scholarly journals The Electromagnetic Shielding of Optoelectronic Devices by Mesh Structures

2021 ◽  
Vol 11 (21) ◽  
pp. 9841
Author(s):  
Mikhal K. Khodzitsky ◽  
Vladimir V. Bassarab ◽  
Alexey A. Shakhmin ◽  
Valentin S. Sokolov ◽  
Grigory I. Kropotov
Keyword(s):  
Optoelectronic Devices ◽  
Theoretical Models ◽  
Video Camera ◽  
Calculation Model ◽  
Transmission Spectra ◽  
Frequency Range ◽  
Mesh Structure ◽  
Shielding Properties ◽  
The One ◽  
Mesh Structures

In this work, the shielding properties of mesh structures with various cell sizes on a K108 glass substrate are studied. The transmission spectra of the samples were obtained in a frequency range from 1 GHz to 1620 THz. A comparison of the experimental transmission spectra with those obtained using several theoretical models, and a numerical calculation were carried out. The most optimal theoretical model used to describe the shielding properties of a mesh structure in the frequency range upper-bounded by a resonant frequency is the one-mode calculation model. Anti-reflection coatings were used to increase the transmission coefficient of the structures in the visible and near-IR spectral ranges. These mesh structures can be used to shield optoelectronic devices such as a video camera or a laser rangefinder from microwaves.

КОНСТРУКТИВНО-ТЕХНОЛОГІЧНІ ОСОБЛИВОСТІ ХВОСТО-ВИХ БАЛОК СІТЧАСТОГО ТИПУ З ПОЛІМЕРНИХ КОМПО-ЗИЦІЙНИХ МАТЕРІАЛІВ ВЕРТОЛЬОТІВ ТРАНСПОРТНОЇ КАТЕГОРІЇ

2020 ◽  
pp. 15-30
Author(s):  
А. Г. Гребеников ◽  
И. В. Малков ◽  
В. А. Урбанович ◽  
Н. И. Москаленко ◽  
Д. С. Колодийчик
Keyword(s):  
Finite Element ◽  
Strain State ◽  
Layer Structure ◽  
Metal Structure ◽  
Element Model ◽  
Stress Strain ◽  
Element Analysis ◽  
Mesh Structure ◽  
Stress Strain State ◽  
Mesh Structures

The analysis of the design and technological features of the tail boom (ТB) of a helicopter made of polymer composite materials (PCM) is carried out.Three structural and technological concepts are distinguished - semi-monocoque (reinforced metal structure), monocoque (three-layer structure) and mesh-type structure. The high weight and economic efficiency of mesh structures is shown, which allows them to be used in aerospace engineering. The physicomechanical characteristics of the network structures are estimated and their uniqueness is shown. The use of mesh structures can reduce the weight of the product by a factor of two or more.The stress-strain state (SSS) of the proposed tail boom design is determined. The analysis of methods for calculating the characteristics of the total SSS of conical mesh shells is carried out. The design of the tail boom is presented, the design diagram of the tail boom of the transport category rotorcraft is developed. A finite element model was created using the Siemens NX 7.5 system. The calculation of the stress-strain state (SSS) of the HC of the helicopter was carried out on the basis of the developed structural scheme using the Advanced Simulation module of the Siemens NX 7.5 system. The main zones of probable fatigue failure of tail booms are determined. Finite Element Analysis (FEA) provides a theoretical basis for design decisions.Shown is the effect of the type of technological process selected for the production of the tail boom on the strength of the HB structure. The stability of the characteristics of the PCM tail boom largely depends on the extent to which its design is suitable for the use of mechanized and automated production processes.A method for the manufacture of a helicopter tail boom from PCM by the automated winding method is proposed. A variant of computer modeling of the tail boom of a mesh structure made of PCM is shown.The automated winding technology can be recommended for implementation in the design of the composite tail boom of the Mi-2 and Mi-8 helicopters.

