Physical Essence Research Articles

Results of Experimental and Theoretical Studies of the Possibilities of the Resonance Method of Ice Cover Destruction

Based on experiments carried out: in ice basins; with large-scale models of hovercraft in the field; with full-scale hovercraft, as well as using theoretical dependencies for calculating the stressstrain state of the ice cover from the action of moving loads, the possibilities (patterns) of the resonant method of ice destruction, i.e., by excitation of resonant flexural-gravity waves (FGW), were studied. Its physical essence, the expediency of its implementation by a hovercraft are explained, the possible areas of effective use of this method are indicated. The results of the information review on the topic of the work are given, on the basis of which the purpose of the research is set. When describing the viscoelastic nature of the relationship between stresses and strains in ice, the Kelvin-Voigt law of deformation of an elastically retarded medium was used. The theoretical bending potential energy density of an infinite plate was taken as a criterion for the ice breaking capacity of FGW. In this case, the condition is used that when it reaches a certain value, complete (with the opening of cracks) destruction of ice occurs. The initial data for these calculations are taken from the performed experiments. Dependences are given that make it possible to determine the parameters of a load moving at a resonant speed (hovercraft parameters) sufficient to destroy an ice cover of a given thickness under given ice conditions.

A method to address beam cross coupling errors in phased array Doppler sonar

Performance of Doppler sonar is degraded by beam cross coupling errors. This performance degradation presents itself as the loss of precision and bias of velocity estimates output by the system. A model is proposed here to reveal the physical essence of the beam cross coupling. Specifically, the model can analyze the effects of environmental conditions and vehicle attitude on the coupling bias. Based on this model, a phase assignment method is also proposed to reduce the beam cross coupling bias. The results obtained for various settings validate the efficacy of the proposed method.

Physical models for vacuum-induced multistage atomization of high-entropy FeCoCrNiMo alloy powder for 3D printing

The atomization process of high-entropy FeCoCrNiMo alloy was tested using electrode induction gas atomization (EIGA) at different powers, pressures and rotary speeds. The modelization about the physical essence in the metal drop atomization was studied. A surface tension model, a specific surface energy model, a cooling rate model, and a solidification kinetic model of the alloy drop atomization process were built. Based on these models, the quantitative relationships between the powder particle size and process parameters during the alloy atomization were determined. Together with the results of particle size and scanning electron microscopy-based morphology of the powder obtained from EIGA under different process systems, the accuracy of the above physical models was validated.

A Universal Formation Mechanism of Hollow Multi‐Shelled Structures Dominated by Concentration Waves

AbstractHollow multi‐shelled structures (HoMS), a new family of hierarchical nano/micro‐structured materials, have evoked intensive studies to discover their unique temporal‐spatial ordering features. The theoretical understanding of the general synthetic methods of HoMS, i.e. the sequential templating approach (STA), makes it possible to understand, predict, and control the shell formation process. Herein, a mathematical model is established based on the experiment results, which reveal the appearance of concentration waves in the STA. The numerical simulation results not only correspond well to the experimental observations but also explain the regulation methods. Whereby, the underlying physical essence of STA is elucidated, suggesting that HoMS is the concrete representation of the concentration waves. Thereafter the formation of HoMS is not limited to the solid‐gas reactions through high‐temperature calcination, but could be extended to solution systems under low‐temperature conditions.

A Universal Formation Mechanism of Hollow Multi-Shelled Structures Dominated by Concentration Waves.

Hollow multi-shelled structures (HoMS), a new family of hierarchical nano/micro-structured materials, have evoked intensive studies to discover their unique temporal-spatial ordering features. The theoretical understanding of the general synthetic methods of HoMS, i. e. the sequential templating approach (STA), makes it possible to understand, predict, and control the shell formation process. Herein, a mathematical model is established based on the experiment results, which reveal the appearance of concentration waves in the STA. The numerical simulation results not only correspond well to the experimental observations but also explain the regulation methods. Whereby, the underlying physical essence of STA is elucidated, suggesting that HoMS is the concrete representation of the concentration waves. Thereafter the formation of HoMS is not limited to the solid-state reactions through high-temperature calcination, but could be extended to synthetic systems under mild conditions.

