Search results for "bidirectional"
showing 10 items of 39 documents
Adapting hierarchical bidirectional inter prediction on a GPU-based platform for 2D and 3D H.264 video coding
2013
The H.264/AVC video coding standard introduces some improved tools in order to increase compression efficiency. Moreover, the multi-view extension of H.264/AVC, called H.264/MVC, adopts many of them. Among the new features, variable block-size motion estimation is one which contributes to high coding efficiency. Furthermore, it defines a different prediction structure that includes hierarchical bidirectional pictures, outperforming traditional Group of Pictures patterns in both scenarios: single-view and multi-view. However, these video coding techniques have high computational complexity. Several techniques have been proposed in the literature over the last few years which are aimed at acc…
The role of the Access Point in Wi-Fi networks with selfish nodes
2009
In Wi-Fi networks, mobile nodes compete for accessing the shared channel by means of a random access protocol called Distributed Coordination Function (DCF), which is long term fair. But recent drivers allow users to configure protocol parameters differently from their standard values in order to break the protocol fairness and obtain a larger share of the available bandwidth at the expense of other users. This motivates a game theoretical analysis of DCF. Previous studies have already modeled access to a shared wireless channel in terms of non-cooperative games among the nodes, but they have mainly considered ad hoc mode operation. In this paper we consider the role of the Access Point (AP…
Resource sharing optimality in WiFi infrastructure networks
2009
In WiFi networks, mobile nodes compete for accessing a shared channel by means of a random access protocol called Distributed Coordination Function (DCF). Although this protocol is in principle fair, since all the stations have the same probability to transmit on the channel, it has been shown that unfair behaviors may emerge in actual networking scenarios. Assuming that a contending node can dynamically change its strategy, by tuning its contention parameters to non-standard values on the basis of channel observations, we prove that, for infrastructure networks with bidirectional traffic and homogeneous application requirements, selfish access strategies are able to reach equilibrium condi…
Performance analysis of selfish access strategies on WiFi infrastructure networks
2009
In this paper we propose a game-theoretic approach for characterizing WiFi network performance in presence of intelligent nodes employing cognitive functionalities. We assume that a cognitive WiFi node is aware of its application requirements and is able to dynamically estimate the network status, in order to dynamically change its access strategy by tuning the contention window settings. We prove that, for infrastructure networks with bidirectional traffic and homogeneous application requirements, selfish access strategies are able to reach equilibrium conditions, which are also Pareto optimal. Indeed, we show that the station strategies converge toward values which maximize a per-node uti…
Prototype for Surface Albedo Retrieval Based on Sentinel-3 OLCI and SLSTR Data in the Framework of Copernicus Climate Change
2021
This work describes the different algorithmic steps used to retrieve the first Surface Albedo (SA) product based on Sentinel-3 (S-3) data in the framework of the Copernicus Climate Change Service (C3S). The atmospherically corrected Top-Of-Atmosphere (TOA) reflectances into Top-Of-Canopy (TOC) reflectances are brokered from the Copernicus Global Land Service (CGLS). The TOC reflectances are used to obtain a BRDF model. Next, the spectral and angular integration steps are implemented, which take the latter coefficients as input to produce spectral and broadband albedo quantities. The preliminary quality assessment of BSA broadband albedo for the total shortwave shows good overall spatiotempo…
<title>Methodology for quantitative analysis of scaling effects in multiresolution datasets acquired with airborne sensors flying at different …
2001
Scaling issues are always playing a critical role in most studies based on remote sensing data. The process of getting quantitative scaling information from raw multi-resolution images is not trivial, and many aspects must be taken very carefully into consideration. To get a better picture about the role of spatial resolution, we conducted a series of flights in summer 1997, in several test sites over Spain and Portugal. In order to minimize the time of acquisition (to get minimal changes in atmospheric status and solar illumination) we used three flight altitude levels, that produced images with 1.25 m, 3 m and 12 m resolutions. The main steps in our methodology are: a) Geometrical registr…
Studies on a new potential dopaminergic agent: in vitro BBB permeability, in vivo behavioural effects and molecular docking evaluation.
2015
2-Amino-N-[2-(3,4-dihydroxy-phenyl)-ethyl]-3-phenyl-propionamide (DA-PHEN) has been previously synthesized to obtain a potential prodrug capable of release dopamine (DA) into CNS. However, DA-PHEN could act per se as a dopaminergic drug. In this study, the permeability transport (Pe), obtained by parallel artificial permeability assay (PAMPA), indicated a low passive transcellular transport (Pe = 0.32 ± 0.01 × 10(-6 )cm/s). Using the Caco-2 cell system, the Papp AP-BL in absorptive direction (3.36 ± 0.02 × 10(-5 )cm/s) was significantly higher than the Papp BL-AP in secretive direction (1.75 ± 0.07 × 10(-5 )cm/s), suggesting a polarized transport. The efflux ratio (Papp AP-BL/Papp BL-AP = 0…
An Innovative Conversion Device to the Grid Interface of Combined RES-Based Generators and Electric Storage Systems
2015
This paper is focused on the development of an innovative device, which is based on a bidirectional converter, for the interface to the supply utility grid of combined renewable-energy-source-based generators and electric storage systems. The device can be controlled so as to ease the interface between the low-voltage grid and photovoltaic or wind generators combined with lithium-ion $\hbox{LiFePO}_{4} $ batteries, taking into account the requirements of the reference technical standards for users connection and offering different ancillary services. The operational functioning of the device, the architecture, and its electronic components, as well as laboratory and field test activities an…
A bidirectional converter for the integration of LiFePO4 batteries with RES-based generators. Part II: Laboratory and field tests
2014
This paper presents a device for controlling and connecting combined Renewable Energy Sources (RES)-based generators and electric storage systems to the supply utility grid. The device is a bidirectional converter that can be controlled in order to facilitate the interface between the low voltage grid and small generators combined with Li-ion batteries, contemporary addressing the requirements of the reference technical standards for users connection and providing different ancillary services. The paper describes the laboratory and field test activities carried out by the DEIM of the University of Palermo and ENEA during 2013.
A New Device for the Control and the Connection to the Grid of Combined RES-based Generators and Electric Storage Systems
2013
In this paper a new device for the control and the connection to the supply utility grid of combined RES-based generators and electric storage systems is presented. The device is a bidirectional converter that can be controlled so as to facilitate the interface between the low voltage grid and photovoltaic or wind generators combined with batteries, contemporary addressing the requirements of the reference technical standards for users connection and providing different ancillary services. In the paper the functioning of the device and its circuit diagram are described, the single parts are shown and the potentiality of its control system are commented. © 2013 IEEE.