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In boundary element method, we almost always have to integrate functions with singularities. The treatment of singularity is not particularly difficult for a line integration. Therefore we will focus on area integrations.

The paper aims to estimate the instantaneous breakdown voltage of the lightning discharge from simulated figures in an energized rod-plane configuration protected by a lightning rod. The same configuration of electrodes has been the subject of experimental investigations for the measurement of the instantaneous breakdown voltage using oscillographic monitoring. This study validates the simulation model by making a comparison with experimentation and involves the role of the inception field of the upward discharge in the propagation of this last one.

The research methodology is based on the development of a fractal lightning protection model based on real physical conditions of the discharge propagation, such as the downward discharge and the upward one emanating from protection. The voltage drop and the randomness character of the lightning discharge are also taken into account. The electrical field is an important parameter in discharge development; it is considered in this work at each step of the discharge propagation by the finite element method. The instantaneous breakdown voltage is measured and estimated by both empirical equations and simulated figures of lightning discharge

The established model that allows estimating the instantaneous breakdown voltage from simulated discharges and empirical equations gives results in a good agreement with experimentation. The involvement of the upward discharge inception field emanating from the lightning rod in the evolution of electrical discharge is illustrated.

The work presented in this paper aims to develop a new fractal lightning protection model taking into consideration physical phenomena intervening in the development of the lightning discharge.

The originality of this work consists of the combination between fractals modelling of the electrical discharge and the protection against lightning, in addition, to use one of the characteristics of the electrical discharge, which is the instantaneous breakdown voltage, to prove the importance of the inception field emanating from the upward discharge in the propagation criterion of this last one.

The paper proposes and presents a comprehensive and integrated circuit model for investigating the behaviour of partial discharges occurring in voids inside the solid insulations of medium and high voltage cables.

The model is based on the well‐known three capacitors model, which is remarkably improved to handle physical parameters such as cavity size, position, shape and pressure, environmental parameters such as cable temperature, in addition to operational parameters such as the contributions of the avalanche of free electrons inside the cavity through considering stochastic time delays.

A complete, flexible and reliable model for partial discharges in voids inside the solid insulation of medium and high voltage cables is presented whose output agrees with experimental reported results.

The proposed model deals only with single voids, and the semiconductor layers in the insulation of cables are not considered.

The model can be used in different physical, environmental and operational conditions in order to investigate the characteristics of partial discharge signals to be used as the bases for partial discharge detection and classification in power cables.

This paper presents a novel comprehensive and integrated circuit model with controlling functions to propose the behaviour of partial discharge occurring in voids inside the solid insulation of power cables. The model provides the contribution of geometrical parameters of the void, and operational conditions such as cable temperature and source frequency in partial discharge analysis.

This paper proposes a method for multi‐terminal resistor optimal design based on a stochastic optimization algorithm coupled with a high accuracy boundary element method numerical analysis module using spline boundary elements. The aim of the optimization process is to find out the optimal shape of the resistor so that the values of the partial resistances between its terminals can be globally reduced. In the first part of the paper, a short introduction to the boundary element method formulation using spline interpolation of the boundary unknowns is performed. Then, the genetic algorithm optimization method is briefly described, emphasising the numerical implementation particularities related to the actual application. In the second part of the paper, three numerical examples are proposed and the final conclusions are outlined.

This paper aims to investigate the electroporation phenomenon in a single cell exposed to ultra short (μs) and high voltage (kV) electric pulses.

The problem is addressed by two complementary approaches. First, numerical simulations based on an asymptotic approximation derived from the Smoluchowski theory are used to calculate the pore generation, growth and size evolution at the membrane of a spherical cell model, immersed in a suspension medium and consisting of cytoplasm and membrane. The numerical calculations are solved using the finite difference method. Second, an in vitro experiment with LLC-MK2 cells is carried out in which electroporation was monitored with molecules of propidium iodide. This part also comprehended the design and manufacturing of a portable electric pulse generator capable of providing rectangular pulses with amplitude of 1,000 V and duration in the range of 1-μs to 100-μs. The pulse generator is composed of three modules: a high voltage DC source, a control module, and an energy storage and high voltage switching.

