages as training data and a tunable desired point spread function are proposed.Using our novel method of evaluation, this approach is compared to the classical point-shaped approach. Results show that most figures of merit improve with the use of eigenimages as training data. Moreover, the possibility of tuning the reconstruction by modifying the desired point spread function is shown. Finally, the reconstruction of real EIT data shows that higher contrasts and fewer artifacts can be achieved in ventilation- and perfusion-related images. (paper)

  1. Au nanoparticle-modified DNA sensor based on simultaneous electrochemical impedance spectroscopy and localized surface plasmon resonance.

    Science.gov (United States)

    Cheng, Xin R; Hau, Ben Y H; Endo, Tatsuro; Kerman, Kagan

    2014-03-15

    Electrochemical impedance spectroscopy (EIS) and localized surface plasmon resonance (LSPR) were performed on the same Au nanoparticle (AuNP)-modified indium tin oxide (ITO) coated glass surfaces. Cyclic voltammetry was applied to electrodeposit AuNPs on ITO surface directly. The surface plasmon band characterization of AuNPs was initially studied by controlling the electrodeposition conditions. It was found that the size of AuNP clusters was significantly affected by the applied potential and KCl concentration in solution. The dual-detection platform was applied to detect DNA hybridization related to a specific point mutation in apolipoprotein E gene (ApoE), which was related to the progression of Alzheimer's disease. The preliminary results facilitate the development of a versatile biosensor that can be easily miniaturized and integrated into a high-throughput diagnostic device. © 2013 Elsevier B.V. All rights reserved.

  2. Grid impedance estimation based hybrid islanding detection method for AC microgrids

    DEFF Research Database (Denmark)

    Ghzaiel, Walid; Jebali-Ben Ghorbal, Manel; Slama-Belkhodja, Ilhem

    2017-01-01

    parameters. Grid impedance variations detection algorithm is based on grid current measurements temporal redundancies with fast current acquisition period. Once the grid impedance variation is detected, the excitation resonance is performed by injecting a resonance frequency in only one inverter control...

  3. A Comparison of Impedance-Based Fault Location Methods for Power Underground Distribution Systems

    Directory of Open Access Journals (Sweden)

    Enrique Personal

    2016-12-01

    Full Text Available In the last few decades, the Smart Grid paradigm presence has increased within power systems. These new kinds of networks demand new Operations and Planning approaches, following improvements in the quality of service. In this sense, the role of the Distribution Management System, through its Outage Management System, is essential to guarantee the network reliability. This system is responsible for minimizing the consequences arising from a fault event (or network failure. Obviously, knowing where the fault appears is critical for a good reaction of this system. Therefore, several fault location techniques have been proposed. However, most of them provide individual results, associated with specific testbeds, which make the comparison between them difficult. Due to this, a review of fault location methods has been done in this paper, analyzing them for their use on underground distribution lines. Specifically, this study is focused on an impedance-based method because their requirements are in line with the typical instrumentation deployed in distribution networks. This work is completed with an exhaustive analysis of these methods over a PSCADTM X4 implementation of the standard IEEE Node Test Feeder, which truly allows us to consistently compare the results of these location methods and to determine the advantages and drawbacks of each of them.

  4. Basic study of a diagnostic modality employing a new electrical impedance tomography (EIT) method for noninvasive measurement in localized tissues.

    Science.gov (United States)

    Okazaki, Kenji; Tangoku, Akira; Morimoto, Tadaoki; Kotani, Ryosuke; Hattori, Keigo; Yasuno, Emiko; Akutagawa, Masatake; Kinouchi, Yohsuke

    2010-08-01

    The objective of this study is to develop a device for noninvasive local tissue electrical impedance tomography (EIT) using divided electrodes with guard electrodes and to validate its effectiveness using bioequivalent phantoms. For this purpose, we prepared a measurement device and bioequivalent phantoms, measured the electrical characteristics of the phantoms, and validated the method using the phantoms. Monolayer phantoms mimicking the brain and muscle and bilayer phantoms consisting of muscle and brain layers were prepared. The relative differences between the measured electrical conductivities of the monolayer brain and muscle phantoms and the true values determined by the 4-electrode method were both less than 10%. The relative differences between the measured and true values in the bilayer phantoms were less than 20% in both layers. The biological impedance measurement device that we developed was confirmed to be effective for impedance measurement in bilayer phantoms with different electrical impedances. To develop a device for the early diagnosis of breast diseases, the development of a multi-layer phantom and demonstration of the effectiveness of the device for its examination are necessary. If the device that we developed makes impedance measurement in breast tumors possible, it may be used as a new diagnostic modality for breast diseases.

  5. Assessment of dental implant stability by means of the electromechanical impedance method

    International Nuclear Information System (INIS)

    Boemio, Giovanni; Rizzo, Piervincenzo; Nardo, Luigi De

    2011-01-01

    Implant stability is a prerequisite for functional recovery in load-bearing prostheses. Robust, reliable and noninvasive methods to assess the bone interface of dental and orthopedic implants are increasingly demanded for clinical diagnosis and direct prognosis. In this paper, a study of the feasibility of a noninvasive method based on electromechanical impedance (EMI) to assess dental prostheses stability is presented. Two different dental screws were entrenched in polyurethane foams (Sawbones ® ) and immersed in a solution of nitric acid to allow material degradation, inversely simulating a bone healing process. This process was monitored by bonding a piezoceramic transducer (PZT) to the implant and measuring the admittance of the PZT over time. It was found that the PZT's conductance and the statistical features associated with its analysis were sensitive to the degradation of the foams and can be correlated to the Sawbones mechanical properties. The present study shows promising results and may pave the road towards an innovative approach for the noninvasive monitoring of implanted prostheses

  6. Use of the electro-mechanical impedance method for the assessment of dental implant stability

    Science.gov (United States)

    Rizzo, Piervincenzo; Boemio, Giovanni; de Nardo, Luigi

    2011-04-01

    The robustness and reliability of the Electro-Mechanical Impedance (EMI) method to assess dental prostheses stability is presented. The study aim at addressing an increasing need in the biomedical area where robust, reliable, and non-invasive methods to assess the bone-interface of dental and orthopedic implants are increasingly demanded for clinical diagnosis and direct prognosis. In this study two different dental screws were entrenched in polyurethane foams and immersed in a solution of nitric acid to allow material degradation, inversely simulating a bone-healing process. This process was monitored by bonding a Piezoceramic Transducer (PZT) to the implant and measuring the admittance of the PZT over time. To simulate healing, a second set of experiments was conducted. It consisted of placing four dental screws inside a joint compound specimen and observing the setting of the fresh compound allocated in the alveolus containing each implant. In all cases it was found that the PZT's conductance and the statistical features associated with the analysis of the admittance signatures were sensitive to the degradation or the setting process.

  7. Testing an Impedance Non-destructive Method to Evaluate Steel-Fiber Concrete Samples

    Science.gov (United States)

    Komarkova, Tereza; Fiala, Pavel; Steinbauer, Miloslav; Roubal, Zdenek

    2018-02-01

    Steel-fiber reinforced concrete is a composite material characterized by outstanding tensile properties and resistance to the development of cracks. The concrete, however, exhibits such characteristics only on the condition that the steel fibers in the final, hardened composite have been distributed evenly. The current methods to evaluate the distribution and concentration of a fiber composite are either destructive or exhibit a limited capability of evaluating the concentration and orientation of the fibers. In this context, the paper discusses tests related to the evaluation of the density and orientation of fibers in a composite material. Compared to the approaches used to date, the proposed technique is based on the evaluation of the electrical impedance Z in the band close to the resonance of the sensor-sample configuration. Using analytically expressed equations, we can evaluate the monitored part of the composite and its density at various depths of the tested sample. The method employs test blocks of composites, utilizing the resonance of the measuring device and the measured sample set; the desired state occurs within the interval of between f=3 kHz and 400 kHz.

  8. Impedance cardiography - Old method, new opportunities. Part II. Testing of cardiovascular response to various factors of work environment.

    Science.gov (United States)

    Siedlecka, Jadwiga; Siedlecki, Patryk; Bortkiewicz, Alicja

    2015-01-01

    Impedance cardiography seems to be a very good, although underappreciated diagnostic method. What may distinguish it from among the many research methods is the fact that it enables non-invasive monitoring of cardiac output, stroke volume and systemic vascular resistance. Holter recording of the hemodynamic parameters makes it possible to study them not only in stationary (hospital, outpatient clinic) conditions, but also during household or professional activities, e.g., during road vehicle driving. Assessment of the trends of changes in the circulatory system of the employee at work makes it possible to judge whether the type of work performed by the worker is well tolerated - whether it is not too hard or too stressful. This is important, therefore, impedance cardiography can be extensively used in occupational medicine. Provision of preventive care to workers according to current standards requires, on the one hand, the use of the latest diagnostic methods while, on the other hand, the methods must be inexpensive, because otherwise the employer would not be able or willing to pay the associated costs. Impedance cardiography meets those criteria; however, few data is available in literature worldwide on the use of this method in the research on the impact of occupational work on cardiovascular responses of the employees. This work reports the use of impedance cardiography in studies on the various aspects of work environment. This work is available in Open Access model and licensed under a CC BY-NC 3.0 PL license.

  9. Comparison of experimental and bioelectrical impedance analysis methods in calculation of dry weight in peritoneal dialysis patients

    Directory of Open Access Journals (Sweden)

    A Emami Naini

    2012-01-01

    Conclusion: The study showed that there is significant difference between the two methods. However, there was 98% direct correlation between them. It is concluded that bioelectrical impedance analysis could be a better alternative for accurate evaluation of dry weight in PD patients because it is a fast and cheap method and does not depend on examiner′s capability. Further studies based on the results of this method are recommended to consider this method as the gold standard.

  10. Continuous Microstructural Correlation of Slag/superplasticizer Cement Pastes by Heat and Impedance Methods via Fractal Analysis

    Science.gov (United States)

    Tang, S. W.; Cai, R. J.; He, Z.; Cai, X. H.; Shao, H. Y.; Li, Z. J.; Yang, H. M.; Chen, E.

    This paper presents a preliminary work to evaluate the influence of slag and superplasticizer on the early-age hydration of cement pastes by an innovative non-contact impedance measurement, heat evolution method, compressive strength and setting time tests. Besides, the cumulative pore volume obtained from modulus and phase of impedance in different hydration sections is taken to continuously correlate the cumulative heat releasing of cement pastes via the fractal analysis. Retarded phenomena and mechanism of hydration in cement pastes incorporated with slag and superplasticizer are studied, respectively. It is found that the compressive strength and setting time have a good linear relation with the slag amount in blended cement pastes.

  11. The comparison of impedance-based method of cell proliferation monitoring with commonly used metabolic-based techniques.

    Science.gov (United States)

    Vistejnova, Lucie; Dvorakova, Jana; Hasova, Martina; Muthny, Tomas; Velebny, Vladimir; Soucek, Karel; Kubala, Lukas

    2009-01-01

    Determination of cell numbers is a crucial step in studies focused on cytokinetics and cell toxicity. The impedance-based analysis employing electronic sensor array system xCELLigence System allowing label-free dynamic monitoring of relative viable adherent cell amounts was compared with the most utilized methods for relative quantification of viable cell numbers based on a determination of cellular metabolism. Colorimetric assay based on reduction of tetrazolium salt (MTT) by mitochondrial enzymes and chemiluminiscent assay based on intracellular adenosine triphosphate (ATP) determination were compared with the impedance-based system. Cell morphology was compared by microscopic evaluation. Normal human epidermal keratinocytes (NHEK) and normal human dermal fibroblasts (NHDF), together with 3T3 mouse fibroblast and HaCaT keratinocyte cell lines were employed. The progress of cell growth curves obtained by different methods during 72 hours reflected cell type and cell seeding densities. The impedance-based method was found to be applicable for the determination of the cell proliferation of 3T3 fibroblasts, HaCaT and NHDF, since the comparison of this method with ATP and MTT determinations showed a comparable results. In contrast, the proliferation of NHEK measured by the impedance-based method did not correlate with other methodological approaches. This could be accounted to the specific morphological appearance of these cells. The study shows the impedance-based detection of viable adherent cells is a valuable approach for cytokinetics and pharmacological studies. However, the specific morphological characteristics of cell lines have to be considered employing this method for determination of cell proliferation without using other reference methods.

  12. Application of the Method of Auxiliary Sources for the Analysis of Plane-Wave Scattering by Impedance Spheres

    DEFF Research Database (Denmark)

    Karamehmedovic, Mirza; Breinbjerg, Olav

    2002-01-01

    The Method of Auxiliary Sources (MAS) is applied to 3D scattering problems involving spherical impedance scatterers. The MAS results are compared with the reference spherical wave expansion (SWE) solution. It is demonstrated that good agreement is achieved between the MAS and SWE results....

  13. A Simultaneous and Continuous Excitation Method for High-Speed Electrical Impedance Tomography with Reduced Transients and Noise Sensitivity

    Directory of Open Access Journals (Sweden)

    Antoine Dupré

    2018-03-01

    Full Text Available This paper presents a concept for soft field tomographic scan of all the projections of electromagnetic waves emanating from an array of electrodes. Instead of the sequential excitation of all pairs of electrodes in the list of all projections, the new method present here consists of a single and continuous excitation. This excitation signal is the linear combination of the excitation signals in the projection set at different AC frequencies. The response to a given projection is discriminated by selecting the corresponding AC frequency component in the signal spectra of the digitally demodulated signals. The main advantage of this method is the suppression of transients after each projection, which is particularly problematic in electrical impedance tomography due to contact impedance phenomena and skin effect. The second benefit over the sequential scan method is the increased number of samples for each measurement for reduced noise sensitivity with digital demodulation. The third benefit is the increased temporal resolution in high-speed applications. The main drawback is the increased number of signal sources required (one per electrode. This paper focuses on electrical impedance tomography, based on earlier work by the authors. An experimental proof-of-concept using a simple 4-electrodes electrical impedance tomographic system is presented using simulations and laboratory data. The method presented here may be extended to other modalities (ultrasonic, microwave, optical, etc..

  14. Comparison between two methods of bioelectrical impedance analyses for accuracy in measuring abdominal visceral fat area.

    Science.gov (United States)

    Park, Kyeong Seon; Lee, Dong-Hwa; Lee, JieEun; Kim, Yoon Ji; Jung, Kyong Yeun; Kim, Kyoung Min; Kwak, Soo Heon; Choi, Sung Hee; Park, Kyong Soo; Jang, Hak Chul; Lim, Soo

    2016-03-01

    To compare the accuracy of abdominal visceral fat area (VFA) measurements between abdominal dual bioelectrical impedance analysis (BIA) and whole-body BIA referenced to computed tomography (CT) measures. Abdominal VFAs were measured in 102 individuals: 59 men and 43 women with a mean age of 44.2 ± 16.3 years (range 21 - 76), body mass index 23.9 ± 7.8 kg/m(2) (range 18 - 35) using a DUALSCAN HDS-2000 machine (dual abdominal BIA) and an InBody720 machine (whole-body BIA). The VFA values from each machine were compared with those from CT under various conditions. Mean abdominal VFAs were 116 ± 69 cm(2) by CT, 89 ± 47 cm(2) by dual abdominal BIA, and 84 ± 33 cm(2) by whole-body BIA. The former measure showed a higher correlation with the CT measure than the latter (r=0.89 vs. r=0.64, P<0.001). Both BIA methods tended to underestimate abdominal VFAs compared with CT scans when CT VFA was not small. The dual abdominal BIA had less bias than the whole-body BIA in the assessment of VFAs. The whole-body BIA was affected by subcutaneous fat area. Dual BIA was more accurate in assessing abdominal VFA than whole-body BIA. Copyright © 2016 Elsevier Inc. All rights reserved.

  15. Bioelectrical impedance with different equations versus deuterium oxide dilution method for the inference of body composition in healthy older persons.

    Science.gov (United States)

    Pfrimer, K; Moriguti, J C; Lima, N K C; Marchini, J S; Ferriolli, E

    2012-02-01

    There is no consensus regarding the accuracy of bioimpedance for the determination of body composition in older persons. This study aimed to compare the assessment of lean body mass of healthy older volunteers obtained by the deuterium dilution method (reference) with those obtained by two frequently used bioelectrical impedance formulas and one formula specifically developed for a Latin-American population. A cross-sectional study. Twenty one volunteers were studied, 12 women, with mean age 72±6.7 years. Urban community, Ribeirão Preto, Brazil. Fat free mass was determined, simultaneously, by the deuterium dilution method and bioelectrical impedance; results were compared. In bioelectrical impedance, body composition was calculated by the formulas of Deuremberg, Lukaski and Bolonchuck and Valencia et al. Lean body mass of the studied volunteers, as determined by bioelectrical impedance was 37.8±9.2 kg by the application of the Lukaski e Bolonchuk formula, 37.4±9.3 kg (Deuremberg) and 43.2±8.9 kg (Valencia et. al.). The results were significantly correlated to those obtained by the deuterium dilution method (41.6±9.3 Kg), with r=0.963, 0.932 and 0.971, respectively. Lean body mass obtained by the Valencia formula was the most accurate. In this study, lean body mass of older persons obtained by the bioelectrical impedance method showed good correlation with the values obtained by the deuterium dilution method. The formula of Valencia et al., developed for a Latin-American population, showed the best accuracy.

  16. A high-speed bioelectrical impedance spectroscopy system based on the digital auto-balancing bridge method

    International Nuclear Information System (INIS)

    Li, Nan; Xu, Hui; Zhou, Zhou; Wang, Wei; Qiao, Guofeng; Li, David D-U

    2013-01-01

    A novel bioelectrical impedance spectroscopy system based on the digital auto-balancing bridge method improved from the conventional analogue auto-balancing method is presented for bioelectrical impedance measurements. The hardware of the proposed system consists of a reference source, a null detector, a variable source, a field programmable gate array, a clock generator, a flash and a USB controller. Software implemented in the field programmable gate array includes three major blocks: clock management, peripheral control and digital signal processing. The principle and realization of the least-mean-squares-based digital auto-balancing algorithm is introduced in detail. The performances of our system were examined by comparing with a commercial impedance analyzer. The results reveal that the proposed system has high speed (less than 3.5 ms per measurement) and high accuracy in the frequency range of 1 kHz–10 MHz. Compared with the commercial instrument based on the traditional analogue auto-balancing method, our system shows advantages in measurement speed, compactness and flexibility, making it suitable for various bioelectrical impedance measurement applications. (paper)

  17. A high-speed bioelectrical impedance spectroscopy system based on the digital auto-balancing bridge method

    Science.gov (United States)

    Li, Nan; Xu, Hui; Wang, Wei; Zhou, Zhou; Qiao, Guofeng; D-U Li, David

    2013-06-01

    A novel bioelectrical impedance spectroscopy system based on the digital auto-balancing bridge method improved from the conventional analogue auto-balancing method is presented for bioelectrical impedance measurements. The hardware of the proposed system consists of a reference source, a null detector, a variable source, a field programmable gate array, a clock generator, a flash and a USB controller. Software implemented in the field programmable gate array includes three major blocks: clock management, peripheral control and digital signal processing. The principle and realization of the least-mean-squares-based digital auto-balancing algorithm is introduced in detail. The performances of our system were examined by comparing with a commercial impedance analyzer. The results reveal that the proposed system has high speed (less than 3.5 ms per measurement) and high accuracy in the frequency range of 1 kHz-10 MHz. Compared with the commercial instrument based on the traditional analogue auto-balancing method, our system shows advantages in measurement speed, compactness and flexibility, making it suitable for various bioelectrical impedance measurement applications.

  18. Phase boundary estimation in electrical impedance tomography using the Hooke and Jeeves pattern search method

    International Nuclear Information System (INIS)

    Khambampati, Anil Kumar; Kim, Kyung Youn; Ijaz, Umer Zeeshan; Lee, Jeong Seong; Kim, Sin

    2010-01-01

    In industrial processes, monitoring of heterogeneous phases is crucial to the safety and operation of the engineering structures. Particularly, the visualization of voids and air bubbles is advantageous. As a result many studies have appeared in the literature that offer varying degrees of functionality. Electrical impedance tomography (EIT) has already been proved to be a hallmark for process monitoring and offers not only the visualization of the resistivity profile for a given flow mixture but is also used for detection of phase boundaries. Iterative image reconstruction algorithms, such as the modified Newton–Raphson (mNR) method, are commonly used as inverse solvers. However, their utility is problematic in a sense that they require the initial solution in close proximity of the ground truth. Furthermore, they also rely on the gradient information of the objective function to be minimized. Therefore, in this paper, we address all these issues by employing a direct search algorithm, namely the Hooke and Jeeves pattern search method, to estimate the phase boundaries that directly minimizes the cost function and does not require the gradient information. It is assumed that the resistivity profile is known a priori and therefore the unknown information will be the size and location of the object. The boundary coefficients are parameterized using truncated Fourier series and are estimated using the relationship between the measured voltages and injected currents. Through extensive simulation and experimental result and by comparison with mNR, we show that the Hooke and Jeeves pattern search method offers a promising prospect for process monitoring

  19. Impedances of electrochemically impregnated nickel electrodes as functions of potential, KOH concentration, and impregnation method

    Science.gov (United States)

    Reid, Margaret A.

    1989-01-01

    Impedances of fifteen electrodes form each of the four U.S. manufactures were measured at 0.200 V vs. the Hg/HgO reference electrode. This corresponds to a voltage of 1.145 for a Ni/H2 cell. Measurements were also made of a representative sample of these at 0.44 V. At the higher voltage, the impedances were small and very similar, but at the lower voltage there were major differences between manufacturers. Electrodes from the same manufacturers showed only small differences. The impedances of electrodes from two manufacturers were considerably different in 26 percent KOH from those in 31 percent KOH. These preliminary results seen to correlate with the limited data from earlier life testing of cells from these manufacturers. The impedances of cells being tested for Space Station Freedom are being followed, and more impendance measurements of electrodes are being performed as functions of manufacturer, voltage, electrolyte concentration, and cycle history in hopes of finding better correlations of impedance with life.

  20. Body composition measures of obese adolescents by the deuterium oxide dilution method and by bioelectrical impedance

    Directory of Open Access Journals (Sweden)

    C.M.M. Resende

    2011-11-01

    Full Text Available The objectives of the present study were to describe and compare the body composition variables determined by bioelectrical impedance (BIA and the deuterium dilution method (DDM, to identify possible correlations and agreement between the two methods, and to construct a linear regression model including anthropometric measures. Obese adolescents were evaluated by anthropometric measures, and body composition was assessed by BIA and DDM. Forty obese adolescents were included in the study. Comparison of the mean values for the following variables: fat body mass (FM; kg, fat-free mass (FFM; kg, and total body water (TBW; % determined by DDM and by BIA revealed significant differences. BIA overestimated FFM and TBW and underestimated FM. When compared with data provided by DDM, the BIA data presented a significant correlation with FFM (r = 0.89; P < 0.001, FM (r = 0.93; P < 0.001 and TBW (r = 0.62; P < 0.001. The Bland-Altman plot showed no agreement for FFM, FM or TBW between data provided by BIA and DDM. The linear regression models proposed in our study with respect to FFM, FM, and TBW were well adjusted. FFM obtained by DDM = 0.842 x FFM obtained by BIA. FM obtained by DDM = 0.855 x FM obtained by BIA + 0.152 x weight (kg. TBW obtained by DDM = 0.813 x TBW obtained by BIA. The body composition results of obese adolescents determined by DDM can be predicted by using the measures provided by BIA through a regression equation.

  1. Corrosion Behavior of Surface-Treated Implant Ti-6Al-4V by Electrochemical Polarization and Impedance Studies

    Science.gov (United States)

    Paul, Subir; Yadav, Kasturi

    2011-04-01

    Implant materials for orthopedic and heart surgical services demand a better corrosion resistance material than the presently used titanium alloys, where protective oxide layer breaks down on a prolonged stay in aqueous physiological human body, giving rise to localized corrosion of pitting, crevice, and fretting corrosion. A few surface treatments on Ti alloy, in the form of anodization, passivation, and thermal oxidation, followed by soaking in Hank solution have been found to be very effective in bringing down the corrosion rate as well as producing high corrosion resistance surface film as reflected from electrochemical polarization, cyclic polarization, and Electrochemical Impedance Spectroscopy (EIS) studies. The XRD study revealed the presence of various types of oxides along with anatase and rutile on the surface, giving rise to high corrosion resistance film. While surface treatment of passivation and thermal oxidation could reduce the corrosion rate by 1/5th, anodization in 0.3 M phosphoric acid at 16 V versus stainless steel cathode drastically brought down the corrosion rate by less than ten times. The mechanism of corrosion behavior and formation of different surface films is better understood from the determination of EIS parameters derived from the best-fit equivalent circuit.

  2. Biomass production and control of nutrient leaching of willows using different planting methods with special emphasis on an appraisal of the electrical impedance for roots

    Energy Technology Data Exchange (ETDEWEB)

    Yang Cao

    2011-07-01

    Willow reproduction can be achieved through vertically or horizontally planted cuttings. Conventionally, plantations are established by inserting cuttings vertically into the soil. There is, however, a lack of information about the biomass production and nutrient leaching of plantations established through horizontally planted cuttings. A greenhouse experiment and a field trial were carried out to investigate whether horizontally planted Salix schwerinii cuttings have a positive effect on stem yield, root distribution and nutrient leaching in comparison with vertically planted cuttings with different planting densities. The shoots' height of horizontally planted cuttings was significantly smaller than that of vertically planted cuttings during the first two weeks after planting in the pot experiment. Thereafter, no significant effect of planting orientation on the stem biomass was observed in the two conducted experiments. In both experiments the total stem biomass increased with the planting density. It was also found that the fine root biomass and the specific root length were not affected by the planting orientation or density, while the fine root surface area and the absorbing root surface area (ARSA) were affected only by the planting density. The planting orientation did not affect the nutrient concentrations in the soil leachate, apart from SO{sub 4}-S and PO{sub 4}-P in the pot experiment. The ARSA in the pot experiment was assessed by using the earth impedance method. The applicability of this method was evaluated in a hydroponic study of willow cuttings where root and stem were measured independently. Electrical resistance had a good correlation with the contact area of the roots with the solution. However, the resistance depended strongly on the contact area of the stem with the solution, which caused a bias in the evaluation of root surface area. A similar experimental set-up with electrical impedance spectroscopy was employed to study the

  3. Diaphragm flange and method for lowering particle beam impedance at connected beam tubes of a particle accelerator

    Energy Technology Data Exchange (ETDEWEB)

    Biallas, George Herman

    2017-07-04

    A diaphragm flange for connecting the tubes in a particle accelerator while minimizing beamline impedance. The diaphragm flange includes an outer flange and a thin diaphragm integral with the outer flange. Bolt holes in the outer flange provide a means for bolting the diaphragm flange to an adjacent flange or beam tube having a mating bolt-hole pattern. The diaphragm flange includes a first surface for connection to the tube of a particle accelerator beamline and a second surface for connection to a CF flange. The second surface includes a recessed surface therein and a knife-edge on the recessed surface. The diaphragm includes a thickness that enables flexing of the integral diaphragm during assembly of beamline components. The knife-edge enables compression of a soft metal gasket to provide a leak-tight seal.

  4. An efficient impedance method for induced field evaluation based on a stabilized Bi-conjugate gradient algorithm

    International Nuclear Information System (INIS)

    Wang Hua; Liu Feng; Crozier, Stuart; Xia Ling

    2008-01-01

    This paper presents a stabilized Bi-conjugate gradient algorithm (BiCGstab) that can significantly improve the performance of the impedance method, which has been widely applied to model low-frequency field induction phenomena in voxel phantoms. The improved impedance method offers remarkable computational advantages in terms of convergence performance and memory consumption over the conventional, successive over-relaxation (SOR)-based algorithm. The scheme has been validated against other numerical/analytical solutions on a lossy, multilayered sphere phantom excited by an ideal coil loop. To demonstrate the computational performance and application capability of the developed algorithm, the induced fields inside a human phantom due to a low-frequency hyperthermia device is evaluated. The simulation results show the numerical accuracy and superior performance of the method.

  5. Oxygen surface exchange kinetics measurement by simultaneous optical transmission relaxation and impedance spectroscopy: Sr(Ti,Fe)O3-x thin film case study

    Science.gov (United States)

    Perry, Nicola H.; Kim, Jae Jin; Tuller, Harry L.

    2018-01-01

    Abstract We compare approaches to measure oxygen surface exchange kinetics, by simultaneous optical transmission relaxation (OTR) and AC-impedance spectroscopy (AC-IS), on the same mixed conducting SrTi0.65Fe0.35O3-x film. Surface exchange coefficients were evaluated as a function of oxygen activity in the film, controlled by gas partial pressure and/or DC bias applied across the ionically conducting yttria-stabilized zirconia substrate. Changes in measured light transmission through the film over time (relaxations) resulted from optical absorption changes in the film corresponding to changes in its oxygen and oxidized Fe (~Fe4+) concentrations; such relaxation profiles were successfully described by the equation for surface exchange-limited kinetics appropriate for the film geometry. The kchem values obtained by OTR were significantly lower than the AC-IS derived kchem values and kq values multiplied by the thermodynamic factor (bulk or thin film), suggesting a possible enhancement in k by the metal current collectors (Pt, Au). Long-term degradation in kchem and kq values obtained by AC-IS was also attributed to deterioration of the porous Pt current collector, while no significant degradation was observed in the optically derived kchem values. The results suggest that, while the current collector might influence measurements by AC-IS, the OTR method offers a continuous, in situ, and contact-free method to measure oxygen exchange kinetics at the native surfaces of thin films. PMID:29511391

  6. RF Surface Impedance Measurement of Polycrystalline and Large Grain Nb Disk Sample at 7.5 GHz

    Energy Technology Data Exchange (ETDEWEB)

    Xiao, Binping [BNL; Geng, Rongli [JLAB; Kelley, Michael J. [W& M, JLAB; Marhauser, Frank [JLAB; Phillips, H. Larry [JLAB; Reece, Charles E. [JLAB; Wang, Haipeng [JLAB

    2009-11-01

    A Surface Impedance Characterization (SIC) system has been proposed at the 2005 SRF workshop and recently updated as detailed at the 2009 PAC conference. Currently the SIC system can measure samples in a temperature range from 2K to 20K exposed to an RF magnetic flux density of less than 3mT. We report on new results of a BCP etched large grain Nb sample measured with this system as compared with previous results of a BCP etched polycrystalline Nb sample. The design of an upgraded SIC system for use at higher magnetic flux densities is on the way to more efficiently investigate correlations between local material characteristics and associated SRF properties, both for preparation studies of bulk niobium and also new thin film SRF developments.

  7. Surface impedance of BaFe2-xNixAs2 in the radio frequency range

    Directory of Open Access Journals (Sweden)

    A. Abbassi

    2012-08-01

    Full Text Available We report measurements of the temperature dependence of the surface impedance in superconducting BaFe1.93Ni0.07As2 crystals using the radiofrequency reflection technique in the 5

  8. An Analytical Method of Auxiliary Sources Solution for Plane Wave Scattering by Impedance Cylinders - A Reference Solution for the Numerical Method of Auxiliary Sources

    DEFF Research Database (Denmark)

    Larsen, Niels Vesterdal; Breinbjerg, Olav

    2004-01-01

    To facilitate the validation of the numerical Method of Auxiliary Sources an analytical Method of Auxiliary Sources solution is derived in this paper. The Analytical solution is valid for transverse magnetic, and electric, plane wave scattering by circular impedance Cylinders, and it is derived b...

  9. Surface-activated joining method for surveillance coupon reconstitution

    International Nuclear Information System (INIS)

    Kaihara, Shoichiro; Nakamura, Terumi

    1993-01-01

    As nuclear power plants approach the end of their license periods and license renewal is contemplated, there is an increasing need to expand the data base of mechanical properties obtainable from archival surveillance specimens. A new joining method for reconstituting broken Charpy specimens is being developed, the objective being to retain the original properties of the material in the process. The new method is called surface-activated joining (SAJ). It is designed to obtain a good junction without applying extra heating and deformation. In particular, the purpose of SAJ is to minimize the width of the heat-affected zone (HAZ) and to decrease the maximum temperature experienced by the specimen during reconsolidation of the two pieces. Generally, machined metal surfaces are contaminated with films of oxide, adsorbed gas, oil, or other vapors that impede bonding of surfaces during joining. However, if surface contamination is removed and the two surfaces are mated as closely as possible, joining can be achieved at low temperatures and modest stress levels. In order to apply the SAJ method, the following requirements must be met: (1) inert atmosphere to protect the surfaces from atmospheric gases and oxidation; (2) removal of the existing contamination layers to activate the surfaces; and (3) method for bringing the two surfaces into very intimate contact prior to joining

  10. Evaluation of the usefulness of visceral fat area measurement by the bioelectrical impedance method during workplace health screening

    International Nuclear Information System (INIS)

    Igarashi, Chiyo

    2008-01-01

    In the field of occupational health, health guidance concerning obesity is often conducted in order to prevent lifestyle-related diseases. With recent awareness of the concept of metabolic syndrome, measurement of the visceral fat area (VFA) by CT has been useful for health guidance, but it is difficult in workplace health screening. Presently, the BMI (Body Mass Index), body fat percentage measured by the bioelectrical impedance method, and waist girth at the umbilical level (abdominal girth) are practical indices of obesity used in such health screening. In this study, VAF was measured in 590 clerical or sales workers in the manufacturing industry using a body fat meter capable of a visceral fat measurement by the bioelectrical impedance method. The relationship of this value to the results of biochemical tests and lifestyle was then evaluated using analysis of covariance structures. Analysis indicated that the risk of lifestyle-related disease was closely related to the degree of obesity. Among indices of the degree of obesity, VFA was more closely related than BMI or body fat percentage, and only slightly less closely related than abdominal girth to the risk of lifestyle-related diseases. Since VFA is effective in screening for latent obesity, health guidance based on digital data, and the subjects' body imaging, its measurement by the bioelectrical impedance method is considered useful for workplace health management. (author)

  11. Surface Impedance of Copper MOB Depending on the Annealing Temperature and Deformation Degree

    International Nuclear Information System (INIS)

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

    2006-01-01

    Results of researches of influence of annealing temperature and deformation degree on mechanical features of copper MOB are presented. It is shown that minimal surface resistance is observed in copper samples that were subject to pre-deformation and were annealed in the range of temperatures 873...923 K

  12. Relating Organic Solar Cell Fabrication Methods to Internal Electronic Properties Using Impedance Spectroscopy

    Science.gov (United States)

    Basham, James; Gundlach, David; Jackson, Thomas

    2013-03-01

    We report on the use of impedance spectroscopy to quantify the effect of processing on an array of important OPV device metrics. Interestingly, extract modeled mobilities over the range of 2x10-3 to 1x10-2 cm2/Vs by changing the spinning recipe. We find fast carrier relaxation times of 1x10-4 s for 3% efficiency cells vs 3x10-6 s for a 1.8% efficiency cell, possibly demonstrating reduced recombination in more efficient devices. Devices made via slowly dried films exhibit repressed recombination compared to quickly dried films. Measurements are taken across a bias range of -1 to 1 volt with illumination intensities spanning.001 to 3 suns, in order to test under conditions which are most relevant to real device operation. Impedance spectra are analyzed through the use of a 5 element compact model based upon the work of Bisquert et al. We report an array of device metrics measured via impedance spectroscopy including shunt resistance, effective carrier lifetime, mobility, and capacitance for P3HT:PCBM devices with efficiencies of 3.5% to cell efficiency.

  13. Photoelectrode thin film of dye-sensitized solar cell fabricated by anodizing method and spin coating and electrochemical impedance properties of DSSC

    International Nuclear Information System (INIS)

    Chang, Ho; Chen, Chih-Hao; Kao, Mu-Jung; Chien, Shu-Hua; Chou, Cheng-Yi

    2013-01-01

    The paper studies the photoelectrode thin film of dye-sensitized solar cell (DSSC) fabricated by anodizing method, explores the structure and properties of the fabricated photoelectrode thin film, measures the photoelectric conversion efficiency of DSSC, and finds the electrochemical impedance properties of DSSCs assembled by photoelectrode thin films in different thicknesses. Besides, in order to increase the specific surface area of nanotubes, this paper deposits TiO 2 nanoparticles (TNP) on the surface of titanium oxide nanotube (TNT). As shown in experimental results, the photoelectric conversion efficiency of the DSSC fabricated by the study rises to 6.5% from the original 5.43% without TnB treatment, with an increase of photoelectric conversion efficiency by 19.7%. In addition, when the photoelectrode thin film is fabricated with mixture of TNTs and TNP in an optimal proportion of 2:8 and the photoelectrode thin film thickness is 15.5 μm, the photoelectric conversion efficiency can reach 7.4%, with an increase of 36.7% from the original photoelectric conversion efficiency at 5.43%. Besides, as found in the results of electrochemical impedance analysis, the DSSC with photoelectrode thin film thickness at 15.5 μm has the lowest charge-conduction resistance (R k ) value 9.276 Ω of recombined electron and conduction resistance (R w ) value 3.25 Ω of electrons in TiO 2 .

  14. Surface decontamination compositions and methods

    Science.gov (United States)

    Wright,; Karen, E [Idaho Falls, ID; Cooper, David C [Idaho Falls, ID; Peterman, Dean R [Idaho Falls, ID; Demmer, Ricky L [Idaho Falls, ID; Tripp, Julia L [Pocatello, ID; Hull, Laurence C [Idaho Falls, ID

    2011-03-29

    Clay-based compositions capable of absorbing contaminants from surfaces or objects having surface faces may be applied to a surface and later removed, the removed clay-based compositions absorbing at least a portion of the contaminant from the surface or object to which it was applied.

  15. Impedance Scaling and Impedance Control

    International Nuclear Information System (INIS)

    Chou, W.; Griffin, J.

    1997-06-01

    When a machine becomes really large, such as the Very Large Hadron Collider (VLHC), of which the circumference could reach the order of megameters, beam instability could be an essential bottleneck. This paper studies the scaling of the instability threshold vs. machine size when the coupling impedance scales in a ''normal'' way. It is shown that the beam would be intrinsically unstable for the VLHC. As a possible solution to this problem, it is proposed to introduce local impedance inserts for controlling the machine impedance. In the longitudinal plane, this could be done by using a heavily detuned rf cavity (e.g., a biconical structure), which could provide large imaginary impedance with the right sign (i.e., inductive or capacitive) while keeping the real part small. In the transverse direction, a carefully designed variation of the cross section of a beam pipe could generate negative impedance that would partially compensate the transverse impedance in one plane

  16. Mechanical impedance

    OpenAIRE

    Couroussé, Damien

    2007-01-01

    International audience; Mechanical impedance is a transposition to mechanics of the term impedance that is used and defined in circuit theory. The theory of circuit (theory of Kirchhoff networks) is basically applicable to electric networks but can be considered more generally as a unifying simplified theory of physics available in several domains like mechanics, electromagnetism, aero-acoustics and fluids mechanics.

  17. Comparison of methods for optimal choice of the regularization parameter for linear electrical impedance tomography of brain function.

    Science.gov (United States)

    Abascal, Juan-Felipe P J; Arridge, Simon R; Bayford, Richard H; Holder, David S

    2008-11-01

    Electrical impedance tomography has the potential to provide a portable non-invasive method for imaging brain function. Clinical data collection has largely been undertaken with time difference data and linear image reconstruction methods. The purpose of this work was to determine the best method for selecting the regularization parameter of the inverse procedure, using the specific application of evoked brain activity in neonatal babies as an exemplar. The solution error norm and image SNR for the L-curve (LC), discrepancy principle (DP), generalized cross validation (GCV) and unbiased predictive risk estimator (UPRE) selection methods were evaluated in simulated data using an anatomically accurate finite element method (FEM) of the neonatal head and impedance changes due to blood flow in the visual cortex recorded in vivo. For simulated data, LC, GCV and UPRE were equally best. In human data in four neonatal infants, no significant differences were found among selection methods. We recommend that GCV or LC be employed for reconstruction of human neonatal images, as UPRE requires an empirical estimate of the noise variance.

  18. Kinetics of electrochemically controlled surface reactions on bulk and thin film metals studied with Fourier transform impedance spectroscopy and surface plasmon resonance techniques

    Science.gov (United States)

    Assiongbon, Kankoe A.

    2005-07-01

    In the work presented in this thesis, the surface sensitive electrochemical techniques of cyclic voltametry (CV), potential step (PS) and Fourier transform impedance spectroscopy (FT-EIS), as well as the optical technique of surface plasmon resonance (SPR), were used to probe a wide variety of surface processes at various metal/liquid interface. Three polycrystalline metals (Au, Ta and Cu) and a Cr-coated gold film were used for these studies in different aqueous environments. A combination of CV with FT-EIS and PS was used to investigate electronic and structural proprieties of a modified bulk electrode of Au. This experimental system involved under potential deposition (UPD) of Bi3+ on Au in a supporting aqueous electrolyte containing ClO-4 . UPD range of Bi3+ was determined, and adsorption kinetics of Bi3+ in the presence of coadsorbing anion, ClO-4 were quantified. Potentiodynamic growth of oxide films of Ta in the following electrolytes NaNO3, NaNO3 + 5wt% H2O2, NaOH and NaOH + 5wt% H2O2 had been investigated. The oxide films were grown in the range -0.1 → +0.4V (high electric field) at a scan rate of 10 mV/s. Time resolved A.C. impedance spectroscopy measurements in the frequency range (0.1--20 KHz) were performed to characterize the surface reactions of oxide formation. The results are interpreted in terms of charge conductivity O2- through the oxide film, and disintegration of H2O2 into OH-. In a high pH medium (pH 12), dissociation of H2O2 was catalytically enhanced. This led to destabilization of the electrogenerated tantalum oxide surface film in the form of a soluble hexatantalate species. In contrast with the electrolytes, NaNO3, NaNO3 + 5wt% H2O2, NaOH, where only the oxide growth was observed, the A.C. impedance spectroscopy measurements in NaOH + 5wt% H 2O2 showed competition between oxide formation and its removal. These results are relevant for chemical slurry design in chemical mechanical polishing (CMP) of Ta. Further investigations were

  19. Design And Construction of an Impedance Tube for Measuring Sound Absorptivity and Transmissibility of Materials Using Transfer Function Method

    Science.gov (United States)

    Gowda, Haarish Kapaninaikappa

    Noise is defined as unwanted sound, when perceived in excess can cause many harmful effects such as annoyance, interference with speech, and hearing loss, hence there is a need to control noise in practical situations. Noise can be controlled actively and/or passively, here we discuss the passive noise control techniques. Passive noise control involves using energy dissipating or reflecting materials such as absorbers or barriers respectively. Damping and isolating materials are also used in eliminating structure-borne noise. These materials exhibit properties such as reflection, absorption and transmission loss when incidence is by a sound source. Thus, there is a need to characterize the acoustical properties of these materials for practical use. The theoretical background of the random incident sound absorption with reverberation room and normal incident sound absorption using impedance tube are well documented. The Transfer Matrix method for measuring transmission loss and absorption coefficient using impedance tube is very attractive since it is rather inexpensive and fast. In this research, a low-cost Impedance Tube is constructed using transfer function method to measure both absorption and transmissibility of materials. Equipment and measurement instruments available in the laboratory were used in the construction of the tube, adhering to cost-effectiveness. Care has been taken for precise construction of tube to ensure better measurement results. Further various samples varying from hard non-porous to soft porous materials were tested for absorption and sound transmission loss. Absorption values were also compared with reverberation room method with the available samples further ensuring the reliability of the newly constructed tube for future measurements.

  20. Use of cyclic voltammetry and electrochemical impedance spectroscopy for determination of active surface area of modified carbon-based electrodes

    International Nuclear Information System (INIS)

    Souza, Leticia Lopes de

    2011-01-01

    Carbon-based electrodes as well the ion exchange electrodes among others have been applied mainly in the treatment of industrial effluents and radioactive wastes. Carbon is also used in fuel cells as substrate for the electrocatalysts, having high surface area which surpasses its geometric area. The knowledge of the total active area is important for the determination of operating conditions of an electrochemical cell with respect to the currents to be applied (current density). In this study it was used two techniques to determine the electrochemical active surface area of glassy carbon, electrodes and ion exchange electrodes: cyclic voltammetry (CV) and electrochemical impedance spectroscopy (EIS). The experiments were carried out with KNO 3 0.1 mol.L -1 solutions in a three-electrode electrochemical cell: carbon-based working electrode, platinum auxiliary electrode and Ag/AgCl reference electrode. The glassy carbon and porous carbon electrodes with geometric areas of 3.14 x 10 -2 and 2.83 X 10 -1 cm 2 , respectively, were used. The ion exchange electrode was prepared by mixing graphite, carbon, ion exchange resin and a binder, and this mixture was applied in three layers on carbon felt, using a geometric area of 1.0 cm 2 during the experiments. The capacitance (Cd) of the materials was determined by EIS using Bode diagrams. The value of 172 μF.cm -2 found for the glassy carbon is consistent with the literature data (∼ 200 μF.cm'- 2 ). By VC, varying the scan rate from 0.2 to 2.0 mV.s-1, the capacitance CdS (S = active surface area) in the region of the electric double layer (EDL) of each material was determined. By EIS, the values of C d , 3.0 x 10 -5 μF.cm'- 2 and 11 x 10 3 μF.cm-2, were found for the porous carbon and ion exchange electrodes, respectively, which allowed the determination of active surface areas as 3.73 x 106 cm 2 and 4.72 cm 2 . To sum up, the combined use of EIS and CV techniques is a valuable tool for the calculation of active surface

  1. Technical aspects of impedance plethysmography.

    Directory of Open Access Journals (Sweden)

    Bhuta A

    1990-04-01

    Full Text Available This paper describes the basic methods for measurement of body impedance, electrodes and their configuration, and the measuring instrument with its limitations. A microcomputer assisted impedance plethysmograph system, developed at BARC and different lead configurations for impedance plethysmographic investigation are also described. Typical impedance plethysmographic waveforms recorded from a normal subject and measurement of their amplitude and various time intervals are illustrated.

  2. Ultrasensitive detection and quantification of E. coli O157:H7 using a giant magneto impedance sensor in an open-surface micro fluidic cavity covered with an antibody-modified gold surface

    International Nuclear Information System (INIS)

    Yang, Zhen; Liu, Yan; Lei, Chong; Sun, Xue-cheng; Zhou, Yong

    2016-01-01

    We report on a method for ultrasensitive detection and quantification of the pathogen Escherichia coli (E. coli), type O157:H7. It is using a tortuous-shaped giant magneto impedance (GMI) sensor in combination with an open-surface micro fluidic system coated with a gold film for performing the sandwich immuno binding on its surface. Streptavidin-coated super magnetic Dynabeads were loaded with biotinylated polyclonal antibody to capture E. coli O157:H7. The E. coli-loaded Dynabeads are then injected into the microfluidics system where it comes into contact with the surface of gold nanofilm carrying the monoclonal antibody to form the immuno complex. As a result, the GMI ratio is strongly reduced at high frequencies if E. coli O157:H7 is present. The sensor has a linear response in the 50 to 500 cfu·mL −1 concentration range, and the detection limit is 50 cfu·mL −1 at a working frequency of 2.2 MHz. In our perception, this method provides a valuable tool for developing GMI-based micro fluidic sensors systems for ultrasensitive and quantitative analysis of pathogenic bacteria. The method may also be extended to other sensing applications by employing respective immuno reagents. (author)

  3. An Analytical Method of Auxiliary Sources Solution for Plane Wave Scattering by Impedance Cylinders - A Reference Solution for the Numerical Method of Auxiliary Sources

    DEFF Research Database (Denmark)

    Larsen, Niels Vesterdal; Breinbjerg, Olav

    2004-01-01

    To facilitate the validation of the numerical Method of Auxiliary Sources an analytical Method of Auxiliary Sources solution is derived in this paper. The Analytical solution is valid for transverse magnetic, and electric, plane wave scattering by circular impedance Cylinders, and it is derived...... of the numerical Method of Auxiliary Sources for a range of scattering configurations....... with their singularities at different positions away from the origin. The transformation necessitates a truncation of the wave transformation but the inaccuracy introduced hereby is shown to be negligible. The analytical Method of Auxiliary Sources solution is employed as a reference to investigate the accuracy...

