Longitudinal Oscillations Research Articles

Ribonucleic acid genome mutations induced by the Casimir effect

In this paper, we investigate the Casimir effect within a virus RNA, particularizing the study to the severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2). Then, we discuss the possibility of occurring damage or mutation in its genome due to the presence of quantum vacuum fluctuations inside and around the RNA ribbon. For this, we consider the geometry and the nontrivial topology of the viral RNA as having a simple helical structure. We initially compute the non-thermal Casimir energy associated to that geometry, considering boundary conditions that constrain the zero point oscillations of a massless scalar field to the cylindrical cavity containing a helix pitch of RNA ribbon. Then we extend the obtained result to the electromagnetic field and, following, we calculate the probability of occurring damage or mutation in RNA by using the normalized inverse exponential distribution, which suppresses very low energies, and consider cutoff (threshold) energies corresponding to UV-A and UV-C rays, surely responsible by mutations. Then, by taking into account UV-A, we arrive at a mutation rate per base per infection cycle, which in the case of the SARS-CoV-2 is non-negligible. We find a maximum value of this mutation rate for an RNA ribbon radius, applying it for SARS-CoV-2, in particular. We also calculate a characteristic longitudinal oscillation frequency for the helix pitch value corresponding to the local minimum of the Casimir energy. Finally, we consider thermal fluctuations of classical and quantum nature and show that the corresponding probability of mutation is completely negligible for that virus. Therefore, we conclude that only the nontrivial topology and the geometric attributes of the RNA molecule contribute to the possible mutations caused by quantum vacuum fluctuations in the viral genome.

Strong coupling between longitudinal and U-shaped localized surface plasmon modes in rectangular grating-shaped gold nanostructures

Strong couplings between localized surface plasmon resonance (LSPR) modes and single quantum emitters have been intensively investigated recently, and meanwhile the coupling between different LSPR modes inside individual metallic nanoparticle is still rarely researched. Herein, the strong coupling is investigated for different LSPR modes inside individual rectangular-grating-shaped gold nanostructure composed of one main-cuboid and two side-attached subcuboids. Original uncoupled LSPR modes are revealed to be longitudinal and U-shaped LSPRs. For the nanostructure with increased main-cuboid length, the dispersion curves of simulated dual-original LSPR scattering wavelengths and dual-coupled LSPR scattering wavelengths show typical strong coupling patterns featuring anti-crossing and large Rabi splitting of 598.1 meV. The strong coupling is considered to be caused by the overlap of longitudinal and U-shaped LSPR oscillation modes in the gold nanostructure. The extracted coupling strength is found in order of 1013 Hz and it increases with the LSPR overlap length. The spatial mode and time evolution of the coupled LSPR modes are also numerically investigated. The simulated results are well comprehended with the classical strong coupling model of oscillators, further confirming the coupling between the longitudinal and the U-shaped LSPRs. The experimental dark-field scattering spectrum shows the existence of U-shaped LSPR mode in the gold nanostructure.

Adjustment of the axial load on the bit when hole deepening by using the screw mechanism

The object of the research is a screw mechanism for adjusting the axial load on the bit during a hole deepening. Mathematical modeling of dynamic processes that occur in the drill string during the hole deepening in deep wells is considered. It is shown that in the process of hole deepening, the longitudinal oscillations are proportional in their intensity to the torsional ones. Obtained boundary conditions for mathematical models of the column with the use of a shock absorber or a screw amplifier. In the course of research, it was found that the screw working mechanism of the axial load creates a relationship between the axial load on the bit and the torque on the screw. This makes it possible to install safety devices that limit the torque of the drive shaft (reciprocating engine, rotor). It is shown that various types of energy supplied to the punch, which are transformed by the punching motor and amplified due to the axial (screw) amplifier installed above the bit, ensure the rotary-progressive movement of the ball bit and increase the drilling performance. It was determined that the obtained dependencies take into account the change in time of the axial load and torque depending on the parameters of the axial amplifier and the geological and technical conditions of drilling and the arrangement of the bottom of the drill string. The research results will be useful to scientists and specialists of the oil and gas industry during the physical modeling of the processes of adjusting the axial load on the bit during a hole deepening by using a screw mechanism.

