Influence of friction stir welding conditions on joinability of oxide dispersion strengthened steel / F82H ferritic/martensitic steel joint

AbstractAs one of the joining methods for the reduced activation materials to realize the fusion reactors with high efficiency in the future, friction stir welding (FSW) is selected for fabricating the dissimilar butt joint between oxide-dispersion strengthened (ODS) alloy and F82H, and the effect of FSW conditions on joinability of this dissimilar joint was examined. The sound dissimilar joint can be produced under the condition that ODS plate is set on the advancing side and the FSW tool is plunged into F82H. As for the mild steel backside plate, the sound joint can be fabricated in the case of 150rpm rotational speed and 50mm/min traveling speed. On the other hand, by employing the silicon nitride backside plate, the total heat input should be decreased to obtain the sound joint, where the traveling speed is 100 or 150mm/min and rotational speed is 150rpm. In addition, the finite element heat conduction analyses indicate that the influence of traveling speed on the joinability with the mild steel backside plate seems to be smaller than that with the silicon nitride plate and the allowable range of the appropriate traveling speed for the joint becomes to be wider by employing the silicon nitride backside plate

Decoding distributed oscillatory signals driven by memory and perception in the prefrontal cortex.

Sensory perception and memory recall generate different conscious experiences. Although externally and internally driven neural activities signifying the same perceptual content overlap in the sensory cortex, their distribution in the prefrontal cortex (PFC), an area implicated in both perception and memory, remains elusive. Here, we test whether the local spatial configurations and frequencies of neural oscillations driven by perception and memory recall overlap in the macaque PFC using high-density electrocorticography and multivariate pattern analysis. We find that dynamically changing oscillatory signals distributed across the PFC in the delta-, theta-, alpha-, and beta-band ranges carry significant, but mutually different, information predicting the same feature of memory-recalled internal targets and passively perceived external objects. These findings suggest that the frequency-specific distribution of oscillatory neural signals in the PFC serves cortical signatures responsible for distinguishing between different types of cognition driven by external perception and internal memory

原型炉のための技術基盤確立に向けた日本の取組

The establishment of technology bases required for the development of a fusion demonstration reactor (DEMO) has been discussed by a joint effort throughout the Japanese fusion community. The basic concept of DEMO premised for investigation has been identified and the structure of technological issues to ensure the feasibility of this DEMO concept has been examined. The Joint-Core Team, which was launched along with the request by the ministerial council, has compiled analyses in two reports to clarify technology which should be secured, maintained, and developed in Japan, to share the common targets among industry, government, and academia, and to activate actions under a framework for implementation throughout Japan. The reports have pointed out that DEMO should be aimed at steady power generation beyond several hundred thousand kilowatts, availability which must be extended to commercialization, and overall tritium breeding to fulfill self-sufficiency of fuels. The necessary technological activities, such as superconducting coils, blanket, divertor, and others, have been sorted out and arranged in the chart with the time line toward the decision on DEMO. Based upon these Joint-Core Team reports, related actions are emerging to deliberate the Japanese fusion roadmap

Development of Strategic Establishment of Technology Bases for a Fusion DEMO Reactor in Japan

The strategic establishment of technology bases required for the development of a fusion demonstration reactor (DEMO) has been discussed by joint endeavors throughout the Japanese fusion community. The mission of Fusion DEMO is to demonstrate the technological and economic feasibility of fusion energy. The basic concept of Fusion DEMO has been identified and the structure of technological issues to ensure the feasibility of this DEMO concept has been examined. The Joint-Core Team consisting of experts from the Japanese fusion community including industry has pointed out that DEMO should be aimed at steady power generation beyond several hundred thousand kilowatts, availability which must be extensible to commercialization, and overall tritium breeding sufficient to achieve fuel-cycle self-sufficiency. The necessary technological issues and activities have been sorted out along with 11 identified elements of DEMO, such as superconducting coils, blanket, divertor, and others. These will be arranged within a time line to lead to the Japanese fusion roadmap

Spatial distribution of attentional modulation at columnar resolution in macaque area V4

Attention to a location in a visual scene affects neuronal responses in visual cortical areas in a retinotopically specific manner. Optical imaging studies have revealed that cortical responses consist of two components of different sizes: the stimulus-nonspecific global signal and the stimulus-specific mapping signal (domain activity). It remains unclear whether either or both of these components are modulated by spatial attention. In this study, to determine the spatial distribution of attentional modulation at columnar resolution, we performed cerebral blood volume (CBV)-based optical imaging in area V4 of monkeys performing a color change detection task in which spatial attention was manipulated. We found that spatial attention enhanced global signals of the hemodynamic responses, but did not affect stimulus-selective domain activities. These results indicate the involvement of global signals in neural processing of spatial attention. We propose that global signals reflect the neural substrate of the normalization pool in normalization models of attention

Comparison and validation of the lattice thermal conductivity formulas used in equilibrium molecular dynamics simulations for binary systems

The Green-Kubo relations have been widely utilized in equilibrium molecular dynamics (MD) simulations to evaluate the lattice thermal conductivity (TC) of condensed matter. In previous studies, however, three different formulas have been used to calculate the TC. In the present study, focusing on binary systems, we investigate differences among the three TC formulas to evaluate the appropriateness of each formula and estimate possible errors. First, by using theoretical means, the differences are explicitly expressed in terms of material properties such as the Maxwell-Stefan (MS) diffusion coefficient, the partial specific enthalpy, and the reduced heat of transport. Subsequently, MD simulations are conducted to quantify the differences over wide temperature ranges in Li2O and TiO2 model systems including crystal, amorphous and liquid phases. The results show that although the three TC formulas give virtually identical results at low temperatures, one TC formula may cause significant errors at high temperatures when the MS diffusion coefficient reaches approximately 10−6–10−7 cm2/s. These large diffusion coefficients usually occur in liquid phases, often occur in amorphous and super-ionic crystal phases, and may occur in defective systems. Finally, a simple equation to roughly estimate the error in this TC formula is derived