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Article
Publication date: 4 October 2018

Ali Karami-Mollaee, Hamed Tirandaz and Oscar Barambones

The purpose of this paper is position control scheme for a servo induction motor (SIM) with uncertainty has been designed using a new observer issue and a dynamic sliding mode…

87

Abstract

Purpose

The purpose of this paper is position control scheme for a servo induction motor (SIM) with uncertainty has been designed using a new observer issue and a dynamic sliding mode control (DSMC).

Design/methodology/approach

In DSMC, the chattering is removed due to the integrator (or a low-pass filter) which is placed before the input control of the plant. However, in DSMC, the augmented system has one dimension bigger than the actual system (if integrator is used) and then, the plant model should be completely known. To solve this problem in SIM, the use of a new adaptive state observer (ASO) is proposed.

Findings

The advantage of the proposed approach is to maintain the system controlled under the external load torque variations. Then, the load variations do not affect the motor positioning. Moreover, it is demonstrated that the observer error converges to zero based on the Lyapunov stability theory.

Originality/value

The knowledge of the upper bound for the system uncertainty is not necessary in an adaptive state observer, which is important in practical implementation. Simulation results are presented to demonstrate the performance of the proposed approach.

Details

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

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Article
Publication date: 27 April 2012

Mohsen Rabbani and Khosrow Maleknejad

The purpose of this paper is to explain the choice of Alpert multi‐wavelet as basis functions to discrete Fredholm integral equation of the second kind by using Petrov‐Galerkin…

148

Abstract

Purpose

The purpose of this paper is to explain the choice of Alpert multi‐wavelet as basis functions to discrete Fredholm integral equation of the second kind by using Petrov‐Galerkin method.

Design/methodology/approach

In this process, two kinds of matrices are obtained from inner product between basis of test space and trial space; some of them are diagonal with positive elements and some others are invertible. These matrices depend on type of selection of test and trial space basis.

Findings

In this process, solution of Fredholm integral equation of the second kind is found by solving the generated system of linear equations.

Originality/value

In previous work, convergence of Petrov‐Galerkin method has been discussed with some restrictions on degrees of chosen polynomial basis, but in this paper convergence is obtained for every degree. In point of computation, because of appearance of diagonal and invertible matrices, a small dimension system with a more accurate solution is obtained. The numerical examples illustrate these facts.

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Article
Publication date: 29 May 2019

Penggao Zhang, Boqin Gu, Jianfeng Zhou and Long Wei

The purpose of this study is to investigate the heat transfer characteristics in a spiral groove mechanical seal lubricated by magnetic fluid.

152

Abstract

Purpose

The purpose of this study is to investigate the heat transfer characteristics in a spiral groove mechanical seal lubricated by magnetic fluid.

Design/methodology/approach

The viscosity relationship of magnetic fluid in external electromagnetic field was deduced. The temperature distribution of sealing ring was calculated by the method of separation variables.

Findings

It has been found that the rotating ring absorbs most friction heat. The temperatures on the end faces of rotating ring and stationary ring decrease from inner radius to outer radius, the temperature of magnetic fluid film decreases from rotating ring to stationary ring and the highest temperature of the sealing system is at the junction of the inner radius and the end face of rotating ring.

Originality/value

Selecting the sealing rings with higher thermal conductivity and reducing the volume fraction of solid particles in magnetic fluid can reduce the temperature of sealing system effectively.

Details

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

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Article
Publication date: 1 October 1995

K. Karami and S. Frost

Describes a socio‐psychological study performed in a residentialarea of Tehran, exposed to both aircraft and traffic noise. Analysis ofresidents′ responses to road traffic noise…

4576

Abstract

Describes a socio‐psychological study performed in a residential area of Tehran, exposed to both aircraft and traffic noise. Analysis of residents′ responses to road traffic noise shows that although aircraft noise is the chief environmental problem it fails to mask the nuisance of traffic noise.