Dynamic analysis and vibration control for overhead hoist transport

The OHT system is a transport device used for intra- or inter-plant transport in a fab or other factory, the load-bearing part of the goods stored under the trolley generates longitudinal vibration and lateral oscillation due to inertia force When the OHT in the air starts or stops. Firstly, the trolley dynamic model under the action of lateral thrust and longitudinal tensile force need to be established. secondly, the coupling analysis of horizontal oscillation and longitudinal oscillation on the model is carried out. Thirdly, aiming at the lateral swing and longitudinal vibration of the carriage, a double closed-loop vibration control strategy with tension control as inner loop and speed control as outer loop and carry out the simulation analysis of longitudinal vibration control is proposed. In the experiment of the ground trolley, the control strategy is applied. The simulation and experimental results show that the control method can quickly restrain the longitudinal vibration of the trolley bearing plate, reduce the pulling force of the trolley on the lifting steel belt, and avoid the large displacement of the bearing plate in the air.

Stereoscopic observation of simultaneous longitudinal and transverse oscillations in a single filament driven by two-sided-loop jet

ABSTRACT We report the first observations of simultaneous large-amplitude longitudinal and transverse oscillations of a quiescent filament trigged by a two-sided-loop jet formed by the magnetic reconnection between the filament and an emerging loop in the filament channel, recorded by the Solar Dynamics Observatory and the Solar TErrestrial RElations Observatory. The north arm of the jet firstly pushed the filament mass moving northwardly along the magnetic field lines consisting of the coronal cavity, then some elevated filament mass fell back and started to oscillate longitudinally at the bottom of the cavity (i.e. the magnetic dip). The northernmost part of the filament also showed transverse oscillation simultaneously. The amplitude and period of the longitudinal (transverse) oscillation are 12.96 (2.99) Mm and 1.18 (0.33) h, respectively. By using the method of filament seismology, the radius of curvature of the magnetic dip is about 151 Mm, consistent with that obtained by the 3D reconstruction (166 Mm). Using different physical parameters of the observed longitudinal and transverse oscillations, the magnetic field strength of the filament is estimated to be about 23 and 21 Gauss, respectively. By calculating the energy of the moving filament mass, the minimum energy of the jet is estimated to be about $1.96 \times 10^{28} \operatorname{erg}$. We conclude that the newly formed jet can not only trigger simultaneous longitudinal and transverse oscillations in a single filament, but also can be used as a seismology tool for diagnosing filament information, such as the magnetic structure, magnetic field strength, and magnetic twists.

Waveguiding driven by the Pancharatnam-Berry phase

We theoretically and numerically investigate the properties of waveguides based on the Pancharatnam-Berry phase, obtained by a longitudinally periodic rotation of the optic axis in a transversely twisted birefringent medium. In this paper we study the case where the period of the longitudinal modulation is chosen so that a net accumulation of geometric phase in propagation occurs. First, the interplay between different contributions to the optical potential is addressed. Second, a continuous evolution of the polarization structure of the quasimodes is observed in the numerical simulations. We explain it by a combination of plane-wave-based models and gauge transformations. We discover that, beyond the longitudinal oscillations, the polarization of the quasimode also varies through its cross section. The analogies with respect to charged particles moving in a magnetic field are outlined.

Comparative Study of Cooperative Platoon Merging Control Based on Reinforcement Learning.

The time that a vehicle merges in a lane reduction can significantly affect passengers' safety, comfort, and energy consumption, which can, in turn, affect the global adoption of autonomous electric vehicles. In this regard, this paper analyzes how connected and automated vehicles should cooperatively drive to reduce energy consumption and improve traffic flow. Specifically, a model-free deep reinforcement learning approach is used to find the optimal driving behavior in the scenario in which two platoons are merging into one. Several metrics are analyzed, including the time of the merge, energy consumption, and jerk, etc. Numerical simulation results show that the proposed framework can reduce the energy consumed by up to 76.7%, and the average jerk can be decreased by up to 50%, all by only changing the cooperative merge behavior. The present findings are essential since reducing the jerk can decrease the longitudinal acceleration oscillations, enhance comfort and drivability, and improve the general acceptance of autonomous vehicle platooning as a new technology.

