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The operation of tidal pumping station has an energetic impact on energy course of massive water pumping for a long time. Thus, a multi-objective optimal operation model was developed to optimize the operation scheme and reduce the energy consumption of the tidal pumping station. In the model, a day is divided into several sub-periods according to the regulation of water level in tidal reach. The partition of sub-periods, the number and blade angle of operating units in each sub-period are adjusted to minimize daily operation energy consumption. And the less switching times, the better the reliability and durability of the unit, the lower the failure rate. Therefore, the reduction of wearing parts' service life is quantified for each switching time in the form of cost. A case study is performed with the tidal pumping station of the South-to-North Water Transfer Project in China. In this paper, energy consumption and switching times are quantified as costs respectively, and the result shows that the daily energy consumption could be saved about 2.28%–6.56%, and the switching times reduced at least 60%. Therefore, this paper could provide an effective optimal operation scheme for the tidal pumping station whose operation is affected by tides. [ABSTRACT FROM AUTHOR]

• A fault-tolerant gait for quadruped robots with 2 locked legs is designed. • The gait pattern is designed using the mobility analyzed by the G F set theory. • The trajectory planning method for the fault-tolerant gait is proposed. • Positive static stability margin can be satisfied all throughout the gait. • The gait allows the robot to walk omnidirectionally and adapt to rough terrains. Fault-tolerant gaits can give legged robots the ability to walk under fault conditions, and hence prolong the service life. However, for quadruped robots with two locked legs, fault-tolerant gaits can be rarely found. This paper proposes a novel fault-tolerant gait for quadruped robots with two locked legs using the G F set theory. First, a quadruped robot and eight stages of its fault-free static gait are introduced. Then, the G F set theory is applied to analyze the robot's mobility stage by stage, which takes the mobility loss caused by the two locked legs into account. By taking full advantage of the mobility, the fault-tolerant gait pattern and trajectory planning method are developed. Further, the omnidirectional locomotion capability, adaptability to rough terrains, energy consumption, speed and influences of locking angles of the fault-tolerant gait are addressed to show its performances. Finally, the fault-tolerant gait and its performances are validated by three simulations. The results show that the robot with the fault-tolerant gait can walk omnidirectionally and adapt to rough terrains while keeping the static stability margin positive. [ABSTRACT FROM AUTHOR]

The operation of solar photovoltaic installations for many years may lead to problems such as reduced energy efficiency and aging of components. Under this framework, replacing certain components in the facility to extend the service life of the power plant is viewed, in some cases, as a feasible strategy. However, despite its enormous strategic interest for the solar PV industry, we find that revamping PV installations has been the focus of very few scientific publications, and even less so when it comes to analyzing real facilities. Thus, this paper performs a techno-economic analysis of three revamping strategies at a real PV power plant located in the south-east of Spain. The strategies consist of substituting, in each case, the PV modules, the inverter, and both components. The simulated results show that the highest production value by installed power is obtained when both the modules and the inverter are replaced. In the same vein, the economic analysis reveals this scenario as the most favorable in terms of profitability. Based on the results obtained, an interesting future line of research would be focused on the extension of the analysis at country level to study the joint impact of numerous revamping actions. • Techno-economic analysis of revamping projects of a real solar PV power plant. • Replacing modules and inverter emerges as the most feasible strategy. • Study's applicability extends to other revamping initiatives and geographical regions. • Economic outcomes allow the most cost-effective alternatives to be determined. • This research can contribute to efficient and sustainable energy planning. [ABSTRACT FROM AUTHOR]

• A novel frosting suppression control strategy for air source heat pump is developed. • Frosting suppression can be effectively achieved by using the control strategy. • Heating duration under the novel control strategy is increased by up to 157.68 % • Daily defrosting duration and energy consumption are reduced by 36.30 % and 32.96 % • The novel control strategy can meet required heating capacity with a high COP value. Effective frosting suppression was crucial to further wider applications of air source heat pumps (ASHPs). However, existing frosting suppression measures may not be fully implementable in practice due to various reasons such as short service life, complex manufacturing process and high costs. A condensing-frosting performance map was obtained in a previous study to enable a comprehensive evaluation of the frosting suppression and heating performances of a variable speed (VS) ASHP unit. Therefore, the maps could also provide a basis for developing a novel control strategy for frosting suppression, while still meeting the requirement of desired output heating capacity. As a result, an experimental study on developing a novel control strategy based on the condensing-frosting performance maps has been carried out using an experimental VS ASHP unit, and the study results are presented in this paper. The experimental results suggested that the experimental VS ASHP unit under the proposed novel control strategy could not only achieve effective frosting suppression, but also output the required heating capacity at high COP values whenever possible. By using the developed novel control strategy, the heating duration in one cycle could be increased by up to 157.68 %, and the daily defrosting frequency, duration and energy consumption reduced by up to 59.09 %, 36.30 % and 32.96 %, respectively. The proposed novel control strategy was straightforward and simple to implement, and could contribute to the further development of frosting suppression for ASHPs. [ABSTRACT FROM AUTHOR]

The composite single-cone bit is a new structure of single-cone bit, which breaks the limitation of the one-piece cone structure of existing single-cone bit. The new bit structure makes it possible to apply PDC cutters with strong wear resistance to single cone bit. PDC cutter is more suitable for rock breaking by scraping. In this paper, rock breaking and comparative drilling experiments of composite single-cone bit are carried out. The experiments verified the working principle of the new composite bit. The effective combination of fixed and unfixed cutting structures in the new bit can form complex cross-scraping. The comparative drilling experiments show that the new composite bit has higher rock breaking efficiency than the common single-cone bit, and it is more energy-saving for cross-scraping. The application of PDC cutters can improve the wear resistance of bit cutters and prolong the service life of bit. The research results can provide basic support and reference for subsequent research on the design, development, and application of this new type of bit. • The composite bit proposes a combination of fixed and unfixed cutting structure. • PDC cutters are directly used on the single-cone bit. • The cutters of the composite single-cone bit form complex cross-scraping. • The composite single-cone bit has higher rock breaking efficiency and saves energy. • The application of PDC cutters improves the wear resistance of bit cutters and can prolong the service life of bit. [ABSTRACT FROM AUTHOR]