Politecnio die Bari - Catalogo di prodotti della Ricerca
Not a member yet
36616 research outputs found
Sort by
Geomatics Approaches for Detecting Floating Macroplastic Litter: The Res4Seal Project
No full textPlastic pollution along coastlines is one of today’s most pressing environmental issues. The resilience of plastic, coupled with its ubiquitous use, allows it to persist in marine environments for years, posing a threat not only to marine life but also to human health through the seafood consumption. While traditional methods like in-situ surveys can help monitor this pollution, they are time-consuming, expensive, and limited in scope. Fortunately, remote sensing technology offers a more efficient, large-scale solution for detecting plastics in our oceans. However, this approach still faces challenges such as atmospheric interference and limitations in resolution. To tackle this issue, the ReS4Seal project was developed, using advanced geomatic techniques to detect plastic debris both in the water and along the shoreline. For plastics floating in the sea, a three-tier classification model was created, leveraging Sentinel-2 satellite images combined with the Floating Debris Index, the Normalized Difference Vegetation Index, and the Otsu filter to automatically identify macroplastics. Meanwhile, high-resolution photogrammetric images from Remotely Piloted Aircraft Systems were used to detect shoreline plastics, producing detailed orthophotos that allowed for precise mapping and classification of plastic debris. The results show that these methods are not only effective in locating and tracking macroplastic pollution but also offer a standardized approach, using a 1x1 meter grid, which facilitates consistent data collection for future monitoring efforts. Additionally, spectral analysis of the high-resolution RGB orthophotos confirmed their potential for distinguishing different types of plastic waste. Overall, these innovative techniques provide a promising path forward in our fight to manage plastic pollution and protect our coastal ecosystems
An Approach to Growth Mechanics Based on the Analytical Mechanics of Nonholonomic Systems
No full textMotivated by the convenience, in some biomechanical problems, of interpreting the mass balance law of a growing medium as a nonholonomic constraint on the time rate of a structural descriptor known as growth tensor, we employ some results of analytical mechanics to show that such constraint can be studied variationally. Our purpose is to move a step forward in the formulation of a field theory of the mechanics of volumetric growth by defining a Lagrangian function that incorporates the nonholonomic constraint of the mass balance. The knowledge of such Lagrangian function permits, on the one hand, to deduce the dynamic equations of a growing medium as the result of a variational procedure known as Hamilton-Suslov Principle (clearly, up to non-potential generalized forces that are accounted for by extending this procedure), and, on the other hand, to study the symmetries and conservation laws that pertain to a given growth problem. While this second issue is not investigated in this work, we focus on the first one, and we show that the Euler-Lagrange equations of the considered growing medium, which describe both its motion and the evolution of the growth tensor, can be obtained by reformulating a variational method developed by other authors. We discuss the main features of this method in the context of growth mechanics, and we show how our procedure is able to improve them
The evaluation of the adhesion defects in FRCM reinforcements for masonry constructions by Sideband Peak Count based nonlinear acoustic technique
No full textFabric-reinforced cementitious matrix (FRCM) composites have emerged as reliable strengthening materials especially for historical masonry constructions. Their strengthening effectiveness strongly depends on the bond at the matrix-fibers interface and at the matrix-substrate interface; thus, the analysis of FRCM bond behavior is of crucial relevance. The strong diffusion of the FRCM composites for the reinforcement of masonry and concrete constructions requires suitable experimental techniques for assessing possible defects in the adhesion between FRCM and masonry, and between FRCM layers. To this aim, in this paper, an innovative nonlinear ultrasonic approach based on the sideband peak count technique is proposed. This approach is discussed and validated through acoustic (sonic and ultrasonic) tests performed on masonry tuff substrates reinforced with FRCM mortars embedding a basalt fibers grid and having known artificial defects at the adhesion between masonry and the reinforcement as well as in the fiber grid
Development of in-situ optical sensor-based monitoring methodologies for Additive Manufacturing processes
