Politecnio die Bari - Catalogo di prodotti della Ricerca
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Shaping Signals in Space: Next-Gen Satellites with Reconfigurable Photonic Filters
No full textAs data transmission rates continue to increase, telecommunication channels are becoming more congested, with multiple signals sharing the same bandwidth. In this scenario, reconfigurable photonic filters offer a solution for effective spectrum management and interference reduction, ensuring reliable signal transmission while significantly minimizing size, weight, and power consumption (SWaP). Here, we propose a novel reconfigurable photonic filter with two cascaded Coupled-Resonator Optical Waveguides (CROW) architecture in the TriPleX platform over a compact footprint of 2.8×1.8 mm2. By continuously tuning the phase-change material (PCM) between its crystalline and amorphous states, arranged along the CROW with an engineered pattern, it is possible to achieve the desired adjustments in bandwidth and/or central frequency, with a range of 2 GHz and 20 GHz, respectively, with a flat bandwidth a nd an extinction ratio higher than 3.5 dB. The proposed reconfigurable photonic filter is particularly advantageous for Space payloads due to its ability to adapt both the central frequency and bandwidth while maintaining its compact size, high -speed signal processing capabilities, and adaptability to Space environment continuous changes allowing for Extremely High-Frequency applications such as radio astronomy, high-frequency microwave radio relay, and microwave remote sensing
From Marble Waste to Eco-Friendly Filament for 3D Printing to Help Renaturalization of Quarries
No full textThe excessive use of materials that are generally difficult to discard, such as stone materials, has caused growing ecological concern. Among these, marble is extracted from quarries, but when the raw material is exhausted, these places are deserted. For this reason, several measures have been adopted in recent years to requalify these areas. In addition, recent technological developments involve the creation of innovative green materials that privilege the circular economy and waste recycling. This research presents the development of innovative, sustainable filaments for the fused filament fabrication (FFF) printing technique from recycled marble waste (MW) and biocompostable and biodegradable polylactic acid (PLA) matrix. MW was added to the polymer in concentrations of 10 wt.%, 20 wt.%, and 30 wt.%, and the blends were extruded to develop innovative green filaments. The chemical/structural properties of the raw materials and the thermal and mechanical features of the new composites were investigated. Composites containing 10 and 20 wt.% of MW showed good printability. In contrast, extrusion and printing difficulties were observed with 30 wt.% of MW. Finally, this paper proposes a project to renaturalize and requalify a disused marble quarry located in Trani (Apulia, Italy) with 3D printing devices using the newly produced eco-filaments, which have better features. The main purpose of this article is to propose a concrete, economic, and sustainable application of 3D printing involving processes such as waste and by-product recycling and renaturalization of disused quarries, with both economic and environmental benefits
A Load Model to Reduce Computational Effort in Real-Time Simulation of Asymmetrical Short Circuits
No full textTransient analyses of electrical networks demand highly accurate models to represent component behavior precisely, thereby increasing the computational burden of simulations. This aspect becomes critical when conducting real-time simulations, such as Hardware-in-the-Loop, as the computational weight of the models can make some case studies unfeasible and require increasingly powerful devices, significantly raising the cost of real-time test systems. This paper proposes a low computational cost approach to model single-phase dynamic resources for stationary and dynamic power system analyses. The strategy is based on the instantaneous p-q theory and avoids heavy blocks/calculations such as Root-Mean-Square, Phase-Locked-Loop, and abc-dq0 coordinate transformations. Moreover, a Single-Phase P-Q Theory-based Dynamic Load model is introduced and validated on Matlab/Simulink platform under severe transient network conditions, namely LG and LL asymmetrical short circuits. The model is compared with static and dynamic load models of the simulation platform
CircuitRIS: A Simulation Framework for Analyzing Circuit-Level Non-Idealities in RIS-Aided Wireless Communications
No full textAdaptive Droop Control for Stability Enhancement in Islanded DC Microgrids with CPLs