Study of linear and angular oscillations of the moving platform of the ground robotic complex

Background Modern ground robotic complexes have a significant speed, which leads to the occurrence of vibrations of the platform and the manipulator. The problem is to develop highly efficient vehicles that take into account dynamic processes, and their impact is minimized by constructive solutions and dampers. Objective The purpose of the work is to study the dynamics of the moving platform of the robotic complex and establish its dynamic parameters. At the same time, it is necessary to determine the characteristics of oscillatory processes, in particular, linear and cross-angular movements of the platform. Methods A dynamic model of the platform has been developed. It has three degrees of freedom and takes into account the working processes of caterpillars and rollers. The calculation scheme has six points of support on the surface. The method is based on finding the position of the rollers determined by the profile of the road surface. The elastic-dissipative properties of the track and the surface are taken into account in the model. A research of the platform during its movement on a surface with a complex profile was carried out. Polyharmonic dependencies with random parameters are used to describe it. Results The developed model determine the dynamic characteristics of the robotic platform during its interaction with irregularities of arbitrary shape. Based on the found equations of spherical motion, mathematical modeling of work processes was carried out, angular coordinates and angular speeds of platform rotation were determined. Conclusions The results of modeling the spherical movement of the platform correspond to the physical essence of work processes. These data are necessary for studying the dynamics of the manipulator of the mobile robotic complex. Minimization of platform oscillations improves the characteristics of ground robotic complexes moving at a high speed.

Transient and Steady-State Performance Improvement of IM Drives Based on Dual-Torque Model

Transient response performance and steady-state operation performance are the two most important performance indicators of a motor drive system. In order to solve these two problems, this study proposes a new induction motor (IM) model, and then designs a new simplified linearization controller method. First, the tangential force that determines the transient process of the motor is represented by electromagnetic torque, and the radial force is represented by reactive torque. Then, the dual-torque model of IM is derived, which not only accurately shows the rotating air-gap magnetic field through the amplitude and rotating angular frequency, but also visually demonstrates the physical essence of the transient process of IM. Then, this study proposes a simplified feedback linearization method without the analysis of zero dynamic. In addition, a time-scale hierarchical control system is designed to reduce the ripple caused by the coupling of different time-scale variables. The experimental results show that the steady-state torque ripple of the proposed method is 65% lower than that of RFOC, and the torque response speed is 10% higher than that of DTC.

Importance of the average radius of coal particles on determining the methane diffusion coefficient.

The average radius of coal particles is an estimate of the diffusion path in the particle method for determining the diffusion coefficient. It is currently calculated using the arithmetic mean of coal particle sieved intervals. This calculation, however, ignores the coal particle size distribution, resulting in significant deviations when calculating the gas diffusion coefficient. An appropriate average radius calculation method should consider the particle size distribution and the physical essence of diffusion. To accomplish this, a series of methods for calculating the mean particle diameters and their physical significance were reviewed. Next, coal samples were sieved into three intervals, and gas diffusion tests and laser particle size distribution were conducted. Results show that coal particles are within the sieving interval, ranging from 42.01 to 76.18%. By solving the diffusion coefficients using four mean particle diameters based on particle size distribution and diffusive mass transfer, the difference between the arithmetic mean value and these diameters is up to 89.06%. [Formula: see text] and [Formula: see text] are preferred for the calculation of the average radius since they are compatible with coal particle shape and the physical meaning of diffusive mass transfer.

