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Article
Publication date: 2 March 2015

Maria Dems, Krzysztof Komeza, Slawomir Wiak and Sara Fernández Coya

– The purpose of this paper is to present the distribution of the magnetic field and additional losses analysis of the induction motors (IM) with opened and closed rotor slots.

Abstract

Purpose

The purpose of this paper is to present the distribution of the magnetic field and additional losses analysis of the induction motors (IM) with opened and closed rotor slots.

Design/methodology/approach

In the field-circuit approach the distribution and changes of magnetic flux density in the motor are computed using a time-stepping finite element method. The additional losses in each element are evaluated at different frequencies.

Findings

An approximate analytical formulation is derived for rapid losses computation confirmed by the results of field-circuit method. For high-voltage motors due to the size ratios of the core and relatively deep stator and rotor slots major role in causing loss of higher harmonics play a fundamental slot harmonics. Higher harmonics order bigger than 100 cause only small part of total higher harmonics core losses. Closed rotor slots construction influenced significantly on no-load losses mainly due to reduction of losses at slot upper part. For nominal load condition that influence is not so strong according to the saturation of slot tips by rotor leakage flux. Nevertheless, core losses at load are several times higher as at no-load.

Research limitations/implications

In future research authors will take into account motors feed from PWM inverter, working in the frequency range up to 400 Hz.

Practical implications

The results of investigation will be used in more detailed design of IMs especially for motors with closed rotor slots.

Originality/value

The methods presented in the paper was not used before. Also results of additional losses in the motor core calculation, especially according motors with closed slots at no load and load conditions are new.

Details

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

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Article
Publication date: 13 July 2010

S. Jelassi, R. Romary and J.F. Brudny

The aim of this paper is to estimate the iron losses for an induction machine in the healthy case taking the slotting effect into account and to study the effect of an…

Abstract

Purpose

The aim of this paper is to estimate the iron losses for an induction machine in the healthy case taking the slotting effect into account and to study the effect of an inter‐turn short‐circuit on these losses. Theoretical results are then compared with experimental ones.

Design/methodology/approach

A simple analytical model of iron losses allows one to calculate and to appreciate the contribution of the slotting effect on induction machine iron losses without and with an inter‐turn stator short‐circuit. This semi‐analytical approach is based on the iron stator and rotor flux density repartition which is deduced from the air‐gap flux density.

Findings

The iron losses are not only due to the fundamental air‐gap flux density, but also to the slotting harmonics. In fact, the slotting effect generates harmonic flux density waves with very low magnitudes but with high‐angular velocities, leading to non‐negligible harmonic iron dynamic losses which have similar values on both the stator and the rotor. The inter‐turn short‐circuit generates an iron losses and a slotting harmonic contribution increase.

Research limitations/implications

Experimental measurements give the total iron losses. They do not allow separating the fundamental and the slotting harmonics contribution.

Practical implications

The knowledge of the iron losses behaviour in the healthy machine taking into account the slotting effect is important to optimize the design. The fault contribution on these losses allows one to estimate the damage which can be engendered by the fault.

Originality/value

Generally, iron losses studies and calculations are performed numerically using finite element software. The analytical approach can be interesting because it allows one to make faster calculations and to analyze the influence of the machine geometric parameters.

Details

COMPEL - The international journal for computation and mathematics in electrical and electronic engineering, vol. 29 no. 4
Type: Research Article
ISSN: 0332-1649

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Article
Publication date: 17 September 2021

Meiyi Zhang, Yi Luo, Dong Huang, Haimin Miao, Laping Wu and Junfeng Zhu

The purpose of this study was to estimate on-farm maize storage losses and to empirically analyse the main determinants of maize storage losses in China.

Abstract

Purpose

The purpose of this study was to estimate on-farm maize storage losses and to empirically analyse the main determinants of maize storage losses in China.

Design/methodology/approach

Based on a nationwide survey of 1,196 households in 23 provinces (autonomous regions and municipalities) in China, the authors estimated on-farm maize storage losses and used a fractional logit model to analyse the main determinants of maize storage losses in China.

