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Decarbonizing urban public transport: development and final assessment of a hydrogen-fueled hybrid propulsion system for city buses
No full textThe H2ICE project focuses on the investigation of the feasibility and the development of a new class of hybrid
powertrains incorporating a hydrogen-fueled Internal Combustion Engine (ICE) designed for 12-meter urban
buses, with the goal of achieving low emissions and competitive efficiency. A combined experimental and
simulation-based approach was adopted.
Achieving the full potential of this propulsion system requires significant advancements over the current state
of the art, as several technical challenges remain. Chief among these is effectively managing the combustion
process. First, a three-dimensional CFD model was calibrated and validated against an extensive optical-engine
campaign, achieving predictive accuracy on mixture formation and flame development adequate for supporting
design decisions in ultra-lean operation. This model supported the development of a complete one-dimensional
engine model, coupled with a dedicated control strategy that improved combustion stability in the ultra-lean
regime while enabling reduced NOx formation and high efficiency.
Several Waste Heat Recovery (WHR) configurations were assessed through a synergy between experimental
analysis and numerical simulations, including an electric turbocompound and an Organic Rankine Cycle (ORC).
The combined two-stage WHR system achieved a maximum recovery efficiency of 14% (6.4% on average),
delivering up to 16 kW of net electrical power under high exhaust energy conditions. In parallel, an innovative
H2-SCR concept was experimentally validated, reaching up to 50% NOx conversion efficiency at exhaust temperatures
around 250 ◦C and oxygen concentrations of approximately 12.5%.
A causal Rule-Based (RB) Energy Management System was designed as an implementable solution for realtime
ECU application. In the final virtual-vehicle assessment over SORT driving cycles, hydrogen consumption
reached values as low as 9 kg/100 km (i.e., meeting the project target of ~ 10 kg/100 km under standardized
conditions), while real-world variability may lead to higher values, as discussed in the manuscript. Tailpipe NOx
emissions ranged from approximately 0.14 g/kWh under standardized type-approval cycles to as low as 0.009 g/
kWh under real-world operating conditions, remaining below the forthcoming Euro 7 limits for heavy-duty
applications.
These results demonstrate that H2ICE-based hybrid powertrains represent a technically feasible and realistic
solution for urban buses, capable of delivering low pollutant emissions and competitive efficiency, and offering a
viable decarbonization pathway in contexts where battery-electric solutions face infrastructure or range
limitations
Come mare increspato da piccole onde: le coperture a volta sottile di Felice Bertone per l'architettura industriale
No full textThe rapid industrial development that characterised the second half of the 20th century in Italy led to the spread of an increasing number of production facilities across the country, which soon became the focus of the professional activity of many architects and engineers. The need to ensure optimal natural lighting for work surfaces and maximum flexibility in the use of interior spaces directed designers' attention to roofing. It became a fascinating field for technical experimentation: during these years the use of thin reinforced concrete vaults with extremely innovative solutions was established. In this perspective, the work of engineer Felice Bertone, a unique figure as a designer and building contractor, takes on particular significance. Known for his decisive contribution to the roofing solution for the Teatro Regio in Turin, Bertone stood out for his professional commitment to perfecting thin vaulted roofs, composed of self-supporting elements, shaped as hyperbolic paraboloids. His experimentation resulted in two patents and found its main field of application in industrial architecture. Considering the contemporary technical context, the paper analyses his patent proposals and some of his most significant works, drawing on the rich archive documentation preserved at the Politecnico di Torino
CFD-supported calibration optimization of a retrofit hydrogen–diesel dual-fuel engine
No full textDual-fuel (DF) hydrogen–diesel engines could offer a retrofit-compatible pathway for medium-/heavy-duty transport decarbonization. In this study, a 6-cylinder
compression ignition engine retrofitted for hydrogen port fuel injection is investigated through a CFD-supported framework. A validated 3D-CFD model, based
on an extensive experimental dataset, was applied to investigate injection strategies and calibration parameters in both retrofit and native DF engine modes. The
model accurately captures combustion behavior, emissions trends, and the factors limiting hydrogen energy share (HES). Results show that an optimized native DF
calibration enables up to 90% CO2 reduction relative to diesel operation while maintaining combustion stability. Particulate matter emissions are nearly eliminated
at high HES, whereas low HES combined with non-optimized diesel injection results in PM levels comparable to diesel-only operation. The analysis highlights the
decisive role of a coordinated optimization of HES and diesel calibration strategy in governing ignition dynamics, combustion efficiency, and soot formation
A linear programming framework and an improved backtracking strategy for multiple-gradient descent
No full textThis work introduces a method to compute descent directions common to two or more differentiable functions defined over a shared unconstrained domain. Building on this, an alternative Multiple-Gradient Descent procedure for Multi-Objective Optimization problems is proposed. The core of the approach consists of solving a relatively cheap Linear Programming (LP) problem, where the objective and constraints are constructed from the gradients of the functions involved. In particular, the LP formulation is designed such that, when a common descent direction does not exist, it still yields a direction that is perpendicular to all objectives’ gradients, if such a direction is available. Additionally, a tailored backtracking strategy is presented, enhancing the performance of Multiple-Gradient Descent methods, especially when paired with the proposed LP-based direction computation, by improving the exploration of the Pareto set and front. Theoretical analysis and experiments on standard benchmark problems are provided to evaluate the effectiveness of the proposed techniques
