The electropulsing anisotropy of pre-twinned AZ31 Mg alloy was investigated via quasi-in-situ electron backscatter diffraction analysis to decouple the thermal and athermal effects of electropulsing treatment. A pre-compression along the rolling direction (RD) introduced extensive {10−12} extension twins, yielding a twinned area fraction of 75.4%. Three consecutive electropulses were applied along the RD or the transverse direction (TD), with the durations tailored to maintain comparable peak temperatures. The TD specimens exhibited higher heating efficiency owing to the predominant a-axis current path preserved in both matrix and twinned regions despite twinning-induced lattice rotation. A finite difference simulation based on the c-axis orientation distribution predicted an electrical resistivity ratio in excellent agreement with the experimental value. Quasi-in-situ tracing revealed that strain-induced boundary migration governed the early stage of microstructural evolution, while nucleation and growth gradually became activated during subsequent cycles; thermally activated twin boundary migration was suppressed under the subsecond thermal exposure. Notably, the RD specimens underwent faster grain growth and twin boundary annihilation than the TD counterparts, contrary to predictions based on grain morphology and texture. This anomalous behavior was ascribed to current crowding in the twinned regions, where the lower resistivity along the c-axis locally amplified the athermal effect, as evidenced by preferential static recovery under a short-duration electropulse. The RD specimens recovered more ductility (up to 71%) than the TD counterparts (19%). This ductility recovery was governed primarily by the deformation behavior associated with the tensile direction and further enhanced by the accelerated microstructural evolution in the RD specimens, which delayed the onset of plastic instability.
This study examines how destination brand equity was distributed across the PyeongChang 2018 Olympic period. A matched panel of 502 U.S.-based target-market respondents evaluated South Korea approximately three months before and three months after the Games. The post-event measure intentionally captured evaluations attributed by respondents to hosting the Games and is therefore interpreted as an early event-attributed response rather than a causal Olympic effect. Separate-wave latent profile analyses, supported by focused four-versus-five-state validation, retained five ordered destination-brand-equity states. Average destination brand equity was higher at the post-event observation (mean difference = .340), but this positive net difference coexisted with substantial between-person heterogeneity. A fixed-criterion regression-to-the-mean benchmark reproduced the small residual net direction but not the observed volume of gross bidirectional redistribution, while reliable-change analysis indicated that most respondents did not exceed a conservative change threshold. After baseline adjustment, media consumption and hosting appraisal were positively associated with the postevent score, whereas their interaction was not significant. The findings show why aggregate brand tracking and individual-level diagnostics should be interpreted jointly and distinguish early event-attributed responses from durable mega-event legacy.
Urea is a vital nitrogen fertilizer for global food security; however, its production remains carbon-intensive owing to heavy reliance on fossil fuel–based H2. To reduce the carbon emissions of the urea production process, capturing CO2 from the flue gas has emerged as a promising strategy. However, this strategy faces several critical limitations. First, the captured CO2 from flue gas undergoes incomplete conversion into urea, causing inherent carbon losses. Second, conventional air combustion requires substantial fuel consumption, leading to thermodynamic inefficiencies. Finally, absorption-based capture approach causes high thermal energy penalties. To address these issues, this study proposes hybrid urea production processes that introduce solid oxide electrolysis and utilize oxy-fuel combustion within the natural gas-based process. CO2F, fully utilizing internally captured CO2, and CO2E, supplementing external CO2, were compared with the base case employing amine-based absorption with partial utilization of the captured CO2. The proposed processes maximized the carbon valorization efficiency, reduced fuel consumption, eliminated high thermal energy consumption for solvent regeneration, and achieved high CO2 capture rates. CO2F and CO2E achieved a levelized cost of urea as 409.7 $/tUrea and 440.3 $/tUrea, lower than 468.4 $/tUrea for the base case. CO2E demonstrated superior environmental performance, achieving a global warming potential of 348.8–462.8 gCO2-eq./kgUrea, including process direct, indirect and upstream emissions. Notably, under the broader greenhouse gas emission boundary, CO2E achieved a higher probability of being economically feasible under variable carbon taxes, credits, and electricity prices.
This study experimentally investigated the wall friction characteristics of single-phase water flow in vertical annular channels of a natural circulation loop under mixed convection conditions at elevated temperatures. Experiments were conducted in annular test sections with gaps of 2.9, 5, and 7 mm at 30 bar for a Reynolds number (Re) range of 663-5003. Under these low-velocity mixed convection conditions, the wall friction factor increased with increasing annular gap size and inlet fluid temperature, and decreased with increasing flow velocity. Over the investigated Richardson number (Ri) range of 0.13-4.86, the wall friction factor increased up to approximately nine times the corresponding forced convection value. As Ri decreased and inertial effects became dominant, the friction factor approached the forced convection prediction. This behavior is consistent with buoyancy-induced modification of the velocity profile and the resulting changes in near-wall shear, coupled with temperature-dependent fluid-property variations. A machine-learning-based analysis identified Ri, the viscous dissipation parameter (N), and the Prandtl number (Pr) as the most influential dimensionless parameters governing wall friction enhancement. Based on these results, a new correlation was developed to predict wall friction factors. The applicability ranges of the proposed correlation are 0.13 <= Ri <= 4.86, 7.91 & times; 10(-)(9) <= N <= 3.17 & times; 10(-)(8), and 1.15 <= Pr <= 2.72. The experimental dataset provides a valuable benchmark for the development and validation of wall friction models under mixed convection conditions, and the proposed correlation enables improved prediction of wall friction factors within the present experimental range.
