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In this work, we introduce DyESP, a novel approach that unites dynamic exploration with space pruning to expedite the combined search of hyperparameters and architecture, enhancing the efficiency and accuracy of hyperparameter-architecture search (HAS). Central to DyESP are two innovative components: a meta-scheduler that customizes the search strategy for varying spaces and a pruner designed to minimize the hyperparameter space by discarding suboptimal configurations. The meta-scheduler leverages historical data to dynamically refine the search direction, targeting the most promising areas while minimizing unnecessary exploration. Meanwhile, the pruner employs a surrogate model, specifically a fine-tuned multilayer perceptron (MLP), to predict and eliminate inferior configurations based on static metrics, thereby streamlining the search and conserving computational resources. The results from the pruner, which identifies and removes underperforming configurations, are fed into the meta-scheduler. This process updates the historical dataset used by the meta-scheduler, enabling it to adjust the exploration degree and refine the sampling strategy for subsequent iterations. This integration ensures the meta-scheduler is continually updated with relevant data, allowing for more accurate and timely adjustments to the exploration strategy.Experiments on various benchmarks show that DyESP outperforms existing methods in terms of both speed and stability on almost all benchmarks. 

ABSTRACT The Earth's ionosphere plays a critical role in radio wave transmission, reflection, and scattering, directly affecting communication, navigation, and positioning systems. However, the comprehensive impacts of space weather remain to be fully established in cases where the ionosphere experiences strong disturbances during geomagnetic storms. We reported unprecedented observational evidence of extreme ionospheric electron density depletion and its hemispheric asymmetry during the May 10–12, 2024 super geomagnetic storm, utilizing multi-instrument ground-based and spaceborne in-situ observations. The ionospheric electron density significantly decreased, with a maximum reduction of 98% over the whole northern hemisphere for more than 2 days, causing backscatter echo failures in multiple ionosondes within the Chinese Meridian Project (CMP) monitoring network. In contrast, mid-to-low latitude regions in the southern hemisphere exhibited electron density enhancements. Thermosphere-Ionosphere-Electrodynamics General Circulation Model (TIEGCM) simulations demonstrated strong consistency with northern hemispheric observations. The vertical drift and the column integrated ratio of O and N2 (ΣO/N2) from observations and simulations indicated the deep reduction of total electron content (TEC) mainly generated by severe ion recombination associated with neutral composition changes that interacted with the disturbed electric field. The summer to winter neutral wind and asymmetry of O/N₂ were possibly responsible for the asymmetry in electron density between the northern and southern hemispheres. These results advance understanding of ionospheric storm physics by establishing causal links between magnetosphere-thermosphere coupling processes and extreme electron density variations, while providing critical observational constraints for space weather model refinement. 

Herein, this work aims to demonstrate the topological effect on the mechanicalx characteristics of selfassembled block copolymers (BCPs). The lamellae-forming polystyrene- block -polydimethylsiloxane (PSb -PDMS) can be self-assembled into various nanostructured monoliths with the use of PS-selective solvent for solvent annealing, giving diamond, gyroid, and cylinder structures with increasing the swelling degree of PS domain (the effective volume fraction of the PS segment after solvent annealing followed by evaporation). The stiffness of the self-assembled monoliths is scrutinized by nanoindentation test. For intrinsic PS- b -PDMS monolith with lamellar structure, the reduced elastic modulus as calculated from the measured stiffness is 0.91 GPa. By contrast, the PS- b -PDMS monolith with cylinder structure gives a significant reduction in reduced elastic modulus with the value of 0.52 GPa due to the introduced microporosity to the PS domain from solvent annealing using PS-selective solvent, resulting in the lower confrontation for continuous layer-by-layer deformation of hard PS and soft PDMS domains. In the case of gyroid-structured PS- b -PDMS monolith, it is unexpected to exhibit a significant increase in the reduced elastic modulus with a value of 1.6 GPa: note that the effect of microporosity is still significant. Accordingly, the enhancement of the reduced elastic modulus is attributed to the effect of deliberate structuring with network topology ( i.e., three-dimensional co-continuous hard PS and soft PDMS domains) that is able to hold the occurrence of large-scale deformation. In contrast to the gyroid with a three-strut texture, the diamond-structured PS- b -PDMS monolith with a four-strut texture is superior to the gyroid with a reduced elastic modulus of 2.2 GPa, further confirming the suggested topology effect. 

Surfaces with micrometer-scale pillars have shown great potential in delaying the boiling crisis and enhancing the critical heat flux (CHF). However, physical mechanisms enabling this enhancement remain unclear. This knowledge gap is due to a lack of diagnostics that allow elucidating how micro-pillars affect thermal transport phenomena on the engineered surface. In this study, for the first time, we are able to measure time-dependent temperature and heat flux distributions on a boiling surface with engineered micro-pillars using infrared thermometry. Using these data, we reveal the presence of an intra-pillar liquid layer, created by the nucleation of bubbles and partially refilled by capillary effects. However, contrarily to conventional wisdom, the energy removed by the evaporation of this liquid cannot explain the observed CHF enhancement. Yet, predicting its dry out is the key to delaying the boiling crisis. We achieve this goal using simple analytic models and demonstrate that this process is driven by conduction effects in the boiling substrates and, importantly, in the intra-pillar liquid layer itself. Importantly, these effects also control the wicking flow rate and its penetration length. The boiling crisis occurs when, by coalescing, the size of the intra-pillar liquid layer becomes too large for the wicking flow to reach its innermost region. Our study reveals and quantifies unidentified physical aspects, key to the performance optimization of boiling surfaces for cooling applications. 

Abstract We reveal and justify, both theoretically and experimentally, the existence of a unifying criterion of the boiling crisis. This criterion emerges from an instability in the near-wall interactions of bubbles, which can be described as a percolation process driven by three fundamental boiling parameters: nucleation site density, average bubble footprint radius and product of average bubble growth time and detachment frequency. Our analysis suggests that the boiling crisis occurs on a well-defined critical surface in the multidimensional space of these parameters. Our experiments confirm the existence of this unifying criterion for a wide variety of boiling surface geometries and textures, two boiling regimes (pool and flow boiling) and two fluids (water and liquid nitrogen). This criterion constitutes a simple mechanistic rule to predict the boiling crisis, also providing a guiding principle for designing boiling surfaces that would maximize the nucleate boiling performance.