Innovation Wing Two

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.

TechTalk – Non-Fourier Phonon Heat Conduction: Ballistic, Coherent, Localized, Hydrodynamic, and Divergent Modes

Innovation Wing Two, TechTalk / By

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.

TechTalk – (RE)-Ba-Cu-O Single Grain Bulk Superconductors with Improved Superconducting and Mechanical Properties

Innovation Wing Two, TechTalk / By

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.

TechTalk – Mechanomaterials: Connecting Mechanics to Materials Innovations and Challenges

Innovation Wing Two, TechTalk / By

The classical subjects of solid mechanics, structural mechanics and mechanics of materials have played important roles in helping develop structural and functional materials, giving rise to recent advances in nanostructured materials, biomedical materials, mechanical metamaterials, soft actuators, flexible electronics, tunable mechanochromics, regenerative mechanomedicine, etc. While these classical subjects often focus on passive access to mechanical properties of materials in existing forms, a paradigm shift, referred to as mechanomaterials, is emerging toward proactive programming of materials’ properties and functionalities during the manufacturing process by leveraging the force–geometry–property relationships. Here, we provide a couple of examples that illustrate this emerging paradigm, which include overcoming some of the long-standing or recent challenges in the developments of fatigue-resistant metals, mechanics-guided shape morphing electronics, strong and switchable adhesives, epicardial patches for the treatment of heart attack and membrane-active nanomedicine.

TechTalk – An Innovative Way of Water Resources Management for Sustainable Development: Utilization of Atmospheric Water Resources

Innovation Wing Two, TechTalk / By

Due to rapid population growth and climate change, there are severe spatiotemporal variations of water resources in the globe, and our society is facing serious challenges in securing sufficient water. To tackle the water shortage, we need to find other water sources. An effective and possible way is to utilize atmospheric water resources, which are the precipitable water in the atmosphere. With relatively stable temporal and spatial distribution, this part of water resources can be exploited and utilized through artificial precipitation enhancement operations which is also known as cloud seeding. In this talk, Professor Chen will introduce the situation of atmospheric water resources and the method that implements low frequency acoustic waves to stimulate and enhance precipitation. Through indoor experimental analysis and a large number of field tests, the effect has been tested. The development and utilization of atmospheric water resources would provide an innovative measure to obtain more freshwater for a certain region. He will also discuss the atmospheric water resources in the Greater Bay Area.

TechTalk – Environmental Materials for Urban Resource Recovery

Innovation Wing Two, TechTalk / By

Substantial material resource recovery opportunities exist in the urban environment to support more sustainable urban development. However, the ability to produce safe and quality recoverable requires in-depth environmental materials studies and state-of-the-art fabrication and characterization technologies. For example, the quantitative X-ray diffraction (QXRD) technique has accurately monitored the transfer and behavior of targeted hazardous metals when being beneficially used for ceramic products in the construction industry. The work of recovering metallic lead from waste cathode ray tube (CRT) glass serves as an excellent example to reflect how environmental materials techniques assisted the development of transforming urban electronic waste into new metal resources. Lastly, the demonstration of recovering phosphorus from wastewater streams as quality slow-releasing fertilizer for agriculture applications leads to new solutions to tackle critical resource challenges with the fast-developing urban mining concept around the world.

TechTalk – A Simple Way of Doing Machine Learning, without Learning

Innovation Wing Two, TechTalk / By

Machine learning and deep neural networks have revolutionized various fields, most obvious examples are computer vision and natural language processing. Apart from the surging sizes of sophisticated models, an emerging trend is to go down the opposite route of deploying lightweight models on the edge (terminal or user end) for relatively simple AI tasks. This is named edge AI which is often constrained to run under restrictive compute and storage resources. In this talk, we will explore the latest theory in neural network modeling that allows the total avoidance of AI training that used to be slow, daunting or even impossible for the edge. Specifically, we will scratch the surface of the neural tangent kernel, and try to establish (well…. qualitatively) the equivalence of data and network, such that once the data are ready, the network is instantly ready, too.

High-voltage Aqueous Mg-ion Battery Facilitated by Water-in-salt Electrolyte

Innovation Wing Two, Second exhibition / By

Although widely used in our daily life, lithium (Li) -ion batteries fall short because the materials used are often scarce, toxic, and expensive. They also have safety issue in operation due to their organic based electrolytes. Beyond lithium-ion batteries, a low-cost magnesium (Mg) metal anode based aqueous Mg-ion battery has been developed first time by Professor Dennis Leung’s research team in the HKU Department of Mechanical Engineering. As Mg is the 5th most abundant metal element in the earth’s crust (three orders of magnitude more than Li), the advantages of low cost and non-toxicity make Mg a desirable alternative to Li as the anode material. The proposed battery shows a high discharge plateau of 2.4-2.0 V and an excellent rechargeability for over 700 stable cycles. This high operation voltage exceeds the counterpart of other multivalent-ion batteries, including zinc (Zn) metal and aluminum (Al) metal batteries. The mechanism behind was also revealed, where a conductive metallic oxide layer was facilitated by the chloride (Cl-) ions inside the water-in-salt electrolyte, providing ionic pathways for rechargeable battery operations. The team hopes that the chemical insights obtained in this work could inspire further optimization and bring attention to the overlooked development of rechargeable aqueous Mg metal batteries. This work uncovers the once dismissed possibility of aqueous Mg metal batteries and opens a new avenue in the field of post-lithium-ion batteries. Other project team members are Dr. Wending Pan (Research Assistant Professor) and Miss Sarah Leong (PhD student).

TechTalk – To See a World in a Grain of Sand: A Geotechnical Researcher’s Perspective

Innovation Wing Two, TechTalk / By

Many large earth structures (e.g. slopes, dams, and artificial islands) are made up of sand or sandy soil. The stability of these structures is a major concern of the public as well as the professional. The bitter memories of the deadly slope failures in Hong Kong in 1972 remind us of the importance of proper stability evaluation. The difficulty in predicting the mechanical behavior of sand and sandy soil mainly comes from the granular nature of these materials. A sand or sandy soil is an assembly of numerous small grains of varying size, shape and even mineral composition. It can exist over a spectrum of states that corresponds to a variety of responses, ranging from fluid-like flow to solid-like strain hardening. The groundwater brings additional difficulty and uncertainty. This talk will present some results and findings yielded from our long-term research endeavor at HKU, which is aimed to advance scientific understanding of the complex behaviors of granular earth materials and thereby provide better engineering solutions. Focus will be placed on the fascinating roles played by the small constituent particles. The significance of these findings to engineering practice will be open to discussion.

Young Scholar TechTalk – Cyber-Physical Spare Parts Intralogistics System for Aviation MRO

Innovation Wing Two, TechTalk / By

Spare parts management is a vital supporting function in aviation Maintenance, Repair,and Overhaul (MRO). Spare parts intralogistics (SPI), the operational perspective of spare parts management, significantly affects performance of MRO activities. This study proposes Cyber-Physical Spare Parts Intralogistics System (CPSPIS) to address the synchronization problems associated with the SPI business process and SPI resources. The proposed system applies Internet-of-Things technologies and unified representations to provide resources and operations traceability and visibility. Further, CPSPIS contributes several services with self-X abilities for real-time synchronization throughout the SPI process. In addition, CPSPIS develops applications and visualization tools for real-time cooperation between execution and decision-making. Finally, this study conducts a real-life case study in one of the largest aviation MRO organizations in Hong Kong, and discusses the quantitative and qualitative improvements of CPSPIS.