A Relativistic Newtonian Mechanics Predicts with Precision the Results of Recent Neutrino-Velocity Experiments

2014 ◽  
Vol 6 (1) ◽  
pp. 1032-1035 ◽  
Author(s):  
Ramzi Suleiman
Keyword(s):  
Null Hypothesis ◽  
Experimental Studies ◽  
Theoretical Models ◽  
Newtonian Mechanics ◽  
Speed Of Light ◽  
Symmetry Principle ◽  
Proposed Model ◽  
Significant Difference ◽  
The One ◽  
Complete Collapse

The research on quasi-luminal neutrinos has sparked several experimental studies for testing the "speed of light limit" hypothesis. Until today, the overall evidence favors the "null" hypothesis, stating that there is no significant difference between the observed velocities of light and neutrinos. Despite numerous theoretical models proposed to explain the neutrinos behavior, no attempt has been undertaken to predict the experimentally produced results. This paper presents a simple novel extension of Newton's mechanics to the domain of relativistic velocities. For a typical neutrino-velocity experiment, the proposed model is utilized to derive a general expression for . Comparison of the model's prediction with results of six neutrino-velocity experiments, conducted by five collaborations, reveals that the model predicts all the reported results with striking accuracy. Because in the proposed model, the direction of the neutrino flight matters, the model's impressive success in accounting for all the tested data, indicates a complete collapse of the Lorentz symmetry principle in situation involving quasi-luminal particles, moving in two opposite directions. This conclusion is support by previous findings, showing that an identical Sagnac effect to the one documented for radial motion, occurs also in linear motion.

The Problem of the Typology of Rationality in Muslim Culture

2019 ◽  
Vol 62 (6) ◽  
pp. 88-99
Author(s):  
Andrey A. Lukashev
Keyword(s):  
Modern Philosophy ◽  
Theoretical Basis ◽  
Theoretical Models ◽  
The Other ◽  
Common Denominator ◽  
Islamic Culture ◽  
The Common ◽  
Per Se ◽  
The One ◽  
Muslim Culture

The typology of rationality is one of major issues of modern philosophy. In an attempt to provide a typology to Oriental materials, a researcher faces additional problems. The diversity of the Orient as such poses a major challenge. When we say “Oriental,” we mean several cultures for which we cannot find a common denominator. The concept of “Orient” involves Arabic, Indian, Chinese, Turkish and other cultures, and the only thing they share is that they are “non-Western.” Moreover, even if we focus just on Islamic culture and look into rationality in this context, we have to deal with a conglomerate of various trends, which does not let us define, with full confidence, a common theoretical basis and treat them as a unity. Nevertheless, we have to go on trying to find common directions in thought development, so as to draw conclusions about types of rationality possible in Islamic culture. A basis for such a typology of rationality in the context of the Islamic world was recently suggested in A.V. Smirnov’s logic of sense theory. However, actual empiric material cannot always fit theoretical models, and the cases that do not fit the common scheme are interesting per se. On the one hand, examination of such cases gives an opportunity to specify certain provisions of the theory and, on the other hand, to define the limits of its applicability.

scholarly journals The Concept of Accuracy Analysis of the Vertical Displacements Gained from the Hydrostatic Levelling Systems’ Measurements

Sensors ◽  
2021 ◽  
Vol 21 (14) ◽  
pp. 4842
Author(s):  
Waldemar Kamiński
Keyword(s):  
Accuracy Assessment ◽  
Theoretical Models ◽  
Vertical Displacement ◽  
Serial Connection ◽  
Vertical Displacements ◽  
Comprehensive Determination ◽  
The One ◽  
The Individual ◽  
Reference Sensor

Nowadays, hydrostatic levelling is a widely used method for the vertical displacements’ determinations of objects such as bridges, viaducts, wharfs, tunnels, high buildings, historical buildings, special engineering objects (e.g., synchrotron), sports and entertainment halls. The measurements’ sensors implemented in the hydrostatic levelling systems (HLSs) consist of the reference sensor (RS) and sensors located on the controlled points (CPs). The reference sensor is the one that is placed at the point that (in theoretical assumptions) is not a subject to vertical displacements and the displacements of controlled points are determined according to its height. The hydrostatic levelling rule comes from the Bernoulli’s law. While using the Bernoulli’s principle in hydrostatic levelling, the following components have to be taken into account: atmospheric pressure, force of gravity, density of liquid used in sensors places at CPs. The parameters mentioned above are determined with some mean errors that influence on the accuracy assessment of vertical displacements. In the subject’s literature, there are some works describing the individual accuracy analyses of the components mentioned above. In this paper, the author proposes the concept of comprehensive determination of mean error of vertical displacement (of each CPs), calculated from the mean errors’ values of components dedicated for specific HLS. The formulas of covariances’ matrix were derived and they enable to make the accuracy assessment of the calculations’ results. The author also presented the subject of modelling of vertical displacements’ gained values. The dependences, enabling to conduct the statistic tests of received model’s parameters, were implemented. The conducted tests make it possible to verify the correctness of used theoretical models of the examined object treated as the rigid body. The practical analyses were conducted for two simulated variants of sensors’ connections in HLS. Variant no. I is the sensors’ serial connection. Variant no. II relies on the connection of each CPs with the reference sensor. The calculations’ results show that more detailed value estimations of the vertical displacements can be obtained using variant no. II.

