1,720,962 research outputs found
Effectiveness of slab stabilization in mitigating reflective cracking in HMA overlays: a case-history
No full textSlab stabilization is the pressure insertion of a flowable material beneath a concrete slab, in order to restore slab support. The application of such a technique can pose some problems. Therefore, an experimental study has been performed on the start of the runway (turnaround bay) of an Italian airport in order to assess the real capability of different types of slab stabilization techniques to rehabilitate the needed bearing properties. Crack surveys, deflection tests by the FWD and traditional plate bearing tests on the subgrade have been performed prior and after the four types of interventions in order to evaluate the structural effects at the centre, at joints and corners of slabs. The obtained results are useful in assessing the different capability of such rehabilitation strategies to optimise bearing properties and allow to identify the effect in mitigating reflective cracking in asphalt overla
Augmented Information Discovery using NFC Technology within a Platform for Disaster Monitoring
No full textCatastrophic and accidental natural events (e.g., earthquakes, sudden floods, fires, etc.) and deficiencies in appropriate management activities require proper plans for disaster management and real-time definition of safe paths and escape routes. Emergencies can affect the structural health status of structures and infrastructures and, consequently, the safety in highly populated areas (e.g., urban contexts, occasional assembly points for crowds, theme parks, etc.) is compromised. Consequently, the use of a decision platform for the management of structures and infrastructures, which is able to gather real-time data from sensors and provide alerts and augmented information about safe paths, paves the way to the adoption of a proactive form of risk management. In this work, objectives were confined into the validation of a Near-Field Communication (NFC) system. Data coming from user smartphones using the NFC technology and sensor data deriving from the decision platform were used as input in a Machine Learning (ML) algorithm. Results show that the ML algorithm mentioned above is able to refine the safe path recognition strategy defined from the platform. In addition, the bidirectional and touch less NFC technology allows the delivery of alerts and disaster plan dissemination, also in the case of connectivity shutdown
Machine Learning techniques applied to Road Health Status Recognition through Tyre Cavity Noise Analysis
Get PDFThis paper proposes a system based on Neural Networks (NN), designed for providing an efficient, non-invasive and automated method for monitoring the health status of road pavements by using features derived from Tyre Cavity Noise (TCN) analysis. Indeed, visual inspection remains to date the most common choice for evaluating the condition of road pavements; however, this method is both labor intensive and time consuming. The system presented in this work uses a microphone placed inside the vehicle tyre that measures TCN while travelling normally, and an embedded data acquisition system based on a Raspberry Pi which feeds the NN tools to recognize and classify road deterioration. We also present a preliminary analysis of features based on temporal and spectral characteristics of TCN signals generated by tyre/road interaction and acquired on three different kind of road distresses. The results show good classification capability and, moreover, the sound pressure measured inside the tyre was correlated accelerometric data measured on-board
Damage detection into road pavements through acoustic signature analysis: First results
No full textEfficient civil infrastructure management strictly depends on Structural Health Monitoring (SHM). Several studies have been conducted on the SHM of civil engineering constructions through the application of a large number of methods, which widely differ based on theory applied and technology used. The aim of this work is to describe the preliminary results of a new acoustic method for road pavement SHM. The proposed method is based on the idea of monitoring the time behaviour of the spectral content of acoustic signals recorded from road pavements under vehicular traffic. The spectral content of the recorded signals is considered as the acoustic signature of the road pavement under investigation. It provides information about the structural health condition of the pavement. Preliminary results were obtained considering asphalt concrete slabs. They show a correlation between the health conditions of the slabs (which were expressly damaged in different ways) and their acoustic signatures (recorded acoustic signals). Based on these preliminary results, further in situ measurements and analyses on road pavements will be carried out and different structural health conditions will be considered. Results can benefit both practitioners and researchers
A real-time decision platform for the management of structures and infrastructures
