A study on damage evolution in composite laminates. A Ritz computational framework for VAT plates and experimental tests for SHM systems

This thesis investigates the development and implementation of numerical damage models and experimental tests for damage detection and monitoring in thermoplastic composite plates.The core of this thesis is a numerical formulation based on the Ritz method within the Continuum Damage Mechanics framework, offering insights into the initiation, evolution, and failure of composite laminates, including Variable Angle Tow configurations. This method shows a remarkable reduction in computational costs compared to traditional approaches. However, the study also identifies limitations in the single-domain Ritz approach, highlighting the need for adaptive techniques to mitigate spurious numerical effects.Additionally, part of the research activities have been performed at Centro Italiano Ricerche Aerospaziali, collaborating on an ongoing project featuring experimental tests on thermoplastic composite materials. This experimental campaign involved testing thermoplastic composite coupons equipped with various sensors, such as Fibre Bragg Gratings and distributed fibre optics. These tests aimed to evaluate the ability of the considered sensors to detect and localise damage under controlled conditions. The findings indicate that both sensor types are effective in damage detection, providing essential data for refining the numerical models, and laying the groundwork for the development of a fully functional SHM system for thermoplastic composite materials in aerospace applications.Future research directions include extensive experimental validation of the numerical models, integration of advanced sensor technologies with SHM systems, and the development of sophisticated algorithms for data analysis and damage prediction. The ultimate goal is to create more robust and reliable SHM systems, ensuring the safety and longevity of engineering structures

An adaptive Ritz formulation for progressive damage modelling in variable angle tow composite plates

In this work, an adaptive Ritz model for the analysis of variable angle tow composite plates featuring damage initiation and evolution under progressive loading is proposed, developed, implemented and tested. The plate kinematics is represented employing a first-order shear deformation theory, while the plate equilibrium equations at a given load step are obtained by minimizing the structure potential energy. The constitutive behaviour is modelled within the framework of continuum damage mechanics. In particular the initiation and evolution of damage, up to failure, are tracked by defining irreversible damage indices related to both fibres and matrix, both in tensile or compression loading. The discrete equations are then obtained by assuming a polynomial Ritz approximation of the primary kinematic variables in the energy minimization. Preliminary tests show how the application of the method as a single-domain approach induces the emergence of problematic spurious effects, related to Gibbs artefacts due to the inability of the selected polynomial basis to represent damage localization. An adaptive multi-domain technique is thus proposed to circumvent such issues, which has been successfully validated by benchmark tests. Eventually, original results about variable angle tow plates featuring damage evolution under progressive loading are presented

Approximating Constraint Propagation in Datalog

We present a technique exploiting Datalog with aggregates to improve the performance of programs with arithmetic (in)equalities. Our approach employs a source-to-source program transformation which approximates the propagation technique from Constraint Programming. The experimental evaluation of the approach shows good run time speed-ups on a range of non-recursive as well as recursive programs. Furthermore, our technique improves upon the previously reported in the literature constraint magic set transformation approach.Comment: Online Proceedings of the 11th International Colloquium on Implementation of Constraint LOgic Programming Systems (CICLOPS 2011), Lexington, KY, U.S.A., July 10, 201

Exploiting Web Technologies to Connect Business Process Management and Engineering

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Continental phylogeography of an ecologically and morphologically diverse neotropical songbird, Zonotrichia capensis

The Neotropics are exceptionally diverse, containing roughly one third of all extant bird species on Earth. This remarkable species richness is thought to be a consequence of processes associated with both Andean orogenesis throughout the Tertiary, and climatic fluctuations during the Quaternary. Phylogeographic studies allow insights into how such events might have influenced evolutionary trajectories of species and ultimately contribute to a better understanding of speciation. Studies on continentally distributed species are of particular interest because different populations of such taxa may show genetic signatures of events that impacted the continentwide biota. Here we evaluate the genealogical history of one of the world’s most broadly-distributed and polytypic passerines, the rufous-collared sparrow (Zonotrichia capensis).Fil: Lougheed, Stephen C.. Queen’s University. Department of Biology; Canadá;Fil: Campagna, Leonardo. Cornell University; Estados Unidos de América; Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Parque Centenario. Museo Argentino de Ciencias Naturales. División de Ornitología; Argentina;Fil: Dávila, José A.. Instituto de Investigación en Recursos Cinegéticos; España;Fil: Tubaro, Pablo Luis. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Parque Centenario. Museo Argentino de Ciencias Naturales; Argentina; Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Parque Centenario. Museo Argentino de Ciencias Naturales. División de Ornitología; Argentina;Fil: Lijtmaer, Dario Alejandro. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Parque Centenario. Museo Argentino de Ciencias Naturales; Argentina; Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Parque Centenario. Museo Argentino de Ciencias Naturales. División de Ornitología; Argentina;Fil: Handford, Paul. University of Western Ontario. Department of Biology; Canadá