Effect of Double Defects on Transmission Spectra of One-Dimensional Photonic Crystals

2010 ◽  
Vol 663-665 ◽  
pp. 725-728 ◽  
Author(s):  
Yuan Ming Huang ◽  
Qing Lan Ma ◽  
Bao Gai Zhai ◽  
Yun Gao Cai
Keyword(s):  
Photonic Crystals ◽  
Band Gap ◽  
Theoretical Calculations ◽  
Stop Band ◽  
Band Gaps ◽  
Characteristic Matrix ◽  
Frequency Range ◽  
Defect Band ◽  
One Dimensional ◽  
The One

Considered the model of the one-dimensional photonic crystals (1-D PCs) with double defects, the refractive indexes (n2’, n3’ and n2’’, n3’’) of the double defects were 2.0, 4.0 and 4.0, 2.0 respectively. With parameter n2=1.5, n3=2.5, by theoretical calculations with characteristic matrix method, the results shown that for a certain number (14 was taken) of layers of the 1-D PCs, when the double defects abutted, there was a defect band gap in the stop band gap, while when the double defects separated, there occurred two defect band gaps in the stop band gap; besides, with the separation of the two defects, the transmittance of the double defect band gaps decreased gradually. In addition, in this progress, the frequency range of the stop band gap has a little increase from 0.092 to 0.095.

scholarly journals Small-Scale Spectrum of a Scalar Field in Water: The Batchelor and Kraichnan Models

2011 ◽  
Vol 41 (11) ◽  
pp. 2155-2167 ◽  
Author(s):  
Xavier Sanchez ◽  
Elena Roget ◽  
Jesus Planella ◽  
Francesc Forcat
Keyword(s):  
Scalar Field ◽  
Thermal Gradient ◽  
Theoretical Models ◽  
Measured Data ◽  
Small Scale ◽  
Temperature Profiles ◽  
One Dimensional ◽  
Kraichnan Model ◽  
The One ◽  
Rate Of Dissipation

Abstract The theoretical models of Batchelor and Kraichnan, which account for the smallest scales of a scalar field passively advected by a turbulent fluid (Prandtl > 1), have been validated using shear and temperature profiles measured with a microstructure profiler in a lake. The value of the rate of dissipation of turbulent kinetic energy ɛ has been computed by fitting the shear spectra to the Panchev and Kesich theoretical model and the one-dimensional spectra of the temperature gradient, once ɛ is known, to the Batchelor and Kraichnan models and from it determining the value of the turbulent parameter q. The goodness of the fit between the spectra corresponding to these models and the measured data shows a very clear dependence on the degree of isotropy, which is estimated by the Cox number. The Kraichnan model adjusts better to the measured data than the Batchelor model, and the values of the turbulent parameter that better fit the experimental data are qB = 4.4 ± 0.8 and qK = 7.9 ± 2.5 for Batchelor and Kraichnan, respectively, when Cox ≥ 50. Once the turbulent parameter is fixed, a comparison of the value of ɛ determined from fitting the thermal gradient spectra to the value obtained after fitting the shear spectra shows that the Kraichnan model gives a very good estimate of the dissipation, which the Batchelor model underestimates.

scholarly journals Grid convergence study of a cyclone separator using different mesh structures

2017 ◽  
Vol 23 (3) ◽  
pp. 311-320 ◽  
Author(s):  
R.A.F. Oliveira ◽  
G.H. Justi ◽  
G.C. Lopes
Keyword(s):  
Pressure Drop ◽  
Collection Efficiency ◽  
Fluid Dynamic ◽  
Two Phase ◽  
Mesh Structure ◽  
Pressure Drops ◽  
Regular Elements ◽  
Grid Convergence ◽  
Grid Convergence Index ◽  
Mesh Structures