  4. Method to measure autonomic control of cardiac function using time interval parameters from impedance cardiography

    International Nuclear Information System (INIS)

    Meijer, Jan H; Boesveldt, Sanne; Elbertse, Eskeline; Berendse, H W

    2008-01-01

    The time difference between the electrocardiogram and impedance cardiogram can be considered as a measure for the time delay between the electrical and mechanical activities of the heart. This time interval, characterized by the pre-ejection period (PEP), is related to the sympathetic autonomous nervous control of cardiac activity. PEP, however, is difficult to measure in practice. Therefore, a novel parameter, the initial systolic time interval (ISTI), is introduced to provide a more practical measure. The use of ISTI instead of PEP was evaluated in three groups: young healthy subjects, patients with Parkinson's disease, and a group of elderly, healthy subjects of comparable age. PEP and ISTI were studied under two conditions: at rest and after an exercise stimulus. Under both conditions, PEP and ISTI behaved largely similarly in the three groups and were significantly correlated. It is concluded that ISTI can be used as a substitute for PEP and, therefore, to evaluate autonomic neuropathy both in clinical and extramural settings. Measurement of ISTI can also be used to non-invasively monitor the electromechanical cardiac time interval, and the associated autonomic activity, under physiological circumstances

  5. Impedance Determination from Bench Measurements

    CERN Document Server

    Caspers, Friedhelm

    2000-01-01

    The concept of the coaxial wire technique as a bench method for beam coupling impedance measurements is presented. Starting with the lumped element impedance model formulae are given for impedance evaluation from measured scattering parameters, both for the longitudinal and transverse case and also for the loss-factor. Followed by a section on distributed impedances many hints, precautions and practical aspects for the proper use of the measuring instrument are mentioned. The paper concludes with a brief discussion on special methods in particular for simulation of slow beams, measurements beyond waveguide cutoff and resonator techniques for evaluation of very small impedances.

  6. A method for reconstructing tomographic images of evoked neural activity with electrical impedance tomography using intracranial planar arrays.

    Science.gov (United States)

    Aristovich, Kirill Y; dos Santos, Gustavo Sato; Packham, Brett C; Holder, David S

    2014-06-01

    A method is presented for reconstructing images of fast neural evoked activity in rat cerebral cortex recorded with electrical impedance tomography (EIT) and a 6 × 5 mm(2) epicortical planar 30 electrode array. A finite element model of the rat brain and inverse solution with Tikhonov regularization were optimized in order to improve spatial resolution and accuracy. The optimized FEM mesh had 7 M tetrahedral elements, with finer resolution (0.05 mm) near the electrodes. A novel noise-based image processing technique based on t-test significance improved depth localization accuracy from 0.5 to 0.1 mm. With the improvements, a simulated perturbation 0.5 mm in diameter could be localized in a region 4 × 5 mm(2) under the centre of the array to a depth of 1.4 mm, thus covering all six layers of the cerebral cortex with an accuracy of brain hippocampal or thalamic activity could be localized with an accuracy of 0.5 mm with a 256 electrode array covering the brain. Parallel studies have achieved a temporal resolution of 2 ms for imaging fast neural activity by EIT during evoked activity; this encourages the view that fast neural EIT can now resolve the propagation of depolarization-related fast impedance changes in cerebral cortex and deeper in the brain with a resolution equal or greater to the dimension of a cortical column.

  7. Body composition by underwater weighing and bioelectrical impedance methods in college students

    Directory of Open Access Journals (Sweden)

    Cândido S. Pires Neto

    1999-12-01

    Full Text Available The objective of this study was to determine and to compare % fat, LBM and FM of male and female college students measured by hydrostatic weighing and bioelectrical impedance assessment (BIA. To this end, 115 subjects (57 male and 58 female, aged 18 to 30, were assessed by BIA and hydrostatic weighing, which was adopted as the gold standard. The t test for dependent samples revealed that there was a statistically signifi cant difference (p RESUMO objetivo desse estudo foi determinar e comparar o percentual de gordura, massa corporal magra (MCM e massa gorda (MG obtidos pelos métodos da pesagem hidrostática e impedância bioelétrica em universitários dos sexos masculino e feminino. Para tanto, foram avaliados 115 sujeitos (57 homens e 58 mulheres entre 18 e 30 anos de idade através da impedância bioelétrica (IB e pesagem hidrostática (PH, que foi o método adotado como critério. O teste t para amostras dependentes revelou que houve diferença estatística significante, p < 0,001, entre os valores médios das variáveis da composição corporal, apesar da correlação de Pearson entre o %G, MG e MCM decorrente dos dois métodos, terem sido significantes, p < 0,001. Concluímos que a utilização da IB como recurso para as estimativas dos componentes da composição corporal sugere extrema cautela na interpretação dos mesmos.

  8. Surface degradation of Li{sub 1–x}Ni{sub 0.80}Co{sub 0.15}Al{sub 0.05}O{sub 2} cathodes: Correlating charge transfer impedance with surface phase transformations

    Energy Technology Data Exchange (ETDEWEB)

    Sallis, S. [Materials Science and Engineering, Binghamton University, Binghamton, New York 13902 (United States); Pereira, N.; Faenza, N.; Amatucci, G. G. [Energy Storage Research Group, Department of Materials Science and Engineering, Rutgers University, North Brunswick, New Jersey 08902 (United States); Mukherjee, P.; Cosandey, F. [Department of Materials Science and Engineering, Rutgers University, North Brunswick, New Jersey 08902 (United States); Quackenbush, N. F. [Department of Physics, Applied Physics and Astronomy, Binghamton University, Binghamton, New York 13902 (United States); Schlueter, C.; Lee, T.-L. [Diamond Light Source Ltd., Harwell Science and Innovation Campus, Didcot, Oxfordshire OX11 0DE (United Kingdom); Yang, W. L. [Advanced Light Source, Lawrence Berkeley National Laboratory, Berkeley, California 94720 (United States); Piper, L. F. J., E-mail: lpiper@binghamton.edu [Materials Science and Engineering, Binghamton University, Binghamton, New York 13902 (United States); Department of Physics, Applied Physics and Astronomy, Binghamton University, Binghamton, New York 13902 (United States)

    2016-06-27

    The pronounced capacity fade in Ni-rich layered oxide lithium ion battery cathodes observed when cycling above 4.1 V (versus Li/Li{sup +}) is associated with a rise in impedance, which is thought to be due to either bulk structural fatigue or surface reactions with the electrolyte (or combination of both). Here, we examine the surface reactions at electrochemically stressed Li{sub 1–x}Ni{sub 0.8}Co{sub 0.15}Al{sub 0.05}O{sub 2} binder-free powder electrodes with a combination of electrochemical impedance spectroscopy, spatially resolving electron microscopy, and spatially averaging X-ray spectroscopy techniques. We circumvent issues associated with cycling by holding our electrodes at high states of charge (4.1 V, 4.5 V, and 4.75 V) for extended periods and correlate charge-transfer impedance rises observed at high voltages with surface modifications retained in the discharged state (2.7 V). The surface modifications involve significant cation migration (and disorder) along with Ni and Co reduction, and can occur even in the absence of significant Li{sub 2}CO{sub 3} and LiF. These data provide evidence that surface oxygen loss at the highest levels of Li{sup +} extraction is driving the rise in impedance.

  9. Surface degradation of Li1-xNi0.80Co0.15Al0.05O2 cathodes: Correlating charge transfer impedance with surface phase transformations

    Science.gov (United States)

    Sallis, S.; Pereira, N.; Mukherjee, P.; Quackenbush, N. F.; Faenza, N.; Schlueter, C.; Lee, T.-L.; Yang, W. L.; Cosandey, F.; Amatucci, G. G.; Piper, L. F. J.

    2016-06-01

    The pronounced capacity fade in Ni-rich layered oxide lithium ion battery cathodes observed when cycling above 4.1 V (versus Li/Li+) is associated with a rise in impedance, which is thought to be due to either bulk structural fatigue or surface reactions with the electrolyte (or combination of both). Here, we examine the surface reactions at electrochemically stressed Li1-xNi0.8Co0.15Al0.05O2 binder-free powder electrodes with a combination of electrochemical impedance spectroscopy, spatially resolving electron microscopy, and spatially averaging X-ray spectroscopy techniques. We circumvent issues associated with cycling by holding our electrodes at high states of charge (4.1 V, 4.5 V, and 4.75 V) for extended periods and correlate charge-transfer impedance rises observed at high voltages with surface modifications retained in the discharged state (2.7 V). The surface modifications involve significant cation migration (and disorder) along with Ni and Co reduction, and can occur even in the absence of significant Li2CO3 and LiF. These data provide evidence that surface oxygen loss at the highest levels of Li+ extraction is driving the rise in impedance.

  10. Accuracy of an eight-point tactile-electrode impedance method in the assessment of total body water.

    Science.gov (United States)

    Bedogni, G; Malavolti, M; Severi, S; Poli, M; Mussi, C; Fantuzzi, A L; Battistini, N

    2002-11-01

    To establish the accuracy of an eight-polar tactile-electrode impedance method in the assessment of total body water (TBW). Transversal study. University department. Fifty healthy subjects (25 men and 25 women) with a mean (s.d.) age of 40 (12) y. TBW measured by deuterium oxide dilution; resistance (R) of arms, trunk and legs measured at frequencies of 5, 50, 250 and 500 kHz with an eight-polar tactile-electrode impedance-meter (InBody 3.0, Biospace, Seoul, Korea). An algorithm for the prediction of TBW from the whole-body resistance index at 500 kHz (height (2)/R(500) where R is the sum of the segmental resistances of arms, trunk and legs) was developed in a randomly chosen subsample of 35 subjects. This algorithm had an adjusted coefficient of determination (r2(adj)) of 0.81 (P<0.0001) and a root mean square error (RMSE) of 3.6 l (9%). Cross-validation of the predictive algorithm in the remaining 15 subjects gave an r2(adj) of 0.87 (P<0.0001) and an RMSE of 3.0 l (8%). The precision of eight-polar BIA, determined by measuring R three times a day for five consecutive days in a fasting subject, was < or =2.8% for all segments and frequencies. Eight-polar BIA is a precise method that offers accurate estimates of TBW in healthy subjects. This promising method should undergo further studies of precision and its accuracy in assessing extracellular water and appendicular body composition should be determined. Modena and Reggio Emilia University.

  11. METHODS TO DEVELOP A TOROIDAL SURFACE

    Directory of Open Access Journals (Sweden)

    DANAILA Ligia

    2017-05-01

    Full Text Available The paper work presents two practical methods to draw the development of a surface unable to be developed applying classical methods of Descriptive Geometry, the toroidal surface, frequently met in technical practice. The described methods are approximate ones; the development is obtained with the help of points. The accuracy of the methods is given by the number of points used when drawing. As for any other approximate method, when practically manufactured the development may need to be adjusted on site.

  12. Impedance and dielectric characterizations of ionic partitioning in interfaces that membranous, biomimetic and gold surfaces form with electrolytes

    International Nuclear Information System (INIS)

    Chilcott, Terry C.; Guo, Chuan

    2013-01-01

    Silicon dioxide, organic monolayers covalently attached to silicon and gold are used as biosensor substrates and anchoring platforms for hybrid, tethered and supported lipid membranes used in membrane-protein studies. Electrical impedance spectroscopy (EIS) studies of gold in contact with potassium chloride electrolytes of concentrations ranging from 1 mM to 300 mM, characterized the gold–electrolyte interface as principally a Stern layer 20–30 Å thick and conductivity many orders of magnitude less than that of the bulk electrolyte. EIS studies of SiO 2 –electrolyte system that were similar to studies of a tetradecane–electrolyte system are presented herein that reveal an interface comprised of at least two interfacial layers and extending some 10 5 Å into the electrolyte. The average conductivity and thickness values for the layer in contact with the SiO 2 surface (∼10 −6 S m −1 and ∼28 Å, respectively) were of the order of magnitude expected for the Gouy–Chapman layer but the dependency of the thickness on concentration did not reflect the expected dependency of the Debye length over the full range of concentrations. The average values for the next layer (∼10 −3 S m −1 and ∼10 5 Å) exhibited a dependency on concentration similar to that expected for the bulk electrolyte. The theoretical derivations of ionic partitioning arising from the Born (dielectric) energy distributions in both the SiO 2 and gold interfaces were generally consistent with the respective EIS studies and revealed that partitioning in the SiO 2 interface mimicked that in bio-membranous interfaces. The dielectric characterizations suggest that; ionic partitioning in biomimetic interfaces play a role in long-ranging sequestration of organic molecules, the extensiveness of these interfaces contributes to differences in the lipid densities of bilayers formed on biomimetic substrates, and chloride ions have a greater affinity than the smaller potassium ions for gold

  13. Electromagnetic Scattering Analysis of Coated Conductors With Edges Using the Method of Auxiliary Sources (MAS) in Conjunction With the Standard Impedance Boundary Condition (SIBC)

    DEFF Research Database (Denmark)

    Anastassiu, H.T.; D.I.Kaklamani, H.T.; Economou, D.P.

    2002-01-01

    A novel combination of the method of auxiliary sources (MAS) and the standard impedance boundary condition (SIBC) is employed in the analysis of transverse magnetic (TM) plane wave scattering from infinite, coated, perfectly conducting cylinders with square cross sections. The scatterer is initia......A novel combination of the method of auxiliary sources (MAS) and the standard impedance boundary condition (SIBC) is employed in the analysis of transverse magnetic (TM) plane wave scattering from infinite, coated, perfectly conducting cylinders with square cross sections. The scatterer...... efficient than the MoM/SIBC method, proving that the proposed novel combination is a powerful and advantageous computational tool....

  14. Effect of temperature on magnetic and impedance properties of Fe3BO6 of nanotubular structure with a bonded B2O3 surface layer

    Science.gov (United States)

    Kumari, Kalpana; Ram, S.; Kotnala, R. K.

    2018-03-01

    In this investigation, we explore a facile synthesis of Fe3BO6 in the form of small crystallites in the specific shape of nanotubes crystallized from a supercooled liquid Fe2O3-B2O3 precursor. This study includes high resolution transmission electron microscopy (HRTEM) images, magnetic, optical, and impedance properties of the sample. HRTEM images reveal small tubes of Fe3BO6 of 20 nm diameter. A well resolved hysteresis loop appears at 5 K in which the magnetization does not saturate even up to as high field as 50 kOe. It means that the Fe3BO6 nanotubes behave as highly antiferromagnetic in nature in which the surface spins do not align along the field so easily. The temperature dependent impedance describes an ionic Fe3BO6 conductor with a reasonably small activation energy Ea ˜ 0.33 eV. Impedance formalism in terms of a Cole-Cole plot shows a deviation from an ideal Debye-like behavior. We have also reported that electronic absorption spectra are over a spectral range 200-800 nm of wavelengths in order to find out how a bonded surface layer present on the Fe3BO6 crystallites tunes the 3d → 3d electronic transitions in Fe3+ ions.

  15. Electrochemical impedance spectroscopy study of a surface confined redox reaction: The reduction of azobenzene on mercury in the absence of diffusion

    Energy Technology Data Exchange (ETDEWEB)

    Prieto, Francisco, E-mail: dapena@us.es [Department of Physical Chemistry, University of Seville, c/Profesor Garcia Gonzalez no 2, 41012 Seville (Spain); Rueda, Manuela; Hidalgo, Jose; Martinez, Elisa; Navarro, Inmaculada [Department of Physical Chemistry, University of Seville, c/Profesor Garcia Gonzalez no 2, 41012 Seville (Spain)

    2011-09-30

    The kinetics of azobenzene reduction on mercury electrodes in the absence of diffussional mass transport is studied by electrochemical impedance spectroscopy (EIS) in acetic acid/acetate buffered solutions at different pH values. Cyclic voltammetry experiments confirm the absence of diffusion effects and provide the values of the surface equilibrium potential. The analysis of the impedance frequency spectrums at every potential within the faradaic region conforms well the model and provides the global rate constant of the process, k{sub f}. The potential dependence of k{sub f} suggests the existence of an EE mechanism, with two electron transfers controlling the overall rate. The kinetic parameters of every step are obtained and their pH dependences clarify the role played by the protonation steps.

  16. A Comparison between the hp-version of Finite Element Method with EIDORS for Electrical Impedance Tomography.

    Science.gov (United States)

    Saeedizadeh, N; Kermani, S; Rabbani, H

    2011-07-01

    In this study, a hp-version of Finite Element Method (FEM) was applied for forward modeling in image reconstruction of Electrical Impedance Tomography (EIT). The EIT forward solver is normally based on the conventional Finite Element Method (h-FEM). In h-FEM, the polynomial order (p) of the element shape functions is constant and the element size (h) is decreasing. To have an accurate simulation with the h-FEM, a mesh with large number of nodes and elements is usually needed. In order to overcome this problem, the high order finite element method (p-FEM) was proposed. In the p-version, the polynomial order is increasing and the mesh size is constant. Combining the advantages of two previously mentioned methods, the element size (h) was decreased and the polynomial order (p) was increased, simultaneously, which is called the hp-version of Finite Element Method (hp-FEM). The hp-FEM needs a smaller number of nodes and consequently, less computational time and less memory to achieve the same or even better accuracy than h-FEM. The SNR value is 42db for hp-FEM and is 9db for h-FEM. The numerical results are presented and verified that the performance of the hp-version is better than of the h-version in image reconstruction of EIT.

  17. Optimisation of the hot conditioning of carbon steel surfaces of primary heat transport system of Pressurized Heavy Water Reactors using electrochemical impedance spectroscopy

    Science.gov (United States)

    Kiran Kumar, M.; Gaonkar, Krishna; Ghosh, Swati; Kain, Vivekanand; Bojinov, Martin; Saario, Timo

    2010-06-01

    Hot conditioning operation of the primary heat transport system is an important step prior to the commissioning of Pressurized Heavy Water Reactors. One of the major objectives of the operation is to develop a stable and protective magnetite layer on the inner surfaces of carbon steel piping. The correlation between stable magnetite film growth on carbon steel surfaces and the period of exposure to hot conditioning environment is generally established by a combination of weight change measurements and microscopic/morphological observations of the specimens periodically removed during the operation. In the present study, electrochemical impedance spectroscopy (EIS) at room temperature is demonstrated as an alternate, quantitative technique to arrive at an optimal duration of the exposure period. Specimens of carbon steel were exposed for 24, 35 and 48 h during hot conditioning of primary heat transport system of two Indian PHWRs. The composition and morphology of oxide films grown during exposure was characterized by X-ray diffraction and optical microscopy. Further, ex situ electrochemical impedance spectra of magnetite films formed after each exposure were measured, in 1 ppm Li + electrolyte at room temperature as a function of potential in a range of -0.8 to +0.3 VSCE. The defect density of the magnetite films formed after each exposure was estimated by Mott-Schottky analysis of capacitances extracted from the impedance spectra. Further the ionic resistance of the oxide was also extracted from the impedance spectra. Defect density was observed to decrease with increase in exposure time and to saturate after 35 h, indicating stabilisation of the barrier layer part of the magnetite film. The values of the ionic transport resistance start to increase after 35-40 h of exposure. The quantitative ability of EIS technique to assess the film quality demonstrates that it can be used as a supplementary tool to the thickness and morphological characterizations of samples

  18. Optimisation of the hot conditioning of carbon steel surfaces of primary heat transport system of Pressurized Heavy Water Reactors using electrochemical impedance spectroscopy

    International Nuclear Information System (INIS)

    Kiran Kumar, M.; Gaonkar, Krishna; Ghosh, Swati; Kain, Vivekanand; Bojinov, Martin; Saario, Timo

    2010-01-01

    Hot conditioning operation of the primary heat transport system is an important step prior to the commissioning of Pressurized Heavy Water Reactors. One of the major objectives of the operation is to develop a stable and protective magnetite layer on the inner surfaces of carbon steel piping. The correlation between stable magnetite film growth on carbon steel surfaces and the period of exposure to hot conditioning environment is generally established by a combination of weight change measurements and microscopic/morphological observations of the specimens periodically removed during the operation. In the present study, electrochemical impedance spectroscopy (EIS) at room temperature is demonstrated as an alternate, quantitative technique to arrive at an optimal duration of the exposure period. Specimens of carbon steel were exposed for 24, 35 and 48 h during hot conditioning of primary heat transport system of two Indian PHWRs. The composition and morphology of oxide films grown during exposure was characterized by X-ray diffraction and optical microscopy. Further, ex situ electrochemical impedance spectra of magnetite films formed after each exposure were measured, in 1 ppm Li + electrolyte at room temperature as a function of potential in a range of -0.8 to +0.3 V SCE . The defect density of the magnetite films formed after each exposure was estimated by Mott-Schottky analysis of capacitances extracted from the impedance spectra. Further the ionic resistance of the oxide was also extracted from the impedance spectra. Defect density was observed to decrease with increase in exposure time and to saturate after 35 h, indicating stabilisation of the barrier layer part of the magnetite film. The values of the ionic transport resistance start to increase after 35-40 h of exposure. The quantitative ability of EIS technique to assess the film quality demonstrates that it can be used as a supplementary tool to the thickness and morphological characterizations of samples

  19. Different methods to alter surface morphology of high aspect ratio structures

    Energy Technology Data Exchange (ETDEWEB)

    Leber, M., E-mail: moritz.leber@utah.edu [Department of Electrical and Computer Engineering, University of Utah, Salt Lake City, UT (United States); Shandhi, M.M.H. [Department of Electrical and Computer Engineering, University of Utah, Salt Lake City, UT (United States); Hogan, A. [Blackrock Microsystems, Salt Lake City, UT (United States); Solzbacher, F. [Department of Electrical and Computer Engineering, University of Utah, Salt Lake City, UT (United States); Bhandari, R.; Negi, S. [Department of Electrical and Computer Engineering, University of Utah, Salt Lake City, UT (United States); Blackrock Microsystems, Salt Lake City, UT (United States)

    2016-03-01

    Graphical abstract: Surface engineering of high aspect ratio silicon structures. - Highlights: • Multiple roughening techniques for high aspect ratio devices were investigated. • Modification of surface morphology of high aspect ratio silicon devices (1:15). • Decrease of 76% in impedance proves significant increase in surface area. - Abstract: In various applications such as neural prostheses or solar cells, there is a need to alter the surface morphology of high aspect ratio structures so that the real surface area is greater than geometrical area. The change in surface morphology enhances the devices functionality. One of the applications of altering the surface morphology is of neural implants such as the Utah electrode array (UEA) that communicate with single neurons by charge injection induced stimulation or by recording electrical neural signals. For high selectivity between single cells of the nervous system, the electrode surface area is required to be as small as possible, while the impedance is required to be as low as possible for good signal to noise ratios (SNR) during neural recording. For stimulation, high charge injection and charge transfer capacities of the electrodes are required, which increase with the electrode surface. Traditionally, researchers have worked with either increasing the roughness of the existing metallization (platinum grey, black) or other materials such as Iridium Oxide and PEDOT. All of these previously investigated methods lead to more complicated metal deposition processes that are difficult to control and often have a critical impact on the mechanical properties of the metal films. Therefore, a modification of the surface underneath the electrode's coating will increase its surface area while maintaining the standard and well controlled metal deposition process. In this work, the surfaces of the silicon micro-needles were engineered by creating a defined microstructure on the electrodes surface using several

  20. An efficient 3-D eddy-current solver using an independent impedance method for transcranial magnetic stimulation.

    Science.gov (United States)

    De Geeter, Nele; Crevecoeur, Guillaume; Dupre, Luc

    2011-02-01

    In many important bioelectromagnetic problem settings, eddy-current simulations are required. Examples are the reduction of eddy-current artifacts in magnetic resonance imaging and techniques, whereby the eddy currents interact with the biological system, like the alteration of the neurophysiology due to transcranial magnetic stimulation (TMS). TMS has become an important tool for the diagnosis and treatment of neurological diseases and psychiatric disorders. A widely applied method for simulating the eddy currents is the impedance method (IM). However, this method has to contend with an ill conditioned problem and consequently a long convergence time. When dealing with optimal design problems and sensitivity control, the convergence rate becomes even more crucial since the eddy-current solver needs to be evaluated in an iterative loop. Therefore, we introduce an independent IM (IIM), which improves the conditionality and speeds up the numerical convergence. This paper shows how IIM is based on IM and what are the advantages. Moreover, the method is applied to the efficient simulation of TMS. The proposed IIM achieves superior convergence properties with high time efficiency, compared to the traditional IM and is therefore a useful tool for accurate and fast TMS simulations.

  1. Impedance spectroscopy of changes in skin-electrode impedance induced by motion.

    Science.gov (United States)

    Cömert, Alper; Hyttinen, Jari

    2014-11-18

    The motion artifact is an ever-present challenge in the mobile monitoring of surface potentials. Skin-electrode impedance is investigated as an input parameter to detect the motion artifact and to reduce it using various methods. However, the impact of the used impedance measurement frequency on the relationship between measured impedance and the motion artifact and the relationship between the impedance and the motion is not well understood. In this paper, for the first time, we present the simultaneous measurement of impedance at 8 current frequencies during the application of controlled motion to the electrode at monitored electrode mounting force. Three interwoven frequency groupings are used to obtain a spectrum of 24 frequencies between 25 Hz and 1 MHz for ten volunteers. Consequently, the surface potential and one channel of ECG are measured from the electrode subject to controlled motion. The signals are then analyzed in time and frequency domain. The results show that the different frequencies of impedance measurements do not reflect the motion in the same manner. The best correlation between impedance and the applied motion was seen at impedance current frequencies above 17 kHz. For resistance this relationship existed for frequencies above 11 kHz, Reactance did not show good time domain correlation, but had good frequency domain correlation at frequencies higher than 42 kHz. Overall, we found that the impedance signal correlated well with the applied motion; however impedance had lower correlation to actual motion artifact signal. Based on our results, we can conclude that the current frequency used for the impedance measurement has a great effect on the relationship of the measurement to the applied motion and its relationship with the resulting motion artifact. Therefore, when flat textile contact biopotential electrodes are used, frequencies higher than 17 kHz are best suited for impedance measurements intended for the estimation of electrode

  2. Feature Extraction Method for High Impedance Ground Fault Localization in Radial Power Distribution Networks

    DEFF Research Database (Denmark)

    Jensen, Kåre Jean; Munk, Steen M.; Sørensen, John Aasted

    1998-01-01

    of three phase voltages and currents. The method consists of a feature extractor, based on a grid description of the feeder by impulse responses, and a neural network for ground fault localization. The emphasis of this paper is the feature extractor, and the detection of the time instance of a ground fault...

  3. A DTI-based model for TMS using the independent impedance method with frequency-dependent tissue parameters

    Science.gov (United States)

    De Geeter, N.; Crevecoeur, G.; Dupré, L.; Van Hecke, W.; Leemans, A.

    2012-04-01

    Accurate simulations on detailed realistic head models are necessary to gain a better understanding of the response to transcranial magnetic stimulation (TMS). Hitherto, head models with simplified geometries and constant isotropic material properties are often used, whereas some biological tissues have anisotropic characteristics which vary naturally with frequency. Moreover, most computational methods do not take the tissue permittivity into account. Therefore, we calculate the electromagnetic behaviour due to TMS in a head model with realistic geometry and where realistic dispersive anisotropic tissue properties are incorporated, based on T1-weighted and diffusion-weighted magnetic resonance images. This paper studies the impact of tissue anisotropy, permittivity and frequency dependence, using the anisotropic independent impedance method. The results show that anisotropy yields differences up to 32% and 19% of the maximum induced currents and electric field, respectively. Neglecting the permittivity values leads to a decrease of about 72% and 24% of the maximum currents and field, respectively. Implementing the dispersive effects of biological tissues results in a difference of 6% of the maximum currents. The cerebral voxels show limited sensitivity of the induced electric field to changes in conductivity and permittivity, whereas the field varies approximately linearly with frequency. These findings illustrate the importance of including each of the above parameters in the model and confirm the need for accuracy in the applied patient-specific method, which can be used in computer-assisted TMS.

  4. Bioelectrical impedance analysis (BIA): a proposal for standardization of the classical method in adults

    Science.gov (United States)

    González-Correa, C. H.; Caicedo-Eraso, J. C.

    2012-12-01

    The accuracy of BIA measurements is limited by different sources of error such as physical model, cross sectional area, ethnicity, body hydration, age and level of body fat among other variables. Equation for each population is required as they can produce overestimation when manufacturer's equations are used. The classical measurements hand to foot has shown better correlation against hydrodensitometry than foot to foot or hand to hand. However there is a lack for an accepted standard of BIA procedures. This is compounded when there is not a good report of the BIA study's methodology; hence the comparability between the results is poor and reduces the reliability of the method. Perhaps, standardization of methods would be the first step for BIA studies to move forward and subsequently improve its accuracy. Standardized procedures could also minimize the impact of these variables on studies results. The aim of this study was to propose a protocol as a checklist to standardize BIA procedures and produce comparable results from future studies performed with the classic hand-foot configuration in adults.

  5. Determination of beam coupling impedance in the frequency domain

    Energy Technology Data Exchange (ETDEWEB)

    Niedermayer, Uwe

    2016-07-01

    The concept of beam coupling impedance describes the electromagnetic interaction of uniformly moving charged particles with their surrounding structures in the Frequency Domain (FD). In synchrotron accelerators, beam coupling impedances can lead to beam induced component heating and coherent beam instabilities. Thus, in order to ensure the stable operation of a synchrotron, its impedances have to be quantified and their effects have to be controlled. Nowadays, beam coupling impedances are mostly obtained by Fourier transform of wake potentials, which are the results of Time Domain (TD) simulations. However, at low frequencies, low beam velocity, or for dispersive materials, TD simulations become unhandy. In this area, analytical calculations of beam coupling impedance in the FD, combined with geometry approximations, are still widely used. This thesis describes the development of two electromagnetic field solvers to obtain the beam coupling impedance directly in the FD, where the beam velocity is only a parameter and dispersive materials can be included easily. One solver is based on the Finite Integration Technique (FIT) on a staircase mesh. It is implemented both in 2D and 3D. However, the staircase mesh is inefficient on curved structures, which is particularly problematic for the modeling of a dipole source, that is required for the computation of the transverse beam coupling impedance. This issue is overcome by the second solver developed in this thesis, which is based on the Finite Element Method (FEM) on an unstructured triangular mesh. It is implemented in 2D and includes an optional Surface Impedance Boundary Condition (SIBC). Thus, it is well suited for the computation of longitudinal and transverse impedances of long beam pipe structures of arbitrary cross-section. Besides arbitrary frequency and beam velocity, also dispersive materials can be chosen, which is crucial for the computation of the impedance of ferrite kicker magnets. Numerical impedance

  6. Methods of decontaminating surfaces and related compositions

    Science.gov (United States)

    Demmer, Ricky L.; Crosby, Daniel; Norton, Christopher J.

    2016-11-22

    A composition of matter includes water, at least one acid, at least one surfactant, at least one fluoride salt, and ammonium nitrate. A method of decontaminating a surface includes exposing a surface to such a composition and removing the composition from the surface. Other compositions of matter include water, a fatty alcohol ether sulfate, nitrilotriacetic acid, at least one of hydrochloric acid and nitric acid, sodium fluoride, potassium fluoride, ammonium nitrate, and gelatin.

  7. Electrochemical Impedance Spectroscopy—A Simple Method for the Characterization of Polymer Inclusion Membranes Containing Aliquat 336

    Science.gov (United States)

    O'Rourke, Michelle; Duffy, Noel; De Marco, Roland; Potter, Ian

    2011-01-01

    Electrochemical impedance spectroscopy (EIS) has been used to estimate the non-frequency dependent (static) dielectric constants of base polymers such as poly(vinyl chloride) (PVC), cellulose triacetate (CTA) and polystyrene (PS). Polymer inclusion membranes (PIMs) containing different amounts of PVC or CTA, along with the room temperature ionic liquid Aliquat 336 and plasticizers such as trisbutoxyethyl phosphate (TBEP), dioctyl sebecate (DOS) and 2-nitrophenyloctyl ether (NPOE) have been investigated. In this study, the complex and abstract method of EIS has been applied in a simple and easy to use way, so as to make the method accessible to membrane scientists and engineers who may not possess the detailed knowledge of electrochemistry and interfacial science needed for a rigorous interpretation of EIS results. The EIS data reported herein are internally consistent with a percolation threshold in the dielectric constant at high concentrations of Aliquat 336, which illustrates the suitability of the EIS technique since membrane percolation with ion exchangers is a well-known phenomenon. PMID:24957616

  8. Method of Grasping Control by Computing Internal and External Impedances for Two Robot Fingers, and Its Application to Admittance Control of a Robot Hand-Arm System

    Directory of Open Access Journals (Sweden)

    Jian Huang

    2015-08-01

    Full Text Available Impedance control is an important technology used in the grasping control of a robot hand. Numerous studies related to grasping algorithms have been reported in recent years, with the contact force between robot fingers and the object to be grasped being primarily discussed in most cases. Generally, a coupling effect occurs between the internal loop of the grasping operation and the external loop of the interaction with the environment when a multi-fingered robot hand is used to complete a contact task. Therefore, a robot hand cannot hold an object using a large external force to complete a wide range of tasks by applying the conventional method. In this paper, the coupling of the internal/external forces occurring in grasping operations using multiple fingers is analysed. Then, improved impedance control based on the previous method is proposed as an effective tool to solve the problem of grasping failure caused by single-finger contact. Furthermore, a method for applying the improved grasping algorithm to the admittance control of a robot hand-arm system is also proposed. The proposed method divides the impedance effect into the grasping control of the hand and the cooperative control of the arm, so that expanding the task space and increasing the flexibility of impedance adjustment can be achieved. Experiments were conducted to demonstrate the effectiveness of the proposed method.

  9. Monte Carlo method for random surfaces

    International Nuclear Information System (INIS)

    Berg, B.

    1985-01-01

    Previously two of the authors proposed a Monte Carlo method for sampling statistical ensembles of random walks and surfaces with a Boltzmann probabilistic weight. In the present paper we work out the details for several models of random surfaces, defined on d-dimensional hypercubic lattices. (orig.)

  10. Determination of kinetic parameters of Fe sup 3+ reduction mediated by a polyaniline film using steady-state and impedance methods

    Energy Technology Data Exchange (ETDEWEB)

    Deslouis, C. (LP15 du CNRS, Physique des Liquides et Electrochimie, Lab. de l' Univ. Pierre et Marie Curie, 75252 Paris Cedex 05 (FR)); Musiani, M.M.; Pagura, C.; Tribollet, C. (Inst. di Polarografia de Elettrochimica Preparativa del CNR, Corso Stati Uniti, 4, 35020 Camin, Padova (IT))

    1991-09-01

    This paper discusses the Fe{sup 3+} reduction reaction studied at Pt and polyaniline rotating disk electrodes by steady-state and impedance methods with the aim of testing the possibility of achieving the charge transfer resistance (R{sub ts}) of a redox reaction mediated by a conducting polymer film by ac impedance R{sub ts} was obtained as a function of electrode potential and rotation rate by nonlinear least squares fitting of a previously developed kinetic equation to the experimental data. These R{sub ts} values were combined with steady-state ones to calculate b{sub c} and k{sup 0}.

  11. Application of a finite element method for computing grazing incidence wave structure in an impedance tube - Comparison with experiment. [for duct liner aeroacoustic design

    Science.gov (United States)

    Lester, H. C.; Parrott, T. L.

    1979-01-01

    The acoustic performance of a liner specimen, in a grazing incidence impedance tube, is analyzed using a finite element method. The liner specimen was designed to be a locally reacting, two-degree-of-freedom type with the resistance and reactance provided by perforated facesheets and compartmented cavities. Measured and calculated wave structures are compared for both normal and grazing incidence from 0.3 to 1.2 kHz. A finite element algorithm was incorporated into an optimization loop in order to predict liner grazing incidence impedance from measured SWR and null position data. Results suggest that extended reaction effects may have been responsible for differences between normal and grazing incidence impedance estimates.

  12. Interaction of DNA with echinomycin at the mercury electrode surface as detected by impedance and chronopotentiometric measurements

    Czech Academy of Sciences Publication Activity Database

    Hasoň, Stanislav; Dvořák, Jakub; Jelen, František; Vetterl, Vladimír

    2002-01-01

    Roč. 56, č. 5 (2002), s. 905-913 ISSN 0039-9140 R&D Projects: GA AV ČR IAA4004901; GA AV ČR IAA4004002; GA AV ČR IBS5004107; GA ČR GV204/97/K084 Grant - others:GA FRVŠ(XC) G40583; GA FRVŠ(XC) F40564 Institutional research plan: CEZ:AV0Z5004920 Keywords : electrochemical impedance spectroscopy * DNA * echinomycin Subject RIV: BO - Biophysics Impact factor: 2.054, year: 2002

  13. Surface physics theoretical models and experimental methods

    CERN Document Server

    Mamonova, Marina V; Prudnikova, I A

    2016-01-01

    The demands of production, such as thin films in microelectronics, rely on consideration of factors influencing the interaction of dissimilar materials that make contact with their surfaces. Bond formation between surface layers of dissimilar condensed solids-termed adhesion-depends on the nature of the contacting bodies. Thus, it is necessary to determine the characteristics of adhesion interaction of different materials from both applied and fundamental perspectives of surface phenomena. Given the difficulty in obtaining reliable experimental values of the adhesion strength of coatings, the theoretical approach to determining adhesion characteristics becomes more important. Surface Physics: Theoretical Models and Experimental Methods presents straightforward and efficient approaches and methods developed by the authors that enable the calculation of surface and adhesion characteristics for a wide range of materials: metals, alloys, semiconductors, and complex compounds. The authors compare results from the ...

  14. Impedance of accelerator components

    International Nuclear Information System (INIS)

    Corlett, J.N.

    1996-05-01

    As demands for high luminosity and low emittance particle beams increase, an understanding of the electromagnetic interaction of these beams with their vacuum chamber environment becomes more important in order to maintain the quality of the beam. This interaction is described in terms of the wake field in time domain, and the beam impedance in frequency domain. These concepts are introduced, and related quantities such as the loss factor are presented. The broadband Q = 1 resonator impedance model is discussed. Perturbation and coaxial wire methods of measurement of real components are reviewed

  15. Implantable Impedance Plethysmography

    Directory of Open Access Journals (Sweden)

    Michael Theodor

    2014-08-01

    Full Text Available We demonstrate by theory, as well as by ex vivo and in vivo measurements that impedance plethysmography, applied extravascularly directly on large arteries, is a viable method for monitoring various cardiovascular parameters, such as blood pressure, with high accuracy. The sensor is designed as an implant to monitor cardiac events and arteriosclerotic progression over the long term.

  16. Impedance plethysmography: basic principles.

    Directory of Open Access Journals (Sweden)

    Babu J

    1990-04-01

    Full Text Available Impedance Plethysmography technique has been discussed with explanation of two compartment model and parallel conductor theory for the estimation of peripheral blood flow and stroke volume. Various methods for signal enhancement to facilitate computation of blood flow are briefly described. Source of error in the estimation of peripheral blood flow is identified and the correction has been suggested.

  17. Comparison between bioelectrical impedance analysis and body mass index methods in determination of obesity prevalence in Ahvazi women.

    Science.gov (United States)

    Amani, R

    2007-04-01

    Obesity has an increasing trend worldwide. Recently, application of body mass index (BMI) cutoff points of obesity classification for all population studies has been questioned. On the other hand, bioelectrical impedance analysis (BIA) is a safe, accurate, reliable and inexpensive method for screening the overweight and obesity in such studies. There were three objectives followed in this research: to determine the prevalence of obesity and overweight in married women using BMI and BIA methods; to evaluate the correlation between these methods; and to compare the women's obesity degrees according to their educational levels. Six hundred and thirty-seven healthy married women 18-40 years aged, who had referred to 14 health centers of the city of Ahvaz (center of Khouzestan province, south-west of Iran) were recruited in a cross-sectional design, and their socio-economic and anthropometric questionnaires were completed by the trained students. Body fat percent (%BF) and body fat mass (BFM) were measured using BIA method. BMI>25 and >30 kg/m(2) were used as criteria for determining the overweight and obese women, respectively. %BF>35% was regarded as cutoff for defining obesity. Mean age+/-s.d. of the women was 26.9+/-5.8 years and majority of them were housewives with secondary educational level. Their BMI, %BF, waist-to-hip ratio, and mid-upper arm circumference means were: 25.9(4.7) kg/m(2), 27.6(7.3)%, 0.75(0.08) and 27.9(3.9) cm, respectively. Central obesity was prevalent in 21.2% of the subjects. Prevalence of obesity determined by BMI and BIA methods was 18.3 and 15.5% and women within normal ranges were detected in 44.7 and 46% of the subjects by these methods, respectively. However, thin (underweight) women were 2.6 and 14.6% of the subjects studied, respectively. About one half of the women were overweight or obese. BMI was statistically correlated with BFM (r=0.86; PObesity and overweight is prevalent in about one-half of the Ahvazian married women and

  18. Generalised empirical method for predicting surface subsidence

    International Nuclear Information System (INIS)

    Zhang, M.; Bhattacharyya, A.K.

    1994-01-01

    Based on a simplified strata parameter, i.e. the ratio of total thickness of the strong rock beds in an overburden to the overall thickness of the overburden, a Generalised Empirical Method (GEM) is described for predicting the maximum subsidence and the shape of a complete transverse subsidence profile due to a single completely extracted longwall panel. In the method, a nomogram for predicting the maximum surface subsidence is first developed from the data collected from subsidence measurements worldwide. Then, a method is developed for predicting the shapes of complete transfer subsidence profiles for a horizontal seam and ground surface and is verified by case studies. 13 refs., 9 figs., 2 tabs

  19. Characterization of full set material constants of piezoelectric materials based on ultrasonic method and inverse impedance spectroscopy using only one sample.

    Science.gov (United States)

    Li, Shiyang; Zheng, Limei; Jiang, Wenhua; Sahul, Raffi; Gopalan, Venkatraman; Cao, Wenwu

    2013-09-14

    The most difficult task in the characterization of complete set material properties for piezoelectric materials is self-consistency. Because there are many independent elastic, dielectric, and piezoelectric constants, several samples are needed to obtain the full set constants. Property variation from sample to sample often makes the obtained data set lack of self-consistency. Here, we present a method, based on pulse-echo ultrasound and inverse impedance spectroscopy, to precisely determine the full set physical properties of piezoelectric materials using only one small sample, which eliminated the sample to sample variation problem to guarantee self-consistency. The method has been applied to characterize the [001] C poled Mn modified 0.27Pb(In 1/2 Nb 1/2 )O 3 -0.46Pb(Mg 1/3 Nb 2/3 )O 3 -0.27PbTiO 3 single crystal and the validity of the measured data is confirmed by a previously established method. For the inverse calculations using impedance spectrum, the stability of reconstructed results is analyzed by fluctuation analysis of input data. In contrast to conventional regression methods, our method here takes the full advantage of both ultrasonic and inverse impedance spectroscopy methods to extract all constants from only one small sample. The method provides a powerful tool for assisting novel piezoelectric materials of small size and for generating needed input data sets for device designs using finite element simulations.

  20. Experimental Study of the Course of Threshold Current, Voltage and Electrode Impedance During Stepwise Stimulation From the Skin Surface to the Human Cortex

    NARCIS (Netherlands)

    Szelenyi, Andrea; Journee, Henricus Louis; Herrlich, Simon; Galistu, Gianni M.; van den Berg, Joris; van Dijk, J. Marc C.

    Background: Transcranial electric stimulation as used during intraoperative neurostimulation is dependent on electrode and skull impedances. Objective: Threshold currents, voltages and electrode impedances were evaluated with electrical stimulation at 8 successive layers between the skin and the

  1. AC impedance diagnosis of a 500 W PEM fuel cell stack . Part I: Stack impedance

    Science.gov (United States)

    Yuan, Xiaozi; Sun, Jian Colin; Blanco, Mauricio; Wang, Haijiang; Zhang, Jiujun; Wilkinson, David P.

    Diagnosis of stack performance is of importance to proton exchange membrane (PEM) fuel cell research. This paper presents the diagnostic testing results of a 500 W Ballard Mark V PEM fuel cell stack with an active area of 280 cm 2 by electrochemical impedance spectroscopy (EIS). The EIS was measured using a combination of a FuelCon test station, a TDI loadbank, and a Solartron 1260 Impedance/Gain-Phase Analyzer operating in the galvanostatic mode. The method described in this work can obtain the impedance spectra of fuel cells with a larger geometric surface area and power, which are normally difficult to measure due to the limitations on commercial load banks operating at high currents. By using this method, the effects of temperature, flow rate, and humidity on the stack impedance spectra were examined. The results of the electrochemical impedance analysis show that with increasing temperature, the charge transfer resistance decreases due to the slow oxygen reduction reaction (ORR) process at low temperature. If the stack is operated at a fixed air flow rate, a low frequency arc appears and grows with increasing current due to the shortage of air. The anode humidification cut-off does not affect the spectra compared to the cut-off for cathode humidification.

  2. Electrical impedance spectroscopy for quality assessment of meat and fish: A review on basic principles, measurement methods, and recent advances

    Science.gov (United States)

    Electrical impedance spectroscopy (EIS), as an effective analytical technique for electrochemical system, has shown a wide application for food quality and safety assessment recently. Individual differences of livestock cause high variation in quality of raw meat and fish and their commercialized pr...

  3. An impedance method for spatial sensing of 3D cell constructs – towards applications in tissue engineering

    DEFF Research Database (Denmark)

    Canali, Chiara; Mazzoni, Chiara; Larsen, Layla Bashir

    2015-01-01

    ) cells were encapsulated in gelatin to form artificial 3D cell constructs and detected when placed in different positions inside large gelatin scaffolds. Taken together, these results open new perspectives for impedance-based sensing technologies for non-invasive monitoring in tissue engineering...

  4. Impedance measurements in the biomedical sciences.

    Science.gov (United States)

    Coffman, Frederick D; Cohen, Stanley

    2013-01-01

    Biological organisms and their component organs, tissues and cells have unique electrical impedance properties. Impedance properties often change with changes in structure, composition, and metabolism, and can be indicative of the onset and progression of disease states. Over the past 100 years, instruments and analytical methods have been developed to measure the impedance properties of biological specimens and to utilize these measurements in both clinical and basic science settings. This chapter will review the applications of impedance measurements in the biomedical sciences, from whole body analysis to impedance measurements of single cells and cell monolayers, and how cellular impedance measuring instruments can now be used in high throughput screening applications.

