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Article
Publication date: 1 March 1996

H.K. Tang and Brian Lee

Programmable electronics are particularly susceptible to transients, a form of electromagnetic interference. The widespread use of programmable electronics in many…

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Abstract

Programmable electronics are particularly susceptible to transients, a form of electromagnetic interference. The widespread use of programmable electronics in many mass‐produced products, industrial systems and safety‐critical applications is a cause for concern over their reliability. Neglecting transients’ effect in the initial product specification stage increases significantly the possibility of having to redesign a product late in its development cycle, with all its serious consequences. Deals first with the nature of transients and transient faults in programmable electronics, then elaborates on transients’ effects on reliability and discusses the related management issues.

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International Journal of Quality & Reliability Management, vol. 13 no. 2
Type: Research Article
ISSN: 0265-671X

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Article
Publication date: 7 June 2018

Sonia Bensemmane, Marc Ohana and Florence Stinglhamber

Prior research has conceptualized workplace justice as a stable variable over time changing from one individual to another. However, it can be assumed that perceptions of…

Abstract

Purpose

Prior research has conceptualized workplace justice as a stable variable over time changing from one individual to another. However, it can be assumed that perceptions of organizational justice fluctuate within the same person over the course of a few weeks or months due to different events at work. Specifically, the purpose of this paper is to suggest that transient overall team justice is predictive of employee’s transient thriving at work (i.e. the experience of vitality and learning at work). In addition, the authors examined transient self-efficacy as an underlying mechanism of this relationship.

Design/methodology/approach

A total of 395 individuals completed a first general questionnaire and then completed an online questionnaire over four waves of survey.

Findings

Results of hierarchical linear models indicated that transient overall team justice positively predicts transient individual’s self-efficacy, which, in turn, positively predicts transient individual’s thriving at work.

Research limitations/implications

Overall, a dynamic approach of organizational justice capturing variability in justice perceptions certainly enlarges our understanding of the concept and its outcomes.

Originality/value

The study contributes to understand why even employees who feel generally treated with justice by their team may experience from time to time low levels of thriving at work because of a recent unjust treatment from the team and a decrease of their subsequent self-efficacy.

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Journal of Managerial Psychology, vol. 33 no. 2
Type: Research Article
ISSN: 0268-3946

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Article
Publication date: 13 November 2007

Jian Tang, Xiang Cui, Lei Qi, Tiebing Lu, Lin Li, Puxuan Zhu, Guang Yang and Weizhen Zhang

The purpose of this paper is to present a method to calculate the transient induced voltages along the underground pipelines and analyze the transient interference…

Abstract

Purpose

The purpose of this paper is to present a method to calculate the transient induced voltages along the underground pipelines and analyze the transient interference generated in the pipelines due to the inductive coupling in the fault‐to‐ground condition of power lines in close proximity.

Design/methodology/approach

Based on finite difference‐time domain method, an improved method is proposed to calculate transient inductive interference in underground metallic pipelines due to a fault in nearby power lines. The frequency‐dependent problem in the analysis of transient interference is solved in phase domain. Compared with the traditional method, the disposal of phase‐modal transformation matrices’ frequency‐dependent characteristic is avoided and the calculation is simplified by using vector fitting approach and recursive algorithm greatly in the proposed method.

Findings

A novel improved method is proposed to calculate transient induced voltage distribution along underground metallic pipelines due to a fault in nearby power lines. Results show that the peak value of transient induced voltage at the most critical point is about 1.15 times of the magnitude in the steady state without the fault removed and the analysis of transient inductive interference is necessary in the fault‐to‐ground case of power lines.

Practical implications

In order to mitigate the interference from power lines to nearby pipelines, pipelines should be good grounded and positioned as far away from the power line as possible. In high soil resistivity areas, the common corridor should be avoided.

Originality/value

The paper presents a method to calculate the transient induced voltages along the underground pipelines and analyze the transient interference generated in the pipelines due to the inductive coupling in the fault‐to‐ground condition of nearby power lines. The proposed method is general and can also be applied to other transient interference studies such as crosstalk problems of communication networks and interference between power lines and aboveground pipelines or communication cables. Effects of various parameters upon the inductive interference generated in underground pipelines due to a fault in nearby power lines are analyzed to be a guide for controlling the inductive interference.

