112 research outputs found
Conceptual Design of a Hydrogen-Propelled Aircraft with Distributed Electric Propulsion
No full textThe growing interest in environmental sustainability motivates the search for disruptive technologies and concepts. However, the lack of conceptual design methods capable of capturing the effects of new propulsive technologies is the main obstacle, often due to the absence of industrial data to support research. In this context, the Clean Sky 2 ELICA (ELectric Innovative Commuter Aircraft) project aims to fill this gap, supporting research with industrial expertise and exploiting a 19-seat commuter aircraft as a technological test bed. This paper aims to present the main results obtained in the investigation of the potential of a full-electric propulsion entirely based on fuel cell systems. After an overview of the main propulsion system modeling techniques used to pursue the objective, three different configurations will be compared, each with a different powerplant, aerodynamic characteristics and weights. The comparison will allow to highlight the real benefits of the aero-propulsive interaction, including effects impossible to quantify except with an approach based on flight mission simulation
TECHNOLOGY ROADMAP AND CONCEPTUAL DESIGN OF HYBRID AND ELECTRIC CONFIGURATIONS IN THE COMMUTER CLASS
No full textThe growing sensitivity to the problem of sustainability requires a rethinking of how aviation is typically conceived by modern society. The aim of the research today must be to analyze the feasibility of disruptive solutions, which drastically reduce consumption and make it possible to meet the growing demand in the commercial aviation sector. The current level of technological maturity does not allow direct implementation on large commercial aircraft, which are responsible for most of the emissions from aviation. In this context, the Clean Sky 2 ELICA project aims to trace a technological roadmap towards green aviation, using the Small Air Transport as a test bed. Two different 19-seat commuter aircraft are presented in this work. The first one, with entry into service in 2025, presents a hybrid-electric architecture with batteries. The second configuration, with entry into service in 2035, is entirely propelled with hydrogen fuel cells, allowing the direct emissions of carbon and nitrogen oxides to be totally eliminated. Both configurations benefit from distributed electric propulsio
Powertrain Model Improvement for Hybrid-Electric Regional Aircraft
No full textThis paper deals with the definition of an improved powertrain model for hybrid-electric aircraft. It is well known that powertrain equations are one of the most convenient tools for modelling the propulsion system at aircraft level, when it comes to hybrid architectures characterized by more than a single propulsive source. However, for a reliable implementation of a robust optimization algorithm for the hybridization parameters, the designer should consider some singularity points related to certain non-physical configurations depending on the operating mode. In this work, singularities are firstly identified by analyzing the operating modes, then a solving strategy is reported. Another crucial aspect is the correct design and simulation of battery behavior. In a broader perspective, the high-level objective of the activities related to powertrain model is to assess a possible fuel saving for regional turboprops using e-storage units as secondary power source. In this respect, preliminary results in terms of flight performance referred to a regional aircraft similar to ATR42 are presented and discussed. The authors conclude that a block fuel saving up to 51% for the typical mission is possible with a battery specific energy of 500 Wh/kg and when the benefits of aero-propulsive interaction are fully exploited
Partitioning of bronchopulmonary carcinoids in two different prognostic categories by Ki-67 score
No full textIntroduction: Histological distinction between typical and atypical bronchopulmonary car- cinoids is based on mitotic activity and necrosis. Regardless of these two parameters, outcome after surgery is often unpredictable. In this study the prognostic value of different clinico-pathological factors was retrospectively analyzed in a large series of patients with bronchopulmonary carcinoid. Materials and Methods: The long-term post-surgical out- come of 106 radically treated patients affected by bronchopulmonary carcinoid from two Italian centers was correlated with tumor characteristics assessed by combining conven- tional histology with a panel of immunohistochemical markers of neuroendocrine differen- tiation (chromogranin-A, NSE) and proliferation activity (Ki-67 score). Results: Carcinoids were assessed as typical (TC = 75; 70.8%) and atypical (AC = 31; 29.2%). Mean follow-up was 8.3 years (range: 0-20; median: 8.0). All cases expressed neuroendocrine markers. At univariate analysis, tumor recurrence [14/75 TC (18.7%), 15/31 AC (48.4%)] correlated with carcinoid histotype (P = 0.003), tumor size (P = 0.012), mitotic index (P = 0.044), Ki-67 score (P < 0.0001), and synchronous node metastasis (P = 0.037). Of these, Cox multivari- ate analysis confirmed only Ki-67 score as independent predictor of disease recurrence (P = 0.009). The best cut-off for Ki-67 score (calculated by ROC curves) discriminating recurrent vs non-recurrent disease was 4% (sensitivity 79.3%; specificity 83.8%; area under the curve 0.85). By stratifying patients according to this cut-off, a significantly dif- ferent disease-free survival was found (log-rank test P < 0.0001). Conclusion: Ki-67 score accurately separates bronchopulmonary carcinoids in two well-distinct histo-prognostic categories. Ki-67 score predicts the patients outcome better than mitotic count, histotype, and tumor stage and it is therefore helpful in establishing the appropriate follow-up. © 2011 Grimaldi, Muser, Beltrami, Machin, Morelli, Pizzolitto, Talmassons, Marciello, Colao, Monaco, Monaco and Faggiano
