New equivalent-electrical circuit model and a practical measurement method for human body impedance.
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.
Equivalent circuit parameters of nickel/metal hydride batteries from sparse impedance measurements
Nelatury, Sudarshan Rao; Singh, Pritpal
In a recent communication, a method for extracting the equivalent circuit parameters of a lead acid battery from sparse (only three) impedance spectroscopy observations at three different frequencies was proposed. It was based on an equivalent circuit consisting of a bulk resistance, a reaction resistance and a constant phase element (CPE). Such a circuit is a very appropriate model of a lead-acid cell at high state of charge (SOC). This paper is a sequel to it and presents an application of it in case of nickel/metal hydride (Ni/MH) batteries, which also at high SOC are represented by the same circuit configuration. But when the SOC of a Ni/MH battery under interrogation goes low, The EIS curve has a positive slope at the low frequency end and our technique yields complex values for the otherwise real circuit parameters, suggesting the need for additional elements in the equivalent circuit and a definite relationship between parameter consistency and SOC. To improvise the previous algorithm, in order that it works reasonably well at both high and low SOCs, we propose three more measurements—two at very low frequencies to include the Warburg response and one at a high frequency to model the series inductance, in addition to the three in the mid frequency band—totally six measurements. In most of the today's instrumentation, it is the user who should choose the circuit configuration and the number of frequencies where impedance should be measured and the accompanying software performs data fitting by complex nonlinear least squares. The proposed method has built into it an SOC-based decision-making capability—both to choose the circuit configuration and to estimate the values of the circuit elements.
Eisenberg, R S
1967-07-01
The input impedance of muscle fibers of the crab was determined with microelectrodes over the frequency range 1 cps to 10 kc/sec. Care was taken to analyze, reduce, and correct for capacitive artifact. One dimensional cable theory was used to determine the properties of the equivalent circuit of the membrane admittance, and the errors introduced by the neglect of the three dimensional spread of current are discussed. In seven fibers the equivalent circuit of an element of the membrane admittance must contain a DC path and two capacitances, each in series with a resistance. In two fibers, the element of membrane admittance could be described by one capacitance in parallel with a resistance. In several fibers there was evidence for a third very large capacitance. The values of the elements of the equivalent circuit depend on which of several equivalent circuits is chosen. The circuit (with a minimum number of elements) that was considered most reasonably consistent with the anatomy of the fiber has two branches in parallel: one branch having a resistance R(e) in series with a capacitance C(e); the other branch having a resistance R(b) in series with a parallel combination of a resistance R(m) and a capacitance C(m). The average circuit values (seven fibers) for this model, treating the fiber as a cylinder of sarcolemma without infoldings or tubular invaginations, are R(e) = 21 ohm cm(2); C(e) = 47 microf/cm(2); R(b) = 10.2 ohm cm(2); R(m) = 173 ohm cm(2); C(m) = 9.0 microf/cm(2). The relation of this equivalent circuit and another with a nonminimum number of circuit elements to the fine structure of crab muscle is discussed. In the above equivalent circuit R(m) and C(m) are attributed to the sarcolemma; R(e) and C(e), to the sarcotubular system; and R(b), to the amorphous material found around crab fibers. Estimates of actual surface area of the sarcolemma and sarcotubular system permit the average circuit values to be expressed in terms of unit membrane area. The
International Nuclear Information System (INIS)
Ogurtsov, V I; Mathewson, A; Sheehan, M M
2005-01-01
Simulation of electrochemical impedance spectroscopy (EIS) based on a LabVIEW model of a complex impedance measuring system in the frequency domain has been investigated to specify parameters of Randle's equivalent circuit, which is ordinarily used for electrode sensors. The model was based on a standard system for EIS instrumentation and consisted of a sensor modelled by Randle's equivalent circuit, a source of harmonic frequency sweep voltage applied to the sensor and a transimpedance amplifier, which transformed the sensor current to voltage. It provided impedance spectroscopy data for different levels of noise, modelled by current and voltage equivalent noise sources applied to the amplifier input. The noise influence on Randle's equivalent circuit specification was analysed by considering the behaviour of the approximation error. Different metrics including absolute, relative, semilogarithmic and logarithmic based distance between complex numbers on a complex plane were considered and compared to one another for evaluating this error. It was shown that the relative and logarithmic based metrics provide more reliable results for the determination of circuit parameters
Energy Technology Data Exchange (ETDEWEB)
Ogurtsov, V I; Mathewson, A; Sheehan, M M [Tyndall National Institute, Lee Maltings, Prospect Row, Cork (Ireland)
2005-01-01
Simulation of electrochemical impedance spectroscopy (EIS) based on a LabVIEW model of a complex impedance measuring system in the frequency domain has been investigated to specify parameters of Randle's equivalent circuit, which is ordinarily used for electrode sensors. The model was based on a standard system for EIS instrumentation and consisted of a sensor modelled by Randle's equivalent circuit, a source of harmonic frequency sweep voltage applied to the sensor and a transimpedance amplifier, which transformed the sensor current to voltage. It provided impedance spectroscopy data for different levels of noise, modelled by current and voltage equivalent noise sources applied to the amplifier input. The noise influence on Randle's equivalent circuit specification was analysed by considering the behaviour of the approximation error. Different metrics including absolute, relative, semilogarithmic and logarithmic based distance between complex numbers on a complex plane were considered and compared to one another for evaluating this error. It was shown that the relative and logarithmic based metrics provide more reliable results for the determination of circuit parameters.
Bera, Tushar Kanti
2016-12-05
Under an alternating electrical signal, biological tissues produce a complex electrical bioimpedance that is a function of tissue composition and applied signal frequencies. By studying the bioimpedance spectra of biological tissues over a wide range of frequencies, we can noninvasively probe the physiological properties of these tissues to detect possible pathological conditions. Electrical impedance spectroscopy (EIS) can provide the spectra that are needed to calculate impedance parameters within a wide range of frequencies. Before impedance parameters can be calculated and tissue information extracted, impedance spectra should be processed and analyzed by a dedicated software program. National Instruments (NI) Inc. offers LabVIEW, a fast, portable, robust, user-friendly platform for designing dataanalyzing software. We developed a LabVIEW-based electrical bioimpedance spectroscopic data interpreter (LEBISDI) to analyze the electrical impedance spectra for tissue characterization in medical, biomedical and biological applications. Here, we test, calibrate and evaluate the performance of LEBISDI on the impedance data obtained from simulation studies as well as the practical EIS experimentations conducted on electronic circuit element combinations and the biological tissue samples. We analyze the Nyquist plots obtained from the EIS measurements and compare the equivalent circuit parameters calculated by LEBISDI with the corresponding original circuit parameters to assess the accuracy of the program developed. Calibration studies show that LEBISDI not only interpreted the simulated and circuitelement data accurately, but also successfully interpreted tissues impedance data and estimated the capacitive and resistive components produced by the compositions biological cells. Finally, LEBISDI efficiently calculated and analyzed variation in bioimpedance parameters of different tissue compositions, health and temperatures. LEBISDI can also be used for human tissue
Bera, Tushar Kanti; Jampana, Nagaraju; Lubineau, Gilles
2016-01-01
Under an alternating electrical signal, biological tissues produce a complex electrical bioimpedance that is a function of tissue composition and applied signal frequencies. By studying the bioimpedance spectra of biological tissues over a wide range of frequencies, we can noninvasively probe the physiological properties of these tissues to detect possible pathological conditions. Electrical impedance spectroscopy (EIS) can provide the spectra that are needed to calculate impedance parameters within a wide range of frequencies. Before impedance parameters can be calculated and tissue information extracted, impedance spectra should be processed and analyzed by a dedicated software program. National Instruments (NI) Inc. offers LabVIEW, a fast, portable, robust, user-friendly platform for designing dataanalyzing software. We developed a LabVIEW-based electrical bioimpedance spectroscopic data interpreter (LEBISDI) to analyze the electrical impedance spectra for tissue characterization in medical, biomedical and biological applications. Here, we test, calibrate and evaluate the performance of LEBISDI on the impedance data obtained from simulation studies as well as the practical EIS experimentations conducted on electronic circuit element combinations and the biological tissue samples. We analyze the Nyquist plots obtained from the EIS measurements and compare the equivalent circuit parameters calculated by LEBISDI with the corresponding original circuit parameters to assess the accuracy of the program developed. Calibration studies show that LEBISDI not only interpreted the simulated and circuitelement data accurately, but also successfully interpreted tissues impedance data and estimated the capacitive and resistive components produced by the compositions biological cells. Finally, LEBISDI efficiently calculated and analyzed variation in bioimpedance parameters of different tissue compositions, health and temperatures. LEBISDI can also be used for human tissue
Investigation of Equivalent Circuit for PEMFC Assessment
International Nuclear Information System (INIS)
Myong, Kwang Jae
2011-01-01
Chemical reactions occurring in a PEMFC are dominated by the physical conditions and interface properties, and the reactions are expressed in terms of impedance. The performance of a PEMFC can be simply diagnosed by examining the impedance because impedance characteristics can be expressed by an equivalent electrical circuit. In this study, the characteristics of a PEMFC are assessed using the AC impedance and various equivalent circuits such as a simple equivalent circuit, equivalent circuit with a CPE, equivalent circuit with two RCs, and equivalent circuit with two CPEs. It was found in this study that the characteristics of a PEMFC could be assessed using impedance and an equivalent circuit, and the accuracy was highest for an equivalent circuit with two CPEs
DEFF Research Database (Denmark)
Scipioni, Roberto; Jørgensen, Peter Stanley; Graves, Christopher R.
2017-01-01
In this work an Equivalent Circuit Model (ECM) is developed and used to model impedance spectra measured on a commercial 26650 LiFePO4/Graphite cylindrical cell. The ECM is based on measurements and modeling of impedance spectra recorded separately on cathode (LiFePO4) and anode (Graphite) samples...
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...
Fuel Cell Equivalent Electric Circuit Parameter Mapping
DEFF Research Database (Denmark)
Jeppesen, Christian; Zhou, Fan; Andreasen, Søren Juhl
In this work a simple model for a fuel cell is investigated for diagnostic purpose. The fuel cell is characterized, with respect to the electrical impedance of the fuel cell at non-faulty conditions and under variations in load current. Based on this the equivalent electrical circuit parameters can...
Ecker, Bernhard; Egelhaaf, Hans-Joachim; Steim, Roland; Parisi, Juergen; von Hauff', Elizabeth
2012-01-01
In this study we propose an equivalent circuit model to describe S-shaped current–voltage (I–V) characteristics in inverted solar cells with a TiOx interlayer between the cathode and the poly(3-hexylthiophene):[6,6]-phenyl C61 butyric acid methyl ester active layer. Initially the solar cells
Array of piezoelectric energy harvesting by the equivalent impedance approach
International Nuclear Information System (INIS)
Lien, I C; Shu, Y C
2012-01-01
This article proposes to use the idea of equivalent impedance to investigate the electrical response of an array of piezoelectric oscillators endowed with distinct energy harvesting circuits. Three interface electronics systems are considered including standard AC/DC and parallel/series-SSHI (synchronized switch harvesting on inductor) circuits. Various forms of equivalent load impedance are analytically obtained for different interfaces. The steady-state response of an array system is then shown to be determined by the matrix formulation of generalized Ohm’s law whose impedance matrix is explicitly expressed in terms of the load impedance. A model problem is proposed for evaluating the ability of power harvesting under various conditions. It is shown first that harvested power is increased dramatically for the case of small deviation in the system parameters. On the other hand, if the deviation in mass is relatively large, the result is changed from the power-boosting mode to wideband mode. In particular, the parallel-SSHI array system exhibits much more significant bandwidth improvement than the other two cases. Surprisingly, the series-SSHI array system shows the worst electrical response. Such an observation is opposed to our previous finding that an SSHI technique avails against the standard technique in the case based on a single piezoelectric energy harvester and the explanation is under investigation. (fast track communication)
Estimating the short-circuit impedance
DEFF Research Database (Denmark)
Nielsen, Arne Hejde; Pedersen, Knud Ole Helgesen; Poulsen, Niels Kjølstad
1997-01-01
A method for establishing a complex value of the short-circuit impedance from naturally occurring variations in voltage and current is discussed. It is the symmetrical three phase impedance at the fundamental grid frequency there is looked for. The positive sequence components in voltage...... and current are derived each period, and the short-circuit impedance is estimated from variations in these components created by load changes in the grid. Due to the noisy and dynamic grid with high harmonic distortion it is necessary to threat the calculated values statistical. This is done recursively...... through a RLS-algorithm. The algorithms have been tested and implemented on a PC at a 132 kV substation supplying a rolling mill. Knowing the short-circuit impedance gives the rolling mill an opportunity to adjust the arc furnace operation to keep flicker below a certain level. Therefore, the PC performs...
Equivalent circuit analysis of terahertz metamaterial filters
Zhang, Xueqian
2011-01-01
An equivalent circuit model for the analysis and design of terahertz (THz) metamaterial filters is presented. The proposed model, derived based on LMC equivalent circuits, takes into account the detailed geometrical parameters and the presence of a dielectric substrate with the existing analytic expressions for self-inductance, mutual inductance, and capacitance. The model is in good agreement with the experimental measurements and full-wave simulations. Exploiting the circuit model has made it possible to predict accurately the resonance frequency of the proposed structures and thus, quick and accurate process of designing THz device from artificial metamaterials is offered. ©2011 Chinese Optics Letters.
ASCERTAINMENT OF THE EQUIVALENT CIRCUIT PARAMETERS OF THE ASYNCHRONOUS MACHINE
Directory of Open Access Journals (Sweden)
V. S. Safaryan
2015-01-01
Full Text Available The article considers experimental and analytical determination of the asynchronous machine equivalent-circuit parameters with application of the reference data. Transient processes investigation of the asynchronous machines necessitates the equivalent circuit parameters (resistance impedance, inductances and coefficient of the stator-rotor contours mutual inductance that help form the transitory-process mathematical simulation model. The reference books do not provide those parameters; they instead give the rated ones (active power, voltage, slide, coefficient of performance and capacity coefficient as well as the ratio of starting and nominal currents and torques. The noted studies on the asynchronous machine equivalent-circuits parametrization fail to solve the problems ad finem or solve them with admissions. The paper presents experimental and analytical determinations of the asynchronous machine equivalent-circuit parameters: the experimental one based on the results of two measurements and the analytical one where the problem boils down to solving a system of nonlineal algebraic equations. The authors investigate the equivalent asynchronous machine input-resistance properties and adduce the dependence curvatures of the input-resistances on the slide. They present a symbolic model for analytical parameterization of the asynchronous machine equivalent-circuit that represents a system of nonlineal equations and requires one of the rotor-parameters arbitrary assignment. The article demonstrates that for the asynchronous machine equivalent-circuit experimental parameterization the measures are to be conducted of the stator-circuit voltage, current and active power with two different slides and arbitrary assignment of one of the rotor parameters. The paper substantiates the fact that additional measurement does not discard the rotor-parameter choice arbitrariness. The authors establish that in motoring mode there is a critical slide by which the
On equivalent resistance of electrical circuits
Kagan, Mikhail
2015-01-01
While the standard (introductory physics) way of computing the equivalent resistance of nontrivial electrical circuits is based on Kirchhoff's rules, there is a mathematically and conceptually simpler approach, called the method of nodal potentials, whose basic variables are the values of the electric potential at the circuit's nodes. In this paper, we review the method of nodal potentials and illustrate it using the Wheatstone bridge as an example. We then derive a closed-form expression for the equivalent resistance of a generic circuit, which we apply to a few sample circuits. The result unveils a curious interplay between electrical circuits, matrix algebra, and graph theory and its applications to computer science. The paper is written at a level accessible by undergraduate students who are familiar with matrix arithmetic. Additional proofs and technical details are provided in appendices.
Electrical equivalent circuit of an ion-exchange membrane system
Energy Technology Data Exchange (ETDEWEB)
Nikonenko, Victor V., E-mail: v_nikonenko@mail.r [Membrane Institute, Kuban State University, Krasnodar (Russian Federation); Kozmai, Anton E. [Membrane Institute, Kuban State University, Krasnodar (Russian Federation)
2011-01-01
Usually, the current flowing through an electrochemical cell is divided into the faradaic current going to an electrochemical interface reaction, and the current charging electric double layer (EDL). This division leads to the Randles-Ershler equivalent circuit with an EDL capacitance in one branch, and the faradaic impedance in the other, specific for each particular system. However, the physics of the separation of the impedance into faradaic and capacitive components for different electrochemical systems is not sufficiently clear. The most of derivations resulting in the formal construction of the Randles-Ershler or similar equivalent circuits are based on the a priori separation of the electroneutral and the double-layer regions. In this paper, we derive an equation for the impedance of a three-layer system consisted of an ion-exchange membrane and two adjoining diffusion boundary layers (DBL) starting from the Poisson equation. The system is polarized by a constant electric current over which a small sinusoidal signal is applied. The equation shows that the impedance of the considered system can be formally interpreted via an equivalent circuit with a frequency dependent capacitance in one branch and a finite-length Warburg-type impedance in the other. To take into account this dependence, the impedance of the system may be presented as a series connection of five circuits. Three of them are consisted of a geometric capacitance connected in parallel with an ohmic resistance, respectively, for both diffusion layers and for the membrane bulk; the two others being the double-layer capacitance in parallel with the finite-length Warburg impedance for the left and the right interfaces, respectively. The comparison of the impedance spectra calculated within our analytical approach with those obtained by the full numerical solution of the Nernst-Planck-Poisson (NPP) equations shows a good agreement. Different possible situations, which might arise in real systems
International Nuclear Information System (INIS)
Muta, I.; Magarikaji, N.
1980-01-01
Operational impedances of synchronous machine are very important in the study of dynamic and transient stability. In recent years, it has become possible to analyze the transient behavior of operational impedance by the direct Fourier transformation of frequency response characteristics of operational impedance. It is desired very much to derive the equivalent circuit based on exact operational impedances. In this paper, we calculate the frequency characteristics of operational impedances which are derived in a companion paper. Also, we analyze the effects of various parameters on the equivalent circuit constants. Approximate expressions for sub-subtransient, subtransient and transient reactances are derived from the theoretical expressions for operational impedances. The validity of theoretical calculations is confirmed by comparison with experimental results
Equivalent Circuit Modeling of Hysteresis Motors
Energy Technology Data Exchange (ETDEWEB)
Nitao, J J; Scharlemann, E T; Kirkendall, B A
2009-08-31
We performed a literature review and found that many equivalent circuit models of hysteresis motors in use today are incorrect. The model by Miyairi and Kataoka (1965) is the correct one. We extended the model by transforming it to quadrature coordinates, amenable to circuit or digital simulation. 'Hunting' is an oscillatory phenomenon often observed in hysteresis motors. While several works have attempted to model the phenomenon with some partial success, we present a new complete model that predicts hunting from first principles.
Developing equivalent circuits for radial distribution networks
Energy Technology Data Exchange (ETDEWEB)
Prada, Ricardo; Coelho, Agnelo; Rodrigues, Anselmo [Catholic University of Rio de Janeiro (PUC-Rio), RJ (Brazil). Dept. of Electrical Engineering], Emails: prada@ele.puc-rio.br, agnelo@ele.puc-rio.br, nebulok_99@yahoo.com; Silva, Maria da Guia da [Federal University of Maranhao, Sao Luiz, MA (Brazil). Dept. of Electrical Engineering
2009-07-01
This paper presents a method for evaluating External Equivalent in Electric Distribution Networks (EDN).The proposed method has as its main objectives the reduction of the computational costs in distribution network reconfiguration, investigation of the optimal allocation of banks of capacitors, investigation of the allocation of distributed generation, etc. In these sorts of problems a large number of alternative projects must be assessed in order to identify the optimal solution. The optimal solution comes up with the voltage level in the load points within specified limits. Consequently, the EDN must retain the external network load points but without major increasing in the dimension of the equivalent circuit. The proposed method has been tested and validated in a substation of the Electricity Utility of Maranhao - CEMAR, in Brazil. (author)
Equivalent circuit of a coaxial-line-based nozzleless microwave 915 MHz plasma source
International Nuclear Information System (INIS)
Miotk, R; Jasiński, M; Mizeraczyk, J
2016-01-01
This paper presents a new concept of an equivalent circuit of a microwave plasma source (MPS) used for gas treatment. The novelty of presented investigations is the use of the Weissfloch circuit as equivalent of an area of waveguide discontinuity in the MPS which is a result of entering a coaxial-line structure. Furthermore, in this area the microwave discharge is generated. Verification of the proposed method was carried out. The proposed equivalent circuit enabled calculating the MPS tuning characteristics and comparing them with those measured experimentally. This process allowed us to determine the impedance Z_P ofplasma in the MPS. (paper)
Huang, Yihua; Huang, Wenjin; Wang, Qinglei; Su, Xujian
2013-07-01
The equivalent circuit model of a piezoelectric transformer is useful in designing and optimizing the related driving circuits. Based on previous work, an equivalent circuit model for a circular flexural-vibration-mode piezoelectric transformer with moderate thickness is proposed and validated by finite element analysis. The input impedance, voltage gain, and efficiency of the transformer are determined through computation. The basic behaviors of the transformer are shown by numerical results.
New equivalent lumped electrical circuit for piezoelectric transformers.
Gonnard, Paul; Schmitt, P M; Brissaud, Michel
2006-04-01
A new equivalent circuit is proposed for a contour-vibration-mode piezoelectric transformer (PT). It is shown that the usual lumped equivalent circuit derived from the conventional Mason approach is not accurate. The proposed circuit, built on experimental measurements, makes an explicit difference between the elastic energies stored respectively on the primary and secondary parts. The experimental and theoretical resonance frequencies with the secondary in open or short circuit are in good agreement as well as the output "voltage-current" characteristic and the optimum efficiency working point. This circuit can be extended to various PT configurations and appears to be a useful tool for modeling electronic devices that integrate piezoelectric transformers.
An Equivalent Circuit of Longitudinal Vibration for a Piezoelectric Structure with Losses.
Yuan, Tao; Li, Chaodong; Fan, Pingqing
2018-03-22
Equivalent circuits of piezoelectric structures such as bimorphs and unimorphs conventionally focus on the bending vibration modes. However, the longitudinal vibration modes are rarely considered even though they also play a remarkable role in piezoelectric devices. Losses, especially elastic loss in the metal substrate, are also generally neglected, which leads to discrepancies compared with experiments. In this paper, a novel equivalent circuit with four kinds of losses is proposed for a beamlike piezoelectric structure under the longitudinal vibration mode. This structure consists of a slender beam as the metal substrate, and a piezoelectric patch which covers a partial length of the beam. In this approach, first, complex numbers are used to deal with four kinds of losses-elastic loss in the metal substrate, and piezoelectric, dielectric, and elastic losses in the piezoelectric patch. Next in this approach, based on Mason's model, a new equivalent circuit is developed. Using MATLAB, impedance curves of this structure are simulated by the equivalent circuit method. Experiments are conducted and good agreements are revealed between experiments and equivalent circuit results. It is indicated that the introduction of four losses in an equivalent circuit can increase the result accuracy considerably.
Modeling Stochastic Route Choice Behaviors with Equivalent Impedance
Directory of Open Access Journals (Sweden)
Jun Li
2015-01-01
Full Text Available A Logit-based route choice model is proposed to address the overlapping and scaling problems in the traditional multinomial Logit model. The nonoverlapping links are defined as a subnetwork, and its equivalent impedance is explicitly calculated in order to simply network analyzing. The overlapping links are repeatedly merged into subnetworks with Logit-based equivalent travel costs. The choice set at each intersection comprises only the virtual equivalent route without overlapping. In order to capture heterogeneity in perception errors of different sizes of networks, different scale parameters are assigned to subnetworks and they are linked to the topological relationships to avoid estimation burden. The proposed model provides an alternative method to model the stochastic route choice behaviors without the overlapping and scaling problems, and it still maintains the simple and closed-form expression from the MNL model. A link-based loading algorithm based on Dial’s algorithm is proposed to obviate route enumeration and it is suitable to be applied on large-scale networks. Finally a comparison between the proposed model and other route choice models is given by numerical examples.
Equivalent circuit for the characterization of the resonance mode in piezoelectric systems
Fernández-Afonso, Y.; García-Zaldívar, O.; Calderón-Piñar, F.
2015-12-01
The impedance properties in polarized piezoelectric can be described by electric equivalent circuits. The classic circuit used in the literature to describe real systems is formed by one resistor (R), one inductance (L) and one capacitance C connected in series and one capacity (C0) connected in parallel with the formers. Nevertheless, the equation that describe the resonance and anti-resonance frequencies depends on a complex manner of R, L, C and C0. In this work is proposed a simpler model formed by one inductance (L) and one capacity (C) in series; one capacity (C0) in parallel; one resistor (RP) in parallel and one resistor (RS) in series with other components. Unlike the traditional circuit, the equivalent circuit elements in the proposed model can be simply determined by knowing the experimental values of the resonance frequency fr, anti-resonance frequency fa, impedance module at resonance frequency |Zr|, impedance module at anti-resonance frequency |Za| and low frequency capacitance C0, without fitting the impedance experimental data to the obtained equation.
Equivalent circuit for the characterization of the resonance mode in piezoelectric systems
Directory of Open Access Journals (Sweden)
Y. Fernández-Afonso
2015-12-01
Full Text Available The impedance properties in polarized piezoelectric can be described by electric equivalent circuits. The classic circuit used in the literature to describe real systems is formed by one resistor (R, one inductance (L and one capacitance C connected in series and one capacity (C0 connected in parallel with the formers. Nevertheless, the equation that describe the resonance and anti-resonance frequencies depends on a complex manner of R, L, C and C0. In this work is proposed a simpler model formed by one inductance (L and one capacity (C in series; one capacity (C0 in parallel; one resistor (RP in parallel and one resistor (RS in series with other components. Unlike the traditional circuit, the equivalent circuit elements in the proposed model can be simply determined by knowing the experimental values of the resonance frequency fr, anti-resonance frequency fa, impedance module at resonance frequency |Zr|, impedance module at anti-resonance frequency |Za| and low frequency capacitance C0, without fitting the impedance experimental data to the obtained equation.
Directory of Open Access Journals (Sweden)
José Francisco Gómez Aguilar
2012-07-01
Full Text Available Using the fractional calculus approach, we present the Laplace analysis of an equivalent electrical circuit for a multilayered system, which includes distributed elements of the Cole model type. The Bode graphs are obtained from the numerical simulation of the corresponding transfer functions using arbitrary electrical parameters in order to illustrate the methodology. A numerical Laplace transform is used with respect to the simulation of the fractional differential equations. From the results shown in the analysis, we obtain the formula for the equivalent electrical circuit of a simple spectrum, such as that generated by a real sample of blood tissue, and the corresponding Nyquist diagrams. In addition to maintaining consistency in adjusted electrical parameters, the advantage of using fractional differential equations in the study of the impedance spectra is made clear in the analysis used to determine a compact formula for the equivalent electrical circuit, which includes the Cole model and a simple RC model as special cases.
ELECTRICAL EQUIVALENT CIRCUIT OF BIOLOGICAL OBJECTS OF VEGETABLE
Directory of Open Access Journals (Sweden)
I. M. Golev
2014-01-01
Full Text Available Summary.The results of measurements of complex biological tissues electrical resistance of vegetable origin are presented. The measurements were performed at T=296 K in the frequency range from 5 to 500 kHz. As the electrodes were covered with tin (purity of 99.9% copper plates.. Experimentally investigated the following objects: samples parenchymal tissue of Apple in the form of cylinders with a diameter of 20 mm and a length of 20 mm; Apple juice, obtained by mechanical destruction of cells; pressed Apple pulp (juice content of not more than 20%obtained by the centrifugal separation, which destroyed the system of cells. For plant tissue with a holistic system of cells in the field 103 - 105 Hz is observed pronounced minimum angle of phase shift. In the absence of cells and its value is greatly reduced .The equivalent electrical circuit fabrics are considered. The calculation of all its elements is made. The equivalent capacitance of the electrical double layer at the interface of metal measuring electrode and extracellular fluid is element of C1 . The electrical resistance of this layer alternating current is characterized by the element R1 . Chain parallel connected resistance and capacitance describes the system of plant cells. The capacitance C2 is due to the electrical capacity of the cell membranes, and the resistance R2 is the electrical resistance of the membranes and intracellular space.The coincidence of experimental and calculated data in a frequency range of more than 103 Hz satisfactory. In the region of lower frequencies is observed differences. This may be due to the specific behavior of the electrical double layer. However, in the frequency region where the electrical properties of the cell structure of the investigated tissue match good, which proves the validity of the considered equivalent circuit. It is shown that the value of the complex electrical impedance of vegetable tissue in the frequency range from 103 Hz to 105
Graphene-based THz modulator analyzed by equivalent circuit model
DEFF Research Database (Denmark)
Xiao, Binggang; Chen, Jing; Xie, Zhiyi
2016-01-01
A terahertz (THz) modulator based on graphene is proposed and analysed by use of equivalent transmission line of a homogeneous mediumand the local anisotropic model of the graphene conductivity. The result calculated by the equivalent circuit is consistent with that obtained byFresnel transfer...
International Nuclear Information System (INIS)
Bao Bo-Cheng; Feng Fei; Dong Wei; Pan Sai-Hu
2013-01-01
A flux-controlled memristor characterized by smooth cubic nonlinearity is taken as an example, upon which the voltage—current relationships (VCRs) between two parallel memristive circuits — a parallel memristor and capacitor circuit (the parallel MC circuit), and a parallel memristor and inductor circuit (the parallel ML circuit) — are investigated. The results indicate that the VCR between these two parallel memristive circuits is closely related to the circuit parameters, and the frequency and amplitude of the sinusoidal voltage stimulus. An equivalent circuit model of the memristor is built, upon which the circuit simulations and experimental measurements of both the parallel MC circuit and the parallel ML circuit are performed, and the results verify the theoretical analysis results
Equivalence Checking of Combinational Circuits using Boolean Expression Diagrams
DEFF Research Database (Denmark)
Hulgaard, Henrik; Williams, Poul Frederick; Andersen, Henrik Reif
1999-01-01
The combinational logic-level equivalence problem is to determine whether two given combinational circuits implement the same Boolean function. This problem arises in a number of CAD applications, for example when checking the correctness of incremental design changes (performed either manually...... or by a design automation tool).This paper introduces a data structure called Boolean Expression Diagrams (BEDs) and two algorithms for transforming a BED into a Reduced Ordered Binary Decision Diagram (OBDD). BEDs are capable of representing any Boolean circuit in linear space and can exploit structural...... similarities between the two circuits that are compared. These properties make BEDs suitable for verifying the equivalence of combinational circuits. BEDs can be seen as an intermediate representation between circuits (which are compact) and OBDDs (which are canonical).Based on a large number of combinational...
Formalization, equivalence and generalization of basic resonance electrical circuits
Penev, Dimitar; Arnaudov, Dimitar; Hinov, Nikolay
2017-12-01
In the work are presented basic resonance circuits, which are used in resonance energy converters. The following resonant circuits are considered: serial, serial with parallel load parallel capacitor, parallel and parallel with serial loaded inductance. For the circuits under consideration, expressions are generated for the frequencies of own oscillations and for the equivalence of the active power emitted in the load. Mathematical expressions are graphically constructed and verified using computer simulations. The results obtained are used in the model based design of resonant energy converters with DC or AC output. This guaranteed the output indicators of power electronic devices.
Fleischer, Christian; Waag, Wladislaw; Heyn, Hans-Martin; Sauer, Dirk Uwe
2014-08-01
Lithium-ion battery systems employed in high power demanding systems such as electric vehicles require a sophisticated monitoring system to ensure safe and reliable operation. Three major states of the battery are of special interest and need to be constantly monitored, these include: battery state of charge (SoC), battery state of health (capcity fade determination, SoH), and state of function (power fade determination, SoF). In a series of two papers, we propose a system of algorithms based on a weighted recursive least quadratic squares parameter estimator, that is able to determine the battery impedance and diffusion parameters for accurate state estimation. The functionality was proven on different battery chemistries with different aging conditions. The first paper investigates the general requirements on BMS for HEV/EV applications. In parallel, the commonly used methods for battery monitoring are reviewed to elaborate their strength and weaknesses in terms of the identified requirements for on-line applications. Special emphasis will be placed on real-time capability and memory optimized code for cost-sensitive industrial or automotive applications in which low-cost microcontrollers must be used. Therefore, a battery model is presented which includes the influence of the Butler-Volmer kinetics on the charge-transfer process. Lastly, the mass transport process inside the battery is modeled in a novel state-space representation.
Equivalent Circuit Modeling of a Rotary Piezoelectric Motor
DEFF Research Database (Denmark)
El, Ghouti N.; Helbo, Jan
2000-01-01
In this paper, an enhanced equivalent circuit model of a rotary traveling wave piezoelectric ultrasonic motor "shinsei type USR60" is derived. The modeling is performed on the basis of an empirical approach combined with the electrical network method and some simplification assumptions about the ...
Modelling of multilayer piezoelectric transducers for echographic applications Equivalent circuits
International Nuclear Information System (INIS)
Ramos, A.; Riera, E.; San Emeterio, J.L.; Sanz, P.T.
1988-01-01
In this paper, the main equivalent circuits of pulse-echo, single element, multilayer piezoelectric transducers, are analysed. The analogy of matching layers with lossless transmission lines is described. Finally, using the KLM model, the effects of backing and matching layers on the bandwidth and impulse response is analysed. (Author)
Large impedances and Majorana bound states in superconducting circuits
International Nuclear Information System (INIS)
Ulrich, Jascha
2017-01-01
Superconducting circuits offer the opportunity to study quantum mechanics on mesoscopic scales unimpeded by dissipation. This fact and the nonlinearity of the Josephson inductance make it possible to use superconducting circuits as artificial atoms whose long-lived states can be selectively addressed and studied. A pronounced nonlinearity of the energy spectrum, however, requires quantum fluctuations of the flux across the Josephson junction which are large on the scale of the superconducting flux quantum Φ Q =h/2e. This implies charge fluctuations below the single Cooper-pair limit via flux-charge duality. The localization of charge leads to a strong susceptibility to interactions with charges in the environment which has motivated the search for schemes to decouple charges from their environment. This thesis is concerned with theoretical challenges arising from two complementary approaches to this problem: the realization of large impedances and the fractionalization of electrons by means of Majorana bound states. In recent years, the decoupling of charges from the environment through reactive large impedances, so-called ''superinductances'' L, has attracted much interest. These inductances feature small parasitic capacitance C such that the characteristic impedance √(L/C) is much larger than the superconducting resistance quantum R Q =h/4e 2 . Superinductances have various applications ranging from qubit designs such as the 0-π qubit or the fluxonium to impedance matching, Bloch oscillations and the stabilization of phase slips in superconducting nanowires. Although there exists a well-established formalism for the quantization of superconducting circuits in terms of node fluxes, this formalism is ill-suited for the description of fast flux transport with localized charges in large-impedance environments. In particular, the nonlinear capacitive behavior of phase slip junctions cannot be modeled in a straightforward way using node fluxes
Equivalent Circuit Modeling of the Dielectric Loaded Microwave Biosensor
Directory of Open Access Journals (Sweden)
M. T. Jilani
2014-12-01
Full Text Available This article describes the modeling of biological tissues at microwave frequency using equivalent lumped elements. A microwave biosensor based on microstrip ring resonator (MRR, that has been utilized previously for meat quality evaluation is used for this purpose. For the first time, the ring-resonator loaded with the lossy and high permittivity dielectric material, such as; biological tissue, in a partial overlay configuration is analyzed. The equivalent circuit modeling of the structure is then performed to identify the effect of overlay thickness on the resonance frequency. Finally, the relationship of an overlay thickness with the corresponding RC values of the meat equivalent circuit is established. Simulated, calculated and measured results are then compared for validation. Results are well agreed while the observed discrepancy is in acceptable limit.
Lumped-parameters equivalent circuit for condenser microphones modeling.
Esteves, Josué; Rufer, Libor; Ekeom, Didace; Basrour, Skandar
2017-10-01
This work presents a lumped parameters equivalent model of condenser microphone based on analogies between acoustic, mechanical, fluidic, and electrical domains. Parameters of the model were determined mainly through analytical relations and/or finite element method (FEM) simulations. Special attention was paid to the air gap modeling and to the use of proper boundary condition. Corresponding lumped-parameters were obtained as results of FEM simulations. Because of its simplicity, the model allows a fast simulation and is readily usable for microphone design. This work shows the validation of the equivalent circuit on three real cases of capacitive microphones, including both traditional and Micro-Electro-Mechanical Systems structures. In all cases, it has been demonstrated that the sensitivity and other related data obtained from the equivalent circuit are in very good agreement with available measurement data.
MAGNETIC CIRCUIT EQUIVALENT OF THE SYNCHRONOUS MOTOR WITH INCORPORATED MAGNETS
Directory of Open Access Journals (Sweden)
Fyong Le Ngo
2015-01-01
Full Text Available Magnetic circuitry computation is one of the central stages of designing a synchronous motor with incorporated magnets, which can be performed by means of a simplified method of the magnetic-circuits equivalent modeling. The article studies the magnetic circuit of the motor with the rotor-incorporated magnets, which includes four sectors: constant magnets with the field pole extension made of magnetically soft steel, magniflux dispersion sections containing air barriers and steel bridges; the air gap; the stator grooves, cogs and the frame yoke. The authors introduce an equivalent model of the magnetic circuit. High-energy magnets with a linear demagnetization curve are employed in the capacity of constant magnets. Two magnets create the magnetic flux for one pole. The decline of magnetic potential in the steel of the pole is negligible consequent on the admission that the poles magnetic inductivity µ = ∞. The rotor design provides for the air barriers and the steel bridges that close leakage flux. The induction-permeability curve linearization serves for the bridges magnetic saturation accountability and presents a polygonal line consisting of two linear sections. The estimation of the magnet circuit section including the cogs and the frame yoke is executed with account of the steel saturation, their magnetic conductivities thereat being dependent on the saturation rate. Relying on the equivalent model of the magnetic circuit, the authors deduce a system of two equations written from the first and the second Kirchhoff laws of the magnetic circuits. These equations allow solving two problems: specifying dimensions of the magnets by the preset value of the magnetic flow in the clearance and determining the clearance magnetic flow at the preset motor rotor-and-stator design.
Physically-insightful equivalent circuit models for electromagnetic periodic structures
Mesa, F.; Rodríguez-Berral, R.; Medina, F.
2018-02-01
In this presentation it will be discussed how to obtain analytical or quasi-analytical equivalent circuits to deal with periodic structures such as frequency selective surfaces and/or metasurfaces. Both the topology and the values of the involved elements of these circuits are obtained from a basic rationale to solve the corresponding integral equation. This procedure, besides providing a very efficient analysis/design tool, allows for a good physical insight into the operating mechanisms of the structure in contrast with the almost blind numerical scheme of commercial simulators.
On the electrical equivalent circuits of gravitational-wave antennas
International Nuclear Information System (INIS)
Pallottino, G.V.; Pizzella, G.; Rome Univ.
1978-01-01
The electrical equivalent circuit of a Weber gravitational-wave antenna with piezoelectric transducers is derived for the various longitudinal normal modes by using the Lagrangian formalism. The analysis is applied to the antenna without piezoelectric ceramics, as well as with one or more ceramics operated in both passive and active mode. Particular attention is given to the dissipation problem in order to obtain an expression of the overall merit factor directly related to the physics of the actual dissipation processes. As an example the results are applied to a cylindrical bar with two ceramics: one for calibrating the antenna, the other as sensor of the motion. The values of the physical parameters and of the pertinent parameters of the equivalent circuit for the small antenna (20 kg) and those (predicted) for the intermediate antenna (390 kg) of the Rome group are given in the appendix. (author)
Equivalent Circuit for Magnetoelectric Read and Write Operations
Camsari, Kerem Y.; Faria, Rafatul; Hassan, Orchi; Sutton, Brian M.; Datta, Supriyo
2018-04-01
We describe an equivalent circuit model applicable to a wide variety of magnetoelectric phenomena and use spice simulations to benchmark this model against experimental data. We use this model to suggest a different mode of operation where the 1 and 0 states are represented not by states with net magnetization (like mx , my, or mz) but by different easy axes, quantitatively described by (mx2-my2), which switches from 0 to 1 through the write voltage. This change is directly detected as a read signal through the inverse effect. The use of (mx2-my2) to represent a bit is a radical departure from the standard convention of using the magnetization (m ) to represent information. We then show how the equivalent circuit can be used to build a device exhibiting tunable randomness and suggest possibilities for extending it to nonvolatile memory with read and write capabilities, without the use of external magnetic fields or magnetic tunnel junctions.
Equivalent Circuit Modeling of a Rotary Piezoelectric Motor
DEFF Research Database (Denmark)
El, Ghouti N.; Helbo, Jan
2000-01-01
In this paper, an enhanced equivalent circuit model of a rotary traveling wave piezoelectric ultrasonic motor "shinsei type USR60" is derived. The modeling is performed on the basis of an empirical approach combined with the electrical network method and some simplification assumptions about...... of the temperature on the mechanical resonance frequency is considered and thereby integrated in the final model for long term operations....
Equivalent Circuit of a High Q Tunable PIFA
DEFF Research Database (Denmark)
Barrio, Samantha Caporal Del; Pelosi, Mauro; Franek, Ondrej
2011-01-01
This paper presents an Equivalent Circuit Model (ECM) for a high Quality factor (Q) tunable Planar Inverted F Antenna (PIFA). A PIFA is described and simulated with the Finite-Difference Time-Domain (FDTD) method. The resonance behavior of the proposed ECM is compared to the FDTD results and shows...... a match. The ECM is also valid when the PIFA is made tunable with an additional capacitor....
Energy Technology Data Exchange (ETDEWEB)
Ema, S [Numazu College of Technology, Shizuoka (Japan); Ajiki, K [Railway Technical Research Inst., Tokyo (Japan)
1993-09-20
In connection with the impedance frequency characteristics of the coils for propulsion and the power feeding circuit of the magnetically levitated train (MAGLEV), the inverted L circuit and T circuit as equivalent circuits for the coil for propulsion and for the power feeding, respectively, are proposed and analyzed. The simulated result and the result of measurement reported by now are in good agreement, the measured values and calculated values being almost equal in both the characteristics of the coils for propulsion and those of the power feeding circuit. The validity of the two equivalent circuits are clarified, and the frequency characteristics are verified theoretically. The impedance frequency characteristics of the coils for propulsion which are peculiar to MAGLEV are investigated with the power feeding circuit consisting of the power feeding line and propulsion coils. Lastly, simulation is carried out for the coils for propulsion with several hundred propulsion coils and for the power feeding system assuming the commercial line. As a result, it is found that the antiresonant frequencies are decreased to about one tenth in both of the characteristics. 11 refs., 18 figs.
Equivalent circuit study of beam-loading using a moment method
International Nuclear Information System (INIS)
Wang, T.F.; Machida, S.; Mori, Y.; Ohmori, C.
1997-01-01
In this work, we present a formalism by considering the perturbations in the moments of a bunched beam for the equivalent circuit model to include all harmonics of the synchroton oscillation in a beam-cavity interaction system. The linear coupling among all longitudinal modes under the influence of narrow-band impedance can be naturally incorporated in this new approach. We used this method to re-examine the coupling between the dipole and the quadrupole modes. The dispersion relation obtained by this new method was compared with that derived from the linearized Vlasov equation up to the second harmonic of the synchrotron motion. We found excellent qualitative agreements between two approaches
Improved equivalent circuit for twin slot terahertz receivers
McGrath, W. R.
2002-01-01
Series-fed coplanar waveguide embedding circuits are being developed for terahertz mixers using, in particular, submicron-sized superconducting devices, such as hot electron bolometers as the nonlinear element. Although these mixers show promising performance, they usually also show a considerable downward shift in the center frequency, when compared with simulations obtained by using simplified models. This makes it very difficult to design low-noise mixers for a given THz frequency. This shiftis principally caused by parasitics due to the extremely small details (in terms of wavelength) of the device, and by the electrical properties of the RF choke filter in the DC/IF line. In this paper, we present an improved equivalent network model of such mixer circuits which agrees with measured results at THz frequencies and we propose a new set of THz bolometric mixers that have been fabricated and are currently being tested.
The short-circuit concept used in field equivalence principles
DEFF Research Database (Denmark)
Appel-Hansen, Jørgen
1990-01-01
In field equivalence principles, electric and magnetic surface currents are specified and considered as impressed currents. Often the currents are placed on perfect conductors. It is shown that these currents can be treated through two approaches. The first approach is decomposition of the total...... field into partial fields caused by the individual impressed currents. When this approach is used, it is shown that, on a perfect electric (magnetic) conductor, impressed electric (magnetic) surface currents are short-circuited. The second approach is to note that, since Maxwell's equations...... and the boundary conditions are satisfied, none of the impressed currents is short-circuited and no currents are induced on the perfect conductors. Since all currents and field quantities are considered at the same time, this approach is referred to as the total-field approach. The partial-field approach leads...
Alizadeh Sahraei, Abolfazl; Ayati, Moosa; Baniassadi, Majid; Rodrigue, Denis; Baghani, Mostafa; Abdi, Yaser
2018-03-01
This study attempts to comprehensively investigate the effects of multi-walled carbon nanotubes (MWCNTs) on the AC and DC electrical conductivity of epoxy nanocomposites. The samples (0.2, 0.3, and 0.5 wt. % MWCNT) were produced using a combination of ultrason and shear mixing methods. DC measurements were performed by continuous measurement of the current-voltage response and the results were analyzed via a numerical percolation approach, while for the AC behavior, the frequency response was studied by analyzing phase difference and impedance in the 10 Hz to 0.2 MHz frequency range. The results showed that the dielectric parameters, including relative permittivity, impedance phase, and magnitude, present completely different behaviors for the frequency range and MWCNT weight fractions studied. To better understand the nanocomposites electrical behavior, equivalent electric circuits were also built for both DC and AC modes. The DC equivalent networks were developed based on the current-voltage curves, while the AC equivalent circuits were proposed by using an optimization problem according to the impedance magnitude and phase at different frequencies. The obtained equivalent electrical circuits were found to be highly useful tools to understand the physical mechanisms involved in MWCNT filled polymer nanocomposites.
A new equivalent circuit model for micro electroporation systems
Shagoshtasbi, Hooman
2011-02-01
Electroporation (EP) is a unique biotechnique in which intense electric pulses are applied on the cell membrane to temporarily generate nanoscale electropores and to increase the membrane permeability for the delivery of exogenous biomolecules or drugs. We propose a new equivalent circuit model with 8 electric components to predict the electrodynamic response of a micro EP system. As the permeability of the cell membrane increases, the membrane resistance decreases. The numerical simulations of the transmembrane current responses to different applied voltages (1∼6V) are consistent with the experimental results using HeLa cells. Besides, the transmembrane voltage as a function of applied voltages is determined as well. These transmembrane current and voltage responses can be extremely useful for the design of new generation of micro EP systems for transfection of large DNA molecules in the future. © 2011 IEEE.
A new equivalent circuit model for micro electroporation systems
Shagoshtasbi, Hooman; Lee, Yi-Kuen
2011-01-01
Electroporation (EP) is a unique biotechnique in which intense electric pulses are applied on the cell membrane to temporarily generate nanoscale electropores and to increase the membrane permeability for the delivery of exogenous biomolecules or drugs. We propose a new equivalent circuit model with 8 electric components to predict the electrodynamic response of a micro EP system. As the permeability of the cell membrane increases, the membrane resistance decreases. The numerical simulations of the transmembrane current responses to different applied voltages (1∼6V) are consistent with the experimental results using HeLa cells. Besides, the transmembrane voltage as a function of applied voltages is determined as well. These transmembrane current and voltage responses can be extremely useful for the design of new generation of micro EP systems for transfection of large DNA molecules in the future. © 2011 IEEE.
Simulation of Ni-MH Batteries via an Equivalent Circuit Model for Energy Storage Applications
Directory of Open Access Journals (Sweden)
Ying Zhu
2016-01-01
Full Text Available Impedance measurement was conducted at the entire cell level for studying of the Ni-MH rechargeable batteries. An improved equivalent circuit model considering diffusion process is proposed for simulation of battery impedance data at different charge input levels. The cell capacity decay was diagnosed by analyzing the ohmic resistance, activation resistance, and mass transfer resistance of the Ni-MH cells with degraded capacity. The capacity deterioration of this type, Ni-MH cell, is considered in relation to the change of activation resistance of the nickel positive electrodes. Based on the report and surface analysis obtained from the energy dispersive X-ray spectroscopy, the composition formula of metal-hydride electrodes can be closely documented as the AB5 type alloy and the “A” elements are recognized as lanthanum (La and cerium (Ce. The capacity decay of the Ni-MH cell is potentially initiated due to starved electrolyte for the electrochemical reaction of active materials inside the Ni-MH battery, and the discharge product of Ni(OH2 at low state-of-charge level is anticipated to have more impeding effects on electrode kinetic process for higher power output and efficient energy delivery.
Equivalent Electrical Circuits of Thermoelectric Generators under Different Operating Conditions
Directory of Open Access Journals (Sweden)
Saima Siouane
2017-03-01
Full Text Available Energy harvesting has become a promising and alternative solution to conventional energy generation patterns to overcome the problem of supplying autonomous electrical systems. More particularly, thermal energy harvesting technologies have drawn a major interest in both research and industry. Thermoelectric Generators (TEGs can be used in two different operating conditions, under constant temperature gradient or constant heat flow. The commonly used TEG electrical model, based on a voltage source in series with an electrical resistance, shows its limitations especially under constant heat flow conditions. Here, the analytical electrical modeling, taking into consideration the internal and contact thermal resistances of a TEG under constant temperature gradient and constant heat flow conditions, is first given. To give further insight into the electrical behavior of a TEG module in different operating conditions, we propose a new and original way of emulating the above analytical expressions with usual electronics components (voltage source, resistors, diode, whose values are determined with the TEG’s parameters. Note that such a TEG emulation is particularly suited when designing the electronic circuitry commonly associated to the TEG, to realize both Maximum Power Point Tracking and output voltage regulation. First, the proposed equivalent electrical circuits are validated through simulation with a SPICE environment in static operating conditions using only one value of either temperature gradient or heat flow. Then, they are also analyzed in dynamic operating conditions where both temperature gradient and heat flow are considered as time-varying functions.
Equivalent circuit simulation of HPEM-induced transient responses at nonlinear loads
Directory of Open Access Journals (Sweden)
M. Kotzev
2017-09-01
Full Text Available In this paper the equivalent circuit modeling of a nonlinearly loaded loop antenna and its transient responses to HPEM field excitations are investigated. For the circuit modeling the general strategy to characterize the nonlinearly loaded antenna by a linear and a nonlinear circuit part is pursued. The linear circuit part can be determined by standard methods of antenna theory and numerical field computation. The modeling of the nonlinear circuit part requires realistic circuit models of the nonlinear loads that are given by Schottky diodes. Combining both parts, appropriate circuit models are obtained and analyzed by means of a standard SPICE circuit simulator. It is the main result that in this way full-wave simulation results can be reproduced. Furthermore it is clearly seen that the equivalent circuit modeling offers considerable advantages with respect to computation speed and also leads to improved physical insights regarding the coupling between HPEM field excitation and nonlinearly loaded loop antenna.
Inductance analyzer based on auto-balanced circuit for precision measurement of fluxgate impedance
Setiadi, Rahmondia N.; Schilling, Meinhard
2018-05-01
An instrument for fluxgate sensor impedance measurement based on an auto-balanced circuit has been designed and characterized. The circuit design is adjusted to comply with the fluxgate sensor characteristics which are low impedance and highly saturable core with very high permeability. The system utilizes a NI-DAQ card and LabVIEW to process the signal acquisition and evaluation. Some fixed reference resistances are employed for system calibration using linear regression. A multimeter HP 34401A and impedance analyzer Agilent 4294A are used as calibrator and validator for the resistance and inductance measurements. Here, we realized a fluxgate analyzer instrument based on auto-balanced circuit, which measures the resistance and inductance of the device under test with a small error and much lower excitation current to avoid core saturation compared to the used calibrator.
Impedance Matching Antenna-Integrated High-Efficiency Energy Harvesting Circuit
Shinki, Yuharu; Shibata, Kyohei; Mansour, Mohamed
2017-01-01
This paper describes the design of a high-efficiency energy harvesting circuit with an integrated antenna. The circuit is composed of series resonance and boost rectifier circuits for converting radio frequency power into boosted direct current (DC) voltage. The measured output DC voltage is 5.67 V for an input of 100 mV at 900 MHz. Antenna input impedance matching is optimized for greater efficiency and miniaturization. The measured efficiency of this antenna-integrated energy harvester is 60% for −4.85 dBm input power and a load resistance equal to 20 kΩ at 905 MHz. PMID:28763043
Impedance Matching Antenna-Integrated High-Efficiency Energy Harvesting Circuit
Directory of Open Access Journals (Sweden)
Yuharu Shinki
2017-08-01
Full Text Available This paper describes the design of a high-efficiency energy harvesting circuit with an integrated antenna. The circuit is composed of series resonance and boost rectifier circuits for converting radio frequency power into boosted direct current (DC voltage. The measured output DC voltage is 5.67 V for an input of 100 mV at 900 MHz. Antenna input impedance matching is optimized for greater efficiency and miniaturization. The measured efficiency of this antenna-integrated energy harvester is 60% for −4.85 dBm input power and a load resistance equal to 20 kΩ at 905 MHz.