Findings

The results showed that, first, 1.78% of maize was lost during the storage stage in China and that storage loss experienced by smallholders varied across regions. Second, the empirical analysis showed that storage quantities have significant and negative effects on storage losses and that an economy of scale in household storage may exist; the percentage of maize stored for consumption and feed has significant and positive effects on storage losses, which may be related to market requirements and management activities. Third, compared to traditional facilities, silos and warehouses cause lower storage losses, while spraying chemicals and re-drying maize in the storage stage incur higher losses, possibly because to save costs, smallholders conduct loss-reduction activities only when they suffer serious losses, and when taking measures, farmers may sort grains, which also increases losses. Fourth, harvesting maize when it matures is significantly associated with lower storage losses.

Research limitations/implications

To reduce storage losses, first, farmers' awareness of food saving and loss reduction must be increased. This could be achieved through agricultural training and education regarding food-saving practices. Second, the government could provide subsidies or low-interest credits to encourage farmers to use advanced facilities and promote land transfers to realize economies of scale. Finally, the government should accelerate the construction of smart agriculture systems and the timely monitoring of crop growth to suggest farmers to harvest at the appropriate time.

Originality/value

Reducing post-harvest loss (PHL) has become an important means of increasing the food supply and reducing resources use in China. This study provides a complete introduction to household maize storage losses and can therefore help characterize the current state of PHL in China, which is of vital importance to food security and food policy.

Details

China Agricultural Economic Review, vol. ahead-of-print no. ahead-of-print
Type: Research Article
ISSN: 1756-137X

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Article
Publication date: 13 September 2021

Charlotte Haugland Sundkvist and Tonny Stenheim

This study examines the reporting of impairment losses in family and non-family private firms. The socioemotional wealth (SEW) theory suggests that the reporting practices…

Abstract

Purpose

This study examines the reporting of impairment losses in family and non-family private firms. The socioemotional wealth (SEW) theory suggests that the reporting practices in family firms may differ from non-family firms and may vary among family firms.

Design/methodology/approach

The research question is examined using a large-scale archival study. The authors use unique register data on family relationships for Norwegian private firms provided by the CCGR database at BI Norwegian Business School.

Findings

Drawing on the socioemotional wealth theory, the authors predict and find that private family firms are more reluctant to report impairment losses compared to private non-family firms. The results also suggest that both the likelihood to report impairment losses and the impairment amounts increase with board independence in private family firms. The authors also find some evidence suggesting that private family firms with a family CEO report lower impairment losses than private family firms without a family CEO, but this result is less robust and should be interpreted with caution.

Research limitations/implications

The true economic impairment is unobservable. The authors use proxies based on prior research to control for whether impairment losses are faithfully reported or not.

Practical implications

The results suggest a higher risk of impairment losses being managed in private family firms than in private non-family firms and that independent board members mitigate this tendency somewhat in private family firms. Awareness of this risk should have practical value for stakeholders such as non-family owners and creditors, external auditors, supervisory and monitoring bodies, and regulators.

Originality/value

This study contributes to the accounting literature by examining the reporting of a specific accrual (impairment losses) in the setting of private family firms. Prior research in this area is scarce.

Details

Journal of Applied Accounting Research, vol. ahead-of-print no. ahead-of-print
Type: Research Article
ISSN: 0967-5426

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Article
Publication date: 10 August 2018

Valentin Ionita, Lucian Petrescu and Emil Cazacu

The electrical machines connected to modern electric power grids are non-sinusoidal excited, and their augmented losses, including iron losses, limit their working…

Abstract

Purpose

The electrical machines connected to modern electric power grids are non-sinusoidal excited, and their augmented losses, including iron losses, limit their working characteristics. This paper aims to propose a prediction method for iron losses in non-oriented grains (NO) FeSi sheets under non-sinusoidal voltage, involving an inverse classical Preisach hysteresis model and the time-integration of each loss component.

Design/methodology/approach

The magnetic history management in inverse Preisach model is optimized and a numerical Everett function is identified from measured symmetrical hysteresis cycles. The experimental data for sinusoidal waveforms obtained by a single sheet tester were also used to identify the parameters involved in Bertotti’ losses separation method. The non-sinusoidal magnetic induction waveform, corresponding to a measured voltage in an industrial electrical grid, was the input for Preisach model, the output magnetic field being accurately computed. The hysteresis, classical and excess losses are calculated by time-integration and the total losses are compared with those obtained for sinusoidal excitation.

