Politecnio die Bari - Catalogo di prodotti della Ricerca
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3D NUMERICAL INVESTIGATION OF THE SEISMIC RESPONSE OF A SHALLOW TUNNEL CROSSING A TOPOGRAPHICALLY COMPLEX AREA
No full textInvestigating the Role of Stabilizers in Enhancing the Electrocatalytic Activity of PdAu Nanoalloy Catalysts for Methanol Oxidation in Fuel Cells through an Oxidative Addition Mechanism
No full textThe formation of nanoalloys through borohydride reduction is an effective method for creating nanocatalysts. Surfactants and stabilizers are crucial for enhancing the stability, dispersion, and electrocatalytic activity of catalysts used in the methanol oxidation reaction (MOR) in fuel cells. This study investigates the effects of various capping agents and stabilizers─reduced graphene oxide, aminoclay, sodium dodecyl sulfate (SDS), cetyltrimethylammonium bromide, polyvinylpyrrolidone, and poly(vinyl alcohol)─on the morphology and electrocatalytic activity of PdAu nanoalloy thin films for methanol oxidation. In electrochemical tests, the PdAu/SDS catalyst demonstrated impressive activity of approximately 700.48 mA mg-1, significantly surpassing conventional Pt/C catalysts. Scanning electron microscopy (SEM), energy-dispersive analysis of X-ray, and elemental mapping analyses after accelerated durability tests revealed no significant structural changes or metal leaching following 200 MOR cycles. Our analysis aimed to clarify their functions while considering various stabilizers (cationic, anionic, nonionic) and proposed a new mechanism. The incorporation of SDS notably enhances the catalytic properties by increasing the electron density on the PdAu surface and facilitating the oxidative-addition of O-H bonds from methanol. Our proposed mechanism includes: methanol adsorption, O-H bonds activation (oxidative-addition), C-H bond activation, nucleophilic attack on a coordinated formyl group, and decarboxylation. As a result, the PdAu/SDS composite establishes itself as the most effective catalyst for methanol fuel cells, with anionic stabilizers outperforming nonionic and cationic surfactants
“Com’era, dov’era”... cos’era (e cos’è)? I progetti di concorso per la ricostruzione de La Fenice di Venezia
No full textNei confronti dell’architettura contemporanea, della quale è anche ospite di importanti eventi,
Venezia ha sempre avuto un rapporto controverso, essendo non solo la città dei grandi progetti
mancati (Le Corbusier, Wright, Kahn, Miralles), ma, al contrario, anche di importanti realiz-
zazioni (Scarpa, Valle, Gardella, Gregotti, Koolhaas, Aulenti, Ando e Calatrava) che dialoga-
no con la preesistenza, o comunque con parti della città lagunare. Anche il deprecabile episodio
dell’incendio del Teatro la Fenice, con una ferma e rapida operazione, è riuscito a trasformarsi
in un’occasione progettuale, sebbene normata da un bando operativo molto rigido e ideologica-
mente avvinto nell’ormai celebre motto “com’era, dov’era”. Il dibattito che ne è nato è stato par-
ticolarmente animato: certamente la definizione di “restauro” che il progetto afferma, riprende
le debite distanze da certi indirizzi progettuali contemporanei, posizionandosi più vicino agli
orientamenti del rifacimento del campanile di San Marco, al più trovando alcuni compromessi
di verosimiglianza con l’antico. Attraverso la sintetica analisi del bando di concorso e sulla base
del confronto tra ampia letteratura critica versata negli anni di quel dibattito, il paper vuole
effettuare una rilettura dei sei progetti in gara (Valle, Rossi, Aulenti, Rocchi/Aymonino, Arroyo
& Hurtado, Gardella), provando a comprenderne il valore rispetto al dibattito tra antico e
contemporaneo che anima l’architettura
Simulation-based analysis of 3D-printing industrial manufacturing processes
Get PDFIn the evolving landscape of Additive Manufacturing (AM), achieving scalable, efficient, and cost-effective production remains a critical challenge. As industries advance toward the industrialization of 3D printing, they face complex operational demands, including machine utilization, part flow synchronization, and post-processing efficiency. This thesis tackles these challenges by developing a simulation-based framework utilizing Discrete Event Simulation (DES) to enhance AM workflow efficiency across multiple technologies.
