The influence of the perturbation of the wheel rotation speed on the stability of a railway bogie on steady curve sections of a track

2018 ◽  
Vol 57 (3) ◽  
pp. 425-443 ◽  
Author(s):  
Tingting Zhang ◽  
Hans True ◽  
Huanyun Dai
Keyword(s):  
Rotation Speed ◽  
Wheel Rotation ◽  
Railway Bogie ◽  
The Stability

THE STAEILITY OF COUETTE FLOW IN AN AXIAL MAGNETIC FIELD

1958 ◽  
Vol 36 (11) ◽  
pp. 1509-1525 ◽  
Author(s):  
E. R. Niblett
Keyword(s):  
Magnetic Field ◽  
Boundary Conditions ◽  
Theoretical Prediction ◽  
Viscous Flow ◽  
Rotation Speed ◽  
Axial Magnetic Field ◽  
Radioactive Isotopes ◽  
Electrically Conducting ◽  
Electrically Conducting Fluid ◽  
The Stability

Chandrasekhar's theory of the stability of viscous flow of an electrically conducting fluid between coaxial rotating cylinders with perfectly conducting walls is extended to include the case of non-conducting walls, and it is found that their effect is to reduce the critical Taylor numbers and increase the wavelength of the instability patterns by considerable amounts. An experiment designed to measure the values of magnetic field and rotation speed at the onset of instability in mercury between perspex cylinders is described. The radioactive isotopes Hg197 and Hg203 were used to trace the flow. The results support the theoretical prediction that the boundary conditions can have a large effect on the motion.

scholarly journals Configuration-Based Wheel Control for Step-Climbing Vehicle

2007 ◽  
Vol 19 (1) ◽  
pp. 52-59 ◽  
Author(s):  
Daisuke Chugo ◽  
◽  
Kuniaki Kawabata ◽  
Hayato Kaetsu ◽  
Hajime Asama ◽  
...  
Keyword(s):  
Rotation Speed ◽  
Rotation Velocity ◽  
Rough Terrain ◽  
Traction Control ◽  
Irregular Terrain ◽  
Wheel Rotation ◽  
Rotation Error ◽  
Vehicle Configuration ◽  
Step Climbing

We propose a derivation of adaptable wheel rotation velocity for negotiating irregular terrain based on vehicle configuration. We developed a holonomic vehicle capable of negotiating steps and running around omnidirectionally on a flat floor using seven special wheels and two passive links. Each wheel has its actuator, requiring that the rotation velocity of individual wheels be coordinated, which is difficult due to changes rotation speed when the passive link negotiates the irregular terrain. Unstable rotation velocity calculated without considering the vehicle configuration causes wheel slippage and rotation error that adversely affect mobility on rough terrain. Because conventional general traction control cannot coordinate wheel velocity, we propose reference derivation that does so based on the vehicle configuration. In the sections that follow, we focus on (1) the derivation of individual wheel velocity during step climbing and (2) adaptation to wheel control reference while balancing rotation velocity among wheels. We confirm the feasibility of our proposal in experiments using our vehicle prototype.

scholarly journals EFFECT OF DITCHING'S PARAMETERS ON OPERATION QUALITY OF ORCHARD DITCHING-FERTILIZER MACHINE

2021 ◽  
pp. 477-487
Author(s):  
ChunBao Xu ◽  
HongJian Zhang ◽  
ShuangXi Liu ◽  
Chengfu Zhang ◽  
Junlin Mu ◽  
...  
Keyword(s):  
Deflection Angle ◽  
Rotation Speed ◽  
Design Method ◽  
Coverage Rate ◽  
Forward Speed ◽  
Stability Coefficient ◽  
Machine Performance ◽  
The Deflection Angle ◽  
Relative Errors ◽  
The Stability

This study aims to evaluate the effects of different parameter settings on the ditching performance using a ditching-fertilizer. We aimed to improve the performance of ditching-fertilizer machine performance in sustainable agriculture. With Box-Behnken experimental design method, taking forward speed, the rotation speed of the ditching cutter, and the deflection angle of ditching cutter as experimental factors, taking ditching depth stability and soil coverage rate as test indexes, the operation parameters of orchard ditching-fertilizer machine are studied. The regression model between test indexes and experimental factors is established, and the influence of each factor on the experimental indexes is analyzed. The test factors are comprehensively optimized. The results show that when the forward speed is 0.8km/h, the rotation speed of the ditching cutter is 348r/min, and the deflection angle of the ditching cutter is 32°, the ditching effect is the best. At this time, the stability coefficient of the ditching depth is 98.33%, and the soil coverage rate is 81.53%. As for the field test, which measured the stability coefficient of ditching depth, and the average soil cover rate is 96.24%, and 79.14%, respectively, and the relative errors from the optimized value are 2.17%, and 3.02%, respectively.

