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Article
Publication date: 3 August 2012

Noa Aharony

This study aims to understand how three political leaders – the Prime Minister of Israel, Benjamin Netanyahu; the Prime Minister of Britain, David Cameron; and the President of…

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Abstract

Purpose

This study aims to understand how three political leaders – the Prime Minister of Israel, Benjamin Netanyahu; the Prime Minister of Britain, David Cameron; and the President of the United States of America, Barack Obama – communicate through Twitter.

Design/methodology/approach

This paper presents an analysis of tweets produced between August and October 2010 by three political leaders, using statistical descriptive analysis and content analysis.

Findings

The research shows that the US President tweets more than the other leaders, with the British Prime Minister tweeting the least, and that all three leaders use Twitter for both transparency and outreach.

Originality/value

As Twitter has become widespread over the last few years, and several studies have focused on Twitter and its impact on different sectors in our society, it is interesting to focus on political leaders' use of Twitter.

Details

Online Information Review, vol. 36 no. 4
Type: Research Article
ISSN: 1468-4527

Keywords

Article
Publication date: 20 December 2023

Matt Johnson and Rob Barlow

The purpose of this paper is to explore the prospect of using neurophenomenology to understand, design and test phygital consumer experiences. It aims to clarify interpretivist…

Abstract

Purpose

The purpose of this paper is to explore the prospect of using neurophenomenology to understand, design and test phygital consumer experiences. It aims to clarify interpretivist approaches to consumer neuroscience, wherein theoretical models of individual phenomenology can be combined with modern neuroimaging techniques to detect and interpret the first-person accounts of phygital experiences.

Design/methodology/approach

The argument is conceptual in nature, building its position through synthesizing insights from phenomenology, phygital marketing, theoretical neuroscience and other related fields.

Findings

Ultimately, the paper presents the argument that interpretivist neuroscience in general, and neurophenomenology specifically, provides a valuable new perspective on phygital marketing experiences. In particular, we argue that the approach to studying first-personal experiences within the phygital domain can be significantly refined by adopting this perspective.

Research limitations/implications

One of the primary goals of this paper is to stimulate a novel approach to interpretivist phygital research, and in doing so, provide a foundation by which the impact of phygital interventions can be empirically tested through neuroscience, and through which future research into this topic can be developed. As such, the success of such an approach is yet untested.

Originality/value

Phygital marketing is distinguished by its focus on the quality of subjective first-personal consumer experiences, but few papers to date have explored how neuroscience can be used as a tool for exploring these inner landscapes. This paper addresses this lacuna by providing a novel perspective on “interpretivist neuroscience” and proposes ways that current neuroscientific models can be used as a practical methodology for addressing these questions.

Details

Qualitative Market Research: An International Journal, vol. ahead-of-print no. ahead-of-print
Type: Research Article
ISSN: 1352-2752

Keywords

Article
Publication date: 5 May 2015

Fabien Hospital, Marc Budinger, Aurélien Reysset and Jean-Charles Maré

This paper aims to propose preliminary design models of actuator housing that enable various geometries to be compared without requiring detailed knowledge of the actuator…

Abstract

Purpose

This paper aims to propose preliminary design models of actuator housing that enable various geometries to be compared without requiring detailed knowledge of the actuator components. Aerospace actuation systems are currently tending to become more electrical and fluid free. Methodologies and models already exist for designing the mechanical and electrical components, but the actuator housing design is still sketchy.

Design/methodology/approach

The approach is dedicated to linear actuators, the most common in aerospace. With special attention paid to mechanical resistance to the vibratory environment, simplified geometries are proposed to facilitate the generation of an equivalent formal development. The vibratory environment imposes the sizing of the actuator housing. Depending on the expected level of details and to vibration boundary conditions, three levels of modeling have been realized.

Findings

This paper shows that the vibrations induced by aircraft environment are not design drivers for conventional hydraulic actuators but can be an issue for new electromechanical actuators. The weight of the latter can be optimized through a judicious choice of the diameter of the housing.

Practical implications

This approach is applied to a comparison of six standard designs of linear actuator geometries after validation of the consistency of the different models. Early conclusions can be drawn and may lead to design perspectives for the definition of actuator architecture and the optimization of the design.

Originality/value

This paper has demonstrated the importance of the vibratory environment in the design of linear actuator housing, especially for electro-mechanical actuators with important strokes. Developed analytical models can be used for the overall design and optimization of these new aerospace actuators.