Using FlexSim simulation software, the research models and analyzes production systems involving Selective Laser Sintering (SLS), Stereolithography (SLA), and Digital Light Processing (DLP). The DES approach enables detailed evaluation of workflow parameters, resource allocation, and job scheduling strategies. Through comprehensive case studies, the framework demonstrates its ability to identify system bottlenecks, minimize idle time, and improve throughput and labor efficiency.
This thesis contributes a domain-specific DES framework tailored to AM environments, validated through empirical modeling and performance evaluation. The findings underscore the value of simulation in both the design and operational optimization of AM production lines. Furthermore, the research demonstrates the role of simulation tools in supporting data-driven decision-making, reducing production costs, and improving reliability in large-scale additive manufacturing.
Ultimately, this thesis positions Discrete Event Simulation as a key enabler for the industrial adoption of AM technologies, offering a strategic path toward enhanced productivity, scalability, and operational resilience in modern manufacturing systems
Nanomagnetic Gears With Electrically Controlled Transmission Ratio
Get PDFMagnetic gears offer a reliable and vibration-free alternative to traditional mechanical gears. At the micro- and nanoscale, electrical manipulation of magnetic domains can further enhance the performance and versatility of these gears. In this work, we introduce the concept of electrically tunable magnetic nanogears and propose a nanomagnetic gear design that operates at the mesoscopic scale and exploits the electrical manipulation of magnetic textures and stray field coupling to achieve precise, contactless and tunable torque transmission. This device concept is scalable and offers a continuously adjustable electrical transmission ratio between two gears by exploiting the spin-orbit torque observed in nanomagnetic devices. We have analyzed the coupling of magnetic domains in two parallel circular nanotracks, each serving as a rotor in the gear system, using experimentally realistic material parameters. By exploiting the current-driven motion of the magnetic domains, we derive an ideal transmission ratio given by ω2/ω1 = 1 + ωd/ω1 where ω2 and ω1 are the mechanical angular velocities of the driven (output) and driving (input) rotors, respectively, and ωd(J) is the current-driven angular velocity of the magnetic domains valid when the two rotors are fully coupled via stray fields. Numerical calculations show that this nanogear can work up to current densities J of 4.1012 A/m2 and distances of 30 nm. This work paves the way for the development of a new generation of highly tunable nanomagnetic gears with potential applications in nano-actuators, micromachines and other nanoscale devices
Cyber-Esperienza. Estendere la progettazione dell'esperienza d'acquisto per l'industria della moda
No full textBottom quark energy loss and hadronization with B+ and nuclear modification factors using pp and PbPb collisions at = 5.02 TeV
No full textWeather-induced landslide activity in clayey slopes: modelling for the design of site-scale early warning system
No full textBased upon both phenomenological and numerical analyses, current landslide activity in clayey slopes has been found to be recurrently prompted by the soil–vegetation–atmosphere interaction taking place in the very topsoil layers. This interaction can cause transient seepage down to large depth in the slope, resulting in significant variations of pore water pressures and available strength with time at both very shallow depth and large depth below the water table, i.e., variation of the slope equilibrium, defined as slope–vegetation–atmosphere interaction. Such interaction may be the triggering factor of the activity of either shallow landslides or deep slow landslide bodies in clayey soils. This paper reports the results of a research insight into both the pore water pressure and the safety factor variations determined by the soil–vegetation–atmosphere interaction at the ground surface of slopes made of clayey turbidites, location of seasonal acceleration of deep landslide displacements and of shallow landsliding. The analyses are carried out making reference to a representative slope and are validated against field data. The results of the numerical analyses are shown to succeed in reproducing the current weather-induced activity of the landslide bodies, so that the adopted modeling represents a tool to be used within early warning systems for the mitigation of the landslide risk in the slope scenarios of reference in the paper
On the solution for the initial-boundary value problem for a nonlocal elliptic–hyperbolic system related to the short pulse equation
No full textIn this paper, we consider a non-local elliptic-hyperbolic system related to short pulse equation. That equation describes the dynamics of the electrical field of linearly polarized continuum spectrum pulses in optical waveguides, including fused-silica telecommunication-type or photonic-crystal fibers, as well as hollow capillaries filled with transparent gases or liquids. We augment the equations with some boundary conditions and prove the well-posedness of the global in time distributional solution
