Mini-light-emitting diodes (mini-LEDs) were combined with multiple three-dimensional (3D) diffuse reflection cavity arrays (DRCAs) to produce thin, large-area, high-brightness, flat light source modules. The curvature of the 3D free-form DRCA was optimized to control its light path; this increased the distance between light sources and reduced the number of light sources used. Experiments with a 12.3-inch prototype indicated that 216 mini-LEDs were required for a 6 mm optical mixing distance to achieve a thin, large-area surface with high brightness, uniformity, and color saturation of 23,044 cd/m2, 90.13%, and 119.2, respectively. This module can serve as the local dimming backlight in next generation automotive displays.
Corrosion behaviors of X80 pipeline steel were investigated in different simulated alkaline soil solution using electrochemical test, EDS coupled to SEM and weight loss method. The results showed uniform corrosion was happened on X80 steel in Shanshan and Hami simulated solution, and local corrosion was the main failure mode for X80 steel in Yumen simulated solution. The ranking of corrosion rate of X80 steel from the biggest in simulated solution was Hami, Shanshan and Yumen. With the increasing of immersion time, a dense Ca2+ deposited layer was formed on the surface of X80 steel, which could inhibiting the Cl- effects on the corrosion of X80 steel in Shanshan and Hami solution. The SO42- competition absorbed effect could provide certain corrosion protection for X80 steel in Yumen solution at the early corrosion stage.
Consider material machinability and lattice mismatch sapphire as substrates for the ultraviolet-C light-emitting diodes (UV-C LEDs) are commonly used, but their high refractive index can result in the total internal reflection (TIR) of light whereby some light is absorbed, therefore caused reducing light extraction efficiency (LEE). In this study, we propose a method to optimize the thickness of a sapphire substrate light guide layer through first-order optical design which used the optical simulation software Ansys SPEOS to simulate and evaluate the light extraction efficiency. AlGaN UV-C LEDs wafers with a light guide layer thickness of 150–700 μm were used. The simulation proceeded under a center wavelength of 275 nm to determine the optimal thickness design of the light guide layer. Finally, the experimental results demonstrated that the initial light guide layer thickness of 150 μm the reference output power of 13.53 mW, and an increased thickness of 600 um resulted in output power of 20.58 mW. The LEE can be increased by 1.52 times through light guide layer thickness optimization. We propose a method to optimize the thickness of a sapphire substrate light guide layer through first-order optical design. AlGaN UV-C LEDs wafers with a light guide layer thickness of 150–700 μm were used. Finally, the experimental results demonstrated that the LEE can be increased by 1.52 times through light guide layer thickness optimization.
Threshold stress in constant load tests and critical stress inconstant strain tests for sulfide stress corrosion cracking (SCC) of seven tubular steels were measured. Percent reduction in area loss caused by SCC of four tubular steels also were measured. Results showed there was no interrelationship among the three parameters for sulfide SCC. The threshold stress for hydrogen-induced delayed failure during charging in the sulfuric acid (H 2 SO 4 ) solution in the constant load test decreased linearly with the logarithm of the concentration of diffusible hydrogen for four tubular steels. Threshold stresses obtained during dynamic charging with the current corresponding to the diffusible hydrogen concentration during immersing in hydrogen sulfide (H 2 S) solution were consistent with the threshold stresses for sulfide SCC. Therefore, the threshold stress for sulfide SCC can be measured using dynamic charging in the H 2 SO 4 solution.
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