scholarly journals Estimation of the physical parameters of planets and stars in the gravitational equilibrium model

2016 ◽  
Vol 94 (4) ◽  
pp. 370-379 ◽  
Author(s):  
Sergey G. Fedosin
Keyword(s):  
Equilibrium Model ◽  
Pressure Field ◽  
Physical Parameters ◽  
Acceleration Field ◽  
Precise Calculation ◽  
Proposed Model ◽  
Calculation Results ◽  
Field Coefficient ◽  
Physical Quantities ◽  
Gravitational Equilibrium

The motion equations of matter in a gravitational field, acceleration field, pressure field, and other fields are considered based on the field theory. This enables us to derive simple formulas in the framework of the gravitational equilibrium model, which allow us to estimate the physical parameters of cosmic bodies. The acceleration field coefficient, η, and the pressure field coefficient, σ, are a function of the state of matter, and their sum is close in magnitude to the gravitational constant, G. In the presented model the dependence is found of the internal temperature and pressure on the current radius. The central temperatures and pressures are calculated for the Earth and the Sun, for a typical neutron star and a white dwarf. The heat flux and the thermal conductivity coefficient of these objects’ matter are found, and the formula for estimating the entropy is provided. All the quantities are compared with the calculation results in different models of cosmic bodies. The discovered good agreement with these data proves the effectiveness and universality of the proposed model for estimating the parameters of planets and stars and for more precise calculation of physical quantities.

scholarly journals The Generalized Poynting Theorem for the General Field and Solution of the 4/3 Problem

2019 ◽  
Vol 14 ◽  
pp. 19-40
Author(s):  
Sergey G. Fedosin
Keyword(s):  
Pressure Field ◽  
Mass Density ◽  
Relativistic Energy ◽  
Equilibrium System ◽  
Gravitational Fields ◽  
Acceleration Field ◽  
System Of Particles ◽  
Field Coefficient ◽  
The Given ◽  
Poynting Theorem

The generalized Poynting theorem is applied to the equilibrium system of particles, both inside and outside the system. The particles are bound to each other by means of the electromagnetic and gravitational fields, acceleration field and pressure field. As a result, the correlation is found between the acceleration field coefficient, the pressure field coefficient, the gravitational constant and the vacuum permittivity. This correlation also depends on the ratio of the charge density to the mass density of the particles inside the sphere. Due to the correlation between the given field coefficients the 4/3 problem is solved and the expression for the relativistic energy of the system is refined.

scholarly journals Couple stress fluid flow due to slow steady oscillations of a permeable sphere

2020 ◽  
Vol 9 (1) ◽  
pp. 352-360
Author(s):  
P. Aparna ◽  
P. Padmaja ◽  
N. Pothanna ◽  
J.V. Ramana Murthy
Keyword(s):  
Fluid Flow ◽  
Couple Stress ◽  
Bessel Functions ◽  
Pressure Field ◽  
Flow Region ◽  
Couple Stress Fluid ◽  
Physical Parameters ◽  
External Flows ◽  
Steady Oscillations ◽  
Permeable Sphere

AbstractThe study of oscillating flow of a Couple Stress fluid past a permeable sphere is considered. Analytical solution for the flow field in terms of stream function is obtained using modified Bessel functions. The formula for Drag acting on the sphere due external flow is evaluated. Pressure field for the flow region past and inside the sphere is obtained. Effects of physical parameters like couple stress parameter, permeability, frequency and geometric parameters on the drag due to internal and external flows are represented graphically. It is observed that the drag for viscous fluid flow will be less than the case of couple-stress fluid flow and hence couple stress fluids offer resistance for flow.

scholarly journals Numerical Model for the Analysis of Thermal Transients in District Heating Networks

2020 ◽  
Vol 197 ◽  
pp. 01004
Author(s):  
Martina Capone ◽  
Elisa Guelpa ◽  
Vittorio Verda
Keyword(s):  
Carbon Dioxide Emissions ◽  
Renewable Energy Sources ◽  
Management Strategies ◽  
District Heating ◽  
Equivalent Model ◽  
Computational Time ◽  
Physical Parameters ◽  
Thermal Transients ◽  
Proposed Model ◽  
Wide Range

As District Heating (DH) networks are experiencing an evolution towards the so-called 4th generation, there is a need to update the currently used models to take into account the ever-increasing complexity of this technology. Indeed, to further improve the reduction in energy consumption and carbon-dioxide emissions, a wide range of technologies and management strategies are being introduced within district heating, such as a large exploitation of Renewable Energy Sources (RES). As a consequence, thermal transients assume a major importance, posing the need to redefine the relevant physical parameters and to develop a model which accurately describes their behaviour. In this framework, this paper proposes a quantitative analysis of the influence of the pipe heat-capacity on the model. Moreover, an equivalent-model, which is able to take into account the two heat capacities of steel and water in just one equation, is proposed and compared with two commonly used approaches. One of the features of the proposed model is the suitability for application to large networks. To prove its capabilities, an application to the Turin district heating network, which is among the largest systems in Europe, is proposed. Results show significant improvements in terms of accuracy over computational time ratio.

