Problem Of Motion Research Articles

USAGE OF CONSTRUCTION-ORIENTED SOFTWARE SCAD FOR ANALYSIS OF WORK OF MACHINE-BUILDING STRUCTURES

Purpose. In the case of analysis of work of the machine-building structures, the direct usage of construction-oriented software developments is impossible, since ideology and methodology for solving various tasks in construction and machine-building are different. Therefore, in the conducting of practical calculations, there is a need for a certain adjustment of the approaches put in the program complexes and their adaptation to the engineering industry. The presentation of the author's experience of the construction-oriented software SCAD usage for Windows for analyzing the work of various machine-building structures, their components and assemblies is the immediate purpose of the publication. Methodology. During a long period of time the author was engaged in analyzing the work of building, mainly thin-walled, steel structures using the Finite Element Method based on the SCAD for Windows software package. At the same time, a considerable number of machine-building structures were considered, including railroad rolling stock units. Most of these tasks grew into a scientific and research problem that needed to be thoroughly researched and analyzed before giving design recommendations. Findings. The publication presents more than a dozen different tasks, typical for the machine-building industry, which the author had to deal with. Static and quasi-static problems, the problem of motion in time, the contact problem, the problem of the cracks deve-lopment, the physical and geometric non-linearity are among them. Accordingly, for each of these problems the main challenges, features and practical techniques developed during the work are presented, as well as the constructed finite element models are presented as an illustration. Originality. The experience of construction-oriented software product usage on the basis of the Finite Element Method for analyzing of the work of machine-building structures is generalized. A number of practical methods and approaches to the solution of various problems in the machine-building sphere are set forth. Practical value. The application of the given information, methods and approaches allows not only to solve concrete practical problems of the machine-building sphere, but also to obtain correct and practically acceptable solutions.

VIBRATIONS OF AN INSTANTLY LOADED DISSIPATIVE OSCILLATOR

The work investigates non-stationary oscillations of dissipative oscillators. The joint influence of resistance forces of different nature in the composition of the dissipative force on the oscillations of an elastic linear oscillator caused by its instantaneous loading by a constant external force is investigated. The work was limited to the case of small displacements, when the elastic characteristic of the system can be considered linear. The problem is nonlinear due to the account of the action of the dry friction force, but it allows the construction of exact analytical solutions in elementary functions. In this work, by the method of adding solutions, formulas are derived for calculating the amplitude of oscillations and the duration of half cycles. First, a variant is considered when the resistance force consists of linear viscous and dry friction forces. Then a generalization is made to the case of three resistance forces. The third force is the force of positional friction, which arises in elastic elements such as a leaf spring. It is shown that as a result of the action of the total resistance force, the oscillatory process of a loaded oscillator has a finite number of cycles and is limited in time, which is usually observed in practice. The system dynamic factor is less than two. Examples of calculations that illustrate the possibilities of the stated theory are considered. To check the adequacy of the derived calculation formulas, numerical computer integration of the nonlinear differential equations of the oscillator motion was additionally carried out. The full agreement of the numerical results obtained using various methods is shown. In addition to direct problems of dynamics, the inverse problems of determining the characteristics of the load and resistance from the results of measuring the amplitude of oscillations are also considered. The derived calculation formulas are also suitable for identifying the characteristics of the load and resistance based on the results of experimental measurements of the oscillation ranges. Examples of identifying these characteristics are given. The study showed that the nonlinear problem of motion of an instantly loaded oscillator with the total resistance of several forces of different nature has an analytical solution in elementary functions. The presence of such resistance significantly affects the motion of the oscillator after loading. The constructed analytical solutions give results such as the numerical integration of the original nonlinear differential equation on a computer, which confirms the adequacy of the formulas obtained.