Stability and Bifurcation of a Continuum Rotor with Transverse Electromagnetic and Bearing Excitations

2011 ◽  
Vol 105-107 ◽  
pp. 439-443
Author(s):  
Hai Yang Luo ◽  
Yue Fang Wang
Keyword(s):  
Periodic Solution ◽  
Electromagnetic Force ◽  
Rotation Speed ◽  
Harmonic Balance Method ◽  
Oil Film ◽  
Runge Kutta Method ◽  
Stability And Bifurcation ◽  
Nonlinear Motion ◽  
Transverse Electromagnetic ◽  
The Stability

This paper presents the stability and bifurcation of a continuum rotor with transverse electromagnetic and bearing excitations. The rotor system is modeled as continuous beam which is excited by uniformly distributed electromagnetic force and two oil-film forces. Using the Galerkin’s method, the partial differential equation of nonlinear motion is discretized as second order ordinary differential equations. The harmonic balance method is used to determine the approximate periodic solution, then the Floquet multipliers are obtained and the stability of periodic solution can be judged. The Andronov-Hopf bifurcation is presented when the leading Floquet multiplier continually changing with rotation speed passes the unit circle on the complex plane. Bifurcation diagrams of displacement with varying rotation speed are obtained using the Runge-Kutta method. Periodic motion and quasi-periodic motions appear alternately with the rotation speed showing inherent interaction between electromagnetic force and oil-film forces.

The stability of rotating flows with a cylindrical free surface

1967 ◽  
Vol 30 (1) ◽  
pp. 127-147 ◽  
Author(s):  
T. J. Pedley
Keyword(s):  
Free Surface ◽  
Rotation Speed ◽  
Outer Boundary ◽  
Rotating Flows ◽  
Rotating Flow ◽  
Sufficient Condition ◽  
Necessary And Sufficient Condition ◽  
The Stability ◽  
Necessary And Sufficient ◽  
Axisymmetric Disturbances

The stability to small inviscid disturbances of a rotating flow, whose velocity components in cylindrical polars (r, 0, z) are (0, V(r), 0), is investigated when one boundary of the flow (r = b) is a free surface under the action of surface tension (γ), and the other is either at infinity, or a rigid cylinder (r = a ≠ b), or at the axis (r = 0). The free surface may be the inner or the outer boundary. A necessary and sufficient condition for stability to axisymmetric disturbances is derived, which requires that Rayleigh's criterion of increasing circulation be satisfied, and otherwise depends only on b, V(b), γ and the density of the swirling liquid. This condition may be extended to include non-axisymmetric disturbances when V ∝ 1/r and when V ∝ r although in the latter case it is no longer a necessary one. It is shown that, in the case V ∝ r, as well as V ∝ 1/r, the ‘most unstable’ disturbance on a rotating column of fluid will be non-axisymmetric if the rotation speed at the surface is sufficiently great. Several applications of the theory are suggested, and a possible experiment to test it is described.

Floquet Stability Analysis of a Rotor Supported on Rolling Element Bearings With Clearance and Static Load

2013 ◽  
Author(s):  
C. A. Kitio Kwuimy ◽  
A. S. Das ◽  
C. Nataraj
Keyword(s):  
Static Load ◽  
Rotation Speed ◽  
Approximate Model ◽  
Hertzian Contact ◽  
Rolling Element Bearings ◽  
Rotating Shaft ◽  
Second Order Differential Equations ◽  
Rolling Element ◽  
Small Clearance ◽  
The Stability

A rotating shaft supported on rolling element bearings is considered. The system is known to be modeled by a pair of coupled second order differential equations involving Hertzian contact force and thus parametric excitations. In studying the stability of the system, the static equilibrium in the direction of the static load is found to linearly increases with clearance. An approximate model is obtained and conditions of validity of such a model are discussed. Cage rotation speed, static load and clearance are revealed as key parameters. Considering the Floquet formalism for stability, in the domain (clearance,speed), it is found that the domain of stability decreases for large clearance and increases for small clearance. Higher number of rolling element as well as smaller static load positively affect the stability as well.

