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Article
Publication date: 1 April 1993

P.P. Ciufo, C.D. Cook and F. Naghdy

While robots have proved to be ideal for the manipulation of single articles accurately in three dimensions, they are not as cost‐effective in industry for tasks which require…

55

Abstract

While robots have proved to be ideal for the manipulation of single articles accurately in three dimensions, they are not as cost‐effective in industry for tasks which require simultaneous manipulations of several parts. In addition, changes in part geometry often necessitate the redesign of the gripping device, modification to the sensors and re‐examination of the grasping strategies to be used. These tasks are time consuming and add to the inefficiency of the approach.

Details

Assembly Automation, vol. 13 no. 4
Type: Research Article
ISSN: 0144-5154

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Article
Publication date: 19 August 2021

Morteza Ghaseminezhad, Aref Doroudi, Seyed Hossein Hosseinian and Alireza Jalilian

Voltage fluctuation (flicker) is a power quality disturbance that can produce several undesirable effects on industrial equipment. This paper aims to present the methodology and…

84

Abstract

Purpose

Voltage fluctuation (flicker) is a power quality disturbance that can produce several undesirable effects on industrial equipment. This paper aims to present the methodology and results of investigations undertaken to examine the speed and torque of an induction motor (IM) under voltage fluctuation conditions.

Design/methodology/approach

The IM response to different characteristics of voltage fluctuations is presented. It will be shown that under a special condition the IM torque can even reach two times the rated torque. To show how this occurs, a qualitative discussion is given on the motor response by linearized equations.

Findings

The small-signal analysis was used to determine the frequency which leads to maximum speed fluctuations. It was shown that, if the motor is excited with a modulation frequency (resonant frequency) which is one of its natural frequencies (modes), the mode will act as a fluctuating amplifier and greatly increase the amplitude of torque and speed fluctuations. Sensitivity analysis is also carried out to evaluate the influence of motor parameters on the resonance frequency. The results show that the resonance frequency is not affected at all by the changes in magnetizing reactance. This has been shown that magnetic saturation does not have any impact on the resonance frequency. The most effective parameters are rotor and stator resistances.

Originality/value

With the increasing popularity and use of arc furnace loads in the metallurgy industry and due to the wide application of large IMs in the industry, it is possible that the frequency of torque pulsation locates near a natural frequency and then will create an oscillation with a large magnitude, potentially leading to accelerated fatigue or severe damage of shaft. However, if this phenomenon occurs in industries, the resonance frequency must be filtered from the input voltage. Experimental results on a 1.1 kW, 380 V, 50 Hz, 2 pole IM are used to validate the accuracy of simulation results.

Details

COMPEL - The international journal for computation and mathematics in electrical and electronic engineering , vol. 40 no. 4
Type: Research Article
ISSN: 0332-1649

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Article
Publication date: 11 February 2021

Houda Laabidi, Houda Jouini and Abdelkader Mami

The purpose of this paper is to propose an efficient current control technique based on model predictive control (MPC) for grid-connected wind conversion system. This nonlinear…

68

Abstract

Purpose

The purpose of this paper is to propose an efficient current control technique based on model predictive control (MPC) for grid-connected wind conversion system. This nonlinear strategy is applied for the chopper circuit and grid-tied inverter and compared with other two conventional schemes; a traditional proportional-integral (PI) and sliding mode controller (SMC) using the same switching frequency.

Design/methodology/approach

Firstly, the MPC scheme uses the mathematical model to predict future behaviors of the controlled converter outputs for possible switching states. After that, the optimal voltage vector is selected by minimizing a cost function, which is defined as a sum of the absolute values of the controlled current errors. Then, the corresponding switching signals are applied to the converter switches in the next sampling period to track correctly the reference current. Thus, the MPC scheme ensures a minimal error between the predicted and reference trajectories of the considered variables.

Findings

The MPC-based algorithm presents several benefits in terms of high accuracy control, reduced DC-link voltage ripples during steady-state operation, faster transient response, lower overshoots and disturbance rejection and acceptable total harmonic distortion.

