Um refinamento h, p e hp adaptativo na análise de flexao de placas semi-espessas

O Método dos Elementos Finitos é utilizado através de suas versoes adaptativas h, p e hp para analisar problemas de flexáo elástica de placas semi-espessas. A abordagem adotada considera a influencia das deformacoes cisalhantes transversais, caracterizando, assim, a teoria de primeira ordem para flexiio de placas semi-espessas, conhecida por teoria de Reissner- Mindlin. Devido A complexidade no gerenciamento das informacoes em um problema autoadaptativo, é utilizada a filosofia de programaciio orientada a objetos (C++). Na discretizaciio do problema é adotada a base hierárquica para trigngulos de Webb e Abouchacra, recentemente proposta em12. O estimador de erro de Zienkiewicz e Zhu13 é utilizado para guiar o processo de refinamento da malha. Finalmente, sáo apresentados alguns resultados numéricos, sendo comparados, quando possível, com solucoes analíticas.In this work, the Finite Element Method is used through its h, p and hp adaptive version to solve the Reissner-Mindlin plate elastic bending problem. The object oriented programming philosophy (C++) is employed in order to overcome the natural difficulties of handling information in a self-adaptive finite element code. The Webb and Abouchacra hierarchical basis for triangular e lements, recently proposed in12, is employed to discretize the plate domain. The adaptive refinement is done in accordance with the Zienkiewicz and Zhu error estimator13. Finally, some numerical results are shown, being compared with analytical solutions, when they are available.Peer Reviewe

Multidisciplinary study of biological parameters and fatigue evolution in quay crane operators

In intermodal terminals the handling of containers and the number of accidents still depends on a wide range of human errors due to fatigue despite the automation level reached nowadays. For this reason it is very important to increase knowledge about the factors affecting the propensity of operators to make errors, increasing the chance of accidents happening. The aim of this work is to propose a novel approach to assess fatigue and performance lev els in quay crane operators as a function of physiological parameters and of the many varying boundary conditions encountered in daily work. During their work, quay crane operators have to deal with variable environmental conditions, such as task type, wind speed and direction, lighting conditions that redu ce visibility that can require an exacting level of attention. In the trial eight operators have been examined in a session lastin g four hours. All actual conditions are reproduced through a fully imme rsive quay crane simulator. The operator completes the assigned task (the same for each one) and can see through four wide monito rs a high quality virtual reality view of the simulation. Most biological parameters are acquired using different devices including a Holter ECG monitor, electromyographic monitoring the four trunk muscles most involved in the test, eye tracker and seat - body pressure interface for both seat pan and backrest. Changes in physiological parameters have been monitored during the trial and interesting correlations with performance levels and boundary conditions ha ve been f ound for each operator, in accord ance with their age and skills. The present study can form the basis for further investigations aimed at developing a cost effective, reliable and robust system for monitoring increasing fat igue and for predicting the critical conditions that may result in an acciden

A flamelet generated manifolds lookup table tool for premixed turbulent combustion

No abstract available

Planning and design support tools for walkability: a guide for urban analysts

We present a survey of operational methods for walkability analysis and evaluation, which we hold to show promise as decision-support tools for sustainability-oriented planning and urban design. An initial overview of the literature revealed a subdivision of walkability studies into three main lines of research: transport and land use, urban health, and livable cities. A further selection of articles from the Scopus and Web of Science databases focused on scientific papers that deal with walkability evaluation methods and their suitability as planning and decision-support tools. This led to the definition of a taxonomy to systematize and compare the methods with regard to factors of walkability, scale of analysis, attention on profiling, aggregation methods, spatialization and sources of data used for calibration and validation. The proposed systematization aspires to offer to non-specialist but competent urban analysts a guide and an orienteering, to help them integrate walkability analysis and evaluation into their research and practice

Multi-Analytical Techniques to Define the Mineralogical and Petrophysical Characteristics and Provenance of Siliceous Lithic Findings: The Case Study of La Calvera Rock Shelter (Cantabria, Spain)