Get PDFProcess monitoring has proven to be essential in manufacturing fields, where quality and precision are paramount. The introduction of AM techniques has enabled the production of complex parts but has also increased the complexity of manufacturing systems. This has led to the demand for monitoring systems able to provide significant information about the process while it is running as well as give real-time insights to detect and prevent, when possible, process anomalies. Reliable monitoring systems provide a window into the process dynamics, allowing for process parameters adjustment that could maintain product quality and reduce waste of materials and energy. Despite the numerous advantages introduced by monitoring systems, widespread traditional solutions remain limited, prompting significant effort from researchers and industries in this direction. This thesis addresses the current critical gaps in terms of monitoring purposes by proposing innovative and cost-effective in-situ optical-based monitoring methodologies for three key AM processes: Material Extrusion Additive Manufacturing, Laser Powder Bed Fusion and Direct Energy Deposition. Material Extrusion showed to be lacking adequate metrics able to describe the process, together with the absence of solutions exploiting profilometers as monitoring sensors. The monitoring activities on L-PBF were driven by the lack of robust monitoring systems able to characterize lattice structures. Finally, the monitoring activities on L-DED were led by the current absence of real-time monitoring system capable of monitoring more than one direction, since the majority of the system focused on single direction thin wall monitoring. First, two layerwise monitoring approaches for MEX, based on a high-resolution blue laser line profilometer embedded within a consumer grade MEX printer, were presented to characterize the surface quality, to detect defect occurrence layer-by-layer and to expand the metrology field related to the MEX process, which is currently lacking, by proposing new metrics. The three proposed quality indexes (ADLH, RAD and slope s) proven to be representative of the layer height accuracy, the occurrence and distribution of surface defects, such as over/under-fill, and, also, the process stability respectively. In the second approach, functional analysis tools were successfully used to detect, localize, and characterize the topology of common surface defects caused by over-extrusion and under-extrusion conditions. An optical-based monitoring procedure was also developed and applied for layerwise in-situ monitoring of complex geometries produced by L-PBF through a tailor-made image processing algorithm. Based on High-Resolution Optical Tomography (HR-OT), this procedure effectively detected geometric distortions and, at the end of the process, provided a 3D reconstruction of the lightweight structure suitable for post-process quality assessment. Finally, a preliminary study on a cost-effective off-axis dual-camera real-time 3D monitoring method for L-DED process was conducted. The aim was to enable a reliable measure of the melt pool height regardless of the laser head scanning direction. Results showed that the proposed methodology was able to provide acceptable melt pool height measures for all the scanning direction tests. By introducing robust process signatures and defect metrics, this work significantly advances the metrology of AM processes. The comprehensive monitoring methodologies developed during the research activities not only improve in-process quality evaluation and process stability but also pave the way for real-time, closed-loop corrective actions
Il porto teatroide. Metodi e tecniche per la riforma della città-porto mediterranea = Port as theater. Methodologies and techniques for the renovation of the mediterranean port city
No full textLa città-porto è nella sua forma costitutiva l’esito di una relazione, che si è definita e riformulata nei secoli, a seconda del carattere di permeabilità e dipendenza, o viceversa, di distacco e indifferenza, tra le due diverse parti che la compongono.
I porti del Mediterraneo a differenza degli altri porti europei che hanno dismesso, delocalizzato e riconvertito ad uso urbano interi quartieri e parti urbane, convivono ancora oggi in una condizione di sovrapposizione con la città consolidata. Il porto, nei limiti imposti della morfologia costiera, è interno al corpo della città, finanche nella sua dimensione territoriale contemporanea.
Questo fenomeno, esito di un lungo processo di stratificazione di usi nel tempo, assieme alle difficoltà a riconoscere le parti di un “tutto” eterogeneo, fatto di pieni e vuoti, spazi abitati e spazi abbandonati, causa l’indeterminatezza della modalità trasformative del territorio delle città-porto mediterranee. Allo stesso tempo, offre le opportunità di riflettere su un’alternativa ai metodi di costruzione della città portuale.
Lo specchio d’acqua, che definisce i limiti territoriali del porto, si è trasformata oggi in superficie infrastrutturale, unico medium in grado di tenere funzionalmente assieme delle diverse parti e sezioni portuali. Il vuoto naturale d’acqua, potrebbe aprirsi a nuove interpretazioni, costituendosi come l’intervallo necessario al riconoscimento degli ambiti portuali e del loro dialogo con gli elementi cardine della città.