  5. A rigorous uniform diffraction analysis of the electromagnetic scattering from impedance edges and junctions

    Science.gov (United States)

    Fortney, Joseph C.

    1991-12-01

    This paper investigates the scattering from impedance strips and impedance-loaded conducting strips. The impedance strips are analyzed using Senior's impedance half plane formulation. Once the primary diffraction from the impedance half plane is presented, it is used to develop multiple diffraction mechanisms on an impedance strip. The scattering from impedance-loaded strips are analyzed using Maliuzhinets' impedance wedge formulation. The primary diffraction mechanism from an impedance wedge is used to develop the multiple diffractions on an impedance double wedge. The multiple diffractions on both types of strips are developed using the Extended Spectral Ray Method. Sample calculations are made for impedance strips and impedance-loaded strips for a large purely capacitive impedance, a large purely inductive impedance, a large real impedance, and a small real impedance. Measurements are made for impedance strips and impedance loaded strips and are used to compare against predictions. The impedance materials used are two magnetic radar absorbing materials and two resistive materials.

  6. Gynecologic electrical impedance tomograph

    Science.gov (United States)

    Korjenevsky, A.; Cherepenin, V.; Trokhanova, O.; Tuykin, T.

    2010-04-01

    Electrical impedance tomography extends to the new and new areas of the medical diagnostics: lungs, breast, prostate, etc. The feedback from the doctors who use our breast EIT diagnostic system has induced us to develop the 3D electrical impedance imaging device for diagnostics of the cervix of the uterus - gynecologic impedance tomograph (GIT). The device uses the same measuring approach as the breast imaging system: 2D flat array of the electrodes arranged on the probe with handle is placed against the body. Each of the 32 electrodes of the array is connected in turn to the current source while the rest electrodes acquire the potentials on the surface. The current flows through the electrode of the array and returns through the remote electrode placed on the patient's limb. The voltages are measured relative to another remote electrode. The 3D backprojection along equipotential surfaces is used to reconstruct conductivity distribution up to approximately 1 cm in depth. Small number of electrodes enables us to implement real time imaging with a few frames per sec. rate. The device is under initial testing and evaluation of the imaging capabilities and suitability of usage.

  7. Impedance source power electronic converters

    CERN Document Server

    Liu, Yushan; Ge, Baoming; Blaabjerg, Frede; Ellabban, Omar; Loh, Poh Chiang

    2016-01-01

    Impedance Source Power Electronic Converters brings together state of the art knowledge and cutting edge techniques in various stages of research related to the ever more popular impedance source converters/inverters. Significant research efforts are underway to develop commercially viable and technically feasible, efficient and reliable power converters for renewable energy, electric transportation and for various industrial applications. This book provides a detailed understanding of the concepts, designs, controls, and application demonstrations of the impedance source converters/inverters. Key features: Comprehensive analysis of the impedance source converter/inverter topologies, including typical topologies and derived topologies. Fully explains the design and control techniques of impedance source converters/inverters, including hardware design and control parameter design for corresponding control methods. Presents the latest power conversion solutions that aim to advance the role of pow...

  8. Determination of the ionic transport numbers of lanthanum gallate materials by impedance spectroscopy and modified EMF method

    Directory of Open Access Journals (Sweden)

    Peña-Martínez, J.

    2008-06-01

    Full Text Available A combination of impedance spectroscopy and a modified electromotive force method (emf were used to evaluate the ionic transport numbers and the overall conductivity of several doped lanthanum gallate materials, i.e. La0.9Sr0.1Ga1-xMgxO3-δ (x=0.05-0.30, La0.9A0.1Ga0.8Mg0.2O3-δ (A=Sr, Ba and Ca and La0.9Sr0.1Ga0.8Mg0.2-yCoyO3-δ (y=0.015 and 0.045. La0.9Sr0.1Ga0.8Mg0.2O2.85 (LSGM sample showed the maximum ionic transport number in the temperature range 900-1173 K, around 0.99 in both O2/air and H2/air gradients.

    La conductividad total y los números de transporte iónico de las composiciones, basadas en el galato de lantano, La0,9Sr0,1Ga1-xMgxO3-δ (x=0,05-0,30, La0,9A0,1Ga0,8Mg0,2O3-δ (A=Sr, Ba, Ca y La0,9Sr0,1Ga0,8Mg0,2-yCoyO3-δ (y=0.015; 0,045 fueron estudiadas mediante una combinación de técnicas de espectroscopia de impedancia compleja y fuerza electromotriz (fem. La composición La0,9Sr0,1Ga0,8Mg0,2O2,85 (LSGM presenta el mayor número de transporte iónico, concretamente 0,99 en el rango de temperaturas 900-1173 K, tanto en gradiente de O2/aire como de H2/aire.

  9. Electrical Impedance Tomography of Breast Cancer

    Science.gov (United States)

    2004-06-01

    Algorithm in Magnetic Resonance Electrical Impedance Tomography (MREIT): Phantom Experiment for Static Resistivity Images," IEEE Trans. on Medical Imaging...Tomography MREIT: Magnetic Resonance Electrical Impedance Tomography FEM: Finite Element Method EIS: Electrical Impedance Scanning OPAMP : Operational...transconductance amplifier was designed and built using three LM741 OPAMP circuits to convert the voltage from the signal generator into a current

  10. A 3D Multiport Scattering Matrix Based-Method for Educing Wall Impedance of Cylindrical Lined Duct Section: Simulation and Error Evaluation

    Directory of Open Access Journals (Sweden)

    Mohamed Taktak

    2009-01-01

    Full Text Available The first step to achieve the development of an original indirect method to educe the wall normalized acoustic impedance of a cylindrical lined duct section which includes frequency and modal content pressure field dependence is introduced. It is based on the minimization of the difference between numerical and experimental acoustic power dissipations deduced from the 3D numerical and experimental scattering matrices of a lined duct element. The work presented in this paper is a step toward conducting experiments with a flow duct facility developed during the European DUCAT program. To validate this eduction technique, a simulation of the experiment is performed for no flow conditions assuming an axi-symmetric wall lined with a locally reacting material whose impedance was measured with the two microphone method (TMM. The simulation conducted for two incident pressure vectors with a Monte Carlo's technique also provides an assessment of the uncertainty in three predominant experimental parameters on the scattering matrix coefficients, the acoustic power dissipation, and the educed impedance whose results will be useful during the experiments being conducted.

  11. Evaluation of electrical broad bandwidth impedance spectroscopy as a tool for body composition measurement in cows in comparison with body measurements and the deuterium oxide dilution method.

    Science.gov (United States)

    Schäff, C T; Pliquett, U; Tuchscherer, A; Pfuhl, R; Görs, S; Metges, C C; Hammon, H M; Kröger-Koch, C

    2017-05-01

    Body fatness and degree of body fat mobilization in cows vary enormously during their reproduction cycle and influence energy partitioning and metabolic adaptation. The objective of the study was to test bioelectrical impedance spectroscopy (BIS) as a method for predicting fat depot mass (FDM), in living cows. The FDM is defined as the sum of subcutaneous, omental, mesenteric, retroperitoneal, and carcass fat mass. Bioelectrical impedance spectroscopy is compared with the prediction of FDM from the deuterium oxide (DO) dilution method and from body conformation measurements. Charolais × Holstein Friesian (HF; = 18; 30 d in milk) crossbred cows and 2 HF (lactating and nonlactating) cows were assessed by body conformation measurements, BIS, and the DO dilution method. The BCS of cows was a mean of 3.68 (SE 0.64). For the DO dilution method, a bolus of 0.23 g/kg BW DO (60 atom%) was intravenously injected and deuterium (D) enrichment was analyzed in plasma and whey by stabile isotope mass spectrometry, and total body water content was calculated. Impedance measurement was performed using a 4-electrode interface and time domain-based measurement system consisting of a voltage/current converter for applying current stimulus and an amplifier for monitoring voltage across the sensor electrodes. For the BIS, we used complex impedances over three frequency decades that delivers information on intra- and extracellular water and capacity of cell membranes. Impedance data (resistance of extra- and intracellular space, cell membrane capacity, and phase angle) were extracted 1) by simple curve fit to extract the resistance at direct current and high frequency and 2) by using an electrical equivalent circuit. Cows were slaughtered 7 d after BIS and D enrichment measurements and dissected for the measurement of FDM. Multiple linear regression analyses were performed to predict FDM based on data obtained from body conformation measurements, BIS, and D enrichment, and applied

  12. Advances In Impedance Theory

    International Nuclear Information System (INIS)

    Stupakov, G.

    2009-01-01

    We review recent progress in the following areas of the impedance theory: calculation of impedance of tapers and small angle collimators; optical approximation and parabolic equation for the high-frequency impedance; impedance due to resistive inserts in a perfectly conducting pipe.

  13. Novel method to study pericyte contractility and responses to ischaemia in vitro using electrical impedance.

    Science.gov (United States)

    Neuhaus, Ain A; Couch, Yvonne; Sutherland, Brad A; Buchan, Alastair M

    2017-06-01

    Pericytes are contractile vascular mural cells overlying capillary endothelium, and they have been implicated in a variety of functions including regulation of cerebral blood flow. Recent work has suggested that both in vivo and ex vivo, ischaemia causes pericytes to constrict and die, which has implications for microvascular reperfusion. Assessing pericyte contractility in tissue slices and in vivo is technically challenging, while in vitro techniques remain unreliable. Here, we used isolated cultures of human brain vascular pericytes to examine their contractile potential in vitro using the iCelligence electrical impedance system. Contraction was induced using the vasoactive peptide endothelin-1, and relaxation was demonstrated using adenosine and sodium nitroprusside. Endothelin-1 treatment also resulted in increased proliferation, which we were able to monitor in the same cell population from which we recorded contractile responses. Finally, the observation of pericyte contraction in stroke was reproduced using chemical ischaemia, which caused a profound and irreversible contraction clearly preceding cell death. These data demonstrate that isolated pericytes retain a contractile phenotype in vitro, and that it is possible to quantify this contraction using real-time electrical impedance recordings, providing a significant new platform for assessing the effects of vasoactive and vasculoprotective compounds on pericyte contractility.

  14. Plasmonic nanostructures for surface enhanced spectroscopic methods.

    Science.gov (United States)

    Jahn, Martin; Patze, Sophie; Hidi, Izabella J; Knipper, Richard; Radu, Andreea I; Mühlig, Anna; Yüksel, Sezin; Peksa, Vlastimil; Weber, Karina; Mayerhöfer, Thomas; Cialla-May, Dana; Popp, Jürgen

    2016-02-07

    A comprehensive review of theoretical approaches to simulate plasmonic-active metallic nano-arrangements is given. Further, various fabrication methods based on bottom-up, self-organization and top-down techniques are introduced. Here, analytical approaches are discussed to investigate the optical properties of isotropic and non-magnetic spherical or spheroidal particles. Furthermore, numerical methods are introduced to research complex shaped structures. A huge variety of fabrication methods are reviewed, e.g. bottom-up preparation strategies for plasmonic nanostructures to generate metal colloids and core-shell particles as well as complex-shaped structures, self-organization as well as template-based methods and finally, top-down processes, e.g. electron beam lithography and its variants as well as nanoimprinting. The review article is aimed at beginners in the field of surface enhanced spectroscopy (SES) techniques and readers who have a general interest in theoretical modelling of plasmonic substrates for SES applications as well as in the fabrication of the desired structures based on methods of the current state of the art.

  15. RF impedance measurement calibration

    International Nuclear Information System (INIS)

    Matthews, P.J.; Song, J.J.

    1993-01-01

    The intent of this note is not to explain all of the available calibration methods in detail. Instead, we will focus on the calibration methods of interest for RF impedance coupling measurements and attempt to explain: (1). The standards and measurements necessary for the various calibration techniques. (2). The advantages and disadvantages of each technique. (3). The mathematical manipulations that need to be applied to the measured standards and devices. (4). An outline of the steps needed for writing a calibration routine that operated from a remote computer. For further details of the various techniques presented in this note, the reader should consult the references

  16. Comparison of Modified Impedance Whole Blood Platelet Aggregation Method Detecting Platelet Function in ACS Patients with Different CYP2C19 Genotypes.

    Science.gov (United States)

    Cui, Chanjuan; Qiao, Rui; Zhang, Jie

    2016-01-01

    A reliable laboratory test to monitor onclopidogrel platelet reactivity (PR) is very necessary. In addition, genetic factors also play an important part in onclopidogrel PR. This study aimed to modify the original impedance whole blood platelet aggregation assay associated with the release assay to monitor onclopidogrel PR and assess their relationship with genotype. We adjusted the concentration of calcium in the in vitro reaction system of platelet aggregation to modify the original impedance whole blood platelet aggregation assay. Meanwhile, chronolume, which quantified the adenosine triphosphate (ATP) released from platelet dense granules, is added to this reaction system to reflect the platelet release function. In the modified assay, platelet magnified activation time (MAT) and the maximal platelet ATP release value (RV) were used to reflect platelet function parameters. In the original assay, the electrical resistance (omega) and RV were used to reflect platelet function parameters. Onclopidogrel PR was detected by the original impedance whole blood platelet aggregation assay, modified assay, and flow cytometric vasodilator stimulated phosphoprotein (VASP) assay in 168 patients with acute coronary syndromes (ACS). CYP2C19*2 and CYP2C19*3 polymorphisms were also detected in all of these patients. This modified method showed that when 12.5 microL CaCl2 (0.2 mmol/L) was added to the reaction system, MAT was appropriate (93 +/- 23 seconds). The CVs for the modified impedance assay and release assay were 9.31% and 6.13%, respectively. The mean VASP-PRI in the patient group treated with clopidogrel was significantly lower than that in the control group without antiplatelet therapy (54.88 +/- 16.81% vs. 79.86 +/- 10.24%, p 50% group were shorter than that in the PRI 50% group were higher than that in the PRI omega) and RV of the original method showed no differences between the two groups [0 (0-2) vs. 0 (0-1.25), 0.05 (0-0.25) vs. 0.08 (0-0.24); p > 0.05, p > 0

  17. In situ electrochemical impedance spectroscopy/synchrotron radiation grazing incidence X-ray diffraction-A powerful new technique for the characterization of electrochemical surfaces and interfaces

    International Nuclear Information System (INIS)

    De Marco, Roland; Jiang, Z.-T.; Martizano, Jay; Lowe, Alex; Pejcic, Bobby; Riessen, Arie van

    2006-01-01

    A marriage of electrochemical impedance spectroscopy (EIS) and in situ synchrotron radiation grazing incidence X-ray diffraction (SR-GIXRD) has provided a powerful new technique for the elucidation of the mechanistic chemistry of electrochemical systems. In this study, EIS/SR-GIXRD has been used to investigate the influence of metal ion buffer calibration ligands, along with natural organic ligands in seawater, on the behaviour of the iron chalcogenide glass ion-selective electrode (ISE). The SR-GIXRD data demonstrated that citrate - a previously reported poor iron calibration ligand for the analysis of seawater - induced an instantaneous and total dissolution of crystalline GeSe and Sb 2 Se 3 in the modified surface layer (MSL) of the ISE, while natural organic ligands in seawater and a mixture of ligands in a mimetic seawater ligand system protected the MSL's crystalline inclusions of GeSe and Sb 2 Se 3 from oxidative attack. Expectedly, the EIS data showed that citrate induced a loss in the medium frequency time constant for the MSL of the ISE, while seawater's natural organic ligands and the mimetic ligand system preserved the medium frequency EIS response characteristics of the ISE's MSL. The new EIS/SR-GIXRD technique has provided insights into the suitability of iron calibration ligands for the analysis of iron in seawater

  18. Comparison of foot-to-foot and hand-to-foot bioelectrical impedance methods in a population with a wide range of body mass indices.

    Science.gov (United States)

    Gagnon, Claudia; Ménard, Julie; Bourbonnais, Annie; Ardilouze, Jean-Luc; Baillargeon, Jean-Patrice; Carpentier, André C; Langlois, Marie-France

    2010-10-01

    Several techniques are currently used for measurement of body composition. Bioelectrical impedance assessment (BIA) is a simple, noninvasive method of assessing body composition. We aimed to compare multifrequency hand-to-foot (HF-BIA) and foot-to-foot (FF-BIA) bioelectrical impedance analysis techniques to assess fat-free mass (FFM) in a population with a wide range of body mass indices (BMI). This was a cross-sectional study of 198 adult subjects. Anthropometric and BIA measures (HF-BIA with Hydra ICF/ECF, Xitron Technologies and FF-BIA with Tanita, model TBF-300A) were recorded after a 12-h fast. Participants had a mean age of 42 years and BMI of 33.50.7 (range, 17.7-65.6) kg/m2. Mean FFM with HF-BIA (FFM BIA/HF) and FF-BIA (FFM BIA/FF) were 61.31.3 kg and 58.10.9 kg, respectively (P 42 kg/m2 (-8.0 kg; P=0.001). Pearson correlations between both methods were very high for FFM (r=0.92), fat mass (r=0.91), and % fat mass (r=0.85), all Pobese subjects.

  19. Method for surface treatment by electron beams

    International Nuclear Information System (INIS)

    Panzer, S.; Doehler, H.; Bartel, R.; Ardenne, T. von.

    1985-01-01

    The invention has been aimed at simplifying the technology and saving energy in modifying surfaces with the aid of electron beams. The described beam-object geometry allows to abandon additional heat treatments. It can be used for surface hardening

  20. Impedance spectroscopy and morphology of SrBi{sub 4}Ti{sub 4}O{sub 15} ceramics prepared by soft chemical method

    Energy Technology Data Exchange (ETDEWEB)

    Rout, S.K. [Department of Chemical and Biomolecular Engineering, KAIST (Korea, Republic of); Department of Applied Physics, BIT, Mesra, Ranchi (India)], E-mail: drskrout@gmail.com; Hussian, Ali; Lee, J.S. [School of Materials Science and Engineering University of Ulsan (Korea, Republic of); Kim, I.W. [Department of Physics, University of Ulsan (Korea, Republic of); Woo, S.I. [Department of Chemical and Biomolecular Engineering, KAIST (Korea, Republic of)], E-mail: siwoo@kaist.ac.kr

    2009-05-27

    In this work, we have synthesized polycrystalline SrBi{sub 4}Ti{sub 4}O{sub 15} (SBiT) ceramics by soft chemical method. These ceramics were structurally characterized by analysis of X-ray diffraction (XRD) patterns, indicates that SBiT ceramics present an orthorhombic structure. Scanning electron micrograph shows that the grains exhibit a plate like morphology. Dielectric relaxations of the SBiT ceramics were investigated in the temperature range 100-700 deg. C. Using the Cole-Cole model, an analysis of the dielectric loss with frequency was performed, assuming a distribution of relaxation time. The presence of the peaks in temperature dependent dielectric loss indicates that the hoping of charge carriers is responsible for the relaxation. Impedance studies shows a non-Debye type relaxation, and relaxation frequency shift to higher side with increase in temperature. A significant shift in impedance loss peaks towards higher frequency side indicates conduction in material and favoring the long range motion of mobile charge carriers. The Nyquist plot shows overlapping semicircles, for grain and grain boundary of SBiT ceramics. The frequency dependent ac conductivity at different temperatures indicates that the conduction process is thermally activated process and the spectra follow the universal power law. The hopping frequency shifts towards higher frequency side with increase of temperature, below which the conductivity is frequency independent. The variation of dc conductivity confirms that the SBiT ceramics exhibits negative temperature coefficient of resistance behavior in high temperature.

  1. Developing a novel technique for absolute measurements of the principal- and second-shock Hugoniots: a benchmark for the impedance-match methods

    Science.gov (United States)

    Gu, Yunjun; Zheng, Jun; Chen, Qifeng; Li, Chengjun; Li, Jiangtao; Chen, Zhiyun

    2017-06-01

    A novel diagnostics configuration was presented for performing the absolute measurements of the principal- and second-shock Hugoniots of the dense gaseous H2+D2 mixtures under multi-shock compression and probing their thermodynamic properties by a joint diagnostics of multi-channel optical pyrometer (MCOP), Doppler Pin System (DPS), and streak camera. This technique allowed the time-resolved optical radiation histories, interface velocity profiles, and time-resolved spectrum of the multi-compressed sample to be simultaneously measured in a single shot. The shock wave velocities and particle velocities under the former two shock compressions can be directly determined with the help of the above multiple detects instead of the impedance-match methods. So, absolute measurements of the principal- and second-shock Hugoniots for pre-compressed dense gaseous H2+D2 mixtures under multi-shock compression can be achieved, which provides a benchmark for the impedance-match measurement technique. Furthermore, the combination of multiple diagnostics also allows different experimental observables to be cross-checked, which reinforces the reliability of the experimental measurements.

  2. Structural and impedance studies of LiNi{sub 0.5}Mn{sub 1.5}O{sub 4} synthesized by sol-gel method

    Energy Technology Data Exchange (ETDEWEB)

    Lobo, Laurel Simon, E-mail: laurelsimonlobo@gmail.com; Rubankumar, A., E-mail: arubankumarvit@gmail.com; Kalainathan, S. [Material Physics Division, School of Advanced Sciences, VIT University, Vellore-63201 Tel: +91 9443107659. Fax: 91 04162242092 (India)

    2016-05-23

    LiNi{sub 0.5}Mn{sub 1.5}O{sub 4} is synthesized by sol-gel method by using succinic acid as chelating agent. X-ray diffraction pattern confirms the material is spinel cubic structure with Fd3m space group. Impedance spectroscopy analysis of spinel LiNi{sub 0.5}Mn{sub 1.5}O{sub 4} was performed under a wide frequency and temperature range of 50 Hz to 5 MHz and 303 K to 783 K respectively. The hopping of the electrons, ionic conductivity and activation energy were analyzed from the relaxation frequency of the imaginary impedance (Z”). The activation energy E{sub a} is calculated from the Arrhenius plots and it is found to be 0.3713 eV, which indicates the existence of oxygen vacancy in the material. Nyquist plot indicates the presence of grain effect in the material and suppression in the grain effect is observed with increasing temperature.

  3. Three-phase short circuit calculation method based on pre-computed surface for doubly fed induction generator

    Science.gov (United States)

    Ma, J.; Liu, Q.

    2018-02-01

    This paper presents an improved short circuit calculation method, based on pre-computed surface to determine the short circuit current of a distribution system with multiple doubly fed induction generators (DFIGs). The short circuit current, injected into power grid by DFIG, is determined by low voltage ride through (LVRT) control and protection under grid fault. However, the existing methods are difficult to calculate the short circuit current of DFIG in engineering practice due to its complexity. A short circuit calculation method, based on pre-computed surface, was proposed by developing the surface of short circuit current changing with the calculating impedance and the open circuit voltage. And the short circuit currents were derived by taking into account the rotor excitation and crowbar activation time. Finally, the pre-computed surfaces of short circuit current at different time were established, and the procedure of DFIG short circuit calculation considering its LVRT was designed. The correctness of proposed method was verified by simulation.

  4. A method for recording resistance changes non-invasively during neuronal depolarization with a view to imaging brain activity with electrical impedance tomography.

    Science.gov (United States)

    Gilad, Ori; Ghosh, Anthony; Oh, Dongin; Holder, David S

    2009-05-30

    Electrical impedance tomography (EIT) is a recently developed medical imaging method which has the potential to produce images of fast neuronal depolarization in the brain. The principle is that current remains in the extracellular space at rest but passes into the intracellular space during depolarization through open ion channels. As current passes into the intracellular space across the capacitance of cell membranes at higher frequencies, applied current needs to be below 100 Hz. A method is presented for its measurement with subtraction of the contemporaneous evoked potentials which occur in the same frequency band. Neuronal activity is evoked by stimulation and resistance is recorded from the potentials resulting from injection of a constant current square wave at 1 Hz with amplitude less than 25% of the threshold for stimulating neuronal activity. Potentials due to the evoked activity and the injected square wave are removed by subtraction. The method was validated with compound action potentials in crab walking leg nerve. Resistance changes of -0.85+/-0.4% (mean+/-SD) occurred which decreased from -0.97+/-0.43% to -0.46+/-0.16% with spacing of impedance current application electrodes from 2 to 8 mm but did not vary significantly with applied currents of 1-10 microA. These tallied with biophysical modelling, and so were consistent with a genuine physiological origin. This method appears to provide a reproducible and artefact free means for recording resistance changes during neuronal activity which could lead to the long-term goal of imaging of fast neural activity in the brain.

  5. Surface Imaging Skin Friction Instrument and Method

    Science.gov (United States)

    Brown, James L. (Inventor); Naughton, Jonathan W. (Inventor)

    1999-01-01

    A surface imaging skin friction instrument allowing 2D resolution of spatial image by a 2D Hilbert transform and 2D inverse thin-oil film solver, providing an innovation over prior art single point approaches. Incoherent, monochromatic light source can be used. The invention provides accurate, easy to use, economical measurement of larger regions of surface shear stress in a single test.

  6. A method of determining surface runoff by

    Science.gov (United States)

    Donald E. Whelan; Lemuel E. Miller; John B. Cavallero

    1952-01-01

    To determine the effects of watershed management on flood runoff, one must make a reliable estimate of how much the surface runoff can be reduced by a land-use program. Since surface runoff is the difference between precipitation and the amount of water that soaks into the soil, such an estimate must be based on the infiltration capacity of the soil.

  7. System and method for free-boundary surface extraction

    KAUST Repository

    Algarni, Marei

    2017-10-26

    A method of extracting surfaces in three-dimensional data includes receiving as inputs three-dimensional data and a seed point p located on a surface to be extracted. The method further includes propagating a front outwardly from the seed point p and extracting a plurality of ridge curves based on the propagated front. A surface boundary is detected based on a comparison of distances between adjacent ridge curves and the desired surface is extracted based on the detected surface boundary.

  8. Use of anisotropic modelling in electrical impedance tomography: description of method and preliminary assessment of utility in imaging brain function in the adult human head.

    Science.gov (United States)

    Abascal, Juan-Felipe P J; Arridge, Simon R; Atkinson, David; Horesh, Raya; Fabrizi, Lorenzo; De Lucia, Marzia; Horesh, Lior; Bayford, Richard H; Holder, David S

    2008-11-01

    Electrical Impedance Tomography (EIT) is an imaging method which enables a volume conductivity map of a subject to be produced from multiple impedance measurements. It has the potential to become a portable non-invasive imaging technique of particular use in imaging brain function. Accurate numerical forward models may be used to improve image reconstruction but, until now, have employed an assumption of isotropic tissue conductivity. This may be expected to introduce inaccuracy, as body tissues, especially those such as white matter and the skull in head imaging, are highly anisotropic. The purpose of this study was, for the first time, to develop a method for incorporating anisotropy in a forward numerical model for EIT of the head and assess the resulting improvement in image quality in the case of linear reconstruction of one example of the human head. A realistic Finite Element Model (FEM) of an adult human head with segments for the scalp, skull, CSF, and brain was produced from a structural MRI. Anisotropy of the brain was estimated from a diffusion tensor-MRI of the same subject and anisotropy of the skull was approximated from the structural information. A method for incorporation of anisotropy in the forward model and its use in image reconstruction was produced. The improvement in reconstructed image quality was assessed in computer simulation by producing forward data, and then linear reconstruction using a sensitivity matrix approach. The mean boundary data difference between anisotropic and isotropic forward models for a reference conductivity was 50%. Use of the correct anisotropic FEM in image reconstruction, as opposed to an isotropic one, corrected an error of 24 mm in imaging a 10% conductivity decrease located in the hippocampus, improved localisation for conductivity changes deep in the brain and due to epilepsy by 4-17 mm, and, overall, led to a substantial improvement on image quality. This suggests that incorporation of anisotropy in

  9. A volume-based method for denoising on curved surfaces

    KAUST Repository

    Biddle, Harry

    2013-09-01

    We demonstrate a method for removing noise from images or other data on curved surfaces. Our approach relies on in-surface diffusion: we formulate both the Gaussian diffusion and Perona-Malik edge-preserving diffusion equations in a surface-intrinsic way. Using the Closest Point Method, a recent technique for solving partial differential equations (PDEs) on general surfaces, we obtain a very simple algorithm where we merely alternate a time step of the usual Gaussian diffusion (and similarly Perona-Malik) in a small 3D volume containing the surface with an interpolation step. The method uses a closest point function to represent the underlying surface and can treat very general surfaces. Experimental results include image filtering on smooth surfaces, open surfaces, and general triangulated surfaces. © 2013 IEEE.

  10. Short-circuit impedance measurement

    DEFF Research Database (Denmark)

    Pedersen, Knud Ole Helgesen; Nielsen, Arne Hejde; Poulsen, Niels Kjølstad

    2003-01-01

    Methods for estimating the short-circuit impedance in the power grid are investigated for various voltage levels and situations. The short-circuit impedance is measured, preferably from naturally occurring load changes in the grid, and it is shown that such a measurement system faces different...... kinds of problems at different locations in the grid. This means that the best measurement methodology changes depending on the location in the grid. Three typical examples with different measurement problems at 400 kV, 132 kV and 400 V voltage level are discussed....

  11. Surface analysis methods in materials science

    CERN Document Server

    Sexton, Brett; Smart, Roger

    1992-01-01

    The idea for this book stemmed from a remark by Philip Jennings of Murdoch University in a discussion session following a regular meeting of the Australian Surface Science group. He observed that a text on surface analysis and applica­ tions to materials suitable for final year undergraduate and postgraduate science students was not currently available. Furthermore, the members of the Australian Surface Science group had the research experience and range of coverage of sur­ face analytical techniques and applications to provide a text for this purpose. A of techniques and applications to be included was agreed at that meeting. The list intended readership of the book has been broadened since the early discussions, particularly to encompass industrial users, but there has been no significant alter­ ation in content. The editors, in consultation with the contributors, have agreed that the book should be prepared for four major groups of readers: - senior undergraduate students in chemistry, physics, metallur...

  12. Impedance plethysmography of thoracic region: impedance cardiography.

    Directory of Open Access Journals (Sweden)

    Deshpande A

    1990-10-01

    Full Text Available Impedance plethysmograms were recorded from thoracic region in 254 normal subjects, 183 patients with coronary artery disease, 391 patients with valvular heart disease and 107 patients with congenital septal disorder. The data in 18 normal subjects and 55 patients showed that basal impedance decreases markedly during exercise in patients with ischaemic heart disease. Estimation of cardiac index by this technique in a group of 99 normal subjects has been observed to be more consistent than that of the stroke volume. Estimation of systolic time index from impedance plethysmograms in 34 normal subjects has been shown to be as reliable as that from electrocardiogram, phonocardiogram and carotid pulse tracing. Changes in the shape of plethysmographic waveform produced by valvular and congenital heart diseases are briefly described and the role of this technique in screening cardiac patients has been highlighted.

  13. Surface control alloy substrates and methods of manufacture therefor

    Energy Technology Data Exchange (ETDEWEB)

    Fritzemeier, Leslie G. (Mendon, MA); Li, Qi (Marlborough, MA); Rupich, Martin W. (Framingham, MA); Thompson, Elliott D. (Coventry, RI); Siegal, Edward J. (Malden, MA); Thieme, Cornelis Leo Hans (Westborough, MA); Annavarapu, Suresh (Brookline, MA); Arendt, Paul N. (Los Alamos, NM); Foltyn, Stephen R. (Los Alamos, NM)

    2004-05-04

    Methods and articles for controlling the surface of an alloy substrate for deposition of an epitaxial layer. The invention includes the use of an intermediate layer to stabilize the substrate surface against oxidation for subsequent deposition of an epitaxial layer.

  14. Trainable Methods for Surface Natural Language Generation

    OpenAIRE

    Ratnaparkhi, Adwait

    2000-01-01

    We present three systems for surface natural language generation that are trainable from annotated corpora. The first two systems, called NLG1 and NLG2, require a corpus marked only with domain-specific semantic attributes, while the last system, called NLG3, requires a corpus marked with both semantic attributes and syntactic dependency information. All systems attempt to produce a grammatical natural language phrase from a domain-specific semantic representation. NLG1 serves a baseline syst...

  15. Impedance-Based Non-Destructive Testing Method Combined with Unmanned Aerial Vehicle for Structural Health Monitoring of Civil Infrastructures

    Directory of Open Access Journals (Sweden)

    Wongi S Na

    2016-12-01

    Full Text Available Unmanned aerial vehicles (UAVs, commonly known as drones, are a rising topic in remote sensing technologies for structural health monitoring. With technology advancement in cameras, the visual inspection method using drones is gaining much attention in the field of civil engineering. However, although visual inspection methods are feasible for finding cracks in structures, the limitations of image processing for finding internal damage or small defects cannot be ignored. To overcome this problem, a possible application concept of UAV, combined with a vibration-based non-destructive health monitoring method, is proposed. The idea is for the drone to temporarily attach the piezoelectric transducer onto a specific region where excitation and data acquisition occurs simultaneously. This eliminates the need for a structure to be covered with hundreds of sensors for monitoring, as this concept uses a single piezoelectric transducer for monitoring a structure. The proposed work offers new areas of research by converging UAV with a vibration-based method, as associated problems are required to be solved.

  16. Segmental bioelectrical impedance analysis: an update.

    Science.gov (United States)

    Ward, Leigh C

    2012-09-01

    Bioelectrical impedance analysis is a popular, noninvasive and practical method for assessment of body composition. The last decade has seen the development of impedance analyzers designed to assess the composition of body segments as well as the whole body. This review outlines the theoretical basis for segmental impedance analysis, validity and use in practice. Segmental impedance analysis tends to underestimate fat-free mass and overestimate fat mass when compared to reference techniques, although the magnitude of these differences can be small. Performance is improved with population-specific prediction equations; algorithms in-built into instrument firmware should not be relied upon. Prediction of whole-body composition from the sum of the individual segments, although theoretically preferable, shows little advantage over whole body wrist to ankle impedance approaches. Prediction of appendicular skeletal muscle mass, although promising, requires further research. The use of measured impedance data directly as indices of composition, rather than for prediction, has not found extensive application in nutritional research despite its success in other fields. Segmental bioimpedance techniques have advanced substantially in recent years due to availability of simple-to-use analyzers and simplified measurement protocols. The method has been well validated and increasingly adopted in nutritional and clinical practice. Segmental impedance, like conventional whole body impedance approaches, provides indirect prediction of body composition whose accuracy is yet to achieve that of reference techniques such as magnetic reference imaging. This lack of accuracy, however, is outweighed by the method's practicality of use in many settings.

  17. Tracking of electrochemical impedance of batteries

    Science.gov (United States)

    Piret, H.; Granjon, P.; Guillet, N.; Cattin, V.

    2016-04-01

    This paper presents an evolutionary battery impedance estimation method, which can be easily embedded in vehicles or nomad devices. The proposed method not only allows an accurate frequency impedance estimation, but also a tracking of its temporal evolution contrary to classical electrochemical impedance spectroscopy methods. Taking into account constraints of cost and complexity, we propose to use the existing electronics of current control to perform a frequency evolutionary estimation of the electrochemical impedance. The developed method uses a simple wideband input signal, and relies on a recursive local average of Fourier transforms. The averaging is controlled by a single parameter, managing a trade-off between tracking and estimation performance. This normalized parameter allows to correctly adapt the behavior of the proposed estimator to the variations of the impedance. The advantage of the proposed method is twofold: the method is easy to embed into a simple electronic circuit, and the battery impedance estimator is evolutionary. The ability of the method to monitor the impedance over time is demonstrated on a simulator, and on a real Lithium ion battery, on which a repeatability study is carried out. The experiments reveal good tracking results, and estimation performance as accurate as the usual laboratory approaches.

  18. Analysis of the willow root system by electrical impedance spectroscopy.

    Science.gov (United States)

    Cao, Yang; Repo, Tapani; Silvennoinen, Raimo; Lehto, Tarja; Pelkonen, Paavo

    2011-01-01

    Information on plant roots is increasingly needed for understanding and managing plants under various environmental conditions, including climate change. Several methods have been developed to study fine roots but they are either destructive or cumbersome, or may not be suitable for studies of fine root functionality. Electrical impedance, resistance, and capacitance have been proposed as possible non-destructive measures for studying roots. Their use is limited by a lack of knowledge concerning the electrical circuit of the system. Electrical impedance spectroscopy (EIS) was used for hydroponically raised willows (Salix schwerinii) to estimate the root system size. The impedance spectra were investigated in three experimental set-ups and the corresponding appropriate lumped models were formulated. The fit of the proposed lumped models with the measured impedance spectra data was good. The model parameters were correlated with the contact area of the roots and/or stems raised in the hydroponic solution. The EIS method proved a useful non-destructive method for assessing root surface area. This work may be considered to be a new methodological contribution to understanding root systems and their functions in a non-destructive manner.

  19. BODY COMPOSITION OF YOUNG PEOPLE AGED 17-18 YEARS, PRACTICING AND NOT PRACTICING SWIMMING, WITH THE USE OF THE BIOELECTRICAL IMPEDANCE METHOD

    Directory of Open Access Journals (Sweden)

    Jendrysek Marek

    2015-11-01

    Full Text Available Purpose: Body composition evaluation of youth aged 17-18 of a different physical activity with the help of bioelectric impedance method. Material and Methods: 18 boys practicing swimming and 19 boys not practicing it took part in the study, making up a control group. Height, weight, BMI, lean body mass, the content of fat and water, Rohr factor were evaluated. Non-parametric Mann-Whitney test has been used to evaluate the differences in the range of the tissue components between the two groups. Results: Statistically significant differences were found on the p<0,05 level in % fat content. Mean body weight in experimental group was 71.5 kg, while in control group it was 69.4 kg. Minimum and maximum weight in group of swimming-practicing persons was: 56.6-92.2 kg. Increased body weight in the group of swimmers can result from greater amount of active tissue in this group compared with persons of low physical activity. Proportionally, it amounted to 64.3 kg and 61.3 kg. In the tested groups, minimal and maximal values of amount of active tissue proportionately amounted to: 54.1-78 and 49.5-72,3 kg. Conclusions: Physical activity modifies body composition. Active lifestyle is one of the methods for prevention of overweight and obesity.

  20. Body composition of young people aged 17-18 years, practicing and not practicing swimming, with the use of the bioelectrical impedance method

    Directory of Open Access Journals (Sweden)

    Marek Jendrysek

    2015-11-01

    Full Text Available Purpose: Body composition evaluation of youth aged 17-18 of a different physical activity with the help of bioelectric impedance method. Material and Methods: 18 boys practicing swimming and 19 boys not practicing it took part in the study, making up a control group. Height, weight, BMI, lean body mass, the content of fat and water, Rohr factor were evaluated. Non-parametric Mann-Whitney test has been used to evaluate the differences in the range of the tissue components between the two groups. Results: Statistically significant differences were found on the p<0,05 level in % fat content. Mean body weight in experimental group was 71.5 kg, while in control group it was 69.4 kg. Minimum and maximum weight in group of swimming-practicing persons was: 56.6-92.2 kg. Increased body weight in the group of swimmers can result from greater amount of active tissue in this group compared with persons of low physical activity. Proportionally, it amounted to 64.3 kg and 61.3 kg. In the tested groups, minimal and maximal values of amount of active tissue proportionately amounted to: 54.1-78 and 49.5-72,3 kg. Conclusions: Physical activity modifies body composition. Active lifestyle is one of the methods for prevention of overweight and obesity.

  1. Bioelectrical impedance is an accurate method to assess body composition in obese but not severely obese adolescents.

    Science.gov (United States)

    Verney, Julien; Metz, Lore; Chaplais, Elodie; Cardenoux, Charlotte; Pereira, Bruno; Thivel, David

    2016-07-01

    The aim of this study was to compare total and segmental body composition results between bioimpedance analysis (BIA) and dual x-ray absorptiometry (DXA) scan and to test the reproducibility of BIA in obese adolescents. We hypothesized that BIA offers an accurate and reproducible method to assess body composition in adolescents with obesity. Whole-body and segmental body compositions were assessed by BIA (Tanita MC-780) and DXA (Hologic) among 138 (110 girls and 28 boys) obese adolescents (Tanner stage 3-5) aged 14±1.5years. The BIA analysis was replicated on 3 identical occasions in 32 participants to test the reproducibility of the methods. Whole-body fat mass percentage was significantly higher using the BIA method compared with DXA (40.6±7.8 vs 38.8±4.9%, Pobese adolescents, with however a loss of correlation between BIA and DXA with increasing body fat; its validity remains uncertain for segmental analysis among obese youth. Copyright © 2016 Elsevier Inc. All rights reserved.

  2. Fractional Order Element Based Impedance Matching

    KAUST Repository

    Radwan, Ahmed Gomaa

    2014-06-24

    Disclosed are various embodiments of methods and systems related to fractional order element based impedance matching. In one embodiment, a method includes aligning a traditional Smith chart (|.alpha.|=1) with a fractional order Smith chart (|.alpha.|.noteq.1). A load impedance is located on the traditional Smith chart and projected onto the fractional order Smith chart. A fractional order matching element is determined by transitioning along a matching circle of the fractional order Smith chart based at least in part upon characteristic line impedance. In another embodiment, a system includes a fractional order impedance matching application executed in a computing device. The fractional order impedance matching application includes logic that obtains a first set of Smith chart coordinates at a first order, determines a second set of Smith chart coordinates at a second order, and determines a fractional order matching element from the second set of Smith chart coordinates.

  3. Nonsynchronous Noncommensurate Impedance Transformers

    DEFF Research Database (Denmark)

    Zhurbenko, Vitaliy; Kim, K

    2012-01-01

    Nonsynchronous noncommensurate impedance transformers consist of a combination of two types of transmission lines: transmission lines with a characteristic impedance equal to the impedance of the source, and transmission lines with a characteristic impedance equal to the load. The practical...... advantage of such transformers is that they can be constructed using sections of transmission lines with a limited variety of characteristic impedances. These transformers also provide comparatively compact size in applications where a wide transformation ratio is required. This paper presents the data...... which allows to estimate the achievable total electrical length and in-band reflection coefficient for transformers consisting of up to twelve transmission line sections in the range of transformation ratios r = 1:5 to 10 and bandwidth ratios  = 2 to 20. This data is obtained using wave transmission...

  4. Improved adhesion of superhydrophobic layer on metal surfaces via one step spraying method

    Directory of Open Access Journals (Sweden)

    Wael I. El Dessouky

    2017-03-01

    Full Text Available Superhydrophobic metal substrates have been fabricated by a simple spraying method. The processes of decreasing surface free energy and increasing surface roughness have been accomplished in one step via the addition of functionalized silica (silica nano particles with octyltriethoxysilane to adhesive polymer. The method is simple, cost-effective and can be applied on the large industrial scale. Scanning electron microscopy (SEM was used for surface morphology analysis, showing the roughness produced by surface treatment. The wettability of the micro-nano silica film varied from hydrophilicity (water contact angle 88° to superhydrophobicity (water contact angle 156.9°, while sliding contact angles dramatically decreased (<5° by adding Functionalized silica and/or adhesive polymer. Roughness increased with silica increment which improves the wettability. The coatings were electrochemically characterized by electrochemical impedance spectroscopy (EIS and Tafel polarization curves; it was found that both systems had good performance against corrosion in 3.5% sodium chloride solution. Furthermore, the stability of the coated layer on copper substrate was investigated.

  5. Surface renewal method for estimating sensible heat flux | Mengistu ...

    African Journals Online (AJOL)

    For short canopies, latent energy flux may be estimated using a shortened surface energy balance from measurements of sensible and soil heat flux and the net irradiance at the surface. The surface renewal (SR) method for estimating sensible heat, latent energy, and other scalar fluxes has the advantage over other ...

  6. Method for treatment of a surface area of steel

    NARCIS (Netherlands)

    Bhowmik, S.; Aaldert, P.J.

    2009-01-01

    The invention relates to a method for treatment of a surface area of steel by polishing said surface area and performing a plasma treatment of said surface area wherein the plasma treatment is performed at at least atmospheric conditions and wherein the plasma treatment is carried out at a power of

  7. Wave impedance retrieving via Bloch modes analysis

    DEFF Research Database (Denmark)

    Andryieuski, Andrei; Ha, S.; Sukhorukov, A.

    2011-01-01

    -ciples violation, like antiresonance behaviour with Im(ε) wave impedances by the surface and volume aver-aging of the electromagnetic field...... of the Bloch mode, respectively. Case studies prove that our ap-proach can determine material and wave effective parameters of lossy and lossless metamaterials. In some examples when the passivity is violated we made further analysis and showed that this is due to the failure of concept of impedance retrieving...

  8. Applying isotope methods in flowing surface waters

    International Nuclear Information System (INIS)

    Mook, W.G.

    1976-01-01

    The most frequent application of natural or environmental isotopes to investigate surface water is as tracer. Especially the natural variations in the 18 O/ 16 O ratio in rainfall are traced in streams and rivers. The isotopes deuterium, 13 C and 14 C enable refined applications such as the investigation of geochemical processes in waters. 18 O analyses are fairly fast (20 samples per day can be carried out) and require little water (1 to 10 ml). Therefore, the natural variations in the 18 O/ 16 O ratio of water are treated. There is a certain connection between the 18 O/ 16 O and D/H ratios in rainfall waters. 18 O analyses are somewhat easier to perform so that this technique is generally preferred. Additional D analyses are of great use in detecting geochemical processes, e.g. evaporation. Although tritium is still an important agent in hydrological studies, the concentration variations in nature are now lower than for 18 O compared to the usual experimental error. Furthermore, they are not so important geochemically. Accurate tritium measurements require relatively much time (1 or 2 analyses per day), are expensive (50 DM to 150 DM) and require more material (10 to 500 ml water), depending on the desired accuracy. The stable and radioactive carbon isotopes are mainly used in special cases to study certain geochemical processes. (orig./HK) [de

  9. Impedance and Collective Effects

    CERN Document Server

    Metral, E; Rumolo, R; Herr, W

    2013-01-01

    This document is part of Subvolume C 'Accelerators and Colliders' of Volume 21 'Elementary Particles' of Landolt-Börnstein - Group I 'Elementary Particles, Nuclei and Atoms'. It contains the Chapter '4 Impedance and Collective Effects' with the content: 4 Impedance and Collective Effects Introduction 4.1 Space Charge 4.2 Wake Fields and Impedances 4.3 Coherent Instabilities 4.4 Landau Damping 4.5 Two-Stream Effects (Electron Cloud and Ions) 4.6 Beam-Beam Effects 4.7 Numerical Modelling

  10. Chemical method for producing smooth surfaces on silicon wafers

    Science.gov (United States)

    Yu, Conrad

    2003-01-01

    An improved method for producing optically smooth surfaces in silicon wafers during wet chemical etching involves a pre-treatment rinse of the wafers before etching and a post-etching rinse. The pre-treatment with an organic solvent provides a well-wetted surface that ensures uniform mass transfer during etching, which results in optically smooth surfaces. The post-etching treatment with an acetic acid solution stops the etching instantly, preventing any uneven etching that leads to surface roughness. This method can be used to etch silicon surfaces to a depth of 200 .mu.m or more, while the finished surfaces have a surface roughness of only 15-50 .ANG. (RMS).

