Aerodynamic and Acoustic Design Optimization of a Multiple Propeller Combination for Distributed Electrical Propulsion

This manuscript illustrates an optimization procedure carried out on a large-scale wind tunnel model conceived to investigate the aerodynamic and acoustic performance of a Distributed Electric Propulsion (DEP) system installed on the wings of a regional aircraft in high lift conditions. The aim of the optimization process is to obtain the best possible improvements in terms of noise and aerodynamic performance by modifying the propellers' layout of the Wing + DEP wind tunnel model. A multi-objective, multi-point design approach is adopted based on evolutionary computing. The research work is carried out in the framework of the VENUS EU-funded project GA-886019

Acoustic Impact of Hybrid-Electric DEP Aircraft Configuration at Airport Level

The Italian research project PROSIB (PROpulsione e Sistemi IBridi per velivoli ad ala fissa e rotante), is a 30-month initiative funded by the Italian Ministry of University and Scientific Research (MIUR) and coordinated by the Leonardo company. The project is aimed to investigate configurations for regional aircraft and rotary wing platforms and architectures for propulsion systems, and is dedicated to the identification of the best strategy for their use, given different on-board energy sources. The reduced environmental impact is the key for the success of the new hybrid/electric aircraft configurations. This not only considers the chemical pollution introduced in the atmosphere, but also the noise produced on the surrounding area of airports. The present paper describes the acoustic impact assessment resulting from the inclusion of new propulsion technologies and new configurations of regional aircraft (ATR42 pax) in a reference airport area

A Novel Optimization Framework to Replicate the Vibro-Acoustics Response of an Aircraft Fuselage

In this work, a novel optimization framework, based on a Multi-Disciplinary Optimization (MDO) procedure, applied to the vibro-acoustic Finite Element Method (FEM) model of an aircraft fuselage mock-up, is proposed. The MDO procedure, based on an Efficient Global Optimization (EGO)-like approach, is implemented to characterize acoustic sources that replicate the sound pressure field generated by the engines on the fuselage. A realistic sound pressure field, evaluated by aeroacoustic simulations, was considered as the reference acoustic load, whereas two equivalent sound fields, displayed by two different arrays of microphones and generated by the same configuration of monopoles, were calculated by the proposed vibro-acoustic FEM-MDO procedure. The proposed FEM-MDO framework enables to set up ground experimental tests on aircraft components, useful to replicate their vibro-acoustic performances as if tested in flight. More in general, such a procedure can also be used as a reference tool to design simplified tests starting from more complex ones

characterization of equivalent acoustic sources to reproduce the acoustic field generated by engines on an aircraft fuselage

Abstract This work presents a general procedure to characterize equivalent acoustic sources to reproduce the sound pressure field generated by the engines on an aircraft fuselage. The procedure would allow to set up ground experimental tests on aircraft components, by means of distributed loudspeakers, to obtain their vibro-acoustic performances as if they were tested in flight conditions. A FEM model of an aircraft fuselage mock-up was built up, comprising the structure, the internal acoustic cavities and the external air. The sound pressure field generated by the engines was considered as the reference solution, whereas an equivalent sound field, produced by distributed monopole sources surrounding the structure, was obtained by leveraging on the proposed Multi-Disciplinary Optimization (MDO) procedure. The MDO procedure was based on the mutual interaction between the commercial codes Siemens NX, for the CAE/FEM simulations, and Noesis Optimus, for the optimization framework

The Impact of Company Grade Officer Self-Sacrificial Behavior on Subordinate Assessments of Leader Charisma

Newly commissioned officers in the U.S. Army are taught to lead their soldiers from the front and to voluntarily make personal sacrifices in the service of the nation. Although this facet of military culture is seen as critical to the integrity of the force, there are few research studies describing the impact of leader self-sacrifice in the U.S. Army. Research evolving from the transformational leadership literature indicates that civilian leaders who engage in self-sacrificial behavior are viewed as more charismatic than their counterparts and that this perception is particularly pronounced in crisis situations. The current study extended this research to a military population utilizing a quantitative experimental research design. Respondents were randomly assigned to written vignettes that manipulated leader self-sacrifice and the combat environment and then provided assessments of the company grade officer\u27s attributed charisma. Currently serving enlisted and commissioned officers in the California Army National Guard (n = 218) took part in the research, and ANOVA test results indicated that both self-sacrifice and the experience of combat significantly increase perceptions of a company grade officer\u27s attributed charisma. No significant interaction was found between leader self-sacrifice and combat. This study indicated that the self-sacrificial leadership model may have broad applicability across organizations and provides strong support for the Army\u27s emphasis on selfless service. This research can spur positive social change by fostering a more aspirational form of leadership within the Army that builds the psychological resilience of soldiers and results in stronger teams

Experimental investigation of UAV rotor aeroacoustics and aerodynamics with computational cross‑validation

The study provided a base of comparison of known computational techniques with different fidelity levels for performance and noise prediction of a single, fixed-pitch UAV rotor operating with varying flight parameters. The range of aerodynamic tools included blade element theory, potential flow methods (UPM, RAMSYS), lifting-line method (PUMA) and Navier–Stokes solver (FLOWer). Obtained loading distributions served as input for aeroacoustic codes delivering noise estimation for the blade passing frequency on a plane below the rotor. The resulting forces and noise levels showed satisfactory agreement with experimental data; however, differences in accuracy could be noticed depending on the computational method applied. The wake influence on the results was estimated based on vortex trajectories from simulations and those visible in background-oriented schlieren (BOS) pictures. The analysis of scattering effects showed that influence of ground and rotor platform on aeroacoustic results was observable even for low frequencies

