The integrated valve-controlled cylinder combines various control and execution components in hydraulic transmission systems. Its precise control and rapid response characteristics make it widely used in mobile equipment for aerospace, robotics, and other engineering applications. Additive manufacturing provides high design freedom which can further enhance the power density of integrated valve-controlled cylinders. However, there is a lack of effective design methods to guide the additive manufacturing of valve-controlled cylinders for more efficient hydraulic energy transmission. This study accordingly introduces an energy-saving design method based on additive manufacturing for integrated valve-controlled cylinders. The method consists of two main parts: (1) redesigning the manifold block to eliminate leakage points and reduce energy losses through integrated design of the valve, cylinder, and piping; (2) establishing a pressure loss model to achieve energy savings through optimized flow channel design for bends with different parameters. Compared to traditional valve-controlled cylinders, the integrated valve-controlled cylinder developed from our method reduces the weight by 31%, volume by 55%, and pressure loss in the main flow channel by over 30%. This indicates that the design achieves both lightweight construction and improved hydraulic transmission efficiency. This study provides theoretical guidance for the design of lightweight and energy-efficient valve-controlled cylinders, and may aid the design of similar hydraulic machinery.

Segment lifting, performed by an electro-hydraulic system including two cylinders, is a crucial step in segment grasping, transporting, and assembly in tunnel boring machines. Due to heavy and uneven loading, large vibration, uncertainty of parameters, and nonlinear friction, it is difficult to develop an accurate physical model. This paper presents a comprehensive procedure to achieve two-cylinder automation and synchronisation according to the actual engineering requirements and environments. An improved deviation compensation recursive least squares identification algorithm with a forgetting factor was used to identify the key parameters of the model. To achieve synchronous control and precise control of the lifting system, SMC with improved sliding mode approach rate and the deviation coupling method of fusion single neuron PID were designed and verified by simulation. A full-scale bench test was also performed to show that the tracking steady-state error is below 4 mm, and the synchronisation error is below 2 mm.

The hydrodynamic cavitation abrasive finishing (HCAF) technology, as an innovative, clean, and efficient polishing method, has been proven effective for processing the internal surfaces of additive manufacturing flow channels. However, in-depth mechanistic studies on the key factors affecting the cavitation intensity in the HCAF processing remain limited, even though they play a crucial role in optimizing polishing performance and enhancing process stability. This study aims to apply the HCAF process to the flow channels fabricated by the laser powder bed fusion (LPBF). By adjusting the abrasive inlet pressure and throat diameter, the optimal process parameter combination was obtained, resulting in a 90% reduction in surface roughness near the inlet. fluent simulations and high-speed imaging were conducted to further validate its effect on the cavitation intensity. Furthermore, the channel diameter was found to have a significant impact on the polishing performance. Additionally, predictions of cavitation intensity were used to guide the application of the HCAF polishing for channels of different diameters. The results indicate that although the abrasive inlet pressure has a minor effect on the incipient cavitation number, it significantly alters the pressure distribution in the mixed-flow chamber, thereby influencing cavitation dynamics. The high-pressure region accelerates cavitation bubble contraction and collapse, significantly reducing bubble lifespan and weakening both the intensity and persistence of the cavitation effect. This instability makes sustained cavitation enhancement in the HCAF difficult, affecting material removal efficiency and jet stability. Therefore, the abrasive inlet pressure plays a crucial role in controlling cavitation behavior and enhancing machining performance.

This study investigates the high-temperature wear of additive-manufactured Ti6Al4V alloy against GH2132. The wear mechanism transitioned from abrasive and adhesive wear to oxidative wear with rising temperatures. The microstructure characteristics reveal the special hybrid high-temperature wear mechanisms: shear deformation-induced wear hardening and dynamic recrystallization-induced wear softening. At lower temperatures, the thinner oxide layer was easily removed and the worn surface in contact underwent work hardening, reducing the negative effects of thermal softening. At higher temperatures, the thicker oxide layer slightly reduced adhesive of the substrate but failed due to cracking and spalling. Combined with intensified thermal softening, recrystallization softening on the worn surface not only eliminated surface hardening but led to a sharp decline in wear resistance.

Since supercritical carbon dioxide (S-CO2) systems usually have to work at both high temperature, high pressure and high heat flux, selecting appropriate solid materials is of great important to their system safety. In this study, the thermofluidic characteristics of supercritical carbon dioxide (S-CO2) in a horizontal rectangular channel have been investigated under high pressure and one-side-wall heated with high heat flux. Four different solid wall materials (253 MA, Inconel 617, Haynes 230 and Haynes 233) and three different heat flux values (1.5 MW/m2, 2.0 MW/m2 and 2.5 MW/m2) are selected for analyzing the impacts of wall material and heat flux boundary conditions. The results showed that the maximum wall temperature difference of all four wall materials can generally exceed 100 K under the minimum heat flux, and can reach 500 K for Haynes 233 at the heat flux of 2.5 MW/m2. Considering the maximum allowable stress and creep characteristics, Inconel 617 has more obvious advantages as a solid material at the heat flux below 2 MW/m2, while Haynes 230 is a better choice at the heat flux beyond 2 MW/m2 because of the stronger mechanical properties. By exploring the effect of inlet temperature, it is found that the inlet temperature close to the pseudo-critical temperature is conducive to flow and heat transfer. Taking the effect of buoyancy into account, it is shown that the temperature of the heating surface is decreased, the deterioration of heat transfer is weakened and occurs early, and the difference on the cross sections of the wall temperature decreases.

