Novel parametric reduced order model for aeroengine blade dynamics

© 2015 Elsevier Ltd. All rights reserved.The work introduces a novel reduced order model (ROM) technique to describe the dynamic behavior of turbofan aeroengine blades. We introduce an equivalent 3D frame model to describe the coupled flexural/torsional mode shapes, with their relevant natural frequencies and associated modal masses. The frame configurations are identified through a structural identification approach based on a simulated annealing algorithm with stochastic tunneling. The cost functions are constituted by linear combinations of relative errors associated to the resonance frequencies, the individual modal assurance criteria (MAC), and on either overall static or modal masses. When static masses are considered the optimized 3D frame can represent the blade dynamic behavior with an 8% error on the MAC, a 1% error on the associated modal frequencies and a 1% error on the overall static mass. When using modal masses in the cost function the performance of the ROM is similar, but the overall error increases to 7%. The approach proposed in this paper is considerably more accurate than state-of-the-art blade ROMs based on traditional Timoshenko beams, and provides excellent accuracy at reduced computational time when compared against high fidelity FE models. A sensitivity analysis shows that the proposed model can adequately predict the global trends of the variations of the natural frequencies when lumped masses are used for mistuning analysis. The proposed ROM also follows extremely closely the sensitivity of the high fidelity finite element models when the material parameters are used in the sensitivity

Novel frame model for mistuning analysis of bladed disc systems

The work investigates the application of a novel frame model to reduce the computational cost of the mistuning analysis of bladed disc systems. A full-scale finite element (FE) model of the bladed disc is considered as benchmark. The single blade frame configuration is identified via an optimization process. The individual blades are then assembled by 3D springs, whose parameters are determined via calibration process. The dynamics of the novel beam frame assembly is also compared to those obtained from three state-of-the-art FE-based reduced order models (ROMs): a lumped parameter approach; a Timoshenko beam assembly, and component mode synthesis (CMS) based techniques with free and fixed interfaces. The development of these classical ROMs to represent the bladed disc is also addressed in detail. A methodology to perform the mistuning analysis is then proposed and implemented. A comparison of the modal properties and forced response dynamics between the aforementioned ROMs and the full-scale FE model is presented. The case study demonstrates that the beam frame assembly can predict the variations of the blade amplitude factors with results being in agreement with the full-scale FE model. The CMS based ROMs underestimate the maximum amplitude factor, while the results obtained from beam frame assembly are generally conservative. The beam frame assembly is 4 times more computationally efficient than the CMS fixed-interface approach. This study proves that the beam frame assembly can efficiently predict the mistuning behavior of bladed discs when low order modes are of interest

Idiopathic calcium nephrolithiasis with pure calcium oxalate composition: clinical correlates of the calcium oxalate dihydrate/monohydrate (COD/COM) stone ratio

Pure calcium oxalate is the most frequent type of idiopathic kidney stone composition. Fourier transform infrared spectroscopy (FT-IR) allows to detect the ratio of calcium oxalate dihydrate (COD) and monohydrate (COM) crystals in stones, but the clinical significance of this parameter remains uncertain. The objective of this observational study was to verify the association of clinical and laboratory parameters of kidney stone disease with COD/COM ratio in a group of 465 (322 M, age 46 ± 14) patients suffering from idiopathic calcium nephrolithiasis with pure calcium oxalate stones (≥ 97%). Each participant underwent a complete clinical examination, serum chemistry, 24-h urine collection for the determination of the profile of lithogenic risk, and had stones analyzed by FT-IR. Most (62%) of the stones had a COD/COM ratio ≤ 0.25, and the urine chemistry of the corresponding patients showed a low prevalence of urinary metabolic abnormalities. With increasing COD/COM ratio intervals (0–0.25, 0.26–0.50, 0.51–0.75, 0.76–1), a significant association was observed for the number of urological procedures, serum calcium, 24-h urinary calcium excretion, prevalence of hypercalciuria and relative calcium oxalate supersaturation, and a negative trend was detected for the age of the first stone episode (all p values < 0.05). A linear regression model showed that the only parameters significantly associated with COD/COM ratio were 24-h urinary calcium excretion (standardized β = 0.464, p < 0.001) and urine pH (standardized β = 0.103, p = 0.013). In pure calcium oxalate idiopathic stones, COD/COM ratio may reflect the presence of urinary metabolic risk factors, and represent a guide for the prescription of urinary analyses

The prevention of analgesic opioids abuse: expert opinion

Opioids are drugs of reference for the treatment of moderate to severe pain. Their proper use and a periodic assessment of the patient are crucial to prevent misuse. A multidisciplinary group suggests strategies for all stakeholders involved in the management of pain and suggests the importance of the doctor-patient relationship

Rehabilitative treatment of patients with covid-19 infection: The p.a.r.m.a. evidence based clinical practice protocol

Background: The impact of the SARS-CoV-2 on the National Health System (NHS) required a reorganization of the various levels of care, which also involved the rehabilitation reality. Aim of the work: A clinical practice review of the literature was conducted to provide operational-rehabilitation guidelines adapt-ed to the local reality and to the recent corporate reorganization in the context of the COVID-19 emergency. Methods: A practice review of the available scientific evidence was regularly conducted from the start of the COVID-19 pandemic to periodically update the clinical practice guidelines. Articles that met the following inclusion criteria were included: studies conducted on human adult subjects with COVID-19 infection, un-dergoing rehabilitation in any hospitalization setting. Results: The results of this clinical practice update were periodically discussed with colleagues and collaborators in a multi-professional team, in order to guarantee a good clinical practice protocol, named P.A.R.M.A. Conclusions: The P.A.R.M.A. protocol is the result of a periodic review literature update, which has allowed us to take charge of patients affected by COVID-19 ac-cording to the most up-to-date clinical evidences, guaranteeing a shared and uniform treatment within a local reality in an era of health emergency. (www.actabiomedica.it)

Renal outcome in patients with congenital anomalies of the kidney and urinary tract.

15openopenSanna-Cherchi S; Ravani P; Corbani V; Parodi S; Haupt R; Piaggio G; Innocenti ML; Somenzi D; Trivelli A; Caridi G; Izzi C; Scolari F; Mattioli G; Allegri L; Ghiggeri GM.Sanna Cherchi, S; Ravani, P; Corbani, V; Parodi, S; Haupt, R; Piaggio, G; Innocenti, Ml; Somenzi, D; Trivelli, A; Caridi, G; Izzi, C; Scolari, Francesco; Mattioli, G; Allegri, L; Ghiggeri, G. M

Morphine metabolism, transport and brain disposition

The chemical structures of morphine and its metabolites are closely related to the clinical effects of drugs (analgesia and side-effects) and to their capability to cross the Blood Brain Barrier (BBB). Morphine-6-glucuronide (M6G) and Morphine-3-glucuronide (M3G) are both highly hydrophilic, but only M6G can penetrate the BBB; accordingly, M6G is considered a more attractive analgesic than the parent drug and the M3G. Several hypotheses have been made to explain these differences. In this review we will discuss recent advances in the field, considering brain disposition of M6G, UDP-glucoronosyltransferases (UGT) involved in morphine metabolism, UGT interindividual variability and transport proteins