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Fatigue behavior of powder bed Fused–Laser beam (PBF-LB) 70/30 Copper-Nickel (CuNi30)
Get PDFThe 70/30 Cu–Ni alloy (CuNi30) is widely employed in marine systems due to its excellent corrosion resistance
and mechanical reliability. Despite its industrial relevance, its behavior under additive manufacturing (AM),
particularly powder bed fusion–laser beam (PBF-LB) processing, has received limited attention in the context of
fatigue-critical applications. This study presents the first systematic assessment of the microstructure, defect
population, mechanical properties, and fatigue performance of PBF-LB 70/30 Cu–Ni in both the as-built and
heat-treated conditions, with specific attention to the role of build orientation using horizontally and vertically
fabricated specimens. The applied heat treatment increased mechanical strength and produced a marked
improvement in the stress–life (S–N) response of the alloy. Detailed microstructural characterization and postmortem fractography showed that fatigue cracks predominantly initiated from surface or subsurface crystallographic facets induced by local embrittlement in the matrix. The results provide essential guidance for designing
fatigue-resistant Cu–Ni components and support the broader adoption of PBF-LB 70/30 Cu–Ni in demanding
marine and naval environments. Furthermore, this work establishes a foundation for future investigations into
the corrosion-fatigue behavior of the alloy
A Software-Based Control System to Reduce Conducted CM EMI in Four-Leg Three-Phase Inverters Using the Delay Compensation Technique
Get PDFCommon-Mode (CM) conducted Electro Magnetic Interference (EMI) is a critical issue in automotive power converters, where strict EMC regulations must be met. This paper investigates the Delay Compensation Technique (DCT) applied to traction inverters to reduce CM EMI at low-frequency. Although the four-leg topology enables complementary switching, existing works do not provide a method to finely align the commutation edges, which is required to have CM current pulses canceling out and effectively reducing CM EMI. In this work, an iterative optimization method is introduced for the two-leg case, and then extended to the four-leg inverter with sinusoidal modulation, enabling fast convergence and minimal computational overhead. Experimental validation resulted in 30 dB EMI reduction at 160kHz and in 15-20 dB for frequencies up to a few MHz, with significant benefits in terms of volume reduction of the input EMI filter compared to state-of-the-art techniques
La crisi del metabolismo dell’acqua e dell’energia in Valtellina e le sfide per il progetto urbanistico
No full textFin dalla rivoluzione industriale le montagne della Valtellina sono state modellate al fine di produrre energia attraverso lo sfruttamento delle acque. Nonostante il crescente interesse per le fonti rinnovabili, il funzionamento di questo territorio è oggi messo in crisi dal cambiamento climatico e il conseguente esaurimento delle risorse idriche. Alla luce di queste problematicità, l’articolo indaga le strette relazioni fra l’infrastruttura energetica e lo spazio che ne supporta il funzionamento. L’osservazione del nesso fra acqua, energia e ambiente, rende possibile ridiscutere funzionamenti territoriali consolidati e immaginare nuovi metabolismi attraverso strategie e progetti che consentano un migliore utilizzo delle risorse disponibili
Synthesis and application of a coumarin-derived dye for sustainable dyeing of polyester fabric
No full textPurpose: This study aims to synthesize a coumarin-derived dye and evaluate its application in polyester fabric dyeing, focusing on its potential as a safer alternative to hazardous disperse dyes. By examining the dye's fastness, fluorescence, thermal behavior and theoretical binding interactions, this research supports more sustainable practices in textile processing.
Design/methodology/approach: The coumarin dye, 7-diethylamino-3-acetylcoumarin, was synthesized via the Knoevenagel reaction. Polyester fabrics were dyed using this coumarin dye under various conditions, including acidic and alkaline environments. Dyeing performance was evaluated based on washing, rubbing and light fastness tests, with particular attention to reductive washing for optimal results. The dye's structural characteristics were analyzed through Fourier transform infrared spectroscopy (FTIR), ultraviolet-visible (UV-Vis) and nuclear magnetic resonance (NMR) spectroscopy. Thermogravimetric analysis assessed thermal stability and degradation behavior. Density functional theory simulations were conducted to elucidate dye-fiber interaction mechanisms at the molecular level. In addition, in vitro cytotoxicity was tested using human skin fibroblast (CCD-1079Sk) cells.