scholarly journals A Dynamic Cavity Expansion Model for Rigid Projectile Penetration into Concrete considering the Compressibility and Nonlinear Constitutive Relations

Geofluids ◽  
2021 ◽  
Vol 2021 ◽  
pp. 1-13
Author(s):  
Fei Gao ◽  
Zhen Wang ◽  
Zhu Wen ◽  
Yuguo Ji
Keyword(s):  
Yield Criterion ◽  
Constitutive Relations ◽  
Cavity Expansion ◽  
Depth Of Penetration ◽  
Proposed Model ◽  
Rigid Projectile ◽  
Calculation Results ◽  
Expansion Model ◽  
Constitutive Parameters ◽  
Nonlinear Constitutive Relations

The P-α equation of state (EOS) and a nonlinear yield criterion are utilized to characterize the dynamic constitutive behavior of concrete targets subjected to projectile normal penetration. A dynamic cavity expansion model considering the compressibility and nonlinear constitutive relations for concrete material is developed. Then, a theoretical model to calculate the depth of penetration (DOP) for rigid projectile is established. Furthermore, the proposed model is validated based on the available test data as well as the calculation results by the linear compressible EOS and linear yield criterion. This study shows that the proposed model derived using the P-α EOS and nonlinear yield criterion can effectively reflect the plastic mechanical properties of concrete and is also suitable for predicting the DOP of concrete targets. In addition, the influence law of concrete constitutive parameters such as the cohesion strength, shear strength, internal friction coefficient, and elastic limit pressure on the DOP is revealed.

Flow between Stretchable Rotating Disks in an Anisotropic Porous Medium with Cattaneo Christov Heat Flux

2019 ◽  
Vol 393 ◽  
pp. 138-148
Author(s):  
K. Gowthami ◽  
P. Hari Prasad ◽  
B. Mallikarjuna ◽  
Oluwole Daniel Makinde
Keyword(s):  
Heat Flux ◽  
Porous Medium ◽  
Thermal Relaxation ◽  
Relaxation Parameter ◽  
Transport Processes ◽  
Rotation Parameter ◽  
Physical Parameters ◽  
Fluid Temperature ◽  
Anisotropic Porous Medium ◽  
Physical Quantities

A study on fully developed fluid flow between 2two stretchable disks in a 1porous medium is presented. The porous medium is assumed to be an anisotropic porous medium and described using Darcy’s model. Moreover Cattaneo - Christov heat flux 1model is used for heat transport processes. Numerical method 1is used to compute the solutions of non-dimensionalized equations and obtained results are discussed with the aid of graphs and table values on physical quantities (fluid velocity, fluid temperature, skin frication coefficients and Nusselt numbers) for various values of physical parameters, Darcy’ number in different directions, stretchable disk parameters, rotation parameter and thermal relaxation parameter. Increasing stretchable disks parameter reports opposite behavior on physical quantities at different disks. Positive and negative values of rotation parameter impact on physical quantities are presented and discussed. As increase in thermal relaxation parameter fluid temperature transfers in different directions between disks and Nusselt number values are enhanced at both disks.

Kron–Branin modelling of ultra-short pulsed signal microelectrode

2018 ◽  
Vol 81 (2) ◽  
pp. 21001
Author(s):  
Zhifei Xu ◽  
Blaise Ravelo ◽  
Yang Liu ◽  
Lu Zhao ◽  
Fabien Delaroche ◽  
...  
Keyword(s):  
Model Simulation ◽  
Signal Propagation ◽  
Atom Probe ◽  
Physical Parameters ◽  
Characteristic Matrix ◽  
Nanosecond Duration ◽  
S Parameter ◽  
Proposed Model ◽  
Structure Problem ◽  
Short Signal

An uncommon circuit modelling of microelectrode for ultra-short signal propagation is developed. The proposed model is based on the Tensorial Analysis of Network (TAN) using the Kron–Branin (KB) formalism. The systemic graph topology equivalent to the considered structure problem is established by assuming as unknown variables the branch currents. The TAN mathematical solution is determined after the KB characteristic matrix identification. The TAN can integrate various structure physical parameters. As proof of concept, via hole ended microelectrodes implemented on Kapton substrate were designed, fabricated and tested. The 0.1-MHz-to-6-GHz S-parameter KB model, simulation and measurement are in good agreement. In addition, time-domain analyses with nanosecond duration pulse signals were carried out to predict the microelectrode signal integrity. The modelled microstrip electrode is usually integrated in the atom probe tomography. The proposed unfamiliar KB method is particularly beneficial with respect to the computation speed and adaptability to various structures.