No full textModern DC Microgrids (DC-MGs) typically comprise renewable generation units, batteries, and loads interconnected via power converters. Loads with stiffly regulated converters may behave as Constant Power Loads (CPLs) and exhibit negative incremental impedance, which can decrease the system's damping capability and increase the risk of instability. To address this issue, droop gains can offer a proper potential to enhance the grid's dynamic behavior. Thus, this paper proposes a decentralized droop-based algorithm to adjust the droop gains adaptively to not only provide good voltage regulation and accurate current sharing among units but also sustain the grid far from the instability margin. To this end, the droop gains' upper bound necessitated to ensure stable operation will be determined, considering the in-service CPLs. Then, based on this upper bound, the droop gain for each unit can be obtained. The stability of the DC-MG is analyzed by computing the system's eigenvalues using a small-signal analysis. The effectiveness of the proposed approach has been evaluated through simulation scenarios using MATLAB®/Simulink
Progettare il superamento degli insediamenti abusivi dei lavoratori agricoli: questioni e prospettive
No full textL’occasione offerta dal PNRR con la Misura 5C2 investimento 2.2 Piani urbani integrati per il superamento degli insediamenti abusivi per combattere lo sfruttamento dei lavoratori in agricoltura consente ai territori gravati dalla problematica di beneficiare di finanziamenti per migliorare per predisporre soluzioni insediative per il miglioramento della condizione abitativa e per consentire la fuoriuscita dai circuiti di illegalità dei lavoratori stagionali. Il contributo si concentra sulla ricerca-azione portata avanti da dipartimento ArCoD, tuttora in corso, sull’insediamento informale abusivo di Borgo Mezzanone nel territorio della Capitanata e riflette sulle modalità con cui una politica abitativa ambiziosa e straordinaria possa definire un nuovo spazio ‘abilitante’ dove sollecitare le capacità di appropriazione e le relazioni sociali.The opportunity offered by the PNRR with Measure 5C2 investment 2.2 Integrated Urban Plans for the overcoming of illegal settlements to combat the exploitation of workers in agriculture allows territories burdened by the problem to benefit from funding to improve settlement solutions for the improvement of housing conditions and to allow seasonal workers to escape from illegal circuits. The contribution focuses on the action-research carried out by the ArCoD department, which is still in progress, on the informal squatter settlement of Borgo Mezzanone in the Capitanata area and reflects on the ways in which an ambitious and extraordinary housing policy can define a new 'enabling' space where to solicit appropriation skills and social relation
An isomorphism between projective models of toric and hyperplane graphic arrangements
No full textThis paper presents a bridge between the theories of wonderful models associated with toric arrangements and wonderful models associated with hyperplane arrangements. In a previous work, the same authors noticed that the model of the toric arrangement of type An-1 associated with the minimal building set is isomorphic to the one of the hyperplane arrangement of type An associated again with the minimal building set; it is natural to ask if there exist similar isomorphisms between other families of arrangements. The aim of this paper is to study one such family, namely the family of arrangements defined by graphs. The main result states that there is indeed an isomorphism between the model of the toric arrangement defined by a graph Gamma and the model of the hyperplane arrangement defined by the cone of Gamma, provided that a suitable building set is chosen
Impact of feed rate and arc power in wire arc additive manufacturing of AISI 308L stainless steel
No full textIn this study, the process of wire arc additive manufacturing (WAAM) by cold metal transfer (CMT) operation has been investigated for AISI 308L austenitic stainless steel. The wire feeder rate (WFR) was set between 3.5 and 7.0 m/min, while the current ranged from 72 to 115 A and the voltage from 11.1 to 12.6 V, as determined by the generator. Additionally, the robot speed was maintained at 7 mm/min for all samples. Microstructural and mechanical analyses have been conducted to improve the dilution area by considering having a different range of the width of the deposited part. Optical microscopy (OM) has been used for scanning the cross-section of the fabricated parts, and scanning electron microscopy (SEM), together with electron back scatter diffraction (EBSD), for monitoring the microstructure of the substrate, heat-affected zone (HAZ), and deposited metal. Energy-dispersive X-ray (EDX) analysis was applied to reveal the dilution area. Moreover, to link the oxidation of the peak deposition to the surface roughness, a focused ion beam (FIB) was used to remove a tiny volume of the peak surface. The results indicate that increasing the voltage and current in the WAAM process directly influences both microhardness and bead width. Microhardness reached up to 310 HV in the heat-affected zone (HAZ), while the width of the deposited bead increased from 2.9 mm at 799 W to 6.2 mm at 1449 W. Additionally, surface roughness along the deposited lines decreased with a higher wire feeder rate, with the lowest roughness recorded at 20.1 μm. Finally, FIB analysis revealed that the oxide layer was approximately 1 μm thick, with chromium penetration observed within the layer
