December 2023

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.

TechTalk – Insights on the Future Development of Engineering and Technologies in China

Speaker: Academician C.C. Chan, Honorary Professor, The University of Hong Kong, Distinguished Chair Professor, Hong Kong Polytechnic University, Academician, Chinese Academy of Engineering, Fellow, Royal Academy of Engineering   About the TechTalk We would like to extend our sincere gratitude and appreciation to Academician C.C. Chan for sharing with us two videos of his speech on …

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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.

A Self-rotating, Single-actuated UAV with Extended Sensor Field of View for Autonomous Navigation

The UAV is named Powered-flying Ultra-underactuated LiDAR-sensing Aerial Robot (PULSAR), whose motion in three-dimensional space is controlled by only a single actuator (i.e., motor). The single actuator design can naturally cause self-rotation motion of the UAV body, obviously extending the field of view (FoV) of the onboard LiDAR sensor. Furthermore, it also effectively reduces the energy loss of the propulsion system, allowing PULSAR to save 26.7% of energy consumption compared to a benchmarked quadrotor UAV. Utilizing the extended FoV and onboard computing resource, PULSAR can perform autonomous navigation in unknown environments and detect both static and dynamic obstacles in panoramic views without using any external instruments. PULSAR has large FoV, high flight efficiency, and autonomous navigation ability, which are all beneficial for the environmental observation and information collection. Therefore, it can be used in various applications, such as environment surveying, search and rescue, terrain mapping, and automatic 3D reconstruction.

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.