scholarly journals On Experimental Data of the TCR of TFRs and Their Relation to Theoretical Models of Conduction Mechanism

1985 ◽  
Vol 11 (4) ◽  
pp. 255-259 ◽  
Author(s):  
I. Storbeck ◽  
M. Wolf
Keyword(s):  
Experimental Data ◽  
Grain Size ◽  
Theoretical Model ◽  
Temperature Dependence ◽  
Electrical Conduction ◽  
Conduction Mechanism ◽  
Volume Fraction ◽  
Theoretical Models ◽  
Strain Dependence ◽  
Conducting Component

Any theory of electrical conduction in TFRs encounters mainly two problems: (i) explanation of the dependence of R□on properties of conducting component (volume fraction, grain size, resistivity), (ii) explanation of the temperature dependence of R□taking into account (i). In order to achieve this one has to fit some microscopic parameters to experimental R□-and TCR-values, and to check if they are reasonable or not. The aim of the following discussion is to show, that such a fitting by means of experimental TCR-values is not correct. This is due to the fact that TCR-behaviour, as is well known, is determined also by the dependence of resistivity on strain. But any theoretical model neglects strains, also those who are induced by thermal strains. By means of published experiments concerning the strain dependence of resistance, the magnitude is estimated by which the TCR-values have to be corrected for the described fit.

scholarly journals Dependence of the Sheet Resistivity and Current Noise Behaviour of the Grain Size and Volume Fraction of Conducting Material in Thick-Film Resistors Experiments

1988 ◽  
Vol 13 (1) ◽  
pp. 1-6 ◽  
Author(s):  
F. Müller ◽  
M. Wolf
Keyword(s):  
Grain Size ◽  
Thick Film ◽  
Electrical Conduction ◽  
Conduction Mechanism ◽  
Volume Fraction ◽  
Experimental Results ◽  
Current Noise ◽  
Sheet Resistivity ◽  
Conducting Material ◽  
Electrical Conduction Mechanism

Experimental results concerning the dependence of the sheet resistivity and the noise coefficient on the grain size and the volume fraction, respectively, of the metallic-like component in Bi2Ru2O7-based thick-film resistors are presented. The results are compared with current models for the electrical conduction mechanism in these resistors.

TEMPERATURE DEPENDENCE BEHAVIOR OF ELECTRICAL RESISTIVITY IN NOBLE METALS AT LOW TEMPERATURES

2014 ◽  
Vol 5 (3) ◽  
pp. 982-992 ◽  
Author(s):  
M AL-Jalali
Keyword(s):  
Experimental Data ◽  
Electrical Resistivity ◽  
Temperature Dependence ◽  
Concentration Dependence ◽  
Low Temperatures ◽  
Noble Metals ◽  
Phonon Scattering ◽  
Theoretical Models ◽  
Residual Resistivity ◽  
Electron Phonon Scattering

Resistivity temperature – dependence and residual resistivity concentration-dependence in pure noble metals(Cu, Ag, Au) have been studied at low temperatures. Dominations of electron – dislocation and impurity, electron-electron, and electron-phonon scattering were analyzed, contribution of these mechanisms to resistivity were discussed, taking into consideration existing theoretical models and available experimental data, where some new results and ideas were investigated.

Retrieval of Bio-Geophysical Parameters from Remotely Sensing Data by Using Bayesian Methodology

2007 ◽  
pp. 222-252
Author(s):  
C. Notarnicola
Keyword(s):  
Experimental Data ◽  
Theoretical Model ◽  
Theoretical Models ◽  
Data Sets ◽  
Model Errors ◽  
Sources Of Information ◽  
Remotely Sensed Data ◽  
Bayesian Methodology ◽  
Information Models ◽  
Bayesian Methodologies

