HKAES TechTalk – Creating New Radio Frequency Wave Technology for 6G

April 23 2024 (Tuesday) 4:00-5:00pm
Radio frequency (RF) waves are a fundamental phenomenon that can carry electromagnetic signals and energy through space and interact with it. Their use in wireless communication has revolutionized our lives and created a mobile information society and new industries. However, RF wave technology can do much more and in this talk I explore new RF wave technologies that can be further exploited for 6G. I broadly classify the new RF technologies into wave shaping and wave sensing and in this talk I focus on the development of RF Imaging, RF energy harvesting and reconfigurable intelligent surfaces (RIS). In particular both the concepts and experimental results obtained from our prototypes are presented for each of these technologies. Furthermore, while each of these technologies is promising, significant further research is needed to exploit the enormous potential of new RF wave technology for 6G and this is also detailed.

TechTalk – Device-Independent Quantum Key Generation

March 7 2024 (Thursday) 4:30-5:30pm
The extraction of private, uniformly random bits from weakly random seeds is a problem of central importance in cryptography with multiple applications. A well-known result in classical computer science states that randomness extraction is possible using classical resources only when multiple independent sources are available. On the other hand, Quantum Entanglement enables a solution to the problem even in the so-called device-independent framework. Device-Independent quantum cryptography offers the highest form of security, wherein the users do not need to even trust the devices executing the cryptographic protocol, and can instead verify correctness and security by means of simple statistical tests on the devices. In this talk, we report on the state-of-art theoretical and experimental results on device-independent quantum cryptography, with a focus on quantum randomness amplification and quantum key distribution.

TechTalk – Seawater Sea-sand Engineered Cementitious Composites (SS-ECC) for Marine and Coastal Infrastructures

January 25 2024 (Thursday) 4:30-5:30pm
Engineered/Strain-Hardening Cementitious Composites (ECC/SHCC) is an advanced fiber-reinforced concrete exhibiting multiple-cracking and strain-hardening under tension. We aimed to explore the feasibility of producing high-strength seawater sea-sand Engineered Cementitious Composites (SS-ECC) for marine and coastal applications facing the shortage of freshwater and river/manufactured sand. The effects of key composition parameters including the sea-sand size, the polyethylene fiber length, and the fiber volume dosage on the mechanical performance of SS-ECC were comprehensively investigated. The crack characteristics of SS-ECC were also assessed and modelled, which are critical for its applications with non-corrosive reinforcements. SS-ECC with tensile strength over 8 MPa, ultimate tensile strain of about 5%, and compressive strength over 130 MPa were achieved. Using seawater and sea-sand had almost no negative effects on the 28-day mechanical properties of high-strength ECC. Smaller sand size and higher fiber dosage of SS-ECC resulted in smaller crack widths under the same tensile strain. A five-dimensional representation was proposed to assess the overall performance of SS-ECC, by comprehensively considering both the crack characteristics and the mechanical properties. A probabilistic model was also proposed to describe the stochastic nature and evolution of crack width, and it can be used to estimate the critical tensile strain on SS-ECC for a given crack-width limit and cumulative probability. The findings and proposed methods can facilitate the design of SS-ECC in marine and coastal infrastructures.

HKAES TechTalk – Living with Climate Extremes – Hong Kong Perspective

January 23 2024 (Tuesday) 4:00-5:00pm
Hong Kong has a sub-tropical climate and wide variety of weather. Different extreme weather events, including tropical cyclone, heavy rain, and extreme temperatures, can affect Hong Kong and result in significant impacts to the society. Looking into the future, against the background of climate change and local urbanization, Hong Kong will expect even warmer climate, more variable rainfall, more intense typhoons, and a sea level that keeps rising in the coming centuries. This may affect the frequency and severity of various extreme weather and increase the risk of related weather hazards. This presentation will review different kinds of high impact extreme weather in Hong Kong and their past trend and future projection. Moreover, a brief overview on the concept of climate risk management will be shared.

TechTalk – HKU’s Contributions to Landslide Hazard Mitigation in Hong Kong

February 1 2024 (Thursday) 3:00-4:00pm
Hong Kong, renowned as one of the most densely populated territories globally, grapples with its hilly terrain and limited flat land, resulting in numerous buildings constructed on slopes or adjacent to large cut slopes. This situation poses a grave risk as landslides could tragically claim multiple lives. To address this critical issue, slope stabilization plays a crucial role in mitigating the landslide hazard. In this TechTalk, the pioneering work of Professor Peter Lumb on slope stability will be reviewed. The development and validation of soil nailing as an effective measure for slope stabilization will also be described.

