1,720,998 research outputs found
Metodologia innovativa di analisi preventiva di tipo Safety Review in ambito autostradale
No full textPerformance of mMIMO FD Relay Networks with Limited Relay State Knowledge
Full text linkMassive MIMO (mMIMO) is a key technology for improving propagation conditions and extending geographical coverage of wireless communications. We here address a mMIMO full-duplex relay network for machine-type-communications where channel state information availability at the transmitter is impractical. In this scenario, we argue that high end-to-end data rates can be achieved even if no precoding is performed at the transmitting nodes. We first formulate an optimization problem aiming at maximizing the achievable rate, considering the source transmit power to depend on the transmit power distribution at the relay node. We then solve this problem by letting the number of antennas grow large, and derive closed-form expressions for the transmit power at the source and relay, as well as for the system data rate. Our results, show that the rate obtained when no precoding is implemented at the relay, or at any of the transmitters, closely matches that of SVD precoding under the optimum receiver, and still achieves very high values in the case of the ZF and the MMSE receiver
Trasporto e distribuzione delle merci in ambito urbano. Un progetto innovativo di City Logistics attraverso l’applicazione di un Transit Point Intermodale
No full textA calculation code for the air pollution valuation produced by duty vehicle moving in an urban area
No full textScientific research that started three years ago and was first developed in a Ph.D., has resulted in important results in producing a calculation code in “Excel” that values the main pollutant emissions (CO, NOx, VOC and PM) produced by duty vehicles moving in an urban area. Emissions were obtained by studying data about the main geometrical and flow features of transport network in the area covered. Two mathematical models were integrated in the developed code, a flow and an emission model respectively. The flow simulation model determines, after a calibration according to the particular urban area in examination, the average vehicular speed on a single homogeneus branch of a road network. So, when the average speed is fixed, it is possible to calculate the polluting emissions through the definition of an opportune emission model integrated in the code. The emission model is based on the CORINAIR methodology, implemented in the COPERT III program (COmputer Programme to calculate Emissions from Road Transport) that, where necessary, has been modified according to experimental results, without distorting its basic philosophy. In conclusion, the calculation code allows for making choices in the transport fields considering environmental sustainabilityy aspects in the urban planning analysis, and it represents a good decision support system (DSS)
Asymptotics of multi-fold vandermonde matrices with applications to communications and radar problems
No full textWe study the performance of signal estimation and reconstruction systems, that exploit the linear minimum mean square error (LMMSE) technique. This model often occurs in signal processing and wireless communications; some examples are radar applications, MIMO communications, or sensor networks sampling a physical field. Our performance analysis implies the characterization of a random matrix product, involving a multifold Vandermonde matrix with complex exponential entries. We therefore derive the LMMSE by computing the η-transform of this matrix product, which can be evaluated either by implicit as well as by explicit expression, using the matrix asymptotic moments. Finally, we show how our results can be applied in some cases of practical interest. ©2009 IEEE
La strategia del car-sharing per una mobilità sostenibile. Il caso di Genova con la tipologia di CS 'misto
No full textModelli e strumenti per la pianificazione della mobilità urbana
No full textIn this chapter the basic elements of the model for transportation systems are described in detail. In particular, the basic assumptions and models of transportation supply are analyzed, starting with the definition of graphs till the characterization of cost function of links, and the mobility demand models, starting with the behavioral models, till the “four stages” model. Finally, the interaction between demand and supply are analyzed, and the differences between passenger and freight mobility are discussed
Going Beyond Counting First Authors in Author Co-citation Analysis
Full text linkThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
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