Torque production improvement of a five phase fractional-slot PM machine under faulty operation

2015 ◽  
Vol 34 (6) ◽  
pp. 1758-1770
Author(s):  
Hajer Rebai ◽  
Imen Abdennadher ◽  
Ahmed Masmoudi
Keyword(s):  
Open Circuit ◽  
Electromagnetic Torque ◽  
Propulsion Systems ◽  
Element Analysis ◽  
Content Type ◽  
Production Capability ◽  
Production Improvement ◽  
The Mean ◽  
Practical Implications ◽  
Fractional Slot

Purpose – The purpose of this paper is to deal with several approach to recover the torque production capability of a five phase double-layer fractional-slot PM machine under faulty operation. The considered fault is an open-circuit coil in a given phase. Design/methodology/approach – In a first step, the mean futures, such as the phase back-EMFs and the electromagnetic torque, are computed by finite element analysis under healthy operation, and are taken as references. Then, they are investigated, under a faulty coil, for different approaches to recover the torque production capability. Findings – A comparison of the potentialities of the torque recovery approaches has clearly highlight the superiority of the approach consisting in the re-adjustment of the current initial phases, in an attempt to equilibrate the resulting air gap MMF. Research limitations/implications – This work should be extended by an experimental validation of the predicted results regarding the back-EMFs and the electromagnetic torque. Practical implications – The investigation of the considered five phase fractional-slot PM machine under faulty operation should be extended to several faulty scenarios in order to fulfill the requirements of many applications such as the propulsion systems. Originality/value – The paper proposes different approaches to recover the torque production capability of a five phase fractional-slot PM machine under faulty operation.

scholarly journals Time required to move cash through slot machines

2018 ◽  
Vol 21 (3) ◽  
pp. 376-384 ◽  
Author(s):  
Karen Kelly ◽  
Carl James Schwarz ◽  
Ricardo Gomez ◽  
Kim Marsh
Keyword(s):  
British Columbia ◽  
Slot Machines ◽  
Content Type ◽  
The Public ◽  
Average Value ◽  
The Mean ◽  
Time Required ◽  
Rest Breaks ◽  
Mean Time ◽  
Practical Implications

Purpose The purpose of this paper is to present an empirical study on the time needed to load and disburse cash using bill validators on slot machines and stand-alone cash dispensers in casinos in British Columbia under a Ticket In Ticket Out (TITO) system. Design/methodology/approach Testing took place over two days, using 18 machines. The results were extrapolated to estimate the approximate time required to process $1,000,000 with different average bill amounts in the cash mix and three different bill validator machines in common use. The average value per bill using the cash mix used by the public in the casino was $33.11 [standard error (SE) $2.11]. Findings The mean time/accepted note ranged from 4.12 to 9.65 s, depending on bill validator type. This implies that the time needed to load $1,000,000 onto credit slips using bill validators on slot machines ranges from 35 to 81 h, excluding rest breaks and other breaks. The time needed to redeem $1,000,000 is estimated to be 3 h. Practical/implications The implications of these finding for illicit actors to successfully launder large amounts of cash are discussed. Given the time needed to physically handle the cash, and other control systems currently in use in casinos in British Columbia, processing large amounts of cash using bill validators on slot machines would require a highly organized team that would find it difficult to elude detection. Originality/value The trial results provide a baseline estimate to be used going forward when investigating or proposing money laundering methodologies that include slot machines.

Analytical sub-domain model for predicting open-circuit field of permanent magnet vernier machine accounting for tooth tips

2016 ◽  
Vol 35 (2) ◽  
pp. 624-640 ◽  
Author(s):  
Y. Oner ◽  
Z.Q. Zhu ◽  
L.J. Wu ◽  
X. Ge
Keyword(s):  
Magnetic Field ◽  
Permanent Magnet ◽  
Open Circuit ◽  
Air Gap ◽  
Domain Model ◽  
Direct Drive ◽  
Element Analysis ◽  
Cogging Torque ◽  
Content Type ◽  
Flux Modulation

