scholarly journals The physical basis of the fission wave reactor

2008 ◽  
Vol 23 (2) ◽  
pp. 3-15 ◽  
Author(s):  
Volodymyr Pavlovych ◽  
Volodymyr Khotyayintsev ◽  
Olena Khotyayintseva
Keyword(s):  
Diffusion Equation ◽  
Main Idea ◽  
Stationary Wave ◽  
Short Review ◽  
Nuclear Fission ◽  
Stationary Processes ◽  
Wave Parameters ◽  
Nuclear Burning ◽  
Fission Wave

The main idea of slow nuclear fission wave reactor is discussed and short review of the existing works is also presented. The aim of this paper is to clarify the physics of processes, which define the stationary wave of nuclear burning, and to develop the approaches determining the wave parameters. It is shown that the diffusion equation for fluence can be used to describe the stationary and non-stationary processes in the nuclear fission wave. Two conditions of stationary wave existence are first formulated in the paper. The rule of determination of wave velocity as the eigenvalue of boundary problem is also formulated.

scholarly journals Electroanalytical Techniques for the Detection of Selenium as a Biologically and Environmentally Significant Analyte—A Short Review

Molecules ◽  
2021 ◽  
Vol 26 (6) ◽  
pp. 1768
Author(s):  
Miroslav Rievaj ◽  
Eva Culková ◽  
Damiána Šandorová ◽  
Zuzana Lukáčová-Chomisteková ◽  
Renata Bellová ◽  
...  
Keyword(s):  
Oxidative Stress ◽  
Essential Element ◽  
Analytical Techniques ◽  
High Sensitivity ◽  
Stripping Voltammetry ◽  
Short Review ◽  
Electroanalytical Methods ◽  
High Concentrations ◽  
Speed Of Analysis

This short review deals with the properties and significance of the determination of selenium, which is in trace amounts an essential element for animals and humans, but toxic at high concentrations. It may cause oxidative stress in cells, which leads to the chronic disease called selenosis. Several analytical techniques have been developed for its detection, but electroanalytical methods are advantageous due to simple sample preparation, speed of analysis and high sensitivity of measurements, especially in the case of stripping voltammetry very low detection limits even in picomoles per liter can be reached. A variety of working electrodes based on mercury, carbon, silver, platinum and gold materials were applied to the analysis of selenium in various samples. Only selenium in oxidation state + IV is electroactive therefore the most of voltammetric determinations are devoted to it. However, it is possible to detect also other forms of selenium by indirect electrochemistry approach.

Two-Dimensional Legendre Wavelets for Solving Variable-Order Fractional Nonlinear Advection-Diffusion Equation with Variable Coefficients

2018 ◽  
Vol 19 (7-8) ◽  
pp. 793-802 ◽  
Author(s):  
M. Hosseininia ◽  
M. H. Heydari ◽  
Z. Avazzadeh ◽  
F. M. Maalek Ghaini
Keyword(s):  
Diffusion Equation ◽  
Fractional Derivative ◽  
Main Idea ◽  
Variable Coefficients ◽  
Variable Order ◽  
Two Dimensional ◽  
Legendre Wavelets ◽  
Advection Diffusion Equation ◽  
Advection Diffusion ◽  
Nonlinear Advection

AbstractThis article studies a numerical scheme for solving two-dimensional variable-order time fractional nonlinear advection-diffusion equation with variable coefficients, where the variable-order fractional derivative is in the Caputo type. The main idea is expanding the solution in terms of the 2D Legendre wavelets (2D LWs) where the variable-order time fractional derivative is discretized. We describe the method using the matrix operators and then implement it for solving various types of fractional advection-diffusion equations. The experimental results show the computational efficiency of the new approach.

scholarly journals Void and Moisture Content of Fiber Reinforced Composites

2021 ◽  
Vol 87 (3) ◽  
pp. 78-93
Author(s):  
Nurul Zuhairah Mahmud Zuhudi ◽  
Afiq Faizul Zulkifli ◽  
Muzafar Zulkifli ◽  
Ahmad Naim Ahmad Yahaya ◽  
Nurhayati Mohd Nur ◽  
...  
Keyword(s):  
Moisture Content ◽  
Short Review ◽  
Fiber Reinforced Composites ◽  
Moisture Determination ◽  
Reinforced Composites ◽  
Fiber Reinforced ◽  
Mechanical Performances ◽  
Future Work ◽  
Selection Of

