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This paper develops a mixed finite-element, analytical solutions, equivalent surface impedance methodology for the computation of electric and magnetic field distributions near power facilities. The proposed method enables efficient consideration of conductor sag, ground surface irregularities, proximity effects of metallic components such as transmission line towers, and transformer tank walls as well as human presence. Application examples of this methodology are given, illustrating that under a single-circuit 400 kV transmission line, the maximum electric field intensity at 1.5 m height from the ground is generated at a distance of 10 m from the line center while the maximum current density induced in a human standing on the ground is developed in the ankle; the computed values are practically half of the admissible limits of 5 kV/m and 2 mA/m2, respectively, foreseen for general public exposure by international standards.

Precise PV energy yield estimation is critically dependent on an accurate temperature estimation method. This paper experimentally investigates the accuracy of three commonly used thermal modelling methods. Detailed sensitivity analysis of yearly, monthly, daily and intraday time resolution reveals that the actual data are clearly dependent of day-type and weather parameters. However, the proposed methods struggle to estimate temperature with varying irradiance or wind speed. During the summer months, on intermittently cloudy days the intraday mismatch can be as high as 25°C, whereas on clear sky days it can be below 10°C. Applying these methods for short term estimation of any day type can lead to a large error in energy yield estimation. Further adaptation is required to propose estimation methods which can properly handle different day types and weather fluctuations.

Background: Human immunodeficiency virus (HIV) infection and antiretroviral therapy have been associated with non-alcoholic fatty liver disease (NAFLD), but few studies have evaluated whether HIV infection is an independent risk factor for the development of hepatic steatosis and advanced liver fibrosis. Objectives: To study the prevalence and severity of hepatic steatosis and advanced fibrosis in people living with HIV and control outpatients. Methods: We conducted a cross-sectional analysis of relevant data from 875 pairs of individuals belonging to an HIV-dedicated outpatient clinic and an adult primary care clinic of an inner-city hospital. Hepatic Steatosis Index (HSI) and FIB-4 index were calculated as non-invasive measures of steatosis and fibrosis, respectively. A multivariate logistic regression analysis was performed to assess predictors of steatosis and advanced fibrosis. Results: The prevalence of hepatic steatosis, determined by HSI ≥36, was higher in HIV-negative subjects (71.5% vs. 65.4%, p=0.006). The prevalence of advanced fibrosis, determined by FIB-4 index ≥3.25, was higher in the HIV-positive group (7% vs. 1.7%, p Conclusions: In this cohort, hepatic steatosis was more prevalent in non-HIV infected patients, while advanced fibrosis had a higher prevalence in people living with HIV. HIV infection was not found to be an independent risk factor for either hepatic steatosis or fibrosis.

Litz wires are commonly used in high-frequency applications in order to reduce the impact of skin and proximity effects. Recently, this winding type has become more popular in high-speed electrical machines. Although many research papers have already highlighted the benefits and the practical limitations that derive from their utilization, less attention has been paid to the impact of the wire’s cross-section shape. Thus, this design characteristic is investigated in the present work by comparing the losses in litz wires with circular, square and rectangular cross-section. At first, the stator copper losses (including DC resistance losses, proximity- effect and skin-effect losses) of a high-speed permanent magnet synchronous motor are calculated through 2D finite element analysis. Then, the obtained results of different litz wire strand shapes are presented and thoroughly discussed. Finally, some useful conclusions are drawn.

The paper investigates demagnetization effects under three-phase short-circuit conditions, in Radial Flux- Interior Permanent Magnet Motors favored in electric mobility applications. The geometry optimization is based on high efficiency requirement along a wide operating range, in conjunction with high torque in low speed ranges and satisfactory performance under field weakening conditions. Various permanent magnet material grades are considered while three different magnet configurations are studied, namely V-, Insert-, and Spoke-type ones. The robustness under short circuit conditions is investigated by using the Limited Model and Finite Element Analysis. The feasibility analysis is drawn by conveniently assessing advantages and drawbacks among the considered topologies.

In recent years, the demand for wrist wearable devices to monitor continuously critical physiological parameters in real time that are limited by designated hospital monitoring equipment is steadily increasing. In the medical field, one of the main issues that wearable devices could sufficiently address is the pervasive monitoring of vital signs and the corresponding health status assessment of the rapidly growing elderly population in real time. Main advantages in the adoption of wearable devices for the real time monitoring are the significant decrease of the cost both for the health system and subsequently the patient as well as the dramatic decrease of the waiting time in the hospital emergency rooms.Reflectance pulse oximetry being the right mode to be used at the wrist for measurements such as Heart Rate (HR), Peripheral Capillary Oxygen Saturation (SpO2) and Respiratory Rate (RR) imposes many technical challenges with its excessive sensitivity to all types of entailed artifacts due to arm/hand/body motions to be amongst the major ones.This work introduces a low-power wrist wearable device comprising a Photoplethysmography (PPG) array sensor special extraction algorithms to estimate HR and SpO2 parameters and a Multiple Linear Regression model, which after training performs considerable reduction of the imposed Motion Artifacts (Mas) thus enabling more accurate reading outputs.

