Research for the Optimal Flux-Cored Arc Welding Process of 9% Nickel Steel Using Multi Object Optimization with Solidification Crack Susceptibility

The environment of the global shipbuilding market is changing rapidly. Recently, the International Maritime Organization (IMO) has tightened regulations on sulfur oxide content standards for marine fuels and tightened sulfur oxide emission standards for the entire coastal region of China to consider the environment globally and use LNG as a fuel. There is a tendency for the number of vessels to operate to increase significantly. To use cryogenic LNG fuel, various pieces of equipment, such as storage tanks or valves, are required, and equipment using steel, which has excellent impact toughness in cryogenic environments, is required. Four steel types are specified in the IGG Code, and 9% Ni steel is mostly used for LNG fuel equipment. However, to secure safety at cryogenic temperatures, a systematic study investigating the causes of quality deterioration occurring in the 9% Ni steel welding process is required and a discrimination function capable of quality evaluation is urgent. Therefore, this study proposes a plan where the uniform quality of 9% Nickel steel is secured by reviewing the tendency of the solidification crack susceptibility among the quality problems of cryogenic steel to establish the criteria for quality deterioration and to develop a system capable of quality discrimination and defect avoidance

Induced astigmatism biases the orientation information represented in multivariate electroencephalogram activities

© 2021 The Authors. Human Brain Mapping published by Wiley Periodicals LLC.A small physical change in the eye influences the entire neural information process along the visual pathway, causing perceptual errors and behavioral changes. Astigmatism, a refractive error in which visual images do not evenly focus on the retina, modulates visual perception, and the accompanying neural processes in the brain. However, studies on the neural representation of visual stimuli in astigmatism are scarce. We investigated the relationship between retinal input distortions and neural bias in astigmatism and how modulated neural information causes a perceptual error. We induced astigmatism by placing a cylindrical lens on the dominant eye of human participants, while they reported the orientations of the presented Gabor patches. The simultaneously recorded electroencephalogram activity revealed that stimulus orientation information estimated from the multivariate electroencephalogram activity was biased away from the neural representation of the astigmatic axis and predictive of behavioral bias. The representational neural dynamics underlying the perceptual error revealed the temporal state transition; it was transiently dynamic and unstable (approximately 350 ms from stimulus onset) that soon stabilized. The biased stimulus orientation information represented by the spatially distributed electroencephalogram activity mediated the distorted retinal images and biased orientation perception in induced astigmatism.11Nsciescopu

Frontal-to-visual information flow explains predictive motion tracking

Predictive tracking demonstrates our ability to maintain a line of vision on moving objects even when they tem-porarily disappear. Models of smooth pursuit eye movements posit that our brain achieves this ability by directly streamlining motor programming from continuously updated sensory motion information. To test this hypoth-esis, we obtained sensory motion representation from multivariate electroencephalogram activity while human participants covertly tracked a temporarily occluded moving stimulus with their eyes remaining stationary at the fixation point. The sensory motion representation of the occluded target evolves to its maximum strength at the expected timing of reappearance, suggesting a timely modulation of the internal model of the visual target. We further characterize the spatiotemporal dynamics of the task-relevant motion information by computing the phase gradients of slow oscillations. We discovered a predominant posterior-to-anterior phase gradient immedi-ately after stimulus occlusion; however, at the expected timing of reappearance, the axis reverses the gradient, becoming anterior-to-posterior. The behavioral bias of smooth pursuit eye movements, which is a signature of the predictive process of the pursuit, was correlated with the posterior division of the gradient. These results suggest that the sensory motion area modulated by the prediction signal is involved in updating motor programming.11Nsciescopu

Effect of Divided Exhaust Period in a High Efficiency TGDI Engine

The divided exhaust period (DEP) concept was applied to a high-efficiency gasoline engine and its impact on various engine performance aspects were investigated. To this end, key design parameters of DEP components were optimized through 1-D engine simulation. The designed DEP components were fabricated and experimental verification was performed through an engine dynamometer test. The developed DEP engine shows suitable performance for electrified vehicles, with a maximum thermal efficiency of 42.5% as well as a wide sweet spot area of efficiency over 40%. The improvement in thermal efficiency was mainly due to a reduction in pumping loss. Notably, the reduction in pumping loss was achieved under high exhaust gas recirculation (EGR) flow conditions, where further improvements in fuel consumption could be achieved through a synergistic combination of DEP implementation and high dilution combustion. Furthermore, a significantly improved catalyst light-off time, uncharacteristic in turbocharged engines, was confirmed through a simulated cold-start catalyst heating engine test

Controlled Grafting of Colloidal Nanoparticles on Graphene through Tailored Electrostatic Interaction

Nanoparticle/graphene hybrid composites have been of great interest in various disciplines due to their unique synergistic physicochemical properties. In this study, we report a facile and generalized synthesis method for preparing nanoparticle/exfoliated graphene (EG) composites by tailored electrostatic interactions. EG was synthesized by an electrochemical method, which produced selectively oxidized graphene sheets at the edges and grain boundaries. These EG sheets were further conjugated with polyethyleneimine to provide positive charges at the edges. The primary organic ligands of the colloidal nanoparticles were exchanged with Cl- or MoS42- anions, generating negatively charged colloidal nanoparticles in polar solvents. By simple electrostatic interactions between the EG and nanoparticles in a solution, nanoparticles were controllably assembled at the edges of the EG. Furthermore, the generality of this process was verified for a wide range of nanoparticles, such as semiconductors, metals, and magnets, on the EG. As a model application, designed composites with size-controlled FeCo nanoparticle/EG were utilized as electromagnetic interference countermeasure materials that showed a size-dependent shift of the frequency ranges on the electromagnetic absorption properties. The current generalized process will offer great potential for the large-scale production of well-designed graphene nanocomposites for electronic and energy applications

Synthesis of high quality 2D carbide MXene flakes using a highly purified MAX precursor for ink applications

The practical application of 2D MXenes in electronic and energy fields has been hindered by the severe variation in the quality of MXene products depending on the parent MAX phases, manufacturing techniques, and preparation parameters. In particular, their synthesis has been impeded by the lack of studies reporting the synthesis of high-quality parent MAX phases. In addition, controllable and uniform deposition of 2D MXenes on various large-scale substrates is urgently required to use them practically. Herein, a method of pelletizing raw materials could synthesize a stoichiometric Ti3AlC2 MAX phase with high yield and processability, and fewer impurities. The Ti3AlC2 could be exfoliated into 1???2-atom-thick 2D Ti3C2Tx flakes, and their applicability was confirmed by the deposition and additional alignment of the 2D flakes with tunable thickness and electrical properties. Moreover, a practical MXene ink was fabricated with rheological characterization. MXene ink exhibited much better thickness uniformity while retaining excellent electrical performances (e.g., sheet resistance, electromagnetic interference shielding ability) as those of a film produced by vacuum filtration. The direct functional integration of MXenes on various substrates is expected to initiate new and unexpected MXene-based applications