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Understanding Surgical Triplet Videos Through Transferable Visual Models from Natural Language Supervision
No full textSurgical triplet video understanding is essential for accu-rately recognizing and classifying surgical actions in real-time video data, enabling improved surgical planning and support. However, the recog-nition of surgical video triplets is particularly influenced by the varying frequency and duration of specific actions. Furthermore, the similarity in motion trajectories across various surgical actions presents another issue in video-based fine-grained surgical action recognition, complicat-ing the differentiation of similar actions. To address these challenges, we propose a new comprehensive paired image-text surgical activity event dataset (SAE), consisting of 90,500 pairs of images and text depict-ing surgical actions. Additionally, we introduce TriClip, a novel dual-branch contrastive multimo dalframework,whicheffectivelybridgesthegapbetweenvisualandtextualmodalitiesinsurgicalactionrecogni-tion.Byleveragingtransferablevisualmodelsfromnaturallanguagesupervision,TriClipwasevaluatedusingtheCholecT45dataset,whereitachievedanSOTAaverageprecisionof42.1%,settinganewstate-of-the-artinthefieldofsurgicalactionrecognition
DLP Fabrication of Mullite Structures: Flaw Mitigation Through Powder Thermal Processing
Full text linkDigital Light Processing (DLP), which operates through a layer-by-layer deposition, has proven to be a promising technique for obtaining complex and customized architectures. However, there are still numerous unresolved challenges in ceramics additive manufacturing, among which is delamination due to suboptimal adhesion between the layers, which threatens the structural integrity and properties of samples. According to recent findings, excess surface hydroxyl groups were identified as being responsible for this defect; a suitable calcination pre-treatment of the ceramic powder could be effective in significantly mitigating delamination flaws in mullite DLP printed bodies. Therefore, in addition to optimizing the printable slurry formulation and printing parameters (mainly in terms of curing energy and layer resolution), this work aimed at investigating the influence of the calcination of a commercial mullite powder (added with magnesium nitrate hexahydrate, as a precursor of the sintering aid MgO) as a simple and effective treatment to additively shape ceramic bodies with limited flaws and enhanced density. The surface characteristics evolution of the mullite powder was investigated, specifically comparing samples after magnesium nitrate hexahydrate addition and ball-milling in water (labeled as BM), and after an additional calcination (BMC). In particular, the effect of the superficial -OH groups detected by FTIR analysis in the BM powder, but not in the BMC sample, was studied and correlated to the properties of the respective ceramic slurry in terms of rheological behavior and curing depth. The hydrophilicity of BM powders, due to superficial hydroxyls groups, affects ceramic powder dispersion and wettability by the resin, causing a weak interface. At the same time, it promotes photopolymerization of the light-sensitive resin, thus inducing the as-printed matrix embrittlement. Anyhow, its photopolymerization degree, equal to 67% and 55% for BM and BMC, respectively, was enough to guarantee the printability of both slurries. However, the use of BMC significantly reduced flaw occurrence in the as-printed bodies and the final density of the samples sintered at 1450 °C (without an isothermal step) was increased (approx. 60% and 50% of the theoretical value for BMC and BM, respectively). Thus, the target porosity of the ceramic bodies was guaranteed, and their structural integrity achieved without any increase in sintering temperature but with a simple powder treatment
Effects of date palm and green tea polyphenol extracts on the thermal stability and mechanical properties of poly lactic acid
No full textPoly (lactic acid) (PLA) is a biodegradable polymer whose thermal and mechanical performance can be enhanced through natural additives such as polyphenols. In this study, polyphenols extracted from green tea (Camellia sinensis L.) and date palm (Phoenix dactylifera L., Arecaceae) were incorporated into PLA at concentrations of 1, 5, and 10 wt.% using an internal mixer. The oxidative thermal stability of the blends was examined by thermogravimetric analysis and differential scanning calorimetry, while their morphology and mechanical properties were also characterized. Both polyphenols improved the thermal stability of PLA, with green tea polyphenols showing a greater effect, likely due to their broader range of active compounds. However, increasing polyphenol content reduced the glass transition temperature, tensile strength, and Young’s modulus, while enhancing elongation at break and ductility. These findings indicate that plant-derived polyphenols act as both thermal stabilizers and plasticizers within the PLA matrix
Modulization and Simulation of Thermal Management System Based on Pumped Two-Phase Loop for Hybrid-Electric Aircraft
No full textAn efficient thermal management system (TMS) is essential for ensuring hybrid-electric aircraft (HEA) can handle the significant heat rejection required by electrified propulsion. This paper presents a system-level analysis of a compact P2PL TMS for a 1.4 MW battery generating a 70 kW heat load. A modular modeling method was used to size the key components, and then dynamic simulations were conducted under varying environmental conditions. The results indicate that a compact TMS weighing 22 kg can be developed, with a condenser heat transfer area of 26.20 m2 and operating with a refrigerant mass flow rate of 0.56 kg/s while maintaining low pump power consumption at 22 W. This system can successfully regulate a battery’s temperature so that it remains below 40 °C in both standard (15 °C) and cold (−20 °C) environments. Pressure analysis confirmed the system’s flexibility and its ability to control battery temperature between 27 °C and 38 °C by adjusting the working pressure (6–8 bar). Furthermore, under hot day conditions (40 °C), battery temperature can be maintained at 47.6 °C. Even under extreme conditions (50 °C), the TMS limits the temperature to 57.45 °C, ensuring it stays within the safe operating range
Development and quasi-static experimental calibration of a novel lumped-mass tyre-wheel model for tyre envelope analysis
