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Article
Publication date: 23 January 2009

Gargi Khanna, Rajeevan Chandel, Ashwani Kumar Chandel and Sankar Sarkar

The aim of this paper is to analyze the effects of aggressor‐line load variations (both active gate and passive capacitive loads) on the non‐ideal effects of a coupled…

Abstract

Purpose

The aim of this paper is to analyze the effects of aggressor‐line load variations (both active gate and passive capacitive loads) on the non‐ideal effects of a coupled VLSI‐interconnect system.

Design/methodology/approach

Signal delay, power dissipation and crosstalk noise in interconnect can be influenced by variation in load of another interconnect which is coupled to it. For active gate and passive capacitive load variations, such effects are studied through SPICE simulations of a coupled interconnect pair in a 0.13 μm technology. Crosstalk between a coupled pair, is affected by transition time of the coupled signal, interconnect length, distance between interconnects, size of driver and receiver, pattern of input, direction of flow of signal and clock skew. In this work, influence of an aggressor‐line load variations (both active gate and passive capacitive loads) on the non‐ideal effects of delay, power consumption and crosstalk in a victim‐line of a coupled VLSI‐interconnect system are determined through SPICE simulation. In this experiment, the victim line is terminated by a fixed capacitive load and the coupled to aggressor line has variable load, either passive capacitive or active gate. Four different input signal cases have been considered for the two types of variable load. Distributed RLC transmission model of interconnect is considered for the SPICE simulations.

Findings

The simulation results reveal that the effects are much dependent on the type of load and signal variations at the inputs of the two mutually coupled interconnects. Load control at the aggressor far end can be used to minimize some of the adverse effects of crosstalk.

Originality/value

This paper shows that in interconnect, signal delay, power consumption and crosstalk are all affected by load variations in a coupled neighboring interconnect.

Details

Microelectronics International, vol. 26 no. 1
Type: Research Article
ISSN: 1356-5362

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Article
Publication date: 9 April 2019

Mohamed Abd Alsamieh

The purpose of this paper is to study the behavior of elastohydrodynamic contacts subjected to forced harmonic vibrations including the effect of changing various working…

Abstract

Purpose

The purpose of this paper is to study the behavior of elastohydrodynamic contacts subjected to forced harmonic vibrations including the effect of changing various working parameters such as frequency, load amplitude and entrainment speed.

Design/methodology/approach

The time-dependent Reynolds equation is solved using the Newton–Raphson technique. The film thickness and pressure distribution are obtained at every time step by simultaneous solution of the Reynolds equation and film thickness equation including elastic deformation.

Findings

The frequency of vibration, load amplitude and entrainment speed are directly related to the film thickness perturbation, which is formed during load increasing phase of the cycle. The film thickness formed during load increasing phase is larger than that formed during load decreasing phase with larger deviation at a higher frequency or load amplitude and vice versa for lower frequency or load amplitude. The entrainment speed of the contact has an opposite effect to that of the frequency of vibration or load amplitude.

Originality/value

Physical explanations for the behavior of elastohydrodynamic contact subjected to forced harmonic vibration are presented in this paper for various working parameters of frequency, load amplitude and entrainment speed.

Details

Industrial Lubrication and Tribology, vol. 71 no. 6
Type: Research Article
ISSN: 0036-8792

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Article
Publication date: 9 April 2018

Swagat Pati, Kanungo Barada Mohanty and Sanjeeb Kumar Kar

This paper aims to demonstrate the efficacy of fuzzy logic controller (FLC) over proportional integral (PI) and sliding mode controller (SMC) for maintaining flat voltage…

Abstract

Purpose

This paper aims to demonstrate the efficacy of fuzzy logic controller (FLC) over proportional integral (PI) and sliding mode controller (SMC) for maintaining flat voltage profile at the load bus of a single-generator-based micro-grid system using STATCOM.

Design/methodology/approach

A STATCOM is used to improve the voltage profile of the load bus. The performance of the STATCOM is evaluated by using three different controllers: PI controllers, FLCs and SMCs. The performance comparison of the controllers is done with different dc bus voltages, different load bus voltage references, various loads such as R-L loads and dynamic loads.

Findings

A comparative analysis is done between the performances of the three different controllers. The comparative study culminates that FLC is found to be superior than the other proposed controllers. SMC is a close competitor of fuzzy controller.

Originality/value

Design of fuzzy logic and SMCs for a STATCOM implemented in a single-generator-based micro-grid system is applied.

Details

World Journal of Engineering, vol. 15 no. 2
Type: Research Article
ISSN: 1708-5284

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Article
Publication date: 8 June 2015

Qingrui Meng

– The purpose of this paper is to reveal the effect of starting time on hydro-viscous drive speed regulating start.

Abstract

Purpose

The purpose of this paper is to reveal the effect of starting time on hydro-viscous drive speed regulating start.

