OPT: optimal human visual system-aware and power-saving color transformation for mobile AMOLED displays

Organic light-emitting diode (OLED) displays have a high power efficiency; however, the frequent use of user interaction-based applications such as instant messengers, video players, and games contributes strongly to the total power consumption. The power consumption varies significantly depending on the display contents, and thus, color transformation, which is a representative low-power technique, is used for OLED displays. Previously developed low-power color transformation methods have not been thoroughly researched for satisfying the human visual system and have not considered optimal visual satisfaction and power consumption simultaneously. In this paper, a novel low-power color transformation approach is proposed, which is aimed at simultaneously optimizing both visual satisfaction and power consumption. In addition, it is implemented on an active-matrix OLED (AMOLED) display-based Android smartphone at runtime. Experimental results show that the proposed technique achieves better human visual satisfaction and shows up to 22.32% power saving on average on the AMOLED display and offers 6.23% more extended battery life over that of an existing leading technique.

     

Effect of Texture and Temperature on Strain-Induced Martensitic Transformation in 304 Austenitic Stainless Steel

The austenitic stainless steel's remarkable mechanical properties are caused by twinning-induced plasticity and transformation-induced plasticity mechanisms. Numerous studies focus on stacking fault energy's effect, which is affected by various factors, to interpret and control these mechanisms. However, crystallographic orientation is also an important parameter for mechanical properties in metals. This study compares the mechanical properties and microstructural features of 304 austenitic stainless steel, focusing on the effect of initial texture and deformation temperature. Microstructural characterization is identified by an interrupted tensile test based on strain, tensile direction, and temperature conditions, and X-ray diffraction and electron back-scattered diffraction analysis are performed. The results show that the mechanical features and strain-induced martensitic transformation rate depend on the tensile directions. In addition, this trend is maintained irrespective of the temperature conditions. The attribute reason is that the difference in the Taylor factor and the formation rate of the deformed band structure is induced by the initial crystallographic orientations. Moreover, a decrease in temperature significantly increases the dislocation densities and abundant twins and transformed martensites formation. Furthermore, the yield and tensile strengths are enhanced while the elongation decreased with the tensile strains.     

Numerical Simulations and In Situ Optical Microscopy Connecting Flow Pattern,Crystallization, and Thin-Film Properties for Organic Transistors with Superior Device-to-Device Uniformity

Currently, due to the lack of precise control of flow behavior and the understanding of how it influences thin-film crystallization, strict tuning of thin-film properties during solution-based coating is difficult. In this work, a continuous-flow microfluidic-channel-based meniscus-guided coating (CoMiC) is introduced, which is a system that enables manipulation of flow patterns and analysis connecting flow pattern, crystallization, and thin-film properties. Continuous supply of a solution of an organic semiconductor with various flow patterns is generated using microfluidic channels. 3D numerical simulations and in situ microscopy allow the tracking of the flow pattern along its entire path (from within the microfluidic channel to near the liquid–solid boundary), and enable direct observation of thin-film crystallization process. In particular, the generation of chaotic flow results in unprecedented device-to-device uniformity, with coefficient of variation (CV) of 7.3% and average mobility of 2.04 cm² V⁻¹ s⁻¹ in doped TIPS-pentacene. Furthermore, CV and average mobility of 9.6% and 11.4 cm² V⁻¹ s⁻¹ are achieved, respectively, in a small molecule:polymer blend system. CoMiC can serve as a guideline for elucidating the relation between flow behavior, liquid-to-solid phase transition, and device performance, which has thus far been unknown.