  11. LHC Bellows Impedance Calculations

    CERN Document Server

    Dyachkov, M

    1997-01-01

    To compensate for thermal expansion the LHC ring has to accommodate about 2500 bellows which, together with beam position monitors, are the main contributors to the LHC broad-band impedance budget. In order to reduce this impedance to an acceptable value the bellows have to be shielded. In this paper we compare different designs proposed for the bellows and calculate their transverse and longitudinal wakefields and impedances. Owing to the 3D geometry of the bellows, the code MAFIA was used for the wakefield calculations; when possible the MAFIA results were compared to those obtained with ABCI. The results presented in this paper indicate that the latest bellows design, in which shielding is provided by sprung fingers which can slide along the beam screen, has impedances smaller tha those previously estimated according to a rather conservative scaling of SSC calculations and LEP measurements. Several failure modes, such as missing fingers and imperfect RF contact, have also been studied.

  12. Impedance and component heating

    CERN Document Server

    Métral, E; Mounet, N; Pieloni, T; Salvant, B

    2015-01-01

    The impedance is a complex function of frequency, which represents, for the plane under consideration (longitudinal, horizontal or vertical), the force integrated over the length of an element, from a “source” to a “test” wave, normalized by their charges. In general, the impedance in a given plane is a nonlinear function of the test and source transverse coordinates, but it is most of the time sufficient to consider only the first few linear terms. Impedances can influence the motion of trailing particles, in the longitudinal and in one or both transverse directions, leading to energy loss, beam instabilities, or producing undesirable secondary effects such as excessive heating of sensitive components at or near the chamber wall, called beam-induced RF heating. The LHC performance limitations linked to impedances encountered during the 2010-2012 run are reviewed and the currently expected situation during the HL-LHC era is discussed.

  13. Electrical Impedance Tomography Technology

    Data.gov (United States)

    National Aeronautics and Space Administration — The goal for the Electrical Impedance Tomography Technology (EITT) project is to develop a reliable portable, lightweight device providing two-dimensional...

  14. ROUGHNESS ON WOOD SURFACES AND ROUGHNESS MEASUREMENT METHODS

    Directory of Open Access Journals (Sweden)

    İsmail Aydın

    2003-04-01

    Full Text Available Some visual characteristics of wood such as color, pattern and texture determine the quality of manufactured products. Surface properties of wood material are important both in production and marketing after production. Initial studies related to the roughness of wood surface were begun in early 1950’s. However, no general agreed standardization can not have been developed for wood surfaces. Surface roughness of wood is function of the production process, product type and the natural anatomical properties of wood. Contact and non-contact tracing methods are used to measure of wood surface roughness. Surface roughness also affects the gluability and wettability of wood surfaces. The success in finishing also depends on the surface roughness of wood.

  15. The LEP impedance model

    Energy Technology Data Exchange (ETDEWEB)

    Zotter, B. [European Organization for Nuclear Research, Geneva (Switzerland)

    1996-08-01

    This report describes a number of measurements and computations of the impedance of the Large Electron Positron collider LEP at CERN. The work has been performed over several years, together with D. Brandt, K. Cornelis, A. Hofmann, G. Sabbi and many others. The agreement between measurements of single bunch instabilities on the machine and computer simulations is in general excellent and gives confidence in the impedance model used. (author)

  16. Formation of Reflecting Surfaces Based on Spline Methods

    Science.gov (United States)

    Zamyatin, A. V.; Zamyatina, E. A.

    2017-11-01

    The article deals with problem of reflecting barriers surfaces generation by spline methods. The cases of reflection when a geometric model is applied are considered. The surfaces of reflecting barriers are formed in such a way that they contain given points and the rays reflected at these points and hit at the defined points of specified surface. The reflecting barrier surface is formed by cubic splines. It enables a comparatively simple implementation of proposed algorithms in the form of software applications. The algorithms developed in the article can be applied in architecture and construction design for reflecting surface generation in optics and acoustics providing the geometrical model of reflex processes is used correctly.

  17. System and method for extracting a sample from a surface

    Science.gov (United States)

    Van Berkel, Gary; Covey, Thomas

    2015-06-23

    A system and method is disclosed for extracting a sample from a sample surface. A sample is provided and a sample surface receives the sample which is deposited on the sample surface. A hydrophobic material is applied to the sample surface, and one or more devices are configured to dispense a liquid on the sample, the liquid dissolving the sample to form a dissolved sample material, and the one or more devices are configured to extract the dissolved sample material from the sample surface.

  18. Electrical impedance tomography: topology optimization

    International Nuclear Information System (INIS)

    Miranda, Lenine Campos

    2013-01-01

    The Electrical Impedance Tomography (EIT) is a study of body parts who use electric current. Is studied through computers resistance or conductivity of these parts, producing an image used for medical diagnosis. A body is wrapped in a blanket placed with small electrodes and receivers of electric current, potential difference. Based on data obtained from a series of measurements at the electrodes, one by one, sending and receiving, you can perform a numerical phantom, where each 'voxel' of the image formed computationally represents the impedance of biological tissue. In Brazil, studies on electrical impedance tomography (EIT) has not yet started. Such equipment are measured tensions - potential difference - between each electrode / sensor one by one, as a way to Simple Combinatorial Analysis. The sequence and the way it is measured strains are in the final image quality. Finite Element Method Interactive, whose algorithm is based on Dialectical Method. We use an initial function with the objective of maximizing the data quantitatively, for better qualitative analysis. Topology Optimization methods are used to improve the image reconstruction. Currently the study is quite primitive related to the theory that shows how to power the new science studied. The high quality images requires a difficulty in obtaining. This work is not intended for detailed for analysis in any tissue or organ specific, but in general terms. And the formation of the 2D image. 3D need a reconstructor to part. (author)

  19. Evaluation of surface sampling method performance for Bacillus Spores on clean and dirty outdoor surfaces.

    Energy Technology Data Exchange (ETDEWEB)

    Wilson, Mollye C.; Einfeld, Wayne; Boucher, Raymond M.; Brown, Gary Stephen; Tezak, Matthew Stephen

    2011-06-01

    Recovery of Bacillus atrophaeous spores from grime-treated and clean surfaces was measured in a controlled chamber study to assess sampling method performance. Outdoor surfaces investigated by wipe and vacuum sampling methods included stainless steel, glass, marble and concrete. Bacillus atrophaeous spores were used as a surrogate for Bacillus anthracis spores in this study designed to assess whether grime-coated surfaces significantly affected surface sampling method performance when compared to clean surfaces. A series of chamber tests were carried out in which known amounts of spores were allowed to gravitationally settle onto both clean and dirty surfaces. Reference coupons were co-located with test coupons in all chamber experiments to provide a quantitative measure of initial surface concentrations of spores on all surfaces, thereby allowing sampling recovery calculations. Results from these tests, carried out under both low and high humidity conditions, show that spore recovery from grime-coated surfaces is the same as or better than spore recovery from clean surfaces. Statistically significant differences between method performance for grime-coated and clean surfaces were observed in only about half of the chamber tests conducted.

  20. Prediction of fat-free mass by bioelectrical impedance analysis in older adults from developing countries: a cross-validation study using the deuterium dilution method

    International Nuclear Information System (INIS)

    Mateo, H. Aleman; Romero, J. Esparza; Valencia, M.E.

    2010-01-01

    Objective: Several limitations of published bioelectrical impedance analysis (BIA) equations have been reported. The aims were to develop in a multiethnic, elderly population a new prediction equation and cross- validate it along with some published BIA equations for estimating fat-free mass using deuterium oxide dilution as the reference method. Design and setting: Cross-sectional study of elderly from five developing countries. Methods: Total body water (TBW) measured by deuterium dilution was used to determine fat-free mass (FFM) in 383 subjects. Anthropometric and BIA variables were also measured. Only 377 subjects were included for the analysis, randomly divided into development and cross-validation groups after stratified by gender. Stepwise model selection was used to generate the model and Bland Altman analysis was used to test agreement. Results: FFM = 2.95 - 3.89 (Gender) + 0.514 (Ht2/Z) + 0.090 (Waist) + 0.156 (Body weight). The model fit parameters were an R2, total F-Ratio, and the SEE of 0.88, 314.3, and 3.3, respectively. None of the published BIA equations met the criteria for agreement. The new BIA equation underestimated FFM by just 0.3 kg in the cross-validation sample. The mean of the difference between FFM by TBW and the new BIA equation were not significantly different; 95% of the differences were between the limits of agreement of -6.3 to 6.9 kg of FFM. There was no significant association between the mean of the differences and their averages (r= 0.008 and p= 0.2). Conclusions:This new BIA equation offers a valid option compared with some of the current published BIA equations to estimate FFM in elderly subjects from five developing countries. (Authors)

  1. Alternative methods to model frictional contact surfaces using NASTRAN

    Science.gov (United States)

    Hoang, Joseph

    1992-01-01

    Elongated (slotted) holes have been used extensively for the integration of equipment into Spacelab racks. In the past, this type of interface has been modeled assuming that there is not slippage between contact surfaces, or that there is no load transfer in the direction of the slot. Since the contact surfaces are bolted together, the contact friction provides a load path determined by the normal applied force (bolt preload) and the coefficient of friction. Three alternate methods that utilize spring elements, externally applied couples, and stress dependent elements are examined to model the contacted surfaces. Results of these methods are compared with results obtained from methods that use GAP elements and rigid elements.

  2. AC impedance technique in PEM fuel cell diagnosis - A review

    Energy Technology Data Exchange (ETDEWEB)

    Yuan, Xiaozi; Wang, Haijiang; Colin Sun, Jian; Zhang, Jiujun [Institute for Fuel Cell Innovation, National Research Council (Canada)

    2007-12-15

    Because the AC impedance technique, also known as electrochemical impedance spectroscopy (EIS), is being utilized by more and more researchers in proton exchange membrane (PEM) fuel cell studies, the technique has developed into a primary tool in such research. In this paper the recent work on PEM fuel cells using the AC impedance technique is reviewed. Both in situ and ex situ impedance measurements are discussed, with primary focus on the in situ measurements. Within the domain of in situ studies, various methods for measuring the impedance of a PEM fuel cell are examined, and typical impedance spectra in several common scenarios are presented. Representative applications of the AC impedance technique in PEM fuel cell research are also discussed. Finally, the necessity of a time domain rapid AC impedance technique is briefly discussed. (author)

  3. RHIC ABORT KICKER WITH REDUCED COUPLING IMPEDANCE

    International Nuclear Information System (INIS)

    HAHN, H.; DAVINO, D.

    2002-01-01

    Kicker magnets typically represent the most important contributors to the transverse impedance budget of accelerators and storage rings. Methods of reducing the impedance value of the SNS extraction kicker presently under construction and, in view of a future performance upgrade, that of the RHIC abort kicker have been thoroughly studied at this laboratory. In this paper, the investigation of a potential improvement from using ferrite different from the BNL standard CMD5005 is reported. Permeability measurements of several ferrite types have been performed. Measurements on two kicker magnets using CMD5005 and C2050 suggest that the impedance of a magnet without external resistive damping, such as the RHIC abort kicker, would benefit

  4. Electrical Impedance Measurements of PZT Nanofiber Sensors

    Directory of Open Access Journals (Sweden)

    Richard Galos

    2017-01-01

    Full Text Available Electrical impedance measurements of PZT nanofiber sensors were performed using a variety of methods over a frequency spectrum ranging from DC to 1.8 GHz. The nanofibers formed by electrospinning with diameters ranging from 10 to 150 nm were collected and integrated into sensors using microfabrication techniques. Special matching circuits with ultrahigh input impedance were fabricated to produce low noise, measurable sensor outputs. Material properties including resistivity and dielectric constant are derived from the impedance measurements. The resulting material properties are also compared with those of individual nanofibers being tested using conductive AFM and Scanning Conductive Microscopy.

  5. Method for Surface Scanning in Medical Imaging and Related Apparatus

    DEFF Research Database (Denmark)

    2015-01-01

    A method and apparatus for surface scanning in medical imaging is provided. The surface scanning apparatus comprises an image source, a first optical fiber bundle comprising first optical fibers having proximal ends and distal ends, and a first optical coupler for coupling an image from the image...

  6. A continuous surface reconstruction method on point cloud captured from a 3D surface photogrammetry system

    Energy Technology Data Exchange (ETDEWEB)

    Liu, Wenyang [Department of Bioengineering, University of California, Los Angeles, California 90095 (United States); Cheung, Yam; Sabouri, Pouya; Arai, Tatsuya J.; Sawant, Amit [Department of Radiation Oncology, University of Texas Southwestern, Dallas, Texas 75390 (United States); Ruan, Dan, E-mail: druan@mednet.ucla.edu [Department of Bioengineering, University of California, Los Angeles, California 90095 and Department of Radiation Oncology, University of California, Los Angeles, California 90095 (United States)

    2015-11-15

    Purpose: To accurately and efficiently reconstruct a continuous surface from noisy point clouds captured by a surface photogrammetry system (VisionRT). Methods: The authors have developed a level-set based surface reconstruction method on point clouds captured by a surface photogrammetry system (VisionRT). The proposed method reconstructs an implicit and continuous representation of the underlying patient surface by optimizing a regularized fitting energy, offering extra robustness to noise and missing measurements. By contrast to explicit/discrete meshing-type schemes, their continuous representation is particularly advantageous for subsequent surface registration and motion tracking by eliminating the need for maintaining explicit point correspondences as in discrete models. The authors solve the proposed method with an efficient narrowband evolving scheme. The authors evaluated the proposed method on both phantom and human subject data with two sets of complementary experiments. In the first set of experiment, the authors generated a series of surfaces each with different black patches placed on one chest phantom. The resulting VisionRT measurements from the patched area had different degree of noise and missing levels, since VisionRT has difficulties in detecting dark surfaces. The authors applied the proposed method to point clouds acquired under these different configurations, and quantitatively evaluated reconstructed surfaces by comparing against a high-quality reference surface with respect to root mean squared error (RMSE). In the second set of experiment, the authors applied their method to 100 clinical point clouds acquired from one human subject. In the absence of ground-truth, the authors qualitatively validated reconstructed surfaces by comparing the local geometry, specifically mean curvature distributions, against that of the surface extracted from a high-quality CT obtained from the same patient. Results: On phantom point clouds, their method

  7. Facile fabrication of superhydrophobic surface with excellent mechanical abrasion and corrosion resistance on copper substrate by a novel method.

    Science.gov (United States)

    Su, Fenghua; Yao, Kai

    2014-06-11

    A novel method for controllable fabrication of a superhydrophobic surface with a water contact angle of 162 ± 1° and a sliding angle of 3 ± 0.5° on copper substrate is reported in this Research Article. The facile and low-cost fabrication process is composed from the electrodeposition in traditional Watts bath and the heat-treatment in the presence of (heptadecafluoro-1,1,2,2-tetradecyl) triethoxysilane (AC-FAS). The superhydrophobicity of the fabricated surface results from its pine-cone-like hierarchical micro-nanostructure and the assembly of low-surface-energy fluorinated components on it. The superhydrophobic surface exhibits high microhardness and excellent mechanical abrasion resistance because it maintains superhydrophobicity after mechanical abrasion against 800 grit SiC sandpaper for 1.0 m at the applied pressure of 4.80 kPa. Moreover, the superhydrophobic surface has good chemical stability in both acidic and alkaline environments. The potentiodynamic polarization and electrochemical impedance spectroscopy test shows that the as-prepared superhydrophobic surface has excellent corrosion resistance that can provide effective protection for the bare Cu substrate. In addition, the as-prepared superhydrophobic surface has self-cleaning ability. It is believed that the facile and low-cost method offer an effective strategy and promising industrial applications for fabricating superhydrophobic surfaces on various metallic materials.

  8. Measuring the multi-frequency electrical impedance of the mouse gastrocnemius muscle using a tetrapolar technique

    Science.gov (United States)

    Li, J.; Fogerson, P. M.; Rutkove, S. B.

    2010-04-01

    Electrical impedance methods can be used to evaluate and monitor neuromuscular disease states. Recently, we have applied tetrapolar surface electrical impedance methods to the gastrocnemius muscle of the rat for this purpose and substantial changes in the impedance parameters after sciatic nerve crush can be identified. In order to be able to study additional animal models of nerve and muscle disease, however, it would highly desirable to be able to perform such impedance measurements in the mouse. Yet the small size of the mouse presents a substantial technical challenge. In this study, we evaluate a basic approach for performing such measurements. A series of thin, stainless steel strip electrodes affixed to the gastrocnemius and interfaced via a separate connector to the Imp SFB7® (Impedimed, Inc), provided an effective means for obtaining impedance data in the 20-500 kHz range. After two weeks, test-retest reproducibility was good, with intra-class correlation coefficients as high 0.84 and variability as low as 12.86 ± 6.18% in the 15 mice studied. Using this approach, it may now be possible to study impedance changes in a variety of mouse models of neuromuscular disease, including amyotrophic lateral sclerosis, spinal muscular atrophy, muscular dystrophy and Charcot-Marie-Tooth disease.

  9. Interferometric method for measuring high velocities of diffuse surfaces

    International Nuclear Information System (INIS)

    Maron, Y.

    1978-01-01

    An interferometric method for measuring the displacement of diffuse surfaces moving with velocities of a few microsecond is presented. The method utilizes the interference between two light beams reflected from a constant area of the moving surface at two different angles. It enables the detection of high rate velocity variations. Light source of a fairly low temporal coherence and power around 100mW is needed. (author)

  10. A continuous surface reconstruction method on point cloud captured from a 3D surface photogrammetry system.

    Science.gov (United States)

    Liu, Wenyang; Cheung, Yam; Sabouri, Pouya; Arai, Tatsuya J; Sawant, Amit; Ruan, Dan

    2015-11-01

    To accurately and efficiently reconstruct a continuous surface from noisy point clouds captured by a surface photogrammetry system (VisionRT). The authors have developed a level-set based surface reconstruction method on point clouds captured by a surface photogrammetry system (VisionRT). The proposed method reconstructs an implicit and continuous representation of the underlying patient surface by optimizing a regularized fitting energy, offering extra robustness to noise and missing measurements. By contrast to explicit/discrete meshing-type schemes, their continuous representation is particularly advantageous for subsequent surface registration and motion tracking by eliminating the need for maintaining explicit point correspondences as in discrete models. The authors solve the proposed method with an efficient narrowband evolving scheme. The authors evaluated the proposed method on both phantom and human subject data with two sets of complementary experiments. In the first set of experiment, the authors generated a series of surfaces each with different black patches placed on one chest phantom. The resulting VisionRT measurements from the patched area had different degree of noise and missing levels, since VisionRT has difficulties in detecting dark surfaces. The authors applied the proposed method to point clouds acquired under these different configurations, and quantitatively evaluated reconstructed surfaces by comparing against a high-quality reference surface with respect to root mean squared error (RMSE). In the second set of experiment, the authors applied their method to 100 clinical point clouds acquired from one human subject. In the absence of ground-truth, the authors qualitatively validated reconstructed surfaces by comparing the local geometry, specifically mean curvature distributions, against that of the surface extracted from a high-quality CT obtained from the same patient. On phantom point clouds, their method achieved submillimeter

  11. Experimental study of the course of threshold current, voltage and electrode impedance during stepwise stimulation from the skin surface to the human cortex.

    Science.gov (United States)

    Szelényi, Andrea; Journée, Henricus Louis; Herrlich, Simon; Galistu, Gianni M; van den Berg, Joris; van Dijk, J Marc C

    2013-07-01

    Transcranial electric stimulation as used during intraoperative neurostimulation is dependent on electrode and skull impedances. Threshold currents, voltages and electrode impedances were evaluated with electrical stimulation at 8 successive layers between the skin and the cerebral cortex. Data of 10 patients (6f, 53 ± 11 years) were analyzed. Motor evoked potentials were elicited by constant current stimulation with corkscrew type electrodes (CS) at C3 and C4 in line with standard transcranial electric stimulation. A monopolar anodal ball tip shaped probe was used for all other measurements being performed at the level of the skin, dura and cortex, as well as within the skull by stepwise performed burr holes close to C3 resp. C4. Average stimulation intensity, corresponding voltage and impedance for muscle MEPs at current motor threshold (CMT) were recorded: CS 54 ± 23 mA (mean ± SD), 38 ± 21 V, 686 ± 146 Ω; with the monopolar probe on skin 55 ± 28 mA, 100 ± 44 V, 1911 ± 683 Ω and scalp 59 ± 32 mA, 56 ± 28 V, 1010 ± 402 Ω; within the skull bone: outer compact layer 33 ± 23 mA, 91 ± 53 V, 3734 ± 2793 Ω; spongiform layer 33 ± 23 mA, 70 ± 44 V, 2347 ± 1327 Ω; inner compact layer (ICL) 28 ± 19 mA, 48 ± 23 V, 2103 ± 1498 Ω; on dura 25 ± 12 mA, 17 ± 12 V, 643 ± 244 Ω and cortex 14 ± 6 mA, 11 ± 5 V, 859 ± 300 Ω. CMTs were only significantly different for CS (P = 0.02) and for the monopolar probe between the cortex and ICL (P = 0.03), scalp (P = 0.01) or skin (P = 0.01) and between ICL and CS (P ≤ 0.01) or skin (P ≤ 0.01). The mean stimulation current of the CMT along the extracranial to intracranial anodal trajectory followed a stepwise reduction. VMT was strongly dependent on electrode impedance. CMT within the skull layers was noted to have relative strong shunting currents in scalp layers. Copyright © 2013 Elsevier Inc. All rights reserved.

  12. Impeded Dark Matter

    International Nuclear Information System (INIS)

    Kopp, Joachim; Liu, Jia; Slatyer, Tracy R.; Wang, Xiao-Ping; Xue, Wei

    2016-01-01

    We consider dark matter models in which the mass splitting between the dark matter particles and their annihilation products is tiny. Compared to the previously proposed Forbidden Dark Matter scenario, the mass splittings we consider are much smaller, and are allowed to be either positive or negative. To emphasize this modification, we dub our scenario “Impeded Dark Matter”. We demonstrate that Impeded Dark Matter can be easily realized without requiring tuning of model parameters. For negative mass splitting, we demonstrate that the annihilation cross-section for Impeded Dark Matter depends linearly on the dark matter velocity or may even be kinematically forbidden, making this scenario almost insensitive to constraints from the cosmic microwave background and from observations of dwarf galaxies. Accordingly, it may be possible for Impeded Dark Matter to yield observable signals in clusters or the Galactic center, with no corresponding signal in dwarfs. For positive mass splitting, we show that the annihilation cross-section is suppressed by the small mass splitting, which helps light dark matter to survive increasingly stringent constraints from indirect searches. As specific realizations for Impeded Dark Matter, we introduce a model of vector dark matter from a hidden SU(2) sector, and a composite dark matter scenario based on a QCD-like dark sector.

  13. Impeded Dark Matter

    Energy Technology Data Exchange (ETDEWEB)

    Kopp, Joachim; Liu, Jia [PRISMA Cluster of Excellence & Mainz Institute for Theoretical Physics,Johannes Gutenberg University,Staudingerweg 7, 55099 Mainz (Germany); Slatyer, Tracy R. [Center for Theoretical Physics, Massachusetts Institute of Technology,Cambridge, MA 02139 (United States); Wang, Xiao-Ping [PRISMA Cluster of Excellence & Mainz Institute for Theoretical Physics,Johannes Gutenberg University,Staudingerweg 7, 55099 Mainz (Germany); Xue, Wei [Center for Theoretical Physics, Massachusetts Institute of Technology,Cambridge, MA 02139 (United States)

    2016-12-12

    We consider dark matter models in which the mass splitting between the dark matter particles and their annihilation products is tiny. Compared to the previously proposed Forbidden Dark Matter scenario, the mass splittings we consider are much smaller, and are allowed to be either positive or negative. To emphasize this modification, we dub our scenario “Impeded Dark Matter”. We demonstrate that Impeded Dark Matter can be easily realized without requiring tuning of model parameters. For negative mass splitting, we demonstrate that the annihilation cross-section for Impeded Dark Matter depends linearly on the dark matter velocity or may even be kinematically forbidden, making this scenario almost insensitive to constraints from the cosmic microwave background and from observations of dwarf galaxies. Accordingly, it may be possible for Impeded Dark Matter to yield observable signals in clusters or the Galactic center, with no corresponding signal in dwarfs. For positive mass splitting, we show that the annihilation cross-section is suppressed by the small mass splitting, which helps light dark matter to survive increasingly stringent constraints from indirect searches. As specific realizations for Impeded Dark Matter, we introduce a model of vector dark matter from a hidden SU(2) sector, and a composite dark matter scenario based on a QCD-like dark sector.

  14. Surface treatment and protection method for cadmium zinc telluride crystals

    Science.gov (United States)

    Wright, Gomez W.; James, Ralph B.; Burger, Arnold; Chinn, Douglas A.

    2003-01-01

    A method for treatment of the surface of a CdZnTe (CZT) crystal that provides a native dielectric coating to reduce surface leakage currents and thereby, improve the resolution of instruments incorporating detectors using CZT crystals. A two step process is disclosed, etching the surface of a CZT crystal with a solution of the conventional bromine/methanol etch treatment, and after attachment of electrical contacts, passivating the CZT crystal surface with a solution of 10 w/o NH.sub.4 F and 10 w/o H.sub.2 O.sub.2 in water.

  15. Surface Treatment And Protection Method For Cadium Zinc Telluride Crystals

    Science.gov (United States)

    Wright, Gomez W.; James, Ralph B.; Burger, Arnold; Chinn, Douglas A.

    2006-02-21

    A method for treatment of the surface of a CdZnTe (CZT) crystal that provides a native dielectric coating to reduce surface leakage currents and thereby, improve the resolution of instruments incorporating detectors using CZT crystals. A two step process is disclosed, etching the surface of a CZT crystal with a solution of the conventional bromine/methanol etch treatment, and after attachment of electrical contacts, passivating the CZT crystal surface with a solution of 10 w/o NH4F and 10 w/o H2O2 in water.

  16. [Body composition assessment by anthropometry and bioelectrical impedance].

    Science.gov (United States)

    Aristizábal, Juan Carlos; Restrepo, María Teresa; Estrada, Alejandro

    2007-06-01

    Anthropometry and electric impedance methods are widely used for body composition assessment. However the evidence is unclear whether the results obtained from the two methods can be compared. Two methods are compared for assessment of body composition; anthropometry and electric impedance. Body composition was measured in 70 women; aged 22 to 56 and 53 men; aged 24 to 54, using anthropometry (Durning/Womersley and Jackson/Pollock skinfolds equations) and electric impedance (foot to foot electric impedance) to obtain percentage body fat. The mean percentage body fat was significant higher with Durning/Womersley (25.2%) than Jackson/Pollock (20.1%) and electric impedance (19.3%) for men (pimpedance (27.6%) for women (p0.77) however, the concordance between methods to classify obesity subjects was low (Kbioelectrical impedance method. A significant difference was found between methods applied in men and women, and therefore these methods are not comparable.

  17. Investigation of dielectric relaxation and ac electrical conductivity using impedance spectroscopy method in (AuZn)/TiO{sub 2}/p-GaAs(1 1 0) Schottky barrier diodes

    Energy Technology Data Exchange (ETDEWEB)

    Şafak-Asar, Yasemin, E-mail: ysafak81@gmail.com; Asar, Tarık; Altındal, Şemsettin; Özçelik, Süleyman

    2015-04-15

    Dielectric properties and ac electrical conductivity of (AuZn)/TiO{sub 2}/p-GaAs(1 1 0) Schottky barrier diodes (SBDs) were investigated by using impedance spectroscopy method (capacitance and conductance measurements) in a wide frequency and applied bias voltage ranges at room temperature. The values of dielectric constant (ε′), dielectric loss (ε″), dielectric loss tangent (tan δ), real and imaginary parts of electrical modulus (M′ and M″) and ac electrical conductivity (σ{sub ac}) were found considerably sensitive to frequency and applied bias voltage especially in depletion and accumulation regions. While the values of ε″, ε″ and tan δ decrease, M′ and M″ increase with increasing frequencies due to the effect of interface states/traps (N{sub ss}), interfacial and dipole polarizations, series resistance (R{sub s}) and interfacial layer. Changes in these parameters are considerably high at low frequencies and they confirmed that the interfacial and dipole polarizations can occur more easily at low frequencies. Majority of the charges at N{sub ss} between (TiO{sub 2}/p-GaAs) can also easily follow external ac signal and so contributes to deviation of dielectric properties of the (AuZn)/TiO{sub 2}/p-GaAs(1 1 0) SBDs. In addition, structural properties of the sample such as crystallographic quality and interface characteristics were analyzed by X-ray Diffraction (XRD) and Secondary Ion Mass Spectrometry (SIMS) measurements. Surface morphology of the sample was characterized by atomic force microscopy (AFM) measurements. Surface RMS roughness values of the sample is obtained as 8.94 nm over a scan area of 3 μm × 3 μm.

  18. Investigation of dielectric relaxation and ac electrical conductivity using impedance spectroscopy method in (AuZn)/TiO2/p-GaAs(1 1 0) Schottky barrier diodes

    International Nuclear Information System (INIS)

    Şafak-Asar, Yasemin; Asar, Tarık; Altındal, Şemsettin; Özçelik, Süleyman

    2015-01-01

    Dielectric properties and ac electrical conductivity of (AuZn)/TiO 2 /p-GaAs(1 1 0) Schottky barrier diodes (SBDs) were investigated by using impedance spectroscopy method (capacitance and conductance measurements) in a wide frequency and applied bias voltage ranges at room temperature. The values of dielectric constant (ε′), dielectric loss (ε″), dielectric loss tangent (tan δ), real and imaginary parts of electrical modulus (M′ and M″) and ac electrical conductivity (σ ac ) were found considerably sensitive to frequency and applied bias voltage especially in depletion and accumulation regions. While the values of ε″, ε″ and tan δ decrease, M′ and M″ increase with increasing frequencies due to the effect of interface states/traps (N ss ), interfacial and dipole polarizations, series resistance (R s ) and interfacial layer. Changes in these parameters are considerably high at low frequencies and they confirmed that the interfacial and dipole polarizations can occur more easily at low frequencies. Majority of the charges at N ss between (TiO 2 /p-GaAs) can also easily follow external ac signal and so contributes to deviation of dielectric properties of the (AuZn)/TiO 2 /p-GaAs(1 1 0) SBDs. In addition, structural properties of the sample such as crystallographic quality and interface characteristics were analyzed by X-ray Diffraction (XRD) and Secondary Ion Mass Spectrometry (SIMS) measurements. Surface morphology of the sample was characterized by atomic force microscopy (AFM) measurements. Surface RMS roughness values of the sample is obtained as 8.94 nm over a scan area of 3 μm × 3 μm

  19. Comparison study of intraoperative surface acquisition methods for surgical navigation.

    Science.gov (United States)

    Simpson, Amber L; Burgner, Jessica; Glisson, Courtenay L; Herrell, S Duke; Ma, Burton; Pheiffer, Thomas S; Webster, Robert J; Miga, Michael I

    2013-04-01

    Soft-tissue image-guided interventions often require the digitization of organ surfaces for providing correspondence from medical images to the physical patient in the operating room. In this paper, the effect of several inexpensive surface acquisition techniques on target registration error and surface registration error (SRE) for soft tissue is investigated. A systematic approach is provided to compare image-to-physical registrations using three different methods of organ spatial digitization: 1) a tracked laser-range scanner (LRS), 2) a tracked pointer, and 3) a tracked conoscopic holography sensor (called a conoprobe). For each digitization method, surfaces of phantoms and biological tissues were acquired and registered to CT image volume counterparts. A comparison among these alignments demonstrated that registration errors were statistically smaller with the conoprobe than the tracked pointer and LRS (pconoscopic holography) of digitizing surfaces for clinical usage. The tracked conoscopic holography device outperforms LRS acquisitions with respect to registration accuracy.

  20. Laser method of acoustical emission control from vibrating surfaces

    Science.gov (United States)

    Motyka, Zbigniew

    2013-01-01

    For limitation of the noise in environment, the necessity occurs of determining and location of sources of sounds emitted from surfaces of many machines and devices, assuring in effect the possibility of suitable constructional changes implementation, targeted at decreasing of their nuisance. In the paper, the results of tests and calculations are presented for plane surface sources emitting acoustic waves. The tests were realized with the use of scanning laser vibrometer which enabled remote registration and the spectral analysis of the surfaces vibrations. The known hybrid digital method developed for determination of sound wave emission from such surfaces divided into small finite elements was slightly modified by distinguishing the phase correlations between such vibrating elements. The final method being developed may find use in wide range of applications for different forms of vibrations of plane surfaces.

  1. A GPU-based mipmapping method for water surface visualization

    Science.gov (United States)

    Li, Hua; Quan, Wei; Xu, Chao; Wu, Yan

    2018-03-01

    Visualization of water surface is a hot topic in computer graphics. In this paper, we presented a fast method to generate wide range of water surface with good image quality both near and far from the viewpoint. This method utilized uniform mesh and Fractal Perlin noise to model water surface. Mipmapping technology was enforced to the surface textures, which adjust the resolution with respect to the distance from the viewpoint and reduce the computing cost. Lighting effect was computed based on shadow mapping technology, Snell's law and Fresnel term. The render pipeline utilizes a CPU-GPU shared memory structure, which improves the rendering efficiency. Experiment results show that our approach visualizes water surface with good image quality at real-time frame rates performance.

  2. Evaluation of total body water in canine breeds by single-frequency bioelectrical impedance analysis method: specific equations are needed for accuracy.

    Science.gov (United States)

    Yaguiyan-Colliard, Laurence; Daumas, Caroline; Nguyen, Patrick; Grandjean, Dominique; Cardot, Philippe; Priymenko, Nathalie; Roux, Françoise

    2015-08-06

    Equations based on single-frequency bioelectrical impedance analysis at 50 kHz for determination of total body water content (TBW) have been previously validated in healthy non-sedated beagle dogs. We investigated whether these equations are predictive of TBW in various canine breeds by comparing the results of these equations with TBW values evaluated directly by deuterium oxide (D2O) dilution. Total body water content of 13 healthy adult pet dogs of various breeds was determined directly using D2O dilution and indirectly using previous equations based on values obtained with a portable bioelectric impedance device. Paired Student's t-tests were used to compare TBW obtained by single-frequency bioelectrical impedance analysis and D2O dilution. A p-value of bioelectrical impedance analysis parameters validated at 50 kHz in healthy adult beagles need to be modified including morphological parameters such as body size and shape in a first approach. As in humans, morphological-specific equations have to be developed and validated.

  3. Numerical studies of backscattering enhancement of electromagnetic waves from two-dimensional random rough surfaces with the forward-backward/novel spectral acceleration method.

    Science.gov (United States)

    Torrungrueng, D; Johnson, J T

    2001-10-01

    The forward-backward method with a novel spectral acceleration algorithm (FB/NSA) has been shown to be a highly efficient O(Ntot) iterative method of moments, where Ntot is the total number of unknowns to be solved, for the computation of electromagnetic (EM) wave scattering from both one-dimensional and two-dimensional (2-D) rough surfaces. The efficiency of the method makes studies of backscattering enhancement from moderately rough impedance surfaces at large incident angles tractable. Variations in the characteristics of backscattering enhancement with incident angle, surface impedance, polarization, and surface statistics are investigated by use of the 2-D FB/NSA method combined with parallel computing techniques. The surfaces considered are Gaussian random processes with an isotropic Gaussian spectrum and root-mean-square surface heights and slopes ranging from 0.5 lambda to lambda and from 0.5 to 1.0, respectively, where lambda is the EM wavelength in free space. Incident angles ranging from normal incidence up to 70 degrees are considered in this study. It is found that backscattering enhancement depends strongly on all parameters of interest. America

  4. Mechanism of the formation for thoracic impedance change.

    Science.gov (United States)

    Kuang, Ming-Xing; Xiao, Qiu-Jin; Cui, Chao-Ying; Kuang, Nan-Zhen; Hong, Wen-Qin; Hu, Ai-Rong

    2010-03-01

    The purpose of this study is to investigate the mechanism of the formation for thoracic impedance change. On the basis of Ohm's law and the electrical field distribution in the cylindrical volume conductor, the formula about the thoracic impedance change are deduced, and they are demonstrated with the model experiment. The results indicate that the thoracic impedance change caused by single blood vessel is directly proportional to the ratio of the impedance change to the basal impedance of the blood vessel itself, to the length of the blood vessel appearing between the current electrodes, and to the basal impedance between two detective electrodes on the chest surface, while it is inversely proportional to the distance between the blood vessel and the line joining two detective electrodes. The thoracic impedance change caused by multiple blood vessels together is equal to the algebraic addition of all thoracic impedance changes resulting from the individual blood vessels. That is, the impedance changes obey the principle of adding scalars in the measurement of the electrical impedance graph. The present study can offer the theoretical basis for the waveform reconstruction of Impedance cardiography (ICG).

  5. Development of ceramic vacuum chambers and their impedance measurement

    International Nuclear Information System (INIS)

    Shang Lei; Pei Yuanji; Wang Xiangqi; Leng Yongbin; Wang Lin; Fan Kuanjun

    2000-01-01

    Several technical schemes of constructing a injection kicker magnet and its vacuum chambers are firstly reviewed and discussed. A method of using ferrite kicker magnets with ceramic chambers inside is adopted in HLS new injection system. The inner surfaces of these ceramic chambers are coated with a metallic layer to meet the requirements of both the penetration of pulse magnetic field and small beam coupling impedance. The loss factors and wake fields of the ceramic chambers with and without coating are measured. Broadband impedance parameters of these ceramic chambers are obtained by fitting the measured data. Combining the results of magnetic field studies, an improved coating scheme is proposed for the new ceramic chambers

  6. Acoustic impedances of audiometric earphones coupled to different loads

    DEFF Research Database (Denmark)

    Ciric, Dejan; Hammershøi, Dorte

    2005-01-01

    . The importance of this impedance is related to the contribution of other elements involved in transmission such as ear canal impedance or impedance of the coupler seen from outside. In order to determine the acoustic impedances of five audiometric earphones, the standardized method for measurement of complex......, audiometric earphones are coupled to different loads. Thus, they are placed on different terminations of the tube including metal plate, artificial rubber pinna and upper part of the standardized coupler. The results show that the impedances of earphones are different, but they also differ from radiation...... in investigations of coupling of audiometric earphones to human ears and to the same coupler....

  7. Application of Ultrasonic Sensors in Road Surface Condition Distinction Methods

    Directory of Open Access Journals (Sweden)

    Shota Nakashima

    2016-10-01

    Full Text Available The number of accidents involving elderly individuals has been increasing with the increase of the aging population, posing increasingly serious challenges. Most accidents are caused by reduced judgment and physical abilities, which lead to severe consequences. Therefore, studies on support systems for elderly and visually impaired people to improve the safety and quality of daily life are attracting considerable attention. In this study, a road surface condition distinction method using reflection intensities obtained by an ultrasonic sensor was proposed. The proposed method was applied to movement support systems for elderly and visually impaired individuals to detect dangerous road surfaces and give an alarm. The method did not perform well in previous studies of puddle detection, because the alert provided by the method did not enable users to avoid puddles. This study extended the method proposed by previous studies with respect to puddle detection ability. The findings indicate the effectiveness of the proposed method by considering four road surface conditions. The proposed method could detect puddle conditions. The effectiveness of the proposed method was verified in all four conditions, since users could differentiate between road surface conditions and classify the conditions as either safe or dangerous.

  8. METHOD FOR FABRICATING NANOSCALE PATTERNS ON A SURFACE

    DEFF Research Database (Denmark)

    2000-01-01

    A novel method to fabricate nanoscale pits on Au(111) surfaces in contact with aqueous solution is claimed. The method uses in situ electrochemical scanning tunnelling microscopy with independent electrochemical substrate and tip potential control and very small bias voltages. This is significantly...

  9. A new method to obtain narrowband emission from a broadband current using increased impedance of plasma-like media (Conference Presentation)

    Science.gov (United States)

    Hur, Min Sup; Ersfeld, Bernhard; Noble, Adam; Suk, Hyyong; Jaroszynski, Dino A.

    2017-05-01

    In conventional radiation sources, narrowband radiation emission can be obtained by narrowband current oscillation. Usually the spectrum of the oscillating current is made narrow by a large or complicated structure for wave-particle interaction. One good example is the beam-undulator system. In this presentation, we introduce a new method to obtain a radiation emission with a well-collimated frequency without changing the broadband nature of a given current source. The method is based on our recent discovery of the new physical properties of the cut-off phenomenon, which broadly exists in general plasma-like media, such as plasma, waveguide, or photonic crystal, etc. A common feature of these media is the Bohm-Gross dispersion relation, which has a frequency condition to make the wavenumber zero. In the zero-wavenumber state, an electromagnetic wave cannot propagate through the medium, but instead, is reflected (i.e. cut-off). In regular steady-state analysis, the cut-off condition is characterized by infinite radiation impedance. An interesting question here is what would happen to the radiation power, if a non-zero current oscillating with the cut-off frequency were enforced in a medium (a current source, in contrast with the regular voltage source). A regular steady-state analysis for this situation leads to infinite power of radiation from Ohm's law. We could solve such a paradoxical situation by analyzing the non-steady-state system; we found that the system can be described by a time-dependent Schroedinger equation with an external driving term. The solution of this equation shows a temporally growing electromagnetic field. When this concept is extended to a generally broadband current source, the spectral density at the cut-off frequency can be selectively enhanced (selectively enhanced emission, SEE). Hence a general broadband radiation source can be easily converted to a narrowband source by enclosing the system with a plasma-like medium. The current

  10. Quantifying Uncertainty in Near Surface Electromagnetic Imaging Using Bayesian Methods

    Science.gov (United States)

    Blatter, D. B.; Ray, A.; Key, K.

    2017-12-01

    Geoscientists commonly use electromagnetic methods to image the Earth's near surface. Field measurements of EM fields are made (often with the aid an artificial EM source) and then used to infer near surface electrical conductivity via a process known as inversion. In geophysics, the standard inversion tool kit is robust and can provide an estimate of the Earth's near surface conductivity that is both geologically reasonable and compatible with the measured field data. However, standard inverse methods struggle to provide a sense of the uncertainty in the estimate they provide. This is because the task of finding an Earth model that explains the data to within measurement error is non-unique - that is, there are many, many such models; but the standard methods provide only one "answer." An alternative method, known as Bayesian inversion, seeks to explore the full range of Earth model parameters that can adequately explain the measured data, rather than attempting to find a single, "ideal" model. Bayesian inverse methods can therefore provide a quantitative assessment of the uncertainty inherent in trying to infer near surface conductivity from noisy, measured field data. This study applies a Bayesian inverse method (called trans-dimensional Markov chain Monte Carlo) to transient airborne EM data previously collected over Taylor Valley - one of the McMurdo Dry Valleys in Antarctica. Our results confirm the reasonableness of previous estimates (made using standard methods) of near surface conductivity beneath Taylor Valley. In addition, we demonstrate quantitatively the uncertainty associated with those estimates. We demonstrate that Bayesian inverse methods can provide quantitative uncertainty to estimates of near surface conductivity.

  11. Novel method for controllable fabrication of a superhydrophobic CuO surface on AZ91D magnesium alloy.

    Science.gov (United States)

    She, Zuxin; Li, Qing; Wang, Zhongwei; Li, Longqin; Chen, Funan; Zhou, Juncen

    2012-08-01

    A novel method for controllable fabrication of a superhydrophobic CuO surface on AZ91D magnesium alloy is reported in this paper. Hierarchical structure composed of micro/nano-featherlike CuO was obtained by electrodeposition of Cu-Zn alloy coating and subsequently an electrochemical anodic treatment in alkaline solution. After modification with lauric acid, the surface became hydrophobicity/superhydrophobicity. The formation of featherlike CuO structures was controllable by varying the coating composition. By applying SEM, ICP-AES, and water contact angle analysis, the effects of coating composition on the surface morphology and hydrophobicity of the as-prepared surfaces were detailedly studied. The results indicated that at the optimal condition, the surface showed a good superhydrophobicity with a water contact angle as high as 155.5 ± 1.3° and a sliding angle as low as about 3°. Possible growth mechanism of featherlike CuO hierarchical structure was discussed. Additionally, the anticorrosion effect of the superhydrophobic surface was studied by potentiodynamic polarization and electrochemical impedance spectroscopy (EIS) measurements. The interface model for anticorrosion mechanism of superhydrophobic surface in corrosive medium was proposed. Besides, the mechanical stability test indicated that the resulting superhydrophobic surfaces have good mechanical stability.

  12. ac impedance, X-ray photoelectron spectroscopy and density functional theory studies of 3,5-bis(n-pyridyl)-1,2,4-oxadiazoles as efficient corrosion inhibitors for carbon steel surface in hydrochloric acid solution

    Energy Technology Data Exchange (ETDEWEB)

    Outirite, Moha; Lagrenee, Michel; Lebrini, Mounim [Unite de Catalyse et de Chimie du Solide, UMR-CNRS 8181, ENSCL, B.P. 90108, F-59652 Villeneuve d' Ascq Cedex (France); Traisnel, Michel; Jama, Charafeddine [Laboratoire des Procedes d' Elaboration des Revetements Fonctionnels, PERF UMR-CNRS 8008, ENSCL, B.P. 90108, F-59652 Villeneuve d' Ascq Cedex (France); Vezin, Herve [Laboratoire de Chimie Organique et Macromoleculaire, UMR-CNRS 8009, USTL Bat C4, F-59655 Villeneuve d' Ascq Cedex (France); Bentiss, Fouad, E-mail: fbentiss@enscl.f [Laboratoire de Chimie de Coordination et d' Analytique, Faculte des Sciences, Universite Chouaib Doukkali, B.P. 20, M-24000 El Jadida (Morocco)

    2010-02-01

    The corrosion inhibition properties of a new class of oxadiazole derivatives, namely 3,5-bis(n-pyridyl)-1,2,4-oxadiazoles (n-DPOX) for C38 carbon steel corrosion in 1 M HCl medium were analysed by electrochemical impedance spectroscopy (EIS). An adequate structural model of the interface was used and the values of the corresponding parameters were calculated and discussed. The experimental results showed that these compounds are excellent inhibitors for the C38 steel corrosion in acid solution and that the protection efficiency increased with increasing the inhibitors concentration. Electrochemical impedance data demonstrate that the addition of the n-DPOX derivatives in the corrosive solution decreases the charge capacitance and simultaneously increases the function of the charge/discharge of the interface, facilitating the formation of an adsorbed layer over the steel surface. Adsorption of these inhibitors on the steel surface obeys to the Langmuir adsorption isotherm. X-ray photoelectron spectroscopy (XPS) and the thermodynamic data of adsorption showed that inhibition of steel corrosion in normal hydrochloric solution by n-DPOX is due to the formation of a chemisorbed film on the steel surface. Quantum chemical calculations using the Density Functional Theory (DFT) and the Quantitative Structure Activity Relationship (QSAR) approach were performed on n-DPOX derivatives to determine the relationship between molecular structure and their inhibition efficiencies. The results of the quantum chemical calculations and experimental inhibition efficiency were subjected to correlation analysis and indicate that their inhibition effect is closely related to E{sub HOMO}, E{sub LUMO}, and dipole moment (mu).

  13. Optical description and design method with annularly stitched aspheric surface.

    Science.gov (United States)

    Cheng, De-Wen; Chen, Xue-Jiao; Xu, Chen; Hu, Yuan; Wang, Yong-Tian

    2015-12-01

    The relentless pressure for designs with new optical functions, small volume, and light weight has greatly increased the importance of aspheric surfaces. In this paper, we propose an annularly stitched aspheric surface (ASAS) description method to increase the freedom and flexibility of imaging system design. The rotationally symmetric ASAS consists of a circular central zone and one or more annular zones. Two neighboring zones are constrained to have the same derivatives on their joint curve, and this means the ASAS is C1 continuous. This finding is proved and verified by the mathematical deduction of the surface formulas. Two optimization strategies and two design methods with the C1 continuous constraints are also discussed. This surface can greatly facilitate the design and even achieve some previously impossible designs without increasing the fabrication difficulty. Two different systems with the proposed ASAS are optimized and the results are presented. The design results verified the practicability of the ASAS.

