High Fidelity Model of Ball Screws to Support Model-based Health Monitoring

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Towards a PHM system for Electro-Mechanical Flight Control Actuators

This paper describes the roadmap of an on-going research effort aimed at the design of a novel Prognostics and Health Management system for electro-mechanical actuators employed as secondary flight control systems

Development of a High-Performance Low-Weight Hydraulic Damper for Active Vibration Control of the Main Rotor on Helicopters—Part 1: Design and Mathematical Model

The helicopter vibrations generated by the main rotor/gearbox assembly are the principal cause of damage to cockpit instruments and discomfort of the crew in terms of cabin noise. The principal path of vibration transmission to the fuselage is through the gearbox rigid support struts. With the aim of reducing these vibrations, this paper presents the design of a low-weight high-performance active damper for vibration control developed by Elettronica Aster S.p.A. The system is intended to replace the conventional struts and is composed of an electro-hydraulic actuator hosted within a compliant structure. This parallel nested structure allows the system to reach a high-power density. A physics-based mathematical model was used as a design digital twin to optimize the performance to meet the strict requirements. The active damper was designed for a reference application of a 15-seat medium-sized twin-engine helicopter. The model was used to perform the tests specified in the acceptance and testing procedure document, showing the compliance with the requirements of the current design. The damper physical realization, test bench design, experimental campaign, and model validation will be presented in Part 2

Development of a High-Performance Low-Weight Hydraulic Damper for Active Vibration Control of the Main Rotor on Helicopters—Part 2: Preliminary Experimental Validation

Vibrations generated by the main rotor-gearbox assembly in a helicopter are the principal cause of damage to cockpit instruments and crew discomfort in terms of cabin noise. The principal path of vibration transmission to the fuselage is through the gearbox’s rigid support struts. This article is Part 2 of a two-part paper presenting an innovative solution involving the replacement of rigid struts with low-weight, high-performance active dampers for vibration control developed by Elettronica Aster S.p.A. Part 1 provided a comprehensive overview of the system layout obtained through a model-based design process and presented a thorough description of the adopted nonlinear mathematical model. Part 2 focuses on the physical realization of the damper and its dedicated experimental test bench. The mathematical model parameter fitting procedure is presented in detail, as it has been used to help in the definition and optimization of the control schemes and the verification of the expected performance. The experimental results obtained in Part 2 not only demonstrate the compliance of the active damper prototype with the acceptance tests outlined in the ATP but also provide compelling evidence reinforcing the promise of the presented solution for effective vibration reduction

Corrigendum: Tomographic characterization of copper cellular bodies fabricated by a powder metallurgy route (2019 Mater. Res. Express 6 056531)

The actual sentence in the last paragraph of section 3.2 Cell structure characterization: The average thickness is compute as t = (2VsizeV1)/V2, where Vsize is the tomography voxel size (26.36 µmin our sample), V1 is the sum of the voxel intensities in the material distance map image and V2 is the number of voxels in the separation surfaces distance map image. Should be replaced by the following sentence: The average thickness is calculated as t = (2VsizeV1)/V2, where Vsize is the tomography voxel size (26.36 µm in our sample), V1 is the sum of the voxel intensities in the separation surfaces distance map image and V2 is the number of voxels in the binary image of the filtered and separated cells.Fil: Malachevsky, Maria Teresa. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Patagonia Norte; Argentina. Comisión Nacional de Energía Atómica. Centro Atómico Bariloche; ArgentinaFil: Bertolino, Graciela Mabel. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Patagonia Norte; Argentina. Comisión Nacional de Energía Atómica. Centro Atómico Bariloche; ArgentinaFil: Oliber, Edgardo Antonio. Comisión Nacional de Energía Atómica. Centro Atómico Bariloche; ArgentinaFil: D'ovido, Claudio. Comisión Nacional de Energía Atómica. Centro Atómico Bariloche; ArgentinaFil: Baruj, Alberto Leonardo. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Patagonia Norte; Argentina. Comisión Nacional de Energía Atómica. Centro Atómico Bariloche; ArgentinaFil: Cuscueta, Diego Javier. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Patagonia Norte; Argentina. Comisión Nacional de Energía Atómica. Centro Atómico Bariloche; Argentin

