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Book part
Publication date: 15 December 1998

A D Mason and A W Woods

We use a combination of continuum and car-following models to explore the potential impact of speed-controls on (i) decreasing travel times at times of congested flow; and…

Abstract

We use a combination of continuum and car-following models to explore the potential impact of speed-controls on (i) decreasing travel times at times of congested flow; and (ii) increasing the safety of motorway flow approaching the site of an accident.

Details

Mathematics in Transport Planning and Control
Type: Book
ISBN: 978-0-08-043430-8

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Article
Publication date: 21 January 2021

Hui Li, Hao Li, Rongfeng Zhang, Yi Liu, Shemiao Qi and Heng Liu

The purpose of this paper is to introduce the structure design process of the cantilever spindle with limited installation space and wishing to increase its critical speed.

Abstract

Purpose

The purpose of this paper is to introduce the structure design process of the cantilever spindle with limited installation space and wishing to increase its critical speed.

Design/methodology/approach

In this paper, the finite element method was used to analyze the influence of the supporting stiffness and the structure of the spindle on the critical speed, and then the structure of the spindle was designed; moreover, the experiment was accomplished and the experiment results show that the spindle can work stably.

Findings

Through analyzing the influence of the supporting stiffness and the structure of the spindle on the critical speed, the following conclusions could be obtained: the shape of the first-mode is the bend vibration of the cantilever of the spindle; the first-order critical speed of the spindle gradually decreases with the diameter and length of the cantilever increasing; the first-order critical speed of the spindle increases with the depth and diameter of the blind hole increasing; and the experiment was accomplished and the experiment results show that the spindle can work stably.

Originality/value

In this paper, the finite element method was used to design the spindle of the testing machine, and satisfactory results were obtained. It can provide a theoretical reference for the design of a similar spindle.

Details

Industrial Lubrication and Tribology, vol. 73 no. 2
Type: Research Article
ISSN: 0036-8792

Keywords

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Article
Publication date: 10 September 2020

Zhiming Zhao, Rui Zhang, Feng Ji and Xiaoyang Yuan

High power and speed are new demands for rotating machinery which needs the journal bearings with high dynamic characteristics. The critical speed of the rotor-bearing…

Abstract

Purpose

High power and speed are new demands for rotating machinery which needs the journal bearings with high dynamic characteristics. The critical speed of the rotor-bearing system is one of the most significant parameters to evaluate the dynamic characteristics. This paper aims to investigate the theoretical and experimental analysis of a rotor system supported by large diameter elliptical bearings.

Design/methodology/approach

To obtain the theoretical and experimental support for rotor-bearing system design, dynamic characteristics theoretical analysis based on the finite difference method is given and an experiment focuses on critical speed identification is carried out.

Findings

The theoretical calculation results indicate that the critical speed is near to 800 rpm and there is no large vibration amplitude round working speed (1,500 rpm). Using the test bench in the factory unit, vibration data including three experimental processes are obtained. According to the vibration data, the critical speed is identified which also indicates that it is stable when working at 1,500 rpm.

Originality/value

The design method for the rotor system supported by large diameter elliptical bearing can be obtained by the theoretical and experimental results shown in this paper.

Peer review

The peer review history for this article is available at: https://publons.com/publon/10.1108/ILT-04-2020-0122/

Details

Industrial Lubrication and Tribology, vol. 73 no. 1
Type: Research Article
ISSN: 0036-8792

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Article
Publication date: 3 December 2021

Haris Calgan

This study aims to design and implement a novel tilt integral sliding mode controller and observer for sensorless speed control of a permanent magnet synchronous motor (PMSM).

Abstract

Purpose

This study aims to design and implement a novel tilt integral sliding mode controller and observer for sensorless speed control of a permanent magnet synchronous motor (PMSM).

Design/methodology/approach

A control strategy combining the tilt integral derivative (TID) with sliding mode control (SMC) is proposed to determine the tilt integral sliding mode manifold. Using this manifold, tilt integral sliding mode controller (TISMC) and observer (TISMO) are designed. The stabilities are verified by using Lyapunov method. To prove the effectiveness and robustness of proposed methods, sensorless speed control of PMSM is performed for various operating conditions such as constant and variable speed references, load disturbance injection, parameter perturbation, whereas sensor noises are not taken into account. The performance of proposed method is compared with TID controller, proportional integral derivative controller and conventional SMO.

Findings

Simulation results demonstrate that TISMC and TISMO have better performance in all operating conditions. They are robust against parameter uncertainties and disturbances. TISM based sensorless control of PMSM is well guaranteed with superior performance.

