TechTalk

This talk introduces our Moonshot project which is a project in the National Research and Development (R&D) program in Japan. The Moonshot program promotes high-risk, high-impact R&D aiming to achieve ambitious Moonshot Goals and solve issues facing future society such as super-aging populations. Our project is accepted under the Moonshot Goal 3: Realization of AI robots that autonomously learn, adapt to their environment, evolve in intelligence, and act alongside human beings, by 2050. Our project aims to create adaptable AI-enabled robots available in a variety of places. We are now developing a variety of assistive robots called the Robotic Nimbus which can change their shape and form according to the user’s condition, environment, and the purpose of the task, and provide appropriate assistance to encourage the user to take independent action.

Disaster response is an important area where robotics has to be applied intensively. Residents are sometimes left in rubble piles in destroyed buildings and soils in many natural disasters like earthquakes and landslides. The search-and-rescue process is slow and inefficient because of high-risk and demanding situations. This talk will introduce the achievement of research and development of serpentine robots led by the speaker. Active Scope Camera (ASC) is a soft serpentine robot that adapts its configuration to the complex shape of debris and moves by ciliary vibration drive. It was used at some disaster sites in the world. The new version of the ASC levitates and moves by adding an air-jet drive. Its vision, auditory and tactile sensing capability supports the teleoperation of its long body. Its performance was tested at first responder’s training sites and actual disasters.

Beyond the Fourier diffusion theory on heat conduction, the classical size effects—the Casimir regime—caused by phonon boundary scattering is well known and extensively studied. However, over the last three decades, new regimes beyond the Fourier and the Casimir pictures of heat conduction have been demonstrated. In this talk, I will discuss different phonon heat conduction regimes, including the Knudsen regime, the hydrodynamic regime, the quantization regime, the coherence and localization regimes, and the divergence regime. The Knudsen regime expands Casimir’s picture to many other quasi-ballistic transport geometries, and is being exploited to develop phonon mean free path spectroscopy techniques. Phonon hydrodynamic transport happens when the normal scattering dominates over the resistive scattering, which is a condition difficult to satisfy and only observed at a narrow temperature range less than 20K. However, our recent experiments have observed second sound—a consequence of phonon hydrodynamic transport—at as high at 200K, while simulations point to possibility of observing hydrodynamic heat conduction even at room temperature. Quantized phonon transport was observed at very low temperatures. Signatures of coherent heat conduction, including localization, will be discussed, together with experimental evidences. Divergent thermal conductivity, implying thermal superconductors, is predicted to be possible in low-dimensional materials, although no experiments have provided conclusive evidence. These different phonon heat conduction regimes will be summarized in a regime map, demonstrating the rich phonon transport physics rivaling that of electrons.

Extensive research has been carried out over the last three decades, in general, and over last 10 years, in particular, to produce single-grain, high-performance RE-Ba-Cu-O [(RE)BCO bulk superconductors, where RE is a rare earth element or yttrium, for a variety of high field engineering applications. Sample assemblies of bulk (RE)BCO bulk superconductors reinforced under different configurations, remarkably, have enabled trapped fields of more than 17.5 T to be achieved, which is the current world record. More recently, hybrid (RE)BCO bulk superconductors containing Ag, composite and fibre-reinforcements are being developed specifically for both conventional, static devices and more challenging engineering applications where the presence of large electromagnetic stresses has been of concern for the operation of these ceramic-like materials. This seminar will describe the key developments in the processing and properties of high-performance, state-of-the-art (RE)BCO bulk superconductors with a view to develop practical applications over the next 5 years.