Wave devouring propulsion: an overview of flapping foil propulsion technology

A comprehensive review of flapping foils for Wave Devouring Propulsion (WDP) is presented. The flapping foil can effectively utilize wave energy and generate thrust. The development of WDP is discussed, followed by an introduction to the geometry, modes of motion, and operating principles. These research studies are classified as theoretical, experimental, and numerical and are provided in detail. They demonstrate that marine equipment with a flapping foil system can achieve high energy conversion efficiency and low resistance. Several prototypes of the combination of WDP with human-crewed and uncrewed vessels have been shown, including the latest initial concept models and company products. There is a huge prospect for self-driven, pollution-free propulsion of marine devices, and this paper suggests several future studies

Modulation of Type III Secretion System in Pseudomonas aeruginosa: Involvement of the PA4857 Gene Product

Pseudomonas aeruginosais an opportunistic pathogen that causes serious acute or chronic infections in humans.Acute infections typically involve the type Ш secretion systems (T3SS) and bacterial motility,whereas chronic infectionsare often associated with biofilm formation and the type VI secretion system (T6SS). To identifynew genes required for pathogenesis, a transposon mutagenesis library was constructed and the gene PA4857, named tspR, was found to modulateT3SS gene expression. Deletion of P. aeruginosa tspRreduced the virulence in a mouse acute lung infection model and diminished cytotoxicity. Suppression of T3SS gene expression in the tspR mutant resulted from compromised translation of the T3SS master regulator ExsA. TspR negatively regulated two small RNAs, RsmYand RsmZ, which control RsmA. Our data demonstrated that defects inT3SS expression and biofilm formation in retS mutant could be partially restored by overexpression of tspR. Taken together, our results demonstrated thatthe newly identifiedretS-tspRpathway is coordinated with the retS-gacSsystem, which regulates the genes associated with acute and chronic infections andcontrols the lifestyle choice of P. aeruginosa

Numerical modelling of oil containment process under current and waves

This study presents a novel three-phase Fluid–Structure Interaction (FSI) model for simulating the containment of oil spills. The model uses Level Sets to capture the evolution of multiple interfaces and incorporates spring forces on the structure under hybrid wave–current boundary conditions. The implementation of spring forces has been validated through simple harmonic motion models and a wedge falling simulation demonstrates the model’s ability to handle multi-phase deformation. The study compares numerical results with experimental data to study the response of oil spills to wave–current hybrid conditions. Our simulations reveal that when the current exceeds 0.2 m/s, the movement of the boom is dominated by the current and not by the waves or their inertia, providing important information for the design of effective oil spill containment systems

Experimental investigation of wave induced flapping foil for marine propulsion: heave and pitch stiffness effect

The submerged hydrofoil has the capability to harness wave energy and convert it into thrust to work with the ship's power system. The current series of experiments investigated the interaction of a passive submerged hydrofoil with regular waves through a comparison of the generated horizontal forces. Springs provide the restoring force for the hydrofoil's heave/pitch motion, corresponding to heave spring and pitch spring. Maintaining a constant heave spring stiffness (490 N/m), subsequent statistical analysis summarized the force trends at different pitch stiffnesses (16–300 N/m) and suggested an optimal pitch spring stiffness in regular waves. A pulse-shaped force signal was observed and explained as a result of low pitch stiffness. Experiments with different spring setups revealed that the heave spring contributes to the harmonic force generated by the fully passive foil. Additionally, by varying wave conditions with limited wave amplitudes and frequencies, tests reproduced the variation of force signals over time and assessed their dependence on wave parameters.L. Yang acknowledgement the support from the UK – Saudi Challenge Fund ‘Feasibility study of hybrid propulsion for unmanned surface vehicle for environmental monitoring’ and TRIG2022 grant from Department for Transport (DfT): ‘G[1]TRANSPORT: Greening Transportation of Cargo Ships via Hybrid Wave Propulsion’

Sharing tableware reduces waste generation, emissions and water consumption in China’s takeaway packaging waste dilemma

China has a rapidly growing online food delivery and takeaway market, serving 406 million customers with 10.0 billion orders and generating 323kilotonnes of tableware and packaging waste in 2018. Here we use a top-down approach with city-level takeaway order data to explore the packaging waste and life-cycle environmental impacts of the takeaway industry in China. The ten most wasteful cities, with just 7% of the population, in terms of per capita waste generation, were responsible for 30% of the country's takeaway waste, 27-34% of the country's pollutant emissions and 30% of the country's water consumption. We defined one paper substitution and two sharing tableware scenarios to simulate the environmental mitigation potentials. The results of the scenario simulations show that sharing tableware could reduce waste generation by up to 92%, and environmental emissions and water consumption by more than two-thirds. Such a mechanism provides a potential solution to address the food packaging waste dilemma and a new strategy for promoting sustainable and zero-waste lifestyles. The online food delivery and takeaway market is growing in China, serving 406 million customers with 10.0 billion orders in 2018. Here, data from an online food delivery platform, life-cycle environmental impacts of packaging and tableware waste generated across 353 cities in China, and scenarios for paper alternatives and tableware sharing are presented

Comparison of power cycling reliability of flexible PCB interconnect smaller/thinner and larger/thicker power devices with topside Sn-3.5Ag solder joints

The power cycling reliability of flexible printed circuit board (PCB) interconnect smaller/thinner (ST) 9.5 mm × 5.5 mm × 0.07 mm and larger/thicker (LT) 13.5 mm × 13.5 mm × 0.5 mm single Si diode samples have been studied. With the assumption of creep strain accumulation-induced fatigue cracking as the failure mechanism of the Sn-3.5Ag solder joints, finite element (FE) simulations predicted a higher power cycling reliability of soldering the flexible PCB on a ST Si diode than on a LT Si diode under similar power cycling conditions. Then the power cycling test results of 10 samples for each type are reported and discussed. The samples were constructed with commercially available ST Si diodes with 3.2/0.5/0.3 μm thick AlSiCu/NiP/Pd topside metallization and LT Si diodes with 5/0.1/1/1 μm thick Al/Ti/Ni/Ag topside metallization. In contradiction with the FE prediction, most ST Si diode samples were less reliable than those LT Si diode samples. This can be attributed to the fact that the failure of the ST diode samples was associated with the weak bonding and hence the shear-induced local delamination of the topside solder joints from the AlSiCu metallization, while the failure of the LT diode samples was mainly caused by the creep strain accumulation-induced fatigue cracking within the solder joints. Such results can be used to not only provide better understanding of the different failure mechanisms, but also demonstrate the importance of employing an appropriate topside metallization on the power devices

Methodology and applications of city level CO2 emission accounts in China

China is the world's largest energy consumer and CO2 emitter. Cities contribute 85% of the total CO2 emissions in China and thus are considered as the key areas for implementing policies designed for climate change adaption and CO2 emission mitigation. However, the emission inventory construction of Chinese cities has not been well researched, mainly owing to the lack of systematic statistics and poor data quality. Focusing on this research gap, we developed a set of methods for constructing CO2 emissions inventories for Chinese cities based on energy balance table. The newly constructed emission inventory is compiled in terms of the definition provided by the IPCC territorial emission accounting approach and covers 47 socioeconomic sectors, 17 fossil fuels and 9 primary industry products, which is corresponding with the national and provincial inventory. In the study, we applied the methods to compile CO2 emissions inventories for 24 common Chinese cities and examined uncertainties of the inventories. Understanding the emissions sources in Chinese cities is the basis for many climate policy and goal research in the future