1,354,210 research outputs found
Effect of corroded reinforcement in RC structures: from cracking to bond performance
No full textReinforced concrete (rc) is the most used building material. The natural ageing of the rc structures moves the attention to the durability aspect. The latter depends on the environmental conditions, which are getting always more severe, but also it depends on the poor detailing and material characteristics during casting. Hence, the deterioration of rc structures becomes a matter of primary importance. The most common cause of deterioration of rc structures is the reinforcement corrosion: it affects the steel reinforcement reducing the sectional area and modifying the mechanical properties. Moreover, corrosion provokes the concrete section loss because of the cracking induced by the expansive phenomenon; hence the resisting section is reduced and the deteriorated reinforcement is further exposed to the aggressive environment. Finally, corrosion deeply changes the characteristics of the interface layer between steel and concrete because of the oxides formation; therefore, bond between the materiala changes. In the present dissertation, steel reinforcement corrosion and its mechanical implications were studied; in particular, the investigation was developed both experimentally and numerically. As far as the former is concerned, pull-out test of corroded RILEM type specimens was performed. The experimental variables were three: the corrosion level; the main reinforcement dimension and the presence of the transversal reinforcement. The maximum corrosion level reached was 20% in terms of mass loss, this values is far greater than those available in the literature which rarely overtake the 10% of mass loss; further corrosion nominal levels were 2, 5 and 10%. The main reinforcement, whose diameter was of 12 and 16 mm, were artificially corroded by means of the application of a low density current in order to reach the nominal corrosion level with a reliable accelerated mechanism. Confined specimens were provided with closed stirrups which were corroded up to the level of the main reinforcement. During the corrosion phase, the specimens were daily soaked in a tank containing water and then stored in a humidity controlled room, those operations allowed to accomplish the wet and dry condition. The cracks were measured every 48 hours and the collected data were merged to other outcomes obtained from the literature. An interpolation curve was proposed: it is able to forecast the corrosion level starting from the crack width measure and taking into account geometrical and mechanical characteristics of the rc elements. The core of the experimental program was the pull-out test stage which allowed to obtain the bondslip curves of the specimens firstly corroded and then tested. At the end of the pull-out test, the reinforcing bars and the stirrups were extracted and the actual corrosion rates were determined. Results of the test integrate the present literature and highlighted the role of the inspected parameters. Furthermore, the outcomes were used for calibrating the numerical model. The numerical study lead to the definition of a simple and modular analytical model which allows to take into account the presence of the confinement and the corrosion products. The modelling was realized in the longitudinal and in the transversal direction: hence the model can be considered three dimensional with axial symmetry assumption. In the longitudinal modelling, the boundary value problem is solved using a local bond-stress similar to that one proposed by the MC2010. The transversal modelling was based on the thick-walled cylinder theory which allowed to determine the pressure acting at the steel to concrete interface. In this context, a softening behaviour of the cracked concrete was assumed. Transversal and longitudinal modelling were linked by means of a friction criteria whose parameter depend on the corrosion level and on the concrete tensile strength. Finally, the model was used to simulate some experimental results in the literature. Taking into account the great scatter of the outcomes from the bond test and also due to corrosion phenomenon, a good agreement between the experimental outcomes and the numerical results is observed
Spotlight on eudaimonia and depression. A systematic review of the literature over the past 5 years
No full textBackground and aim: Recent investigations pointed out to the important role of wellbeing in influencing physical and mental health, with robust findings for the dimension of depression. The aim of this systematic review is to provide an updated summary of articles focused on eudaimonia and depression, including psychosocial interventions that addressed both issues. Method: The literature search was performed by entering the keywords: “eudaimonia” OR “eudaimonic well-being (EWB)" and “depression” and by limiting to “journal article” and to the English language. To be included in this, review articles had to present at least one EWB measure and one depression measure, and had to investigate young and adult populations, including populations with mental health disorders. Articles were excluded if they were published before 2014. Results: Thirty-four articles were included, with a total of 81,987 participants. About the majority of participants were recruited in two twin studies, followed by college students, and by adults belonging to the general and clinical populations. Sixteen different instruments assessed eudaimonia, being Ryff’s psychological well-being scale the most frequently used. The most used instrument for assessing depression was the Depression Anxiety Stress Scale, followed by Center for Epidemiological Studies Depression Scale. The studies confirmed the robust, inverse correlation between eudaimonia and depression, which was only partially explained by genetic common factors and which was mediated by other factors, as selfcompassion, personality traits, and defense mechanisms. Various interventions were found to be effective both in promoting eudaimonia and in addressing depression, ranging from cognitive-behavioral therapy, acceptance and commitment therapy, mindfulness, to positive psychotherapy. Conclusion: Clinicians, counselors, and practitioners can select different strategies to promote EWB and to address depression. The findings also suggest the need for a larger consensus on the definition of eudaimonia and on the specific measure(s) to evaluate it in different populations and in different life stages
Nuevas estrategias de consumo de la Economía Social y Solidaria.