scholarly journals Effects on the Stability of the Balloon Shape in the Covered Yarn Process

2017 ◽  
Vol 25 (0) ◽  
pp. 68-72
Author(s):  
Pei Feng ◽  
Pei Feng ◽  
Ronggen Zhang ◽  
Chongchang Yang ◽  
Chongchang Yang
Keyword(s):  
Experimental Data ◽  
Mathematical Model ◽  
High Speed ◽  
Rotation Speed ◽  
Yarn Tension ◽  
The Stability

In the process of producing covered yarn, a single outer wrapping yarn forms a balloon when it rotates at high speed. In this work, we used a mathematical model of a balloon formed by polyamide,which is a common outer wrapping yarn, and verified its feasibility with a group of experimental data. The effects of yarn tension, rotation speed, balloon height and turntable radius on the balloon shape were analysed and the correctness simultaneously demonstrated.

scholarly journals TECHNOLOGY OPTIMIZATION FOR CENTRIFUGAL-CAST ROLL MANUFACTURING

2016 ◽  
Vol 2016 (2) ◽  
pp. 143-148
Author(s):  
Наталья Жижкина ◽  
Natalya Zhizhkina
Keyword(s):  
Rotation Speed ◽  
Vertical Axis ◽  
Production Costs ◽  
Experimental Investigations ◽  
Working Layer ◽  
Nickel Chromium ◽  
Roll Casting ◽  
Casting System ◽  
System Functioning ◽  
The Stability

This paper reports the sheet roll spun casting. It is shown that sheet rolls of required quality and with minimum production costs are manufactured through a method of spun casting on a machine with a vertical axis of a mould rotation. It is defined that at spun casting a more intensive foundry cooling occurs as a result of which a blank is characterized with a denser and more even structure of a working layer. It is revealed that the stability of such a process depends to a considerable degree upon a spin casting system functioning a significant property of which is a speed of rotation. In the paper there is analyzed a rotation speed influence upon a grain size, a quantitative ratio of structural constituents in a working layer composed of nickel-chromium cast iron and also upon the level of its properties. The analysis of the rotation speed influence of a casting mold upon a structure and a property level of a roll working surface was based on experimental investigations of foundries under industrial conditions. The microstructure (the size of primary grains, their composition) of products analyzed was estimated with the aid of a common metallographic procedure. On the basis of experiments carried out it is determined that even an insignificant increase (by 7%) of mould rotation speed during roll casting allows without expensive processing of liquid melt of a work-ing layer increasing its structure uniformity. As a result of this the level of its properties increases (hardness – by 3 units). Consequently, the increase of rolling tool efficiency is expected. The presented results of investigations are basic for works on servicing characteristics increase of spin-cast rolls.

scholarly journals Experimental investigation on operation parameters of 3Å molecular sieve desiccant coated total energy recovery wheel for maximum effectiveness

2020 ◽  
Vol 24 (3 Part B) ◽  
pp. 2113-2124 ◽  
Author(s):  
Miklos Kassai ◽  
Laith Al-Hyari
Keyword(s):  
Air Temperature ◽  
Flow Rate ◽  
Energy Recovery ◽  
Rotation Speed ◽  
Experimental Tests ◽  
Ambient Air ◽  
Volume Flow ◽  
Test Facility ◽  
Wheel Rotation ◽  
Air Volume

The object of this research study was to investigate the maximum effectiveness values of the energy wheel by experimental tests conducted under extreme difference ambient air conditions parameters, different air volume flow rates, and energy wheel rotation speeds. Air temperature and humidity experimental tests were performed using a test facility that was developed and installed into the Indoor Air Quality and Thermal Comfort Laboratory of Budapest University of Technology and Economics. Our objective was to get the effectiveness values of sorption coated air-to-air energy recovery wheel for steady-state conditions under different ambient air (as supply air inlet) conditions. It was found that the sensible effectiveness increases by decreasing the volumetric flow rate through the wheel, and the optimum values of the effectiveness were given at the maximum wheel rotation speed based on the tests. As for the latent and total effectivenesses, their characteristics show an increasing trend by decreasing the air volume flow rate, ambient air temperature and relative humidity and increasing the wheel rotation speed.

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