Uniform Motion Research Articles

Гидравлическое сопротивление системы управления движением инспекционного снаряда с клапаном обтекаемой формы в газопроводе низкого давления

The main problem while developing inspection shells for low-pressure gas pipelines is mainte-nance of their uniform motion under the action of the pumped gas. In the present work, we propose a solution to this problem based on changing the cross-section of the central flow channel of the smart pig by moving an axially symmetric valve along the axis of the channel. Two types of valves with a drop-shaped and a cone-shaped front part were considered. The choice of the valve shape and size can be made by calculating the forces acting on the smart pig during gas flow. The prob-lem was solved by the methods of computational fluid dynamics under the assumption of axial flow symmetry. The gas was considered to be compressible. The calculations showed that the total force acting on the valve and walls of the flow channel does not depend on its shape and, depending on the valve position, can change by more than two times. The optimum length of a drop-shaped valve is nearly half that of a conical valve. Although the drop-shaped valve produces a more inhomoge-neous velocity field than the conical valve, the former is more acceptable for regulating gas flow through the central channel of the inspection smart pig.

Переход от равномерного режима движения полярона к колебательному при изменении начального поляронного состояния

A study of the nature of the motion of a Holstein polaron in a homogeneous polynucleotide chain in a constant electric field, depending on the initial polaron state, was carried out. The calculations performed showed that the duration of the uniform motion of the polaron along the chain is finite and depends on the entire set of system parameters, including the characteristic size of the initial polaron state. It is shown that at a fixed value of the electric field intensity, an increase in the characteristic size of the initial polaron state leads to a decrease in the time of uniform motion of the polaron along the chain. It is also shown that a change in the shape of the initial polaron state exerts influence upon not only the duration of the uniform motion of the polaron along the chain, but also the characteristics of the low-density components of the polaron.

Elements of hydraulic calculation of permanent movement at non-standard sewer collectors

An important issue in the design of the main visitable sewer collectors is the hydraulic calculation in permanent movement and non-permanent movement. Some main collectors that can be visited have non-standard flow sections, a situation that complicates the hydraulic calculation. Non-standard flow sections derive from standard sections (circular, ovoid, bell, rectangular and mixed) through natural and anthropogenic degradation processes. The initially designed section changes over time in terms of shape, dimensions and roughness, a situation in which determining the hydraulic parameters becomes very difficult. The research carried out on a series of visitable main collectors revealed that the flow section has geometrically transformed from curved shapes to mixed shapes (curves + right-hand segments).The hydraulic rehabilitation of degraded collectors requires the analysis of flow parameters in the case of geometrically modified sections. The non-standardized flow section can be considered as a “single bed”, or as a “multiple bed”. At the same time, the “single bed” type sections composed of both circular arcs and straight line segments can be hydraulically analyzed with a customized calculation program. The paper presents a model for calculating the geometric and hydraulic parameters of a sewer collector with a non-standard shape and in permanent uniform motion.

Unsupervised Low-Light Video Enhancement with Spatial-Temporal Co-attention Transformer.

Existing low-light video enhancement methods are dominated by Convolution Neural Networks (CNNs) that are trained in a supervised manner. Due to the difficulty of collecting paired dynamic low/normal-light videos in real-world scenes, they are usually trained on synthetic, static, and uniform motion videos, which undermines their generalization to real-world scenes. Additionally, these methods typically suffer from temporal inconsistency (e.g., flickering artifacts and motion blurs) when handling large-scale motions since the local perception property of CNNs limits them to model long-range dependencies in both spatial and temporal domains. To address these problems, we propose the first unsupervised method for low-light video enhancement to our best knowledge, named LightenFormer, which models long-range intra- and inter-frame dependencies with a spatial-temporal co-attention transformer to enhance brightness while maintaining temporal consistency. Specifically, an effective but lightweight S-curve Estimation Network (SCENet) is first proposed to estimate pixel-wise S-shaped non-linear curves (S-curves) to adaptively adjust the dynamic range of an input video. Next, to model the temporal consistency of the video, we present a Spatial-Temporal Refinement Network (STRNet) to refine the enhanced video. The core module of STRNet is a novel Spatial-Temporal Co-attention Transformer (STCAT), which exploits multi-scale self- and cross-attention interactions to capture long-range correlations in both spatial and temporal domains among frames for implicit motion estimation. To achieve unsupervised training, we further propose two non-reference loss functions based on the invertibility of the S-curve and the noise independence among frames. Extensive experiments on the SDSD and LLIV-Phone datasets demonstrate that our LightenFormer outperforms state-of-the-art methods.

