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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

Keywords

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

Keywords

Open Access
Article
Publication date: 28 November 2022

Elena Stefana, Paola Cocca, Federico Fantori, Filippo Marciano and Alessandro Marini

This paper aims to overcome the inability of both comparing loss costs and accounting for production resource losses of Overall Equipment Effectiveness (OEE)-related approaches.

Abstract

Purpose

This paper aims to overcome the inability of both comparing loss costs and accounting for production resource losses of Overall Equipment Effectiveness (OEE)-related approaches.

Design/methodology/approach

The authors conducted a literature review about the studies focusing on approaches combining OEE with monetary units and/or resource issues. The authors developed an approach based on Overall Equipment Cost Loss (OECL), introducing a component for the production resource consumption of a machine. A real case study about a smart multicenter three-spindle machine is used to test the applicability of the approach.

Findings

The paper proposes Resource Overall Equipment Cost Loss (ROECL), i.e. a new KPI expressed in monetary units that represents the total cost of losses (including production resource ones) caused by inefficiencies and deviations of the machine or equipment from its optimal operating status occurring over a specific time period. ROECL enables to quantify the variation of the product cost occurring when a machine or equipment changes its health status and to determine the actual product cost for a given production order. In the analysed case study, the most critical production orders showed an actual production cost about 60% higher than the minimal cost possible under the most efficient operating conditions.

Originality/value

The proposed approach may support both production and cost accounting managers during the identification of areas requiring attention and representing opportunities for improvement in terms of availability, performance, quality, and resource losses.

Details

International Journal of Productivity and Performance Management, vol. ahead-of-print no. ahead-of-print
Type: Research Article
ISSN: 1741-0401

Keywords

Article
Publication date: 22 November 2022

Romanus Osabohien

Post-harvest losses are becoming a huge issue worldwide and are predominantly severe in developing countries. Seeking ways to control post-harvest losses is important…

Abstract

Purpose

Post-harvest losses are becoming a huge issue worldwide and are predominantly severe in developing countries. Seeking ways to control post-harvest losses is important because losses decrease farm income by more than 15% for approximately 480 million small-scale farmers.

Design/methodology/approach

The study engaged Wave 4 (2018/2019) of the Living Standards Measurement Studies–Integrated Survey on Agriculture, to examine the impact of soil technology such as fertilisers, herbicides, pesticides and certified crops on post-harvest losses in Nigeria. The study engaged descriptive statistics, logit regression and propensity score matching (PSM) to analyse the data.

Findings

The study found that approximately 38% of the household harvest was lost along the value chain. In addition, the results showed that among the indicators of soil technology, crop certification has a significant impact on the reduction of post-harvest losses. The implication is that from the nearest neighbour and kernel-based matching, the use of certified crops by households contributed to 1.62 and 1.36% reduction in post-harvest losses, respectively. In contrast, pesticide, herbicide and fertiliser use had no significant impact on post-harvest losses.

Research limitations/implications

One of the limitations is that this study applied the PSM, the model did not account for endogeneity. Therefore, in examining this concept, further studies should consider applying other impact model such as the difference-in-difference to account for endogeneity.

Originality/value

While previous studies have examined how ICT adoption, storage mechanisms and value chain among others help to minimise post-harvest losses, the aspect of how soil technology can reduce post-harvest losses has been a subject of exclusion in the extant literature. This study empirically examines the impact of soil technology adoption on post-harvest losses in Nigeria.

Details

Journal of Agribusiness in Developing and Emerging Economies, vol. ahead-of-print no. ahead-of-print
Type: Research Article
ISSN: 2044-0839

Keywords

Article
Publication date: 20 September 2022

Stoyu I. Ivanov and Matthew Faulkner

Small firms, which represent much of the Silicon Valley region, tend to experience losses due to their small scale, small customer base and lack of diversification. The…

Abstract

Purpose

Small firms, which represent much of the Silicon Valley region, tend to experience losses due to their small scale, small customer base and lack of diversification. The authors study the impact of accounting conservatism and losses on firm value and as such this study is an appropriate addition to this growing field of financial management.

Design/methodology/approach

The authors use methodology developed in prior literature to examine Silicon Valley and non-Silicon Valley firms' and their behavior when facing losses and the factors, which might play a role in their valuation. The authors focus particularly on earnings and accounting conservatism. Accounting conservatism captures how fast firms record losses relative to gains. The faster losses are recognized than gains the more accounting conservatism is exhibited. The authors examine the seemingly unrelated estimation of differences in means for our independent variables of interest across the two samples of Silicon Valley and non-Silicon Valley firms, both earnings and accounting conservatism. The authors use matched sample analysis of these firms based on four digit SIC code, size and date. In robustness, the authors run a more in-depth propensity score matched sample analysis.

Findings

The authors document that market values of Silicon Valley firms with accounting losses are affected less by negative earnings than other firms with accounting losses in the United States outside of the Silicon Valley region, noting the “lose big, win bigger” sentiment of Silicon Valley. Additionally, the authors document that accounting conservatism does play a role in influencing valuations of companies with accounting losses both in Silicon Valley and the rest of the United States, marginally more for Silicon Valley firms.

Originality/value

This study would be of interest to fund managers who need to consider smaller firms for inclusion in their portfolios. A lot of small firms have experienced losses ever since going public, especially Silicon Valley start-up firms.

Details

Managerial Finance, vol. ahead-of-print no. ahead-of-print
Type: Research Article
ISSN: 0307-4358

Keywords

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

Keywords

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

Keywords

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

Keywords

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

Abstract

Details

Operational Risk Management in Banks and Idiosyncratic Loss Theory: A Leadership Perspective
Type: Book
ISBN: 978-1-80455-223-0

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