More than an Afterimage: Music as Holocaust Spatial Representation and Legacy

Music occupies a unique and multi-faceted role in spatial representation of the Holocaust, both in terms of documenting its horrors and in cultivating legacy. This uniqueness derives from music’s dual temporal and physical essence as it is represented by written scores that serve as a blueprint, as sonic events that fill both time and space, and as musical instruments that operate as conduits for both. String instruments, in particular, have occupied a vital place in Jewish culture and, consequently, during the Holocaust. In the most tragic sense, some of these instruments even became actual containers of genocidal evidence as with violins played outside concentration camp crematoria that filled with the human ash that fell. This article will demonstrate that, when played, these instruments transform into living artifacts and musical witnesses, with voices that can speak for those who have been silenced, and that the resulting music that resonates from the printed page fills a sonic space that serves as a powerful medium for memory and representation. The phrase “bearing witness” often refers to representing the stories of people, places, and experiences through words, either written or spoken. But material culture also has a role to play in representation. While objects, art, and architecture certainly support language-based witness, they also provide their own unique lens and conduit for testimony. This seems especially true for music, which has the ability to exist as and cross between both words and objects. Nevertheless, music as material witness remains a complex and often understudied aspect of historical testimony. As a result, this paper will explore through an interdisciplinary approach the divergent nature of music as an aural form, as a creative art, and as a cultural artifact and will offer examples of how music can enhance, elucidate, and complicate Holocaust representation.

Development of Experimental Facilities for Studying the Process of Electric Pulse Neutralization of Automobile Exhaust Gases

The main goal of the research work described in the article is to determine the optimal operating mode of the future electric pulse silencer to solve the problem of efficient cleaning of exhaust gases of an internal combustion engine (ICE) by an electric pulse. According to the purpose of the study, a number of research methods are used in the article, in particular, the physical essence of the process of electropulse cleaning of exhaust gases of internal combustion engines of cars is described and an analysis of known patents in this direction is carried out, as well as experimental installations designed to determine the mode of neutralization of exhaust gases based on such parameters as voltage, duty cycle, distance between electrodes. The devices were made from various electrically conductive materials. Preliminary experiments on the units showed that under the action of an electric pulse, an increased oxygen content was observed in the exhaust gas, which gave rise to a hypothesis about the possibility of determining the optimal operating mode of an electric pulse silencer. In support of the hypothesis put forward, the task was to develop the design of an electric pulse silencer and a method for cleaning exhaust gases to optimize its operation. As a result of the implementation of the task, a patent was obtained for a utility model that characterizes the design of an electric pulse silencer and the method of gas cleaning by an electric pulse

THE PROBLEM OF CRACK OPENING WIDTH AND STIFFNESS OF REINFORCED CONCRETE STRUCTURES, BUILDINGS AND CONSTRUCTIONS

The article defines the main results for the development of reinforced concrete mechanics. In the isotropic medium between the cracks is used "first object - flows-blocks", "second object - main cracks" and the effect of reinforced concrete, the physical essence of which is the non-uniformity of concrete and continuous reinforcement. Reactions arise in the concrete for deformation of the reinforcement from the bonding of the compressed concrete in the tensile region. The average resistance of the tensile concrete and the "average total force of the working reinforcement," the third object, are transmitted through the effect of reinforced concrete and the "dowel" effect. The crack opening widths are the relative mutual displacements of reinforcement and concrete, determined from the boundary conditions and the Thomas-Author hypothesis. A new classification of cracks has been developed: regular cracks (anisotropic medium of reinforced concrete) and main cracks based on the effect of reinforced concrete (origins - concentrations) and maximum opening in the closed equations of mechanics of reinforced concrete from the Lagrange function. The author has proposed hypotheses, theorems of linear and angular deformations, functionals for deplanation of cross section of reinforced concrete element from elastic-plastic stage, jumps - cracks and stiffness matrix in a single compound strip which allow to reduce the order of differential equations. The resistance design model method for reinforced concrete mechanics is used for the rod, wall, and slab of the "envelope" of cracks. Hybrid from Lira (finite element method of reinforced concrete from anisotropy) developed in the form of two finite element effect of reinforced concrete of "flat and spatial cantilever" for external and internal displacements. The general principle from Loleith to the "opening - closing" of cracks, the stiffness of the mechanics of reinforced concrete is obtained in the form of the method of the computational model of resistance.