In a cyclone design, pressure drop and collection efficiency are two important performance parameters to estimate its implementation viability. The optimum design provides higher efficiencies and lower pressure drops. In this paper, a grid independence study was performed to determine the most appropriate mesh to simulate the two-phase flow in a Stairmand cyclone. Computational fluid dynamic (CFD) tools were used to simulate the flow in an Eulerian-Lagrangian approach. Two different mesh structure, one with wall-refinement and the other with regular elements, and several mesh sizes were tested. The grid convergence index (GCI) method was applied to evaluate the result independence. The CFD model results were compared with empirical correlations from bibliography, showing good agreement. The wall-refined mesh with 287 thousand elements obtained errors of 9.8% for collection efficiency and 14.2% for pressure drop, while the same mesh, with regular elements, obtained errors of 8.7% for collection efficiency and 0.01% for pressure drop.

scholarly journals PAKARTOJIMAS IR NIHILIZMAS

Problemos ◽  
2013 ◽  
Vol 84 ◽  
pp. 46-59
Author(s):  
Rita Šerpytytė
Keyword(s):  
Theoretical Models ◽  
The Other ◽  
Philosophical Tradition ◽  
Western Tradition ◽  
Other Hand ◽  
Text Fragment ◽  
Western Philosophical Tradition ◽  
Universal Structure ◽  
The One

Straipsnio tikslas yra atskleisti Vakarų filosofijos tradicijoje savitai įsitvirtinusios patyrimo struktūros, įvardijamos pakartojimu, nihilistinę prasmę. Šioje hermeneutinėje analizėje, viena vertus, re­miamasi tam tikra nihilizmo samprata, numatančia du nihilizmo teorinius modelius – nihilizmą, parem­tą Überwindung teorija, ir nihilizmą, paremtą différance idėja. Kita vertus, remiamasi tam tikru („onto-teologiniu“) pretekstu Vakarų mąstymo tradicijoje atpažįstant pakartojimo struktūrą – Pauliaus Laiško efeziečiams Ef. I, 10 teksto fragmentu, laikomu paradigmine pakartojimo struktūros išsklaida. Herme­neutinė analizė projektuojama į Kierkegaardo ir Agambeno filosofiją, atskirus jų mąstyme atpažįstamus pakartojimo invariantus atskleidžiant kaip minėto Pauliaus Laiško fragmento eksplozijos atvejus. Ke­liamas klausimas, kas yra pakartojimas, kur slypi jo negatyvumas ir kaip pasirodo jo nihilistinė prasmė? Kaip šioje negatyvumo ir nihilizmo atskleistyje „tarpininkauja“ différance? Straipsnyje parodoma, jog skirtis kaip neigimo judesys, atstovaujantis nihilistinei logikai, gali būti traktuojamas ir vien formaliai, ir realiai. Skirties kaip realaus neigimo traktavimas Kierkegaardo ir Agambeno mąstyme atitinka pačios patirties struktūros – pakartojimo – ontologinį (tikrovišką) įšaknytumą.Pagrindiniai žodžiai: pakartojimas, nihilizmas, différance, negatyvumas, laikasPakartojimas ir nihilizmasRita Šerpytytė   AbstractThe purpose of this article is to reveal the nihilistic sense of an experiential structure, which has been distinctively rooted in Western philosophical tradition. On the one hand, this hermeneutical analysis will be based on a certain conception of nihilism presupposing two theoretical models of nihilism – nihilism, which refers to the theory of Überwindung, and nihilism associated with the idea of différance. On the other hand, it builds upon a certain (the so-called “onto-theological”) pretext, which might be used for recognition of the structure of repetition in Western tradition of thinking, – i.e. the fragment of a text from St. Paul’s Letter to the Ephesians Eph. I, 10 – the paradigmatic passage proposing this universal structure of repetition. Focused both on philosophy of Kierkegaard and Agamben, hermeneutical analysis will aim to disclose the separate invariants of such repetition as cases of explosion of the mentioned text fragment. The question is raised – what is repetition? Where does its negativity lie? How does its nihilistic sense appear? How does the différance mediate in this process of revealing of negativity and nihilism? The article argues that difference, as a motion of negation representing nihilistic logic, can be treated both in merely formal and in a realistic way. The treating of différance as real denying in Kierkegaard’s and Agamben’s thinking corresponds to the ontological rootedness of the very structure of experience – repetition.Keywords: repetition, nihilism, différance, negativity, time

scholarly journals Understanding jökulhlaups: From tale to theory

2010 ◽  
Vol 56 (200) ◽  
pp. 1002-1010 ◽  
Author(s):  
Helgi Björnsson
Keyword(s):  
Theoretical Models ◽  
Frictional Heat ◽  
Drainage Systems ◽  
Linear Rise ◽  
Observed Behaviour ◽  
Flow Through ◽  
Discharge Patterns ◽  
The One ◽  
Different Sources ◽  
Source Geometry