Details

Aircraft Engineering and Aerospace Technology: An International Journal, vol. 87 no. 3
Type: Research Article
ISSN: 0002-2667

Keywords

Article
Publication date: 14 September 2010

Ekkehard Bolte and Burghard Kipp

The purpose of this paper is to provide a thermal model for apparatus and assemblies, especially electrical drives, capable of predicting the temperature distribution under steady…

Abstract

Purpose

The purpose of this paper is to provide a thermal model for apparatus and assemblies, especially electrical drives, capable of predicting the temperature distribution under steady state or transient operational conditions.

Design/methodology/approach

Starting from Fourier's partical differential equation, the regions of interest are represented by lumped parameters, i.e. by R, C‐networks, and the heat flow is modelled by a system of non‐linear ordinary differential equations. Thus, the thermal equivalent circuit model is established. Next step is an analytical approach to predict the temperature functions in the considered sub‐regions. The presented analysis is validated by a benchmark example and by measurements.

Findings

The usefulness of the model is demonstrated by means of benchmark calculations and comparisons with measurements. It is relevant to the design stage as well as to the performance prediction, particularly with respect to on‐line control techniques.

Research limitations/implications

The accuracy of the model would benefit from further research into the mathematical representation of the heat flow by thermal resistances and capacitances, particularly taking into account the temperature dependency.

Practical implications

The paper presents a valuable tool for engineers involved in temperature problems.

Originality/value

Efficient analytical thermal analysis is presented in this paper, taking into account a large number of potentially non‐linear elements (sub‐regions).

Details

COMPEL - The international journal for computation and mathematics in electrical and electronic engineering, vol. 29 no. 5
Type: Research Article
ISSN: 0332-1649

Keywords

Article
Publication date: 30 April 2019

Mariusz Baranski

This paper aims to elaborate the method and algorithm for the analysis of the influence of high temperature on electric and thermal properties of the materials, as well as thermal…

Abstract

Purpose

This paper aims to elaborate the method and algorithm for the analysis of the influence of high temperature on electric and thermal properties of the materials, as well as thermal phenomena process.

Design/methodology/approach

The paper presents specially author’s software for the transient finite element analysis of coupled electromagnetic-thermal problems in a squirrel cage induction motor. The numerical implementation is based on finite element method and step-by-step algorithm. The nonlinearity of a magnetic circuit, the dependence of electric and thermal parameters on temperature, the movement of a rotor and skewed rotor bars have been taken into account. To verify the developed algorithm and software, the influence of high ambient temperature on selected electromagnetic and thermal parameters of the induction motor was examined.

Findings

The results of simulations compared with measurements confirm the adequacy of this approach to the analysis of coupled electromagnetic-thermal problems.

Research limitations/implications

3D effects have only been taken into account when using quasi-3D techniques (e.g. the multi-slice for skewed rotor slots).

Practical implications

The author’s software developed can be useful in the analysis and design of squirrel cage motors, especially motors working in high ambient temperature.

Originality/value

The paper offers appropriate author’s software for the transient and steady-state analysis of coupled electromagnetic and thermal problems in squirrel cage motors with skewed slots.

Details

COMPEL - The international journal for computation and mathematics in electrical and electronic engineering, vol. 38 no. 4
Type: Research Article
ISSN: 0332-1649

Keywords

Article
Publication date: 9 September 2013

Maximilian Schrittwieser, Oszkár Bíró, Ernst Farnleitner and Gebhard Kastner

The purpose of this work is to propose a numerical method based on computational fluid dynamics (CFD) for reconstructing the heat transfer inside electrical machines. The used…

Abstract

Purpose

The purpose of this work is to propose a numerical method based on computational fluid dynamics (CFD) for reconstructing the heat transfer inside electrical machines. The used conjugate heat transfer (CHT) method takes heat convection and heat conduction into account to determine the temperature rise and the thermal losses in stator duct models of large hydro generators. Three different test cases are studied with different slot section components. The numerical models are validated with measurement data for a range of different mass flow rates.

Design/methodology/approach

The work presented is based on the combination of two complementary approaches, namely numerical simulation and measurements. The measured data for the air mass flow and the heat losses are used as boundary conditions for the identification of the temperature distribution in the solid and fluid domains (using a commercial software for CFD). The CHT method is an additional application of CFD and is used to solve the energy equations in the solid domains. Therefore, it is possible to define a thermal source in the solid domains.

