Search

The double-disk arc-contact lapping (DDACL) method is a novel for precision machining of the rolling surface of cylindrical roller. The contact characteristics of DDACL process can affect the lapping quality of the bearing roller. However, there is a limited amount of study on the contact theory of DDACL. Therefore, the objective of this research is to create a semi-analytical modeling approach that can effectively and accurately forecast the contact characteristics of DDACL. In the initial step, the spatial coordinate transformation was employed to establish accurate mathematical models that represents the surfaces of the cylindrical roller and arc groove. Subsequently, the potential contact area was determined and subdivided into discrete elements based on the differential geometry principles. The accurate flexibility of the potential contact area is achieved by utilizing the interpolation theory and considering both the global and local deformations of the roller and groove. By employing the influence coefficient method and the force-deformation coordination relation, the deformation and contact force can be calculated. Finally, the accuracy and efficiency of this calculation is confirmed through a comparison between the finite element method (FEM) and the proposed method. [ABSTRACT FROM AUTHOR]

The working conditions of planetary gearboxes are complex, and their structural couplings are strong, leading to low reliability. Traditional deep neural networks often struggle with feature learning in noisy environments, and their reliance on one-dimensional signals as input fails to capture the interrelationships between data points. To address these challenges, we proposed a fault diagnosis method for planetary gearboxes that integrates Markov transition fields (MTFs) and a residual attention mechanism. The MTF was employed to encode one-dimensional signals into feature maps, which were then fed into a residual networks (ResNet) architecture. To enhance the network's ability to focus on important features, we embedded the squeeze-and-excitation (SE) channel attention mechanism into the ResNet34 network, creating a SE-ResNet model. This model was trained to effectively extract and classify features. The developed method was validated using a specific dataset and achieved an accuracy of about 98.1%. The results demonstrate the effectiveness and reliability of the developed method in diagnosing faults in planetary gearboxes under strong noise conditions. [ABSTRACT FROM AUTHOR]

The performance and reliability of lithium thionyl chloride (Li/SOCl2) batteries are significantly affected by temperature, but the reliability level and failure mechanisms of Li/SOCl2 batteries remain unclear. In this study, Weibull distribution statistics were used to infer the life expectancy of Li/SOCl2 batteries at different temperatures. Additionally, the battery failure mechanism was analyzed using electrochemical impedance spectroscopy (EIS). It is found that under the discharge condition of 7.5 kΩ load, the mean time between failures (MTBF) and reliable life of the battery decreased with increasing operating temperature. Under the discharge condition of 750 Ω load, the MTBF of the battery peaked at 60 °C. Furthermore, the influence of temperature on the voltage output characteristics of Li/SOCl2 batteries and the voltage hysteresis were analyzed. Both the battery output voltage and the hysteresis effect increased with rising temperature. This is because high temperature accelerates internal battery reactions, thus altering the formation process of the passivation film on the lithium metal negative electrode. [ABSTRACT FROM AUTHOR]

Offshore gas hydrates are being focused on as an unconventional energy source. The susceptibility of marine hydrate reservoirs to sand emergence makes them unsuitable for long-term exploitation. This research delves into the particle-transport law in hydrate reservoirs, revealing that sand blockage hinders long-term exploitation, and proposes a reservoir modification strategy to establish high-permeability channels, thereby enhancing production. After 110 days of mining, the range of porosity and permeability below the initial value was approximately 8.5 m. The study further optimizes reservoir modification parameters under sand blockage, suggesting that a balance between fracture and reservoir blockage can be achieved with a fracture half-length of 20 m, leading to increased production. It also highlights that the slow decomposition of blocked hydrate and the accumulation of decomposed methane gas in the upper part of the reservoir can be leveraged to increase production by providing a high permeability channel for free gas, concluding that maintaining long-term high permeability is crucial for hydrate reservoir fractures. • The highlights of the paper are: • Determined that sand blockage is the main reason why the hydrate reservoir cannot be exploited for a long time. • Proposed a method for reservoir modification to break through the blockage range to increase production. • The optimization of hydrate reservoir modification parameters under sand blockage is investigated. [ABSTRACT FROM AUTHOR]

In this study, ZnCo 2 O 4 nanosheets and NiCo 2 O 4 nanowires were successfully grown on nickel foam as anode materials for lithium-ion batteries by a low-temperature hydrothermal and immersion method. The nanosheets offered an enlarged electrically active surface area, and the nanowires provided support for the nanosheets, thereby forming a heterojunction interface. The ZnCo 2 O 4 /NiCo 2 O 4 heterojunction demonstrated favorable electrochemical performance in electrochemical tests. In terms of its rated performance, the capacity of the composite electrode recovered to 1050 mAh g -1 when the current density ranged from 0.1 to 1 A g -1 ; its capacity was maintained even when the current density returned to 0.1 A g -1 after 60 cycles. The diffusion coefficient of lithium ions ( D Li + ) increased due to the reduction of the interfacial contact resistance under the interfacial electric field of the heterostructure, and they were continuously activated during repeated cycles. This further significantly enhanced the electrochemical activity of the electrode. The analysis results based on the density functional theory revealed the hybridization of the 3d orbitals of Ni and Zn and the augmented electronic state occupancy of the orbitals near the Fermi energy level. This process was accompanied by the migration of electrons, leading to a decrease in the band gap. Meanwhile, the Li + diffusion barrier decreased, and the conductivity of the electrode materials was enhanced.