This work proposes a motor design methodology implemented in a Surface Mounted Permanent Magnet Motor case for a particular trajectory urban concept electric vehicle. It enables the generation of motor configuration clouds, populated by geometries produced by a parametric design algorithm. The methodology proposed consists of both analytical models and minimized finite element analysis, resulting in reduced computational time and densely populated cloud of motors. Motor structures are generated based on the vehicle's torque and speed specifications and are evaluated with respect to their resulting mass and efficiency, as well as their performance characteristics. The finally proposed powertrain emerges from a comparative study considering two gear ratios (1:1 and 3:1), based on the estimated vehicle energy consumption.

A new topology of end windings in permanent magnet machines is proposed enabling short circuit current reduction by introducing a convenient Ferrite magnetic circuit. This magnetic circuit includes a convenient auxiliary coil in each end winding coil, energized in case of over-current in stator windings, connected to an appropriate resistance. The proposed concept provides an efficient design improvement concerning fault tolerance capability, especially for surface permanent magnet rotor cases involving low leakage reactance and high short circuit currents. This technique can be of great interest for cases of weak grids with important electric traction applications such as more electric ship initiative.

The paper introduces an adaptive predictive controller for induction motor drives adequate for reduction of thruster start-ups power quality problems and efficiency improvement in electric ships. The algorithm calculates the optimal level of rotor flux that minimize the stator and rotor losses and calculates a voltage vector that drive the motor to the desired rotor speed set point. Independent control of the torque producing current is also introduced and limits the maximum electromagnetic torque. Special mention is made for the implementation of the algorithm in modern day microprocessors. The results are validated through laboratory measurements and compared with the simulated calculations.

The azimuth thruster is widely used in electric propulsion ships due to its excellent performance in contrast to their mechanical counterparts which present an inherent drawback regarding to maintenance needs, high costs and overall system deficiency. At the same time, according to up-to-date manufacturers’ reports, permanent magnet motors make azimuth thrusters more compact, lighter and more efficient compared to other types of motors. Thus, the replacement of a conventional drive with a properly designed low-speed permanent magnet synchronous motor (PMSM) directly coupled to the thruster propeller, provides an attractive alternative. This paper, based on authors’ previous work on low-speed surface mounted PMSM design for azimuth thruster application, presents and proposes here an optimization procedure using a meta-heuristic population based technique namely the symbiotic organism search (SOS) algorithm. The results obtained reveal that the SOS algorithm provides effectively the required design solutions and performance.

Purpose This paper aims to introduce a computationally efficient hybrid analytical–finite element (FE) methodology for loss evaluation in electric vehicle (EV) permanent magnet (PM) traction motor applications. In this class of problems, eddy current losses in PMs and iron laminations constitute an important part of overall drive losses, representing a key design target. Design/methodology/approach Both surface mounted permanent magnet (SMPM) and double-layer interior permanent magnet (IPM) motor topologies are considered. The PM eddy losses are calculated by using analytical solutions and Fourier harmonic decomposition. The boundary conditions are based on slot opening magnetic field strength tangential component in the air gap in the SMPM topology case, whereas the numerically evaluated normal flux density variation on the surface of the outer PM is implemented in the IPM case. Combined analytical–loss evaluation technique has been verified by comparing its results to a transient magnetodynamic two-dimensional FE model ones. Findings The proposed loss evaluation technique calculated the total power losses for various operating conditions with low computational cost, illustrating the relative advantages and drawbacks of each motor topology along a typical EV operating cycle. The accuracy of the method was comparable to transient FE loss evaluation models, particularly around nominal speed. Originality/value The originality of this paper is based on the development of a fast and accurate PM eddy loss model for both SMPM and IPM motor topologies for traction applications, combining effectively both analytical and FE techniques.

This paper proposes a multicriteria design optimization methodology for permanent magnet (PM) motors used in electric vehicle (EV) applications. In the process, an adaptive-network-based fuzzy inference system (ANFIS) is utilized, coupled with a multiobjective optimization algorithm, as a surrogate model of the electric motor. This allows for the consideration of the full drive cycle and respective efficiency map for every motor design. The prediction error of the ANFIS is minimized by employing appropriate membership functions, initial training data, and an adaptive learning scheme via iterative training. The efficiency map is then implemented in a vehicle dynamic model to compute the total consumed energy over the driving cycle. The optimization profile accounts for total energy efficiency, torque density, and additionally considers complementary design criteria via an a posteriori selection procedure on the resulting Pareto set. The methodology developed is applied to optimize a surface PM motor with concentrated fractional slot winding, mounted on a light EV that competes in fuel economy races. The selected motor design has been validated through measurements on a prototype.