Higher Institute on Territorial Systems for Innovation
PORTO@iris (Publications Open Repository TOrino - Politecnico di Torino)Not a member yet
146173 research outputs found
Sort by
A modal-based shape optimization methodology for conventionally shaped patches in composite plate repair
Full text linkComposite materials are known to excel in high-performance applications, particularly in the aerospace industry. Due to this fact, there is a growing concern regarding the maintenance, repair, and overhaul operations of such materials. Within this context, the best approaches for restoring the degraded mechanical properties of composites converge towards the use of fiber-reinforced adhesive patches. The present work proposes a novel methodology for the shape optimization of patches for the recovery of locally damaged composite plates. A shape optimization problem was formulated with the aim of minimizing the error associated with the modal response of the repaired structure to that of the undamaged one. Sequential linear programming was employed alongside an interior point algorithm to attain the optimized dimensions of rectangular single-sided patches, which were used in the restoration of simply supported damaged square panels. The damage was introduced by the mechanical removal of material along the central region. Modal and three-point bending tests were conducted to evaluate the performance of the patch repair. The modal response of the repaired panels indicated an efficiency of 98.2% restoration of the first natural frequency. The effectiveness in terms of mechanical strength was 94.0% in restoring the maximum resisted load, and 96.5% in terms of the ultimate displacement
A residual a posteriori error estimate for the stabilization-free virtual element method
Full text linkIn this work, we present the a posteriori error analysis of Stabilization-Free Virtual Element Methods for the 2D Poisson equation. The absence of a stabilizing bilinear form in the scheme allows to prove the equivalence between a suitably defined error measure and standard residual error estimators, which is not obtained in general for stabilized virtual elements. Several numerical experiments are carried out, confirming the expected behaviour of the estimator in the presence of different mesh types, and robustness with respect to jumps of the diffusion term
Hierarchical zeolites for dimethyl ether dehydration into light olefins
Full text linkDimethyl ether (DME) conversion into light olefins (DTO) is a process that can lead to the sustainable production of molecules like ethylene, propylene, and butenes, which are key building blocks in the chemical industry. Acid catalysts involved in the conversion of methanol and DME into hydrocarbons (MTO and DTO) are usually affected by fast deactivation due to coke generation. In the present study, four hierarchical zeolites were synthesized with different Si/Al ratios according to two procedures: a post-treatment (named “etching”) of a HZSM-5 microporous zeolite with a solution of ammonium fluoride and hydrofluoric acid, and a one-pot bottom-down approach involving an organosilane to induce mesoporosity during the hydrothermal synthesis. The samples were characterized from a physico-chemical standpoint to assess crystallinity, textural properties, and acidity. All the synthesized zeolites were then tested for about 14 h in the DTO process at a temperature range of 300–375 °C. Results showed that hierarchical zeolites with mild acidity have a very good stability, even when they are tested at the highest temperature, at which conventional microporous samples deactivate quickly. Conversion of 80–90 % is achieved at 375 °C and a space velocity of 1 gcat∙h∙molC−1, with propylene as the most abundant product. Samples prepared via one-pot synthesis resulted in a greater propylene-to-ethylene ratio, partly due to shape selectivity related to the pore size distribution
Mechanical Characterization and Constitutive Modelling of Commercial Biopolymers and Their Blends for Biomedical Applications
Full text linkNowadays, biopolymers like Poly(lactic acid) (PLA) and Polycaprolactone (PCL) are commonly adopted in
several fields of medicine, from orthopaedics to pharmacology. When dealing with medical applications like
prostheses or scaffolds, it is crucial to have a deep knowledge of the mechanical properties of such biopolymers.
Both biopolymers show a viscoplastic behaviour, namely, their mechanical response depends on the temperature and the velocity at which the loading or the deformation is applied. Currently, several companies commercialise a large variety of PCL and PLA blends with different ratios classified as “medical grade”, indicating that such blends are suitable for manufacturing medical devices. The information about the mechanical behaviour of these blends remains unclear, since the datasheets available report information about the Young’s Modulus, a limited amount of data considering their full mechanical behaviour. Most of these commercially available biopolymers have not been investigated thoroughly in the past. In this paper two commercially available biopolymers, Resomer LR 704 S and LC 703 S, from Evonik were investigated. Specifically, the original polymers and the following blend combinations were tested: 60:40, 40:60, and 50:50. The original biopolymers and their blendcombinations were considered to explore the application of developing two innovative devices for soft tissues repair, T-REMEDIE for tendon repair (Tendon Repair Medical DevIcE) [patent ID: IT202000006967A1](“Device
and assembly for the repair of soft tissues, such as tendons and ligaments,” 2020) and T-SURE for abdominal
hernia repair (Tissue Surgical REpair), under development in the BIOMAST Lab (BIO-MAterials and STructures
Laboratory) at the Politecnico di Torino. Experimental tensile tests on dog bone specimens manufactured by
compression and injection moulding were evaluated. Based on the experimental results, the constitutive three
network model (TNM), the three network viscoplastic (TNV) model and the Flow Evolution Network (FEN)
model were implemented in MATLAB and calibrated. This work represents the first time these constitutive laws
have been applied to biopolymers. All the models are suitable for biopolymer constitutive modelling, showing
promising results. The constitutive material parameters for all the models are reported in the paper
Deep reinforcement learning control architectures for industrial multi-energy systems: from single-agent to hierarchical multi-agents
Full text linkThe increasing share of renewable energy sources in industrial, multi-energy systems has introduced significant challenges for the optimal coordination of multiple energy carriers. This work focuses on improving the cost-effective and robust operation of an industrial plant that simultaneously produces electricity, steam, hot water, and chilled water. It explores whether data-driven control strategies based on deep reinforcement learning can enhance the economic and energy performance of the plant, compared to traditional methods, and whether multi-agent structures can further improve robustness. Three control architectures were designed and evaluated – centralized, decentralized, and hierarchical – using a year of actual operational data from the industrial plant. The results show that all of the proposed strategies reduced total operating costs by more than 6% compared to existing rule-based control. The hierarchical configuration achieved the best performance and demonstrated superior robustness to variations in energy prices. These findings highlight the potential of learning-based hierarchical coordination as a practical and resilient framework to manage complex industrial energy systems
The Special issue of HYCELTEC2024 - IX International Symposium on Hydrogen, Fuel Cells and Advanced Batteries
No full textSTRATEGIE DI DISSEMINAZIONE DEL PATRIMONIO ARCHEOLOGICO: DIGITALIZZAZIONE E VIDEO MAPPING DEL SITO DI NISA VECCHIA.