Impedance Matching Antenna-Integrated High-Efficiency Energy Harvesting Circuit.
Shinki, Yuharu; Shibata, Kyohei; Mansour, Mohamed; Kanaya, Haruichi
2017-08-01
This paper describes the design of a high-efficiency energy harvesting circuit with an integrated antenna. The circuit is composed of series resonance and boost rectifier circuits for converting radio frequency power into boosted direct current (DC) voltage. The measured output DC voltage is 5.67 V for an input of 100 mV at 900 MHz. Antenna input impedance matching is optimized for greater efficiency and miniaturization. The measured efficiency of this antenna-integrated energy harvester is 60% for -4.85 dBm input power and a load resistance equal to 20 kΩ at 905 MHz.
International Nuclear Information System (INIS)
Kwon, Woosung; Kim, Jung-Min; Rhee, Shi-Woo
2012-01-01
In this research, a new equivalent circuit for porous carbon electrodes is proposed. In order to analyze the validity of the new model, electrochemical impedance spectra of carbon black (CB) electrodes in a symmetric cell configuration are examined by varying the CB particle size and the electrode thickness. This model decouples and identifies the following elements: (i) the electron transport resistance and trap capacitance in the CB layer, (ii) the charge transfer resistance and the double layer capacitance, and (iii) the Nernst diffusion impedance at the electrode/electrolyte interface. The fit quality is quantified by the chi-square test, and the fit data show consistency with the measured conductivity, surface area, and thickness of the CB electrode.
Two dimensional analysis of MHD generator by means of equivalent circuit
International Nuclear Information System (INIS)
Yoshida, Masaharu; Umoto, Juro
1975-01-01
The authors report on the method analyzing generally the MHD generator by means of the equivalent circuit including the negative resistance. At first, they divide the duct space into many space elements, and for each space element they derive the fundamental equivalent four-terminal circuit which satisfies the two-dimensional Ohm's law. Next, they make an attempt to apply the equivalent circuits to the typical MHD generators such as diagonal, Faraday and Hall generators considering the boundary layer in the duct and the wall leakage current. Using their analysis, the current density, Joul's heat, generated and output electrical powers, electrical efficiency etc. in the generator can be fairly easily calculated. (auth.)
Electrical impedance tomography system: an open access circuit design
Directory of Open Access Journals (Sweden)
Soleimani Manuchehr
2006-05-01
Full Text Available Abstract Background This paper reports a simple 2-D system for electrical impedance tomography EIT, which works efficiently and is low cost. The system has been developed in the Sharif University of Technology Tehran-Iran (for the author's MSc Project. Methods The EIT system consists of a PC in which an I/O card is installed with an external current generator, a multiplexer, a power supply and a phantom with an array of electrodes. The measurement system provides 12-bit accuracy and hence, suitable data acquisition software has been prepared accordingly. The synchronous phase detection method has been implemented for voltage measurement. Different methods of image reconstruction have been used with this instrument to generate electrical conductivity images. Results The results of simulation and real measurement of the system are presented. The reconstruction programs were written in MATLAB and the data acquisition software in C++. The system has been tested with both static and dynamic mode in a 2-D domain. Better results have been produced in the dynamic mode of operation, due to the cancellation of errors. Conclusion In the spirit of open access publication the design details of this simple EIT system are made available here.
Sato-Akaba, Hideo
2014-01-01
A low impedance transceiver circuit consisting of a transmit-receive switch circuit, a class-D amplifier and a transimpedance amplifier (TIA) was newly designed and tested for a nitrogen-14 NQR. An NQR signal at 1.37MHz from imidazole was successfully observed with the dead time of ~85µs under the high Q transmission (Q~120) and reception (Q~140). The noise performance of the low impedance TIA with an NQR probe was comparable with a commercial low noise 50Ω amplifier (voltage input noise: 0.25 nV/Hz) which was also connected to the probe. The protection voltage for the pre-amplifier using the low impedance transceiver was ~10 times smaller than that for the pre-amplifier using a 50Ω conventional transceiver, which is suitable for NQR remote sensing applications. Copyright © 2014 Elsevier Inc. All rights reserved.
Huh, Junghwan; Na, Junhong; Ha, Jeong Sook; Kim, Sangtae; Kim, Gyu Tae
2011-08-01
Electrical contacts between the nanomaterial and metal electrodes are of crucial importance both from fundamental and practical points of view. We have systematically compared the influence of contact properties by dc and EIS (Electrochemical impedance spectroscopy) techniques at various temperatures and environmental atmospheres (N(2) and 1% O(2)). Electrical behaviors are sensitive to the variation of Schottky barriers, while the activation energy (E(a)) depends on the donor states in the nanowire rather than on the Schottky contact. Equivalent circuits in terms of dc and EIS analyses could be modeled by Schottky diodes connected with a series resistance and parallel RC circuits, respectively. These results can facilitate the electrical analysis for evaluating the nanowire electronic devices with Schottky contacts.
Inter digital transducer modelling through Mason equivalent circuit model
DEFF Research Database (Denmark)
Mishra, Dipti; Singh, Abhishek; Hussain, Dil muhammed Akbar
2016-01-01
) is projected which is well-suited with a broadly cast-off universal resolution circuit simulator SPICE built-in out with the proficiency to simulate the negative capacitances and inductances. The investigation is done to prove the straightforwardness of establishing the frequency and time domain physical...
Analysis of Equivalent Circuits for Cells: A Fractional Calculus Approach
Directory of Open Access Journals (Sweden)
Bernal-Alvarado J.
2012-07-01
Full Text Available Fractional order systems are considered by many mathematicians the systems of the XXI century. The reason is that nature has proved to be best described in terms of systems composed of fractional order derivatives. This emerging area of research is slowly gaining more strength in engineering, biochemistry, medicine, biophysics, among others. This paper presents an analysis in the frequency domain equivalent of cellular systems described by equations of integer and fractional order; it also carries out an analysis in time domain in order to display the memory capacity of fractional systems. It presents the fractional differential equations equivalent models and simulations comparing integer and fractional order.
The negative differential resistance characteristics of an RC-IGBT and its equivalent circuit model
International Nuclear Information System (INIS)
Zhang Wenliang; Zhu Yangjun; Tian Xiaoli; Lu Shuojin
2014-01-01
A simple equivalent circuit model is proposed according to the device structure of reverse conducting insulated gate bipolar transistors (RC-IGBT). Mathematical derivation and circuit simulations indicate that this model can explain the snap-back effect (including primary snap-back effect, secondary snap-back effect, and reverse snap-back effect) and hysteresis effect perfectly. (semiconductor devices)
Roussy, Georges; Dichtel, Bernard; Chaabane, Haykel
2003-01-01
By using a new integrated circuit, which is marketed for bluetooth applications, it is possible to simplify the method of measuring the complex impedance, complex reflection coefficient and complex transmission coefficient in an industrial microwave setup. The Analog Devices circuit AD 8302, which measures gain and phase up to 2.7 GHz, operates with variable level input signals and is less sensitive to both amplitude and frequency fluctuations of the industrial magnetrons than are mixers and AM crystal detectors. Therefore, accurate gain and phase measurements can be performed with low stability generators. A mechanical setup with an AD 8302 is described; the calibration procedure and its performance are presented.
Directory of Open Access Journals (Sweden)
MANFREDI, P.
2014-11-01
Full Text Available This paper extends recent literature results concerning the statistical simulation of circuits affected by random electrical parameters by means of the polynomial chaos framework. With respect to previous implementations, based on the generation and simulation of augmented and deterministic circuit equivalents, the modeling is extended to generic and ?black-box? multi-terminal nonlinear subcircuits describing complex devices, like those found in integrated circuits. Moreover, based on recently-published works in this field, a more effective approach to generate the deterministic circuit equivalents is implemented, thus yielding more compact and efficient models for nonlinear components. The approach is fully compatible with commercial (e.g., SPICE-type circuit simulators and is thoroughly validated through the statistical analysis of a realistic interconnect structure with a 16-bit memory chip. The accuracy and the comparison against previous approaches are also carefully established.
Fan, Xu; Wang, Yunguang; Cheng, Haiping; Chong, Xiaochen
2016-02-01
The present circuit was designed to apply to human tissue impedance tuning and matching device in ultra-short wave treatment equipment. In order to judge if the optimum status of circuit parameter between energy emitter circuit and accepter circuit is in well syntony, we designed a high frequency envelope detect circuit to coordinate with automatic adjust device of accepter circuit, which would achieve the function of human tissue impedance matching and tuning. Using the sampling coil to receive the signal of amplitude-modulated wave, we compared the voltage signal of envelope detect circuit with electric current of energy emitter circuit. The result of experimental study was that the signal, which was transformed by the envelope detect circuit, was stable and could be recognized by low speed Analog to Digital Converter (ADC) and was proportional to the electric current signal of energy emitter circuit. It could be concluded that the voltage, transformed by envelope detect circuit can mirror the real circuit state of syntony and realize the function of human tissue impedance collecting.
Gomez, Jamie; Nelson, Ruben; Kalu, Egwu E.; Weatherspoon, Mark H.; Zheng, Jim P.
2011-05-01
Equivalent circuit model (EMC) of a high-power Li-ion battery that accounts for both temperature and state of charge (SOC) effects known to influence battery performance is presented. Electrochemical impedance measurements of a commercial high power Li-ion battery obtained in the temperature range 20 to 50 °C at various SOC values was used to develop a simple EMC which was used in combination with a non-linear least squares fitting procedure that used thirteen parameters for the analysis of the Li-ion cell. The experimental results show that the solution and charge transfer resistances decreased with increase in cell operating temperature and decreasing SOC. On the other hand, the Warburg admittance increased with increasing temperature and decreasing SOC. The developed model correlations that are capable of being used in process control algorithms are presented for the observed impedance behavior with respect to temperature and SOC effects. The predicted model parameters for the impedance elements Rs, Rct and Y013 show low variance of 5% when compared to the experimental data and therefore indicates a good statistical agreement of correlation model to the actual experimental values.
Wang, Hao; Zhang, Fengge; Guan, Tao; Yu, Siyang
2017-09-01
A brushless electrically excited synchronous generator (BEESG) with a hybrid rotor is a novel electrically excited synchronous generator. The BEESG proposed in this paper is composed of a conventional stator with two different sets of windings with different pole numbers, and a hybrid rotor with powerful coupling capacity. The pole number of the rotor is different from those of the stator windings. Thus, an analysis method different from that applied to conventional generators should be applied to the BEESG. In view of this problem, the equivalent circuit and electromagnetic torque expression of the BEESG are derived on the basis of electromagnetic relation of the proposed generator. The generator is simulated and tested experimentally using the established equivalent circuit model. The experimental and simulation data are then analyzed and compared. Results show the validity of the equivalent circuit model.
Energy Technology Data Exchange (ETDEWEB)
Rittinghaus, D
1981-09-01
The complex short-circuit impedances of energized low-voltage main systems were measured with a double-bridge in underground mining operation. The magnitude of the short-circuit currents depends on these impedances. Customary calculations of such currents depend on empirical approximations. To verify the accuracy of these approximations, the measured impedances of 61 nodes in three different main systems were compared with the results of the calculations. The comparison made between the short-circuit currents determined by measurable quantities and the values calculated according to VDE 0118 shows that the stipulated coefficients for calculating the minimum short-circuit currents lie very far on the safe side. An amendment for calculating the short-circuit in accordance with VDE 0118 is therefore suggested.
FEA identification of high order generalized equivalent circuits for MF high voltage transformers
Candolfi, Sylvain; Cros, Jérôme; Aguglia, Davide
2015-01-01
This paper presents a specific methodology to derive high order generalized equivalent circuits from electromagnetic finite element analysis for high voltage medium frequency and pulse transformers by splitting the main windings in an arbitrary number of elementary windings. With this modeling approach, the dynamic model of the transformer over a large bandwidth is improved and the order of the generalized equivalent circuit can be adapted to a specified bandwidth. This efficient tool can be used by the designer to quantify the influence of the local structure of transformers on their dynamic behavior. The influence of different topologies and winding configurations is investigated. Several application examples and an experimental validation are also presented.
Equivalent circuit modeling of space charge dominated magnetically insulated transmission lines
Energy Technology Data Exchange (ETDEWEB)
Hiraoka, Kazuki; Nakajima, Mitsuo; Horioka, Kazuhiko
1997-12-31
A new equivalent circuit model for space charge dominated MITLs (Magnetically Insulated Transmission Lines) was developed. MITLs under high power operation are dominated with space charge current flowing between anode and cathode. Conventional equivalent circuit model does not account for space charge effects on power flow. The model was modified to discuss the power transportation through the high power MITLs. With this model, it is possible to estimate the effects of space charge current on the power flow efficiency, without using complicated particle code simulations. (author). 3 figs., 3 refs.
International Nuclear Information System (INIS)
Taylan, O.; Berberoglu, H.
2014-01-01
This paper reports the electrical characterization and an equivalent circuit of a microhollow cathode discharge (MHCD) reactor in the self-pulsing regime. A MHCD reactor was prototyped for air plasma generation, and its current-voltage characteristics were measured experimentally in the self-pulsing regime for applied voltages from 2000 to 3000 V. The reactor was modeled as a capacitor in parallel with a variable resistor. A stray capacitance was also introduced to the circuit model to represent the capacitance of the circuit elements in the experimental setup. The values of the resistor and capacitors were recovered from experimental data, and the proposed circuit model was validated with independent experiments. Experimental data showed that increasing the applied voltage increased the current, self-pulsing frequency and average power consumption of the reactor, while it decreased the peak voltage. The maximum and the minimum voltages obtained using the model were in agreement with the experimental data within 2.5%, whereas the differences between peak current values were less than 1%. At all applied voltages, the equivalent circuit model was able to accurately represent the peak and average power consumption as well as the self-pulsing frequency within the experimental uncertainty. Although the results shown in this paper was for atmospheric air pressures, the proposed equivalent circuit model of the MHCD reactor could be generalized for other gases at different pressures.
International Nuclear Information System (INIS)
Mian, Muhammad Umer; Khir, M. H. Md.; Tang, T. B.; Dennis, John Ojur; Riaz, Kashif; Iqbal, Abid; Bazaz, Shafaat A.
2015-01-01
Pre-fabrication, behavioural and performance analysis with computer aided design (CAD) tools is a common and fabrication cost effective practice. In light of this we present a simulation methodology for a dual-mass oscillator based 3 Degree of Freedom (3-DoF) MEMS gyroscope. 3-DoF Gyroscope is modeled through lumped parameter models using equivalent circuit elements. These equivalent circuits consist of elementary components which are counterpart of their respective mechanical components, used to design and fabricate 3-DoF MEMS gyroscope. Complete designing of equivalent circuit model, mathematical modeling and simulation are being presented in this paper. Behaviors of the equivalent lumped models derived for the proposed device design are simulated in MEMSPRO T-SPICE software. Simulations are carried out with the design specifications following design rules of the MetalMUMPS fabrication process. Drive mass resonant frequencies simulated by this technique are 1.59 kHz and 2.05 kHz respectively, which are close to the resonant frequencies found by the analytical formulation of the gyroscope. The lumped equivalent circuit modeling technique proved to be a time efficient modeling technique for the analysis of complex MEMS devices like 3-DoF gyroscopes. The technique proves to be an alternative approach to the complex and time consuming couple field analysis Finite Element Analysis (FEA) previously used
Energy Technology Data Exchange (ETDEWEB)
Mian, Muhammad Umer, E-mail: umermian@gmail.com; Khir, M. H. Md.; Tang, T. B. [Department of Electrical and Electronic Engineering, Universiti Teknologi PETRONAS, Tronoh, Perak (Malaysia); Dennis, John Ojur [Department of Fundamental & Applied Sciences, Universiti Teknologi PETRONAS, Tronoh, Perak (Malaysia); Riaz, Kashif; Iqbal, Abid [Faculty of Electronics Engineering, GIK Institute of Engineering Sciences and Technology, Topi, Khyber Pakhtunkhaw (Pakistan); Bazaz, Shafaat A. [Department of Computer Science, Center for Advance Studies in Engineering, Islamabad (Pakistan)
2015-07-22
Pre-fabrication, behavioural and performance analysis with computer aided design (CAD) tools is a common and fabrication cost effective practice. In light of this we present a simulation methodology for a dual-mass oscillator based 3 Degree of Freedom (3-DoF) MEMS gyroscope. 3-DoF Gyroscope is modeled through lumped parameter models using equivalent circuit elements. These equivalent circuits consist of elementary components which are counterpart of their respective mechanical components, used to design and fabricate 3-DoF MEMS gyroscope. Complete designing of equivalent circuit model, mathematical modeling and simulation are being presented in this paper. Behaviors of the equivalent lumped models derived for the proposed device design are simulated in MEMSPRO T-SPICE software. Simulations are carried out with the design specifications following design rules of the MetalMUMPS fabrication process. Drive mass resonant frequencies simulated by this technique are 1.59 kHz and 2.05 kHz respectively, which are close to the resonant frequencies found by the analytical formulation of the gyroscope. The lumped equivalent circuit modeling technique proved to be a time efficient modeling technique for the analysis of complex MEMS devices like 3-DoF gyroscopes. The technique proves to be an alternative approach to the complex and time consuming couple field analysis Finite Element Analysis (FEA) previously used.
Novel pulse amplifying circuits based on transmission lines of different characteristic impedance
International Nuclear Information System (INIS)
Belloni, F.; Doria, D.; Lorusso, A.; Nassisi, V.
2006-01-01
Two novel circuits used to amplify electric pulses by the coupling of transmission lines of different characteristic impedance are described. The circuits are intended for doubling voltage pulses and for doubling current pulses. The former is composed by a R 0 transmission line closed on a set of two 2R 0 storage lines connected in parallel, while the latter is composed by a R 0 transmission line closed on a set of two R 0 /2 storage lines connected in series. The length of every storage line is half of input-pulse length. In both circuits, one storage line is characterized by an open extremity and the other line by a closed extremity. Connecting opportunely the storage lines to suitable load resistors, 4R 0 and R 0 /4, for the circuit having parallel and series connected lines, respectively, a twice of the output pulse intensity is obtained. Such devices are very suitable to generate high intensity voltage and/or current peaks which are very interesting in the field of the accelerators. Both circuit behaviours have been theoretically studied and verified by computer simulations
Simple Wide Frequency Range Impedance Meter Based on AD5933 Integrated Circuit
Directory of Open Access Journals (Sweden)
Chabowski Konrad
2015-03-01
Full Text Available As it contains elements of complete digital impedance meter, the AD5933 integrated circuit is an interesting solution for impedance measurements. However, its use for measurements in a wide range of impedances and frequencies requires an additional digital and analogue circuitry. This paper presents the design and performance of a simple impedance meter based on the AD5933 IC. Apart from the AD5933 IC it consists of a clock generator with a programmable prescaler, a novel DC offset canceller for the excitation signal based on peak detectors and a current to voltage converter with switchable conversion ratios. The authors proposed a simple method for choosing the measurement frequency to minimalize errors resulting from the spectral leakage and distortion caused by a lack of an anti-aliasing filter in the DDS generator. Additionally, a novel method for the AD5933 IC calibration was proposed. It consists in a mathematical compensation of the systematic error occurring in the argument of the value returned from the AD5933 IC as a result. The performance of the whole system is demonstrated in an exemplary measurement.
Energy Technology Data Exchange (ETDEWEB)
Zhu, Wenhua H.; Zhu Ying [Center for Microfibrous Materials, Department of Chemical Engineering, 212 Ross Hall, Auburn University, AL 36849-5127 (United States); Tatarchuk, Bruce J., E-mail: brucet@eng.auburn.edu [Center for Microfibrous Materials, Department of Chemical Engineering, 212 Ross Hall, Auburn University, AL 36849-5127 (United States)
2011-08-15
Highlights: {yields} Pb-acid battery is reexamined in electrode structure and capacitance enhancement. {yields} Pb-acid batteries were tested through the electrochemical impedance at loads. {yields} Electrode behaviors are evaluated by simulation using an equivalent circuit model. {yields} A defective and a failed Pb-acid battery was used in non-destructive analysis. {yields} Potential applications are for power reserve and sustainable electricity storage. - Abstract: Three main types of battery chemistries in consideration for vehicle applications are Pb-acid, nickel-metal hydride, and lithium-ion batteries. Lead-acid batteries are widely used in traditional automotive applications for many years. Higher voltage, high-rate discharge capability, good specific energy, lower temperature performance, lower thermal management requirement, and low-cost in both manufacturing and recycling are the advantages of the rechargeable battery. Disadvantages of the lead-acid battery are: weight concerns of lead metal (lower energy density and lower power density) and limited cycle-life (especially in deep-cycle duties). If two major disadvantages have been significantly changed to a proper state to compete with other battery chemistries, the Pb-acid battery is still a good candidate in considering of cost/performance ratio. The lead-acid battery is always a good power source for fast starting of cold vehicles, for recharging from either a stop-start braking system, or for a charge from the engine itself, which consumes battery energy or stores electricity back into chemical energy. The main reasons for reexamining this battery chemistry are cost-savings and life-cycling considerations upon advances in electrode structure design and enhancement of capacitance behavior inside the battery pack. Several Pb-acid batteries were evaluated and tested through a unique method, i.e., the electrochemical impedance method at different loads, in order to characterize and further understand the
International Nuclear Information System (INIS)
Zhu, Wenhua H.; Zhu Ying; Tatarchuk, Bruce J.
2011-01-01
Highlights: → Pb-acid battery is reexamined in electrode structure and capacitance enhancement. → Pb-acid batteries were tested through the electrochemical impedance at loads. → Electrode behaviors are evaluated by simulation using an equivalent circuit model. → A defective and a failed Pb-acid battery was used in non-destructive analysis. → Potential applications are for power reserve and sustainable electricity storage. - Abstract: Three main types of battery chemistries in consideration for vehicle applications are Pb-acid, nickel-metal hydride, and lithium-ion batteries. Lead-acid batteries are widely used in traditional automotive applications for many years. Higher voltage, high-rate discharge capability, good specific energy, lower temperature performance, lower thermal management requirement, and low-cost in both manufacturing and recycling are the advantages of the rechargeable battery. Disadvantages of the lead-acid battery are: weight concerns of lead metal (lower energy density and lower power density) and limited cycle-life (especially in deep-cycle duties). If two major disadvantages have been significantly changed to a proper state to compete with other battery chemistries, the Pb-acid battery is still a good candidate in considering of cost/performance ratio. The lead-acid battery is always a good power source for fast starting of cold vehicles, for recharging from either a stop-start braking system, or for a charge from the engine itself, which consumes battery energy or stores electricity back into chemical energy. The main reasons for reexamining this battery chemistry are cost-savings and life-cycling considerations upon advances in electrode structure design and enhancement of capacitance behavior inside the battery pack. Several Pb-acid batteries were evaluated and tested through a unique method, i.e., the electrochemical impedance method at different loads, in order to characterize and further understand the improved electrode
Equivalent circuit of frog atrial tissue as determined by voltage clamp-unclamp experiments.
Tarr, M; Trank, J
1971-11-01
The equivalent circuit that has been used in the analysis of nerve voltage-clamp data is that of the membrane capacity in parallel with the membrane resistance. Voltage-clamp experiments on frog atrial tissue indicate that this circuit will not suffice for this cardiac tissue. The change in membrane current associated with a step change in membrane potential does not show a rapid spike of capacitive current as would be expected for the simple parallel resistance-capacitance network. Rather, there is a step change in current followed by an exponential decay in current with a time constant of about 1 msec. This relatively slow capacitive charging current suggests that there is a resistance in series with the membrane capacity. A possible equivalent circuit is that of a series resistance external to the parallel resistance-capacitance network of the cell membranes. Another possible circuit assumes that the series resistance is an integral part of the cell membrane. The data presented in this paper demonstrate that the equivalent circuit of a bundle of frog atrial muscle is that of an external resistance in series with the cell membranes.
An equivalent circuit approach to the modelling of the dynamics of dye sensitized solar cells
DEFF Research Database (Denmark)
Bay, L.; West, K.
2005-01-01
A model that can be used to interpret the response of a dye-sensitized photo electrode to intensity-modulated light (intensity modulated voltage spectroscopy, IMVS and intensity modulated photo-current spectroscopy, IMPS) is presented. The model is based on an equivalent circuit approach involvin...
Equivalent circuit modelling of integrated traveling-wave optical modulator in InP foundry platform
Yao, W.; Gilardi, G.; Smit, M.K.; Wale, M.J.
2016-01-01
In this paper we present an electro-optical model for traveling-wave modulator devices utilizing measurement-based equivalent circuit model extraction in conjunction with microwave CAD simulation techniques. Model verification is performed with frequencydomain and time-domain characterization of an
Complexity classifications for different equivalence and audit problems for Boolean circuits
BÃ¶hler, Elmar; Creignou, Nadia; Galota, Matthias; Reith, Steffen; Schnoor, Henning; Vollmer, Heribert
2010-01-01
We study Boolean circuits as a representation of Boolean functions and conskier different equivalence, audit, and enumeration problems. For a number of restricted sets of gate types (bases) we obtain efficient algorithms, while for all other gate types we show these problems are at least NP-hard.
Theoretical analysis of a YBCO squirrel-cage type induction motor based on an equivalent circuit
International Nuclear Information System (INIS)
Morita, G; Nakamura, T; Muta, I
2006-01-01
A HTS induction motor, with a HTS squirrel-cage rotor, is analysed using an electrical equivalent circuit. The squirrel-cage winding in the rotor consists of rotor bars and end rings, and both are considered to be made of YBCO film conductors. A wide range of electric field versus current density in YBCO film is formulated based on the Weibull function, and analysed as a non-linear resistance in the equivalent circuit. It is shown that starting and accelerating torques of the HTS induction motor are improved drastically compared to those of a conventional induction motor. Furthermore, large synchronous torque can also be realized by trapping the magnetic flux in the rotor circuit because of the persistent current mode
Sammoura, Firas; Kim, Sang-Gook
2012-05-01
An electric circuit model for a circular bimorph piezoelectric micromachined ultrasonic transducer (PMUT) was developed for the first time. The model was made up of an electric mesh, which was coupled to a mechanical mesh via a transformer element. The bimorph PMUT consisted of two piezoelectric layers of the same material, having equal thicknesses, and sandwiched between three thin electrodes. The piezoelectric layers, having the same poling axis, were biased with electric potentials of the same magnitude but opposite polarity. The strain mismatches between the two layers created by the converse piezoelectric effect caused the membrane to vibrate and, hence, transmit a pressure wave. Upon receiving the echo of the acoustic wave, the membrane deformation led to the generation of electric charges as a result of the direct piezoelectric phenomenon. The membrane angular velocity and electric current were related to the applied electric field, the impinging acoustic pressure, and the moment at the edge of the membrane using two canonical equations. The transduction coefficients from the electrical to the mechanical domain and vice-versa were shown to be bilateral and the system was shown to be reversible. The circuit parameters of the derived model were extracted, including the transformer ratio, the clamped electric impedance, the spring-softening impedance, and the open-circuit mechanical impedance. The theoretical model was fully examined by generating the electrical input impedance and average plate displacement curves versus frequency under both air and water loading conditions. A PMUT composed of piezoelectric material with a lossy dielectric was also investigated and the maximum possible electroacoustical conversion efficiency was calculated.
Circuit modeling of the electrical impedance: part III. Disuse following bone fracture
International Nuclear Information System (INIS)
Shiffman, C A
2013-01-01
Multifrequency measurements of the electrical impedance of muscle have been extended to the study of disuse following bone fracture, and analyzed using the five-element circuit model used earlier in the study of the effects of disease. Eighteen subjects recovering from simple fractures on upper or lower limbs were examined (ten males, eight females, aged 18–66). Muscles on uninjured contralateral limbs were used as comparison standards, and results are presented in terms of the ratios p(injured)/p(uninjured), where p stands for the circuit parameter r 1 , r 2 , r 3 , 1/c 1 or 1/c 2 . These are strikingly similar to the diseased-to-healthy ratios for patients with neuromuscular disease, reported in part I of this series. In particular, r 1 is virtually unaffected and the ratios for r 2 , r 3 , 1/c 1 and 1/c 2 can be as large as in serious disease. Furthermore, the same pattern of relationships between the parameters is found, suggesting that there is a common underlying mechanism for the impedance changes. Atrophy and fibrosis are examined as candidates for that mechanism, but it is argued that their effects are too small to explain the observed changes. Fundamental considerations aside, the sensitivity, reproducibility and technical simplicity of the technique recommend its use for in-flight assessments of muscles during orbital or interplanetary missions. (paper)
A new three-dimensional equivalent circuit of diagonal type MHD generator
International Nuclear Information System (INIS)
Yoshida, Masahrau; Komaya, Kiyotoshi; Umoto, Juro
1979-01-01
For a large scale diagonal type generator with oil combustion gas plasma, a new three-dimensional equivalent circuit is proposed, in which threre are considered the leakage resistance of the duct insulator surface, the boundary layer, the ion slip, the effect of the finite electrode segmentation etc. Next, through the relation between the Hall voltage per one electrode pitch region and the load current obtained by use of the equivalent circuit, a suitable size and number of the space elements per region and determined. Further, by comparing in detail the electrical performances of two types of the diagonal generators with diagonal conducting and insulating sidewalls, three-dimensional effects of the sidewalls are discussed. (author)
Equivalent circuit and optimum design of a multilayer laminated piezoelectric transformer.
Dong, Shuxiang; Carazo, Alfredo Vazquez; Park, Seung Ho
2011-12-01
A multilayer laminated piezoelectric Pb(Zr(1-x)Ti(x))O(3) (PZT) ceramic transformer, operating in a half- wavelength longitudinal resonant mode (λ/2 mode), has been analyzed. This piezoelectric transformer is composed of one thickness-polarized section (T-section) for exciting the longitudinal mechanical vibrations, two longitudinally polarized sections (L-section) for generating high-voltage output, and two insulating layers laminated between the T-section and L-section layers to provide insulation between the input and output sections. Based on the piezoelectric constitutive and motion equations, an electro-elasto-electric (EEE) equivalent circuit has been developed, and correspondingly, an effective EEE coupling coefficient was proposed for optimum design of this multilayer transformer. Commercial finite element analysis software is used to determine the validity of the developed equivalent circuit. Finally, a prototype sample was manufactured and experimental data was collected to verify the model's validity.
Directory of Open Access Journals (Sweden)
Christos A. Christodoulou
2017-12-01
Full Text Available The appropriate circuit modeling of metal oxide gapless surge arresters is critical for insulation coordination studies. Metal oxide arresters present a dynamic behavior for fast front surges; namely, their residual voltage is dependent on the peak value, as well as the duration of the injected impulse current, and should therefore not only be represented by non-linear elements. The aim of the current work is to adjust the parameters of the most frequently used surge arresters’ circuit models by considering the magnitude of the residual voltage, as well as the dissipated energy for given pulses. In this aim, the harmony search method is implemented to adjust parameter values of the arrester equivalent circuit models. This functions by minimizing a defined objective function that compares the simulation outcomes with the manufacturer’s data and the results obtained from previous methodologies.
Directory of Open Access Journals (Sweden)
Haijun Chen
2014-01-01
Full Text Available Combining two different types of solar cells with different absorption bands into a hybrid cell is a very useful method to improve the utilization efficiency of solar energy. The experimental data of dye-sensitized solar cells (DSSCs and thermoelectric generators (TEG was simulated by equivalent circuit method, and some parameters of DSSCs were obtained. Then, the equivalent circuit model with the obtained parameters was used to optimize the structure design of photovoltaic- (PV- thermoelectric (TE hybrid devices. The output power (Pout first increases to a maximum and then decreases by increasing the TE prism size, and a smaller spacing between p-type prism and n-type prism of a TE p-n junction causes a higher output power of TEG and hybrid device. When the spacing between TE prisms is 15 μm and the optimal base side length of TE prism is 40 μm, the maximum theoretical efficiency reaches 24.6% according to the equivalent circuit analysis. This work would give some enlightenment for the development of high-performance PV-TE hybrid devices.
International Nuclear Information System (INIS)
Li Wenjun; China Academy of Engineering Physics, Mianyang; Xu Zhou; Li Ming; Yang Xingfan; Chen Yanan; Liu Jie; Jin Xiao; Lin Yuzheng
2008-01-01
In this paper, a time-domain equivalent circuit method is applied to solve dispersion of coupled-cavity travelling-wave tube (CCTWT). First, the time-domain circuit equations of CCTWT coupled-cavity chain are deduced from the equivalent circuit model. Then, the equations are solved numerically by fourth-order Runge-Kutta method and a program CTTDCP is developed using MATLAB. Last, a L-band CCTWT is calculated using CTTDCP and the cavity pass-band of this tube is computed to be 1.08-1.48 GHz, which is consistent with the experimental results and the simulation results of electromagnetic code and demonstrates the validity of the time-domain equivalent circuit method. In addition, a new design method which uses the equivalent circuit method and electromagnetic simulation together to optimize the cold cavity characteristics of CCTWT is proposed. (authors)
Equivalence between classical and quantum dynamics. Neutral kaons and electric circuits
International Nuclear Information System (INIS)
Caruso, M.; Fanchiotti, H.; Canal, C.A. Garcia
2011-01-01
An equivalence between the Schroedinger dynamics of a quantum system with a finite number of basis states and a classical dynamics is presented. The equivalence is an isomorphism that connects in univocal way both dynamical systems. We treat the particular case of neutral kaons and found a class of electric networks uniquely related to the kaon system finding the complete map between the matrix elements of the effective Hamiltonian of kaons and those elements of the classical dynamics of the networks. As a consequence, the relevant ε parameter that measures CP violation in the kaon system is completely determined in terms of network parameters. - Highlights: → We provide a formal equivalence between classical and quantum dynamics. → We make use of the decomplexification concept. → Neutral kaon systems can be represented by electric circuits. → CP symmetry violation can be taken into account by non-reciprocity. → Non-reciprocity is represented by gyrators.
A new method for electric impedance imaging using an eddy current with a tetrapolar circuit.
Ahsan-Ul-Ambia; Toda, Shogo; Takemae, Tadashi; Kosugi, Yukio; Hongo, Minoru
2009-02-01
A new contactless technique for electrical impedance imaging, using an eddy current managed along with the tetrapolar circuit method, is proposed. The eddy current produced by a magnetic field is superimposed on a constant current that is normally used in the tetrapolar circuit method, and thus is used to control the current distribution in the body. By changing the current distribution, a set of voltage differences is measured with a pair of electrodes. This set of voltage differences is used in the image reconstruction of the resistivity distribution. The least square error minimization method is used in the reconstruction algorithm. The principle of this method is explained theoretically. A backprojection algorithm was used to get 2-D images. Based on this principle, a measurement system was developed and model experiments were conducted with a saline-filled phantom. The estimated shape of each model in the reconstructed image was similar to that of the corresponding model. From the results of these experiments, it is confirmed that the proposed method is applicable to the realization of electrical conductivity imaging.
International Nuclear Information System (INIS)
Sudhir, Dass; Bandyopadhyay, M.; Chakraborty, A.; Kraus, W.; Gahlaut, A.; Bansal, G.
2014-01-01
Impedance matching circuit between radio frequency (RF) generator and the plasma load, placed between them, determines the RF power transfer from RF generator to the plasma load. The impedance of plasma load depends on the plasma parameters through skin depth and plasma conductivity or resistivity. Therefore, for long pulse operation of inductively coupled plasmas, particularly for high power (∼100 kW or more) where plasma load condition may vary due to different reasons (e.g., pressure, power, and thermal), online tuning of impedance matching circuit is necessary through feedback. In fusion grade ion source operation, such online methodology through feedback is not present but offline remote tuning by adjusting the matching circuit capacitors and tuning the driving frequency of the RF generator between the ion source operation pulses is envisaged. The present model is an approach for remote impedance tuning methodology for long pulse operation and corresponding online impedance matching algorithm based on RF coil antenna current measurement or coil antenna calorimetric measurement may be useful in this regard
A nonlinear equivalent circuit method for analysis of passive intermodulation of mesh reflectors
Directory of Open Access Journals (Sweden)
Jiang Jie
2014-08-01
Full Text Available Passive intermodulation (PIM has gradually become a serious electromagnetic interference due to the development of high-power and high-sensitivity RF/microwave communication systems, especially large deployable mesh reflector antennas. This paper proposes a field-circuit coupling method to analyze the PIM level of mesh reflectors. With the existence of many metal–metal (MM contacts in mesh reflectors, the contact nonlinearity becomes the main reason for PIM generation. To analyze these potential PIM sources, an equivalent circuit model including nonlinear components is constructed to model a single MM contact so that the transient current through the MM contact point induced by incident electromagnetic waves can be calculated. Taking the electric current as a new electromagnetic wave source, the far-field scattering can be obtained by the use of electromagnetic numerical methods or the communication link method. Finally, a comparison between simulation and experimental results is illustrated to verify the validity of the proposed method.
Energy Technology Data Exchange (ETDEWEB)
Haubrock, J.
2007-12-13
Fuel cells are a very promising technology for energy conversion. For optimization purpose, useful simulation tools are needs. Simulation tools should simulate the static and dynamic electrical behaviour and the models should parameterized by measurment results which should be done easily. In this dissertation, a useful model for simulating a pem fuel cell is developed. the model should parametrizes by V-I curve measurment and by current step respond. The model based on electrical equivalent circuits and it is shown, that it is possible to simulate the dynamic behaviour of a pem fuel cell stack. The simulation results are compared by measurment results. (orig.)
Analysis of each branch current of serial solar cells by using an equivalent circuit model
International Nuclear Information System (INIS)
Yi Shi-Guang; Zhang Wan-Hui; Ai Bin; Song Jing-Wei; Shen Hui
2014-01-01
In this paper, based on the equivalent single diode circuit model of the solar cell, an equivalent circuit diagram for two serial solar cells is drawn. Its equations of current and voltage are derived from Kirchhoff's current and voltage law. First, parameters are obtained from the I—V (current—voltage) curves for typical monocrystalline silicon solar cells (125 mm × 125 mm). Then, by regarding photo-generated current, shunt resistance, serial resistance of the first solar cell, and resistance load as the variables. The properties of shunt currents (I sh1 and I sh2 ), diode currents (I D1 and I D2 ), and load current (I L ) for the whole two serial solar cells are numerically analyzed in these four cases for the first time, and the corresponding physical explanations are made. We find that these parameters have different influences on the internal currents of solar cells. Our results will provide a reference for developing higher efficiency solar cell module and contribute to the better understanding of the reason of efficiency loss of solar cell module. (interdisciplinary physics and related areas of science and technology)
International Nuclear Information System (INIS)
Yao, J; Zhang, Z T; Xu, S J; Yu, Q X; Yu, Z; Zhao, J S
2013-01-01
This paper presents a dynamic simulating model of the dielectric barrier discharge (DBD), structured as an equivalent electric circuit of the streamer and glow discharge generated alternately in DBD. The main parameters of DBD have been established by means of analysing the structural characteristics of a single discharge cell. An electrical comprehensive Simulink /MATLAB model was developed in order to reveal the interaction of the adjacent two discharge cell. A series of simulations was carried out in order to estimate the key structural parameters that affect the alternate streamer and glow discharge mode. The comparison results of experimental and simulate indicate that there exists a close similarity of the current waveforms graphic. Therefore, we can grasp a deep understanding mechanism of the dielectric barrier discharge and optimize the plasma reactor.
Multi-temperature state-dependent equivalent circuit discharge model for lithium-sulfur batteries
DEFF Research Database (Denmark)
Propp, Karsten; Marinescu, Monica; Auger, Daniel J.
2016-01-01
Lithium-sulfur (Li-S) batteries are described extensively in the literature, but existing computational models aimed at scientific understanding are too complex for use in applications such as battery management. Computationally simple models are vital for exploitation. This paper proposes a non......-linear state-of-charge dependent Li-S equivalent circuit network (ECN) model for a Li-S cell under discharge. Li-S batteries are fundamentally different to Li-ion batteries, and require chemistry-specific models. A new Li-S model is obtained using a ‘behavioural’ interpretation of the ECN model; as Li...... pulse profile at four temperatures from 10 °C to 50 °C, giving linearized ECN parameters for a range of states-of-charge, currents and temperatures. These are used to create a nonlinear polynomial-based battery model suitable for use in a battery management system. When the model is used to predict...
Parameter Sensitivity of High–Order Equivalent Circuit Models Of Turbine Generator
Directory of Open Access Journals (Sweden)
T. Niewierowicz–Swiecicka
2010-01-01
Full Text Available This work shows the results of a parametric sensitivity analysis applied to a state–space representation of high–order two–axis equivalent circuits (ECs of a turbo generator (150 MVA, 120 MW, 13.8 kV y 50 Hz. The main purpose of this study is to evaluate each parameter impact on the transient response of the analyzed two–axis models –d–axis ECs with one to five damper branches and q–axis ECs from one to four damper branches–. The parametric sensitivity concept is formulated in a general context and the sensibility function is established from the generator response to a short circuit condition. Results ponder the importance played by each parameter in the model behavior. The algorithms were design within MATLAB® environment. The study gives way to conclusions on electromagnetic aspects of solid rotor synchronous generators that have not been previously studied. The methodology presented here can be applied to any other physical system.
Energy Technology Data Exchange (ETDEWEB)
White, B.D. [Department of Mechanical Engineering, The University of British Columbia, 2054-6250 Applied Sciences Lane, Vancouver, British Columbia (Canada); Kesler, O. [Department of Mechanical and Industrial Engineering, University of Toronto, 5 King' s College Road, Toronto, Ontario (Canada)
2008-02-15
Electronic short circuiting of the electrolyte in a solid oxide fuel cell (SOFC) arising from flaws in the plasma spray fabrication process has been found to have a significant effect on the perceived performance of the electrodes, as evaluated by electrochemical impedance spectroscopy (EIS). The presence of a short circuit has been found to lead to the underestimation of the electrode polarization resistance (R{sub p}) and hence an overestimation of electrode performance. The effect is particularly noticeable when electrolyte resistance is relatively high, for example during low to intermediate temperature operation, leading to an obvious deviation from the expected Arrhenius-type temperature dependence of R{sub p}. A method is developed for determining the real electrode performance from measurements of various cell properties, and strategies for eliminating the occurrence of short circuiting in plasma sprayed cells are identified. (author)
White, B. D.; Kesler, O.
Electronic short circuiting of the electrolyte in a solid oxide fuel cell (SOFC) arising from flaws in the plasma spray fabrication process has been found to have a significant effect on the perceived performance of the electrodes, as evaluated by electrochemical impedance spectroscopy (EIS). The presence of a short circuit has been found to lead to the underestimation of the electrode polarization resistance (R p) and hence an overestimation of electrode performance. The effect is particularly noticeable when electrolyte resistance is relatively high, for example during low to intermediate temperature operation, leading to an obvious deviation from the expected Arrhenius-type temperature dependence of R p. A method is developed for determining the real electrode performance from measurements of various cell properties, and strategies for eliminating the occurrence of short circuiting in plasma sprayed cells are identified.
International Nuclear Information System (INIS)
Cascella, Franco; Sorin, Mikhail; Formosa, Fabien; Teyssedou, Alberto
2017-01-01
Highlights: • A model based on the electrical analogy theory has been developed to predict the operation of a Stirling engine. • The models takes into account the continuity, the momentum and the energy conservation equations. • The model predicts the operating conditions of the RE100 Free piston Stirling engine. • The model is sensible to the modeling of the effects of the machine load. - Abstract: The Stirling engines are inherently efficient; their thermodynamic cycles reach the Carnot efficiency. These technologies are suitable to operate under any low temperature difference between the hot and the cold sources. For these reasons, these engines can be considered as reliable power conversion systems to promote the conversion of low-grade waste heat generated by industrial plants. The need of a model to predict the behavior of these engines is of primary importance. Nevertheless, a great difficulty is encountered in developing such a model since it is not simple to take into account coupled thermodynamic and dynamic effects. This is the main reason why several models make use of electrical analogies to describe Stirling engines (in particular, free-piston machines): by assuming the pressure equivalent to a voltage and the flow rate to an electrical current, a coupled dynamic-thermodynamic analysis of the engine can be performed. In this paper, an electrical circuit whose behavior is equivalent to that of the engine is derived from the electrical analogy theory. To this aim, we propose an electrical analogy model based on the three conservation laws (mass, momentum and energy). Since limited experimental information is available in the open literature, the results obtained with the proposed model are compared with the experimental data collected at the NASA Lewis Research center for a free-piston Stirling engine i.e., the RE-1000 engine.
International Nuclear Information System (INIS)
Murayama, Masaki; Mori, Tatsuo
2006-01-01
Equivalent circuit analysis using a one-diode model was carried out as a simpler, more convenient method to evaluate the electric mechanism and to employ effective treatment of a dye-sensitized solar cell (DSC). Cells treated using acetic acid or 4,t-butylpyridine were measured under irradiation (0.1 W/m 2 , AM 1.5) to obtain current-voltage (I-V) curves. Cell performance and equivalent circuit parameters were calculated from the I-V curves. Evaluation based on residual factors was useful for better fitting of the equivalent circuit to the I-V curve. The diode factor value was often over two for high-performance DSCs. Acetic acid treatment was effective to increase the short-circuit current by decreasing the series resistance of cells. In contrast, 4,t-butylpyridine was effective to increase open-circuit voltage by increasing the cell shunt resistance. Previous explanations considered that acetic acid worked to decrease the internal resistance of the TiO 2 layer and butylpyridine worked to lower the back-electron-transfer from the TiO 2 to the electrolyte
Real-time monitoring of a microbial electrolysis cell using an electrical equivalent circuit model.
Hussain, S A; Perrier, M; Tartakovsky, B
2018-04-01
Efforts in developing microbial electrolysis cells (MECs) resulted in several novel approaches for wastewater treatment and bioelectrosynthesis. Practical implementation of these approaches necessitates the development of an adequate system for real-time (on-line) monitoring and diagnostics of MEC performance. This study describes a simple MEC equivalent electrical circuit (EEC) model and a parameter estimation procedure, which enable such real-time monitoring. The proposed approach involves MEC voltage and current measurements during its operation with periodic power supply connection/disconnection (on/off operation) followed by parameter estimation using either numerical or analytical solution of the model. The proposed monitoring approach is demonstrated using a membraneless MEC with flow-through porous electrodes. Laboratory tests showed that changes in the influent carbon source concentration and composition significantly affect MEC total internal resistance and capacitance estimated by the model. Fast response of these EEC model parameters to changes in operating conditions enables the development of a model-based approach for real-time monitoring and fault detection.
Electro-thermal characterization of Lithium Iron Phosphate cell with equivalent circuit modeling
International Nuclear Information System (INIS)
Saw, L.H.; Ye, Y.; Tay, A.A.O.
2014-01-01
Highlights: • We modeled the electrical and thermal behavior of the Li-ion battery. • We validated the simulation results with experimental studies. • We studied the thermal response of the battery pack using UDDS and US06 test. • Active cooling system is needed to prolong life cycle of cell. - Abstract: Prediction of the battery performance is important in the development of the electric vehicles battery pack. A battery model that is capable to reproduce I–V characteristic, thermal response and predicting the state of charge of the battery will benefit the development of cell and reduce time to market for electric vehicles. In this work, an equivalent circuit model coupled with the thermal model is used to analyze the electrical and thermal behavior of Lithium Iron Phosphate pouch cell under various operating conditions. The battery model is comprised three RC blocks, one series resistor and one voltage source. The parameters of the battery model are extracted from pulse discharge curve under different temperatures. The simulations results of the battery model under constant current discharge and pulse charge and discharge show a good agreement with experimental data. The validated battery model is then extended to investigate the dynamic behavior of the electric vehicle battery pack using UDDS and US06 test cycle. The simulation results show that an active thermal management system is required to prolong the calendar life and ensure safety of the battery pack
Estimation of the Diesel Particulate Filter Soot Load Based on an Equivalent Circuit Model
Directory of Open Access Journals (Sweden)
Yanting Du
2018-02-01
Full Text Available In order to estimate the diesel particulate filter (DPF soot load and improve the accuracy of regeneration timing, a novel method based on an equivalent circuit model is proposed based on the electric-fluid analogy. This proposed method can reduce the impact of the engine transient operation on the soot load, accurately calculate the flow resistance, and improve the estimation accuracy of the soot load. Firstly, the least square method is used to identify the flow resistance based on the World Harmonized Transient Cycle (WHTC test data, and the relationship between flow resistance, exhaust temperature and soot load is established. Secondly, the online estimation of the soot load is achieved by using the dual extended Kalman filter (DEKF. The results show that this method has good convergence and robustness with the maximal absolute error of 0.2 g/L at regeneration timing, which can meet engineering requirements. Additionally, this method can estimate the soot load under engine transient operating conditions and avoids a large number of experimental tests, extensive calibration and the analysis of complex chemical reactions required in traditional methods.
On the calculation of the equivalent circuit for an electrostatic probe
International Nuclear Information System (INIS)
Alekseev, B.V.; Kotel'nikov, V.A.; Cherepanov, V.V.
1982-01-01
An electric circuit of the probe including a nonlinear element - the layer of a volumetric charge - is considered. Free-molecular and gas dynamical modes are investigated. Calculations of transition processes in the probe circuit are conducted. Characteristic times of formation of the excited zone and the transition process in the circuit are compared. The threshold value of time constant of the circuit at which the transition process in the excited zone can be neglected is determined
International Nuclear Information System (INIS)
Sun Ya-Bin; Li Xiao-Jin; Zhang Jin-Zhong; Shi Yan-Ling
2017-01-01
In this paper, we present an improved high-frequency equivalent circuit for SiGe heterojunction bipolar transistors (HBTs) with a CBE layout, where we consider the distributed effects along the base region. The actual device structure is divided into three parts: a link base region under a spacer oxide, an intrinsic transistor region under the emitter window, and an extrinsic base region. Each region is considered as a two-port network, and is composed of a distributed resistance and capacitance. We solve the admittance parameters by solving the transmission-line equation. Then, we obtain the small-signal equivalent circuit depending on the reasonable approximations. Unlike previous compact models, in our proposed model, we introduce an additional internal base node, and the intrinsic base resistance is shifted into this internal base node, which can theoretically explain the anomalous change in the intrinsic bias-dependent collector resistance in the conventional compact model. (paper)
Javier Cubas; Santiago Pindado; Carlos de Manuel
2014-01-01
Due to the high dependence of photovoltaic energy efficiency on environmental conditions (temperature, irradiation...), it is quite important to perform some analysis focusing on the characteristics of photovoltaic devices in order to optimize energy production, even for small-scale users. The use of equivalent circuits is the preferred option to analyze solar cells/panels performance. However, the aforementioned small-scale users rarely have the equipment or expertise to perform large testin...
Astorino, Maria Denise; Frezza, Fabrizio; Tedeschi, Nicola
2018-03-01
The analysis of the transmission and reflection spectra of stacked slot-based 2D periodic structures of arbitrary geometry and the ability to devise and control their electromagnetic responses have been a matter of extensive research for many decades. The purpose of this paper is to develop an equivalent Π circuit model based on the transmission-line theory and Floquet harmonic interactions, for broadband and short longitudinal period analysis. The proposed circuit model overcomes the limits of identical and symmetrical configurations imposed by the even/odd excitation approach, exploiting both the circuit topology of a single 2D periodic array of apertures and the ABCD matrix formalism. The transmission spectra obtained through the equivalent-circuit model have been validated by comparison with full-wave simulations carried out with a finite-element commercial electromagnetic solver. This allowed for a physical insight into the spectral and angular responses of multilayer devices with arbitrary aperture shapes, guaranteeing a noticeable saving of computational resources.
International Nuclear Information System (INIS)
Kern, R.; Sastrawan, R.; Ferber, J.; Stangl, R.; Luther, J.