Design/methodology/approach

The modified transient Reynolds equation, thermal energy equation and temperature–viscosity equation were solved simultaneously by using finite element method. And then variations of the oil film load capacity, variations of temperature and variations of the torque generated by the oil film during the starting process were obtained.

Findings

The results show that during the starting process, both the oil film load capacity and the temperature show an upward trend, the torque increases during the beginning period and then decreases during the latter part of the starting process. When the starting time is less than 60 s, variations of the oil film load capacity and temperature show fluctuations, which decrease with the starting time. For any output speed, the corresponding oil film load capacity, temperature and torque decrease with the starting time, and the decreasing amplitude also decreases with the starting time.

Originality/value

This paper indicates that the starting time can be set to 60-90 s to obtain a perfect starting process. The simulation results are verified by the speed regulating start experiments. Research findings of this work provide theoretical basis for the design and practical application of the hydro-viscous drive equipments.

Details

Industrial Lubrication and Tribology, vol. 67 no. 4
Type: Research Article
ISSN: 0036-8792

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Article
Publication date: 2 August 2018

V.S. Madalli, Siddharama Patil, Ayyappa Hiremath and Ramesh Kudenatti

This paper aims to present a detailed analysis to explore the various properties of non-Newtonian couple stress lubricants between parallel porous plates.

Abstract

Purpose

This paper aims to present a detailed analysis to explore the various properties of non-Newtonian couple stress lubricants between parallel porous plates.

Design/methodology/approach

With reference to the theories based on micro-continuum analysis, a non-linear, non-Newtonian Reynolds type equation is arrived. The closed form solutions obtained clearly indicate the changes in pressure, load bearing capacity and response time because of variation in viscosity of couple stress fluid.

Findings

It is observed that the viscosity variation factor greatly influences the change in pressure, load carrying capacity and squeezing time.

Originality/value

It is observed that the nature of lubricants with suitable additives greatly helps in overcoming the adverse effect because of porous surface. Reynolds type equation is analysed using appropriate boundary conditions. The expression for pressure distribution arrived at in turn leads to the analysis of load bearing capacity and response time.

Details

Industrial Lubrication and Tribology, vol. 70 no. 6
Type: Research Article
ISSN: 0036-8792

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Article
Publication date: 16 August 2011

Dewan Muhammad Nuruzzaman, Mohammad Asaduzzaman Chowdhury and Mohammad Lutfar Rahaman

The present paper seeks to report the effect of duration of rubbing on friction coefficient for different polymer and composite materials. Variations of friction…

Abstract

Purpose

The present paper seeks to report the effect of duration of rubbing on friction coefficient for different polymer and composite materials. Variations of friction coefficient and wear rate with the normal load are also investigated experimentally when stainless steel (SS 304) pin slides on different types of materials such as cloth‐reinforced ebonite (commercially known as gear fiber), glass fiber‐reinforced plastic (glass fiber), nylon and polytetrafluoroethylene (PTFE).

Design/methodology/approach

A pin on disc apparatus is designed and fabricated. During experiment, the rpm of test samples was kept constant and relative humidity was 70 percent.

Findings

Studies have shown that the values of friction coefficient depend on applied load and duration of rubbing. It is observed that the values of friction coefficient decrease with the increase of normal load for glass fiber, nylon and PTFE. Different trend is observed for gear fiber, i.e. coefficient of friction increases with the increase of normal load. It is also found that wear rate increases with the increase of normal load for all the materials. The magnitudes of friction coefficient and wear rate are different for different materials.

Practical implications

It is expected that the applications of these results will contribute to the design of different mechanical components of these materials.

Originality/value

Within the observed range of applied normal load, the relative friction coefficient and wear rate of gear fiber, glass fiber, nylon and PTFE are experimentally investigated.

Details

Industrial Lubrication and Tribology, vol. 63 no. 5
Type: Research Article
ISSN: 0036-8792

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Article
Publication date: 26 June 2007

Erdem Koç and Emel Ceyhun Sabir

The main purpose of the research work carried out is to investigate the hydraulic balance conditions of the sealing ring of a mechanical radial face seal in terms of the…

Abstract

Purpose

The main purpose of the research work carried out is to investigate the hydraulic balance conditions of the sealing ring of a mechanical radial face seal in terms of the residual load acting on the ring by employing the theoretical model developed mentioned in the first part of the investigation.

Design/methodology/approach

The end load balance conditions for the movable seal ring have been examined by considering the residual load acting on the ring under all running conditions. The main lubrication and sealing mechanism is assumed to be due to the existence of the relative tilt between the mating surfaces, which is formed by the bearing misalignment. The aim of the theoretical model developed is to predict the necessary minimum film thickness between the relatively moving surfaces by considering the non‐dimensional running (operating) conditions and the geometrical parameters defined. The theoretical model is based on the main differential equation (Reynolds' equation) which is achieved by adopting the standard finite difference form.