AbstractThe study of jökulhlaups has advanced from describing them qualitatively to measuring systematically on site their discharge curves and source geometry, as well as investigating conditions when particular floods were initiated. In the early days of this science, hypotheses were formulated which attempted to explain the processes responsible for unstable flood growth. The general theory of time-dependent turbulent water flow through intraglacial conduits marked a breakthrough in understanding jökulhlaup hydraulics and has since remained a classical foundation for jökulhlaup studies. This theory described flood evolution in terms of water input into the upper end of a tunnel leading from a reservoir, taking account of sensible stored lake heat and geometry. Such a tunnel expands by positive feedback, since its ice walls melt through frictional heat produced by the flowing water. While this model successfully described jökulhlaups in which the discharge hydrograph increases more or less exponentially over time, other floods were observed which are in stark contrast. In them, pressurized floodwater propagates in a turbulent subglacial water sheet which opens and expands a system of conduits, with an extremely rapid linear rise in discharge. The rushing water enlarges its subglacial pathway not only by melting the ice around it but also by lifting, deforming and fracturing it. Subsequent drainage is nourished by two different sources, with conduit growth being controlled not only by water input at the upper end of the flood path but also by further water joining in, all the way to the edge of the glacier. Moreover, the trigger for releasing meltwater from glacial lakes has been seen to be either of two conduit opening mechanisms, which also determine whether a turbulent subglacial water sheet will result or not. On the one hand, drainage may begin by expanding already existing conduits, in which case the pressure remains lower than that of the ice overburden at the dam and the conduits grow slowly. On the other hand, lake levels may rise until flotation of the ice dam, abruptly opening a sufficient gap for water to propagate as a sheet flow. In order to explain which of these two initiation mechanisms will act, further studies are required into the structure of hydrological drainage systems under ice dams and into their linkage with these two mechanisms. Although current theoretical models of jökulhlaups drainage have managed to reproduce the observed discharge patterns, inconsistencies with the observed behaviour of subglacial drainage systems along the flood path demand further exploration of the actual hydraulic and glaciodynamic processes of jökulhlaups.

Karl Polanyi’s Anthropological Theory of Economy

Naukratis ◽  
2000 ◽  
Author(s):  
Astrid Moller
Keyword(s):  
Economic History ◽  
Industrial Revolution ◽  
Theoretical Models ◽  
Classical Antiquity ◽  
Economic Organization ◽  
Ideal Types ◽  
Use Of Resources ◽  
History Of ◽  
The Subject ◽  
The One

In accordance with the hermeneutical principles laid down in the introduction, this chapter will be devoted to an account of the theoretical models underlying the analysis and interpretation of the source material. Karl Polanyi’s empirical observations resulted in a series of ideal-types such as can be employed for the evaluation of the evidence from Naukratis in the following chapters. Polanyi’s works do not form one single, complete theory of economy; rather, they should be seen—as Sally Humphreys has put it so aptly—as sketches of areas within largely unexplored territory. It is of course true that George Dalton went to great lengths to develop Polanyi’s ideas further; the fact nevertheless remains that they continue to be far from accepted as paradigms for all further research in the field of economic anthropology or economic history. Indeed, such continuations of Polanyi’s approach have served only to limit unduly the openness that is the very advantage of his ideal-types. It is for this reason that one should return to Polanyi himself and employ his original ideas. His work has been taken up by only a few within the realm of the economic history of classical antiquity, something due partly to his own—problematic—statements on the subject of Greek history, and partly to lack of interest shown for anthropological approaches within ancient history. Polanyi disagreed with the view that markets were the ubiquitous form of economic organization—an attitude regarding the notion of the market as essential to the description of every economy—and also with the belief that it is the economic organization of any given society which determines its social, political, and cultural structures. For his part, Polanyi contended that an economy organized around the market first came into being with the Industrial Revolution, and that it was not until then that the two root meanings of the word ‘economic’—on the one hand, in the sense of provision with goods; on the other, in the sense of a thrifty use of resources, as in the words ‘economical’ and ‘economizing’—merged.

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