All current studies on impingement-cooled plate-fin heatsinks adopt a vertically-downward inlet flow for simplicity. Further with assumption of a uniform flow, semi-empirical correlations can be derived for the pressure drops and convection heat transfer coefficients for single-channel analysis. However, such approaches overlooked the non-uniformity and rotationality of the flow field generated by an axial fan. Hence, these correlations can be unreliable in predicting the performance of the impingement-cooled plate-fin heatsink. In this study, the non-uniform and rotational flow provided by the axial impingement fan was modeled and the heatsink performance was analyzed numerically and compared with experimental results. The current practice of using uniform impingement flow is found to under-estimate the differences between the average base temperature and the ambient temperature by 15.4-17.9 % and the Sopt by 50-70 %, in comparison with the numerical results. The distributions of air velocity, convection heat transfer coefficient, pressure, and fin temperature for the rotational fan flow are demonstrated and discussed.
As safety-critical human–computer interaction (HCI) systems increasingly rely on sustained attention and rapid decisions, realistic operational noise may shape how operators perform and interact with interfaces. This study examined the effects of mixed operational noise—simulated Air Force radio communication (speech) combined with wireless radio static—on performance, interaction behavior, and subjective response during a simulated radar-based threat-detection task. Thirty active-duty military personnel completed the task under three noise intensity levels (50, 60, and 70 dB) in a within-subject design. One-way ANOVAs revealed a significant effect of noise level on reaction time and visual search behavior. Post hoc comparisons indicated that the high-noise condition (70 dB) not only prolonged reaction times but also significantly increased response variability, indicating behavioral instability. Furthermore, a marked rise in the number of observed threat targets suggests that operators adopted compensatory visual strategies to maintain accuracy under auditory stress. In contrast, repeated-measures ANOVA showed no significant differences in subjective ratings across noise conditions. Together, the findings suggest a dissociation between objective performance and subjective experience; operators may suffer from performance degradation and instability without consciously perceiving increased disturbance. These results highlight the critical risk of “hidden” cognitive costs and support the need for objective performance monitoring in acoustic design for mission-critical environments such as control rooms and military monitoring systems.
BACKGROUND:Hairdressers often reuse disposable gloves, yet the effect of repeated washing on protection against oxidative hair-dye sensitizers is unclear. OBJECTIVES:To determine how reuse and wash type influence the permeation of p-phenylenediamine (PPD) and aminophenols through natural-rubber-latex (NRL) and neoprene gloves. METHODS:Closed-loop ASTM F739 tests (27°C) were run for five consecutive 8-h exposures, each followed by either a water-only rinse or a detergent wash. Breakthrough time (BT), steady-state permeation rate (PR) and cumulative permeated mass (CPM) were quantified; linear mixed models were used to evaluate the effects of reuse day, wash type and concentration. RESULTS:NRL failed after one reuse; by Day 5, CPM reached 110 μg, and BT shortened. Neoprene maintained BT > 2 h across two reuse cycles; however, by Day 5, CPM increased by 41 μg. Wash type did not affect BT, PR, or CPM (p > 0.05). In NRL, each 1% (w/v) concentration increment shortened BT by 1.1 min and increased PR by 0.037 μg/cm2 min; no concentration effect was observed in neoprene. CONCLUSIONS:Barrier performance was governed more by the reuse cycle than the rinse chemistry. Reuse of single-use gloves is not recommended because repeated use and cleaning reduce their protective performance.
We present results over an 11-year Solar cycle of cosmic antiprotons based on 1.1×10^{6} events in the rigidity range from 1.00 to 41.9 GV. The p[over ¯] fluxes exhibit distinct properties. The magnitude of the p[over ¯] flux temporal variation is significantly smaller than those of p, e^{-}, and e^{+}. A hysteresis between the p[over ¯] fluxes and the p fluxes is observed, whereas the p[over ¯] and e^{-} fluxes show a linear correlation. With a model-independent analysis, we found a universal relation between the shape of the rigidity spectrum and the magnitude of flux temporal variation over an 11-year Solar cycle for both positively and negatively charged particles. The simultaneous results on p[over ¯] and p, e^{-}, and e^{+} provide unique information for understanding particle transport in the Solar System as a function of mass, charge, and spectral shape.
We present the first measurement of cosmic-ray fluxes of Li6 and Li7 isotopes in the rigidity range from 1.9 to 25 GV. The measurements are based on 9.7×105 Li6 and 1.04×106 Li7 nuclei collected by the Alpha Magnetic Spectrometer on the International Space Station from May 2011 to October 2023. We observe that over the entire rigidity range the Li6 and Li7 fluxes exhibit nearly identical time variations and, above ∼4 GV, the time variations of Li6, Li7, He, Be, B, C, N, and O fluxes are identical. Above ∼7 GV, we find an identical rigidity dependence of the Li6 and Li7 fluxes. This shows that they are both produced by collisions of heavier cosmic-ray nuclei with the interstellar medium and, in particular, excludes the existence of a sizable primary component in the Li7 flux.