2002-01-01
Electrical impedance spectroscopy (EIS) was applied in order to investigate electrochemical nanocrystalline TiO 2 dye solar cells (DSC). Typically, three characteristic frequency peaks were observed in the spectra. These frequency peaks could be explained by variations of cell parameters and by comparison with intensity-modulated photovoltage spectroscopy (IMVS). It was shown that the low-frequency peak (in the mHz range) corresponds to the Nernstian diffusion within the electrolyte, while the middle-frequency peak (in the 10-100 Hz range) reflects the properties of the photoinjected electrons within the TiO 2 . The high-frequency peak (in the kHz range) corresponds to the charge-transfer at the platinum counter electrode. For a detailed analysis of the spectra, a model was developed which allows the evaluation of EIS spectra, measured under bias illumination and under open-circuit conditions. The influence of cell parameters such as the TiO 2 layer thickness, cell thickness, charge-transfer resistance of the platinum counter electrode, and the lifetime of the photoinjected electrons, on the impedance spectra was studied both experimentally and theoretically. Finally, it is shown that EIS is a measurement method suited well for the investigation of the long-term stability of DSC, as changes of the inner cell parameters can be revealed
Modeling degradation in SOEC impedance spectra
DEFF Research Database (Denmark)
Jensen, Søren Højgaard; Hauch, Anne; Knibbe, Ruth
2013-01-01
Solid oxide cell (SOC) performance is limited by various processes. One way to investigate these processes is by electrochemical impedance spectroscopy. In order to quantify and characterize the processes, an equivalent circuit can be used to model the SOC impedance spectra (IS). Unfortunately......, the optimal equivalent circuit is often unknown and to complicate matters further, several processes contribute to the SOC impedance - making detailed process characterization difficult. In this work we analyze and model a series of IS measured during steam electrolysis operation of an SOC. During testing......, degradation is only observed in the Ni/YSZ electrode and not in the electrolyte or the LSM/YSZ electrode. A batch fit of the differences between the IS shows that a modified Gerischer element provides a better fit to the Ni/YSZ electrode impedance than the frequently used RQ element - albeit neither...
In situ electrochemical impedance spectroscopy of Zr-1%Nb under VVER primary circuit conditions
International Nuclear Information System (INIS)
Nagy, Gabor; Kerner, Zsolt; Pajkossy, Tamas
2002-01-01
Oxide layers were grown on tubular samples of Zr-1%Nb under conditions simulating those in VVER-type pressurised water reactors, viz. in near-neutral borate solutions in an autoclave at 290 deg. C. These samples were investigated using electrochemical impedance spectroscopy which was found to be suitable to follow in situ the corrosion process. A -CPE ox parallel R ox - element was used to characterise the oxide layer on Zr-1%Nb. Both the CPE ox coefficient, σ ox , and the parallel resistance, R ox , were found to be thickness dependent. The layer thickness, however, can only be calculated after a calibration procedure. The temperature dependence of the CPE ox element was also found to be anomalous while the temperature dependence of R ox indicates that the oxide layer has semiconductor properties. The relaxation time - defined as (R ox σ ox ) 1/α - was found to be quasi-independent of oxidation time and temperature; thus it is characteristic to the oxide layer on Zr-1%Nb
Arjhangmehr, Afshin; Feghhi, Seyed Amir Hossein
2014-10-01
Solar modules and arrays are the conventional energy resources of space satellites. Outside the earth's atmosphere, solar panels experience abnormal radiation environments and because of incident particles, photovoltaic (PV) parameters degrade. This article tries to analyze the electrical performance of electron and photon-irradiated mono-crystalline silicon (mono-Si) solar cells. PV cells are irradiated by mono-energetic electrons and poly-energetic photons and immediately characterized after the irradiation. The mean degradation of the maximum power (Pmax) of silicon solar cells is presented and correlated using the displacement damage dose (Dd) methodology. This method simplifies evaluation of cell performance in space radiation environments and produces a single characteristic curve for Pmax degradation. Furthermore, complete analysis of the results revealed that the open-circuit voltage (Voc) and the filling factor of mono-Si cells did not significantly change during the irradiation and were independent of the radiation type and fluence. Moreover, a new technique is developed that adapts the irradiation-induced effects in a single-cell equivalent electrical circuit and adjusts its elements. The "modified circuit" is capable of modeling the "radiation damage" in the electrical behavior of mono-Si solar cells and simplifies the designing of the compensation circuits.
Detailed characterization of anode-supported SOFCs by impedance spectroscopy
DEFF Research Database (Denmark)
Barfod, R.; Mogensen, Mogens Bjerg; Klemensø, Trine
2007-01-01
Anode-supported thin electrolyte cells are studied by electrochemical impedance spectroscopy (EIS). The aim is to describe how the losses of this type of cells are distributed at low current density (around open-circuit voltage) as a function of temperature. An equivalent circuit consisting...
Directory of Open Access Journals (Sweden)
Gan Zhang
2017-05-01
Full Text Available Most of the published papers regarding the design of flux-switching permanent magnet machines are focused on the analysis and optimization of electromagnetic or mechanical behaviors, however, the evaluate of the parameter sensitivities have not been covered, which contrarily, is the main contribution of this paper. Based on the finite element analysis (FEA and simplified equivalent magnetic circuit, the method proposed in this paper enables the influences of parameters on the electromagnetic performances, i.e. the parameter sensitivities, to be given by equations. The FEA results are also validated by experimental measurements.
Directory of Open Access Journals (Sweden)
Dinh An Nguyen
2012-07-01
Full Text Available Many of the Proton Exchange Membrane Fuel Cell (PEMFC models proposed in the literature consist of mathematical equations. However, they are not adequately practical for simulating power systems. The proposed model takes into account phenomena such as activation polarization, ohmic polarization, double layer capacitance and mass transport effects present in a PEM fuel cell. Using electrical analogies and a mathematical modeling of PEMFC, the circuit model is established. To evaluate the effectiveness of the circuit model, its static and dynamic performances under load step changes are simulated and compared to the numerical results obtained by solving the mathematical model. Finally, the applicability of our model is demonstrated by simulating a practical system.
A new equivalent circuit model for on-chip spiral transformers in CMOS RFICs
International Nuclear Information System (INIS)
Wei Jiaju; Wang Zhigong; Li Zhiqun; Tang Lu
2012-01-01
A new compact model has been introduced to model on-chip spiral transformers. Unlike conventional models, which are often a compound of two spiral inductor models (i.e., the combination of two coupled Π or 2-Π sub-circuits), our new model only uses 12 elements to model the whole structure in the form of T topology. The new model is based on the physical meaning, and the process of model derivation is also presented. In addition, a simple parameter extraction procedure is proposed to get the elements' values without any fitting and optimization. In this procedure, a new method has been developed for the parameter extraction of the ladder circuit, which is commonly used to represent the skin effect. In order to verify the model's validity and accuracy, we have compared the simulated and measured self-inductance, quality factor, coupling coefficient and insertion loss, and an excellent agreement has been found over a broad frequency range up to the resonant frequency. (semiconductor integrated circuits)
Broadband electrical impedance matching for piezoelectric ultrasound transducers.
Huang, Haiying; Paramo, Daniel
2011-12-01
This paper presents a systematic method for designing broadband electrical impedance matching networks for piezoelectric ultrasound transducers. The design process involves three steps: 1) determine the equivalent circuit of the unmatched piezoelectric transducer based on its measured admittance; 2) design a set of impedance matching networks using a computerized Smith chart; and 3) establish the simulation model of the matched transducer to evaluate the gain and bandwidth of the impedance matching networks. The effectiveness of the presented approach is demonstrated through the design, implementation, and characterization of impedance matching networks for a broadband acoustic emission sensor. The impedance matching network improved the power of the acquired signal by 9 times.
Directory of Open Access Journals (Sweden)
Javier Cubas
2014-06-01
Full Text Available Due to the high dependence of photovoltaic energy efficiency on environmental conditions (temperature, irradiation..., it is quite important to perform some analysis focusing on the characteristics of photovoltaic devices in order to optimize energy production, even for small-scale users. The use of equivalent circuits is the preferred option to analyze solar cells/panels performance. However, the aforementioned small-scale users rarely have the equipment or expertise to perform large testing/calculation campaigns, the only information available for them being the manufacturer datasheet. The solution to this problem is the development of new and simple methods to define equivalent circuits able to reproduce the behavior of the panel for any working condition, from a very small amount of information. In the present work a direct and completely explicit method to extract solar cell parameters from the manufacturer datasheet is presented and tested. This method is based on analytical formulation which includes the use of the Lambert W-function to turn the series resistor equation explicit. The presented method is used to analyze commercial solar panel performance (i.e., the current-voltage–I-V–curve at different levels of irradiation and temperature. The analysis performed is based only on the information included in the manufacturer’s datasheet.
Ramotar, Lokendra; Rohrauer, Greg L.; Filion, Ryan; MacDonald, Kathryn
2017-03-01
The development of a dynamic thermal battery model for hybrid and electric vehicles is realized. A thermal equivalent circuit model is created which aims to capture and understand the heat propagation from the cells through the entire pack and to the environment using a production vehicle battery pack for model validation. The inclusion of production hardware and the liquid battery thermal management system components into the model considers physical and geometric properties to calculate thermal resistances of components (conduction, convection and radiation) along with their associated heat capacity. Various heat sources/sinks comprise the remaining model elements. Analog equivalent circuit simulations using PSpice are compared to experimental results to validate internal temperature nodes and heat rates measured through various elements, which are then employed to refine the model further. Agreement with experimental results indicates the proposed method allows for a comprehensive real-time battery pack analysis at little computational expense when compared to other types of computer based simulations. Elevated road and ambient conditions in Mesa, Arizona are simulated on a parked vehicle with varying quiescent cooling rates to examine the effect on the diurnal battery temperature for longer term static exposure. A typical daily driving schedule is also simulated and examined.
Herden, Susanne; Hirschfeld, Julian A.; Lohri, Cyrill; Perchthaler, Markus; Haase, Stefan
2017-10-01
To improve the performance of proton exchange membrane fuel cells, membrane electrode assemblies (MEAs) with segmented cathode electrodes have been manufactured. Electrodes with a higher and lower ionomer equivalent weight (EW) were used and analyzed using current density and temperature distribution, polarization curve, temperature sweep and electrochemical impedance spectroscopy measurements. These were performed using automotive metallic bipolar plates and operating conditions. Measurement data were used to manufacture an optimized segmented cathode electrode. We were able to show that our results are transferable from a small scale hardware to automotive application and that an ionomer EW segmentation of the cathode leads to performance improvement in a broad spectrum of operating conditions. Furthermore, we confirmed our results by using in-situ electrochemical impedance spectroscopy.
Directory of Open Access Journals (Sweden)
Lubomir Ivanek
2017-01-01
Full Text Available This paper deals with the sensitivity of the input impedance of an open track circuit in the event that the parameters of the track are changed. Weather conditions and the state of pollution are the most common reasons for parameter changes. The results were obtained from the measured values of the parameters R (resistance, G (conductance, L (inductance, and C (capacitance of a rail superstructure depending on the frequency. Measurements were performed on a railway siding in Orlova. The results are used to design a predictor of occupancy of a track section. In particular, we were interested in the frequencies of 75 and 275 Hz for this purpose. Many parameter values of track substructures have already been solved in different works in literature. At first, we had planned to use the parameter values from these sources when we designed the predictor. Deviations between them, however, are large and often differ by three orders of magnitude (see Tab.8. From this perspective, this article presents data that have been updated using modern measurement devices and computer technology. And above all, it shows a transmission (cascade matrix used to determine the parameters.
An equivalent circuit model of supercapacitors for applications in wireless sensor networks
Yang, Hengzhao; Zhang, Ying
2011-04-01
Energy harvesting technologies have been extensively researched to develop long-lived wireless sensor networks. To better utilize the harvested energy, various energy storage systems are proposed. A simple circuit model is developed to describe supercapacitor behavior, which uses two resistor-capacitor branches with different time constants to characterize the charging and redistribution processes, and a variable leakage resistance (VLR) to characterize the self-discharge process. The voltage and temperature dependence of the VLR values is also discussed. Results show that the VLR model is more accurate than the energy recursive equation (ERE) models for short term wireless sensor network applications.
Nirmal, D.; Arivazhagan, L.; Fletcher, A. S. Augustine; Ajayan, J.; Prajoon, P.
2018-01-01
In this paper, the drain current collapse in AlGaN/GaN High Electron Mobility Transistor (HEMT) with field plate engineering is investigated. A small signal equivalent circuit of AlGaN/GaN HEMT is developed and a new drain current model is derived. This model is useful to correlate the impact of intrinsic capacitance and conductance on drain current collapse. The proposed device suppressed the current collapse phenomena by 10% compared with the conventional AlGaN/GaN HEMT. Moreover, the DC characteristics of the simulated device shows a drain current of 900 mA/mm, breakdown voltage of 291 V and transconductance of 175 mS/mm. Besides, the intrinsic capacitance and conductance parameters are extracted and its impact on drain current is analysed. Finally, the simulation results obtained were in compliance with the derived mathematical model of AlGaN/GaN HEMT.
Directory of Open Access Journals (Sweden)
Jinxin Fan
2011-03-01
Full Text Available To improve the use of lithium-ion batteries in electric vehicle (EV applications, evaluations and comparisons of different equivalent circuit models are presented in this paper. Based on an analysis of the traditional lithium-ion battery equivalent circuit models such as the Rint, RC, Thevenin and PNGV models, an improved Thevenin model, named dual polarization (DP model, is put forward by adding an extra RC to simulate the electrochemical polarization and concentration polarization separately. The model parameters are identified with a genetic algorithm, which is used to find the optimal time constant of the model, and the experimental data from a Hybrid Pulse Power Characterization (HPPC test on a LiMn2O4 battery module. Evaluations on the five models are carried out from the point of view of the dynamic performance and the state of charge (SoC estimation. The dynamic performances of the five models are obtained by conducting the Dynamic Stress Test (DST and the accuracy of SoC estimation with the Robust Extended Kalman Filter (REKF approach is determined by performing a Federal Urban Driving Schedules (FUDS experiment. By comparison, the DP model has the best dynamic performance and provides the most accurate SoC estimation. Finally, sensitivity of the different SoC initial values is investigated based on the accuracy of SoC estimation with the REKF approach based on the DP model. It is clear that the errors resulting from the SoC initial value are significantly reduced and the true SoC is convergent within an acceptable error.
Directory of Open Access Journals (Sweden)
Dafen Chen
2016-10-01
Full Text Available A battery model that has the capability of analyzing the internal non-uniformity of local state variables, including the state of charge (SOC, temperature and current density, is proposed in this paper. The model is built using a set of distributed parameter equivalent circuits. In order to validate the accuracy of the model, a customized battery with embedded T-type thermocouple sensors inside the battery is tested. The simulated temperature conforms well with the measured temperature at each test point, and the maximum difference is less than 1 °C. Then, the model is applied to analyze the evolution processes of local state variables’ distribution inside the battery during the discharge process. The simulation results demonstrate drastic distribution changes of the local state variables inside the battery during the discharge process. The internal non-uniformity is originally caused by the resistance of positive and negative foils, while also influenced by the change rate of open circuit voltage and the total resistance of the battery. Hence, the factors that affect the distribution of the local state variables are addressed.
Zhang, Xi; Lu, Jinling; Yuan, Shifei; Yang, Jun; Zhou, Xuan
2017-03-01
This paper proposes a novel parameter identification method for the lithium-ion (Li-ion) battery equivalent circuit model (ECM) considering the electrochemical properties. An improved pseudo two-dimension (P2D) model is established on basis of partial differential equations (PDEs), since the electrolyte potential is simplified from the nonlinear to linear expression while terminal voltage can be divided into the electrolyte potential, open circuit voltage (OCV), overpotential of electrodes, internal resistance drop, and so on. The model order reduction process is implemented by the simplification of the PDEs using the Laplace transform, inverse Laplace transform, Pade approximation, etc. A unified second order transfer function between cell voltage and current is obtained for the comparability with that of ECM. The final objective is to obtain the relationship between the ECM resistances/capacitances and electrochemical parameters such that in various conditions, ECM precision could be improved regarding integration of battery interior properties for further applications, e.g., SOC estimation. Finally simulation and experimental results prove the correctness and validity of the proposed methodology.
A type of 2D magnetic equivalent circuit framework of permanent magnet for magnetic system in AEMR
Directory of Open Access Journals (Sweden)
Huimin Liang
2015-02-01
Full Text Available Modeling of permanent magnet (PM is very important in the process of electromagnetic system calculation of aerospace electromagnetic relay (AEMR. In traditional analytical calculation, PM is often equivalent to a lumped parameter model of one magnetic resistance and one magnetic potential, but great error is often caused for the inner differences of PM; based on the conception of flux tube, a type of 2D magnetic equivalent circuit framework of permanent magnet model (2D MECF is established; the element is defined, the relationship between elements is deduced, and solution procedure as well as verification condition of this model is given; by a case study of the electromagnetic system of a certain type of AEMR, the electromagnetic system calculation model is established based on 2D MECF and the attractive force at different rotation angles is calculated; the proposed method is compared with the traditional lumped parameter model and finite element method (FEM; for some types of electromagnetic systems with symmetrical structure, 2D MECF proves to be of acceptable accuracy and high calculation speed which fit the requirement of robust design for AEMR.
DEFF Research Database (Denmark)
Midili, Virginio; Squartecchia, Michele; Johansen, Tom Keinicke
2016-01-01
equivalent circuit description. In the first approach, the EM simulations of contact pads and ballasting network are combined with the small-signal model of the intrinsic device. In the second approach, the ballasting network is modeled with lumped components derived from physical analysis of the layout...
International Nuclear Information System (INIS)
Zhou, Hao-Miao; Li, Chao; Xuan, Li-Ming; Zhao, Ji-Xiang; Wei, Jing
2011-01-01
This paper analyzes the magnetoelectric (ME) response around the resonance frequency in the magnetostrictive/piezoelectric/magnetostrictive (MPM) magnetoelectric laminate composites. Following the equivalent circuit method and considering the mechanical loss, we select the nonlinear magnetostrictive constitutive model to present a novel explicit nonlinear expression for the resonant magnetoelectric (ME) coefficient of the magnetoelectric laminate composites. Compared with the experimental results, the predicted resonant ME coefficient of the explicit expression shows a good agreement both qualitatively and quantitatively. Also, when the electromechanical coupling factor of the piezoelectric material, k 31 p , is small, this explicit expression can be reduced to the existing model. On this basis, this paper considers and predicts the magnetoelectric conversion characteristics of the magnetoelectric laminate composites, calculates and analyzes the influences of the thickness ratio of magnetostrictive layer and piezoelectric material, bias magnetic field, and saturation magnetostrictive coefficient on the resonant ME coefficient. This research can provide a theoretical basis for the preparation of magnetoelectric devices with good magnetoelectric conversion characteristics, such as magnetoelectric sensors, energy harvesting transducers, microwave devices etc
Martin, S J; Bandey, H L; Cernosek, R W; Hillman, A R; Brown, M J
2000-01-01
We derive a lumped-element, equivalent-circuit model for the thickness-shear mode (TSM) resonator with a viscoelastic film. This modified Butterworth-Van Dyke model includes in the motional branch a series LCR resonator, representing the quartz resonance, and a parallel LCR resonator, representing the film resonance. This model is valid in the vicinity of film resonance, which occurs when the acoustic phase shift across the film is an odd multiple of pi/2 rad. For low-loss films, this model accurately predicts the frequency changes and damping that arise at resonance and is a reasonable approximation away from resonance. Elements of the parallel LCR resonator are explicitly related to film properties and can be interpreted in terms of elastic energy storage and viscous power dissipation. The model leads to a simple graphical interpretation of the coupling between the quartz and film resonances and facilitates understanding of the resulting responses. These responses are compared with predictions from the transmission-line and Sauerbrey models.
Pipa, A. V.; Koskulics, J.; Brandenburg, R.; Hoder, T.
2012-11-01
The concept of the simplest equivalent circuit for a dielectric barrier discharge (DBD) is critically reviewed. It is shown that the approach is consistent with experimental data measured either in large-scale sinusoidal-voltage driven or miniature pulse-voltage driven DBDs. An expression for the charge transferred through the gas gap q(t) is obtained with an accurate account for the displacement current and the values of DBD reactor capacitance. This enables (i) the significant reduction of experimental error in the determination of q(t) in pulsed DBDs, (ii) the verification of the classical electrical theory of ozonizers about maximal transferred charge qmax, and (iii) the development of a graphical method for the determination of qmax from charge-voltage characteristics (Q-V plots, often referred as Lissajous figures) measured under pulsed excitation. The method of graphical presentation of qmax is demonstrated with an example of a Q-V plot measured under pulsed excitation. The relations between the discharge current jR(t), the transferred charge q(t), and the measurable parameters are presented in new forms, which enable the qualitative interpretation of the measured current and voltage waveforms without the knowledge about the value of the dielectric barrier capacitance Cd. Whereas for quantitative evaluation of electrical measurements, the accurate estimation of the Cd is important.
Yousefvand, H. R.
2017-12-01
We report a study of the effects of hot-electron and hot-phonon dynamics on the output characteristics of quantum cascade lasers (QCLs) using an equivalent circuit-level model. The model is developed from the energy balance equation to adopt the electron temperature in the active region levels, the heat transfer equation to include the lattice temperature, the nonequilibrium phonon rate to account for the hot phonon dynamics and simplified two-level rate equations to incorporate the carrier and photon dynamics in the active region. This technique simplifies the description of the electron-phonon interaction in QCLs far from the equilibrium condition. Using the presented model, the steady and transient responses of the QCLs for a wide range of sink temperatures (80 to 320 K) are investigated and analysed. The model enables us to explain the operating characteristics found in QCLs. This predictive model is expected to be applicable to all QCL material systems operating in pulsed and cw regimes.
International Nuclear Information System (INIS)
Pipa, A. V.; Brandenburg, R.; Hoder, T.; Koskulics, J.
2012-01-01
The concept of the simplest equivalent circuit for a dielectric barrier discharge (DBD) is critically reviewed. It is shown that the approach is consistent with experimental data measured either in large-scale sinusoidal-voltage driven or miniature pulse-voltage driven DBDs. An expression for the charge transferred through the gas gap q(t) is obtained with an accurate account for the displacement current and the values of DBD reactor capacitance. This enables (i) the significant reduction of experimental error in the determination of q(t) in pulsed DBDs, (ii) the verification of the classical electrical theory of ozonizers about maximal transferred charge q max , and (iii) the development of a graphical method for the determination of q max from charge-voltage characteristics (Q-V plots, often referred as Lissajous figures) measured under pulsed excitation. The method of graphical presentation of q max is demonstrated with an example of a Q-V plot measured under pulsed excitation. The relations between the discharge current j R (t), the transferred charge q(t), and the measurable parameters are presented in new forms, which enable the qualitative interpretation of the measured current and voltage waveforms without the knowledge about the value of the dielectric barrier capacitance C d . Whereas for quantitative evaluation of electrical measurements, the accurate estimation of the C d is important.
DEFF Research Database (Denmark)
Bak, Claus Leth; Sigurbjörnsson, Ragnar; Bukh, Bjarne
2016-01-01
are interconnected in a simple way but via transformers and infeed from remaining parts of the network. Distance relay measured fault loop impedance shows wide ranges of variations for both phase-phase loops as well as phase-earth loops. No simple relations exist. Simulation models can be used to study fault loop...... impedance for combined faults and thereby shed light on relay trips. This study uses actual fault records, analytical method and PSCAD simulation studies to analyse combined faults in an existing 400 and 150 kV transmission line owned by Danish TSO Energinet.dk. The results clearly show that an accurate...
Yan Hong; Yong Wang; Wang Ling Goh; Yuan Gao; Lei Yao
2015-08-01
This paper presents a mathematic method and a cost-efficient circuit to measure the value of each component of the bio-impedance model at electrode-electrolyte interface. The proposed current excited triple-time-voltage oversampling (TTVO) method deduces the component values by solving triple simultaneous electric equation (TSEE) at different time nodes during a current excitation, which are the voltage functions of time. The proposed triple simultaneous electric equations (TSEEs) allows random selections of the time nodes, hence numerous solutions can be obtained during a single current excitation. Following that, the oversampling approach is engaged by averaging all solutions of multiple TSEEs acquired after a single current excitation, which increases the practical measurement accuracy through the improvement of the signal-to-noise ratio (SNR). In addition, a print circuit board (PCB) that consists a switched current exciter and an analog-to-digital converter (ADC) is designed for signal acquisition. This presents a great cost reduction when compared against other instrument-based measurement data reported [1]. Through testing, the measured values of this work is proven to be in superb agreements on the true component values of the electrode-electrolyte interface model. This work is most suited and also useful for biological and biomedical applications, to perform tasks such as stimulations, recordings, impedance characterizations, etc.
Kobayashi, Kiyoshi; Suzuki, Tohru S.
2018-03-01
A new algorithm for the automatic estimation of an equivalent circuit and the subsequent parameter optimization is developed by combining the data-mining concept and complex least-squares method. In this algorithm, the program generates an initial equivalent-circuit model based on the sampling data and then attempts to optimize the parameters. The basic hypothesis is that the measured impedance spectrum can be reproduced by the sum of the partial-impedance spectra presented by the resistor, inductor, resistor connected in parallel to a capacitor, and resistor connected in parallel to an inductor. The adequacy of the model is determined by using a simple artificial-intelligence function, which is applied to the output function of the Levenberg-Marquardt module. From the iteration of model modifications, the program finds an adequate equivalent-circuit model without any user input to the equivalent-circuit model.
DEFF Research Database (Denmark)
Andreasen, Søren Juhl; Vang, Jakob Rabjerg; Kær, Søren Knudsen
2011-01-01
at different temperatures, currents, and different content of CO, CO2 and H2 in the anode gas. The impedance spectrum at each operating point is fitted to an equivalent circuit and an analysis to identify the different mechanisms governing the impedance is performed. The trends observed, when varying...
Directory of Open Access Journals (Sweden)
Alexandros Nikolian
2016-05-01
Full Text Available In this paper, advanced equivalent circuit models (ECMs were developed to model large format and high energy nickel manganese cobalt (NMC lithium-ion 20 Ah battery cells. Different temperatures conditions, cell characterization test (Normal and Advanced Tests, ECM topologies (1st and 2nd Order Thévenin model, state of charge (SoC estimation techniques (Coulomb counting and extended Kalman filtering and validation profiles (dynamic discharge pulse test (DDPT and world harmonized light vehicle profiles have been incorporated in the analysis. A concise state-of-the-art of different lithium-ion battery models existing in the academia and industry is presented providing information about model classification and information about electrical models. Moreover, an overview of the different steps and information needed to be able to create an ECM model is provided. A comparison between begin of life (BoL and aged (95%, 90% state of health ECM parameters (internal resistance (Ro, polarization resistance (Rp, activation resistance (Rp2 and time constants (τ is presented. By comparing the BoL to the aged parameters an overview of the behavior of the parameters is introduced and provides the appropriate platform for future research in electrical modeling of battery cells covering the ageing aspect. Based on the BoL parameters 1st and 2nd order models were developed for a range of temperatures (15 °C, 25 °C, 35 °C, 45 °C. The highest impact to the accuracy of the model (validation results is the temperature condition that the model was developed. The 1st and 2nd order Thévenin models and the change from normal to advanced characterization datasets, while they affect the accuracy of the model they mostly help in dealing with high and low SoC linearity problems. The 2nd order Thévenin model with advanced characterization parameters and extended Kalman filtering SoC estimation technique is the most efficient and dynamically correct ECM model developed.
Microfluidic device for cell capture and impedance measurement.
Jang, Ling-Sheng; Wang, Min-How
2007-10-01
This work presents a microfluidic device to capture physically single cells within microstructures inside a channel and to measure the impedance of a single HeLa cell (human cervical epithelioid carcinoma) using impedance spectroscopy. The device includes a glass substrate with electrodes and a PDMS channel with micro pillars. The commercial software CFD-ACE+ is used to study the flow of the microstructures in the channel. According to simulation results, the probability of cell capture by three micro pillars is about 10%. An equivalent circuit model of the device is established and fits closely to the experimental results. The circuit can be modeled electrically as cell impedance in parallel with dielectric capacitance and in series with a pair of electrode resistors. The system is operated at low frequency between 1 and 100 kHz. In this study, experiments show that the HeLa cell is successfully captured by the micro pillars and its impedance is measured by impedance spectroscopy. The magnitude of the HeLa cell impedance declines at all operation voltages with frequency because the HeLa cell is capacitive. Additionally, increasing the operation voltage reduces the magnitude of the HeLa cell because a strong electric field may promote the exchange of ions between the cytoplasm and the isotonic solution. Below an operating voltage of 0.9 V, the system impedance response is characteristic of a parallel circuit at under 30 kHz and of a series circuit at between 30 and 100 kHz. The phase of the HeLa cell impedance is characteristic of a series circuit when the operation voltage exceeds 0.8 V because the cell impedance becomes significant.
International Nuclear Information System (INIS)
Schaefer, G.; Schoenbach, K.H.; Kristiansen, M.; Strickland, B.E.; Korzekwa, R.A.; Hutcheson, G.Z.
1986-01-01
The use of attaching gases in an externally sustained diffuse discharge opening switch with a low attachment rate at low values of E/N and a high attachment rate at high values of E/N allows the discharge to operate with low losses in the closed switch phase and to achieve fast opening after the sustainment source is turned off. Such an attacher generates a J-E/N characteristic with a negative differential conductivity in an intermediate E/N range. Such a characteristic obstructs the closing process of the discharge if it is operated in a high impedance system. Experiments demonstrating these effects are presented for electron beam sustained discharges in mixtures of argon and C 2 F 6
International Nuclear Information System (INIS)
Chu, J; Chang, X L; Zhao, M; Man, M H; Wei, M; Yuan, L
2013-01-01
With the continuous improvement of circuit integration and working clock frequency in the electronic system, it is increasingly easy for the system to be affected by electromagnetic waves, and electromagnetic susceptibility and vulnerability become more severe. However, living beings in nature have shown extraordinary compatibility, immunity and adaptability to the electromagnetism at the same time. In addition, the ion channel on the neuron cytomembrane is a typical representation of b ioelectrical immunity . So the Hodgkin-Huxley circuit model with one capacitor in parallel with some power supplies and resistors was adopted to simulate the ion channel on the neuron cytomembrane. Through analysis, the circuit model can be used to simulate some electrical characteristics of biological neuron cells, and then acquire a certain level of anti-electromagnetic interference ability. This method will be useful for improving the reliability, compatibility and anti-interference capability of the electronic system in the complicated electromagnetic environment.
Directory of Open Access Journals (Sweden)
Jung-Chuan Chou
2016-01-01
Full Text Available The internal impedances of different dye-sensitized solar cell (DSSC models were analyzed by electrochemical impedance spectrometer (EIS with an equivalent circuit model. The Nyquist plot was built to simulate the redox reaction of internal device at the heterojunction. It was useful to analyze the component structure and promote photovoltaic conversion efficiency of DSSC. The impedance of DSSC was investigated and the externally connected module assembly was constructed utilizing single cells on the scaled-up module. According to the experiment results, the impedance was increased with increasing cells connected in series. On the contrary, the impedance was decreased with increasing cells connected in parallel.
Directory of Open Access Journals (Sweden)
U. Marschner
2014-09-01
Full Text Available Two-layer flexure beams often serve as basic transducers in actuators and sensors. In this paper a generalized description of their stimuli-influenced mechanical behavior is derived. For small deflection angles this description includes a multi-port circuit or network representation with lumped elements for a beam part of finite length. A number of coupled finite beam parts model the dynamic behavior including the first natural frequencies of the beam. For piezoelectric and piezomagnetic interactions, reversible transducer models are developed. The piezomagnetic two-layer beam model is extended to include solenoid and planar coils. Linear network theory is applied in order to determine network parameters and to simplify the circuit representation. The resulting circuit model is the basis for a fast simulation of the dynamic system behavior with advanced circuit simulators and, thus, the optimization of the system. It is also a useful tool for understanding and explaining this multi-domain system through basic principles of general system theory.
International Nuclear Information System (INIS)
Koo, Kil-Mo; Song, Yong-Mann; Ahan, Kwang-Il; Ha, Jea-Joo
2007-01-01
An electrical signal should be checked to see whether it lies within its expected electrical range when there is a doubtful condition. The normal signal level for pressure, flow, level and resistance temperature detector sensors is 4 - 20mA for most instruments as an industrial process control standard. In the case of an abnormal signal level from an instrument under a severe accident condition, it is necessary to obtain a more accurate signal validation to operate a system in a control room in NPPs. Diagnostics and analysis for some abnormal signals have been performed through an important equivalent circuits modeling for passive elements under severe accident conditions. Unlike the design basis accidents, there are some inherent uncertainties for the instrumentation capabilities under severe accident conditions. In this paper, to implement a diagnostic analysis for an equivalent circuits modeling, a kind of linked LabVIEW program for each PSpice and MULTISim code is introduced as a one body order system, which can obtain some abnormal signal patterns by a special function such as an advanced simulation tool for each PSpice and Multi-SIM code as a means of a function for a PC based ASSA (abnormal signal simulation analyzer) module
Energy Technology Data Exchange (ETDEWEB)
Koo, Kil-Mo; Song, Yong-Mann; Ahan, Kwang-Il; Ha, Jea-Joo [Korea Atomic Energy Research Institute, Daejeon (Korea, Republic of)
2007-07-01
An electrical signal should be checked to see whether it lies within its expected electrical range when there is a doubtful condition. The normal signal level for pressure, flow, level and resistance temperature detector sensors is 4 - 20mA for most instruments as an industrial process control standard. In the case of an abnormal signal level from an instrument under a severe accident condition, it is necessary to obtain a more accurate signal validation to operate a system in a control room in NPPs. Diagnostics and analysis for some abnormal signals have been performed through an important equivalent circuits modeling for passive elements under severe accident conditions. Unlike the design basis accidents, there are some inherent uncertainties for the instrumentation capabilities under severe accident conditions. In this paper, to implement a diagnostic analysis for an equivalent circuits modeling, a kind of linked LabVIEW program for each PSpice and MULTISim code is introduced as a one body order system, which can obtain some abnormal signal patterns by a special function such as an advanced simulation tool for each PSpice and Multi-SIM code as a means of a function for a PC based ASSA (abnormal signal simulation analyzer) module.
Foster, J. M.
2013-01-01
In this study, a drift-diffusion model is used to derive the current-voltage curves of an organic bilayer solar cell consisting of slabs of electron acceptor and electron donor materials sandwiched together between current collectors. A simplified version of the standard drift-diffusion equations is employed in which minority carrier densities are neglected. This is justified by the large disparities in electron affinity and ionisation potential between the two materials. The resulting equations are solved (via both asymptotic and numerical techniques) in conjunction with (i) Ohmic boundary conditions on the contacts and (ii) an internal boundary condition, imposed on the interface between the two materials, that accounts for charge pair generation (resulting from the dissociation of excitons) and charge pair recombination. Current-voltage curves are calculated from the solution to this model as a function of the strength of the solar charge generation. In the physically relevant power generating regime, it is shown that these current-voltage curves are well-approximated by a Shockley equivalent circuit model. Furthermore, since our drift-diffusion model is predictive, it can be used to directly calculate equivalent circuit parameters from the material parameters of the device. © 2013 AIP Publishing LLC.
DEFF Research Database (Denmark)
2009-01-01
A load testing circuit a circuit tests the load impedance of a load connected to an amplifier. The load impedance includes a first terminal and a second terminal, the load testing circuit comprising a signal generator providing a test signal of a defined bandwidth to the first terminal of the load...
Development of AC impedance methods for evaluating corroding metal surfaces and coatings
Knockemus, Ward
1986-01-01
In an effort to investigate metal surface corrosion and the breakdown of metal protective coatings the AC Impedance Method was applied to zinc chromate primer coated 2219-T87 aluminum. The model 368-1 AC Impedance Measurement System recently acquired by the MSFC Corrosion Research Branch was used to monitor changing properties of coated aluminum disks immersed in 3.5% NaCl buffered at ph 5.5 over three to four weeks. The DC polarization resistance runs were performed on the same samples. The corrosion system can be represented by an electronic analog called an equivalent circuit that consists of transistors and capacitors in specific arrangements. This equivalent circuit parallels the impedance behavior of the corrosion system during a frequency scan. Values for resistances and capacities 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 coating. A suitable equivalent circuit was determined that predicts the correct Bode phase and magnitude for the experimental sample. The DC corrosion current density data are related to equivalent circuit element parameters.
Impedance analysis of subwoofer systems
Berkhoff, Arthur P.
The electrical impedance of four low-frequency loudspeaker systems is analyzed. The expression for this impedance is obtained directly from the acoustical analogous circuit. Formulas are derived for calculating the small-signal parameters from the frequencies of impedance minima and maxima of two
Lou, Guofeng; Yu, Xinjie; Lu, Shihua
2017-06-15
This paper describes the modeling of magnetoelectric (ME) effects for disk-type Terfenol-D (Tb 0.3 Dy 0.7 Fe 1.92 )/PZT (Pb(Zr,Ti)O₃) laminate composite at low frequency by combining the advantages of the static elastic model and the equivalent circuit model, aiming at providing a guidance for the design and fabrication of the sensors based on magnetoelectric laminate composite. Considering that the strains of the magnetostrictive and piezoelectric layers are not equal in actual operating due to the epoxy resin adhesive bonding condition, the magnetostrictive and piezoelectric layers were first modeled through the equation of motion separately, and then coupled together with a new interface coupling factor k c , which physically reflects the strain transfer between the phases. Furthermore, a theoretical expression containing k c for the transverse ME voltage coefficient α v and the optimum thickness ratio n optim to which the maximum ME voltage coefficient corresponds were derived from the modified equivalent circuit of ME laminate, where the interface coupling factor acted as an ideal transformer. To explore the influence of mechanical load on the interface coupling factor k c , two sets of weights, i.e., 100 g and 500 g, were placed on the top of the ME laminates with the same thickness ratio n in the sample fabrication. A total of 22 T-T mode disk-type ME laminate samples with different configurations were fabricated. The interface coupling factors determined from the measured α v and the DC bias magnetic field H bias were 0.11 for 500 g pre-mechanical load and 0.08 for 100 g pre-mechanical load. Furthermore, the measured optimum thickness ratios were 0.61 for k c = 0.11 and 0.56 for k c = 0.08. Both the theoretical ME voltage coefficient α v and optimum thickness ratio n optim containing k c agreed well with the measured data, verifying the reasonability and correctness for the introduction of k c in the modified equivalent circuit model.
Directory of Open Access Journals (Sweden)
Guofeng Lou
2017-06-01
Full Text Available This paper describes the modeling of magnetoelectric (ME effects for disk-type Terfenol-D (Tb0.3Dy0.7Fe1.92/PZT (Pb(Zr,TiO3 laminate composite at low frequency by combining the advantages of the static elastic model and the equivalent circuit model, aiming at providing a guidance for the design and fabrication of the sensors based on magnetoelectric laminate composite. Considering that the strains of the magnetostrictive and piezoelectric layers are not equal in actual operating due to the epoxy resin adhesive bonding condition, the magnetostrictive and piezoelectric layers were first modeled through the equation of motion separately, and then coupled together with a new interface coupling factor kc, which physically reflects the strain transfer between the phases. Furthermore, a theoretical expression containing kc for the transverse ME voltage coefficient αv and the optimum thickness ratio noptim to which the maximum ME voltage coefficient corresponds were derived from the modified equivalent circuit of ME laminate, where the interface coupling factor acted as an ideal transformer. To explore the influence of mechanical load on the interface coupling factor kc, two sets of weights, i.e., 100 g and 500 g, were placed on the top of the ME laminates with the same thickness ratio n in the sample fabrication. A total of 22 T-T mode disk-type ME laminate samples with different configurations were fabricated. The interface coupling factors determined from the measured αv and the DC bias magnetic field Hbias were 0.11 for 500 g pre-mechanical load and 0.08 for 100 g pre-mechanical load. Furthermore, the measured optimum thickness ratios were 0.61 for kc = 0.11 and 0.56 for kc = 0.08. Both the theoretical ME voltage coefficient αv and optimum thickness ratio noptim containing kc agreed well with the measured data, verifying the reasonability and correctness for the introduction of kc in the modified equivalent circuit model.
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)
Modelling of a High Temperature PEM Fuel Cell Stack using Electrochemical Impedance Spectroscopy
DEFF Research Database (Denmark)
Andreasen, Søren Juhl; Jespersen, Jesper Lebæk; Kær, Søren Knudsen
2008-01-01
This work presents the development of an equivalent circuit model of a 65 cell high temperature PEM (HTPEM) fuel cell stack using Electrochemical Impedance Spectroscopy (EIS). The HTPEM fuel cell membranes used are PBI-based and uses phosphoric acid as proton conductor. The operating temperature...
Directory of Open Access Journals (Sweden)
Pierre Tchakoua
2015-09-01
Full Text Available Models are crucial in the engineering design process because they can be used for both the optimization of design parameters and the prediction of performance. Thus, models can significantly reduce design, development and optimization costs. This paper proposes a novel equivalent electrical model for Darrieus-type vertical axis wind turbines (DTVAWTs. The proposed model was built from the mechanical description given by the Paraschivoiu double-multiple streamtube model and is based on the analogy between mechanical and electrical circuits. This work addresses the physical concepts and theoretical formulations underpinning the development of the model. After highlighting the working principle of the DTVAWT, the step-by-step development of the model is presented. For assessment purposes, simulations of aerodynamic characteristics and those of corresponding electrical components are performed and compared.
Directory of Open Access Journals (Sweden)
Emrah Cetin
2017-10-01
Full Text Available Higher efficiency is always a desire for the electric machines researchers. One serious candidate is the axial flux permanent magnet motor to achieve that. These machines have advantages on power and torque density profile. This study aims to analyse the performances of the different rotor poles’ characteristics of the axial flux permanent magnet machines. The magnetic equivalent circuit designed and placed into the single gap axial flux permanent magnet machine to fathom the machine characteristic. The proposed rotors magnet poles are investigated in the view of the torque ripple reduction, back EMF waveforms and flux density distribution by using finite element analysis. Four different designs are compared. 3D analysis is used for FEA simulations. Torque ripple, back emf and magnetic flux distribution waveforms are obtained from the 3D FEA analysis. As a result, the proposed rotors are practicable and situated for higher performance.
Directory of Open Access Journals (Sweden)
Zuchang Gao
2017-01-01
Full Text Available A computational efficient battery pack model with thermal consideration is essential for simulation prototyping before real-time embedded implementation. The proposed model provides a coupled equivalent circuit and convective thermal model to determine the state-of-charge (SOC and temperature of the LiFePO4 battery working in a real environment. A cell balancing strategy applied to the proposed temperature-dependent battery model balanced the SOC of each cell to increase the lifespan of the battery. The simulation outputs are validated by a set of independent experimental data at a different temperature to ensure the model validity and reliability. The results show a root mean square (RMS error of 1.5609 × 10−5 for the terminal voltage and the comparison between the simulation and experiment at various temperatures (from 5 °C to 45 °C shows a maximum RMS error of 7.2078 × 10−5.
The frequency characteristics of medium voltage distribution system impedances
Directory of Open Access Journals (Sweden)
Liviu Emil Petrean
2009-10-01
Full Text Available In this paper we present the frequency characteristics of impedances involved in the electrical equivalent circuit of a large medium voltage distribution system. These impedances influence harmonics distortions propagation occurring due to the nonsinusoidal loads. We analyse the case of a 10 kV large urban distribution system which supplies industrial, commercial and residential customers. The influence of various parameters of the distribution network on the frequency characteristics are presented, in order to assess the interaction of harmonic distortion and distribution system network.
Oxide impedance characteristics of the Zr-xNb alloys
International Nuclear Information System (INIS)
Park, S. Y.; Choi, B. K.; Jung, Y. H.; Jung, Y. H.
2002-01-01
To elucidate the correlation between the oxide impedance and corrosion characteristics of the Zr-xNb alloys, the long term corrosion test in high temperature / high pressure aqueous solution and the impedance test in the room temperature sulfate solution were performed. β-quenched plate specimens were heat-treated at 570 .deg. C for 500 hours to get the α+β Nb phase and the at 640 .deg. C for 10 hours to get the α+β Zr phase. The impedance test was conducted in sulfate solution for the initial corrosion test specimen (WG = 30 mg/dm 2 ). To evaluate the impedance date, 4 types of equivalent circuits were constructed by 5 parallel and serial RC elements. By using the equivalent circuits, the thickness of the inner and outer layers were calculated and the electric resistance of each layers were estimated. The corrosion behaviour of Zr-xNb alloys were quite different depending of the annealing condition and Nb-content. The corrosion resistance of the β Nb phase contained high Nb alloys were excellent rather than β Zr phase contained high Nb alloys. The electric resistance of the outer layer of β Zr phase contained high Nb alloy was twice larger than that of β Zr phase contained high Nb alloy, and in the case of outer layer 30% larger. So, the long term corrosion behaviors in high temperature could be estimated well by using the impedance test results
Electrochemical impedance measurement of a carbon nanotube probe electrode
International Nuclear Information System (INIS)
Inaba, Akira; Takei, Yusuke; Kan, Tetsuo; Shimoyama, Isao; Matsumoto, Kiyoshi
2012-01-01
We measured and analyzed the electrochemical impedance of carbon nanotube (CNT) probe electrodes fabricated through the physical separation of insulated CNT bridges. The fabricated CNT electrodes were free-standing CNTs that were completely covered with an insulator, except for their tips. Typical dimensions of the nanoelectrodes were 1–10 nm in CNT diameter, 80–300 nm in insulator diameter, 0.5–4 μm in exposed CNT length and 1–10 μm in probe length. The electrochemical impedance at frequencies ranging from 40 Hz to 1 MHz was measured in physiological saline. The measured impedance of the CNT electrode was constant at 32 MΩ at frequencies below 1 kHz and was inversely proportional to frequency at frequencies above 10 kHz. By means of comparison with the parasitic capacitive impedance of the insulator membrane, we confirmed that the electrode was sufficiently insulated such that the measured constant impedance was given by the exposed CNT tip. Consequently, we can use the CNT electrode for highly localized electrochemical impedance measurements below 1 kHz. Considering an equivalent circuit and the nanoscopic dimensions of the CNT electrode, we demonstrated that the constant impedance was governed by diffusion impedance, whereas the solution resistance, charge-transfer resistance and double-layer capacitance were negligible. (paper)
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.
Correlation between the oxide impedance and corrosion behavior of Zr-Nb-Sn-Fe-Cu alloys
Park, Sang-Yoon; Lee, Myung-Ho; Jeong, Yong-Hwan; Jung, Youn-Ho
2004-12-01
The correlation between the oxide impedance and corrosion behavior of two series of Zr-Nb-Sn-Fe-Cu alloys was evaluated. Corrosion tests were performed in a 70 ppm LiOH aqueous solution at 360°C for 300 days. The results of the corrosion tests revealed that the corrosion behavior of the alloys depended on the Nb and Sn content. The impedance characteristics for the pre- and post-transition oxide layers formed on the surface of the alloys were investigated in sulfuric acid at room temperature. From the results, a pertinent equivalent circuit model was preferably established, explaining the properties of double oxide layers. The impedance of the oxide layers correlated with the corrosion behavior; better corrosion resistance always showed higher electric resistance for the inner layers. It is thus concluded that a pertinent equivalent circuit model would be useful for evaluating the long-term corrosion behavior of Zr-Nb-Sn-Fe-Cu alloys.
Fleischer, Christian; Waag, Wladislaw; Heyn, Hans-Martin; Sauer, Dirk Uwe
2014-09-01
Lithium-ion battery systems employed in high power demanding systems such as electric vehicles require a sophisticated monitoring system to ensure safe and reliable operation. Three major states of the battery are of special interest and need to be constantly monitored. These include: battery state of charge (SoC), battery state of health (capacity fade determination, SoH), and state of function (power fade determination, SoF). The second paper concludes the series by presenting a multi-stage online parameter identification technique based on a weighted recursive least quadratic squares parameter estimator to determine the parameters of the proposed battery model from the first paper during operation. A novel mutation based algorithm is developed to determine the nonlinear current dependency of the charge-transfer resistance. The influence of diffusion is determined by an on-line identification technique and verified on several batteries at different operation conditions. This method guarantees a short response time and, together with its fully recursive structure, assures a long-term stable monitoring of the battery parameters. The relative dynamic voltage prediction error of the algorithm is reduced to 2%. The changes of parameters are used to determine the states of the battery. The algorithm is real-time capable and can be implemented on embedded systems.
Pridham, G J
2013-01-01
Solid-State Circuits provides an introduction to the theory and practice underlying solid-state circuits, laying particular emphasis on field effect transistors and integrated circuits. Topics range from construction and characteristics of semiconductor devices to rectification and power supplies, low-frequency amplifiers, sine- and square-wave oscillators, and high-frequency effects and circuits. Black-box equivalent circuits of bipolar transistors, physical equivalent circuits of bipolar transistors, and equivalent circuits of field effect transistors are also covered. This volume is divided
Directory of Open Access Journals (Sweden)
Bizhong Xia
2017-08-01
Full Text Available Accurate state of charge (SOC estimation can prolong lithium-ion battery life and improve its performance in practice. This paper proposes a new method for SOC estimation. The second-order resistor-capacitor (2RC equivalent circuit model (ECM is applied to describe the dynamic behavior of lithium-ion battery on deriving state space equations. A novel method for SOC estimation is then presented. This method does not require any matrix calculation, so the computation cost can be very low, making it more suitable for hardware implementation. The Federal Urban Driving Schedule (FUDS, The New European Driving Cycle (NEDC, and the West Virginia Suburban Driving Schedule (WVUSUB experiments are carried to evaluate the performance of the proposed method. Experimental results show that the SOC estimation error can converge to 3% error boundary within 30 seconds when the initial SOC estimation error is 20%, and the proposed method can maintain an estimation error less than 3% with 1% voltage noise and 5% current noise. Further, the proposed method has excellent robustness against parameter disturbance. Also, it has higher estimation accuracy than the extended Kalman filter (EKF, but with decreased hardware requirements and faster convergence rate.
Directory of Open Access Journals (Sweden)
Bart Wymeersch
2018-04-01
Full Text Available Line start permanent magnet synchronous motors (LS-PMSM are energy-efficient synchronous motors that can start asynchronously due to a squirrel cage in the rotor. The drawback, however, with this motor type is the chance of failure to synchronize after start-up. To identify the problem, and the stable operation limits, the synchronization at various parameter combinations is investigated. For accurate knowledge of the operation limits to assure synchronization with the utility grid, an accurate classification of parameter combinations is needed. As for this, many simulations have to be executed, a rapid evaluation method is indispensable. To simulate the dynamic behavior in the time domain, several modeling methods exist. In this paper, a discussion is held with respect to different modeling methods. In order to include spatial factors and magnetic nonlinearities, on the one hand, and to restrict the computation time on the other hand, a magnetic equivalent circuit (MEC modeling method is developed. In order to accelerate numerical convergence, a mesh-based analysis method is applied. The novelty in this paper is the implementation of support vector machine (SVM to classify the results of simulations at various parameter combinations into successful or unsuccessful synchronization, in order to define the synchronization capability limits. It is explained how these techniques can benefit the simulation time and the evaluation process. The results of the MEC modeling correspond to those obtained with finite element analysis (FEA, despite the reduced computation time. In addition, simulation results obtained with MEC modeling are experimentally validated.
Intraesophageal impedance monitoring: clinical studies
Conchillo Armendáriz, J.M.
2007-01-01
Electrical impedance (Z) between two electrodes is the ratio between applied voltage (U) and resulting current (I). In electrical impedance monitoring the resistance to electrical flow in an alternating current circuit is measured. Multichannel esophageal monitoring can be measured by using an
Energy Technology Data Exchange (ETDEWEB)
Lopez Garcia, I.; Escalera Perez, R. [Universidad Autonoma Metropolitana - Azcapotzalco (Mexico)]. E-mail: irvinlopez@yahoo.com; r.escalera@ieee.org; Niewierowicz Swiecicka, T. [Instituto Politecnico Nacional, U.P. Adolfo Lopez Mateos (Mexico)]. E-mail: tniewi@ipn.mx; Campero Littlewood, E.[Universidad Autonoma Metropolitana - Azcapotzalco (Mexico)]. E-mail: ecl@correo.azc.uam.mx
2010-01-15
This work shows the results of a parametric sensitivity analysis applied to a state-space representation of high-order two-axis equivalent circuits (Ecs) of a turbo generator (150 MVA, 120 MW, 13.8 kV y 50 Hz). The main purpose of this study is to evaluate each parameter impact on the transient response of the analyzed two axis models -d axis Ecs with one to five damper branches and q axis Ecs from one to four damper branches-. The parametric sensitivity concept is formulated in a general context and the sensibility function is established from the generator response to a short circuit condition. Results ponder the importance played by each parameter in the model behavior. The algorithms were design within MATLAB environment. The study gives way to conclusion on electromagnetic aspects of solid rotor synchronous generators that have not been previously studied. The methodology presented here can be applied to any other physical system. [Spanish] En este trabajo se presentan los resultados del analisis de sensibilidad parametrica realizado a modelos de circuitos equivalentes de orden superior de un turbogenerador (150 MVA, 120 MW, 13.8 kV y 50 Hz). La representacion del generador sincrono se hace en el espacio de estados, utilizando la teoria de dos ejes (d y a). El objetivo del estudio de sensibilidad es evaluar el impacto que tiene cada uno de los parametros en la respuesta transitoria de los modelos analizados -circuitos equivalentes desde una hasta cinco ramas de amortiguamiento en el eje d y de una a cuatro ramas en el eje q-. En este trabajo el concepto de sensibilidad parametrica se formula en terminos generales, planteando la funcion de sensibilidad a partir de condiciones de cortocircuito en las terminales del generador. Los resultados se presentan senalando el nivel de importancia de cada parametro en el comportamiento del modelo. Los algoritmos utilizados fueron disenados en MATLAB. Asi, este estudio permite inferir aspectos electromagneticos de los
Impedance analysis on organic ultrathin layers
Energy Technology Data Exchange (ETDEWEB)
Bom, Sidhant; Wagner, Veit [Jacobs University Bremen, School of Engineering and Science, Campus Ring 8, 28759 Bremen (Germany)
2008-07-01
Impedance spectroscopy is a standard technique for thin film analysis to obtain important information as thicknesses, diffusion properties of mobile ions and leakage currents. The measured electrical impedance of a sample is modeled by a physical equivalent circuit of resistors and capacitors. In the present work this information is obtained as a function of frequency also for ultrathin organic layers in the monolayer regime. A series of semiconducting and insulating polymers (regioregular poly-3-hexylthiophene (rr-P3HT), polymethylmethacrylate (PMMA)) and self assembled monolayers (octadecyltrichlorosilane (OTS), hexamethyldisilazane (HMDS), thiolated phospholipids) were deposited either on highly n-doped silicon wafers or on gold surfaces. E.g. ultrathin layers were obtained by dip coating a silicon wafer in rr-P3HT solution in chloroform. The thickness of 2 nm determined for this system by impedance measurement agrees well with the atomic force microscopy analysis and corresponds to a single layer of polymer chains. The leakage current is seen as an ohmic contribution at low frequencies and allows a systematic optimization of process parameters. In summary, impedance spectroscopy allows very fast and convenient analysis of thin organic layers even down to the monolayer regime.
