Performance Assessment of an Integrated Environmental Control System of Civil Hypersonic Vehicles

This paper discloses the architecture and related performance of an environment control system designed to be integrated within a complex multi-functional thermal and energy management system that manages the heat loads and generation of electric power in a hypersonic vehicle by benefitting from the presence of cryogenic liquid hydrogen onboard. A bleed-less architecture implementing an open-loop cycle with a boot-strap sub-freezing air cycle machine is suggested. Hydrogen boil-off reveals to be a viable cold source for the heat exchangers of the system as well as for the convective insulation layer designed around the cabin walls. Including a 2 mm boil-off convective layer into the cabin cross-section proves to be far more effective than a more traditional air convective layer of approximately 60 mm. The application to STRATOFLY MR3, a Mach 8 waverider cruiser using liquid hydrogen as propellant, confirmed that presence of cryogenic tanks provides up to a 70% reduction in heat fluxes entering the cabin generated outside of it but inside the vehicle, by the propulsive system and other onboard systems. The effectiveness of the architecture was confirmed for all Mach numbers (from 0.3 to 8) and all flight altitudes (from sea level to 35 km)

Liquid Metals Heat-Pipe solution for hypersonic air-intake leading edge: Conceptual design, numerical analysis and verification

Embedded propulsion systems will allow future hypersonic aircraft to reach amazing levels of performance. However, their peculiar small-radius air-intake leading edges pose serious challenges from the aerothermodynamic, design, integration, and manufacturing standpoints. This paper discloses the methodology developed in the framework of the H2020 STRATOFLY project and specifically tailored to support the conceptual and preliminary design phases of future high-speed transportation systems. The methodology implements an incremental approach which includes multifidelity design, modelling and simulation techniques. The specific application to the MR3, a Mach 8 waverider configuration with an embedded dorsal mounted propulsive subsystem, is reported. Different alternative solutions have been thoroughly analysed, including five liquid metals as fluids (Mercury, Cesium, Potassium, Sodium and Lithium) and relative wick and case materials (Steel, Titanium, Nickel, Inconel® and Tungsten) and three leading-edges materials (CMC, Tungsten with low emissivity painting and Tungsten with high emissivity painting). The analysis of the heat transfer limits (the capillary, entrainment, viscosity, chocking and boiling limits) carried out for all five fluids and relative compatible materials, together with a more accurate FEM analysis, suggest the adoption of a Nickel- Potassium liquid metal heat pipe completely integrated in a platelet air-intake leading edge made of CMC material. Ultimately, the effectiveness of the adopted solution throughout all mission phases has been verified with a detailed numerical model, built upon an electrical analogy

Thermal Protection System preliminary design of STRATOFLY high-speed propelled vehicle

This paper discloses the methodology and the preliminary results achieved in the framework of the H2020 STRATOFLY Project on the design of the Thermal Protection System of the MR3 vehicle. The results of the aero-thermal assessment performed throughout the trajectory clearly indicate the air-intake leading edges as the most critical area, thus dedicated Thermal Protection System alternatives have been explored. Specifically, solutions coupling high-temperature materials (mainly CMC and tungsten with different emissivity paints) with Liquid Metals Heat Pipe arrangements are modelled. Eventually, the effectiveness of the designed solutions is verified with detailed numerical simulation. The design which includes the air-intake main structure made of CMC material and integrating Nickel - Potassium heat pipe results to be the most promising solution to withstand the high thermal loads experienced by STRATOFLY MR3 throughout its Mach 8 long-haul route

Aero-thermal design of STRATOFLY MR3 hypersonic vehicle

Civil hypersonic flights are one of the key technological challenges of next generation. The EC-funded STRATOFLY (Stratospheric Flying Opportunities for High-Speed Propulsion Concepts) project has the objective of assessing the potential of this type of high-speed transport vehicle to reach TRL6 by 2035, with respect to key technological, societal and economical aspects, namely thermal and structural integrity, low-emissions combined propulsion cycles, subsystems design and integration including smart energy management, environmental aspects impacting climate change, noise emissions and social acceptance, and economic viability accounting for safety and human factors. This paper presents the aerothermal design of the new STRATOFLY MR3 hypersonic vehicle

Cooling system of STRATOFLY hypersonic vehicle: conceptual design, numerical analysis and verification

This paper describes the thermal design processes of STRATOFLY hypersonic vehicle cooling system showing either the methodology and the supporting FEM numerical simulations. It focuses on two different regions that are both subjected to severe overheating: air-intake leading edges and the combustion chamber. Final remarks on structure survivability are presented

A stable CC-chemokine receptor (CCR)-5 tropic virus is correlated with the persistence of HIV RNA at less than 2.5 copies in successfully treated naïve subjects