Findings

The data obtained by the numerical computation are compared with measurement data for different mass flow rates of the cooling fluid. The quality of the computed values depending on the different mass flow rates shows a good agreement with the measured data. The temperature distribution in the solid domains depending on different material properties is also pointed out in this investigation.

Research limitations/implications

The topic describes a method for solving the heat transfer in the fluid as well as the solid domains. The losses can be defined as sources in the solid domains, e.g. copper and iron, obtained by electromagnetic calculations. This boundary condition defines the situation more accurately than, for example, a constant value of the heat flux or the temperature at the walls like in common used CFD simulations. Another advantage of CFD over other approaches is the consideration of the actual wall heat transfer coefficient.

Originality/value

The presented investigations show relevant issues influencing the thermal behaviour of electrical machines.

Details

COMPEL: The International Journal for Computation and Mathematics in Electrical and Electronic Engineering, vol. 32 no. 5
Type: Research Article
ISSN: 0332-1649

Keywords

Article
Publication date: 18 September 2018

Pichai Aree

An important characteristic of most induction motors is speed- or slip-torque curve. A simplified Kloss formula is widely used for describing speed-torque characteristic because…

182

Abstract

Purpose

An important characteristic of most induction motors is speed- or slip-torque curve. A simplified Kloss formula is widely used for describing speed-torque characteristic because it is fairly simple. Only two parameters related to break-down torque and break-down slip are regarded as input parameters. Because this simplified formula ignores an unknown parameter that is a ratio between Thevenin’s and rotor resistances, an accurate torque curve characteristic may not be fully obtained over an entire speed range. Moreover, the conventional Kloss formula does not offer a speed-torque curve calculation when motor’s supply voltages and frequencies are deviated from rated values. Hence, the purpose of this paper is to present an extension of Kloss formula, which allows a more precise estimation of speed-torque and speed-current curves of single-cage three-phase induction motors over a wide range of speeds at different motor’s operating voltages, frequencies and rotor-circuit resistances.

Design/methodology/approach

The analytical approach is mainly used for determining all key parameters in the Kloss formula using a known set of data such as rated torque, starting torque, break-down torque and rated speed, in which they can be obtained from motor’s manufacturer.

Findings

The speed-torque and speed-current curves taken from laboratory measurements are compared with those from the calculations. Good agreements between them are fully observed.

Originality/value

This analytical approach is useful in providing an accurate speed-torque and speed-current curves required for most steady-state analysis.

Details

COMPEL - The international journal for computation and mathematics in electrical and electronic engineering, vol. 37 no. 6
Type: Research Article
ISSN: 0332-1649

Keywords

Article
Publication date: 7 September 2015

M. Schrittwieser, O. Bíró, E. Farnleitner and G. Kastner

The purpose of this paper is to approximate the convective heat transfer using a few non-dimensional parameters in the design process of large synchronous machines. The computed…

Abstract

Purpose

The purpose of this paper is to approximate the convective heat transfer using a few non-dimensional parameters in the design process of large synchronous machines. The computed convective wall heat transfer coefficient can be used in circuit models or can be defined in numerical heat conduction (HC) models to compute the thermal field in the solid domains without the time consuming computation of the fluid domain.

Design/methodology/approach

Computational fluid dynamics (CFD) has been used to include a wide range of different designs, operating conditions and cooling schemes to ensure accurate results for a wide range of possible machines. Neural networks are used to correlate the computed heat transfer coefficients to various design parameters. The data set needed to define the weights and bias layers in the network has been obtained by several CFD simulations. A comparison of the evaluated solid temperatures with those obtained using the conjugate heat transfer (CHT) method has been carried out. The results have also been validated with calorimetric measurements.

Findings

The validation of the HC model has shown that this model is capable of yielding accurate results in a few minutes, in contrast to the several hours needed by the CHT solution. The workflow to determine the convective heat transfer in a specific part of an electrical machine has been also been established. The approximation of the convective wall heat transfer coefficient is shown to be obtainable in sufficient detail by using a neural network.

Research limitations/implications

The paper describes a method to approximate the convective heat transfer accurately in a few seconds, which is very useful in the design process. The heat convection can then be characterized in a HC model including the solid domains only. The losses can be defined as sources in the solid domains, e.g. copper and iron, obtained by electromagnetic calculations and the thermal field can hence be easily computed in these parts. This HC model has the main advantage that the time consuming computation of the fluid domain is avoided.

