The Durability of Composite Wood-Steel Systems

Nell\u2019ambito della valutazione e del controllo della qualit\ue0 tecnologica in edilizia, la conoscenza del comportamento nel tempo dei prodotti e componenti complessi per l\u2019edilizia, risulta aspetto fondamentale, in particolare per quei prodotti tecnologicamente \u201cinnovativi\u201d per i quali la normativa non prevede ancora prove specifiche per valutarne la durabilit\ue0. In particolare, oggi risulta sempre pi\uf9 diffuso l\u2019impiego di sistemi assemblati o con connessioni tra materiali di diversa natura, tra cui i sistemi legno-acciaio, ottenuti rinforzando le travi in legno lamellare con piastre in acciaio forate, incollati mediante una resina epossidica bicomponente. Tali sistemi, che sono stati gi\ue0 oggetto di sperimentazione sul comportamento a flessione del sistema trave in legno lamellare e solaio collaborante in calcestruzzo, affidano la loro efficacia in riguardo alla resistenza ed alla rigidezza attraverso gli sforzi di taglio e gli spostamenti relativi che in caso di buona collaborazione legno-acciaio sono molto ridotti. Il presente studio si occupa di indagare la durabilit\ue0 delle caratteristiche di aderenza legno-resina-acciaio del sistema, attraverso una sperimentazione condotta su campioni secondo le procedure della normativa ISO 15686. Dopo una prima fase di studio del sistema agenti-azioni-effetti \ue8 stato messo a punto un ciclo di invecchiamento accelerato e sono state effettuate le indagini in laboratorio in camera climatica. Il comportamento della connessione dopo vari livelli di invecchiamento \ue8 stato analizzato attraverso prove meccaniche di resistenza al taglio, azioni cui il sistema \ue8 sottoposto in esercizio, considerando sia le sollecitazioni climatiche che possono condizionare il comportamento dei singoli componenti del sistema: resina, acciaio e legno lamellare, sia il sistema nel suo insieme per cui risulta critico il comportamento all\u2019interfaccia legno-resina e resina-acciaio. I risultati ottenuti hanno fornito indicazioni interessanti sul comportamento del sistema nel tempo. Infatti con l\u2019avanzare dei cicli di invecchiamento si \ue8 manifestata una progressiva riduzione del carico massimo a rottura, mantenendo caratteristiche di rigidezza elevata, con spostamenti relativi ridottissimi anche sui campioni pi\uf9 invecchiati

Numerical investigation of 48 V electrification potential in terms of fuel economy and vehicle performance for a lambda-1 gasoline passenger car

Real Driving Emissions (RDE) regulations require the adoption of stoichiometric operation across the entire engine map for downsized turbocharged gasoline engines, which have been so far generally exploiting spark timing retard and mixture enrichment for knock mitigation. However, stoichiometric operation has a detrimental effect on engine and vehicle performances if no countermeasures are taken, such as alternative approaches for knock mitigation, as the exploitation of Miller cycle and/or powertrain electrification to improve vehicle acceleration performance. This research activity aims, therefore, to assess the potential of 48 V electrification and of the adoption of Miller cycle for a downsized and stoichiometric turbocharged gasoline engine. An integrated vehicle and powertrain model was developed for a reference passenger car, equipped with a EU5 gasoline turbocharged engine. Afterwards, two different 48 V electrified powertrain concepts, one featuring a Belt Starter Generator (BSG) mild-hybrid architecture, the other featuring, in addition to the BSG, a Miller cycle engine combined with an e-supercharger were developed and investigated. Vehicle performances were evaluated both in terms of elasticity maneuvers and of CO2 emissions for type approval and RDE driving cycles. Numerical simulations highlighted potential improvements up to 16% CO2 reduction on RDE driving cycle of a 48 V electrified vehicle featuring a high efficiency powertrain with respect to a EU5 engine and more than 10% of transient performance improvement

Efficacy and Safety of Using High-Flow Nasal Oxygenation in Patients Undergoing Rapid Sequence Intubation.