In this paper, a short review on the void and moisture content studies of fiber reinforced composites for both, synthetic and natural based fibers are presented. The review summarized the research papers in which include experimental and theoretical works that related to the void and moisture content studies. In addition to that, this review paper highlighting a few research studies conducted in literature on the effects of the void and moisture on the mechanical performances of the composite. Few common measurement methods used for the void and moisture determination are discussed here. The aims of this short review, mainly to capture the trend ranging from the recent five years back and summarize the various studies and also to compare and conclude the most common method for the determination of the void and moisture content. This paper is mainly providing a baseline in the selection of the methods for the future work of the author’s work with regard to the reduction of the presence of voids and moisture occur during the impregnation process of fiber reinforced composites, especially when using natural-based fiber.

scholarly journals Determination of source term for fractional heat equation on the sphere

2020 ◽  
Vol 24 (Suppl. 1) ◽  
pp. 361-370
Author(s):  
Nguyen Phuong ◽  
Tran Binh ◽  
Nguyen Luc ◽  
Nguyen Can
Keyword(s):  
Diffusion Equation ◽  
Heat Equation ◽  
Exact Solutions ◽  
Source Term ◽  
Fractional Diffusion ◽  
Inverse Source Problem ◽  
Fractional Heat Equation ◽  
Ill Posed ◽  
Time Fractional Diffusion Equation

In this work, we study a truncation method to solve a time fractional diffusion equation on the sphere of an inverse source problem which is ill-posed in the sense of Hadamard. Through some priori assumption, we present the error estimates between the regularized and exact solutions.

The 3D graph approach for breakdown voltage calculation in BaTiO3 ceramics

2021 ◽  
pp. 2150103
Author(s):  
Vojislav V. Mitic ◽  
Branislav Randjelovic ◽  
Ivana Ilic ◽  
Srdjan Ribar ◽  
An-Lu Chun ◽  
...  
Keyword(s):  
Graph Theory ◽  
Crystal Structures ◽  
Breakdown Voltage ◽  
Main Idea ◽  
Experimental Results ◽  
Grain Structure ◽  
Mathematical Approach ◽  
Electronic Parameters ◽  
Mathematical Graph

After pioneering attempts for the introduction of graph theory in the field of ceramics and microstructures, where 1D and 2D graphs were used, in this paper we applied 3D graphs for the breakdown voltage calculation in BaTiO3 sample with some predefined constraints. We have described the relations between grains in the sample and established a mathematical approach for the calculation of breakdown voltage using experimental results. As a result, we introduced mapping between the property of sample and grain structure, then between the grain structure and mathematical graph, using various crystal structures. The main idea was to apply 3D graph theory for the distribution of electronic parameters between the neighboring grains. With this study, we successfully confirmed the possibilities for applications of graphs as a tool for the determination of properties even at the intergranular level.

Determination of Relative Damping at Various Prestresses

1960 ◽  
Vol 33 (2) ◽  
pp. 282-301
Author(s):  
Th Kempermann ◽  
R. Clamroth
Keyword(s):  
Energy Loss ◽  
Phase Angle ◽  
Loss Factor ◽  
Short Review ◽  
The Other ◽  
Simple Function ◽  
History Of ◽  
Tan Δ ◽  
Special Case

Abstract After a short review of the history of the development of the concept of damping, the definitions—one in words, the other in the form of an equation—given in DIN 53513 are discussed, and their usefulness for measurements at various values of prestress is investigated. It is evident that the mathematical definition given in the Standard applies only in the special case when prestress and alternating stress are equal. For the complete range of prestress, the phase angle δ or some simple function of δ, such as the loss factor, tan δ, should be measured. If it is desired not to relinquish the percentage statement of the energy loss, then a new definition for the relative damping is proposed which is independent of the prestress, just as is tan δ. The dependence upon the prestress of the damping values under discussion is demonstrated in an experimental section, for various types of elastomers.

scholarly journals ANALYTICAL DETERMINATION OF INITIAL CONDITIONS LEADING TO FIRING IN NERVE FIBERS

2007 ◽  
Vol 17 (10) ◽  
pp. 3697-3701
Author(s):  
SABIR JACQUIR ◽  
STEPHANE BINCZAK ◽  
JEAN-MARIE BILBAULT
Keyword(s):  
Initial Conditions ◽  
Travelling Waves ◽  
Stationary Wave ◽  
Nerve Fibers ◽  
Analytical Determination ◽  
Action Potential Firing ◽  
Perturbative Method ◽  
Potential Firing ◽  
The Stability

An analytical solution characterizing initial conditions leading to action potential firing in smooth nerve fibers is determined, using the bistable equation. In the first place, we present a nontrivial stationary solution wave, then, using the perturbative method, we analyze the stability of this stationary wave. We show that it corresponds to a frontier between the initiation of the travelling waves and a decay to the resting state. Eventually, this analytical approach is extended to FitzHugh–Nagumo model.

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