Search results for "FDM"

FLUMO: FLexible Underwater MOdem

2019

The last years have seen a growing interest in underwater acoustic communications because of its applications in marine research, oceanography, marine commercial operations, the offshore oil industry and defense. High-speed communication in the underwater acoustic channel has been challenging because of limited bandwidth, extended multipath, refractive properties of the medium, severe fading, rapid time variation and large Doppler shifts. In this paper, we show an implementation of a flexible Software-Defined Acoustic (SDA) underwater modem, where modulation parameters are completely tunable to optimize performance. In particular, we develop the system architecture following two key ideas. …

Architectures and Protocols for Flexible Physical Layers in Wireless Networks

Emerging wireless technologies are characterized by an increasing level of flexibility and programmability, not only in terms of core network functionalities, with the consolidated paradigms of software-defined-networks and function virtualization, but also in terms of radio access functionalities. Although the concept of software-defined PHY and MAC protocols is not new, exploiting flexibility at the lower layers of the protocol stack is not an easy task, because of complexity and performance constraints. Indeed, dealing with software-defined implementations of the radio implies managing complex software routines, often tightly inter-dependent and difficult to reuse, and poses some perform…

MUSIC-based modal channel estimation for wideband OFDM-OQAM

2008

Orthogonal frequency division multiplexing based on offset quadrature amplitude modulation (OFDM-OQAM) over wideband frequency selective multipath channels suffers from inter-symbol interference (ISI) and inter-carrier interference (ICI) that degrade its performance. Channel estimation and equalization are needed to combat these interferences. In this paper a novel channel estimator for passband OFDM-OQAM signaling over wideband multipath channels, which is based on multiple signal classification (MUSIC) with the Spatial Smoothing technique is presented. Numerical simulation results are presented in the low number of subcarriers, i.e. wideband, scenario.

Analysis and performance of FBMC techniques with application to relay networks

2014

A Finite Difference Model of a PV-PCM System

2012

Abstract The performances of a photovoltaic panel (PV) are defined according to the “peak power” that identifies the maximum electric power supplied by the panel when it receives an insolation of 1 kW/m2 and the temperature of the cell is maintained at 25 °C. These conditions are only nominal since the solar radiation has a variable intensity and also the panel is subjected to thermal excursions; due to these reasons the real power efficiency of the panel is considerably lower than that obtainable in the nominal conditions. The study focused on assessing a method to reduce the peak temperatures of PV systems using Phase Change Materials (PCM). To this aim it was created a numerical model ca…

A numerical solution that determines the temperature field inside phase change materials: application in buildings

2013

The use of novel building materials that contain active thermal components would be a major advancement in achieving significant heating and cooling energy savings. In the last 40 years, Phase Change Materials or PCMs have been tested as thermal mass components in buildings, and most studies have found that PCMs enhance the building energy performance. The use of PCMs as an energy storage device is due to their relatively high fusion latent heat; during the melting and/or solidification phase, a PCM is capable of storing or releasing a large amount of energy. PCMs in a wall layer store solar energy during the warmer hours of the day and release it during the night, thereby decreasing and sh…

TORSIONAL STRESS CONCENTRATIONS IN SHAFTS: FROM ELECTRICAL ANALOGIES TO NUMERICAL METHODS

2013

This paper presents the historical development of methods used for the study of torsional stresses in shafts. In particular the paper covers both analog methods, in particular those based on electrical analogies proposed since about 1925, and numerical methods, in particular finite difference methods (FDM), finite element methods (FEM) and boundary elements (BEM).

3D-Printed Products for Topical Skin Applications: From Personalized Dressings to Drug Delivery.

2021

3D printing has been widely used for the personalization of therapies and on-demand production of complex pharmaceutical forms. Recently, 3D printing has been explored as a tool for the development of topical dosage forms and wound dressings. Thus, this review aims to present advances related to the use of 3D printing for the development of pharmaceutical and biomedical products for topical skin applications, covering plain dressing and products for the delivery of active ingredients to the skin. Based on the data acquired, the important growth in the number of publications over the last years confirms its interest. The semisolid extrusion technique has been the most reported one, probably …

Synthesis and application of orthogonal signal bases possessing enhanced timefrequency localization for mobile wireless networks

2012

Efficient pipeline FFT processors for WLAN MIMO-OFDM systems

2005

The most area-efficient pipeline FFT processors for WLAN MIMO-OFDM systems are presented. It is shown that although the R2/sup 3/SDF architecture is the most area-efficient approach for implementing pipeline FFT processors, RrMDC architectures are more efficient in MIMO-OFDM systems when more than three channels are used.