Proton membrane exchange fuel cells (PEMFCs) provide an important energy solution to decarbonizing transport sectors and electric systems due to zero carbon emission during the operating process, and how to enhance the system efficiency of PEMFCs is one of the most challengeable issues to hinder the large-scale commercial application of PEMFCs. In recent years, numerous studies have been conducted to explore the feasibility and techno-economic performance of advanced thermal management to promote the efficiency of PEMFC systems. The thermal management of PEMFCs can be implemented from two aspects: one is efficient cooling methods to maintain the PEMFC under proper working temperature range, and the other one is waste heat recovery from PEMFCs to improve the overall system efficiency. Concentrated on these topics, many achievements have been gained by academic and industrial communities, and it is imperative to analyze and conclude these experienced studies from mechanism, technology, and application aspects. Therefore, this review summarized the great advances of thermal management of PEMFCs with efficient cooling and waste heat recovery for the sake of improving the overall efficiency of PEMFC systems, providing guidelines for the future design and optimization of PEMFC systems.

Based on the safety monitoring requirements of power batteries for new energy commercial vehicles, this study proposes a battery insulation detection method utilizing the bridge method in combination with existing insulation detection techniques. Through optimization and improvement of this methodology, an insulation detection system for new energy commercial vehicle power batteries was developed, along with a dynamic online calculation method for insulation resistance. Comprehensive experimental testing under multiple operational conditions demonstrates that the proposed system achieves a measurement accuracy with errors below 5% for insulation resistance. Furthermore, the system exhibits significant advantages in dynamic real-time monitoring capabilities and operational reliability.

The electric vertical take-off and landing (eVTOL) aircraft offers the advantages of vertical take-off and landing, environmental cleanliness, and automated control, making it a crucial component of future urban air traffic. As competition intensifies, demands for aircraft performance are escalating, including forward flight speed and payload capacity. The article presents a novel eVTOL design with propulsive wings and establishes methodologies for propulsive wing unsteady numerical simulation and wind tunnel experiments, analyzing its aerodynamic characteristics and lift enhancement mechanism. The results indicate that the cross-flow fan (CFF) provides unique airflow control capabilities, enabling the propulsive wing to achieve remarkably high lift coefficients (exceeding 7.6 in experiments) and propulsion coefficients (exceeding 7.1 in experiments) at extreme angles of attack (30°~40°) and low airspeeds. On the one hand, the CFF effectively controls boundary layer flow, delaying airflow separation at high angles of attack; on the other hand, the rotation of the CFF induces two eccentric vortices, generating vortex-induced lift and propulsion. The aerodynamic performance of the propulsive wing depends on the advance ratio and angle of attack. Typically, both lift and propulsion coefficients increase with the advance ratio, while lift and drag coefficients increase with the angle of attack. The propulsive wing shows significant advantages and prospects for eVTOL aircrafts in the low flight velocity range (0–30 m/s).

The ducted coaxial propeller (DCP) is highly advantageous in the design of eVTOL aircraft due to its safety, compactness, and low noise levels. To study the aerodynamic characteristics of DCP in hovering, a novel eVTOL was used, and a slip grid model was established to solve the three-dimensional unsteady N-S equation. The aerodynamic characteristics of DCP were compared to those of the free coaxial propeller (FCP) and ducted single propeller (DSP) to reveal the interaction mechanism of unsteady flow between the duct and propellers. The results indicate that the duct significantly mitigates the intensity of tip vortexes by changing the characteristics of propeller tip winding, which reduces the corresponding energy loss. Additionally, the static pressure loss is decreased by the reduced radical-induced velocity in the slipstream area. Finally, the induced power loss is reduced by the decreased axial-induced velocity and suppressed wake contraction, resulting in DCP having 39% higher aerodynamic efficiency than FCP and the duct accounting for 41.7% of the total lift. Although DCP generates 1.77 times more lift than DSP, its aerodynamic efficiency is only 91.08% of DSP.

With the increasing demand for the performance and design refinement of steel structures (including houses, bridges, and infrastructure), many structures have adopted ultimate bearing capacity in service. The design service lives of steel building structures are generally more than 50 years, and most of them contain bolted connections, which suffer from extreme conditions such as fire (high temperature) during service. When the structure contains defects or cracks and bolt holes, it is easy to produce stress concentration at the defect location, which leads to crack nucleation and crack propagation, reduces the bearing capacity of the structure, and causes the collapse of the structure and causes disasters. In the process of structural damage and crack propagation, the traditional method has some disadvantages, such as stress singularity, the mesh needing to be redivided, and the crack being restricted to mesh; however, the integral method of peridynamics (PD) can completely avoid these problems. Therefore, in this paper, the constitutive equation of PD in high temperature is derived according to the variation law of steel material properties when changed by temperature increase and peridynamics parameters; the damage and crack expansion characteristics of Q345 steel specimens with bolt holes and a central double-crack at 20 °C, 200 °C, 400 °C, and 600 °C were analyzed to clarify the structural damage and failure mechanism. This study is helpful for providing theoretical support for the design of high-temperature steel structures, improving the stability of the structure, and ensuring the bearing capacity of the structure and the safety of people’s lives and property.