Mixing layer-wise and refined equivalent-single layer FEs based on Lagrange expansions

In the aeronautic engineering, in case of the design of an aircraft system, the finite element model of the structure is usually developed by combining 1D and 2D elements, which opportunely approximate the mathematical domains of ribs, stringers, panels, and other components. Clearly, this discretization results in a simplification of reality. Indeed, in many applications, a complete description of the 3D stress field of a certain portion of the model may be mandatory. To accurately capture these localized 3D stress fields, solid models or high-order theories are demanded. However, in order to make the model more efficient, i.e. to balance computational cost and accuracy of the results, a global/local approach can be adopted. A popular approach for the global/local analysis of structures consists of formulating multiple kinematic models. In particular, different subregions of the structure are analyzed with different mathematical models, so that particular areas of interest can be described through an accurate description, as the Layer-Wise (LW) approach when dealing with laminated materials, whereas lower-order kinematics can be employed in the remaining zones. Although accurate, LW models may require the use of high computational efforts. Thus, in the last years, several efforts have been addressed by researchers to make the composite plate and shell models as accurate as efficient. One of the simple types of multiple-model method, for composite laminates analysis, is the concept of selective ply grouping or sublaminates (see [1]). This approach consists in creating some local regions in the plate/shell thickness direction, identified by specific ply or plies, whithin which accurate stresses are desired. The purpose of this work is the development of a mathematical model able to arbitrarily select multiple plies, within which the interlaminar stresses have to be accurately defined. The approach is developed in framework of the Carrera Unified Formulation [2], which allows the user to define the order of model as an input of the analysis, so that low- to higher-order models can be built in a global/local meaning without the need of any ad-hoc model. The proposed approach is applied to 1D beam and 2D plate/shell models, as well as on a stiffened panel from a real aeronautic application. The results show the capability of the present model to accurately describe the localized interlaminar phenomena in terms of stresses using the global/local approach

Effect of angiotensin-converting enzyme inhibitor and angiotensin receptor blocker initiation on organ support-free days in patients hospitalized with COVID-19

IMPORTANCE Overactivation of the renin-angiotensin system (RAS) may contribute to poor clinical outcomes in patients with COVID-19. Objective To determine whether angiotensin-converting enzyme (ACE) inhibitor or angiotensin receptor blocker (ARB) initiation improves outcomes in patients hospitalized for COVID-19. DESIGN, SETTING, AND PARTICIPANTS In an ongoing, adaptive platform randomized clinical trial, 721 critically ill and 58 non–critically ill hospitalized adults were randomized to receive an RAS inhibitor or control between March 16, 2021, and February 25, 2022, at 69 sites in 7 countries (final follow-up on June 1, 2022). INTERVENTIONS Patients were randomized to receive open-label initiation of an ACE inhibitor (n = 257), ARB (n = 248), ARB in combination with DMX-200 (a chemokine receptor-2 inhibitor; n = 10), or no RAS inhibitor (control; n = 264) for up to 10 days. MAIN OUTCOMES AND MEASURES The primary outcome was organ support–free days, a composite of hospital survival and days alive without cardiovascular or respiratory organ support through 21 days. The primary analysis was a bayesian cumulative logistic model. Odds ratios (ORs) greater than 1 represent improved outcomes. RESULTS On February 25, 2022, enrollment was discontinued due to safety concerns. Among 679 critically ill patients with available primary outcome data, the median age was 56 years and 239 participants (35.2%) were women. Median (IQR) organ support–free days among critically ill patients was 10 (–1 to 16) in the ACE inhibitor group (n = 231), 8 (–1 to 17) in the ARB group (n = 217), and 12 (0 to 17) in the control group (n = 231) (median adjusted odds ratios of 0.77 [95% bayesian credible interval, 0.58-1.06] for improvement for ACE inhibitor and 0.76 [95% credible interval, 0.56-1.05] for ARB compared with control). The posterior probabilities that ACE inhibitors and ARBs worsened organ support–free days compared with control were 94.9% and 95.4%, respectively. Hospital survival occurred in 166 of 231 critically ill participants (71.9%) in the ACE inhibitor group, 152 of 217 (70.0%) in the ARB group, and 182 of 231 (78.8%) in the control group (posterior probabilities that ACE inhibitor and ARB worsened hospital survival compared with control were 95.3% and 98.1%, respectively). CONCLUSIONS AND RELEVANCE In this trial, among critically ill adults with COVID-19, initiation of an ACE inhibitor or ARB did not improve, and likely worsened, clinical outcomes. TRIAL REGISTRATION ClinicalTrials.gov Identifier: NCT0273570

Finite elements based on Jacobi shape functions for the analysis of beams, plates and shells

This paper proposes the use of Jacobi polynomials to approximate higher-ordertheories of beam, plate, and shell structures. The Carrera unified formulation isused in this context to express displacement kinematics in a hierarchical form.In this manner, classical to complex higher-order theories can be implementedwith ease. Particular attention is focused on the attenuation and the correctionof the shear locking. Therefore, reduced integration as well as mixed interpo-lation of tensorial components methods are investigated against the new finiteelements. Several case studies are taken into account to highlight the effective-ness and robustness of the proposed approach. Also, several benchmarks areprovided for future assessments

Biogas from anaerobic digestion of fruit and vegetable wastes: experimental results on pilot-scale and preliminary performance evaluation of a full-scale power plant

This paper presents the experimental results obtained through an anaerobic digestion pilot plant by using fruit and vegetable wastes as single substrate. The substrate materials were sampled from the wastes produced by the Fruit and Vegetable Wholesale Market of Sardinia (Italy). The experimental study was carried out over a period of about six months to evaluate the most suitable operating parameters of the process depending on the availability of different kinds of fruit and vegetable wastes over the different periods of the year. Overall, the optimum daily loading rate of wastes was 35 kg/d, with a corresponding hydraulic residence time of 27 days. The optimum organic loading rate ranged from 2.5 to 3.0 kgVS/m3d and the average specific biogas production was about 0.78 Nm3/kgVS, with a specific methane yield of about 0.43 Nm3/kgVS. The results of the experimental investigation were used for a preliminary performance evaluation of a full-scale anaerobic digestion power plant for treating all the fruit and vegetable wastes produced by the Wholesale Market of Sardinia (9 t/d). The estimate of daily methane production (290 Nm3/d) leads to a CHP unit with a power output of about 42 kW and an annual electrical production of about 300 MWh/y (about 25% of the wholesale market electrical consumption). The AD power plant also shows interesting economic features, since its energy production cost (about 150 €/MWh) is slightly lower than the energy purchase cost of the wholesale market (about 200 €/MWh) and a pay-back time of about 7.25 years can be achieved in the case of dispatching the electrical energy to the national grid. The PBT decreases to about 5.4 years if 50% of the available thermal energy is used to substitute heat production from fossil fuel boilers. Keywords Anaerobic digestion; fruit and vegetable waste; biogas production; mesophilic digestion

Effect of Antiplatelet Therapy on Survival and Organ Support–Free Days in Critically Ill Patients With COVID-19

International audienc