A new mathematical model of rigid boundary in shear flows

The present investigation is devoted to the revealing of the physical essence of the action of the rigid boundary on the linear dynamics of perturbations in plane shear flows. A new mathematical approach is proposed which accurately and completely replaces the horizontal rigid boundary by the actions of certain localized sources placed on the plane of the boundary (z = 0) in the original/canonical shear flow dynamical equations for wave and vortex mode perturbations, i.e. for perturbations with zero and nonzero potential vorticity. The approach is elaborated on the example of the well-known problem of geophysical hydrodynamics—the linear dynamics of perturbations in semi-infinite () flow of stratified rotating fluid with a vertical shear of velocity, , zero beta, β = 0, and horizontal rigid boundary at z = 0—which analytical wave and vortex mode solutions are well-known and serve as the reference solutions of our model equations. From the beginning, we have replaced the rigid boundary with localized sources for vortices and wave modes separately. The sources are the sum of the delta function and its first derivative the coefficients in front of which were unknown at this stage. In what follows, we accurately calculated these coefficients and thus determined the exact expressions for localized sources. Subsequent mathematical analysis showed that the localized sources give rise to new perturbations which can be labeled as secondary. The revealed physical essence of the action of the rigid boundary is as follows: being the external (localized) source of the analyzed open complex flow system, the rigid boundary puts an additional energy into perturbation harmonics that becomes an important power supplier supporting the linear dynamics of the system under study. Namely, the rigid boundary rearranges the vortex component via exciting new/secondary perturbations, which, superimposing with the main/primary perturbations of the flow, ensures zeroing of perturbations in the area z < 0 and, at the same time, provides the growth of the wave component in the area coinciding with the well-known analytical solution of the canonical approach. From a general point of view, the following is important: In the existing/classical trend of studying the dynamics of perturbations in bounded shear flows, the actions of the flow boundary/boundaries and the flow shear are not delimited from each other. Whereas, the proposed new mathematical approach delimits them highlighting the action of the boundary on the linear dynamics of wave and vortex modes of perturbations.

Pulsed thermo-induction-dynamic welding and pressing of dissimilar materials

To obtain permanent joints from diversified parts and powder compositions, it is proposed to use discharge-pulse processes with the accumulation of stored energy in a capacitor bank. Technological difficulties in the manufacture of structures from non-ferrous metal and alloy parts of different thicknesses are listed. The thermal effect is carried out by passing the discharge current from the batteries of pulse capacitors, and the power effect is realized through the use of an inductive-dynamic drive. A scheme for the series connection of a compacted powder with an induction-dynamic drive, consisting of a flat inductor with a pusher, is proposed. The physical essence of the formation of compounds is described. The processes responsible for the formation of permanent connections by a pulsed current discharge have been identified. A picture of the relationship between the main parameters of the pressing process – sintering in time, as well as the results of measuring the temperature of the sintering process of powders by the photoemission method is presented. The results of energy consumption for the consolidation of powder compositions with simultaneous welding to a steel base are given.

Planting of nanoparticles controlled by high energy laser irradiation on the surface of SiC whisker

The surface modification of silicon carbide whiskers to raise the specific surface area and mechanical blocking function, which can effectively improve the reinforcing and toughening effect of the whiskers on engineering structural materials. In this study, it is proposed to directly metallurgical plant nanoparticles on the surface of silicon carbide whiskers by high-energy laser irradiation. The metallurgical reaction of the whisker-nanoparticle interface is realized by the transient gaussian laser energy field action and the formation of a binding layer of about 10 nm thickness. However, the whisker surface still maintains the regular trench morphology after the whisker is etched, and the structure greatly improving the generation efficiency of the whisker-nanoparticle metallurgical interface bonding layer. The material phase before and after laser irradiation maintains a consistent β-SiC crystal. TEM results are displayed that the whiskers and nanoparticles in the metallurgical binding region indicate that the (111) plane arranged parallel along the [111] orientation. TEM- EDS mapping shows that the whiskers formed after irradiation are almost free of nitrogen and oxide impurities. So that the final product can maintain the original phase and physical essence of the material. These results proved that laser irradiation is a highly stable processing technique for texturing modification of whisker surfaces.