BACKGROUND: To determine if tropism for CXCR4 or CCR5 correlates with cellular HIV DNA load, residual viraemia and CD4 count in 219 successfully treated naive subjects with HIV infection enrolled in five infectious diseases units in Northeastern Italy. METHODS: A subset of subjects, achieving plasma HIV RNA level <50 copies/ml after initiation of first-line therapy and maintaining it until follow-up time points, was retrospectively selected from a prospective cohort. Blood samples were collected before the beginning of therapy (T0), at the first follow-up time (T1) and, when available, at a second (T2) follow-up time. RESULTS: HIV DNA, CD4 count and plasma viraemia were available from all 219 patients at T0 and T1, and in 86 subjects at T2, while tropism determinations were available from 109 subjects at T0, 219 at T1, and from 86 subjects at T2. Achieving residual viraemia <2.5 copies/ml at T1 correlated with having the same condition at T2 (p = 0.0007). X4 tropism at T1 was negatively correlated with the possibility of achieving viraemia<2.5 copies/ml at T2 (p = 0.0076). T1-T2 tropism stability was significant (p <0.0001). T0 tropism correlated with T1 and T2 tropism (p < 0.001); therefore the stability of the tropism over the two follow-up periods was significant (p = 0.0003). An effective viremic suppression (viraemia<2.5 copies/ml) correlated with R5 coreceptor affinity (p= 0.047). CONCLUSIONS: The tropism of archived virus was stable during an effective treatment, with 15-18% of subjects switching over time, despite a viraemia<50 copies/ml. R5 tropism and its stability were related to achieving and maintaining viraemia<2.5 copies/ml

Role of pretreatment variables on plasma HIV RNA value at the sixth month of antiretroviral therapy including all first line drugs in HIV na\uefve patients: A path analysis approach

We investigated the conditioning roles of viral tropism and other variables on plasma HIV RNA levels after 6 months of combination antiretroviral therapy (cART) in an HIV-infected Italian naïve population using regression tree, random forest regression, and path analysis (PA). Patients in this multicenter observational study were treated with all antiviral drugs that are currently recommended as first-line therapies

Epidemiology and Microbiology of Skin and Soft Tissue Infections: Preliminary Results of a National Registry

Skin and soft tissue infections (SSTIs) represent a wide range of clinical conditions characterized by a considerable variety of clinical presentations and severity. Their aetiology can also vary, with numerous possible causative pathogens. While other authors previously published analyses on several types of SSTI and on restricted types of patients, we conducted a large nationwide surveillance programme on behalf of the Italian Society of Infectious and Tropical Diseases to assess the clinical and microbiological characteristics of the whole SSTI spectrum, from mild to severe life-threatening infections, in both inpatients and outpatients. Twenty-five Infectious Diseases (ID) Centres throughout Italy collected prospectively data concerning both the clinical and microbiological diagnosis of patients affected by SSTIs via an electronic case report form. All the cases included in our database, independently from their severity, have been managed by ID specialists joining the study while SSTIs from other wards/clinics have been excluded from this analysis. Here, we report the preliminary results of our study, referring to a 12-month period (October 2016–September 2017). During this period, the study population included 254 adult patients and a total of 291 SSTI diagnoses were posed, with 36 patients presenting more than one SSTIs. The type of infection diagnosed, the aetiological micro-organisms involved and some notes on their antimicrobial susceptibilities were collected and are reported herein. The enrichment of our registry is ongoing, but these preliminary results suggest that further analysis could soon provide useful information to better understand the national epidemiologic data and the current clinical management of SSTIs in Italy

Measurement of the dependence of transverse energy production at large pseudorapidity on the hard-scattering kinematics of proton-proton collisions at √s=2.76 TeV with ATLAS

The relationship between jet production in the central region and the underlying-event activity in a pseudorapidity-separated region is studied in 4.0 pb-1 of s=2.76 TeV pp collision data recorded with the ATLAS detector at the LHC. The underlying event is characterised through measurements of the average value of the sum of the transverse energy at large pseudorapidity downstream of one of the protons, which are reported here as a function of hard-scattering kinematic variables. The hard scattering is characterised by the average transverse momentum and pseudorapidity of the two highest transverse momentum jets in the event. The dijet kinematics are used to estimate, on an event-by-event basis, the scaled longitudinal momenta of the hard-scattered partons in the target and projectile beam-protons moving toward and away from the region measuring transverse energy, respectively. Transverse energy production at large pseudorapidity is observed to decrease with a linear dependence on the longitudinal momentum fraction in the target proton and to depend only weakly on that in the projectile proton. The results are compared to the predictions of various Monte Carlo event generators, which qualitatively reproduce the trends observed in data but generally underpredict the overall level of transverse energy at forward pseudorapidity

Measurements of the charge asymmetry in top-quark pair production in the dilepton final state at s √ =8 TeV with the ATLAS detector

Measurements of the top-antitop quark pair production charge asymmetry in the dilepton channel, characterized by two high-pT leptons (electrons or muons), are presented using data corresponding to an integrated luminosity of 20.3  fb−1 from pp collisions at a center-of-mass energy s√=8  TeV collected with the ATLAS detector at the Large Hadron Collider at CERN. Inclusive and differential measurements as a function of the invariant mass, transverse momentum, and longitudinal boost of the tt¯ system are performed both in the full phase space and in a fiducial phase space closely matching the detector acceptance. Two observables are studied: AℓℓC based on the selected leptons and Att¯C based on the reconstructed tt¯ final state. The inclusive asymmetries are measured in the full phase space to be AℓℓC=0.008±0.006 and Att¯C=0.021±0.016, which are in agreement with the Standard Model predictions of AℓℓC=0.0064±0.0003 and Att¯C=0.0111±0.0004