Un rapporto chiaramente espresso nei porti mediterranei del passato, che si fondava sul carattere di visibilità, e sulla costruzione di una scenografia: circoscritta dai limiti fisici geografici e che aveva per punto di vista, la rappresentazione della città dal mare.
All’interno di questo contesto operativo, si inserisce la presente tesi di ricerca dottorale, che ha inteso indagare la “formatività” di un’idea di città-porto che potesse esprimere una sintesi tra la qualità di un progetto unitario e la molteplicità e complessità di attività e funzioni legate al microcosmo portuale.
Per fare ciò, risulta necessario rifondare il punto di vista sulle città portuali, in una prospettiva che superi la “cecità” (espressa negli interventi degli ultimi decenni) della visione dicotomica ed escludente, tra area portuale ed area urbana. Quindi modificare i processi di conoscenza, prima ancora delle forme di intervento.
L’interesse della ricerca è stato rivolto alla descrizione e analisi dei caratteri fondativi della città-porto mediterranea. A partire da una riscoperta degli aspetti identitari delle eccezionalità geografiche, costituite dai porti naturali. Allo stesso modo, ed in forma complementare, si è provato ad elencare e interpretare le “forme tecniche” artificiali che popolano, stratificatesi nel tempo, lo spazio portuale contemporaneo.
Le forme fisiche dell’approdo condizionano fortemente le strutture formali e le disposizioni delle attività del porto; tanto quanto le forme artificiali influenzano la conformazione delle parti di città in prossimità della linea di riva ed interi brani di paesaggio.
Un obiettivo centrale per la ricerca è stata la messa a punto di un metodo che indagasse sulle modalità trasformative, in grado di suggerire categorie, e risposte, adeguate.
È stato sviluppato un atlante interpretativo di alcune esperienze progettuali, svolte negli ultimi decenni, che possano costituire “buone pratiche” ai fini della valorizzazione della relazione tra porto e città. Un abaco che mira alla traduzione delle “tecniche” progettuali, dotate di valore generale, e quindi applicabili a diversi contesti, componendo un “toolkit” destinato agli attori dei processi rigenerativi.
Il carattere di innovatività che propone questa ricerca, precisando il campo di indagine rispetto all’intero bacino del Mar Mediterraneo, consiste nell’uso di rinnovate metodologie progettuali, che mettono al centro il valore di sistema e il ruolo che ha la forma architettonica nella definizione dell'identità degli spazi.
Un metodo alla base sia del lavoro critico-analitico, che delle sperimentazioni sul progetto, concretizzatosi in una proposta di intervento sul porto di Bari.The port-city is the result of a relationship, which has been defined and reformulated over the centuries, depending on the character of permeability and dependence, or vice versa, detachment and indifference, between the two different parts that compose it.
Mediterranean ports, unlike other European ports that have decommissioned, relocated and converted entire neighborhoods and urban parts to urban use, still coexist today in a condition of overlap with the consolidated city. The port, within the limits imposed by coastal morphology, is internal to the body of the city, even in its contemporary territorial dimension.
This phenomenon, result of a long process of stratification of uses over time, together with the difficulties in recognizing the parts of a heterogeneous "whole", made of full and empty spaces, causes the indeterminateness of the transformation of the Mediterranean port cities. At the same time, it offers opportunities to reflect on alternative methods of building a port city.
The body of water, that defines the territorial limits of the port, is transformed today in infrastructural surface, as a medium able to keep functionally together the different harbour sections. The “natural void” of water, could open to new interpretations, constituting as the necessary interval for the recognition of port areas, and their dialogue with the key elements of the city.
A relationship clearly expressed in the Mediterranean ports of the past, which was based on the character of visibility, and on the construction of a scenography: circumscribed by geographical physical limits and that had for point of view, the representation of the city from the sea.
Within this operational context, the present doctoral research thesis, which aimed to investigate the "formativity" an idea of a city-port that could express a synthesis between the quality of a unitary project and the multiplicity and complexity of activities related to the port microcosm.
To do this, it is necessary to refound the point of view on port cities, in a perspective that overcomes the "blindness" (expressed in the interventions of recent decades) of the dichotomous and exclusive vision, between port area and urban area. Then modify the processes of knowledge, even before the forms of intervention.