Hamster (Cricetinae) Motion Assisted by Video Tracker Application on Motion Materials in Junior High School

This study aims to explain the phenomenon of motion in hamsters moving in a rolling wheel. Motion is one of the materials taught at the 7th-grade junior high school. The study can be used in learning with the practicum method, namely animal motion. Hamster (Cricetinae) motion is analyzed using a video tracker analysis application with a javascript program. This study used a direct experiment using a hamster using four reference points, namely the forelegs, head, middle body, and hind legs. The results of data analysis from the tracker application were processed using the Microsoft Excel program to obtain a graph of changes in the position and velocity of the hamster. Hamster motion on the rolling wheel is a type of translational motion, namely uniform linear motion. Changes in the hamster's position indicate motion on a horizontal line. The velocity obtained in the tracker application is more accurate than manual calculations.

Asynchronous Motor in a Mild Hybrid Vehicle

Problem. Strengthening requirements for reducing CO2 emissions requires reducing fuel consumption in cars with internal combustion engines. One of the ways to solve this problem is to equip cars with a hybrid power plant that combines an internal combustion engine and an electric motor. A classic hybrid vehicle requires two energy sources: a fuel tank for the internal combustion engine and a power battery for the electric motor. Therefore, hybrid vehicle has a more complex design and a relatively high cost. A mild hybrid vehicle is a new concept of a hybrid vehicle for urban use that is emerging today. Such MHVs have a simpler design and also allow you to save up to 30% of fuel in urban driving mode. Goal. The purpose of the work is to improve the economic and environmental characteristics of a mild hybrid car, due to the use of an inexpensive asynchronous electric motor with frequency control in the scalar mode, as well as more effective use of power plant control system algorithms. Methodology. Analytical research methods were used to develop algorithms for effective use of the power plant in acceleration, uniform motion, regenerative braking, and stopping modes. Mathematical modeling and calculation methods were used to justify the use of an asynchronous motor for the power plant of a mild hybrid vehicle. Results. The use of a low-power asynchronous motor in the power plant of a mild hybrid vehicle is mathematically justified. The use of the principle of rational amplitude-frequency scalar control is proposed. An algorithm and a scheme for the implementation of an induction motor control system with support for the optimal power factor have been developed. Originality. Instead of using a valve synchronous electric motor with an expensive control system, it is proposed to use an asynchronous motor, which has advantages in the power plant of a mild hybrid vehicle. An asynchronous motor will allow the use of effective algorithms of uniform motion and regenerative braking modes. Practical value. The design of a soft hybrid vehicle with the use of a low-power asynchronous electric motor makes it efficient and cost-effective. The scalar control method of an asynchronous motor, with the slip control, makes it possible to obtain a system with high control quality and lower cost of implementation.

Dynamic skin effects in non-Hermitian systems

We study the time evolution processes of non-Hermitian systems under the open boundary condition and confirm that the dynamical skin effect exists in non-Hermitian systems analytically, and unveil the mechanism of its formation, which is caused by both the non-Hermitian skin effect and the Hermitian wave packet spreading. Furthermore, we find that in contrast to the uniform speed motion in Hermitian situations, the Gaussian wave packet can be accelerated and amplified during its time evolution in non-Hermitian systems. This additional motion is found to be responsible for the dynamic skin effect.

