In order to achieve the International Air Transport Association’s (IATA) goal of achieving net-zero emissions in the aviation industry by 2050, there has been a growing emphasis globally on the technological development and practical application of sustainable aviation fuels (SAFs). Discrepancies in feedstock and production processes result in differences in composition between SAFs and traditional aviation fuels, ultimately affecting the emission performance of the two types of fuel. This paper discusses the impact of CO₂/NO_x/SO₂/CO/PM/UHC emissions from the aviation industry on the natural environment and human health by comparing the two types of fuel under the same conditions. Fuel combustion is a complex process in the combustor of an engine, which transfers chemical energy into heat energy. The completeness of combustion is related to the fuel properties, including spray, evaporation, and flammability. Therefore, engine performance is not only affected by fuel performance, but also interacts with engine structure and control laws. The CO₂ emissions of SAFs differ significantly from traditional aviation fuels from a lifecycle analysis perspective, and most SAFs can reduce CO₂ emissions by 41–89%. Compared with traditional aviation fuels, SAFs and blended fuels can significantly reduce SO₂ and PM emissions. Pure Fischer–Tropsch hydroprocessed synthesized paraffinic kerosine (FT-SPK) can reduce SO₂ and PM emissions by 92% and 70–95% respectively, owing to its extremely low sulfur and aromatic compound content. In contrast, the differences in NO_x emissions between the two types of fuel are not significant, as their generation mechanisms largely stem from thermal drive and turbulent flow in the combustor, with emissions performance being correlated to power output and flame temperature profile in engine testing. CO and UHC emissions are related to engine operating conditions and the physical/chemical properties of the SAFs, with no significant upward or downward trend. Therefore, SAFs have significant advantages over conventional aviation fuels in terms of CO₂, SO₂, and PM emissions, and can effectively reduce the hazards of aviation to the environment and human health.

In recent years, various devices utilizing surface acoustic waves (SAW) have emerged as powerful tools for manipulating particles and fluids in microchannels. Although they demonstrate a wide range of functionalities across diverse applications, existing devices still face limitations in flexibility, manipulation efficiency, and spatial resolution. In this study, we developed a dual-sided standing surface acoustic wave (SSAW) device that simultaneously excites acoustic waves through two piezoelectric substrates positioned at the top and bottom of a microchannel. By fully exploiting the degrees of freedom offered by two pairs of interdigital transducers (IDTs) on each substrate, the system enables highly flexible control of microparticles. To explore its capability on particle aggregation, we developed a two-dimensional numerical model to investigate the influence of the SAW phase modulation on the established acoustic fields within the microchannel. Single-particle motion was first examined under the influence of the phase-modulated acoustic fields to form a reference for identifying effective phase modulation strategies. Key parameters, such as the phase changes and the duration of each phase modulation step, were determined to maximize the lateral motion while minimizing undesired vertical motion of the particle. Our dual-sided SSAW configuration, combined with novel dynamic phase modulation strategy, leads to rapid and precise aggregation of microparticles towards a single focal point. This study sheds new light on the design of acoustofluidic devices for efficient spatiotemporal particle concentration.

Digital twin technology provides a promising approach for integrating the diverse physical and information resources involved in civil aircraft maintenance. However, existing studies often address individual technologies or isolated maintenance applications, while the systematic integration of digital twins and complementary digital technologies within a digital hangar remains insufficiently clarified. This study develops a practice-informed framework for digital-twin-enabled smart aircraft maintenance through a structured synthesis of relevant technologies and an illustrative analysis of the China Eastern Airlines Digital Hangar project. The framework organizes the smart maintenance system into interconnected functions for data perception, digital representation and data management, analytical decision support, and visualization and simulation. The industrial case illustrates how these functions can be mapped to core maintenance-management domains, including personnel, tools, aircraft materials, maintenance tasks, and safety. The analysis also clarifies the distinction between a digital-twin-enabled maintenance system and a conventional maintenance information platform with three-dimensional visualization. To support subsequent empirical assessment, operational efficiency, traceability, decision quality, system reliability, and economic performance are proposed as key evaluation dimensions. The framework provides a structured reference for the design, assessment, and further development of digital hangars in civil aviation maintenance.