Node adaptation for global collocation with radial basis functions using direct multisearch for multiobjective optimization

Meshless methods are used for their capability of producing excellent solutions without requiring a mesh, avoiding mesh related problems encountered in other numerical methods, such as finite elements. However, node placement is still an open question, specially in strong form collocation meshless methods. The number of used nodes can have a big influence on matrix size and therefore produce ill-conditioned matrices. In order to optimize node position and number, a direct multisearch technique for multiobjective optimization is used to optimize node distribution in the global collocation method using radial basis functions. The optimization method is applied to the bending of isotropic simply supported plates. Using as a starting condition a uniformly distributed grid, results show that the method is capable of reducing the number of nodes in the grid without compromising the accuracy of the solution. (C) 2013 Elsevier Ltd. All rights reserved.

An overview on how failure analysis contributes to flight safety in the Portuguese Air Force

Failure analysis has been, throughout the years, a fundamental tool used in the aerospace sector, supporting assessments performed by sustainment and design engineers mainly related to failure modes and material suitability. The predicted service life of aircrafts often exceeds 40 years, and the design assured life rarely accounts for all in service loads and in service environmental menaces that aging aircrafts must deal with throughout their service lives. From the most conservative safe-life conceptual design approaches to the most recent on-condition based design approaches, assessing the condition and predicting the failure modes of components and materials are essential for the development of adequate preventive and corrective maintenance actions as well as for the accomplishment and optimization of scheduled maintenance programs of aircrafts. Moreover, as the operational conditions of aircrafts may vary significantly from operator to operator (especially in military aircraft), it is necessary to access if the defined maintenance programs are adequate to guarantee the continuous reliability and safe usage of the aircrafts, preventing catastrophic failures which bear significant maintenance and repair costs, and that may lead to the loss of human lives. Thus being, failure analysis and material investigations performed as part of aircraft accidents and incidents investigations arise as powerful tools of the utmost importance for safety assurance and cost reduction within the aeronautical and aerospace sectors. The Portuguese Air Force (PRTAF) has operated different aircrafts throughout its long existence, and in some cases, has operated a particular type of aircraft for more than 30 years, gathering a great amount of expertise in: assessing failure modes of the aircrafts materials; conducting aircrafts accidents and incidents investigations (sometimes with the participation of the aircraft manufacturers and/or other operators); and in the development of design and repair solutions for in-service related problems. This paper addresses several studies to support the thesis that failure analysis plays a key role in flight safety improvement within the PRTAF. It presents a short summary of developed

Positive solutions of fourth order problems with clamped beam boundary conditions

n this paper we make an exhaustive study of the fourth order linear operator u((4)) + M u coupled with the clamped beam conditions u(0) = u(1) = u'(0) = u'(1) = 0. We obtain the exact values on the real parameter M for which this operator satisfies an anti-maximum principle. Such a property is equivalent to the fact that the related Green's function is nonnegative in [0, 1] x [0, 1]. When M < 0 we obtain the best estimate by means of the spectral theory and for M > 0 we attain the optimal value by studying the oscillation properties of the solutions of the homogeneous equation u((4)) + M u = 0. By using the method of lower and upper solutions we deduce the existence of solutions for nonlinear problems coupled with this boundary conditions. (C) 2011 Elsevier Ltd. All rights reserved.

Water quality issues in rivers, lakes and reservoirs in Asian countries: an approach to the problems and the methodologies