Method of estimating the time required to ensure the uniform motion of vehicle platoon progres-sion on the coordinated section of the city arterial road

Problem. The problem of distributing competing flows of road users in time is prevalent worldwide, and there is no fully justified and intelligible solution, even if only traffic flows can be considered. At the busiest street intersections, the primary means of traffic management is traffic signal control. If the traffic lights are close to each other, then it is a good practice to coordinate the operation of such traffic lights to organise the most unhampered movement of vehicles in one or several directions; that is the progression. Goal. The goal is estimation of the time required to ensure the uniform motion of vehicle platoon progression on the coordinated artery of the city arterial. Methodology. The developed approach is based on the use of analytical research methods and allows to formalize the interaction of the platoon progression with additional vehicles. Results. The results of the estimation of the minimum time required to ensure the uniform motion of the platoon progression allow us to state that for actual speeds and vehicle accelerations when starting from the stop-line of the intersection, the requirement for the uniform motion of the platoon progression is too strict, especially if we take into account that advance time will increase significantly as the number of additional vehicles in the queue increases. Originality. Analytical models created using formulas of the kinematics of rectilinear uniform accelerated motion of a point make it possible to estimate the minimum advance time of the start of the traffic light signal due to the deliberate speed of traffic and the average acceleration of one additional vehicle when starting from the stop-line of the intersection. Practical value. The developed models reflect the minimum value of the advance time, which ensures uniform motion of the platoon progression, provided that there is one additional vehicle at the stop-line of the intersection.

Spatially varying earthquake ground motion: artificial generation and effects on earth-fill dam behavior

ABSTRACT The observed amplitude and phase differences of seismic ground motions recorded at different locations over extended areas are termed as spatially varying earthquake ground motion (SVEGM). Earthquake-resistant design and seismic risk assessment of extended structures require three-dimensional dynamic analyses for which the excitation is needed in the form of three-directional SVEGM components, where each component needs to be consistent with the coherency model. In this paper, the principal features of the performed analyses are as follows: (1) discretisation of the spatial domain at the foundation base, (2) the selection of coherency model and (3) propagation angle of the seismic waves. In the first part of the paper, three cases for the generation of three-directional SVEGM are presented. First, the two-dimensional spatial domain, representing the foundation base of the extended structure, is discretised. Second, for case 1, the three-directional SVEGM is generated using the Liu and Hong coherency model at the cells of the grid. In this case, the loss of coherency is considered independent of the direction of the wave propagation (case general). Then, for the case 2, the two different propagation angles of 30 and 60 degrees of seismic waves and the Liu and Hong coherency model are considered. Finally, using the anisotropic coherency model of Hao et al. and the propagation angle 45 degree, the three-directional SVEGM is generated, in case 3. Results show that each component of the generated SVEGM records is affected by propagation angle and directional dependency of the coherency model. The second part of the paper is devoted to two-dimensional analyses of Marun earthfill dam and three-dimensional analyses of earthfill dams with different length-to-height ratios subjected to uniform input motion and artificially generated SVEGM.