Originality/value

The authors introduce several simulation case studies, using PSIM software package, which prove the reliability and effectiveness of the proposed MPC scheme. Therefore, the MPC performances, during dynamic and steady-state condition, are compared with those obtained by a PI regulator and SMC to highlight the improvements, specifically the transfer of smooth power to the grid.

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Article
Publication date: 31 December 2015

V.N.A. Naikan and Arvind Rathore

The purpose of this paper is to focus on conducting accelerated life tests on aluminium electrolytic capacitors under accelerated temperature and voltage stress to study the…

501

Abstract

Purpose

The purpose of this paper is to focus on conducting accelerated life tests on aluminium electrolytic capacitors under accelerated temperature and voltage stress to study the effect of applied voltage and ambient temperature on the capacitor, its degradation over time, failure data collection, analysis and then modelling the failure times. Principles of DOE are used for studying the effect of temperature and voltage.

Design/methodology/approach

Life tests are conducted at three levels of temperature and applied voltage and the life of capacitor is ascertained at each treatment level. Life variation with voltage and temperature is studied to gain an insight as to how these factors affect the lifetime of the capacitor. The interaction effect of temperature and voltage on capacitor life is also established.

Findings

The life of the capacitor decreases exponentially with temperature and voltage at all the three factor levels. Ambient temperature, applied voltage and their interaction effect significantly affects the life of the capacitor. Applied voltage has the greatest effect followed by ambient temperature and then their interaction effect. Life of the capacitor has been estimated as 4,206 hrs when only voltage is taken as the accelerated stress using Inverse Power Law and as 4,003 hrs when both temperature and voltage are taken as accelerating stress using combination model.

Research limitations/implications

This work consider only decrease in capacitance as the failure criterion. However, as a future scope, it is proposed that test may be conducted by taking into consideration not only the decrease in capacitance as the failure criteria but by monitoring all the performance parameters of the capacitor. This would give a more realistic assessment of life as it is possible that capacitor may have failed much before it reached the lower threshold capacitance value.

Practical implications

This work has lots of practical implications. It shows how DOE approach can be used for ALT data analysis and identification and effect of critical stresses acting on capacitors in real practice. Most critical types of stresses affecting the reliability can thus be controlled to ensure better performance. Product manufactures as well as users will be benefited by such findings. The paper has also illustrated how failure data can generated by degradation analysis using life test data collection at discrete intervals.

Originality/value

The methodology presents an alternative non traditional approach of accelerated life testing, which does not require continuous monitoring of test items. This only requires intermittent monitoring which reduces the need of test resources. Though the degradation study itself is not new but using degradation study for ALT data generation is new. This approach may considerably reduce the test duration and resources used for ALT. DOE approach gives more tangible result to study the effect of various variables on the dependent variable. As DOE approach uses a fractional factorial design, it can be very helpful to conduct life tests with minimum number of test units (only a fraction of full factorial test units). This will considerably reduce the test duration, resources requirement for testing, easier but accurate data analysis, and faster product development, especially when ALT is to be conducted at several stresses simultaneously.

Details

International Journal of Quality & Reliability Management, vol. 33 no. 1
Type: Research Article
ISSN: 0265-671X

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Article
Publication date: 1 April 1976

Roberta A. Scull

This compilation of over 500 United States Government bibliographies is the second annual supplement to BIBLIOGRAPHY OF UNITED STATES GOVERNMENT BIBLIOGRAPHIES 1968–1973 (Pierian…

140

Abstract

This compilation of over 500 United States Government bibliographies is the second annual supplement to BIBLIOGRAPHY OF UNITED STATES GOVERNMENT BIBLIOGRAPHIES 1968–1973 (Pierian Press). Due to the Government Printing Office backlog during 1974, many 1973 and 1974 titles are included in this 1975 Supplement, which should have appeared earlier.