Findings: The coumarin-derived dye exhibited excellent dye affinity and color fastness on polyester fabrics, especially under acidic conditions with a 45-minute dyeing process followed by reductive washing. No cytotoxic effects were observed in human skin fibroblast cells, highlighting its potential as a safer alternative to conventional synthetic dyes. UV-Vis spectroscopy confirmed strong absorption properties, making the dye suitable for various textile applications.
Research limitations/implications: The study focused on polyester fabric; future research should extend the application to other textile types. Moreover, further investigation into aquatic degradation pathways and industrial-scale applicability is needed to fully validate the environmental benefits.
Practical implications: The findings suggest that coumarin-derived dyes could provide a safer and more environmentally friendly alternative to disperse dyes in the textile industry. The successful application of the dye under both acidic and alkaline conditions makes it versatile for polyester dyeing, potentially reducing chemical waste and health risks associated with synthetic dyes.
Originality/value: This study contributes to the growing body of research on sustainable textile dyeing by demonstrating the potential of a coumarin-derived dye for polyester fabrics. Its fluorescence, non-toxic nature, strong fastness properties, eco-friendliness and adaptability to different dyeing conditions make it a valuable alternative to traditional hazardous dyes, supporting the transition toward greener practices in the textile industry
Mejoras en el desempeño en economía circular en el reciclaje de PET en Cuba / Improvements in circular economy performance in PET recycling in Cuba.
No full textThe sequence of operations for recycling polyethylene terephthalate (PET) in Cuba includes the supply chain and a unique mechanical recycling plant. The objective was to evaluate and improve performance in terms of the circular economy in PET recycling. A methodology strengthened by a process approach, the use of Six Sigma (6σ) tools, circularity assessment, environmental impact assessment, and a technical, economic, environmental, and social prefeasibility study of the corrective action plan and continuous improvement opportunities was used. The results revealed nonconformities that confirmed performance deficiencies. Based on the causal analysis, a plan of measures was proposed, including technical-organizational and
engineering solutions, which will enhance and increase selective collection and recycling nationwide, restore the Recycling Plant’s design capacity, and improve product quality. The profitability indicators and sensitivity analysis were favorable. Short-term measures related to technical-organizational aspects and best practices are being implemented. Likewise, with the measures that require investment, in accordance with the investment process regulations. The results obtained corroborate the validity
of the methodology used, and constitute a viable and relevant tool for public policies. It can be generalized to the
organizational structures of the Recycling Business Group (GER), as well as to the rest of the country’s business organizations,
particularly in the process industry
Parametric modelling between supputation and graphic descriptions in Antoine de Ville’s Les fortifications (1628)
No full textThis paper examines Antoine de Ville's Les fortifications (1628), a landmark of the French school of military architecture, notable for merging geometric constructions with tabular calculations, the "supputation par les Sinus". Using parametric and algorithmic modelling, the study translates de Ville's design principles into a modular digital workflow that employs historical units of measurement and dimensions to reconstructing both plan and section of regular fortresses. The method proceeds from data input to two- and three-dimensional construction and ends with Building Information Modelling (BIM) export. This approach validates the consistency of de Ville's values, identifies points of variation, and allows parametric control of elements such as the orillon. Beyond reconstruction, the models enable enriched analysis of bastioned systems and are made available through web-based BIM platforms. The research demonstrates how early modern treatises can evolve into interactive resources, bridging historical building knowledge with contemporary tools for study and dissemination
Rank aggregation to predict the fundamental frequency of historic masonry towers