Purpose – Due to high electromagnetic torque at low speed, vernier machines are suitable for direct-drive applications such as electric vehicles and wind power generators. The purpose of this paper is to present an exact sub-domain model for analytically predicting the open-circuit magnetic field of permanent magnet vernier machine (PMVM) including tooth tips. The entire field domain is divided into five regions, viz. magnets, air gap, slot openings, slots, and flux-modulation pole slots (FMPs). The model accounts for the influence of interaction between PMs, FMPs and slots, and radial/parallel magnetization. Design/methodology/approach – Magnetic field distributions for slot and air-gap, flux linkage, back-EMF and cogging torque waveforms are obtained from the analytical method and validated by finite element analysis (FEA). Findings – It is found that the developed sub-domain model including tooth tips is very accurate and is applicable to PMVM having any combination of slots/FMPs/PMs. Originality/value – The main contributions include: accurate sub-domain model for PMVM is proposed for open-circuit including tooth-tip which cannot be accounted for in literature; the model accounts the interaction between flux modulation pole (FMP) and slot; developed sub-domain model is accurate and applicable to any slot/FMP/PM combinations; and it has investigated the influence of FMP/slot opening width/height on cogging torque.

Investigation of modular odd-pole PM linear synchronous motors with flux gaps

2016 ◽  
Vol 35 (2) ◽  
pp. 424-438 ◽  
Author(s):  
Jiameng Shi ◽  
Hao Kong ◽  
Liren Huang ◽  
Qinfen Lu ◽  
Yunyue Ye
Keyword(s):  
Fault Tolerant ◽  
Detailed Comparison ◽  
Open Circuit ◽  
Flux Linkage ◽  
Element Analysis ◽  
Content Type ◽  
Manufacture Process ◽  
The Difference ◽  
Linear Synchronous Motors ◽  
Open Flux

Purpose – Nowadays, to simplify manufacture process and improve fault-tolerant capability, more and more modular electrical machines are being applied in industrial areas. The purpose of this paper is to investigate a novel modular single-sided flat permanent magnet linear synchronous motor (PMLSM), which adopts segmented armature with the required flux gaps between segments to enhance the performance. Design/methodology/approach – Using 2D finite element analysis, the performances, such as open-flux linkage, back-EMF, average thrust force, thrust ripple, etc., are compared in different values of flux gaps, as well as different slot/pole number combinations (mainly odd numbers of poles). Finally, to show the difference of linear motor from rotary one, the detailed comparison is made between modular PMLSM and rotary PMSM. Findings – Due to flux gaps, it is found the electromagnetic performances are worsened along with flux gap width increasing to modular PMLSMs having slot number higher than pole number, but some aspects of performances such as winding factor, open-circuit flux linkage, back-EMF and average thrust can be improved to those having slot number lower than pole number. Due to the end effect of linear format, the thrust ripple is not significantly improved. Originality/value – It is concluded the proper flux gaps can be chosen to improve the performance of PMLSM with certain slot/pole combinations. A new structure of 12-slot-13-pole (hereinafter referred to as 12s/13p) PMLSM with fractional slot and alternative-teeth wound winding is designed.

Analysis of electromagnetic torque for induction motors with a novel non-skewed rotor structure

2021 ◽  
Vol ahead-of-print (ahead-of-print) ◽  
Author(s):  
Amir Darjazini ◽  
Abolfazl Vahedi ◽  
Amin Nobahari ◽  
Saber Gharehseyed
Keyword(s):  
High Performance ◽  
Induction Motors ◽  
Acoustic Noise ◽  
Torque Ripple ◽  
Iron Loss ◽  
Mechanical Equipment ◽  
Electromagnetic Torque ◽  
Content Type ◽  
The Mean ◽  
Rotor Structure