Details

Environmental Management and Health, vol. 6 no. 4
Type: Research Article
ISSN: 0956-6163

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Book part
Publication date: 25 November 2024

C. Cozette Comer

This chapter explores the financial aspects of resolving the COVID-19 pandemic, including respondents’ feelings about their country going into more debt and perceptions of how…

Abstract

This chapter explores the financial aspects of resolving the COVID-19 pandemic, including respondents’ feelings about their country going into more debt and perceptions of how public funding should be spent. A factor analysis reveals spending priorities could be classified into three broad areas: Welfare (e.g., funding social welfare and research), Development (e.g., business, infrastructure, and international development), and Security (e.g., police and military). Finnish residents were more likely to support spending on welfare while Americans were more likely to support spending on development. There was no difference between the nations for supporting spending on the security state. Importantly, confidence in institutions was negatively correlated with supporting spending on welfare but positively correlated with supporting spending in development and security. Potentially confounding factors such as having been sick with COVID-19, worrying about the pandemic, news consumption about COVID-19, social capital, life satisfaction, and feelings toward the future were included in the model to determine if these mediated or moderated the relationship between confidence in institutions and support for various types of spending. While none of the variables mediated the relationship between confidence and spending priorities, worrying about COVID-19, social isolation, and social capital were related to increased support for spending on welfare, while being sick with COVID-19 and social capital were related to increased support for spending on the security state. The analyses reveal that pandemic-related factors influence spending priorities, but these did not overcome the influence of demographic factors and the general level of confidence one had in the institutions of society.

Details

Perceptions of a Pandemic: A Cross-Continental Comparison of Citizen Perceptions, Attitudes, and Behaviors During Covid-19
Type: Book
ISBN: 978-1-83608-625-3

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Article
Publication date: 1 May 1999

Khodabakshsh Karami and Stan Frost

Noise measurement and social questionnaire surveys in three residential areas around Mehrabad International Airport (Tehran, Iran) were based upon randomly selected dwellings in…

1223

Abstract

Noise measurement and social questionnaire surveys in three residential areas around Mehrabad International Airport (Tehran, Iran) were based upon randomly selected dwellings in each area. A total of 193 individuals responded and many are annoyed and dissatisfied with aircraft noise and in consequence they would like to move. Aircraft noise is the strongest negative environmental factor affecting the residents in the vicinity of Mehrabad Airport and it could be a hazard for their health.

Details

Environmental Management and Health, vol. 10 no. 2
Type: Research Article
ISSN: 0956-6163

Keywords

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Book part
Publication date: 16 June 2021

Aidin Salamzadeh and Veland Ramadani

The Iranian entrepreneurial ecosystem has grown dramatically during the past decade. Several improvements have been made at different levels, and, therefore, one could witness its…

Abstract

The Iranian entrepreneurial ecosystem has grown dramatically during the past decade. Several improvements have been made at different levels, and, therefore, one could witness its unique achievements. Digital entrepreneurs are an integral part of this ecosystem, as most of the early achievements are the results of their proactive behaviors. Hopefully, the number of female digital entrepreneurs has increased, and their entrepreneurial activities have profoundly changed the competition scene. Therefore, this chapter provides a better understanding of the multilayered entrepreneurial ecosystem of Iran and then elaborates how female entrepreneurs are positioned in this ecosystem. Moreover, six well-known award-winning female digital entrepreneurs are introduced, and their challenges are scrutinized accordingly through narrative research. Finally, the chapter concludes with some remarks and directions for future research.

Details

The Emerald Handbook of Women and Entrepreneurship in Developing Economies
Type: Book
ISBN: 978-1-80071-327-7

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Article
Publication date: 16 October 2009

Rahman Farnoosh and Ebrahimi Morteza

The purpose of this paper is to provide a Monte Carlo variance reduction method based on Control variates to solve Fredholm integral equations of the second kind.

508

Abstract

Purpose

The purpose of this paper is to provide a Monte Carlo variance reduction method based on Control variates to solve Fredholm integral equations of the second kind.

Design/methodology/approach

A numerical algorithm consisted of the combined use of the successive substitution method and Monte Carlo simulation is established for the solution of Fredholm integral equations of the second kind.

Findings

Owing to the application of the present method, the variance of the solution is reduced. Therefore, this method achieves several orders of magnitude improvement in accuracy over the conventional Monte Carlo method.