This chapter introduces the use of Bayesian methodology for inversion purposes: the extraction of bio-geophysical parameters from remotely sensed data. Multisources information, such as different polarizations, frequencies, and sensors are fundamental to the development of operationally useful inversion systems. In this context, Bayesian methodologies offer a convenient tool of combining two or more disparate sources of information, models, and data. The chapter describes the development of a general model starting from a theoretical model, including the sensor noise and the model errors, by using a Bayesian approach. Furthermore, the developed procedure is applied to some experimental data sets. The author hopes that considering theoretical models and experimental data in many different configurations can give an idea of the versatility and robustness of the Bayesian framework.

scholarly journals On the correspondence of theoretical models of longitudinal vibrations of a rod with experimental data

2021 ◽  
Vol 8 (2) ◽  
pp. 270-281
Author(s):  
Alexander L. Popov ◽  
◽  
Sergei A. Sadovsky ◽  
Keyword(s):  
Experimental Data ◽  
Wave Equation ◽  
Theoretical Model ◽  
Natural Frequencies ◽  
Lateral Displacement ◽  
Experimental Spectrum ◽  
Theoretical Models ◽  
Transverse Displacement ◽  
Longitudinal Vibrations ◽  
Longitudinal Waves

A number of theoretical models are known for describing longitudinal vibrations of a rod. The simplest and most common is based on the wave equation. Next comes a model that takes into account lateral displacement (Rayleigh correction). The Bishop model is considered to be more perfect, taking into account both transverse displacement and shear deformation. It would seem that the more perfect the theoretical model, the better it should be consistent with experimental data. Nevertheless, when comparing with a really defined experimental spectrum of longitudinal vibrations of a rod on a large base of natural frequencies, it turns out that this is not quite so. Moreover, in the relative loss is the most complex Bishop model. Comparisons were made for a smooth long cylindrical rod. The questions of refinement with the help of experimentally found frequencies of the velocity of longitudinal waves and the Poisson’s ratio of the rod material are also touched.

Comparison of Different Theoretical Models to Experimental Data on Viscosity of Binary Liquid Alloys

2007 ◽  
Vol 537-538 ◽  
pp. 489-496 ◽  
Author(s):  
I. Budai ◽  
Mária Z. Benkő ◽  
György Kaptay
Keyword(s):  
Experimental Data ◽  
Temperature Dependence ◽  
Theoretical Models ◽  
Liquid Alloys ◽  
Binary Liquid ◽  
New Equation ◽  
Metallic Systems

Six different theoretical equations are compared in the present paper with experimental data, measured for 28 binary liquid metallic systems. General conclusions are drawn on the ability of the different theoretical models to describe the concentration and temperature dependence of the viscosity of liquid alloys. A new equation is derived, being able to predict the viscosity in multicomponents alloy even if the viscosities of the pure components are not known.

scholarly journals Electrical Conductivity of New Nanoparticle Enhanced Fluids: An Experimental Study

Nanomaterials ◽  
2019 ◽  
Vol 9 (9) ◽  
pp. 1228 ◽  
Author(s):  
Chereches ◽  
Minea
Keyword(s):  
Experimental Data ◽  
Electrical Conductivity ◽  
Base Fluid ◽  
Volume Concentration ◽  
Volume Fraction ◽  
Three Dimensional ◽  
Sio2 Nanoparticles ◽  
Theoretical Models ◽  
Conductivity Ratio ◽  
Hybrid Nanofluids

In this research, the electrical conductivity of simple and hybrid nanofluids containing Al2O3, TiO2 and SiO2 nanoparticles and water as the base fluid was experimentally studied at ambient temperature and with temperature variation in the range of 20–60 °C. A comparison of the experimental data with existing theoretical models demonstrated that the theoretical models under-predict the experimental data. Consequently, several correlations were developed for nanofluid electrical conductivity estimation in relation to temperature and volume concentration. The electrical conductivity of both simple and hybrid nanofluids increased linearly with both volume concentration and temperature upsurge. More precisely, by adding nanoparticles to water, the electrical conductivity increased from 11 times up to 58 times for both simple and hybrid nanofluids, with the maximum values being attained for the 3% volume concentration. Plus, a three-dimensional regression analysis was performed to correlate the electrical conductivity with temperature and volume fraction of the titania and silica nanofluids. The thermo-electrical conductivity ratio has been calculated based on electrical conductivity experimental results and previously determined thermal conductivity. Very low figures were noticed. Concluding, one may affirm that further experimental work is needed to completely elucidate the behavior of nanofluids in terms of electrical conductivity.

