A modified harmony search approach on structural identification and damage detection of wind turbine supporting structures

Although numerous structural identification methods have been proposed, most of them are problem dependent, rely on classical approaches based on mathematical concepts, and/or are based on changes in modal characteristics that are not sensitive to damage. This study aims to utilize a metaheuristic modified optimization algorithm for the identification of damage in a numerically modeled 5-MW reference turbine. A variety of damage severities, sensor numbers and noise percentages were investigated. The results show that the presented algorithm’s identification accuracy is not affected by the magnitude of damage whereas sensor configuration and noise severity do have a significant effect. The satisfying results encourage considering its application on in-situ structural identification tasks based on experimental measurements

A modified adaptive harmony search algorithm approach on structural identification and damage detection

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The Effectiveness of a Meta Cognitive Strategy on Developing the Scientific Reasoning, Self Efficacy & Decision Making Skill in Science Teaching among Student-Teachers

The current research aimed at investigating the effectiveness of a meta cognitive strategy on developing scientific reasoning, self efficacy and decision making skills in teaching science among science studentteachers. Science teaching strategies course 2 prescribed for science majors at Al-Aqsa University was selected for experimentation. The researcher selected two sections: one as experimental (n= 48) and the other as control group (n= 53). The researcher designed three instruments: a 24- multiple choice questions of scientific reasoning test; a 48- item self-efficacy in science teaching scale, and a 30-questions decisionmaking in science teaching test. The validity of the scientific reasoning test was ensured via referees' validity and its reliability through split-half method (0.87) Reliability was ensured via computing alpha Cronbach (0.82) and split half method (0.90) The decision-making test was 0.81. Before the start of the experiment, the three instruments were administered to the groups, and the means, standard deviations, ttest for two independent samples were computed. The findings showed that: there were statistically significant differences (p < 0.01) in favor of the experimental group in self-efficacy and decision making, whereas no statistically significant differences were observed in scientific reasoning. The researcher recommended using the meta cognitive strategy in University instruction and decreasing verbal teaching strategies

A modified harmony search approach on structural identification and damage detection of wind turbine supporting structures

Although numerous structural identification methods have been proposed, most of them are problem dependent, rely on classical approaches based on mathematical concepts, and/or are based on changes in modal characteristics that are not sensitive to damage. This study aims to utilize a metaheuristic modified optimization algorithm for the identification of damage in a numerically modeled 5-MW reference turbine. A variety of damage severities, sensor numbers and noise percentages were investigated. The results show that the presented algorithm’s identification accuracy is not affected by the magnitude of damage whereas sensor configuration and noise severity do have a significant effect. The satisfying results encourage considering its application on in-situ structural identification tasks based on experimental measurements

A geometric study for determining the optimum volume fraction of pre-embedded capsules for self-healing of cracks in a cementitious matrix

Funder: Yousef Jameel FoundationAbstract Autonomous healing of cracks using capsule-based systems is emerging as a promising solution to restore durability and strength of damaged structures. For satisfactory self-healing efficiency, both capsule geometry and dosage are to be determined for the concrete mix proportion. With previous research being performed on self-healing efficiency using different capsule shapes and crack patterns, this paper introduces quantitative numerical solutions on the optimal dosage of the capsules required to completely repair cracks in a three-dimensional model of a cementitious matrix. Four different sizes of spherical capsules ranging between 0.6 mm to 4.75 mm embedded within a mortar matrix were tested in the model and the model results were validated using previous experimental findings. As the cargo of capsules could be powder or liquid self-healing agents, three different scenarios were considered in this work to calculate the volume of the healing agent in the crack. It was found that the smaller the capsules the more homogenous and uniform the distribution of capsules is. However, the bigger sizes of the capsules are much preferable in terms of the amount of self-healing materials supplied to the cracked vicinity. For instance, capsules of 2–4 mm size could fill 80% of the crack volume but were localised and unevenly distributed on the planes of the crack. Overall, the developed model in this study provides a robust and efficient tool to quantitively design the proportions of cement-based self-healing systems. Based on the results of the geometric model, an ANN model was also developed to calculate healing volume in terms of the volume fraction of the healing agents and the size of capsules. Results showed very close values to those obtained by the numerical model.</jats:p

Th/U dating of marine and continental mollusk shell, and travertine samples in quaternary deposits in Morocco

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