MARKET ANALYSIS, TLARS SELECTION AND PRELIMINARY DESIGN INVESTIGATIONS FOR A REGIONAL HYBRID-ELECTRIC AIRCRAFT
No full textThis paper is framed in the context of the GENESIS Project (Gauging the ENvironmEntal Sustainability of electrIc and hybrid aircraft Systems), which complies with the European Union topic JTI-CS2-2020-CFP11-THT13 (Sustainability of Hybrid-Electric Aircraft System Architectures) as part of the Clean Sky 2 programme for Horizon 2020. The research work is focused on gauging the environmental sustainability of electric aircraft in a life-cycle-based, foresight perspective to support the development of a technology roadmap for transitioning towards sustainable and competitive electric aircraft systems. The analyzed aircraft segment is regional aircraft, to identify, design and assess prospectively the best energy storage and transmission topology. Different alternatives including batteries, fuel cells, hybrid and conventional powertrain technologies are evaluated and compared over different time horizons. In particular, the paper is focused on the description of the workflow implemented to define the Top-Level Aircraft Requirements for a non-conventional regional class hybrid-electric aircraft with 50 passengers, and on the identification of key specifications in terms of on-board energy storage, shaft power level and weight
Broad virus inactivation using inorganic micro/nano-particulate materials
No full textThis publication was also supported by the European
Virus Archive GLOBAL (EVA-GLOBAL) project that has received funding
from the European Union's Horizon 2020 research and innovation program under grant agreement 871029.Rius-Rocabert S, Arranz-Herrero J, Fernández-Valdés A, Marciello M, Moreno S, Llinares-Pinel F, Presa J, Hernandez-Alcoceba R, López-Píriz R, Torrecillas R, García A, Brun A, Filice M, Moya JS, Cabal B, Nistal-Villan
Design of Hybrid-Electric Small Air Transports
No full textThe potential benefits of hybrid-electric or full-electric propulsion have led to the proliferation of many concepts over the past decade. The lack of conceptual design methods capable of grasping the effects of the new propulsive technologies is often due to the absence of industrial data supporting the research. In the present work, two objectives are pursued. On the one hand, the introduction of semi-empirical methods for weight estimation based on the data provided by the industrial partners of the ELICA CS2 project. On the other hand, the establishment of generative engineering as a conceptual design tool for propulsive system architecting and fault tolerance analysis. The applications of the proposed conceptual design methods deal with two different years of entrance in service
Osteoporosis and thyrotropin-suppressive therapy: reduced effectiveness of alendronate.
No full textBACKGROUND:
Many reports of the effect of exogenous thyroxine therapy on bone mineral density (BMD) show a relationship between excess thyroid hormone administration and osteoporosis. The aim of this study was to evaluate the effect of antibone resorptive agents, in particular alendronate (ALN) on BMD in postmenopausal osteoporotic women with thyroid carcinoma who were receiving long-term thyrotropin (TSH)-suppressive therapy with thyroxine.
METHODS:
Seventy-four postmenopausal women with low BMD (T-score or =0.05 and < or =0.1 microU/mL) for about 3-9 years were selected for the study. The patients were divided into three groups according to the length of levothyroxine (LT(4)) treatment prior to the beginning of the study: group A (TSH-suppressive therapy for about 3 years), group B (for about 6 years), and group C (for about 9 years). These patients were compared with 74 matched women not taking LT(4). All patients and controls were treated with bisphosphonates, calcium, and vitamin D for 2 years and evaluated.
RESULTS:
After 24 months of treatment group A showed a 7.8% increase in lumbar BMD; group B, a 4.6% increase; and group C, a 0.86% increase. In the control group BMD increased 8.2%. A significant difference was found in both lumbar and femoral BMD increase among the three groups: group C had a lower BMD increase than group A (p < 0.001) and B (p < 0.001).
CONCLUSIONS:
In postmenopausal women who were receiving adequate amounts of calcium and vitamin D in their diet ALN was less effective for those who were also receiving TSH-suppressive doses of LT(4) for either 6 or 9 years. The positive effect of ALN on BMD was less for longer periods of LT(4) treatment. It seems likely that other bisphosphonates would also be less effective in increasing BMD in postmenopausal women receiving TSH-suppressing doses of LT(4)
Early traumatic experiences and eating disorders: A focus on the endogenous stress response system
No full textExposure to trauma during childhood is believed to be a major risk factor for lifelong psychiatric disorders, including eating disorders (EDs). Moreover, both an association between stressful life events and the onset/maintenance of EDs and higher presence of traumatic experiences in people with EDs have been documented. The aim of this review was to summarize the current knowledge concerning mechanisms involved in the connection between early trauma exposure and the risk to develop an ED by focusing on body stress response system. Several researches confirm that childhood trauma impairs the biological response to stress so dysregulations of the activity of the hypothalamic-pituitary adrenal (HPA) axis have been proposed as one of the main mechanisms underlying the early trauma-related risk for EDs across the life span. The data presented in this review support the existence of a “maltreated ecophenotype” in EDs characterized by specific clinic and neurobiological features resulting from early stressful environmental experiences. This concept may have important implications in treatment programming for such a type of patients
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