76 research outputs found

    A hybrid method for inversion of 3D DC resistivity logging measurements

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    This paper focuses on the application of hp hierarchic genetic strategy (hp-HGS) for solution of a challenging problem, the inversion of 3D direct current (DC) resistivity logging measurements. The problem under consideration has been formulated as the global optimization one, for which the objective function (misfit between computed and reference data) exhibits multiple minima. In this paper, we consider the extension of the hp-HGS strategy, namely we couple the hp-HGS algorithm with a gradient based optimization method for a local search. Forward simulations are performed with a self-adaptive hp finite element method, hp-FEM. The computational cost of misfit evaluation by hp-FEM depends strongly on the assumed accuracy. This accuracy is adapted to the tree of populations generated by the hp-HGS algorithm, which makes the global phase significantly cheaper. Moreover, tree structure of demes as well as branch reduction and conditional sprouting mechanism reduces the number of expensive local searches up to the number of minima to be recognized. The common (direct and inverse) accuracy control, crucial for the hp-HGS efficiency, has been motivated by precise mathematical considerations. Numerical results demonstrate the suitability of the proposed method for the inversion of 3D DC resistivity logging measurements

    A hybrid method for inversion of 3D DC resistivity logging measurements

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    Long-Term Health Effects of the 9/11 Disaster

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    The terrorist attacks on the World Trade Center towers on September 11, 2001, also referred as 9/11, was an iconic event in US history that altered the global and political response to terrorism. The attacks, which involved two planes hitting the twin towers in Lower Manhattan, New York City, resulted in the collapse of the buildings and over 2800 deaths of occupants of the buildings, fire, police and other responders and persons on the street in the vicinity of the collapsing buildings. The destroyed towers and the surrounding buildings have since been replaced but the health effects that resulted from the release of tons of dust, gases and debris as well as the life threat trauma are ongoing, and represent a major health burden among persons directly exposed. Hundreds of scientific publications have documented the physical and mental health effects attributed to the disaster. The current state-of-the-art in understanding the ongoing interactions of physical and mental health, especially PTSD, and the unique mechanisms by which pollutants from the building collapse, have resulted in long term pulmonary dysfunction, course of previously reported conditions, potential emerging conditions (e.g., heart disease and autoimmune diseases), as well as quality of life, functioning and unmet health care needs would be in the purview of this Special Issue on the 9/11 Disaster

    Healthy snacks consumption and the Theory of Planned Behaviour. The role of anticipated regret

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    Two empirical studies explored the role of anticipated regret (AR) within the Theory of Planned Behavior (TPB) framework (Ajzen, 1991), applied to the case of healthy snacks consumption. AR captures affective reactions and it can be defined as an unpleasant emotion experienced when people realize or imagine that the present situation would be better if they had made a different decision. In this research AR refers to the expected negative feelings for not having consumed healthy snacks (i.e., inaction regret). The aims were: a) to test whether AR improves the TPB predictive power; b) to analyze whether it acts as moderator within the TPB model relationships. Two longitudinal studies were conducted. Target behaviors were: consumption of fruit and vegetables as snacks (Study 1); consumption of fruit as snacks (Study 2). At time 1, the questionnaire included measures of intention and its antecedents, according to the TPB. Both the affective and evaluative components of attitude were assessed. At time 2, self-reported consumption behaviors were surveyed. Two convenience samples of Italian adults were recruited. In hierarchical regressions, the TPB variables were added at the first step; AR was added at the second step, and the interactions at the last step. Results showed that AR significantly improved the TPB ability to predict both intentions and behaviours, also after controlling for intention. In both studies AR moderated the effect of affective attitude on intention: affective attitude was significant only for people low in AR
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