Stringent requirements in emissions and the depletion of conventional fossil fuels drive the development of Gaseous Alternative Fuels (GAF). As a commonly used power source, compatibility issues of the internal combustion engines under the harsh conditions created by the fuels become a technical barrier to improving the safety, reliability, and power performance of real world engines' applications. This paper systematically reviewed the material performance affected by GAF from the perspective of crucial engine components. Issues related to the compatibility of crucial components with GAF were firstly summarized in corrosion, thermal damage, and wear. Experimental study progresses concerning these compatibility issues and the assessment criteria for the material performances were discussed. Feasible critical technologies for improving material performances were discussed from tribology. Finally, this review briefly discussed the characteristics and plausible future trends for these compatibility issues. This study provides technical assistance for the safe application of GAF on internal combustion engines.

As vital components of diesel engines, failure issues of cylinder liner-piston ring components (CLPRs), which work under harsh conditions of high temperature, high pressure, and heavy load, become a technical shortcoming of performance improvement and service life for diesel engines. Online condition monitoring and maintenance based on the operating conditions of CLPRs are considered an effective method for ensuring normal diesel engine operation. For this reason, a comprehensive overview for condition-monitoring technologies, including lubricating oil and vibration condition monitoring, and wear-repairing strategies was necessary. However, such an overview, to the best of our knowledge, is needed in related research fields of condition monitoring and maintenance regarding diesel engines and its components. This paper systematically reviewed the research progress of online condition monitoring and self-repairing techniques for in-service diesel CLPRs from the perspective of tribosystems. To contextualize this concern, an initial review of various condition-monitoring techniques, such as lubricating oil, mechanical vibration, essential state parameters, and acoustic emission technology were specifically discussed. Subsequently, real-time maintenance strategies based on lubricating oil self-repairing additives were comprehensively summarized. Finally, this review concluded with a brief discussion of shortcomings and plausible future trends for various techniques. This study tackled wear-induced failure issues of CLPRs by reviewing online condition techniques and in-time maintenance methodology, providing a theoretical foundation and technical assistance for the development of operation and maintenance guarantee systems for marine diesel engines and intelligent engine rooms in the near future.

With the wider recognition of the concept of environmental protection and sustainable development, more and more manufacturers have begun to implement green manufacturing strategies. However, green development is a gradual process, and the coexistence of ordinary and green products is common. This paper examines the competition between ordinary products and green ones based on supply chains, and discusses the impact of retailers' horizontal cooperation on pricing, greenness, market demand, profit, and other related decisions and results. Model solutions and numerical experiments have shown that consumers' green preference (CGP) has a positive impact on the results of green products and negative effects on those of ordinary ones; however, the impact of competition intensity (CI) is more complex, and the trend tends to change if it exceeds a certain critical value. In general, cooperation encourages retailers to raise prices and make manufacturers lower wholesale prices, but the retail and wholesale prices of green products are always higher than the corresponding prices of ordinary ones. Market demand can be reduced due to cooperation, but it is conducive to strengthening green products' greenness. However, if CI exceeds a certain threshold, the greenness will be weakened by cooperation. Both retailers can benefit from cooperation easily and they always reach a win-win situation, but manufacturers suffer badly as a result. Nevertheless, when CI is weak, cooperation will bring a greater profit improvement to the whole chain of ordinary products; in this case, if a retailer is willing to compensate for a manufacturer's profit loss and help it benefit from cooperation, the manufacturer will encourage the retailer to cooperate horizontally with the green retailer, but the green chain will be seriously damaged. When CI is strong, the greenness of green products is not obvious enough, and cooperation can bring some chances to achieve a win-win situation for two chains; if the green retailer can obtain a larger share from cooperation under this scenario, it can also enable its manufacturer to obtain compensation and change the profit increment from negative to positive. From an overall perspective, when CI is very weak or very strong, horizontal cooperation is conducive to improving the profit of the entire supply chain competition system, but when CI is relatively flat, independent operation for each chain is more advantageous; if the competition status is stable and unchanged, independent competition will be superior to horizontal cooperation. © 2021. The Author(s).