Vibration of general symmetric systems using group theory

This work presents group-theory-based vibration analysis to determine the highly structured, symmetry-related modal properties of symmetric systems and classify them into specific types. No eigenvalue problem solutions are required. In fact, the properties are obtained without a mathematical model. They derive only from symmetry and the degrees of freedom chosen to describe the deformation. Dynamic or static response is similarly decomposed into the sum of multiple response components associated with the mode types. One knows a priori, without any numerical computation, which mode types can or can not be excited by a given input excitation. Group theory divides the full system equations of motion and eigenvalue problem into multiple, smaller, decoupled problems associated with each mode type, which is computationally efficient. The method applies for general three-dimensional systems having any type of symmetry where components of the system are modeled using any mixture of lumped-parameter (including finite element) and elastic continuum models. Only basic elements of group theory are required, and they are introduced. Among three examples of the method, one derives the modal properties for general cyclically symmetric systems having any number of central components and substructures that can be modeled as any of rigid bodies, finite element meshes, and elastic continua.

Control of reference orbit using wire position sensor for X-ray free electron laser

We present a method to control the reference orbit of the undulator line using the 2D wire position sensor (WPS) to maintain the FEL intensity circumventing the ground motion problem. The WPS data shows that FEL intensity variation during the user beamtime is closely related to the undulator hall ground motion. We successfully demonstrated that the correction method could recover the FEL intensity, not interrupting the user beamtime.

Application of rotating coupling time‐step finite element method in synchronous generators’ internal faults simulation

A precise simulation of the internal faults of synchronous generators is very important for designing the main protection scheme; therefore, it is necessary to propose an accurate model. The time-step finite element method is quite qualified for analysing problems related to the transient electromagnetic field, including the internal faults of synchronous generators. This paper presents a new time-step method, which employs a rotation coupling technique to handle rotor motion. By using this technique, the rotor remains stationary during the process of the simulation, and the motion problem becomes simple and can be conveniently implemented with a programming process. Simulation and experimental results for the internal faults of an experimental machine are compared to verify the accuracy of the rotation coupling time-step method. Moreover, a 300 MW salient pole synchronous generator is used as an example, and the transient process of this generator during internal faults is simulated. The air gap flux density, fault currents, damper windings eddy current losses, and core dynamic electromagnetic force are investigated in detail to reveal the fault characteristics more clearly and provide a basis for designing protection schemes.

Endogenous assessment of myocardial injury with single-shot model-based non-rigid motion-corrected T1 rho mapping

BackgroundCardiovascular magnetic resonance T1ρ mapping may detect myocardial injuries without exogenous contrast agent. However, multiple co-registered acquisitions are required, and the lack of robust motion correction limits its clinical translation. We introduce a single breath-hold myocardial T1ρ mapping method that includes model-based non-rigid motion correction.MethodsA single-shot electrocardiogram (ECG)-triggered balanced steady state free precession (bSSFP) 2D adiabatic T1ρ mapping sequence that collects five T1ρ-weighted (T1ρw) images with different spin lock times within a single breath-hold is proposed. To address the problem of residual respiratory motion, a unified optimization framework consisting of a joint T1ρ fitting and model-based non-rigid motion correction algorithm, insensitive to contrast change, was implemented inline for fast (~ 30 s) and direct visualization of T1ρ maps. The proposed reconstruction was optimized on an ex vivo human heart placed on a motion-controlled platform. The technique was then tested in 8 healthy subjects and validated in 30 patients with suspected myocardial injury on a 1.5T CMR scanner. The Dice similarity coefficient (DSC) and maximum perpendicular distance (MPD) were used to quantify motion and evaluate motion correction. The quality of T1ρ maps was scored. In patients, T1ρ mapping was compared to cine imaging, T2 mapping and conventional post-contrast 2D late gadolinium enhancement (LGE). T1ρ values were assessed in remote and injured areas, using LGE as reference.ResultsDespite breath holds, respiratory motion throughout T1ρw images was much larger in patients than in healthy subjects (5.1 ± 2.7 mm vs. 0.5 ± 0.4 mm, P < 0.01). In patients, the model-based non-rigid motion correction improved the alignment of T1ρw images, with higher DSC (87.7 ± 5.3% vs. 82.2 ± 7.5%, P < 0.01), and lower MPD (3.5 ± 1.9 mm vs. 5.1 ± 2.7 mm, P < 0.01). This resulted in significantly improved quality of the T1ρ maps (3.6 ± 0.6 vs. 2.1 ± 0.9, P < 0.01). Using this approach, T1ρ mapping could be used to identify LGE in patients with 93% sensitivity and 89% specificity. T1ρ values in injured (LGE positive) areas were significantly higher than in the remote myocardium (68.4 ± 7.9 ms vs. 48.8 ± 6.5 ms, P < 0.01).ConclusionsThe proposed motion-corrected T1ρ mapping framework enables a quantitative characterization of myocardial injuries with relatively low sensitivity to respiratory motion. This technique may be a robust and contrast-free adjunct to LGE for gaining new insight into myocardial structural disorders.

