scholarly journals Fractional Derivative Modification of Drude Model

Sensors ◽  
2021 ◽  
Vol 21 (15) ◽  
pp. 4974
Author(s):  
Karol Karpiński ◽  
Sylwia Zielińska-Raczyńska ◽  
David Ziemkiewicz
Keyword(s):  
Biological Tissues ◽  
Theoretical Description ◽  
Drude Model ◽  
Dielectric Susceptibility ◽  
Acoustic Wave Propagation ◽  
Parameter Modification ◽  
Two Parameter ◽  
Flexible Model ◽  
Accuracy And Stability ◽  
Good Agreement

A novel, two-parameter modification of a Drude model, based on fractional time derivatives, is presented. The dielectric susceptibility is calculated analytically and simulated numerically, showing good agreement between theoretical description and numerical results. The absorption coefficient and wave vector are shown to follow a power law in the frequency domain, which is a common phenomenon in electromagnetic and acoustic wave propagation in complex media such as biological tissues. The main novelty of the proposal is the introduction of two separate parameters that provide a more flexible model than most other approaches found in the literature. Moreover, an efficient numerical implementation of the model is presented and its accuracy and stability are examined. Finally, the model is applied to an exemplary soft tissue, confirming its flexibility and usefulness in the context of medical biosensors.

A two-parameter Margules method for modelling the thermodynamic mixing properties of albite-water melts

1992 ◽  
Vol 83 (1-2) ◽  
pp. 423-428 ◽  
Author(s):  
James G. Blencoe
Keyword(s):  
Phase Equilibrium ◽  
Phase Relations ◽  
Phase Equilibrium Data ◽  
Excess Enthalpies ◽  
Calorimetric Data ◽  
Mixing Properties ◽  
Modelling Method ◽  
Equilibrium Data ◽  
Two Parameter ◽  
Good Agreement

ABSTRACTA two-parameter Margules method has been developed for modelling the thermodynamic mixing properties and hypersolidus phase relations of albite-water (ab-w) melts. The method is based largely on phase-equilibrium and calorimetric data that are either currently available or readily obtainable; P-V-T data are not required.The new modelling method has been applied to calculate: (1) thermodynamic mixing properties for ab-w melts at 2-5 kbar, 815°C; and (2) hypersolidus phase relations for the ab-w system at 2·5 kbar. Results are uniformly positive—activity-composition relations are similar to those predicted by equations based on P-V-T data, excess enthalpies are in good agreement with data obtained from calorimetry, and calculated phase relations are fully compatible with phase-equilibrium data for ab-w melts acquired at 2·5 kbar.It is concluded that the Margules method for thermodynamic modelling of ab-w melts is a practical alternative to the P-V-T modelling method.

THEORY OF GIANT MAGNETORESISTANCE IN NONMULTILAYER MAGNETIC SYSTEMS

1993 ◽  
Vol 07 (21) ◽  
pp. 1365-1372 ◽  
Author(s):  
L. SHENG ◽  
D. Y. XING
Keyword(s):  
Giant Magnetoresistance ◽  
Theoretical Description ◽  
Single Domain ◽  
Magnetic Systems ◽  
Potential Barriers ◽  
Dependent Potential ◽  
Spin Dependent Scattering ◽  
Ferromagnetic Particles ◽  
Good Agreement

We present a simple theoretical description of recently measured giant magnetoresistance (GMR) effect in granular ferromagnetic systems. We propose that single-domain ferromagnetic particles embedded in a metallic medium form a series of randomly distributed and spin-dependent potential barriers and wells. This spin-dependent scattering is considered as the main origin of the GMR effect. Good agreement with experiment is found for phase-separated Co x Cu 1−x samples.

CAUSAL FREQUENCY-LINEAR ATTENUATION ALGORITHM FOR TIME DOMAIN PROBLEMS

2009 ◽  
Vol 17 (04) ◽  
pp. 357-364
Author(s):  
B. EDWARD MCDONALD
Keyword(s):  
Wave Propagation ◽  
Time Domain ◽  
Fourier Transforms ◽  
Phase Speed ◽  
Sandy Sediment ◽  
Acoustic Wave Propagation ◽  
In Situ Data ◽  
Ocean Sediment ◽  
Good Agreement

Attenuation which is linear in frequency (as opposed to quadratic as for laminar viscosity) occurs in porous media wave propagation and biomedical applications. Straightforward use of Fourier transforms for frequency-linear attenuation violates causality. We give a causal time domain algorithm with numerical stability criteria and verify its accuracy. For acoustic wave propagation in ocean sediment, the algorithm results in a mild increase of phase speed with frequency as a result of the Kramers–Kronig relation. The algorithm gives results in good agreement with in situ data for sandy sediment.