This archaeometric study aims at characterizing the archaeological finds belonging to the lithic industry from La Calvera rock shelter (Camaleño, Cantabria) and at hypothesizing the possible provenance of each material. The site, located in the mountainous area of Picos de Europa National Park (more than 1000 m a.s.l.) close to the megalithic complex of Peña Oviedo, is characterized by the presence of hearths and charcoal remains, ancient pottery, and a rich lithic assemblage composed of siliceous rocks dating back to >8000 BP and linked to the first Holocene occupations of the Cantabrian Mountains. For the study of the rock shelter’s lithic assemblage, a multi-analytical approach was used: SEM-EDS and XRD analyses were performed to define the microtextural characteristics of samples and to identify the amorphous/crystalline phases; physical and mechanical tests were conducted to define the petrophysical properties (density, porosity, imbibition and saturation indexes, mechanical strength) of the samples. Preliminary data of chemical compositions, obtained by portable XRF, are also presented. The results show that the different siliceous materials (quartzite, cherts, hyaline quartz) can be distinguished through the basic analytical techniques used here. In addition, most of the archaeological samples have mineralogical and petrographic features similar to the natural samples coming from nearby outcrops, corroborating the hypothesis of a local material supply. The presence of local sources of useful raw materials could have favoured the site’s occupation. Finally, the diverse compositional and textural feature of the analysed materials result in different mechanical properties (porosity, density, hardness, workability), so they likely had different uses and technical functions

Vertigo and dizziness in children: An update

Background: Vertigo and dizziness are relatively infrequent in paediatric patients, but specific data on the prevalence of these disorders are limited and influenced by various factors, including the age of the examined population. These conditions often have a significant impact on patients’ and parents’ quality of life. The aim of this paper is to investigate the prevalence of different aetiologies of vertigo in the paediatric population through a systematic review. Methods: According to PRISMA guidelines, a systematic review of the literature was performed. Medline and Embase were searched from January 2011 through to 10 September 2021. The search yielded 1094 manuscripts, which were reduced to 7 upon the application of inclusion criteria. Results: A total of 2470 paediatric patients were evaluated by the selected papers. Vestibular Migraine was the most frequently diagnosed condition, occurring alone or in association with other diseases. Overall, audio-vestibular disorders represented the second cause of vertigo, and the prevalence appears to increase according to age growth. Over the years, even though we assisted in the amelioration of diagnostic rates, partially related to an improvement in diagnostic tools, the aetiology of vertigo remains still unclear in a variable percentage of patients. Conclusion: Vertigo in children, despite being an uncommon symptom, requires a multidisciplinary approach, often involving Paediatricians, Neurologists and Otorhinolaryngologists. A comprehensive evaluation of children suffering from vertigo is crucial for establishing a successful therapy and reducing parental worries

Survey on the occurrence of silage volatile organic compounds in the Po Valley - Italy

The volatile organic compounds (VOC) are the fermentation products and used to assess the quality of ensiled forages. The study aimed to monitor the VOC concentrations in silage and haylage by GC/FID system and to reveal the relationships among these different end-fermentation products by carrying out a multivariate analysis. Forty-six compounds were quantified by GC/FID system in a single chromatographic run. The average repeatability and reproducibility coefficients of variation obtained on standard solutions, composed by 0.1 mL/L of each VOC (solution A) or volatile fatty acids (VFA, solution B), were 0.028 and 0.017 (absolute value), respectively. The average repeatability and reproducibility coefficients of variation obtained on silage samples were 0.026 and 0.027, respectively. Mean values of recovery obtained on the standard solutions at different concentration levels of compounds were in the range 0.95–1.04 (absolute values), and no effect of analyte concentration was observed on recovery. When multivariate analysis was carried out on whole database, 7 factors were retained and they explained 0.50 of the total variability. The factors were interpreted for their biological meanings, based on specific VOC loading on each extracted latent structure. Alfalfa haylage and ryegrass silage were characterized by higher contents of valeric and butyric acids, methyl and ethyl butyrate, 2,3-butaneldiol, 1-butanol, and 2-butanol compared with the other fermented products. Except for mixture crop silage, all the fermented products containing legume crops had higher levels of 2-methyl-1-propanol, 2-methyl-1-butanol, 3-methyl-1-butanol, 2-phenyl ethanol, and methanol and lower contents of ethanol, ethyl lactate, and ethyl acetate compared with the other fermented products. Silage containing grass crops had higher levels of acetic and lactic acids, and 1,2-propanediol respect to the other investigated products. The most part of the investigated fermented products were characterized by the presence of 2-methyl propionaldehyde and 2-methyl butyraldehyde. The VOC profile determination of ensiled products provides useful information for an overall evaluation of the fermentative quality of silages and haylage