The reconstructed phase images (PIs) from digital holographic microscopy contain in each pixel values of the phase shift introduced by the sample in optical path, which allow to segment cells in the most important compartments: nucleus and cytoplasm. Based on PIs, we computed optical properties of cells from two sublines with different malignancy levels and propose a three-layers numerical model to analyze the response under the stress of a high frequency continuous wave electric field. The induced transmembrane voltage is compared for different values of dielectric properties assigned to the cell compartments. Considering the nucleus as a distinct domain with specific electrical properties, brings the model closer to realistic cases; the importance of its presence in simulation models was also investigated.

Electropermeabilization represents the general process of increasing the permeability of lipid membranes to various substances, facilitating their transition between the indoor and outdoor cellular environment, by exposure to variable electric field; the process is highly dependent, on both the electric field features (amplitude, waveform, frequency and space-distribution) and the characteristics of the target (cell morphology and dielectric properties of the cell membrane). Some of these aspects are evaluated in this study, using numerical simulation with the finite element analysis. The behavior of realistically shaped cells (computation domains built based on holographic imaging techniques) and idealized circular cells is comparatively assessed under uniform distributed, time-harmonic electric field, within a large frequency spectrum. Our results confirm that simulation is a valuable tool for the predetermination and adjustment of the optimal settings for an experimental approach, taking into account the particularities of the used field or cell sample.

Thermal medical procedures of assisted procedures have been proven to be beneficial in a number of severe diseases, and the quest for their development and optimization is of major concern. Heat transfer is the underlying mechanism, but the work to produce it is generally done by other physics, for instance, electromagnetic fields and ultrasounds. In general, coupled diffusive, convective, and radiation processes concur, and their knowledge is key to sizing the intervening devices, applicators, electrodes, and adjusting the pending medical protocols. Relying on continuous media assumptions and mathematical models, this chapter is about the mathematical and numerical simulation of several thermotherapy methods—radiofrequency, microwave, magnetic, ultrasound hyperthermia and ablation, and their numerical solution. Numerical simulation results are more valuable when their controllable accuracy and predictability are related to more realistic, patient-specific computational domains, and, to this aim, CAD and medical scan-based reconstructions are utilized.

The paper is about the prototype of a proportional electromagnetic actuator (PEA) with wide displacement of its mobile part and the electronic driver for its control. The complexity of this electromagnetic device requires mathematical modeling and numerical simulations in the initial design phases. The actuator coil is powered by a PWM (Pulse Width Modulation) source. To verify the linear response of the PEA, in the experimental phase of the design, numerous tests were performed on the PWM rectangular pulse shape and on the displacement of the PEA mobile part, for the DC control voltage of the drive in the range of 0.75 V and 3.4 V, which may provide for displacements of up to 15 mm. Finally, the automatic control system for this device is presented.

Passive magnetic bearing with Halbach array method used for combining the direction of magnetization of the permanent magnets, may alleviate some critical aspects related to the usage of the conventional bearing solutions for high-speed electromechanical systems. This paper presents numerical simulation results of such a passive magnetic bearing (PMB) concerning the static loads, and some critical problems related to the limitation of the conventional bearing solutions. The magnetic flux and the magnetic forces occurring in the magnetic bearing air gap, and the radial loads are evaluated. The rotor is subjected to static displacements to determine the radial and axial magnetic forces that occur between the rotor and stator parts.

Interdigitated grid topology may provide for higher quality electrical devices, which are sieges of electric and magnetic fields, in terms of capacity, reconfiguration capability, and compactness. It is then important to provide design solutions that add to these the architectural scalability required to produce readily available solutions for designers. This paper aims to propose a constructal solution for interdigitated grid topologies based on an optimal scalable, minimum-redundant, reconfigurable interdigitated topology for planar electric devices. Although the interdigitated constructal design (ICD) may be of interest in the optimization of numerous planar structures, here we envisage two applications. In this paper, ICD is applied to optimize a planar micro supercapacitor that utilizes vertically grown carbon nanotube forests electrodes. This study relies on numerical solutions to boundary value problems that are solved using the finite element method.