Slow mode oscillations in curved arcade loops

ABSTRACT In this work we theoretically investigate the effect of curvature on the slow-mode oscillations in coronal loop arcade. A simple model of an arc circle magnetic slab is used to simulate curved coronal magnetic structures. Solving the set of magnetohydrodynamic (MHD) equations for a compressible plasma, we obtain the dispersion relation that governs the compressible MHD modes in the model. A band of slow body modes with phase speeds close to the internal tube speed and a single hybrid slow mode with phase speed close to the external tube speed are found to exist under typical coronal circumstances. The principal slow body and hybrid modes both produce radial kink-like displacements of the slab axis and distort its cross-section. These motions are accompanied with the dominating longitudinal oscillations. Such mode properties may result in Doppler shift and intensity oscillations as well as oscillating spatial displacements, observed in coronal loops. A number of observations of long-period oscillations in arcade loops are interpreted on the basis of the developed theory.

Longitudinal and transverse oscillations of the impact device tool under impulsive loads

The destruction process of the rock by the tool of the impact device occurs with an impulsive load on the tool from the recoil reaction from the side of the rock, not only in the axial, but also in the transverse direction. A model of the tool part of the impact device is considered, which takes into account the transverse and longitudinal tool oscillations. The tool model has the form of a rod for longitudinal loading and a beam of constant cross section for transverse loading. Transverse and longitudinal oscillations of the tool sections are considered independent. When calculating transverse oscillations, the tool is considered as a cantilever beam with a rigid mount at one end. The calculation scheme of longitudinal oscillations is represented by a rod with reduced elastic resistance at the end. Impulsive loads are modeled by the initial velocity distribution on the contact part of the tool. The initial-boundary value problem with wave equations of the second and fourth orders is formulated. The solution of the initial-boundary value problem by the Fourier method, realized in the Mathcad system, is proposed.

INCREASING OF VIBRATORY CONVEYING VELOCITY BY OPTIMIZING THE NORMAL VIBRATION

The paper is dedicated to researching the influence of normal vibration on the vibratory conveying velocity of particles on an inclined track that performs independent longitudinal and normal oscillations (two-component vibration). The study considers the optimizing conditions of the conveying velocity for different laws of oscillating components (harmonic, polyharmonic, oscillations with piecewise constant acceleration) with a limited value of the longitudinal acceleration of conveying track and with maximal normal acceleration that does not exceed the gravitational acceleration (non-hopping modes of moving, when particles slide without detachment from the surface). The optimization criterion is the maximal distance, traveled by the particle during the oscillation period, or the maximal value of dimensionless conveying velocity, depending on several dimensionless parameters. The maximal conveying velocity with polyharmonic normal oscillations is achieved at a certain ratio of the amplitudes of harmonic oscillation, which essentially depends on the track’s inclination angle to the horizon. The ratios of the amplitudes of harmonic oscillation, which practically do not reduce conveying velocity at any inclination angles, are proposed. Two-component vibratory conveying under normal oscillations with piecewise constant acceleration is considered in optimal non-hopping modes of a particle moving with one forward (or upward on an inclined track) sliding stage and one backward (or downward) sliding stage during the oscillation period. The equations for determining the dimensionless conveying velocity are derived for different values of dimensionless parameters, such as the inclination angle parameter (a ratio of an inclination angle tangent to a frictional coefficient) and the intensive vibration parameter (a ratio of the amplitudes of longitudinal and normal oscillations, divided by the frictional coefficient). The effectivity of polyharmonic normal oscillations in two-component vibratory conveying is compared with the effectivity of normal oscillations with piecewise constant acceleration. Maximal conveying velocity is achieved at certain values of phase difference angles between longitudinal and normal oscillations, which are called optimal. The value of dimensionless conveying velocity V increases with the increase of asymmetry of normal oscillations, which is described by the ratio n of the maximal acceleration of the track when moving down to the acceleration of gravity. This ratio n corresponds to the number of harmonics for polyharmonic oscillations. A comparison of values of V for normal oscillations with piecewise constant acceleration shows an advantage in velocity compared to polyharmonic normal oscillations at the same number n of harmonics, especially with increasing inclination angles. The research was carried out by the numerical step-by-step integration method, which allows for performing calculations with any given accuracy. The obtained results are demonstrated in figures and comparative tables.

