The Influence of a Torus Shaped Auto-Equalizer on the Vibrations of Rotary Systems

2015 ◽  
Vol 220-221 ◽  
pp. 97-103
Author(s):  
Guntis Strautmanis ◽  
Vadim Jurjev ◽  
Ivans Grinevich
Keyword(s):  
Mathematical Model ◽  
Experimental Research ◽  
Crucial Role ◽  
Rotation Axis ◽  
Tangential Force ◽  
Vertical Axis ◽  
The Body ◽  
Resistance Force ◽  
Ball Motion ◽  
Motion Mode

Rotary systems are frequently used in different kinds of machines and devices, and therefore the problem of vibrations observed in rotary systems play a crucial role. The article analyses a ball-shaped auto-equalizer with a vertical axis the body of which is placed relatively eccentric to the rotation axis. The auto-equalizer with a torus-shaped body contains one ball-shaped adjustment mass moving freely within the body of the auto-equalizer both in circularly and crosswise directions. This reduces resistance force in the ball motion mode to the minimum, and, at the same time, decreases the possibility of starting the auto-equalizer.Making the analysis of experimental research on the ball-shaped auto-equalizer has led to the conclusion that, along with the working mode when the ball stops relatively at the rotating body from the opposite to imbalance side, there is another mode when the ball is moving relatively continuously to the body of the auto-equalizer. It has been stated that the ball in the working mode is affected by forces trying to move it to the body of the auto-equalizer opposite to the imbalance. The closer is the ball to the optimum place the smaller is tangential force influencing the ball. A mathematical model for the auto-equalizer consisting of two differential equations has been developed.

scholarly journals On the complete radiation-diffraction problem and wave-drift damping of marine bodies in the yaw mode of motion

1998 ◽  
Vol 357 ◽  
pp. 289-320 ◽  
Author(s):  
STYRK FINNE ◽  
JOHN GRUE
Keyword(s):  
Rotation Axis ◽  
Diffraction Problem ◽  
Slow Motion ◽  
Vertical Axis ◽  
The Body ◽  
Floating Body ◽  
Slow Rotation ◽  
Wave Drift ◽  
Exciting Forces ◽  
Wave Drift Damping

The coupled radiation-diffraction problem due to a floating body with slow (time-dependent) rotation about the vertical axis in incoming waves is studied by means of potential theory. The water depth may be finite. First, the radiation problem is described. It is shown how the various components of the velocity potential may be obtained by means of integral equations. The first-order forces in the coupled radiation-diffraction problem are then considered. Generalized Haskind relations for the exciting forces and generalized Timman–Newman relations for the added mass and damping forces are deduced for bodies of arbitrary shape with vertical walls at the water line. The equation of motion is obtained, and the frequencies of the linear body responses superposed on the slow rotation are identified. Formulae for the wave-drift damping coefficients in the yaw mode of motion are derived in explicit form, and the energy equation is discussed. Computations illustrating the various aspects of the method are performed for two ships. The wave-drift damping moment is found to become positive in the present examples. When the rotation axis is moved far away from the body, the slow motion becomes effectively unidirectional, and results of the translational case are recovered.

The Meaning of Children's Poetry: A Cognitive Approach

2013 ◽  
Vol 6 (2) ◽  
pp. 127-142 ◽  
Author(s):  
Karen Coats
Keyword(s):  
Crucial Role ◽  
The Body ◽  
Critical Discourse ◽  
Holding Environment ◽  
Cognitive Poetics ◽  
Cognitive Approach ◽  
Communal Life ◽  
Clear Sense ◽  
Critical Attention ◽  
Children's Poetry

Critical attention to children's poetry has been hampered by the lack of a clear sense of what a children's poem is and how children's poetry should be valued. Often, it is seen as a lesser genre in comparison to poetry written for adults. This essay explores the premises and contradictions that inform existing critical discourse on children's poetry and asserts that a more effective way of viewing children's poetry can be achieved through cognitive poetics rather than through comparisons with adult poetry. Arguing that children's poetry preserves the rhythms and pleasures of the body in language and facilitates emotional and physical attunement with others, the essay examines the crucial role children's poetry plays in creating a holding environment in language to help children manage their sensory environments, map and regulate their neurological functions, contain their existential anxieties, and participate in communal life.

