Modellizzazione cross-layer del canale wireless per reti ad-hoc CDMA

Studio di trasmissioni su canale multipath stastico e tempo-variante. Realizzazione di un simulatore in C++ di un ricevitore Rake, calcolo prestazioni e confronto con i convenzionali ricevitori a correlazione

NTRCI Legacy Engine Research and Development Project Final Technical Report

The Legacy engine is a completely new design, transitional diesel engine, replacing the reciprocating engine with a rotary engine. The Legacy engine offers significant advances over conventional internal combustion engines in 1) power to weight ratio; 2) multiple fuel acceptance; 3) fuel economy; and 4) environmental compliance. These advances are achieved through a combination of innovative design geometry, rotary motion, aspiration simplicity, and manufacturing/part simplicity. The key technical challenge to the Legacy engineâs commercialization, and the focus of this project, was the development of a viable roton tip seal. The PST concept for the roton tip seal was developed into a manufacturable design. The design was evaluated using a custom designed and fabricated seal test fixture and further refined. This design was incorporated into the GEN2.5A prototype and tested for achievable compression pressure. The Decision Point at the end of Phase 1 of the project (described below) was to further optimize the existing tip seal design. Enhancements to the tip seal design were incorporated into the GEN2.5B prototype and tested and evaluated using the iterative research strategy described below. Compression pressures adequate for compression ignition of diesel fuel were achieved, although not consistently in all combustion volumes. The variation in compression pressures was characterized versus design features. As the roton tip seal performance was improved, results pointed toward inadequate performance of the housing side seals. Enhancement of the housing side seal system was accomplished using a custom designed side seal test fixture. The design enhancements developed with the test fixture were also incorporated into the GEN2.5B prototype and tested and evaluated using the iterative research strategy described below. Finally, to simplify the requirements for the roton tip seals and to enhance the introduction and combustion of fuel, a flush-mount fuel injector was designed, manufactured and demonstrated in the GEN2.5B prototype

Validation of rainfall estimation derived from commercial DVB received signal with disdrometer, rain gauges and ground based radar

An accurate measurement and monitoring of precipitation events is closely linked with different applications that have an impact on human welfare such as water resources management, and floods, landslides or wildfire risk assessments. Currently rain gauges, disdrometers, ground-based weather radars and satellite sensors (both active and passive) can be considered the conventional devices for precipitation measurements that are worldwide adopted. These devices have different measurement principles, time and space resolution, and accuracy (Gebremichael and Testik, 2013). In the last decade, a new technology that exploits the microwave satellite links has been investigated to retrieve precipitation information. The idea is to estimate the precipitation starting from the attenuation of the signal along its propagation path. Few studies have been carried out in this direction (such as Barthès and Mallet, 2013 and Mercier et al., 2015), showing promising results. In that regards, recently, an Italian project called NEFOCAST, funded by Tuscany Region (Italy), has been carried out with the aim of estimating rainfall rate from attenuation measurements made available by commercial interactive digital video broadcasting (DVB) receivers, called smartLNBs. During the NEFOCAST project, an ad hoc rainfall retrieval algorithm has been developed, tuned and tested. It allows to estimate, with 1-minute rate, the instantaneous rainfall rate (R, in mm/h) from the ratio η = Es/N0 between the received energy-per-symbol Es and the one-sided power spectral density of the additive white Gaussian noise N0, (Giannetti et al. 2017). To validate the algorithm, a 1-year field campaign (from January 2018 to January 2019) was conducted. The collected data allow to compare the SmartLNB precipitation estimates with the measurements gathered by ‘conventional’ meteorological devices such as rain gauges, weather radar and disdrometer. A network of 24 smartLNBs was deployed in Tuscany, along with 11 rain gauges and one X-band dual-polarization weather radar. Furthermore, the performance of the NEFOCAST algorithm has been preliminarily tested by comparing data provided from one SmartLNB installed at the Institute of Atmospheric Sciences and Climate (ISAC) of CNR in Rome (Italy) with a co-located laser disdrometer. For this site, data from a dual polarization C-band weather radar (Polar55C) could be compared with SmartLNB measurements along the Earth-satellite link. In fact, during the project the Polar55C has been aimed in the same direction as the SmartLNB, with the same elevation angle, thus scanning the same portion of atmosphere where the SmartLNB signal was propagating. Preliminary results show a good agreement between the total cumulative precipitation (in mm) obtained from SmartLNB data and the one collected by the co-located disdrometer during different rainfall events. The corresponding values of Normalized Mean Absolute Error (NMAE) and Root Mean Square Error (RMSE) obtained comparing the total cumulative precipitations obtained from SmartLNB and disdrometer are 41% and 4.71 mm, respectively. Encouraging results come also from the comparison of the total precipitation amounts as measured by the network of SmartLNBs and rain gauges, with values of NMAE (RMSE) that range between 39% and 53% (2.8 mm and 8.0 mm), depending on the specific site

