Propagation of Elastic Waves in Homogeneous Media: 2D Numerical Simulation for a Concrete Specimen

This paper addresses the theoretical foundation of a localization method for crack detection in a concrete sample based on the time of arrival of the elastic wave generated by the crack formation to a group of sensors positioned on the boundary of the sample. The equations of motion for the elastic waves are carefully presented, including a body force term which accounts for the sudden formation of a crack. Then, a localization method based on the detection of acoustic emissions, and specifically on their arrival times, is described. Finally, a discretization scheme for the 2D equations of elasticity is developed, and some numerical experiments are performed to assess the validity of the method

Experimental evaluation of the adhesion of a FRCM-tuff strengthening system

Abstract Nowadays, the use of innovative materials for the reinforcement of existing buildings are the most used technological solutions. Several reinforcement systems are available currently on the market and different research groups dealt with them from experimental point of view; these systems differ both in the reinforcing fibers used and the type of matrix applied. The most common reinforcement systems are those based on polymer matrix (FRP) provided by criteria and design rules consolidated in the application field for both new and existing buildings. In recent years scientifically-based cement matrix reinforcement systems (FRCM) are been used and experimented in the field of existing constructions. Unfortunately, there are currently no guidelines for qualification, as well as design criteria and application rules. It is a completely different reinforcement system compared to the common FRP reinforcements, in fact the cement matrix has a different mechanical behavior when applied to masonry supports. The mechanical behavior, already investigated by numerous authors, highlights the advantages that can be obtained with respect to a traditional reinforcement system. The aspect that still needs to be analyzed and studied is the adhesion between the existing support and the FRCM reinforcement system. In the present work, the attention is focused on the adhesion of a FRCM-tuff reinforcement system; for this purpose, experimental tests were carried out at the Materials and Structural Testing Laboratory of the Civil Engineering Department of the University of Calabria. The specimens consist of blocks of tuff, as regards the support, while the applied FRCM reinforcement system is based on basalt fibers and cement matrix. All results were compared with those obtained from previous research using other support materials and reinforcing fibers

experimental and analytical analysis on a masonry arch strengthened with basalt frcm

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The development and application of an optimization tool in industrial design

AbstractDesigners are identified, in industry 4.0, as the professional figures that have to design well performing new object. In order to do this, it is necessary to take into account a series of properties called design objectives. Often the structural problem of new design is underestimated or even not considered. This can be a real problem because this objective is in competitive and in contrast with other design objectives. So, this can bring to substantial change in a design in the final phase and sometimes to the complete change. In this paper is presented an optimization workflow that adopt a Multi Objective Optimization engine so called "Octopus" and Karamba3D, that is a Finite Elements (FE) plug-in, typically used in structural simulations, these extensions run in a software: Grassopper3D, that is a parametric design tool. The workflow allows designers to explore a large range of solutions and at the same time permits to filter and sort the optimized models in order to analyze the tradeoff of the resultant solution space, both qualitatively and quantitatively. In such way designers can obtain easily a lot of information of the generate design and identify potential solution for immediate use or for further optimization. In this paper is analyzed a design problem of an ergonomic chair in order to provide the efficiency of the workflow. The design criteria and the structural problem for this type of design object are identified as the main optimization objectives in order to iteratively improve the design solutions

A social robot connected with chatGPT to improve cognitive functioning in ASD subjects

Neurodevelopmental Disorders (NDDs) represent a significant healthcare and economic burden for families and society. Technology, including AI and digital technologies, offers potential solutions for the assessment, monitoring, and treatment of NDDs. However, further research is needed to determine the effectiveness, feasibility, and acceptability of these technologies in NDDs, and to address the challenges associated with their implementation. In this work, we present the application of social robotics using a Pepper robot connected to the OpenAI system (Chat-GPT) for real-time dialogue initiation with the robot. After describing the general architecture of the system, we present two possible simulated interaction scenarios of a subject with Autism Spectrum Disorder in two different situations. Limitations and future implementations are also provided to provide an overview of the potential developments of interconnected systems that could greatly contribute to technological advancements for Neurodevelopmental Disorders (NDD)

Propagation of Elastic Waves in Homogeneous Media: 2D Numerical Simulation for a Concrete Specimen

