Detection and localization of debonding damage in composite-masonry strengthening systems with the acoustic emission technique

Different types of strengthening systems, based on fiber reinforced materials, are under investigation for external strengthening of historical masonry structures. A full characterization of the bond behavior and of the short—and long-term failure mechanisms is crucial to ensure effective design, compatibility and durability of the strengthening solution. In this paper, the effectiveness of the Acoustic Emission (AE) technique for debonding characterization and localization on Fiber Reinforced Polymer (FRP)- and Steel Reinforced Grout (SRG)-strengthened clay bricks is investigated. The AE technique proofs to be efficient for damage detection during accelerated ageing tests under thermal cycles and during experimental shear bond tests. AE data demonstrated the thermal incompatibility between brick and epoxy-bonded FRP composites during the accelerated ageing tests and debonding damage was successfully detected, characterized and located during the shear bond tests.- (undefined

How Should Governments Address High Levels of Natural Radiation and Radon--Lessons from the Chernobyl Nuclear Accident and Ramsar, Iran

The authors discuss the high levels of natural background radiation in Ramsar, Iran, and offer data indicating that this has had little effect on the health of Ramsar\u27s inhabitants. The authors then examine the implications their research could have for public health policy

Joint Optimal Design and Operation of Hybrid Energy Storage Systems

The wide range of performance characteristics of storage technologies motivates the use of a hybrid energy storage systems (HESS) that combines the best features of multiple technologies. However, HESS design is complex, in that it involves the choice of storage technologies, the sizing of each storage element, and deciding when to charge and discharge each underlying storage element (the operating strategy.We formulate the problem of jointly optimizing the sizing and the operating strategy of an HESS that can be used for a large class of applications and storage technologies. Instead of a single set of storage element sizes, our approach determines the Pareto-optimal frontier of the sizes of the storage elements along with the corresponding optimal operating strategy. Thus, as long as the performance objective of a storage application (such as an off-grid microgrid) can be expressed as a linear combination of the underlying storage sizes, the optimal vector of storage sizes falls somewhere on this frontier. We present two case studies to illustrate our approach, demonstrating that a single storage technology is sometimes inadequate to meet application requirements, unlike an HESS designed using our approach. We also find simple, near-optimal, and practical operating strategies for these case studies, which allows us to gain several new engineering insights

On-line hydraulic state prediction for water distribution systems

World Environmental and Water Resources Congress 2009: Great Rivers Proceedings of World Environmental and Water Resources Congress 2009 May 17–21, 2009 Kansas City, MissouriThis paper describes and demonstrates a method for on‐line hydraulic state prediction in urban water networks. The proposed method uses a Predictor‐Corrector (PC) approach in which a statistical data‐driven algorithm is applied to estimate future water demands, while near real‐time field measurements are used to correct (i.e., calibrate) these predicted values on‐line. The calibration problem is solved using a modified Least Squares (LS) fit method. The objective function is the minimization of the least‐squares of the differences between predicted and measured hydraulic parameters (i.e., pressure and flow rates at several system locations), with the decision variables being the consumers' water demands. The a‐priori estimation (i.e., prediction) of the values of the decision variables, which improves through experience, facilitates a better convergence of the calibration model and provides adequate information on the system's hydraulic state for real time optimization. The proposed methodology is demonstrated on a prototypical municipal water distribution system

Repair of composite-to-masonry bond using flexible matrix

The paper presents an experimental investigation on an innovative repair method, in which composite reinforcements, after debonding, are re-bonded to the substrate using a highly deformable polymer. In order to assess the effectiveness of this solution, shear bond tests were carried out on brick and masonry substrates within two Round Robin Test series organized within the RILEM TC 250-CSM: Composites for Sustainable strengthening of Masonry. Five laboratories from Italy, Poland and Portugal were involved. The shear bond performance of the reinforcement systems before and after repair were compared in terms of ultimate loads, load-displacement curves and strain distributions. The results showed that the proposed repair method may provide higher strength and ductility than stiff epoxy resins, making it an effective and cost efficient technique for several perspective structural applications

Classification of Camellia (Theaceae) Species Using Leaf Architecture Variations and Pattern Recognition Techniques

Leaf characters have been successfully utilized to classify Camellia (Theaceae) species; however, leaf characters combined with supervised pattern recognition techniques have not been previously explored. We present results of using leaf morphological and venation characters of 93 species from five sections of genus Camellia to assess the effectiveness of several supervised pattern recognition techniques for classifications and compare their accuracy. Clustering approach, Learning Vector Quantization neural network (LVQ-ANN), Dynamic Architecture for Artificial Neural Networks (DAN2), and C-support vector machines (SVM) are used to discriminate 93 species from five sections of genus Camellia (11 in sect. Furfuracea, 16 in sect. Paracamellia, 12 in sect. Tuberculata, 34 in sect. Camellia, and 20 in sect. Theopsis). DAN2 and SVM show excellent classification results for genus Camellia with DAN2's accuracy of 97.92% and 91.11% for training and testing data sets respectively. The RBF-SVM results of 97.92% and 97.78% for training and testing offer the best classification accuracy. A hierarchical dendrogram based on leaf architecture data has confirmed the morphological classification of the five sections as previously proposed. The overall results suggest that leaf architecture-based data analysis using supervised pattern recognition techniques, especially DAN2 and SVM discrimination methods, is excellent for identification of Camellia species

Mortar-based systems for externally bonded strengthening of masonry

Mortar-based composite materials appear particularly promising for use as externally bonded reinforcement (EBR) systems for masonry structures. Nevertheless, their mechanical performance, which may significantly differ from that of Fibre Reinforced Polymers, is still far from being fully investigated. Furthermore, standardized and reliable testing procedures have not been defined yet. The present paper provides an insight on experimental-related issues arising from campaigns on mortar-based EBRs carried out by laboratories in Italy, Portugal and Spain. The performance of three reinforcement systems made out of steel, carbon and basalt textiles embedded in inorganic matrices has been investigated by means of uniaxial tensile coupon testing and bond tests on brick and stone substrates. The experimental results contribute to the existing knowledge regarding the structural behaviour of mortar-based EBRs against tension and shear bond stress, and to the development of reliable test procedures aiming at their homogenization/standardization