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.     

Chromatographic Fingerprinting with Multivariate Data Analysis for Detection and Quantification of Apricot Kernel in Almond Powder

Adulteration of almond powder samples with apricot kernel was solved by gas chromatographic fatty acid fingerprinting combined with multivariate data analysis methods (principal component analysis (PCA), PCA-linear discriminant analysis (PCA-LDA), partial least squares (PLS), and LS support vector machine (LS-SVM). Different almond and apricot kernel samples were mixed at concentrations ranging from 10 to 90% w/w. PCA and PCA-LDA methods were applied for the classification of almonds, apricot kernels, and mixtures. PLS and LS-SVM were used for the quantification of adulteration ratios of almond. Models were developed using a training data set and evaluated using a validation data set. The root mean square error of prediction (RMSEP) and coefficient of determination (R ²) of validation data set obtained for PLS and LS-SVM were 5.01, 0.964 and 2.29, 0.995, respectively. The results showed that the methods can be applied as an effective and feasible method for testing almond adulteration.     

Novel Linear Piezo-resistive Auxetic Meta-Sensors with Low Young's Modulus by a Core–Shell Conceptual Design and Electromechanical Modelling

Production of piezo-resistive auxetic sensors is usually carried out through mixing and coating methods. Although these methods are beneficial, Young's modulus of mixed sensors becomes high because of using a high percentage of sensing elements while the durability of coated sensors gets low due to the separation of sensing elements from the sensor surface. This article presents a new core–shell metamaterial model to address the mentioned problems. The shell and the core are produced of polydimethylsiloxane (PDMS) rubber and a mixture of PDMS/graphite powders (73.45 wt% graphite powders), respectively. A finite element model is developed via COMSOL software to predict the electromechanical behaviors of the created sensor and verified by an experimental study. Scanning electron microscope imaging is conducted to detect the separations of the graphite particles. The main important feature of this meta-sensor is to possess a linear sensitivity due to having zero Poisson's ratio. The advantage of this method is that Young's modulus of the sensor does not decrease (unlike the mixing method), and the sensor-coated particles do not separate from the sensor after a while (unlike the coating method). The introduced model has advantages that promote potential applications such as using sensory gloves to detect, for instance, human hand movements.     

Migration of Bisphenol-A into packaged food simulants: Development of a novel MAE-LDS-ME strategy for the investigation of storage time and temperature

In this research, migration of bisphenol A from epoxy resin into 64 food simulants including tuna fish cans, eggplant cans and cherries cans have been measured. The effective of storage time in the range 0–180 days and storage temperature at 25 and 45°C were investigated. Microwave-assisted extraction and low-density solvent based on microextraction followed by high-performance liquid chromatography has been applied to analyze migrated-BPA. The limit of detection 2.7 ng ml⁻¹ and limit of quantification 9.33 ng ml⁻¹ were obtained for the proposed method. The results confirmed that the migration of BPA has been increased with raising the storage time and temperature. Also, the migration of BPA in oily simulant was higher than acidic simulant. The migrated-BPA concentration range has been measured in the range 3.42–4165 ng ml⁻¹. The highest amount of migrated-BPA has been found for simulant of tuna fish cans at 45°C and the lowest amount of migrated-BPA has been detected for simulant of cherries cans at 25°C.     

Novel Linear,Piezoresistive, Auxetic Sensors Coated by AAA Battery Active Carbons with Supreme Sensitivity for Human Body Movement Detection

Herein, a novel strategy for creating low-cost, sustainable, piezoresistive auxetic sensors using the active carbon in consumed AAA batteries, promoting a circular economy, is presented. An auxetic structure with a fixed Poisson's ratio during the strain is designed for sensing. The sensor substrate is silicone RTV2, and the sensing element is the active carbon in AAA batteries chopped to microscale particles using an ultrasonic wave. The sensor mold is designed using Solidworks software and produced using a computer numerical control device and EdgeCam2014 software. The coating process is performed by spraying the prepared particles on the molded auxetic structure and putting the coated auxetic structure under ultraviolet ray to prepare the final sensor. Sensitivity tests are performed, and the results show that the proposed sensor has a better sensitivity of about 1000% and 410% than the previous mixed and layered composite auxetic counterparts. The proposed sensor has linear sensitivity during the strain (estimated with a line with a slope of 0.64) while previous ones have a nonlinear performance (estimated at least with two lines). The sustainable sensor is implemented to detect the movements of the human body, including the movements of the wrist, finger, elbow, and forearm.     

Conflict management techniques for model merging: a systematic mapping review

Software and Systems Modeling - Model merging conflicts occur when different stakeholders aim to integrate their contradicting changes that are applied concurrently to update software models. We...