TechTalk – Filtration Solutions for Sustainable Environment

January 30 2023 (Tuesday) 4:00-5:30pm
We are developing filtration technologies to benefit sustainable environment. The Center for Filtration Research (CFR) at the University of Minnesota, collaborating with 20 leading international filtration manufacturers and end users, was established to find filtration solutions to mitigate PM2.5 and other environmental pollutants. There are more than 15 on-going fundamental and applied research projects on air, gas and liquid filtration. Five projects will be presented: 1. reduction of aerosol concentration in classrooms to prevent virus transmissions; 2. electret and nanofiber media to improve filtration performance; 3. indoor air cleaning using gas purifiers, ionizers, and UV-C; 4. real-time image detection of airborne biological particles; 5. temperature resistant nano-scale membrane for enhanced ceramic wall-flow filter performance. Large scale air cleaning towers are established in Xi’an and Yancheng in China to mitigate urban air PM2.5and CO2 (Yancheng) with two additional towers in Delhi, India. All these research and development activities are helping to improve sustainable environment.

TechTalk – Artificial Intelligence for Structural Design, Simulation and Health Monitoring

December 14 2023 (Thursday) 4:30-5:30pm
Structural engineering community require the experience of experts in design, simulation and structural health monitoring (SHM) of existing structures. Currently, the training process of structural engineers may take more than 10 years from undergraduate to expert. The economic design currently relies on the experience of engineers, which may not reach the optimized design outcome. In addition, high-fidelity simulation and SHM are still challenging and practical applications of the nonlinear structural simulation and SHM are mostly limited to researchers, instead of practical engineers. Conventional structural engineering widely adopts finite element solvers based on CPUs, which may be time consuming. The computing resources of GPU accelerators and GPU-based supercomputers cannot be fully utilized due to the lack of GPU-based simulation platforms.

The project develops deep-learning-based intelligent structural design, simulation and structural health monitoring platform. For structural design, dataset is collected for structural design input parameters and structural design drawings, the generative models are learned to generate preliminary structural design drawings of buildings and bridges. For structural simulation, physics-informed neural networks are developed to replicate the spatial discretization and temporal discretization of conventional finite element solvers. For SHM, the state-of-the-art neural operator is trained on finite element simulation dataset of vehicle-bridge interaction (VBI) system and fine-tuned on experimental dataset to infer the damage distribution field based on structural response field. The project can inspire the undergraduate and graduate students to learn more about the challenges and future developments of structural engineering.

HKAES TechTalk – Hong Kong’s Climate Action Plan 2050

The Hong Kong Government issued the “Climate Action Plan 2050” in October 2021. This blueprint sets out four decarbonisation strategies : (1) net-zero electricity generation; (2) energy saving and green buildings; (3) green transport and (4) waste reduction. The plan provided a clear timeline to reduce total carbon emissions by half before 2035 from the 2005 level and to achieve carbon neutrality before 2050.

TechTalk – 3D Functional Mesosystems: From Neural Interfaces to Environmental Monitors

December 13 2023 (Wednesday) 4:30-5:30pm
Complex, three dimensional (3D) micro/nanostructures in biology provide sophisticated, essential functions in even the most basic forms of life. Compelling opportunities exist for analogous 3D structures in man-made devices, but existing design options are highly constrained by comparatively primitive capabilities in fabrication and growth. Recent advances in mechanical engineering and materials science provide broad access to diverse, highly engineered classes of 3D architectures, with characteristic dimensions that range from nanometers to centimeters and areas that span square centimeters or more. The approach relies on geometric transformation of preformed two dimensional (2D) precursor micro/nanostructures and/or devices into extended 3D layouts by controlled processes of substrate-induced compressive buckling, where the bonding configurations, thickness distributions and other parameters control the final configurations. This talk reviews the key concepts and focuses on the most recent developments with example applications in areas ranging from mesoscale microfluidic/electronic networks as neural interfaces, to bio-inspired microfliers as environmental sensing platforms.

HKAES TechTalk – Magneto-electric Dipole – Advanced Antenna Technology for a Smart World

Since Heinrich Hertz developed the first antenna in 1887 to demonstrate the existence of radio waves, the antenna has become the linchpin in countless wireless systems and devices. With the increasing demand for faster wireless connectivity, rising adoption of smartphones for consumer electronics, and accelerating digitization, stringent requirements, such as wide bandwidth and compact size, are imposed on antenna technology. The magneto-electric (ME) dipole is proposed to tackle the new challenges. It has been developed for mobile communications, global navigation receivers, radars, sensors, medical imaging systems and wireless power transfer systems. Compared with conventional antennas such as dipoles, slots and microstrip antennas, the ME dipoles have many distinguished features including wide bandwidth, low cross-polarization, low back radiation and stable gain and beamwidth over the operating frequencies. An overview of the theory and applications of the ME dipoles will be presented.