No full textNatural disasters and the poor management of civil engineering structures and infrastructures require timely action and new tools such as specially designed structural health monitoring platforms. This paper proposes an innovative platform based on a network of wirelessly connected, low-power, and renewable-energy-fed sensor units. The platform is a multipurpose tool for diagnostics, maintenance, and supervision, capable of simultaneously carrying out damage detection, localization, identification, and “multiclass” and “multi-material” level quantification of different types of failures. In addition, it works as a decision support tool for emergency management and post-disaster assessment, here tailored for an Italian theme park. The platform uses innovative algorithms based on the concept of the vibro-acoustic signature of the asset monitored. The vibro-acoustic signatures of the monitored assets are gathered by the microphones and accelerometers of the platform’s sensor units. Then, almost simultaneously, they are analyzed using specifically designed wavelet-based and convolutional-neural-network-based algorithms, which are able to extract crucial information about the structural and environmental conditions of both the asset and the areas of the thematic park. In addition, the platform shows escape routes during an emergency, indicating meeting points and helping people to proceed safely along a recognizable escape route to a safe place, as demonstrated by the simulations
The LIFE SILENT Project's approach to sustainable noise mitigation
No full textThe main objective of the LIFE SILENT project is the development of sustainable and eco-friendly solutions to mitigate noise in complex urban environments, where multiple and diverse noise sources, mainly roads and railways, coexist across densely populated areas. Mitigating noise in such environments generally excludes the use of solutions that might interfere with the urban context, such as high noise barriers. This is mainly due to the proximity of receivers to the noise source, which reduces the visibility of the surroundings and air circulation, leading to microclimatic modifications and social opposition. This is why noise mitigation measures acting directly on the source are recommended, such as low-noise pavements for roads, and dampers, rail grinding, and silent brakes for railways. However, these solutions suffer from either durability issues or high implementation costs. Thus, an improvement is necessary. In the LIFE SILENT project, innovative and sustainable low-noise and long-lasting pavements, as well as low-height noise barriers, will be developed and demonstrated in a real test environment. Additionally, procedures will be established to facilitate their synergistic implementation, providing transport infrastructure owners and managers with solid information to support their widespread adoption. In this paper, a general overview of the LIFE SILENT project is given
Sensing road pavement health status through acoustic signals analysis
No full textTraffic produces seismic and acoustic waves. These waves affect both bystanders and civil infrastructures in terms of health issues and of complication in the maintenance, rehabilitation, assessment and monitoring processes, respectively. Therefore, it is increasingly important to reduce, or at least to monitor these annoyances through methods that are capable to take advantage of the potentialities offered from new technologies. The aim of this study is to present the preliminary results of the application of a new method for the monitoring the traffic-induced vibrations and noise, and for the assessment of the health conditions of road pavements. This method can be classified as an acoustic method because it is based on the concept of acoustic signature, defined in this work as the spectral content of the acoustic signals coming from the road pavement under vehicular traffic condition. The estimation of variation over time of this signature provides important information about the changes of the response of roads to the traffic, i.e. about their structural health conditions. In this preliminary stage, acoustic signals were detected through a sensor placed in a hole drilled both in un-cracked and cracked slabs of asphalt concrete, during accelerated loading in-lab tests (EN 12697-22:2007). Simultaneously, these signals were sampled and processed in order to carry out the acoustic signature of the slab under test. Results show the possibility of developing a new acoustic method that allows estimating the structural health condition of a road pavement from its acoustic signature
Going Beyond Counting First Authors in Author Co-citation Analysis
Get PDFThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
Variations on the Author
Get PDF“Variations on the Author” discusses two of Eduardo Coutinho’s recent films (Um Dia na Vida, from 2010, and Últimas Conversas, posthumously released in 2015) and their contribution to the general question of documentary authorship. The director’s filmography is characterized by a consistent yet self-effacing form of authorial self-inscription: Coutinho often features as an interviewer that rather than express opinions propels discourses; an interviewer that is good at listening. This mode of self-inscription characterizes him as an author who is not expressive but who is nonetheless markedly present on the screen. In Um Dia na Vida, however, Coutinho is completely absent form the image, while Últimas Conversas, on the contrary, includes a confessional prologue that moves the director from the margins to the center of his films. This article examines the ways in which these works stand out in the filmography of a director who offers new insights into the notion of cinematic authorship
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