Variational approach to the problem of optimal propeller design

The aim of this paper is to evaluate the theoretical efficiency of propellers with non-planar blade, optimally shaped. It is well known that non-planar wing configurations can significantly re- duce the induced drag [5], hence this can be of interest also for propeller design. Furthermore the adoption of a curvilinear blade system can be justi- fied not only for an efficiency improvement, but also for reason that concerns the structure and the noise reduction [12], [1]. A solution to the optimum rotor problem, in the context of propeller vortex theory, was given by Goldstein [7]. He considered straight blade pro- pellers and expressed the optimum circulation function via a trigonometrical series of Bessel functions. However, such were the difficulties of computa- tion, even after the solution was found, that Theodorsen resorted to the use of rheoelectrical analogy to evaluate the circulation function, unfortunately without great success [14]. Accurate tabulated values of the Goldstein func- tion covering a wide range of parameters became available with an extensive mathematical effort by Tibery and Wrench [15]. Although this work is based on a completely different approach, Goldstein results are fundamental to validate the procedure for the case of straight blade. In this dissertation, a variational formulation1 of the optimum rotor prob- lem is proposed in order to support the optimization of more complex blade configurations, such as the non-planar ones. The first step of the formulation consists into finding a class of functions (representing the circulation distri- bution along the blade) for which the thrust and the aerodynamic resisting moment functionals are well defined. Then, in this class, the functional to be minimized is proved to be strictly convex; taking into account this result, it is proved that the global minimum exists and is unique. Some of the configurations analysed are: - Classical straight blade - Parabolic blade - Elliptical blade - Superelliptic blade Configurations with the same value of maximum dimensions and perfor- mances required are compared in the case of single and multiple blade pro- pellers. This formulation can be seen as the extension of the one proposed in [11]. The main difficulty in the functionals’ evaluation, is the fact that an an- alytical expression of the velocity induced by a semi-infinite helical vortex filament do not exist2. For this reason the Euler-Lagrange equation asso- ciated with the variational problem is not obtained and a direct method is used. In particular the Ritz Method is adopted. Another task to deal with, is the evaluation of the singular integral rep- resenting the induced velocity. A two-dimensional quadrature rule, based on Legendre polynomials, is used [9]. This procedure is implemented in a MATLAB program that, given the parametric expression of the curve representing the blade, allows the eval- uation of the momentum in the required condition and plots the optimal circulation along the curve

Arbuscular mycorrhizal fungi as a tool to ameliorate the phytoremediation potential of poplar: biochemical and molecular aspects

Poplar is a suitable species for phytoremediation, able to tolerate high concentrations of heavy metals (HMs). Arbuscular mycorrhizal fungi (AMF) form symbiotic associations with the roots of most land plants; they improve nutrient uptake and enhance phytoextraction of HMs while alleviating stress in the host plant. This review summarizes previous results from field and greenhouse studies conducted by us and dealing with this topic. In a field trial on a highly Zn- and Cu-contaminated site, differences in plant survival and growth were observed among 168 clones originating from natural populations of Populus alba L. and Populus nigra L. from northern Italy. After two and a half years from planting, the density, activity and metabolic versatility of the culturable fraction of the soil bacteria in the HM-polluted field was higher in the soil close to where larger poplar plants were growing, in spite of comparable HM concentrations recorded in these soils. One well-performing clone of P. alba (AL35), which accumulated a higher concentration of both metals and had high foliar polyamine (PA) levels, was used for further investigation. In a greenhouse study, AL35 cuttings pre-inoculated with AMF (Glomus mosseae or Glomus intraradices) and then transferred to pots containing soil, collected from the HM-polluted site, displayed growth comparable to that of controls grown on unpolluted soil, in spite of higher Cu and Zn accumulation. Such plants also showed an overall up-regulation of metallothionein (MT) and PA biosynthetic genes, together with increased PA levels. A genome-wide transcriptomic (cDNA-AFLP) analysis allowed the identification of a number of genes, mostly belonging to stress-related functional categories of defense and secondary metabolism, that were differentially regulated in mycorrhizal vs. non mycorrhizal plants. A proteomic analysis revealed that, depending on sampling time, changes in protein profiles were differentially affected by AMF and/or HMs. It is concluded that soil-borne microorganisms affect plant performance on HM-polluted soil. In particular, mycorrhizal plants exhibited increased capacity for phytostabilization of HMs, together with improved growth. Their greater stress tolerance may derive from the protective role of PAs, and from the strong modulation in the expression profiles of stress-related genes and proteins