An analytical investigation of the cylindrical capacitor in the framework of a two-parameter modification of Born–Infeld electrodynamics

2018 ◽  
Vol 15 (07) ◽  
pp. 1850118 ◽  
Author(s):  
F. Fathi ◽  
S. K. Moayedi
Keyword(s):  
Electric Fields ◽  
Weak Field ◽  
Analytical Investigation ◽  
Nonlinear Electrodynamics ◽  
Self Energy ◽  
Maxwell Electrodynamics ◽  
Parameter Modification ◽  
Cylindrical Capacitor ◽  
Electrostatic Potential Energy ◽  
Two Parameter

Iacopini and Zavattini [Vacuum polarization effects in the [Formula: see text] atom and the Born–Infeld electromagnetic theory, Nuovo Cimento B 78 (1983) 38–52] proposed a [Formula: see text]-two-parameter modification of Born–Infeld electrodynamics, in which the classical self-energy for an electron takes a finite value for [Formula: see text]. In this paper, we want to study a cylindrical capacitor from the viewpoint of Iacopini–Zavattini nonlinear electrodynamics analytically. The capacitance, the electrostatic potential energy, and the potential difference between the plates of a cylindrical capacitor are calculated in the framework of Iacopini–Zavattini electrodynamics for two specific values of [Formula: see text] and [Formula: see text]. The study of the behavior of a nonlinear cylindrical capacitor in the weak electric fields shows that our results are compatible with the correspondence principle, i.e. we recover the results of Maxwell electrodynamics in the weak field regime. Finally, the invariance of Iacopini–Zavattini nonlinear electrodynamics under the duality transformation is investigated.

Agar phantoms of biological tissue for fluorescence monitoring of photodynamic therapy

2022 ◽  
Vol 52 (1) ◽  
pp. 63-68
Author(s):  
A V Khilov ◽  
V A Shishkova ◽  
E A Sergeeva ◽  
D A Kurakina ◽  
M Yu Kirillin
Keyword(s):  
Optical Properties ◽  
Photodynamic Therapy ◽  
Intravenous Injection ◽  
Biological Tissue ◽  
Biological Tissues ◽  
Fluorescent Properties ◽  
Fluorescent Marker ◽  
Scattering Coefficients ◽  
Scattering Spectra ◽  
Good Agreement

Abstract An approach to fabricating agar phantoms mimicking spectral optical properties of biological tissues with fluorescent inclusions is proposed, which allows one to imitate the problem of optical visualisation of superficial biological tissues after the administration of a chlorin-based photosensitiser. The different arrangement of a fluorescent layer within a phantom makes it possible to simulate biological tissue in the cases of both topical application and intravenous injection of a photosensitiser. It is shown that absorption and scattering spectra of phantoms are in good agreement with the spectra of real biological tissues in the wavelength range of 500-800 nm. Changes in spectra of absorption and scattering coefficients of phantoms, as well as in their fluorescent properties induced by the addition of a fluorescent marker (chlorinbased photosensitiser) are demonstrated.

Deviation of the Calculated of Density of Refrigerant Fluids in Both Super and Sub Critical Regions

2011 ◽  
Author(s):  
Neda Mobinipouya
Keyword(s):  
Thermodynamic Properties ◽  
Speed Of Sound ◽  
Equations Of State ◽  
Numerical Procedure ◽  
Corresponding States ◽  
Temperature Range ◽  
Critical Regions ◽  
Two Parameter ◽  
Good Agreement

A numerical procedure has successfully predicted accurate values of thermodynamic properties in seven cubic equations of state (EOS) in predicting thermodynamic properties of nine ozone-safe refrigerants both in super and sub-critical regions. Refrigerants include R22, R32, R123, R124, R125, R134a, R141b, R143, and R152a and equations of state, considered here, are Ihm-Song-Mason (ISM), Peng-Robinson (PR) [2], Redlich-Kwong (RK), Soave-Redlikh-Kwong (SRK), Modified Redlickh-Kwong (MRK), Nasrifar-Moshfeghian (NM), and TCC were shown in this paper. In general, the results are in favor of the preference of TCC and PR EOS over other remaining EOS’s in predicting gas densities of all aforementioned refrigerants in both super and sub critical regions. Typically, PR and SRK are in good agreement with those obtained from recent correlations and speed of sound measurements. Therefore, these two EOS stand over other EOS both in sub and super critical regions. All EOS follow two-parameter principle of corresponding states at T/Tc higher than 8 and lower than 1 except NM EOS. In the temperature range 1<T/Tc<8, PR and SRK still follow above mentioned principle. The same trend has been observed for other refrigerants.