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COMPEL - The international journal for computation and mathematics in electrical and electronic engineering, vol. 26 no. 5
Type: Research Article
ISSN: 0332-1649

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Article
Publication date: 3 May 2016

Nicola Massarotti, Michela Ciccolella, Gino Cortellessa and Alessandro Mauro

The purpose of this paper is to focus on the numerical analysis of transient free convection heat transfer in partially porous cylindrical domains. The authors analyze the…

Abstract

Purpose

The purpose of this paper is to focus on the numerical analysis of transient free convection heat transfer in partially porous cylindrical domains. The authors analyze the dependence of velocity and temperature fields on the geometry, by analyzing transient flow behavior for different values of cavity aspect ratio and radii ratio; both inner and outer radius are assumed variable in order to not change the difference ro-ri. Moreover, several Darcy numbers have been considered.

Design/methodology/approach

A dual time-stepping procedure based on the transient artificial compressibility version of the characteristic-based split algorithm has been adopted in order to solve the transient equations of the generalized model for heat and fluid flow through porous media. The present model has been validated against experimental data available in the scientific literature for two different problems, steady-state free convection in a porous annulus and transient natural convection in a porous cylinder, showing an excellent agreement.

Findings

For vertically divided half porous cavities, with Rayleigh numbers equal to 3.4×106 for the 4:1 cavity and 3.4×105 for the 8:1 cavity, the numerical results show that transient oscillations tend to disappear in presence of cylindrical geometry, differently from what happens for rectangular one. The magnitude of this phenomenon increases with radii ratio; the porous layer also affects the stability of velocity and temperature fields, as oscillations tend to decrease in presence of a porous matrix with lower value of the Darcy number.

Research limitations/implications

A proper analysis of partially porous annular cavities is fundamental for the correct estimation of Nusselt numbers, as the formulas provided for rectangular domains are not able to describe these problems.

Practical implications

The proposed model represents a useful tool for the study of transient natural convection problems in porous and partially porous cylindrical and annular cavities, typical of many engineering applications. Moreover, a fully explicit scheme reduces the computational costs and ensures flexibility.

Originality/value

This is the first time that a fully explicit finite element scheme is employed for the solution of transient natural convection in partially porous tall annular cavities.

Details

International Journal of Numerical Methods for Heat & Fluid Flow, vol. 26 no. 3/4
Type: Research Article
ISSN: 0961-5539

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Article
Publication date: 15 February 2013

Kam C. Chan, Feida Zhang and Weining Zhang

The purpose of this paper is to study the relationship between institutional holdings and analyst coverage in the context of the heterogeneous nature of institutional investors.

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Abstract

Purpose

The purpose of this paper is to study the relationship between institutional holdings and analyst coverage in the context of the heterogeneous nature of institutional investors.

Design/methodology/approach

Similar to prior studies (e.g. Ke and Ramalingegowda; Ramalingegowda and Yu), this paper obtains institutional investors' trading classifications (transient, dedicated, and quasi‐indexing) from Brian Bushee directly. To examine the hypotheses, the paper uses a two‐step instrumental variable approach demonstrated in O'Brien and Bhushan to mitigate the simultaneity relationship between the change in analyst coverage and the change in the number of heterogeneous institutional investors.

Findings

The findings suggest that such relations are different among transient, dedicated, and quasi‐indexing institutional investors. Specifically, there are three major results. First, a change to the number of analyst coverage has the lowest impact on the change in the number of dedicated institutional investors. Second, a change in the number of transient institutional investors has a higher impact on change in analyst coverage than those for change in the number of dedicated and quasi‐indexing institutional investors. Third, changes to analysts' buy or sell recommendations have the least impact on the change in the number of dedicated institutions, relative to transient and quasi‐indexing institutions.

Research limitations/implications

The findings suggest that institutional investors are not homogeneous. Research studies on institutional investors need to disentangle the differences among different types of institutions.

Originality/value

The paper provides a comprehensive study on different institutional investors and analyst coverage. The findings show the complex nature of the interaction between institutional investors and analyst coverage.

