This study reports the development of a brush-distributed metal oxide nanostructure, in which zinc oxide (ZnO) nanorods are grown on electrospun lanthanum (La)-doped tin oxide (SnO2) nanofibers for enhanced ethanol sensing. The La-doped SnO2 nanofibers are first fabricated through electrospinning, followed by calcination treatment. La incorporation significantly enhances the sensing performance of the pure SnO2 nanofibers by facilitating dehydrogenation and oxidation of hydrocarbons, while simultaneously increasing the number of active sites on the surface of semiconductor oxides. The ZnO nanorods are then grown on the La-doped SnO2 nanofibers to form the La-doped SnO2/ZnO brush-distributed nanostructures via the hydrothermal method. The incorporation of ZnO plays a dominant role in enhancing the sensing performance of the La-doped SnO2 nanofibers by generating additional oxygen vacancies and increasing the specific surface area. The La-doped SnO2/ZnO brush-distributed nanostructures were comprehensively characterized in terms of its morphology, structure, and composition using FESEM, XRD, and EDS analyses. The experimental results showed that the optimal sensing performance was observed for the La-doped SnO2/ZnO brush-distributed nanostructures with 2 mol% La, which achieved a sensitivity of 10.77 in response to 100 ppm ethanol at an operating temperature of 300(degrees)C. The ethanol gas sensor exhibited a response time of 8 s and a recovery time of 20
Copper indium gallium selenide (CIGS) thin-film solar cells are a leading technology for next-generation photovoltaics due to their high absorption coefficients and tunable electronic properties. However, achieving optimal device performance via scalable methods like magnetron sputtering is critically dependent on precise stoichiometric control of the quaternary absorber layer, which remains a significant challenge. We fabricated CIGS thin films by sputtering from two distinct targets, one slightly Cu-poor and one Cu-rich, followed by a rapid thermal selenization process. We found that annealing at 500 °C for 30 minutes is optimal for producing highly crystalline films with minimal secondary phases. Devices fabricated using the Cu-poor target achieved a power conversion efficiency of 4.6
This study investigates thermo fluid coupling mechanisms governing temperature distribution and thermal stress evolution in Solid Oxide Electrolyzer Cells (SOEC) under varying operating conditions. A multiphysics model integrating electrochemistry, gas flow and diffusion, heat transfer, and thermo mechanical response is developed to examine the effects of operating temperature, steam ratio, air flow rate, and flow configuration on electrolysis performance, internal temperature fields, and stress distributions. The numerical model is validated against the experimental data of Tu et al., showing a maximum polarization curve deviation of 9.84%. Results show that increasing operating temperature from 973 K to 1073 K raises current density by approximately 31.7%, while increasing peak temperature by about 11.5% and electrolyte tensile stress from 439.9 MPa to 518.6 MPa. Increasing the cathode side steam fraction from 60% to 90% improves current density by about 11.7%, with minor increases in peak temperature below 1% and stress near 1%. Increasing the anode side air flow rate from 10 sccm to 50 sccm reduces temperature spread and decreases maximum electrolyte tensile stress by approximately 7%. These results highlight the role of thermo fluid interactions in temperature gradient development and thermal stress evolution in SOECs.
Human longevity has been experiencing its largest increase since the end of World War II, and modeling the mortality rates is often the focus of many studies. Among all mortality models, the Lee-Carter model is a popular approach since it is easy to use and has good accuracy in predicting mortality rates. However, empirical studies from several countries have shown that the age parameters of the Lee-Carter model are not constant in time. Many modifications of the Lee-Carter model have been proposed to deal with this problem, including adding an extra cohort effect and adding another period effect. In this study, we propose a spatial modification of the Lee-Carter model and use simulation results to explain why the proposed approach can be used to deal with the problem of the age parameters. Mortality rates are usually recorded by age and time, and thus we can treat mortality rates as two-dimensional values and apply tools of spatial analysis to them. For example, clusters are areas with unusually higher (or lower) mortality rates than their neighbors and we use popular cluster detection methods, such as Spatial scan statistics, to evaluate where there are locations with mortality rates that cannot be described well by the Lee-Carter model. We first use computer simulation to demonstrate that the cluster effect is a possible source causing the problem of the age parameters not being constant and adding the cluster effect can solve the nonconstant problem. We also apply the proposed approach to mortality data from several countries including Japan, France, the United States, and Taiwan. The empirical results show that our approach has better fitting results and smaller mean absolute percentage errors than the Lee-Carter model.
Given the importance of national defense, recruiting volunteers has become a crucial issue in the military’s building and preparation for warfare. This study aims to contribute to existing academic literature and recommend improving military recruitment and marketing strategies. Analyzing responses from 491 eligible young individuals of military age, the study first reveals that the army’s image greatly influences the likelihood of volunteering for military service. However, military career identity was found to mediate/moderate the relationship, as the direct effect of army’s image on WVM became non-significant when accounting for military career identity. In addition, the independent sample t-test results show that career-oriented advertising appeals are more effective than national defense advertising appeals for WVM. Further moderation analysis reveals that advertising appeals do not moderate the relationship between the army’s image and WVM. These findings offer important insights into the military’s recruitment strategies.