scholarly journals Research on Blade-Casing Rub-Impact Mechanism by Experiment and Simulation in Aeroengines

2019 ◽  
Vol 2019 ◽  
pp. 1-15 ◽  
Author(s):  
Jie Hong ◽  
Tianrang Li ◽  
Zhichao Liang ◽  
Dayi Zhang ◽  
Yanhong Ma
Keyword(s):  
High Speed ◽  
High Performance ◽  
Element Model ◽  
Physical Parameters ◽  
Test Rig ◽  
Calculation Results ◽  
Rotor Support ◽  
Blade Tip ◽  
Set Up ◽  
The Impact

Aeroengines pursue high performance, and compressing blade-casing clearance has become one of the main ways to improve turbomachinery efficiency. Rub-impact faults occur frequently with clearance decreasing. A high-speed rotor-support-casing test rig was set up, and the mechanism tests of light and heavy rub-impact were carried out. A finite element model of the test rig was established, and the calculation results were in good agreement with the experimental results under both kinds of rub-impact conditions. Based on the actual blade-casing structure model, the effects of the major physical parameters including imbalance and material characteristics were investigated. During the rub-impact, the highest stress occurs at the blade tip first and then it is transmitted to the blade root. Deformation on the impact blade tip generates easily with decreased yield strength, and stress concentration at the blade tip occurs obviously with weaker stiffness. The agreement of the computation results with the experimental data indicates the method could be used to estimate rub-impact characteristics and is effective in design and analyses process.

scholarly journals A Flexible 5-In-1 Microsensor for Internal Microscopic Diagnosis of Vanadium Redox Flow Battery Charging Process

Sensors ◽  
2019 ◽  
Vol 19 (5) ◽  
pp. 1030 ◽  
Author(s):  
Chi-Yuan Lee ◽  
Chin-Lung Hsieh ◽  
Chia-Hung Chen ◽  
Yen-Pu Huang ◽  
Chong-An Jiang ◽  
...  
Keyword(s):  
Real Time ◽  
Vanadium Redox Flow Battery ◽  
Optimum Operating ◽  
Physical Parameters ◽  
Redox Flow Battery ◽  
Flow Battery ◽  
Mems Technology ◽  
Microscopic Diagnosis ◽  
Vanadium Redox ◽  
Physical Quantities

Multiple important physical parameters in the vanadium redox flow battery are difficult to measure accurately, and the multiple important physical parameters (e.g., temperature, flow, voltage, current, pressure, and electrolyte concentration) are correlated with each other; all of them have a critical influence on the performance and life of vanadium redox flow battery. In terms of the feed of fuel to vanadium redox flow battery, the pump conveys electrolytes from the outside to inside for reaction. As the performance of vanadium redox flow battery can be tested only by an external machine—after which, the speed of pump is adjusted to control the flow velocity of electrolyte—the optimum performance cannot be obtained. There is a demand for internal real-time microscopic diagnosis of vanadium redox flow batteries, and this study uses micro-electro-mechanical systems (MEMS) technology to develop a flexible five-in-one (temperature, flow, voltage, current, and pressure) microsensor, which is embedded in vanadium redox flow battery, for real-time sensing. Its advantages include: (1) Small size and the simultaneous measurement of five important physical quantities; (2) elastic measurement position and accurate embedding; and (3) high accuracy, sensitivity, and quick response time. The flexible five-in-one microsensor embedded in the vanadium redox flow battery can instantly monitor the changes in different physical quantities in the vanadium redox flow battery during charging; as such, optimum operating parameters can be found out so that performance and life can be enhancec.

Physics of Flexible Magnetic Filaments

2011 ◽  
Vol 222 ◽  
pp. 221-224 ◽  
Author(s):  
Ivars Javaitis ◽  
Vineta Zilgalve
Keyword(s):  
Magnetic Field ◽  
Numerical Simulation ◽  
Coefficient Of Friction ◽  
Low Frequency ◽  
Rotating Magnetic Field ◽  
Physical Parameters ◽  
Filament Dynamics ◽  
Field Coefficient ◽  
Stable Shape

A model of elastic magnetic filaments is developed, which allows investigating the dependence of filament dynamics on such physical parameters as magnetoelastic number (Cm), frequency of magnetic field, coefficient of friction, etc. By numerical simulation of the dynamics of filament shaping under the action of magnetic field it is shown that a characteristic U-like stable shape (hairpins) can form. Such a shape of filament can exist in the case of low-frequency rotating magnetic field. At the frequency increasing the U-like shape transforms to the S-like one. In the present work it is shown that in unsteady magnetic field a flexible magnetic filament “swims” in the direction of magnetic field.

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