Analysis of the First Order and Slowly Varying Motions of an Axisymmetric Floating Body in Bichromatic Waves

2013 ◽  
Vol 135 (1) ◽  
Author(s):  
João Pessoa ◽  
Nuno Fonseca ◽  
C. Guedes Soares
Keyword(s):  
Vertical Cylinder ◽  
Vertical Axis ◽  
Second Order ◽  
The Body ◽  
Floating Body ◽  
Drift Motion ◽  
First Order ◽  
Motion Responses ◽  
Simple Geometry ◽  
Good Agreement

The paper presents an experimental and numerical investigation on the motions of a floating body of simple geometry subjected to harmonic and biharmonic waves. The experiments were carried out in three different water depths representing shallow and deep water. The body is axisymmetric about the vertical axis, like a vertical cylinder with a rounded bottom, and it is kept in place with a soft mooring system. The experimental results include the first order motion responses, the steady drift motion offset in regular waves and the slowly varying motions due to second order interaction in biharmonic waves. The hydrodynamic problem is solved numerically with a second order boundary element method. The results show a good agreement of the numerical calculations with the experiments.

Impact of Electric Vehicle Lateral Dynamics on the Battery Pack

2014 ◽  
Vol 590 ◽  
pp. 451-457
Author(s):  
Sen Nan Song ◽  
Fa Chao Jiang ◽  
Hong Shi
Keyword(s):  
Mathematical Model ◽  
Angular Acceleration ◽  
Simulation Software ◽  
The Body ◽  
Battery Pack ◽  
Vehicle Body ◽  
Rolling Motion ◽  
Rolling Angle ◽  
On The Road ◽  
The Mathematical Model

The present work is concerned with the rolling motion of the battery pack when EV travelling on the road. First McPherson suspension system was regarded as the research object with detailed analysis of its structural features and motion characteristics. Establish the mathematical model which could apply to calculating the rolling motion of the vehicle body. Through MATLAB/Simulink simulation software, we could calculate the rolling angle on passive suspension. On this basis, assume that the battery pack mounted on the vehicle body and make it passive connection and PID connection. When the body rolls, the battery pack will produce a certain angle then. Next establish the mathematical model to summarize the relationship between the two variables. Then we set the parameters and calculate the roll angle of battery pack in both cases for comparison. Simulation results show that road irregularities will make battery rotate an angle and PID controller can effectively reduce the angle, especially angular acceleration. This paper put forward a new idea that battery is connected with body by active control on EV, and proves the superiority in reducing the rolling angle.

Drift Forces on a Floating Body of Simple Geometry Due to Second Order Interactions Between Pairs of Harmonics With Different Frequencies

2009 ◽  
Author(s):  
Joa˜o Pessoa ◽  
Nuno Fonseca ◽  
C. Guedes Soares
Keyword(s):  
Vertical Cylinder ◽  
Vertical Axis ◽  
Second Order ◽  
The Body ◽  
Floating Body ◽  
Order Problem ◽  
Simple Geometry ◽  
The Mean ◽  
Order Quantities ◽  
Drift Forces

The paper presents an investigation of the slowly varying second order drift forces on a floating body of simple geometry. The body is axis-symmetric about the vertical axis, like a vertical cylinder with a rounded bottom and a ratio of diameter to draft of 3.25. The hydrodynamic problem is solved with a second order boundary element method. The second order problem is due to interactions between pairs of incident harmonic waves with different frequencies, therefore the calculations are carried out for several difference frequencies with the mean frequency covering the whole frequency range of interest. Results include the surge drift force and pitch drift moment. The results are presented in several stages in order to assess the influence of different phenomena contributing to the global second order responses. Firstly the body is restrained and secondly it is free to move at the wave frequency. The second order results include the contribution associated with quadratic products of first order quantities, the total second order force, and the contribution associated to the free surface forcing.