To catch up with the sustainability transition progress, the global capacity of PV system is predicted to grow dramatically in the following decades, including high-latitude regions. To effectively use the urban space resource for PV power generation in the high-latitude areas, wall-mounted PV system is becoming an attractive solution. This paper evaluates the potential of wallmounted PV system in the high-latitude areas with a case study in Swedish contexts through a PV power generation model by considering weather conditions (including snowfall, icing and melting), orientation, and economics. The key performances are compared with rooftop fixed-tilt angle PV systems in Swedish contexts. Although the annual power generation of the wallmounted PV system is around 5% lower under heavy snow conditions, its power generation during the snow season (from October to April) increases significantly. In general, the power generation in March almost doubled and the increase could be more than 25% in April. Therefore, wall-mounted PV system can contribute to the winter electricity supply in high-latitude areas, when the electricity price is high.

Although much progress has been made in recycling components of end-of-life wind turbines, the recycling and reuse of the blades still present significant challenges. A two-stage pyrolysis process was applied in this work to recycle high quality glass fibers from waste wind turbine blades, which were then reused as support to grow heterogeneous photo-Fenton catalyst, zinc oxide nanorods coated by amorphous tin oxide and decorated with nano-zero valent iron (ZnO-SnOx-nZVI) to treat melanoidins, the major pollutant in effluents from distillery and bakery industries with dark brown color and high chemical oxygen demand (COD). Factors influencing the degradation process including pH (3 and 6), the amount of catalyst, and H2O2 dosage, were investigated. More than 97 % decolorization of melanoidin wastewater with 7000 mg/L COD was achieved with only 1/6th of theoretical amount of H2O2 required for Fenton reactions at pH 6. Kinetic studies were conducted to elucidate the correlation between generations of free radicals, unreacted H2O2 at different pH, and the effects on melanoidin degradation, revealing the significant role of pH in both the adsorption of melanoidin and the oxidation potential of radicals. The catalyst was reused three times maintaining 90 % decolorization, thus exhibiting good recyclability. The findings of this work have significant implications in treatment of non-biodegradable organic pollutants, owing to the advantages in avoiding low pH treatment condition, reducing the cost of H2O2, and enhanced chemical stability of photo-Fenton catalyst.

Polyethylene terephthalate (PET), the fifth most produced plastic in Europe, has become a focus of intense research due to the growing need for sustainable recycling solutions. In previous studies, a novel solar-assisted, sorption-enhanced gasification process was proposed, offering a breakthrough method to recover hydrogen and other valuable chemicals while capturing fossil CO2. This research takes the concept further by performing a gate-to-gate life cycle assessment (LCA) of the proposed method and comparing its techno-economic-environmental performance across selected European locations using an integrated evaluation metric. The LCA demonstrated an avoided global warming potential of 1639.13 kg CO2 eq. per tonne of PET waste recycled, highlighting the environmental advantages. Among the selected sites, Aldeire in Spain showed the most promising economic returns, boasting an internal return rate above 12%, thanks to its abundant solar energy. However, the location in Germany exhibited the best overall environmental performance. The findings confirm that this innovative process significantly outperforms current PET recycling systems, offering a cleaner, more sustainable alternative. Coupled with a comprehensive techno-economic analysis, the proposed recycling approach proves viable and highly beneficial for implementation in Southern Europe. These insights offer valuable guidance to policymakers as they seek to advance PET recycling technologies, driving Europe toward a more resource-efficient, circular economy and a carbon-neutral future. 

The demand for sustainable energy is increasingly urgent to mitigate global warming which has been exacerbated by the extensive use of fossil fuels. Solar energy has attracted global attention as a crucial renewable resource. This study conducted a bibliometric analysis based on publication metrics from the Web of Science database to gain insights into global solar power research. The results indicate a stable global increase in publications on solar power generation and a rise in citations, reflecting growing academic interest. Leading contributors include China, the USA, South Korea, Japan, and India, with the Chinese Academy of Sciences emerging as the most prolific institution. Multidisciplinary Materials Science, Applied Physics, Energy and Fuels, Physical Chemistry, and Nanoscience and Nanotechnology were the most used and promising subject categories. Current hot topics include the systematic analysis of photovoltaic systems, perovskite as a solar cell material, and focusing on stability and flexibility issues arising during photovoltaic-grid integration. This study facilitates a comprehensive understanding of the status and trends in solar power research for researchers, stakeholders, and policy-makers.

PV technologies are regarded as one of the most promising renewable options for the transition towards Net Zero. Despite the rapid development of PV systems in recent years, achieving the necessary goals requires more than a threefold increase in annual capacity deployment by 2030. However, current PV systems often fall short of optimal performance due to improper installation angles. In high-latitude cold regions, the actual PV generation capacity is frequently overestimated due to the omission of snow conditions. This study introduces a novel model designed for high-latitude regions to predict local optimal PV installation angle that maximizes PV power generation, utilizing historical weather big data, including snowfall and melting effects. A case study is presented within a Swedish context to demonstrate the implementation of these methods. The results highlight the crucial role snow conditions play in determining PV performance, resulting in an average reduction of 14.7% in annual PV power generation. Optimal installation angle could yield approximately a 4.8% improvement compared to common installation angles. The study also explores the application of snow removal agents, which could potentially increase PV generation by 0.1–2.3%. Additionally, the new PV installation angle successfully captures the impact of the local weather changes on PV power generation, potentially serving as a bridge between climate change adaptation and future PV power generation endeavors.