Purpose Pulsating torques cause a number of problems in electrical machines, including mechanical vibrations, acoustic noise and the depreciation of mechanical equipment. In induction motors, the slot skewing method is an effective way to solve these issues; however, it has some drawbacks such as output torque drop, stray loss intensification due to inter-bar currents and iron loss increment. Besides, slot skewing may not be practical in higher-rated induction motors. In this regard, this paper introduces a modified non-skewed rotor (MNSR) structure as a possible alternative to the skewed designs. Design/methodology/approach The proposed structure includes a two-segmented rotor with an intermediate ring between the rotor parts that are mounted on the shaft with a relative shift angle. Detailed information about the idea and structure of the MNSR as well as its manufacturing aspects will be presented in the second section of the paper. First, the working principle of the proposed design is described via analytical equations to provide an insight into the concept. The shifting angle will then be calculated by analyzing the harmonic contents of the electromagnetic torque. Finally, the validity of the analytical method will be verified by developing three-dimensional finite element models. Findings It is demonstrated that by using the proposed rotor structure, the torque ripple has been reduced to a satisfactory level without significantly affecting the mean torque, unlike the skewing method. Furthermore, the new method could avoid the disadvantages of the skewing method while enhancing other motor characteristics such as iron loss. Also, the total volume of the MNSR is equal to the initial design, and the mass and material differences are also negligible. Originality/value In this paper, a MNSR is introduced as a possible alternative to the skewed patterns. The study mainly focused on electromagnetic torque profile characteristics, i.e. the mean torque enhancement and the ripple reduction. The MNSR structure can be used for general purposes and high-performance applications, especially where excellent torque characteristics are required.

Designs of low frictional coefficients for joint bearings by inlaying graphites and liquid spraying of MoS2

2018 ◽  
Vol 70 (9) ◽  
pp. 1630-1635 ◽  
Author(s):  
Jun Cao ◽  
Zhongwei Yin
Keyword(s):  
High Temperature ◽  
Design Methodology ◽  
Element Analysis ◽  
Content Type ◽  
Nuclear Plants ◽  
Temperature Environment ◽  
Frictional Coefficients ◽  
Practical Implications ◽  
Permissible Stresses ◽  
High Temperature Environment

PurposeThe purpose of this paper is to solve the problem of joint bearings that cannot work in high temperature because of their high frictional coefficients.Design/methodology/approachTwo methods of inlaying graphites and liquid spraying of MoS2are designed. The arrangement of graphites is shown and its frictional coefficients (COFs) are discussed. MoS2coating is deposited by liquid spraying. The ingredients of liquid spraying of MoS2are illustrated. Stresses, structure deformations and fatigue life are analyzed by finite element analysis.FindingsResults show that both two designed methods can decrease COFs effectively. All stresses are in the limit of the maximum permissible stresses. The new designed bearings can be safety worked in sealed and high temperature environment which are proved by fatigue analyses.Practical implicationsTwo new designs can help joint bearings work in nuclear plants because of their low COFs and litter wear. The new designs can improve bearings life.Originality/valueTwo methods of decreasing COFs of joint bearings are designed in this paper. The technologies are illustrated. The proper scopes of applications of two designed methods are discussed.

Further studies on the heat production and effective lower critical temperature of early-weaned pigs under commercial conditions of feeding and management

1984 ◽  
Vol 39 (2) ◽  
pp. 283-290 ◽  
Author(s):  
K. J. McCracken ◽  
R. Gray
Keyword(s):  
Critical Temperature ◽  
Heat Production ◽  
Thermal Conductance ◽  
Open Circuit ◽  
Weaned Pigs ◽  
Respiration Chamber ◽  
Lower Critical Temperature ◽  
The Mean ◽  
The Difference ◽  
Practical Implications

