Fast charging of lithium-ion batteries at subzero temperatures is limited by increased polarization, reduced charge acceptance, and accelerated degradation. This study develops and validates a combined preheating framework for commercial 21700 NMC811/graphite cells by integrating adaptive internal pulse-current heating with external phase-change composite (PCC)-based heating. Experiments were conducted at initial SOC levels of 30%, 50%, and 80% under −20°C ambient conditions. A control-oriented equivalent-circuit model, parameterized using hybrid pulse power characterization and electrochemical impedance spectroscopy data, was coupled with a three-dimensional thermal model to predict temperature rise, thermal non-uniformity, and energy demand. A voltage-constrained adaptive pulse-current strategy maximized internal heat generation while limiting the absolute SOC drift to within 0.43%. Combined preheating outperformed internal-only and external-only approaches across all SOC levels. At 30% SOC, the strategy raised the cell above 35°C in about 15 min, achieved a heating rate of 3.61°C/min, reduced preheating time by about 30%, and decreased the temperature difference from 2.5°C to 0.9°C. After 200 equivalent full cycles (EFC) at −20°C, the combined-preheated cell retained 86% state of health, compared with 50% for the unheated cell.
The long-range delocalization of electrons in macrocyclic compounds, such as porphyrins and phthalocyanines, allows for tuning the electronic properties of domains that utilize these chemicals as building blocks. This approach has rapidly become a powerful platform for preparing diverse electroactive materials for electrochemical applications. To that end, in this review, we outline the most recent advancements in design, synthesis, and computational modeling of porphyrin-based frameworks. Herein, we highlight innovative synthetic approaches that are utilized to both enhance the structural stability and porosity of the materials and control the microenvironment of their catalytic sites. These approaches include post-synthetic modification, metal coordination, and hierarchical assembly. Key focus areas of research, including the use of these materials as electrocatalysts and capacitors, are highlighted. The expansion in the utility of these materials in environmental remediation applications, such as carbon dioxide capture, photocatalytic degradation of pollutants, and selective adsorption of heavy metals, underscores the versatility of the porphyrin-based materials across many disciplines.
Embodied learning posits that all concepts, including mathematical concepts, are understood in a perceptual and body-based manner. The coordination of action and language processes can allow students to articulate mathematical insights in a generalizable way, as learners create embodied artifacts of their mathematical reasoning. We examined high school students creating poses that corresponded to conjectures about quadrilaterals. Pose creation consisted of creating a novel sequence of arm motions to capture key relations in a mathematical conjecture. Activities were embedded in a technology-enhanced motion capture system using digital avatars. We examined the types of poses students created and their relation to geometric understandings, emergence of students’ understanding throughout the activities, and differences in performance. We found that students created poses both to illustrate the objects and relations in the conjecture and to show why conjectures were true, and that these pose sequences showed both diversity and consistency across student groups. We observed instances of mathematical insight emerging through pose creation, particularly as students stabilized embodied representations across collaborative interaction. We found that gesturally embodied argumentation, often spurred by pose creation was a process through which meaning could be produced. We also found gestures to be a way to negotiate mathematical terminology, and this negotiation was often a precursor to pose creation. Implications for theories of embodied learning and the design of learning environments are given.
This study investigates the seismic response of an idealized monopile-supported wind-turbine system embedded in a dry granular deposit using the discrete-element method (DEM). The model is intended as a mechanism-oriented representation rather than a design model for a specific commercial turbine class. A 100 g numerical-centrifuge similitude is used to retain prototype stress levels while reducing the computational domain. The framework is evaluated through building-block checks of soil small-strain properties, tower response, and one-dimensional free-field amplification. Harmonic base motions with frequencies from 1 Hz to 5 Hz, together with an earthquake record used at its original and amplitude-scaled levels, are applied to the coupled soil-monopile-tower model. The low-amplitude free-field response peaks near 2 Hz, where the DEM surface amplification factor is 6.3, compared with 5.45 from a linear analytical baseline. Structural demand, localized soil strain, and settlement also increase when the input contains strong energy near this soil-deposit frequency. Contact-force resultants are further used to construct segment-level lateral, shaft, and base load-transfer-type relationships, providing insight into cyclic hysteresis, depth-dependent load redistribution, and permanent deformation. The results indicate a soil-dominated coupled amplification mechanism rather than pure tower resonance. Because the study considers one dry-soil configuration, uses scaled particles, and does not include pore-pressure generation, the findings are interpreted as relative trends and micromechanical evidence rather than site-specific design predictions.
This study examines the static and seismic performance of sandy slopes containing 30