  14. Impedance pattern of vaginal and vestibular mucosa in cyclic goats

    Directory of Open Access Journals (Sweden)

    Ivo Křivánek

    2008-01-01

    Full Text Available The changes of vaginal and vestibular impedance during the oestrous cycle in goats were examined. The onset of oestrus was teased with a buck once a day during the experiment. Impedance was mea­sured by a four-terminal method. The vaginal impedance was recorded under slight pressure of electrodes to the vaginal dorsal wall at the cervix. The vestibular impedance was recorded under slight pressure of electrodes to the vestibular dorsal wall 5 cm from the vulva and at the vulva. The im­pe­dan­ce was measured once a day from 4 days before the expected oestrus to 6 days after onset of oestrus. The vaginal impedance at the cervix decreased during pro-oestrus (P < 0.01 and increased du­ring oestrus (P < 0.01. The vestibular impedance 5 cm from the vulva decreased during pro-oestrus (P < 0.01 and increased after oestrus (P < 0.01. The decrease of vaginal impedance during peri-oestrus was nearly twofold in comparison with the vestibular impedance 5 cm from the vulva. No sig­ni­fi­cant decrease of the vestibular impedance at the vulva was found during the oestrous cycle. The results indicate that the vaginal impedance at the cervix and vestibular impedance 5 cm from the vulva measured by means of a four-terminal method during the oestrous cycle display cyclic changes that are closely related to the oestrous behaviour of goats.

  15. Multiscale Finite Element Methods for Flows on Rough Surfaces

    KAUST Repository

    Efendiev, Yalchin

    2013-01-01

    In this paper, we present the Multiscale Finite Element Method (MsFEM) for problems on rough heterogeneous surfaces. We consider the diffusion equation on oscillatory surfaces. Our objective is to represent small-scale features of the solution via multiscale basis functions described on a coarse grid. This problem arises in many applications where processes occur on surfaces or thin layers. We present a unified multiscale finite element framework that entails the use of transformations that map the reference surface to the deformed surface. The main ingredients of MsFEM are (1) the construction of multiscale basis functions and (2) a global coupling of these basis functions. For the construction of multiscale basis functions, our approach uses the transformation of the reference surface to a deformed surface. On the deformed surface, multiscale basis functions are defined where reduced (1D) problems are solved along the edges of coarse-grid blocks to calculate nodalmultiscale basis functions. Furthermore, these basis functions are transformed back to the reference configuration. We discuss the use of appropriate transformation operators that improve the accuracy of the method. The method has an optimal convergence if the transformed surface is smooth and the image of the coarse partition in the reference configuration forms a quasiuniform partition. In this paper, we consider such transformations based on harmonic coordinates (following H. Owhadi and L. Zhang [Comm. Pure and Applied Math., LX(2007), pp. 675-723]) and discuss gridding issues in the reference configuration. Numerical results are presented where we compare the MsFEM when two types of deformations are used formultiscale basis construction. The first deformation employs local information and the second deformation employs a global information. Our numerical results showthat one can improve the accuracy of the simulations when a global information is used. © 2013 Global-Science Press.

  16. Experimental Method for Measuring Dust Load on Surfaces in Rooms

    DEFF Research Database (Denmark)

    Lengweiler, Philip; Nielsen, Peter V.; Moser, Alfred

    , there is a need for better understanding of the mechanism of dust deposition and resuspension. With the presented experimental setup, the dust load on surfaces in a channel can be measured as a function of the environmental and surface conditions and the type of particles under controlled laboratory conditions.......A new experimental setup to investigate the physical process of dust deposition and resuspension on and from surfaces is introduced. Dust deposition can reduce the airborne dust concentration considerably. As a basis for developing methods to eliminate dust-related problems in rooms...

  17. Noise robustness of interferometric surface topography evaluation methods. Correlogram correlation

    Science.gov (United States)

    Kiselev, Ilia; Kiselev, Egor I.; Drexel, Michael; Hauptmannl, Michael

    2017-12-01

    Different surface height estimation methods are differently affected by interferometric noise. From a theoretical analysis we obtain height variance estimators for the methods. The estimations allow us to rigorously compare the noise robustness of popular evaluation algorithms. The envelope methods have the highest variances and hence the lowest noise resistances. The noise robustness improves from the envelope to the phase methods, but a technique involving the correlation of correlograms is superior even to the latter. We dwell on some details of this correlogram correlation method and the range of its application.

  18. Mechanical Impedance Modeling of Human Arm: A survey

    Science.gov (United States)

    Puzi, A. Ahmad; Sidek, S. N.; Sado, F.

    2017-03-01

    Human arm mechanical impedance plays a vital role in describing motion ability of the upper limb. One of the impedance parameters is stiffness which is defined as the ratio of an applied force to the measured deformation of the muscle. The arm mechanical impedance modeling is useful in order to develop a better controller for system that interacts with human as such an automated robot-assisted platform for automated rehabilitation training. The aim of the survey is to summarize the existing mechanical impedance models of human upper limb so to justify the need to have an improved version of the arm model in order to facilitate the development of better controller of such systems with ever increase in complexity. In particular, the paper will address the following issue: Human motor control and motor learning, constant and variable impedance models, methods for measuring mechanical impedance and mechanical impedance modeling techniques.

  19. Longitudinal impedance calculation of coated ceramic vacuum chamber at HLS

    International Nuclear Information System (INIS)

    Wang Lin; Xu Hongliang; Shang Lei; Wang Xiangqi; Li Weimin

    2003-01-01

    The purpose of this paper is to estimate the longitudinal coupling impedance of the coated ceramic vacuum chamber employed in new injection system of Hefei Light Source. For the regular axially symmetric boundary, the analytical results of the impedance for the coated ceramic chamber can be easily obtained by application field matching techniques to Maxwell equations in cylindrical coordinate system. For the irregular boundary used in HLS, it is very hard to obtain analytical result of impedance. Based on the impedance measurement principle of coaxial wire method, the impedance of ceramic chamber was numerically calculated. The calculated results showed that, although coating inside ceramic chamber can reduce impedance by some factor, the coated ceramic chamber is one of the main impedance sources of HLS storage ring

  20. 3D electric field calculation with surface charge method

    International Nuclear Information System (INIS)

    Yamada, S.

    1992-01-01

    This paper describes an outline and some examples of three dimensional electric field calculations with a computer code developed at NIRS. In the code, a surface charge method is adopted because of it's simplicity in the mesh establishing procedure. The charge density in a triangular mesh is assumed to distribute with a linear function of the position. The electric field distribution is calculated for a pair of drift tubes with the focusing fingers on the opposing surfaces. The field distribution in an acceleration gap is analyzed with a Fourier-Bessel series expansion method. The calculated results excellently reproduces the measured data with a magnetic model. (author)

  1. Meaning of the negative impedance

    Energy Technology Data Exchange (ETDEWEB)

    Conciauro, G.; Puglisi, M.

    1981-06-01

    It is shown that the negative real part of an input impedance does not mean instability of the related circuit. A negative real part of the input impedance means only that the concerned circuit is active.

  2. Meaning of the negative impedance

    International Nuclear Information System (INIS)

    Conciauro, G.; Puglisi, M.

    1981-06-01

    It is shown that the negative real part of an input impedance does not mean instability of the related circuit. A negative real part of the input impedance means only that the concerned circuit is active

  3. Correction of surface aberration in strain scanning method with analyzer

    International Nuclear Information System (INIS)

    Shobu, Takahisa; Mizuki, Junichiro; Suzuki, Kenji; Akiniwa, Yoshiaki; Tanaka, Keisuke

    2006-01-01

    When a gauge volume sank below a specimen surface, the diffraction angle shifts. Thus, it is required to correct the surface aberration. For the annealed specimen of S45C, the shift in the diffraction angle was investigated using a strain scanning method with Ge (111) analyzer. This phenomenon was caused by the difference in the centroid between the geometric and the instrumental gauge volumes. This difference is explained by the following factors; 1) the change in the gauge volume by the divergence of the analyzer, 2) the X-ray penetration depth, 3) the gap of the centre line between the double receiving slits due to mis-setting the analyzer. As a result, the correcting method considered into these factors was proposed. For the shot-peened specimens of S45C, the diffraction angles were measured and corrected by our method. The distribution of the residual stress agreed with that obtained by the removal method. (author)

  4. DIFFERENTIAL SOIL IMPEDANCE OBSTACLE DETECTION

    Energy Technology Data Exchange (ETDEWEB)

    Maximillian J. Kieba

    2003-10-01

    This project develops a new and unique obstacle detection sensor for horizontal directional drilling (HDD) equipment. The development of this new technology will greatly improve the reliability and safety of natural gas HDD construction practices. This sensor utilizes a differential soil impedance measurement technique that will be sensitive to the presence of plastic and ceramic, as well as metallic obstacles. The use of HDD equipment has risen significantly in the gas industry because HDD provides a much more cost-effective and less disruptive method for gas pipe installation than older, trenching methods. However, there have been isolated strikes of underground utilities by HDD equipment, which may have been avoided if methods were available to detect other underground obstacles when using HDD systems. GTI advisors from the gas industry have ranked the value of solving the obstacle detection problem as the most important research and development project for GTI to pursue using Federal Energy Regulatory Commission (FERC) funds available through its industry partner, GRI. GTI proposes to develop a prototype down-hole sensor system that is simple and compact. The sensor utilizes an impedance measurement technique that is sensitive to the presence of metallic or nonmetallic objects in the proximity of the HDD head. The system will use a simple sensor incorporated into the drill head. The impedance of the soil will be measured with a low frequency signal injected through the drill head itself. A pair of bridge type impedance sensors, mounted orthogonal to one another, is coupled to the soil. Inclusions in the soil will cause changes to the sensor balance distinguishable from homogeneous soil. The sensor will provide range and direction data for obstacles near the HDD head. The goal is to provide a simple, robust system that provides the information required to avoid obstacles. This must be done within the size and ruggedness constraints of the HDD equipment. Imaging

  5. DIFFERENTIAL SOIL IMPEDANCE OBSTACLE DETECTION

    Energy Technology Data Exchange (ETDEWEB)

    Maximillian J. Kieba

    2004-02-01

    This project develops a new and unique obstacle detection sensor for horizontal directional drilling (HDD) equipment. The development of this new technology will greatly improve the reliability and safety of natural gas HDD construction practices. This sensor utilizes a differential soil impedance measurement technique that will be sensitive to the presence of plastic and ceramic, as well as metallic obstacles. The use of HDD equipment has risen significantly in the gas industry because HDD provides a much more cost-effective and less disruptive method for gas pipe installation than older, trenching methods. However, there have been isolated strikes of underground utilities by HDD equipment, which may have been avoided if methods were available to detect other underground obstacles when using HDD systems. GTI advisors from the gas industry have ranked the value of solving the obstacle detection problem as the most important research and development project for GTI to pursue using Federal Energy Regulatory Commission (FERC) funds available through its industry partner, GRI. GTI proposes to develop a prototype down-hole sensor system that is simple and compact. The sensor utilizes an impedance measurement technique that is sensitive to the presence of metallic or nonmetallic objects in the proximity of the HDD head. The system will use a simple sensor incorporated into the drill head. The impedance of the soil will be measured with a low frequency signal injected through the drill head itself. A pair of bridge type impedance sensors, mounted orthogonal to one another, is coupled to the soil. Inclusions in the soil will cause changes to the sensor balance distinguishable from homogeneous soil. The sensor will provide range and direction data for obstacles near the HDD head. The goal is to provide a simple, robust system that provides the information required to avoid obstacles. This must be done within the size and ruggedness constraints of the HDD equipment. Imaging

  6. DIFFERENTIAL SOIL IMPEDANCE OBSTACLE DETECTION

    Energy Technology Data Exchange (ETDEWEB)

    Maximillian J. Kieba

    2003-04-01

    This project develops a new and unique obstacle detection sensor for horizontal directional drilling (HDD) equipment. The development of this new technology will greatly improve the reliability and safety of natural gas HDD construction practices. This sensor utilizes a differential soil impedance measurement technique that will be sensitive to the presence of plastic and ceramic, as well as metallic obstacles. The use of HDD equipment has risen significantly in the gas industry because HDD provides a much more cost-effective and less disruptive method for gas pipe installation than older, trenching methods. However, there have been isolated strikes of underground utilities by HDD equipment, which may have been avoided if methods were available to detect other underground obstacles when using HDD systems. GTI advisors from the gas industry have ranked the value of solving the obstacle detection problem as the most important research and development project for GTI to pursue using Federal Energy Regulatory Commission (FERC) funds available through its industry partner, GRI. GTI proposes to develop a prototype down-hole sensor system that is simple and compact. The sensor utilizes an impedance measurement technique that is sensitive to the presence of metallic or nonmetallic objects in the proximity of the HDD head. The system will use a thin film sensor conformal with the drill head. The impedance of the soil will be measured with a low frequency signal injected through the drill head itself. A pair of bridge type impedance sensors, mounted orthogonal to one another, is capacitively coupled to the soil. Inclusions in the soil will cause changes to the sensor balance distinguishable from homogeneous soil. The sensor will provide range and direction data for obstacles near the HDD head. The goal is to provide a simple, robust system that provides the information required to avoid obstacles. This must be done within the size and ruggedness constraints of the HDD

  7. DIFFERENTIAL SOIL IMPEDANCE OBSTACLE DETECTION

    Energy Technology Data Exchange (ETDEWEB)

    Maximillian J. Kieba

    2003-01-30

    This project develops a new and unique obstacle detection sensor for horizontal directional drilling (HDD) equipment. The development of this new technology will greatly improve the reliability and safety of natural gas HDD construction practices. This sensor utilizes a differential soil impedance measurement technique that will be sensitive to the presence of plastic and ceramic, as well as metallic obstacles. The use of HDD equipment has risen significantly in the gas industry because HDD provides a much more cost-effective and less disruptive method for gas pipe installation than older, trenching methods. However, there have been isolated strikes of underground utilities by HDD equipment, which may have been avoided if methods were available to detect other underground obstacles when using HDD systems. GTI advisors from the gas industry have ranked the value of solving the obstacle detection problem as the most important research and development project for GTI to pursue using Federal Energy Regulatory Commission (FERC) funds available through its industry partner, GRI. GTI proposes to develop a prototype down-hole sensor system that is simple and compact. The sensor utilizes an impedance measurement technique that is sensitive to the presence of metallic or nonmetallic objects in the proximity of the HDD head. The system will use a thin film sensor conformal with the drill head. The impedance of the soil will be measured with a low frequency signal injected through the drill head itself. A pair of bridge type impedance sensors, mounted orthogonal to one another, is capacitively coupled to the soil. Inclusions in the soil will cause changes to the sensor balance distinguishable from homogeneous soil. The sensor will provide range and direction data for obstacles near the HDD head. The goal is to provide a simple, robust system that provides the information required to avoid obstacles. This must be done within the size and ruggedness constraints of the HDD

  8. DIFFERENTIAL SOIL IMPEDANCE OBSTACLE DETECTION

    Energy Technology Data Exchange (ETDEWEB)

    Maximillian J. Kieba; Christopher J. Ziolkowski

    2005-01-17

    This project aimed at developing a new and unique obstacle detection sensor for horizontal directional drilling (HDD) equipment. The development of this new technology will greatly improve the reliability and safety of natural gas HDD construction practices. This sensor utilizes a differential soil impedance measurement technique that will be sensitive to the presence of plastic and ceramic, as well as metallic obstacles. The use of HDD equipment has risen significantly in the gas industry because HDD provides a much more cost-effective and less disruptive method for gas pipe installation than older, trenching methods. However, there have been isolated strikes of underground utilities by HDD equipment, which may have been avoided if methods were available to detect other underground obstacles when using HDD systems. GTI advisors from the gas industry ranked the value of solving the obstacle detection problem as the most important research and development project for GTI to pursue using Federal Energy Regulatory Commission (FERC) funds available through its industry partner, GTI. GTI proposed to develop a prototype down-hole sensor system that is simple and compact. The sensor utilizes an impedance measurement technique that is sensitive to the presence of metallic or non-metallic objects in the proximity of the HDD head. The system will use a simple sensor incorporated into the drill head. The impedance of the soil will be measured with a low frequency signal injected through the drill head itself. A pair of bridge type impedance sensors, mounted orthogonal to one another, is coupled to the soil. Inclusions in the soil will cause changes to the sensor balance distinguishable from homogeneous soil. The sensor will provide range and direction data for obstacles near the HDD head. The goal is to provide a simple, robust system that provides the information required to avoid obstacles. This must be done within the size and ruggedness constraints of the HDD equipment

  9. DIFFERENTIAL SOIL IMPEDANCE OBSTACLE DETECTION

    Energy Technology Data Exchange (ETDEWEB)

    Maximillian J. Kieba

    2002-11-27

    This project develops a new and unique obstacle detection sensor for horizontal directional drilling (HDD) equipment. The development of this new technology will greatly improve the reliability and safety of natural gas HDD construction practices. This sensor utilizes a differential soil impedance measurement technique that will be sensitive to the presence of plastic and ceramic, as well as metallic obstacles. The use of HDD equipment has risen significantly in the gas industry because HDD provides a much more cost-effective and less disruptive method for gas pipe installation than older, trenching methods. However, there have been isolated strikes of underground utilities by HDD equipment, which may have been avoided if methods were available to detect other underground obstacles when using HDD systems. GTI advisors from the gas industry have ranked the value of solving the obstacle detection problem as the most important research and development project for GTI to pursue using Federal Energy Regulatory Commission (FERC) funds available through its industry partner, GRI. GTI proposes to develop a prototype down-hole sensor system that is simple and compact. The sensor utilizes an impedance measurement technique that is sensitive to the presence of metallic or nonmetallic objects in the proximity of the HDD head. The system will use a thin film sensor conformal with the drill head. The impedance of the soil will be measured with a low frequency signal injected through the drill head itself. A pair of bridge type impedance sensors, mounted orthogonal to one another, is capacitively coupled to the soil. Inclusions in the soil will cause changes to the sensor balance distinguishable from homogeneous soil. The sensor will provide range and direction data for obstacles near the HDD head. The goal is to provide a simple, robust system that provides the information required to avoid obstacles. This must be done within the size and ruggedness constraints of the HDD

  10. DIFFERENTIAL SOIL IMPEDANCE OBSTACLE DETECTION

    Energy Technology Data Exchange (ETDEWEB)

    Maximillian J. Kieba

    2004-05-03

    This project develops a new and unique obstacle detection sensor for horizontal directional drilling (HDD) equipment. The development of this new technology will greatly improve the reliability and safety of natural gas HDD construction practices. This sensor utilizes a differential soil impedance measurement technique that will be sensitive to the presence of plastic and ceramic, as well as metallic obstacles. The use of HDD equipment has risen significantly in the gas industry because HDD provides a much more cost-effective and less disruptive method for gas pipe installation than older, trenching methods. However, there have been isolated strikes of underground utilities by HDD equipment, which may have been avoided if methods were available to detect other underground obstacles when using HDD systems. GTI advisors from the gas industry have ranked the value of solving the obstacle detection problem as the most important research and development project for GTI to pursue using Federal Energy Regulatory Commission (FERC) funds available through its industry partner, GRI. GTI proposes to develop a prototype down-hole sensor system that is simple and compact. The sensor utilizes an impedance measurement technique that is sensitive to the presence of metallic or nonmetallic objects in the proximity of the HDD head. The system will use a simple sensor incorporated into the drill head. The impedance of the soil will be measured with a low frequency signal injected through the drill head itself. A pair of bridge type impedance sensors, mounted orthogonal to one another, is coupled to the soil. Inclusions in the soil will cause changes to the sensor balance distinguishable from homogeneous soil. The sensor will provide range and direction data for obstacles near the HDD head. The goal is to provide a simple, robust system that provides the information required to avoid obstacles. This must be done within the size and ruggedness constraints of the HDD equipment. Imaging

  11. DIFFERENTIAL SOIL IMPEDANCE OBSTACLE DETECTION

    Energy Technology Data Exchange (ETDEWEB)

    Maximillian J. Kieba; Christopher J. Ziolkowski

    2004-06-30

    This project develops a new and unique obstacle detection sensor for horizontal directional drilling (HDD) equipment. The development of this new technology will greatly improve the reliability and safety of natural gas HDD construction practices. This sensor utilizes a differential soil impedance measurement technique that will be sensitive to the presence of plastic and ceramic, as well as metallic obstacles. The use of HDD equipment has risen significantly in the gas industry because HDD provides a much more cost-effective and less disruptive method for gas pipe installation than older, trenching methods. However, there have been isolated strikes of underground utilities by HDD equipment, which may have been avoided if methods were available to detect other underground obstacles when using HDD systems. GTI advisors from the gas industry have ranked the value of solving the obstacle detection problem as the most important research and development project for GTI to pursue using Federal Energy Regulatory Commission (FERC) funds available through its industry partner, GRI. GTI proposes to develop a prototype down-hole sensor system that is simple and compact. The sensor utilizes an impedance measurement technique that is sensitive to the presence of metallic or nonmetallic objects in the proximity of the HDD head. The system will use a simple sensor incorporated into the drill head. The impedance of the soil will be measured with a low frequency signal injected through the drill head itself. A pair of bridge type impedance sensors, mounted orthogonal to one another, is coupled to the soil. Inclusions in the soil will cause changes to the sensor balance distinguishable from homogeneous soil. The sensor will provide range and direction data for obstacles near the HDD head. The goal is to provide a simple, robust system that provides the information required to avoid obstacles. This must be done within the size and ruggedness constraints of the HDD equipment. Imaging

  12. DIFFERENTIAL SOIL IMPEDANCE OBSTACLE DETECTION

    Energy Technology Data Exchange (ETDEWEB)

    Maximillian J. Kieba; Christopher J. Ziolkowski

    2004-10-29

    This project develops a new and unique obstacle detection sensor for horizontal directional drilling (HDD) equipment. The development of this new technology will greatly improve the reliability and safety of natural gas HDD construction practices. This sensor utilizes a differential soil impedance measurement technique that will be sensitive to the presence of plastic and ceramic, as well as metallic obstacles. The use of HDD equipment has risen significantly in the gas industry because HDD provides a much more cost-effective and less disruptive method for gas pipe installation than older, trenching methods. However, there have been isolated strikes of underground utilities by HDD equipment, which may have been avoided if methods were available to detect other underground obstacles when using HDD systems. GTI advisors from the gas industry have ranked the value of solving the obstacle detection problem as the most important research and development project for GTI to pursue using Federal Energy Regulatory Commission (FERC) funds available through its industry partner, GRI. GTI proposes to develop a prototype down-hole sensor system that is simple and compact. The sensor utilizes an impedance measurement technique that is sensitive to the presence of metallic or non-metallic objects in the proximity of the HDD head. The system will use a simple sensor incorporated into the drill head. The impedance of the soil will be measured with a low frequency signal injected through the drill head itself. A pair of bridge type impedance sensors, mounted orthogonal to one another, is coupled to the soil. Inclusions in the soil will cause changes to the sensor balance distinguishable from homogeneous soil. The sensor will provide range and direction data for obstacles near the HDD head. The goal is to provide a simple, robust system that provides the information required to avoid obstacles. This must be done within the size and ruggedness constraints of the HDD equipment. Imaging

  13. DIFFERENTIAL SOIL IMPEDANCE OBSTACLE DETECTION

    Energy Technology Data Exchange (ETDEWEB)

    Maximillian J. Kieba

    2002-08-30

    This project develops a new and unique obstacle detection sensor for horizontal directional drilling (HDD) equipment. The development of this new technology will greatly improve the reliability and safety of natural gas HDD construction practices. This sensor utilizes a differential soil impedance measurement technique that will be sensitive to the presence of plastic and ceramic, as well as metallic obstacles. The use of HDD equipment has risen significantly in the gas industry because HDD provides a much more cost-effective and less disruptive method for gas pipe installation than older, trenching methods. However, there have been isolated strikes of underground utilities by HDD equipment, which may have been avoided if methods were available to detect other underground obstacles when using HDD systems. GTI advisors from the gas industry have ranked the value of solving the obstacle detection problem as the most important research and development project for GTI to pursue using Federal Energy Regulatory Commission (FERC) funds available through its industry partner, GRI. GTI proposes to develop a prototype down-hole sensor system that is simple and compact. The sensor utilizes an impedance measurement technique that is sensitive to the presence of metallic or nonmetallic objects in the proximity of the HDD head. The system will use a thin film sensor conformal with the drill head. The impedance of the soil will be measured with a low frequency signal injected through the drill head itself. A pair of bridge type impedance sensors, mounted orthogonal to one another, is capacitively coupled to the soil. Inclusions in the soil will cause changes to the sensor balance distinguishable from homogeneous soil. The sensor will provide range and direction data for obstacles near the HDD head. The goal is to provide a simple, robust system that provides the information required to avoid obstacles. This must be done within the size and ruggedness constraints of the HDD

  14. Method and Apparatus for Creating a Topography at a Surface

    Science.gov (United States)

    Adams, David P.; Sinclair, Michael B.; Mayer, Thomas M.; Vasile, Michael J.; Sweatt, William C.

    2008-11-11

    Methods and apparatus whereby an optical interferometer is utilized to monitor and provide feedback control to an integrated energetic particle column, to create desired topographies, including the depth, shape and/or roughness of features, at a surface of a specimen. Energetic particle columns can direct energetic species including, ions, photons and/or neutral particles to a surface to create features having in-plane dimensions on the order of 1 micron, and a height or depth on the order of 1 nanometer. Energetic processes can include subtractive processes such as sputtering, ablation, focused ion beam milling and, additive processes, such as energetic beam induced chemical vapor deposition. The integration of interferometric methods with processing by energetic species offers the ability to create desired topographies at surfaces, including planar and curved shapes.

  15. Multi-phase-field method for surface tension induced elasticity

    Science.gov (United States)

    Schiedung, Raphael; Steinbach, Ingo; Varnik, Fathollah

    2018-01-01

    A method, based on the multi-phase-field framework, is proposed that adequately accounts for the effects of a coupling between surface free energy and elastic deformation in solids. The method is validated via a number of analytically solvable problems. In addition to stress states at mechanical equilibrium in complex geometries, the underlying multi-phase-field framework naturally allows us to account for the influence of surface energy induced stresses on phase transformation kinetics. This issue, which is of fundamental importance on the nanoscale, is demonstrated in the limit of fast diffusion for a solid sphere, which melts due to the well-known Gibbs-Thompson effect. This melting process is slowed down when coupled to surface energy induced elastic deformation.

  16. Temperature sensitive surfaces and methods of making same

    Science.gov (United States)

    Liang, Liang [Richland, WA; Rieke, Peter C [Pasco, WA; Alford, Kentin L [Pasco, WA

    2002-09-10

    Poly-n-isopropylacrylamide surface coatings demonstrate the useful property of being able to switch charateristics depending upon temperature. More specifically, these coatings switch from being hydrophilic at low temperature to hydrophobic at high temperature. Research has been conducted for many years to better characterize and control the properties of temperature sensitive coatings. The present invention provides novel temperature sensitive coatings on articles and novel methods of making temperature sensitive coatings that are disposed on the surfaces of various articles. These novel coatings contain the reaction products of n-isopropylacrylamide and are characterized by their properties such as advancing contact angles. Numerous other characteristics such as coating thickness, surface roughness, and hydrophilic-to-hydrophobic transition temperatures are also described. The present invention includes articles having temperature-sensitve coatings with improved properties as well as improved methods for forming temperature sensitive coatings.

  17. Localized surface plasmon resonance mercury detection system and methods

    Science.gov (United States)

    James, Jay; Lucas, Donald; Crosby, Jeffrey Scott; Koshland, Catherine P.

    2016-03-22

    A mercury detection system that includes a flow cell having a mercury sensor, a light source and a light detector is provided. The mercury sensor includes a transparent substrate and a submonolayer of mercury absorbing nanoparticles, e.g., gold nanoparticles, on a surface of the substrate. Methods of determining whether mercury is present in a sample using the mercury sensors are also provided. The subject mercury detection systems and methods find use in a variety of different applications, including mercury detecting applications.

  18. Method and apparatus for aligning laser reflective surfaces

    International Nuclear Information System (INIS)

    Caruolo, A.B.; Davis, J.W.; Walch, A.P.

    1975-01-01

    Methods and apparatus used in the alignment of high power laser systems to obtain optimum performance are disclosed. An external source of visible radiation provides an alignment beam which is reflected along the axis of a resonator. Reflecting surfaces of the resonator are aligned with respect to the axis located by the visible beam

  19. An alternative safer and cost effective surface sterilization method for ...

    African Journals Online (AJOL)

    Regardless of its serious health effect, mercury chloride is frequently utilized for surface sterilization to mitigate microbial contamination in sugarcane tissue culture. The current study aimed at finding an alternative safer and cost effective sterilization method to substitute mercury chloride. In the study, sugarcane shoot tip ...

  20. Response surface method to optimize the low cost medium for ...

    African Journals Online (AJOL)

    A protease producing Bacillus sp. GA CAS10 was isolated from ascidian Phallusia arabica, Tuticorin, Southeast coast of India. Response surface methodology was employed for the optimization of different nutritional and physical factors for the production of protease. Plackett-Burman method was applied to identify ...

  1. Surface sterilization method for reducing microbial contamination of ...

    African Journals Online (AJOL)

    An effective disinfection method for strawberry (Fragaria x ananassa Duch.) cv. Senga Sengana micropropagation using runner tips and nodal segments as explants was developed. The explants were surface sterilized with different sterilants for different durations. The present studies on the effect of different regimes of ...

  2. Assessment methods of injection moulded nano-patterned surfaces

    DEFF Research Database (Denmark)

    Menotti, S.; Bisacco, G.; Hansen, H. N.

    2014-01-01

    algorithm for feature recognition. To compare the methods, the mould insert and a number of replicated nano-patterned surfaces, injection moulded with an induction heating aid, were measured on nominally identical locations by means of an atomic force microscope mounted on a manual CMM....

  3. An alternative safer and cost effective surface sterilization method for ...

    African Journals Online (AJOL)

    user

    2013-10-30

    Oct 30, 2013 ... Regardless of its serious health effect, mercury chloride is frequently utilized for surface sterilization to mitigate microbial contamination in sugarcane tissue culture. The current study aimed at finding an alternative safer and cost effective sterilization method to substitute mercury chloride. In the study,.

  4. Comparison of surface sampling methods for virus recovery from fomites.

    Science.gov (United States)

    Julian, Timothy R; Tamayo, Francisco J; Leckie, James O; Boehm, Alexandria B

    2011-10-01

    The role of fomites in infectious disease transmission relative to other exposure routes is difficult to discern due, in part, to the lack of information on the level and distribution of virus contamination on surfaces. Comparisons of studies intending to fill this gap are difficult because multiple different sampling methods are employed and authors rarely report their method's lower limit of detection. In the present study, we compare a subset of sampling methods identified from a literature review to demonstrate that sampling method significantly influences study outcomes. We then compare a subset of methods identified from the review to determine the most efficient methods for recovering virus from surfaces in a laboratory trial using MS2 bacteriophage as a model virus. Recoveries of infective MS2 and MS2 RNA are determined using both a plaque assay and quantitative reverse transcription-PCR, respectively. We conclude that the method that most effectively recovers virus from nonporous fomites uses polyester-tipped swabs prewetted in either one-quarter-strength Ringer's solution or saline solution. This method recovers a median fraction for infective MS2 of 0.40 and for MS2 RNA of 0.07. Use of the proposed method for virus recovery in future fomite sampling studies would provide opportunities to compare findings across multiple studies.

  5. SSC kicker impedances

    International Nuclear Information System (INIS)

    Colton, E.P.; Wang, T.F.

    1985-01-01

    The longitudinal and transverse complex impedances Z/sub l//n and Z/sub t/, respectively, have been calculated for both the SSC injection and abort kickers. The calculations assumed that no attempt was made to shield the beam from the kickers. We took the injection and abort kickers to be as specified. The injection kickers were ferrite with a single-turn design, and the abort kickers were of a ''window-frame design'' with tape wound cores

  6. Surface zwitterionization: Effective method for preventing oral bacterial biofilm formation on hydroxyapatite surfaces

    Science.gov (United States)

    Lee, Myoungjin; Kim, Heejin; Seo, Jiae; Kang, Minji; Kang, Sunah; Jang, Joomyung; Lee, Yan; Seo, Ji-Hun

    2018-01-01

    In this study, we conducted surface zwitterionization of hydroxyapatite (HA) surfaces by immersing them in the zwitterionic polymer solutions to provide anti-bacterial properties to the HA surface. Three different monomers containing various zwitterionic groups, i.e., phosphorylcholine (PC), sulfobetaine (SB), and carboxybetaine (CB), were copolymerized with the methacrylic monomer containing a Ca2+-binding moiety, using the free radical polymerization method. As a control, functionalization of the copolymer containing the Ca2+-binding moiety was synthesized using a hydroxy group. The stable immobilization of the zwitterionic functional groups was confirmed by water contact angle analysis and X-ray photoelectron spectroscopy (XPS) measurement conducted after the sonication process. The zwitterionized HA surface showed significantly decreased protein adsorption, whereas the hydroxyl group-coated HA surface showed limited efficacy. The anti-bacterial adhesion property was confirmed by conducting Streptococcus mutans (S. mutans) adhesion tests for 6 h and 24 h. When furanone C-30, a representative anti-quorum sensing molecule for S. mutans, was used, only a small amount of bacteria adhered after 6 h and the population did not increase after 24 h. In contrast, zwitterionized HA surfaces showed almost no bacterial adhesion after 6 h and the effect was retained for 24 h, resulting in the lowest level of oral bacterial adhesion. These results confirm that surface zwitterionization is a promising method to effectively prevent oral bacterial adhesion on HA-based materials.

  7. A novel test method for quantifying surface tack of polypropylene compound surfaces

    Directory of Open Access Journals (Sweden)

    2011-11-01

    Full Text Available While adhesiveness is required for polymer surfaces in special applications, tacky surfaces are generally undesirable in many applications like automotive interior parts. The tackiness of polymer surface results from a combination of composition and additivation, and it can change significantly in natural or accelerated ageing. Since there is no established, uniform method to characterize surface tack, the major focus of the present work was on the development of an objective quantification method. A setup having a soft die tip attached to a standard tensile tester was developed aiming for correlation to the human sense of touch. Three different model thermoplastic polyolefin (TPO compound formulations based on a high-impact isotactic polypropylene (iPP composition with varying amounts and types of anti-scratch additives were used for these investigations. As the surface tack phenomenon is related to ageing and weathering, the material’s examination was also performed after various intervals of weathering. The developed method allows a fast assessment of the effect of polymer composition variations and different additive formulations on surface tack and gives identical rankings as the standardized haptic panel.

  8. Forward problem solution as the operator of filtered and back projection matrix to reconstruct the various method of data collection and the object element model in electrical impedance tomography

    Energy Technology Data Exchange (ETDEWEB)

    Ain, Khusnul [Engineering Physics Program, ITB, Bandung - Indonesia (Indonesia); Physics Department - Airlangga University, Surabaya – Indonesia, khusnulainunair@yahoo.com (Indonesia); Kurniadi, Deddy; Suprijanto [Engineering Physics Program, ITB, Bandung - Indonesia (Indonesia); Santoso, Oerip [Informatics Program, ITB, Bandung - Indonesia (Indonesia); Wibowo, Arif [Physics Department - Airlangga University, Surabaya – Indonesia, khusnulainunair@yahoo.com (Indonesia)

    2015-04-16

    Back projection reconstruction has been implemented to get the dynamical image in electrical impedance tomography. However the implementation is still limited in method of adjacent data collection and circular object element model. The study aims to develop the methods of back projection as reconstruction method that has the high speed, accuracy, and flexibility, which can be used for various methods of data collection and model of the object element. The proposed method uses the forward problem solution as the operator of filtered and back projection matrix. This is done through a simulation study on several methods of data collection and various models of the object element. The results indicate that the developed method is capable of producing images, fastly and accurately for reconstruction of the various methods of data collection and models of the object element.

  9. An Electrochemical Impedance Spectroscopy Study on the Effects of the Surface- and Solution-Based Mechanisms in Li-O2Cells

    DEFF Research Database (Denmark)

    Knudsen, Kristian Bastholm; Vegge, Tejs; McCloskey, Bryan D.

    2016-01-01

    The maximum discharge capacity in non-aqueous Li-O2 batteries has been limited to a fraction of its theoretical value, largely due to a conformal deposition of Li2O2 on the cathode surface. However, it has recently been established that additives that increase the shielding of either O2− or Li...

  10. Advances in calibration methods for micro- and nanoscale surfaces

    Science.gov (United States)

    Leach, R. K.; Giusca, C. L.; Coupland, J. M.

    2012-04-01

    Optical surface topography measuring instrument manufacturers often quote accuracies of the order of nanometres and claim that the instruments can reliably measure a range of surfaces with structures on the micro- to nanoscale. However, for many years there has been debate about the interpretation of the data from optical surface topography measuring instruments. Optical artefacts in the output data and a lack of a calibration infrastructure mean that it can be difficult to get optical instruments to agree with contact stylus instruments. In this paper, the current situation with areal surface topography measurements is discussed along with the ISO specification standards that are in draft form. An infrastructure is discussed whereby the ISO-defined metrological characteristics of optical instruments can be determined, but these characteristics do not allow the instrument to measure complex surfaces. Current research into methods for determining the transfer function of optical instruments is reviewed, which will allow the calibration of optical instruments to measure complex surfaces, at least in the case of weak scattering. The ability of some optical instruments to measure outside the spatial bandwidth limitation of the numerical aperture is presented and some general outlook for future work given.

  11. Optical triangulation method for height measurements on water surfaces

    Science.gov (United States)

    Maas, Hans-Gerd; Hentschel, Bernd; Schreiber, Frank

    2003-01-01

    Optical triangulation methods based on a laser light sheet and a camera are frequently used as a surface measurement technique in a wide range of applications. They allow for the fast accurate determination of height profiles, based on relatively simple hardware and software configurations. Moreover, they can be implemented very efficiently and are especially suited for measurements on moving objects such as products on an assembly line. The study presented in the paper describes the adaptation of laser light sheet optical triangulation techniques to the task of water level profile measurements in hydromechanics experimental facilities. The properties of water surfaces necessitate several modifications of optical triangulation techniques to make them applicable: The mirror-like reflection properties of water surfaces form a contradiction to the assumption of diffuse reflection, on which standard light sheet triangulation techniques are based; this problem can be circumvented by using a diffuse reflecting projection plane to capture the mirror-like reflection of the laser line from the water surface. Due to the angle of incidence law, however, water surface tilts caused by waves will usually cause a strong degradation of the quality of the results when using reflected light; this effect can largely be compensated by processing max-store images derived from short image sequences rather than single images. These extensions of optical triangulation turned out to be crucial for the applicability of the method on water surfaces. Besides the theoretical concept and a sensitivity analysis of the method, a system configuration is outlined, and the results of a number of practical experiments are shown and discussed.

  12. Observations involving broadband impedance modelling

    Energy Technology Data Exchange (ETDEWEB)

    Berg, J.S. [Stanford Linear Accelerator Center, Menlo Park, CA (United States)

    1996-08-01

    Results for single- and multi-bunch instabilities can be significantly affected by the precise model that is used for the broadband impedance. This paper discusses three aspects of broadband impedance modelling. The first is an observation of the effect that a seemingly minor change in an impedance model has on the single-bunch mode coupling threshold. The second is a successful attempt to construct a model for the high-frequency tails of an r.f. cavity. The last is a discussion of requirements for the mathematical form of an impedance which follow from the general properties of impedances. (author)

  13. Method for Reduction of Silver Biocide Plating on Metal Surfaces

    Science.gov (United States)

    Steele, John; Nalette, Timothy; Beringer, Durwood

    2013-01-01

    Silver ions in aqueous solutions (0.05 to 1 ppm) are used for microbial control in water systems. The silver ions remain in solution when stored in plastic containers, but the concentration rapidly decreases to non-biocidal levels when stored in metal containers. The silver deposits onto the surface and is reduced to non-biocidal silver metal when it contacts less noble metal surfaces, including stainless steel, titanium, and nickel-based alloys. Five methods of treatment of contact metal surfaces to deter silver deposition and reduction are proposed: (1) High-temperature oxidation of the metal surface; (2) High-concentration silver solution pre-treatment; (3) Silver plating; (4) Teflon coat by vapor deposition (titanium only); and (5) A combination of methods (1) and (2), which proved to be the best method for the nickel-based alloy application. The mechanism associated with surface treatments (1), (2), and (5) is thought to be the development of a less active oxide layer that deters ionic silver deposition. Mechanism (3) is an attempt to develop an equilibrium ionic silver concentration via dissolution of metallic silver. Mechanism (4) provides a non-reactive barrier to deter ionic silver plating. Development testing has shown that ionic silver in aqueous solution was maintained at essentially the same level of addition (0.4 ppm) for up to 15 months with method (5) (a combination of methods (1) and (2)), before the test was discontinued for nickel-based alloys. Method (1) resulted in the maintenance of a biocidal level (approximately 0.05 ppm) for up to 10 months before that test was discontinued for nickel-based alloys. Methods (1) and (2) used separately were able to maintain ionic silver in aqueous solution at essentially the same level of addition (0.4 ppm) for up to 10 months before the test was discontinued for stainless steel alloys. Method (3) was only utilized for titanium alloys, and was successful at maintaining ionic silver in aqueous solution at

  14. Methods to study microbial adhesion on abiotic surfaces

    Directory of Open Access Journals (Sweden)

    Ana Meireles

    2015-09-01

    Full Text Available Microbial biofilms are a matrix of cells and exopolymeric substances attached to a wet and solid surface and are commonly associated to several problems, such as biofouling and corrosion in industries and infectious diseases in urinary catheters and prosthesis. However, these cells may have several benefits in distinct applications, such as wastewater treatment processes, microbial fuel cells for energy production and biosensors. As microbial adhesion is a key step on biofilm formation, it is very important to understand and characterize microbial adhesion to a surface. This study presents an overview of predictive and experimental methods used for the study of bacterial adhesion. Evaluation of surface physicochemical properties have a limited capacity in describing the complex adhesion process. Regarding the experimental methods, there is no standard method or platform available for the study of microbial adhesion and a wide variety of methods, such as colony forming units counting and microscopy techniques, can be applied for quantification and characterization of the adhesion process.

  15. Simulating condensation on microstructured surfaces using Lattice Boltzmann Method

    Science.gov (United States)

    Alexeev, Alexander; Vasyliv, Yaroslav

    2017-11-01

    We simulate a single component fluid condensing on 2D structured surfaces with different wettability. To simulate the two phase fluid, we use the athermal Lattice Boltzmann Method (LBM) driven by a pseudopotential force. The pseudopotential force results in a non-ideal equation of state (EOS) which permits liquid-vapor phase change. To account for thermal effects, the athermal LBM is coupled to a finite volume discretization of the temperature evolution equation obtained using a thermal energy rate balance for the specific internal energy. We use the developed model to probe the effect of surface structure and surface wettability on the condensation rate in order to identify microstructure topographies promoting condensation. Financial support is acknowledged from Kimberly-Clark.

  16. Facile stamp patterning method for superhydrophilic/superhydrophobic surfaces

    Energy Technology Data Exchange (ETDEWEB)

    Lyu, Sungnam, E-mail: blueden@postech.ac.kr; Hwang, Woonbong, E-mail: whwang@postech.ac.kr [Department of Mechanical Engineering, POSTECH, Pohang 680-749 (Korea, Republic of)

    2015-11-16

    Patterning techniques are essential to many research fields such as chemistry, biology, medicine, and micro-electromechanical systems. In this letter, we report a simple, fast, and low-cost superhydrophobic patterning method using a superhydrophilic template. The technique is based on the contact stamping of the surface during hydrophobic dip coating. Surface characteristics were measured using scanning electron microscopy and energy-dispersive X-ray spectroscopic analysis. The results showed that the hydrophilic template, which was contacted with the stamp, was not affected by the hydrophobic solution. The resolution study was conducted using a stripe shaped stamp. The patterned line was linearly proportional to the width of the stamp line with a constant narrowing effect. A surface with regions of four different types of wetting was fabricated to demonstrate the patterning performance.

  17. Scattering of surface waves modelled by the integral equation method

    Science.gov (United States)

    Lu, Laiyu; Maupin, Valerie; Zeng, Rongsheng; Ding, Zhifeng

    2008-09-01

    The integral equation method is used to model the propagation of surface waves in 3-D structures. The wavefield is represented by the Fredholm integral equation, and the scattered surface waves are calculated by solving the integral equation numerically. The integration of the Green's function elements is given analytically by treating the singularity of the Hankel function at R = 0, based on the proper expression of the Green's function and the addition theorem of the Hankel function. No far-field and Born approximation is made. We investigate the scattering of surface waves propagating in layered reference models imbedding a heterogeneity with different density, as well as Lamé constant contrasts, both in frequency and time domains, for incident plane waves and point sources.

  18. Response-Surface Methods in R, Using rsm

    Directory of Open Access Journals (Sweden)

    Russell V. Lenth

    2009-10-01

    Full Text Available This article describes the recent package rsm, which was designed to provide R support for standard response-surface methods. Functions are provided to generate central-composite and Box-Behnken designs. For analysis of the resulting data, the package provides for estimating the response surface, testing its lack of fit, displaying an ensemble of contour plots of the fitted surface, and doing follow-up analyses such as steepest ascent, canonical analysis, and ridge analysis. It also implements a coded-data structure to aid in this essential aspect of the methodology. The functions are designed in hopes of providing an intuitive and effective user interface. Potential exists for expanding the package in a variety of ways.

  19. Results from a Novel Method for Corrosion Studies of Electroplated Lithium Metal Based on Measurements with an Impedance Scanning Electrochemical Quartz Crystal Microbalance

    Directory of Open Access Journals (Sweden)

    Martin Winter

    2013-07-01

    Full Text Available A new approach to study the chemical stability of electrodeposited lithium on a copper metal substrate via measurements with a fast impedance scanning electrochemical quartz crystal microbalance is presented. The corrosion of electrochemically deposited lithium was compared in two different electrolytes, based on lithium difluoro(oxalato borate (LiDFOB and lithium hexafluorophosphate, both salts being dissolved in solvent blends of ethylene carbonate and diethyl carbonate. For a better understanding of the corrosion mechanisms, scanning electron microscopy images of electrodeposited lithium were also consulted. The results of the EQCM experiments were supported by AC impedance measurements and clearly showed two different corrosion mechanisms caused by the different salts and the formed SEIs. The observed mass decrease of the quartz sensor of the LiDFOB-based electrolyte is not smooth, but rather composed of a series of abrupt mass fluctuations in contrast to that of the lithium hexafluorophosphate-based electrolyte. After each slow decrease of mass a rather fast increase of mass is observed several times. The slow mass decrease can be attributed to a consolidation process of the SEI or to the partial dissolution of the SEI leaving finally lithium metal unprotected so that a fast film formation sets in entailing the observed fast mass increases.

