Use of the 3D Equilibrium Equations in the Free‐Edge Analyses for Laminated Structures with the Variable Kinematics Approach

This paper compares out-of-plane stresses evaluated with Hooke’s Law and the stress recovery technique, focusing on the free edges of composite plates and shells. The Carrera Unified Formulation and the finite element method are adopted to derive the governing equations. Lagrange polynomials are implemented in the equivalent single-layer, layer-wise, and variable kinematics approaches. The latter is used to refine structural models locally and reduce computational overheads. Laminated plates and shells subjected to uniaxial tension are considered. The out-of-plane stresses are compared with references from the existing literature for most cases. The results demonstrate that the stress recovery technique effectively calculates stresses and improves the accuracy of equivalent single-layer models. Furthermore, layer-wise models are needed for accurate results near the free-edge zone. Finally, variable kinematics theories are helpful in accurately detecting local phenomena along the structure’s thickness

Use of Lagrange polynomials to build refined theories for laminated beams, plates and shells

This paper proposes an equivalent single-layer approach for modeling laminated structures, where the number layers to be considered as a single one is chosen a priori by the user. Lagrange points are set to locate and, eventually, join equivalent single-layer and layer-wise tenchiques by imposing displacement continuity in the thickness direction. The Finite Element (FE) method is applied to provide numerical solutions whereas the Carrera Unified Formulation (CUF) is used to generate the related stiffness matrices in a compact and straightforward way. The approach is employed using one-dimensional beam and two-dimensional plate and shell models and several case studies, taken from well-known examples in the literature, are analyzed. Results clearly show the advantages and superiority of the present approach to completely capture the displacements and the distribution of the axial stress components, whereas local values of the shear stresses can be obtained by opportunely chosing the Lagrange points pattern opportunely

Refined multilayered beam, plate and shell elements based on Jacobi polynomials

In this paper, theories of structures based on hierarchical Jacobi expansions are explored for the static analysis of multilayered beams, plates and shells. They belong to the family of classical orthogonal polynomials. This expansion is employed in the framework of the Carrera Unified Formulation (CUF), which allows to generate finite element stiffness matrices in a straightforward way. CUF allows also to employ both layer-wise and equivalent single layer approaches in order to obtain the desired degree of precision and computational cost. In this work, CUF is exploited for the analysis of one-dimensional beams and two-dimensional plates and shells, and several case studies from the literature are analysed. Displacements, in-plane, transverse and shear stresses are shown. In particular, for some benchmarks, the shear stresses are calculated using the constitutive relations and the stress recovery technique. The obtained results clearly show the convenience of using equivalent single layer models when calculating displacements, in-plane stresses and shear stresses recovered by three-dimensional indefinite equilibrium equations. On the other hand, layer-wise models are able to accurately predict the structural behaviour, even though higher degrees of freedom are needed

Evaluation of transverse shear stresses in layered beams/plates/shells via stress recovery accounting for various CUF-based theories

This paper exploits the stress recovery technique to evaluate the out-of-plane stress components in the static analysis of composite beams, plates and shells. This technique is implemented in the framework of the Carrera Unified Formulation, an approach allowing the implementation of the theories of structures in a compact way. This work uses Taylor, Legendre and Jacobi polynomials with equivalent single-layer and layer-wise approaches. The finite element method is applied to provide numerical solutions. Multi-layered beams, plates and shells subjected to different loading and boundary conditions are studied to validate and assess the proposed technique. The results are compared with those from the literature and show that the stress recovery technique provides reasonable accuracy for the shear stresses, even with lower-order models. Furthermore, results confirm that, when dealing with thick structures, the adoption of layer-wise models is mandatory to obtain accurate results

WHO Clinical Staging of HIV Infection and Disease, Tuberculosis and Eligibility for Antiretroviral Treatment: Relationship to CD4 Lymphocyte Counts.

SETTING: Thyolo district, Malawi. OBJECTIVES: To determine in HIV-positive individuals aged over 13 years CD4 lymphocyte counts in patients classified as WHO Clinical Stage III and IV and patients with active and previous tuberculosis (TB). DESIGN: Cross-sectional study. METHODS: CD4 lymphocyte counts were determined in all consecutive HIV-positive individuals presenting to the antiretroviral clinic in WHO Stage III and IV. RESULTS: A CD4 lymphocyte count of < or = 350 cells/microl was found in 413 (90%) of 457 individuals in WHO Stage III and IV, 96% of 77 individuals with active TB, 92% of 65 individuals with a history of pulmonary TB (PTB) in the last year, 91% of 89 individuals with a previous history of PTB beyond 1 year, 81% of 32 individuals with a previous history of extra-pulmonary TB, 93% of 107 individuals with active or past TB with another HIV-related disease and 89% of 158 individuals with active or past TB without another HIV-related disease. CONCLUSIONS: In our setting, nine of 10 HIV-positive individuals presenting in WHO Stage III and IV and with active or previous TB have CD4 counts of < or = 350 cells/microl. It would thus be reasonable, in this or similar settings where CD4 counts are unavailable for clinical management, for all such patients to be considered eligible for antiretroviral therapy

First Demonstration of MANTRA IPoWDM Convergent SDN Architecture using SONiC White Box and 400ZR/ZR+ Pluggables

In this work, the MANTRA (Metaverse ready Architectures for Open Transport) "Single"IP over Wavelength Division Multiplexing (IPoWDM) architecture is implemented and experimentally demonstrated in a network testbed employing three SDN Controllers (IP, Optical and Hierarchical) and Software for Open Networking in the Cloud (SONiC) white box equipped with 400ZR and 400ZR+ coherent pluggable transceivers

Infectious agents including COVID-19 and the involvement of blood coagulation and fibrinolysis. A narrative review

Platelets, blood coagulation along with fibrinolysis are greatly involved in the pathophysiology of infectious diseases induced by bacteria, parasites and virus. This phenomenon is not surprising since both the innate immunity and the hemostatic systems are two ancestral mechanisms which closely cooperate favoring host's defense against foreign invaders. However, the excessive response of these systems may be dangerous for the host itself