Search results for "Electrical resistance and conductance"
showing 10 items of 47 documents
Novel Wood Resistance Measurement Method Reducing the Initial Transient Instabilities Arising in DC Methods Due to Polarization Effects
2019
A novel method for measuring the electrical resistance in wood is presented. It is based on applying an Alternating Current (AC) to two electrodes rammed into the wood. The method reduces the transient time for value stabilization. In case of Direct Current (DC) resistance measurement methods, typically used in wood measurement, an initial transient exists, invalidating the measured value during an initial transient period. This measurement method uses an electronic circuit based on a relaxation oscillator where the wood automatically sets the oscillation frequency depending on its electrical resistance. Compared to other AC methods, this circuit greatly simplifies the measurement process, …
Long-range vortex transfer in superconducting nanowires
2019
Under high-enough values of perpendicularly-applied magnetic feld and current, a type-II superconductor presents a fnite resistance caused by the vortex motion driven by the Lorentz force. To recover the dissipation-free conduction state, strategies for minimizing vortex motion have been intensely studied in the last decades. However, the non-local vortex motion, arising in areas depleted of current, has been scarcely investigated despite its potential application for logic devices. Here, we propose a route to transfer vortices carried by non-local motion through long distances (up to 10 micrometers) in 50nm-wide superconducting WC nanowires grown by Ga+ Focused Ion Beam Induced Deposition.…
High resistance measurement circuit for fiber materials: Application to moisture content estimation
2018
Abstract Measuring very high resistance values is a difficult task since low voltage or currents are present and thus, noise and amplification must be carefully done, especially when low resistance values are required to be measured using the same circuit, too. This work proposes a novel and accurate measurement instrument for a wide range of resistance values oriented to portable applications, i.e. low power and low supply voltage (5 V) for battery operated equipment, with a small circuit design including analog sensing, digital interface (data reading and control) using a microcontroller and external communication. The proposed circuit includes an inverter attenuator with layout and confi…
Electric and elastic properties of conductive polymeric nanocomposites on macro- and nanoscales
2002
Abstract In the past several years, the macroscopic electric and elastic properties of conductive polymeric composites have been studied from the viewpoint of such applications as thermistors and pressure sensors. In particular, we studied carbon black (CB) polymeric nanocomposites on macro- and nanoscales, using polyisoprene as the composite matrix. The filler component was an extra conductive carbon black (PRINTEX XE2, DEGUSSA) with a primary particle diameter of about 30 nm. A very strong reversible tensoresistive effect of electric resistance dependence on uniaxial tension deformation was observed in composites with the 10 carbon black mass parts added to 100 mass parts of polyisoprene.…
Determination of rate constants of ion transfer kinetics across immiscible electrolyte solutions
1998
Abstract The rotating diffusion cell was used to study ion transfer across the interface between two immiscible electrolyte solutions. Tetrabutylammonium was chosen as the transferring cation and lithium chloride as the supporting electrolyte in aqueous phase. Tetrabutylammonium tetrakis-(4-fluorophenyl)-borate in 2-nitrophenyl-octylether was used as the organic electrolyte solution supported in the porous membrane. The quasi-steady state current–voltage curves were measured both by applying potential steps and by imposing a slow potential sweep. The analysis of experimental results was based on the comparison with the theoretical current–voltage curves and on the Koutecky–Levich plots. The…
Colossal Density-Driven Resistance Response in the Negative Charge Transfer Insulator MnS2
2021
A reversible density driven insulator to metal to insulator transition in high-spin MnS_{2} is experimentally observed, leading with a colossal electrical resistance drop of 10^{8} Ω by 12 GPa. Density functional theory simulations reveal the metallization to be unexpectedly driven by previously unoccupied S_{2}^{2-} σ_{3p}^{*} antibonding states crossing the Fermi level. This is a unique variant of the charge transfer insulator to metal transition for negative charge transfer insulators having anions with an unsaturated valence. By 36 GPa the emergence of the low-spin insulating arsenopyrite (P2_{1}/c) is confirmed, and the bulk metallicity is broken with the system returning to an insula…
LiCrO2 Under Pressure: In-Situ Structural and Vibrational Studies
2018
The high-pressure behaviour of LiCrO2, a compound isostructural to the battery compound LiCoO2, has been investigated by synchrotron-based angle-dispersive X-ray powder diffraction, Raman spectroscopy, and resistance measurements up to 41, 30, and 10 Gpa, respectively. The stability of the layered structured compound on a triangular lattice with R-3m space group is confirmed in all three measurements up to the highest pressure reached. The dependence of lattice parameters and unit-cell volume with pressure has been determined from the structural refinements of X-ray diffraction patterns that are used to extract the axial compressibilities and bulk modulus by means of Birch&ndash
<title>Laser-pulse-induced chemical reactions and surface patterning in Co-Si and Co-Ti-Si films: investigations by x-ray diffraction and atomi…
2001
X-ray diffraction patterns reflected from the laser treated crystalline CoSi2 layer, the measurements of surface electrical resistance and atomic force microscopy micrographs confirm the 'generation-diffusion-deformational instabilities' model of formation of defect ordered structures of various types. The CO2 laser induced decrease of the thermal coefficient of resistance to zero in Co-Ti-Si films is realized. X-ray diffraction studies of the treated films confirm that the obtained (alpha) changes with number of laser pulses are caused due to solid phase reaction Co + 2Si equals CoSi2 and 5Ti + 3Si equals Ti5Si3.© (2001) COPYRIGHT SPIE--The International Society for Optical Engineering. Do…
The electromigration and diffusion of hydrogen in molybdenum
1990
Abstract The electromigration and diffusion of hydrogen atoms in molybdenum were investigated using the resistance method in the temperature range 293–773 K. The following dependence of the diffusion coefficient D and electrical mobility vE on temperature were obtained: D = (5.3 ± 1.53) × 10 −10 exp {− (0.8 ± 0.01) eV kT } { m 2 s −1 } v E = (1.24 ± 0.19) × 10 −8 exp {− (0.9 ± 0.01) eV kT }{ m 2 ( V s ) −1 } . The hydrogen migrates towards the cathode and the effective valency grows with temperature, fulfilling the relation Z eff = (1.42 ± 0.03) − (5.0 ± 0.2) × 10 −8 (Ω m ) ρ ; where ρ is the specific electric resistance.
The Reinforcement Effect of Strain Gauges Embedded in Low Modulus Materials
2013
The reinforcement effect of electrical resistance strain gauges is well-described in the literature, especially for strain gauges installed on surface. This paper considers the local reinforcement effect of strain gauges embedded within low Young modulus materials. In particular, by using a simple theoretical model, already used for strain gauges installed on the surface, it proposes a simple formula that allows the user to evaluate the local reinforcement effect of a generic strain gauge embedded on plastics, polymer composites, etc. The theoretical analysis has been integrated by numerical and experimental analyses, which confirmed the reliability of the proposed model.