Science Daily May 30, 2023 Researchers in Japan numerically demonstrated an inverse design of a structure for camouflaging the location of a sound source as if the sound emanated from a different location. They used a topology optimization approach used in acoustic elastic coupled problems, the difference between the sound pressure fields emanating from an actual source and a virtual source, was the objective function infimized in camouflaging the sound source. Optimal topologies of elastic structures made of acrylonitrile butadiene styrene were designed for the camouflaging purpose, acoustic metamaterials were not used. The metastructures (source-shifters) were expressed at the design […]
Tag Archives: S&T Japan
Eruption of Tonga underwater volcano found to disrupt satellite signals halfway around the world
Phys.org May 22, 2023 Equatorial plasma bubbles which impact satellite-based communications was observed in the Asia-Pacific region after the eruption of the Tonga volcano on January 15, 2022. Researchers in Japan used satellite and ground-based ionospheric observations to demonstrate that an air pressure wave triggered by the Tonga volcanic eruption could cause the emergence of an equatorial plasma bubble. The most prominent observation result showed a sudden increase of electron density and height of the ionosphere several ten minutes to hours before the initial arrival of the air pressure wave in the lower atmosphere. They also found that the propagation […]
High-quality 2D films could be one-drop away
EurekAlert May 19, 2023 The effective application of 2D materials is strongly dependent on the mass production of high-quality large area 2D thin films. Researchers in Japan demonstrated a strategy for the automated manufacturing of high-quality 2D thin films using a modified drop-casting approach. They used an automated pipette to drop a dilute aqueous suspension onto a substrate heated on a hotplate, and controlled convection. Liquid removal caused the nanosheets to come together to form a tile-like monolayer film in 1–2 min. Ti0.87O2 nanosheets were utilized as a model system for investigating the control parameters such as concentrations, suction speeds, […]
Improving alloys: Researchers successfully establish a strong mechanical bond of immiscible iron and magnesium
Phys.org April 17, 2023 Steel is heavy, and scientists are turning to alternatives in the quest to improve the safety and speed of transportation, while simultaneously lessening its environmental footprint. Joining of Mg alloy to steel has received wide attention for design of multi-materials. Researchers in Japan have described joining of immiscible pure iron and pure magnesium (Fe–Mg), as a simplified model, performed by solid metal dealloying (SMD) between Mg and Fe100−xNix interlayers that were preliminary joined to the Fe part by diffusion bonding. SMD formed an Fe–Mg bicontinuous composite with interconnected morphology at the Fe–Mg weld interface. The effect […]
Storing information with spins: Creating new structured spin states with spatially structured polarized light
Phys.org March 27, 2023 So far, only uniformly polarized light has been exploited to control electron spins. However, if the polarization has an additional spatial structure it can produce spatially structured electron spins, opening up new ways to store information. Researchers in Japan devised a method for generating spatially structured electron spins using a structured light with spatially varying polarization profile. They transferred spatially variant polarization of topologically structured light to the spatial spin texture in a semiconductor quantum well. The electron spin texture was directly excited by a vector vortex beam with a spatial helicity structure. The spin texture […]
Novel tunable 2D nanosheets enable many semiconductor applications, ranging from electronics to photocatalysis
Nanowerk March 15, 2023 Perovskites is a promising material for producing 2D monolayer nanosheets if their tunability of bandgap corresponding to the energy of visible light. To solve this problem researchers in Japan focused on a Ruddlesden–Popper (RP) phase layered perovskite oxynitrides and successfully created 2D perovskite oxynitride nanosheets with a tunable bandgap using their novel process. The material had a homogenous thickness of 1.6 nm and exhibited different colors, ranging from white to yellow, depending on the nitridation temperature, and exhibited the semiconductor property of having a tunable bandgap in the visible region, ranging from 2.03-2.63 eV, based on […]
Neural networks could help predict destructive earthquakes
Phys.org March 3, 2023 The movement and deformation of the Earth’s crust and upper mantle provide critical insights into the evolution of earthquake processes and future earthquake potentials. Crustal deformation can be modeled by dislocation models that represent earthquake faults in the crust as defects in a continuum medium. Researchers in Japan have proposed a physics-informed deep learning approach to model crustal deformation due to earthquakes. Neural networks can represent continuous displacement fields in arbitrary geometrical structures and mechanical properties of rocks by incorporating governing equations and boundary conditions into a loss function. They introduced polar coordinate system to accurately […]
Scientists thread rows of metal atoms into nanofiber bundles
Phys.org March 6, 2023 A class of 3D atomic wires of transition metal chalcogenides (TMC) structures consisting of bundles of TMC nanofibers held together by metallic atoms in between the fibers, all forming a well-ordered lattice in its cross section are of particular interest. Depending on the choice of metal, the structure could even be made to become a superconductor. Researchers in Japan demonstrated versatile method to fabricate indium (In)-intercalated W6Te6 (In–W6Te6) bundles with a nanoscale thickness. Atomic-resolution electron microscopy revealed that In atoms were surrounded by three adjacent W6Te6 wires. First-principles calculations suggested that their wire-by-wire stacking can transform […]
Fickle winters in East Asia caused by major shift in regional atmospheric circulation, suggests study
Phys.org February 27, 2023 Researchers in Japan investigated the structure and dynamics of two distinct patterns. They showed that the winter climate over East Asia is influenced by two teleconnection patterns, the western Pacific pattern, and the Southeast Asia-Japan pattern. Using meteorological data for winters from 1974 to 2021 they established the baseline climate and analyzed anomalous departures from that baseline. In the first half of the 2020/2021 winter season, an anticyclonic circulation anomaly appeared over the southeastern Tibetan Plateau, and a corresponding cyclonic anomaly occurred over northern Japan. This pattern was associated with enhanced convection over the South China […]
Improving the performance of satellites in low Earth orbit
EurekAlert February 21, 2023 Although small satellites have a lot of potential due to their smaller size, they have lesser radiation shield and the deployable membrane attached to the main body for a large phased-array transceiver causing non-uniform radiation degradation across the transceiver. This affects the gain variation and performance of the satellite. To mitigate radiation degradation researchers in Japan created a phased-array transceiver with on-chip distributed radiation sensors which can detect the gain variation between the chips of the antenna. This was combined with current-sharing techniques to mitigate the gain variation and thus reduce the impact of non-uniform ionizing […]