Weicht, J. A.; Hamelmann, F. U.; Behrens, G.
2016-02-01
Silicon-based thin film tandem solar cells consist of one amorphous (a-Si) and one microcrystalline (μc-Si) silicon solar cell. The Staebler - Wronski effect describes the light- induced degradation and temperature-dependent healing of defects of silicon-based solar thin film cells. The solar cell degradation depends strongly on operation temperature. Until now, only the light-induced degradation (LID) of the amorphous layer was examined in a-Si/μc-Si solar cells. The LID is also observed in pc-Si single function solar cells. In our work we show the influence of the light-induced degradation of the μc-Si layer on the diode equivalent circuit. The current-voltage-curves (I-V-curves) for the initial state of a-Si/pc-Si modules are measured. Afterwards the cells are degraded under controlled conditions at constant temperature and constant irradiation. At fixed times the modules are measured at standard test conditions (STC) (AM1.5, 25°C cell temperature, 1000 W/m2) for controlling the status of LID. After the degradation the modules are annealed at dark conditions for several hours at 120°C. After the annealing the dangling bonds in the amorphous layer are healed, while the degradation of the pc-Si is still present, because the healing of defects in pc-Si solar cells needs longer time or higher temperatures. The solar cells are measured again at STC. With this laboratory measured I-V-curves we are able to separate the values of the diode model: series Rs and parallel resistance Rp, saturation current Is and diode factor n.
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...... from driver to driver. Therefore, a loudspeaker emulator capable of adjusting its impedance to that of a given driver is desired for measurement purposes. This paper proposes a loudspeaker emulator circuit for small signals. Simulations and experimental results are compared and show that it is possible...... to emulate the loudspeaker impedance with an electric circuit and that its resonance frequency can be changed by tuning two resistors....
Wu, Ching-Chou; Lin, Chia-Hung; Wang, Way-Shyan
2009-06-30
Enrofloxacin is the most widespread antibiotic in the fluoroquinolone family. As such, the development of a rapid and sensitive method for the determination of trace amounts of enrofloxacin is an important issue in the health field. The interaction of the enrofloxacin antigen to a specific antibody (Ab) immobilized on an 11-mercapto-undecanoic acid-coated gold electrode was quantified by electrochemical impedance spectroscopy. Two equivalent circuits were separately used to interpret the obtained impedance spectra. These circuits included one resistor in series with one parallel circuit comprised of a resistor and a capacitor (1R//C), and one resistor in series with two parallel RC circuits (2R//C). The results indicate that the antigen-antibody reaction analyzed using the 1R//C circuit provided a more sensitive resistance increment against the enrofloxacin concentration than that of the 2R//C circuit. However, the 2R//C circuit provided a better fitting for impedance spectra, and therefore supplies more detailed results of the enrofloxacin-antibody interaction, causing the increase of electron transfer resistance selectively to the modified layer, and not the electrical double layer. The antibody-modified electrode allowed for analysis of the dynamic linear range of 1-1000 ng/ml enrofloxacin with a detection limit of 1 ng/ml. The reagentless and label-free impedimetric immunosensors provide a simple and sensitive detection method for the specific determination of enrofloxacin.
Smart Multi-Frequency Bioelectrical Impedance Spectrometer for BIA and BIVA Applications.
Harder, Rene; Diedrich, Andre; Whitfield, Jonathan S; Buchowski, Macie S; Pietsch, John B; Baudenbacher, Franz J
2016-08-01
Bioelectrical impedance analysis (BIA) is a noninvasive and commonly used method for the assessment of body composition including body water. We designed a small, portable and wireless multi-frequency impedance spectrometer based on the 12 bit impedance network analyzer AD5933 and a precision wide-band constant current source for tetrapolar whole body impedance measurements. The impedance spectrometer communicates via Bluetooth with mobile devices (smart phone or tablet computer) that provide user interface for patient management and data visualization. The export of patient measurement results into a clinical research database facilitates the aggregation of bioelectrical impedance analysis and biolectrical impedance vector analysis (BIVA) data across multiple subjects and/or studies. The performance of the spectrometer was evaluated using a passive tissue equivalent circuit model as well as a comparison of body composition changes assessed with bioelectrical impedance and dual-energy X-ray absorptiometry (DXA) in healthy volunteers. Our results show an absolute error of 1% for resistance and 5% for reactance measurements in the frequency range of 3 kHz to 150 kHz. A linear regression of BIA and DXA fat mass estimations showed a strong correlation (r(2)=0.985) between measures with a maximum absolute error of 6.5%. The simplicity of BIA measurements, a cost effective design and the simple visual representation of impedance data enables patients to compare and determine body composition during the time course of a specific treatment plan in a clinical or home environment.
Directory of Open Access Journals (Sweden)
Congcong Cheng
2016-01-01
Full Text Available A practical piezoelectric vibration energy harvesting (PVEH system is usually composed of two coupled parts: a harvesting structure and an interface circuit. Thus, it is much necessary to build system-level coupled models for analyzing PVEH systems, so that the whole PVEH system can be optimized to obtain a high overall efficiency. In this paper, two classes of coupled models are proposed by joint finite element and circuit analysis. The first one is to integrate the equivalent circuit model of the harvesting structure with the interface circuit and the second one is to integrate the equivalent electrical impedance of the interface circuit into the finite element model of the harvesting structure. Then equivalent circuit model parameters of the harvesting structure are estimated by finite element analysis and the equivalent electrical impedance of the interface circuit is derived by circuit analysis. In the end, simulations are done to validate and compare the proposed two classes of system-level coupled models. The results demonstrate that harvested powers from the two classes of coupled models approximate to theoretic values. Thus, the proposed coupled models can be used for system-level optimizations in engineering applications.
International Nuclear Information System (INIS)
Kil-Mo, Koo; Sang-Baik, Kim; Hee-Dong, Kim; Gyu-Tae, Kim
2007-01-01
An electrical signal should be checked to see whether it lies within its expected electrical range when there is a doubtful condition. The normal signal level for pressure, flow, level and resistance temperature detector sensors is 4-20 mA in most industrial process controls. In the case of an abnormal signal level from an instrument under a severe accident condition, it is necessary to obtain a more accurate signal validation to operate a system in a control room in NPPs. Diagnostics and analysis for some abnormal signals have been performed through an important equivalent circuits modeling for passive elements under severe accident conditions. Unlike the design basis accidents, there are some inherent uncertainties for the instrumentation capabilities under severe accident conditions. In this paper, to implement a diagnostic analysis for an equivalent circuits modeling, a kind of linked LabVIEW program for each PSpice and MULTI-SIM code is introduced as a one body order system, which can obtain some abnormal signal patterns by a special function such as an advanced simulation tool for each PSpice and Multi-SIM code as a means of a function for a PC based ASSA (Abnormal Signal Simulation Analyzer) module. The output signal can be analyzed by a comparative analysis of each PSpice and Multi-SIM code for a 4-20 mA circuit modeling which is by a composition of an R-L-C passive circuit as an alternating range of the elements for the temperature accident condition. In this simulation, a new simulator through an analysis of the important equivalent circuits modeling has been designed, the designed simulator is composed of the LabVIEW code as a main tool and the out-put file of each PSpice code and a Multi-SIM engine code as an engine tool is exported to the in-put file of the LabVIEW code. There are 3 main function units of the ASSA module, the first one is individual PSpice and Multi-SIM engine code units to comprise an equivalent circuit element, the second one is the
Ravikiran, Y. T.; Vijaya Kumari, S. C.
2013-06-01
To innovate the properties of Polypyrrole/Titanium dioxide (PPy/TiO2) nanocomposite further, it has been synthesized by chemical polymerization technique. The nanostructure and monoclinic phase of the prepared composite have been confirmed by simulating the X-ray diffraction pattern (XRD). Also, complex plane impedance plot of the composite has been simulated to find equivalent resistance capacitance circuit (RC circuit) and numerical values of R and C have been predicted.
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
In-Plane Impedance Spectroscopy measurements in Vanadium Dioxide thin films
Ramirez, Juan; Patino, Edgar; Schmidt, Rainer; Sharoni, Amos; Gomez, Maria; Schuller, Ivan
2012-02-01
In plane Impedance Spectroscopy measurements have been done in Vanadium Dioxide thin films in the range of 100 Hz to 1 MHz. Our measurements allows distinguishing between the resistive and capacitive response of the Vanadium Dioxide films across the metal-insulator transition. A non ideal RC behavior was found in our thin films from room temperature up to 334 K. Around the MIT, an increase of the total capacitance is observed. A capacitor-network model is able to reproduce the capacitance changes across the MIT. Above the MIT, the system behaves like a metal as expected, and a modified equivalent circuit is necessary to describe the impedance data adequately.
Plasma diagnosis of RF discharge by using impedance measurement
International Nuclear Information System (INIS)
Huang Jianjun; Teuner, D.
2001-01-01
It is presented that the method known from network analysis with home-made probe and experimental setup to measure current, voltage and phase angle of RF discharge in He gas more accurately. The sheath thickness and the real and imaginary parts of the plasma impedance were obtained by using the equivalent circuit model and taking account stray capacitances of the set-up. In addition, making use of Godyak's RF discharge simple model, the electron density in the discharge was calculated at different pressure and current density
Unstable oscillators based hyperchaotic circuit
DEFF Research Database (Denmark)
Murali, K.; Tamasevicius, A.; G. Mykolaitis, A.
1999-01-01
A simple 4th order hyperchaotic circuit with unstable oscillators is described. The circuit contains two negative impedance converters, two inductors, two capacitors, a linear resistor and a diode. The Lyapunov exponents are presented to confirm hyperchaotic nature of the oscillations in the circ...... in the circuit. The performance of the circuit is investigated by means of numerical integration of appropriate differential equations, PSPICE simulations, and hardware experiment.......A simple 4th order hyperchaotic circuit with unstable oscillators is described. The circuit contains two negative impedance converters, two inductors, two capacitors, a linear resistor and a diode. The Lyapunov exponents are presented to confirm hyperchaotic nature of the oscillations...
Energy Technology Data Exchange (ETDEWEB)
Sung, Chang Kyu [Dept. of Radiology, SMG-SNU Boramae Medical Center, Seoul National University College of Medicine, Seoul (Korea, Republic of); Han, Bong Soo [Dept. of Radiological Science, College of Health Science, Yonsei University, Wonju (Korea, Republic of); Kim, Seung Hyup [Dept. of Radiology, Institute of Radiation Medicine, Seoul National University Hospital, Seoul National University College of Medicine, Seoul (Korea, Republic of)
2016-01-15
The goal of this study was to evaluate the effect of vascular compliance, resistance, and pulse rate on the resistive index (RI) by using an electrical circuit model to simulate renal blood flow. In order to analyze the renal arterial Doppler waveform, we modeled the renal blood-flow circuit with an equivalent simple electrical circuit containing resistance, inductance, and capacitance. The relationships among the impedance, resistance, and compliance of the circuit were derived from well-known equations, including Kirchhoff’s current law for alternating current circuits. Simulated velocity-time profiles for pulsatile flow were generated using Mathematica (Wolfram Research) and the influence of resistance, compliance, and pulse rate on waveforms and the RI was evaluated. Resistance and compliance were found to alter the waveforms independently. The impedance of the circuit increased with increasing proximal compliance, proximal resistance, and distal resistance. The impedance decreased with increasing distal compliance. The RI of the circuit decreased with increasing proximal compliance and resistance. The RI increased with increasing distal compliance and resistance. No positive correlation between impedance and the RI was found. Pulse rate was found to be an extrinsic factor that also influenced the RI. This simulation study using an electrical circuit model led to a better understanding of the renal arterial Doppler waveform and the RI, which may be useful for interpreting Doppler findings in various clinical settings.
International Nuclear Information System (INIS)
Sung, Chang Kyu; Han, Bong Soo; Kim, Seung Hyup
2016-01-01
The goal of this study was to evaluate the effect of vascular compliance, resistance, and pulse rate on the resistive index (RI) by using an electrical circuit model to simulate renal blood flow. In order to analyze the renal arterial Doppler waveform, we modeled the renal blood-flow circuit with an equivalent simple electrical circuit containing resistance, inductance, and capacitance. The relationships among the impedance, resistance, and compliance of the circuit were derived from well-known equations, including Kirchhoff’s current law for alternating current circuits. Simulated velocity-time profiles for pulsatile flow were generated using Mathematica (Wolfram Research) and the influence of resistance, compliance, and pulse rate on waveforms and the RI was evaluated. Resistance and compliance were found to alter the waveforms independently. The impedance of the circuit increased with increasing proximal compliance, proximal resistance, and distal resistance. The impedance decreased with increasing distal compliance. The RI of the circuit decreased with increasing proximal compliance and resistance. The RI increased with increasing distal compliance and resistance. No positive correlation between impedance and the RI was found. Pulse rate was found to be an extrinsic factor that also influenced the RI. This simulation study using an electrical circuit model led to a better understanding of the renal arterial Doppler waveform and the RI, which may be useful for interpreting Doppler findings in various clinical settings
Understanding the Behaviour of Infinite Ladder Circuits
Ucak, C.; Yegin, K.
2008-01-01
Infinite ladder circuits are often encountered in undergraduate electrical engineering and physics curricula when dealing with series and parallel combination of impedances, as a part of filter design or wave propagation on transmission lines. The input impedance of such infinite ladder circuits is derived by assuming that the input impedance does…
Vandamme, E.P.; Schreurs, D.; Dinther, van C.H.J.; Badenes, G.; Deferm, L.
2002-01-01
The improved RF performance of silicon-based technologies over the years and their potential use in telecommunication applications has increased the research in RF modelling of MOS transistors. Especially for analog circuits, accurate RF small signal and large signal transistor models are required.
International Nuclear Information System (INIS)
Krhounkova, J.; Kral, P.; Parduba, Z.
1999-10-01
The conservative assumptions of the analyses were oriented towards a worsening of the process with respect to the pressurized thermal shock (PTS). Four variants were treated, viz. leaks from the cold or hot leg, each at the rated power or zero power. Since the temperature of water supplied to the primary circuit by the emergency core cooling system is an important parameter with respect to a PTS, the calculations were performed by the iterative procedure: the basic thermal hydraulic calculation was performed by the RELAP5/MOD3.2.1 code which calculates the behaviour of the primary and secondary circuits, whereas the MELCOR code was used to calculate the behaviour of the parameters in the hermetic rooms. The calculation by the RELAP code was then repeated using data from the MELCOR calculations. Interventions by the reactor operators were also considered. (P.A.)
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.
Application of an impedance matching transformer to a plasma focus.
Bures, B L; James, C; Krishnan, M; Adler, R
2011-10-01
A plasma focus was constructed using an impedance matching transformer to improve power transfer between the pulse power and the dynamic plasma load. The system relied on two switches and twelve transformer cores to produce a 100 kA pulse in short circuit on the secondary at 27 kV on the primary with 110 J stored. With the two transformer systems in parallel, the Thevenin equivalent circuit parameters on the secondary side of the driver are: C = 10.9 μF, V(0) = 4.5 kV, L = 17 nH, and R = 5 mΩ. An equivalent direct drive circuit would require a large number of switches in parallel, to achieve the same Thevenin equivalent. The benefits of this approach are replacement of consumable switches with non-consumable transformer cores, reduction of the driver inductance and resistance as viewed by the dynamic load, and reduction of the stored energy to produce a given peak current. The system is designed to operate at 100 Hz, so minimizing the stored energy results in less load on the thermal management system. When operated at 1 Hz, the neutron yield from the transformer matched plasma focus was similar to the neutron yield from a conventional (directly driven) plasma focus at the same peak current.
International Nuclear Information System (INIS)
Lee, Seung Hyun; Song, Ho Seung; Kim, Jeong Hwan; Cong, Truong Van; Kim, Hui Su; Yeon, Yeong Heum; Lee, Yong seok; Chai, Jong Seo
2015-01-01
The SKKUCY-9 is a compact cyclotron for radioactive isotopes (RI) production of positron emission tomography (PET). Charged particles such as H-ions are accelerated azimuthally within a high intensity electric field (E-field) generated from a radio frequency (RF) system in cyclotron. A high power RF signal is transmitted from an RF amplifier to an RF resonating cavity. The RF system of the SKKUCY-9 operates in continuous wave (CW) mode. If an ion beam were accelerated in the cyclotron, the vacuum level and permittivity would be changed because of beam loading. It causes an impedance shift of the RF resonating cavity. This impedance mismatch generates reflected power that decreases the RF transmitting power. To prevent this situation, an impedance matching system is necessary. This paper describes the impedance matching system of a 20 kW RF amplifier in an SKKUCY-9 compact cyclotron. The impedance matching circuit was designed using both an input stage and output stage, which are divided between the cathode and anode in a vacuum tube that is used as an amplifying device. The equivalent circuit of the matching system is made of passive elements. The characteristic results of designed circuit were calculated using a Smith chart. In assembling, the inductors were replaced by movable stub-line structures. The dimensions of the stub-line structures were optimized with equations and the measurement results. The experiment was performed to find the result values of matching circuit impedance and RF power amplitude
Complex impedance techniques and some properties of Mn sub 0.5 Zn sub 0.5 Fe sub 2 O sub 4 ferrite
International Nuclear Information System (INIS)
Ahmad Nazlim Yusoff; Mustaffa Abdullah
1995-01-01
Complex impedances (Z-axes = Z' - jZ ) of a standard parallel R-C circuit and a Mn sub 0.5 Zn sub 0.5 Fe sub 2 O sub 4 ferrite sample at 300 K have been measured in the frequency range 1 Hz to 10 MHz by a technique of phase shift. For comparison, the impedances of both systems were also measured using Schlumberger HF 1255 frequency response analyzer. The complex impedance spectrum (Z' vs Z') from the R-C circuit is a perfect semicircle, whereas the spectrum for the ferrite sample is a semicircular curve with its centre being depressed to below the real impedance axis. The depression of the semicircle for the ferrite is discussed as due to a deviation from the ideal Debye relaxation process. An equivalent circuit model that comprises of a capacitor and a resistor in parallel is suggested for the ferrite, but the result for the impedance is modified by including a factor that accounts for the distribution of the relaxation time. The simulated data from the circuit are in agreement with those from the experiment. The dispersion of the impedance is attributed to the conduction and polarization processes in the material
DEFF Research Database (Denmark)
Johansen, Tom Keinicke; Leblanc, Rémy; Poulain, Julien
2016-01-01
A unique direct parameter extraction method for the small-signal equivalent-circuit model of InP/GaAsSb/InP double heterojunction bipolar transistors (DHBTs) is presented. $S$-parameters measured at cut-off bias are used, at first, to extract the distribution factor $X_{0}$ for the base-collector......A unique direct parameter extraction method for the small-signal equivalent-circuit model of InP/GaAsSb/InP double heterojunction bipolar transistors (DHBTs) is presented. $S$-parameters measured at cut-off bias are used, at first, to extract the distribution factor $X_{0}$ for the base......-collector capacitance at zero collector current and the collector-to-emitter overlap capacitance $C_{ceo}$ present in InP DHBT devices. Low-frequency $S$-parameters measured at normal bias conditions then allows the extraction of the external access resistances $R_{bx}$, $R_{e}$, and $R_{cx}$ as well as the intrinsic...
Energy Technology Data Exchange (ETDEWEB)
Takahisa, K; Kojima, T; Nakamura, K; Koyanagi, T; Yanagisawa, T [Electrotechnical Laboratory, Tsukuba (Japan)
1997-11-25
Investigations were given on how the equivalent circuit constants change when efficiency of amorphous silicon solar cells changes with time in light degradation and temperature recovery. In the experiment, light irradiation tests under a constant temperature and light intensity condition, followed by recovery tests under a constant temperature and constant weak light intensity or constant temperature condition were repeated continuously. According to the result of an experiment on single layer type cells, the change in each equivalent circuit constant in association with degradation in efficiency and file factor and variation in recovery is reversible mostly. However, a slightly irreversible component was recognized only in the initial degradation process in series resistance and diode factor values. With regard to stacked cells, it was suggested that the main players to determine cell characteristics during the processes of deterioration and recovery take turns among the three layers as follows: the shape of the time-based change in the efficiency comes different and is not saturating; as the efficiency decreases, the extent of the change increases in the diode factor and series resistance; and the path the deterioration takes differs from that the recovery takes. 2 refs., 12 figs.
International Nuclear Information System (INIS)
Šály, V; Pern, M; Janíček, F; Mikolášek, M; Packa, J; Huran, J
2017-01-01
Progressive smart photovoltaic technologies including heterostructures a-SiC/c-Si with ITO antireflection film are one of the prospective replacements of conventional photovoltaic silicon technology. Our paper is focused on the investigation of heterostructures a-SiC/c-Si provided with a layer of ITO (indium oxide/tin oxide 90/10 wt.%) which acts as a passivating and antireflection coating. Prepared photovoltaic cell structure was investigated at various temperatures and the influence of temperature on its operation was searched. The investigation of the dynamic properties of heterojunction PV cells was carried out using impedance spectroscopy. The equivalent AC circuit which approximates the measured impedance data was proposed. Assessment of the influence of the temperature on the operation of prepared heterostructure was carried out by analysis of the temperature dependence of AC equivalent circuit elements. (paper)
Šály, V.; Perný, M.; Janíček, F.; Huran, J.; Mikolášek, M.; Packa, J.
2017-04-01
Progressive smart photovoltaic technologies including heterostructures a-SiC/c-Si with ITO antireflection film are one of the prospective replacements of conventional photovoltaic silicon technology. Our paper is focused on the investigation of heterostructures a-SiC/c-Si provided with a layer of ITO (indium oxide/tin oxide 90/10 wt.%) which acts as a passivating and antireflection coating. Prepared photovoltaic cell structure was investigated at various temperatures and the influence of temperature on its operation was searched. The investigation of the dynamic properties of heterojunction PV cells was carried out using impedance spectroscopy. The equivalent AC circuit which approximates the measured impedance data was proposed. Assessment of the influence of the temperature on the operation of prepared heterostructure was carried out by analysis of the temperature dependence of AC equivalent circuit elements.
Stupin, Daniil D.; Koniakhin, Sergei V.; Verlov, Nikolay A.; Dubina, Michael V.
2017-05-01
The time-domain technique for impedance spectroscopy consists of computing the excitation voltage and current response Fourier images by fast or discrete Fourier transformation and calculating their relation. Here we propose an alternative method for excitation voltage and current response processing for deriving a system impedance spectrum based on a fast and flexible adaptive filtering method. We show the equivalence between the problem of adaptive filter learning and deriving the system impedance spectrum. To be specific, we express the impedance via the adaptive filter weight coefficients. The noise-canceling property of adaptive filtering is also justified. Using the RLC circuit as a model system, we experimentally show that adaptive filtering yields correct admittance spectra and elements ratings in the high-noise conditions when the Fourier-transform technique fails. Providing the additional sensitivity of impedance spectroscopy, adaptive filtering can be applied to otherwise impossible-to-interpret time-domain impedance data. The advantages of adaptive filtering are justified with practical living-cell impedance measurements.
Diffusion and Gas Conversion Analysis of Solid Oxide Fuel Cells at Loads via AC Impedance
Directory of Open Access Journals (Sweden)
Robert U. Payne
2011-01-01
Full Text Available Impedance measurements were conducted under practical load conditions in solid oxide fuel cells of differing sizes. For a 2 cm2 button cell, impedance spectra data were separately measured for the anode, cathode, and total cell. Improved equivalent circuit models are proposed and applied to simulate each of measured impedance data. Circuit elements related to the chemical and physical processes have been added to the total-cell model to account for an extra relaxation process in the spectra not measured at either electrode. The processes to which elements are attributed have been deduced by varying cell temperature, load current, and hydrogen concentration. Spectra data were also obtained for a planar stack of five 61 cm2 cells and the individual cells therein, which were fitted to a simplified equivalent circuit model of the total button cell. Similar to the button cell, the planar cells and stack exhibit a pronounced low-frequency relaxation process, which has been attributed to concentration losses, that is, the combined effects of diffusion and gas conversion. The simplified total-cell model approximates well the dynamic behavior of the SOFC cells and the whole stack.
Electronic devices and circuits
Pridham, Gordon John
1972-01-01
Electronic Devices and Circuits, Volume 3 provides a comprehensive account on electronic devices and circuits and includes introductory network theory and physics. The physics of semiconductor devices is described, along with field effect transistors, small-signal equivalent circuits of bipolar transistors, and integrated circuits. Linear and non-linear circuits as well as logic circuits are also considered. This volume is comprised of 12 chapters and begins with an analysis of the use of Laplace transforms for analysis of filter networks, followed by a discussion on the physical properties of
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 implement at a low cost. This makes it appealing as a characterization method for on-line diagnostic algorithms. In this work a parameter estimation method for estimation of equivalent electrical circuit (EEC) parameters, which is suited for on-line use is proposed. Tests on a 10 cell high temperature PEM...... fuel cell show that the method yields consistent results in estimating EEC parameters for different current pulse at different current loads, with a low variance. A comparison with EIS shows that despite its simplicity the response of CPI can reproduce well the impedance response of the high...
Directory of Open Access Journals (Sweden)
Martini Milena
2000-01-01
Full Text Available The morphology, thickness, oxidation and illumination effects in dodecylsulphate doped polypyrrole films can be qualitatively observed by EIS and consist in variations of interfacial and bulk resistances and capacitances of a proposed equivalent circuit. The circuit well with the measured spectra of films obtained with 190 mC cm-2 of synthesis charge density. For thinner films the calculated values observed by electrochemical impedance spectroscopy (EIS deviate probably due to the absence of diffusion effects. The oxidation of the films diminishes the total impedance over the entire frequency range. The morphology effects are also observed in the entire spectra. The illumination effects are reversible and are observed as expected only in the reduced form of the polymer. The illumination reduces the internal resistance and the space-charge capacitance and increases the charge transfer resistance and the double layer capacitance.
Organic electrochemical transistors for cell-based impedance sensing
International Nuclear Information System (INIS)
Rivnay, Jonathan; Ramuz, Marc; Hama, Adel; Huerta, Miriam; Owens, Roisin M.; Leleux, Pierre
2015-01-01
Electrical impedance sensing of biological systems, especially cultured epithelial cell layers, is now a common technique to monitor cell motion, morphology, and cell layer/tissue integrity for high throughput toxicology screening. Existing methods to measure electrical impedance most often rely on a two electrode configuration, where low frequency signals are challenging to obtain for small devices and for tissues with high resistance, due to low current. Organic electrochemical transistors (OECTs) are conducting polymer-based devices, which have been shown to efficiently transduce and amplify low-level ionic fluxes in biological systems into electronic output signals. In this work, we combine OECT-based drain current measurements with simultaneous measurement of more traditional impedance sensing using the gate current to produce complex impedance traces, which show low error at both low and high frequencies. We apply this technique in vitro to a model epithelial tissue layer and show that the data can be fit to an equivalent circuit model yielding trans-epithelial resistance and cell layer capacitance values in agreement with literature. Importantly, the combined measurement allows for low biases across the cell layer, while still maintaining good broadband signal
International Nuclear Information System (INIS)
Detch, J.L. Jr.; Noel, B.W.
1981-01-01
Electrically gated proximity-focused channel intensifier tubes are often used as optical shutters. Optimum nanosecond shuttering requires both understanding the electrical pulse propagation across the device structure and proper impedance matching. A distributed-transmission-line model is developed that describes analytically the voltage- and current-wave propagation characteristics as functions of time for any point on the surface. The optical gain's spatial uniformity and shutter-open times are shown to depend on the electrical pulse width and amplitude, and on the applied bias. The driving-point impedance is derived from the model and is expressed as a function of an infinite sum of terms in the complex frequency. The synthesis in terms of lumped-constant network elements is realized in first- and second-Foster equivalent circuits. Experimental impedance data are compared with the model's predictions and deviations from the ideal model are discussed
Directory of Open Access Journals (Sweden)
Ivan M Roitt
2010-01-01
Full Text Available Bioimpedance measurements are of great use and can provide considerable insight into biological processes. However, there are a number of possible sources of measurement error that must be considered. The most dominant source of error is found in bipolar measurements where electrode polarisation effects are superimposed on the true impedance of the sample. Even with the tetrapolar approach that is commonly used to circumvent this issue, other errors can persist. Here we characterise the positive phase and rise in impedance magnitude with frequency that can result from the presence of any parallel conductive pathways in the measurement set-up. It is shown that fitting experimental data to an equivalent electrical circuit model allows for accurate determination of the true sample impedance as validated through finite element modelling (FEM of the measurement chamber. Finally, the model is used to extract dispersion information from cell cultures to characterise their growth.
Study on Turn-to-turn Short Circuit On一line Monitoring System for Dry一type Ai r一core Reactor
Directory of Open Access Journals (Sweden)
GAO Zi-wei
2017-04-01
Full Text Available The change of current value caused by turn-to-turn short circuit of dry-type air-core reactor is so little that failure detection is difficult to be carried out. In order to solve this problem，a new on-line monitoring system based on impedance variation of turn-to-turn short circuit is proposed. The numerical method is applied to analyze the variation of equivalent resistance and equivalent reactance when dry-type air-core reactor winding short circuit happens in different places，and the monitoring method based on harmonic analysis method and quasi- synchronization sampling method is analyzed by theory. The hardware system，which takes single-chip microcomputer as the core of data processing and logic control，completes data acquisition of voltage signal and current signal of the reactor. In the respect of software design，the impedance variation will be uploaded to the PC after it has been calculated by using the above monitoring method，and then monitoring of turn-to-turn short circuit fault will be realized. Finally，the design of on-line monitoring system is studied by testing. The research result shows that，the equivalent resistance increases and the equivalent reactance decreases when turn-to-turn short circuit occurs，and the variation of equivalent resistance is more obvious than equivalent reactance. The experiment results prove that this monitoring method is true and the on-line monitoring system is feasible.
International Nuclear Information System (INIS)
Yoetz-Kopelman, Tal; Ram, Yaron; Freeman, Amihay; Shacham-Diamand, Yosi
2015-01-01
The changes in the Faradaic impedance of gold/biomolecules system due to specific binding of small molecule to a significantly larger binding protein molecule were investigated. The biotin (244.31 Da) - avidin (66000 Da) couple was used as a model for small ligand - binding protein biorecognition. The study was carried out under open circuit potential in the presence of [Fe(CN) 6 ] −3/−4 redox couple. An equivalent electrical circuit was proposed and used for the interpretation of the recorded impedance spectra. Adsorption of thiolated avidin increased the electron transfer resistance, R ct , by a factor of about 7.5 while subsequent addition of biotin within the concentration range of 4.1-40.9 nM reduced the value of R ct by amount proportional to the biotin concentration. The addition of biotin did not affect, however, the equivalent double layer capacitance or other equivalent circuit parameters. A simple model based on effective surface coverage by the avidin molecules and the effect of the added biotin on electron transfer through the coated surface is proposed. A model for the minimum detection limit based on the random distribution of the binding protein and its dimensions is proposed
Small-signal Loudspeaker Impedance Emulator
DEFF Research Database (Denmark)
Knott, Arnold; Iversen, Niels Elkjær
2014-01-01
Specifying the performance of audio ampliers is typically done by playing sine waves into a pure ohmic load. However real loudspeaker impedances are not purely ohmic but characterised by the mechanical resonance between the mass of the diaphragm and the compliance of its' suspension which vary from...... driver to driver. Therefore a loudspeaker emulator capable of adjusting its' impedance to a given driver is in need for measurement purposes. This paper proposes a loudspeaker emulator circuit for small signals. Simulations and experimental results are compared and show that it is possible to emulate...... the loudspeaker impedance with an electric circuit and that its' resonance frequency can be changed by tuning two resistors....
Ochoa, Agustin
2016-01-01
This book describes a consistent and direct methodology to the analysis and design of analog circuits with particular application to circuits containing feedback. The analysis and design of circuits containing feedback is generally presented by either following a series of examples where each circuit is simplified through the use of insight or experience (someone else’s), or a complete nodal-matrix analysis generating lots of algebra. Neither of these approaches leads to gaining insight into the design process easily. The author develops a systematic approach to circuit analysis, the Driving Point Impedance and Signal Flow Graphs (DPI/SFG) method that does not require a-priori insight to the circuit being considered and results in factored analysis supporting the design function. This approach enables designers to account fully for loading and the bi-directional nature of elements both in the feedback path and in the amplifier itself, properties many times assumed negligible and ignored. Feedback circuits a...
Distance protection of multiple-circuit shared tower transmission lines with different voltages
DEFF Research Database (Denmark)
Silva, Filipe Miguel Faria da; Bak, Claus Leth
2017-01-01
combined faults, being advised to increase the resistive limit of the protection zone, if the network has lower short-circuit power. It is recommended to assure that the fault can only happen for cases where the faulted phase from the higher voltage level leads the faulted phase from the lower voltage......Multiple-circuit transmission lines combining different voltage levels in one tower present extra challenges when setting a protection philosophy, as faults between voltage levels are possible. In this study, the fault loop impedance of combined faults is compared with the fault loop impedance......-phase-to-ground faults. It is also demonstrated that the fault loop impedance of combined faults is more resistive, when compared with equivalent single-phase-to-ground faults. It is concluded that the settings used to protect a line against single-phase-to-ground faults are capable of protecting the line against...
Comments on field equivalence principles
DEFF Research Database (Denmark)
Appel-Hansen, Jørgen
1987-01-01
It is pointed Out that often-used arguments based on a short-circuit concept in presentations of field equivalence principles are not correct. An alternative presentation based on the uniqueness theorem is given. It does not contradict the results obtained by using the short-circuit concept...
Analysis and design of complex impedance transforming marchand baluns
DEFF Research Database (Denmark)
Michaelsen, Rasmus Schandorph; Johansen, Tom Keinicke; Tamborg, Kjeld M.
2014-01-01
A new type of Marchand balun is presented in this paper, which has the property of complex impedance transformation. To allow the Marchand balun to transform between arbitrary complex impedances, three reactances should be added to the circuit. A detailed analysis of the circuit gives the governing...
A Portable Impedance Immunosensing System for Rapid Detection of Salmonella Typhimurium.
Wen, Tao; Wang, Ronghui; Sotero, America; Li, Yanbin
2017-08-28
Salmonella Typhimurium is one of the most dangerous foodborne pathogens and poses a significant threat to human health. The objective of this study was to develop a portable impedance immunosensing system for rapid and sensitive detection of S . Typhimurium in poultry. The developed portable impedance immunosensing system consisted of a gold interdigitated array microelectrode (IDAM), a signal acquisitive interface and a laptop computer with LabVIEW software. The IDAM was first functionalized with 16-Mercaptohexadecanoic acid, and streptavidin was immobilized onto the electrode surface through covalent bonding. Then, biotin-labelled S . Typhimurium -antibody was immobilized onto the IDAM surface. Samples were dropped on the surface of the IDAM and the S . Typhimurium cells in the samples were captured by the antibody on the IDAM. This resulted in impedance changes that were measured and displayed with the LabVIEW software. An equivalent circuit of the immunosensor demonstrated that the largest change in impedance was due to the electron-transfer resistance. The equivalent circuit showed an increase of 35% for the electron-transfer resistance value compared to the negative control. The calibration result indicated that the portable impedance immunosensing system could be used to measure the standard impedance elements, and it had a maximum error of measurement of approximately 13%. For pure culture detection, the system had a linear relationship between the impedance change and the logarithmic value of S . Typhimurium cells ranging from 76 to 7.6 × 10⁶ CFU (colony-forming unit) (50 μL) -1 . The immunosensor also had a correlation coefficient of 0.98, and a high specificity for detection of S . Typhimurium cells with a limit of detection (LOD) of 10² CFU (50 μL) -1 . The detection time from the moment a sample was introduced to the display of the results was 1 h. To conclude, the portable impedance immunosensing system for detection of S . Typhimurium achieved
A Portable Impedance Immunosensing System for Rapid Detection of Salmonella Typhimurium
Directory of Open Access Journals (Sweden)
Tao Wen
2017-08-01
Full Text Available Salmonella Typhimurium is one of the most dangerous foodborne pathogens and poses a significant threat to human health. The objective of this study was to develop a portable impedance immunosensing system for rapid and sensitive detection of S. Typhimurium in poultry. The developed portable impedance immunosensing system consisted of a gold interdigitated array microelectrode (IDAM, a signal acquisitive interface and a laptop computer with LabVIEW software. The IDAM was first functionalized with 16-Mercaptohexadecanoic acid, and streptavidin was immobilized onto the electrode surface through covalent bonding. Then, biotin-labelled S. Typhimurium-antibody was immobilized onto the IDAM surface. Samples were dropped on the surface of the IDAM and the S. Typhimurium cells in the samples were captured by the antibody on the IDAM. This resulted in impedance changes that were measured and displayed with the LabVIEW software. An equivalent circuit of the immunosensor demonstrated that the largest change in impedance was due to the electron-transfer resistance. The equivalent circuit showed an increase of 35% for the electron-transfer resistance value compared to the negative control. The calibration result indicated that the portable impedance immunosensing system could be used to measure the standard impedance elements, and it had a maximum error of measurement of approximately 13%. For pure culture detection, the system had a linear relationship between the impedance change and the logarithmic value of S. Typhimurium cells ranging from 76 to 7.6 × 106 CFU (colony-forming unit (50 μL−1. The immunosensor also had a correlation coefficient of 0.98, and a high specificity for detection of S. Typhimurium cells with a limit of detection (LOD of 102 CFU (50 μL−1. The detection time from the moment a sample was introduced to the display of the results was 1 h. To conclude, the portable impedance immunosensing system for detection of S. Typhimurium
Directory of Open Access Journals (Sweden)
Viswanath eSankar
2014-05-01
Full Text Available Changes in biotic and abiotic factors can be reflected in the complex impedance spectrum of the microelectrodes chronically implanted into the neural tissue. The recording surface of the tungsten electrode in vivo undergoes abiotic changes due to recording site corrosion and insulation delamination as well as biotic changes due to tissue encapsulation as a result of the foreign body immune response. We reported earlier that large changes in electrode impedance measured at 1 kHz were correlated with poor electrode functional performance, quantified through electrophysiological recordings during the chronic lifetime of the electrode. There is a need to identity the factors that contribute to the chronic impedance variation. In this work, we use numerical simulation and regression to equivalent circuit models to evaluate both the abiotic and biotic contributions to the impedance response over chronic implant duration. COMSOL® simulation of abiotic electrode morphology changes provide a possible explanation for the decrease in the electrode impedance at long implant duration while biotic changes play an important role in the large increase in impedance observed initially.
Energy Technology Data Exchange (ETDEWEB)
Niedermayer, U., E-mail: u.niedermayer@gsi.de [Technische Universitaet Darmstadt, Institut fuer Theorie Elektromagnetischer Felder, Schlossgartenstrasse 8, 64289 Darmstadt (Germany); Boine-Frankenheim, O. [Technische Universitaet Darmstadt, Institut fuer Theorie Elektromagnetischer Felder, Schlossgartenstrasse 8, 64289 Darmstadt (Germany)
2012-09-21
The resistive wall impedance is one of the main sources for beam instabilities in synchrotrons and storage rings. The fast ramped SIS18 synchrotron at GSI and the projected SIS100 synchrotron for FAIR both employ thin (0.3 mm) stainless steel beam pipes in order to reduce eddy current effects. The lowest betatron sidebands are at about 100 kHz, which demands accurate impedance predictions in the low frequency (LF) range where the beam pipe and possibly also the structures behind the pipe are the dominating impedance sources. The longitudinal and transverse resistive wall impedances of a circular multi-layer pipe are calculated analytically using the field matching technique. We compare the impedances obtained from a radial wave model, which corresponds to the setup used in bench measurements, with the axial wave model, which corresponds to an actual beam moving with relativistic velocity. For thin beam pipes the induced wall current and the corresponding shielding properties of the pipe are important. In both models the wall current is obtained analytically. The characteristic frequencies for the onset of the wall current are calculated from equivalent lumped element circuits corresponding to the radial model. For more complex structures, like the SIS100 beam pipe, we use a numerical method, in which the impedance is obtained from the total power loss. The method is validated by the analytic expressions for circular beam pipes.
Bias-dependent model of the electrical impedance of ionic polymer-metal composites.
Cha, Youngsu; Porfiri, Maurizio
2013-02-01
In this paper, we analyze the charge dynamics of ionic polymer-metal composites (IPMCs) in response to voltage inputs composed of a large dc bias and a small superimposed time-varying voltage. The IPMC chemoelectrical behavior is described through the modified Poisson-Nernst-Planck framework, in which steric effects are taken into consideration. The physics of charge build-up and mass transfer in the proximity of the high surface electrodes is modeled by schematizing the IPMC as the stacked sequence of five layers, in which the ionomeric membrane is separated from the metal electrodes by two composite layers. The method of matched asymptotic expansions is used to derive a semianalytical solution for the concentration of mobile counterions and the electric potential in the IPMC, which is, in turn, used to establish an equivalent circuit model for the IPMC electrical response. The circuit model consists of the series connection of a resistor and two complex elements, each constituted by the parallel connection of a capacitor and a Warburg impedance. The resistor is associated with ion transport in the ionomeric membrane and is independent of the dc bias. The capacitors and the Warburg impedance idealize charge build-up and mass transfer in the vicinity of the electrodes and their value is controlled by the dc bias. The proposed approach is validated against experimental results on in-house fabricated IPMCs and the accuracy of the equivalent circuit is assessed through comparison with finite element results.
Electrical characterization and impedance response of lanthanum doped barium titanate ceramics
Directory of Open Access Journals (Sweden)
Mančić D.
2008-01-01
Full Text Available The dielectric permittivity and dissipation factor of La-doped and undoped BaTiO3 were investigated as a function of frequency and temperature. The impedance response was used to study the electrical properties of La-doped BaTiO3 over the temperature range from room temperature (RT to 350°C. La-doped and undoped BaTiO3, obtained by a modified Pechini method, were sintered in air at 1300°C for 2 and 16 hours. The impedance spectra were analyzed in terms of equivalent circuits involving resistors, capacitors and constant phase elements (CPE. The most suitable electrical circuit for the interpretation of experimental results is found to be the equivalent circuit consisting of resistors and CPE elements which replace the capacitor elements. The contribution of grain boundary resistance to the total resistance of a system is remarkable at low temperature. Dielectric permittivity of doped BaTiO3 was in the range of 8000 to 12000 at 1 kHz and the dissipation factor was less than 1%.
Dielectric and impedance spectroscopic studies of neodymium gallate
Energy Technology Data Exchange (ETDEWEB)
Sakhya, Anup Pradhan, E-mail: npshakya31@gmail.com [Department of Physics, Bose Institute, 93/1 Acharya Prafulla Chandra Road, Kolkata 700009 (India); Dutta, Alo [Department of Condensed Matter Physics and Material Sciences, S. N. Bose National Centre for Basic Sciences, Block-JD, Sector-III, Salt Lake, Kolkata 700098 (India); Sinha, T.P. [Department of Physics, Bose Institute, 93/1 Acharya Prafulla Chandra Road, Kolkata 700009 (India)
2016-05-01
The AC electrical properties of a polycrystalline neodymium gallate, NdGaO{sub 3} (NGO), synthesized by the sol–gel method have been investigated by employing impedance spectroscopy in the frequency range from 42 Hz to 5 MHz and in the temperature range from 323 K to 593 K. The X-ray diffraction analysis shows that the compound crystallizes in the orthorhombic phase with Pbnm space group at room temperature. Two relaxation processes with different relaxation times are observed from the impedance as well as modulus spectroscopic measurements, which have been attributed to the grain and the grain boundary effects at different temperatures in NGO. The complex impedance data are analyzed by an electrical equivalent circuit consisting of a resistance and a constant phase element in parallel. It has been observed that the value of the capacitance and the resistance associated with the grain boundary is higher than those associated with the grain. The temperature dependent electrical conductivity shows the negative temperature coefficient of resistance. The frequency dependent conductivity spectra are found to follow the power law.
NOTE: Impedance magnetocardiogram
Kandori, Akihiko; Miyashita, Tsuyoshi; Suzuki, Daisuke; Yokosawa, Koichi; Tsukada, Keiji
2001-02-01
We have developed an impedance magnetocardiogram (IMCG) system to detect the change of magnetic field corresponding to changes in blood volume in the heart. A low magnetic field from the electrical activity of the human heart - the so-called magnetocardiogram (MCG) - can be simultaneously detected by using this system. Because the mechanical and electrical functions in the heart can be monitored by non-invasive and non-contact measurements, it is easy to observe the cardiovascular functions from an accurate sensor position. This system uses a technique to demodulate induced current in a subject. A flux-locked circuit of a superconducting quantum interference device has a wide frequency range (above 1 MHz) because a constant current (40 kHz) is fed through the subject. It is shown for the first time that the system could measure IMCG signals at the same time as MCG signals.
International Nuclear Information System (INIS)
Allafi, Walid; Uddin, Kotub; Zhang, Cheng; Mazuir Raja Ahsan Sha, Raja; Marco, James
2017-01-01
Highlights: •Off-line estimation approach for continuous-time domain for non-invertible function. •Model reformulated to multi-input-single-output; nonlinearity described by sigmoid. •Method directly estimates parameters of nonlinear ECM from the measured-data. •Iterative on-line technique leads to smoother convergence. •The model is validated off-line and on-line using NCA battery. -- Abstract: The accuracy of identifying the parameters of models describing lithium ion batteries (LIBs) in typical battery management system (BMS) applications is critical to the estimation of key states such as the state of charge (SoC) and state of health (SoH). In applications such as electric vehicles (EVs) where LIBs are subjected to highly demanding cycles of operation and varying environmental conditions leading to non-trivial interactions of ageing stress factors, this identification is more challenging. This paper proposes an algorithm that directly estimates the parameters of a nonlinear battery model from measured input and output data in the continuous time-domain. The simplified refined instrumental variable method is extended to estimate the parameters of a Wiener model where there is no requirement for the nonlinear function to be invertible. To account for nonlinear battery dynamics, in this paper, the typical linear equivalent circuit model (ECM) is enhanced by a block-oriented Wiener configuration where the nonlinear memoryless block following the typical ECM is defined to be a sigmoid static nonlinearity. The nonlinear Weiner model is reformulated in the form of a multi-input, single-output linear model. This linear form allows the parameters of the nonlinear model to be estimated using any linear estimator such as the well-established least squares (LS) algorithm. In this paper, the recursive least square (RLS) method is adopted for online parameter estimation. The approach was validated on experimental data measured from an 18650-type Graphite
International Nuclear Information System (INIS)
Hojman, S.
1982-01-01
We present a review of the inverse problem of the Calculus of Variations, emphasizing the ambiguities which appear due to the existence of equivalent Lagrangians for a given classical system. In particular, we analyze the properties of equivalent Lagrangians in the multidimensional case, we study the conditions for the existence of a variational principle for (second as well as first order) equations of motion and their solutions, we consider the inverse problem of the Calculus of Variations for singular systems, we state the ambiguities which emerge in the relationship between symmetries and conserved quantities in the case of equivalent Lagrangians, we discuss the problems which appear in trying to quantize classical systems which have different equivalent Lagrangians, we describe the situation which arises in the study of equivalent Lagrangians in field theory and finally, we present some unsolved problems and discussion topics related to the content of this article. (author)
DEFF Research Database (Denmark)
Sahlin, Simon Lennart; Simon Araya, Samuel; Andreasen, Søren Juhl
2017-01-01
their effects on a reformate-operated stack. Polarization curves were also recorded to complement the impedance analysis of the researched phenomena. An equivalent circuit model was used to estimate the different resistances at varying parameters. It showed a significantly higher low frequency resistance......, λanode= 1.6 for reformate operation and λcathode= 4.The work also compared dry hydrogen, steam reforming and autothermal reforming gas feeds at160 ◦Cand showed appreciably lower performance in the case of autothermal reforming at the same stoichiometry, mainly attributable to mass transport related...
Loudspeaker impedance emulator for multi resonant systems
DEFF Research Database (Denmark)
Iversen, Niels Elkjær; Knott, Arnold
2015-01-01
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 characterised by its electrical, mechanical and acoustical properties. Therefore a loudspeaker emulator capable of adjusting...... its impedance to that of a given loudspeaker is desired for measurement purposes. An adjustable RLC based emulator is implemented with switch controlled capacitors, air gap controlled inductors and potentiometers. Calculations and experimental results are compared and show that it is possible...... to emulate the loudspeaker impedance infinite baffle-, closed box- and the multi resonant vented box-loudspeaker by tuning the component values in the proposed circuit. Future work is outlined and encourage that the proposed impedance emulator is used as part of a control circuit in a switch-mode based...
Electrochemical impedance spectroscopy: An effective tool for a fast microbiological diagnosis
International Nuclear Information System (INIS)
Ramirez, Nardo; Regueiro, Angel; Arias, Olimpia; Contreras, Rolando
2009-01-01
Dielectric spectroscopy, also called electrochemical impedance spectroscopy, is traditionally used in monitoring corrosion and electro-deposition processes in the coating and characterization assessment of many kinds of sensors and semi-conductors. Its application in biotechnology for the characterization of cell cultures has, however, been notably expanded in the last decade. As a transductional principle, impedance has been applied in the field of microbiology as a means of detecting and quantifying pathogenic bacteria. This paper reviews the state-of-the-art of Impedance Microbiology, its progress and its applications for the detection of foodborne pathogenic bacteria, including the use of interdigitated microelectrodes, the development of chip-based impedance microbiology and the integration of impedance biosensors along with other techniques such as dielectrophoresis and electropermeabilization. Reference is made to basic components, definitions and principles of this technique, as well as to the explanation of the components and principles for cell culture design and the use of equivalent circuits for the analysis of the systems based on this alternative. (Author)
Process modeling of the impedance characteristics of proton exchange membrane fuel cells
International Nuclear Information System (INIS)
Rezaei Niya, Seyed Mohammad; Phillips, Ryan K.; Hoorfar, Mina
2016-01-01
Highlights: • The impedance of the PEM fuel cell is analytically calculated. • The measured impedances are presented for different operating conditions. • The high frequency arc in the measured Nyquist plot is related to the anode. • The intermediate frequency arc is related to the cathode. • The low frequency arc and high frequency resistance are related to the membrane. - Abstract: A complete process modeling of the impedance characteristics of the proton exchange membrane fuel cells is presented. The impedance of the cell is determined analytically and the resultant equivalent circuit is calculated. The model predictions are then compared against the measured impedances in different current densities, operating temperatures and anode and cathode relative humidities. It is shown that the model predicts the Nyquist plots in all different operating conditions extremely well. Next, the trends observed in the Nyquist plots reported in the literature are compared against the model predictions. The result of this comparison confirms the accuracy of the model. Using the verified model, various arcs in the Nyquist plots are separated and related to the fuel cell physical parameters.
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.