Originality/value

The proposed method has not been tackled in the literature. By combining TID and SMC, novel tilt integral sliding manifold is presented and used in designing of the controller and observer. It is proven by Lyapunov method that errors converge to zero.

Details

COMPEL - The international journal for computation and mathematics in electrical and electronic engineering , vol. 41 no. 1
Type: Research Article
ISSN: 0332-1649

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Article
Publication date: 2 October 2018

Qingrui Meng, Zhao Chenghao and Tian Zuzhi

Friction pairs of the hydro-viscous drive speed regulating start device should be designed based on the rated torque. To obtain design basis of the rated torque of the…

Abstract

Purpose

Friction pairs of the hydro-viscous drive speed regulating start device should be designed based on the rated torque. To obtain design basis of the rated torque of the hydro-viscous drive speed regulating start device, studies on effect of torque ratio (a ratio of the load torque to the rated torque) on speed regulating start were carried out theoretically and experimentally.

Design/methodology/approach

Under different torque ratio, the modified Reynolds, the thermal energy and the viscosity-temperature equations were solved simultaneously by using finite element method to reveal variation laws of the oil film load capacity and torque transmission during the starting process. Then, speed regulating start experiments were carried out to study the following performance of the output speed.

Findings

The results show that oil film thickness decreases with the increase of the torque ratio; when oil film thickness is less than 0.05 mm, oil film temperature increases rapidly with the decrease of oil film thickness, which eventually deteriorates performance of the speed regulating start; when the torque ratio decreases to about 0.3, output speed shows a better following performance.

Originality/value

It indicates that, to acquire a better speed regulating start, the rated torque of the hydro-viscous drive speed regulating start device should not be less than three times of the load torque. Achievements of this work provide theoretical basis for optimal design of the friction pairs of the hydro-viscous drive speed regulating start device.

Details

Industrial Lubrication and Tribology, vol. 70 no. 9
Type: Research Article
ISSN: 0036-8792

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Article
Publication date: 21 June 2011

Qingrui Meng and Youfou Hou

The purpose of this paper is to reveal the effect of working oil temperature, load and starting time on hydro‐viscous drive speed‐regulating start.

Abstract

Purpose

The purpose of this paper is to reveal the effect of working oil temperature, load and starting time on hydro‐viscous drive speed‐regulating start.

Design/methodology/approach

The authors developed an experimental equipment and carried out a number of experiments under different temperatures, load and starting time.

Findings

The results show that both the temperature rise of working oil and the increase of load can induce fluctuations in output speed, but the effect of the working oil temperature rise is more serious; also the longer the starting time is, the more perfectly the output speed can trace the given speed.

Practical implications

It indicates that the working oil temperature should be kept in a certain range by using a cooling device in practical application; and that under this experimental condition, kinematics viscosity of the working oil should be greater than 45 mm2/s under rated working temperature, and the relatively suitable starting time should range from 90 to 120 s.

Originality/value

The paper explains the effect of various factors on speed‐regulating start, and provides the basis for the design and the application of hydro‐viscous drives.

Details

Industrial Lubrication and Tribology, vol. 63 no. 4
Type: Research Article
ISSN: 0036-8792

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Article
Publication date: 1 January 1948

It is now well known among aircraft engineers that the compressibility of the air has an increasingly important effect on the aerodynamic forces as the flight speed rises…

Abstract

It is now well known among aircraft engineers that the compressibility of the air has an increasingly important effect on the aerodynamic forces as the flight speed rises and approaches the speed of sound. As a result of the development of the gas turbine and other improvements, aircraft speeds have risen very rapidly during the last few years, and compressibility effects are, therefore, of great importance in many new aircraft designs. Unfortunately, the designer is faced with very great difficulties in attempting to predict the behaviour of a new aircraft flying at high speeds. The main reason for this is simply that there is very little systematic knowledge of air flow at high speeds past wings and bodies. A further difficulty arises because many of the methods and ideas which have proved so useful in the design of low speed aircraft may have to be changed completely when high speeds are considered. To mention only one example, it is well known that at low speeds a separation of the boundary layer at the rear of an aerofoil causes an increase of drag, but is not so well known that a separation of the same kind at supersonic speeds causes a reduction of drag (for a given incidence). Because there may be differences as important as this between high and low speeds it is not enough that the designer should merely modify his present methods and ideas to allow for compressibility; he must regard the design problems of high speed flight as completely new ones, and acquire a new scientific background to deal with them. It is important that the designer of high speed aircraft should have a sound knowledge of the fundamental principles of air flow at high speeds. Unfortunately, much of the information which is available on this subject is scattered among a large number of books and reports, and is not easily accessible. Thus there is a great need for a book giving a concise introduction to the subject, to enable the aircraft designer to read and understand the current reports dealing with recent developments, and to provide the scientific background which is so necessary for good design.

