scholarly journals Квантовое трение и трение ван-дер-Ваальса в конфигурациях частица-пластина и пластина-пластина: нелокальные эффекты

2020 ◽  
Vol 62 (8) ◽  
pp. 1312
Author(s):  
Г.В. Дедков ◽  
А.А. Кясов
Keyword(s):  
Relative Motion ◽  
Constant Velocity ◽  
Specular Reflection ◽  
Au Nanoparticle ◽  
Friction Forces ◽  
Nonrelativistic Approximation ◽  
Dissipative Forces ◽  
Reflection Model ◽  
Gold Plate ◽  
Analytical Expressions

Within the nonrelativistic approximation of fluctuation electrodynamics, using the specular reflection model and nonlocal permittivity of the metal, we have obtained simple analytical expressions for friction forces in particle – plate and plate – plate systems at relative motion of bodies at a constant velocity. It has been shown that at distances of about 1–10 nm for an Au nanoparticle (or gold plate) moving near another (identical) plate at rest, dissipative forces prove to be 2–4 orders of magnitude higher than when using the local Drude dielectric function.

Design of Midcourse Trajectory for Tactical Ballistic Missile Intercept on the Basis of Zero Effort Miss

2013 ◽  
Vol 397-400 ◽  
pp. 536-545
Author(s):  
Luo Gang Li ◽  
Wu Xing Jing ◽  
Chang Sheng Gao
Keyword(s):  
Relative Motion ◽  
Design Method ◽  
Ballistic Missile ◽  
Prediction Methods ◽  
Trajectory Design ◽  
Motion State ◽  
Simulating Calculation ◽  
Analytical Expressions ◽  
Maximal Principle ◽  
Computing Method

Since the maneuverability of the tactical ballistic missile, the midcourse trajectory of interception missile needs design online. Firstly, this paper reasonably simplifies the models and explores the analytical expressions of their relative motion state to obtain a kind of rapid and high-precision computing method of zero effort miss. Secondly, it applies constant thrust for the interception missile, burns out shut-down solid engine, reflects on the index requirement of overloaded interception missile, and designs midcourse trajectory of the interception missile with Pontryagin maximal principle, in accordance with the analytical expressions of zero effort miss. Finally, with the simulating calculation, the prediction methods of zero effort miss and trajectory design method provided by this paper are applied to a situation simulation which is close to the fact as much as possible so as to verify the applicability in the interception of tactical ballistic missile.

scholarly journals The influence of vortices upon the resitance experienced by solids moving through a liquid

1928 ◽  
Vol 119 (781) ◽  
pp. 146-156 ◽  
Keyword(s):  
Perfect Fluid ◽  
Relative Motion ◽  
Constant Velocity ◽  
Fluid Motion ◽  
Resultant Force ◽  
The Other ◽  
Two Dimensional ◽  
Perfect Fluids ◽  
Potential Problems ◽  
The Moment

(1) It is not so long ago that it was generally believed that the "classical" hydrodynamics, as dealing with perfect fluids, was, by reason of the very limitations implied in the term "perfect," incapable of explaining many of the observed facts of fluid motion. The paradox of d'Alembert, that a solid moving through a liquid with constant velocity experienced no resultant force, was in direct contradiction with the observed facts, and, among other things, made the lift on an aeroplane wing as difficult to explain as the drag. The work of Lanchester and Prandtl, however, showed that lift could be explained if there was "circulation" round the aerofoil. Of course, in a truly perfect fluid, this circulation could not be produced—it does need viscosity to originate it—but once produced, the lift follows from the theory appropriate to perfect fluids. It has thus been found possible to explain and calculate lift by means of the classical theory, viscosity only playing a significant part in the close neighbourhood ("grenzchicht") of the solid. It is proposed to show, in the present paper, how the presence of vortices in the fluid may cause a force to act on the solid, with a component in the line of motion, and so, at least partially, explain drag. It has long been realised that a body moving through a fluid sets up a train of eddies. The formation of these needs a supply of energy, ultimately dissipated by viscosity, which qualitatively explains the resistance experienced by the solid. It will be shown that the effect of these eddies is not confined to the moment of their birth, but that, so long as they exist, the resultant of the pressure on the solid does not vanish. This idea is not absolutely new; it appears in a recent paper by W. Müller. Müller uses some results due to M. Lagally, who calculates the resultant force on an immersed solid for a general fluid motion. The result, as far as it concerns vortices, contains their velocities relative to the solid. Despite this, the term — ½ ρq 2 only was used in the pressure equation, although the other term, ρ ∂Φ / ∂t , must exist on account of the motion. (There is, by Lagally's formulæ, no force without relative motion.) The analysis in the present paper was undertaken partly to supply this omission and partly to check the result of some work upon two-dimensional potential problems in general that it is hoped to publish shortly.