Findings

Under the combination of the hydrostatic clamping forces and hydrodynamic restoring forces, an equilibrium position is reached with the seal ring displaced from its central position. At a particular non‐dimensional pressure, the seal ring comes into contact with the stationary plate and this limits the upper value of pressure that can be resisted by the mechanical seal type examined without metal‐metal contact. With the theoretical model developed, it was found that the minimum film thickness between the realtively moving surfaces could be predicted.

Originality/value

This paper provides a considerable scientific contribution to the field of lubrication and sealing aspect of the mechanical radial face seals. The results presented in the first part of the investigation and the remarks outlined in this paper would be considered as a design tool for the seal designers with special reference to ring behaviour under hydrodynamic and hydrostatic conditions.

Details

Industrial Lubrication and Tribology, vol. 59 no. 4
Type: Research Article
ISSN: 0036-8792

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Article
Publication date: 23 March 2012

Sandeep Singh, Kamlesh Kulkarni, Ramesh Pandey and Harpreet Singh

The purpose of this paper is to present elastic buckling behaviour of simply supported and clamped thin rectangular isotropic plates having central circular cutouts…

Abstract

Purpose

The purpose of this paper is to present elastic buckling behaviour of simply supported and clamped thin rectangular isotropic plates having central circular cutouts subjected to uniaxial partial edge compression. Analysis is carried out for four different kinds of partial edge compression and it is extended to study the effect of aspect ratio of plate on buckling load.

Design/methodology/approach

A finite element method technique is used in the current work to solve the buckling problem of plate using eight node quadrilateral element and plate kinematics based on first order shear deformation theory. Results obtained from finite element analysis are first validated for isotropic square plates, without cutouts, subjected to uniaxial partial edge compression with some earlier published literature.

Findings

From the current work it is concluded that the buckling strength of square plates is highly influenced by partial edge compression, as compared to plate subjected to uniform edge compression; but with increase in aspect ratio, influence of partial edge compression on plate buckling load decreases.

Originality/value

This paper usefully shows how partial edge compression of plates affects the buckling strength of plate having circular cutouts. Generally, simply supported plates subjected uniaxial partial edge compression of Type I and Type III are found to be stronger than plates subjected to partial edge compression Type II and Type IV, respectively.

Details

Journal of Engineering, Design and Technology, vol. 10 no. 1
Type: Research Article
ISSN: 1726-0531

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Article
Publication date: 1 July 1949

W.S. Hemp

CONSIDER a fuselage or wing structure in the form of a reinforced cylindrical tube. We shall base our analysis of the equilibrium conditions of this structure upon the…

Abstract

CONSIDER a fuselage or wing structure in the form of a reinforced cylindrical tube. We shall base our analysis of the equilibrium conditions of this structure upon the assumptions outlined in 2.6. In particular referring in the first place to a skin panel lying between adjacent stringers and rings, we remark that this panel carries only shear stresses and is free from external forces. It follows, as we have observed before, that this panel must therefore be in a state of uniform shearing and so must apply uniform shear flows at its lines of juncture with the adjacent panels and the reinforcing stringers and rings. The equilibrium conditions to be satisfied at a stringer‐skin joint are now clear. The panels adjacent to the stringer apply different, but uniform, shear flows, to the line of attachment. The reaction from the stringer is determined by the rate of variation of its end load, for this clearly gives the rate of load input into the stringer. Adopting a consistent sign convention for the shear flows in the several skin panels we can thus enunciate the following theorem:

Details

Aircraft Engineering and Aerospace Technology, vol. 21 no. 7
Type: Research Article
ISSN: 0002-2667

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Article
Publication date: 1 September 2005

L.T. Wong and N.K. Fong

To model the evacuation time from buildings in the event of emergencies based on occupant load, looking specifically at the exit width as a design parameter.

Abstract

Purpose

To model the evacuation time from buildings in the event of emergencies based on occupant load, looking specifically at the exit width as a design parameter.

Design/methodology/approach

In this study, transient occupant loads from a simulation model based on a recent study of 34 offices in Hong Kong were used to evaluate the probable risk to evacuees in the case of an emergency evacuation. For this analysis the “door carrying capacity” approach was used, together with probability profiles for the occupant loads at certain exit flow rates. This paper investigates the occupant load profiles as well as the yearly and daily occupant load variations of some typical offices in Hong Kong and examines the fire safety implications of the office building designs from the perspective of the risk to evacuees.

Findings

The results show that the building occupant load, occupant‐load ratio, total exit width and specific flow rate at the exit significantly affect the risk to evacuees.

Research limitations/implications

The model parameters are not exhaustive and are determined from surveys in Hong Kong.

Practical implications

A useful source of reference in conducting risk assessment for safe egress design of office buildings for those involved in building design, operation and management.

Originality/value

This paper, taking account of exit design, occupant load and its variations using the door carrying capacity approach, presents a simple method to determine the probable risk to evacuees in offices.

Details

Facilities, vol. 23 no. 11/12
Type: Research Article
ISSN: 0263-2772

Keywords

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