  20. Exploration on Kerf-angle and Surface Roughness in Abrasive Waterjet Machining using Response Surface Method

    Science.gov (United States)

    Babu, Munuswamy Naresh; Muthukrishnan, Nambi

    2017-05-01

    Abrasive waterjet machining is a mechanical based unconventional cutting process which uses a mixture of abrasives and pressurized water as an intermediate to cut the material. The present paper focuses in analyzing the effect process parameters like feed rate, water pressure, standoff distance and abrasive flow rate on the surface roughness and kerf-angle of AISI 1018 mild steel experimentally. The experiments were performed under Taguchi's L27 orthogonal array. Moreover, the optimal parameter that significantly reduces the surface roughness and kerf-angle were calculated through response surface method. The most dominating process parameter that affects the responses was calculated by the Analysis of variance. In addition, machined surfaces are further subjected to scanning electron microscope (SEM) and atomic force microscope (AFM) for detailed study on the texture developed.

  1. Modeling and Grid impedance Variation Analysis of Parallel Connected Grid Connected Inverter based on Impedance Based Harmonic Analysis

    DEFF Research Database (Denmark)

    Kwon, JunBum; Wang, Xiongfei; Bak, Claus Leth

    2014-01-01

    This paper addresses the harmonic compensation error problem existing with parallel connected inverter in the same grid interface conditions by means of impedance-based analysis and modeling. Unlike the single grid connected inverter, it is found that multiple parallel connected inverters and grid...... impedance can make influence to each other if they each have a harmonic compensation function. The analysis method proposed in this paper is based on the relationship between the overall output impedance and input impedance of parallel connected inverter, where controller gain design method, which can...

  2. Sound radiation contrast in MR phase images. Method for the representation of elasticity, sound damping, and sound impedance changes; Schallstrahlungskontrast in MR-Phasenbildern. Methode zur Darstellung von Elastizitaets-, Schalldaempfungs- und Schallimpedanzaenderungen

    Energy Technology Data Exchange (ETDEWEB)

    Radicke, Marcus

    2009-12-18

    The method presented in this thesis combines ultrasound techniques with the magnetic-resonance tomography (MRT). An ultrasonic wave generates in absorbing media a static force in sound-propagation direction. The force leads at sound intensities of some W/cm{sup 2} and a sound frequency in the lower MHz range to a tissue shift in the micrometer range. This tissue shift depends on the sound power, the sound frequency, the sound absorption, and the elastic properties of the tissue. A MRT sequence of the Siemens Healthcare AG was modified so that it measures (indirectly) the tissue shift, codes as grey values, and presents as 2D picture. By means of the grey values the sound-beam slope in the tissue can be visualized, and so additionally sound obstacles (changes of the sound impedance) can be detected. By the MRT images token up spatial changes of the tissue parameters sound absorption and elasticity can be detected. In this thesis measurements are presented, which show the feasibility and future chances of this method especially for the mammary-cancer diagnostics. [German] Die in dieser Arbeit praesentierte Methode kombiniert Ultraschalltechniken mit der Magnetresonanztomographie (MRT). Eine Ultraschallwelle ruft in absorbierenden Medien eine statische Kraft in Schallausbreitungsrichtung hervor. Die Kraft fuehrt bei Schallintensitaeten von einigen W/cm{sup 2} und einer Schallfrequenz im niederen MHz-Bereich zu einer Gewebeverschiebung im Mikrometerbereich. Diese Gewebeverschiebung haengt ab von der Schallleistung, der Schallfrequenz, der Schallabsorption und den elastischen Eigenschaften des Gewebes. Es wurde eine MRT-Sequenz der Siemens Healthcare AG modifiziert, so dass sie (indirekt) die Gewebeverschiebung misst, als Grauwerte kodiert und als 2D-Bild darstellt. Anhand der Grauwerte kann der Schallstrahlverlauf in dem Gewebe visualisiert werden, und so koennen zusaetzlich Schallhindernisse (Aenderungen der Schallkennimpedanz) aufgespuert werden. Mit den

  3. LIA longitudinal coupling impedance

    International Nuclear Information System (INIS)

    Faltens, A.

    1980-01-01

    The beam generated fields enter into the problems of waveform generation and longitudinal stability. In the former, provision must be made for the longitudinally defocusing forces due to the space charge and the beam loading effects on the accelerating voltage due to the current of a presumably known bunch. In the latter, the concern is for the growth of unintentional perturbations to unacceptably large values through the interaction of the charge and current fluctuations with the rest of the beam and the surrounding structures. These beam generated electric fields may be related to the beam current through a coupling impedance

  4. Theoretical studies of potential energy surfaces and computational methods

    Energy Technology Data Exchange (ETDEWEB)

    Shepard, R. [Argonne National Laboratory, IL (United States)

    1993-12-01

    This project involves the development, implementation, and application of theoretical methods for the calculation and characterization of potential energy surfaces involving molecular species that occur in hydrocarbon combustion. These potential energy surfaces require an accurate and balanced treatment of reactants, intermediates, and products. This difficult challenge is met with general multiconfiguration self-consistent-field (MCSCF) and multireference single- and double-excitation configuration interaction (MRSDCI) methods. In contrast to the more common single-reference electronic structure methods, this approach is capable of describing accurately molecular systems that are highly distorted away from their equilibrium geometries, including reactant, fragment, and transition-state geometries, and of describing regions of the potential surface that are associated with electronic wave functions of widely varying nature. The MCSCF reference wave functions are designed to be sufficiently flexible to describe qualitatively the changes in the electronic structure over the broad range of geometries of interest. The necessary mixing of ionic, covalent, and Rydberg contributions, along with the appropriate treatment of the different electron-spin components (e.g. closed shell, high-spin open-shell, low-spin open shell, radical, diradical, etc.) of the wave functions, are treated correctly at this level. Further treatment of electron correlation effects is included using large scale multireference CI wave functions, particularly including the single and double excitations relative to the MCSCF reference space. This leads to the most flexible and accurate large-scale MRSDCI wave functions that have been used to date in global PES studies.

  5. Comparison of optical methods for surface roughness characterization

    DEFF Research Database (Denmark)

    Feidenhans'l, Nikolaj Agentoft; Hansen, Poul Erik; Pilny, Lukas

    2015-01-01

    We report a study of the correlation between three optical methods for characterizing surface roughness: a laboratory scatterometer measuring the bi-directional reflection distribution function (BRDF instrument), a simple commercial scatterometer (rBRDF instrument), and a confocal optical profiler...... of the scattering angle distribution (Aq). The twenty-two investigated samples were manufactured with several methods in order to obtain a suitable diversity of roughness patterns.Our study shows a one-to-one correlation of both the Rq and the Rdq roughness values when obtained with the BRDF and the confocal...

  6. Delta self-consistent field method to obtain potential energy surfaces of excited molecules on surfaces

    DEFF Research Database (Denmark)

    Gavnholt, Jeppe; Olsen, Thomas; Engelund, Mads

    2008-01-01

    is a density-functional method closely resembling standard density-functional theory (DFT), the only difference being that in Delta SCF one or more electrons are placed in higher lying Kohn-Sham orbitals instead of placing all electrons in the lowest possible orbitals as one does when calculating the ground......-photoemission spectroscopy measurements. This comparison shows that the modified Delta SCF method gives results in close agreement with experiment, significantly closer than the comparable methods. For N2 adsorbed on ruthenium (0001) we map out a two-dimensional part of the potential energy surfaces in the ground state...

  7. TWO METHODS FOR REMOTE ESTIMATION OF COMPLETE URBAN SURFACE TEMPERATURE

    Directory of Open Access Journals (Sweden)

    L. Jiang

    2017-09-01

    Full Text Available Complete urban surface temperature (TC is a key parameter for evaluating the energy exchange between the urban surface and atmosphere. At the present stage, the estimation of TC still needs detailed 3D structure information of the urban surface, however, it is often difficult to obtain the geometric structure and composition of the corresponding temperature of urban surface, so that there is still lack of concise and efficient method for estimating the TC by remote sensing. Based on the four typical urban surface scale models, combined with the Envi-met model, thermal radiant directionality forward modeling and kernel model, we analyzed a complete day and night cycle hourly component temperature and radiation temperature in each direction of two seasons of summer and winter, and calculated hemispherical integral temperature and TC. The conclusion is obtained by examining the relationship of directional radiation temperature, hemispherical integral temperature and TC: (1 There is an optimal angle of radiation temperature approaching the TC in a single observation direction when viewing zenith angle is 45–60°, the viewing azimuth near the vertical surface of the sun main plane, the average absolute difference is about 1.1 K in the daytime. (2 There are several (3–5 times directional temperatures of different view angle, under the situation of using the thermal radiation directionality kernel model can more accurately calculate the hemispherical integral temperature close to TC, the mean absolute error is about 1.0 K in the daytime. This study proposed simple and effective strategies for estimating TC by remote sensing, which are expected to improve the quantitative level of remote sensing of urban thermal environment.

  8. Two Methods for Remote Estimation of Complete Urban Surface Temperature

    Science.gov (United States)

    Jiang, L.; Zhan, W.; Zou, Z.

    2017-09-01

    Complete urban surface temperature (TC) is a key parameter for evaluating the energy exchange between the urban surface and atmosphere. At the present stage, the estimation of TC still needs detailed 3D structure information of the urban surface, however, it is often difficult to obtain the geometric structure and composition of the corresponding temperature of urban surface, so that there is still lack of concise and efficient method for estimating the TC by remote sensing. Based on the four typical urban surface scale models, combined with the Envi-met model, thermal radiant directionality forward modeling and kernel model, we analyzed a complete day and night cycle hourly component temperature and radiation temperature in each direction of two seasons of summer and winter, and calculated hemispherical integral temperature and TC. The conclusion is obtained by examining the relationship of directional radiation temperature, hemispherical integral temperature and TC: (1) There is an optimal angle of radiation temperature approaching the TC in a single observation direction when viewing zenith angle is 45-60°, the viewing azimuth near the vertical surface of the sun main plane, the average absolute difference is about 1.1 K in the daytime. (2) There are several (3-5 times) directional temperatures of different view angle, under the situation of using the thermal radiation directionality kernel model can more accurately calculate the hemispherical integral temperature close to TC, the mean absolute error is about 1.0 K in the daytime. This study proposed simple and effective strategies for estimating TC by remote sensing, which are expected to improve the quantitative level of remote sensing of urban thermal environment.

  9. Battery Internal Temperature Estimation for LiFePO4 Battery Based on Impedance Phase Shift under Operating Conditions

    Directory of Open Access Journals (Sweden)

    Jiangong Zhu

    2017-01-01

    Full Text Available An impedance-based temperature estimation method is investigated considering the electrochemical non-equilibrium with short-term relaxation time for facilitating the vehicular application. Generally, sufficient relaxation time is required for battery electrochemical equilibrium before the impedance measurement. A detailed experiment is performed to investigate the regularity of the battery impedance in short-term relaxation time after switch-off current excitation, which indicates that the impedance can be measured and also has systematical decrement with the relaxation time growth. Based on the discussion of impedance variation in electrochemical perspective, as well as the monotonic relationship between impedance phase shift and battery internal temperature in the electrochemical equilibrium state, an exponential equation that accounts for both measured phase shift and relaxation time is established to correct the measuring deviation caused by electrochemical non-equilibrium. Then, a multivariate linear equation coupled with ambient temperature is derived considering the temperature gradients between the active part and battery surface. Equations stated above are all identified with the embedded thermocouple experimentally. In conclusion, the temperature estimation method can be a valuable alternative for temperature monitoring during cell operating, and serve the functionality as an efficient implementation in battery thermal management system for electric vehicles (EVs and hybrid electric vehicles (HEVs.

  10. Broadband impedance of the NESTOR storage ring

    International Nuclear Information System (INIS)

    Androsov, V.P.; Gladkikh, P.I.; Gvozd, A.M.; Karnaukhov, I.M.; Telegin, Yu.N.

    2011-01-01

    The contributions from lossy and inductive vacuum chamber components to the broadband impedance of the NESTOR storage ring are obtained by using both low-frequency analytical approaches and computer simulations. As was expected considering the small ring circumference (15.44m), the main contributions both to the longitudinal impedance Z || /n and the loss factor k loss come from the RF-cavity. Cavity impedance was also estimated with CST Microwave Studio (CST Studio Suite TM 2006) by simulating coaxial wire method commonly used for impedance measurements. Both estimates agree well. Finally, we performed the simulations of a number of inductive elements with CST Particle Studio 2010 by using wake field solver. We have also evaluated the bunch length in NESTOR taking the conservative estimate of 3 Ohm for the ring broadband impedance and have found that the bunch length s z = 0.5 cm could be obtained in steady state operation mode for the designed bunch current of 10 mA and RF-voltage of 250 kV.

  11. Evaluation of ring impedance of the Photon Factory storage ring

    International Nuclear Information System (INIS)

    Kiuchi, T.; Izawa, M.; Tokumoto, S.; Hori, Y.; Sakanaka, S.; Kobayashi, M.; Kobayakawa, H.

    1992-05-01

    The loss parameters of the ducts in the Photon Factory (PF) storage ring were evaluated using the wire method and the code TBCI. Both the measurement and the calculation were done for a different bunch length (σ) ranging from 23 to 80 ps. The PF ring impedance was estimated to be |Z/n|=3.2 Ω using the broadband impedance model. The major contribution to the impedance comes from the bellows and the gate valve sections. Improvements of these components will lower the ring impedance by half. (author)

  12. Electrode contact impedance sensitivity to variations in geometry

    International Nuclear Information System (INIS)

    Cardu, Roberto; Leong, Philip H W; Jin, Craig T; McEwan, Alistair

    2012-01-01

    Electrode contact impedance is a crucial factor in physiological measurements and can be an accuracy-limiting factor when performing electroencephalography and electrical impedance tomography. In this work, standard flat electrodes and micromachined multipoint spiked electrodes are characterized with a finite-element method electromagnetic solver and the dependence of the contact impedance on geometrical factors is explored. It is found that flat electrodes are sensitive to changes in the outer skin layer properties related to hydration and thickness, while spike electrodes are not. The impedance as a function of the effective contact area, number of spikes and penetration depth has also been studied and characterized. (paper)

  13. Passivation of mechanically polished, chemically etched and anodized zirconium in various aqueous solutions: Impedance measurements

    International Nuclear Information System (INIS)

    Abo-Elenien, G.M.; Abdel-Salam, O.E.

    1987-01-01

    Zirconium and its alloys are finding increasing applications especially in water-cooled nuclear reactors. Because of the fact that zirconium is electronegative (E 0 = -1.529V) its corrosion resistance in aqueous solutions is largely determined by the existence of a thin oxide film on its surface. The structure and properties of this film depend in the first place on the method of surface pre-treatment. This paper presents an experimental study of the nature of the oxide film on mechanically polished, chemically etched and anodized zirconium. Ac impedance measurements carried out in various acidic, neutral and alkaline solutions show that the film thickness depends on the method of surface pre-treatment and the type of electrolyte solution. The variation of the potential and impedance during anodization of zirconium at low current density indicates that the initial stages of polarization consist of oxide build-up at a rate dependent on the nature of the electrode surface and the electrolyte. Oxygen evolution commences at a stage where oxide thickening starts to decline. The effect of frequency on the measured impedance indicates that the surface reactivity, and hence the corrosion rate, decreases in the following order: mechanically polished > chemically etched > anodized

  14. Non thermal plasma surface cleaner and method of use

    KAUST Repository

    Neophytou, Marios

    2017-09-14

    Described herein are plasma generation devices and methods of use of the devices. The devices can be used for the cleaning of various surfaces and/or for inhibiting or preventing the accumulation of particulates, such as dust, or moisture on various surfaces. The devices can be used to remove dust and other particulate contaminants from solar panels and windows, or to avoid or minimize condensation on various surfaces. In an embodiment a plasma generation device is provided. The plasma generation device can comprise: a pair of electrodes (1,2) positioned in association with a surface of a dielectric substrate (3). The pair of electrodes (1,2) can comprise a first electrode (1) and a second electrode (2). The first electrode and second electrode can be of different sizes, one of the electrodes being smaller than the other of the electrodes. The first electrode and second electrode can be separated by a distance and electrically connected to a voltage source (4,5).

  15. Impedance plethysmographic observations in thoracic outlet syndrome.

    Directory of Open Access Journals (Sweden)

    Nerurkar S

    1990-07-01

    Full Text Available Forty patients with symptoms of neuro-vascular compression in the upper extremities were subjected to impedance plethysmographic study using Parulkar′s method. Two patients recorded decreased blood flow (BFI in supine position and were diagnosed as having partial occlusion at subclavian level. Sixteen of the patients recorded decreased BFI on 90 degrees abduction and hyper-abduction. Twelve of these patients had radiological evidence of anomalous cervicle ribs. In remaining four patients extrinsic impression on the subclavian artery due to fibrous deposits was confirmed by arteriography. Remaining 22 patients recorded normal impedance plethysmograms. Impedance plethysmography thus provided a non-invasive modality for confirmation of vascular compression in thoracic outlet syndrome.

  16. Body fat estimation using bioelectrical impedance.

    Science.gov (United States)

    Shaikh, M G; Crabtree, N J; Shaw, N J; Kirk, J M W

    2007-01-01

    Although childhood obesity is a major problem, routine assessment methods do not reflect fat mass. Body mass index, which is most commonly used, gives an indication of weight for height and not a degree of adiposity. Bioelectrical impedance and dual-energy X-ray absorptiometry (DEXA) were used in a group of obese children to assess body fat. Comparison between DEXA and commercial bioelectrical impedance scales in 46 children showed a highly significant correlation (R = 0.944, p bioelectrical impedance was 2.4 kg lower compared to measurement using DEXA. These bioelectrical scales may prove useful in the management of childhood obesity as they are able to provide important clinical information regarding fat mass and adiposity. Copyright 2007 S. Karger AG, Basel.

  17. Determination of corrosion rate by ac impedance

    Energy Technology Data Exchange (ETDEWEB)

    Novitskii, V.S.; Orishchenko, M.Ya.; Kuzub, V.S.

    1988-07-01

    Computerized graphical and chemical analyses were used to study the effect of frequency on corrosion impedance for the systems: Armco iron/H/sub 2/SO/sub 4/ and St3 steel/H/sub 2/SO/sub 4/ with and without the addition of propargyl alcohol inhibitor, St3/NaCl, and St3/circulated water. The Epelboin equation for the effect of frequency on the impedance of anodic iron dissolution in sulfuric acid was confirmed between 10/sup /minus/2/ and 10/sup /minus/3/ Hz. The equation was analyzed theoretically. Corrosion rates found by extrapolating low-frequency conductance to zero frequency, with correction for nonlinearity, agreed with rates obtained gravimetrically with a root-mean-square deviation of no more than 20%. The impedance method was found to be useful for continuously monitoring corrosion rates in industry.

  18. Physical and chemical characterization methods of surfaces and interfaces; Methodes de caracterisation physico-chimique des surfaces et des interfaces

    Energy Technology Data Exchange (ETDEWEB)

    Barthes-Labrousse, M.G. [Centre d`Etudes de Chimie Metallurgique, 94 - Vitry-sur-Seine (France)

    1997-12-31

    The main physical and chemical characterization techniques of surfaces and interfaces are presented. There are: Auger electron spectroscopy, photoelectron spectroscopies (XPS and UPS), secondary ions mass spectroscopy (SIMS), infrared and Raman spectroscopies, electron energy loss spectroscopy (EELS and HREELS) and atomic force microscopy (AFM). For each method is given the theoretical principle, the apparatus and the main uses of the techniques. (O.M.) 27 refs.

  19. Surface charge method for molecular surfaces with curved areal elements I. Spherical triangles

    Science.gov (United States)

    Yu, Yi-Kuo

    2018-03-01

    Parametrizing a curved surface with flat triangles in electrostatics problems creates a diverging electric field. One way to avoid this is to have curved areal elements. However, charge density integration over curved patches appears difficult. This paper, dealing with spherical triangles, is the first in a series aiming to solve this problem. Here, we lay the ground work for employing curved patches for applying the surface charge method to electrostatics. We show analytically how one may control the accuracy by expanding in powers of the the arc length (multiplied by the curvature). To accommodate not extremely small curved areal elements, we have provided enough details to include higher order corrections that are needed for better accuracy when slightly larger surface elements are used.

  20. A novel method for recording neuronal depolarization with recording at 125-825 Hz: implications for imaging fast neural activity in the brain with electrical impedance tomography.

    Science.gov (United States)

    Oh, T; Gilad, O; Ghosh, A; Schuettler, M; Holder, D S

    2011-05-01

    Electrical impedance tomography (EIT) is a recently developed medical imaging method which has the potential to produce images of fast neuronal depolarization in the brain. Previous modelling suggested that applied current needed to be below 100 Hz but the signal-to-noise ratio (SNR) recorded with scalp electrodes during evoked responses was too low to permit imaging. A novel method in which contemporaneous evoked potentials are subtracted is presented with current applied at 225 Hz to cerebral cortex during evoked activity; although the signal is smaller than at DC by about 10×, the principal noise from the EEG is reduced by about 1000×, resulting in an improved SNR. It was validated with recording of compound action potentials in crab walking leg nerve where peak changes of -0.2% at 125 and 175 Hz tallied with biophysical modelling. In recording from rat cerebral cortex during somatosensory evoked responses, peak impedance decreases of -0.07 ± 0.006% (mean ± SE) with a SNR of >50 could be recorded at 225 Hz. This method provides a reproducible and artefact free means for recording resistance changes during neuronal activity which could form the basis for imaging fast neural activity in the brain.

  1. Bioelectrical Impedance and Body Composition Assessment

    Science.gov (United States)

    Martino, Mike

    2006-01-01

    This article discusses field tests that can be used in physical education programs. The most common field tests are anthropometric measurements, which include body mass index (BMI), girth measurements, and skinfold testing. Another field test that is gaining popularity is bioelectrical impedance analysis (BIA). Each method has particular strengths…

  2. impedance calculations of induction machine rotor conductors.

    African Journals Online (AJOL)

    Dr Obe

    This paper describes a method of' calculating the impedance of Rectangular and Trapezoidal rotor bars. An R-L parallel network is used to model each of the Rotor bars. A computer optimisation Algorithm is developed and from which the Rotor circuit parameters at several frequencies are estimated. The model solutions ...

  3. impedance calculations of induction machine rotor conductors.

    African Journals Online (AJOL)

    Dr Obe

    ABSTRACT. The exact calculation of the impedance of induction machine rotor conductors at several operating frequencies are necessary if the dynamic behaviour of the machine is to give a good correlation between the simulated starting torque and current and the experimental results. This paper describes a method of'.

  4. New method to design stellarator coils without the winding surface

    Science.gov (United States)

    Zhu, Caoxiang; Hudson, Stuart R.; Song, Yuntao; Wan, Yuanxi

    2018-01-01

    Finding an easy-to-build coils set has been a critical issue for stellarator design for decades. Conventional approaches assume a toroidal ‘winding’ surface, but a poorly chosen winding surface can unnecessarily constrain the coil optimization algorithm, This article presents a new method to design coils for stellarators. Each discrete coil is represented as an arbitrary, closed, one-dimensional curve embedded in three-dimensional space. A target function to be minimized that includes both physical requirements and engineering constraints is constructed. The derivatives of the target function with respect to the parameters describing the coil geometries and currents are calculated analytically. A numerical code, named flexible optimized coils using space curves (FOCUS), has been developed. Applications to a simple stellarator configuration, W7-X and LHD vacuum fields are presented.

  5. A new method for patterning azopolymer thin film surfaces

    Science.gov (United States)

    Sorkhabi, Sh. Golghasemi; Barille, R.; Ahmadi-Kandjani, S.; Zielinska, S.; Ortyl, E.

    2017-04-01

    We present a simple bottom-up approach via an incoherent unpolarized illumination and the choice of a solvent-droplet-induced-dewetting method to photoinduce nano doughnuts on the surface of azopolymer thin films. We demonstrate that doughnut-shaped nanostructures can be formed and tailored with a wide range of typical sizes, thus providing a rich field of applications using surface photo-patterning. Furthermore, due to the presence of highly photoactive azobenzene derivative in the material, illumination of these nanostructures by a polarized laser light shows the possibility of a further growth and reshaping opening the way for fundamental studies of size-dependent scaling laws of optical properties and possible fabrication of nano-reactor or nano-trap patterns.

  6. Economic method for helical gear flank surface characterisation

    Science.gov (United States)

    Koulin, G.; Reavie, T.; Frazer, R. C.; Shaw, B. A.

    2018-03-01

    Typically the quality of a gear pair is assessed based on simplified geometric tolerances which do not always correlate with functional performance. In order to identify and quantify functional performance based parameters, further development of the gear measurement approach is required. Methodology for interpolation of the full active helical gear flank surface, from sparse line measurements, is presented. The method seeks to identify the minimum number of line measurements required to sufficiently characterise an active gear flank. In the form ground gear example presented, a single helix and three profile line measurements was considered to be acceptable. The resulting surfaces can be used to simulate the meshing engagement of a gear pair and therefore provide insight into functional performance based parameters. Therefore the assessment of the quality can be based on the predicted performance in the context of an application.

  7. An experimental method for making spectral emittance and surface temperature measurements of opaque surfaces

    International Nuclear Information System (INIS)

    Moore, Travis J.; Jones, Matthew R.; Tree, Dale R.; Daniel Maynes, R.; Baxter, Larry L.

    2011-01-01

    An experimental procedure has been developed to make spectral emittance and temperature measurements. The spectral emittance of an object is calculated using measurements of the spectral emissive power and of the surface temperature of the object obtained using a Fourier transform infrared (FTIR) spectrometer. A calibration procedure is described in detail which accounts for the temperature dependence of the detector. The methods used to extract the spectral emissive power and surface temperature from measured infrared spectra were validated using a blackbody radiator at known temperatures. The average error in the measured spectral emittance was 2.1% and the average difference between the temperature inferred from the recorded spectra and the temperature indicated on the blackbody radiator was 1.2%. The method was used to measure the spectral emittance of oxidized copper at various temperatures.

  8. Roman sophisticated surface modification methods to manufacture silver counterfeited coins

    Science.gov (United States)

    Ingo, G. M.; Riccucci, C.; Faraldi, F.; Pascucci, M.; Messina, E.; Fierro, G.; Di Carlo, G.

    2017-11-01

    By means of the combined use of X-ray photoelectron spectroscopy (XPS), optical microscopy (OM) and scanning electron microscopy (SEM) coupled with energy dispersive X-ray spectroscopy (EDS) the surface and subsurface chemical and metallurgical features of silver counterfeited Roman Republican coins are investigated to decipher some aspects of the manufacturing methods and to evaluate the technological ability of the Roman metallurgists to produce thin silver coatings. The results demonstrate that over 2000 ago important advances in the technology of thin layer deposition on metal substrates were attained by Romans. The ancient metallurgists produced counterfeited coins by combining sophisticated micro-plating methods and tailored surface chemical modification based on the mercury-silvering process. The results reveal that Romans were able systematically to chemically and metallurgically manipulate alloys at a micro scale to produce adherent precious metal layers with a uniform thickness up to few micrometers. The results converge to reveal that the production of forgeries was aimed firstly to save expensive metals as much as possible allowing profitable large-scale production at a lower cost. The driving forces could have been a lack of precious metals, an unexpected need to circulate coins for trade and/or a combinations of social, political and economic factors that requested a change in money supply. Finally, some information on corrosion products have been achieved useful to select materials and methods for the conservation of these important witnesses of technology and economy.

  9. Electrical impedance tomography.

    Science.gov (United States)

    Costa, Eduardo L V; Lima, Raul Gonzalez; Amato, Marcelo B P

    2009-02-01

    Electrical impedance tomography (EIT) is a noninvasive, radiation-free monitoring tool that allows real-time imaging of ventilation. The purpose of this article is to discuss the fundamentals of EIT and to review the use of EIT in critical care patients. In addition to its established role in describing the distribution of alveolar ventilation, EIT has been shown to be a useful tool to detect lung collapse and monitor lung recruitment, both regionally and on a global basis. EIT has also been used to diagnose with high sensitivity incident pneumothoraces during mechanical ventilation. Additionally, with injection of hypertonic saline as a contrast agent, it is possible to estimate ventilation/perfusion distributions. EIT is cheap, noninvasive and allows continuous monitoring of ventilation. It is gaining acceptance as a valuable monitoring tool for the care of critical patients.

  10. Methods on estimation of the evaporation from water surface

    International Nuclear Information System (INIS)

    Trajanovska, Lidija; Tanushevska, Dushanka; Aleksovska, Nina

    2001-01-01

    The whole world water supply on the Earth is in close dependence on hydrological cycle connected with water circulation at Earth-Atmosphere route through evaporation, precipitation and water runoff. Evaporation exists worldwide where the atmosphere is unsatiated of water steam (when there is humidity in short supply) and it depends on climatic conditions in some regions. The purpose of this paper is to determine a method for estimation of evaporation of natural water surface in our areas, that means its determination as exact as possible. (Original)

  11. Something different - caching applied to calculation of impedance matrix elements

    CSIR Research Space (South Africa)

    Lysko, AA

    2012-09-01

    Full Text Available (N). The method requires only minor modifications of an existing code, and has been realized in Matlab. The tests confirmed validity of the method and showed doubling the speed of filling the impedance matrix in....

  12. Evaluation of surface renewal and flux-variance methods above agricultural and forest surfaces

    Science.gov (United States)

    Fischer, M.; Katul, G. G.; Noormets, A.; Poznikova, G.; Domec, J. C.; Trnka, M.; King, J. S.

    2016-12-01

    Measurements of turbulent surface energy fluxes are of high interest in agriculture and forest research. During last decades, eddy covariance (EC), has been adopted as the most commonly used micrometeorological method for measuring fluxes of greenhouse gases, energy and other scalars at the surface-atmosphere interface. Despite its robustness and accuracy, the costs of EC hinder its deployment at some research experiments and in practice like e.g. for irrigation scheduling. Therefore, testing and development of other cost-effective methods is of high interest. In our study, we tested performance of surface renewal (SR) and flux variance method (FV) for estimates of sensible heat flux density. Surface renewal method is based on the concept of non-random transport of scalars via so-called coherent structures which if accurately identified can be used for the computing of associated flux. Flux variance method predicts the flux from the scalar variance following the surface-layer similarity theory. We tested SR and FV against EC in three types of ecosystem with very distinct aerodynamic properties. First site was represented by agricultural wheat field in the Czech Republic. The second site was a 20-m tall mixed deciduous wetland forest on the coast of North Carolina, USA. The third site was represented by pine-switchgrass intercropping agro-forestry system located in coastal plain of North Carolina, USA. Apart from solving the coherent structures in a SR framework from the structure functions (representing the most common approach), we applied ramp wavelet detection scheme to test the hypothesis that the duration and amplitudes of the coherent structures are normally distributed within the particular 30-minutes time intervals and so just the estimates of their averages is sufficient for the accurate flux determination. Further, we tested whether the orthonormal wavelet thresholding can be used for isolating of the coherent structure scales which are associated with

  13. Comparison of dimensionality reduction methods for wood surface inspection

    Science.gov (United States)

    Niskanen, Matti; Silven, Olli

    2003-04-01

    Dimensionality reduction methods for visualization map the original high-dimensional data typically into two dimensions. Mapping preserves the important information of the data, and in order to be useful, fulfils the needs of a human observer. We have proposed a self-organizing map (SOM)- based approach for visual surface inspection. The method provides the advantages of unsupervised learning and an intuitive user interface that allows one to very easily set and tune the class boundaries based on observations made on visualization, for example, to adapt to changing conditions or material. There are, however, some problems with a SOM. It does not address the true distances between data, and it has a tendency to ignore rare samples in the training set at the expense of more accurate representation of common samples. In this paper, some alternative methods for a SOM are evaluated. These methods, PCA, MDS, LLE, ISOMAP, and GTM, are used to reduce dimensionality in order to visualize the data. Their principal differences are discussed and performances quantitatively evaluated in a few special classification cases, such as in wood inspection using centile features. For the test material experimented with, SOM and GTM outperform the others when classification performance is considered. For data mining kinds of applications, ISOMAP and LLE appear to be more promising methods.

  14. A new surface resistance measurement method with ultrahigh sensitivity

    International Nuclear Information System (INIS)

    Liang, Changnian.

    1993-01-01

    A superconducting niobium triaxial cavity has been designed and fabricated to study residual surface resistance of planar superconducting materials. The edge of a 25.4 mm or larger diameter sample in the triaxial cavity is located outside the strong field region. Therefore, the edge effects and possible losses between the thin film and the substrate have been minimized, ensuring that induced RF losses are intrinsic to the test material. The fundamental resonant frequency of the cavity is the same as the working frequency of CEBAF cavities. The cavity has a compact size compared to its TE 011 counterpart, which makes it more sensitive to the sample's loss. For even higher sensitivity, a calorimetry method has been used to measure the RF losses on the superconducting sample. At 2 K, a 2 μK temperature change can be resolved by using carbon resistor sensors. The temperature distribution caused by RF heating is measured by 16 carbon composition resistor sensors. A 0.05 μW heating power can be detected as such a resolution, which translates to a surface resistance of 0.02 nΩ at a surface magnetic field of 52 Oe. This is the most sensitive device for surface resistance measurements to date. In addition, losses due to the indium seal, coupling probes, field emission sites other than the sample, and all of the high field resonator surface, are excluded in the measurement. Surface resistance of both niobium and high-Tc superconducting thin films has been measured. A low R s of 35.2 μΩ was measured for a 25.4 mm diameter YBa 2 Cu 3 O 7 thin film at 1.5 GHz and at 2 K. The measurement result is the first result for a large area epitaxially grown thin film sample at such a low RF frequency. The abrupt disappearance of multipacting between two parallel plates has been observed and monitored with the 16 temperature mapping sensors. Field emission or some field dependent anomalous RF losses on the niobium plate have also been observed

  15. Development on electromagnetic impedance function modeling and its estimation

    International Nuclear Information System (INIS)

    Sutarno, D.

    2015-01-01

    Today the Electromagnetic methods such as magnetotellurics (MT) and controlled sources audio MT (CSAMT) is used in a broad variety of applications. Its usefulness in poor seismic areas and its negligible environmental impact are integral parts of effective exploration at minimum cost. As exploration was forced into more difficult areas, the importance of MT and CSAMT, in conjunction with other techniques, has tended to grow continuously. However, there are obviously important and difficult problems remaining to be solved concerning our ability to collect process and interpret MT as well as CSAMT in complex 3D structural environments. This talk aim at reviewing and discussing the recent development on MT as well as CSAMT impedance functions modeling, and also some improvements on estimation procedures for the corresponding impedance functions. In MT impedance modeling, research efforts focus on developing numerical method for computing the impedance functions of three dimensionally (3-D) earth resistivity models. On that reason, 3-D finite elements numerical modeling for the impedances is developed based on edge element method. Whereas, in the CSAMT case, the efforts were focused to accomplish the non-plane wave problem in the corresponding impedance functions. Concerning estimation of MT and CSAMT impedance functions, researches were focused on improving quality of the estimates. On that objective, non-linear regression approach based on the robust M-estimators and the Hilbert transform operating on the causal transfer functions, were used to dealing with outliers (abnormal data) which are frequently superimposed on a normal ambient MT as well as CSAMT noise fields. As validated, the proposed MT impedance modeling method gives acceptable results for standard three dimensional resistivity models. Whilst, the full solution based modeling that accommodate the non-plane wave effect for CSAMT impedances is applied for all measurement zones, including near-, transition

  16. Development on electromagnetic impedance function modeling and its estimation

    Energy Technology Data Exchange (ETDEWEB)

    Sutarno, D., E-mail: Sutarno@fi.itb.ac.id [Earth Physics and Complex System Division Faculty of Mathematics and Natural Sciences Institut Teknologi Bandung (Indonesia)

    2015-09-30

    Today the Electromagnetic methods such as magnetotellurics (MT) and controlled sources audio MT (CSAMT) is used in a broad variety of applications. Its usefulness in poor seismic areas and its negligible environmental impact are integral parts of effective exploration at minimum cost. As exploration was forced into more difficult areas, the importance of MT and CSAMT, in conjunction with other techniques, has tended to grow continuously. However, there are obviously important and difficult problems remaining to be solved concerning our ability to collect process and interpret MT as well as CSAMT in complex 3D structural environments. This talk aim at reviewing and discussing the recent development on MT as well as CSAMT impedance functions modeling, and also some improvements on estimation procedures for the corresponding impedance functions. In MT impedance modeling, research efforts focus on developing numerical method for computing the impedance functions of three dimensionally (3-D) earth resistivity models. On that reason, 3-D finite elements numerical modeling for the impedances is developed based on edge element method. Whereas, in the CSAMT case, the efforts were focused to accomplish the non-plane wave problem in the corresponding impedance functions. Concerning estimation of MT and CSAMT impedance functions, researches were focused on improving quality of the estimates. On that objective, non-linear regression approach based on the robust M-estimators and the Hilbert transform operating on the causal transfer functions, were used to dealing with outliers (abnormal data) which are frequently superimposed on a normal ambient MT as well as CSAMT noise fields. As validated, the proposed MT impedance modeling method gives acceptable results for standard three dimensional resistivity models. Whilst, the full solution based modeling that accommodate the non-plane wave effect for CSAMT impedances is applied for all measurement zones, including near-, transition

  17. Journal and Wave Bearing Impedance Calculation Software

    Science.gov (United States)

    Hanford, Amanda; Campbell, Robert

    2012-01-01

    The wave bearing software suite is a MALTA application that computes bearing properties for user-specified wave bearing conditions, as well as plain journal bearings. Wave bearings are fluid film journal bearings with multi-lobed wave patterns around the circumference of the bearing surface. In this software suite, the dynamic coefficients are outputted in a way for easy implementation in a finite element model used in rotor dynamics analysis. The software has a graphical user interface (GUI) for inputting bearing geometry parameters, and uses MATLAB s structure interface for ease of interpreting data. This innovation was developed to provide the stiffness and damping components of wave bearing impedances. The computational method for computing bearing coefficients was originally designed for plain journal bearings and tilting pad bearings. Modifications to include a wave bearing profile consisted of changing the film thickness profile given by an equation, and writing an algorithm to locate the integration limits for each fluid region. Careful consideration was needed to implement the correct integration limits while computing the dynamic coefficients, depending on the form of the input/output variables specified in the algorithm.

  18. Improved Decoupling for 13C coil Arrays Using Non-Conventional Matching and Preamplifier Impedance

    DEFF Research Database (Denmark)

    Sanchez, Juan Diego; Johansen, Daniel Højrup; Hansen, Rie Beck

    In this study, we describe a method to obtain improved preamplifier decoupling for receive-only coils. The method relies on the better decoupling obtained when coils are matched to an impedance higher than 50 . Preamplifiers with inductive imaginary impedance and low real impedance, increase...

  19. On-line monitoring of the crystallization process: relationship between crystal size and electrical impedance spectra

    International Nuclear Information System (INIS)

    Zhao, Yanlin; Yao, Jun; Wang, Mi

    2016-01-01

    On-line monitoring of crystal size in the crystallization process is crucial to many pharmaceutical and fine-chemical industrial applications. In this paper, a novel method is proposed for the on-line monitoring of the cooling crystallization process of L-glutamic acid (LGA) using electrical impedance spectroscopy (EIS). The EIS method can be used to monitor the growth of crystal particles relying on the presence of an electrical double layer on the charged particle surface and the polarization of double layer under the excitation of alternating electrical field. The electrical impedance spectra and crystal size were measured on-line simultaneously by an impedance analyzer and focused beam reflectance measurement (FBRM), respectively. The impedance spectra were analyzed using the equivalent circuit model and the equivalent circuit elements in the model can be obtained by fitting the experimental data. Two equivalent circuit elements, including capacitance ( C 2 ) and resistance ( R 2 ) from the dielectric polarization of the LGA solution and crystal particle/solution interface, are in relation with the crystal size. The mathematical relationship between the crystal size and the equivalent circuit elements can be obtained by a non-linear fitting method. The function can be used to predict the change of crystal size during the crystallization process. (paper)

  20. Evaluation of Surface Treatment Methods on the Bond Strength of Zirconia Ceramics Systems, Resin Cements and Tooth Surface

    Directory of Open Access Journals (Sweden)

    Akkuş Emek

    2015-07-01

    Full Text Available Objectives: To compare the effects of airborne-particle abrasion (APA and tribochemical silica coating (TSC surface treatment methods on the shear bond strength of zirconia ceramics systems, resin cements and tooth surface

  1. Ultra-wideband impedance sensor

    Science.gov (United States)

    McEwan, T.E.

    1999-03-16

    The ultra-wideband impedance sensor (UWBZ sensor, or Z-sensor) is implemented in differential and single-ended configurations. The differential UWBZ sensor employs a sub-nanosecond impulse to determine the balance of an impedance bridge. The bridge is configured as a differential sample-and-hold circuit that has a reference impedance side and an unknown impedance side. The unknown impedance side includes a short transmission line whose impedance is a function of the near proximity of objects. The single-ended UWBZ sensor eliminates the reference side of the bridge and is formed of a sample and hold circuit having a transmission line whose impedance is a function of the near proximity of objects. The sensing range of the transmission line is bounded by the two-way travel time of the impulse, thereby eliminating spurious Doppler modes from large distant objects that would occur in a microwave CW impedance bridge. Thus, the UWBZ sensor is a range-gated proximity sensor. The Z-sensor senses the near proximity of various materials such as metal, plastic, wood, petroleum products, and living tissue. It is much like a capacitance sensor, yet it is impervious to moisture. One broad application area is the general replacement of magnetic sensors, particularly where nonferrous materials need to be sensed. Another broad application area is sensing full/empty levels in tanks, vats and silos, e.g., a full/empty switch in water or petroleum tanks. 2 figs.

  2. A plateau-valley separation method for multifunctional surfaces characterization

    DEFF Research Database (Denmark)

    Godi, Alessandro; Kühle, A.; De Chiffre, Leonardo

    2012-01-01

    Turned multifunctional surfaces are a new typology of textured surfaces presenting a flat plateau region and deterministically distributed lubricant reservoirs. Existing standards are not suitable for the characterization of such surfaces, providing at times values without physical meaning. A new...

  3. Impedance Source Power Electronic Converters

    DEFF Research Database (Denmark)

    Liu, Yushan; Abu-Rub, Haitham; Ge, Baoming

    Impedance Source Power Electronic Converters brings together state of the art knowledge and cutting edge techniques in various stages of research related to the ever more popular impedance source converters/inverters. Significant research efforts are underway to develop commercially viable...... and technically feasible, efficient and reliable power converters for renewable energy, electric transportation and for various industrial applications. This book provides a detailed understanding of the concepts, designs, controls, and application demonstrations of the impedance source converters/inverters. Key...... features: Comprehensive analysis of the impedance source converter/inverter topologies, including typical topologies and derived topologies. Fully explains the design and control techniques of impedance source converters/inverters, including hardware design and control parameter design for corresponding...

  4. Multifrequency electrical impedance tomography using spectral constraints.

    Science.gov (United States)

    Malone, Emma; Sato Dos Santos, Gustavo; Holder, David; Arridge, Simon

    2014-02-01

    Multifrequency electrical impedance tomography (MFEIT) exploits the dependence of tissue impedance on frequency to recover an image of conductivity. MFEIT could provide emergency diagnosis of pathologies such as acute stroke, brain injury and breast cancer. We present a method for performing MFEIT using spectral constraints. Boundary voltage data is employed directly to reconstruct the volume fraction distribution of component tissues using a nonlinear method. Given that the reconstructed parameter is frequency independent, this approach allows for the simultaneous use of all multifrequency data, thus reducing the degrees of freedom of the reconstruction problem. Furthermore, this method allows for the use of frequency difference data in a nonlinear reconstruction algorithm. Results from empirical phantom measurements suggest that our fraction reconstruction method points to a new direction for the development of multifrequency EIT algorithms in the case that the spectral constraints are known, and may provide a unifying framework for static EIT imaging.

  5. Comparison of Abdominal Visceral Adipose Tissue Area Measured by Computed Tomography with That Estimated by Bioelectrical Impedance Analysis Method in Korean Subjects.

    Science.gov (United States)

    Lee, Dong-Hwa; Park, Kyeong Seon; Ahn, Soyeon; Ku, Eu Jeong; Jung, Kyong Yeun; Kim, Yoon Ji; Kim, Kyoung Min; Moon, Jae Hoon; Choi, Sung Hee; Park, Kyong Soo; Jang, Hak Chul; Lim, Soo

    2015-12-16

    We evaluated the concordance between visceral fat area (VFA) estimated by bioelectrical impedance analysis (BIA) or computed tomography (CT) in Korean subjects with a wide range in age and body mass index (BMI). In 1006 individuals (mean age 55.2 ± 11.8 (19-87) years, mean BMI 26.0 ± 3.5 (17-46) kg/m², 48.9% men), VFA quantified by CT was compared with VFA using multifrequency BIA machines within 15 days. Concordance rates were compared by age or BMI using correlation analysis, Bland-Altman plots, and intraclass correlation coefficient (ICC). Using BIA data, we established a regression formula to reflect CT-VFA. The mean VFAs by CT and BIA were 131.9 ± 57.3 cm² and 110.5 ± 33.9 cm², respectively (r = 0.605, p < 0.001). The mean difference was 21.4 ± 45.6 cm², tending to increase with BMI. In women with BMI <25 kg/m² or age <50 years, the VFAs by BIA were similar to those by CT (ICC = 0.496 in BMI <25 kg/m² and ICC = 0.638 in age <50 years). However, the difference was greater in men with BMI ≥25 kg/m² or age ≥50 years. Applying our formula, the difference between estimations decreased to 0.2 ± 38.2cm². VFA estimated by BIA correlated well with that by CT, but a more accurate formula is needed to match CT data, particularly in older men or subjects with a high BMI.

  6. Modern Trends in Imaging XI: Impedance Measurements in the Biomedical Sciences

    Directory of Open Access Journals (Sweden)

    Frederick D. Coffman

    2012-01-01

    Full Text Available Biological organisms and their component organs, tissues and cells have unique electrical impedance properties. Impedance properties often change with changes in structure, composition, and metabolism, and can be indicative of the onset and progression of disease states. Over the past 100 years, instruments and analytical methods have been developed to measure the impedance properties of biological specimens and to utilize these measurements in both clinical and basic science settings. This chapter will review the applications of impedance measurements in the biomedical sciences, from whole body analysis to impedance measurements of single cells and cell monolayers, and how cellular impedance measuring instruments can now be used in high throughput screening applications.

  7. Adaptive control of grid-connected inverters based on online grid impedance measurements

    Energy Technology Data Exchange (ETDEWEB)

    Cespedes, Mauricio; Sun, Jian [Rensselaer Polytechnic Institute, Troy, NY (United States). Dept. of Electrical, Computer and Systems Engineering

    2012-07-01

    Stability of a grid-connected inverter depends on the ratio of the grid impedance to the inverter impedance. Since the grid impedance changes during normal power system conditions, this paper uses first an impulse response analysis method built into a grid-connected inverter for online grid impedance identification. Secondly, in order to develop simple adaptation rules for the inverter control system, the grid impedance is assumed inductive, and used to derive, analytically, the stability limits of PLL bandwidth and grid voltage feedforward gains. Experimental measurements demonstrate the online grid impedance identification and the inverter adaptive control implemented together within the DSP of a three-phase grid-connected inverter. (orig.)

