Open microchannels are a promising configuration for flow boiling because the top gap facilitates vapor evacuation and liquid replenishment, thereby improving thermal performance and moderating flow instabilities. However, their behavior under different inlet subcooling conditions remains insufficiently understood under hydrostatically controlled inlet-head operation, particularly when water is used as the working fluid. Deionized water flow boiling was experimentally investigated in an open microchannel heatsink featuring a 100 μm top gap and microstructures with an aspect ratio of 15 and a length of 50 mm. Experiments were conducted at four prescribed hydrostatic heads (from 45 to 85 cm) at three different inlet temperatures: 60, 75 and 90 ºC. Quantitative thermohydraulic measurements were complemented by high-speed flow visualization. Raising inlet temperature from 60 to 90 ºC reduced the heat flux at the onset of nucleate boiling (ONB) by 73–79%, whereas the critical heat flux (CHF) decreased by only 19–34%. Consequently, the two-phase operating window widened and was largest at 90 ºC. The lowest subcooling condition yielded the highest heat transfer performance, with maximum heat transfer coefficients of 12,847–23,686 W/m2·K under surge-like vapor motion, but also the sharpest pre-CHF deterioration. This wider operating window incurred hydraulic and dynamic penalties: pressure drop increased by up to 335% from ONB to CHF and, at 102 W/cm2 under the highest hydrostatic-head condition, pressure drop oscillation severity increased by 169%. Increasing hydrostatic head from 45 to 85 cm more than doubled the ONB flow rate, whereas lower subcooling accelerated flow rate depletion and fluctuations toward CHF.
In dynamical systems on networks, one assigns the dynamics to nodes, which are then coupled via links. This approach does not account for group interactions and dynamics on links and other higher dimensional structures. Higher-order network theory addresses this by considering variables defined on nodes, links, triangles, and higher-order simplices, called topological signals (or cochains). Moreover, topological signals of different dimensions can interact through the Dirac-Bianconi operator, which allows coupling between topological signals defined, for example, on nodes and links. Such interactions can induce various dynamical behaviors, for example, periodic oscillations. The oscillating system consists of topological signals on nodes and links whose dynamics are driven by the Dirac-Bianconi coupling, hence, which we call it Dirac-Bianconi driven oscillator. Using the phase reduction method, we obtain a phase description of this system and apply it to the study of synchronization between two such oscillators. This approach offers a way to analyze oscillatory behaviors in higher-order networks beyond the node-based paradigm, while providing a ductile modeling tool for node- and edge-signals.
Marine habitats in the Mediterranean Sea play a vital role in supporting biodiversity, ecosystem functioning and services, and climate resilience. However, they are facing escalating threats from anthropogenic pressures. This study, coordinated and financially supported by the Specially Protected Areas Regional Activity Centre (SPA/RAC) under the Barcelona Convention, presents an updated, harmonized assessment of the distribution and protection status of three iconic benthic habitats: Posidonia oceanica meadows, coralligenous assemblages, and marine caves. A standardized methodology was applied to compile, review, harmonize, and aggregate fine-scale data from regional databases, National Focal Points (NFPs), expert networks, and online repositories. Posidonia oceanica meadows were mapped over 22,379 km(2) across 15 Mediterranean countries, with 95% within territorial waters and 37% in Marine Protected Areas (MPAs). Coralligenous assemblages and ma & euml;rl beds covered 2,889.5 km(2) in 13 countries, in line with previous modelling estimates, with 67.1% located within MPAs, particularly in the central and western regions. Approximately 3,000 marine caves were identified across 15 countries, representing the first country-level spatial inventory of this habitat. Nearly 69% of known caves are located in MPAs, although lacking specific conservation measures. Despite significant progress, notable limitations remain. Data quality and availability are uneven across regions, and inconsistencies in classification, spatial resolution, and ecological descriptors-especially for coralligenous assemblages and marine cave typologies-limit detailed habitat representation. This study highlights persistent knowledge gaps in parts of North Africa, the Eastern Mediterranean, and non-EU coastal states, and provides a robust baseline for conservation planning and supports regional monitoring efforts under the Barcelona Convention. Future priorities include addressing data gaps, standardizing classification systems, prioritizing sites for conservation and restoration to strengthen marine habitat protection and recovery and enhance the ecological effectiveness of MPAs.
Nowadays, the need to reduce the industry’s energy demands means that green concerns must be incorporated as performance indicators. In scheduling, this translates into decision makers willing to sacrifice, to a certain point, production-related criteria, such as meeting delivery deadlines, in favour of reducing energy consumption. The exact degree of compromise can be difficult to set a priori; instead, the expert may only be able to provide some vague production goals that need to be achieved before dealing with energy savings. The decision maker’s task is further complicated in many real-world problems due to the presence of uncertainty in some of the parameters. In this paper, we tackle a flexible job shop scheduling problem with uncertain task durations, minimising the total weighted tardiness while also considering the total energy consumption. In this setting, when there is a clear hierarchy between multiple objectives, a lexicographical goal programming approach seems natural but has the caveat of needing well-defined target values a priori. Therefore, we propose a new hierarchical multiobjective adaptive strategy to work in a lexicographic goal programming setting where only vaguely defined goals are provided. This strategy is then embedded in a memetic algorithm. Extensive experimentation shows that the proposed adaptive strategy is more suitable for the problem at hand than a purely lexicographic and a traditional lexicographic goal programming strategy, and it constitutes an excellent complement to Pareto-based methods.
The dehydration of ethylene glycol-water mixtures is a relevant challenge in the recovery and reuse of cooling liquids from industrial processes, particularly in the pharmaceutical sector. This work investigates the feasibility of using pervaporation with a hydrophilic polymeric membrane (PERVAP 4101, based on highly cross-linked poly-(vinyl alcohol)) to partially dehydrate mixtures containing up to 70 wt% water and maintain compositions close to the eutectic point (≈58 wt% ethylene glycol). Experimental tests were conducted in a laboratory-scale pervaporation unit at 60, 70, and 80 °C. The influence of feed composition and temperature on permeation flux, separation factor, and long-term stability was analyzed. A conditioning stage at 80 °C was found to be essential to achieve steady operation, resulting in high water selectivity (98.9-99.8 wt% water in permeate) and stable fluxes up to 4.2 kg m-2 h-1 during 30 h continuous tests. ATR-FTIR spectra of the pristine and conditioned membranes revealed only minor structural modifications, suggesting a slight reduction in crystallinity associated with increased permeability, which was later confirmed by DSC analysis. The experimental data were successfully correlated using a solution-diffusion model, considering the dependence of permeance on component activity and temperature. The apparent activation energies for water and ethylene glycol permeation were 34-42 and 43-58 kJ mol-1, respectively. Results confirm that PERVAP 4101 membranes provide an efficient and stable route for ethylene glycol dehydration at high water contents, demonstrating potential for industrial implementation.