The paper reports the design and realization of a dipolar superconducting electromagnet for high uniformity magnetic field generation, aimed for particle accelerators. The adopted solution for winding distribution is of cosine type. The HTS coils are executed from YBCO tape, 6 mm wide. The mathematical model and numerical, finite element (FEM) analysis was performed for model optimization. First, was addressed the magnetic field problem, as the main purpose of the HTS electromagnet is to provide for a highly uniform (10 -3 ), high flux density magnetic field (~2.5 T). The study is based on a three dimensional computational domain that was CAD-designed for the prototype. The numerical simulation results unveil the magnetic field, which is valuable in optimizing the electromagnet design and assessing its magnetic field fingerprint. The electrodynamic forces are of concern to the mechanical stability of the HTS winding, and numerical simulation is used to evaluate their spectrum and to predict the regions of higher concentration.

This paper presents the driving system of a linear magnetostrictive motor (LMM) that operates in a wide range of frequencies of up to 16 kHz, which is intended for space applications. Accordingly, the design and control of the LMM differs from the classical version, causing changes in electrical driving conception. The LMM drive has two units Pulse Width Modulators (PWM) for the control of the activation coil, the magnetic bias coil, and it is also provided with a power supply block. An ensemble of three series, connected Peltier elements is powered by a third PWM modulator with the following features: f = 24 kHz, U = 28 VPP and duty cycle kPWM = 30%. The Peltier ensemble provides the cooling of LMM in the absence of terrestrial gravity.

This paper is about a high temperature superconductor (HTS) electromagnet for uniform magnetic field generation, without a magnetic core. More specifically, we are concerned with the design of a field winding made of HTS wire, for a homogeneous magnetic field in the working place, and with the evaluation of the electrodynamic interactions (Laplace forces) to which the winding is subjected. Another objective is the thermal stability of the HTS winding, which is provided by a Gifford-McMahon cryocooler for cooling down the winding and a confining cryostat system. Its thermal design and performance assessment are of concern too.Mathematical modeling and numerical simulations with Comsol Multiphysics are used to size the device and to evaluate the quality of the generated magnetic field.

This paper presents a bending-mode cantilever actuator (CA) concept for optical devices. Two designs are analyzed in stationary working conditions through numerical simulations, and their deformations under the action of electrodynamic body forces are evaluated. The modal structural analysis and the lumped, electric circuit parameters are also provided. These results may be of interest in the design stage of these CAs.

This paper presents a technical solution for bearings that combines axial sustentation and radial coupling, for the transmission of rotary motion, which is using permanents only assembled in a unique system. The ensemble is equipped to measure forces, torques, and displacements, and it may be equipped with different inertial masses. Mathematical modeling and numerical simulation are used in the design phase of the prototype with the aim to determine the forces that occur and the coupling torque, the deformations and stress related to total static loads and the first two eigenmodes for the main mechanical parts, which unveil fine details concerning the stability of the bearing system.

This paper presents mathematical modeling and numerical simulation results that are part of a study concerning the dynamics of the stator of piezoelectric (PZ) traveling wave (TW) rotating ultrasonic motor. The stator is a PZ composite ring, and the rotor is a metallic ring. The rotational torque is produced by exciting the stator into a flexural traveling wave, transmitted to the rotor through the stator-rotor friction. A modal analysis provides for the structural eigenfrequencies of the stator. When the AC powering stage providing for two voltages of same amplitude and shifted in quadrature is adapted to a frequency close to the flexural resonance of the stator, the TW reaches higher amplitudes that result in higher rotational velocities because the rotor speed is proportional to the stator TW amplitude.

This paper presents a new active electronic protection system that keeps a high temperature superconductor (HTS) coil that is in superconductive state from shifting into normal conduction state (quench). The coil is made of YBCO tape high temperature superconductor, with a critical temperature of 92 K. The superconducting coil is confined to a cryostat, which is vacuumed at about 0.001 mbar to minimize the heat transfer influx. The cryogenic agent, in which the coil is immersed, is liquid nitrogen, such that the working temperature of the HTS coil is about 77 K. The quench protection system is composed of an electronic quench protection and signal processing system, a power electronic module, and a stabilized voltage power supply, described in the paper.