Electrochemical impedance spectroscopy of oxidized porous silicon
Energy Technology Data Exchange (ETDEWEB)
Mula, Guido, E-mail: guido.mula@unica.it [Dipartimento di Fisica, Università degli Studi di Cagliari, Cittadella Universitaria di Monserrato, S.P. 8 km 0.700, 09042 Cagliari (Italy); Tiddia, Maria V. [Dipartimento di Fisica, Università degli Studi di Cagliari, Cittadella Universitaria di Monserrato, S.P. 8 km 0.700, 09042 Cagliari (Italy); Ruffilli, Roberta [Nanochemistry, Istituto Italiano di Tecnologia, Via Morego 30, 16163 Genova (Italy); Falqui, Andrea [Nanochemistry, Istituto Italiano di Tecnologia, Via Morego 30, 16163 Genova (Italy); Dipartimento di Scienze Chimiche e Geologiche, Università degli Studi di Cagliari, Cittadella Universitaria di Monserrato, S.P. 8 km 0.700, 09042 Cagliari (Italy); Palmas, Simonetta; Mascia, Michele [Dipartimento di Ingegneria Meccanica Chimica e dei Materiali, Università degli Studi di Cagliari, Piazza d' Armi, 09126 Cagliari (Italy)
2014-04-01
We present a study of the electrochemical oxidation process of porous silicon. We analyze the effect of the layer thickness (1.25–22 μm) and of the applied current density (1.1–11.1 mA/cm{sup 2}, values calculated with reference to the external samples surface) on the oxidation process by comparing the galvanostatic electrochemical impedance spectroscopy (EIS) measurements and the optical specular reflectivity of the samples. The results of EIS were interpreted using an equivalent circuit to separate the contribution of different sample parts. A different behavior of the electrochemical oxidation process has been found for thin and thick samples: whereas for thin samples the oxidation process is univocally related to current density and thickness, for thicker samples this is no more true. Measurements by Energy Dispersive Spectroscopy using a Scanning Electron Microscopy confirmed that the inhomogeneity of the electrochemical oxidation process is increased by higher thicknesses and higher currents. A possible explanation is proposed to justify the different behavior of thin and thick samples during the electrochemical process. - Highlights: • A multidisciplinary approach on porous Si electrochemical oxidation is proposed. • Electrochemical, optical, and structural characterizations are used. • Layer thickness and oxidation current effects are shown. • An explanation of the observed behavior is proposed.
Sabah, Nassir H
2007-01-01
Circuit Variables and Elements Overview Learning Objectives Electric Current Voltage Electric Power and Energy Assigned Positive Directions Active and Passive Circuit Elements Voltage and Current Sources The Resistor The Capacitor The Inductor Concluding Remarks Summary of Main Concepts and Results Learning Outcomes Supplementary Topics on CD Problems and Exercises Basic Circuit Connections and Laws Overview Learning Objectives Circuit Terminology Kirchhoff's Laws Voltage Division and Series Connection of Resistors Current Division and Parallel Connection of Resistors D-Y Transformation Source Equivalence and Transformation Reduced-Voltage Supply Summary of Main Concepts and Results Learning Outcomes Supplementary Topics and Examples on CD Problems and Exercises Basic Analysis of Resistive Circuits Overview Learning Objectives Number of Independent Circuit Equations Node-Voltage Analysis Special Considerations in Node-Voltage Analysis Mesh-Current Analysis Special Conside...
Circuit simulation of exponential transmission line for petawatt Z-pinch plasma drivers
International Nuclear Information System (INIS)
Zeng Zhengzhong
2011-01-01
It was demonstrated, based on the PSPICE circuit simulation, that the sectioning number for the circuit simulation of an exponential transmission line should be determined as twice the line's one-way electromagnetic wave transport time(electric length) divided by the wave-front of input pulse, owing to elimination of the wave reflections caused by artificial impedance discontinuity in the line's circuit simulation model, which employs a serial and sectional transmission line with impedances constant in each section but stair-step-varied between sections, and with total electric length the same as that of the exponential line under simulation. A pulse of 112.2 ns wave-front propagates through an exponential water transmission line of 1 234.2 ns one-way transport time will give the best sectioning number of 22, when the constant impedance of each section is given by the geometric mean of the two ends' impedances of the corresponding section on the exponential line under simulation. This sectioning rule is equivalent to the statement that the two-way transport time of each section should be equal to the input pulse's wave-front. (authors)
International Nuclear Information System (INIS)
Zia, Asif I; Syaifudin, A R Mohd; Mukhopadhyay, S C; Yu, P L; Al-Bahadly, I H; Gooneratne, Chinthaka P; Kosel, Juergen; Liao, Tai-Shan
2013-01-01
Phthalate esters are ubiquitous environmental and food pollutants well known as endocrine disrupting compounds (EDCs). These developmental and reproductive toxicants pose a grave risk to the human health due to their unlimited use in consumer plastic industry. Detection of phthalates is strictly laboratory based time consuming and expensive process and requires expertise of highly qualified and skilled professionals. We present a real time, non-invasive, label free rapid detection technique to quantify phthalates' presence in deionized water and fruit juices. Electrochemical impedance spectroscopy (EIS) technique applied to a novel planar inter-digital (ID) capacitive sensor plays a vital role to explore the presence of phthalate esters in bulk fluid media. The ID sensor with multiple sensing gold electrodes was fabricated on silicon substrate using micro-electromechanical system (MEMS) device fabrication technology. A thin film of parylene C polymer was coated as a passivation layer to enhance the capacitive sensing capabilities of the sensor and to reduce the magnitude of Faradic current flowing through the sensor. Various concentrations, 0.002ppm through to 2ppm of di (2-ethylhexyl) phthalate (DEHP) in deionized water, were exposed to the sensing system by dip testing method. Impedance spectra obtained was analysed to determine sample conductance which led to consequent evaluation of its dielectric properties. Electro-chemical impedance spectrum analyser algorithm was employed to model the experimentally obtained impedance spectra. Curve fitting technique was applied to deduce constant phase element (CPE) equivalent circuit based on Randle's equivalent circuit model. The sensing system was tested to detect different concentrations of DEHP in orange juice as a real world application. The result analysis indicated that our rapid testing technique is able to detect the presence of DEHP in all test samples distinctively.
Zia, Asif I
2013-06-10
Phthalate esters are ubiquitous environmental and food pollutants well known as endocrine disrupting compounds (EDCs). These developmental and reproductive toxicants pose a grave risk to the human health due to their unlimited use in consumer plastic industry. Detection of phthalates is strictly laboratory based time consuming and expensive process and requires expertise of highly qualified and skilled professionals. We present a real time, non-invasive, label free rapid detection technique to quantify phthalates\\' presence in deionized water and fruit juices. Electrochemical impedance spectroscopy (EIS) technique applied to a novel planar inter-digital (ID) capacitive sensor plays a vital role to explore the presence of phthalate esters in bulk fluid media. The ID sensor with multiple sensing gold electrodes was fabricated on silicon substrate using micro-electromechanical system (MEMS) device fabrication technology. A thin film of parylene C polymer was coated as a passivation layer to enhance the capacitive sensing capabilities of the sensor and to reduce the magnitude of Faradic current flowing through the sensor. Various concentrations, 0.002ppm through to 2ppm of di (2-ethylhexyl) phthalate (DEHP) in deionized water, were exposed to the sensing system by dip testing method. Impedance spectra obtained was analysed to determine sample conductance which led to consequent evaluation of its dielectric properties. Electro-chemical impedance spectrum analyser algorithm was employed to model the experimentally obtained impedance spectra. Curve fitting technique was applied to deduce constant phase element (CPE) equivalent circuit based on Randle\\'s equivalent circuit model. The sensing system was tested to detect different concentrations of DEHP in orange juice as a real world application. The result analysis indicated that our rapid testing technique is able to detect the presence of DEHP in all test samples distinctively.
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.
Energy Technology Data Exchange (ETDEWEB)
Want, Basharat, E-mail: bawant@kashmiruniversity.ac.in; Bhat, Bilal Hamid; Ahmad, Bhat Zahoor
2015-04-05
Highlights: • The substitution of La affects the dielectric and magnetic properties of strontium hexaferrite. • The electric behaviour of the compound follows the Koop’s phenomenological theory. • The impedance study shows the role of grain boundaries to the electric properties of the compound. • The substitution of La to strontium hexaferrite reduces the resistive nature of grain boundaries. - Abstract: Lanthanum strontium hexaferrite Sr{sub 1−x}La{sub x}Fe{sub 12}O{sub 19} (x = 0, 0.08, 0.13 , 0.18) has been successfully synthesized by using citrate-precursor method and characterized by different techniques. The X-ray diffraction results revealed that the sample is crystalline in nature and is of single phase with the space group P63/mmc. The dielectric, conducting and impedance related studies have been carried out as a function of frequency and concentration of lanthanum in the frequency ranges of 20 Hz–3 MHz. Impedance studies were performed in the frequency domain to distinguish between bulk and grain boundary contributions of the material to the overall dielectric response. The electric response of the material was also modeled by an equivalent circuit and different circuit parameters were calculated. Magnetic characterization of the material was also performed and the effect of lanthanum concentration was studied. The hysteresis loop obtained from the magnetometer showed that with the increase of lanthanum concentration, the saturation magnetisation decreases while as coercivity increases.
Study on electrical impedance matching for broadband ultrasonic transducer
Energy Technology Data Exchange (ETDEWEB)
Kim, Geon Woo [University of Science and Technology, Daejeon (Korea, Republic of); Kim, Ki Bok [Korea Research Institute of Standards and Science, Center for Safety Measurement, Daejeon (Korea, Republic of); Baek, Kwang Sae [Elache Co., Busan (Korea, Republic of)
2017-02-15
Ultrasonic transducers with high resolution and resonant frequency are required to detect small defects (less than hundreds of μm) by ultrasonic testing. The resonance frequency and resolution of an ultrasonic transducer are closely related to the thickness of piezo-electric materials, backing materials, and the electric impedance matching technique. Among these factors, electrical impedance matching plays an important role because it can reduce the loss and reflection of ultrasonic energy differences in electrical impedance between an ultrasonic transducer and an ultrasonic defects detecting system. An LC matching circuit is the most frequently used electric matching method. It is necessary for the electrical impedance of an ultrasonic transducer to correspond to approximately 50 Ω to compensate the difference in electrical impedance between both connections. In this study, a 15 MHz immersion ultrasonic transducer was fabricated and an LC electrical impedance circuit was applied to that for having broad-band frequency characteristic.
Correlation between zirconium oxide impedance and corrosion behavior of Zr-Nb-Sn-Fe-Cu alloys
International Nuclear Information System (INIS)
Park, Sang Yoon; Lee, Myung Ho; Choi, Byoung Kwon; Jeong, Yong Hwan; Jung, Youn Ho
2001-01-01
To evaluate the correlation of Zr oxide impedance and corrosion behavior of Zr-Nb-Sn-Fe-Cu alloys, the corrosion behavior of the alloys was tested in the autoclave containing 70 ppm LiOH solution at 360 .deg. C. The characteristics of the oxide on the alloys were investigated by using the electrochemical impedance spectrosocpy (EIS) method. The corrosion resistance of the alloys was evaluated from the corrosion rate determined as a function of the concentration of Nb. The equivalent circuit of the oxide was composed on the base of the spectrum from EIS measurements on the oxide layers that had formed at pre-and post-transition regions on the curve of corrosion rate. By using the capacitance characteristics of the equivalent circuit, the thickness of impervious layer, it's electrical resistance and characteristics of space charge layer were evaluated. The corrosion characteristics of the Zr-Nb-Sn-Fe-Cu alloys were successfully explained by applying the EIS test results
Improved impedance transformation between microwave oscillator and Josephson junction series array
International Nuclear Information System (INIS)
Gutmann, P.; Vollmer, E.; Niemeyer, J.
1993-01-01
Superconducting microwave monolithic integrated circuits (S-MMIC), based on Josephson tunnel junctions, are a well-established tool to reproduce the volt at the highest level of accuracy. An external oscillator of a fixed frequency f supplies microwave energy through a waveguide to the S-MMIC. The wave changes its mode at a waveguide-antipodal finline-stripline taper before entering a series array stripline of up to 30 000 Josephson tunnel junctions and is dissipated as heat in a lossy stripline. Both striplines have a characteristic impedance Z of 2 to 5 Ω. An equivalent circuit is shown in figure 1. The oscillator is matched to the waveguide with a source resistance R G Z(waveguide) ∼ 550 Ω. The most critical part is the taper, which should work as a lossless impedance matching network at the frequency of the oscillator. Microwave energy is fed into the tunnel junctions by the surface current I HF of the travelling wave in the series array stripline producing an rf voltage amplitude U JHF across the capacitance C of each junction. The Josephson tunnel junctions work as self-oscillating parametric mixers producing steps of constant voltage V in the current-voltage characteristic whenever (nf - 2eV/h) = 0, with n denoting an integer and e and h denoting the elementary charge and Planck's constant, respectively. The equivalent circuit of a Josephson tunnel element used in a voltage standard for 1 V working at a frequency of f = 70 GHz is given by a lumped parallel resonant circuit with a nonlinear inductance on the order of L = φ 0 /2πI 0 ∼ 1 pH, flux quantum φ 0 = h/2e and a linear capacitance of C ∼ 40 pF. These tunnel junctions have a maximum zero voltage current of approximately I 0 ∼ 350 μA. (orig.)
Pivac, Ivan; Šimić, Boris; Barbir, Frano
2017-10-01
Representation of fuel cell processes by equivalent circuit models, involving resistance and capacitance elements representing activation losses on both anode and cathode in series with resistance representing ohmic losses, cannot capture and explain the inductive loop that may show up at low frequencies in Nyquist diagram representation of the electrochemical impedance spectra. In an attempt to explain the cause of the low-frequency inductive loop and correlate it with the processes within the fuel cell electrodes, a novel equivalent circuit model of a Proton Exchange Membrane (PEM) fuel cell has been proposed and experimentally verified here in detail. The model takes into account both the anode and the cathode, and has an additional resonant loop on each side, comprising of a resistance, capacitance and inductance in parallel representing the processes within the catalyst layer. Using these additional circuit elements, more accurate and better fits to experimental impedance data in the wide frequency range at different current densities, cell temperatures, humidity of gases, air flow stoichiometries and backpressures were obtained.
Directory of Open Access Journals (Sweden)
Amador M. González
2016-01-01
Full Text Available Electronic devices using the piezoelectric effect contain piezoelectric materials: often crystals, but in many cases poled ferroelectric ceramics (piezoceramics, polymers or composites. On the one hand, these materials exhibit non-negligible losses, not only dielectric, but also mechanical and piezoelectric. In this work, we made simulations of the effect of the three types of losses in piezoelectric materials on the impedance spectrum at the resonance. We analyze independently each type of loss and show the differences among them. On the other hand, electrical and electronic engineers include piezoelectric sensors in electrical circuits to build devices and need electrical models of the sensor element. Frequently, material scientists and engineers use different languages, and the characteristic material coefficients do not have a straightforward translation to those specific electrical circuit components. To connect both fields of study, we propose the use of accurate methods of characterization from impedance measurements at electromechanical resonance that lead to determination of all types of losses, as an alternative to current standards. We introduce a simplified equivalent circuit model with electrical parameters that account for piezoceramic losses needed for the modeling and design of industrial applications.
Directory of Open Access Journals (Sweden)
M. Fall
2006-12-01
Full Text Available 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 properties studied by cyclic voltammetry. Impedance spectra were obtained at potentials ranging from 0 to 0.8 V/SCE. The EIS data were fitted using two different equivalent electrical circuits (depending on the nature of the dopant. They involve a diffusive capacitance, which increased with the passing charge during electrosynthesis (i.e. film thickness for ClO4--doped PPy, but was practically unaffected by the film thickness in the case of SDS-doped PPy. Also, a double-layer capacitance was found only in the circuit of ClO4--doped PPy. It increased with the film thickness, and showed a minimum near the open-circuit potential. Finally the charge-transfer resistance (Rct obtained with SDS is nearly 200-fold higher than that obtained with ClO4- in the same solvent (H2O. With the same dopant (ClO4-, Rct is about five times higher in acetonitrile relative to water. All these EIS results of the different types of PPy suggest a relation with the wettability of the polymer.
González, Amador M; García, Álvaro; Benavente-Peces, César; Pardo, Lorena
2016-01-26
Electronic devices using the piezoelectric effect contain piezoelectric materials: often crystals, but in many cases poled ferroelectric ceramics (piezoceramics), polymers or composites. On the one hand, these materials exhibit non-negligible losses, not only dielectric, but also mechanical and piezoelectric. In this work, we made simulations of the effect of the three types of losses in piezoelectric materials on the impedance spectrum at the resonance. We analyze independently each type of loss and show the differences among them. On the other hand, electrical and electronic engineers include piezoelectric sensors in electrical circuits to build devices and need electrical models of the sensor element. Frequently, material scientists and engineers use different languages, and the characteristic material coefficients do not have a straightforward translation to those specific electrical circuit components. To connect both fields of study, we propose the use of accurate methods of characterization from impedance measurements at electromechanical resonance that lead to determination of all types of losses, as an alternative to current standards. We introduce a simplified equivalent circuit model with electrical parameters that account for piezoceramic losses needed for the modeling and design of industrial applications.
Yoon-Ho Kim; Jung-Hyeon Ryu; Jin-Hwan Kim; Kern-Joong Kim
2016-01-01
The equivalent test circuit that can deliver both short-circuit current and recovery voltage is used to verify the performance of high-voltage circuit breakers. Most of the parameters in this circuit can be obtained by using a simple calculation or a simulation program. The ratings of the circuit breaker include rated short-circuit breaking current, rated short-circuit making current, rated operating sequence of the circuit breaker and rated short-time current. Among these ratings, the short-...
Investigation of body's impedance under different conditions for electro-acupuncture
International Nuclear Information System (INIS)
Ahmed, M.M.; Abrarov, S.; Khan, R.R.; Maqsood, R.S.; Qaiser, M.A.; Karimov, Kh. S.
2001-01-01
A computer controlled automated setup has been designed to investigate the body acupuncture points (bio-active points) by using a probes matrix which exerts a uniform pressure on the body. 16 probes matrix was placed in a 15 : 15 mm/sup 2/ dielectric substrate with 5 mm inter probe distance, compatible with the average diameter of the points. These probes have been designed to facilitate a semiconductor injection laser for probing of the points along with optical and/or electric signal. The bioactive points were identified by evaluating the impedance between each probe and a hand held electrode through a micro-controlled scan. This also allowed the selection of an appropriate signal - DC, AC or tidal waveform, for the electric treatment of bioactive points. It has been found that body impedance decreases with the increase of measuring voltage. Moreover, for current-voltage characteristics a nonlinearity coefficient in the range 2-3 was also observed. The study revealed that at low applied voltages 0.l V, the impedance depends on the polarity of the applied signal. Furthermore, body impedance decreases nonlinearly by increasing the probe's pressure on the skin, which may be attributed to piezo resistive effect. By using the AC and Dc measurements an appropriate body equivalent circuit is proposed in this investigation. (author)
Dynamic impedance model of the skin-electrode interface for transcutaneous electrical stimulation.
Directory of Open Access Journals (Sweden)
José Luis Vargas Luna
Full Text Available Transcutaneous electrical stimulation can depolarize nerve or muscle cells applying impulses through electrodes attached on the skin. For these applications, the electrode-skin impedance is an important factor which influences effectiveness. Various models describe the interface using constant or current-depending resistive-capacitive equivalent circuit. Here, we develop a dynamic impedance model valid for a wide range stimulation intensities. The model considers electroporation and charge-dependent effects to describe the impedance variation, which allows to describe high-charge pulses. The parameters were adjusted based on rectangular, biphasic stimulation pulses generated by a stimulator, providing optionally current or voltage-controlled impulses, and applied through electrodes of different sizes. Both control methods deliver a different electrical field to the tissue, which is constant throughout the impulse duration for current-controlled mode or have a very current peak for voltage-controlled. The results show a predominant dependence in the current intensity in the case of both stimulation techniques that allows to keep a simple model. A verification simulation using the proposed dynamic model shows coefficient of determination of around 0.99 in both stimulation types. The presented method for fitting electrode-skin impedance can be simple extended to other stimulation waveforms and electrode configuration. Therefore, it can be embedded in optimization algorithms for designing electrical stimulation applications even for pulses with high charges and high current spikes.
International Nuclear Information System (INIS)
Chang, Fu-Yu; Chen, Ming-Kun; Jang, Ling-Sheng; Wang, Min-Haw
2016-01-01
Cell impedance analysis is widely used for monitoring biological and medical reactions. In this study, a highly sensitive three-dimensional (3D) interdigitated microelectrode (IME) with a high aspect ratio on a polyimide (PI) flexible substrate was fabricated for microparticle detection (e.g. cell quantity detection) using electroforming and lithography technology. 3D finite element simulations were performed to compare the performance of the 3D IME (in terms of sensitivity and signal-to-noise ratio) to that of a planar IME for particles in the sensing area. Various quantities of particles were captured in Dulbecco’s modified Eagle medium and their impedances were measured. With the 3D IME, the particles were arranged in the gap, not on the electrode, avoiding the noise due to particle position. For the maximum particle quantities, the results show that the 3D IME has at least 5-fold higher sensitivity than that of the planar IME. The trends of impedance magnitude and phase due to particle quantity were verified using the equivalent circuit model. The impedance (1269 Ω) of 69 particles was used to estimate the particle quantity (68 particles) with 98.6% accuracy using a parabolic regression curve at 500 kHz. (paper)
International Nuclear Information System (INIS)
Parra, Felix I; Catto, Peter J
2009-01-01
We compare two different derivations of the gyrokinetic equation: the Hamiltonian approach in Dubin D H E et al (1983 Phys. Fluids 26 3524) and the recursive methodology in Parra F I and Catto P J (2008 Plasma Phys. Control. Fusion 50 065014). We prove that both approaches yield the same result at least to second order in a Larmor radius over macroscopic length expansion. There are subtle differences in the definitions of some of the functions that need to be taken into account to prove the equivalence.
International Nuclear Information System (INIS)
Forsberg, Stefan; Ahlberg, Elisabet; Andersson, Ulf
2004-09-01
The corrosion of three Zircaloy 2 cladding materials, LK2, LK2+ and LK3, have been studied in-situ in an autoclave using electrochemical impedance spectroscopy. Measurements were performed in simulated BWR water at temperatures up to 288 deg C. The impedance spectra were successfully modelled using equivalent circuits. When the oxide grew thicker during the experiments, a change-over from one to two time constants was seen, showing that a layered structure was formed. Oxide thickness, oxide conductivity and effective donor density were evaluated from the impedance data. The calculated oxide thickness at the end of the experiments was consistent with the value obtained from SEM. It was shown that the difference in oxide growth rate between the investigated materials is small in the pre-transition region. The effective donor density, which is a measure of electronic conductivity, was found to be lower for the LK3 material compared to the other two materials
Graf, Rudolf F
1996-01-01
This series of circuits provides designers with a quick source for oscillator circuits. Why waste time paging through huge encyclopedias when you can choose the topic you need and select any of the specialized circuits sorted by application?This book in the series has 250-300 practical, ready-to-use circuit designs, with schematics and brief explanations of circuit operation. The original source for each circuit is listed in an appendix, making it easy to obtain additional information.Ready-to-use circuits.Grouped by application for easy look-up.Circuit source listing
Graf, Rudolf F
1996-01-01
This series of circuits provides designers with a quick source for measuring circuits. Why waste time paging through huge encyclopedias when you can choose the topic you need and select any of the specialized circuits sorted by application?This book in the series has 250-300 practical, ready-to-use circuit designs, with schematics and brief explanations of circuit operation. The original source for each circuit is listed in an appendix, making it easy to obtain additional information.Ready-to-use circuits.Grouped by application for easy look-up.Circuit source listings
Determination of SoH of Lead-Acid Batteries by Electrochemical Impedance Spectroscopy
Directory of Open Access Journals (Sweden)
Monika Kwiecien
2018-05-01
Full Text Available The aging mechanisms of lead-acid batteries change the electrochemical characteristics. For example, sulfation influences the active surface area, and corrosion increases the resistance. Therefore, it is expected that the state of health (SoH can be reflected through differentiable changes in the impedance of a lead-acid battery. However, for lead-acid batteries, no reliable SoH algorithm is available based on single impedance values or the spectrum. Additionally, the characteristic changes of the spectrum during aging are unknown. In this work, lead-acid test cells were aged under specific cycle regimes known as AK3.4, and periodic electrochemical impedance spectroscopy (EIS measurements and capacity tests were conducted. It was examined that single impedance values increased linearly with capacity decay, but with varying slopes depending on the pre-history of the cell and measurement frequency of impedance. Thereby, possible reasons for ineffective SoH estimation were found. The spectra were fitted to an equivalent electrical circuit containing, besides other elements, an ohmic and a charge-transfer resistance of the negative electrode. The linear increase of the ohmic resistance and the charge-transfer resistance were characterized for the performed cyclic aging test. Results from chemical analysis confirmed the expected aging process and the correlation between capacity decay and impedance change. Furthermore, the positive influence of charging on the SoH could be detected via EIS. The results presented here show that SoH estimation using EIS can be a viable technique for lead-acid batteries.
Directory of Open Access Journals (Sweden)
Maria Mallén-Alberdi
2016-03-01
Full Text Available Impedance-based biosensors for bacterial detection offer a rapid and cost-effective alternative to conventional techniques that are time-consuming and require specialized equipment and trained users. In this work, a new bacteria detection scheme is presented based on impedance measurements with antibody-modified polysilicon interdigitated electrodes (3 μm pitch, IDEs. The detection approach was carried out taking advantage of the E. coli structure which, in electrical terms, is constituted by two insulating cell membranes that separate a conductive cytoplasmatic medium and a more conductive periplasm. Impedance detection of bacteria is usually analyzed using electrical equivalent circuit models that show limitations for the interpretation of such complex cell structure. Here, a differential impedance spectrum representation is used to study the unique fingerprint that arises when bacteria attach to the surface of IDEs. That fingerprint shows the dual electrical behavior, insulating and conductive, at different frequency ranges. In parallel, finite-element simulations of this system using a three-shell bacteria model are performed to explain such phenomena. Overall, a new approach to detect bacteria is proposed that also enables to differentiate viable bacteria from other components non-specifically attached to the IDE surface by just detecting their spectral fingerprints. Keywords: Impedance spectroscopy, Bacterial detection, Interdigitated electrodes, Label-free detection, Immuno-detection, E. coli O157:H7
Tracking of electrochemical impedance of batteries
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.
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
Impedance spectroscopy of CdTe thin film solar cells
Energy Technology Data Exchange (ETDEWEB)
Weiss, Charlotte; Heisler, Christoph; Reisloehner, Udo; Ronning, Carsten; Wesch, Werner [Institute of Solid State Physics, University of Jena, Max-Wien-Platz 1, D-07743 Jena (Germany)
2012-07-01
Impedance Spectroscopy (IS) is a widely used method to analyze dielectric properties of specimen as a function of frequency. Typically this characterization method delivers an equivalent circuit diagram of the device under examination to describe its electrical properties. Traditionally IS is used in coating evaluation, corrosion monitoring and in electrochemistry. During the last years the method became more important also in the field of electrical characterization of solar cells. In our work we use IS for the electrical characterization of thin film CdTe solar cells. The measurement is done at room temperature without illumination in a frequency domain from 20 Hz to 2 MHz. The samples are measured under variable forward bias. The results match insufficiently with the model of two resistor-capacitor circuits in series which is commonly used to describe the p-n junction and the blocking back contact. For better consistency, other models from the literature are used and discussed. From the results a conclusion is drawn about the properties of the solar cell such as the nature of the p-n junction or the performance of the back contact.
Empirical Modeling of Lithium-ion Batteries Based on Electrochemical Impedance Spectroscopy Tests
International Nuclear Information System (INIS)
Samadani, Ehsan; Farhad, Siamak; Scott, William; Mastali, Mehrdad; Gimenez, Leonardo E.; Fowler, Michael; Fraser, Roydon A.
2015-01-01
Highlights: • Two commercial Lithium-ion batteries are studied through HPPC and EIS tests. • An equivalent circuit model is developed for a range of operating conditions. • This model improves the current battery empirical models for vehicle applications • This model is proved to be efficient in terms of predicting HPPC test resistances. - ABSTRACT: An empirical model for commercial lithium-ion batteries is developed based on electrochemical impedance spectroscopy (EIS) tests. An equivalent circuit is established according to EIS test observations at various battery states of charge and temperatures. A Laplace transfer time based model is developed based on the circuit which can predict the battery operating output potential difference in battery electric and plug-in hybrid vehicles at various operating conditions. This model demonstrates up to 6% improvement compared to simple resistance and Thevenin models and is suitable for modeling and on-board controller purposes. Results also show that this model can be used to predict the battery internal resistance obtained from hybrid pulse power characterization (HPPC) tests to within 20 percent, making it suitable for low to medium fidelity powertrain design purposes. In total, this simple battery model can be employed as a real-time model in electrified vehicle battery management systems
Energy Technology Data Exchange (ETDEWEB)
Xiao, Y.P.; Liu, X.Y.; He, Y.B.; Li, C.L. [School of Materials Science and Engineering, Central South University, Changsha (China); Pan, Q.L. [School of Materials Science and Engineering, Central South University, Changsha (China); The Key Laboratory of Nonferrous Materials Science and Engineering of Ministry of Education, Changsha (China); Li, W.B. [School of Materials Science and Engineering, Central South University, Changsha (China); School of Civil Engineering, Hunan City University, Yiyang (China)
2012-02-15
The exfoliation corrosion behavior of an Al-Zn-Mg-Cu-Zr alloy containing Sc artificially aged at 120 C for 24 h is studied by macroscopic observation techniques and electrochemical impedance spectroscopy (EIS) measurements. After 48 h immersion, the blisters start bursting and delamination initiates, along with the appearance of two time constants in the impedance diagrams. According to the simulation by equivalent circuit, the corrosion rate decreases sharply and then reaches a steady state, which is due to the change of the solution pH and oxide layer thickness, as well as the accumulation of corrosion products. (Copyright copyright 2012 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim)
DEFF Research Database (Denmark)
Jeppesen, Christian; Polverino, Pierpaolo; Andreasen, Søren Juhl
2017-01-01
This work presents a comprehensive mapping of electrochemical impedance measurements under the influence of CO and methanol vapor contamination of the anode gas in a high temperature proton exchange membrane fuel cell, at varying load current. Electrical equivalent circuit model parameters based...... effects are similar for all the test cases, namely, CO alone, methanol alone and a mix of the two, suggesting that effects of methanol may include oxidation into CO on the catalyst layer....... on experimental evaluation of electrochemical impedance spectroscopy measurements were used to quantify the changes caused by different contamination levels. The changes are generally in good agreement with what is found in the literature. It is shown that an increased level of CO contamination resulted...
VISUALIZATION OF BIOLOGICAL TISSUE IMPEDANCE PARAMETERS
Directory of Open Access Journals (Sweden)
V. I. Bankov
2016-01-01
Full Text Available Objective. Investigation the opportunity for measurement of biological tissue impedance to visualize its parameters.Materials and methods. Studies were undertook on the experimental facility, consists of registrating measuring cell, constructed from flat inductors system, formed in oscillatory circuit, herewith investigated biological tissue is the part of this oscillatory circuit. An excitation of oscillatory circuit fulfilled by means of exciter inductor which forms impulse complex modulated electromagnetic field (ICM EMF. The measurement process and visualizations provided by set of certificated instruments: a digital oscillograph AKTAKOM ADS-2221MV, a digital generator АКТАКОМ AWG-4150 (both with software and a gauge RLC E7-22. Comparative dynamic studies of fixed volume and weight pig’s blood, adipose tissue, muscular tissue impedance were conducted by contact versus contactless methods. Contactless method in contrast to contact method gives opportunity to obtain the real morphological visualization of biological tissue irrespective of their nature.Results. Comparison of contact and contactless methods of impedance measurement shows that the inductance to capacitance ratio X(L / X(C was equal: 17 – for muscular tissue, 4 – for blood, 1 – for adipose tissue. It demonstrates the technical correspondence of both impedance registration methods. If propose the base relevance of X (L and X (C parameters for biological tissue impedance so contactless measurement method for sure shows insulating properties of adipose tissue and high conductivity for blood and muscular tissue in fixed volume-weight parameters. Registration of biological tissue impedance complex parameters by contactless method with the help of induced ICM EMF in fixed volume of biological tissue uncovers the most important informative volumes to characterize morphofunctional condition of biological tissue namely X (L / X (C.Conclusion. Contactless method of biological
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...... matrix approach and experimentally verified by synthesizing a 12-section nonsynchronous noncommensurate impedance transformer. The measured characteristics of the transformer are compared to the characteristics of a conventional tapered line transformer....
Coupled Transmission Lines as Impedance Transformer
DEFF Research Database (Denmark)
Jensen, Thomas; Zhurbenko, Vitaliy; Krozer, Viktor
2007-01-01
A theoretical investigation of the use of a coupled line section as an impedance transformer is presented. We show how to properly select the terminations of the coupled line structures for effective matching of real and complex loads in both narrow and wide frequency ranges. The corresponding...... circuit configurations and the design procedures are proposed. Synthesis relations are derived and provided for efficient matching circuit construction. Design examples are given to demonstrate the flexibility and limitations of the design methods and to show their validity for practical applications...
Choi, Wookjin; Inoue, Junichi; Tsutsui, Yusuke; Sakurai, Tsuneaki; Seki, Shu
2017-11-01
A unique concerted analysis comprising non-contact microwave conductivity measurements and impedance spectroscopy was developed to simultaneously assess the charge carrier mobility and injection barriers. The frequency dependence of the microwave conductivity as well as the electrical current was analyzed by applying sinusoidal voltage to determine the equivalent circuit parameters. Based on the temperature dependence of the circuit parameters, the energy of the injection barrier was estimated to be 0.4 eV with the Richardson-Schottky model, and the band-like transport was confirmed with the negative temperature coefficient with the β value of 1.4 in the intra-layer conduction of C8-BTBT. In contrast, the increase in the resistance of the C8-BTBT layer with decreasing temperature implied the occurrence of hopping-like transport in the inter-layer conduction of C8-BTBT.
Energy Technology Data Exchange (ETDEWEB)
Mora-Sero, Ivan; Luo, Yan; Garcia-Belmonte, Germa; Bisquert, Juan [Departament de Fisica, Universitat Jaume I, E-12071 Castello (Spain); Munoz, Delfina; Voz, Cristobal; Puigdollers, Joaquim; Alcubilla, Ramon [Departament d' Enginyeria Electronica, Universitat Politecnica de Catalunya, E-08034 Barcelona (Spain)
2008-04-15
Impedance spectroscopy (at forward bias and under illumination) of solar cells comprised thin hydrogenated amorphous silicon (a-Si:H) films deposited on crystalline silicon (c-Si) wafers was analyzed in terms of ac equivalent circuits. Shockley-Read-Hall recombination at states on the device interfaces governs the cell dynamic response. Recombination process was modeled by means of simple RC circuits which allow to determine the capture rate of electrons and holes. Carrier lifetime is found to be stated by the electron capture time {tau}{sub SRH}{approx}{tau}{sub n}, and it results in the range of 300 {mu}s. The Al-annealed back contact was regarded as the dominating recombination interface. (author)
Energy Technology Data Exchange (ETDEWEB)
Jlassi, I., E-mail: ifa.jlassi@fst.rnu.tn [Laboratoire Physico-chimie des Matériaux Minéraux et leurs Applications, Centre National de Recherches en Sciences des Matériaux, B.P. 95, Hammam-Lif 2050 (Tunisia); Département de Physique, Faculté des Sciences de Tunis, Université de Tunis ElManar, Campus Universitaire Farhat Hachad, ElManar 2092 (Tunisia); Sdiri, N. [Laboratoire Physico-chimie des Matériaux Minéraux et leurs Applications, Centre National de Recherches en Sciences des Matériaux, B.P. 95, Hammam-Lif 2050 (Tunisia); Elhouichet, H. [Laboratoire Physico-chimie des Matériaux Minéraux et leurs Applications, Centre National de Recherches en Sciences des Matériaux, B.P. 95, Hammam-Lif 2050 (Tunisia); Département de Physique, Faculté des Sciences de Tunis, Université de Tunis ElManar, Campus Universitaire Farhat Hachad, ElManar 2092 (Tunisia); Ferid, M. [Laboratoire Physico-chimie des Matériaux Minéraux et leurs Applications, Centre National de Recherches en Sciences des Matériaux, B.P. 95, Hammam-Lif 2050 (Tunisia)
2015-10-05
Highlights: • We have prepared a new lithium diphosphate glasses doped MgO. • Investigate structural and electrical properties at room temperature. • Investigate relation between structure and electrical conductivity of the glass. - Abstract: Lithium diphosphate glasses doped MgO was prepared via a melt quenching technique. The samples were characterized by X-ray diffraction (XRD), Raman and impedance spectroscopy. XRD spectra reflected the amorphous nature of the glasses Raman spectra show structural network modifications with the composition variations of the studied glasses. Raman spectra of the studied glasses contain also typical phosphate glasses bands. Thus the band at ∼698 cm{sup −1} assigned to symmetric stretching vibrations of P−O−P groups and that from ∼1168 cm{sup −1} is attributed to symmetric stretching motions of the non-bridging oxygen (NBO) atoms bonded to phosphorous atoms (PO{sub 2}) in phosphate tetrahedron. Electric properties were investigated using complex impedance spectroscopy in a frequency range from 40 Hz to 6 MHz at room temperature. The impedance spectra were analyzed in terms of equivalent circuits involving resistors, capacitors and constant phase elements (CPE). Constant-phase elements (CPE) are used in equivalent electrical circuits for the fitting of experimental impedance data. The AC conductivity exhibited a Jonscher’s universal power law according with the relation σ(ω) = σ(0) + Aω{sup s} and it is observed that as the MgO content increases, frequency exponent (s) decreases.
Rocha, Paulo R F; Schlett, Paul; Kintzel, Ulrike; Mailänder, Volker; Vandamme, Lode K J; Zeck, Gunther; Gomes, Henrique L; Biscarini, Fabio; de Leeuw, Dago M
2016-10-06
Microelectrode arrays (MEA) record extracellular local field potentials of cells adhered to the electrodes. A disadvantage is the limited signal-to-noise ratio. The state-of-the-art background noise level is about 10 μVpp. Furthermore, in MEAs low frequency events are filtered out. Here, we quantitatively analyze Au electrode/electrolyte interfaces with impedance spectroscopy and noise measurements. The equivalent circuit is the charge transfer resistance in parallel with a constant phase element that describes the double layer capacitance, in series with a spreading resistance. This equivalent circuit leads to a Maxwell-Wagner relaxation frequency, the value of which is determined as a function of electrode area and molarity of an aqueous KCl electrolyte solution. The electrochemical voltage and current noise is measured as a function of electrode area and frequency and follow unambiguously from the measured impedance. By using large area electrodes the noise floor can be as low as 0.3 μVpp. The resulting high sensitivity is demonstrated by the extracellular detection of C6 glioma cell populations. Their minute electrical activity can be clearly detected at a frequency below about 10 Hz, which shows that the methodology can be used to monitor slow cooperative biological signals in cell populations.
International Nuclear Information System (INIS)
Raman, V.; Tamilselvi, S.; Rajendran, N.
2007-01-01
Alkali treatment of titanium with subsequent heat treatment has been adapted as an important pre-treatment procedure for hydroxyapatite formation in orthopaedic applications. The electrochemical study during the alkali treatment process has not been explored yet. In the present work, electrochemical impedance spectroscopic (EIS) studies have been employed to analyse the electrochemical behaviour of titanium during the alkali treatment. The open circuit potential and potentiodynamic polarisation measurements were carried out in simulated body fluid (SBF) solution. Scanning electron microscopy and energy dispersive X-ray analysis were used to characterize the surface morphology and to correlate the results obtained from the electrochemical studies. An optimum growth of the passive film was found to occur at the end of 17th hour of treatment by alkali treatment. The alkali treated titanium immersed in SBF solution for various durations exhibited the formation of a duplex layer structure due to an inner barrier layer and an outer gel layer during the initial periods of immersion. However, with increase in immersion time to 10 days, a stable apatite layer was formed over the barrier layer and this was confirmed from the equivalent circuit fitted for the impedance data
Energy Technology Data Exchange (ETDEWEB)
Raman, V.; Tamilselvi, S. [Department of Chemistry, MIT Campus, Anna University, Chennai 600 044 (India); Rajendran, N. [Department of Chemistry, MIT Campus, Anna University, Chennai 600 044 (India)], E-mail: nrajendran@annauniv.edu
2007-09-30
Alkali treatment of titanium with subsequent heat treatment has been adapted as an important pre-treatment procedure for hydroxyapatite formation in orthopaedic applications. The electrochemical study during the alkali treatment process has not been explored yet. In the present work, electrochemical impedance spectroscopic (EIS) studies have been employed to analyse the electrochemical behaviour of titanium during the alkali treatment. The open circuit potential and potentiodynamic polarisation measurements were carried out in simulated body fluid (SBF) solution. Scanning electron microscopy and energy dispersive X-ray analysis were used to characterize the surface morphology and to correlate the results obtained from the electrochemical studies. An optimum growth of the passive film was found to occur at the end of 17th hour of treatment by alkali treatment. The alkali treated titanium immersed in SBF solution for various durations exhibited the formation of a duplex layer structure due to an inner barrier layer and an outer gel layer during the initial periods of immersion. However, with increase in immersion time to 10 days, a stable apatite layer was formed over the barrier layer and this was confirmed from the equivalent circuit fitted for the impedance data.
Impedance response characteristics of iron oxide interface in the EDTA solutions
International Nuclear Information System (INIS)
Sawa, Tosio; Higuchi, Shigeo; Kataoka, Ichiro; Ito, Hisao.
1986-01-01
The relationship between the dissolution and the surface conditions of Fe 3 O 4 were studied in the various conditions of EDTA solutions by means of the A · C impedance measurement. From the experimental results obtained, surface layer of Fe 3 O 4 electrode can be expressed with electrical equivalent circuit that have capacitance and reaction resistance in the electrical double layer. In the Na 2 SO 4 solution without occuring dissolution, reaction resistance was estimated as 314 kΩ · cm 2 and capacitance was 203 μF/cm 2 . In the EDTA solutions, reaction resistance decreases along with dissolution of Fe 3 O 4 . The factors to make decrease reaction resistance are EDTA concentration, pH and temperature of the solutions. In contrast with this, the factor to increase it is dissolved oxygen in the solutions. The reciprocal value of reaction resistance agrees well with the rate of dissolution. On the other hand, when the electrode potential was maintained under the cathodic polarization in the EDTA solutions, impedances of electrode surface showed the lower value than that in the immersion condition. And apparent resistance came near to 0 at the potential of -2.0 V in all the range of frequency. Fe 3 O 4 electrodes pretreated with the cathodic polarization exhibited the characteristic impedance response that were caused by the change of electrode surface and the deposites such as iron hydroxide. (author)
Tsai, Meng-Yen; Creedon, Niamh; Brightbill, Eleanor; Pavlidis, Spyridon; Brown, Billyde; Gray, Darren W.; Shields, Niall; Sayers, Ríona; Mooney, Mark H.; O'Riordan, Alan; Vogel, Eric M.
2017-08-01
A fully integrated system that combines extended gate field-effect transistor (EGFET)-based potentiometric biosensors and electrochemical impedance spectroscopy (EIS)-based biosensors has been demonstrated. This integrated configuration enables the sequential measurement of the same immunological binding event on the same sensing surface and consequently sheds light on the fundamental origins of sensing signals produced by FET and EIS biosensors, as well as the correlation between the two. Detection of both the bovine serum albumin (BSA)/anti-BSA model system in buffer solution and bovine parainfluenza antibodies in complex blood plasma samples was demonstrated using the integrated biosensors. Comparison of the EGFET and EIS sensor responses reveals similar dynamic ranges, while equivalent circuit modeling of the EIS response shows that the commonly reported total impedance change (ΔZtotal) is dominated by the change in charge transfer resistance (Rct) rather than surface capacitance (Csurface). Using electrochemical kinetics and the Butler-Volmer equation, we unveil that the surface potential and charge transfer resistance, measured by potentiometric and impedance biosensors, respectively, are, in fact, intrinsically linked. This observation suggests that there is no significant gain in using the FET/EIS integrated system and leads to the demonstration that low-cost EGFET biosensors are sufficient as a detection tool to resolve the charge information of biomolecules for practical sensing applications.
Directory of Open Access Journals (Sweden)
Emil Roduner
2012-06-01
Full Text Available Spatially resolved impedance spectroscopy of a Nafion polyelectrolyte membrane is performed employing a conductive and Pt-coated tip of an atomic force microscope as a point-like contact and electrode. The experiment is conducted by perturbing the system by a rectangular voltage step and measuring the incurred current, followed by Fourier transformation and plotting the impedance against the frequency in a conventional Bode diagram. To test the potential and limitations of this novel method, we present a feasibility study using an identical hydrogen atmosphere at a well-defined relative humidity on both sides of the membrane. It is demonstrated that good quality impedance spectra are obtained in a frequency range of 0.2–1,000 Hz. The extracted polarization curves exhibit a maximum current which cannot be explained by typical diffusion effects. Simulation based on equivalent circuits requires a Nernst element for restricted diffusion in the membrane which suggests that this effect is based on the potential dependence of the electrolyte resistance in the high overpotential region.
El-Shabaan, M. M.
2018-02-01
Impedance spectroscopy and alternating-current (AC) conductivity (σ AC) studies of bulk 3-amino-7-(dimethylamino)-2-methyl-hydrochloride (neutral red, NR) have been carried out over the temperature (T) range from 303 K to 383 K and frequency (f) range from 0.5 kHz to 5 MHz. Dielectric data were analyzed using the complex impedance (Z *) and complex electric modulus (M *) for bulk NR at various temperatures. The impedance loss peaks were found to shift towards high frequencies, indicating an increase in the relaxation time (τ 0) and loss in the material, with increasing temperature. For each temperature, a single depressed semicircle was observed at high frequencies, originating from the bulk transport, and a spike in the low-frequency region, resulting from the electrode effect. Fitting of these curves yielded an equivalent circuit containing a parallel combination of a resistance R and constant-phase element (CPE) Q. The carrier transport in bulk NR is governed by the correlated barrier hopping (CBH) mechanism, some parameters of which, such as the maximum barrier height (W M), charge density (N), and hopping distance (r), were determined as functions of both temperature and frequency. The frequency dependence of σ AC at different temperatures indicated that the conduction in bulk NR is a thermally activated process. The σ AC value at different frequencies increased linearly with temperature.
Directory of Open Access Journals (Sweden)
Bastidas, D. M.
2004-08-01
Full Text Available This paper studies the applicability of Kramers-Kronig (KK relationships to assess the validity of real and imaginary impedance measurements for titanium in a Ringer's solution using the electrochemical impedance spectroscopy (EIS method. Nyquist and Bode plots showed a capacitive behaviour with a high impedance modulus including two time constants. Two procedures were employed in the implementation of the KK integral relationships based on an equivalent circuit which satisfies KK relationships and an ohmic resistance shunted to the measured EIS data. The titanium's EIS data satisfied the KK relationships.
Este artículo estudia la aplicabilidad de las relaciones de Kramers-Kronig (KK al estudio de la validez de las medidas de impedancia (EIS, parte real y parte imaginaria, del titanio en contacto con la solución de Ringer. Los diagramas de Nyquist y Bode muestran un comportamiento capacitivo, con un módulo de impedancia elevado y con dos constantes de tiempo. En la implementación de las integrales de KK se emplearon dos procedimientos, que se basan en un circuito equivalente que cumple las relaciones de KK y en una resistencia óhmica en paralelo añadida a los datos de impedancia medidos. Los resultados de impedancia del titanio satisfacen las relaciones de KK.
International Nuclear Information System (INIS)
Greffet, Jean-Jacques; Laroche, Marine; Marquier, Francois
2009-01-01
We introduce a generalized definition of the impedance of a nanoantenna that can be applied to any system. We also introduce a definition of the impedance of a two level system. Using this framework, we establish a link between the electrical engineering and the quantum optics picture of light emission.
RHIC injection kicker impedance
International Nuclear Information System (INIS)
Mane, V.; Peggs, S.; Trbojevic, D.; Zhang, W.
1995-01-01
The longitudinal impedance of the RHIC injection kicker is measured using the wire method up to a frequency of 3 GHz. The mismatch between the 50 ohm cable and the wire and pipe system is calibrated using the TRL calibration algorithm. Various methods of reducing the impedance, such as coated ceramic pipe and copper strips are investigated
Energy Technology Data Exchange (ETDEWEB)
Chakraborty Banerjee, P. [Department of Chemical Engineering, Monash University, Clayton, VIC-3800 (Australia); CAST Cooperative Research Centre, Hawthorn, VIC-3122 (Australia); Singh Raman, R.K., E-mail: raman.singh@eng.monash.edu.a [Department of Chemical Engineering, Monash University, Clayton, VIC-3800 (Australia); Department of Mechanical and Aerospace Engineering, Monash University, Clayton, VIC-3800 (Australia)
2011-04-15
The protective performance of the coatings of bis-1,2-(triethoxysilyl) ethane (BTSE) on ZE41 magnesium alloy with different surface pre-treatments were evaluated using potentiodynamic polarization and electrochemical impedance spectroscopy (EIS) in 0.1 M sodium chloride solution. Electrical equivalent circuits were developed based upon hypothetical corrosion mechanisms and simulated to correspond to the experimental data. The morphology and cross section of the alloy subjected to different pre-treatments and coatings were characterized using scanning electron microscope. A specific alkaline pre-treatment of the substrate prior to the coating has been found to improve the corrosion resistance of the alloy.
International Nuclear Information System (INIS)
Chakraborty Banerjee, P.; Singh Raman, R.K.
2011-01-01
The protective performance of the coatings of bis-1,2-(triethoxysilyl) ethane (BTSE) on ZE41 magnesium alloy with different surface pre-treatments were evaluated using potentiodynamic polarization and electrochemical impedance spectroscopy (EIS) in 0.1 M sodium chloride solution. Electrical equivalent circuits were developed based upon hypothetical corrosion mechanisms and simulated to correspond to the experimental data. The morphology and cross section of the alloy subjected to different pre-treatments and coatings were characterized using scanning electron microscope. A specific alkaline pre-treatment of the substrate prior to the coating has been found to improve the corrosion resistance of the alloy.
Energy storage cell impedance measuring apparatus, methods and related systems
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.
International Nuclear Information System (INIS)
Fu, Ji; Tan, Chi; Li, Faxin
2015-01-01
The electromechanical impedance (EMI) method, which holds great promise in structural health monitoring (SHM), is usually treated as a qualitative method. In this work, we proposed a quantitative EMI method based on a piezoelectric bimorph cantilever using the sample’s local contact stiffness (LCS) as the identification parameter for nondestructive testing (NDT). Firstly, the equivalent circuit of the contact vibration system was established and the analytical relationship between the cantilever’s contact resonance frequency and the LCS was obtained. As the LCS is sensitive to typical defects such as voids and delamination, the proposed EMI method can then be used for NDT. To verify the equivalent circuit model, two piezoelectric bimorph cantilevers were fabricated and their free resonance frequencies were measured and compared with theoretical predictions. It was found that the stiff cantilever’s EMI can be well predicted by the equivalent circuit model while the soft cantilever’s cannot. Then, both cantilevers were assembled into a homemade NDT system using a three-axis motorized stage for LCS scanning. Testing results on a specimen with a prefabricated defect showed that the defect could be clearly reproduced in the LCS image, indicating the validity of the quantitative EMI method for NDT. It was found that the single-frequency mode of the EMI method can also be used for NDT, which is faster but not quantitative. Finally, several issues relating to the practical application of the NDT method were discussed. The proposed EMI-based NDT method offers a simple and rapid solution for damage evaluation in engineering structures and may also shed some light on EMI-based SHM. (paper)
Impedance and Collective Effects
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
Extended equivalent dipole model for radiated emissions
Obiekezie, Chijioke S.
2016-01-01
This work is on the characterisation of radiated fields from electronic devices. An equivalent dipole approach is used. Previous work showed that this was an effective approach for single layer printed circuit boards where an infinite ground plane can be assumed. In this work, this approach is extended for the characterisation of more complex circuit boards or electronic systems.\\ud For complex electronic radiators with finite ground planes, the main challenge is characterising field diffract...
International Nuclear Information System (INIS)
Hung, C.-C.; Lee, W.-H.; Wang, Y.-L.; Chan, D.-Y.; Hwang, G.-J.
2008-01-01
Polyethylene glycol (PEG) is an additive that is commonly used as a suppressor in the semiconductor copper (Cu)-electroplating process. In this study, electrochemical impedance spectroscopy (EIS) was used to analyze the electrochemical behavior of PEG in the Cu-electroplating process. Polarization analysis, cyclic-voltammetry stripping, and cell voltage versus plating time were examined to clarify the suppression behavior of PEG. The equivalent circuit simulated from the EIS data shows that PEG inhibited the Cu-electroplating rate by increasing the charge-transfer resistance as well as the resistance of the adsorption layer. The presence of a large inductance demonstrated the strong adsorption of cuprous-PEG-chloride complexes on the Cu surface during the Cu-electroplating process. Increasing the PEG concentration appears to increase the resistances of charge transfer, the adsorption layer, and the inductance of the electroplating system
Electrical Impedance Tomography Technology
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...
Impedance and component heating
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.