Intelligent Diagnostics for Aircraft Hydraulic Equipment

In aviation industry, unscheduled maintenance costs may vary in a large range depending on several factors, such as specific aircraft system, operational environment, aircraft usage and maintenance policy. These costs will become more noteworthy in the next decade, due to the positive growing of worldwide fleet and the introduction of more technologically advanced aircraft. New implemented technologies will bring new challenges in the Maintenance, Repair and Overhaul (MRO) companies, both because of the rising number of new technologies and high volume of well-established devices, such as Electro-Hydraulic Servo Actuators for primary flight control. Failures in aircraft hydraulic systems deeply influence the overall failure rate and so the relative maintenance costs. For this reason, overhaul procedures for these components still represents a profitable market share for all MRO stakeholders. Innovative solutions able to facilitate maintenance operations can lead to large cost savings. This paper proposes new methodologies and features of the Intelligent Diagnostic system which is being developed in partnership with Lufthansa Technik (LHT). The implementation of this innovative procedure is built on a set of failure detection algorithms, based on Machine Learning techniques. This development requires first to bring together the results from different parallel research activities: 1. Identification of critical components from historical data; 2. Designing and testing automatic and adaptable procedure for first faults detection; 3. High-fidelity mathematical modeling of considered test units, for deeper physics analysis of possible failures; 4. Implementation of Machine Learning reasoner, able to process experimental and simulated data

Machine learning-based ability to classify psychosis and early stages of disease through parenting and attachment-related variables is associated with social cognition

Background: Recent views posited that negative parenting and attachment insecurity can be considered as general environmental factors of vulnerability for psychosis, specifically for individuals diagnosed with psychosis (PSY). Furthermore, evidence highlighted a tight relationship between attachment style and social cognition abilities, a key PSY behavioral phenotype. The aim of this study is to generate a machine learning algorithm based on the perceived quality of parenting and attachment style-related features to discriminate between PSY and healthy controls (HC) and to investigate its ability to track PSY early stages and risk conditions, as well as its association with social cognition performance. Methods: Perceived maternal and paternal parenting, as well as attachment anxiety and avoidance scores, were trained to separate 71 HC from 34 PSY (20 individuals diagnosed with schizophrenia + 14 diagnosed with bipolar disorder with psychotic manifestations) using support vector classification and repeated nested cross-validation. We then validated this model on independent datasets including individuals at the early stages of disease (ESD, i.e. first episode of psychosis or depression, or at-risk mental state for psychosis) and with familial high risk for PSY (FHR, i.e. having a first-degree relative suffering from psychosis). Then, we performed factorial analyses to test the group x classification rate interaction on emotion perception, social inference and managing of emotions abilities. Results: The perceived parenting and attachment-based machine learning model discriminated PSY from HC with a Balanced Accuracy (BAC) of 72.2%. Slightly lower classification performance was measured in the ESD sample (HC-ESD BAC = 63.5%), while the model could not discriminate between FHR and HC (BAC = 44.2%). We observed a significant group x classification interaction in PSY and HC from the discovery sample on emotion perception and on the ability to manage emotions (both p = 0.02). The interaction on managing of emotion abilities was replicated in the ESD and HC validation sample (p = 0.03). Conclusion: Our results suggest that parenting and attachment-related variables bear significant classification power when applied to both PSY and its early stages and are associated with variability in emotion processing. These variables could therefore be useful in psychosis early recognition programs aimed at softening the psychosis-associated disability