scholarly journals CONSTRAINING THE PREFERRED-FRAME α1, α2 PARAMETERS FROM SOLAR SYSTEM PLANETARY PRECESSIONS

2014 ◽  
Vol 23 (01) ◽  
pp. 1450006 ◽  
Author(s):  
L. IORIO
Keyword(s):  
Binary System ◽  
Solar System ◽  
Relative Motion ◽  
A Priori ◽  
The Other ◽  
Preferred Frame ◽  
General Relativistic ◽  
Ppn Parameters ◽  
Invariable Plane ◽  
Analytical Expressions

Analytical expressions for the orbital precessions affecting the relative motion of the components of a local binary system induced by Lorentz-violating Preferred Frame Effects (PFE) are explicitly computed in terms of the Parametrized Post-Newtonian (PPN) parameters α1, α2. Preliminary constraints on α1, α2 are inferred from the latest determinations of the observationally admitted ranges [Formula: see text] for any anomalous Solar System planetary perihelion precessions. Other bounds existing in the literature are critically reviewed, with particular emphasis on the constraint [Formula: see text] based on an interpretation of the current close alignment of the Sun's equator with the invariable plane of the Solar System in terms of the action of a α2-induced torque throughout the entire Solar System's existence. Taken individually, the supplementary precessions [Formula: see text] of Earth and Mercury, recently determined with the INPOP10a ephemerides without modeling PFE, yield α1 = (0.8±4) × 10-6 and α2 = (4±6) × 10-6, respectively. A linear combination of the supplementary perihelion precessions of all the inner planets of the Solar System, able to remove the a priori bias of unmodeled/mismodeled standard effects such as the general relativistic Lense–Thirring precessions and the classical rates due to the Sun's oblateness J2, allows to infer α1 = (-1 ± 6) × 10-6, α2 = (-0.9 ± 3.5) × 10-5. Such figures are obtained by assuming that the ranges of values for the anomalous perihelion precessions are entirely due to the unmodeled effects of α1 and α2. Our bounds should be improved in the near-mid future with the MESSENGER and, especially, BepiColombo spacecrafts. Nonetheless, it is worthwhile noticing that our constraints are close to those predicted for BepiColombo in two independent studies. In further dedicated planetary analyses, PFE may be explicitly modeled to estimate α1, α2 simultaneously with the other PPN parameters as well.

Analysis of Motion of the Impact-Dry-Friction Pair of Bodies and its Application to the Investigation of the Impact Dampers Dynamics

1999 ◽  
Author(s):  
František Peterka
Keyword(s):  
Analytical Solution ◽  
Numerical Simulations ◽  
Mechanical System ◽  
Relative Motion ◽  
Dry Friction ◽  
Friction Pair ◽  
Strong Nonlinearity ◽  
Friction Forces ◽  
The Impact ◽  
Analysis Of Motion

