TechTalk

TechTalk – Rational Approach for Seismic Analysis of Long Underground Tunnels Based on 2.5D Formulation

Innovation Wing Two, TechTalk / By

This lecture presents a rational procedure for the seismic analysis of underground tunnels using recorded free-field earthquakes based on the 2.5D finite/infinite element approach. The near and far fields of the half space are modeled by finite and infinite elements, respectively. Using the 1D wave theory, the nodal force and displacement on the near-field boundary are computed for each spectral frequency of the earthquake. Then, equivalent seismic forces are computed for the near-field boundary for the imposition of earthquake spectrum. By assuming the soil-tunnel system to be uniform along the tunnel axis, the 2.5D approach adopted can duly account for the wave transmission along the tunnel axis, which reduces to the 2D case for infinite transmission velocity. The horizontal and vertical components of the 1999 Chi-Chi Earthquake (TCU068) are adopted as the free-field motions in the numerical analysis. The maximal stresses and distribution patterns of the tunnel section under the P- and SV-waves are thoroughly studied by the 2.5D and 2D approaches, which should prove useful to the design of underground tunnels. Comments on the idea to extend the present approach to include the effect of overlying water, such as the case for the sites below reservoirs, rivers, or sea, will also be pointed out.

Young Scholar TechTalk – Flexible Learning of Quantum States with Generative Query Neural Networks

Innovation Wing Two, TechTalk / By

Deep neural networks are a powerful tool for the characterization of quantum states. Existing networks are typically trained with experimental data gathered from the specific quantum state that needs to be characterized. In this talk, Mr. Yan Zhu, from Department of Computer Science, will introduce a model of network that can be trained with classically simulated data from a fiducial set of states and measurements, and can later be used to characterize quantum states that share structural similarities with the states in the fiducial set. With little guidance of quantum physics, the network builds its own data-driven representation of quantum states, and then uses it to predict the outcome statistics of quantum measurements that have not been performed yet. The state representation produced by the network can also be used for tasks beyond the prediction of outcome statistics, including clustering of quantum states and identification of different phases of matter.

TechTalk – Scalable Nanoprinting for Nanophotonics Computing Platform

Innovation Wing Two, TechTalk / By

Photonic platforms with multiplexing capabilities are of profound importance for high-dimensional information processing. In this talk, Professor Nicholas X. Fang will present their recent effort on advancing scalable nanoprinting methods compatible with nanophotonic computing platforms. In the first part, Professor Nicholas X. Fang will discuss an efficient and cost-effective grayscale stencil lithography method to achieve material deposition with spatial thickness variation, for spatially resolved amplitude and phase modulation suitable for flat optics and metasurfaces. The design of stencil shadow masks and deposition strategy offers arbitrarily 2D thickness patterning with low surface roughness. The method is applied to fabricate multispectral reflective filter arrays based on lossy Fabry–Perot-type optical stacks with dielectric layers of variable thickness, which generate a wide color spectrum with high customizability. Grayscale stencil lithography offers a feasible and efficient solution to overcome the thickness-step and material limitations in fabricating spatially thickness-varying structures. In the second part, they show that selective ion doping of oxide electrolyte with electronegative metals shows promise to reproducible resistive switching that are critical for reliable hardware neuromorphic circuits. Based on density functional theory calculations, the underlying mechanism is hypothesized to be the ease of creating oxygen vacancies in the vicinity of electronegative dopants due to the capture of the associated electrons by dopant midgap states and the weakening of Al-O bonds. These oxygen vacancies and vacancy clusters also bind significantly to the dopant, thereby serving as preferential sites and building blocks in the formation of conducting paths. They validate this theory experimentally by implanting different dopants over a range of electronegativities in devices made of multiple alternating layers of alumina and WN and find superior repeatability and yield with highly electronegative metals, Au, Pt, and Pd. These devices also exhibit a gradual SET transition, enabling multibit switching that is desirable for analog computing.