Microstructure Alteration in the High-Speed Machining of Titanium Alloy Involved With Tool Wear and Cryogenic Condition

2021 ◽  
Author(s):  
Xin Li ◽  
Xueping Zhang ◽  
Rajiv Shivpuri
Keyword(s):  
Experimental Data ◽  
Grain Size ◽  
Titanium Alloy ◽  
Tool Wear ◽  
High Speed ◽  
Volume Fraction ◽  
High Speed Machining ◽  
Phase Volume ◽  
Machined Surface ◽  
Phase Volume Fraction

Abstract The microstructure alteration generated in the high-speed machining of titanium alloy has significant influence on the performance, quality and service life of production. The prediction of grain size or phase distribution based on physics mechanism or the regression of experimental data have been reported in the process of static or quasi-static state. However, it is still a challenge to predict the phase transformation and grain growth process in machining accurately and effectively since it has characteristics of high strain, strain rate and temperature. In this paper, a novel FEM-based model involving with the microstructure alteration was introduced and implemented to predict finial grain size or phase result in the high-speed machining of Ti-6Al-4V alloys especially at the machined surface. The phase transformation process was proposed and discussed by considering tool wear and cryogenic condition at machined surface, while the microstructure results were displayed on the chip in the previous works. Firstly, the phase volume fraction and grain size were modelled by experimental data. Then the simulation based on the self-consistent method (SCM) was used to output strain and temperature distribution. Thirdly, the phase volume fraction and grain size expressions were transmitted into subroutine programs and the microstructure alteration process under the different cutting conditions were showed in the FE results. The simulation results of temperature, phase fraction and strain were compared against previous simulation or experiment results in published papers revealing good agreement. The proposed model was further to investigate the influence of tool wear and cutting temperature on machined surface. The results indicated that the tool wear increased heat at the flank face significantly resulting to β phase increasing and grain growth at machined surface and the cryogenic condition would lower temperature gradient as well as stress gradient contributing to reduce roughness and residual stress.

scholarly journals Towards Sophisticated 3D Interphase Modelling of Advanced Bionanocomposites via Atomic Force Microscopy

2020 ◽  
Vol 2020 ◽  
pp. 1-22
Author(s):  
Mohanad Mousa ◽  
Yu Dong
Keyword(s):  
Experimental Data ◽  
Volume Fraction ◽  
Hard Core ◽  
Theoretical Models ◽  
Halloysite Nanotubes ◽  
Accurate Estimation ◽  
Effective Volume ◽  
Force Microscopy ◽  
Effective Volume Fraction ◽  
Cloisite 30B

Nanomechanical properties and interphase dimensions of PVA bionanocomposites reinforced with halloysite nanotubes (HNTs) and Cloisite 30B montmorillonite (MMT) were evaluated by means of peak force quantitative nanomechanical mapping (PFQNM). A three-phase theoretical composite model was established based on hard-core–soft-shell structures consisting of hard mono-/polydispersed anisotropic particles and soft interphase and matrices. Halpin-Tsai model and Mori-Tanaka model were employed to predict experimentally determined tensile moduli of PVA bionanocomposites where effective volume fraction of randomly oriented nanoparticles resulted from the inclusion of interphase properties and volume fractions. Overall, it was suggested that the estimation of elastic modulus according to effective volume fraction of nanoparticles revealed better agreement with experimental data as opposed to that based upon their nominal volume fraction. In particular, the use of polydispersed HNTs and Cloisite 30B MMT clays with Fuller particulate gradation was proven to yield the best prediction when compared with experimental data among all proposed theoretical models. This study overcomes the neglected real interphase characteristics in modelling nanocomposite materials with much more accurate estimation of their mechanical properties.

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