Abstract The motion with impacts and dry friction forces appears in some mechanical systems as mechanisms with clearances, (e.g., in gearings, pins, slots, guides, valve gears etc.), impact dampers, relays, forming and mailing machines, power pics etc. Such mechanisms include one or more pairs of impacting bodies, which introduce the strong nonlinearity into the system motion. The motion of the general pair of bodies with the both-sides impacts and dry friction forces is assumed (Fig.1). It can be the part of a more complex chain of masses in the mechanical system. Dead zones in the relative motion of bodies can be caused by assumed nonlinearities. The mathematical conditions controlling the numerical simulations or analytical solution of the motion are introduced. The application of this method is explained by the study of the influence of dry friction force on amplitude-frequency characteristics of four types of dynamical and impact dampers with optimised parameters.

Experimental Study of Friction in a Pneumatic Actuator at Constant Velocity

1993 ◽  
Vol 115 (3) ◽  
pp. 575-577 ◽  
Author(s):  
Lee E. Schroeder ◽  
Rajendra Singh
Keyword(s):  
Experimental Study ◽  
Experimental Method ◽  
Friction Force ◽  
Constant Velocity ◽  
Sliding Friction ◽  
Pneumatic Actuator ◽  
Friction Forces ◽  
Friction Models ◽  
Semi Empirical ◽  
Force Data

This paper describes an experimental method of determining sliding friction forces in a pneumatic actuator. Several empirical and semi-empirical friction models are evaluated using measured friction force data. A repeatability study is also performed to qualitatively assess friction randomness and a change in friction regimes.

Development of a System to Measure the Optical Properties of Facial Skin using a 3D Camera and Projector

2021 ◽  
Author(s):  
Kumiko Kikuchi ◽  
Shoji Tominaga ◽  
Jon Y. Hardeberg
Keyword(s):  
Optical Properties ◽  
Diffuse Reflection ◽  
Specular Reflection ◽  
Three Dimensional ◽  
Depth Image ◽  
Facial Skin ◽  
Subsurface Scattering ◽  
Surface Reflection ◽  
Reflection Model ◽  
Reflection Component

We have developed a system to measure both the optical properties of facial skin and the three-dimensional shape of the face. To measure the three-dimensional facial shape, our system uses a light-field camera to provide a focused image and a depth image simultaneously. The light source uses a projector that produces a high-frequency binary illumination pattern to separate the subsurface scattering and surface reflections from the facial skin. Using a dichromatic reflection model, the surface reflection image of the skin can be separated further into a specular reflection component and a diffuse reflection component. Verification using physically controlled objects showed that the separation of the optical properties by the system correlated with the subsurface scattering, specular reflection, or diffuse reflection characteristics of each object. The method presented here opens new possibilities in cosmetology and skin pharmacology for measurement of the skin’s gloss and absorption kinetics and the pharmacodynamics of various external agents.

scholarly journals Sliding-vibrating responses of elastic structures

1988 ◽  
Vol 21 (3) ◽  
pp. 190-197
Author(s):  
Yu-An Fu
Keyword(s):  
Rigid Body ◽  
Harmonic Excitation ◽  
Body Motion ◽  
Shake Table ◽  
Reciprocating Motion ◽  
Friction Forces ◽  
Single Degree Of Freedom ◽  
Single Degree ◽  
Analytical Expressions ◽  
Vibrating Response

By using simulated friction forces, analytical expressions were derived from the sliding-vibrating response of a single degree of freedom system under harmonic excitation or the "disadvantageous period reciprocating motion", taking the mass of the sliding base into consideration. Some of the general laws were studied and some new characteristics determined which had previously been ignored by assuming rigid body motion. The analysis methods adopted in this paper have been confirmed in comparison with the results of model tests on a shake table.

scholarly journals PERSPECTIVE METHODS OF DIVERGENCE OF VESSELS AND ANALYSIS OF THEIR EFFICIENCY