The physical basis of mollusk shell chiral coiling

2021 ◽  
Vol 118 (48) ◽  
pp. e2109210118
Author(s):  
Régis Chirat ◽  
Alain Goriely ◽  
Derek E. Moulton
Keyword(s):  
Mathematical Model ◽  
The Body ◽  
Symmetric Body ◽  
Model Organisms ◽  
Physical Interaction ◽  
Mechanical Forces ◽  
Hard Shell ◽  
Left Right Asymmetry ◽  
Development And Evolution ◽  
Mollusk Shell

Snails are model organisms for studying the genetic, molecular, and developmental bases of left–right asymmetry in Bilateria. However, the development of their typical helicospiral shell, present for the last 540 million years in environments as different as the abyss or our gardens, remains poorly understood. Conversely, ammonites typically have a bilaterally symmetric, planispiraly coiled shell, with only 1% of 3,000 genera displaying either a helicospiral or a meandering asymmetric shell. A comparative analysis suggests that the development of chiral shells in these mollusks is different and that, unlike snails, ammonites with asymmetric shells probably had a bilaterally symmetric body diagnostic of cephalopods. We propose a mathematical model for the growth of shells, taking into account the physical interaction during development between the soft mollusk body and its hard shell. Our model shows that a growth mismatch between the secreted shell tube and a bilaterally symmetric body in ammonites can generate mechanical forces that are balanced by a twist of the body, breaking shell symmetry. In gastropods, where a twist is intrinsic to the body, the same model predicts that helicospiral shells are the most likely shell forms. Our model explains a large diversity of forms and shows that, although molluscan shells are incrementally secreted at their opening, the path followed by the shell edge and the resulting form are partly governed by the mechanics of the body inside the shell, a perspective that explains many aspects of their development and evolution.

Numerical modelling of swirling momentumless turbulent wake dynamics

2018 ◽  
pp. 37-48
Author(s):  
Андрей Геннадьевич Деменков ◽  
Геннадий Георгиевич Черных
Keyword(s):  
Numerical Simulation ◽  
Mathematical Model ◽  
Mathematical Models ◽  
Equations Of Motion ◽  
Turbulent Wake ◽  
The Body ◽  
Jet Flows ◽  
Reynolds Stresses ◽  
Bodies Of Revolution ◽  
Averaged Equations

С применением математической модели, включающей осредненные уравнения движения и дифференциальные уравнения переноса нормальных рейнольдсовых напряжений и скорости диссипации, выполнено численное моделирование эволюции безымпульсного закрученного турбулентного следа с ненулевым моментом количества движения за телом вращения. Получено, что начиная с расстояний порядка 1000 диаметров от тела течение становится автомодельным. На основе анализа результатов численных экспериментов построены упрощенные математические модели дальнего следа. Swirling turbulent jet flows are of interest in connection with the design and development of various energy and chemical-technological devices as well as both study of flow around bodies and solving problems of environmental hydrodynamics, etc. An interesting example of such a flow is a swirling turbulent wake behind bodies of revolution. Analysis of the known works on the numerical simulation of swirling turbulent wakes behind bodies of revolution indicates lack of knowledge on the dynamics of the momentumless swirling turbulent wake. A special case of the motion of a body with a propulsor whose thrust compensates the swirl is studied, but there is a nonzero integral swirl in the flow. In previous works with the participation of the authors, a numerical simulation of the initial stage of the evolution of a swirling momentumless turbulent wake based on a hierarchy of second-order mathematical models was performed. It is shown that a satisfactory agreement of the results of calculations with the available experimental data is possible only with the use of a mathematical model that includes the averaged equations of motion and differential equations for the transfer of normal Reynolds stresses along the rate of dissipation. In the present work, based on the above mentioned mathematical model, a numerical simulation of the evolution of a far momentumless swirling turbulent wake with a nonzero angular momentum behind the body of revolution is performed. It is shown that starting from distances of the order of 1000 diameters from the body the flow becomes self-similar. Based on the analysis of the results of numerical experiments, simplified mathematical models of the far wake are constructed. The authors dedicate this work to the blessed memory of Vladimir Alekseevich Kostomakha.