The research interest was directed to the description and analysis of the founding characteristics of the Mediterranean port city. Starting from a rediscovery of the identity aspects of geographical exceptionalities, constituted by natural ports. In the same way, and in a complementary form, we tried to list and interpret the artificial "technical forms" that populate, stratified over time, the contemporary port space.
The physical forms of the landing strongly condition the formal structures of port activities; as much as the artificial forms influence the conformation of the parts of city in proximity to the shore line and whole pieces of landscape.
A central focus of the research was to develop a method that would investigate transformative modes, suggesting appropriate categories and responses.
An interpretative atlas of some project experiences, carried out in recent decades, has been developed, that can constitute "good practices" for the purpose of enhancing the relationship between port and city.
An “abacus” that aims to translate the "techniques" of design, endowed with general value, and therefore applicable to different contexts, composing a "toolkit" intended for the actors of regenerative processes.
The innovative nature of this research, specifying the field of investigation in relation to the entire Mediterranean basin, consists in the use of new design methodologies, that focus on the value of architectural form in defining the identity of spaces.
A method at the basis of both critical-analytical work, and experiments on the project, which has been materialized in a proposal for intervention on the port of Bari
Treatment of concrete waste from construction and demolition activities: Application of organic acids from continuous dark fermentation in moving bed biofilm reactors
No full textConcrete construction and demolition waste (CDW) treatment and disposal is often complicated and expensive. The recourse to bioleaching processes, able to weaken the concrete CDW leading to a decrease in its weight and volume could play a key role to increase the effectiveness of the treatment, making possible the recovery of valuable substances, such as aggregates and calcium-based compounds. This paper presents the result of an experimental study aimed at testing concrete CDW bioleaching, using volatile fatty acids (VAFs) generated by a continuous dark fermentation (DF) processe, conducted in a moving bed biofilm reactor (MBBR) under different operating conditions. Bioleaching tests are conducted on ∼25 g concrete blocks with VFA mixtures obtained operating the reactor varying the pH value from 6.0 to 4.0. Best results, in terms of concrete dissolution, are obtained at pH 5.5 (weight loss 30 % and bio-hydrogen production 0.90 L/d) and 5.0 (weight loss 32 % and bio-hydrogen production 0.58 L/d). The main objective of the study include the evaluation, as performance indicators, of concrete waste debris weight and volume reduction, and bio-hydrogen and VFAs production. Further development of this technique will enable testing its applicability on a pilot scale and enhance understanding of its environmental impact, establishing the groundwork for more sustainable and efficient CDW management. This innovative approach aims to mitigate the environmental impact of CDW and offers a new pathway for resource recovery
Shear characterization in soft polyurethane foams: A critical comparison among experimental approaches
No full textThe study addresses the lack of standardization for the evaluation of the shear properties of hyperelastic soft foams. The results of three different standards used for sandwich structures or rigid materials (ASTM C 273, BS 4370, ASTM D 5379) are compared using specimens with different geometries and aspect ratios. Displacements are captured using Digital Image Correlation applying texture correlation and an incremental approach on three flame-retardant foams with densities around 85, 63, and 46 kg/m3. The study examines secondary effects like bending moments and normal stresses, finding the Iosipescu method effective for hyperelastic foams, ensuring minimal material wastage and test repeatability
Interactive mixed reality widgets for precise dexterity of tool manipulation to enhance surgical procedures in Industry 4.0 realm
No full textLe procedure mediche complesse, in particolare quelle che coinvolgono interventi chirurgici, richiedono una precisione eccezionale nella manipolazione degli strumenti spaziali a 6DOF (Sei Gradi di Libertà), dove anche errori minimi possono causare danni irreversibili o risultati indesiderati. In questo contesto, l’allineamento preciso degli strumenti è cruciale, sia nelle chirurgie minimamente invasive che in procedure delicate come l'implantologia dentale. La tecnologia della Realtà Mista (MR) è emersa come uno strumento promettente per affrontare queste sfide, fornendo ai chirurghi una guida spazialmente accurata in tempo reale attraverso risorse visive conosciute come widget. Questi widget MR hanno il potenziale di supportare i chirurghi sovrapponendo informazioni utili direttamente sull'ambiente fisico, permettendo loro di eseguire compiti complessi con maggiore precisione. Tuttavia, nonostante i progressi nella tecnologia MR, gli approcci attuali rimangono prevalentemente statici o quasi statici, portando a errori persistenti a causa della mancanza di soluzioni adattive e dinamiche. Inoltre, l'assenza di linee guida standardizzate per la progettazione dei widget e la scarsa enfasi sulle considerazioni relative all'interfaccia utente (UI) nei sistemi MR esacerbano i problemi di usabilità, aumentando il carico cognitivo e fisico per i chirurghi e, in ultima analisi, compromettendo le prestazioni e i risultati.