2020 ◽  
Vol 1 (22) ◽  
pp. 54-63
Author(s):  
Yu. M. Khussein ◽  
◽  
O. V. Yanchetskyy ◽  
Keyword(s):  
Decision Making ◽  
Collision Avoidance ◽  
Relative Motion ◽  
Relative Position ◽  
Preliminary Analysis ◽  
Decision Making Process ◽  
Rule Application ◽  
The Moment ◽  
Analytical Expressions

The article is devoted to the analysis of the most perspective and effective locally-independent methods of divergence of vessels for forming of the system of the automatic warning of collisions, providing safety of perspective autonomous vessels. Development of method of estimation of efficiency of methods of divergence of vessels, which characterizes the degree of safety of completion of process of divergence of vessels, is offered, since the moment of discovery of situation of dangerous rapprochement. The stages of process of decision-making divergence of vessels of necessity are considered at their rapprochement and choice of strategy of divergence. It is shown that a decision-making process contains the following stages: control of environment, including relative position and parameters of relative motion, exposure of situation of rapprochement of vessels, estimation of degree of danger of rapprochement and choice of strategy of divergence. Analytical expressions for formalization of the offered stages of process of decision-making divergence of vessels of necessity are resulted. It is shown that depending on the degree of danger of situation of rapprochement, it is necessary to choose strategy of divergence, coming co-ordination of maneuvers of the drawn together vessels from, foreseen ColReg. Thus character of maneuver of divergence is also determined by the value of situation indignation. As a rule, application of standard maneuver of divergence is foreseen, and in the situation of excessive rapprochement of vessels, in order to avoid the collision it is necessary to use the maneuver of urgent divergence. As the index of efficiency of the analytical collision avoidance systems vessels probability of safe completion of process of divergence, which is work of probabilities of successful finish of stages of process of decision-making on the choice of strategy of divergence, is offered. For the system of the automatic warning of collisions the methods of divergence with one dangerous target are offered by the change of course or speed of ship and with two dangerous targets by the combined maneuver of the repeated change of course of ship. After the preliminary analysis the perspective most effective methods of the mentioned types of maneuvers of divergence were offered. For the operative choice of parameters of maneuver of divergence of ship with a target the regions of impermissible values of parameters of deviation and region of acceptability parameters of deviation and output are offered. For the case of choice of maneuver of divergence of ship by the decline of speed the active or passive braking offers the method of forming of region of impermissible speeds and calculation of its scopes. In the situation of dangerous rapprochement of ship with two targets for the operative choice of parameters of maneuver of divergence of ship in work it is suggested to form the region of acceptability successive courses of deviation.

scholarly journals Резонансное взаимодействие переходного излучения заряженной частицы с периодически модулированным в пространстве анизотропным магнитодиэлектрическим заполнением волновода

2019 ◽  
Vol 127 (9) ◽  
pp. 441
Author(s):  
Э.А. Геворкян
Keyword(s):  
Charged Particle ◽  
Strong Interaction ◽  
Constant Velocity ◽  
Cherenkov Radiation ◽  
Transition Radiation ◽  
Transverse Electric ◽  
Resonant Interaction ◽  
Transverse Magnetic ◽  
Frequency Region ◽  
Analytical Expressions

The peculiarities of the interaction of the transition radiation of a charged particle with periodically modulated in space anisotropic magnetodielectric medium in the waveguide in the frequency region of the strong (resonant) interaction of the radiation with the modulated medium are considered. It is assumed that the charged particle moves with constant velocity perpendicular to the axis of the waveguide. Analytical expressions are obtained for the energy of transition radiation of transverse-electric (TE) and transverse-magnetic (TM) fields in the waveguide in the region of strong interaction with an accuracy of small modulation indexes in the first degree inclusive. Analytical expressions for the frequency and for the width of the frequency region of strong interaction are found. The possibility of the appearance of Cherenkov radiation in the region of strong interaction in the case of a rectangular waveguide is analyzed.

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