This paper addresses the theoretical foundation of a localization method for crack detection in a concrete sample based on the time of arrival of the elastic wave generated by the crack formation to a group of sensors positioned on the boundary of the sample. The equations of motion for the elastic waves are carefully presented, including a body force term which accounts for the sudden formation of a crack. Then, a localization method based on the detection of acoustic emissions, and specifically on their arrival times, is described. Finally, a discretization scheme for the 2D equations of elasticity is developed, and some numerical experiments are performed to assess the validity of the method

On a One-Dimensional Hydrodynamic Model for Semiconductors with Field-Dependent Mobility

We consider a one-dimensional, isentropic, hydrodynamical model for a unipolar semiconductor, with the mobility depending on the electric field. The mobility is related to the momentum relaxation time, and field-dependent mobility models are commonly used to describe the occurrence of saturation velocity, that is, a limit value for the electron mean velocity as the electric field increases. For the steady state system, we prove the existence of smooth solutions in the subsonic case, with a suitable assumption on the mobility function. Furthermore, we prove uniqueness of subsonic solutions for sufficiently small currents

Post-Cracking FRCM Strengthening of an Arch Composed by Hollow Clay Elements Embedded in Mortar: Experimental Investigations and Numerical Analyses

The use of hollow clay elements (fictile tubules, amphorae and caroselli) for erecting arches, vaults and domes was a building technique very popular in the Mediterranean area from the Roman Empire on. It was devised to ensure lightness and thermal insulation of structural elements. This paper presents experimental investigations and some preliminary numerical analyses regarding an arch consisting of caroselli embedded in mortar. A full-scale laboratory model was constructed and subject to vertical loads. After the development of hinges, the arch was repaired and strengthened with FRCM strips and further loads were applied to investigate the post-strengthening mechanical behavior. Also, numerical models of caroselli and mortar are created in Abaqus. Then, an elementary cell comprised of caroselli and mortar is created. The mechanical properties of the cell are evaluated by studying its behavior under uniaxial tensile and compressive loads. These properties set the basis for a possible homogenized material which can be used for numerical analyses of the arch

Fictile tubules: A traditional Mediterranean construction technique for masonry vaulted systems

The historical centres of many Italian cities are integral parts of the Country's cultural heritage, and guaranteeing their conservation over time is paramount. Many constructions are characterised by building techniques that are not well-known and still have to be studied. In particular, one technique involving the use of clay fictile tubules is here examined through historical studies, experimental characterisation and numerical investigations. This technique is typical of the Mediterranean area and Southern Italy, and dates back to Roman and early Christian times; three different types of elements were usually employed (tubules, amphorae and caroselli). Walls, domes and vaulted structures with different geometries were built with this technique, which allowed for the creation of modular construction elements in potteries. Relevant historical building issues are first addressed in detail, then a comprehensive experimental investigation on the constitutive materials (caroselli and mortar) is presented, provided with a series of numerical simulations aimed at validating the experimental results. Eventually, the composite material consisting of caroselli and mortar is investigated through a homogenisation approach, allowing its mechanical characterisation through the evaluation of equivalent homogenised material properties. They are derived through the investigation of an analytical elementary cell, subject to uniaxial tension and compression, which enables to derive homogenised constitutive laws. These are validated by comparing experimental data obtained from compressive tests performed on three real elementary cells with numerical results gathered from the use of such homogenised properties on an equivalent cell

Automatic crack classification by exploiting statistical event descriptors for Deep Learning

In modern building infrastructures, the chance to devise adaptive and unsupervised data-driven health monitoring systems is gaining in popularity due to the large availability of big data from low-cost sensors with communication capabilities and advanced modeling tools such as Deep Learning. The main purpose of this paper is to combine deep neural networks with Bidirectional Long Short Term Memory and advanced statistical analysis involving Instantaneous Frequency and Spectral Kurtosis to develop an accurate classification tool for tensile, shear and mixed modes originated from acoustic emission events (cracks). We investigated on effective event descriptors to capture the unique characteristics from the different types of modes. Tests on experimental results confirm that this method achieves promising classification among different crack events and can impact on the design of future on structural health monitoring (SHM) technologies. This approach is effective to classify incipient damages with 92% of accuracy, which is advantageous to plan maintenance.Comment: 19 pages, 2 tables, 9 figure