On a hyperbolic system of equations in the problem of unsteady fluid motion

We consider a nonlinear system of the first-order partial differential equations with constant coefficients admitting a solution of the traveling wave type. Such systems are used in applied research to describe the dynamics of unsteady water movement in a pressure pipeline. In this paper, we propose methods for obtaining exact solutions in the case of an inhomogeneous equation of fluid motion under restrictions on the right-hand side in the form of a function. A special feature of the present research is reduction of the problem under study to the equations integrable in elementary functions.

Optimization of Spraying Process in Thermal Power Plant using Robot

To synthesize the surface of the metal bodies, a thermal spray coating is used. There is a great need for this new coating technology in today's progressive world where modification of the substrate material is carried out a great deal. Thermal spray covering, electroplating, powder metallurgy and other metallurgical processes are used very quickly in the field of surface modification. We have presented the summary of all different types of thermal spray coating in this review paper and the advantages of high-speed oxy fuel coating. There is a literature review and an experiment was conducted on behalf of that to demonstrate the effect of coating on mild steel plate. Through Robot, we present a proposed optimization of the spraying process in a thermal power plant. We will explore the thermal spraying and oxidation effect on deposited aluminium and bronze in this research work. We present a detailed assessment of the robot kinematics and optimize the generation of the robot trajectory with a focus on the constant relative scanning speed. The results show that the motion behavior of each axis of robot permits to identify the motion problems in the trajectory. This approach enables the generation of robot trajectories in a limited working envelope to be optimised.

Performance comparison of two motion modes of a piezoelectric inertial linear motor and its potential application in cell manipulation

The piezoelectric inertial linear motor (PILM) has great application potential in cell manipulation, location of artificial neural electrode, and other micro-operation fields for its advantages of fast response, long stroke, and high resolution. However, the traditional schemes have been challenging to avoid the phenomenon of backward motion, which may lead to motion instability and failure of positioning in cell manipulation. To solve this problem, a novel PILM with two motion modes is proposed. In this study, throughin-depthanalysis of steppingcharacteristics, the reason why the motor with the traditional “forward–backward” motion mode is difficult to eliminate the backward motion phenomenon by adjusting the friction force in experiments is revealed. Then, a series of performance evaluation and cell manipulation simulation experiments are carried out. Experimental results indicate that the novel “forward–forward” motion mode can solve the backward motion problem and has the advantages of the speed, efficiency, and stability of the system, while the “forward–backward” motion mode has the advantages of resolution and carrying capacity. Moreover, the proposed motor can switch between the two motion modes freely according to the different requirements of the application environment for obtaining the required specific performance. Based on the above advantages and the successful druginjection simulation process in a zebrafishembryo, the proposed motor has great application potential in cell manipulation and other micromanipulation fields.

Large amplitude inversion tunneling motion in ammonia, methylamine, hydrazine, and secondary amines: From structure determination to coordination chemistry