«КИНЕМАТИКА» ТАРАУЫН ОҚЫТУДАҒЫ ӘДІСТЕР

Taimuratova Lidiya Ungarbaevna Candidate of Physical and Mathematical Sciences, Acting Associate Professor, Sh.Yessenov Caspian state university of technology and engineering, Aktau, Kazakhstan Almagambetova Aigul Aldazharovna Candidate of Pedagogical Sciences, senior lecturer, Korkyt Ata Kyzylorda University, Kyzylorda, Kazakhstan Shakimardan Nazerke Berdibekkyzy 2nd-year Master's student, MNFIZ-21, Korkyt Ata Kyzylorda University, Kyzylorda, Kazakhstan METHODS OF TEACHING THE CHAPTER «KINEMATICS» Abstract. In this article we will focus on new methods of teaching the chapters of «Kinematics» in the physics section «Mechanics». The teaching of this chapter says that with the help of interdisciplinary connections, students need to explain the most important physical parameters with problems that they use in life, in everyday life, in order to form elementary ideas. Physical quantities that measure any phenomena, things, it is desirable to solve with the help of problems. In addition, it is important to form the basic concepts by integrating the chapter of kinematics with mathematics. The concepts of kinematics begin with the chapter "movement" in the 7th grade. The main purpose of teaching the chapter "motion" is the formation of systematic ideas about mechanical motion, which is the simplest form of motion of matter. Since this chapter is considered more complex than the methodical one, it combines the knowledge gained in mathematics. When interpreting this chapter of kinematics, it is necessary that students have knowledge of the concept of vectors in mathematics. In connection with the introduction of the concepts of coordinates of a material point and displacement, the method of introducing the concepts of velocity and acceleration is determined. The body can move in space quickly or slowly. To describe the speed of change of the displacement vector, a special physical quantity is introduced – velocity. In grade 9, the concept of velocity is interpreted as a vector quantity. When repeating a uniform rectilinear motion, it stops at its main sign: a point of matter makes the same movements at any equal intervals of time. Students in most cases understand the average speed of uneven movement as the arithmetic mean of the initial and final speeds. This is done only for equidistant motion (linear dependence of speed on time). When teaching the chapter of kinematics, the most important issues are the units of measurement of physical quantities, such as speed, path, displacement, acceleration, and the use of formulas in solving problems. Using the internet to explain the chapter of kinematics, kahoot.it to facilitate the work of the teacher, to quickly and accurately assess the knowledge of students using the program, new technologies can be used. About students' understanding of the chapter of kinematics in this article, kahoot.it with the help of the program, knowledge was tested. Keywords: fundamentals of kinematics, mechanical motion, bodies, velocity, displacement, time, momentum, acceleration, vectors, program kahoot.it.

Constrained Large-Displacement Thermal Analysis

Abstract Two different cases are encountered in the thermal analysis of solids. In the first case, continua are not subject to boundary and motion constraints and all material points experience same displacement-gradient changes as the result of application of thermal loads. In this case, referred to as unconstrained thermal expansion, the thermal load produces uniform stress-free motion within the continuum. In the second case, point displacements due to boundary and motion constraints are restricted, and therefore, continuum points do not move freely when thermal loads are applied. This second case, referred to as constrained thermal expansion, leads to thermal stresses and its study requires proper identification of the independent coordinates which represent expansion degrees-of-freedom. To have objective evaluation and comparison between the two cases of constrained and unconstrained thermal expansion, the reference-configuration geometry is accurately described using the absolute nodal coordinate formulation (ANCF) finite elements. ANCF position-gradient vectors have unique geometric meanings as tangent to coordinate lines, allowing systematic description of the two different cases of unconstrained and constrained thermal expansions using multiplicative decomposition of the matrix of position-gradient vectors. Furthermore, generality of the approach for large-displacement thermal analysis requires using the Lagrange–D'Alembert principle for proper treatment of algebraic constraint equations. Numerical results are presented to compare two different expansion cases, demonstrate use of the new approach, and verify its results by comparing with conventional finite element (FE) approaches.

Extension of Galilean invariance to uniform motions for a relativistic equation of fluid flows

Galilean invariance and the Lorentz transformation are the two pillars of mechanics that an equation of motion must respect. The objective is to extend the Galilean invariance to uniform rotational motion and to expansion motion of which motion at constant translational velocity is only a special case. The second goal is to show that the discrete equation of motion is naturally relativistic without using the Lorentz transformation. The realization of these two aims leads to different concepts of special relativity: (i) space is homogeneous and isotropic and (ii) time, which flows regularly, is invariant by translation. These invariances, symmetric for translation and rotation, observed by the discrete equation of motion give it fundamental conservation properties to extend the scope of the equations of fluid mechanics to other fields of physics.