Fabrication of copper foams by powder metallurgy

Se presenta un método de fabricación de esponjas de cobre por pulvimetalurgia, empleando perlas de urea como formadores de poros que son removidas por disolución en agua antes de sinterizar el compacto. Este método permite un control preciso de las características de las celdas (tamaño, forma y distribución), obteniéndose una porosidad de celdas interconectadas. El empleo de metales en polvo lleva a tener una porosidad asociada a las paredes de las mismas que afecta a las propiedades mecánicas, provocando la falla a tensiones menores de lo esperable. Se optimizó el método de fabricación seleccionando los parámetros de sinterizado (presión de compactado, temperatura y atmósfera). Para caracterizar la meso y microestructura de las muestras se emplearon técnicas de microscopía tradicionales (microscopio electrónico de barrido SEM) y tomografía de rayos x. Esta última técnica permite visualizar en 3D la distribución de las celdas, realizar una caracterización completa de la mesoestructura, evaluar la porosidad de las muestras y seguir la evolución de la deformación de las celdas en ensayos de compresión.A method for the fabrication of copper foams by powder metallurgy, employing carbamide beads as space holders, is presented. These are removed by water dissolution before sintering the compact. The method allows for a precise control of the cell characteristics (size, shape and distribution) within an interconnected porosity. The use of metal powder promotes the formation of an inherent porosity in the cell walls that affects their mechanical properties, producing failure at a lower than expected tension. Optimization of the method was achieved by selecting the sintering parameters (compaction pressure, temperature and atmosphere). The mesostructure and microstructure of the samples were characterized by traditional microscopy (scanning electron microscope SEM) and x-ray tomography. The latter technique allows a 3D visualization of the cell distribution, a complete characterization of the mesostructure, the evaluation of the porosity and to follow the cell evolution during compression tests.Fil: Malachevsky, Maria Teresa. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina. Comisión Nacional de Energía Atómica. Centro Atómico Bariloche; ArgentinaFil: Bertolino, Graciela Mabel. Comisión Nacional de Energía Atómica. Centro Atómico Bariloche; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; ArgentinaFil: Arneodo Larochette, Pierre Paul. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina. Comisión Nacional de Energía Atómica. Centro Atómico Bariloche; ArgentinaFil: Baruj, Alberto Leonardo. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina. Comisión Nacional de Energía Atómica. Centro Atómico Bariloche; ArgentinaFil: Oliber, Edgardo Antonio. Comisión Nacional de Energía Atómica. Centro Atómico Bariloche; ArgentinaFil: D'ovido, Claudio. Comisión Nacional de Energía Atómica. Centro Atómico Bariloche; ArgentinaFil: Cuscueta, Diego Javier. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina. Comisión Nacional de Energía Atómica. Centro Atómico Bariloche; Argentin

HBV-Specific Adaptive Immunity

The successful control of HBV infection requires an efficient expansion of distinct elements of the adaptive immune system (B cells, helper and cytotoxic T cells) that, due to the hepatotropic nature of HBV, need to operate in the liver parenchyma. In this respect, we will discuss broad features of HBV immunity in patients with resolved or chronic HBV infection and analyze how the liver environment can directly modulate HBV-immunity

Deep coral oases in the South Tyrrhenian Sea

A Mediterranean ‘‘roche du large’’ ecosystem, represented by four rocky shoals, located a few miles apart on a muddy bottom at 70–130 m depth in the gulf of St. Eufemia (Calabria, South Tyrrhenian Sea), was studied by means of Remotely Operated Vehicle (ROV) photo imaging. The shoals host highly diversified coral communities, mainly composed of arborescent colonies of gorgonians (Callogorgia verticillata, Paramuricea clavata, Paramuricea macrospina, Bebryce mollis, Villogorgia bebrycoides, Corallium rubrum, and Leptogorgia sarmentosa), and antipatharians (Antipathella subpinnata, Antipathes dichotoma and Parantipathes larix). The coral colonies reach high densities (up to ca. 17 colonies m22) and large sizes, such as the over 1.5 m wide antipatharian colonies. We hypothesized that the abundance and composition of the coral assemblages differed significantly among the rocky shoals and with respect to the surrounding soft bottoms. Various environmental variables were tested as possible explanatory factors of the observed differences. Moreover, due to their off- coast localization, we report here that these unique ecosystems are potentially subjected to a strong pressure from the local fishing activities, which were tentatively characterized. The recorded coral b-diversity among the shoals supports the hypothesis that these habitats behave like small oases of hard substrata interspersed in a muddy bottom. Because of their intrinsic beauty and rarity and their biological and ecological value, we stress the need of specific actions aimed at the urgent protection of these oases of biodiversity