Oversea speaker

TechTalk – Quantitative Predictive Theories through Integration of Quantum, Statistical, and Irreversible Thermodynamics

August 28, 2023 (Monday) 2-3pm
Thermodynamics is a science concerning the state of a system, whether it is stable, metastable, or unstable. Its derivatives to natural variables give fundamental physico-chemical properties of the system. It is historically divided into four categories: equilibrium thermodynamics by Gibbs, statistical thermodynamics by Gibbs and Landau, irreversible thermodynamics by Onsager and Prigogine, and quantum mechanics. The development of density function theory (DFT) enabled the quantitative prediction of properties of the ground state of a system from quantum mechanics. Their integration into predictive theories will be discussed in this presentation along with future perspectives. It will be shown that the zentropy theory combines the bottom-up DFT predictions with the revised top-down statistical thermodynamics, while the theory of cross phenomena keeps the entropy production due to irreversible processes in the combine law of thermodynamics to revise the Onsager flux equations. The zentropy theory is capable of quantitatively predicting free energy landscape, singularity and emergent divergences of properties at critical point free of parameters, while the theory of cross phenomena can predict the coefficients of internal processes between non-conjugate variables.

TechTalk – Theoretical Concepts and Innovative Laboratory Techniques for Estimating the Effective Permeability of Rocks: Applications to the Longyou Claystone

The Longyou Caves represent an important historical site in China that has undergone periodic water level changes over several centuries. The ground water flow through the intact rock and fractures is an important factor in the geotechnical assessment of the site. The Environmental Geomechanics Laboratory at McGill University has focused on the development of innovative theoretical approaches and experimental facilities for wide range of rocks including Indiana Limestone, the Cobourg Limestone, the Vermont Granite and the Lac du Bonnet Granite, using both steady state and transient techniques. In this Teck Talk, Professor Selvadurai will present a range of experimental techniques, their theoretical interpretations that can be used to estimate of fluid transport processes through intact rocks that can be described by Darcy’s law. The theoretical and experimental techniques are used to determine the intact permeability of Longyou claystone recovered from the site.

TechTalk – Organic Neuromorphic Materials and Devices

By integrating sensing, memory and processing functionalities, biological nervous systems are energy and area efficient. Emulating such capabilities in artificial systems is, however, challenging and is limited by the device heterogeneity of sensing and processing cores., Here, we present a universal solution to simultaneously perform multi-modal sensing, memory and processing using organic electrochemical transistors. The device has a vertical traverse architecture and a crystalline–amorphous channel that can be selectively doped by ions to enable two reconfigurable modes: volatile receptor and non-volatile synapse. As a volatile receptor, the device is capable of multi-modal sensing, and as a non-volatile synapse, it is capable of 10-bit analogue states, low switching stochasticity and good state retention. Homogeneous integration of such devices enables functions such as conditioned reflex and real-time cardiac disease diagnose via reservoir computing, illustrating the promise for future edge AI hardware.

TechTalk – AI for Science: From Scientific Discoveries to Platform Engineering

Artificial Intelligence (AI) has been revolutionizing numerous fields within science and engineering, giving rise to “AI for Science” – a new paradigm for both academia and industry. In this seminar, we will explore how AI algorithms and tools empower researchers to tackle intricate scientific challenges, strengthen collaboration, and expedite the discovery process. We will also envision the future of this field in the era of cloud-native infrastructures and large language models, emphasizing the crucial role of platform engineering in nurturing the growth and development of the entire scientific community. Lastly, we will provide examples to illustrate the potential appearance of such platforms and discuss the path towards their realization.

TechTalk – Schwarz Crystal Structure in Polycrystalline Metals with Extremely Fine Grains

Metals usually exist in form of polycrystalline solids, in which the networks of disordered grain boundaries tend to get eliminated through grain coarsening upon heating or straining, or to transform into metastable amorphous states when the grains are small enough. This is why nano-grained structures in metals are much more unstable relative to their coarse-grained counterparts. Through experiments and molecular dynamic simulations, we recently discovered a novel metastable structure in metals with grains of few nanometers in size, namely Schwarz crystal structure. The GB-network of the metal is characterized by 3D minimal interfaces structure with a zero-mean-curvature constrained by twin boundaries. The unique structure is thermally stable against grain coarsening at temperatures close to the equilibrium melting point and exhibits a hardness in vicinity of the theoretical value. The across-boundary diffusion is so effectively suppressed that the diffusion-controlled processes such as intermetallic precipitation are inhibited. In this presentation, Professor Ke Lu will introduce the formation process, structure characteristics, and some properties of the Schwarz crystal structures in a number of pure metals and alloys.

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

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.

TechTalk – The Metaverse Heatwave

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 – Innovation in MRI: Back to the Future?

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

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

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.