  8. Detecting stochastic inclusions in electrical impedance tomography

    Science.gov (United States)

    Barth, Andrea; Harrach, Bastian; Hyvönen, Nuutti; Mustonen, Lauri

    2017-11-01

    This work considers the inclusion detection problem of electrical impedance tomography with stochastic conductivities. It is shown that a conductivity anomaly with a random conductivity can be identified by applying the factorization method or the monotonicity method to the mean value of the corresponding Neumann-to-Dirichlet map provided that the anomaly has high enough contrast in the sense of expectation. The theoretical results are complemented by numerical examples in two spatial dimensions.

  9. Low profile conformal antenna arrays on high impedance substrate

    CERN Document Server

    Singh, Hema; Jha, Rakesh Mohan

    2016-01-01

    This book presents electromagnetic (EM) design and analysis of dipole antenna array over high impedance substrate (HIS). HIS is a preferred substrate for low-profile antenna design, owing to its unique boundary conditions. Such substrates permit radiating elements to be printed on them without any disturbance in the radiation characteristics. Moreover HIS provides improved impedance matching, enhanced bandwidth, and increased broadside directivity owing to total reflection from the reactive surface and high input impedance. This book considers different configurations of HIS for array design on planar and non-planar high-impedance surfaces. Results are presented for cylindrical dipole, printed dipole, and folded dipole over single- and double-layered square-patch-based HIS and dogbone-based HIS. The performance of antenna arrays is analyzed in terms of performance parameters such as return loss and radiation pattern. The design presented shows acceptable return loss and mainlobe gain of radiation pattern. Thi...

  10. Impedance of Surface Footings on Layered Ground

    DEFF Research Database (Denmark)

    Andersen, Lars; Clausen, Johan

    2008-01-01

    Traditionally only the static bearing capacity and stiffness of the ground is considered in the design of wind turbine foundations. However, modern wind turbines are flexible structures with resonance frequencies as low as 0.2 Hz. Unfortunately, environmental loads and the passage of blades past...

  11. Impedance of Surface Footings on Layered Ground

    DEFF Research Database (Denmark)

    Andersen, Lars; Clausen, Johan Christian

    2005-01-01

    Traditionally only the static bearing capacity and stiffness of the ground is considered in the design of wind turbine foundations. However, modern wind turbines are flexible structures with resonance frequencies as low as 0.2 Hz. Unfortunately, environmental loads and the passage of blades past...

  12. Biological methods used to assess surface water quality

    Directory of Open Access Journals (Sweden)

    Szczerbiñska Natalia

    2015-12-01

    Full Text Available In accordance with the guidelines of the Water Framework Directive 2000/60 (WFD, both ecological and chemical statuses determine the assessment of surface waters. The profile of ecological status is based on the analysis of various biological components, and physicochemical and hydromorphological indicators complement this assessment. The aim of this article is to present the biological methods used in the assessment of water status with a special focus on bioassay, as well as to provide a review of methods of monitoring water status. Biological test methods include both biomonitoring and bioanalytics. Water biomonitoring is used to assess and forecast the status of water. These studies aim to collect data on water pollution and forecast its impact. Biomonitoring uses organisms which are characterized by particular vulnerability to contaminants. Bioindicator organisms are algae, fungi, bacteria, larval invertebrates, cyanobacteria, macroinvertebrates, and fish. Bioanalytics is based on the receptors of contaminants that can be biologically active substances. In bioanalytics, biosensors such as viruses, bacteria, antibodies, enzymes, and biotests are used to assess degrees of pollution.

  13. Integral methods for shallow free-surface flows with separation

    DEFF Research Database (Denmark)

    Watanabe, S.; Putkaradze, V.; Bohr, Tomas

    2003-01-01

    eddy and separated flow. Assuming a variable radial velocity profile as in Karman-Pohlhausen's method, we obtain a system of two ordinary differential equations for stationary states that can smoothly go through the jump. Solutions of the system are in good agreement with experiments. For the flow down...... an inclined plane we take a similar approach and derive a simple model in which the velocity profile is not restricted to a parabolic or self-similar form. Two types of solutions with large surface distortions are found: solitary, kink-like propagating fronts, obtained when the flow rate is suddenly changed......, and stationary jumps, obtained, for instance, behind a sluice gate. We then include time dependence in the model to study the stability of these waves. This allows us to distinguish between sub- and supercritical flows by calculating dispersion relations for wavelengths of the order of the width of the layer....

  14. Method for producing high surface area chromia materials for catalysis

    Science.gov (United States)

    Gash, Alexander E [Brentwood, CA; Satcher, Joe [Patterson, CA; Tillotson, Thomas [Tracy, CA; Hrubesh, Lawrence [Pleasanton, CA; Simpson, Randall [Livermore, CA

    2007-05-01

    Nanostructured chromium(III)-oxide-based materials using sol-gel processing and a synthetic route for producing such materials are disclosed herein. Monolithic aerogels and xerogels having surface areas between 150 m.sup.2/g and 520 m.sup.2/g have been produced. The synthetic method employs the use of stable and inexpensive hydrated-chromium(III) inorganic salts and common solvents such as water, ethanol, methanol, 1-propanol, t-butanol, 2-ethoxy ethanol, and ethylene glycol, DMSO, and dimethyl formamide. The synthesis involves the dissolution of the metal salt in a solvent followed by an addition of a proton scavenger, such as an epoxide, which induces gel formation in a timely manner. Both critical point (supercritical extraction) and atmospheric (low temperature evaporation) drying may be employed to produce monolithic aerogels and xerogels, respectively.

  15. Application of Electrochemical Impedance Spectroscopy for Fuel Cell Characterization

    OpenAIRE

    Wagner, N.

    2010-01-01

    Theory of impedance spectra measured at fuel cells with electrodes changing their state with time e.g. anode surface changing during CO poisoning of PEFC anodes and water flooding of the cathode during “dead end” operation mode of the PEFC are discussed in the presentation. Also first experimental results of locally resolved EIS measured simultaneously on 5 cells of a SOFC stack will be presented and discussed. For the evaluation of the measured impedance spectra a porous electrode model w...

  16. Modified surface testing method for large convex aspheric surfaces based on diffraction optics.

    Science.gov (United States)

    Zhang, Haidong; Wang, Xiaokun; Xue, Donglin; Zhang, Xuejun

    2017-12-01

    Large convex aspheric optical elements have been widely applied in advanced optical systems, which have presented a challenging metrology problem. Conventional testing methods cannot satisfy the demand gradually with the change of definition of "large." A modified method is proposed in this paper, which utilizes a relatively small computer-generated hologram and an illumination lens with certain feasibility to measure the large convex aspherics. Two example systems are designed to demonstrate the applicability, and also, the sensitivity of this configuration is analyzed, which proves the accuracy of the configuration can be better than 6 nm with careful alignment and calibration of the illumination lens in advance. Design examples and analysis show that this configuration is applicable to measure the large convex aspheric surfaces.

  17. Structural identification and damage diagnosis using self-sensing piezo-impedance transducers

    Science.gov (United States)

    Lim, Yee Yan; Bhalla, Suresh; Kiong Soh, Chee

    2006-08-01

    The use of smart materials, such as lead zirconate titanate (PZT), has accelerated developments in the fields of structural identification and automated structural health monitoring (SHM). One such technique that has made much progress is the electro-mechanical impedance (EMI) technique, which employs self-sensing piezo-impedance transducers. In this technique, a PZT patch is surface bonded to the structure to be monitored and its corresponding electro-mechanical admittance signature is used for damage detection. This paper introduces a new method for identifying structures from the measured admittance signatures in terms of equivalent structural parameters, whereby the identified parameters are used for damage characterization. The new method has been applied to a truss, a beam and a concrete cube, and found to be able to successfully perform structural identification and damage diagnosis. In addition, several advantages have been ascertained in comparison with the conventional, non-parametric statistical methods.

  18. Development of galvanostatic Fourier transform electrochemical impedance spectroscopy.

    Science.gov (United States)

    Nam, Kwang-Mo; Shin, Dong-Hyup; Jung, Namchul; Joo, Moon G; Jeon, Sangmin; Park, Su-Moon; Chang, Byoung-Yong

    2013-02-19

    Here, we report development of the galvanostatic Fourier transform electrochemical impedance spectroscopy (FTEIS), which monitors impedance of electrochemical reactions activated by current steps. We first derive relevant relations for potential change upon application of a step current, obtain impedances theoretically from the relations by simulation, and verify them with experimental results. The validity of the galvanostatic FTEIS technique is demonstrated by measuring impedances of a semiconductive silicon wafer using the conventional frequency response analysis (FRA), the potentiostatic FTEIS, and the galvanostatic FTEIS methods, and the results are in excellent agreement with each other. This work is significant in that the galvanostatic FTEIS would allow one to record impedance changes during charge/discharge cycles of secondary batteries and fuel cells as well as electrochemically irreversible systems which may produce noise level chronoamperometric currents by potentiostatic techniques.

  19. Advanced impedance modeling of solid oxide electrochemical cells

    DEFF Research Database (Denmark)

    Graves, Christopher R.; Hjelm, Johan

    2014-01-01

    Impedance spectroscopy is a powerful technique for detailed study of the electrochemical and transport processes that take place in fuel cells and electrolysis cells, including solid oxide cells (SOCs). Meaningful analysis of impedance measurements is nontrivial, however, because a large number...... techniques to provide good guesses for the modeling parameters, like transforming the impedance data to the distribution of relaxation times (DRT), together with experimental parameter sensitivity studies, is the state-of-the-art approach to achieve good EC model fits. Here we present new impedance modeling......) constraining the parameter values during fitting to ranges of physically reasonable values. Using these methods, the number of fitting parameters for four impedance spectra measured with isolated changes to the fuel and oxidant gas compositions, has been reduced from 80 to 21-34 depending on the model...

  20. Modeling the Impedance of Nanostructured PV in Simulink/matlab

    Science.gov (United States)

    Houshmand, Mohammad; Zandi, Mohammad. H.; Gorji, Nima E.

    2013-08-01

    Impedance measurement is a common method to study the electrical properties of thin film photovoltaics. For the first time, we use the MATLAB/Simulink environment to extract the complex impedance of the nanostructured heterojunction solar cells. The impedance magnitude, phase and Nyquist plot of the PV are simulated in LTI Viewer and Impedance versus Frequency analysis tools of SimPower GUI block of Simulink. We examined a variety of the equivalent circuits consisting of capacitance, series and shunt resistances representing the solar cell structure. The model uses the parameters with values reported in the literature at room temperature and zero bias. The effect of the additional capacitance and resistances in the equivalent circuits on the impedance components of the cells is considered by Simulink environment.

  1. Impedance pneumography using textile electrodes.

    Science.gov (United States)

    Fiedler, P; Biller, S; Griebel, S; Haueisen, J

    2012-01-01

    The acquisition of physiological parameters using textile and textile-integrated sensors has become an important alternative for mobile and long-term monitoring. We analyzed to different commercially available electrically conductive textiles concerning their applicability for textile-based impedance pneumography. We immersed the textiles to four corroding solutions and observed no considerable changes in the absolute value as well as the phase shift of the material impedances. Subsequently, we performed impedance pneumography tests with different current amplitudes and frequencies. Using silver coated synthetic textile electrodes it was possible to detect the correct respiration frequency during normal, flat as well as slow, deep respiration.

  2. Development of impedance matching technologies for ICRF antenna arrays

    Energy Technology Data Exchange (ETDEWEB)

    Pinsker, R.I.

    1998-03-01

    All high power ICRF heating systems include devices for matching the input impedance of the antenna array to the generator output impedance. For most types of antennas used, the input impedance is strongly time-dependent on timescales as rapid as 10-4 s, while the rf generators used are capable of producing full power only into a stationary load impedance. Hence, the dynamic response of the matching method is of great practical importance. In this paper, world-wide developments in this field over the past decade are reviewed. These techniques may be divided into several classes. The edge plasma parameters that determine the antenna array`s input impedance may be controlled to maintain a fixed load impedance. The frequency of the rf source can be feedback controlled to compensate for changes in the edge plasma conditions, or fast variable tuning elements in the transmission line between the generator output and the antenna input connections can provide the necessary time-varying impedance transformation. In lossy passive schemes, reflected power due to the time-varying impedance of the antenna array is diverted to a dummy load. Each of these techniques can be applied to a pre-existing antenna system. If a new antenna is to be designed, recent advances allow the antenna array to have the intrinsic property of presenting a constant load to the feeding transmission lines despite the varying load seen by each antenna in the array.

  3. Impedance Immunsensor Based on Interdigitated Array Microelectrode and its Experiment Parameter Optimization

    Directory of Open Access Journals (Sweden)

    Wen Ping Zhao

    2014-05-01

    Full Text Available This article accounts for a novel impedance immunosensor based on the specificity reaction of the antigen-antibody and the sensitivity of the interdigitated array microelectrode (IDAM for the determination of chlorpyrifos residues. The basic knowledge of immunoassay was in relation to its IDAM electrode surface modification, antibody immobilization, bovine serum albumin (BSA blocking and sample detection. The SPA was dropped onto the surface of IDAM electrode, used for binding antibody Fc fragments. Next, antibody was immobilized on the SPA modified electrode. Finally, BSA was employed to block the possible remaining active sites avoiding any nonspecific adsorption. Target chlorpyrifos was then captured by the immobilized antibody, resulting in a change in the impedance of the IDAM microelectrode surface. The fabrication procedure of the immunosensor and the sample detection were characterized by electrochemical impedance spectroscopy (EIS. The influences of the experiment parameters were investigated. Under optimized conditions, an excellent biosensor was fabricated. Many of the antibodies, enzymes and other reagents integral to immunoassays were very expensive, often hundreds of dollars per milligram, therefore miniaturization reduces reagent costs drastically. In this article the volume of the reagents was micro upgrade, the antibodies, SPA and BSA were 30 mL, the chlorpyrifos sample and detection solution were 50mL. The advantages of the immunosensor were exhibited in its better specificity, stability, selectivity and regeneration. The proposed method was proven to be a feasible quantitative method for chlorpyrifos analysis in vegetables and fruits.

  4. Rapid surface enhanced Raman scattering detection method for chloramphenicol residues

    Science.gov (United States)

    Ji, Wei; Yao, Weirong

    2015-06-01

    Chloramphenicol (CAP) is a widely used amide alcohol antibiotics, which has been banned from using in food producing animals in many countries. In this study, surface enhanced Raman scattering (SERS) coupled with gold colloidal nanoparticles was used for the rapid analysis of CAP. Density functional theory (DFT) calculations were conducted with Gaussian 03 at the B3LYP level using the 3-21G(d) and 6-31G(d) basis sets to analyze the assignment of vibrations. Affirmatively, the theoretical Raman spectrum of CAP was in complete agreement with the experimental spectrum. They both exhibited three strong peaks characteristic of CAP at 1104 cm-1, 1344 cm-1, 1596 cm-1, which were used for rapid qualitative analysis of CAP residues in food samples. The use of SERS as a method for the measurements of CAP was explored by comparing use of different solvents, gold colloidal nanoparticles concentration and absorption time. The method of the detection limit was determined as 0.1 μg/mL using optimum conditions. The Raman peak at 1344 cm-1 was used as the index for quantitative analysis of CAP in food samples, with a linear correlation of R2 = 0.9802. Quantitative analysis of CAP residues in foods revealed that the SERS technique with gold colloidal nanoparticles was sensitive and of a good stability and linear correlation, and suited for rapid analysis of CAP residue in a variety of food samples.

  5. Constrained MRI Impedance Imaging

    National Research Council Canada - National Science Library

    Plewes, Donald

    2002-01-01

    An approach for imaging electric tissue properties in vivo is proposed. The technique relies upon the integration of MRI data with electrical potential measurements made over the surface of the patient...

  6. Method for Qualification of Coatings Applied to Wet Surfaces

    Science.gov (United States)

    2009-12-16

    The field application of a pipeline repair or rehabilitation coating usually cannot wait until ambient conditions become optimal. In a humid environment, water can condense on the pipe surface because the pipe surface is usually cooler than the ambie...

  7. The Influence of Segmental Impedance Analysis in Predicting Validity of Consumer Grade Bioelectrical Impedance Analysis Devices

    Science.gov (United States)

    Sharp, Andy; Heath, Jennifer; Peterson, Janet

    2008-05-01

    Consumer grade bioelectric impedance analysis (BIA) instruments measure the body's impedance at 50 kHz, and yield a quick estimate of percent body fat. The frequency dependence of the impedance gives more information about the current pathway and the response of different tissues. This study explores the impedance response of human tissue at a range of frequencies from 0.2 - 102 kHz using a four probe method and probe locations standard for segmental BIA research of the arm. The data at 50 kHz, for a 21 year old healthy Caucasian male (resistance of 180φ±10 and reactance of 33φ±2) is in agreement with previously reported values [1]. The frequency dependence is not consistent with simple circuit models commonly used in evaluating BIA data, and repeatability of measurements is problematic. This research will contribute to a better understanding of the inherent difficulties in estimating body fat using consumer grade BIA devices. [1] Chumlea, William C., Richard N. Baumgartner, and Alex F. Roche. ``Specific resistivity used to estimate fat-free mass from segmental body measures of bioelectrical impedance.'' Am J Clin Nutr 48 (1998): 7-15.

  8. Response Surface Methods For Spatially-Resolved Optical Measurement Techniques

    Science.gov (United States)

    Danehy, P. M.; Dorrington, A. A.; Cutler, A. D.; DeLoach, R.

    2003-01-01

    Response surface methods (or methodology), RSM, have been applied to improve data quality for two vastly different spatially-resolved optical measurement techniques. In the first application, modern design of experiments (MDOE) methods, including RSM, are employed to map the temperature field in a direct-connect supersonic combustion test facility at NASA Langley Research Center. The laser-based measurement technique known as coherent anti-Stokes Raman spectroscopy (CARS) is used to measure temperature at various locations in the combustor. RSM is then used to develop temperature maps of the flow. Even though the temperature fluctuations at a single point in the flowfield have a standard deviation on the order of 300 K, RSM provides analytic fits to the data having 95% confidence interval half width uncertainties in the fit as low as +/- 30 K. Methods of optimizing future CARS experiments are explored. The second application of RSM is to quantify the shape of a 5-meter diameter, ultra-lightweight, inflatable space antenna at NASA Langley Research Center. Photogrammetry is used to simultaneously measure the shape of the antenna at approximately 500 discrete spatial locations. RSM allows an analytic model to be developed that describes the shape of the majority of the antenna with an uncertainty of 0.4 mm, with 95% confidence. This model would allow a quantitative comparison between the actual shape of the antenna and the original design shape. Accurately determining this shape also allows confident interpolation between the measured points. Such a model could, for example, be used for ray tracing of radio-frequency waves up to 95 GHz. to predict the performance of the antenna.

  9. Sound reflection in an acoustic impedance tube terminated with a loudspeaker shunted by a negative impedance converter

    International Nuclear Information System (INIS)

    Černík, M; Mokrý, P

    2012-01-01

    A system for the absorption of sound at the termination of an acoustic tube using an electrodynamic loudspeaker connected to a shunt circuit is presented. A theoretical model of the electrodynamic loudspeaker in the acoustic tube is used for the calculation of the frequency dependence of the ideal shunt circuit impedance, which yields perfect sound absorption in broad frequency range. It is shown that both the real and imaginary parts of the shunt circuit impedance must be negative in the considered system. The required negative values of the shunt circuit impedance are achieved using a negative impedance converter. Frequency dependences of the reflection coefficient were measured in the acoustic impedance tube using the two-microphone transfer function method. Greatly reduced values of sound absorption coefficient were achieved in a narrow frequency range. The stability, applicability of the sound absorption system, and broadening its frequency range are discussed. (paper)

  10. ROUGHNESS ON WOOD SURFACES AND ROUGHNESS MEASUREMENT METHODS

    OpenAIRE

    İsmail Aydın; Gürsel Çolakoğlu

    2003-01-01

    Some visual characteristics of wood such as color, pattern and texture determine the quality of manufactured products. Surface properties of wood material are important both in production and marketing after production. Initial studies related to the roughness of wood surface were begun in early 1950’s. However, no general agreed standardization can not have been developed for wood surfaces. Surface roughness of wood is function of the production process, product type and the natural anatomic...

  11. Validity of total and segmental impedance measurements for prediction of body composition across ethnic population groups

    NARCIS (Netherlands)

    Deurenberg, P.R.M.; Deurenberg-Yap, M.; Schouten, F.J.M.

    2002-01-01

    Methods: Anthropometric parameters were measured in addition to impedance (100 kHz) of the total body, arms and legs. Impedance indexes were calculated as height2/impedance. Arm length (span) and leg length (sitting height), wrist and knee width were measured from which body build indices were

  12. Impedance of electrochemically modified graphite.

    Science.gov (United States)

    Magdić, Katja; Kvastek, Krešimir; Horvat-Radošević, Višnja

    2014-01-01

    Electrochemical impedance spectroscopy, EIS, has been applied for characterization of electrochemically modified graphite electrodes in the sulphuric acid solution. Graphite modifications were performed by potential cyclization between potentials of graphite oxide formation/reduction, different number of cycles, and prolonged reduction steps after cyclization. Impedance spectra measured at two potential points within double-layer region of graphite have been successfully modeled using the concept of porous electrodes involving two different electrolyte diffusion paths, indicating existence of two classes of pores. The evaluated impedance parameter values show continuous changes with stages of graphite modification, indicating continuous structural changes of pores by number of potential cycles applied. Differences of impedance parameter values at two potential values indicate the potential induced changes of solution properties within the pores of modified graphite.

  13. A New Method Based on TOPSIS and Response Surface Method for MCDM Problems with Interval Numbers

    Directory of Open Access Journals (Sweden)

    Peng Wang

    2015-01-01

    Full Text Available As the preference of design maker (DM is always ambiguous, we have to face many multiple criteria decision-making (MCDM problems with interval numbers in our daily life. Though there have been some methods applied to solve this sort of problem, it is always complex to comprehend and sometimes difficult to implement. The calculation processes are always ineffective when a new alternative is added or removed. In view of the weakness like this, this paper presents a new method based on TOPSIS and response surface method (RSM for MCDM problems with interval numbers, RSM-TOPSIS-IN for short. The key point of this approach is the application of deviation degree matrix, which ensures that the DM can get a simple response surface (RS model to rank the alternatives. In order to demonstrate the feasibility and effectiveness of the proposed method, three illustrative MCMD problems with interval numbers are analysed, including (a selection of investment program, (b selection of a right partner, and (c assessment of road transport technologies. The contrast of ranking results shows that the RSM-TOPSIS-IN method is in good agreement with those derived by earlier researchers, indicating it is suitable to solve MCDM problems with interval numbers.

  14. A facile method for simulating randomly rough membrane surface associated with interface behaviors

    Science.gov (United States)

    Qu, Xiaolu; Cai, Xiang; Zhang, Meijia; Lin, Hongjun; Leihong, Zhao; Liao, Bao-Qiang

    2018-01-01

    Modeling rough surfaces has emerged as a distinct discipline of considerable research interest in interface behaviors including membrane fouling. In this paper, a facile method was proposed to simulate rough membrane surface morphology. Natural membrane surface was found to be randomly rough, and its height distribution obeys Gaussian distribution. A new method which combines spectrum method, Gaussian distribution and Fourier transform technique was deduced. Simulation of the rough membrane surface showed high similarity in terms of statistical roughness and height distribution between the simulated surface and the real membrane surface, indicating feasibility of the new method. It was found that, correlation length (l) and the number of superposed ridges (N) are key parameters affecting the simulated membrane surface morphology. This new method has evident advantages over conventional modeling methods The proposed method for randomly rough membrane surface modeling could be potentially used to quantify the interfacial interactions between two rough surfaces, giving implications for membrane fouling mitigation.

  15. Neck electrical impedance for measurement of swallowing; Enge katsudo no keisoku no tame no keibu denki impedance

    Energy Technology Data Exchange (ETDEWEB)

    Yamamoto, Y. [Okayama University, Okayama (Japan)] Nakamura, T. [Okayama University, Okayama (Japan). School of Health Science; Utsunomiya, K.; Akashi, K. [Kawasaki Medical School, Kawasaki (Japan)] Jikuya, K. [Kawasaki College of Allied Health Professions, Kawasaki (Japan)

    1998-03-01

    Recently videofluorography has been used for evaluation of swallowing function in rehabilitation field. But it is not easy to evaluate swallowing disorder simply. And it has problems or exposure for daily use. We have proposed a measurement method of swallowing using bioelectrical impedance method (Impedance Pharyngography, IPG) which has advantages of easy handle and non-invasive measurement. Appropriate electrode positions have been determined. The waveform of IPG can be obtained with some extent reproducibility. The change of neck electrical impedance in pharyngeal phase is mainly caused by the changes of equivalent cross sectional area of near epiglottis. The possibilities of applications for clinical diagnosis have been shown. 7 refs., 10 figs.

  16. Small Signal Loudspeaker Impedance Emulator

    DEFF Research Database (Denmark)

    Iversen, Niels Elkjær; Knott, Arnold

    2014-01-01

    Specifying the performance of audio amplifiers is typically done by playing sine waves into a pure ohmic load. However real loudspeaker impedances are not purely ohmic but characterized by the mechanical resonance between the mass of the diaphragm and the compliance of its suspension which vary f...... to emulate the loudspeaker impedance with an electric circuit and that its resonance frequency can be changed by tuning two resistors....

  17. Beam-beam and impedance

    CERN Document Server

    White, S.

    2014-07-17

    As two counter-rotating beams interact they can give rise to coherent dipole modes. Under the influence of impedance these coherent beam-beam modes can couple to higher order head-tail modes and lead to strong instabilities. A fully self-consistent approach including beam-beam and impedance was used to characterize this new coupled mode instability and study possible cures such as a transverse damper and high chromaticity.

  18. Applications of Nonlinear Electrochemical Impedance Spectroscopy (NLEIS)

    KAUST Repository

    Adler, S. B.

    2013-08-31

    This paper reviews the use of nonlinear electrochemical impedance spectroscopy (NLEIS) in the analysis of SOFC electrode reactions. By combining EIS and NLEIS, as well as other independent information about an electrode material, it becomes possible to establish quantitative links between electrochemical kinetics and materials properties, even when systems are unstable with time. After a brief review of the method, this paper summarizes recent results analyzing the effects of Sr segregation in thin-film LSC electrodes. © The Electrochemical Society.

  19. Techniques for beam impedance measurements above cutoff

    International Nuclear Information System (INIS)

    Lambertson, G.R.; Jacob, A.F.; Rimmer, R.A.; Voelker, F.

    1990-08-01

    Methods for measuring beam impedance above cutoff have been very limited. For design work on the ALS we have developed two techniques that yield data in the frequency domain with high sensitivity. The first is an extension of the wire method; the second utilizes traveling TM waves to simulate the beam's fields at the wall, and thus avoids the mechanical difficulties of mounting the wire. It is also more sensitive than the other method but the interpretation is complicated by the presence of higher order modes. With either method we were able to detect resonant peaks smaller than 1 Ohm at 10 GHz

  20. Nanoscale array structures suitable for surface enhanced raman scattering and methods related thereto

    Science.gov (United States)

    Bond, Tiziana C.; Miles, Robin; Davidson, James C.; Liu, Gang Logan

    2014-07-22

    Methods for fabricating nanoscale array structures suitable for surface enhanced Raman scattering, structures thus obtained, and methods to characterize the nanoscale array structures suitable for surface enhanced Raman scattering. Nanoscale array structures may comprise nanotrees, nanorecesses and tapered nanopillars.

  1. A nanoporous thin-film miniature interdigitated capacitive impedance sensor for measuring humidity

    Directory of Open Access Journals (Sweden)

    T. Islam

    2014-07-01

    Full Text Available This paper presents a development of a low-cost miniature humidity sensor with an interdigitated aluminium electrode connected in parallel on quartz substrate. Interdigitated capacitive device has been fabricated using the photolithography method. The aluminium electrode was covered with sensitive film of a nanoporous thin film of γ-Al2O3 made from novel sol–gel technique. Nanostructured thin film offers very high surface to volume ratio with distribution of micro pores for moisture detection. Pore morphologies of the film have been studied by field emission electron microscope and X-ray diffraction methods. Impedance measurement of the miniature capacitive humidity sensor toward relative humidity was investigated at room temperature by Agilent 4294A impedance analyzer (Agilent, Santa Clara, CA, USA. The device exhibits short response and recovery times and good repeatability.

  2. Variation in Deep Brain Stimulation Electrode Impedance over Years Following Electrode Implantation

    Science.gov (United States)

    Satzer, David; Lanctin, David; Eberly, Lynn E.; Abosch, Aviva

    2014-01-01

    Background Deep brain stimulation (DBS) electrode impedance is a major determinant of current delivery to target tissues, but long-term variation in impedance has received little attention. Objectives To assess the relationship between electrode impedance and time in a large DBS patient population and characterize the relationship between contact activity and impedance. Methods We collected retrospective impedance and programming data from 128 electrodes in 84 patients with Parkinson's disease, essential tremor, or dystonia. Effects of time, contact activity, stimulation voltage, and other parameters on impedance were assessed. We also examined impedance changes following contact activation and deactivation. Results Impedance decreased by 73 Ω/year (P Impedance was on average 163 Ω lower in active contacts (P impedance, respectively. Higher stimulation voltages were associated with lower impedance values (P impedance. Conclusions Impedance decreases gradually in a stimulation-dependent manner. These trends have implications for long-term programming, the development of a closed-loop DBS device, and current understanding of the electrode-tissue interface. PMID:24503709

  3. Characterization of Porous WO3 Electrochromic Device by Electrochemical Impedance Spectroscopy

    Directory of Open Access Journals (Sweden)

    Chien Chon Chen

    2013-01-01

    Full Text Available This paper concerns the microstructure of the anodic tungsten oxide (WO3 and its use in an electrochromic (EC glass device. When voltages between 100 V and 160 V were applied to tungsten film for 1 h under 0.4 wt. % NaF electrolyte, porous WO3 film was formed. The film, which had a large surface area, was used as electrochromic film for EC glass. The average transmittance in a visible region of the spectrum for a 144 cm2 EC device was above 75% in the bleached state and below 40% in the colored state, respectively. Repeatability using of the colored/bleached cycles was tested good by a cyclic voltammograms method. The internal impedance values under colored and bleached states were detected and simulated using an electrical impedance spectra (EIS technique. The EC glass impedance characteristics were simulated using resistors, capacitors, and Warburg impedance. The ITO/WO3, WO3/electrolyte, electrolyte/NiO, and NiO/ITO interfaces can be simulated using a resistance capacitance (RC parallel circuits, and bulk materials such as the indium tin oxide (ITO and conducting wire can be simulated by using a series of resisters.

  4. A Wide-Band Electromagnetic Impedance Profiling System forNon-Invasive Subsurface Characterization

    Energy Technology Data Exchange (ETDEWEB)

    Tseng, Hung-Wen; Lee, Ki Ha; Becker, Alex

    2004-12-17

    A non-invasive, wide-band electromagnetic (EM) impedance difference system for shallow subsurface electrical structure characterization in environmental and engineering problems has been developed at the Lawrence Berkeley National Laboratory (LBNL). Electrical parameters of interest are electrical conductivity and dielectric permittivity that are deduced from the impedance difference data. The prototype system includes a magnetic loop transmitter, which operates between 0.1 MHz and 100 MHz, an electrical dipole antenna for observing the electric field, and a loop antenna for measuring the magnetic field.All antennas are mounted on a cart made of non-metallic material for easy movement of the whole array for profiling. Surface EM impedance difference is obtained by taking the difference of the ratios of the electric fields to the magnetic fields at selected frequencies at two different levels. Numerical simulations will be presented to verify this new approach. A set of the impedance difference data acquired at the University of California's Richmond Field Station compares reasonably well with simulation results based on a model obtained with the resistivity method and in situ TDR (time domain reflectometry)measurements.

  5. Quantitative evaluation of impedance perception characteristics of humans in the man-machine interface

    Energy Technology Data Exchange (ETDEWEB)

    Onish, Keiichi [Yamaha Motor Co., Shizuoka (Japan); Kim, Young Woo [Daegu Techno Park R and D Center, Seoul (Korea, Republic of); Obinata, Goro [Nagoya University, Nagoya (Japan); Hase, Kazunori [Tokyo Metropolitan University, Tokyo (Japan)

    2013-05-15

    We investigated impedance perception characteristics of humans in the man-machine interface. Sensibility or operational feel about physical properties of machine dynamics is obtained through perception process. We evaluated the impedance perception characteristics of humans who are operating a mechanical system, based on extended Scheffe's subjective evaluation method in full consideration of the influence of impedance level, impedance difference, experiment order, individual difference and so on. Constant method based quantitative evaluation was adopted to investigate the influence of motion frequency and change of the impedance on human impedance perception characteristics. Experimental results indicate that humans perceive impedance of mechanical systems based on comparison process of the dynamical characteristics of the systems. The proposed method can be applied to quantify the design requirement of man-machine interface. The effectiveness of the proposed method is verified through experimental results.

  6. Quantitative evaluation of impedance perception characteristics of humans in the man-machine interface

    International Nuclear Information System (INIS)

    Onish, Keiichi; Kim, Young Woo; Obinata, Goro; Hase, Kazunori

    2013-01-01

    We investigated impedance perception characteristics of humans in the man-machine interface. Sensibility or operational feel about physical properties of machine dynamics is obtained through perception process. We evaluated the impedance perception characteristics of humans who are operating a mechanical system, based on extended Scheffe's subjective evaluation method in full consideration of the influence of impedance level, impedance difference, experiment order, individual difference and so on. Constant method based quantitative evaluation was adopted to investigate the influence of motion frequency and change of the impedance on human impedance perception characteristics. Experimental results indicate that humans perceive impedance of mechanical systems based on comparison process of the dynamical characteristics of the systems. The proposed method can be applied to quantify the design requirement of man-machine interface. The effectiveness of the proposed method is verified through experimental results.

  7. Propagation-inside-layer-expansion method combined with physical optics for scattering by coated cylinders, a rough layer, and an object below a rough surface.

    Science.gov (United States)

    Bourlier, Christophe; Pinel, Nicolas; Kubické, Gildas

    2013-09-01

    In this article, the fields scattered by coated cylinders, a rough layer, and an object below a rough surface are computed by the efficient propagation-inside-layer-expansion (PILE) method combined with the physical optics (PO) approximation to accelerate the calculation of the local interactions on the non-illuminated scatterer, which is assumed to be perfectly conducting. The PILE method is based on the method of moments, and the impedance matrix of the two scatterers is then inverted by blocks from a Taylor series expansion of the inverse of the Schur complement. Its main interest is that it is rigorous, with a simple formulation and a straightforward physical interpretation. In addition, one of the advantages of PILE is to be able to hybridize methods (rigorous or asymptotic) valid for a single scatterer. Then, in high frequencies, the hybridization with PO allows us to significantly reduce the complexity in comparison to a direct lower-upper inversion of the impedance matrix of the two scatterers without loss in accuracy.

  8. Longitudinal impedance variability in patients with chronically implanted DBS devices.

    Science.gov (United States)

    Cheung, Tyler; Nuño, Miriam; Hoffman, Matilde; Katz, Maya; Kilbane, Camilla; Alterman, Ron; Tagliati, Michele

    2013-09-01

    Deep brain stimulation (DBS) is an effective therapy for advanced movement disorders, but its optimal use is still controversial. One factor that could play a role in the proper delivery of therapeutic stimulation by current DBS devices is the variability of the impedance at the interface between the electrode surface and surrounding tissue. To analyze variability and trends in the impedance of chronically-implanted DBS electrodes in subjects with movement disorders. We reviewed impedance values from medical records of DBS patients at an academic tertiary-care movement disorders center. The standard deviation of data recorded within individual subjects and single contacts were used as measures of longitudinal impedance variability. A generalized linear mixed model (GLMM) determined if a number of effects had significant influences on impedance. We analyzed 2863 impedance measurements from 94 subjects. Median variability, for subjects with follow-up from 6 months to 5 years (n = 77), was 194 Ω for individual subjects and 141 Ω for individual contacts, with a range spanning from 18 to over 600 Ω. The GLMM, incorporating all subjects (n = 94), identified time, electrical activity, implanted target, contact position on the electrode and side of implantation as significant predictors of impedance. Age and disease duration at surgery, gender or ethnicity were not significant predictors. Our analysis suggests that a significant amount of impedance variability can be expected in chronically implanted DBS electrodes and indicates a number of factors with possible predictive value. Further studies are needed to link impedance characteristics to clinical outcomes. Copyright © 2013 Elsevier Inc. All rights reserved.

  9. On the longitudinal coupling impedance of a toroidal beam tube

    International Nuclear Information System (INIS)

    Hahn, H.; Tepikian, S.

    1990-01-01

    In this paper, the longitudinal coupling impedance of a smooth toroidal beam tube is derived. By treating the torus as a slow-wave structure, the well-known method of describing the impedance in terms of cavity resonances can be used. A simple analytical expression for the coupling impedance of a toroidal beam tube with square cross section valid in the low-frequency limit is obtained. The results from the present study are compared with previously published solutions and qualitative differences are pointed out. 16 refs., 3 figs., 1 tab

  10. MEASURED TRANSVERSE COUPLING IMPEDANCE OF RHIC INJECTION AND ABORT KICKERS

    International Nuclear Information System (INIS)

    HAHN, H.; DAVINO, D.

    2001-01-01

    Concerns regarding possible transverse instabilities in RHIC and the SNS pointed to the need for measurements of the transverse coupling impedance of ring components. The impedance of the RHIC injection and abort kicker was measured using the conventional method based on the S 21 forward transmission coefficient. A commercial 450 Ω twin-wire Lecher line were used and the data was interpreted via the log-formula. All measurements, were performed in test stands fully representing operational conditions including pulsed power supplies and connecting cables. The measured values for the transverse coupling impedance in kick direction and perpendicular to it are comparable in magnitude, but differ from Handbook predictions

  11. Radiation induced diffusion as a method to protect surface

    International Nuclear Information System (INIS)

    Baumvol, I.J.R.

    1980-01-01

    Radiation induced diffusion forms a coating adeherent and without interface on the surface of metalic substrates. This coating improves the behaviour of metal to corrosion and abrasion. The effect of radiation induced diffusion of tin and calcium on pure iron surface is described and analyzed in this work. (author) [pt

  12. Impedance of a beam tube with antechamber

    Energy Technology Data Exchange (ETDEWEB)

    Barry, W.; Lambertson, G.R.; Voelker, F.

    1986-08-01

    A beam vacuum chamber was proposed to allow synchrotron light to radiate from a circulating electron beam into an antechamber containing photon targets, pumps, etc. To determine the impedance such a geometry would present to the beam, electromagnetic measurements were carried out on a section of chamber using for low frequencies a current-carrying wire and for up to 16 GHz, a resonance perturbation method. Because the response of such a chamber would depend on upstream and downstream restrictions of aperture yet to be determined, the resonance studies were analyzed in some generality. The favorable conclusion of these studies is that the antechamber makes practically no contribution to either the longitudinal or the transverse impedances.

  13. Beam measurements of the SPS longitudinal impedance

    CERN Document Server

    Lasheen, A

    2017-01-01

    Longitudinal instabilities are one of the main limitationsin the CERN SPS to reach the beam parameters requiredfor the High Luminosity LHC project. In preparation tothe SPS upgrade, possible remedies are studied by perform-ing macroparticle simulations using the machine impedancemodel obtained from electromagnetic simulations and mea-surements. To benchmark the impedance model, the resultsof simulations are compared with various beam measure-ments. In this study, the reactive part of the impedance wasprobed by measuring the quadrupole frequency shift withintensity, obtained from bunch length oscillations at mis-matched injection into the SPS. This method was appliedover many last years to follow up the evolution of the SPSimpedance, injecting bunches with the same bunch length.A novel approach, giving significantly more information,consists in varying the injected bunch length. The compari-son of these measurements with macroparticle simulationsallowed to test the existing model and identify some missingSPS i...

  14. Quantum dots conjugated zinc oxide nanosheets: Impeder of microbial growth and biofilm

    Energy Technology Data Exchange (ETDEWEB)

    Patil, Rajendra [Department of Biotechnology, Savitribai Phule Pune University, Pune 411007 (India); Gholap, Haribhau, E-mail: haribhau.gholap@fergusson.edu [Department of Physics, Fergusson College, Pune 411004 (India); Warule, Sambhaji [Department of Physics, Nowrosjee Wadia College, Pune 411001 (India); Banpurkar, Arun; Kulkarni, Gauri [Department of Physics, Savitribai Phule Pune University, Pune 411007 (India); Gade, Wasudeo, E-mail: wngade@unipune.ac.in [Department of Biotechnology, Savitribai Phule Pune University, Pune 411007 (India)

    2015-01-30

    Graphical abstract: The visible light upon incident on ZnO/CdTe initiate the phenomenon of photocatalytical impedance of biofilm. - Highlights: • Synthesis of efficient light photocatalyst ZnO/CdTe nanostructures by hydrothermal method. • ZnO/CdTe nanostructures show a good antibacterial activity by action on cell membrane. • ZnO/CdTe nanostructures show a good antibiofilm activity, and also act on the cells inside the biofilm. - Abstract: The grieving problem of the 21st century has been the antimicrobial resistance in pathogenic microorganisms to conventional antibiotics. Therefore, developments of novel antibacterial materials which effectively inhibit or kill such resistant microorganisms have become the need of the hour. In the present study, we communicate the synthesis of quantum dots conjugated zinc oxide nanostructures (ZnO/CdTe) as an impeder of microbial growth and biofilm. The as-synthesized nanostructures were characterized by X-ray diffraction, ultraviolet–visible spectroscopy, photoluminescence spectroscopy, field emission scanning electron microscopy and high resolution transmission electron microscopy. The growth impedance property of ZnO and ZnO/CdTe on Gram positive organism, Bacillus subtilis NCIM 2063 and Gram negative, Escherichia coli NCIM 2931 and biofilm impedance activity in Pseudomonas aeruginosa O1 was found to occur due to photocatalytical action on the cell biofilm surfaces. The impedance in microbial growth and biofilm formation was further supported by ruptured appearances of cells and dettrered biofilm under field emission scanning electron and confocal laser scanning microscope. The ZnO/CdTe nanostructures array synthesized by hydrothermal method has an advantage of low growth temperature, and opportunity to fabricate inexpensive material for nano-biotechnological applications.

  15. Applications of Electrical Impedance Tomography (EIT): A Short Review

    Science.gov (United States)

    Kanti Bera, Tushar

    2018-03-01

    Electrical Impedance Tomography (EIT) is a tomographic imaging method which solves an ill posed inverse problem using the boundary voltage-current data collected from the surface of the object under test. Though the spatial resolution is comparatively low compared to conventional tomographic imaging modalities, due to several advantages EIT has been studied for a number of applications such as medical imaging, material engineering, civil engineering, biotechnology, chemical engineering, MEMS and other fields of engineering and applied sciences. In this paper, the applications of EIT have been reviewed and presented as a short summary. The working principal, instrumentation and advantages are briefly discussed followed by a detail discussion on the applications of EIT technology in different areas of engineering, technology and applied sciences.

  16. Bioelectrical Impedance Assessment of Wound Healing

    Science.gov (United States)

    Lukaski, Henry C; Moore, Micheal

    2012-01-01

    Objective assessment of wound healing is fundamental to evaluate therapeutic and nutritional interventions and to identify complications. Despite availability of many techniques to monitor wounds, there is a need for a safe, practical, accurate, and effective method. A new method is localized bioelectrical impedance analysis (BIA) that noninvasively provides information describing cellular changes that occur during healing and signal complications to wound healing. This article describes the theory and application of localized BIA and provides examples of its use among patients with lower leg wounds. This promising method may afford clinicians a novel technique for routine monitoring of interventions and surveillance of wounds. PMID:22401341

  17. Impedance matched thin metamaterials make metals absorbing.

    Science.gov (United States)

    Mattiucci, N; Bloemer, M J; Aközbek, N; D'Aguanno, G

    2013-11-13

    Metals are generally considered good reflectors over the entire electromagnetic spectrum up to their plasma frequency. Here we demonstrate an approach to tailor their absorbing characteristics based on the effective metamaterial properties of thin, periodic metallo-dielectric multilayers by exploiting a broadband, inherently non-resonant, surface impedance matching mechanism. Based on this mechanism, we design, fabricate and test omnidirectional, thin ( 99%) over a frequency range spanning from the UV to the IR. Our approach opens new venues to design cost effective materials for many applications such as thermo-photovoltaic energy conversion devices, light harvesting for solar cells, flat panel display, infrared detectors, stray light reduction, stealth and others.

  18. Modeling of Impedance of Porous Electrodes

    Science.gov (United States)

    Lasia, Andrzej

    Porous electrodes are very important in practical applications of electrocatalysis, where an increase in the real surface area leads to an increase in catalytic activity. Porous electrodes are used in gas evolution (water electrolysis, hydrogen and oxygen evolution, chlorine evolution), electrocatalytic hydrogenation or oxidation of organic compounds, in batteries, fuel cells, etc. Good knowledge of the porous electrode theory permits for the construction of the electrodes with optimal utilization of the active electrode material. The porous electrode model was first developed by several authors for dc conditions (1-6) and later applied to the impedance studies.

  19. Optimization design of power efficiency of exponential impedance transformer

    International Nuclear Information System (INIS)

    Wang Meng; Zou Wenkang; Chen Lin; Guan Yongchao; Fu Jiabin; Xie Weiping

    2011-01-01

    The paper investigates the optimization design of power efficiency of exponential impedance transformer with analytic method and numerical method. In numerical calculation, a sine wave Jantage with hypothesis of rising edge equivalence is regarded as the forward-going Jantage at input of transformer, and its dominant angular frequency is determined by typical rise-time of actual Jantage waveforms. At the same time, dissipative loss in water dielectric is neglected. The numerical results of three typical modes of impedance transformation, viz. linear mode, saturation mode and steep mode,are compared. Pivotal factors which affect the power efficiency of exponential impedance transformer are discussed, and a certain extent quantitative range of intermediate variables and accordance coefficients are obtained. Finally, the paper discusses some important issues in actual design, such as insulation safety factor in structure design, effects of coupling capacitance on impedance calculation, and dissipative loss in water dielectric. (authors)

  20. A Forward Solution for RF Impedance Tomography in Wood

    Directory of Open Access Journals (Sweden)

    Ian WOODHEAD

    2008-04-01

    Full Text Available Both integral equation and differential equation methods enable modelling current and hence impedance of wood, to provide the forward solution for impedance tomography that in turn provides a measure of its internal moisture distribution. Previously, we have used a series impedance model and successfully demonstrated measurement of internal moisture distribution. Here we describe the adaptation of our integral equation method for this application. This has required an alternative calculation to model the impressed field from the segmented electrodes used in the measurements to date, and we demonstrate distortion of the anomalous field due to the presence of a wood dielectric, and the field magnitude. Further work will be required to translate the resulting field distribution from our model, to complex current and hence impedance readings, to allow completion of tomographic reconstruction using this approach.

  1. An EIS alternative for impedance measurement of a high temperature PEM fuel cell stack based on current pulse injection

    DEFF Research Database (Denmark)

    Jeppesen, Christian; Araya, Samuel Simon; Sahlin, Simon Lennart

    2017-01-01

    In this paper a method for estimating the fuel cell impedance is presented, namely the current pulse injection (CPI) method, which is well suited for online implementation. This method estimates the fuel cell impedance and unlike electrochemical impedance spectroscopy (EIS), it is simple to imple...

