Search results for " key"
showing 10 items of 409 documents
El socialismo liberal / 5
2008
A simple joint estimation-detection technique for OFDM systems
2005
In this work a simple approach for the joint estimation-detection in a frequency selective severe fading environment of OFDM signals adopting PSK constellations is presented. A linear predictor of suitable order is adopted for the channel estimation in the frequency domain. The predictor coefficients are estimated on the basis of a sample estimation of the autocorrelation of the channel frequency response, aided by a preliminary differential decoding, in a blockwise manner. The detection technique proposed here is based on a simple tree search where a small number of best survivor paths are maintained at each step. Despite the simplicity of above detection approach, the simulation results s…
Optimum pulse shape for minimum spectral occupancy in FSK signals
1984
The characteristics of a frequency shift keying (FSK) signal giving rise to maximum power within a prescribed frequency band are determined. The baseband pulse shape extends over any integer number of bit periods. An integral equation for the optimum pulse shape is derived and some simple properties of the solution are investigated. The equation has been solved for some values of the product of the prescribed band times the pulse duration and the signal shape is shown. Our results for the particular case of pulses only one bit period long are presented for purpose of comparison with results known in the literature. Plots of out-of-band power for some values of the prescribed band and of pul…
Design and Characterization of a New MV PLC Coupler for Smart Electric Energy Systems
2018
This paper deals with the design, modeling and characterization of a new coupling system for medium voltage (MV) narrow band power line communications (NB-PLC). It exploits the capacitive divider of voltage detecting systems (VDSs) normally used to reveal the mains voltage presence, thus avoiding the use of dedicated MV couplers. The proposed coupling system was patented by the authors. In this paper, the modeling of the VDS capacitive divider is presented, using a proper characterization method. Moreover, the interface card design is described, based on simulation of the whole PLC transmission channel. Laboratory tests are also presented and discussed. More in detail, a frequency response …
On the error sequences of M-ary FSK modulation schemes over Nakagami-m fading channels
2012
In this paper, we have studied some important statistical properties of error sequences of M-ary orthogonal frequency-shift keying (FSK) modulation schemes over Nakagami-m fading channels. We have derived the joint probability density function (PDF) of error sequences of arbitrary length. From the joint PDF, we have found an analytical solution for the autocorrelation function (ACF) of the error sequences. The correctness of the analytical expression for the ACF of error sequences has been confirmed by simulations, where the simulation results are obtained by using the sum-of-sinusoids principle. The derived joint PDF of error sequences is useful for the development of first-order and highe…
The uses of urban fortresses of Burgundy in the modern times
2011
Study the urban fortresses of Burgundy means interesting in the relationships between, on the one hand, these buildings and their occupants and, on the other hand, the society in which they are located. A city with a castle isn’t necessarily a castral town. The castle can generate, move or expand a city. Its representation also reflects its place in society. The genesis of the city often has consequences throughout the modern times on relationships between the castle and the city. In wartime, the castle can be the ruin or the salvation for the city. In peacetime, it’s most often a dead weight : it must be maintained, sometimes its garnison must be maintained too. But in the dialectic cities…
Keypoint descriptor matching with context-based orientation estimation
2014
Abstract This paper presents a matching strategy to improve the discriminative power of histogram-based keypoint descriptors by constraining the range of allowable dominant orientations according to the context of the scene under observation. This can be done when the descriptor uses a circular grid and quantized orientation steps, by computing or providing a global reference orientation based on the feature matches. The proposed matching strategy is compared with the standard approaches used with the SIFT and GLOH descriptors and the recent rotation invariant MROGH and LIOP descriptors. A new evaluation protocol based on an approximated overlap error is presented to provide an effective an…
Two new antarctic species of the genus Schizotricha Allman, 1883 (Cnidaria, Hydrozoa)
1998
Two new antarctic species of the genus Schizotricha Allman have been studied. The material comes from the Scotia Sea (Antarctica) and was collected by the Spanish antarctic expedition `Antartida 8611'. Both species are described and figured and the systematic position is discussed. A general survey of the geographical and bathymetrical distribution of the antarctic and subantarctic species of the genus is given. Finally, a key for the identification of the antarctic and subantarctic species of the genus, together with a comparative table including main features, are presented.
Environmental Sustainability Approaches and Positive Energy Districts: A Literature Review
2021
During the last decade, increasing attention has been paid to the emerging concept of Positive Energy Districts (PED) with the aim of pushing the transition to clean energy, but further research efforts are needed to identify design approaches optimized from the point of view of sustainable development. In this context, this literature review is placed, with a specific focus on environmental sustainability within innovative and eco-sustainable districts. The findings show that some sustainability aspects such as sustainable food, urban heat islands mitigation and co-impacts, e.g., green gentrification, are not adequately assessed, while fragmented thinking limits the potential of circularit…
The role of family-related factors in the effects of the UP4FUN school-based family-focused intervention targeting screen time in 10- to 12-year-old …
2014
Background Screen-related behaviours are highly prevalent in schoolchildren. Considering the adverse health effects and the relation of obesity and screen time in childhood, efforts to affect screen use in children are warranted. Parents have been identified as an important influence on children’s screen time and therefore should be involved in prevention programmes. The aim was to examine the mediating role of family-related factors on the effects of the school-based family-focused UP4FUN intervention aimed at screen time in 10- to 12-year-old European children (n child–parent dyads = 1940). Methods A randomised controlled trial was conducted to test the six-week UP4FUN intervention in 10-…