TechTalk – The Metaverse Heatwave

Innovation Wing Two, TechTalk / By

It may not be an overstatement that most of us using the internet has heard of metaverse. The term ‘metaverse’ has seen to stir up global hype for business opportunities and fantasy for mankind, if not became the Oxford Word of the Year 2022 – a word reflecting the ethos, mood, or preoccupations, one that has potential of lasting cultural significance. Metaverse describes a virtual reality environment in which users interact with one another’s avatars and their surroundings in an immersive way. We are going to explore what metaverse meant for us, its fantasy and reality, and the development in the current hype. Experience of exploration and creation of the metaverse is shared and lesson learnt, and takeaway is discussed.

TechTalk – Meta-materials for Sustainability

Innovation Wing Two, TechTalk / By

Micro/nanostructured materials offer significantly new opportunities for high-efficiency devices and systems for energy harvesting, conversion and storage. There is, however, a tremendous gap between the proof-of-principle demonstrations at the small scale and the intrinsically large-scale real-world energy systems and sustainable applications. In this talk, Professor Yin will give an overview of our research and, more specifically, present our recent development on how structured photonic materials address the challenge of the tremendous power hungry for space cooling and promote photosynthesis and crop yield in greenhouses.

TechTalk – Innovation in MRI: Back to the Future?

Innovation Wing Two, TechTalk / By

This year MRI celebrates the 50th anniversary of P. Lauterbur’s seminal discovery paper on MR imaging published on March 16, 1973. The first human sized scanners producing ‘proof of principle’-images were based on homemade magnets with a typical field strength of ~ 0.05 Tesla. First commercial MRI machines appeared in the early 80s with field strength approaching 0.5 Tesla. Sounds familiar ? Today MRI at 0.05 and at 0.5 Tesla are back as ‘hot topics’ in the current developments. The presentation will present the ‘then and now’ of MRI and discuss opportunities from ongoing technological developments to demonstrate that these trends are not just a revival of previous work, but open up new ways into the future of MRI.

TechTalk – Understanding the Turkey-Syria Earthquakes with Methane Gas Refined Fault Theory of Tectonic Earthquakes

Innovation Wing Two, TechTalk / By

At 4:17 am (Turkey time), Feb. 6, 2023, a damaging Mw 7.8 (or 8.0) earthquake struck southern and central Turkey and western Syria and was followed by many aftershocks including an unusually powerful Mw 7.8 (or 7.5) that occurred at 13:24. The earthquakes caused widespread damage including collapsing of many buildings. So far over 11,000 deaths were reported. Figures were projected to rise dramatically by World Health Organization.
In this Teck Talk, Professor Yue will present his understanding of the causes of the earthquakes and the associated building collapses using his methane gas refined fault theory of tectonic earthquakes. Each earthquake involved a rapid release of highly compressed methane gas expansion energy that was previously stored in deep aperture of rock fault zone. The highly compressed gas mass can rapidly expand, rupture, penetrate, and flow from the deep fault zone to shallow ground at a speed of 3 to 1 km/s. The rapid gas flow and expansion in fault rock zone generate massive seismic waves and induce huge concentrated damage to localized grounds and buildings. The earthquake is a cooling process since the gas expansion absorbs heat and cools the surrounding materials in the ground and sky, which can cause local weather changes including the occurrence of air temperature drop-down, rainfall and/or snow.

TechTalk – Adaptable AI-enabled Robots to Create a Vibrant Society – Moonshot R&D Program in Japan –

Innovation Wing Two, TechTalk / By

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.

TechTalk – Search and Rescue in Rubble Piles

Innovation Wing Two, TechTalk / By

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.

TechTalk – Defect Tolerant Brain-inspired Computing with Memristors

Innovation Wing Two, TechTalk / By

Human brain can perform many tasks much better than classical electronic computers, such as face recognition, reasoning based on vague information, and learning from experience, to name a few. Recently, brain-inspired algorithms have promoted in the rapid development of artificial intelligence, however, they cannot work well in classical computers. In this talk, Dr. Can Li will present his recent works on building brain-inspired computers to fit better with brain-inspired algorithms. Those computers are based on an emerging nanoelectronics device – a memristor – which can store information and compute simultaneously, similar to synapses and neurons in our brain. The built hardware can function similar to human brains, for example, it can tolerate hardware defects, make full use of the nonlinearity of devices, learn from rare samples, and so on.