Thermo-fluidic transport process in magnetohydrodynamic Couette channel containing hybrid nanofluid

Current paper focusses on the mathematical simulation of thermo-fluidic unsteady flow in a magnetohydrodynamic (MHD) Couette channel containing novel (ZnO–Al2 O3)-water hybrid nanofluid (HNF). The nanoparticles of zinc oxide(ZnO) and aluminium oxide(Al2O3) are supplemented to basefluid water in 1:1 ratio. The bottom wall of channel kept stationary and stretchable, while the top is set in uniform motion with convective cooling. A uniform magnetic field appealed normally to lower plate. The governed nonlinear partial differential equations(PDE) are integrated employing finite difference method (FDM). A comparison of effect of hybrid nanofluid versus nanofluid (NF) is performed. The effects of non-dimensional quantities namely, nanoparticle volume fraction(NVF), magnetic field, stretching parameter, Biot number and Eckert number are reported graphically. The results demonstrate that (ZnO+ Al2O3)-water HNF shows significant impact over ZnO–water NF on velocity and temperature in the Couette channel.

Concept Mastery and Mathematical Problem Solving Ability of High School Students in Uniform Motion in a Straight Line Materials (GLBB)

This study aims to describe the pattern of the relationship between students concept mastery and mathematical problem-solving ability in GLBB material. This is qualitative associative/constructive research. This investigation was conducted with grade X MIA2 students at SMAN 1 Nita. This study's instrument included a test of concept mastery and mathematical problem-solving ability, documentation of student answer sheets, and unstructured interviews. The technique for data analysis consisted of five stages: data collection, description of raw data, data reduction, data categorization, and construction of category relationships. The findings revealed a reciprocal relationship between concept mastery and mathematical problem-solving ability. In addressing physics problems, mastery of concepts and mathematical problem-solving ability play mutually reinforcing roles. The level of concept mastery of students increases with their problem-solving abilities, and vice versa: the higher the level of conceptual mastery, the greater the mathematical problem-solving abilities. The results showed that there was a semantic congruence between issue solving using the Polya step indicator and problem solving at the levels of analyzing (C4), evaluating (C5), and creating (C6).
 Keywords : GLBB, Concept Mastery, Mathematical Problem Solving Ability

Two second order instantaneous invariants of axodes

It is well established that generalized spatial motion of a rigid body can be defined in terms of two axodes; a fixed axode and a moving axode. These axodes are ruled surfaces that uniquely roll and slide upon one another. Presented are two instantaneous invariants that define relative motion between two axodes. These invariants are based on the instantaneous screw axis (ISA) or line-tangency shared by two axodes in mesh. One invariant is the relative angular displacement (rolling) about the ISA and the other invariant is the relative axial displacement (sliding) along the ISA. Both invariants are ratios expressed in terms of the normal curvature and geodesic torsion for any point on the ISA. An induced curvature is introduced to quantify the combined rolling and sliding displacement. Two osculating hyperboloids are established in terms of induced curvature, which when combined, create a skew axis gear pair with uniform motion that matches the instantaneous invariants of the axodes. A skew axis gear set with elliptical motion is presented to demonstrate generalized axodes, instantaneous invariants, induced curvature, and osculating hyperboloids.

Graphical analysis of an oscillator with constant magnitude sliding friction

We treat a horizontal oscillator damped by constant-magnitude sliding friction by extending the analogy between the simple harmonic motion of a mass on a spring and the uniform circular motion of a mass attached to the end of a string. In the presence of sliding friction, the motion of the mass on a spring becomes the horizontal projection of the path of a mass attached to a string winding around two nails separated by a well-defined distance; this path is a spiral consisting of connected semi-circles of diminishing radii. This graphical analysis is very simple and pedagogically useful. It can also be generalized to any oscillation affected by other forces of constant magnitude but not necessarily constant direction.