Details

Review of Accounting and Finance, vol. 12 no. 1
Type: Research Article
ISSN: 1475-7702

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Article
Publication date: 7 June 2011

Juan Wang

The aim of this paper is to examine how informed traders, i.e. transient institutional investors that actively trade on information to maximize investment profits, use…

Abstract

Purpose

The aim of this paper is to examine how informed traders, i.e. transient institutional investors that actively trade on information to maximize investment profits, use insider trading signals in addition to accounting numbers to mitigate future abnormal returns.

Design/methodology/approach

Using a sample of 44,843 firm‐quarters from 1988 to 2001 in the USA, the paper examines how informed investors use insider trading signals and the extent to which the use of these signals by informed investors impacts insiders' future abnormal returns from trading.

Findings

This study finds that the change in transient institutional ownership in the next‐quarter is positively associated with net insider trading in the current quarter, after controlling for accounting information (including total accruals, unexpected earnings, etc.). In addition, this study finds that insider profits decrease in transient institutional ownership, consistent with the notion that trading by informed investors limits insider profits.

Research limitations/implications

The institutional ownership data are only available on a quarterly basis, which may not capture institutional investors' immediate response to insider trading signals.

Originality/value

This study provides systematic evidence on how informed traders use insider trading signals. This study adds to existing knowledge of the information environment of institutional investors by showing that transient institutional investors use insider trading signals in addition to accounting information in making investment decisions. Moreover, this study contributes to the literature on the determinants of insider profits by providing evidence that informed trading by investors has incremental power to explain insider profits.

Details

International Journal of Accounting & Information Management, vol. 19 no. 2
Type: Research Article
ISSN: 1834-7649

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Article
Publication date: 14 October 2019

Nagesh Babu Balam and Akhilesh Gupta

Modelling accurately the transient behaviour of natural convection flow in enclosures been a challenging task because of a variety of numerical errors which have limited…

Abstract

Purpose

Modelling accurately the transient behaviour of natural convection flow in enclosures been a challenging task because of a variety of numerical errors which have limited achieving the higher order temporal accuracy. A fourth-order accurate finite difference method in both space and time is proposed to overcome these numerical errors and accurately model the transient behaviour of natural convection flow in enclosures using vorticity–streamfunction formulation.

Design/methodology/approach

Fourth-order wide stencil formula with appropriate one-sided difference extrapolation technique near the boundary is used for spatial discretisation, and classical fourth-order Runge–Kutta scheme is applied for transient term discretisation. The proposed method is applied on two transient case studies, i.e. convection–diffusion of a Gaussian Pulse and Taylor Vortex flow having analytical solution.

Findings

Error magnitude comparison and rate of convergence analysis of the proposed method with these analytical solutions establish fourth-order accuracy and prove the ability of the proposed method to truly capture the transient behaviour of incompressible flow. Also, to test the transient natural convection flow behaviour, the algorithm is tested on differentially heated square cavity at high Rayleigh number in the range of 103-108, followed by studying the transient periodic behaviour in a differentially heated vertical cavity of aspect ratio 8:1. An excellent comparison is obtained with standard benchmark results.

Research limitations/implications

The developed method is applied on 2D enclosures; however, the present methodology can be extended to 3D enclosures using velocity–vorticity formulations which shall be explored in future.

Originality/value

The proposed methodology to achieve fourth-order accurate transient simulation of natural convection flows is novel, to the best of the authors’ knowledge. Stable fourth-order vorticity boundary conditions are derived for boundary and external boundary regions. The selected case studies for comparison demonstrate not only the fourth-order accuracy but also the considerable reduction in error magnitude by increasing the temporal accuracy. Also, this study provides novel benchmark results at five different locations within the differentially heated vertical cavity of aspect ratio 8:1 for future comparison studies.

Details

International Journal of Numerical Methods for Heat & Fluid Flow, vol. 30 no. 3
Type: Research Article
ISSN: 0961-5539

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Article
Publication date: 2 October 2017

Sujun Dong, Fanchao Meng, Dechun Guo and Hongling Kang

The time of tightly coupled transient calculation and the accuracy of conventional loosely coupled algorithm make it difficult to meet the engineering design requirements…

Abstract

Purpose

The time of tightly coupled transient calculation and the accuracy of conventional loosely coupled algorithm make it difficult to meet the engineering design requirements for long-term conjugate heat transfer (CHT) problems. The purpose of this paper is to propose a new loosely coupled algorithm with sufficient accuracy and less calculation time on the basis of the quasi-steady flow field. Through this algorithm, it will be possible to reduce the update frequency of the flow field and devise a strategy by which to reasonably determine the update steps.