Questa tesi affronta queste sfide attraverso un'indagine sistematica che impiega metodologie sperimentali, comprese indagini con chirurghi e esperti del settore, per valutare e ottimizzare soluzioni innovative basate sulla MR. Una revisione completa della letteratura evidenzia significative lacune nei sistemi MR esistenti, come la progettazione inadeguata dei widget, l'usabilità subottimale, l'alto carico cognitivo e la limitata adattabilità nei contesti chirurgici in tempo reale, in particolare in odontoiatria. Un contributo chiave di questo lavoro è il miglioramento della comprensione del design dell'interfaccia utente centrato sull'utente per i sistemi di guida precisione strumento-obiettivo. Questa ricerca sottolinea l'importanza di affrontare sfide persistenti come il disordine visivo, l'occlusione e l'inclusività, assicurandosi che i widget soddisfino le diverse esigenze degli utenti, inclusi quelli con disabilità visive o capacità cognitive variabili.
Sfruttando queste intuizioni, questa tesi introduce widget interattivi che integrano principi di percezione cognitiva, in particolare quelli derivati dalla teoria della Gestalt. Applicando principi della Gestalt come la prossimità, la continuità e l'organizzazione figura-sfondo, la ricerca si concentra sull'ottimizzazione del design visivo e sull'incorporazione di meccanismi di feedback sugli errori in tempo reale che rispondano alle azioni dell'utente. Il risultato è un set di widget interattivi che migliorano significativamente la precisione posizionale e angolare degli strumenti, gestendo efficacemente il carico cognitivo e il tempo di completamento dei compiti.
I risultati dimostrano che i widget proposti superano i design tradizionali e statici in termini di precisione, efficienza e usabilità. Questi widget migliorano l'accuratezza nella manipolazione degli strumenti, semplificano i processi cognitivi coinvolti nelle procedure ad alto rischio, riducono i tempi di completamento dei compiti e migliorano la preferenza dell'utente. Inoltre, la natura modulare e adattabile di questi design si estende oltre le applicazioni mediche, offrendo soluzioni preziose per settori che richiedono alta precisione e sicurezza, come la produzione, la manutenzione e l'assemblaggio.
Inoltre, questa ricerca presenta un framework di valutazione flessibile e open-source per la progettazione dei widget MR, promuovendo metodologie di test standardizzate e favorendo una maggiore collaborazione all'interno della comunità scientifica. Questo framework facilita lo sviluppo e la valutazione coerente dei sistemi MR, garantendo affidabilità e applicabilità trasversale ai vari settori. Guardando al futuro, questa ricerca esplora diverse direzioni per migliorare la progettazione dei widget MR, tra cui l'integrazione di sistemi di feedback tattili e uditivi per aumentare la fedeltà dell'interazione, lo sviluppo di interfacce utente adattive e personalizzate su misura per le esigenze individuali degli utenti e l'istituzione di linee guida progettuali standardizzate per incoraggiare l'innovazione e la coerenza tra i vari settori. L'obiettivo è aprire la strada a risultati più sicuri, efficienti e precisi nelle procedure e nei sistemi assistiti dalla MR, fornendo una base per i continui progressi negli strumenti di precisione basati sulla MR.Complex medical procedures, particularly those involving surgery, demand exceptional precision in spatial 6DOF (Six Degrees of Freedom) tool manipulation, where even minor errors can result in irreversible damage or undesirable outcomes. In this context, precise tool alignment is crucial,
whether in minimally invasive surgeries or delicate procedures such as dental implantology. Mixed Reality (MR) technology has emerged as a promising tool for addressing these challenges by providing surgeons with real-time, spatially accurate guidance through visual assets known as widgets. These MR widgets have the potential to support surgeons by superimposing helpful information directly onto the physical environment, enabling them to perform complex tasks with higher precision. However, despite the advancements in MR technology, current approaches remain predominantly static or quasi-static, leading to persistent errors due to a lack of adaptive and dynamic solutions. Additionally, the absence of standardized guidelines for widget design and
the underemphasis of user interface (UI) considerations in MR systems exacerbate usability issues, leading to increased cognitive and physical task loads for surgeons and ultimately detracting from performance and outcomes.