No full textThe digitisation of the Parthian site of Old Nisa and the resulting video mapping communication project effectively address many of the challenges outlined by international guidelines from ICOMOS, UNESCO, and ICOM for the protection, conservation, enhancement, and communication of cultural heritage. In May 2024, a series of 3D survey activities was carried out to achieve a complete mapping of the city and its walls, using integrated laser scanning techniques that combined the well-established Terrestrial Laser Scanning (TLS) method with Mobile Mapping Systems (MMS) supported by portable scanners employing SLAM (Simultaneous Localisation and Mapping) technology. The narrative project is based on a video projection onto a 3D-printed replica of the city derived from the 3D laser-based model, divided into tiles reminiscent of a cartographic grid. This model is mounted on a wooden support designed to accurately represent the elevation differences of the hill on which the citadel stands.
The video mapping projection offers the public an overview of the region of Parthian influence in present-day Turkmenistan and its relations with other civilisations. It also presents the history of the settlement foundation, describes its most significant architectural complexes, and summarises their excavations, including recent restoration and enhancement efforts, as well as the digitisation of the site through laser scanning technology. The information is based on archaeological research that has been developed and gradually deepened over the course of a century
Benchmark of the new release of FELICE solver in TOPICA code with the ASDEX Upgrade 3-strap antenna
Full text linkThis paper discusses the integration of the latest release of the FELICE code (2023) with the TOPICA code. A comparison is made between the current and previous versions of FELICE, starting from the plasma impedance matrix itself and, eventually, getting to the standard TOPICA outputs as the antenna input parameters, the coupled power and the radiated fields. The ASDEX Upgrade (AUG) 3-strap antenna is adopted for this comparison, showing very similar results for the two versions of FELICE
Self-extinguishing and hydrophobic epoxy composites containing hydrothermal liquefaction-derived biochar and whisker-like particles based on tailored PVP-coated silica fibers
Full text linkThe hydrothermal liquefaction (HTL) of waste biomass produces bio-oil along with solid, aqueous, and gaseous co-products. The utilization of solid residue (biochar) is a crucial step in achieving the sustainability and circularity of the entire HTL process. Here, we propose the valorization of biochar derived from HTL of municipal sewage sludge as a functional additive for epoxy resins to enhance their flame retardancy. Biochar samples from HTL, obtained under different operative conditions, were characterized and incorporated into an epoxy resin
cured with a cycloaliphatic amine. Biochar was used in combination with whisker-like particles, made of silica coated with electrospun poly(vinylpyrrolidone) (PVP) and functionalized to enhance compatibility with the polymer matrix. The synergy of these fillers with ammonium polyphosphate and urea enabled the preparation of no-drip self-extinguishing composites (V0 rating at UL-94 vertical flame spread tests), showing excellent fire performance, as assessed by cone calorimetry and pyrolysis combustion flow calorimetry, with a limited effect on
the viscoelastic behavior and some impact on the flexural properties. Notably, a strong flame retardant action in the condensed phase, with a slight effect in the gas phase, was responsible for the formation of a ceramic continuous char, which decreased the peak of the heat release rate (~36%) as well as the total smoke release (~10%) during the burning process. Besides, the tailored whisker-like particles were able to migrate at the surface of composites, providing water contact angles of ~120◦, suggesting a potential use of the designed materials as water-proof protective coatings or components for multifunctional infrastructures
Exploring Environmental Management Systems Effectiveness: Do Environmental Investments Effectively Lead to Performance Improvements?
Full text linkIndustrial production is a cornerstone of modern economies but significantly impacts the
environment. Environmental Management Systems (EMSs) aim to drive sustainable performance,
yet their effectiveness remains questioned. This study quantitatively investigated
the relationship between improvement objectives, allocated budgets, and environmental
performance in 14 EMAS-registered natural gas thermal power plants in Italy (2014–2021).
Using correlation analyses and a combined metric (CUF) encompassing improvement focus
and plant utilization rate, the results show that investments alone did not directly drive
performance improvements. However, increased plant utilization emerged as a critical
factor, with strong correlations observed for CO2 emissions and fuel efficiency. The CUF
metric outperformed standalone measures, underscoring the interplay between operational
efficiency and targeted investments. This study offers new insights into the effectiveness of
EMSs, demonstrating their potential to drive environmental performance improvements
when combined with operational strategies. Future research should explore long-term
impacts and qualitative factors, such as technological and managerial practices, to refine
EMS effectiveness further