Моделирование затухания нелинейных стоячих волн в высокотемпературной плазме

Longitudinal oscillations in hot post-flare coronal loops are studied in the nonlinear hydrodynamic approximation. To explain its rapid damping, the mechanism of thermal conductivity, important at high temperatures, is used. In the case of large amplitude, numerical simulations show that nonlinearity inhibits damping.

EFFICACY OF POROUS MEDIA ON FLUID-INDUCED VIBRATION OF A FLUCTUATING CYLINDER

In this research, the numerical simulation of the vibrations caused by the release of the vortex from the surface of the two-degrees-of-freedom circular cylinder, under the elastic support with the porous cover, has been done. The laminar flow around the cylinder is considered and the Reynolds number is < 250. The effect of the porous layer is investigated by considering its different thicknesses. In order to solve continuity and momentum equations for incompressible, unsteady, and two-dimensional flow, the finite volume numerical method based on the SIMPLE algorithm has been used. In addition, to simulate the fluid-structure interaction, the solver of the equations of motion of the rigid body in the flow direction and perpendicular to it is coupled with the computational fluid dynamics solver. The efficacy of the porous coat on the locking zone was investigated by comparing the transverse-longitudinal displacement diagrams and aerodynamic coefficients. The results show that, by adding the porous layer, the amplitude of transverse and longitudinal oscillations, the length of vortices, the drag and lift force are reduced. Up to 97% reduction of transverse vibrations in the porous state has been observed.

Исследование по динамике многоэтажных зданий

The design of multi-storey buildings is a natural trend in the development of a modern metropolis. Obtaining exact solutions when studying their own and forced oscillations within the framework of a continuous homogeneous medium model (continuum mechanics) with an infinite number of degrees of freedom is often difficult to implement. Therefore, in the article (as part of the modernization of the finite element method), the model of a multi-storey building is discretized and endowed with a finite number of degrees of freedom placed in the middle of the finite elements at the nodes (the mass of finite elements is also placed there), which elastically interact with the finite elements of the model that do not have mass. It is believed that the elements of a multi-storey building work only for bending, which is fully justified by comparing the frequencies of its bending and longitudinal oscillations. The resolving system of differential equations of oscillations of a multi-storey building, in which expressions for energies (potential, kinetic and Rayleigh) are written in quadratures, is obtained using Lagrange equations of the second kind. In the article, the problems of free oscillations of 3- and 100-storey buildings are solved using Green’s functions, stiffness, mass, compliance matrices, etc. The approximate results obtained in the article, when compared with the little-known approximate results obtained by other methods, as well as exact results (direct and indirect methods of boundary elements), showed a good correspondence.

Апаратурно-методичний комплекс досліджень петрофізичних властивостей тріщинуватих порід-колекторів вуглеводнів

We have developed the apparatus-methodical complex of laboratory investigations of fractured reservoir rocks of hydrocarbons. Basing on the study of variability of acoustic properties in different-oriented directions for measuring of raw pieces of core, it was possible to develop the apparatus for the express-diagnostics of the inner structure of the rock. The results of analysis of anisotropy of acoustic properties of the core give us the possibility to choose the specimens with abnormal properties on which one can conduct further investigations for determination of the factors of heterogeneity of rocks. Measuring of the velocity of longitudinal and transverse oscillations with recording their wave pictures is conducting in the acoustic bath. The acoustic system is equipped with corresponding adapter for connection to the computer that enables us to keep up the recording of all parameters of measuring. To estimate the permeability of microfractures and the influence of composite taut state upon them we have developed the device for studying radial filtration the results of which allow us to estimate the rock permeability due to the change in the structure and microfractures size depending upon the value and the character of the taut state. To measure deformational-strength parameters the corresponding plant was developed and produced, which was additionally equipped with a meter for the measuring of deformation, that allows to measure the values of contact strength, elasticity module and the boundary of rock strength while one-axis charging. The parameters are determined at arbitrary points of the core cuts, and the velocity of charging is half-automatically regulated at a wide bounds. The device is equipped with the electron controller that allows us not only to measure the value of contact strength, but to conduct observations on a display as to the changes in deformation depending on the charging value in real time and to put down the parameters of investigations into corresponding data base. Obtained characteristic of rocks is not only parametric basis for interpretation of materials of charging, but for the estimation of the changes in volume, type of porous space and permeability, and also for modelling of formation conditions of fractured reservoir, and on the whole, for prediction of zones (plots) where a dense rock with corresponding mechanical parameters should acquire the properties of the collector. The usage of the complex for the studying of fracturing in oil geology allows us to widen the prognosis and discovery of new fields and to improve production and exploitation possibilities of already acting ones.