Details

Reference Services Review, vol. 4 no. 4
Type: Research Article
ISSN: 0090-7324

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Book part
Publication date: 14 November 2022

Daniella Bendo, Christine Goodwin-De Faria and Stefania Maggi

In 2020, UNICEF Canada released Report Card 16 revealing that Canada ranks in the bottom tier compared to other wealthy countries in terms of child and youth well-being. The…

Abstract

In 2020, UNICEF Canada released Report Card 16 revealing that Canada ranks in the bottom tier compared to other wealthy countries in terms of child and youth well-being. The Report Card highlights that promoting participation is required to improve this ranking. Recognising the connection between child well-being and participation, this chapter explores youth-serving institutions in Canada to understand how participation materialises in these settings. Through interviews with provincial and territorial Canadian child and youth advocates, this chapter first explores advocate offices that serve young people facing challenges. These are the only group of child and youth advocates in Canada that have formal legal mandates to implement children's rights at the provincial and territorial level. Comparatively, through interviews with justice-involved youth we analyse the youth justice system. By adjusting the setup of the court space and attempting to minimise power imbalances, we discuss how Canada's first and only Aboriginal Youth Court (AYC), promotes participation and engagement. Through a comparative case analysis, this chapter explores where barriers exist in terms of conceptualising and implementing participation rights, and where opportunities and best practices may be leveraged across child and youth serving institutions in Canada.

Details

Establishing Child Centred Practice in a Changing World, Part A
Type: Book
ISBN: 978-1-80117-407-7

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Article
Publication date: 15 November 2022

Syed Marwan, Suhaiza Ismail, Mohamed Aslam Mohamed Haneef and Engku Rabiah Adawiah Engku Ali

There are three objectives of this paper. First, the study investigates the critical success factors critical success factors (CSFs) of implementing sustainable and responsible…

422

Abstract

Purpose

There are three objectives of this paper. First, the study investigates the critical success factors critical success factors (CSFs) of implementing sustainable and responsible investment (SRI) Sukuk in Malaysia as perceived by stakeholders. Second, the study examines the differences between the developers and the investors in relation to the importance of the CSFs. Third, the study attempts to categorise the CSFs.

Design/methodology/approach

Using a questionnaire survey, 260 completed and useable responses were received representing a 42.54% response rate. In examining the importance of CSFs, the descriptive statistical tests of mean, standard deviation and mean score ranking were used. Independent t-tests were conducted to investigate the differences in the perceptions of the importance of CSFs between the developer and the investor groups. In categorising the CSFs, exploratory factor analysis (EFA) was undertaken.

Findings

Overall, the top five most important CSFs as perceived by respondents are as follows: (1) good governance framework, (2) fulfil ethical standards, (3) transparent procurement process, (4) well-defined scope and (5) viable feasibility study. On the other hand, the five factors that are ranked last are as follows: (1) defined stakeholder roles, (2) stable macro-economic conditions, (3) existing social programmes, (4) guarantor and (5) political will. The study also found that there is a significant statistical difference in how the developers and investors scored the CSFs. Moreover, there are three main categories of the CSFs that are effective feasibility study, financial and technical considerations and political willingness and agreeability.

Originality/value

The findings highlight the critical factors to consider when implementing SRI Sukuk. This can also serve as a reference and guideline for countries considering SRI Sukuk issuances for economic recovery stimulus post-coronavirus disease 2019 (COVID-19) pandemic.

Details

Journal of Economic and Administrative Sciences, vol. 40 no. 4
Type: Research Article
ISSN: 2054-6238

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Article
Publication date: 1 October 2004

Guy Knowles

Many corporations in recent years have considered outsourcing administrative or non‐essential functions. This reflects both a corporate desire to focus on core functions and…

712

Abstract

Many corporations in recent years have considered outsourcing administrative or non‐essential functions. This reflects both a corporate desire to focus on core functions and growing sophistication among providers of these secondary functions. Rogers Communications Inc., one of Canada’s largest, diversified telecommunications enterprises, considered this option but chose instead to retain and centralise its extensive real estate interests into a single corporate real estate function. The following case study traces Rogers’ experience, from the starting point of distinct real estate portfolios managed by individual operating groups to the end point of a centralised, full‐service, corporate real estate function. It discusses various challenges faced by Rogers during the centralisation process and the corresponding measures and strategies that contributed to a successful outcome. It also suggests useful performance indicators to measure the value contributed by the corporate real estate function.

Details

Journal of Corporate Real Estate, vol. 6 no. 4
Type: Research Article
ISSN: 1463-001X

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