• Molecular structures of ammonia derivatives captured by spectroscopy. • Tunneling motion as essential information to understand coordination complexes. • Structures and internal dynamics from experimental and theoretical points of view. • Using the structures of isolated ligand to determine the structure of complexes. Inversion tunneling in a symmetric double minimum potential is a challenging large amplitude motion problem which causes all rotational energy levels to split into a symmetric and an antisymmetric level. Not like other types of large amplitude motion such as internal rotation, inversion tunneling appears much rarer, but the fundamental knowledge gained from this motion is essential to understand the complex structures in coordination chemistry. A double minimum potential needed for inversion tunneling requires the symmetry of the frame to which the inversion object is attached to be C s or higher, while there is no restriction on the symmetry of the frame for internal rotation. This review summarizes four most classic examples of molecules featuring inversion tunneling motion and their coordination complexes. The textbook example, ammonia, with its umbrella motion during which the nitrogen atom passes from one side of the plane formed by the three hydrogens to the other, will be presented with information on its group theoretical considerations, theoretical studies, electronic ground state spectra in the infrared range, and its coordination complexes, especially those formed with calcium and copper. In the second classic example, methylamine, CH 3 NH 2 , the inversion motion of the amino group –NH 2 is coupled with a methyl internal rotation –CH 3 . The spectrum of methylamine can be treated using a tunneling formalism applying the G 12 permutation-inversion symmetry group. Extensive studies on the ground state, the first and second excited torsional states ν 15 , the inversion wagging state ν 9 , and the C-N stretching band ν 8 exist along with their combinations. Pertubations and blends have made the analysis of methylamine very challenging. The third subject is on hydrazine with complex internal dynamics governed by three large amplitude motions: two –NH 2 tunneling motions and an internal rotation (torsion) of the two amino groups around the N-N bond. Regarding the spectrum of hydrazine, the vibrational ground state lies in the microwave region. The first, second, and third excited torsional band ν 7 , symmetric wagging ν 6 , and asymmetric wagging ν 12 are found in the infrared range. Group theoretical treatment and tunneling formalism can only be used to fit sub-bands individually, while global fits still remain a difficult task. Metal complexes with hydrazine and methylamine are introduced, proving the importance of spectroscopic understanding of molecular structures for the knowledge of coordination chemistry. Finally, secondary amines feature inversion tunneling of the hydrogen atom attached to the nitrogen, which is accompanied by two methyl internal rotations but not coupled with them so that they can be treated separately. For this class of molecules, only spectra of the vibrational ground state in the microwave domain will be considered.

Breakdown of quantum-to-classical correspondence for diffusion in a high-temperature thermal environment

We re-consider the old problem of Brownian motion in homogeneous high-temperature thermal environment. The semiclassical theory implies that the diffusion coefficient does not depend on whether the thermal fluctuations are correlated in space or disordered. We show that the corresponding quantum analysis exhibits a remarkable breakdown of quantum-to-classical correspondence. Explicit results are found for a tight binding model, within the framework of an Ohmic master equation, where we distinguish between on-site and on-bond dissipators. The breakdown is second-order in the inverse temperature, and therefore, on the quantitative side, involves an inherent ambiguity that is related to the Ohmic approximation scheme.

Feedback Control Problem for Modified Kelvin-Voigt Model

This paper deals with the optimal feedback control problem for the modified Kelvin-Voigt model. The considered model describes the motion of weakly concentrated aqueous polymer solutions. In our case, the control function (the external force) depends on the velocity of the fluid. In such a way, the control is not selected from a finite set of available controls, but belongs to the image of some multi-valued map. The solution for the control problem of fluid motion is a pair: the velocity of the fluid and the control (the density of external forces). Since there can be many such pairs, the concept of optimal solution naturally arises, which gives a minimum to specified cost functional. For the considered optimal feedback control problem the existence theorem on weak solution is proved.

On New Modifications of Some Perturbation Procedures

In this paper, we present new modifications for some perturbation procedures used in mathematics, physics, astronomy, and engineering. These modifications will help us to solve the previous problems in different sciences under new conditions. As problems, we have, for example, the rotary rigid body problem, the gyroscopic problem, the pendulum motion problem, and other ones. These problems will be solved in a new manner different from the previous treatments. We solve some of the previous problems in the presence of new conditions, new analysis, and new domains. We let complementary conditions of such studied previously. We solve these problems by applying the large parameter technique used by assuming a large parameter which inversely proportional to a small quantity. For example, in rigid body dynamic problems, we take such quantity to be one of the components of the angular velocity vector in the initial instant of the rotary body about a fixed point. The domain of our solutions will be depending on the choice of a large parameter. The problem of slow (weak) oscillations is considered. So, we obtain slow motions of the bodies instead of fast motions and find the solutions of the problem in present new conditions on both of center of gravity, moments of inertia, and the angular velocity vector or one of these parameters of the body. This study is important for aerospace engineering, gyroscopic motions, satellite motion which has the correspondence of inertia moments, antennas, and navigations.