КООРДИНАЦІЯ АНТИ-КОЛІЗІЙНИХ ДІЙ СУДЕН

The mechanisms of coordination of anti-collision measures of ships are systematized and analyzed. The main of these mechanisms is COLREG, which regulates the actions of two vessels. It is shown that non-regulated coordination used in addition to COLREG is based on the standardized qualification of ship operators and includes knowledge of good seamanship recommendations. In the analysis of mechanisms of binary coordination, the classification of situations of ships' approach is clarified, and principles of a choice of actions general for ships of the same and different navigation statuses in free and constrained waters at normal visibility are highlighted. Ways of reception of numerical values of restrictions on parameters of passing targets in different sailing conditions are offered. It is noted that in order to solve the problem of automation of collision prevention processes, radar-AIS technologies should be supplemented with video camera technologies in the visible and infrared range combined with computer vision. The role of communication in vessel actions coordination has been analyzed. Proposals for its improvement given the achievements in the field of scientific and technological progress are elaborated. It is recommended to use AIS alerts of planned evasive trajectory to decrease uncertainty in the collision prevention process. To reduce the volume of these notifications, it is proposed to replace the segments of changes in motion parameters with time-equivalent segments of rectilinear uniform motion sections. It gets rid of transmitting data characterizing the manoeuvrability of a ship and planned modes of course or/and speed change, and practically does not worsen the assessment of the safety of the measures selected to avoid a collision. The received information allows the ship to present the trajectory of the giving way vessel on the screen in graphical form, both in true and relative motion. Using this capability allows the first ship to quickly assess the safety of the second vessel's planned operations. Keywords: collision avoidance, coordination mechanisms, anti-collision plans, mapping of evasive trajectories.

A Framework for Distributed LEO SAR Air Moving Target 3D Imaging via Spectral Estimation

This paper aims to perform imaging and detect moving targets in a 3D scene for space-borne air moving target indication (AMTI). Specifically, we propose a feasible framework for distributed LEO space-borne SAR air moving target 3D imaging via spectral estimation. This framework contains four subsystems: the distributed LEO satellite and radar modeling, moving target information processing, baseline design framework, and spectrum estimation 3D imaging. Firstly in our method, we develop a relative motion model between the satellite platform and the 3D moving target for satellite and radar modeling. In a very short time, the relative motion between the platform and the target is approximated as a uniform motion. We then establish the space-borne distributed SAR moving target 3D imaging model based on the motion model. After that, we analyze the influencing factors, including the Doppler parameters, the three-dimensional velocity, acceleration, and baseline intervals, and further investigate the performance of the 3D imaging of the moving target. The moving target spectrum estimation 3D imaging finally obtains the 3D imaging results of the target, which preliminarily solves the imaging and resolution problems of slow air moving targets. Simulations are conducted to verify the effectiveness of the proposed distributed LEO space-borne SAR moving target 3D imaging framework.

Motion parameter estimation of AUV based on underwater acoustic Doppler frequency measured by single hydrophone

This paper describes the use of a single hydrophone to estimate the motion parameters of an autonomous underwater vehicle (AUV) from the underwater acoustic signal excited by its propulsion motor. First, the frequency range of the hydroacoustic signal radiated by the AUV motor is determined, and a detection and recognition model is designed. In the case of uniform linear motion of the AUV, the geometric relationship between the Doppler frequency shift curve of the sound source is derived and the motion model of the sound source and sound line propagation is established. An estimation algorithm for the motion parameters of multiple AUVs based on data from a single hydrophone is derived. Then, for Doppler underwater acoustic signals disturbed by independent identically distributed noise with an arbitrary probability distribution, a cumulative phase difference power amplification instantaneous frequency estimation method is proposed. This method is based on the sum of multiple logarithmic functions. Finally, the effectiveness and accuracy of the algorithm in estimating the motion parameters of multiple AUVs are verified through simulations and experiments.

An Efficient Method for Calculating the Doppler Spectrum of an Arbitrarily Shaped Object in Uniform Motion

In the article, an efficient numerical method for calculating the spectrum of the scattering fields of an arbitrarily shaped object in uniform motion is proposed. This method relies on the frame hopping technique stemming from the special theory of relativity (STR). Firstly, the incident monochromatic plane wave is transformed to the comoving inertial frame in which the object is stationary. Next, the scattering fields of the moving object at the sampling time points are obtained in the comoving frame by solving the electromagnetic (EM) scattering problem with the conventional numerical method in the frequency domain. Then, the spectrum of the scattering fields in the frame in which the observer remains stationary is obtained using the discrete Fourier transform (DFT). The asymptotic expressions for the scattering fields when the moving object is far away from the observation point are derived, by applying which the computation efficiency could be greatly improved.