Topic
Electrical impedance
About: Electrical impedance is a research topic. Over the lifetime, 36015 publications have been published within this topic receiving 371891 citations. The topic is also known as: electrical impedance & complex impedance.
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TL;DR: An imaging system capable of magnification, subwavelength-resolution and impedance matching, which minimizes reflection losses is developed, which is based on available materials and existing fabrication technologies.
Abstract: We propose an approach to optical imaging beyond the diffraction limit, based on transformation optics in concentric circular cylinder domains. The resulting systems allow image magnification and minimize reflection losses due to the impedance matching at the input or output boundaries. While perfect impedance matching at both surfaces can be obtained only in a system with radius-dependent magnetic permeability, we demonstrate that comparable performance can be achieved in an optimized nonmagnetic design.
164 citations
Patent•
20 Jul 2000TL;DR: In this paper, an electrical current is created across an electrically conductive medium comprising a cell which may be part of a tissue of a living organism, and a first electrical parameter, such as current, voltage, or electrical impedance is measured.
Abstract: An electrical current is created across an electrically conductive medium comprising a cell which may be part of a tissue of a living organism. A first electrical parameter which may be current, voltage, or electrical impedance is measured. A second electrical parameter which may be current, voltage or a combination of both is then adjusted and/or analyzed. Adjustments are carried out to facilitate analysis and/or obtain a desired degree of electroporation. Analysis is carried out to determine characteristics of the cell membrane and/or tissue.
164 citations
TL;DR: In this paper, the results of simulations were used to predict the net harmonic currents produced by large numbers of single-phase desktop computers in a facility, such as a commercial office building.
Abstract: In this paper we use the results of simulations to predict the net harmonic currents produced by large numbers of single-phase desktop computers in a facility, such as a commercial office building. We take into account attenuation due to system impedance and voltage distortion, as well as diversity in harmonic current phase angles due to variations in power and circuit parameters. Using experimental and published data we establish ranges of circuit parameters for an equivalent 120 V, 100 W "base computer unit" and branch circuit, update our computer modeling code (described in previous papers) to iteratively handle the interaction between current and voltage harmonics, and use the code to predict the net harmonic injection currents at the point of common coupling (PCC) represented by a shared transformer connected to a stiff power system. The key contributions of this paper are: providing estimates of the net harmonic current injection due to distributed single-phase computer loads in Amps/kW, as well as in percent of fundamental current, for a wide range of system loading and voltage distortion conditions; and illustrating that the reduction in harmonic currents due to phase angle diversity (expressed in Amps/kW) is relatively independent of system loading, whereas the reduction due to attenuation increases significantly with system loading. >
163 citations
TL;DR: A new method is described, which derives a 1-D model for CMUT arrays from finite-element methods (FEM) simulations, which allows an easy description of the CMUT behavior in air and fluids and simplifies the investigation of wave propagation within the connecting fluid represented by FEM or transmission line matrix (TLM) models.
Abstract: Using piston radiator and plate capacitance theory capacitive micromachined ultrasound transducers (CMUT) membrane cells can be described by one-dimensional (1-D) model parameters. This paper describes in detail a new method, which derives a 1-D model for CMUT arrays from finite-element methods (FEM) simulations. A few static and harmonic FEM analyses of a single CMUT membrane cell are sufficient to derive the mechanical and electrical parameters of an equivalent piston as the moving part of the cell area. For an array of parallel-driven cells, the acoustic parameters are derived as a complex mechanical fluid impedance, depending on the membrane shape form. As a main advantage, the nonlinear behavior of the CMUT can be investigated much easier and faster compared to FEM simulations, e.g., for a design of the maximum applicable voltage depending on the input signal. The 1-D parameter model allows an easy description of the CMUT behavior in air and fluids and simplifies the investigation of wave propagation within the connecting fluid represented by FEM or transmission line matrix (TLM) models.
163 citations
TL;DR: In this article, a Kramers-Kronig transform was employed to calculate the polarization resistance from the frequency-dependent imaginary component of carbon steel in solution at ambient temperature and for aluminum and Al.
Abstract: A Kramers‐Kronig transform that is useful for validating electrochemical and corrosion impedance data is employed to calculate the polarization resistance from the frequency‐dependent imaginary component. Applications of the transform in the analysis of experimental impedance data for carbon steel in solution at ambient temperature and for aluminum and Al‐0.1P‐0.1In‐0.2‐Ga‐0.01Tl alloy in solution at 25°C are discussed.
162 citations