Details

Aircraft Engineering and Aerospace Technology, vol. 20 no. 1
Type: Research Article
ISSN: 0002-2667

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Article
Publication date: 1 December 1937

B. Lundberg

THE sinking speed of an, aeroplane is defined as the vertical component of the forward velocity in gliding flight. It is easy to show that the sinking speed so defined is…

Abstract

THE sinking speed of an, aeroplane is defined as the vertical component of the forward velocity in gliding flight. It is easy to show that the sinking speed so defined is included in the general equation of the rate of climb with engine on, the rate of climb being the difference between the “rising speed,” corresponding with the horsepower available, and the sinking speed, which in turn corresponds with the horse‐power required. Thus the sinking speed always plays an important rôle in all conditions of flight and it is the author's opinion that, especially in performance calculations, the use of the quantities rising an,d sinking speed are preferable to the more commonly used power‐quantities.

Details

Aircraft Engineering and Aerospace Technology, vol. 9 no. 12
Type: Research Article
ISSN: 0002-2667

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Article
Publication date: 14 August 2007

T. Orlowska‐Kowalska and M. Dybkowski

This paper aims to obtain an accurate and robust estimation method of the rotor flux and speed for the sensorless induction motor (IM) drive.

Abstract

Purpose

This paper aims to obtain an accurate and robust estimation method of the rotor flux and speed for the sensorless induction motor (IM) drive.

Design/methodology/approach

The reduced order observer has been used as an online tuned rotor flux model in the model reference adaptive system (MRAS) concept applied for the IM speed estimation. The output of this observer was used also as a feedback signal required in the direct field‐oriented control (DFOC) structure of the IM.

Findings

It is shown that a new rotor flux and speed estimator are more robust to motor parameter changes in comparison with the classical MRAS estimator and can work stably in the DFOC structure, in the wide speed range, even for relatively high (50 per cent) identification errors of equivalent circuit parameters of the IM.

Research limitations/implications

The investigation looked mainly at the estimation accuracy performance and whole system stability while economic issues will still need to be addressed.

Practical implications

The proposed new improved MRAS speed estimator can be easily realised using modern digital signal processors. The implementation was tested in an experimental set‐up with floating point DSP used as the system controller. The fixed‐point realisation needs to be developed to obtain the practical application in the industrial drive systems.

Originality/value

The application of the reduced order flux observer as a tuned flux model in the MRAS type speed estimator instead of the simple, but very sensitive to motor parameter uncertainties, current flux model, enables much better accuracy and stability of the rotor speed estimation in the complex DFOC structure than in the case of classical MRAS estimator.

Details

COMPEL - The international journal for computation and mathematics in electrical and electronic engineering, vol. 26 no. 4
Type: Research Article
ISSN: 0332-1649

Keywords

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Article
Publication date: 5 May 2015

Konrad Urbanski

The purpose of this paper is to develop the Permanent Magnet Synchronous Motors drive which has possibility to work in sensorless mode at low speed based on back EMFs…

Abstract

Purpose

The purpose of this paper is to develop the Permanent Magnet Synchronous Motors drive which has possibility to work in sensorless mode at low speed based on back EMFs estimation.

Design/methodology/approach

Estimation uses modified Luenberger observer and the preprocessing of the EMFs before calculating the speed, using derivative and the Kalman filter (KF) to obtain smooth waveform of the estimated speed. This modification is needed because of the nonlinear change of the estimated back EMFs amplitude as a function of speed, in low-speed range.

Findings

How to use back EMF observer to estimate a speed in the low-speed range was found in the course of the work. Simple and effective algorithm uses KF and can work even with a relatively big deformation of the estimated back EMF.

Practical implications

Such sensorless drive may be used in low-cost constant or variable speed drive in domestic use or industrial application. Such drive may work properly where there is no initial load torque and the sign of the speed does not change.

Originality/value

Presented results challenge the view that at low-speed range (not the standstill), the back EMF-based method of position estimation is very difficult or impossible. However, the problem lays in proper speed estimation, not the position estimation.

Details

COMPEL: The International Journal for Computation and Mathematics in Electrical and Electronic Engineering, vol. 34 no. 3
Type: Research Article
ISSN: 0332-1649

Keywords

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