Energy-optimal trajectory problems in relative motion solved via Theory of Functional Connections

In this paper, we present a new approach for solving a broad class of energy-optimal trajectory problems in relative motion using the recently developed Theory of Functional Connections (TFC). A total of four problem cases are considered and solved, i.e. rendezvous and intercept with fixed and free final time. Each problem is constrained and formulated using an indirect approach which casts the optimal trajectory problem as a system of linear or nonlinear two-point boundary value problems for the fixed and free final time cases, respectively. Using TFC, we convert each two-point boundary value problem into an unconstrained problem by analytically embedding the boundary constraints into a “constrained expression.” The latter includes a free-function that is expanded using Chebyshev polynomials with unknown coefficients. Regardless of the values of the unknown coefficients, the boundary constraints are satisfied and simple optimization schemes can be employed to numerically solve the problem (e.g. linear and nonlinear least-square methods). To validate the proposed approach, the TFC solutions are compared with solutions obtained via an analytical based method as well as direct and indirect numerical methods. In general, the proposed technique produces solutions to machine level accuracy. Additionally, for the cases tested, it is reported that computational run-time within the MATLAB implementation is lower than 28 and 300 ms for the fixed and free final time problems respectively. Consequently, the proposed methodology is potentially suitable for on-board generation of optimal trajectories in real-time.

Journal of Siberian Federal University. Mathematics &amp; Physics

The aim of this work is to find approximate analytic solution of the problem of granular medium motion in a convergent channel, to develop computational algorithm based on the finite element method, and to carry out numerical calculations of the problem

ANALISIS TINGKAT BERPIKIR DALAM MENYELESAIKAN SOAL GERAK PARABOLA MENGGUNAKAN TAKSONOMI STRUCTURE OF THE OBSERVED LEARNING OUTCOMES (SOLO) SISWA KELAS X MIA SMAN 1 SUNGAI RAYA

This This study aims to describe the level of students’ thinking profilein solving parabolic motion problems based on the SOLO taxonomy seen from learning outcomes and gender. This is a survey research without a comparison group. Data collection was done by giving 4 questions to 95class X MIA students at SMAN 1 Sungai Raya, and categorized based on learning outcomes (high, medium, low) and gender (male, female). The level ofstudents’ thinking profile in solving parabolic motion problems based on SOLO taxonomyis 50.52% at the pre-structural level, 11.57% at the uni-structural level, 21.05% at the multi-structural level, 16.84% at relational level , and0% at extended-abstract level. Additionally, students with high learning outcomes reached the uni-structural-relational thinking level, while moderate ones reached the uni-structural-multi-structural level, and low ones reached the uni-structural-pre-structural level. In terms of gender,female students' average percentage of thinking level is 44.2% higher than male students with only 33.6% of the ideal score.Keywords: Thinking Level, SOLO Taxonomy, Parabolic Motion.

Investigating the Effects of Bed Roughness on Incipient Motion in Rigid Boundary Channels with Developed Hybrid Geno-Fuzzy versus Neuro-Fuzzy Models

In present study, the comprehension of different types of bedforms generated by different bed roughness, in rectangular and circular cross-sectional rigid boundary channels and the resistance generated by the bed roughness against the flow are evaluated. Moreover, the critical condition of sediment motion under bed roughness influence is investigated. This study presents novel contributions in solving engineering problems that suffer from the lack of knowledge on the incipient motion of sediment particles in rigid boundary channels under bed roughness effects. Furthermore, soft computing and evolutionary computation methods have been combined to develop a new novel predictive model. The Evolutionary GENOFIS also aims at improving the ANFIS tool depends on Sugeno Fuzzy Inference System. The advantages of the proposed hybrid GENOFIS approach over the ANFIS tool is its novel ability to tackle the incipient prediction problem by using less fuzzy based rules and to represent the consequent part of the model as a constant, linear or non-linear function as well as with possible simultaneous combinations of them. For validation and comparison purposes, model performances of hybrid GENOFIS, ANFIS and data-based linear regression approaches are evaluated via experimental data partitioned for testing purposes. The model results are compared through corresponding RMSE and CE values. It is found that the hybrid GENOFIS model results outperformed the ANFIS and linear regression models. Consequently, novel experimental data-driven incipient motion formula and the hybrid GENOFIS approach are proposed to modeling complex incipient motion problems that are full of uncertainty and complication.