Impedance adaptation methods of the piezoelectric energy harvesting
Kim, Hyeoungwoo
factor. This characteristic is useful for a small force vibration source which has a high displacement such as human's activities. An experimental setup was used to apply the same conditions as a vibrating car engine. The experiment was done with a cymbal transducer which has 29 mm PZT diameter, 1mm PZT thickness, and 0.4mm endcap operating under force of 70 N in the frequency range of 10--200 Hz. It was found that the generated power was increased and the output impedance was decreased with a higher frequency of vibration source at a constant force. The experimental results were found to be in agreement with the analytical results from the model using the equivalent circuit. In addition, the FEM simulation (ATILA) was employed to optimize the dimensions of cymbal transducer such as endcap thickness and PZT thickness. Finally, the electrical impedance matching method used to increase the electrical to electrical energy transfer for some applications was discussed. To match the output impedance, two methods were employed: one is changing capacitance of transducer by size effect and multilayered ceramics, and another one is developing an energy harvesting circuit which consumes low electrical power and maximizes the output transferred to the intended load. The fabricated multilayered ceramics which has 10, 100 mum thick, layers yielded 10 times higher output current for 40 times reduced output load. Also the electrical output power was double. A DC-DC buck converter which has 78% efficiency was fabricated to transfer the accumulated electrical energy to the low output load without consuming more than 5 mW of power itself. In this DC-DC converter, most of the power was consumed by the gate drive which was required for PWM switching. To reduce the power consumption of the gate drive, the switching frequency was fixed at 1 kHz with optimal duty cycle around 1˜5%. Also the dependence of the inductance (L) in the DC-DC converter was investigated and optimized to increase the
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)
Measured longitudinal beam impedance of booster gradient magnets; TOPICAL
International Nuclear Information System (INIS)
James L Crisp and Brian J. Fellenz
2001-01-01
The Booster gradient magnets have no vacuum pipe which forces the beam image current to flow along the laminated pole tips. Both D and F style magnets were measured with a stretched wire to determine the longitudinal beam impedance caused by these laminations. Results are compared to calculations done 30 years ago. The inductive part of the magnet impedance is interesting because it partially compensates for the negative inductance effects of space charge on the beam. An R/L circuit consisting of 37K(center d ot) in parallel with between 40 and 100uH is a reasonable approximation to the total impedance of Booster magnet laminations
Hyperchaotic circuit with damped harmonic oscillators
DEFF Research Database (Denmark)
Lindberg, Erik; Murali, K.; Tamasevicius, A.
2001-01-01
A simple fourth-order hyperchaotic circuit with damped harmonic oscillators is described. ANP3 and PSpice simulations including an eigenvalue study of the linearized Jacobian are presented together with a hardware implementation. The circuit contains two inductors with series resistance, two ideal...... capacitors and one nonlinear active conductor. The Lyapunov exponents are presented to confirm the hyperchaotic nature of the oscillations of the circuit. The nonlinear conductor is realized with a diode. A negative impedance converter and a linear resistor. The performance of the circuit is investigated...... by means of numerical integration of the appropriate differential equations....
Resonance circuits for adiabatic circuits
Directory of Open Access Journals (Sweden)
C. Schlachta
2003-01-01
Full Text Available One of the possible techniques to reduces the power consumption in digital CMOS circuits is to slow down the charge transport. This slowdown can be achieved by introducing an inductor in the charging path. Additionally, the inductor can act as an energy storage element, conserving the energy that is normally dissipated during discharging. Together with the parasitic capacitances from the circuit a LCresonant circuit is formed.
Interrogation of the rat mammary gland using intraductal impedance spectroscopy
International Nuclear Information System (INIS)
Young, E F; Quinn, D A; Davies, R J
2010-01-01
Extant technologies for the detection of breast cancer exploit changes in the morphology of the mammary ductal epithelial network and can involve ionizing radiation. Intraductal surveillance of mammary epithelium has the potential to allow for earlier detection based on changes in function of the epithelium. This study investigated the feasibility of using intraductal impedance spectroscopy (IIS) to assess changes in resistance in the mammary epithelium in a small group of female rats in resting, pregnant and ultimately lactating states. In resting rats, intraductal surveillance was able to detect only a single resistive capacitance (RC). In pregnant animals, a second RC became evident in the frequency range between 1 and 190 Hz. The real resistance of this low frequency RC increased when measurements were made after the animals had begun lactating. Equivalent circuit modeling revealed this increase to be a 1.7-fold change from pregnancy to lactation. A model of tight junction closure in the context of ductal expansion is proposed. These results suggest that physiologic measurements can be made in rodent mammary epithelium using this technique allowing for assessment of function in normal and disease states
Impedance and modulus spectroscopic study of nano hydroxyapatite
Jogiya, B. V.; Jethava, H. O.; Tank, K. P.; Raviya, V. R.; Joshi, M. J.
2016-05-01
Hydroxyapatite (Ca10 (PO4)6 (OH)2, HAP) is the main inorganic component of the hard tissues in bones and also important material for orthopedic and dental implant applications. Nano HAP is of great interest due to its various bio-medical applications. In the present work the nano HAP was synthesized by using surfactant mediated approach. Structure and morphology of the synthesized nano HAP was examined by the Powder XRD and TEM. Impedance study was carried out on pelletized sample in a frequency range of 100Hz to 20MHz at room temperature. The variation of dielectric constant, dielectric loss, and a.c. conductivity with frequency of applied field was studied. The Nyquist plot as well as modulus plot was drawn. The Nyquist plot showed two semicircle arcs, which indicated the presence of grain and grain boundary effect in the sample. The typical behavior of the Nyquist plot was represented by equivalent circuit having two parallel RC combinations in series.
Laboratory scale tests of electrical impedence tomography
International Nuclear Information System (INIS)
Binley, A; Daily, W; LaBredcque, D; Ramirez, A.
1998-01-01
Electrical impedance tomographs (magnitude and phase) of known, laboratory-scale targets are reported. Three methods are used to invert electrical impedance data and their tomographs compared. The first method uses an electrical resistance tomography (ERT) algonthm (designed for DC resistivity inversion) to perform impedance magnitude inversion and a linearized perturbation approach (PA) to invert the imaginary part. The second approximate method compares ERT magnitude inversions at two frequencies and uses the frequency effect (FE) to compute phase tomographs. The third approach, electrrcal impedance tomography (EIT), employs fully complex algebra to account for the real and imaginary components of electrical impedance data. The EIT approach provided useful magnitude and phase images for the frequency range of 0.0625 to 64 Hz; images for higher frequencies were not reliable. Comparisons of the ERT and EIT magnitude images show that both methods provided equivalent results for the water blank, copper rod and PVC rod targets. The EIT magnitude images showed better spatial resolutron for a sand-lead mixture target. Phase images located anomalies of both high and low contrast IP and provided better spatial resolution than the magnitude images. When IP was absent from the data, the EIT algorithm reconstructed phase values consistent with the data noise levels
Impedance matching through a single passive fractional element
Radwan, Ahmed Gomaa
2012-07-01
For the first time, a generalized admittance Smith chart theory is introduced to represent fractional order circuit elements. The principles of fractional order matching circuits are described. We show that for fractional order α < 1, a single parallel fractional element can match a wider range of load impedances as compared to its series counterpart. Several matching examples demonstrate the versatility of fractional order series and parallel element matching as compared to the conventional approach. © 2012 IEEE.
Short circuit in deep brain stimulation.
Samura, Kazuhiro; Miyagi, Yasushi; Okamoto, Tsuyoshi; Hayami, Takehito; Kishimoto, Junji; Katano, Mitsuo; Kamikaseda, Kazufumi
2012-11-01
The authors undertook this study to investigate the incidence, cause, and clinical influence of short circuits in patients treated with deep brain stimulation (DBS). After the incidental identification of a short circuit during routine follow-up, the authors initiated a policy at their institution of routinely evaluating both therapeutic impedance and system impendence at every outpatient DBS follow-up visit, irrespective of the presence of symptoms suggesting possible system malfunction. This study represents a report of their findings after 1 year of this policy. Implanted DBS leads exhibiting short circuits were identified in 7 patients (8.9% of the patients seen for outpatient follow-up examinations during the 12-month study period). The mean duration from DBS lead implantation to the discovery of the short circuit was 64.7 months. The symptoms revealing short circuits included the wearing off of therapeutic effect, apraxia of eyelid opening, or dysarthria in 6 patients with Parkinson disease (PD), and dystonia deterioration in 1 patient with generalized dystonia. All DBS leads with short circuits had been anchored to the cranium using titanium miniplates. Altering electrode settings resulted in clinical improvement in the 2 PD cases in which patients had specific symptoms of short circuits (2.5%) but not in the other 4 cases. The patient with dystonia underwent repositioning and replacement of a lead because the previous lead was located too anteriorly, but did not experience symptom improvement. In contrast to the sudden loss of clinical efficacy of DBS caused by an open circuit, short circuits may arise due to a gradual decrease in impedance, causing the insidious development of neurological symptoms via limited or extended potential fields as well as shortened battery longevity. The incidence of short circuits in DBS may be higher than previously thought, especially in cases in which DBS leads are anchored with miniplates. The circuit impedance of DBS
Electronic circuit encyclopedia 2
International Nuclear Information System (INIS)
Park, Sun Ho
1992-10-01
This book is composed of 15 chapters, which are amplification of weak signal and measurement circuit audio control and power amplification circuit, data transmission and wireless system, forwarding and isolation, signal converting circuit, counter and comparator, discriminator circuit, oscillation circuit and synthesizer, digital and circuit on computer image processing circuit, sensor drive circuit temperature sensor circuit, magnetic control and application circuit, motor driver circuit, measuring instrument and check tool and power control and stability circuit.
Electronic circuit encyclopedia 2
Energy Technology Data Exchange (ETDEWEB)
Park, Sun Ho
1992-10-15
This book is composed of 15 chapters, which are amplification of weak signal and measurement circuit audio control and power amplification circuit, data transmission and wireless system, forwarding and isolation, signal converting circuit, counter and comparator, discriminator circuit, oscillation circuit and synthesizer, digital and circuit on computer image processing circuit, sensor drive circuit temperature sensor circuit, magnetic control and application circuit, motor driver circuit, measuring instrument and check tool and power control and stability circuit.
DEFF Research Database (Denmark)
Gonzalez Eiras, Martin; Niepelt, Dirk
2015-01-01
Traditional "economic equivalence'' results, like the Ricardian equivalence proposition, define equivalence classes over exogenous policies. We derive "politico-economic equivalence" conditions that apply in environments where policy is endogenous and chosen sequentially. A policy regime and a st......Traditional "economic equivalence'' results, like the Ricardian equivalence proposition, define equivalence classes over exogenous policies. We derive "politico-economic equivalence" conditions that apply in environments where policy is endogenous and chosen sequentially. A policy regime...... their use in the context of several applications, relating to social security reform, tax-smoothing policies and measures to correct externalities....
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.
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.
Rahman Khan, Motiur; Anjaneyulu, P.; Koteswara Rao, K. S. R.; Menon, R.
2017-03-01
We report on the analysis of temperature-dependent current-voltage characteristics and impedance measurements of electrochemically doped poly(3-methylthiophene) devices at different doping levels. The extent of doping is carefully tailored such that only the bulk-limited transport mechanism prevails. A transition from exponentially distributed trap-limited transport to trap-free space-charge-limited current is observed in current-voltage conduction upon increasing the doping. The obtained trap densities (3.2 × 1016 cm-3 and 8.6 × 1015 cm-3) and trap energies (31.7 meV and 16.6 meV) for different devices signify the variation in disorder with doping, which is later supported by impedance measurements. Impedance-frequency data for various devices can not be explained using the parallel resistance-capacitance (RC) model in the equivalent circuit. However, this was established by incorporating a constant phase element Q (CPE) instead of the capacitance parameter. It should be emphasized that low doping devices in particular are best simulated with two CPE elements, while the data related to other devices are fitted well with a single CPE element. It is also observed from evaluated circuit parameters that the spatial inhomogeneity and disorder are the cause of variability in different samples, which has an excellent correlation with the temperature-dependent current-voltage characteristics.
Microgrid Reactive and Harmonic Power Sharing Using Enhanced Virtual Impedance
DEFF Research Database (Denmark)
He, Jinwei; Wei Li, Yun; Guerrero, Josep M.
2013-01-01
To address the load sharing problem in islanding microgrids, this paper proposes an improved approach which regulates the distributed generation (DG) unit interfacing virtual impedance at fundamental and selected harmonic frequencies. In contrast to the conventional virtual impedance control where...... only a line current feed-forward term is added to the DG voltage reference, the proposed virtual impedances at fundamental and harmonic frequencies are realized using DG line current and point of common coupling (PCC) voltage feed-forward terms, respectively. With this modification, the mismatched DG...... feeder impedances can be properly compensated, resulting in accurate reactive and harmonic power sharing at the same time. In addition, this paper shows that the microgrid PCC harmonic voltages can be mitigated by reducing the magnitude of DG unit equivalent harmonic impedance. Finally, an improved...
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
Superconducting active impedance converter
International Nuclear Information System (INIS)
Ginley, D.S.; Hietala, V.M.; Martens, J.S.
1993-01-01
A transimpedance amplifier for use with high temperature superconducting, other superconducting, and conventional semiconductors allows for appropriate signal amplification and impedance matching to processing electronics. The amplifier incorporates the superconducting flux flow transistor into a differential amplifier configuration which allows for operation over a wide temperature range, and is characterized by high gain, relatively low noise, and response times less than 200 picoseconds over at least a 10-80 K. temperature range. The invention is particularly useful when a signal derived from either far-IR focal plane detectors or from Josephson junctions is to be processed by higher signal/higher impedance electronics, such as conventional semiconductor technology. 12 figures
International Nuclear Information System (INIS)
Yan, Bo; Li, Minsi; Li, Xifei; Bai, Zhimin; Dong, Lei; Li, Dejun
2015-01-01
Highlights: • The electrochemical reaction kinetics of the Ni/NiO anode was studied for the first time. • Charge transfer resistance is main contribution to total resistance during discharge process. • The slow growth of the SEI film is responsible for the capacity fading upon cycling. • Some promising strategies to optimize NiO anode performance were summarized. - Abstract: The electrochemical reaction kinetics of the porous core–shell structured Ni/NiO anode for Li ion battery application is systematically investigated by monitoring the electrochemical impedance evolution for the first time. The electrochemical impedance under prescribed condition is measured by using impedance spectroscopy in equilibrium conditions at various depths of discharge (DOD) during charge–discharge cycles. The Nyquist plots of the binder-free porous Ni/NiO electrode are interpreted with a selective equivalent circuit composed of solution resistance, solid electrolyte interphase (SEI) film, charge transfer and solid state diffusion. The impedance analysis shows that the change of charge transfer resistance is the main contribution to the total resistance change during discharge, and the surface configuration of the obtained electrode may experience significant change during the first two cycles. Meanwhile, the increase of internal resistance reduced the utilization efficiency of the active material may be another convincing factor to increase the irreversible capacity. In addition, the impedance evolution of the as-prepared electrode during charge–discharge cycles reveals that the slow growth of the SEI film is responsible for the capacity fading after long term cycling. As a result, several strategies are summarized to optimize the electrochemical performances of transition metal oxide anodes for lithium ion batteries
Directory of Open Access Journals (Sweden)
Carmen A. Bulucea
2013-03-01
current interruption by the generator the circuit-breaker (when the GCB has been subjected at the metal contact terminals to the high temperature of a plasma arc, up to 50,000 K between its opened contacts, there arises the transient recovery voltage (TRV which constitutes the most important dielectric stress after the electric arc extinction. Since the magnitude and shape of the TRV occurring across the generator circuit-breaker are critical parameters in the recovering gap after the current zero, in this paper, we model, for the case of the faults fed by the main step-up transformer, the equivalent configurations, with operational impedances, for the TRV calculation, taking into account the main transformer parameters, on the basis of the symmetrical components method.
Impact of grid impedance variations on harmonic emission of grid-connected inverters
DEFF Research Database (Denmark)
Hoseinzadeh, Bakhtyar; Bak, Claus Leth; Blaabjerg, Frede
2017-01-01
This paper addresses harmonic magnification due to resonance circuits resulting from interaction between uncertain grid impedance and converter. The source of harmonic may be either the grid or inverter. It is demonstrated that unknown and unpredictable grid impedance may result in variable...
International Nuclear Information System (INIS)
Gao, Wenjiao; Cao, Si; Yang, Yanze; Wang, Hao; Li, Jin; Jiang, Yiming
2012-01-01
The electrochemical corrosion behaviors of indium tin oxide (ITO) films under the cathodic polarization in 0.1 M NaOH solution were investigated by electrochemical impedance spectroscopy. The as-received and the cathodically polarized ITO films were characterized by scanning electron microscopy, energy dispersive X-ray spectroscopy and X-ray diffraction for morphological, compositional and structural studies. The results showed that ITO films underwent a corrosion process during the cathodic polarization and the main component of the corrosion products was body-centered cubic indium. The electrochemical impedance parameters were related to the effect of the cathodic polarization on the ITO specimens. The capacitance of ITO specimens increased, while the charge transfer resistance and the inductance decreased with the increase of the polarization time. The proposed mechanism indicated that the corrosion products (metallic indium) were firstly formed during the cathodic polarization and then absorbed on the surface of the ITO film. As the surface was gradually covered by indium particles, the corrosion process was suppressed. - Highlights: ► Cathodic polarization of indium tin oxide (ITO) in 0.1 M NaOH. ► Cathodic polarization studied with electrochemical impedance spectroscopy. ► ITO underwent a corrosion attack during cathodic polarization, indium was observed. ► Electrochemical parameters of ITO were obtained using equivalent electrical circuit. ► A corrosion mechanism is proposed.
International Nuclear Information System (INIS)
Li, J.; Zheng, L.; Zeng, L.; Zhang, Y.; Jiang, L.; Song, J.; Li, J.; Zheng, L.; Song, J.; Li, J.; Zheng, L.; Song, J.
2016-01-01
A new biomimetic nano interface was constructed by facile grafting the bioactive arginylglycylaspartic acid (RGD) peptide on the graphene oxide (GO) surface through carbodiimide and N-hydroxysuccinimide coupling amidation reaction. The formed RGD-GO nano composites own unique two-dimensional structure and desirable electrochemical performance. The linked RGD peptides could improve GO∼s biocompatibility and support the adhesion and proliferation of human periodontal ligament fibroblasts (HPLFs) on RGD-GO biofilm surface. Furthermore the biologically active RGD-GO nano composites were demonstrated as a potential biomimetic nano interface for monitoring cell bio behaviors by electrochemical impedance spectroscopy (EIS). By analysis of the data obtained from equivalent circuit-fitting impedance spectroscopy, the information related to cell membrane capacitance, cell-cell gap resistance, and cell-electrode interface gap resistance in the process of cell adhesion and proliferation could be obtained. Besides, this proposed impedance-based cell sensor could be used to assess the inhibition effect of the lipopolysaccharide (LPS) on the HPLFs proliferation. Findings from this work suggested that RGD peptide functionalized GO nano materials may be not only applied in dental tissue engineering but also used as a sensor interface for electrochemical detection and analysis of cell behaviors in vitro.
Gerngross, Mark-Daniel; Carstensen, Jürgen; Föll, Helmut
2014-01-01
The electrochemical growth of Co nanowires in ultra-high aspect ratio InP membranes has been investigated by fast Fourier transform-impedance spectroscopy (FFT-IS) in the frequency range from 75 Hz to 18.5 kHz. The impedance data could be fitted very well using an electric circuit equivalent model with a series resistance connected in series to a simple resistor-capacitor (RC) element and a Maxwell element. Based on the impedance data, the Co deposition in ultra-high aspect ratio InP membranes can be divided into two different Co deposition processes. The corresponding share of each process on the overall Co deposition can be determined directly from the transfer resistances of the two processes. The impedance data clearly show the beneficial impact of boric acid on the Co deposition and also indicate a diffusion limitation of boric acid in ultra-high aspect ratio InP membranes. The grown Co nanowires are polycrystalline with a very small grain size. They show a narrow hysteresis loop with a preferential orientation of the easy magnetization direction along the long nanowire axis due to the arising shape anisotropy of the Co nanowires.
Energy Technology Data Exchange (ETDEWEB)
Ortega-Chavez, L. [Inst. Tecnologico de Chihuahua 2, Chihuahua, Chih (Mexico); Ortega-Chavez, L.; Herrera-Peraza, E. [Centro de Investigacion en Materiales Avanzados, Chiuahua, Chih (Mexico); Verde, Y. [Inst. Tecnologico de Cancun, Cancun, Quintana Roo (Mexico)
2008-04-15
One of the most widely studied reactions in electrochemistry is the hydrogen evolution reaction (HER). HER is important for the development of water hydrolysis and fuel cell technologies. Because hydrogen-substrate interaction determines oxygen reduction efficiency, an understanding of the chemical and electronic state of hydrogen adsorbed on the electrocatalyst surface is required. Electrochemical impedance spectroscopy (EIS) is a proven highly efficient technique for interface characterization and kinetic parameter determination for different reactions carried out on interfaces. This article presented a study that utilized EIS for characterizing electrodes under HER by implementing a rotating disc electrode with different carbon supported platinum nanoparticles loadings and different potentials in acidic solutions. The results collected by EIS were analyzed in terms of equivalent circuits to calculate different parameters which were compared by statistical analysis. The study also considered the Volmer, Heyrovsky and Tafel steps in the HER reaction as well as a single electro-absorbed intermediate species. The article discussed the experimental set-up with reference to measurements, simulation and fitting. Parameters analysis using ANOVA were reviewed. It was concluded that an increase in impedance occurs when platinum loading decreases in both high and low frequencies. 22 refs., 1 tab., 5 figs.
Characterization of Bi4Ge3O12 single crystal by impedance spectroscopy
Directory of Open Access Journals (Sweden)
Zélia Soares Macedo
2003-12-01
Full Text Available Bi4Ge3O12 (bismuth germanate - BGO single crystals were produced by the Czochralski technique and their electrical and dielectric properties were investigated by impedance spectroscopy. The isothermal ac measurements were performed for temperatures from room temperature up to 750 °C, but only the data taken above 500 °C presented a complete semicircle in the complex impedance diagrams. Experimental data were fitted to a parallel RC equivalent circuit, and the electrical conductivity was obtained from the resistivity values. Conductivity values from 5.4 × 10(9 to 4.3 × 10-7 S/cm were found in the temperature range of 500 to 750 °C. This electrical conductivity is thermally activated, following the Arrhenius law with an apparent activation energy of (1.41 ± 0.04 eV. The dielectric properties of BGO single crystal were also studied for the same temperature interval. Permittivity values of 20 ± 2 for frequencies higher than 10³ Hz and a low-frequency dispersion were observed. Both electric and dielectric behavior of BGO are typical of systems in which the conduction mechanism dominates the dielectric response.
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
The point of practical use for the transistor circuit
International Nuclear Information System (INIS)
1996-01-01
This is comprised of eight chapters and goes as follows; what is transistor? the first step for use of transistor such as connection between power and signal source, static characteristic of transistor and equivalent circuit of transistor, design of easy small-signal amplifier circuit, design for amplification of electric power and countermeasure for prevention of trouble, transistor concerned interface, transistor circuit around micro computer, transistor in active use of FET and power circuit and transistor. It has an appendix on transistor and design of bias of FET circuits like small signal transistor circuit and FET circuit.
Tapping mode microwave impedance microscopy
Lai, K.; Kundhikanjana, W.; Peng, H.; Cui, Y.; Kelly, M. A.; Shen, Z. X.
2009-01-01
We report tapping mode microwave impedance imaging based on atomic force microscope platforms. The shielded cantilever probe is critical to localize the tip-sample interaction near the tip apex. The modulated tip-sample impedance can be accurately
International Nuclear Information System (INIS)
Ochoa, Nathalie; Pebere, Nadine; Moran, Francis; Tribollet, Bernard
2004-01-01
This work concerned an extensive study of the mechanism of inhibition of a carbon steel in a 200 mg l -1 NaCl solution by a non-toxic multicomponent inhibitor used for water treatment in cooling circuits. The inhibitive formulation was composed of 50 mg l -1 fatty amines associated with 200 mg l -1 phosphonocarboxylic acid salts. The influence of flow and immersion time was investigated by electrochemical impedance spectroscopy with a rotating disc electrode. The results were dependent on the experimental protocol used. Equivalent circuits were used to fit the experimental data. The properties of the protective layer were dependent on the electrode rotation rate and on the immersion time. This behaviour was related to the influence of flow on the anodic kinetics. (authors)
Package Holds Five Monolithic Microwave Integrated Circuits
Mysoor, Narayan R.; Decker, D. Richard; Olson, Hilding M.
1996-01-01
Packages protect and hold monolithic microwave integrated circuit (MMIC) chips while providing dc and radio-frequency (RF) electrical connections for chips undergoing development. Required to be compact, lightweight, and rugged. Designed to minimize undesired resonances, reflections, losses, and impedance mismatches.
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
Equivalence principles and electromagnetism
Ni, W.-T.
1977-01-01
The implications of the weak equivalence principles are investigated in detail for electromagnetic systems in a general framework. In particular, it is shown that the universality of free-fall trajectories (Galileo weak equivalence principle) does not imply the validity of the Einstein equivalence principle. However, the Galileo principle plus the universality of free-fall rotation states does imply the Einstein principle.
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...
High-efficiency resonant coupled wireless power transfer via tunable impedance matching
Anowar, Tanbir Ibne; Barman, Surajit Das; Wasif Reza, Ahmed; Kumar, Narendra
2017-10-01
For magnetic resonant coupled wireless power transfer (WPT), the axial movement of near-field coupled coils adversely degrades the power transfer efficiency (PTE) of the system and often creates sub-resonance. This paper presents a tunable impedance matching technique based on optimum coupling tuning to enhance the efficiency of resonant coupled WPT system. The optimum power transfer model is analysed from equivalent circuit model via reflected load principle, and the adequate matching are achieved through the optimum tuning of coupling coefficients at both the transmitting and receiving end of the system. Both simulations and experiments are performed to evaluate the theoretical model of the proposed matching technique, and results in a PTE over 80% at close coil proximity without shifting the original resonant frequency. Compared to the fixed coupled WPT, the extracted efficiency shows 15.1% and 19.9% improvements at the centre-to-centre misalignment of 10 and 70 cm, respectively. Applying this technique, the extracted S21 parameter shows more than 10 dB improvements at both strong and weak couplings. Through the developed model, the optimum coupling tuning also significantly improves the performance over matching techniques using frequency tracking and tunable matching circuits.
DEFF Research Database (Denmark)
2010-01-01
A switch-mode power circuit comprises a controllable element and a control unit. The controllable element is configured to control a current in response to a control signal supplied to the controllable element. The control unit is connected to the controllable element and provides the control...
Nelson, Jane B.
1998-01-01
Describes a research-based activity for high school physics students in which they build an LC circuit and find its resonant frequency of oscillation using an oscilloscope. Includes a diagram of the apparatus and an explanation of the procedures. (DDR)
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...... in the transmission such as the earphone impedance. In order to determine the acoustic impedances of human ear canals, the standardized method for measurement of complex impedances used for the measurement of the audiometric earphone impedances is applied. It is based on the transfer function between two microphone...... locations in an impedance tube. The end of the tube representing the measurement plane is placed at the ear canal entrance. Thus, the impedance seen from the entrance inward is measured on 25 subjects. Most subjects participated in the previous measurement of the ratio between the pressures at the open...
Complex Impedance of Fast Optical Transition Edge Sensors up to 30 MHz
Hattori, K.; Kobayashi, R.; Numata, T.; Inoue, S.; Fukuda, D.
2018-03-01
Optical transition edge sensors (TESs) are characterized by a very fast response, of the order of μs, which is 10^3 times faster than TESs for X-ray and gamma-ray. To extract important parameters associated with the optical TES, complex impedances at high frequencies (> 1 MHz) need to be measured, where the parasitic impedance in the circuit and reflections of electrical signals due to discontinuities in the characteristic impedance of the readout circuits become significant. This prevents the measurements of the current sensitivity β , which can be extracted from the complex impedance. In usual setups, it is hard to build a circuit model taking into account the parasitic impedances and reflections. In this study, we present an alternative method to estimate a transfer function without investigating the details of the entire circuit. Based on this method, the complex impedance up to 30 MHz was measured. The parameters were extracted from the impedance and were compared with other measurements. Using these parameters, we calculated the theoretical limit on an energy resolution and compared it with the measured energy resolution. In this paper, the reasons for the deviation of the measured value from theoretically predicted values will be discussed.
A novel broadband impedance method for detection of cell-derived microparticles.
Lvovich, Vadim; Srikanthan, Sowmya; Silverstein, Roy L
2010-10-15
A novel label-free method is presented to detect and quantify cell-derived microparticles (MPs) by the electrochemical potential-modulated electrochemical impedance spectroscopy (EIS). MPs are present in elevated concentrations during pathological conditions and play a major role in the establishment and pathogenesis of many diseases. Considering this, accurate detection and quantification of MPs is very important in clinical diagnostics and therapeutics. A combination of bulk solution electrokinetic sorting and interfacial impedance responses allows achieving detection limits as low as several MPs per μL. By fitting resulting EIS spectra with an equivalent electrical circuit, the bulk solution electrokinetic and interfacial impedance responses were characterized. In the bulk solution two major relaxations were prominent-β-relaxation in low MHz region due to the MP capacitive membrane bridging, and α-relaxation at ∼10 kHz due to counter ions diffusion. At low frequencies (10-0.1 Hz) at electrochemical potentials exceeding -100 mV, a facile interfacial Faradaic process of oxidation in MPs coupled with diffusion and non-Faradaic double layer charging dominate, probably due to oxidation of phospholipids and/or proteins on the MP surface and MP lysis. Buffer influence on the MP detection demonstrated that a relatively low conductivity Tyrode's buffer background solution is preferential for the MP electrokinetic separation and characterization. This study also demonstrated that standard laboratory methods such as flow cytometry underestimate MP concentrations, especially those with smaller average sizes, by as much as a factor of 2-40. Copyright © 2010 Elsevier B.V. All rights reserved.
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)
Impedance Characteristics Modeling of a Two-Terminal Active Capacitor
DEFF Research Database (Denmark)
Wang, Haoran; Wang, Huai; Lu, Minghui
2017-01-01
to overcome the above issues. In this paper, the modeling of the active capacitor is investigated and a voltage feed-forward compensation scheme is proposed for overshoot reduction. Therefore, the impedance, equivalent capacitance, ESR, and ESL, of the active capacitor can be specified. A case study based...
International Nuclear Information System (INIS)
Ji, In-Hwan; Choi, Young-Hwan; Ha, Min-Woo; Han, Min-Koo; Choi, Yearn-Ik
2006-01-01
A new protection circuit employing the collector to emitter voltage (V CE ) sensing scheme for short-circuit withstanding capability of the insulated gate bipolar transistor (IGBT) is proposed and verified by experimental results. Because the current path between the gate and collector can be successfully eliminated in the proposed protection circuit, the power consumption can be reduced and the gate input impedance can be increased. Previous study is limited to dc characteristics. However, experimental results show that the proposed protection circuit successfully reduces the over-current of main IGBT by 80.4% under the short-circuit condition
International Nuclear Information System (INIS)
Huang Bo; Chen Gang; Li Fei; Yu Qingchun; Hu Keao
2004-01-01
The preparation and subsequent oxidation of nickel cathodes modified by impregnation with rare earth oxide were evaluated by surface and bulk analysis. The electrochemical behaviors of rare earth oxide impregnated nickel oxide cathodes were also evaluated in a molten 62 mol% Li 2 CO 3 +38 mol% K 2 CO 3 eutectic at 650 deg. C by electrochemical impedance spectroscopy (EIS) as a function of rare earth oxide content and immersion time. The rare earth oxide-impregnated nickel cathodes show almost the similar porosity, pore size, and morphology to the reference nickel cathode. The stability tests of rare earth oxide-impregnated nickel oxide cathodes show that the rare earth oxide additive can dramatically reduce the solubility of nickel oxide in a eutectic carbonate mixture under the standard cathode gas condition. The impedance response of all cathode materials at different immersion time is characterized by the presence of depressed semicircles in the high frequency range changing over into the lines with the angles of which observed with the real axis differing 45 deg. or 90 deg. in the low frequency range. The experimental Nyquist plots can be well analyzed theoretically with a modified model based on the well-known Randles-Ershler equivalent circuit model. In the new model, the double layer capacity (C d ) is replaced by the parallel combination of C d and b/ω; therefore, this circuit is modified to be the parallel combination of (C d ), b/ω, and the charge transfer resistance (R ct ) based on the Randles-Ershler equivalent circuit, to take into consideration both the non-uniformity of electric field at the electrode/electrolyte interface owing to the roughness of electrode surface, and the variety of relaxation times with adsorbed species on the electrode surface. The impedance spectra for all cathode materials show important variations during the 200 h of immersion. The incorporation of lithium in its structure and the low dissolution of nickel oxide and rare
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)
High sound screening in low impedance slit arrays
International Nuclear Information System (INIS)
Estrada, Hector; Bravo, Jose Maria; Meseguer, Francisco
2011-01-01
We report on the key role of the acoustical impedance ratio between the solid and the host fluid in the transmission properties of slit arrays. Numerical calculations predict huge sound screening effects up to 60 dB for low impedance ratio values. The screening band appears over a broad frequency region and is very robust against dissipative losses of the material as well as against the sound incident angle. This counterintuitive result is discussed in terms of the hydrodynamic short circuit, where the fluid and the solid at the radiating interface vibrate out of phase, resulting in a huge sound blocking effect.
Electrochemical Impedance Imaging via the Distribution of Diffusion Times
Song, Juhyun; Bazant, Martin Z.
2018-03-01
We develop a mathematical framework to analyze electrochemical impedance spectra in terms of a distribution of diffusion times (DDT) for a parallel array of random finite-length Warburg (diffusion) or Gerischer (reaction-diffusion) circuit elements. A robust DDT inversion method is presented based on complex nonlinear least squares regression with Tikhonov regularization and illustrated for three cases of nanostructured electrodes for energy conversion: (i) a carbon nanotube supercapacitor, (ii) a silicon nanowire Li-ion battery, and (iii) a porous-carbon vanadium flow battery. The results demonstrate the feasibility of nondestructive "impedance imaging" to infer microstructural statistics of random, heterogeneous materials.
FLEXIBLE PH SENSOR WITH POLYANILINE LAYER BASED ON IMPEDANCE MEASUREMENT
Chuang, Cheng-Hsin; Wu, Hsun-Pei; Chen, Cheng-Ho; Wu, Peng-Rong
2012-01-01
A flexible sensor with conducting polyaniline layer for detecting pH value based on the impedance measurement is fabricated and demonstrated in this study. The pH sensor consists of an interdigital electrode array on a flexible printed circuit and a thin-film polyaniline as the sensing layer. As the conductivity of polyaniline depends on the redox state, the impedance change of the polyaniline after it has reacted with different pH value solutions works as the sensing mechanism. In order to o...
Theory of fractional order elements based impedance matching networks
Radwan, Ahmed G.
2011-03-01
Fractional order circuit elements (inductors and capacitors) based impedance matching networks are introduced for the first time. In comparison to the conventional integer based L-type matching networks, fractional matching networks are much simpler and versatile. Any complex load can be matched utilizing a single series fractional element, which generally requires two elements for matching in the conventional approach. It is shown that all the Smith chart circles (resistance and reactance) are actually pairs of completely identical circles. They appear to be single for the conventional integer order case, where the identical circles completely overlap each other. The concept is supported by design equations and impedance matching examples. © 2010 IEEE.
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
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
Electrical impedance tomography
Lobo, Beatriz; Hermosa, Cecilia; Abella, Ana
2018-01-01
Continuous assessment of respiratory status is one of the cornerstones of modern intensive care unit (ICU) monitoring systems. Electrical impedance tomography (EIT), although with some constraints, may play the lead as a new diagnostic and guiding tool for an adequate optimization of mechanical ventilation in critically ill patients. EIT may assist in defining mechanical ventilation settings, assess distribution of tidal volume and of end-expiratory lung volume (EELV) and contribute to titrate positive end-expiratory pressure (PEEP)/tidal volume combinations. It may also quantify gains (recruitment) and losses (overdistention or derecruitment), granting a more realistic evaluation of different ventilator modes or recruitment maneuvers, and helping in the identification of responders and non-responders to such maneuvers. Moreover, EIT also contributes to the management of life-threatening lung diseases such as pneumothorax, and aids in guiding fluid management in the critical care setting. Lastly, assessment of cardiac function and lung perfusion through electrical impedance is on the way. PMID:29430443
Energy Technology Data Exchange (ETDEWEB)
Tan, W.L. [Nanoscience Research Laboratory, School of Chemical Sciences, Universiti Sains Malaysia, 11800 Penang (Malaysia); Abu Bakar, M., E-mail: bmohamad@usm.my [Nanoscience Research Laboratory, School of Chemical Sciences, Universiti Sains Malaysia, 11800 Penang (Malaysia)
2013-06-05
Highlights: ► The Fe{sub 3}O{sub 4}/ENR nanocomposites have not been synthesized and reported. ► Nanocomposites were obtained via in situ synthesis of Fe{sub 3}O{sub 4} in the presence of ENR. ► The use of ENR enabled control of the size of Fe{sub 3}O{sub 4} particles to <20 nm. ► Conductivity of the nanocomposites increases with the increase in Fe{sub 3}O{sub 4} loading. ► The equivalent circuit for the nanocomposites is proposed and discussed. -- Abstract: The magnetite (Fe{sub 3}O{sub 4}) particles were synthesized in situ in the presence of epoxidized natural rubber (ENR) to produce the various Fe{sub 3}O{sub 4}/ENR nanocomposites. The X-ray diffraction (XRD) analysis confirmed the existence of Fe{sub 3}O{sub 4} particles in the composites. The FTIR and DSC studies suggested that no chemical interactions between the particles and the matrix. The SEM and X-mapping micrographs revealed that the Fe{sub 3}O{sub 4} particles were distributed within the ENR matrix. The ENR matrix exerts control on the Fe{sub 3}O{sub 4} particles with a size of <20 nm in the composites. The Fe{sub 3}O{sub 4} particles also affect the electrical properties of the composites. Impedance spectroscopy studies show that the electrical conductivity of the nanocomposites increases with the increase in Fe{sub 3}O{sub 4} loading in the composite. The equivalent circuit for the Fe{sub 3}O{sub 4}/ENR nanocomposites is proposed and discussed.
Modified coaxial wire method for measurement of transfer impedance of beam position monitors
Kumar, Mukesh; Babbar, L. K.; Deo, R. K.; Puntambekar, T. A.; Senecha, V. K.
2018-05-01
The transfer impedance is a very important parameter of a beam position monitor (BPM) which relates its output signal with the beam current. The coaxial wire method is a standard technique to measure transfer impedance of the BPM. The conventional coaxial wire method requires impedance matching between coaxial wire and external circuits (vector network analyzer and associated cables). This paper presents a modified coaxial wire method for bench measurement of the transfer impedance of capacitive pickups like button electrodes and shoe box BPMs. Unlike the conventional coaxial wire method, in the modified coaxial wire method no impedance matching elements have been used between the device under test and the external circuit. The effect of impedance mismatch has been solved mathematically and a new expression of transfer impedance has been derived. The proposed method is verified through simulation of a button electrode BPM using cst studio suite. The new method is also applied to measure transfer impedance of a button electrode BPM developed for insertion devices of Indus-2 and the results are also compared with its simulations. Close agreement between measured and simulation results suggests that the modified coaxial wire setup can be exploited for the measurement of transfer impedance of capacitive BPMs like button electrodes and shoe box BPM.
Modified coaxial wire method for measurement of transfer impedance of beam position monitors
Directory of Open Access Journals (Sweden)
Mukesh Kumar
2018-05-01
Full Text Available The transfer impedance is a very important parameter of a beam position monitor (BPM which relates its output signal with the beam current. The coaxial wire method is a standard technique to measure transfer impedance of the BPM. The conventional coaxial wire method requires impedance matching between coaxial wire and external circuits (vector network analyzer and associated cables. This paper presents a modified coaxial wire method for bench measurement of the transfer impedance of capacitive pickups like button electrodes and shoe box BPMs. Unlike the conventional coaxial wire method, in the modified coaxial wire method no impedance matching elements have been used between the device under test and the external circuit. The effect of impedance mismatch has been solved mathematically and a new expression of transfer impedance has been derived. The proposed method is verified through simulation of a button electrode BPM using cst studio suite. The new method is also applied to measure transfer impedance of a button electrode BPM developed for insertion devices of Indus-2 and the results are also compared with its simulations. Close agreement between measured and simulation results suggests that the modified coaxial wire setup can be exploited for the measurement of transfer impedance of capacitive BPMs like button electrodes and shoe box BPM.
A fast circuit analysis program based on microcomputer
International Nuclear Information System (INIS)
Hu Guoji
1988-01-01
A fast circuit analysis program (FCAP) is introduced. The program may be used to analyse DC operating point, frequency and transient response of fast circuit. The feature is that the model of active element is not specified. Users may choose one of many equivalent circuits. Written in FORTRAN 77, FCAP can be run on IBM PC and its compatible computers. It can be used as an assistant tool of analysis and design for fast circuits
How Many Equivalent Resistances?
Indian Academy of Sciences (India)
preceding numbers; this is expressed as the linear recurrence relation ... is gigantic and there is even a journal, The Fibonacci Quarterly, devoted to the study of .... Circuit Analysis, 11th Edition, Pearson International, Prentice Hall, 2007.
Microwave Impedance Measurement for Nanoelectronics
Directory of Open Access Journals (Sweden)
M. Randus
2011-04-01
Full Text Available The rapid progress in nanoelectronics showed an urgent need for microwave measurement of impedances extremely different from the 50Ω reference impedance of measurement instruments. In commonly used methods input impedance or admittance of a device under test (DUT is derived from measured value of its reflection coefficient causing serious accuracy problems for very high and very low impedances due to insufficient sensitivity of the reflection coefficient to impedance of the DUT. This paper brings theoretical description and experimental verification of a method developed especially for measurement of extreme impedances. The method can significantly improve measurement sensitivity and reduce errors caused by the VNA. It is based on subtraction (or addition of a reference reflection coefficient and the reflection coefficient of the DUT by a passive network, amplifying the resulting signal by an amplifier and measuring the amplified signal as a transmission coefficient by a common vector network analyzer (VNA. A suitable calibration technique is also presented.
International Nuclear Information System (INIS)
Huyskens, C.J.; Passchier, W.F.
1988-01-01
The effective dose equivalent is a quantity which is used in the daily practice of radiation protection as well as in the radiation hygienic rules as measure for the health risks. In this contribution it is worked out upon which assumptions this quantity is based and in which cases the effective dose equivalent can be used more or less well. (H.W.)
Characterization of revenue equivalence
Heydenreich, B.; Müller, R.; Uetz, Marc Jochen; Vohra, R.
2009-01-01
The property of an allocation rule to be implementable in dominant strategies by a unique payment scheme is called revenue equivalence. We give a characterization of revenue equivalence based on a graph theoretic interpretation of the incentive compatibility constraints. The characterization holds
Characterization of Revenue Equivalence
Heydenreich, Birgit; Müller, Rudolf; Uetz, Marc Jochen; Vohra, Rakesh
2008-01-01
The property of an allocation rule to be implementable in dominant strategies by a unique payment scheme is called \\emph{revenue equivalence}. In this paper we give a characterization of revenue equivalence based on a graph theoretic interpretation of the incentive compatibility constraints. The
International Nuclear Information System (INIS)
Grenet, G.; Kibler, M.
1978-06-01
A closed polynomial formula for the qth component of the diagonal operator equivalent of order k is derived in terms of angular momentum operators. The interest in various fields of molecular and solid state physics of using such a formula in connection with symmetry adapted operator equivalents is outlined
Uno, Kazuyuki; Akitsu, Tetsuya; Nakamura, Kenshi; Jitsuno, Takahisa
2013-04-01
We developed a modified driver circuit composed of a capacitance and a spark gap, called a direct-drive circuit, for a longitudinally excited gas laser. The direct-drive circuit uses a large discharge impedance caused by a long discharge length of the longitudinal excitation scheme and eliminates the buffer capacitance used in the traditional capacitor-transfer circuit. We compared the direct-drive circuit and the capacitor-transfer circuit in a longitudinally excited N2 laser (wavelength: 337 nm). Producing high output energy with the capacitor-transfer circuit requires a large storage capacitance and a discharge tube with optimum dimensions (an inner diameter of 4 mm and a length of 10 cm in this work); in contrast, the direct-drive circuit requires a high breakdown voltage, achieved with a small storage capacitance and a large discharge tube. Additionally, for the same input energy of 792 mJ, the maximum output energy of the capacitor-transfer circuit was 174.2 μJ, and that of the direct-drive circuit was 344.7 μJ.
Strong, G.H.; Faught, M.L.
1963-12-24
A device for safety rod counting in a nuclear reactor is described. A Wheatstone bridge circuit is adapted to prevent de-energizing the hopper coils of a ball backup system if safety rods, sufficient in total control effect, properly enter the reactor core to effect shut down. A plurality of resistances form one arm of the bridge, each resistance being associated with a particular safety rod and weighted in value according to the control effect of the particular safety rod. Switching means are used to switch each of the resistances in and out of the bridge circuit responsive to the presence of a particular safety rod in its effective position in the reactor core and responsive to the attainment of a predetermined velocity by a particular safety rod enroute to its effective position. The bridge is unbalanced in one direction during normal reactor operation prior to the generation of a scram signal and the switching means and resistances are adapted to unbalance the bridge in the opposite direction if the safety rods produce a predetermined amount of control effect in response to the scram signal. The bridge unbalance reversal is then utilized to prevent the actuation of the ball backup system, or, conversely, a failure of the safety rods to produce the predetermined effect produces no unbalance reversal and the ball backup system is actuated. (AEC)
Directory of Open Access Journals (Sweden)
Saverio Latorrata
2018-01-01
Full Text Available Polymer electrolyte membrane fuel cells (PEMFCs have attracted great attention in the last two decades as valuable alternative energy generators because of their high efficiencies and low or null pollutant emissions. In the present work, two gas diffusion electrodes (GDEs for PEMFCs were prepared by using an ink containing carbon-supported platinum in the catalytic phase which was sprayed onto a carbon cloth substrate. Two aerograph nozzles, with different sizes, were used. The prepared GDEs were assembled into a fuel cell lab prototype with commercial electrolyte and bipolar plates and tested alternately as anode and cathode. Polarization measurements and electrochemical impedance spectroscopy (EIS were performed on the running hydrogen-fed PEMFC from open circuit voltage to high current density. Experimental impedance spectra were fitted with an equivalent circuit model by using ZView software which allowed to get crucial parameters for the evaluation of fuel cell performance, such as ohmic resistance, charge transfer, and mass transfer resistance, whose trends have been studied as a function of the applied current density.
International Nuclear Information System (INIS)
Khan, Motiur Rahman; Koteswara Rao, K S R; Menon, R; Anjaneyulu, P
2017-01-01
We report on the analysis of temperature-dependent current–voltage characteristics and impedance measurements of electrochemically doped poly(3-methylthiophene) devices at different doping levels. The extent of doping is carefully tailored such that only the bulk-limited transport mechanism prevails. A transition from exponentially distributed trap-limited transport to trap-free space-charge-limited current is observed in current–voltage conduction upon increasing the doping. The obtained trap densities (3.2 × 10 16 cm −3 and 8.6 × 10 15 cm −3 ) and trap energies (31.7 meV and 16.6 meV) for different devices signify the variation in disorder with doping, which is later supported by impedance measurements. Impedance–frequency data for various devices can not be explained using the parallel resistance–capacitance ( RC ) model in the equivalent circuit. However, this was established by incorporating a constant phase element Q (CPE) instead of the capacitance parameter. It should be emphasized that low doping devices in particular are best simulated with two CPE elements, while the data related to other devices are fitted well with a single CPE element. It is also observed from evaluated circuit parameters that the spatial inhomogeneity and disorder are the cause of variability in different samples, which has an excellent correlation with the temperature-dependent current–voltage characteristics. (paper)
International Nuclear Information System (INIS)
Zalita, Z.; Halim, S.A.; Lim, K.P.; Talib, Z.A.; Hishamuddin, Z.; Walter, C.P.
2009-01-01
La 0.67 Sr 0.33 Mn 1-x Ti x O 3 samples with x = 0.0, 0.2, 0.4 and 0.6 have been prepared using the conventional solid-state reaction method. The structure, magnetic and electrical transport properties as well as the impedance spectroscopy of the samples were investigated. The powder XRD analysis showed that all samples were single phase with rhombohedral perovskite structure. The magnetization curve suggests that the Ti substituted samples exhibit weak ferromagnetic behaviour. The highest magnetoresistance (MR) value was obtained for sample x = 0.2 at temperature 200 K and field 1 T, which was 32.5 %. Low field magnetoresistance (LFMR) effect was observed for the x = 0.0 sample. The metal-like resistivity curve for the x = 0.0 sample was best fitted with ρ = ρo + ρ2T2 equation, indicating the grain boundary effects and electron-electron scattering process contribution. Semiconductor-like transport behaviour was observed for the Ti substituted samples and can be fitted by variable range hopping (VRH) and small polaron hopping (SPH) mechanisms. The activation energy of the samples increased when the Ti composition increased. An equivalent circuit was proposed for the impedance plot with a series of two parallel RC circuits. The grain, grain boundary and electrode resistance values increased with Ti composition due to the reduction of the Mn 3+ / Mn 4+ ratio. (author)
Impedance-stabilized positive corona discharge and its decontamination properties
Energy Technology Data Exchange (ETDEWEB)
Horak, P; Khun, J, E-mail: pavel.horak@vscht.c [Department of Physics and Measurements, Faculty of Chemical Engineering, Institute of Chemical Technology, Technicka 5, 166 28 Praha 6 (Czech Republic)
2010-04-01
The point-to-plane DC corona discharge in air at atmospheric pressure was stabilized by a serially connected ballast impedance. The ballast impedance was implemented by a resistor-capacitor group connected in parallel. In the case of connecting the serial impedance into the electric circuit of a negative corona, the transition into a spark takes place at parameters similar to those of a non-stabilized discharge. In contrast, in the case of a positive corona, the discharge does not undergo a transition into a spark, but rather into a mode of periodic streamers. We measured the bactericidal effect of the stabilized discharge. The experiments showed that after a 2-minute exposure the quantity of surviving bacteria decreased from 95% for a non-stabilized discharge down to 5% for a stabilized one.
Impedance-stabilized positive corona discharge and its decontamination properties
International Nuclear Information System (INIS)
Horak, P; Khun, J
2010-01-01
The point-to-plane DC corona discharge in air at atmospheric pressure was stabilized by a serially connected ballast impedance. The ballast impedance was implemented by a resistor-capacitor group connected in parallel. In the case of connecting the serial impedance into the electric circuit of a negative corona, the transition into a spark takes place at parameters similar to those of a non-stabilized discharge. In contrast, in the case of a positive corona, the discharge does not undergo a transition into a spark, but rather into a mode of periodic streamers. We measured the bactericidal effect of the stabilized discharge. The experiments showed that after a 2-minute exposure the quantity of surviving bacteria decreased from 95% for a non-stabilized discharge down to 5% for a stabilized one.
International Nuclear Information System (INIS)
Qian Li-Bo; Xia Yin-Shui; Zhu Zhang-Ming; Ding Rui-Xue; Yang Yin-Tang
2014-01-01
Through-silicon-via (TSV) to TSV crosstalk noise is one of the key factors affecting the signal integrity of three-dimensional integrated circuits (3D ICs). Based on the frequency dependent equivalent electrical parameters for the TSV channel, an analytical crosstalk noise model is established to capture the TSV induced crosstalk noise. The impact of various design parameters including insulation dielectric, via pitch, via height, silicon conductivity, and terminal impedance on the crosstalk noise is analyzed with the proposed model. Two approaches are proposed to alleviate the TSV noise, namely, driver sizing and via shielding, and the SPICE results show 241 mV and 379 mV reductions in the peak noise voltage, respectively
Testing Fixture For Microwave Integrated Circuits
Romanofsky, Robert; Shalkhauser, Kurt
1989-01-01
Testing fixture facilitates radio-frequency characterization of microwave and millimeter-wave integrated circuits. Includes base onto which two cosine-tapered ridge waveguide-to-microstrip transitions fastened. Length and profile of taper determined analytically to provide maximum bandwidth and minimum insertion loss. Each cosine taper provides transformation from high impedance of waveguide to characteristic impedance of microstrip. Used in conjunction with automatic network analyzer to provide user with deembedded scattering parameters of device under test. Operates from 26.5 to 40.0 GHz, but operation extends to much higher frequencies.
Short- circuit tests of circuit breakers
Chorovský, P.
2015-01-01
This paper deals with short-circuit tests of low voltage electrical devices. In the first part of this paper, there are described basic types of short- circuit tests and their principles. Direct and indirect (synthetic) tests with more details are described in the second part. Each test and principles are explained separately. Oscilogram is obtained from short-circuit tests of circuit breakers at laboratory. The aim of this research work is to propose a test circuit for performing indirect test.