Findings

The proposed method allows to estimate the iron losses for non-sinusoidal magnetic induction, using carefully identified parameters of FeSi NO sheets, using experimental data from sinusoidal regimes.

Originality/value

The method accuracy is assured by using a numerical Everett function, a variable Preisach grid step (adapted for the high non-linearity of FeSi sheets) and high-order fitting polynomials for the microscopic parameters involved in the excess loss estimation. The procedure allows a better design of magnetic cores and an improved estimation of the electric machine derating for non-sinusoidal voltages.

Details

COMPEL - The international journal for computation and mathematics in electrical and electronic engineering, vol. 37 no. 5
Type: Research Article
ISSN: 0332-1649

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Article
Publication date: 6 July 2015

Dominic Peltier-Rivest and Nicole Lanoue

The purpose of this paper is to analyze the effect of various internal controls (i.e. hotlines, regular ethics (fraud) training, surprise audits, internal and external…

Abstract

Purpose

The purpose of this paper is to analyze the effect of various internal controls (i.e. hotlines, regular ethics (fraud) training, surprise audits, internal and external audits and background checks) on reducing occupational fraud losses by victim organizations.

Design/methodology/approach

The paper, based on data from an occupational fraud report co-authored by the Association of Certified Fraud Examiners (ACFE) and Peltier-Rivest (2007), uses a multivariate regression analysis to analyze the effect of various internal controls on preventing fraud losses.

Findings

The authors’ analyses demonstrate that hotlines, regular ethics (fraud) training, surprise audits and internal audits all decrease fraud losses when used separately. However, hotlines and surprise audits are the only statistically significant controls when controlling for the potential correlation among all internal controls. Hotlines are associated with a reduction of 54 per cent in median fraud losses, while surprise audits cut median losses by 69 per cent.

Research limitations/implications

This study contributes to academia and the anti-fraud profession by assessing the statistical effect of six internal controls on preventing fraud losses, while controlling for the potential correlation among these controls.

Practical implications

This study discusses the relative benefits (loss savings) of various internal controls to organizations, governments, managers and anti-fraud professionals. This information may help determine investment priorities in the context of scarce resources.

Originality/value

This paper is based on proprietary data owned by the ACFE and is the first to analyze the statistical significance of various internal controls on the reduction of fraud losses in Canada.

Details

Journal of Financial Crime, vol. 22 no. 3
Type: Research Article
ISSN: 1359-0790

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Article
Publication date: 16 August 2019

Lichen Gu, Rui Xu and Nan Wang

The purpose of this paper is to identify the energy losses factors during the hydro-mechanical conversion process at high pressure via a novel reduced order dynamic model.

Abstract

Purpose

The purpose of this paper is to identify the energy losses factors during the hydro-mechanical conversion process at high pressure via a novel reduced order dynamic model.

Design/methodology/approach

A novel reduced order dynamic model of the axial piston motor was proposed, which provides an explicit insight to the compression flow losses and the Coulomb friction losses. A fully coupled dynamic model of the piston motor was obtained based on the array bond graph method. And then, a reduced order model was obtained by the composition analysis of flow and torque of the axial piston motor. After that, the energy losses estimation model was presented to predict the energy loss of the piston motor under a wide range of working conditions. The model was verified by comparing the experimental and simulation results.

Findings

The simulation result indicates that the flow loss caused by oil compression accounts for 59 per cent of the total flow loss, and the Coulomb friction torque accounts for 40 per cent of the total torque loss under a specific working condition. The compression flow loss and Coulomb friction torque are the major factors that lead to the aggravation of energy loss under extreme working conditions of the piston motor.

Originality/value

At high-pressure condition, the compression flow losses due to fluid compressibility cannot be neglected, and the hydro-mechanical losses in varies friction pairs should involve Coulomb friction losses. Flow and torque loss analytical expression in the model involve the design and control parameters of the piston equipment, which can realize the parameter optimization of the piston equipment for the purpose of energy-saving.