Исследование по динамике рамных конструкций

Determining the natural and forced oscillations of frame structures simulated by the rods with distributed masses (an infinite number of degrees of freedom) is quite difficult. Therefore, in the article, the frame model is endued with a finite number of degrees of freedom: the mass is placed in a certain number of nodes that elastically interact with rods that have no mass. The rods work only for bending. Longitudinal displacements are not taken into account, since the frequency of longitudinal oscillations is two orders of magnitude higher than the frequency of bending ones. Such a model leads to the construction of expressions of the kinetic and potential energy, which then allows using the Lagrange equations of second kind to obtain a system of differential oscillation equations of the structure. The problem of free oscillations of the G-shaped frame was solved in the article using Green's functions, matrices of stiffness, masses, malleability, etc. The obtained approximate results were compared with little-known exact results and demonstrated good convergence, especially with an increase in the number of degrees of freedom (the number of concentrated masses simulating the distributed mass of the rods of the G-shaped frame).

Laser Vibrometry-Based Precise Measurement of Tape-Shaped Tethers Damping Ratio Toward Space Applications

To mitigate the growing problem of space debris, current international guidelines require spacecraft in Low Earth Orbit (LEO) to implement post-mission disposal strategies to be deorbited within 25 years from the end of their operative life. Electrodynamic tethers are an effective and promising option for deorbiting as they do not require fuel consumption. However, the success of this new technology also depends on the dynamic stability of thin tape-shaped tethers during both deployment and deorbiting phases. This is where precise measurement of damping characteristics of thin tape-shaped tethers comes in. This paper presents an innovative experimental setup and analysis methods for precisely measuring the damping ratio of a thin (thickness 50 microns) tape-shaped tether made of PEEK intended for use in electrodynamic tethers applications. To capture longitudinal oscillations during dynamic tests, we employed a laser vibrometer and explored four different methods of experimental data analysis, comparing and describing them in detail in the paper. We also conducted an uncertainty analysis in line with ISO GUM. The experimental results show good agreement among the four methods used to estimate the damping ratio with the most precise method involving nonlinear regression applied to all the experimental data. A Monte Carlo analysis was carried out considering the most significant sources of uncertainty. The smallest uncertainty interval is ±1% of the estimated damping ratio, with a 95% confidence level, using this method.

