Search results for "Computer Networks and Communication"

CORMORANT

2019

People own and carry an increasing number of ubiquitous mobile devices, such as smartphones, tablets, and notebooks. Being small and mobile, those devices have a high propensity to become lost or stolen. Since mobile devices provide access to their owners' digital lives, strong authentication is vital to protect sensitive information and services against unauthorized access. However, at least one in three devices is unprotected, with inconvenience of traditional authentication being the paramount reason. We present the concept of CORMORANT, an approach to significantly reduce the manual burden of mobile user verification through risk-aware, multi-modal biometric, cross-device authentication…

Hereditariness of Aortic Tissue: In-Vitro Time-Dependent Failure of Human and Porcine Specimens

2018

This study aims to investigate the time dependent failure of aortic tissues for pathological and healthy samples by biomechanical testing. The experimental campaign has involved human pathological tissue and healthy swine tissue as preliminary study towards the development of novel failure criteria.

Geometry-Based Statistical Modeling of Non-WSSUS Mobile-to-Mobile Rayleigh Fading Channels

2017

In this paper, we present a novel geometry-based statistical model for small-scale non-wide-sense stationary uncorrelated scattering (non-WSSUS) mobile-to-mobile (M2M) Rayleigh fading channels. The proposed model builds on the principles of plane wave propagation to capture the temporal evolution of the propagation delay and Doppler shift of the received multipath signal. This is different from existing non-WSSUS geometry-based statistical channel models, which are based on a spherical wave propagation approach, that in spite of being more realistic is more mathematically intricate. By considering an arbitrary geometrical configuration of the propagation area, we derive general expressions …

A Unified Disk Scattering Model and Its Angle-of-Departure and Time-of-Arrival Statistics

2013

This paper proposes a novel probability density function (PDF) for the distribution of local scatterers inside a disk centered on the mobile station (MS). The new scattering model is introduced as the unified disk scattering model (UDSM), as it unifies a variety of typical circularly symmetric scattering models into one simple model. By adjusting a designated shape factor controlling the distribution of the scatterers, both the uniform circular and uniform ring scattering models can be obtained as special cases. Furthermore, the original Gaussian and uniform hollow-disk scattering models can be approximated with a high level of accuracy. In addition to these established scattering models, a…

Optimization of Gyrotron Resonator’s Dimensions

2021

This paper explains the procedure of determining the initial dimensions of a gyrotron resonator. In particular, the paper discusses which geometrical parameters impact the wave properties of the resonator. The solution is implemented using Matlab software and estimations are performed with the use of the SMath Studio spreadsheet. © 2021 National Institute of Telecommunications. All rights reserved.

Rigorous analysis of three-dimensional beam transmission through a dielectric slab

1997

The plane-wave-spectrum technique is applied to study the transmission of a three-dimensional beam through a dielectric slab. The electromagnetic beam radiated from an aperture antenna is represented by an angular spectrum of plane waves. The use of three different co-ordinate systems using rectangular co-ordinates allows a rigorous formulation to be obtained. The near field transmitted through a dielectric slab is obtained and compared with measurements.

Effect of Acoustic Wave Reflections on Space Charge Measurements with PEA Method

2018

The Pulsed Electro-Acoustic (PEA) method is the most used technique for space charge detection in solid dielectrics. The methodology is largely employed in the field of High Voltage Direct Current (HVDC) transmission and is based on the detection of acoustic waves generated by charges vibration. One of the most common problems arising during the detection is the presence of multiple reflections taking place due to the presence of means discontinuity in the different PEA cell components. This reflection phenomenon, if not well taken into account, could cause incorrect interpretation of the PEA output signal. It is easy to understand that a simulation model is a basic tool to understand the w…

STOCHASTIC ANALYSIS OF ONE-DIMENSIONAL HETEROGENEOUS SOLIDS WITH LONG-RANGE INTERACTIONS

2011

Random mass distribution in one-dimensional (1D) elastic solids in the presence of long-range interactions is studied in this paper. Besides the local Cauchy contact forces among adjacent elements, long-range forces depending on the product of interacting masses, as well as on their relative displacements, are considered. In this context, the random fluctuations of the mass distribution involve a stochastic model of the nonlocal interactions, and the random displacement field of the body is provided as the solution of a stochastic integro-differential equation. The presence of the random field of mass distribution is reflected in the random kernel of the solving integro-differential equatio…

A STRAIN-DIFFERENCE BASED NONLOCAL ELASTICITY THEORY FOR SMALL-SCALE SHEAR-DEFORMABLE BEAMS WITH PARAMETRIC WARPING

2020

Correlation and Spectral Properties of Vehicle-to-Vehicle Channels in the Presence of Moving Scatterers

2013

This paper derives a vehicle-to-vehicle (V2V) channel model assuming a typical propagation scenario in which the local scatterers move with random velocities in random directions. The complex channel gain of the proposed V2V channel model is provided. Subsequently, for different scatterer velocity distributions, the corresponding autocorrelation function (ACF), power spectral density (PSD), and the Doppler spread of the channel are derived, shown, and confirmed by the available measurement data. It is shown that the Gaussian mixture (GM) and the exponential distribution can accurately describe the velocity distribution of relatively fast and slow moving scatterers, respectively. Since the p…