The numerical simulations considered a 5-μm radius cell submitted to a 500 kV/m rectangular electric pulse for 1-μs. The results indicate the formation of around 3,500 pores at the cell membrane, most of them, around 950, located at the poles of the cell aligned to the applied electric pulse, with radii sizes varying from 0.5-nm to 13-nm. The in vitro experiment considered exposition of LLC-MK2 cells to pulses of 200 V, 500 V, and 700 V, and 1-μs. Images from fluorescence microscopy exhibit the LLC-MK2 cells with intense red, a strong evidence of the electroporation.

The work presents a thorough study of the electroporation phenomenon combining two complementary approaches, a rigorous numerical simulation and a detailed in vitro experiment.

In this paper, different shapes of the boundary surfaces within the power transformers are reviewed. The surface charge distribution function on the two surface elements, which have the majority of usage, are recognized and the resultant potential and electric field intensity equations are derived. A numerical interpolation idea is presented and extended to evaluate the values of the existing integrals within the equations. Fulfilment of this idea removes the problems due to the singularity of the integrands and it leads to a shorter computation time for the boundary element method. This idea is applied to a typical problem and results are compared with the corresponding values obtained using the numerical integration. Finally, the electric field within the interior space of a power transformer is estimated using the developed computer program based on the boundary element method.

This paper aims to understand the association of dietary patterns with perceived fatigue and identify predictors for presence of fatigue in women who are obese and trying to lose weight.

An online survey, hosted by slimming world (SW), comprised of a questionnaire regarding weight, level of fatigue and food frequency questionnaire before joining the weight management programme (T0) and current data (T1) was conducted. In total, 543 non-pregnant women with obesity of child-bearing age (19-49 years) completed the survey (T0-T1). The principal components analysis was used to determine dietary patterns and multinomial logistic regression was used to analyse predictors for presence of fatigue.

The participants who have a “simple carbohydrate and high fat” dietary pattern were more likely to have fatigue at T0 (p ≤ 0.001) and those who followed a “vegetables” dietary pattern were less likely to have fatigue at T1 (p ≤ 0.05). The study findings indicate that while “simple carbohydrate and high fat” dietary pattern was associated with increased risk of fatigue, “vegetables” dietary pattern was associated with reduced risk of fatigue and a higher percentage of weight loss.

The present study appears to be the first study to examine associations between dietary patterns and fatigue. The strengths of the study included the in-depth analysis of this association in both before joining a weight management programme (SW) and currently as a member of SW with an adequate sample size.

This paper examines the limits of pragmatism in strategy formulation in the new, knowledge‐rich economy. By tracing the history of pragmatism in social and management thought, and assessing the commonalties and complementarities between a firm’s vision and mission, we explore the possibility and consequences of an intangible resource curse for firms pursuing strategies of incessant pragmatic growth in the expanding Web‐based domain. Ultimately, we posit a combined influence of market‐based governance and strategy simplification as an effective antidote to the executive intangible resource binging, which is sustainable as long as confidence and trust continue to be shared among the firm stakeholders.

This study examined sex differences in the prevalence of mutual intimate partner violence (IPV) and mental health symptoms among Ghanaian university students. Three hundred and fifty‐eight university students in heterosexual relationships were asked if they had experienced IPV, coercion, and symptoms of depression or post‐traumatic stress disorder (PTSD), as well as attitudes on the use of violence. Analyses were conducted separately for female and male respondents to explore sex differences in mutual violence and correlates of partner violence and mental health symptoms. Bivariate analyses found that both males and females reported strong correlations between IPV perpetration and IPV victimisation. Multivariate analyses found that among female respondents, their coercive behaviours, attitudes that accept violence and alcohol use were related to perpetrating against their male partner. Among male respondents, attitudes that accept violence and symptoms of conduct disorder were related to abusing their female partner. Additionally, results were that both females and males reported increased mental health symptoms if she/he reported childhood abuse and if her/his partner had attitudes that accepted the use of violence to achieve goals. Taken together, these findings suggest that the majority of couples experience mutual violence and that both females and males can have violent attitudes that accept the use of violence to control their intimate partners, which may also contribute to mental health symptomology.