Details

Industrial Lubrication and Tribology, vol. 72 no. 5
Type: Research Article
ISSN: 0036-8792

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Book part
Publication date: 3 June 2008

Susan K. Laury and Charles A. Holt

This paper reports a new experimental test of the notion that behavior switches from risk averse to risk seeking when gains are “reflected” into the loss domain. We…

Abstract

This paper reports a new experimental test of the notion that behavior switches from risk averse to risk seeking when gains are “reflected” into the loss domain. We conduct a sequence of experiments that allows us to directly compare choices under reflected gains and losses where real and hypothetical payoffs range from several dollars to over $100. Lotteries with positive payoffs are transformed into lotteries over losses by multiplying all payoffs by –1, that is, by reflecting payoffs around zero. When we use hypothetical payments, more than half of the subjects who are risk averse for gains turn out to be risk seeking for losses. This reflection effect is diminished considerably with cash payoffs, where the modal choice pattern is to exhibit risk aversion for both gains and losses. However, we do observe a significant difference in risk attitudes between losses (where most subjects are approximately risk neutral) and gains (where most subjects are risk averse). Reflection rates are further reduced when payoffs are scaled up by a factor of 15 (for both real and hypothetical payoffs).

Details

Risk Aversion in Experiments
Type: Book
ISBN: 978-1-84950-547-5

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Article
Publication date: 29 April 2021

Anupam Das and Adian McFarlane

The purpose of this paper is to examine the impact of remittance inflows (remittances) on electricity consumption and electric power losses in Jamaica.

Abstract

Purpose

The purpose of this paper is to examine the impact of remittance inflows (remittances) on electricity consumption and electric power losses in Jamaica.

Design/methodology/approach

The authors use annual data from 1976 to 2014 and apply vector error correction modelling, Granger causality testing and impulse response analysis.

Findings

First, the authors find that there is co-integration between remittances and the energy variables, namely electricity consumption and electric power losses. Second, short-run Granger causality exists between the energy variables and remittances. This causality is bidirectional between the energy variables and positive changes in remittances, but it is unidirectional running from the energy variables to negative movements in remittances. Third, the authors find that in the long-run remittances have a negative relationship with electric power losses and a positive relationship with the consumption of electricity.

Practical implications

Findings from this paper will help to elucidate the relationship between electricity consumption, and electric power losses, and remittances.

Social implications

The problem of electric power losses is acute in Jamaica and it is mostly due to theft. At the same time, Jamaica receives significant remittances. Social policy could have a role to encourage the use of remittances to help stem the theft of electricity.

Originality/value

This is the first study that examines the relationships between remittances, electricity consumption and electric power losses.

Details

Journal of Economic Studies, vol. ahead-of-print no. ahead-of-print
Type: Research Article
ISSN: 0144-3585

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Book part
Publication date: 1 October 2014

Guoxiang Song

To raise the quality of regulatory capital, Basel III capital rules recognize unrealized gains and losses on all available-for-sale (AFS) securities in Common Equity Tier…

Abstract

To raise the quality of regulatory capital, Basel III capital rules recognize unrealized gains and losses on all available-for-sale (AFS) securities in Common Equity Tier 1 Capital (CET1). However, by examining the correlations between U.S. GDP growth rate, interest rates and regulatory capital ratios computed using Basel III regulatory capital definition for six U.S. global systemically important banks (G-SIBs) since 2007, this chapter finds that Basel III regulatory capital will enhance the pro-cyclicality of Basel III leverage ratio and Tier 1 capital ratio and their sensitivity to long-term interest rates. Therefore, Basel III capital standards may have significant implications for bank supervision and bank capital risk management in the near future. As banks will hold more high-quality liquid assets (HQLAs) as required by Basel III Liquidity Coverage Ratio (LCR), the weight of unrealized gains and losses arising from fair value accounting will increase in Basel III Tier 1 capital base, the consequent increase of pro-cyclicality in a bank’s regulatory capital ratios may distort the true picture of bank capital adequacy. If an expected loss approach (EL) is used as the provisioning model, such capital risk may be increased further. Moreover, as U.S. monetary policy has started tapering quantitative easing, long-term interest rates will increase inevitably. This may increase the negative impact of unrealized gains and losses on AFS securities on bank capital. As a result, it may be difficult for banks to maintain appropriate capital ratios to meet regulatory requirements and support business activities.

Details

Risk Management Post Financial Crisis: A Period of Monetary Easing
Type: Book
ISBN: 978-1-78441-027-8

Keywords

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