Parametric modeling of cradle-to-gate carbon emissions from gas-atomized AISI 316L powders under closed-loop feedstock strategies
No full textThis study introduces a parametric framework for the cradle-to-gate assessment of carbon emissions associated with the production of gas-atomized AISI 316L stainless steel powders intended for use in additive manufacturing and other powder metallurgy processes. The model provides a detailed representation of upstream material flows and includes all major unit operations involved in powder production, such as feedstock preparation, gas atomization, sieving and blending, and packing. By varying the composition of the feedstock charged into the atomizer crucible, the framework enables the estimation of carbon emissions across a wide range of scenarios reflecting alternative sourcing strategies. The case study on AISI 316L highlights the environmental benefits of integrating closed-loop material flows, including the recirculation of off-specification powders and the direct use of compatible metallic scrap. Furthermore, broadening the acceptable powder size range significantly improves atomization yield, thereby reducing the specific carbon intensity of usable powder output. Such an approach lays the foundation for the development of robust decision-support tools for process planning in gas atomization, with direct implications for industrial-scale powder production
The rehabilitation of atrophic jaws using short implants with different surface treatment. A multicentred cross-over randomized trial
No full textL'abstract è presente nell'allegato / the abstract is in the attachmen
Signal-Based Dynamic Identification of Composite Steel–Concrete Bridges Using Short-Duration Records
Get PDFtructural Health Monitoring (SHM) of existing bridges increasingly relies on dynamic measurements to assess structural performance and detect potential damage. However, the practical implementation of long-term vibration-based monitoring is still constrained by the volume of data required and the complexity of continuous acquisition systems. In the context of ensuring the safety and performance of existing bridge infrastructure, vibration-based monitoring offers a powerful tool for detecting changes in structural behavior. This study presents an extended investigation of dynamic monitoring applied to composite steel–concrete viaducts, focusing particularly on the signal-analysis framework and methodological enhancements. Short-duration accelerometric records are processed through an automated signal-selection pipeline and advanced modal-parameter extraction algorithms to yield identification of modal features. Emphasis is placed on the statistical evaluation of modal-parameter stability, effects of operational and environmental variability, and the potential for long-term trend detection. The results highlight the limits of short-length recordings when OMA techniques are applied. Nevertheless, appropriate signal processing and data handling can provide acceptable insights into the dynamic characteristics of large bridge systems. The methodological findings provide a foundation for improved monitoring workflows, showing the amount of information that can be retrieved using a cost-effective hardware deployment and supporting further development toward structural digital twins
Multi-fidelity probabilistic failure onset analysis of composite structures under uncertainties
Get PDFAdvancements in composite manufacturing have enabled innovative design strategies to enhance stress distribution, stiffness, and overall performance of composite structures. However, uncertainties related to material variability, load fluctuations, and manufacturing defects continue to pose serious challenges for structural reliability and early failure prediction. This study presents a novel multi-fidelity probabilistic framework for analyzing composite laminates under uncertainties. The methodology integrates low- and high-fidelity structural theories generated via the Carrera Unified Formulation (CUF). An adaptive Gaussian Process Regression (GPR) model is employed to construct a probabilistic surrogate that selectively uses high-fidelity theories only where needed, based on uncertainty-driven learning. Compared to conventional Monte Carlo Simulations (MCS) based entirely on high-fidelity models, the proposed framework achieves comparable accuracy, with R2 > 0.99 and nRMSE < 1%, while reducing the computational cost by a factor of two to ten. Convergence is obtained with only 20–300 high-fidelity simulations, against 400–800 required by the reference benchmark. The approach is applied to a composite plate, a free-edge laminate, and an open-hole configuration, where the adaptive multi-fidelity model accurately captures through-thickness stresses and failure indices
Le retour à la ville. L’Architecture d’Aujourd’hui di Bernard Huet, tra Francia e Italia. 1974-1976
No full textBiochar-Coated Drywall Panels for Electromagnetic Shielding Applications in the K-Band
No full textWith the rise of telecommunication systems in recent decades, the implications for human health have prompted a search for ways to reduce the impact of electromagnetic waves in buildings when necessary. A viable and promising solution to realize electromagnetic shielding could be the use of drywall panels coated with a biochar paste, as proposed in this study. Biochar (bio-charcoal), a low-cost and carbon-based material, can be obtained by the thermochemical conversion of different biomass sources. A commercial wood-based biochar thermally treated at 750 °C is considered in this work. Transmission coefficients of several gypsum board elements with a biochar coating are measured in the frequency K-band (18–27 GHz). In addition, the SE of a double panel configuration, obtained by joining two coated boards to form a multilayer structure, is evaluated. The results show that the biochar coating significantly enhances the SE compared to uncoated drywall. At the highest biochar loading investigated (0.20 g/cm2), the shielding effectiveness consistently
exceeds 27 dB for single panels and 46 dB for double panels across the entire frequency band. These findings indicate that biochar-coated drywall systems offer a practical and sustainable solution for integrating electromagnetic shielding into building envelopes, paving the way for innovative applications in indoor exposure control