La donazione di organi. Una domanda di salute tra efficienza di sistema e solidariet\ue0 individuale e collettiva

Questo articolo presenta una ricerca sulla donazione e trapianto di organo proveniente da paziente in morte encefalica, evidenziando le differenze tra contesti regionali e alcune realt\ue0 specifiche del territorio regionale ligure e formula alcune ipotesi esplicative delle differenze rilevate. Lo studio analizza il funzionamento del sistema su indicatori di processo e di risultato per tentare di comprendere e modellizzare il ruolo giocato dai contesti nello spiegare le differenze. Sono stati analizzati i dati provenienti dal sistema informativo per quantificare gli indicatori e interviste con testimoni qualificati per interpretare l\u2019evidenza emersa dai dati

Neoadjuvant and adjuvant doxorubicin chemotherapy in a case of feline soft tissue sarcoma

A 7-year old male neutered domestic shorthair cat was presented with a 2 month history of a slow-growing mass on the right zygomatic area. A CT scan revealed a soft tissue mass in the right zygomatic region with no alterations of the underlying bone and features of local invasiveness. Cytology was suggestive of a mesenchymal tumour and histopathology from an incisional biopsy was consistent with a soft tissue sarcoma (STS). The cat was treated with neoadjuvant intravenous doxorubicin chemotherapy at a dose of 25 mg/m2, every two weeks. The patient experienced a partial response and underwent surgical excision of the tumour. Doxorubicin was continued as an adjuvant treatment for three further chemotherapy sessions, at a dose of 25 mg/m2 every 21 days. Local tumour recurrence was detected on clinical examination and cytologically confirmed 259 days following surgery

\u201cNon \ue8 diverso da te\u201d. Una proposta di sensibilizzazione degli adolescenti al tema della salute mentale

L'articolo presenta un'esperienza di formazione e sensibilizzazione di studenti delle scuole superiori al tema della salute mentale e alcuni dei risultati della ricerca condotta in parallelo con i giovani per conoscere le loro opinioni sul tema prima e dopo la partecipazione a tale attivit\ue0

Aeroelastic Design of the oLAF Reference Aircraft Configuration

One of the main aims of the EU Flightpath 2050 is to significantly reducet he fuel consumption of upcoming designs for transport aircraft. To achieve this challenging goal, new technologies have to be investigated. In this context, the development of the 'optimally load adaptive aircraft' (oLAF) for a conventional design is one of the main goals of the DLR project oLAF. Since the lift-to-drag ration, the structural mass and the thrust specific fuel consumption are the main drivers of the aircraft's fuel consumption, an improvement in all three topics seems to be a promising approach to fulfill the intended aims of the European Union. That's why the design of the new oLAF configuration is equipped with a next generation three shaft geared turbofan engine with an ultra-high bypass-ration and an optimized aerodynamic performance combined with aggressive loadalleviation (LA) techniques to lighten the load-carrying structure of the aircraft significantly compared to a conventional state-of-the-art aircraft. Multiple design cycles with different degree of fidelity and LA approaches are planned to be performed within oLAF. At the current state of the project, three different designs are available. On the one hand, there is the more basic configuration of the overall aircraft design (OAD) further called 'oLAF_SLv1'. On the other hand, there are configurations with more mature aerodynamic characteristics further called the oLAF_ASv0 configuration as start design for a multidisciplinary-design-optimization (MDO) process and the 'oLAF_ASv1' as the optimized result of the MDO. All configurations have been analyzed and evaluated using the aeroelastic structural design tool cpacs-MONA. The optimized 'oLAF_ASv1' configuration has furthermore been checked on aeroelastic stability. Conclusively, the stiffness of the structural pylon model has been adapted to shift a hump-mode of the new generation engine to higher airspeeds, so that the instability occurs outside of the flight envelope

