Search results for "electromagnetic"

showing 10 items of 1595 documents

Bio-electromagnetic Numerical Modeling for Health Diagnostics

Settore ING-IND/31 - ElettrotecnicaSettore MAT/08 - Analisi Numericabioelectromagnetic fields bioelectromagnetism numerical methods medical imaging neuroimaging brain activity electroencephalography magnetoencephalography EEG MEG meshfree meshless method of fundamental solutionscampi bioelettromagnetici bioelettromagnetismo metodi numerici diagnostica per immagini attività cerebrale elettroencefalografia magnetoencefalografia metodo delle soluzioni fondamentali
researchProduct

Un metodo numerico incodizionatamente stabile mesh-free per l'analisi elettromagnetica

2012

Settore ING-IND/31 - Elettrotecnicameshfree numerical method computational electromagnetics
researchProduct

Rateless Codes Performance Analysis in Correlated Channel Model for GEO Free Space Optics Downlinks

2012

Settore ING-INF/03 - TelecomunicazioniFree Space Optics (FSO) technologies for satellite communications offer several advantages: wide bandwidth high rate capability immunity to electromagnetic interference and small equipment size. Thus they are suitable for inter-satellite links deep space communications and also for high data rate ground-to-satellite/satellite-to-ground communications. Nevertheless FSO links suffer impairments that cause power signal degradation at the receiver. Scattering and absorption cause power signal attenuations predictable by suitable deterministic models. Optical turbulence causes random irradiance fluctuations which can generate signal fading events and can thereby only be predicted by statistical models. Attenuation and fading events can corrupt FSO links and so it would be recommended to add mitigation error codes on the communication link. FSO channel can be described as an erasure channel: fading events can cause erasure errors. We have identified in rateless codes (RCs) a suitable solution to be employed in FSO links. RCs do not need feedback and they add a redundant coding on the source data that allows the receiver to recover the whole payload despite erasure errors. We implemented two different of rateless codes: Luby Transform (LT) and Raptor. We analyzed their performances on a simulated turbulent GEO FSO downlink (1 Gbps - OOK modulation) at a 106 μm wavelength and for different values of zenith angles. Assuming a plane-wave propagation and employing Hufnagel-Valley we modeled the downlink using: 1) a temporal correlated channel model based on Gamma-Gamma probability distribution and 2) an irradiance covariance function that we converted on a time function using Taylor frozen eddies hypothesis. Our new channel model is able to simulate irradiance fluctuations at different turbulence conditions as it will be shown in the full paper. We will also report performance results of LT and Raptor codes at overhead range varying between 0 and 50% and for different values of source packets.Settore ING-INF/01 - Elettronica
researchProduct

Studies in thermal and dynamical duality

2011

Settore MAT/07 - Fisica MatematicaT-duality vortex loops cosmic string loops electromagnetic radiation
researchProduct

Smoothed Particle Electromagnetics Modelling on HPC-GRID Environment

2012

In this paper a meshless approach on a high performance grid computing environment to run fast onerous electromagnetic numerical simulations, is presented. The grid computing and the message passing interface standard have been employed to improve the computational efficiency of the Smoothed Particle Electromagnetics meshless solver adopted. Applications involving an high number of particles can run on a grid computational environment simulating complex domains not accessible before and offer a promising approach for the coupling of particle models to continuous models. The used meshless solver is straightforward to program and fully parallelizable. The results of the parallel numerical sch…

Settore MAT/08 - Analisi NumericaSettore ING-IND/31 - ElettrotecnicaElectromagnetic Simulation Grid Computing Meshless method Smoothed Particle Electromagnetics
researchProduct

Computational issues of an electromagnetics transient meshless method

2019

In this paper we refer to the computational issues in solving Maxwell’ s curl equations without using any connectivity among the points in which the problem domain is discretized. The adopted procedure is able to approximate the electric and magnetic vector fields making use of the derivatives of a kernel function at points arranged in the computational domain. In order to improve the numerical accuracy, dealing with irregular data distribution or data located near the boundary, a suitable strategy is considered. The computational core of the overall process requires elementary linear algebra operations. In the paper the method is presented and the discussion is revolved to the computationa…

Settore MAT/08 - Analisi NumericaSettore ING-IND/31 - ElettrotecnicaElectromagneticsComputer scienceMesheLinear algebraLinear algebraTransient (oscillation)Scientific computingComputational scienceAIP Conference Proceedings
researchProduct

An improved Smoothed Particle ElectroMagnetics method in 3D time domain simulations

2012

In this paper, an enhanced variant of the meshless smoothed particle electromagnetics (SPEM) method is performed in order to solve PDEs in time domain describing 3D transient electromagnetic phenomena. The method appears to be very efficient in approximating spatial derivatives in the numerical treatment of Maxwell's curl equations. In many cases, very often, accuracy degradation, due to a lack of particle consistency, severely limits the usefulness of this approach. A numerical corrective strategy, which allows to restore the SPEM consistency, without any modification of the smoothing kernel function and its derivatives, is presented. The method allows to restore the same order of consiste…

Settore MAT/08 - Analisi NumericaSettore ING-IND/31 - ElettrotecnicaNumerical modellingconsistency restoringSmoothed Particle Electromagnetics smoothed particle electromagnetics (SPEM)
researchProduct

Mobile phone and auditory system: update

2009

The aim of this study is to asses the non-thermal effects of the electromagnetic fields generated by 915 MHz GSM cellular phones on the human cochlear activity using transient evoked otoacoustic emissions (TEOAE). The study was carried on 205 young and healthy volunteers (age 18-30 years) with normal hearing which were randomly divided into two samples consisting of 85 (Gcase) and 120 (Gcontrol) respectively. The first one was exposed to genuine 10 minutes of GSM electromagnetic fields while the second, undergone sham exposure, was considered as control group for the statistical investigations. All the participants were blind to the genuine or sham exposure. The TEOAEs were measured in the …

Settore MED/31 - OtorinolaringoiatriaGSM Electromagnetic Fields Auditory system Outer sensory cells TEOAESettore MED/32 - Audiologia
researchProduct

Influence of mobile phone electromagnetic fields on TEOAEs recordings

2006

Settore MED/31 - Otorinolaringoiatriaelectromagnetic fieldTEOAEMobile phoneSettore MED/32 - Audiologia
researchProduct

Flow-induced structures in magnetorheological suspensions

1999

We have measured the yield stress of a magnetic suspension as a function of the external field. To explain the existence of this yield stress, we report a comparison between two models, one based on isolated chains of particles and the other taking into account that the structure is formed by aggregates of particles.

Shear modulusShear rateClassical mechanicsMaterials scienceRheologyField (physics)Critical resolved shear stressMagnetorheological fluidElectromagnetic suspensionComposite materialCondensed Matter PhysicsShear flowElectronic Optical and Magnetic MaterialsJournal of Magnetism and Magnetic Materials
researchProduct