Practical implications

Numerical tests are performed in order to show the efficiency and accuracy of the present paper. Numerical experiments show that an excellent estimation on the solution can be obtained within a couple of minutes CPU time at Pentium IV‐2.4 GHz PC.

Originality/value

This paper provides a new efficient method to solve Fredholm integral equations of the second kind and discusses basic advantages of the present method.

Details

Kybernetes, vol. 38 no. 9
Type: Research Article
ISSN: 0368-492X

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Article
Publication date: 30 December 2022

Kayhan Tajeddini, Taylan Budur, Thilini Chathurika Gamage, Ahmet Demir, Halil Zaim and Ramazan Topal

This paper investigates the effect of diversity management on employees' innovative work behavior (IWB) through human resource management (HRM) and affective commitment (AC).

2200

Abstract

Purpose

This paper investigates the effect of diversity management on employees' innovative work behavior (IWB) through human resource management (HRM) and affective commitment (AC).

Design/methodology/approach

Data were collected from 358 employees of small- and medium-sized enterprises in the Kurdistan Region of Iraq. The hypothesized model has been evaluated using structural equation modeling.

Findings

Findings suggest that workforce diversity management directly and significantly affected HRM and AC. Furthermore, findings revealed that HRM significantly influenced both employees' IWB and AC, while AC had a significant positive influence on IWB. Moreover, concerning the indirect effects, AC and HRM significantly mediated the relationship between DM and employees' IWB.

Research limitations/implications

A cross-sectional single source dataset is used to evaluate the hypothesized model.

Originality/value

Grounded in the social exchange and institutional theories, this research fills the gap in the literature by addressing the “black box” of how workforce DM influences employees' IWB while examining the mediating role of employees' AC and firm HRM policies.

Details

Journal of Management Development, vol. 42 no. 1
Type: Research Article
ISSN: 0262-1711

Keywords

Available. Open Access. Open Access
Article
Publication date: 20 August 2024

Miguel Araya-Calvo, Antti Järvenpää, Timo Rautio, Johan Enrique Morales-Sanchez and Teodolito Guillen-Girón

This study compares the fatigue performance and biocompatibility of as-built and chemically etched Ti-6Al-4V alloys in TPMS-gyroid and stochastic structures fabricated via Powder…

531

Abstract

Purpose

This study compares the fatigue performance and biocompatibility of as-built and chemically etched Ti-6Al-4V alloys in TPMS-gyroid and stochastic structures fabricated via Powder Bed Fusion Laser Beam (PBF-LB). This study aims to understand how complex lattice structures and post-manufacturing treatment, particularly chemical etching, affect the mechanical properties, surface morphology, fatigue resistance and biocompatibility of these metamaterials for biomedical applications.

Design/methodology/approach

Selective Laser Melting (SLM) technology was used to fabricate TPMS-gyroid and Voronoi stochastic designs with three different relative densities (0.2, 0.3 and 0.4) in Ti-6Al-4V ELI alloy. The as-built samples underwent a chemical etching process to enhance surface quality. Mechanical characterization included static compression and dynamic fatigue testing, complemented by scanning electron microscopy (SEM) for surface and failure analysis. The biocompatibility of the samples was assessed through in-vitro cell viability assays using the Alamar Blue assay and cell proliferation studies.

Findings

Chemical etching significantly improves the surface morphology, mechanical properties and fatigue resistance of both TPMS-gyroid and stochastic structures. Gyroid structures demonstrated superior mechanical performance and fatigue resistance compared to stochastic structures, with etching providing more pronounced benefits in these aspects. In-vitro biocompatibility tests showed high cytocompatibility for both as-built and etched samples, with etched samples exhibiting notably improved cell viability. The study also highlights the importance of design and post-processing in optimizing the performance of Ti64 components for biomedical applications.

Originality/value

The comparative analysis between as-built and etched conditions, alongside considering different lattice designs, provides valuable information for developing advanced biomedical implants. The demonstration of enhanced fatigue resistance and biocompatibility through etching adds significant value to the field of additive manufacturing, suggesting new avenues for designing and post-processing implantable devices.

Details

Rapid Prototyping Journal, vol. 30 no. 11
Type: Research Article
ISSN: 1355-2546

Keywords

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