Mathematical modelling of stress-strain state of steel-concrete beams with combined reinforcement

Abstract Most of the modern computer software for the building structures‘ calculation is based on mathematical dependencies which make it possible to analyse rather complex stress-strain state of structures subjected to loading. As a rule, the calculation is based on the finite element method and is reduced to the calculation of deformations arising in structures due to the action of external forces with the use of real strain diagrams of materials, σ-ε diagrams for concrete and reinforcement. Modern normative regulations for reinforced concrete structures‘ calculation are also based on the deformation model using material deformation diagrams, which are as close to the real ones, as possible. Therefore, this study was aimed to investigate in more detail the stress-strain state and the physical essence of the processes occurring in reinforced concrete structures with combined reinforcement according to mathematical approaches and regulations of DBN B.2.6-98:2009 and DSTU B. In 2.6-156:2010. Namely, in the research is analysed the combined reinforcement of S245 steel tapes and A1000 rebar, which is used in the production of reinforced concrete elements. The results of mathematical modelling were compared with the calculation results, according to DBN B.2.6-98: 2009 and DSTU B. B 2.6-156:2010, as well as with field experimental data. Therefore, the conclusion could be made, whether it is possible to use this technique with sufficient accuracy to calculate reinforced concrete structures with combined reinforcement.

Wave patterns and dynamical properties of optical propagation by a higher order nonlinear Schrödinger equation

It is of great significance to explore the physical properties of optical propagation, thus the scholars are keen on the physical essence represented by classical mathematical physics equations. In this paper, a higher order nonlinear Schrödinger equation describing the behavior of polarization mode in optical fibers is firstly analyzed qualitatively, and the existence of periodic and soliton solutions is proved by using bifurcation method. Secondly, all chirped wave patterns with special form for the equation are obtained by using the complete discrimination system for polynomial method and direct integral method, the chirped rational functions and some elliptic functions wave patterns are initially found. As a result, the parameter stability of these patterns is given for the first time, which shows the variant of patterns as the parameters change, and the graphs of several typical patterns are drawn.

Вопросы преподавания иностранных языков в высших образовательных организациях неязыкового направления

The purpose of the study is to consider the second component of language communication — communication, that is, the mechanism of acts of exchange of language signs. Despite the fact that the system of language signs and communication are phenomena with completely different physical nature and essence, the fact that they both act as different aspects of the same complex phenomenon — language communication, determines their closest relationship and interdependence.. The article formulates the prerequisites that actualize the question of the need for the division of language signs into two categories for understanding the mechanism of language communication: ready-made signs, or signs stored in the memory of speakers (writing) in the form of "images" or "prints", and new signs, or signs created by speakers (writing) in themselves acts of communication. In addition, the analysis of the definition of "ready-made" and "new" signs is carried out, this classification refers to the communicative side of language communication and primarily concerns the process of transmitting language messages (speaking, writing). Special attention is paid to the division of signs into ready—made and new ones quite clearly takes place only in each individual act of communication and is valid for this particular person - the speaker or the writer. The tasks of developing a methodology for teaching languages are defined. Mastering both aspects of the transmission technique — storing a stock of ready—made signs in memory and the skills of forming new signs (sign formation) - seems equally important. At the same time, it is necessary, however, to take into account that the specific weight of these aspects in communication significantly depends on the order of the sign. The logical result of the study was the conclusion that the very fact of the division of signs appearing in any act of communication into ready-made and new ones and the knowledge of the general laws of this division helps us to uncover the true mechanism of language communication and, based on this, to determine the ways of the most rational mastery of the technique of transmitting language messages, which presents the greatest difficulties for the language learner. It is also appropriate to emphasize that with the help of a statistical survey, it is possible to select those signs of all orders that should become "ready" for the student (i.e. stored in his memory), in order to ensure his full participation in language communication (in his given field). And this is of paramount importance for the compilation of effective textbooks of foreign languages.