СИНЕРГЕТИЧЕСКИЙ СИНТЕЗ АВТОПИЛОТА ДЛЯ УПРАВЛЕНИЯ ДВИЖЕНИЕМ САМОЛЕТА-АМФИБИИ БЕ-200 ВО ВРЕМЯ ЗАБОРА ВОДЫ

The article is devoted to solving the problem of controlling the Be-200 amphibious aircraft whentaking water in the gliding mode. The specified mode of flight of an amphibious aircraft (AA) is one ofthe most intense for piloting. Controlling an aircraft in gliding mode requires the highest concentrationfrom the pilot, since the hydrodynamic characteristics decrease, but the aerodynamic ones increase,which causes situations in which the SA becomes uncontrollable. To ensure the safe operation of the AAduring water intake, as well as to ensure a steady takeoff, the pilot is forced to constantly maintain acertain value of speed, trim angle, and engine thrust by moving the engine control stick (ECS). In thisregard, it seems very appropriate to use the technical means of the autopilot, which provides control ofthe speed, engine thrust and trim angle to ensure the stability of the movement of the SA during the intakeof water. The article deals with the problem of synthesizing an autopilot to control the movement ofan amphibian aircraft during water intake, and at the same time the following tasks are solved: thesynthesis of an autopilot to control the longitudinal movement of an amphibian aircraft, as well as controllanding on water, followed by water intake and takeoff from the water. The substantiation of thechoice of a mathematical model of the movement of an aircraft on water is given. A procedure for thesynergistic synthesis of the autopilot controller of an amphibious aircraft in the water intake mode presented.The novelty of the ongoing research lies not only in considering the stable movement of an amphibiousaircraft during its operation on the water surface, but also in modeling the process of water intake in planning mode, which is a more complex task from the point of view of synthesis. As a result,the control laws for the autopilot obtained, which ensure the stable movement of the amphibious aircraftwhen descending along the glide path, landing on water, taking in water and subsequent takeoff withdamping of longitudinal oscillations along the trim angle throughout the entire water intake cycle.

VERTICAL VIBRATING MOVEABLE DEVICE

Modern industry is characterized by a high level of automation of technological operations in the production of any product. Thus, in order to save production space, as well as to organize the transportation of objects under the ceiling of the workshop, suspended transportation robotic systems are used. With their help, workpieces are supplied to workplaces, and finished parts to assembly positions, as well as loading and transfer of materials and finished products. First of all, it concerns the electronic and radio-electronic industry. There are a number of transport devices where the cargo flow can move both horizontally, at an angle to the horizon, and vertically. Transportation in the vertical plane can be carried out thanks to a working element such as a belt, rope, chain, combined element, auger, pipe, or a medium (air, water) or a phenomenon (electromagnetic field, vibrations). On the basis of the analysis of their designs and the patent search, it is possible to conclude that the working process of moving goods in the vertical plane, in connection with its wide variety of choosing a design solution, is the subject of scientific research, and the orientation of designers to the modernization of these means of movement, primarily with the aim increasing the efficiency of use, the energy efficiency coefficient and reducing the material consumption of equipment always remains an urgent task of mechanical engineering. The choice of such means depends, first of all, on its type, technological purpose, technical and economic indicators of production. All this indicates the need to deal with this issue, because even a slight improvement of these indicators gives a significant economic effect as a whole. In this work, as a development of alternative means of movement in suspended transport robotic systems, vibrating mobile devices, which can contain a cargo platform with a product or, for example, a simple manipulator, have become. We suggest you familiarize yourself with the results of the device's research in the forward and reverse direction of movement in the vertical plane. For the convenience of the study, a round profile (pipe) is taken as a monorail, on which a mobile vibrating device is strung. The design of the device can be quite diverse: in the form of elastic elements, brake, friction, overtaking, eccentric and ratchet mechanisms, etc. In this case, an elastic conical collet is used, which contacts the surface of the column. An effective means of implementing the given function is the use of an electromagnetic pad brake. The structure is built according to a two-mass scheme, which contains a working body, an electromagnetic drive and a locking mechanism. The effect of vibratory movement of the device along a vertical (rough) pipe is realized according to the asymmetry scheme of the first type under the action of longitudinal harmonic oscillations. Cyclic programming provides automatic execution of specified operations, stopping at loading and unloading positions, changing the direction of movement.

Computer modelling of dynamics of the thread in technological process

The article covers the technology of computer modeling of technological processes on example of the research of transverse oscillations of the thread in weaving process. During the formation of the fabric, various dynamic processes took place, including fluctuations in the threads. As an example, the longitudinal oscillations and tension of the threads in the process of surf on a loom are considered. The program and the results of the calculation are given using the software package “Mathcad”.

Temperature distribution of the gas on the axis at longitudinal intensive oscillations in an open tube near resonance

The oscillations of gas pressure along the axis of an open tube near resonance are investigated. The temperature distribution of the gas along the axis in the open tube using a thermistor was obtained. An acoustothermal effect at the resonance frequency in the form of an irregular axial temperature distribution in the tube is detected.