AIRO Breast Cancer Group Best Clinical Practice 2022 Update

Introduction: Breast cancer is the most common tumor in women and represents the leading cause of cancer death. Radiation therapy plays a key-role in the treatment of all breast cancer stages. Therefore, the adoption of evidence-based treatments is warranted, to ensure equity of access and standardization of care in clinical practice.Method: This national document on the highest evidence-based available data was developed and endorsed by the Italian Association of Radiation and Clinical Oncology (AIRO) Breast Cancer Group.We analyzed literature data regarding breast radiation therapy, using the SIGN (Scottish Intercollegiate Guidelines Network) methodology (www.sign.ac.uk). Updated findings from the literature were examined, including the highest levels of evidence (meta-analyses, randomized trials, and international guidelines) with a significant impact on clinical practice. The document deals with the role of radiation therapy in the treatment of primary breast cancer, local relapse, and metastatic disease, with focus on diagnosis, staging, local and systemic therapies, and follow up. Information is given on indications, techniques, total doses, and fractionations.Results: An extensive literature review from 2013 to 2021 was performed. The work was organized according to a general index of different topics and most chapters included individual questions and, when possible, synoptic and summary tables. Indications for radiation therapy in breast cancer were examined and integrated with other oncological treatments. A total of 50 questions were analyzed and answered.Four large areas of interest were investigated: (1) general strategy (multidisciplinary approach, contraindications, preliminary assessments, staging and management of patients with electronic devices); (2) systemic therapy (primary, adjuvant, in metastatic setting); (3) clinical aspects (invasive, non-invasive and micro-invasive carcinoma; particular situations such as young and elderly patients, breast cancer in males and cancer during pregnancy; follow up with possible acute and late toxicities; loco-regional relapse and metastatic disease); (4) technical aspects (radiation after conservative surgery or mastectomy, indications for boost, lymph node radiotherapy and partial breast irradiation).Appendixes about tumor bed boost and breast and lymph nodes contouring were implemented, including a dedicated web application. The scientific work was reviewed and validated by an expert group of breast cancer key-opinion leaders.Conclusions: Optimal breast cancer management requires a multidisciplinary approach sharing therapeutic strategies with the other involved specialists and the patient, within a coordinated and dedicated clinical path. In recent years, the high-level quality radiation therapy has shown a significant impact on local control and survival of breast cancer patients. Therefore, it is necessary to offer and guarantee accurate treatments according to the best standards of evidence-based medicine

The Zwicky Transient Facility: System Overview, Performance, and First Results

The Zwicky Transient Facility (ZTF) is a new optical time-domain survey that uses the Palomar 48 inch Schmidt telescope. A custom-built wide-field camera provides a 47 deg^2 field of view and 8 s readout time, yielding more than an order of magnitude improvement in survey speed relative to its predecessor survey, the Palomar Transient Factory. We describe the design and implementation of the camera and observing system. The ZTF data system at the Infrared Processing and Analysis Center provides near-real-time reduction to identify moving and varying objects. We outline the analysis pipelines, data products, and associated archive. Finally, we present on-sky performance analysis and first scientific results from commissioning and the early survey. ZTF's public alert stream will serve as a useful precursor for that of the Large Synoptic Survey Telescope

Aeroacoustic methods for low-noise technologies design

As environmental concerns are gaining increased public attention and with the rapid growth of air traffic foreseen in the forthcoming years, the scientific community and aircraft manufacturers are devoting significant resources in developing fast and reliable methods to deliver low noise design solutions. Since fully-resolved Navier–Stokes equations (DNS), and even filtered Navier-Stokes equations such as LES and DES methods, are still too computationally demanding for real applications, the present dissertation is focused on the theoretical and numerical formulation of different alternative computational aeroacoustic methods and their application to typical aeronautics low noise design problems. Following an introduction about the theoretical formulation of the Acoustic Analogy approach based on the Lighthill’s equation, the thesis is focused on the development of a Boundary Element Method (BEM) based on the convective wave equation for uniform mean flow. The BEM code kernel, developed for managing hybrid unstructured grids, builds up the global system matrix by assembling different matrix blocks for the governing equations and the boundary conditions. This strategy allows a more general and efficient implementation of the boundary conditions. The BEM code is also validated against classical analytical test cases for both internal and external problems. Moreover, the broadband noise generated by aircraft surfaces (Airframe noise) is presented with particular attention devoted to the development of RANS-based models for source field characterization. Finally the application of the developed methods to the analysis of the Landing Gear low-noise design problem is presented

Aeroacoustics Assessment of an Hybrid Aircraft Configuration with Rear-Mounted Boundary Layer Ingested Engine

Hybrid electric propulsion is a promising solution to reduce aircraft emissions, thus improving the sustainability of the air transport. In this work, a hybrid aircraft configuration with a rear-mounted boundary layer ingestion (BLI) engine has been investigated. The partial embedding of the engine into the fuselage generates a distortion of the ingested inflow causing additional tonal and broadband BLI noise sources, and, at the same time, alters the existing one, such as the rotor–stator interaction noise (RSI). This work is focused on the tonal RSI noise modeling, with and without the distortion generated by the BLI, and the far-field propagation including the acoustic masking contribution due to the engine–fuselage integration. As the main result, this work shows the contributions of BLI and the engine–aircraft integration on the RSI noise. Both effects should be properly taken into account in the early aircraft design stage for an effective noise reduction even at ground level