Thermal-seepage coupled numerical simulation methodology for the artificial ground freezing process

This paper proposes a thermal-seepage coupled numerical simulation methodology for the artificial ground freezing (AGF) process using measured soil freezing characteristic curve (SFCC). Firstly, the relation equation between pore ice content and temperature is established based on the measured SFCC, and a thermal-seepage coupled simulation method of AGF is proposed. After that, the performance of the proposed method was investigated based on soil column and large-scale model tests. Finally, the proposed method is compared with the traditional apparent heat capacity method. The results show that: (1) By introducing SFCC, the relation equation between pore ice content and temperature can be established with a clear physical meaning and a direct parameter determination process; (2) The proposed method can reasonably simulate the thermal and hydraulic field of AGF with or without seepage; (3) Compared with the traditional apparent heat capacity method, the proposed method has a conform to physical essence of phase transition and potential heat release and shows comprehensive improvement in theoretical basis, calculation accuracy, robustness and efficiency. Overall, the research results can provide a further understanding and improvement for numerical simulation in AGF.

A Universal Method for Extracting and Quantitatively Analyzing Bias‐Dependent Contact Resistance in Carbon‐Nanotube Thin‐Film Transistors

AbstractA single‐device method is reported for extracting gate‐ and/or drain‐voltage‐dependent contact resistance of thin‐film transistors (TFTs). An extended transition‐voltage method is proposed and verified by experiments of all‐carbon‐nanotube thin‐film transistors (ACNT‐TFTs), which can extract gate‐ and/or drain‐voltage‐dependent contact resistance at source and drain independently. By measuring the output and transfer characteristics of a single‐device and extracting the basic parameters with the aid of mature Y‐function method, the contact resistance can be calculated directly. The results show that although a slight Schottky contact behavior is exhibited at very small drain voltages, good electrical contact characteristics can still be obtained in ACNT‐TFTs, exhibiting quasi‐Ohmic contacts. Compared with the existing single‐device methods, this method is suitable for both Ohmic and Schottky contact scenarios without requiring a complex iteration process, which greatly improves the universality and efficiency of the contact resistance extraction. Besides, this method reveals the physical essence of the complex interface contacts and enables researchers to quantitatively analyze the contact performance, not only for network carbon nanotube TFTs but also for the other emerging transistors.

Threshold-like Superlinear Accumulation of Excitons in a Gated Monolayer Transition Metal Dichalcogenide

Coexistence and mutual conversion of various excitonic species in semiconductors are the essence of Mott physics and underpin important device applications such as excitonic or polaritonic lasers. The emergence of monolayer semiconductors provides unprecedented opportunities to study these fundamental issues due to the much larger exciton binding energies. In this paper, we study the evolution of the coupled exciton–trion system in electrically gated monolayer MoTe2 devices. Contrary to the conventional linear scaling, we found that exciton density exhibits an abnormal three-stage scaling behavior: a conventional linear scaling at low pumping levels, followed by a superlinear behavior accompanied by a strong saturation of trion emission. In the third stage, the exciton emission returns to the linear scaling with the further increase of pumping. Although such behavior has a rare similarity in other physical systems, surprisingly we discovered a complete analogy of this behavior with the threshold of a conventional laser and proved mathematically that the exciton–trion equations are identical to the laser equations. We further showed that the power-law index increases with the charge density experimentally and can be as high as 40 at a density of ∼1 × 1012/cm2 in principle, leading to extremely nonlinear behavior of exciton accumulation. Our results reveal a new behavior of exciton accumulation and provide an alternative mechanism for multiplying exciton population, in analogy to a condensate. The intricate dynamics between excitons and trions will also enrich our understanding of the complex Mott physics in 2D semiconductors and may lead to new devices based on the exciton nonlinearity.