  2. Analytical methods for the characterization of surface finishing in bricks

    International Nuclear Information System (INIS)

    Nardini, I.; Zendri, E.; Biscontin, G.; Brunetin, A.

    2006-01-01

    The recent restoration works of Santo Stefano Church Facade (XV century) in Venice have shown traces variously saved of different kind of surface finishes. These finishes were found on the brick's surface both in the masonry and in the decorative elements. Different brick's surface and decorative tile samples were investigated using several techniques: optical microscopy, scanning electron-microscopy, thermal analysis, infrared spectroscopy and reflectance Fourier transform infrared microspectroscopy. The evaluation of the reached results was used to understand the decorative techniques and to recognize the material employed

  3. Carbon nanotube oscillator surface profiling device and method of use

    Science.gov (United States)

    Popescu, Adrian [Tampa, FL; Woods, Lilia M [Tampa, FL; Bondarev, Igor V [Fuquay Varina, NC

    2011-11-15

    The proposed device is based on a carbon nanotube oscillator consisting of a finite length outer stationary nanotube and a finite length inner oscillating nanotube. Its main function is to measure changes in the characteristics of the motion of the carbon nanotube oscillating near a sample surface, and profile the roughness of this surface. The device operates in a non-contact mode, thus it can be virtually non-wear and non-fatigued system. It is an alternative to the existing atomic force microscope (AFM) tips used to scan surfaces to determine their roughness.

  4. Contribution of surface analysis spectroscopic methods to the lubrication field

    International Nuclear Information System (INIS)

    Blanc, C.

    1979-01-01

    The analytical surface technics such as ESCA, AES and SIMS are tested to be applied to a particular lubrication field. One deals with a 100 C 6 steel surface innumered in tricresylphosphate at 110 0 C for 15 days. The nature of the first layers is studied after relevant solvant cleaning. An iron oxide layer is produced on the bearing surface, namely αFe 2 -O 3 . ESCA, AES and SIMS studies show an overlayer of iron phosphate. The exact nature of iron phosphate is not clearly established but the formation of a ferrous phosphate coating can be assumed from ESCA analysis [fr

  5. Acoustic Treatment Design Scaling Methods. Volume 4; Numerical Simulation of the Nonlinear Acoustic Impedance of a Perforated Plate Single-Degree-of-Freedom Resonator Using a Time-Domain Finite Difference Method

    Science.gov (United States)

    Kraft, R. E.

    1999-01-01

    Single-degree-of-freedom resonators consisting of honeycomb cells covered by perforated facesheets are widely used as acoustic noise suppression liners in aircraft engine ducts. The acoustic resistance and mass reactance of such liners are known to vary with the intensity of the sound incident upon the panel. Since the pressure drop across a perforated liner facesheet increases quadratically with the flow velocity through the facesheet, this is known as the nonlinear resistance effect. In the past, two different empirical frequency domain models have been used to predict the Sound Pressure Level effect of the incident wave on the perforated liner impedance, one that uses the incident particle velocity in isolated narrowbands, and one that models the particle velocity as the overall velocity. In the absence of grazing flow, neither frequency domain model is entirely accurate in predicting the nonlinear effect that is measured for typical perforated sheets. The time domain model is developed in an attempt to understand and improve the model for the effect of spectral shape and amplitude of multi-frequency incident sound pressure on the liner impedance. A computer code for the time-domain finite difference model is developed and predictions using the models are compared to current frequency-domain models.

  6. Method and coating composition for protecting and decontaminating surfaces

    Science.gov (United States)

    Overhold, D C; Peterson, M D

    1959-03-10

    A protective coating useful in the decontamination of surfaces exposed to radioactive substances is described. This coating is placed on the surface before use and is soluble in water, allowing its easy removal in the event decontamination becomes necessary. Suitable coating compositions may be prepared by mixing a water soluble carbohydrate such as sucrose or dextrin, together with a hygroscopic agent such as calcium chloride or zinc chloride.

  7. The bioelectrical impedance vector migration in healthy infants

    OpenAIRE

    L'Abee, Carianne; Poorts-Borger, Petra H.; Gorter, Erna H. G. M.; Piccoli, Antonio; Stolk, Ronald P.; Sauer, Pieter J. J.

    2010-01-01

    Background & aims: Detecting young children with high amount of body fat is important to intervene in the development of obesity. The aim of this study is to gain inside in the bioelectrical impedance vector analysis in healthy infants. Methods: Repeated measurements of whole body reactance and resistance were assessed, using a 50 kHz frequency bioelectrical impedance analysis, in 51 boys and 62 girls during infancy. Bivariate vector analysis, which can be used to determine tissue hydration a...

  8. A-Source Impedance Network

    DEFF Research Database (Denmark)

    Siwakoti, Yam Prasad; Blaabjerg, Frede; Galigekere, Veda Prakash

    2016-01-01

    A novel A-source impedance network is proposed in this letter. The A-source impedance network uses an autotransformer for realizing converters for any application that demand a very high dc voltage gain. The network utilizes a minimal turns ratio compared to other Magnetically Coupled Impedance S...... with an example single-switch 400 W dc-dc converter. For the closed-loop control design and stability assessment, a small signal model and its analysis of the proposed network are also presented in brief....... Source (MCIS) networks to attain a high voltage gain. In addition, the proposed converter draws a continuous current from the source, and hence it is suitable for many types of renewable energy sources. The derived network expressions and theoretical analysis are finally validated experimentally...

  9. Influence of various surface-conditioning methods on the bond strength of metal brackets to ceramic surfaces

    NARCIS (Netherlands)

    Schmage, P; Nergiz, [No Value; Herrmann, W; Ozcan, M; Nergiz, Ibrahim; �zcan, Mutlu

    With the increase in adult orthodontic treatment comes the need to find a reliable method for bonding orthodontic brackets onto metal or ceramic crowns and fixed partial dentures. In this study, shear bond strength and surface roughness tests were used to examine the effect of 4 different surface

  10. Feasibility of using a seismic surface wave method to study seasonal and weather effects on shallow surface soils

    Science.gov (United States)

    The objective of this paper is to study the feasibility of using a seismic surface wave method to investigate seasonal and weather effects on shallow surface soils. In the study, temporal variations of subsurface soil properties were measured and monitored by using a combination of a new seismic su...

  11. Group IV nanocrystals with ion-exchangeable surface ligands and methods of making the same

    Energy Technology Data Exchange (ETDEWEB)

    Wheeler, Lance M.; Nichols, Asa W.; Chernomordik, Boris D.; Anderson, Nicholas C.; Beard, Matthew C.; Neale, Nathan R.

    2018-01-09

    Methods are described that include reacting a starting nanocrystal that includes a starting nanocrystal core and a covalently bound surface species to create an ion-exchangeable (IE) nanocrystal that includes a surface charge and a first ion-exchangeable (IE) surface ligand ionically bound to the surface charge, where the starting nanocrystal core includes a group IV element.

  12. A novel surface cleaning method for chemical removal of fouling lead layer from chromium surfaces

    Science.gov (United States)

    Gholivand, Kh.; Khosravi, M.; Hosseini, S. G.; Fathollahi, M.

    2010-10-01

    Most products especially metallic surfaces require cleaning treatment to remove surface contaminations that remain after processing or usage. Lead fouling is a general problem which arises from lead fouling on the chromium surfaces of bores and other interior parts of systems which have interaction with metallic lead in high temperatures and pressures. In this study, a novel chemical solution was introduced as a cleaner reagent for removing metallic lead pollution, as a fouling metal, from chromium surfaces. The cleaner aqueous solution contains hydrogen peroxide (H 2O 2) as oxidizing agent of lead layer on the chromium surface and acetic acid (CH 3COOH) as chelating agent of lead ions. The effect of some experimental parameters such as acetic acid concentration, hydrogen peroxide concentration and temperature of the cleaner solution during the operation on the efficiency of lead cleaning procedure was investigated. The results of scanning electron microscopy (SEM) showed that using this procedure, the lead pollution layer could be completely removed from real chromium surfaces without corrosion of the original surface. Finally, the optimum conditions for the complete and fast removing of lead pollution layer from chromium surfaces were proposed. The experimental results showed that at the optimum condition (acetic acid concentration 28% (V/V), hydrogen peroxide 8% (V/V) and temperature 35 °C), only 15-min time is needed for complete removal of 3 g fouling lead from a chromium surface.

  13. Acoustic impedances of ear canals measured by impedance tube

    DEFF Research Database (Denmark)

    Ciric, Dejan; Hammershøi, Dorte

    2007-01-01

    During hearing sensitivity tests, the sound field is commonly generated by an earphone placed on a subject ear. One of the factors that can affect the sound transmission in the ear is the acoustic impedance of the ear canal. Its importance is related to the contribution of other elements involved...

  14. Microfabricated Thin Film Impedance Sensor & AC Impedance Measurements

    Science.gov (United States)

    Yu, Jinsong; Liu, Chung-Chiun

    2010-01-01

    Thin film microfabrication technique was employed to fabricate a platinum based parallel-electrode structured impedance sensor. Electrochemical impedance spectroscopy (EIS) and equivalent circuit analysis of the small amplitude (±5 mV) AC impedance measurements (frequency range: 1 MHz to 0.1 Hz) at ambient temperature were carried out. Testing media include 0.001 M, 0.01 M, 0.1 M NaCl and KCl solutions, and alumina (∼3 μm) and sand (∼300 μm) particulate layers saturated with NaCl solutions with the thicknesses ranging from 0.6 mm to 8 mm in a testing cell, and the results were used to assess the effect of the thickness of the particulate layer on the conductivity of the testing solution. The calculated resistances were approximately around 20 MΩ, 4 MΩ, and 0.5 MΩ for 0.001 M, 0.01 M, and 0.1 M NaCl solutions, respectively. The presence of the sand particulates increased the impedance dramatically (6 times and 3 times for 0.001 M and 0.1 M NaCl solutions, respectively). A cell constant methodology was also developed to assess the measurement of the bulk conductivity of the electrolyte solution. The cell constant ranged from 1.2 to 0.8 and it decreased with the increase of the solution thickness. PMID:22219690

  15. Y-Source Impedance Network

    DEFF Research Database (Denmark)

    Siwakoti, Yam Prasad; Loh, Poh Chiang; Blaabjerg, Frede

    2014-01-01

    This letter introduces a new versatile Y-shaped impedance network for realizing converters that demand a very high-voltage gain, while using a small duty ratio. To achieve that, the proposed network uses a tightly coupled transformer with three windings, whose obtained gain is presently not matched...... by existing networks operated at the same duty ratio. The proposed impedance network also has more degrees of freedom for varying its gain, and hence, more design freedom for meeting requirements demanded from it. This capability has been demonstrated by mathematical derivation, and proven in experiment...

  16. Hybrid-Source Impedance Networks

    DEFF Research Database (Denmark)

    Li, Ding; Gao, Feng; Loh, Poh Chiang

    2010-01-01

    Hybrid-source impedance networks have attracted attention among researchers because of their flexibility in performing buck-boost energy conversion. To date, three distinct types of impedance networks can be summarized for implementing voltage-type inverters with another three types summarized...... the cascaded networks would have a higher output voltage gain and other unique advantages that currently have not been investigated yet. It is anticipated that these advantages would help the formed inverters find applications in photovoltaic and other renewable systems, where a high voltage gain is usually...

  17. Real-time impedance-based stability assessment of grid converter interactions

    DEFF Research Database (Denmark)

    Messo, Tuomas; Luhtala, Roni; Roinila, Tomi

    2017-01-01

    This paper proposes a method to monitor the impedance-based stability margin of grid-connected converters in real-time. A three-phase converter is configured to inject a broadband perturbation on top of its nominal output current to enable online identification of grid impedance. The ratio...... of converter and grid impedance is computed in real-time by utilizing the measured grid impedance and the analytical impedance model of the inverter. A Nyquist contour is plotted based on the impedance ratio. The contour can be used to assess impedance-based stability margin and to allow, e.g., adaptive tuning......, more efficient post-fault diagnostics or to enable re-selection of control parameters. The method is implemented on a dSPACE real-time control platform and the associated Control Desk software. The paper also discusses potential limitations and suggests future improvements. A short video is available...

  18. IMPEDANCE SPECTROSCOPY OF POLYCRYSTALLINE TIN DIOXIDE FILMS

    Directory of Open Access Journals (Sweden)

    D. V. Adamchuck

    2016-01-01

    Full Text Available The aim of this work is the analysis of the influence of annealing in an inert atmosphere on the electrical properties and structure of non-stoichiometric tin dioxide films by means of impedance spectroscopy method. Non-stoichiometric tin dioxide films were fabricated by two-step oxidation of metallic tin deposited on the polycrystalline Al2O3 substrates by DC magnetron sputtering. In order to modify the structure and stoichiometric composition, the films were subjected to the high temperature annealing in argon atmosphere in temperature range 300–800 °С. AC-conductivity measurements of the films in the frequency range 20 Hz – 2 MHz were carried out. Variation in the frequency dependencies of the real and imaginary parts of the impedance of tin dioxide films was found to occur as a result of high-temperature annealing. Equivalent circuits for describing the properties of films with various structure and stoichiometric composition were proposed. Possibility of conductivity variation of the polycrystalline tin dioxide films as a result of аnnealing in an inert atmosphere was demonstrated by utilizing impedance spectroscopy. Annealing induces the recrystallization of the films, changing in their stoichiometry as well as increase of the sizes of SnO2 crystallites. Variation of electrical conductivity and structure of tin dioxide films as a result of annealing in inert atmosphere was confirmed by X-ray diffraction analysis. Analysis of the impedance diagrams of tin dioxide films was found to be a powerful tool to study their electrical properties. 

  19. Reducing Motional Decoherence in Ion Traps with Surface Science Methods

    Science.gov (United States)

    Haeffner, Hartmut

    2014-03-01

    Many trapped ions experiments ask for low motional heating rates while trapping the ions close to trapping electrodes. However, in practice small ion-electrode distances lead to unexpected high heating rates. While the mechanisms for the heating is still unclear, it is now evident that surface contamination of the metallic electrodes is at least partially responsible for the elevated heating rates. I will discuss heating rate measurements in a microfabricated surface trap complemented with basic surface science studies. We monitor the elemental surface composition of the Cu-Al alloy trap with an Auger spectrometer. After bake-out, we find a strong Carbon and Oxygen contamination and heating rates of 200 quanta/s at 1 MHz trap frequency. After removing most of the Carbon and Oxygen with Ar-Ion sputtering, the heating rates drop to 4 quanta/s. Interestingly, we still measure the decreased heating rate even after the surface oxidized from the background gas throughout a 40-day waiting time in UHV.

  20. Biomimetic superhydrophobic polyolefin surfaces fabricated with a facile scraping, bonding and peeling method

    NARCIS (Netherlands)

    Feng, Huanhuan; Zheng, Tingting; Wang, Huiliang

    2016-01-01

    Inspired by the superhydrophobicity of juicy peach surface, on which microscale hairs are standing vertically to the surface plane, an extremely simple, inexpensive physical method is developed for fabrication of superhydrophobic polyolefin surfaces over large areas. This method includes three

  1. Intramyocardial impedance measurements for diagnosis of acute cardiac allograft rejection.

    Science.gov (United States)

    Pfitzmann, R; Müller, J; Grauhan, O; Hetzer, R

    2000-08-01

    Measurements of intramyocardial impedance at high frequencies can indicate alterations in cell membranes and intracellular spaces during acute cardiac allograft rejection. Fifteen beagle dogs underwent heterotopic heart transplantation and were immunosuppressed with cyclosporine and methyl prednisolone (MP). Impedance was determined twice daily by means of four screw-in electrodes in the right and left ventricle. Transmyocardial biopsies and the intramyocardial electrogram (IMEG) were performed as reference methods. A total of 23 rejection episodes were induced. When acute rejection was recognized histologically and through IMEG readings, the animals were treated with a bolus of 125 mg of methyl prednisolone over 5 consecutive days. Treatment of rejection was controlled by biopsy and IMEG. All hearts showed a uniform decrease in impedance of about 28.3%+/-5.5% immediately after transplantation, which subsequently reached a stable plateau after 7 to 8 days. Impedance values then remained unchanged as long as rejection was absent. Biopsy findings of grades 1A to 1B (ISHLT) were accompanied by a statistically significant increase in impedance of 12.2%+/-2.5%; of grades 2 to 3A of 19.2%+/-3.2% and of grades 3B to 4 of 27.0%+/-2.9%. Sensitivity was 96%, specificity 91%. Successful treatment of rejection led to a decrease of impedance to the initial levels. The amount of increase in impedance of high frequencies is a method to stratify acute cardiac allograft rejection into grades like histologically grading. The effectiveness of rejection treatment can also be monitored through impedance measurement. The method is also applicable for telemetric rejection monitoring by means of an implantable device.

  2. Method of removing hazardous material deposited on concrete surface

    International Nuclear Information System (INIS)

    Komatsu, Fumiaki; Baba, Kyoji.

    1991-01-01

    A salt compound containing a carbonate group such as sodium carbonate or potassium carbonate is dissolved in water and the aqueous solution is sprayed on the surface of concretes, kept for a predetermined period and dried to deposit the carbonate on the surface of the concretes. Then, aqueous solution of an organic acid such as oxalic acid or citric acid is sprayed and reacted with the carbonate to form bubbles of gaseous carbon dioxide. With such procedures, hazardous material containing radioactive materials intruded to the unevenness or fine holes on the surface of the concrete, or heavy metals such as hexavalent chromium or lead are deposited to the bubbles of gaseous carbon dioxide to be raised up therewith. By removing the bubbles, hazardous materials such as radioactive materials or heavy metals intruded to the concretes can be removed without generating powdery dusts, without requiring a large-scaled device and without changing the characteristic of the concretes. (T.M.)

  3. Applications for Electrical Impedance Tomography (EIT) and Electrical Properties of the Human Body.

    Science.gov (United States)

    Lymperopoulos, Georgios; Lymperopoulos, Panagiotis; Alikari, Victoria; Dafogianni, Chrisoula; Zyga, Sofia; Margari, Nikoletta

    2017-01-01

    Electrical Impedance Tomography (EIT) is a promising application that displays changes in conductivity within a body. The basic principle of the method is the repeated measurement of surface voltages of a body, which are a result of rolling injection of known and small-volume sinusoidal AC current to the body through the electrodes attached to its surface. This method finds application in biomedicine, biology and geology. The objective of this paper is to present the applications of Electrical Impedance Tomography, along with the method's capabilities and limitations due to the electrical properties of the human body. For this purpose, investigation of existing literature has been conducted, using electronic databases, PubMed, Google Scholar and IEEE Xplore. In addition, there was a secondary research phase, using paper citations found during the first research phase. It should be noted that Electrical Impedance Tomography finds use in a plethora of medical applications, as the different tissues of the body have different conductivities and dielectric constants. Main applications of EIT include imaging of lung function, diagnosis of pulmonary embolism, detection of tumors in the chest area and diagnosis and distinction of ischemic and hemorrhagic stroke. EIT advantages include portability, low cost and safety, which the method provide, since it is a noninvasive imaging method that does not cause damage to the body. The main disadvantage of the method, which blocks its wider spread, appears in the image composition from the voltage measurements, which are conducted by electrodes placed on the periphery of the body, because the injected currents are affected nonlinearly by the general distribution of the electrical properties of the body. Furthermore, the complex impedance of the skin-electrode interface can be modelled by using a capacitor and two resistor, as a result of skin properties. In conclusion, Electrical Impedance Tomography is a promising method for the

  4. Methods of remote surface chemical analysis for asteroid missions

    International Nuclear Information System (INIS)

    Sagdeev, R.Z.; Managadze, G.G.; Shutyaev, I.Yu.; Timofeev, P.P.; Szegoe, K.

    1984-06-01

    Different remote sensing methods are discussed which can be applied to investigate the chemical composition of minor bodies of the Solar System. The secondary-ion method, remote laser mass-analysis and electron beam induced X-ray emission analysis are treated in detail. Relative advantages of these techniques are analyzed. The physical limitation of the methods: effects of solar magnetic field and solar wind on the secondary-ion and laser methods and the effect of electrostatic potential of the space apparatus on the ion and electron beam methods are described. First laboratory results of remote laser method are given. (D.Gy.)

  5. A surface refractive index scanning system and method

    DEFF Research Database (Denmark)

    2015-01-01

    The invention relates to a surface refractive index scanning system for characterization of a sample. The system comprises a grating device for holding or receiving the sample, the device comprising at least a first grating region having a first grating width along a transverse direction, and a s......The invention relates to a surface refractive index scanning system for characterization of a sample. The system comprises a grating device for holding or receiving the sample, the device comprising at least a first grating region having a first grating width along a transverse direction...

  6. Electrical impedance spectroscopy for measuring the impedance response of carbon-fiber-reinforced polymer composite laminates

    KAUST Repository

    Almuhammadi, Khaled

    2017-02-16

    Techniques that monitor the change in the electrical properties of materials are promising for both non-destructive testing and structural health monitoring of carbon-fiber-reinforced polymers (CFRPs). However, achieving reliable monitoring using these techniques requires an in-depth understanding of the impedance response of these materials when subjected to an alternating electrical excitation, information that is only partially available in the literature. In this work, we investigate the electrical impedance spectroscopy response at various frequencies of laminates chosen to be representative of classical layups employed in composite structures. We clarify the relationship between the frequency of the electrical current, the conductivity of the surface ply and the probing depth for different CFRP configurations for more efficient electrical signal-based inspections. We also investigate the effect of the amplitude of the input signal.

  7. Analytical model of impedance in elliptical beam pipes

    CERN Document Server

    Pesah, Arthur Chalom

    2017-01-01

    Beam instabilities are among the main limitations in building higher intensity accelerators. Having a good impedance model for every accelerators is necessary in order to build components that minimize the probability of instabilities caused by the interaction beam-environment and to understand what piece to change in case of intensity increasing. Most of accelerator components have their impedance simulated with finite elements method (using softwares like CST Studio), but simple components such as circular or flat pipes are modeled analytically, with a decreasing computation time and an increasing precision compared to their simulated model. Elliptical beam pipes, while being a simple component present in some accelerators, still misses a good analytical model working for the hole range of velocities and frequencies. In this report, we present a general framework to study the impedance of elliptical pipes analytically. We developed a model for both longitudinal and transverse impedance, first in the case of...

  8. Response surface method applied to optimization of estradiol ...

    Indian Academy of Sciences (India)

    An optimization process based on response surface methodology was carried out in order to develop a statistical model which describes the relationship between active independent variables and estradiol flux. This model can be used to find out a combination of factor levels during response optimization. Possible options ...

  9. Membrane mimetic surface functionalization of nanoparticles: Methods and applications

    Science.gov (United States)

    Weingart, Jacob; Vabbilisetty, Pratima; Sun, Xue-Long

    2013-01-01

    Nanoparticles (NPs), due to their size-dependent physical and chemical properties, have shown remarkable potential for a wide range of applications over the past decades. Particularly, the biological compatibilities and functions of NPs have been extensively studied for expanding their potential in areas of biomedical application such as bioimaging, biosensing, and drug delivery. In doing so, surface functionalization of NPs by introducing synthetic ligands and/or natural biomolecules has become a critical component in regards to the overall performance of the NP system for its intended use. Among known examples of surface functionalization, the construction of an artificial cell membrane structure, based on phospholipids, has proven effective in enhancing biocompatibility and has become a viable alternative to more traditional modifications, such as direct polymer conjugation. Furthermore, certain bioactive molecules can be immobilized onto the surface of phospholipid platforms to generate displays more reminiscent of cellular surface components. Thus, NPs with membrane-mimetic displays have found use in a range of bioimaging, biosensing, and drug delivery applications. This review herein describes recent advances in the preparations and characterization of integrated functional NPs covered by artificial cell membrane structures and their use in various biomedical applications. PMID:23688632

  10. Ion implantation method for preparing polymers having oxygen erosion resistant surfaces

    Science.gov (United States)

    Lee, Eal H.; Mansur, Louis K.; Heatherly, Jr., Lee

    1995-01-01

    Hard surfaced polymers and the method for making them are generally described. Polymers are subjected to simultaneous multiple ion beam bombardment, that results in a hardening of the surface, improved wear resistance, and improved oxygen erosion resistance.

  11. A surface defects inspection method based on multidirectional gray-level fluctuation

    Directory of Open Access Journals (Sweden)

    Yunpeng Ma

    2017-05-01

    Full Text Available Machine vision inspection technology provides an efficient tool for surface defects inspection. However, because of the multiformity of surface defects, the existing machine vision methods for surface defects inspection are limited by application scenarios. In order to improve the versatility of algorithms, and to process various kinds of images more accurately, we propose a new adaptive method for surface defect detection, named neighborhood gray-level difference method using the multidirectional gray-level fluctuation. This method changes thresholds and step values by extracting gray-level-fluctuating condition of images, and then it uses the neighborhood gray-level difference to segment defects from background. Experimental results demonstrate the effectiveness of the proposed method for inspecting different surface defects. Compared with other methods, the proposed method can be applied to inspect various surface defects, and it can provide more accurate defect segmentation results.

  12. Electrochemical properties and electrochemical impedance ...

    African Journals Online (AJOL)

    Polypyrrole (PPy) films of different thickness were characterized by electrochemical impedance spectroscopy (EIS) measurements in acetonitrile and aqueous solutions, containing 0.1 M NaClO4 or sodium dodecylsulfate as the dopant. The PPy films were electrochemically deposited on Pt, and their electrochemical ...

  13. Small Signal Loudspeaker Impedance Emulator

    DEFF Research Database (Denmark)

    Iversen, Niels Elkjær; Knott, Arnold

    2014-01-01

    Specifying the performance of audio amplifiers is typically done by playing sine waves into a pure ohmic load. However real loudspeaker impedances are not purely ohmic but characterized by the mechanical resonance between the mass of the diaphragm and the compliance of its suspension which vary...

  14. Evaluation of the Influence of Sensor Geometry and Physical Parameters on Impedance-Based Structural Health Monitoring

    Directory of Open Access Journals (Sweden)

    L.V. Palomino

    2012-01-01

    Full Text Available Structural Health Monitoring (SHM is the process of damage identification in mechanical structures that encompasses four main phases: damage detection, damage localization, damage extent evaluation and prognosis of residual life. Among various existing SHM techniques, the one based on electromechanical impedance measurements has been considered as one of the most effective, especially in the identification of incipient damage. This method measures the variation of the electromechanical impedance of the structure as caused by the presence of damage by using piezoelectric transducers bonded on the surface of the structure (or embedded into it. The most commonly used smart material in the context of the present contribution is the lead zirconate titanate (PZT. Through these piezoceramic sensor-actuators, the electromechanical impedance, which is directly related to the mechanical impedance of the structure, is obtained as a frequency domain dynamic response. Based on the variation of the impedance signals, the presence of damage can be detected. A particular damage metric can be used to quantify the damage. For the success of the monitoring procedure, the measurement system should be robust enough with respect to environmental influences from different sources, in such a way that correct and reliable decisions can be made based on the measurements. The environmental influences become more critical under certain circumstances, especially in aerospace applications, in which extreme conditions are frequently encountered. In this paper, the influence of electromagnetic radiation, temperature and pressure variations, and ionic environment have been examined in laboratory. In this context, the major concern is to determine if the impedance responses are affected by these influences. In addition, the sensitivity of the method with respect to the shape of the PZT patches is evaluated. Conclusions are drawn regarding the monitoring efficiency, stability and

  15. First-principles Green's-function method for surface calculations: A pseudopotential localized basis set approach

    Science.gov (United States)

    Smidstrup, Søren; Stradi, Daniele; Wellendorff, Jess; Khomyakov, Petr A.; Vej-Hansen, Ulrik G.; Lee, Maeng-Eun; Ghosh, Tushar; Jónsson, Elvar; Jónsson, Hannes; Stokbro, Kurt

    2017-11-01

    We present an efficient implementation of a surface Green's-function method for atomistic modeling of surfaces within the framework of density functional theory using a pseudopotential localized basis set approach. In this method, the system is described as a truly semi-infinite solid with a surface region coupled to an electron reservoir, thereby overcoming several fundamental drawbacks of the traditional slab approach. The versatility of the method is demonstrated with several applications to surface physics and chemistry problems that are inherently difficult to address properly with the slab method, including metal work function calculations, band alignment in thin-film semiconductor heterostructures, surface states in metals and topological insulators, and surfaces in external electrical fields. Results obtained with the surface Green's-function method are compared to experimental measurements and slab calculations to demonstrate the accuracy of the approach.

  16. Line impedance estimation using model based identification technique

    DEFF Research Database (Denmark)

    Ciobotaru, Mihai; Agelidis, Vassilios; Teodorescu, Remus

    2011-01-01

    The estimation of the line impedance can be used by the control of numerous grid-connected systems, such as active filters, islanding detection techniques, non-linear current controllers, detection of the on/off grid operation mode. Therefore, estimating the line impedance can add extra functions......-passive behaviour of the proposed method comes from the combination of the non intrusive behaviour of the passive methods with a better accuracy of the active methods. The simulation results reveal the good accuracy of the proposed method....

  17. The orthogonal gradients method: A radial basis functions method for solving partial differential equations on arbitrary surfaces

    KAUST Repository

    Piret, Cécile

    2012-05-01

    Much work has been done on reconstructing arbitrary surfaces using the radial basis function (RBF) method, but one can hardly find any work done on the use of RBFs to solve partial differential equations (PDEs) on arbitrary surfaces. In this paper, we investigate methods to solve PDEs on arbitrary stationary surfaces embedded in . R3 using the RBF method. We present three RBF-based methods that easily discretize surface differential operators. We take advantage of the meshfree character of RBFs, which give us a high accuracy and the flexibility to represent the most complex geometries in any dimension. Two out of the three methods, which we call the orthogonal gradients (OGr) methods are the result of our work and are hereby presented for the first time. © 2012 Elsevier Inc.

  18. Ion Beam Methods for the Surface Characterization of Polymers.

    Science.gov (United States)

    1982-02-01

    These surface spectroscopies are useful in many areas of polymer technology including synthesis, extrusion and forming, and long time durability and...Pure and Applied Chemistry Meeting on Polymer Degradation held at Durham University, Durham, England, in July 1981. The author thanks Dr. W. J. Feast...25 7 SIMS Data in Mass Range 160-330 from Teflon Using Charge Neutralization (Ref. 19) 26 8 (a) ISS/SIMS Data for Polypropylene Using 3He+ at 2500 eV

  19. Methods of Attaching or Grafting Carbon Nanotubes to Silicon Surfaces and Composite Structures Derived Therefrom

    Science.gov (United States)

    Tour, James M. (Inventor); Chen, Bo (Inventor); Flatt, Austen K. (Inventor); Stewart, Michael P. (Inventor); Dyke, Christopher A. (Inventor); Maya, Francisco (Inventor)

    2012-01-01

    The present invention is directed toward methods of attaching or grafting carbon nanotubes (CNTs) to silicon surfaces. In some embodiments, such attaching or grafting occurs via functional groups on either or both of the CNTs and silicon surface. In some embodiments, the methods of the present invention include: (1) reacting a silicon surface with a functionalizing agent (such as oligo(phenylene ethynylene)) to form a functionalized silicon surface; (2) dispersing a quantity of CNTs in a solvent to form dispersed CNTs; and (3) reacting the functionalized silicon surface with the dispersed CNTs. The present invention is also directed to the novel compositions produced by such methods.

  20. Review of Electrical and Gravity Methods of Near-Surface ...

    African Journals Online (AJOL)

    The theory and practice of electrical and gravity methods of geophysics for groundwater exploration was reviewed with illustrations and data examples. With the goal of reducing cases of borehole/water-well failure attributed to the lack of the knowledge of the methods of geophysics for groundwater exploration and ...

  1. Review of Electrical and Gravity Methods of Near-Surface ...

    African Journals Online (AJOL)

    USER

    method of groundwater exploration was discussed with field data from Wokbedilo community in Ethopia. ... Electromagnetic and electrical methods have shown superior suitability for groundwater exploration because rock properties that are crucial to hydrogeology ..... Where M and R are the mass and radius of the earth.

  2. Photoswitchable method for the ordered attachment of proteins to surfaces

    Science.gov (United States)

    Camarero, Julio A.; De Yoreo, James J.; Kwon, Youngeun

    2010-04-20

    Described herein is a method for the attachment of proteins to any solid support with control over the orientation of the attachment. The method is extremely efficient, not requiring the previous purification of the protein to be attached, and can be activated by UV-light. Spatially addressable arrays of multiple protein components can be generated by using standard photolithographic techniques.

  3. Identification of Critical Transmission Limits in Injection Impedance Plane

    DEFF Research Database (Denmark)

    Jóhannsson, Hjörtur; Østergaard, Jacob; Nielsen, Arne Hejde

    2012-01-01

    the partial derivatives of the variables P,Q and V in respect to each other become zero. In addition to the mappingof the critical lines, some characteristic lines are mapped as well. These include the mapping of the lines of constant P,Q,Vand d from the PQV-surface into the impedance plane. All of the mapped...

  4. Impedance Measurements on the LHC Dump Kicker Prototype

    CERN Document Server

    González, C; Dyachkov, M

    1998-01-01

    In this paper we demonstrate that a thin layer of metallization on the inner surface of the ceramic pipe in an abort kicker will provide an effective way to screen the kicker's magnets from the electr omagnetic fields generated by the LHC bunches. The other objective of this paper was to measure the kicker impedance in a wide frequency range (up to 1 GHz).

  5. Ernst Equation and Riemann Surfaces: Analytical and Numerical Methods

    Energy Technology Data Exchange (ETDEWEB)

    Ernst, Frederick J [FJE Enterprises, 511 County Route 59, Potsdam, NY 13676 (United States)

    2007-06-18

    source can be represented by discontinuities in the metric tensor components. The first two chapters of this book are devoted to some basic ideas: in the introductory chapter 1 the authors discuss the concept of integrability, comparing the integrability of the vacuum Ernst equation with the integrability of nonlinear equations of Korteweg-de Vries (KdV) type, while in chapter 2 they describe various circumstances in which the vacuum Ernst equation has been determined to be relevant, not only in connection with gravitation but also, for example, in the construction of solutions of the self-dual Yang-Mills equations. It is also in this chapter that one of several equivalent linear systems for the Ernst equation is described. The next two chapters are devoted to Dmitry Korotkin's concept of algebro-geometric solutions of a linear system: in chapter 3 the structure of such solutions of the vacuum Ernst equation, which involve Riemann theta functions of hyperelliptic algebraic curves of any genus, is contrasted with the periodic structure of such solutions of the KdV equation. How such solutions can be obtained, for example, by solving a matrix Riemann-Hilbert problem and how the metric tensor of the associated spacetime can be evaluated is described in detail. In chapter 4 the asymptotic behaviour and the similarity structure of the general algebro-geometric solutions of the Ernst equation are described, and the relationship of such solutions to the perhaps more familiar multi-soliton solutions is discussed. The next three chapters are based upon the authors' own published research: in chapter 5 it is shown that a problem involving counter-rotating infinitely thin disks of matter can be solved in terms of genus two Riemann theta functions, while in chapter 6 the authors describe numerical methods that facilitate the construction of such solutions, and in chapter 7 three-dimensional graphs are displayed that depict all metrical fields of the associated spacetime

  6. Integral methods for shallow free-surface flows with separation

    DEFF Research Database (Denmark)

    Watanabe, S.; Putkaradze, V.; Bohr, Tomas

    2003-01-01

    an inclined plane we take a similar approach and derive a simple model in which the velocity profile is not restricted to a parabolic or self-similar form. Two types of solutions with large surface distortions are found: solitary, kink-like propagating fronts, obtained when the flow rate is suddenly changed......, and stationary jumps, obtained, for instance, behind a sluice gate. We then include time dependence in the model to study the stability of these waves. This allows us to distinguish between sub- and supercritical flows by calculating dispersion relations for wavelengths of the order of the width of the layer....

  7. A new method for background rejection with surface sensitive bolometers

    International Nuclear Information System (INIS)

    Nones, C.; Foggetta, L.; Giuliani, A.; Pedretti, M.; Salvioni, C.; Sangiorgio, S.

    2006-01-01

    We report the performance of three prototype TeO 2 macrobolometers, able to identify events due to energy deposited at the detector surface. This capability is obtained by thermally coupling thin active layers to the main absorber of the bolometer, and is proved by irradiating the detectors with alpha particles. This technique can be very useful in view of background study and reduction for the CUORE experiment, a next generation Double Beta Decay search based on TeO 2 macrobolometers and to be installed in the Laboratori Nazionali del Gran Sasso

  8. Transferring human impedance regulation skills to robots

    CERN Document Server

    Ajoudani, Arash

    2016-01-01

    This book introduces novel thinking and techniques to the control of robotic manipulation. In particular, the concept of teleimpedance control as an alternative method to bilateral force-reflecting teleoperation control for robotic manipulation is introduced. In teleimpedance control, a compound reference command is sent to the slave robot including both the desired motion trajectory and impedance profile, which are then realized by the remote controller. This concept forms a basis for the development of the controllers for a robotic arm, a dual-arm setup, a synergy-driven robotic hand, and a compliant exoskeleton for improved interaction performance.

  9. Development of the impedance void meter

    International Nuclear Information System (INIS)

    Chung, Moon Ki; Song, Chul Hwa; Won, Soon Yeon; Kim, Bok Deuk

    1994-06-01

    An impedance void meter is developed to measure the area-averaged void fraction. Its basic principle is based on the difference in the electrical conductivity between phases. Several methods of measuring void fraction are briefly reviewed and the reason why this type of void meter is chosen to develop is discussed. Basic principle of the measurement is thoroughly described and several design parameters to affect the overall function are discussed in detail. As example of applications is given for vertical air-water flow. It is shown that the current design has good dynamic response as well as very fine spatial resolution. (Author) 47 refs., 37 figs

  10. Bioelectrical impedance analysis--part I

    DEFF Research Database (Denmark)

    Kyle, Ursula G; Bosaeus, Ingvar; De Lorenzo, Antonio D

    2004-01-01

    The use of bioelectrical impedance analysis (BIA) is widespread both in healthy subjects and patients, but suffers from a lack of standardized method and quality control procedures. BIA allows the determination of the fat-free mass (FFM) and total body water (TBW) in subjects without significant...... of the estimate. The determination of changes in body cell mass (BCM), extra cellular (ECW) and intra cellular water (ICW) requires further research using a valid model that guarantees that ECW changes do not corrupt the ICW. The use of segmental-BIA, multifrequency BIA, or bioelectrical spectroscopy in altered...

  11. Using of the surface activation method for enhancement of machine realibility

    International Nuclear Information System (INIS)

    Postnikov, V.I.; Garbar, I.N.

    1979-01-01

    A surface activation method is described for controlling the wear of units and details, allowing one to measure the wear at continuous operation of the mechanism by any program. The main advantages of the surface activation method for the wear tests are shown. By means of that method it was possible to develop a simultaneous controlling conjugate detail wear, and a method of different-activity brands, as well as the method for repeated activation of details. Development of theory for the engineering and technology of engine wear control by the surface activation method allowed one to improve the efficiency and reduce the time of research in the field of friction and wear

  12. Advanced Bayesian Methods for Lunar Surface Navigation, Phase II

    Data.gov (United States)

    National Aeronautics and Space Administration — The key innovation of this project is the application of advanced Bayesian methods to integrate real-time dense stereo vision and high-speed optical flow with an...

  13. Advanced Bayesian Methods for Lunar Surface Navigation, Phase I

    Data.gov (United States)

    National Aeronautics and Space Administration — The key innovation of this project will be the application of advanced Bayesian methods to integrate real-time dense stereo vision and high-speed optical flow with...

  14. Validation of an Acoustic Impedance Prediction Model for Skewed Resonators

    Science.gov (United States)

    Howerton, Brian M.; Parrott, Tony L.

    2009-01-01

    An impedance prediction model was validated experimentally to determine the composite impedance of a series of high-aspect ratio slot resonators incorporating channel skew and sharp bends. Such structures are useful for packaging acoustic liners into constrained spaces for turbofan noise control applications. A formulation of the Zwikker-Kosten Transmission Line (ZKTL) model, incorporating the Richards correction for rectangular channels, is used to calculate the composite normalized impedance of a series of six multi-slot resonator arrays with constant channel length. Experimentally, acoustic data was acquired in the NASA Langley Normal Incidence Tube over the frequency range of 500 to 3500 Hz at 120 and 140 dB OASPL. Normalized impedance was reduced using the Two-Microphone Method for the various combinations of channel skew and sharp 90o and 180o bends. Results show that the presence of skew and/or sharp bends does not significantly alter the impedance of a slot resonator as compared to a straight resonator of the same total channel length. ZKTL predicts the impedance of such resonators very well over the frequency range of interest. The model can be used to design arrays of slot resonators that can be packaged into complex geometries heretofore unsuitable for effective acoustic treatment.

  15. Management of Elevated Therapeutic Impedances on Deep Brain Stimulation Leads

    Directory of Open Access Journals (Sweden)

    Wissam Deeb

    2017-09-01

    Full Text Available Clinical Vignette: A 64-year-old male with a history of essential tremor with bilateral thalamic ventralis intermedius deep brain stimulation implants had elevated therapeutic impedance values despite normal lead integrity impedances and good response to stimulation.Clinical Dilemma: Do elevated therapeutic impedance values indicate a sign of hardware malfunction? What are the guidelines to approach deep brain stimulation hardware malfunction?Clinical Solution: Lead integrity impedance values are a better evaluation of hardware integrity. The discrepancy between therapeutic and lead-integrity impedance values can arise when using low voltage settings.Gaps in Knowledge: There are no established guidelines for the management of possible hardware malfunction in deep brain stimulation. The recommended approach is to distinguish between open and short circuit problems followed by an “inching” evaluation, assessing the structures from the implantable and programmable generator to the intracranial leads. Constant-current devices will deliver a more stable stimulation but the effect of their adoption is still not clear.Expert Commentary: This case emphasizes the need for clinicians to understand fundamental differences in lead integrity and therapeutic impedance while utilizing a methodical approach in treating hardware malfunction. It highlights future avenues of investigation regarding the utility of constant current DBS technology.

  16. Management of Elevated Therapeutic Impedances on Deep Brain Stimulation Leads.

    Science.gov (United States)

    Deeb, Wissam; Patel, Amar; Okun, Michael S; Gunduz, Aysegul

    2017-01-01

    A 64-year-old male with a history of essential tremor with bilateral thalamic ventralis intermedius deep brain stimulation implants had elevated therapeutic impedance values despite normal lead integrity impedances and good response to stimulation. Do elevated therapeutic impedance values indicate a sign of hardware malfunction? What are the guidelines to approach deep brain stimulation hardware malfunction? Lead integrity impedance values are a better evaluation of hardware integrity. The discrepancy between therapeutic and lead-integrity impedance values can arise when using low voltage settings. There are no established guidelines for the management of possible hardware malfunction in deep brain stimulation. The recommended approach is to distinguish between open and short circuit problems followed by an "inching" evaluation, assessing the structures from the implantable and programmable generator to the intracranial leads. Constant-current devices will deliver a more stable stimulation but the effect of their adoption is still not clear. This case emphasizes the need for clinicians to understand fundamental differences in lead integrity and therapeutic impedance while utilizing a methodical approach in treating hardware malfunction. It highlights future avenues of investigation regarding the utility of constant current DBS technology.

  17. Impedance technique for measuring dielectrophoretic collection of microbiological particles

    CERN Document Server

    Allsopp, D W E; Brown, A P; Betts, W B

    1999-01-01

    Measurement of the impedance change resulting from the collection of microbiological particles at coplanar electrodes is shown to be an effective and potentially quantitative method of detecting dielectrophoresis. Strong correlations between the frequency-dependent dielectrophoretic collection characteristics measured by impedance change and those observed using an established counting method based on image analysis have been obtained for Escherichia coli. In addition it is shown that the new electrical method can be used to sense dielectrophoretic collection of 19 nm diameter latex beads, particles too small to be resolved by conventional optical detection systems. (author)

  18. Utilization of bone impedance for age estimation in postmortem cases.

    Science.gov (United States)

    Ishikawa, Noboru; Suganami, Hideki; Nishida, Atsushi; Miyamori, Daisuke; Kakiuchi, Yasuhiro; Yamada, Naotake; Wook-Cheol, Kim; Kubo, Toshikazu; Ikegaya, Hiroshi

    2015-11-01

    In the field of Forensic Medicine the number of unidentified cadavers has increased due to natural disasters and international terrorism. The age estimation is very important for identification of the victims. The degree of sagittal closure is one of such age estimation methods. However it is not widely accepted as a reliable method for age estimation. In this study, we have examined whether measuring impedance value (z-values) of the sagittal suture of the skull is related to the age in men and women and discussed the possibility to use bone impedance for age estimation. Bone impedance values increased with aging and decreased after the age of 64.5. Then we compared age estimation through the conventional visual method and the proposed bone impedance measurement technique. It is suggested that the bone impedance measuring technique may be of value to forensic science as a method of age estimation. Copyright © 2015 Elsevier Ltd and Faculty of Forensic and Legal Medicine. All rights reserved.

  19. Evaluation of chemical surface treatment methods for mitigation of PWSCC

    International Nuclear Information System (INIS)

    Dame, C.; Marks, C.; Olender, A.; Farias, J.

    2015-01-01

    As part of its mission to propose innovative and safe technologies to mitigate Primary Water Stress Corrosion Cracking (PWSCC) in Pressurized Water Reactors (PWR), EPRI recently initiated a program to evaluate potential new chemical surface treatments that might delay the occurrence of PWSCC such that no failure of components would be observed during their lifetime. Among the initial screening of more than thirty technologies, seven were selected for a more detailed review. The selected technologies were: nickel and nickel alloy plating, organic inhibitors, chromium-based inhibitors, silicon carbide, titanium-based inhibitors, rare earth metal (REM)-based inhibitors and encapsulation. The conclusions of the review of these technologies were that two of them were worth pursuing, titanium-based and REM-based inhibitors, and that evaluating the radiological consequences of injecting these products in the primary system, as well as assessing their efficacy to mitigate PWSCC, should be prioritized as the next required steps in qualification for implementation. (authors)

  20. Application of response surface methodology method in designing corrosion inhibitor

    Science.gov (United States)

    Asmara, Y. P.; Athirah; Siregar, J. P.; Kurniawan, T.; Bachtiar, D.

    2017-10-01

    In oil and gas pipelines and offshore structure, inhibitors have been considered to be the first choice to reduce corrosion rate. There are many corrosion inhibitor compositions available in the market. To produce the best corrosion inhibitor requires many experimental data which is not efficient. These experiments used response surface methodology (RSM) to select corrosion inhibitor compositions. The experiments investigated effects of corrosion inhibition on corrosion rate of low carbon steel in 3% NaCl solution with different concentrations of selected main inhibitor compositions which are ethyl acetate (EA), ethylene glycol (EG) and sodium benzoate (SB). Corrosion rate were calculated using linear polarization resistance (LPR). All of the experiments were set in natural conditions at pH 7. MINITAB® version 15 was used for data analysis. It is shown that a quadratic model is a representative model can predict best corrosion inhibitor composition comprehensibly.