No full textFil: Henriquez Acosta, María Dulce. Universidad Nacional de Río Negro. Centro Interdisciplinario de Estudios sobre Territorio, Economía y Sociedad (CIETES). Río Negro, Argentina.Fil: Cesetti Roscini, Mauro. Universidad Nacional de Río Negro. Río Negro, Argentina.Fil: Cesetti Roscini, Mauro. Universidad Nacional de la Patagonia San Juan Bosco. Esquel, Chubut.El escenario de aislamiento social obligatoria generado a raíz de la pandemia, reinstala lo que desde hace tiempo plantea el enfoque de soberanía alimentaria (y no sólo alimentaria): la atención de las necesidades territoriales a partir de las propias capacidades locales
Waste processing: New near infrared technologies for material identification and selection
No full textThe awareness of environmental issues on a global scale increases the opportunities for waste handling companies. Recovery is set to become all the more important in areas such as waste selection, minerals processing, electronic scrap, metal and plastic recycling, refuse and the food industry. Effective recycling relies on effective sorting. Sorting is a fundamental step of the waste disposal/recovery process. The big players in the sorting market are pushing for the development of new technologies to cope with literally any type of waste. The purpose of this tutorial is to gain an understanding of waste management, frameworks, strategies, and components that are current and emerging in the field. A particular focus is given to spectroscopic techniques that pertains the material selection process with a greater emphasis placed on the NIR technology for material identification. Three different studies that make use of NIR technology are shown, they are an example of some of the possible applications and the excellent results that can be achieved with this technique
Observational constraints to the stellar populations in the center of galactic spheroids
No full textGalactic spheroids represent one of the key challenges to our understanding of galaxies formation and evolution as far as their star-formation history is concerned. The knowledge of the stellar content of early-type galaxies is fundamental to understand their star formation and chemical evolution. The thesis is focused on two main topics, both concerned with the study of unresolved stellar populations in the centers of galaxies. The first one is a comprehensive study of the photometrical properties of three galaxies that belong to the Virgo Cluster and host Nuclear Stellar Disks (NSD) in their centers. The second one is focused on the study of absorption lines in the Near-infrared (NIR) that are strictly correlated with the properties of the stellar populations. I defined new NIR spectral indices that show great potential for a stellar population analysis. A simple SSP model is created to interpret the integrated NIR light. The development of the SSPs model pointed out at some limitations of the currently available stellar spectral libraries. Consequently, the study of metal poor red supergiant stars in the NIR was carried out.Gli sferoidi galattici rappresentano uno dei punti chiave per comprendere la formazione e l'evoluzione delle galassie, sopratutto per quanto riguarda la formazione stellare. Infatti, conoscere il contenuto stellare delle galassie early-type fornishe importanti indicazioni sulla formazione e l'evoluzione chimica delle loro stelle. Due sono gli argomenti trattati in questa tesi entrambi connessi con lo studio delle popolazione stellari non risolte nel centro delle galassie. Il primo studia dettagliatamente le proprietà fotometriche di tre galassie appartenenti all'ammasso della Vergine che ospitano un disco stellare nel loro nucleo. Il secondo mira ad individuare le righe spettrali fondamentali per lo studio delle popolazioni stellari nel vicino infrarosso (NIR). I nuovi indici spettrali definiti nel NIR hanno dimostrato essere notevolmente efficaci per l'analisi delle popolazioni stellari. Un semplice modello di popolazione stellare semplice (SSP) è stato creato per interpretare la luce integrata nel vicino infrarosso. Lo sviluppo del modello SSP ha messo in evidenza alcuni limiti delle librerie stellari spettrali oggigiorno disponibili. Pertanto è stato studiato lo spettro di alcune stelle supergiganti rosse a bassa metallicità nel NIR