Objective: To assess the efficacy and safety of high-flow nasal oxygen (HFNO) therapy in patients undergoing rapid sequence intubation (RSI) for emergency abdominal surgery. Methods: HFNO of 60 L.min\ue2\u88\u921at an inspiratory oxygen fraction of 1 was delivered 4 min before laryngoscopy and maintained until the patient was intubated, and correct intubation was verified by the appearance of the end-tidal CO2(EtCO2) waveform. Transcutaneous oxygenation (SpO2), heart rate and non-invasive mean arterial pressure were monitored at baseline (T0), after 4 min on HFNO (T1) and at the time of laryngoscopy (T2) and endotracheal intubation (ETI) (T3). An SpO2of <3% from baseline was recorded at any sampled time. The value of EtCO2at T3 was registered after two mechanical breaths. The apnoea time was defined as the time from the end of propofol injection to ETI. RSI was performed with propofol, fentanyl and rocuronium. Results: Forty-five patients were enrolled. SpO2levels showed a statistically significant increase at T1, T2 and T3 compared with those at T0 (p<0.05); median SpO2% (interquartile range) was 97% (range, 96%-99%) at T0, 99% (range, 99%-100%) at T1, 99% (range, 99%-100%) at T2 and 99% (range, 99%-100%) at T3. Minimal SpO2was 96%; no patient showed an SpO2of <3% from baseline; mean EtCO2at the time of ETI was 36\uc2\ub14 mmHg. Maximum apnoea time was 12 min. Conclusion: HFNO is an effective and safe technique for pre-oxygenation in patients undergoing rapid sequence induction of general anaesthesia for emergency surgery

Spatial correlation between dust and Hα emission in dwarf irregular galaxies

Using a sample of dwarf irregular galaxies selected from the ALFALFA blind H i-survey and observed using the VIMOS IFU, we investigate the relationship between Hα emission and Balmer optical depth (${\tau }_{{\rm{b}}}$). We find a positive correlation between Hα luminosity surface density and Balmer optical depth in 8 of 11 at ≥0.8σ significance (6 of 11 at ≥1.0σ) galaxies. Our spaxels have physical scales ranging from 30 to 80 pc, demonstrating that the correlation between these two variables continues to hold down to spatial scales as low as 30 pc. Using the Spearman's rank correlation coefficient to test for correlation between ${{\rm{\Sigma }}}_{{\rm{H}}\alpha }$ and ${\tau }_{{\rm{b}}}$ in all the galaxies combined, we find $\rho =0.39$, indicating a positive correlation at 4σ significance. Our low stellar-mass galaxy results are in agreement with observations of emission line regions in larger spiral galaxies, indicating that this relationship is independent of the size of the galaxy hosting the emission line region. The positive correlation between Hα luminosity and Balmer optical depth within spaxels is consistent with the hypothesis that young star-forming regions are surrounded by dusty birth-clouds

Tidal Volume Estimation during Helmet Noninvasive Ventilation: an Experimental Feasibility Study

We performed a bench (BS) and human (HS) study to test the hypothesis that estimation of tidal volume (VT) during noninvasive helmet pressure support ventilation (nHPSV) would be possible using a turbine driven ventilator (TDV) coupled with an intentional leak single-limb vented circuit. During the BS a mannequin was connected to a lung simulator (LS) and at different conditions of respiratory mechanics, positive end expiratory pressure (PEEP) levels and leaks (30, 50 and 80 L/min). All differences were within the 95% limits of agreement (LoA) in all conditions in the Bland-Altman plot. The overall bias (difference between VT measured by TDV and LS) was 35 ml (95% LoA 10 to 57 ml), 15 ml (95% LoA -40 to 70 ml), 141 ml (95% LoA 109 to 173 ml) in the normal, restrictive and obstructive conditions. The bias at different leaks flow in normal condition was 29 ml (95% LoA 19 to 38 ml). In the HS four healthy volunteers using nHPSV had a pneumotachograph (P) inserted through a mouthpiece to measure subject's VT.The bias showed a scarce clinical relevance. In conclusions, VT estimation seems to be feasible and accurate in all conditions but the obstructive one. Additional leaks seem not to affect VT reliability