Flocking motion in swarms with limited sensing radius and heterogeneous input constraints

This paper addresses the flocking motion problem for swarms of agents with two restrictions: limited communication/detection ranges and different input constraints. In this problem, the distance between pairs of agents determines if a communication/detection link exists among them, while each agent has a different control action bound. We use the notion of proximity graph to model communication/detection between agents and provide distributed controllers designed for leaderless and leader-followers flocking motion scenarios. Our proposed designs preserve the connectivity of the proximity graph while the control effort satisfies the bound of each particular agent. Unlike previous results, our protocols take advantage of the group’s input heterogeneity to use agents with a greater capacity to compensate for neighbors that are less capable of meeting the group’s requirements. Additionally, our designs are based only on local state errors and are robust to non-modeled edge failures. To illustrate the effectiveness of our proposal, we use numerical simulations of different flocking scenarios.

Safety Analysis of the Running Train under Earthquake Dynamic Disturbance

Focusing on the safe operation of rail transit during earthquakes, the finite element method is used to construct a wheel-track-subgrade dynamics model in this study. Through spring-damper units, the relationship between the rail and the track slab and the connection between the track slab and the subgrade are established. A method for establishing a viscoelastic artificial boundary is proposed. Four seismic waves—the Tianjin wave, the El Centro wave, the Taft wave, and the Qian’an wave—are selected as the seismic input waveforms, and only the impact of the lateral ground motion on the wheel-track-subgrade system is considered. In this paper, the ground motion problem is transformed into a wave source problem, the seismic input is transformed into an equivalent load acting on the artificial boundary, and the wave input of the viscoelastic artificial boundary is realized. The normalization method is used to process the seismic waves, and a method that converts the input of the seismic waves into equivalent loads is proposed. The changing laws of different dynamic response indexes under the influence of the four waveforms are studied. Under the action of the Tianjin wave, the wheel-rail dynamic response is very violent near the acceleration peak, whereas, after the peak, all dynamic response indexes are within a safe range. Under the effect of the El Centro wave, the collision between the wheel and the track is relatively violent, and the train is already in a dangerous state. Under the action of the Taft wave, due to the sudden action of the peak ground motion acceleration, the displacement between the wheel and the track increases instantaneously, causing the train to derail. Under the action of the Qian’an wave, the force between the wheel and rail changes approximately linearly with respect to the frequency of the ground motion, and all dynamic response indexes are within a safe range. The vibration intensity of the four seismic waves is amplified by an intensity expansion factor. Except for the Tianjin wave, the amplified seismic wave has a greater impact on safe train operations. This paper can provide a reference for research on the running safety of trains under similar dynamic disturbance conditions.

The periodic rotary motions of a rigid body in a new domain of angular velocity

In the previous works, the limiting case for the motion of a rigid body about a fixed point in a Newtonian force field, which comes from a gravity center lies on Z-axis, is solved. The authors apply the small parameter technique which is achieved giving the body a sufficiently large angular velocity component ro about the fixed z-axis of the body. The periodic solutions of motion are obtained in neighborhood ro tends to infty. In our work, we aim to find periodic solutions to the problem of motion in the neighborhood of r0 tends to 0. So, we give a new assumption that: ro is sufficiently small. Under this assumption, we must achieve a large parameter and search for another technique for solving this problem. This technique is named; a large parameter technique instead of the small one well known previously. We see the advantage of the new technique which appears in saving high energy used to begin the motion and give the solution of the problem in another domain. The obtained solutions by the new technique depend on ro. We consider that the center of mass of this body does not necessarily coincide with the fixed point O. We reduce the six nonlinear differential equations of the body and their three first integrals to a quasilinear autonomous system of two degrees of freedom and one first integral. We solve the rational case when the frequencies of the generating system are rational except (,omega = ,1,,2,1/2,3,1/3, ldots ) under the condition gamma^{primeprime}_{0} = cos theta_{o} approx 0. We use the fourth-order Runge–Kutta method to find the periodic solutions in the closed interval of the time t and to compare the analytical method with the numerical one.