Design/methodology/approach

In this paper, the new algorithm updates the flow field by solving the steady governing equations in the fluid region and by calculating the transient temperature distribution until the next update of the fluid flow, by means of solving the transient energy equations in the entire computational domain. The authors propose a strategy by which to determine the update step, by using the engineering empirical formula of the Nusselt number, on the basis of the changes of the inlet and outlet boundary conditions.

Findings

Taking a duct heated by an inner forced air flow heating process as an example, the comparison results for the tightly coupled transient calculation by Fluent software shows that the new algorithm is able to significantly reduce the calculation time of the transient temperature distribution with reasonable accuracy. For example, the respective computing times are reduced to 22.8 and 40 per cent, while the duct wall temperature deviations are 7 and 5 per cent, using the two flow update time steps of 100 and 50 s on the variable inlet-flow rate conditions.

Originality/value

The new algorithm outlined in this paper further improves the calculated performance and meets the engineering design requirements for long-term CHT problems.

Details

Engineering Computations, vol. 34 no. 7
Type: Research Article
ISSN: 0264-4401

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Article
Publication date: 1 April 1994

Z.R. Hu, P.A. Mawby, M.S. Towers and K. Board

The transient thermal behaviour, based on a rigorous transient thermodynamic treatment, of a power VDMOS transistor during turn‐off is presented. The time variation of the…

Abstract

The transient thermal behaviour, based on a rigorous transient thermodynamic treatment, of a power VDMOS transistor during turn‐off is presented. The time variation of the interior lattice temperature within the device is calculated by self‐consistently solving the fully coupled Poisson's equation and transient electron continuity equation together with the transient heat flow equation. The simulation takes account of temperature dependent heat conduction and capacity and includes thermoelectric currents due to temperature gradient. To make the transient thermal simulation more robust, a new analytical expression for heat capacity is used.

Details

COMPEL - The international journal for computation and mathematics in electrical and electronic engineering, vol. 13 no. 4
Type: Research Article
ISSN: 0332-1649

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Article
Publication date: 5 March 2018

Wei Li, Leilei Ji, Weidong Shi, Ling Zhou, Xiaoping Jiang and Yang Zhang

The purpose of this paper is to experimentally and numerically study the transient hydraulic impact and overall performance during startup accelerating process of mixed-flow pump.

Abstract

Purpose

The purpose of this paper is to experimentally and numerically study the transient hydraulic impact and overall performance during startup accelerating process of mixed-flow pump.

Design/methodology/approach

In this study, the impeller rotor vibration characteristics during the starting period under the action of fluid–structure interaction was investigated, which is based on the bidirectional synchronization cooperative solving method for the flow field and impeller structural response of the mixed-flow pump. Experimental transient external characteristic and the transient dimensionless head results were compared with the numerical calculation results, to validate the accuracy of numerical calculation method. Besides, the deformation and dynamic stress distribution of the blade under the stable rotating speed and accelerating condition were studied based on the bidirectional fluid–structure interaction.

Findings

The results show that the combined action of complex hydrodynamic environment and impeller centrifugal force in the startup accelerating process makes the deformation and dynamic stress of blade have the rising trend of reciprocating oscillation. At the end of acceleration, the stress and strain appear as transient peak values and the transient effect is nonignorable. The starting acceleration has a great impact on the deformation and dynamic stress of blade, and the maximum deformation near the rim of impeller outlet edge increases 5 per cent above the stable condition. The maximum stress value increases by about 68.7 per cent more than the steady-state condition at the impeller outlet edge near the hub. The quick change of rotating speed makes the vibration problem around the blade tip area more serious, and then it takes the excessive stress concentration and destruction at the blade root.

Originality/value

This study provides basis and reference for the safety operation of pumps during starting period

Details

Engineering Computations, vol. 35 no. 1
Type: Research Article
ISSN: 0264-4401

Keywords

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