Design of the strut braced wing aircraft in the agile collaborative MDO framework

The paper describes the deployment of the AGILE Development Framework to investigate the Strut Braced Wing aircraft configuration. The design process consists of a multilevel multidisciplinary architecture, progressing from the initial conceptual synthesis to the physics based analysis. All the main disciplinary domains, including on board system design and cost assessment, are accounted for in the assembled workflow. Due to the specific characteristics of the Strut Braced Wing configuration, the aeroelastic analysis is the main focus of the study and it is addressed at both high and low fidelity levels. The integration of the engine-wing system is also included in the design process. All the design competences, which are hosted at the different partners, communicate via CPACS (Common Parametric Aircraft Configuration Schema) data schema. All the results generated, including the multidisciplinary design process itself, will be published and made available as part of the AGILE Overall Aircraft Design database

Frailty trajectories in community-dwelling older adults during COVID-19 pandemic: The PRESTIGE study

Background Frailty has been recognized as potential surrogate of biological age and relevant risk factor for COVID-19 severity. Thus, it is important to explore the frailty trajectories during COVID-19 pandemic and understand how COVID-19 directly and indirectly impacts on frailty condition. Methods We enrolled 217 community-dwelling older adults with available information on frailty condition as assessed by multidimensional frailty model both at baseline and at one-year follow-up using Multidimensional Prognostic Index (MPI) tools. Pre-frail/frail subjects were identified at baseline as those with MPI score >0.33 (MPI grades 2-3). Frailty worsening was defined by MPI difference between 12 months follow-up and baseline >= 0.1. Multivariable logistic regression was modelled to identify predictors of worsening of frailty condition. Results Frailer subjects at baseline (MPI grades 2-3 = 48.4%) were older, more frequently female and had higher rates of hospitalization and Sars-CoV-2 infection compared to robust ones (MPI grade 1). Having MPI grades 2-3 at baseline was associated with higher risk of further worsening of frailty condition (adjusted odd ratio (aOR): 13.60, 95% confidence interval (CI): 4.01-46.09), independently by age, gender and Sars-CoV-2 infection. Specifically, frail subjects without COVID-19 (aOR: 14.84, 95% CI: 4.26-51.74) as well as those with COVID-19 (aOR: 12.77, 95% CI: 2.66-61.40, p = 0.001) had significantly higher risk of worsening of frailty condition. Conclusions Effects of COVID-19 pandemic among community-dwelling frailer individuals are far beyond the mere infection and disease, determining a significant deterioration of frailty status both in infected and non-infected subjects

MBSE Certification-Driven Design of a UAV MALE Configuration in the AGILE 4.0 Design Environment

This paper presents a certification-driven design process for an Unmanned Medium-Altitude- Long-Endurance (UAV MALE) air vehicle, including on-board system design and placements, electro-magnetic compatibility analysis, and thermal risk assessments. In literature, the preliminary aircraft design phase is mainly driven by mission performances and structural integrity aspects. However, the inclusion of other disciplines, like on-board system design or electro-magnetic compatibility, or thermal analysis, can lead to more efficient and cost- effective solutions and becomes paramount for non-conventional configurations like unmanned vehicles or highly electrified platforms. In the EC-funded AGILE 4.0 project (2019-2022), the traditional scope of the preliminary aircraft design is extended by including domains that are usually considered only in later design phases, such as certification, production and maintenance. In this paper, the AGILE 4.0 design environment supports the definition and execution of a certification-driven design process of a UAV MALE configuration, using a Model-Based Systems Engineering (MBSE) approach