Bilateral Symmetry of Visual Function Loss in Cone-Rod Dystrophies.

PURPOSE: To investigate bilateral symmetry of visual impairment in cone-rod dystrophy (CRD) patients and understand the feasibility of clinical trial designs treating one eye and using the untreated eye as an internal control. METHODS: This was a retrospective study of visual function loss measures in 436 CRD patients followed at the Ophthalmology Department of the Catholic University in Rome. Clinical measures considered were best-corrected visual acuity, focal macular cone electroretinogram (fERG), and Ganzfeld cone-mediated and rod-mediated electroretinograms. Interocular agreement in each of these clinical indexes was assessed by t- and Wilcoxon tests for paired samples, structural (Deming) regression analysis, and intraclass correlation. Baseline and follow-up measures were analyzed. A separate analysis was performed on the subset of 61 CRD patients carrying likely disease-causing mutations in the ABCA4 gene. RESULTS: Statistical tests show a very high degree of bilateral symmetry in the extent and progression of visual impairment in the fellow eyes of CRD patients. CONCLUSIONS: These data contribute to a better understanding of CRDs and support the feasibility of clinical trial designs involving unilateral eye treatment with the use of fellow eye as internal control

Reliability of forced internal rotation and active internal rotation to assess lateral instability of the biceps pulley

Purpose: the aim of this study was to investigate the relationship between positive painful forced internal rotation (FIR) and lateral pulley instability in the presence of a pre-diagnosed posterosuperior cuff tear. The same investigation was conducted for painful active internal rotation (AIR). Methods: a multicenter prospective study was conducted in a series of patients scheduled to undergo arthroscopic posterosuperior cuff repair. Pain was assessed using a visual analog scale (VAS) and the Disabilities of the Arm, Shoulder and Hand questionnaire (DASH) was administered. The VAS score at rest, DASH score, and presence/absence of pain on FIR and AIR were recorded and their relationships with lesions of the lateral pulley, cuff tear patterns and shape of lesions were analyzed. Results: the study population consisted of 115 patients (mean age: 55.1 years) recruited from 12 centers. The dominant arm was affected in 72 cases (62.6%). The average anteroposterior extension of the lesion was 1.61 cm. The mean preoperative VAS and DASH scores were 6.1 and 41.8, respectively. FIR and AIR were positive in 94 (81.7%) and 85 (73.9%) cases, respectively. The lateral pulley was compromised in 50 cases (43.4%). Cuff tears were partial articular in 35 patients (30.4%), complete in 61 (53%), and partial bursal in 19 (16.5%). No statistical correlation between positive FIR or AIR and lateral pulley lesions was detected. Positive FIR and AIR were statistically associated with complete lesions. Negative FIR was associated with the presence of partial articular tears. Conclusions: painful FIR in the presence of a postero-superior cuff tear does not indicate lateral pulley instability. When a cuff tear is suspected, positive FIR and AIR are suggestive of full-thickness tear patterns while a negative FIR suggests a partial articular lesion. Level of evidence: level I, validating cohort study with good reference standards

PRODPROC- Product and Production Process Modeling and Configuration ⋆

Abstract. Software product configurators are an emerging technology that supports companies in deploying mass customization strategies. Such strategies need to cover the management of the whole customizable product cycle. Adding process modeling and configuration features to a product configurator may improve its ability to assist mass customization development. In this paper, we describe a modeling framework that allows one to model both a product and its production process. We first introduce our framework focusing on its process modeling capabilities. Then, we outline a possible implementation based on Constraint Logic Programming of such product/process configuration system. A comparison with some of the existing systems for product configuration and process modeling concludes the paper.