Collective of mechatronics circuit
International Nuclear Information System (INIS)
1987-02-01
This book is composed of three parts, which deals with mechatronics system about sensor, circuit and motor. The contents of the first part are photo sensor of collector for output, locating detection circuit with photo interrupts, photo sensor circuit with CdS cell and lamp, interface circuit with logic and LED and temperature sensor circuit. The second part deals with oscillation circuit with crystal, C-R oscillation circuit, F-V converter, timer circuit, stability power circuit, DC amp and DC-DC converter. The last part is comprised of bridge server circuit, deformation bridge server, controlling circuit of DC motor, controlling circuit with IC for PLL and driver circuit of stepping motor and driver circuit of Brushless.
Collective of mechatronics circuit
Energy Technology Data Exchange (ETDEWEB)
NONE
1987-02-15
This book is composed of three parts, which deals with mechatronics system about sensor, circuit and motor. The contents of the first part are photo sensor of collector for output, locating detection circuit with photo interrupts, photo sensor circuit with CdS cell and lamp, interface circuit with logic and LED and temperature sensor circuit. The second part deals with oscillation circuit with crystal, C-R oscillation circuit, F-V converter, timer circuit, stability power circuit, DC amp and DC-DC converter. The last part is comprised of bridge server circuit, deformation bridge server, controlling circuit of DC motor, controlling circuit with IC for PLL and driver circuit of stepping motor and driver circuit of Brushless.
Impedances of nickel electrodes cycled in various KOH concentrations
Reid, Margaret A.; Loyselle, Patricia L.
1991-01-01
Recent tests at Hughes have shown that Ni/H2 cells cycled in 26 percent KOH have much longer lives than those cycled in other concentrations. As part of an ongoing program to try to correlate the impedances of nickel electrodes with their life and performance, impedances were measured of a number of electrodes from these tests that had been cycled in concentrations from 21 to 36 percent KOH. These had ranged from about 1000 to 40,000 cycles. After cycling ten times to reduce possible changes due to storage, impedances were measured at five voltages corresponding to low states of charge. The results were analyzed using a standard circuit model including Warburg impedance term. Lower kinetic resistances and Warburg slopes were found for several electrodes which had been cycled in 26 percent KOH even though they had been cycled for a much longer time than the others. Interpretation of the data is complicated by the fact that the cycle lives, storage times, and failure mechanisms varied. Several other circuit models have also been examined, but the best correlations with life were found with parameters obtained from the simple model.
Dynamic impedance compensation for wireless power transfer using conjugate power
Liu, Suqi; Tan, Jianping; Wen, Xue
2018-02-01
Wireless power transfer (WPT) via coupled magnetic resonances has been in development for over a decade. However, the frequency splitting phenomenon occurs in the over-coupled region. Thus, the output power of the two-coil system achieves the maximum output power at the two splitting angular frequencies, and not at the natural resonant angular frequency. According to the maximum power transfer theorem, the impedance compensation method was adopted in many WPT projects. However, it remains a challenge to achieve the maximum output power and transmission efficiency in a fixed-frequency mode. In this study, dynamic impedance compensation for WPT was presented by utilizing the compensator within a virtual three-coil WPT system. First, the circuit model was established and transfer characteristics of a system were studied by utilizing circuit theories. Second, the power superposition of the WPT system was carefully researched. When a pair of compensating coils was inserted into the transmitter loop, the conjugate power of the compensator loop was created via magnetic coupling of the two compensating coils that insert into the transmitter loop. The mechanism for dynamic impedance compensation for wireless power transfer was then provided by investigating a virtual three-coil WPT system. Finally, the experimental circuit of a virtual three-coil WPT system was designed, and experimental results are consistent with the theoretical analysis, which achieves the maximum output power and transmission efficiency.
Dynamic impedance compensation for wireless power transfer using conjugate power
Directory of Open Access Journals (Sweden)
Suqi Liu
2018-02-01
Full Text Available Wireless power transfer (WPT via coupled magnetic resonances has been in development for over a decade. However, the frequency splitting phenomenon occurs in the over-coupled region. Thus, the output power of the two-coil system achieves the maximum output power at the two splitting angular frequencies, and not at the natural resonant angular frequency. According to the maximum power transfer theorem, the impedance compensation method was adopted in many WPT projects. However, it remains a challenge to achieve the maximum output power and transmission efficiency in a fixed-frequency mode. In this study, dynamic impedance compensation for WPT was presented by utilizing the compensator within a virtual three-coil WPT system. First, the circuit model was established and transfer characteristics of a system were studied by utilizing circuit theories. Second, the power superposition of the WPT system was carefully researched. When a pair of compensating coils was inserted into the transmitter loop, the conjugate power of the compensator loop was created via magnetic coupling of the two compensating coils that insert into the transmitter loop. The mechanism for dynamic impedance compensation for wireless power transfer was then provided by investigating a virtual three-coil WPT system. Finally, the experimental circuit of a virtual three-coil WPT system was designed, and experimental results are consistent with the theoretical analysis, which achieves the maximum output power and transmission efficiency.
Smith, Geoff; Arshad, Muhammad Sohail; Polygalov, Eugene; Ermolina, Irina
2013-11-01
Impedance spectroscopy has been used for the measurement of the glass transition of a 10 % maltodextrin solution contained within a glass vial, with externally attached electrodes. Features of the pseudo-relaxation process, associated with the composite impedance of the glass vial-solution assembly, were characterised by the peak amplitude, C(peak)(″), and peak frequency, f(peak), of the capacitance spectra and the equivalent circuit elements that model the impedance spectra (i.e. the solution resistance and solution capacitance) and monitored every 3 min during re-heating of the solution. The time derivatives of all four parameters studied provided a glass transition in close agreement with DSC measurements (-17 °C) and at a precision of ± 0.5 °C. The temperature dependencies of the solution resistance and peak frequency were then characterised with the Arrhenius and Vogel-Fulcher-Tammann fit functions, at temperatures below and above Tg, respectively. The energy of activation (below Tg) was estimated at ~20 kJ mol(-1), and the fragility index (If) of the glass forming liquid (above Tg) was estimated at 0.9. The significance of the fragility index to the development, optimisation and control of the freeze-drying cycle is highlighted. Copyright © 2013 Elsevier B.V. All rights reserved.
Coplanar strips for Josephson voltage standard circuits
International Nuclear Information System (INIS)
Schubert, M.; May, T.; Wende, G.; Fritzsch, L.; Meyer, H.-G.
2001-01-01
We present a microwave circuit for Josephson voltage standards. Here, the Josephson junctions are integrated in a microwave transmission line designed as coplanar strips (CPS). The new layout offers the possibility of achieving a higher scale of integration and to considerably simplify the fabrication technology. The characteristic impedance of the CPS is about 50 Ω, and this should be of interest for programmable Josephson voltage standard circuits with SNS or SINIS junctions. To demonstrate the function of the microwave circuit design, conventional 10 V Josephson voltage standard circuits with 17000 Nb/AlO x /Nb junctions were prepared and tested. Stable Shapiro steps at the 10 V level were generated. Furthermore, arrays of 1400 SINIS junctions in this microwave layout exhibited first-order Shapiro steps. Copyright 2001 American Institute of Physics
Impedance models in time domain
Rienstra, S.W.
2005-01-01
Necessary conditions for an impedance function are derived. Methods available in the literature are discussed. A format with recipe is proposed for an exact impedance condition in time domain on a time grid, based on the Helmholtz resonator model. An explicit solution is given of a pulse reflecting
Optical approximation in the theory of geometric impedance
International Nuclear Information System (INIS)
Stupakov, G.; Bane, K.L.F.; Zagorodnov, I.
2007-02-01
In this paper we introduce an optical approximation into the theory of impedance calculation, one valid in the limit of high frequencies. This approximation neglects diffraction effects in the radiation process, and is conceptually equivalent to the approximation of geometric optics in electromagnetic theory. Using this approximation, we derive equations for the longitudinal impedance for arbitrary offsets, with respect to a reference orbit, of source and test particles. With the help of the Panofsky-Wenzel theorem we also obtain expressions for the transverse impedance (also for arbitrary offsets). We further simplify these expressions for the case of the small offsets that are typical for practical applications. Our final expressions for the impedance, in the general case, involve two dimensional integrals over various cross-sections of the transition. We further demonstrate, for several known axisymmetric examples, how our method is applied to the calculation of impedances. Finally, we discuss the accuracy of the optical approximation and its relation to the diffraction regime in the theory of impedance. (orig.)
Guzman, R
2000-03-01
Circuit parties are extended celebrations, lasting from a day to a week, primarily attended by gay and bisexual men in their thirties and forties. These large-scale dance parties move from city to city and draw thousands of participants. The risks for contracting HIV during these parties include recreational drug use and unsafe sex. Limited data exists on the level of risk at these parties, and participants are skeptical of outside help because of past criticism of these events. Health care and HIV advocates can promote risk-reduction strategies with the cooperation of party planners and can counsel individuals to personally reduce their own risk. To convey the message, HIV prevention workers should emphasize positive and community-centered aspects of the parties, such as taking care of friends and avoiding overdose.
Substrate Effects in Wideband SiGe HBT Mixer Circuits
DEFF Research Database (Denmark)
Johansen, Tom Keinicke; Vidkjær, Jens; Krozer, Viktor
2005-01-01
are also applied to predict short distance substrate coupling effects. Simulation results using extracted equivalent circuit models and substrate coupling networks are compared with experimental results obtained on a wideband mixer circuit implemented in a 0.35 μm, 60 GHz ft SiGe HBT BiCMOS process.......In this paper, the influence from substrate effects on the performance of wideband SiGe HBT mixer circuits is investigated. Equivalent circuit models including substrate networks are extracted from on-wafer test structures and compared with electromagnetic simulations. Electromagnetic simulations...
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...
Impedance source power electronic converters
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...
Integrated circuit implementation of fuzzy controllers
Huertas Díaz, José Luis; Sánchez Solano, Santiago; Baturone Castillo, María Iluminada; Barriga Barros, Ángel
1996-01-01
This paper presents mixed-signal current-mode CMOS circuits to implement programmable fuzzy controllers that perform the singleton or zero-order Sugeno’s method. Design equations to characterize these circuits are provided to explain the precision and speed that they offer. This analysis is illustrated with the experimental results of prototypes integrated in standard CMOS technologies. These tests show that an equivalent precision of 6 bits is achieved. The connection of these...
Molenaar, Peter C M
2017-01-01
Equivalences of two classes of dynamic models for weakly stationary multivariate time series are discussed: dynamic factor models and autoregressive models. It is shown that exploratory dynamic factor models can be rotated, yielding an infinite set of equivalent solutions for any observed series. It also is shown that dynamic factor models with lagged factor loadings are not equivalent to the currently popular state-space models, and that restriction of attention to the latter type of models may yield invalid results. The known equivalent vector autoregressive model types, standard and structural, are given a new interpretation in which they are conceived of as the extremes of an innovating type of hybrid vector autoregressive models. It is shown that consideration of hybrid models solves many problems, in particular with Granger causality testing.
Computer-aided engineering of semiconductor integrated circuits
Meindl, J. D.; Dutton, R. W.; Gibbons, J. F.; Helms, C. R.; Plummer, J. D.; Tiller, W. A.; Ho, C. P.; Saraswat, K. C.; Deal, B. E.; Kamins, T. I.
1980-07-01
Economical procurement of small quantities of high performance custom integrated circuits for military systems is impeded by inadequate process, device and circuit models that handicap low cost computer aided design. The principal objective of this program is to formulate physical models of fabrication processes, devices and circuits to allow total computer-aided design of custom large-scale integrated circuits. The basic areas under investigation are (1) thermal oxidation, (2) ion implantation and diffusion, (3) chemical vapor deposition of silicon and refractory metal silicides, (4) device simulation and analytic measurements. This report discusses the fourth year of the program.
Impedance measurements on YB/sub 2/Cu/sub 3/O/sub 7-delta) interpretation and trapping parameters
International Nuclear Information System (INIS)
Yasmeen, S.; Mohammad, M.; Khan, A.Y.; Subhani, M.S.
1997-01-01
Two probe impedance spectroscopic studies were carried out on YBa/sub 2/Cu/sub 3/ O/sub 7-delta/ two different sintering conditions i.e. at before final sintering and at after final sintering. In both condition ac impedance studies were done in the frequency range of 1Hz to 100kHz and at different temperatures from room temperature down to 78K. Measurements were done with contacts opposite side (i.e., ceramic behaves as a resister) as well as on opposite sides (i.e., ceramic behaves as a capacitor). Results were obtained in the form of Nyquist plot. Log, Yi/omega Vs log f plot and Yr/omega Vs log f plot. These plots were explained through equivalent circuits. The bulk resistance Rb, the grain boundary resistance R/sub b/ and grain boundary capacitance C/sub gb/ were obtained through these plots. The ac conductivities were also obtained at all temperatures. The log sigma g Vs log omega (frequency) plots were interpreted invoking the theory of ac conductivity in polycrystalline solids. The trapping parameters (binding energy, the hopping distance etc.) were calculated and interpreted. (author)
Farmann, Alexander; Waag, Wladislaw; Sauer, Dirk Uwe
2015-12-01
Robust algorithms using reduced order equivalent circuit model (ECM) for an accurate and reliable estimation of battery states in various applications become more popular. In this study, a novel adaptive, self-learning heuristic algorithm for on-board impedance parameters and voltage estimation of lithium-ion batteries (LIBs) in electric vehicles is introduced. The presented approach is verified using LIBs with different composition of chemistries (NMC/C, NMC/LTO, LFP/C) at different aging states. An impedance-based reduced order ECM incorporating ohmic resistance and a combination of a constant phase element and a resistance (so-called ZARC-element) is employed. Existing algorithms in vehicles are much more limited in the complexity of the ECMs. The algorithm is validated using seven day real vehicle data with high temperature variation including very low temperatures (from -20 °C to +30 °C) at different Depth-of-Discharges (DoDs). Two possibilities to approximate both ZARC-elements with finite number of RC-elements on-board are shown and the results of the voltage estimation are compared. Moreover, the current dependence of the charge-transfer resistance is considered by employing Butler-Volmer equation. Achieved results indicate that both models yield almost the same grade of accuracy.
Elhatimi, Wafaa; Bouragba, Fatima Zahra; Lahkale, Redouane; Sadik, Rachid; Lebbar, Nacira; Siniti, Mostapha; Sabbar, Elmouloudi
2018-05-01
The Cu2Cr-DS-LDH hybrid was successfully prepared by the anion exchange method at room temperature. The structure, the chemical composition and the physico-chemical properties of the sample were determined using powder X-ray diffraction (PXRD), Fourier transform infrared spectroscopy (FT-IR), thermogravimetric analysis (TGA) and inductively coupled plasma (ICP). In this work, the electrical and dielectric properties investigated are determined using impedance spectroscopy (IS) in a frequency range of 1 Hz to 1 MHz. Indeed, the Nyquist diagram modelized by an electrical equivalent circuit showed three contributions attributed respectively to the polarization of grains, grains boundaries and interface electrode-sample. This modelization allowed us to determine the intrinsic electrical parameters of the hybrid (resistance, pseudo-capacitance and relaxation time). The presence of the non-Debye relaxation phenomena was confirmed by the frequency analysis of impedance. Moreover, the evolution of the alternating current conductivity (σac) studied obeys the double power law of Jonscher. The ionic conduction of this material was generated through a jump movement by translation of the charge carriers. As for the dielectric behavior of the material, the evolution of dielectric constant as a function of frequency shows relatively high values in a frequency range between 10 Hz and 1 KHz. The low values of the loss tangent obtained in this frequency zone can valorize this LDH hybrid.
Commutation circuit for an HVDC circuit breaker
Premerlani, William J.
1981-01-01
A commutation circuit for a high voltage DC circuit breaker incorporates a resistor capacitor combination and a charging circuit connected to the main breaker, such that a commutating capacitor is discharged in opposition to the load current to force the current in an arc after breaker opening to zero to facilitate arc interruption. In a particular embodiment, a normally open commutating circuit is connected across the contacts of a main DC circuit breaker to absorb the inductive system energy trapped by breaker opening and to limit recovery voltages to a level tolerable by the commutating circuit components.
Introduction of circuit design on RFID system
International Nuclear Information System (INIS)
Pak, Sunho
2007-06-01
This is a case of research of Fujitsu company and design of basic circuit of electronic technique. It is composed of two parts. The first part deals with introduction of RFID system design, which lists basic knowledge of ubiquitous, glossary of high frequency, design of impedance matching circuit, RFID system, sorts and design of filter, modulator and a transmission and RFID system design. The second part deals with research and development of Fujitsu company, including RFID middle ware RFID CONNECT of Fujitsu, sensor network of Fujitsu and high handing technique of RFID system.
Introduction of circuit design on RFID system
Energy Technology Data Exchange (ETDEWEB)
Pak, Sunho
2007-06-15
This is a case of research of Fujitsu company and design of basic circuit of electronic technique. It is composed of two parts. The first part deals with introduction of RFID system design, which lists basic knowledge of ubiquitous, glossary of high frequency, design of impedance matching circuit, RFID system, sorts and design of filter, modulator and a transmission and RFID system design. The second part deals with research and development of Fujitsu company, including RFID middle ware RFID CONNECT of Fujitsu, sensor network of Fujitsu and high handing technique of RFID system.
Effect of temperature on the AC impedance of protein
Indian Academy of Sciences (India)
The depression parameter reveals the electrical equivalent circuit for the biopolymers. The AC electrical conductivity in the biopolymers follows the universal power law. From this, it is observed that the AC conductivity is frequency dependent and the biopolymer papain obeys large polaron tunnelling model, gum acacia and ...
Effect of temperature on the AC impedance of protein and ...
Indian Academy of Sciences (India)
2016-08-26
Aug 26, 2016 ... The depression parameter reveals the electrical equivalent circuit for the biopolymers. The AC electrical conductivity in the biopolymers follows the universal power law. From this, it is observed that the AC conductivity is frequency dependent and the biopolymer papain obeys large polaron tunnelling model ...
Remote tuning of NMR probe circuits.
Kodibagkar, V D; Conradi, M S
2000-05-01
There are many circumstances in which the probe tuning adjustments cannot be located near the rf NMR coil. These may occur in high-temperature NMR, low-temperature NMR, and in the use of magnets with small diameter access bores. We address here circuitry for connecting a fixed-tuned probe circuit by a transmission line to a remotely located tuning network. In particular, the bandwidth over which the probe may be remotely tuned while keeping the losses in the transmission line acceptably low is considered. The results show that for all resonant circuit geometries (series, parallel, series-parallel), overcoupling of the line to the tuned circuit is key to obtaining a large tuning bandwidth. At equivalent extents of overcoupling, all resonant circuit geometries have nearly equal remote tuning bandwidths. Particularly for the case of low-loss transmission line, the tuning bandwidth can be many times the tuned circuit's bandwidth, f(o)/Q. Copyright 2000 Academic Press.
Analog circuit design designing dynamic circuit response
Feucht, Dennis
2010-01-01
This second volume, Designing Dynamic Circuit Response builds upon the first volume Designing Amplifier Circuits by extending coverage to include reactances and their time- and frequency-related behavioral consequences.
International Nuclear Information System (INIS)
Verity, P.R.; Chaplain, M.D.; Turner, G.D.J.
1984-01-01
A monostable trigger circuit comprises transistors TR2 and TR3 arranged with their collectors and bases interconnected. The collector of the transistor TR2 is connected to the base of transistor TR3 via a capacitor C2 the main current path of a grounded base transistor TR1 and resistive means R2,R3. The collector of transistor TR3 is connected to the base of transistor TR2 via resistive means R6, R7. In the stable state all the transistors are OFF, the capacitor C2 is charged, and the output is LOW. A positive pulse input to the base of TR2 switches it ON, which in turn lowers the voltage at points A and B and so switches TR1 ON so that C2 can discharge via R2, R3, which in turn switches TR3 ON making the output high. Thus all three transistors are latched ON. When C2 has discharged sufficiently TR1 switches OFF, followed by TR3 (making the output low again) and TR2. The components C1, C3 and R4 serve to reduce noise, and the diode D1 is optional. (author)
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...... for current-type inverters. These impedance networks can in principle be combined into two generic network entities, before multiple of them can further be connected together by applying any of the two proposed generalized cascading concepts. The resulting two-level and three-level inverters implemented using...
International Nuclear Information System (INIS)
Park, S. Y.; Lee, M. H.; Choi, B. K.; Jung, Y. H.; Jung, Y. H.
2000-01-01
As a part of the advanced Zr fuel cladding development program, the autoclave corrosion test was performed on the series of Zr-0.2Nb-1.1Sn-Fe-Cu and Zr-0.4Nb-0.8Sn-Fe-Cu alloys in 70 ppm LiOH solution at 360 .deg. C. The oxide characteristics were investigated by using the Electrochemical Impedance Spectroscope(EIS) method. The corrosion resistance of the alloys was evaluated from the corrosion rate determined as a function of the concentration of main alloying elements such as Nb, Sn, Fe and Cu. The equivalent circuit was composed as a result of the spectrum from EIS measurements on the oxide layer that formed at pro- and post-transition regions. By using the capacitance characteristics of equivalent circuit, the thickness of impervious layer, it's electrical resistance and characteristics of space charge layer were evaluated. The corrosion characteristics of the Zr-Nb-Sn-Fe-Cu alloys were successfully explained by applying the EIS test results
International Nuclear Information System (INIS)
Blajiev, O.L.; Breugelmans, T.; Pintelon, R.; Hubin, A.
2006-01-01
The electrochemical behavior of copper in chloride solutions containing 0.001 M concentrations of small five- and six-ring member heterocyclic molecules was investigated by means of impedance spectroscopy. The investigation was performed by a new technique based on a broadband multisine excitation. This method allows for a quantification and separation of the measurement and stohastic nonlinear noises and for an estimation of the bias non-linear contribution. It as well reduces the perturbation brought to studied system by the measurement process itself. The measurement data for some experimental conditions was quantified by fitting into a equivalent circuit corresponding to a physical model both of them developed earlier. In general, the experimental results obtained show that the number of atoms in the heterocyclic ring and the molecular conformation have a significant influence on the electrochemical response of copper in the investigated environments
An electrochemical impedance model for integrated bacterial biofilms
International Nuclear Information System (INIS)
Ben-Yoav, Hadar; Freeman, Amihay; Sternheim, Marek; Shacham-Diamand, Yosi
2011-01-01
Bacterial cells attachment onto solid surfaces and the following growth into mature microbial biofilms may result in highly antibiotic resistant biofilms. Such biofilms may be incidentally formed on tissues or implanted devices, or intentionally formed by directed deposition of microbial sensors on whole-cell bio-chip surface. A new method for electrical characterization of the later on-chip microbial biofilm buildup is presented in this paper. Measurement of impedance vs. frequency in the range of 100 mHz to 400 kHz of Escherichia coli cells attachment to indium-tin-oxide-coated electrodes was carried out while using optical microscopy estimating the electrode area coverage. We show that impedance spectroscopy measurements can be interpreted by a simple electrical equivalent model characterizing both attachment and growth of the biofilm. The correlation of extracted equivalent electrical lumped components with the visual biofilm parameters and their dependence on the attachment and growth phases is confirmed.
Establishing Substantial Equivalence: Transcriptomics
Baudo, María Marcela; Powers, Stephen J.; Mitchell, Rowan A. C.; Shewry, Peter R.
Regulatory authorities in Western Europe require transgenic crops to be substantially equivalent to conventionally bred forms if they are to be approved for commercial production. One way to establish substantial equivalence is to compare the transcript profiles of developing grain and other tissues of transgenic and conventionally bred lines, in order to identify any unintended effects of the transformation process. We present detailed protocols for transcriptomic comparisons of developing wheat grain and leaf material, and illustrate their use by reference to our own studies of lines transformed to express additional gluten protein genes controlled by their own endosperm-specific promoters. The results show that the transgenes present in these lines (which included those encoding marker genes) did not have any significant unpredicted effects on the expression of endogenous genes and that the transgenic plants were therefore substantially equivalent to the corresponding parental lines.
Transcranial extracellular impedance control (tEIC modulates behavioral performances.
Directory of Open Access Journals (Sweden)
Ayumu Matani
Full Text Available Electric brain stimulations such as transcranial direct current stimulation (tDCS, transcranial random noise stimulation (tRNS, and transcranial alternating current stimulation (tACS electrophysiologically modulate brain activity and as a result sometimes modulate behavioral performances. These stimulations can be viewed from an engineering standpoint as involving an artificial electric source (DC, noise, or AC attached to an impedance branch of a distributed parameter circuit. The distributed parameter circuit is an approximation of the brain and includes electric sources (neurons and impedances (volume conductors. Such a brain model is linear, as is often the case with the electroencephalogram (EEG forward model. Thus, the above-mentioned current stimulations change the current distribution in the brain depending on the locations of the electric sources in the brain. Now, if the attached artificial electric source were to be replaced with a resistor, or even a negative resistor, the resistor would also change the current distribution in the brain. In light of the superposition theorem, which holds for any linear electric circuit, attaching an electric source is different from attaching a resistor; the resistor affects each active electric source in the brain so as to increase (or decrease in some cases of a negative resistor the current flowing out from each source. From an electrophysiological standpoint, the attached resistor can only control the extracellular impedance and never causes forced stimulation; we call this technique transcranial extracellular impedance control (tEIC. We conducted a behavioral experiment to evaluate tEIC and found evidence that it had real-time enhancement and depression effects on EEGs and a real-time facilitation effect on reaction times. Thus, tEIC could be another technique to modulate behavioral performance.
Directory of Open Access Journals (Sweden)
Ulises Acevedo
2017-05-01
Full Text Available Granular BaTiO3-CoFe2O4 (BTO-CFO nanocomposites were prepared by combining polyol synthesis and spark plasma sintering (SPS. This method allows samples with a high density and a very small grain size (less than 150 nm, and thus a large interface area between phases. In order to study the involved magnetoelectric effects, the impedance response of these nanomaterials was measured in the 5 Hz-10 MHz frequency range, under 0-7.5 kOe magnetic applied fields, and in the 40-170°C temperature range. The best agreement to model these results by an equivalent circuit was achieved by means of three parallel RC arrangements connected in series; by their RC values, these circuits are representative of grain boundaries. An association between each RC circuit and each interface (or grain boundary, i. e., BTO-BTO, BTO-CFO, and CFO-CFO, is proposed on the basis of their temperature and magnetic behavior.
Circuit for automatic load sharing in parallel converter modules
Nagano, S. (Inventor)
1979-01-01
A nondissipative circuit for automatic load sharing in parallel converter modules having push-pull power transistors is presented. Each transistor has a separate current-sensing transformer and an impedance-adjusting transformer in series with its collector. The impedance-adjusting transformer functions as a current-controlled variable impedance that is responsive to the difference between the peak collector current of the transistor and the average peak current of all collector currents of power transistors in all modules, thereby to control the collector currents of all power transistors with reference to the average peak collector current.
International Nuclear Information System (INIS)
Unnikrishnan, C.S.
1994-01-01
Principle of equivalence was the fundamental guiding principle in the formulation of the general theory of relativity. What are its key elements? What are the empirical observations which establish it? What is its relevance to some new experiments? These questions are discussed in this article. (author). 11 refs., 5 figs
International Nuclear Information System (INIS)
Orlowski, S.; Schaller, K.H.
1990-01-01
The report reviews, for the Member States of the European Community, possible situations in which an equivalence concept for radioactive waste may be used, analyses the various factors involved, and suggests guidelines for the implementation of such a concept. Only safety and technical aspects are covered. Other aspects such as commercial ones are excluded. Situations where the need for an equivalence concept has been identified are processes where impurities are added as a consequence of the treatment and conditioning process, the substitution of wastes from similar waste streams due to the treatment process, and exchange of waste belonging to different waste categories. The analysis of factors involved and possible ways for equivalence evaluation, taking into account in particular the chemical, physical and radiological characteristics of the waste package, and the potential risks of the waste form, shows that no simple all-encompassing equivalence formula may be derived. Consequently, a step-by-step approach is suggested, which avoids complex evaluations in the case of simple exchanges
Equivalent Colorings with "Maple"
Cecil, David R.; Wang, Rongdong
2005-01-01
Many counting problems can be modeled as "colorings" and solved by considering symmetries and Polya's cycle index polynomial. This paper presents a "Maple 7" program link http://users.tamuk.edu/kfdrc00/ that, given Polya's cycle index polynomial, determines all possible associated colorings and their partitioning into equivalence classes. These…
Correspondences. Equivalence relations
International Nuclear Information System (INIS)
Bouligand, G.M.
1978-03-01
We comment on sections paragraph 3 'Correspondences' and paragraph 6 'Equivalence Relations' in chapter II of 'Elements de mathematique' by N. Bourbaki in order to simplify their comprehension. Paragraph 3 exposes the ideas of a graph, correspondence and map or of function, and their composition laws. We draw attention to the following points: 1) Adopting the convention of writting from left to right, the composition law for two correspondences (A,F,B), (U,G,V) of graphs F, G is written in full generality (A,F,B)o(U,G,V) = (A,FoG,V). It is not therefore assumed that the co-domain B of the first correspondence is identical to the domain U of the second (EII.13 D.7), (1970). 2) The axiom of choice consists of creating the Hilbert terms from the only relations admitting a graph. 3) The statement of the existence theorem of a function h such that f = goh, where f and g are two given maps having the same domain (of definition), is completed if h is more precisely an injection. Paragraph 6 considers the generalisation of equality: First, by 'the equivalence relation associated with a map f of a set E identical to (x is a member of the set E and y is a member of the set E and x:f = y:f). Consequently, every relation R(x,y) which is equivalent to this is an equivalence relation in E (symmetrical, transitive, reflexive); then R admits a graph included in E x E, etc. Secondly, by means of the Hilbert term of a relation R submitted to the equivalence. In this last case, if R(x,y) is separately collectivizing in x and y, theta(x) is not the class of objects equivalent to x for R (EII.47.9), (1970). The interest of bringing together these two subjects, apart from this logical order, resides also in the fact that the theorem mentioned in 3) can be expressed by means of the equivalence relations associated with the functions f and g. The solutions of the examples proposed reveal their simplicity [fr
Label-Free Aptasensor for Lysozyme Detection Using Electrochemical Impedance Spectroscopy
Directory of Open Access Journals (Sweden)
Dionisia Ortiz-Aguayo
2018-01-01
Full Text Available This research develops a label-free aptamer biosensor (aptasensor based on graphite-epoxy composite electrodes (GECs for the detection of lysozyme protein using Electrochemical Impedance Spectroscopy (EIS technique. The chosen immobilization technique was based on covalent bonding using carbodiimide chemistry; for this purpose, carboxylic moieties were first generated on the graphite by electrochemical grafting. The detection was performed using [Fe(CN6]3−/[Fe(CN6]4− as redox probe. After recording the frequency response, values were fitted to its electric model using the principle of equivalent circuits. The aptasensor showed a linear response up to 5 µM for lysozyme and a limit of detection of 1.67 µM. The sensitivity of the established method was 0.090 µM−1 in relative charge transfer resistance values. The interference response by main proteins, such as bovine serum albumin and cytochrome c, has been also characterized. To finally verify the performance of the developed aptasensor, it was applied to wine analysis.
Label-Free Aptasensor for Lysozyme Detection Using Electrochemical Impedance Spectroscopy.
Ortiz-Aguayo, Dionisia; Del Valle, Manel
2018-01-26
This research develops a label-free aptamer biosensor (aptasensor) based on graphite-epoxy composite electrodes (GECs) for the detection of lysozyme protein using Electrochemical Impedance Spectroscopy (EIS) technique. The chosen immobilization technique was based on covalent bonding using carbodiimide chemistry; for this purpose, carboxylic moieties were first generated on the graphite by electrochemical grafting. The detection was performed using [Fe(CN)₆] 3- /[Fe(CN)₆] 4- as redox probe. After recording the frequency response, values were fitted to its electric model using the principle of equivalent circuits. The aptasensor showed a linear response up to 5 µM for lysozyme and a limit of detection of 1.67 µM. The sensitivity of the established method was 0.090 µM -1 in relative charge transfer resistance values. The interference response by main proteins, such as bovine serum albumin and cytochrome c, has been also characterized. To finally verify the performance of the developed aptasensor, it was applied to wine analysis.
Electrochemical Impedance Analysis of a PEDOT:PSS-Based Textile Energy Storage Device
Directory of Open Access Journals (Sweden)
Ida Nuramdhani
2017-12-01
Full Text Available A textile-based energy storage device with electroactive PEDOT:PSS (poly(3,4-ethylenedioxythiophene/poly(4-styrenesulfonate polymer functioning as a solid-state polyelectrolyte has been developed. The device was fabricated on textile fabric with two plies of stainless-steel electroconductive yarn as the electrodes. In this study, cyclic voltammetry and electrochemical impedance analysis were used to investigate ionic and electronic activities in the bulk of PEDOT:PSS and at its interfaces with stainless steel yarn electrodes. The complex behavior of ionic and electronic origins was observed in the interfacial region between the conductive polymer and the electrodes. The migration and diffusion of the ions involved were confirmed by the presence of the Warburg element with a phase shift of 45° (n = 0.5. Two different equivalent circuit models were found by simulating the model with the experimental results: (QR(QR(QR for uncharged and (QR(QR(Q(RW for charged samples. The analyses also showed that the further the distance between electrodes, the lower the capacitance of the cell. The distribution of polymer on the cell surface also played important role to change the capacitance of the device. The results of this work may lead to a better understanding of the mechanism and how to improve the performance of the device.
Impedance based time-domain modeling of lithium-ion batteries: Part I
Gantenbein, Sophia; Weiss, Michael; Ivers-Tiffée, Ellen
2018-03-01
This paper presents a novel lithium-ion cell model, which simulates the current voltage characteristic as a function of state of charge (0%-100%) and temperature (0-30 °C). It predicts the cell voltage at each operating point by calculating the total overvoltage from the individual contributions of (i) the ohmic loss η0, (ii) the charge transfer loss of the cathode ηCT,C, (iii) the charge transfer loss and the solid electrolyte interface loss of the anode ηSEI/CT,A, and (iv) the solid state and electrolyte diffusion loss ηDiff,A/C/E. This approach is based on a physically meaningful equivalent circuit model, which is parametrized by electrochemical impedance spectroscopy and time domain measurements, covering a wide frequency range from MHz to μHz. The model is exemplarily parametrized to a commercial, high-power 350 mAh graphite/LiNiCoAlO2-LiCoO2 pouch cell and validated by continuous discharge and charge curves at varying temperature. For the first time, the physical background of the model allows the operator to draw conclusions about the performance-limiting factor at various operating conditions. Not only can the model help to choose application-optimized cell characteristics, but it can also support the battery management system when taking corrective actions during operation.
Simulations of a dense plasma focus on a high impedance generator
Beresnyak, Andrey; Giuliani, John; Jackson, Stuart; Richardson, Steve; Swanekamp, Steve; Schumer, Joe; Commisso, Robert; Mosher, Dave; Weber, Bruce; Velikovich, Alexander
2017-10-01
We study the connection between plasma instabilities and fast ion acceleration for neutron production on a Dense Plasma Focus (DPF). The experiments will be performed on the HAWK generator (665 kA), which has fast rise time, 1.2 μs, and a high inductance, 607 nH. It is hypothesized that high impedance may enhance the neutron yield because the current will not be reduced during the collapse resulting in higher magnetization. To prevent upstream breakdown, we will inject plasma far from the insulator stack. We simulated rundown and collapse dynamics with Athena - Eulerian 3D, unsplit finite volume MHD code that includes shock capturing with Riemann solvers, resistive diffusion and the Hall term. The simulations are coupled to an equivalent circuit model for HAWK. We will report the dynamics and implosion time as a function of the initial injected plasma distribution and the implications of non-ideal effects. We also traced test particles in MHD fields and confirmed the presence of stochastic acceleration, which was limited by the size of the system and the strength of the magnetic field. Supported by DOE/NNSA and the Naval Research Laboratory Base Program.
Device, system and method for a sensing electrical circuit
Vranish, John M. (Inventor)
2009-01-01
The invention relates to a driven ground electrical circuit. A driven ground is a current-measuring ground termination to an electrical circuit with the current measured as a vector with amplification. The driven ground module may include an electric potential source V.sub.S driving an electric current through an impedance (load Z) to a driven ground. Voltage from the source V.sub.S excites the minus terminal of an operational amplifier inside the driven ground which, in turn, may react by generating an equal and opposite voltage to drive the net potential to approximately zero (effectively ground). A driven ground may also be a means of passing information via the current passing through one grounded circuit to another electronic circuit as input. It may ground one circuit, amplify the information carried in its current and pass this information on as input to the next circuit.
Longitudinal coupling impedance of a hole in the accelerator beam pipe
International Nuclear Information System (INIS)
Chae, Yong-Chul.
1993-12-01
In the design of modern accelerators, an accurate estimate of coupling impedance is very important. The sources which give rise to coupling impedance are the geometric discontinuities in the accelerator beam pipe. In various discontinuities such as RF cavities, bellows, and collimators, the coupling impedance of the holes has not been well understood. Although coupling impedance can be obtained in general from the Fourier transform of the corresponding wake potential which may be obtained numerically, this is time consuming and requires a large amount of computer storage when applied to a small dimension of a discontinuity in a typical beam pipe, often imposing a fundamental limitation of the numerical approach. More fundamentally, however, numerical calculation does not have the predictive power because of limited understanding of how the coupling impedance of a hole should behave over a wide frequency range. This question was studied by developing a theoretical analysis based on a variational method. An analytical formula for the coupling impedance of a hole is developed in this work using a variational method. The result gives good qualitative agreements with the coupling impedances evaluated numerically from the Fourier transform of the wake potential which is obtained from the computer code MAFIA-T3. The author shows that the coupling impedance of a hole behaves quite similar to the impedance of an RLC-resonator circuit. Important parameters used to describe such a resonator circuit are the resonant frequency and bandwidth. The author provides a theoretical insight on how to parameterize properly the numerical impedance of a hole when data exhibit complicated dependence on frequency. This is possible because one can show that the parameters are a function of the dimensionless quantity kd alone, with k the free-space wave number and d the radius of hole
Impedance Discontinuity Reduction Between High-Speed Differential Connectors and PCB Interfaces
Navidi, Sal; Agdinaoay, Rodell; Walter, Keith
2013-01-01
High-speed serial communication (i.e., Gigabit Ethernet) requires differential transmission and controlled impedances. Impedance control is essential throughout cabling, connector, and circuit board construction. An impedance discontinuity arises at the interface of a high-speed quadrax and twinax connectors and the attached printed circuit board (PCB). This discontinuity usually is lower impedance since the relative dielectric constant of the board is higher (i.e., polyimide approx. = 4) than the connector (Teflon approx. = 2.25). The discontinuity can be observed in transmit or receive eye diagrams, and can reduce the effective link margin of serial data networks. High-speed serial data network transmission improvements can be made at the connector-to-board interfaces as well as improving differential via hole impedances. The impedance discontinuity was improved by 10 percent by drilling a 20-mil (approx. = 0.5-mm) hole in between the pin of a differential connector spaced 55 mils (approx. = 1.4 mm) apart as it is attached to the PCB. The effective dielectric constant of the board can be lowered by drilling holes into the board material between the differential lines in a quadrax or twinax connector attachment points. The differential impedance is inversely proportional to the square root of the relative dielectric constant. This increases the differential impedance and thus reduces the above described impedance discontinuity. The differential via hole impedance can also be increased in the same manner. This technique can be extended to multiple smaller drilled holes as well as tapered holes (i.e., big in the middle followed by smaller ones diagonally).
Fractional-order RC and RL circuits
Radwan, Ahmed Gomaa
2012-05-30
This paper is a step forward to generalize the fundamentals of the conventional RC and RL circuits in fractional-order sense. The effect of fractional orders is the key factor for extra freedom, more flexibility, and novelty. The conditions for RC and RL circuits to act as pure imaginary impedances are derived, which are unrealizable in the conventional case. In addition, the sensitivity analyses of the magnitude and phase response with respect to all parameters showing the locations of these critical values are discussed. A qualitative revision for the fractional RC and RL circuits in the frequency domain is provided. Numerical and PSpice simulations are included to validate this study. © Springer Science+Business Media, LLC 2012.
Microwave integrated circuit for Josephson voltage standards
Holdeman, L. B.; Toots, J.; Chang, C. C. (Inventor)
1980-01-01
A microwave integrated circuit comprised of one or more Josephson junctions and short sections of microstrip or stripline transmission line is fabricated from thin layers of superconducting metal on a dielectric substrate. The short sections of transmission are combined to form the elements of the circuit and particularly, two microwave resonators. The Josephson junctions are located between the resonators and the impedance of the Josephson junctions forms part of the circuitry that couples the two resonators. The microwave integrated circuit has an application in Josephson voltage standards. In this application, the device is asymmetrically driven at a selected frequency (approximately equal to the resonance frequency of the resonators), and a d.c. bias is applied to the junction. By observing the current voltage characteristic of the junction, a precise voltage, proportional to the frequency of the microwave drive signal, is obtained.
Santiago, John
2013-01-01
Circuits overloaded from electric circuit analysis? Many universities require that students pursuing a degree in electrical or computer engineering take an Electric Circuit Analysis course to determine who will ""make the cut"" and continue in the degree program. Circuit Analysis For Dummies will help these students to better understand electric circuit analysis by presenting the information in an effective and straightforward manner. Circuit Analysis For Dummies gives you clear-cut information about the topics covered in an electric circuit analysis courses to help
Current limiter circuit system
Witcher, Joseph Brandon; Bredemann, Michael V.
2017-09-05
An apparatus comprising a steady state sensing circuit, a switching circuit, and a detection circuit. The steady state sensing circuit is connected to a first, a second and a third node. The first node is connected to a first device, the second node is connected to a second device, and the steady state sensing circuit causes a scaled current to flow at the third node. The scaled current is proportional to a voltage difference between the first and second node. The switching circuit limits an amount of current that flows between the first and second device. The detection circuit is connected to the third node and the switching circuit. The detection circuit monitors the scaled current at the third node and controls the switching circuit to limit the amount of the current that flows between the first and second device when the scaled current is greater than a desired level.
International Nuclear Information System (INIS)
Veltman, H.
1990-01-01
The equivalence theorem states that, at an energy E much larger than the vector-boson mass M, the leading order of the amplitude with longitudinally polarized vector bosons on mass shell is given by the amplitude in which these vector bosons are replaced by the corresponding Higgs ghosts. We prove the equivalence theorem and show its validity in every order in perturbation theory. We first derive the renormalized Ward identities by using the diagrammatic method. Only the Feynman-- 't Hooft gauge is discussed. The last step of the proof includes the power-counting method evaluated in the large-Higgs-boson-mass limit, needed to estimate the leading energy behavior of the amplitudes involved. We derive expressions for the amplitudes involving longitudinally polarized vector bosons for all orders in perturbation theory. The fermion mass has not been neglected and everything is evaluated in the region m f ∼M much-lt E much-lt m Higgs
Measurements of the dynamic input impedance of a dc SQUID
International Nuclear Information System (INIS)
Hilbert, C.; Clarke, J.
1985-01-01
The impedance of a circuit coupled magnetically via a mutual inductance M/sub i/ to a dc SQUID of geometric inductance L is modified by the dynamic input impedance of the SQUID, which can be characterized by the flux-to-current transfer function J/sub Phi/approx. =partialJ/partialPhi; J is the current circulating in the SQUID loop and ∫ is the flux applied to the loop. At the same time, the SQUID is modified by the presence of the input circuit in the lumped circuit approximation, one expects its inductance to be reduced to L'(1-α/sub e/ 2 )L, where α/sub e/ is an effective coupling coefficient. Calculations of J/sub Phi/ using an analog simulator are described and presented in the form of a dynamic inductance L and a dynamic resistance R versus bias current I and Phi. Experimental measurements of L and R were made on a planar, thin-film SQUID tightly coupled to a spiral input coil that was connected in series with a capacitor C/sub i/ to form a resonant circuit. Thus, J/sub Phi/ was determined from the change in the resonant frequency and quality factor of this circuit as a function of I and Phi. At low bias currents (low Josephson frequencies) the measured values of L were in reasonable agreement with values simulated for the reduced SQUID, while at higher bias currents (higher Josephson frequencies) the measured values were in better agreement with values simulated for the unscreened SQUID. Similar conclusions were reached in the comparison of the experimental and simulated values of the flux-to-voltage transfer function V/sub Phi/
Impedance matching wireless power transmission system for biomedical devices.
Lum, Kin Yun; Lindén, Maria; Tan, Tian Swee
2015-01-01
For medical application, the efficiency and transmission distance of the wireless power transfer (WPT) are always the main concern. Research has been showing that the impedance matching is one of the critical factors for dealing with the problem. However, there is not much work performed taking both the source and load sides into consideration. Both sides matching is crucial in achieving an optimum overall performance, and the present work proposes a circuit model analysis for design and implementation. The proposed technique was validated against experiment and software simulation. Result was showing an improvement in transmission distance up to 6 times, and efficiency at this transmission distance had been improved up to 7 times as compared to the impedance mismatch system. The system had demonstrated a near-constant transfer efficiency for an operating range of 2cm-12cm.
Fast FPGA Implementation of an Original Impedance Analyser
Directory of Open Access Journals (Sweden)
Abdulrahman HAMED
2011-02-01
Full Text Available This article describes in detail the design and rapid prototyping of an embedded impedance analyzer. The measurement principle is based on the feedback control of the excitation voltage VD during a fast frequency sweeping. This function is carried out by a high precision synthesizer whose output resistance RG is digitally adjustable. Real and imaginary parts of the dipole impedance are determined from RG and the phase of VD. The digital architecture design uses the hardware-in-the-loop simulation in which the dipole is modeled using an RLC parallel circuit and a Butterworth Van Dyke structure. All digital functions are implemented on a Stratix II FPGA board with a 100 MHz frequency clock. The parameters taken into account are the frequency range (0 to 5 MHz, speed and resolution of the analysis and the quality factor of the resonant dipole. To reduce the analysis duration, the frequency sweeping rate is adjusted in real time.
Time-domain representation of frequency-dependent foundation impedance functions
Safak, E.
2006-01-01
Foundation impedance functions provide a simple means to account for soil-structure interaction (SSI) when studying seismic response of structures. Impedance functions represent the dynamic stiffness of the soil media surrounding the foundation. The fact that impedance functions are frequency dependent makes it difficult to incorporate SSI in standard time-history analysis software. This paper introduces a simple method to convert frequency-dependent impedance functions into time-domain filters. The method is based on the least-squares approximation of impedance functions by ratios of two complex polynomials. Such ratios are equivalent, in the time-domain, to discrete-time recursive filters, which are simple finite-difference equations giving the relationship between foundation forces and displacements. These filters can easily be incorporated into standard time-history analysis programs. Three examples are presented to show the applications of the method.
An Islanding Microgrid Power Sharing Approach Using Enhanced Virtual Impedance Control Scheme
DEFF Research Database (Denmark)
He, Jinwei; Li, Yun Wei; Guerrero, Josep M.
2013-01-01
In order to address the load sharing problem in islanding microgrids, this paper proposes an enhanced distributed generation (DG) unit virtual impedance control approach. The proposed method can realize accurate regulation of DG unit equivalent impedance at both fundamental and selected harmonic...... and PCC harmonic voltage compensation are achieved without using any fundamental and harmonic components extractions. Experimental results from a scaled single-phase microgrid prototype are provided to validate the feasibility of the proposed virtual impedance control approach....... frequencies. In contrast to conventional virtual impedance control methods, where only a line current feed-forward term is added to the DG voltage reference, the proposed virtual impedance at fundamental and harmonic frequencies is regulated using DG line current and point of common coupling (PCC) voltage...
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...
Active Match Load Circuit Intended for Testing Piezoelectric Transformers
DEFF Research Database (Denmark)
Andersen, Thomas; Rødgaard, Martin Schøler; Andersen, Michael A. E.
2012-01-01
An adjustable high voltage active load circuit for voltage amplitudes above 100 volts, especially intended for resistive matching the output impedance of a piezoelectric transformer (PT) is proposed in this paper. PTs have been around for over 50 years, were C. A. Rosen is common known for his...
Efficient/reliable dc-to-dc inverter circuit
Pasciutti, E. R.
1970-01-01
Feedback loop, which contains an inductor in series with a saturable reactor, is added to a standard inverter circuit to permit the inverter power transistors to be switched in a controlled and efficient manner. This inverter is applicable where the power source has either high or low impedance properties.
Supplementary High-Input Impedance Voltage-Mode Universal Biquadratic Filter Using DVCCs
Directory of Open Access Journals (Sweden)
Jitendra Mohan
2012-01-01
Full Text Available To further extend the existing knowledge on voltage-mode universal biquadratic filter, in this paper, a new biquadratic filter circuit with single input and multiple outputs is proposed, employing three differential voltage current conveyors (DVCCs, three resistors, and two grounded capacitors. The proposed circuit realizes all the standard filter functions, that is, high-pass, band-pass, low-pass, notch, and all-pass filters simultaneously. The circuit enjoys the feature of high-input impedance, orthogonal control of resonance angular frequency (o, and quality factor (Q via grounded resistor and the use of grounded capacitors which is ideal for IC implementation.
Comparison of on-wafer calibrations using the concept of reference impedance
Purroy Martín, Francesc; Pradell i Cara, Lluís
1993-01-01
A novel method that allows to compare different calibration techniques has been developed. It is based on determining the reference impedance of a given Network Analyzer calibration from the reflection coefficient measurement of a physical open circuit. The method has been applied to several on-wafer calibrations. Peer Reviewed
Unbalanced Impedance of the Aperture Coils of Some LHC Main Dipole Magnets
Ravaioli, Emanuele; Verweij, A.P.; ten Kate, Herman H.J.
2013-01-01
During the Large Hadron Collider operation in 2010 and 2011, it was observed that about 50% of the main dipole magnets exhibiting two apertures showed unbalanced dynamic-impedance behavior not well understood. When a main dipole circuit is switched off, voltage waves with a frequency of 28 Hz travel
Negative Resistance Circuit for Damping an Array of Coupled FitzHugh-Nagumo Oscillators
DEFF Research Database (Denmark)
Tamaševičius, Arūnas; Adomaitienė, Elena; Bumelienė, Skaidra
2015-01-01
An analog circuit, based on a negative impedance converter and a capacitor, for damping oscillations in an array of mean-field coupled neuronal FitzHugh–Nagumo (FHN) type oscillators is described. The circuit is essentially a two-terminal feedback controller. When coupled to an array of the FHN...
Energy Technology Data Exchange (ETDEWEB)
Kimura, Tomoharu; Yamada, Hirofumi, E-mail: h-yamada@kuee.kyoto-u.ac.jp [Department of Electronic Science and Engineering, Kyoto University, Kyoto 615-8510 (Japan); Kobayashi, Kei [Department of Electronic Science and Engineering, Kyoto University, Kyoto 615-8510 (Japan); The Hakubi Center for Advanced Research, Kyoto University, Kyoto 615-8520 (Japan)
2015-08-07
The device performances of organic thin film transistors are often limited by the metal–organic interface because of the disordered molecular layers at the interface and the energy barriers against the carrier injection. It is important to study the local impedance at the interface without being affected by the interface morphology. We combined frequency modulation atomic force microscopy with scanning impedance microscopy (SIM) to sensitively measure the ac responses of the interface to an ac voltage applied across the interface and the dc potential drop at the interface. By using the frequency-modulation SIM (FM-SIM) technique, we characterized the interface impedance of a Pt electrode and a single pentacene grain as a parallel circuit of a contact resistance and a capacitance. We found that the reduction of the contact resistance was caused by the reduction of the energy level mismatch at the interface by the FM-SIM measurements, demonstrating the usefulness of the FM-SIM technique for investigation of the local interface impedance without being affected by its morphology.
Equivalence, commensurability, value
DEFF Research Database (Denmark)
Albertsen, Niels
2017-01-01
Deriving value in Capital Marx uses three commensurability arguments (CA1-3). CA1 establishes equivalence in exchange as exchangeability with the same third commodity. CA2 establishes value as common denominator in commodities: embodied abstract labour. CA3 establishes value substance...... as commonality of labour: physiological labour. Tensions between these logics have permeated Marxist interpretations of value. Some have supported value as embodied labour (CA2, 3), others a monetary theory of value and value as ‘pure’ societal abstraction (ultimately CA1). They all are grounded in Marx....
Effects of smoke on functional circuits
International Nuclear Information System (INIS)
Tanaka, T.J.