Get PDFThe fundamental frequency is a key dynamic parameter for evaluating the seismic vulnerability and structural integrity of historic masonry towers. Its estimation with empirical laws is feasible but it is often complicated by the variability in geometric features, material properties, and boundary conditions. This work proposes an original methodology that combines multiple predictive empirical models and laws using a rank aggregation approach based on the Plackett-Luce model. Rather than selecting a single law, the method considers results from empirical equations and data-driven models to produce a unified and more reliable prediction. Two distinct estimation scenarios are examined: one relying exclusively on geometric properties, and another that also takes into account mechanical features. Both are trained and validated on a broad dataset of historic masonry towers. The novelty of the approach lies in its ability to integrate different sources of knowledge while reducing individual model errors. Since many structural characteristics of the towers may be unknown, this method seeks to combine models with different input features, ranging from complex models to simpler formulations based on easily measurable parameters. By exploiting the best features of each candidate and by ranking their contributions, the method shows improved performance across different towers. This strategy can be a valuable tool in structural health monitoring and seismic assessment of heritage towers, especially when experimental dynamic data are not available and when dealing with complex modeling uncertainties
Waste-to-Hydrogen pathways: Gas composition and char structure evolution during pyrolysis of food and digestate waste
No full textThis study investigates the influence of pyrolysis temperature on the yield distribution and gas composition of biochars derived from food waste (FW) and digestate waste (DW). Pyrolysis experiments were performed at 400–700 ◦C, and the resulting solid, liquid, and gas fractions were characterised. Gas compositions were quantified using Gas Chromatography (GC), while structural and physicochemical properties of the biochars were evaluated using SEM-EDS, BET, XRD, Raman spectroscopy, and TPO-DTG analysis. The proportion of syngas components, particularly hydrogen (H2), showed a pronounced dependence on temperature and feedstock type. No detectable H2 was found at 400 ◦C for either feedstock, whereas a substantial increase occurred with temperature elevation. For FW-derived gas, H2 increased from 7.41 vol% at 500 ◦C to 26.57 vol% at 700 ◦C. Similarly, DW-based gas exhibited an increase from 6.68 vol% to 18.28 vol% across the same temperature range. This rise was accompanied by a reduction in CO2 and an increase in CH4 and light hydrocarbons. Raman spectroscopy revealed a temperature-dependent structural transition, indicated by increasing ID/IG ratios from 0.57 to 0.76 in FW biochar and 0.59 to 0.67 in DW biochar, confirming enhanced disorder and defect formation, particularly in FW. Overall, the thermochemical evolution of both feedstocks demonstrates that increasing pyrolysis temperature significantly enhances hydrogen generation capacity, most notably in food waste, where H2 production increased from undetectable levels at 400 ◦C to 26.57 vol% at 700 ◦C, underscoring the strong potential of temperature-driven pathways for producing hydrogen-rich syngas from waste materials
Computational Modeling and Thermodynamic Simulation Approaches for the Analysis of Highly Energetic Materials
No full textL'abstract è presente nell'allegato / the abstract is in the attachmen
Event-based versus particle image velocimetry for cardiac flow analysis in a left-heart simulator
Get PDFThis study reports the first biomedical application of event-based imaging velocimetry (EBIV) and demonstrates its feasibility for investigating cardiac hemodynamics. Experiments were conducted in a left-heart pulse duplicator to characterize intraventricular fluid mechanics with a transcatheter mitral valve. EBIV and conventional particle image velocimetry (PIV) measurements were acquired synchronously under two distinct flow regimes. The aim was to assess whether EBIV—a neuromorphic, event-driven imaging technology—can provide flow measurements comparable to those obtained with PIV, which serves as the reference technique for the in vitro assessment of prosthetic heart valves hydrodynamics. The results show that EBIV accurately reproduces valve-related hemodynamic features, including phase-averaged velocity fields, vortex structures, circulation, Lagrangian trajectories, and pulsatile kinetic energy, while producing markedly compact datasets and benefiting from an extended dynamic range. A modal analysis based on proper orthogonal decomposition further confirms a strong agreement between EBIV and PIV, revealing nearly identical dominant spatial modes. These findings establish EBIV as a promising, data-efficient, and real-time capable alternative for the quantitative characterization of cardiac flows. This first biomedical application underscores EBIV’s potential for device assessment, intraventricular flow analysis, and broader application in experimental cardiovascular research