THEORETICAL STUDIES ON PIEZORESISTIVE EFFECT OF P-TYPE DIAMOND FILMS

2002 ◽  
Vol 16 (06n07) ◽  
pp. 916-921
Author(s):  
W. L. WANG ◽  
K. J. LIAO ◽  
C. Z. CAI ◽  
C. Y. KONG ◽  
S. X. WANG
Keyword(s):  
Diamond Films ◽  
Uniaxial Stress ◽  
Theoretical Description ◽  
Boltzmann Transport ◽  
Piezoresistive Effect ◽  
Relaxation Time Approximation ◽  
Hole Band ◽  
Mixed Scattering ◽  
P Type ◽  
Good Agreement

In this paper, based on the Fuchs and Sondheimer theory and valence band split-off model, a theoretical description of the piezoresistive effect in P-type heteroepitaxial diamond films was presented by solving the Boltzmann transport equation in the relaxation time approximation, in which a mixed scattering by lattice vibration, ionized impurities and surface was considered. A calculating expression of the piezoresistive effect has been developed in a parallel connection resistance model for the light-hole band, the heavy-hole band and the split-off band. The calculating results were in good agreement with the experimental data, indicating that the prezoresistive effect in diamond films was mainly ascribed to the hole band split-off under a uniaxial stress.

scholarly journals Hydrodynamic model for UV laser ablation of polymers

1999 ◽  
Vol 17 (4) ◽  
pp. 585-590 ◽  
Author(s):  
Y.V. AFANASIEV ◽  
V.A. ISAKOV ◽  
I.N. ZAVESTOVSKAYA ◽  
B.N. CHICHKOV ◽  
F. VON ALVENSLEBEN ◽  
...  
Keyword(s):  
Phase Transition ◽  
Laser Ablation ◽  
Theoretical Description ◽  
Hydrodynamic Equations ◽  
Uv Laser ◽  
Hydrodynamic Models ◽  
Surface Evaporation ◽  
Vapor Plume ◽  
Analytical Expressions ◽  
Good Agreement

The applicability of hydrodynamic models for theoretical description of UV laser ablation of polymers is studied. The plume formation is considered as a first-kind phase transition. In case of strongly absorbing polymers this phase transition occurs as a surface evaporation, and in case of weakly absorbing polymers as a bulk evaporation. The vapor plume is assumed to be transparent for laser radiation, and its expansion is described by the isoentropic hydrodynamic equations. New analytical expressions for ablation (etch) depths per pulse are obtained, which are in good agreement with the available experimental data (Afanasiev et al. 1997).

scholarly journals Ultra-low thermal conductivity and acoustic dynamics of Si nanostructured metalattices probed using ultrafast high harmonic beams

2019 ◽  
Vol 205 ◽  
pp. 04006
Author(s):  
Begoña Abad ◽  
Travis Frazer ◽  
Joshua Knobloch ◽  
Jorge Hernández-Charpak ◽  
Hiu Cheng ◽  
...  
Keyword(s):  
Thermal Conductivity ◽  
Acoustic Wave ◽  
Thermal Transport ◽  
Extreme Ultraviolet ◽  
High Harmonic ◽  
Wave Dispersion ◽  
Acoustic Wave Propagation ◽  
High Quality ◽  
Very High ◽  
Good Agreement

We extend optical nanometrology capabilities to smaller dimensions by using tabletop coherent extreme ultraviolet (EUV) beams. Specifically, we characterize thermal transport and acoustic wave propagation in 3D periodic silicon inverse metalattices with <15nm characteristic dimensions. Measurements of the thermal transport demonstrate that metalattices may significantly impede heat flow, making them promising candidates for thermoelectric applications. Extraction of the acoustic wave dispersion down to ~100nm shows good agreement with finite element predictions, confirming that these semiconductor metalattices were fabricated with a very high-quality. These results demonstrate that EUV nanometrology is capable of extracting both dispersion relations, and thermal properties of 3D complex nano-systems, with applications including informed design and process control of nanoscale devices.

scholarly journals Modeling and simulating the neuromuscular mechanisms regulating ankle and knee joint stiffness during human locomotion

2015 ◽  
Vol 114 (4) ◽  
pp. 2509-2527 ◽  
Author(s):  
Massimo Sartori ◽  
Marco Maculan ◽  
Claudio Pizzolato ◽  
Monica Reggiani ◽  
Dario Farina
Keyword(s):  
Muscle Activation ◽  
Joint Stiffness ◽  
Human Locomotion ◽  
Biological Tissues ◽  
Musculoskeletal Model ◽  
Theoretical Description ◽  
Knee Joints ◽  
Dynamic Simulations ◽  
Muscle Groups ◽  
The Individual

This work presents an electrophysiologically and dynamically consistent musculoskeletal model to predict stiffness in the human ankle and knee joints as derived from the joints constituent biological tissues (i.e., the spanning musculotendon units). The modeling method we propose uses electromyography (EMG) recordings from 13 muscle groups to drive forward dynamic simulations of the human leg in five healthy subjects during overground walking and running. The EMG-driven musculoskeletal model estimates musculotendon and resulting joint stiffness that is consistent with experimental EMG data as well as with the experimental joint moments. This provides a framework that allows for the first time observing 1) the elastic interplay between the knee and ankle joints, 2) the individual muscle contribution to joint stiffness, and 3) the underlying co-contraction strategies. It provides a theoretical description of how stiffness modulates as a function of muscle activation, fiber contraction, and interacting tendon dynamics. Furthermore, it describes how this differs from currently available stiffness definitions, including quasi-stiffness and short-range stiffness. This work offers a theoretical and computational basis for describing and investigating the neuromuscular mechanisms underlying human locomotion.

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