1997-10-01
Nuclear power plants are converting to digital instrumentation and control systems; however, the effects of abnormal environments such as fire and smoke on such systems are not known. There are no standard tests for smoke, but previous smoke exposure tests at Sandia National Laboratories have shown that digital communications can be temporarily interrupted during a smoke exposure. Another concern is the long-term corrosion of metals exposed to the acidic gases produced by a cable fire. This report documents measurements of basic functional circuits during and up to 1 day after exposure to smoke created by burning cable insulation. Printed wiring boards were exposed to the smoke in an enclosed chamber for 1 hour. For high-resistance circuits, the smoke lowered the resistance of the surface of the board and caused the circuits to short during the exposure. These circuits recovered after the smoke was vented. For low-resistance circuits, the smoke caused their resistance to increase slightly. A polyurethane conformal coating substantially reduced the effects of smoke. A high-speed digital circuit was unaffected. A second experiment on different logic chip technologies showed that the critical shunt resistance that would cause failure was dependent on the chip technology and that the components used in the smoke exposures were some of the most smoke tolerant. The smoke densities in these tests were high enough to cause changes in high impedance (resistance) circuits during exposure, but did not affect most of the other circuits. Conformal coatings and the characteristics of chip technologies should be considered when designing circuitry for nuclear power plant safety systems, which must be highly reliable under a variety of operating and accident conditions. 10 refs., 34 figs., 18 tabs
Stochastic modelling of porosity using seismic impedances on a volume of chalk in the Dan Field
Energy Technology Data Exchange (ETDEWEB)
Vejbaek, O.V.
1995-12-31
Seismic impedances calculated from logs show very good correlation to log porosities in wells penetrating the chalk reservoir in the Dan Field, Danish North Sea. This is the basis for an attempt to use seismic impedances derived from inversion as soft data for geostatistical reservoir characterization. The study focusses on porosity description of the Maastrichtian chalk reservoir unit, laterally restricted to an area covered by a subset of a 3D seismic survey. This seismic volume was inverted using the ISIS software producing a volume of seismic impedances. Spatial porosity realizations are produced using a gaussian collocated co-simulation algorithm, where well log porosities constitute the hard data input and seismic impedances are the soft data input. The simulated volume measures 1400 m x 1525 m x 102 m and is oriented parallel to lines and cross lines in the seismic dataset. Simulated blocks measures 25 m x 25 m x 6 m equivalent to twice the line and trace spacing, and approximately equivalent to the seismic sample rate. The correlation coefficient between log porosities and impedances calculated from logs alone are shown to be misleading since they suggest unrealistic high coefficients. However, the actual data used, namely inversion derived impedances and log porosities, still show correlation coefficients in the order of -0,45, which is quite sufficient to make the inversion results very useful. It is remarkable that the calculated correlation coefficient is based on 15 wells, and the inversion is based on only one well. The negative correlation coefficient indicate that high impedances correspond to low porosities and vice-versa. The impedance data indicate the level of average porosities at locations between wells. The fine structure is produced by the geostatistic process, with averages constrained by seismic impedances. The seismic impedances derived from the inversion process are thus shown to constitute useful primary data to constrain reservoir
Intuitive analog circuit design
Thompson, Marc
2013-01-01
Intuitive Analog Circuit Design outlines ways of thinking about analog circuits and systems that let you develop a feel for what a good, working analog circuit design should be. This book reflects author Marc Thompson's 30 years of experience designing analog and power electronics circuits and teaching graduate-level analog circuit design, and is the ideal reference for anyone who needs a straightforward introduction to the subject. In this book, Dr. Thompson describes intuitive and ""back-of-the-envelope"" techniques for designing and analyzing analog circuits, including transistor amplifi
The circuit designer's companion
Williams, Tim
1991-01-01
The Circuit Designer's Companion covers the theoretical aspects and practices in analogue and digital circuit design. Electronic circuit design involves designing a circuit that will fulfill its specified function and designing the same circuit so that every production model of it will fulfill its specified function, and no other undesired and unspecified function.This book is composed of nine chapters and starts with a review of the concept of grounding, wiring, and printed circuits. The subsequent chapters deal with the passive and active components of circuitry design. These topics are foll
Liu, Hai-Tao; Wen, Zhi-Yu; Xu, Yi; Shang, Zheng-Guo; Peng, Jin-Lan; Tian, Peng
2017-09-01
In this paper, an integrated microfluidic analysis microsystems with bacterial capture enrichment and in-situ impedance detection was purposed based on microfluidic chips dielectrophoresis technique and electrochemical impedance detection principle. The microsystems include microfluidic chip, main control module, and drive and control module, and signal detection and processing modulet and result display unit. The main control module produce the work sequence of impedance detection system parts and achieve data communication functions, the drive and control circuit generate AC signal which amplitude and frequency adjustable, and it was applied on the foodborne pathogens impedance analysis microsystems to realize the capture enrichment and impedance detection. The signal detection and processing circuit translate the current signal into impendence of bacteria, and transfer to computer, the last detection result is displayed on the computer. The experiment sample was prepared by adding Escherichia coli standard sample into chicken sample solution, and the samples were tested on the dielectrophoresis chip capture enrichment and in-situ impedance detection microsystems with micro-array electrode microfluidic chips. The experiments show that the Escherichia coli detection limit of microsystems is 5 × 104 CFU/mL and the detection time is within 6 min in the optimization of voltage detection 10 V and detection frequency 500 KHz operating conditions. The integrated microfluidic analysis microsystems laid the solid foundation for rapid real-time in-situ detection of bacteria.
Coupling of impedance functions to nuclear reactor building for soil-structure interaction analysis
International Nuclear Information System (INIS)
Danisch, R.; Delinic, K.; Trbojevic, V.M.
1991-01-01
Finite element model of a nuclear reactor building is coupled to complex soil impedance functions and soil-structure-interaction analysis is carried out in frequency domain. In the second type of analysis applied in this paper, soil impedance functions are used to evaluate equivalent soil springs and dashpots of soil. These are coupled to the structure model in order to carry out the time marching analysis. Three types of soil profiles are considered: hard, medium and soft. Results of two analyzes are compared on the same structural model. Equivalent soil springs and dashpots are determined using new method based on the least square approximation. (author)
Active Magnetic Shielding with magneto-impedance sensor
International Nuclear Information System (INIS)
Okazaki, Yasuo; Yanase, Shunji; Sugimoto, Noriko
2002-01-01
Active shielding effect was examined in a negative feedback circuit system consisting of a magneto-impedance effective sensor, an amplifier and a canceling coil to compensate external magnetic field noise. The phase difference between the input and output sensor signals in a loop was less than 90 degree up to 20,000 Hz. An excellent frequency characteristic of active shielding effectiveness, 48 dB was obtained for the external magnetic field at the frequency of 0 - 2,000 Hz. (Author)
Hydraulic actuator for an electric circuit breaker
Imam, Imdad [Colonie, NY
1983-01-01
This actuator comprises a fluid motor having a piston, a breaker-opening space at one side of the piston, and a breaker-closing space at its opposite side. An accumulator freely communicates with the breaker-opening space for supplying pressurized fluid thereto during a circuit breaker opening operation. The breaker-opening space and the breaker-closing space are connected by an impeded flow passage. A pilot valve opens to allow the pressurized liquid in the breaker-closing space to flow to a back chamber of a normally closed main valve to cause the main valve to be opened during a circuit breaker opening operation to release the pressurized liquid from the breaker-closing space. An impeded passage affords communication between the back chamber and a sump located on the opposite side of the main valve from the back chamber. The pilot valve and impeded passage allow rapid opening of the main valve with pressurized liquid from the breaker closing side of the piston.
Waste Determination Equivalency - 12172
Energy Technology Data Exchange (ETDEWEB)
Freeman, Rebecca D. [Savannah River Remediation (United States)
2012-07-01
by the Secretary of Energy in January of 2006 based on proposed processing techniques with the expectation that it could be revised as new processing capabilities became viable. Once signed, however, it became evident that any changes would require lengthy review and another determination signed by the Secretary of Energy. With the maturation of additional salt removal technologies and the extension of the SWPF start-up date, it becomes necessary to define 'equivalency' to the processes laid out in the original determination. For the purposes of SRS, any waste not processed through Interim Salt Processing must be processed through SWPF or an equivalent process, and therefore a clear statement of the requirements for a process to be equivalent to SWPF becomes necessary. (authors)
DEFF Research Database (Denmark)
Forouzesh, Mojtaba; Abdelhakim, Ahmed; Siwakoti, Yam
2018-01-01
Magnetically coupled impedance source (MCIS) converters are prone to high voltage spikes across the inverter bridge (or dc-link) due to the presence of leakage and stray inductances in the high frequency loop. The problem manifolds because of a shoot-through state in impedance source converters......, but the solutions are not generic (i.e. structure-oriented) and they are quite lossy with intuitive modification in the circuit itself, resulting in significant changes in the performance of the power converter (e.g. increase in components stresses). To address this concern, a general passive regenerative inductor......-capacitor-diode (L-C-D) snubber is presented in this paper for all MCIS converters without any modification in the original circuit. The proposed circuit rechannel the leakage energy of the coupled magnetics and feedback it to input or network itself, which does not only avoid extreme voltage spikes across...
Electrical Circuits and Water Analogies
Smith, Frederick A.; Wilson, Jerry D.
1974-01-01
Briefly describes water analogies for electrical circuits and presents plans for the construction of apparatus to demonstrate these analogies. Demonstrations include series circuits, parallel circuits, and capacitors. (GS)
Establishing Substantial Equivalence: Proteomics
Lovegrove, Alison; Salt, Louise; Shewry, Peter R.
Wheat is a major crop in world agriculture and is consumed after processing into a range of food products. It is therefore of great importance to determine the consequences (intended and unintended) of transgenesis in wheat and whether genetically modified lines are substantially equivalent to those produced by conventional plant breeding. Proteomic analysis is one of several approaches which can be used to address these questions. Two-dimensional PAGE (2D PAGE) remains the most widely available method for proteomic analysis, but is notoriously difficult to reproduce between laboratories. We therefore describe methods which have been developed as standard operating procedures in our laboratory to ensure the reproducibility of proteomic analyses of wheat using 2D PAGE analysis of grain proteins.
Impedance/modulus analysis of sol-gel Ba{sub x}Sr{sub 1-x}TiO{sub 3} thin films
Energy Technology Data Exchange (ETDEWEB)
Saif, Alaeddin A.; Poopalan, P. [University Malaysia Perlis, Perlis (Malaysia)
2010-12-15
Perovskite-structure-type sol-gel barium-strontium-titanate (BST) thin films with molar formula Ba{sub x}Sr{sub 1-x}TiO{sub 3} (x = 0.5, 0.6, 0.7, and 0.8) have been successfully fabricated as Al/BST/Pt capacitors. In order to study the role of the grain size in the conduction mechanisms, we present atomic force microscopy (AFM) results. The impedance and the electric modulus of Ba{sub x}Sr{sub 1-x}TiO{sub 3} thin films have been analyzed in order to correlate the effect of the film regional processes on the conduction mechanism. The impedance and the electric modulus complex planes show three overlapping regions as response for the bulk, the grain boundary and the film/electrode interface mechanisms, and an equivalent circuit has been proposed for each mechanism. The conduction mechanism resulting from the bulk and the grain boundaries is discussed; the results show that the grain boundaries have less effect on the conduction mechanism than the bulk.
REA, Editors of
2012-01-01
REA's Essentials provide quick and easy access to critical information in a variety of different fields, ranging from the most basic to the most advanced. As its name implies, these concise, comprehensive study guides summarize the essentials of the field covered. Essentials are helpful when preparing for exams, doing homework and will remain a lasting reference source for students, teachers, and professionals. Electric Circuits I includes units, notation, resistive circuits, experimental laws, transient circuits, network theorems, techniques of circuit analysis, sinusoidal analysis, polyph
Treu, C.A. Jr.
1999-08-31
A piezoelectric motor drive circuit is provided which utilizes the piezoelectric elements as oscillators and a Meacham half-bridge approach to develop feedback from the motor ground circuit to produce a signal to drive amplifiers to power the motor. The circuit automatically compensates for shifts in harmonic frequency of the piezoelectric elements due to pressure and temperature changes. 7 figs.
Bergstra, J.A.; Ponse, A.
2010-01-01
Short-circuit evaluation denotes the semantics of propositional connectives in which the second argument is only evaluated if the first argument does not suffice to determine the value of the expression. In programming, short-circuit evaluation is widely used. A short-circuit logic is a variant of
Louwsma, S.M.; Vertregt, Maarten
2011-01-01
A sampling circuit for sampling a signal is disclosed. The sampling circuit comprises a plurality of sampling channels adapted to sample the signal in time-multiplexed fashion, each sampling channel comprising a respective track-and-hold circuit connected to a respective analogue to digital
Louwsma, S.M.; Vertregt, Maarten
2010-01-01
A sampling circuit for sampling a signal is disclosed. The sampling circuit comprises a plurality of sampling channels adapted to sample the signal in time-multiplexed fashion, each sampling channel comprising a respective track-and-hold circuit connected to a respective analogue to digital
Mathematical modeling of the electrochemical impedance spectroscopy in lithium ion battery cycling
International Nuclear Information System (INIS)
Xie, Yuanyuan; Li, Jianyang; Yuan, Chris
2014-01-01
Electrochemical impedance spectroscopy (EIS) has been widely utilized as an experimental method for understanding the internal mechanisms and aging effect of lithium ion battery. However, the impedance interpretation still has a lot of difficulties. In this study, a multi-physics based EIS simulation approach is developed to study the cycling effect on the battery impedance responses. The SEI film growth during cycling is coherently coupled with the complicated charge, mass and energy transport processes. The EIS simulation is carried out by applying a perturbation voltage on the electrode surface, and the numerical results on cycled cells are compared with the corresponding experimental data. The effect of electrical double layer, electrode open circuit potential as well as the diffusivity of binary electrolyte are simulated on battery impedance responses. The influence of different SEI growth rate, thermal conditions and charging-discharging rate during cycling are also studied. This developed method can be potentially utilized for interpretation and analysis of experimental EIS results
Basic matrix algebra and transistor circuits
Zelinger, G
1963-01-01
Basic Matrix Algebra and Transistor Circuits deals with mastering the techniques of matrix algebra for application in transistors. This book attempts to unify fundamental subjects, such as matrix algebra, four-terminal network theory, transistor equivalent circuits, and pertinent design matters. Part I of this book focuses on basic matrix algebra of four-terminal networks, with descriptions of the different systems of matrices. This part also discusses both simple and complex network configurations and their associated transmission. This discussion is followed by the alternative methods of de
Quantification of the equivalence principle
International Nuclear Information System (INIS)
Epstein, K.J.
1978-01-01
Quantitative relationships illustrate Einstein's equivalence principle, relating it to Newton's ''fictitious'' forces arising from the use of noninertial frames, and to the form of the relativistic time dilatation in local Lorentz frames. The equivalence principle can be interpreted as the equivalence of general covariance to local Lorentz covariance, in a manner which is characteristic of Riemannian and pseudo-Riemannian geometries
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.
Ishii, H.; Kojima, H.; Fukuhara, H.; Okada, S.; Yamakawa, H.
2012-04-01
Plasma wave is one of the most essential physical quantities in the solar terrestrial physics. The role of plasma wave receiver onboard satellites is to detect plasma waves in space with a good signal to noise ratio. There are two types of plasma wave receivers, the sweep frequency analyzer and the waveform capture. While the sweep frequency analyzer provides plasma wave spectra, the waveform capture obtains waveforms with phase information that is significant in studying nonlinear phenomena. Antenna sensors to observe electric fields of the plasma waves show different features in plasmas from in vacuum. The antenna impedances have specific characteristics in the frequency domain because of the dispersion of plasmas. These antenna impedances are expressed with complex number. We need to know not only the antenna impedances but also the transfer functions of plasma wave receiver's circuits in order to calibrate observed waveforms precisely. The impedances of the electric field antennas are affected by a state of surrounding plasmas. Since satellites run through various regions with different plasma parameters, we precisely should measure the antenna impedances onboard spacecraft. On the contrary, we can obtain the plasma density and by measuring the antenna impedances. Several formulas of the antenna impedance measurement system were proposed. A synchronous detection method is used on the BepiColombo Mercury Magnetospheric Orbiter (MMO), which will be launched in 2014. The digital data are stored in the onboard memory. They are read out and converted to the analog waveforms by D/A converter. They are fed into the input of the preamplifiers of antenna sensors through a resistor. We can calculate a transfer function of the circuit by applying the synchronous detection method to the output waveform from waveform receivers and digital data as a signal source. The size of this system is same as an A5 board. In recent years, Application Specific Integrated Circuit (ASIC
Tapping mode microwave impedance microscopy
Lai, K.
2009-01-01
We report tapping mode microwave impedance imaging based on atomic force microscope platforms. The shielded cantilever probe is critical to localize the tip-sample interaction near the tip apex. The modulated tip-sample impedance can be accurately simulated by the finite-element analysis and the result agrees quantitatively to the experimental data on a series of thin-film dielectric samples. The tapping mode microwave imaging is also superior to the contact mode in that the thermal drift in a long time scale is totally eliminated and an absolute measurement on the dielectric properties is possible. We demonstrated tapping images on working nanodevices, and the data are consistent with the transport results. © 2009 American Institute of Physics.
Impedance-matched Marx generators
Directory of Open Access Journals (Sweden)
W. A. Stygar
2017-04-01
Full Text Available We have conceived a new class of prime-power sources for pulsed-power accelerators: impedance-matched Marx generators (IMGs. The fundamental building block of an IMG is a brick, which consists of two capacitors connected electrically in series with a single switch. An IMG comprises a single stage or several stages distributed axially and connected in series. Each stage is powered by a single brick or several bricks distributed azimuthally within the stage and connected in parallel. The stages of a multistage IMG drive an impedance-matched coaxial transmission line with a conical center conductor. When the stages are triggered sequentially to launch a coherent traveling wave along the coaxial line, the IMG achieves electromagnetic-power amplification by triggered emission of radiation. Hence a multistage IMG is a pulsed-power analogue of a laser. To illustrate the IMG approach to prime power, we have developed conceptual designs of two ten-stage IMGs with LC time constants on the order of 100 ns. One design includes 20 bricks per stage, and delivers a peak electrical power of 1.05 TW to a matched-impedance 1.22-Ω load. The design generates 113 kV per stage and has a maximum energy efficiency of 89%. The other design includes a single brick per stage, delivers 68 GW to a matched-impedance 19-Ω load, generates 113 kV per stage, and has a maximum energy efficiency of 90%. For a given electrical-power-output time history, an IMG is less expensive and slightly more efficient than a linear transformer driver, since an IMG does not use ferromagnetic cores.
Impedance-matched Marx generators
Stygar, W. A.; LeChien, K. R.; Mazarakis, M. G.; Savage, M. E.; Stoltzfus, B. S.; Austin, K. N.; Breden, E. W.; Cuneo, M. E.; Hutsel, B. T.; Lewis, S. A.; McKee, G. R.; Moore, J. K.; Mulville, T. D.; Muron, D. J.; Reisman, D. B.; Sceiford, M. E.; Wisher, M. L.
2017-04-01
We have conceived a new class of prime-power sources for pulsed-power accelerators: impedance-matched Marx generators (IMGs). The fundamental building block of an IMG is a brick, which consists of two capacitors connected electrically in series with a single switch. An IMG comprises a single stage or several stages distributed axially and connected in series. Each stage is powered by a single brick or several bricks distributed azimuthally within the stage and connected in parallel. The stages of a multistage IMG drive an impedance-matched coaxial transmission line with a conical center conductor. When the stages are triggered sequentially to launch a coherent traveling wave along the coaxial line, the IMG achieves electromagnetic-power amplification by triggered emission of radiation. Hence a multistage IMG is a pulsed-power analogue of a laser. To illustrate the IMG approach to prime power, we have developed conceptual designs of two ten-stage IMGs with L C time constants on the order of 100 ns. One design includes 20 bricks per stage, and delivers a peak electrical power of 1.05 TW to a matched-impedance 1.22 -Ω load. The design generates 113 kV per stage and has a maximum energy efficiency of 89%. The other design includes a single brick per stage, delivers 68 GW to a matched-impedance 19 -Ω load, generates 113 kV per stage, and has a maximum energy efficiency of 90%. For a given electrical-power-output time history, an IMG is less expensive and slightly more efficient than a linear transformer driver, since an IMG does not use ferromagnetic cores.
New recommendations for dose equivalent
International Nuclear Information System (INIS)
Bengtsson, G.
1985-01-01
In its report 39, the International Commission on Radiation Units and Measurements (ICRU), has defined four new quantities for the determination of dose equivalents from external sources: the ambient dose equivalent, the directional dose equivalent, the individual dose equivalent, penetrating and the individual dose equivalent, superficial. The rationale behind these concepts and their practical application are discussed. Reference is made to numerical values of these quantities which will be the subject of a coming publication from the International Commission on Radiological Protection, ICRP. (Author)
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)
System equivalent model mixing
Klaassen, Steven W. B.; van der Seijs, Maarten V.; de Klerk, Dennis
2018-05-01
This paper introduces SEMM: a method based on Frequency Based Substructuring (FBS) techniques that enables the construction of hybrid dynamic models. With System Equivalent Model Mixing (SEMM) frequency based models, either of numerical or experimental nature, can be mixed to form a hybrid model. This model follows the dynamic behaviour of a predefined weighted master model. A large variety of applications can be thought of, such as the DoF-space expansion of relatively small experimental models using numerical models, or the blending of different models in the frequency spectrum. SEMM is outlined, both mathematically and conceptually, based on a notation commonly used in FBS. A critical physical interpretation of the theory is provided next, along with a comparison to similar techniques; namely DoF expansion techniques. SEMM's concept is further illustrated by means of a numerical example. It will become apparent that the basic method of SEMM has some shortcomings which warrant a few extensions to the method. One of the main applications is tested in a practical case, performed on a validated benchmark structure; it will emphasize the practicality of the method.
Cascaded impedance networks for NPC inverter
DEFF Research Database (Denmark)
Li, Ding; Gao, Feng; Loh, Poh Chiang
2010-01-01
they are subject to the renewable sources. To date, three distinct types of impedance networks can be summarized for implementing a hybrid source impedance network, which can in principle be combined and cascaded before connected to a NPC inverter by proposed two ways. The resulting cascaded impedance network NPC...
Impedance analysis of acupuncture points and pathways
International Nuclear Information System (INIS)
Teplan, Michal; Kukucka, Marek; Ondrejkovicová, Alena
2011-01-01
Investigation of impedance characteristics of acupuncture points from acoustic to radio frequency range is addressed. Discernment and localization of acupuncture points in initial single subject study was unsuccessfully attempted by impedance map technique. Vector impedance analyses determined possible resonant zones in MHz region.
Journal bearing impedance descriptions for rotordynamic applications
Childs, D.W.; Moes, H.; Leeuwen, van H.J.
1977-01-01
Bearing impedance vectors are introduced for plain journal bearings which define the bearing reaction force components as a function of the bearing motion. Impedance descriptions are developed directly for the approximate Ocvirk (short) and Sommerfeld (long) bearing solutions. The impedance vector
Theoretical interpretation of Warburg's impedance in unsupported electrolytic cells.
Barbero, G
2017-12-13
We discuss the origin of Warburg's impedance in unsupported electrolytic cells containing only one group of positive and one group of negative ions. Our analysis is based on the Poisson-Nernst-Planck model, where the generation-recombination phenomenon is neglected. We show that to observe Warburg-like impedance the diffusion coefficient of the positive ions has to differ from that of the negative ones, and furthermore the electrodes have to be not blocking. We assume that the non-blocking properties of the electrodes can be described by means of an Ohmic model, where the charge exchange between the cell and the external circuit is described by means of an electrode conductivity. For simplicity we consider a symmetric cell. However, our analysis can be easily generalized to more complicated situations, where the cell is not symmetric and the charge exchange is described by the Chang-Jaffe model, or by a linearized version of the Butler-Volmer equation. Our analysis allows justification of the expression for Warburg's impedance proposed previously by several groups, based on wrong assumptions.
The IMPACT shirt: textile integrated and portable impedance cardiography
International Nuclear Information System (INIS)
Ulbrich, Mark; Wan, Tingting; Leonhardt, Steffen; Walter, Marian; Mühlsteff, Jens; Sipilä, Auli; Kamppi, Merja; Koskela, Anne; Myry, Manu
2014-01-01
Measurement of hemodynamic parameters such as stroke volume (SV) via impedance cardiography (ICG) is an easy, non-invasive and inexpensive way to assess the health status of the heart. We present a possibility to use this technology for monitoring risk patients at home. The IMPACT Shirt (IMPedAnce Cardiography Textile) has been developed with integrated textile electrodes and textile wiring, as well as with portable miniaturized hardware. Several textile materials were characterized in vitro and in vivo to analyze their performance with regard to washability, and electrical characteristics such as skin-electrode impedance, capacitive coupling and subjective tactile feeling. The small lightweight hardware measures ECG and ICG continuously and transmits wireless data via Bluetooth to a mobile phone (Android) or PC for further analysis. A lithium polymer battery supplies the circuit and can be charged via a micro-USB. Results of a proof-of-concept trial show excellent agreement between SV assessed by a commercial device and the developed system. The IMPACT Shirt allows monitoring of SV and ECG on a daily basis at the patient’s home. (paper)
International Nuclear Information System (INIS)
Smorodinskij, Ya.A.
1980-01-01
The prerelativistic history of the equivalence principle (EP) is presented briefly. Its role in history of the general relativity theory (G.R.T.) discovery is elucidated. A modern idea states that the ratio of inert and gravitational masses does not differ from 1 at least up to the 12 sign after comma. Attention is paid to the difference of the gravitational field from electromagnetic one. The difference is as follows, the energy of the gravitational field distributed in space is the source of the field. These fields always interact at superposition. Electromagnetic fields from different sources are put together. On the basis of EP it is established the Sun field interact with the Earth gravitational energy in the same way as with any other one. The latter proves the existence of gravitation of the very gravitational field to a heavy body. A problem on gyroscope movement in the Earth gravitational field is presented as a paradox. The calculation has shown that gyroscope at satellite makes a positive precession, and its axis turns in an angle equal to α during a turn of the satellite round the Earth, but because of the space curvature - into the angle two times larger than α. A resulting turn is equal to 3α. It is shown on the EP basis that the polarization plane in any coordinate system does not turn when the ray of light passes in the gravitational field. Together with the historical value of EP noted is the necessity to take into account the requirements claimed by the EP at description of the physical world
Filament supply circuit for particle accelerator
International Nuclear Information System (INIS)
Thompson, C.C. Jr.; Malone, H.F.
1975-01-01
In a particle accelerator of the type employing ac primary power and a voltage multiplication apparatus to achieve the required high dc accelerating voltage, a filament supply circuit is powered by a portion of the ac primary power appearing at the last stage of the voltage multiplier. This ac power is applied across a voltage regulator circuit in the form of two zener diodes connected back to back. The threshold of the zeners is below the lowest peak-to-peak voltage of the ac voltage, so that the regulated voltage remains constant for all settings of the adjustable acceleration voltage. The regulated voltage is coupled through an adjustable resistor and an impedance-matching transformer to the accelerator filament. (auth)
International Nuclear Information System (INIS)
Li, Mian-Gang; Chen, Li; Zhong, Yun-Xin; Chen, Zhao-Bin; Yan, Jia-Wei; Mao, Bing-Wei
2016-01-01
The electrochemical interface between Ag(111) and 1-ethyl-3-methylimidazolium bis(trifluoromethylsulfonyl)imide (EMITFSI) has been investigated by in-situ scanning probe microscopy (SPM) and electrochemical impedance spectroscopy (EIS). In-situ scanning tunneling microscopy (STM) characterization has revealed that there is neither surface reconstruction nor strong adsorption of EMITFSI on Ag(111) surface so that EIS investigation can be fulfilled under well-defined surface condition and in the absence of pseudo capacitive process. In-situ atom force microscopy (AFM) force curve measurements further disclose that there exists five layered structures near and normal to the surface, among them three layered structures being charged and forming the electric double layer (EDL) of the interface. An electric equivalent circuit is proposed, which comprises two serial parallel branches involving the innermost layered structure and the next two layered structures in the EDL, respectively. The inner layer circuit is given by a constant phase element (CPE) in parallel to a resistor, while the outer layer circuit is given by a capacity in parallel with a resistor-Warburg element branch. Slow response is observed for the inner layer, which is attributed to the hindrance of reorientation and/or redistribution of ions in the more ordered and robust inner layer region. The inner layer capacitance and outer layer capacitance have opposing potential dependence, and the resultant double layer capacitance shows weak potential dependence.
Fatigue Life Assessment of Structures Using Electro-Mechanical Impedance Technique
International Nuclear Information System (INIS)
Bhalla, S
2012-01-01
This paper describes a new experimental approach for fatigue life assessment of structures based on the equivalent stiffness determined by surface bonded piezo-impedance transducers through the electro-mechanical impedance (EMI) technique. The remaining life of the component (in terms of the cycles of loading that can be sustained) is non-dimensionally correlated with the equivalent identified stiffness. The proposed approach circumvents the determination of the absolute stiffness of the joint and employs the admittance signature of the surface-bonded piezo-transducers directly. The second part of the paper briefly describes the recent advances made in the field of impedance based structural health monitoring (SHM) in terms of low-cost hardware system and improved damage diagnosis through the integration of global dynamic and EMI techniques using the same set of piezo-sensors. Other recent applications such as bio-sensors and traffic sensors pioneered at the Smart Structures and Dynamics Laboratory (SSDL) are also briefly covered.
Modular thought in the circuit analysis
Wang, Feng
2018-04-01
Applied to solve the problem of modular thought, provides a whole for simplification's method, the complex problems have become of, and the study of circuit is similar to the above problems: the complex connection between components, make the whole circuit topic solution seems to be more complex, and actually components the connection between the have rules to follow, this article mainly tells the story of study on the application of the circuit modular thought. First of all, this paper introduces the definition of two-terminal network and the concept of two-terminal network equivalent conversion, then summarizes the common source resistance hybrid network modular approach, containing controlled source network modular processing method, lists the common module, typical examples analysis.
Feasibility Verification of Mountable PZT-Interface for Impedance Monitoring in Tendon-Anchorage
Directory of Open Access Journals (Sweden)
Thanh-Canh Huynh
2015-01-01
Full Text Available This study has been motivated to numerically evaluate the performance of the mountable PZT-interface for impedance monitoring in tendon-anchorage. Firstly, electromechanical impedance monitoring and feature classification methods are outlined. Secondly, a structural model of tendon-anchorage subsystem with mountable PZT-interface is designed for impedance monitoring. Finally, the feasibility of the mountable PZT-interface is numerically examined. A finite element (FE model is designed for the lab-scaled tendon-anchorage. The FE model of the PZT-interface is tuned as its impedance signatures meet the experimental test results at the same frequency ranges and also with identical patterns. Equivalent model properties of the FE model corresponding to prestress forces inflicted on the lab-tested structure are identified from the fine-tuning practice.
International Nuclear Information System (INIS)
Zhang Fan; Lin Longxiang; Wang Guowei; Hu Ren; Lin Changjian; Chen Yong
2012-01-01
Highlights: ► The EIS of living MG63 cells on the Ti MEA chip with Ag, HA, and Ag–HA was monitored. ► The R cell can be related to the bioresponsibility of the coatings. ► The bioactivity order was evaluated as follows: Ti–Ag–HA > Ti–HA ≈ Ti–Ag > Ti. - Abstract: This paper reports a transparent Ti microelectrode array (MEA) system for a high-throughput evaluation of bioresponsibility using electrochemical impedance spectroscopy (EIS). The MEA chip integrated with hydroxyapatite (HA) and Ag coatings was selectively prepared by electrochemical deposition based on a novel procedure of multichannel current control. The EIS measurement of living MG63 osteosarcoma cells in the integrated MEA chip was conducted, and the result was analyzed using an equivalent circuit corresponding to a titanium oxide film, protein adsorption layer, cell adhesion layer, and medium. It is shown that the bioresponsibility of Ti–Ag–HA on the MEA chip can be improved, compared with the Ti, Ti–HA, and Ti–Ag coatings. The system was further used for real-time EIS monitoring during continuous cell culture for a long period (12 days). The effect of the long-term cell proliferation on the EIS behavior was discussed. This integrated system is valuable to significantly simplify the operation procedures and quickly evaluate the bioresponsibility of biomaterials.
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.
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
Rangel-Abundis, Alberto
2006-01-01
Shunt and short circuit are antonyms. In French, the term shunt has been adopted to denote the alternative pathway of blood flow. However, in French, as well as in Spanish, the word short circuit (court-circuit and cortocircuito) is synonymous with shunt, giving rise to a linguistic and scientific inconsistency. Scientific because shunt and short circuit made reference to a phenomenon that occurs in the field of the physics. Because shunt and short circuit are antonyms, it is necessary to clarify that shunt is an alternative pathway of flow from a net of high resistance to a net of low resistance, maintaining the stream. Short circuit is the interruption of the flow, because a high resistance impeaches the flood. This concept is applied to electrical and cardiovascular physiology, as well as to the metabolic pathways.
Electrical circuit modeling of conductors with skin effect
International Nuclear Information System (INIS)
Kerst, D.W.; Sprott, J.C.
1986-01-01
The electrical impedance of a lossy conductor is a complicated function of time (or frequency) because of the skin effect. By solving the diffusion equation for magnetic fields in conductors of several prototypical shapes, the impedance can be calculated as a function of time for a step function of current. The solution suggests an electrical circuit representation that allows calculation of time-dependent voltages and currents of arbitrary waveforms. A technique using an operational amplifier to determine the current in such a conductor by measuring some external voltage is described. Useful analytical approximations to the results are derived
TLINES: A Computer Program for Circuits of Transmission Lines.
1983-12-01
of various lengths are handled by stringing together many short lines, with the assumption that each of the longer lines has a length approximated as...expressed in terms of transmission lines numbered from 2 through CAPM , connected in numerical sequence as in figure 3. Line 1 is a dummy element disconnected...from line 2 and the rest of the circuit. Lines 2 through CAPM can each be set to any impedance the user desires. Line CAPM +1 is a zero-impedance line
Logically automorphically equivalent knowledge bases
Aladova, Elena; Plotkin, Tatjana
2017-01-01
Knowledge bases theory provide an important example of the field where applications of universal algebra and algebraic logic look very natural, and their interaction with practical problems arising in computer science might be very productive. In this paper we study the equivalence problem for knowledge bases. Our interest is to find out how the informational equivalence is related to the logical description of knowledge. Studying various equivalences of knowledge bases allows us to compare d...
International Nuclear Information System (INIS)
Castro, E.B.; Vilche, J.R.; Milocco, R.H.
1984-01-01
An impedance measurement system based on the spectral analysis of excitation and response signals was implemented using a pseudo-random binary sequence in the generation of the electrical perturbation signal. The spectral density functions were estimated through finite Fourier transforms of the original time history records by fast computation of Fourier series. Experimental results obtained using the FFT algorithm in the developed impedance measurement system which covers a wide frequency range, 10 KHz >= f >= 1 mHz, are given both for dummy cells representing conventional electric circuits in electrochemistry and corrosion systems and for the Fe/acidic chloride solution interfaces under different polarization conditions. (C.L.B.) [pt
International Nuclear Information System (INIS)
Roberge, P.R.; Halliop, E.; Sastri, V.S.
1992-01-01
A technique based on recording corrosion potential fluctuations generated by corroding electrodes was used under open-circuit conditions to study passivation and depassivation of carbon steel. Quantification of the electrochemical signal in terms of the pitting corrosion rate has been attempted. The amplitude of electrochemical noise signals was analyzed under different pitting conditions and correlated to polarization resistance values obtained from the electrochemical impedance spectra. The automatic statistical data analysis of electrochemical impedance data points has been successfully applied to calculate polarization resistance values and other interesting characteristics of such measurements
Hickman, Ian
2013-01-01
Analog Circuits Cookbook presents articles about advanced circuit techniques, components and concepts, useful IC for analog signal processing in the audio range, direct digital synthesis, and ingenious video op-amp. The book also includes articles about amplitude measurements on RF signals, linear optical imager, power supplies and devices, and RF circuits and techniques. Professionals and students of electrical engineering will find the book informative and useful.
Dobkin, Bob
2012-01-01
Analog circuit and system design today is more essential than ever before. With the growth of digital systems, wireless communications, complex industrial and automotive systems, designers are being challenged to develop sophisticated analog solutions. This comprehensive source book of circuit design solutions aids engineers with elegant and practical design techniques that focus on common analog challenges. The book's in-depth application examples provide insight into circuit design and application solutions that you can apply in today's demanding designs. <
Regenerative feedback resonant circuit
Jones, A. Mark; Kelly, James F.; McCloy, John S.; McMakin, Douglas L.
2014-09-02
A regenerative feedback resonant circuit for measuring a transient response in a loop is disclosed. The circuit includes an amplifier for generating a signal in the loop. The circuit further includes a resonator having a resonant cavity and a material located within the cavity. The signal sent into the resonator produces a resonant frequency. A variation of the resonant frequency due to perturbations in electromagnetic properties of the material is measured.
Observations involving broadband impedance modelling
International Nuclear Information System (INIS)
Berg, J.S.
1995-08-01
Results for single- and multi-bunch instabilities can be significantly affected by the precise model that is used for the broadband impendance. This paper discusses three aspects of broadband impendance modeling. 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 impendance which follow from the general properties of impendances
Testing statistical hypotheses of equivalence
Wellek, Stefan
2010-01-01
Equivalence testing has grown significantly in importance over the last two decades, especially as its relevance to a variety of applications has become understood. Yet published work on the general methodology remains scattered in specialists' journals, and for the most part, it focuses on the relatively narrow topic of bioequivalence assessment.With a far broader perspective, Testing Statistical Hypotheses of Equivalence provides the first comprehensive treatment of statistical equivalence testing. The author addresses a spectrum of specific, two-sided equivalence testing problems, from the
Marston, R M
1995-01-01
CMOS Circuits Manual is a user's guide for CMOS. The book emphasizes the practical aspects of CMOS and provides circuits, tables, and graphs to further relate the fundamentals with the applications. The text first discusses the basic principles and characteristics of the CMOS devices. The succeeding chapters detail the types of CMOS IC, including simple inverter, gate and logic ICs and circuits, and complex counters and decoders. The last chapter presents a miscellaneous collection of two dozen useful CMOS circuits. The book will be useful to researchers and professionals who employ CMOS circu
Timergenerator circuits manual
Marston, R M
2013-01-01
Timer/Generator Circuits Manual is an 11-chapter text that deals mainly with waveform generator techniques and circuits. Each chapter starts with an explanation of the basic principles of its subject followed by a wide range of practical circuit designs. This work presents a total of over 300 practical circuits, diagrams, and tables.Chapter 1 outlines the basic principles and the different types of generator. Chapters 2 to 9 deal with a specific type of waveform generator, including sine, square, triangular, sawtooth, and special waveform generators pulse. These chapters also include pulse gen
Electronic devices and circuits
Pridham, Gordon John
1968-01-01
Electronic Devices and Circuits, Volume 1 deals with the design and applications of electronic devices and circuits such as passive components, diodes, triodes and transistors, rectification and power supplies, amplifying circuits, electronic instruments, and oscillators. These topics are supported with introductory network theory and physics. This volume is comprised of nine chapters and begins by explaining the operation of resistive, inductive, and capacitive elements in direct and alternating current circuits. The theory for some of the expressions quoted in later chapters is presented. Th
Maximum Acceleration Recording Circuit
Bozeman, Richard J., Jr.
1995-01-01
Coarsely digitized maximum levels recorded in blown fuses. Circuit feeds power to accelerometer and makes nonvolatile record of maximum level to which output of accelerometer rises during measurement interval. In comparison with inertia-type single-preset-trip-point mechanical maximum-acceleration-recording devices, circuit weighs less, occupies less space, and records accelerations within narrower bands of uncertainty. In comparison with prior electronic data-acquisition systems designed for same purpose, circuit simpler, less bulky, consumes less power, costs and analysis of data recorded in magnetic or electronic memory devices. Circuit used, for example, to record accelerations to which commodities subjected during transportation on trucks.
Wolfendale, E
2013-01-01
MOS Integral Circuit Design aims to help in the design of integrated circuits, especially large-scale ones, using MOS Technology through teaching of techniques, practical applications, and examples. The book covers topics such as design equation and process parameters; MOS static and dynamic circuits; logic design techniques, system partitioning, and layout techniques. Also featured are computer aids such as logic simulation and mask layout, as well as examples on simple MOS design. The text is recommended for electrical engineers who would like to know how to use MOS for integral circuit desi
Chen, Wai-Kai
2003-01-01
A bestseller in its first edition, The Circuits and Filters Handbook has been thoroughly updated to provide the most current, most comprehensive information available in both the classical and emerging fields of circuits and filters, both analog and digital. This edition contains 29 new chapters, with significant additions in the areas of computer-aided design, circuit simulation, VLSI circuits, design automation, and active and digital filters. It will undoubtedly take its place as the engineer's first choice in looking for solutions to problems encountered in the design, analysis, and behavi
Security electronics circuits manual
MARSTON, R M
1998-01-01
Security Electronics Circuits Manual is an invaluable guide for engineers and technicians in the security industry. It will also prove to be a useful guide for students and experimenters, as well as providing experienced amateurs and DIY enthusiasts with numerous ideas to protect their homes, businesses and properties.As with all Ray Marston's Circuits Manuals, the style is easy-to-read and non-mathematical, with the emphasis firmly on practical applications, circuits and design ideas. The ICs and other devices used in the practical circuits are modestly priced and readily available ty
Multistability in Chua's circuit with two stable node-foci
International Nuclear Information System (INIS)
Bao, B. C.; Wang, N.; Xu, Q.; Li, Q. D.
2016-01-01
Only using one-stage op-amp based negative impedance converter realization, a simplified Chua's diode with positive outer segment slope is introduced, based on which an improved Chua's circuit realization with more simpler circuit structure is designed. The improved Chua's circuit has identical mathematical model but completely different nonlinearity to the classical Chua's circuit, from which multiple attractors including coexisting point attractors, limit cycle, double-scroll chaotic attractor, or coexisting chaotic spiral attractors are numerically simulated and experimentally captured. Furthermore, with dimensionless Chua's equations, the dynamical properties of the Chua's system are studied including equilibrium and stability, phase portrait, bifurcation diagram, Lyapunov exponent spectrum, and attraction basin. The results indicate that the system has two symmetric stable nonzero node-foci in global adjusting parameter regions and exhibits the unusual and striking dynamical behavior of multiple attractors with multistability.
Chin, K. B.; Chi, I.; Pasalic, J.; Huang, C.-K.; Barge, Laura M.
2018-04-01
Portable, low power, yet ultra-sensitive life detection instrumentations are vital to future astrobiology flight programs at NASA. In this study, initial attempts to characterize amino acids in an aqueous environment by electrochemical impedance spectroscopy (EIS) using polarizable (blocking) electrodes in order to establish a means of detection via their electrical properties. Seven amino acids were chosen due to their scientific importance in demonstrating sensitivity levels in the range of part per billion concentration. Albeit more challenging in real systems of analyst mixtures, we found individual amino acids in aqueous environment do exhibit some degree of chemical and physical uniqueness to warrant characterization by EIS. The polar amino acids (Asp, Glu, and His) exhibited higher electrochemical activity than the non-polar amino acids (Ala, Gly, Val, and Leu). The non-polar amino acids (Gly and Ala) also exhibited unique electrical properties which appeared to be more dependent on physical characteristics such as molecular weight and structure. At concentrations above 1 mM where the amino acids play a more dominant transport role within the water, the conductivity was found to be more sensitive to concentrations. At lower concentrations activity with water. As revealed by equivalent circuit modeling, the relaxation times showed a 1-2 order of magnitude difference between polar and non-polar amino acids. The pseudo-capacitance from EIS measurements on sample mixtures containing salt water and individual amino acids revealed the possibility for improvement in amino acid selectivity using gold nanoporous surface enhanced electrodes. This work establishes important methodologies for characterizing amino acids using EIS combined with microscale electrodes, supporting the case for instrumentation development for life detection and origin of life programs.
Guseynov, F. G.; Abbasova, E. M.
1977-01-01
The equivalent representation of brakes and coupling by lumped circuits is investigated. Analytical equations are derived for relating the indices of the transients to the parameters of the equivalent circuits for arbitrary rotor speed. A computer algorithm is given for the calculations.
Spheromak Impedance and Current Amplification
International Nuclear Information System (INIS)
Fowler, T K; Hua, D D; Stallard, B W
2002-01-01
It is shown that high current amplification can be achieved only by injecting helicity on the timescale for reconnection, τ REC , which determines the effective impedance of the spheromak. An approximate equation for current amplification is: dI TOR 2 /dt ∼ I 2 /τ REC - I TOR 2 /τ closed where I is the gun current, I TOR is the spheromak toroidal current and τ CLOSED is the ohmic decay time of the spheromak. Achieving high current amplification, I TOR >> I, requires τ REC CLOSED . For resistive reconnection, this requires reconnection in a cold zone feeding helicity into a hot zone. Here we propose an impedance model based on these ideas in a form that can be implemented in the Corsica-based helicity transport code. The most important feature of the model is the possibility that τ REC actually increases as the spheromak temperature increases, perhaps accounting for the ''voltage sag'' observed in some experiments, and a tendency toward a constant ratio of field to current, B ∝ I, or I TOR ∼ I. Program implications are discussed
SAPONIFICATION EQUIVALENT OF DASAMULA TAILA
Saxena, R. B.
1994-01-01
Saponification equivalent values of Dasamula taila are very useful for the technical and analytical work. It gives the mean molecular weight of the glycerides and acids present in Dasamula Taila. Saponification equivalent values of Dasamula taila are reported in different packings.
Saponification equivalent of dasamula taila.
Saxena, R B
1994-07-01
Saponification equivalent values of Dasamula taila are very useful for the technical and analytical work. It gives the mean molecular weight of the glycerides and acids present in Dasamula Taila. Saponification equivalent values of Dasamula taila are reported in different packings.
International Nuclear Information System (INIS)
Lin Guanxin
1991-01-01
A study on the rules in which the lead equivalent of lead glass changes with the energy of X rays or γ ray is described. The reason of this change is discussed and a new testing method of lead equivalent is suggested
Experimental Evaluation of Equivalent-Fluid Models for Melamine Foam
Allen, Albert R.; Schiller, Noah H.
2016-01-01
Melamine foam is a soft porous material commonly used in noise control applications. Many models exist to represent porous materials at various levels of fidelity. This work focuses on rigid frame equivalent fluid models, which represent the foam as a fluid with a complex speed of sound and density. There are several empirical models available to determine these frequency dependent parameters based on an estimate of the material flow resistivity. Alternatively, these properties can be experimentally educed using an impedance tube setup. Since vibroacoustic models are generally sensitive to these properties, this paper assesses the accuracy of several empirical models relative to impedance tube measurements collected with melamine foam samples. Diffuse field sound absorption measurements collected using large test articles in a laboratory are also compared with absorption predictions determined using model-based and measured foam properties. Melamine foam slabs of various thicknesses are considered.
Hybrid silicon mode-locked laser with improved RF power by impedance matching
Tossoun, Bassem; Derickson, Dennis; Srinivasan, Sudharsanan; Bowers, John
2015-02-01
We design and discuss an impedance matching solution for a hybrid silicon mode-locked laser diode (MLLD) to improve peak optical power coming from the device. In order to develop an impedance matching solution, a thorough measurement and analysis of the MLLD as a function of bias on each of the laser segments was carried out. A passive component impedance matching network was designed at the operating frequency of 20 GHz to optimize RF power delivery to the laser. The hybrid silicon laser was packaged together in a module including the impedance matching circuit. The impedance matching design resulted in a 6 dB (electrical) improvement in the detected modulation spectrum power, as well as approximately a 10 dB phase noise improvement, from the MLLD. Also, looking ahead to possible future work, we discuss a Step Recovery Diode (SRD) driven impulse generator, which wave-shapes the RF drive to achieve efficient injection. This novel technique addresses the time varying impedance of the absorber as the optical pulse passes through it, to provide optimum optical pulse shaping.
International Nuclear Information System (INIS)
Hu Yixiang; Qiu Aici; Sun Fengju; Huang Tao; Cong Peitian; Wang Liangping; Zeng Jiangtao; Li Yan; Zhang Xinjun; Lei Tianshi
2011-01-01
Based on the transmission line code TLCODE, a 1D circuit model for a transmission-line impedance transformer was developed and the simulation results were compared with those in the literature. The model was used to quantify the efficiencies of voltage-transport, energy-transport and power-transport for a transmission-line impedance transformer as functions of ψ (the ratio of the output impedance to the input impedance of the transformer) and Γ (the ratio of the pulse width to the one-way transit time of the transformer) under a large scale of m (the coefficient of the generalized exponential impedance profile). Simulation results suggest that with the increase in Γ, from 0 to ∞, the power transport efficiency first increases and then decreases. The maximum power transport efficiency can reach 90% or even higher for an exponential impedance profile (m = 1). With a consideration of dissipative loss in the dielectric and electrodes of the transformer, two representative designs of the water-insulated transformer are investigated for the next generation of petawatt-class z-pinch drivers. It is found that the dissipative losses in the electrodes are negligibly small, below 0.1%, but the dissipative loss in the water dielectric is about 1% to 4%. (fusion engineering)
International Nuclear Information System (INIS)
He Yong; Zou Wen-Kang; Song Sheng-Yi
2011-01-01
In modern pulsed power systems, magnetically insulated transmission lines (MITLs) are used to couple power between the driver and the load. The circuit parameters of MITLs are well understood by employing the concept of flow impedance derived from Maxwell's equations and pressure balance across the flow. However, the electron density in an MITL is always taken as constant in the application of flow impedance. Thus effects of electron flow current density (product of electron density and drift velocity) in an MITL are neglected. We calculate the flow impedances of an MITL and compare them under three classical MITL theories, in which the electron density profile and electron flow current density are different from each other. It is found that the assumption of constant electron density profile in the calculation of the flow impedance is not always valid. The electron density profile and the electron flow current density have significant effects on flow impedance of the MITL. The details of the electron flow current density and its effects on the operation impedance of the MITL should be addressed more explicitly by experiments and theories in the future. (nuclear physics)
DEFF Research Database (Denmark)
Hansen, Kristoffer Arnsfelt; Miltersen, Peter Bro; Vinay, V
2006-01-01
We consider the computational power of constant width polynomial size cylindrical circuits and nondeterministic branching programs. We show that every function computed by a Pi2 o MOD o AC0 circuit can also be computed by a constant width polynomial size cylindrical nondeterministic branching pro...
Electrical circuit model of ITO/AZO/Ge photodetector.
Patel, Malkeshkumar; Kim, Joondong
2017-10-01
In this data article, ITO/AZO/Ge photodetector was investigated for electrical circuit model. Due to the double (ITO and AZO) transparent metal-oxide films (DOI:10.1016/j.mssp.2016.03.007) (Yun et al., 2016) [1], the Ge heterojunction device has a better interface quality due to the AZO layer with a low electrical resistance due to the ITO layer (Yun et al., 2015) [2]. The electrical and interfacial benefitted ITO/AZO/Ge heterojunction shows the quality Schottky junction. In order to investigate the device, the ITO/AZO/Ge heterojunction was analyzed by R-C circuit model using the impedance spectroscopy.
Circuits and electronics hands-on learning with analog discovery
Okyere Attia, John
2018-01-01
The book provides instructions on building circuits on breadboards, connecting the Analog Discovery wires to the circuit under test, and making electrical measurements. Various measurement techniques are described and used in this book, including: impedance measurements, complex power measurements, frequency response measurements, power spectrum measurements, current versus voltage characteristic measurements of diodes, bipolar junction transistors, and Mosfets. The book includes end-of-chapter problems for additional exercises geared towards hands-on learning, experimentation, comparisons between measured results and those obtained from theoretical calculations.
Circuit effects on pierce instabilities, and double-layer formation
International Nuclear Information System (INIS)
Raadu, M.A.; Silevitch, M.B.
1982-11-01
The role of the Pierce instability in the formation of double layers is considered and compared with that of the Buneman instability. Pierce instabilities have been identified in a double-layer experiment, where they lead to ion trapping. Here the effects of external circuit elements are considered. In the case of immobile ions the onset criteria are unaffected, but in the unstable range the growth rate is reduced by the external impedance. Required experimental values of the circuit elements are estimated. The possible relevance to computer simulations is noted. (Authors)
Theory and Circuit Model for Lossy Coaxial Transmission Line
Energy Technology Data Exchange (ETDEWEB)
Genoni, T. C.; Anderson, C. N.; Clark, R. E.; Gansz-Torres, J.; Rose, D. V.; Welch, Dale Robert
2017-04-01
The theory of signal propagation in lossy coaxial transmission lines is revisited and new approximate analytic formulas for the line impedance and attenuation are derived. The accuracy of these formulas from DC to 100 GHz is demonstrated by comparison to numerical solutions of the exact field equations. Based on this analysis, a new circuit model is described which accurately reproduces the line response over the entire frequency range. Circuit model calculations are in excellent agreement with the numerical and analytic results, and with finite-difference-time-domain simulations which resolve the skindepths of the conducting walls.