Water covers over 70% of the Earth's surface, and is vital for all known forms of life. But only 3% of the Earth's water is fresh water, and less than 0.3% of all freshwater is in rivers, lakes, reservoirs and the atmosphere. However, rivers and lakes are an important part of fresh surface water, amounting to about 89%. In this Master Thesis dissertation, the focus is on three types of water bodies – rivers, lakes and reservoirs, and their water quality issues in Asian countries. The surface water quality in a region is largely determined both by the natural processes such as climate or geographic conditions, and the anthropogenic influences such as industrial and agricultural activities or land use conversion. The quality of the water can be affected by pollutants discharge from a specific point through a sewer pipe and also by extensive drainage from agriculture/urban areas and within basin. Hence, water pollutant sources can be divided into two categories: Point source pollution and Non-point source (NPS) pollution. Seasonal variations in precipitation and surface run-off have a strong effect on river discharge and the concentration of pollutants in water bodies. For example, in the rainy season, heavy and persistent rain wash off the ground, the runoff flow increases and may contain various kinds of pollutants and, eventually, enters the water bodies. In some cases, especially in confined water bodies, the quality may be positive related with rainfall in the wet season, because this confined type of fresh water systems allows high dilution of pollutants, decreasing their possible impacts. During the dry season, the quality of water is largely related to industrialization and urbanization pollution. The aim of this study is to identify the most common water quality problems in Asian countries and to enumerate and analyze the methodologies used for assessment of water quality conditions of both rivers and confined water bodies (lakes and reservoirs). Based on the evaluation of a sample of 57 papers, dated between 2000 and 2012, it was found that over the past decade, the water quality of rivers, lakes, and reservoirs in developing countries is being degraded. Water pollution and destruction of aquatic ecosystems have caused massive damage to the functions and integrity of water resources. The most widespread NPS in Asian countries and those which have the greatest spatial impacts are urban runoff and agriculture. Locally, mine waste runoff and rice paddy are serious NPS problems. The most relevant point pollution sources are the effluents from factories, sewage treatment plant, and public or household facilities. It was found that the most used methodology was unquestionably the monitoring activity, used in 49 of analyzed studies, accounting for 86%. Sometimes, data from historical databases were used as well. It can be seen that taking samples from the water body and then carry on laboratory work (chemical analyses) is important because it can give an understanding of the water quality. 6 papers (11%) used a method that combined monitoring data and modeling. 6 papers (11%) just applied a model to estimate the quality of water. Modeling is a useful resource when there is limited budget since some models are of free download and use. In particular, several of used models come from the U.S.A, but they have their own purposes and features, meaning that a careful application of the models to other countries and a critical discussion of the results are crucial. 5 papers (9%) focus on a method combining monitoring data and statistical analysis. When there is a huge data matrix, the researchers need an efficient way of interpretation of the information which is provided by statistics. 3 papers (5%) used a method combining monitoring data, statistical analysis and modeling. These different methods are all valuable to evaluate the water quality. It was also found that the evaluation of water quality was made as well by using other types of sampling different than water itself, and they also provide useful information to understand the condition of the water body. These additional monitoring activities are: Air sampling, sediment sampling, phytoplankton sampling and aquatic animal tissues sampling. Despite considerable progress in developing and applying control regulations to point and NPS pollution, the pollution status of rivers, lakes, and reservoirs in Asian countries is not improving. In fact, this reflects the slow pace of investment in new infrastructure for pollution control and growing population pressures. Water laws or regulations and public involvement in enforcement can play a constructive and indispensable role in environmental protection. In the near future, in order to protect water from further contamination, rapid action is highly needed to control the various kinds of effluents in one region. Environmental remediation and treatment of industrial effluent and municipal wastewaters is essential. It is also important to prevent the direct input of agricultural and mine site runoff. Finally, stricter environmental regulation for water quality is required to support protection and management strategies. It would have been possible to get further information based in the 57 sample of papers. For instance, it would have been interesting to compare the level of concentrations of some pollutants in the diferente Asian countries. However the limit of three months duration for this study prevented further work to take place. In spite of this, the study objectives were achieved: the work provided an overview of the most relevant water quality problems in rivers, lakes and reservoirs in Asian countries, and also listed and analyzed the most common methodologies.

Education for health: alcohol and young aged school teenagers

Introduction: Alcohol consumption starts at an early age in Portuguese people. Health problems and risk behavior associated with excessive consumption can be prevented or highly reduced through effective school programs. Health professionals, such as biomedical scientists, (BSc), are important in promoting healthy lifestyles through the transmission of knowledge. Objective: Explore the role of the BSc in promoting health via intervention and clarification actions, (ICA), with 9th grade students from Agrupamento de Escolas da Portela e Moscavide (AEPM) and Visconde Juromenha (AEVJ); Verify the relationship between participating in the ICA and the level of knowledge acquired from it. Methods: Behaviors and beliefs concerning alcohol consumption and knowledge about the repercussions of it in the human body, mainly regarding the liver, were assessed by questionnaire. The questionnaire was completed before and after the ICA, by the control group (CG) and the study group (SG), respectively. The answers concerning knowledge were given points, later converted to a score from 0 to 100%. Data was analyzed applying descriptive statistics and the t-student test using SPSS 20.0. Results: After statistical analysis, it was found an average score of 48.8% for SG and 46.2% for CG. The difference between groups was statistically significant only in AEPM where ICA included a practical methodology (microscopic and macroscopic observation of pork livers), contrary to AEVJ. Conclusions: BSc intervention through ICA’s improves teenagers’ knowledge. Theoretical knowledge associated with practical approaches improves the retention of information and the development of a conscious behavior about the consumption of alcohol.