ABSTRACTIn two separate experiments pigs were weaned at 14 or 28 days and heat production was determined in an open-circuit respiration chamber at temperatures above and below the lower critical temperature (Tcl) at intervals during the post-weaning period.With 14-day weaned pigs the mean 24 h heat production above Tc1 averaged 267, 328, 474 and 554 kJ/h per m2 at 3, 9, 15 and 21 days post weaning respectively. The mean thermal conductance (H/AT, kJ/h per m2 per °ΔT, where H is total heat production, m2 is the surface area calculated as 0·097 M kg0·633 and °Δ is the difference between rectal temperature, taken at 39°, and air temperature) below TC1 was calculated as 20·5, 20·1, 23·1 and 24·2 at 17, 23, 29 and 35 days of age respectively and the corresponding values for Tc1 were 25·9, 23·0, 18·4 and 16·0°C.With 28-day weaned pigs the mean 24 h heat production above Tc1 averaged 280, 361 and 445 kJ/h per m2 at 3, 9 and 15 days post weaning. The calculated values for H/ΔT were 19·7, 20·8 and 21·6 and the corresponding values of Tcl were 24·8, 21·7, and 18·8°C at 31, 37 and 43 days of age respectively.The results are discussed in relation to previous studies on 10-day and 28-day weaned pigs and in relation to the practical implications for pigs weaned into controlled-environment accommodation.

Internship for accounting undergraduates: comparative insights from stakeholders

2014 ◽  
Vol 56 (6) ◽  
pp. 482-502 ◽  
Author(s):  
Ruhanita Maelah ◽  
Zakiah Muhammaddun Mohamed ◽  
Rosiati Ramli ◽  
Aini Aman
Keyword(s):  
Learning Experience ◽  
Social Implications ◽  
Theoretical Understanding ◽  
Content Type ◽  
Accounting Curriculum ◽  
Perceptions Of Students ◽  
University Support ◽  
The Mean ◽  
Employer Contribution ◽  
Practical Implications

Purpose – This study utilises an internship framework to justify the need for feedback from all three groups of internship stakeholders. The purpose of this paper is to determine the benefits, skills, and outcomes students gained through internships from the perspective of students, university and employers. Design/methodology/approach – A set of structured questionnaires was used to survey the perceptions of students, university and employers of an accounting internship. A total of 172 responses were analysed. Findings – Findings show that all three groups of stakeholders perceived that students benefit from the internship programme. They also perceived that an internship provides the students with both the technical and soft skills required in the marketplace. However, the mean score and ranking differ among the students, university and employers. Research limitations/implications – The study was conducted based on feedback on a single accounting programme. Therefore any characteristics inherent in this sample that differ from the overall population of accounting programmes could bias the results and limit its generalisability and any associated inferences. Questionnaire responses should be interpreted with caution as perceptions and self-insights are subjective and may or may not be reflective of reality. This study falls short of putting forward any reasons why results differ from previous studies or why the mean scores of the three stakeholders all differ. Further research may take into consideration a comparison of internship programmes across institutions and disciplines. Future studies can also use the reflection approach and interview to better explain the benefits and skills developed through accounting internship programmes. Practical implications – Practically, findings from this study provide feedback to the students, university and employers to continuously improve accounting internship for undergraduate accounting programmes. Social implications – Social implications lie within the research framework that emphasises the student learning experience, university support through theoretical understanding and employer contribution through the practical component. Originality/value – Internships have become part of an accounting curriculum in many universities globally. To date, most studies on internship practices are limited in scope and focus on feedback from a single perspective. This study fills the gap in the literature by conducting a perception-based survey of internship stakeholders: students, university and employers, on benefits and skills acquired through internship.

Impact of knowledge enabling factors on organizational effectiveness in construction companies

2018 ◽  
Vol 22 (4) ◽  
pp. 759-780 ◽  
Author(s):  
Chau Ngoc Dang ◽  
Long Le-Hoai ◽  
Soo-Yong Kim
Keyword(s):  
Organizational Effectiveness ◽  
Management Strategies ◽  
Enabling Factors ◽  
Content Type ◽  
Mean Values ◽  
Construction Companies ◽  
Score Method ◽  
The Mean ◽  
The Impact ◽  
Practical Implications