Smart reinforcement steel bars with low-cost MEMS sensors for the structural health monitoring of RC structures
No full textPerception and sensor fusion for flying and mobile robot
No full textdelle superfici artificiali della terra, ma non possono percepire l’ambiente circostante come gli esseri umani e altri animali. La percezione è qualcosa di più del rilevare dati. La percezione comprende l'interpretazione dei dati rilevati in modo significativo. Uno dei compiti più importanti di un sistema autonomo di qualsiasi tipo è quello di acquisire la conoscenza del suo ambiente. Questo viene fatto acquisendo misure con i vari sensori e quindi estraendo informazioni significative da tali misure.
Questa tesi inizia con una discussione di questa problematica con la descrizione delle prestazioni dei sensori per la robotica mobile. Presenta molti dei sensori a disposizione della robotica mobile e ne descrive i principi basilari di funzionamento, nonché i loro limiti di prestazioni. Descrive inoltre le strategie per l'estrazione di feature, particolarmente utilizzate in applicazioni di robotica mobile, compresa l'estrazione di forme geometriche a partire da dati rilevati di tipo range-based, nonché l’individuazione di landmark e l'analisi whole-image basata su dati di tipo visivo.
Dal momento che il sensore di visione è il più promettente per il futuro della robotica mobile, questo lavoro comprende una panoramica della teoria di funzionamento e delle limitazioni dei dispositivi di visione artificiale e comprende considerazioni sulle tecniche e le tecnologie per la robust mobility.
La tesi esplora i temi fondamentali nella percezione dei robot e propone soluzioni innovative per una navigazione efficace e sicura di robot mobili in ambienti indoor e outdoor. In particolare esamina il problema della navigazione basata sulla visione per veicoli aerei. Sono presentati diversi approcci alla percezione basata sulla visione, che riguardano principalmente l'aspetto della localizzazione. Tutte le tecniche introdotte in questa tesi sono state ampiamente validate su robot reali per garantire la robustezza delle soluzioni proposte
A Vision-based guidance system for UAV navigation and safe landing using natural landmarks
No full textIn this paper a vision-based approach for guidance and safe landing of an Unmanned Aerial Vehicle (UAV) is proposed. The UAV is required to navigate from an initial to a final position in a partially known environment. The guidance system allows a remote user to define target areas from a high resolution aerial or satellite image to determine either the waypoints of the navigation trajectory or the landing area. A feature-based image-matching algorithm finds the natural landmarks and gives feedbacks to an onboard, hierarchical, behaviour-based control system for autonomous navigation and landing. Two algorithms for safe landing area detection are also proposed, based on a feature optical flow analysis. The main novelty is in the vision-based architecture, extensively tested on a helicopter, which, in particular, does not require any artificial landmark (e.g., helipad). Results show the appropriateness of the vision-based approach, which is robust to occlusions and light variations
Smart reinforcement steel bars embedded with low-cost MEMS sensors for strain monitoring
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