As transistor densities surge and boost frequencies intensify transient CPU heat fluxes, passive thermal management with phase change materials (PCMs) offers a zero-power alternative. However, the low thermal conductivity of PCMs demands high-conductivity fins, and no existing study has employed topology optimization to design a multi-layer stacked PCM heat sink for long-duration cooling. The present study's novelty is a four-row PCM heat sink with aluminum fins generated by density-based topology optimization (SIMP, 20% solid fraction, Helmholtz filtering) under steady operating conditions. The optimized geometry is simulated via a transient enthalpy-porosity CFD model resolving conjugate heat transfer, laminar natural convection, and phase change, validated against experimental data (RMSE=2.44 K, NRMSE = 3.26%). Over eight hours of continuous CPU load, sequential melting occurs: the lowest row fully melts in 66 min, the second in 275 min, while the third reaches a liquid fraction of 0.54 and the top remains solid. The heat-sink base temperature stabilizes at 355.72 K (approximate to 82.6 degrees C) after 8 h, which lies near the upper limit of typical commercial CPU operating temperatures, with a difference of only 3.51 K, compared to 388.36 K for a conventional single-layer radial-fin heat sink after just 1 h-a 42.4 K reduction, reflecting the combined effect of the multi-layer configuration and the topologyoptimized fin geometry. Latent heat (2.6 kJ per row) dominates the lower blocks, while natural convection is suppressed to micrometre-per-second velocities.
The major development is an effective electrocatalyst that replaces costly noble metals for scalable, real-time hydrogen production without pollution. We synthesize an interfacial p–n heterojunction Co3O4@ZnWO4 via hydrothermal synthesis and calcination; Mott-Schottky analysis confirms p-n formation, offering versatile electronic properties for catalytic water splitting and electrical energy storage supercapacitor applications. The physicochemical characteristics confirm the structural and interfacial growth of Co3O4 with ZnWO4, strengthening p-n heterojunction formation, therefore enhancing charge transfer and catalytic activity, and yielding considerably lower overpotentials of 23 mV for HER and 190 mV for OER at 10 mA cm−2. In a two-electrode configuration, the Co3O4@ZnWO4//Co3O4@ZnWO4 achieves a lower cell voltage of 1.63 V at 10 mA cm−2. Even after 100 h of continuous operation, the electrolyzer retains its stability, indicating consistent water-splitting behaviour. Furthermore, we analyze the Co3O4@ZnWO4 nanocomposite for energy storage applications, which delivers a specific capacitance of 1005 F g−1; the asymmetric device Co3O4@ZnWO4//PVA-KOH//AC delivers a strong energy density of 53.54 Wh kg−1 and a power density of 4500 W kg−1, with capacitance retention of 89.6% over 10,000 charge-discharge cycles. Moreover, real-time LED illumination studies demonstrate practical applicability.
Abstract In recent years, cities worldwide have faced extreme heat, making it essential to study the geographical characteristics of urban environments to develop sustainable urban strategies. This research employs Landsat data from 1984 to 2024, a ArcGIS Pro (version 3.4.2) and Python (version 3.12.1) to thoroughly analyze spatial changes in surface urban heat island (SUHIs) in subtropical Taipei City. We examined the relationships among the normalized difference vegetation index (NDVI), normalized difference built-up index (NDBI), and land surface temperature (LST) concerning land use and land cover. The results show that the Kappa coefficient for the years 1988, 2001, 2007, and 2022 was 0.93, 0.93, 0.94, and 0.92, respectively. LST increased significantly during the study period, with a maximum increase of 12.2°C from 1984 to 2022. Moreover, the growth rate of building area from 1984 to 2024 was 209.3%; this substantial increase in vertical building development substantially impacted the urban thermal environment. LST showed a moderately strong negative correlation with NDVI and a moderately strong positive correlation with NDBI, with both correlations reaching statistical significance. These findings emphasize the urgency of sustainable urban planning controls, especially in high-temperature and high-humidity climatic conditions, to mitigate the impacts of SUHIs.
Trading strategies are commonly utilized to identify optimal trading signals and mitigate trading volatility. Enforcing a trading strategy to include technical indicators from different categories results in resilient and robust performance. To that end, we take the Diverse Technical Indicator Pool (DTIP) into consideration. This paper proposes a memetic-based optimization algorithm for finding a more diverse technical indicator-based strategy, which enables robust and adaptable performance across varying market regimes. The DTIP ensures that selected technical indicators are drawn from distinct categories: volatility, momentum, volume, and trend, thereby providing resilient signals that resist overfitting. Building on previous research, this study conducts a rigorous comparative analysis of three local search algorithms (FA, PSO, and SA) within the memetic framework. Empirical results from a walk-forward validation on the US, Taiwan, and Cryptocurrency markets demonstrate that SA consistently yields the highest stability and risk-adjusted returns. Furthermore, the proposed framework is shown to significantly outperform a machine learning baseline, particularly in high-volatility assets like Bitcoin, where it reduced volatility while maintaining superior profitability.
Polymer gears are increasingly applied in precision transmission systems due to their low weight, corrosion resistance, and acoustic advantages, although their limited wear resistance continues to restrict long-term durability. To address this limitation, this study investigates epoxy-based composite gears reinforced with metal powders and modified with solid lubricants, aiming to enhance load-bearing and sliding wear performance. Epoxy composites are prepared by incorporating copper, iron, or aluminum powders as mechanical reinforcements and introducing polytetrafluoroethylene (PTFE), molybdenum disulfide, tungsten disulfide, or graphite as solid lubricants to improve lubricity. Ball-on-disc tribological tests under a 2 N normal load and a sliding speed of 0.1 m/s indicate that PTFE-modified composites exhibit the lowest steady-state friction coefficients, reaching 0.203, 0.276, and 0.352 for copper-, iron-, and aluminum-filled systems. Wear track measurements further show substantial reductions in wear depth and width, with PTFE-modified composites demonstrating improvements of 73.93