Originality/value

The novelty in this work is the approximation of the convective heat transfer by using a neural network with an accuracy of less than 5 percent as well as the development of a HC model to compute the temperature in the solid domains. The investigations presented pinpoint relevant issues influencing the thermal behavior of electrical machines.

Details

COMPEL: The International Journal for Computation and Mathematics in Electrical and Electronic Engineering, vol. 34 no. 5
Type: Research Article
ISSN: 0332-1649

Keywords

Article
Publication date: 1 July 2005

Michael Nwogugu

The purposes of this article are to evaluate models of stock market risk developed by Robert Engle, and related models (ARCH, GARCH, VAR, etc.); to establish whether prospect…

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Abstract

Purpose

The purposes of this article are to evaluate models of stock market risk developed by Robert Engle, and related models (ARCH, GARCH, VAR, etc.); to establish whether prospect theory, cumulative prospect theory, expected utility theory, and market‐risk models (ARCH, GARCH, VAR, etc.) are related and have the same foundations.

Design/methodology/approach

The author critiques existing academic work on risk, decision making, prospect theory, cumulative prospect theory, expected utility theory, VAR and other market‐risk models (ARCH, GARCH, etc.) and analyzes the shortcomings of various measures of risk (standard deviation, VAR, etc.).

Findings

Prospect theory, cumulative prospect theory, expected utility theory, and market‐risk models are conceptually the same and do not account for many facets of risk and decision making. Risk and decision making are better quantified and modeled using a mix of situation‐specific dynamic, quantitative, and qualitative factors. Belief systems (a new model developed by the author) can better account for the multi‐dimensional characteristics of risk and decision making. The market‐risk models developed by Engle and related models (ARCH, GARCH, VAR, etc.) are inaccurate, do not incorporate many factors inherent in stock markets and asset prices, and thus are not useful and accurate in many asset markets.

Research limitations/implications

Areas for further research include: development of dynamic market‐risk models that incorporate asset‐market psychology, liquidity, market size, frequency of trading, knowledge differences among market participants, and trading rules in each market; and further development of concepts in belief systems.

Practical implications

Decision making and risk assessment are multi‐criteria processes that typically require some processing of information, and thus cannot be defined accurately by rigid quantitative models. Existing market‐risk models are inaccurate – many international banks, central banks, government agencies, and financial institutions use these models for risk management, capital allocation, portfolio management, and investments, and thus the international financial system may be compromised.

Originality/value

The critiques, ideas, and new theories in the article were all developed by the author. The issues discussed in the article are relevant to a multiplicity of situations and people in any case that requires decision making and risk assessment.

Details

The Journal of Risk Finance, vol. 6 no. 3
Type: Research Article
ISSN: 1526-5943

Keywords

Article
Publication date: 2 March 2015

Marcin Lefik

The purpose of this paper is to include thermal analysis in the design process of permanent magnet synchronous motor (PMSM). The additional objective is a comparison of PMSM with…

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Abstract

Purpose

The purpose of this paper is to include thermal analysis in the design process of permanent magnet synchronous motor (PMSM). The additional objective is a comparison of PMSM with induction motor (IM) in terms of thermal phenomena.

Design/methodology/approach

Numerical investigation using commercial software MotorSolve was performed. Parameterized models of PMSM and IM were used. Calculations of motor parameters and temperature distribution were made using Finite Element Method.

Findings

The results of the calculations show that thermal calculations should be included in the design process because the maximum permissible operating temperature of permanent magnets should not be exceeded. A comparative analysis of PMSM and IM shows that the PMSM has better parameters than the IM which was used as a base of the PMSM construction.

Research limitations/implications

Computational models should be verified experimentally on a physical model or by using more complex numerical models. In the case of IM thermal calculations, a method of air speed calculation should be proposed. Air speed is a parameter that is necessary in thermal analysis of IM, but during the design process it is unknown.

Originality/value

This paper presents modelling methodology of 3D transient thermal field coupled with electromagnetic field applied in a three-phase IM at rated load conditions. This paper presents a design strategy which includes thermal analysis of the designed PMSM. Moreover, the paper shows a comparison between PMSM and IM indicating advantages of PMSM over IM.

Details

COMPEL: The International Journal for Computation and Mathematics in Electrical and Electronic Engineering, vol. 34 no. 2
Type: Research Article
ISSN: 0332-1649

Keywords

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