Purpose This study aims to identify key knowledge enabling factors (KEFs) which can enable construction companies to improve various organizational effectiveness outcomes (OEOs). Design/methodology/approach Using a questionnaire, data are collected from construction companies in Vietnam. Mean score method is used to calculate the mean values of KEFs. In addition, regression analysis is used to identify KEFs which significantly affect OEOs. Findings A list of 32 KEFs, whose ranking orders of importance are provided according to different types of construction companies, is presented. In addition, different lists of specific KEFs which could significantly affect different OEOs are identified. Furthermore, seven key KEFs which could have a significant impact on many OEOs are highlighted. Practical implications The findings of this study could help construction companies to know the controllable KEFs, on which they should focus more. Hence, they could perform these KEFs properly to improve various aspects of organizational effectiveness. Originality/value This study identifies 32 KEFs and 10 OEOs specifically for knowledge management in construction companies. This study also provides construction companies with a better understanding of the impact of KEFs on various aspects of organizational effectiveness. Hence, they could develop effective KEFs-based management strategies to enhance various aspects of organizational effectiveness.

Portfolio forming decisions: the role of intellectual capital

2016 ◽  
Vol 17 (3) ◽  
pp. 439-456 ◽  
Author(s):  
Marina Zavertiaeva
Keyword(s):  
Intellectual Capital ◽  
Design Methodology ◽  
Growth Potential ◽  
Innovation Activity ◽  
Investment Portfolio ◽  
Content Type ◽  
The Mean ◽  
Sharpe Ratios ◽  
Practical Implications

Purpose – The purpose of this paper is to present a tool to categorize companies as potentially profitable on the basis of an intellectual capital (IC) analysis. Design/methodology/approach – The paper distinguishes two crucial attributions for picking shares: IC and capitalization of IC-based growth potential. Using these two attributions, the author creates a portfolio from a sample of European companies and annually rebalances it. To test its attractiveness, the author then compares the portfolio with benchmarks and random portfolios during the period from 2006 to 2013 using a Sharpe coefficient. Findings – The comparison of the constructed portfolio with the benchmarks demonstrates the importance of IC for market investors and the validity of the proposed tool. The Sharpe ratio of the portfolio is significantly higher than the mean and median Sharpe ratios of random portfolios. In addition, the importance of IC for choosing proper investment goal increases in crisis. Research limitations/implications – This investigation can be improved by analysing other IC such as the qualification of CEOs, participation of the company in business alliances, and a company’s innovation activity. In addition, the paper considers only European companies. Practical implications – The proposed tool provides a method to construct investment-attractive portfolios on the basis of IC. Originality/value – The paper contributes to the literature by identifying the underestimated shares on the basis of a company’s IC and by developing an algorithm to create an IC-based investment portfolio.

An approach to initiating eWOM intentions

2017 ◽  
Vol 27 (2) ◽  
pp. 277-302 ◽  
Author(s):  
Louis Yi-Shih Lo ◽  
Sheng-Wei Lin
Keyword(s):  
Design Methodology ◽  
Word Of Mouth ◽  
Information Sources ◽  
Content Type ◽  
Online Groups ◽  
Recency Effects ◽  
Reference Prices ◽  
The Mean ◽  
Carry Over ◽  
Practical Implications

Purpose The purpose of this paper is to examine the effects that reference prices and associated information sources (websites that consumers use to explore and their friends who have similar perspectives on value) have on deal evaluation and intention to disseminate electronic word of mouth (eWOM). Design/methodology/approach A stratified survey is conducted to empirically test the relations between reference prices, associated information sources (the top five Consumer-to-consumer (C2C) websites and top five Facebook friends with similar perspectives and values on consumption), deal evaluation, and eWOM intention. The study uses a Facebook API to help participants pick five Facebook friends to act as their favorite sources for advice on shopping. Findings The results suggest that consumers’ deal evaluations (as shaped by the recency effects of previous exposure to prices and the influence of Facebook friends and C2C websites) have carry-over effects on their eWOM intentions. The influence of Facebook friends and C2C websites on deal evaluation is as powerful as that of reference price, especially concerning the mean and the lowest prices. Practical implications The findings encourage marketers to invest their resources in targeting online groups, and suggest that C2C website marketers should set their offer prices between the mean and the lowest prices. Originality/value This study extends prior research on the motives for eWOM dissemination and elaborates an approach to initiate eWOM intention through deal evaluation.

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