No full textAccurate tyre modelling is essential for reliable ride-comfort analyses. Typical approaches, however, rely on numerous empirical parameters and complex calibration procedures that limit their physical interpretability and scalability. This study presents a parametric lumped mass tyre-wheel model specifically developed for the analysis of the tyre-enveloping behaviour over uneven terrains. The formulation, implemented in the time-domain, reproduces the structural behaviour of the belt, sidewalls and contact with the road. Model parameters are customised on an electric kick scooter tyre. Quasi-static experimental tests are conducted to identify the overall radial stiffness and the footprint dimensions as a function of the vertical load. An optimisation-based model calibration is designed to match the experimental evidence. The validated model is then used to simulate the tyre crossing cleats with different heights and under various loading conditions. A normalisation framework and a set of performance indicators are introduced to quantitatively assess and compare the tyre-enveloping capability. Results demonstrate that the proposed model provides a physically consistent tool for investigating tyre-road interaction and evaluating ride comfort over uneven road surfaces
Life Cycle Assessment of Graphite, Silicon Composite, and Silicon‐Dominant Anodes for Lithium‐Ion Batteries: Environmental Impacts, Uncertainties, and Supply Chain Considerations
No full textLithium-ion batteries (LIBs) are essential for applications from portable devices to electric vehicles, where higher specific energy and energy density drive innovation. As cathode research moves toward cobalt-free formulations, anode development focuses on incorporating silicon into graphite. Although silicon production is more energy-intensive than synthetic graphite, its superior theoretical capacity (4200 vs. 372 mAh g−1) reduces the material demand for equivalent electrochemical performance. This study assessed the environmental impacts of producing and testing three anode types, graphite (benchmark, ∼350 mAh g−1), silicon composite (10% Si, ∼400 mAh g−1), and silicon-dominant (80% Si, capacity limited at ∼1000 mAh g−1) using Life Cycle Assessment (LCA) at laboratory scale. Results indicated that introducing silicon leads to lower impacts under the investigated conditions across most of the 18 midpoint categories of ReCiPe 2016 (H). Regarding the carbon footprint, CO2 emissions decreased by about 40% (from 1.33 to 0.79 kg CO2-Eq) for the silicon composite and up to 97% (0.04 kg CO2-Eq) for the silicon-dominant electrode. Sensitivity analysis highlighted the importance of supply-chain conditions: adopting a European electricity mix and shorter transport distances led to additional reductions even at gram-scale production. Overall, integrating silicon and optimizing regional supply chains promoted more sustainable LIB production
Cost-Effective and Regenerating Porous Polysulfone-Based Beads Extraction for in Situ Microbial 2-Phenylethanol Recovery
Full text link2-Phenylethanol (2-PE) is a multipurpose aromatic molecule, approved as GRAS, largely used across various industries, including cosmetics and pharmaceuticals. Growing demand and concerns about petroleum-based synthesis drive the need for sustainable alternatives. Microbial biotechnologies offer ecofriendly solutions with high specificity and mild conditions. In this work, porous polysulfone beads (PPBs) are presented as novel 2-PE recovery adsorbents. PPBs show selective absorption of 2-PE without affecting microbial growth, and they are inexpensive, reusable, and sterilizable. According to comparative testing, PPBs achieve high absorption properties reaching 0.004 mg2-PE mgPPB–1 in 24 h when using 200 mg of PPBs with 10 mL of an aqueous 150 mg L–1 2-PE solution. Moreover, the majority is absorbed in the first 5 h, while after 24 h, the absorption is minimal. 2-PE affinity for PPBs in water solution is demonstrated by its partition coefficient K of 8.24, which explains its effective absorption and poor release in water. Ethanol was utilized to desorb 2-PE from PPBs more effectively, and in just 24 h, 98.8% of 2-PE was liberated. Additionally, the material retains selectivity in a complex growth medium and performs consistently throughout several usage cycles. Even at laboratory scale, the life cycle assessment (LCA) of this process shows that it overcomes the industrial extraction methods in terms of environmental impact. These results establish PPBs as viable options for scalable and sustainable 2-PE bioproduction
Mechanical characterization of flexible rockfall barriers through a global multi-component analytical framework
No full textL'abstract è presente nell'allegato / the abstract is in the attachmen
Study of polymeric materials for industrial applications in the field of laser welding
No full textL'abstract è presente nell'allegato / the abstract is in the attachmen
Experimental validation of genetic programming for heat exchanger circuitry optimization
No full textAlthough evolutionary circuitry optimization has been recognized as a cost-effective method in recent research, it remains to be experimentally verified. Accordingly, this study reports on experiments conducted to validate the effectiveness of genetic programming for heat exchanger circuitry optimization. The numerical optimization results of the evaporator are identified for R32 in a capacity range between 3 and 4 kW and for the given airside features, thereby suggesting optimal branching and patterning characteristics obtained by implementing genetic operators through genetic programming for 3.0, 3.5, and 4.0 kW design conditions. Airside design, including fin package, remains unchanged across all investigated capacities. The manufacturability of the optimized solutions is enhanced by introducing additional constraints. Consequently, baseline and optimized heat exchangers are manufactured and tested using dedicated equipment. The test results validate the numerical model, with 66.7 % of the temperature deviation within ±1.0 K and pressure deviations within ±5.0 % of the measured values, as well as verify the benefits achievable through optimized branching and patterning. The optimized configurations at 3- and 4-kW capacity achieve inlet saturation temperatures that are 2.7 K and 4.1 K higher, respectively. The circuitry optimized at 3 kW results in an 18.0 kPa increase in pressure drop, whereas the optimization conducted at 4 kW produces an 83.5 kPa decrease. These effects translate into corresponding improvements of 18.9 % and 12.8 % in the measured coefficient of performance. The results support the development of more accurate simulations and pave the way for the practical implementation of genetic programming for actual product development