Simulation of cancer treatment using the MATLAB SimBiology application

2021 ◽  
Vol 14 (3) ◽  
pp. 90-96
Author(s):  
Anastasia Goncharova ◽  
Maria Vil'
Keyword(s):  
Mathematical Model ◽  
Cancer Treatment ◽  
Interference Competition ◽  
The Body ◽  
Continuous Treatment ◽  
Constant Concentration ◽  
Application Package ◽  
The Mathematical Model ◽  
Cancerous Cells

The paper presents the implementation of the mathematical model of cancer taking into account interference competition and the model of continuous treatment with a constant concentration of the drug in the patient's blood. The implementation was carried out using the MATLAB SimBiology application package. The principle of implementation of different stages of the course of the disease within the framework of one model is described. On the basis of the constructed models and SimBiology tools, a modification was carried out that implements the discrete administration of doses of the drug in courses and takes into account its dynamics in the body, taking into account the assumption that the drug is consumed only to suppress cancerous cells.

Anticipatory weight shift between arms when reaching from a crouched posture

2021 ◽  
Author(s):  
Rosemary Gallagher ◽  
Stephaine Perez ◽  
Derek DeLuca ◽  
Isaac L. Kurtzer
Keyword(s):  
Body Weight ◽  
Muscle Activity ◽  
Force Plate ◽  
Vertical Axis ◽  
The Body ◽  
Reaching Movements ◽  
Reactive Control ◽  
Step Initiation ◽  
Weight Shift ◽  
The Many

Reaching movements performed from a crouched body posture require a shift of body weight from both arms to one arm. This situation has remained unexamined despite the analogous load requirements during step initiation and the many studies of reaching from a seated or standing posture. To determine whether the body weight shift involves anticipatory or exclusively reactive control we obtained force plate records, hand kinematics, and arm muscle activity from 11 healthy right-handed participants. They performed reaching movements with their left and right arm in two speed contexts - 'comfortable' and 'as fast as possible' - and two postural contexts - a less stable knees-together posture and more stable knees-apart posture. Weight-shifts involved anticipatory postural actions (APA) by the reaching and stance arms that were opposing in the vertical axis and aligned in the side-to-side axis similar to APAs by the legs for step initiation. Weight-shift APAs were correlated in time and magnitude, present in both speed contexts, more vigorous with the knees placed together, and similar when reaching with the dominant or non-dominant arm. The initial weight-shift was preceded by bursts of muscle activity in the shoulder and elbow extensors (posterior deltoid and triceps lateral) of the reach arm and shoulder flexor (pectoralis major) of the stance arm which indicates their causal role; leg muscles may have indirectly contributed but were not recorded. The strong functional similarity of weight-shift APAs during crouched reaching to human stepping and cats reaching suggests that they are a core feature of posture-movement coordination.

scholarly journals Analytical and Experimental Analysis of a Free Link in Contact with a Granular Medium

2013 ◽  
Vol 2013 ◽  
pp. 1-9 ◽  
Author(s):  
Dan B. Marghitu ◽  
Seung Lee
Keyword(s):  
Granular Medium ◽  
Stopping Time ◽  
The Body ◽  
Resistance Force ◽  
Time Interval ◽  
The Moment ◽  
Static Resistance ◽  
The Impact ◽  
Resistance Forces ◽  
Empirical Approaches

In this study, the experimental and the simulation results for a planar free link impacting a granular medium are analyzed. The resistance force of the granular medium on the body from the moment of the impact until the body stops is very important. Horizontal and vertical static resistance forces developed by theoretical and empirical approaches are considered. The penetrating depth of the impacting end of the free link increases with the increase of the initial impacting velocity. We define the stopping time as the time interval from the moment of impact until the vertical velocity of the link end is zero. The stopping time of the end decreases as the initial velocity increases. The faster the end of the link impacts the surface of the granular medium, the sooner it will come to a stop. This phenomenon involves how rapidly a free link strikes the granular medium and how it slows down upon contact.

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