Energy harvesting devices (EHD) utilize small-scale components with low power losses. Key parts, the electric power transformers (EPTs) are to convert the voltage/current electromagnetic parameters from the primary, energy harvesting stage, to the secondary, storage and delivery power levels. Magnetic colloidal nanofluids seem to be a sound solution for building the magnetic circuit of such EPTs, enabling miniaturized constructions, whose implementation may benefit of LIGA fabrication technology. Because the magnetic cores of EPTs are, at least in part, fluid, the occurring magnetization body forces may result in complex flows that need to be known. Along this line, this paper presents mathematical models and numerical simulation results for a miniature, planar, spiral EPT with hybrid, ferrite-magnetic nanofluid core. Several electric powering schemes are envisaged and the pending flows investigated.

This paper presents mathematical modeling and numerical simulation results for a miniature, planar, spiral transformer (MPST) fabricated in micro-electromechanical MEMS technology. When the MPST is magnetic nanofluid cored, magnetization body forces occur, entraining it into a complex flow. This particular MPST design is then compared with other competing solutions concerning the lumped (circuit) parameters. Finally, the heat transfer problem is solved for different electromagnetic working conditions to assess the thermal loads inside the MPST.

Blood pressure measurement (BPM) is a standard method of investigation for the cardiovascular activity. In this study we are concerned with its usage for the evaluation of the flow in the brachial-ulnar-radial tree. First, we consider a standard piezoelectric transducer (PZT) usable in BPM. Next, we build a mathematical model that sums up the blood flowvessel- muscle-PZT interactions to investigate the BPM information and analyze it numerically. Finally, we present a lumped circuit equivalent that may conveniently be used to analyze the cardiovascular activity monitored through BPM methods.

The paper presents the prototype of an YBCO superferric quadrupolar magnet for high gradient magnetic field generation, design and construction. The temperature of the superconducting coil has to be kept within safe limits or the HTS would exit the superconductive state. Of particular concern is the "warm" beam tube that passes through the magnet. Cryogenic conduction cooling with a closed cycle G-M Cooler may ensure the removal of the ambient heat influx. Numerical simulation results on the magnetic field and heat transfer problems are then discussed. The computational domain is abstracted out of the CAD design of the system. The design solution is presented and compared with the numerical simulations results.

In many applications the chip-embedded core of miniature devices is a micro-structured planar spiral power transformer (MPST), and operational and electromagnetic compatibility are key issues to its sizing. Numerical simulation aided design may then be used to solve them. This paper presents mathematical models and numerical simulation results related to sizing the ferrite core, the lumped parameters of the MPST, and their sensitivity with respect to the core thickness ( the spacing between the planar windings) and the magnetic permeability of the ferrite core. These outcomes may be of interest to the electrical design of the device that uses the MPST and in analyzing its electromagnetic compatibility with the interfering working environment. Finally, we address the high-frequency noise reduction in DC/DC flyback power sources with MPST.

Micro electromechanical systems (MEMS) are complex devices that consist of structural parts, magnetic materials, and electric coils that interact. Their fabrication relies on complex and expensive technologies therefore accurate design solutions that utilize mathematical modeling and numerical simulations. This paper presents a MEMS bending-mode cantilever microactuator (BCM). Two design solution are CAD-virtualized and their behavior in stationary conditions is evaluated by numerical simulations. The eigenfrequency analysis reveals the modal structural behavior of the BCM. These results may be of interest in the design stage of prototyping such devices.

This paper presents a superparamagnetic nanofluid (SMP-NF) and three of its applications. The SPM-NF particles were suspended in oleic acid as surfactant, and then dispersed in UTR 40 transformer oil (TO). The average particle size obtained from X-ray diffraction is 14 nm, and from scanning electron microscopy is between 10 and 30 nm. The magnetic measurements for the oleic-oil transformer acid-magnetite nanoparticles of 27 nm diameter in size and 9.78×10 25 nanoparticles/m 3 particle density system provide for specific saturation magnetization, Ms. The volume fraction is 1.1% and the magnetization is 62 Gs. The SPM-NF may be designed to be used either as coolant or as magnetic medium in three electrotechnic devices: a power electric transformer TMOf 2-36 kV-40 kVA, at 50 Hz, a microactuator that implements the pulse width modulation (PWM) principle, and in miniature planar spiral transformers, for galvanic separation or step-up/step-down conversion. The paper presents experimental and numerical simulation results that confirm that the SPM-NF usage open new venues in optimizing conventional electrotechnic constructions or to design novel devices.