Amphibious aircraft is one example of a complex engineering system that has not been properly optimized due to the complex design challenges and lack of data required to develop a suitable design framework. Unlike conventional aircraft, amphibious aircraft can takeoff and land both on water and on ground-based runways. The unique capabilities of amphibious aircraft to operate both in water and on land, while providing versatility and competitive advantages to conventional ground-based aircraft, impose significant challenges in the design and development. The key challenge lies in the fact that an amphibious aircraft design must strike a balance between aerodynamic and hydrodynamic performances, airworthiness and seaworthiness, water stability, spray, and buoyancy. Analyses involved in an amphibious aircraft design problem range from expensive computational fluid dynamics (CFD) for the aerodynamic and hydrodynamic analyses, to simple empirical models for the less studied analyses (e.g., hull resistance computation). The only currently available models of hull resistance are empirical models based on outdated experiments on a limited number of jull designs. These data and models limit the accuracy of amphibious aircraft design, and will deem our analysis results meaningless. Moreover, the hull parameterization is still lacking as well, i.e., we do not have sufficient information on how the change in the hull geometry and shape will affect the hull performance. In the proposed collaboration, we aim to use the multifunction water towing tank facility at SJTU to perform the necessary experiments and measurements to build the hull resistance database. Once incorporated to the amphibious aircraft design framework, we hope to use this framework to help bring revolutionary technological improvement to amphibious aircraft design. e.g., by optimizing the shape of the hull and hydrofoils.

The formation of discrete droplets from capillary jets by the action of surface tension and/or open-loop forcing is one of the most vital processes in fluid mechanics, playing an important role in industrial processes such as ink-jet printing and drug delivery. However, regardless of the specific application, in all types of capillary jets, droplets form at a wide range of temporal frequencies – from around a single droplet per second in the case of a leaky faucet to up to thousands of droplets per second in the case of an ink-jet printer . A thorough understanding of the physics behind this would therefore enable more accurate and more precise control over the droplet formation process and, in turn, over properties such as the droplet diameter, its velocity and its formation frequency. Previous experiments have already examined the droplet formation frequency of a dripping faucet. For example, Katsuyama and Nagata found that the dripping dynamics alternate between a stable state and a chaotic state over a wide range of flow rates. Subramani et al. found that increasing the Bond number can enhance the complexity of the nonlinear dynamics exhibited by a leaky faucet. Ambravaneswaran et al. found that the use of a high-viscosity liquid can trigger a direct transition from simple dripping to jetting, by-passing the intermediate chaotic behavior. Ambravaneswaran et al. computationally simulated the long-time behavior of a dripping faucet and verified the results with experiments. In addition to the natural frequency of droplet formation, Olinger’s observation of frequency lock-in in the dripping mode of a capillary jet, produced via open-loop forcing, shows that forced synchronization can also occur, producing nonlinear dynamics far more complex than previously thought.

However, previous studies have focused only on a narrow range of operating parameters, all within the linear regime. The nonlinear instability characteristics of capillary jets have yet to be comprehensively explored. This is why a systematic investigation of capillary droplet formation, from its inception to transition to nonlinear instability is being proposed here as a UROP project. Furthermore, previous studies on the control of such jets have explored only open-loop control. Here we propose to apply closed-loop control, leveraging recent advances in machine-learning control to discover more efficient control laws. Not only will this spur new pathways for the development of novel control strategies for such jets, but it will also provide much needed fundamental insight into the physics of self-excited flows in general. This is important because it has been conjectured that absolute instability in open shear flows could be the underlying cause of the dripping mode in a capillary jet. Providing direct experimental evidence to support (or refute) this hypothesis could therefore lead to a paradigm shift in our understanding of the physics of such jets.

This proposed project aims to examine the factors that shape the commensurability between heritage preservation and tourism development for community revitalization on the island of Yimtintsai (鹽田梓), the home of a Catholic Hakka village and a popular heritage site of Hakka culture and Catholicism in Saikung (西貢), Hong Kong. The 2018-19 government budget included a recurrent investment of 24 million HKD for the development of an annual art festival on the island in three consecutive years from 2019 to 2021. This government project of international tourism development seeks to be modeled after the Setouchi Triennale International Art Festival (瀨戶內海國際藝術祭) in Japan, which has been developed around the main theme of community revitalization. The impact of the government project on Yimtintsai’s community revitalization project will be studied by focusing on the following two factors: 1) the commensurability between heritage preservation and tourism development, in particular how contemporary installation art works accommodate the heritage of local Hakka culture and Catholicism; and 2) the alignment between local agency and external intervention with respect to how local villagers’ voices get accommodated in the planning of art works and the implementation of the art festival. A research tour will be organized to the Setouchi Triennale International Art Festival in the summer this year. After conducting a general survey on the development of the Art Festival in the region, two islands with local conditions comparable with Yimtintsai Island will be selected for in-depth research by conducting interviews with local villagers, officials, artists and tourists to learn the views of different stakeholders and their experiences of interaction.Japanese art experts will be invited to give consultation on the tour about the development of contemporary Japanese art in relation with local village heritage in the region. Data collection will focus on the commensurability between heritage preservation and tourism development, on the one hand; and the alignment of local agency and external intervention, on the other.

After returning from the research trip to Japan, data on the Japanese model of international art festival development will be processed and organized. They will serve as the base for comparison with the Yimtintsai case, with its first annual art festival to be inaugurated at the end of 2019. Data from participation in the planning sessions and the following installation of art works will be accumulated for analysis. During the one-month long festival, research will be conducted to collect data by means of designed survey and in-depth interviews with local villagers, officials, artists and tourists to learn the views of different stakeholders and their experiences of interaction. Village leaders’ opinions will also be solicited about the festival’s effects upon their goal of community revitalization. After the first annual Yimtintsai Art Festival concludes, data on public opinions about the festival will be collected from media for analysis. The research will then follow-up the second phase of the Yimtintsai Art Festival’s development to be implemented in 2020. According to the plan of the Tourism Bureau, more art works will be installed on Yimtintsai Island in the second and third phases, and the length and scale of the festival will be augmented. This proposed project will cover the first two phases of the Yimtintsai Art Festival’s development, attempting to argue that successful revitalization of marginalized communities that own rich heritage relies on the commensurability between heritage preservation and tourism development, on the one hand; and the alignment of local agency and external intervention, on the other. The transnational comparison between the Setouchi Triennale International Art Festival in Japan and the Yimtintsai Art Festival in Hong Kong will expand our horizon on exploring the conditions and constraints for the involved factors.