This thesis addresses these challenges through a systematic investigation that employs experimental methodologies, including user studies with surgeons and domain experts, to evaluate and optimize innovative MR-based solutions. A comprehensive literature review reveals significant gaps in existing MR systems, such as inadequate widget design, suboptimal usability, high cognitive task demands, and limited adaptability in real-time surgical contexts, particularly in dentistry. A key contribution of this work is advancing the understanding of user-centered UI design for precision tool-to-target guidance systems. This research highlights the importance of addressing persistent challenges such as visual clutter, occlusion, and inclusivity, ensuring that
widgets cater to diverse user needs, including those with visual impairments or varying cognitive capabilities.
Building on these insights, this thesis introduces interactive widgets that integrate principles of cognitive perception, particularly those derived from Gestalt theory. By applying Gestalt principles such as proximity, continuity, and figure-ground organization, the research focuses on optimizing visual design and incorporating real-time error feedback mechanisms that respond to user actions. The result is a set of interactive widgets that significantly enhance the positional and angular precision of the tools while managing cognitive load and task completion time effectively.
The findings demonstrate that the proposed widgets outperform traditional, static designs in terms of precision, efficiency, and usability. These widgets improve tool manipulation accuracy, streamline cognitive processes involved in high-stakes procedures, reduce task completion times, and enhance user preference. Moreover, these designs’ modular and adaptable nature extends beyond medical applications, offering valuable solutions for industries requiring high precision and safety, such as manufacturing, maintenance, and assembly.
Furthermore, this research presents a flexible, open-source evaluation framework for MR widget design, promoting standardized testing methodologies and fostering greater collaboration within the scientific community. This framework facilitates consistent development and assessment of MR systems, ensuring reliability and cross-domain applicability.
Looking to the future, this research explores several directions for enhancing MR widget design, including integrating haptic and auditory feedback systems to increase interaction fidelity, developing adaptive and personalized user interfaces tailored to individual user needs, and establishing standardized design guidelines to encourage innovation and consistency across industries. The aim is to pave the way for safer, more efficient, and precise outcomes in MRassisted procedures and systems, providing a foundation for continued advancements in MR-based precision tools
Safety Compliant, Ergonomic and Time-Optimal Trajectory Planning for Collaborative Robotics
No full textThe demand for safe and ergonomic workplaces is rapidly growing in modern industrial scenarios, especially for companies that intensely rely on Human-Robot Collaboration (HRC). This work focuses on optimizing the trajectory of the end-effector of a cobot arm in a collaborative industrial environment, ensuring the maximization of the operator's safety and ergonomics without sacrificing production efficiency requirements. Hence, a multi-objective optimization strategy for trajectory planning in a safe and ergonomic HRC is defined. This approach aims at finding the best trade-off between the total traversal time of the cobot's end-effector trajectory and ergonomics for the human worker, while respecting in the kinematic constraint of the optimization problem the ISO safety requirements through the well-known Speed and Separation Monitoring (SSM) methodology. Guaranteeing an ergonomic HRC means reducing musculoskeletal disorders linked to risky and highly repetitive activities. The three main phases of the proposed technique are described as follows. First, a manikin designed using a dedicated software is employed to evaluate the Rapid Upper Limb Assessment (RULA) ergonomic index in the working area. Next, a second-order cone programming problem is defined to represent a time-optimal safety compliant trajectory planning problem. Finally, the trajectory that ensures the best compromise between these two opposing goals -minimizing the task's traversal time and maintaining a high level of ergonomics for the human worker- is computed by defining and solving a multi-objective control problem. The method is tested on an experimental case study in reference to an assembly task and the obtained results are discussed, showing the effectiveness of the proposed approach