The Potential of Smartlnb Networks for Rainfall Estimation

NEFOCAST is a research project that aims at retrieving rainfall fields from channel attenuation measurements on satellite links. Rainfall estimation algorithms rely on the deviation of the measured Es/N0 from the clear-sky conditions. Unfortunately, clear-sky measurements exhibit signal fluctuations (due to a variety of causes) which could generate false rain detections and reduce estimation accuracy. In this paper we first review the main causes of random amplitude fluctuations in the received Es/N0, and then we present an adaptive tracking algorithm based on two Kalman filters: one that tracks slow changes in Es/N0 due to external causes and another which tracks fast Es/N0 variations due to rain. A comparison of the outputs of the two filters confirms the reliability of the rainfall rate estimate

Real-time rain rate evaluation via satellite downlink signal attenuation measurement

We present the NEFOCAST project (named by the contraction of "Nefeleâ", which is the Italian spelling for the mythological cloud nymph Nephele, and "forecast"), funded by the Tuscany Region, about the feasibility of a system for the detection and monitoring of precipitation fields over the regional territory based on the use of a widespread network of new-generation Eutelsat "SmartLNB" (smart low-noise block converter) domestic terminals. Though primarily intended for interactive satellite services, these devices can also be used as weather sensors, as they have the capability of measuring the rain-induced attenuation incurred by the downlink signal and relaying it on an auxiliary return channel. We illustrate the NEFOCAST system architecture, consisting of the network of ground sensor terminals, the space segment, and the service center, which has the task of processing the information relayed by the terminals for generating rain field maps. We discuss a few methods that allow the conversion of a rain attenuation measurement into an instantaneous rainfall rate. Specifically, we discuss an exponential model relating the specific rain attenuation to the rainfall rate, whose coefficients were obtained from extensive experimental data. The above model permits the inferring of the rainfall rate from the total signal attenuation provided by the SmartLNB and from the link geometry knowledge. Some preliminary results obtained from a SmartLNB installed in Pisa are presented and compared with the output of a conventional tipping bucket rain gauge. It is shown that the NEFOCAST sensor is able to track the fast-varying rainfall rate accurately with no delay, as opposed to a conventional gauge

Comparative Safety of Originator and Biosimilar Epoetin Alfa Drugs: An Observational Prospective Multicenter Study

Background: Erythropoiesis-stimulating agents (ESAs) are biological molecules approved for the treatment of anemia associated with chronic renal failure. Biosimilars were licensed for use in Europe in 2007. Aim: This study aimed to compare the safety profile of biosimilars with respect to the reference product in a nephrology setting. Methods: A prospective study was conducted in four Italian regions between 1 October 2013 and 30 June 2015. The study population included patients aged 65 18 years undergoing hemodialysis and treated with epoetins as per the clinical practice of the participating centers. The two comparison cohorts included patients treated with either an originator or a biosimilar epoetin alfa. Each patient was followed up until occurrence of any safety outcome of interest (grouped into three major categories), switch to a different ESA product, transplant or peritoneal dialysis, death, or end of the study period, whichever came first. Results: Overall, 867 subjects were included in the study (originator: N = 423; biosimilar: N = 444). Biosimilar users were older than originator users (median age of 76 vs 64 years, respectively), more frequently affected by arrhythmia (29.3 vs 22.5%), and less frequently candidates for transplantation (3.8 vs 18.2%). Cox-regression analysis showed no increase in risk of safety outcomes in biosimilar users, even after adjusting for confounding factors: 1.0 (95% confidence interval [CI] 0.7\u20131.3) for any outcomes; 1.1 (95% CI 0.7\u20131.8) for problems related to dialysis device; 0.9 (95% CI 0.6\u20131.5) for cardio- and cerebro-vascular conditions; 0.9 (95% CI 0.6\u20131.5) for infections. Conclusion: This study confirms the comparable safety profiles of originator and biosimilar epoetin alfa drugs when used in patients receiving dialysis