Osteoarthritis (OA) is a disease in which articular cartilage wears down due to degeneration associated with aging, which makes adjacent bones contact each other and causes pain. Considering that OA changes the mechanical properties of cartilage when it degenerates, it is important to investigate its mechanical properties under impact load. Therefore, in this study, dynamic and quasi-static tests using the split-Hopkinson pressure bar (SHPB) were carried out on healthy cartilage and cartilage with collagen fibers degenerated by enzyme treatment. The differences in elastic moduli over a wide range of strain rates were examined. To obtain the mechanical properties of soft tissue, polymethyl methacrylate was used for the input and output bars of the SHPB because of its low mechanical impedance, which is suitable for highly compliant materials. Healthy and degenerated cartilage specimens were prepared to clarify the difference in mechanical properties, and quasi-static compression and SHPB tests were performed. The results showed that the elastic modulus increased with increasing strain rate, revealing that the strain rate dependency affects both healthy and degenerated articular cartilage. However, in the high-strain-rate region, a significant positive correlation was observed in healthy cartilage, but no correlation was observed in degenerated cartilage. This suggests that, in degenerated cartilage, resistance to static and dynamic loads, as well as viscosity, decreased at a high strain rate. According to the biphasic theory, the higher the strain rate is, the more it tends to limit interstitial water flow, which explains the increase in elastic modulus in the high-strain-rate region. Therefore, these results suggest that degeneration of collagen fibers in the cartilage reduces the resistance to internal water flow and to static and dynamic loads.

Interpretation for the two-week long Unit 3 ex-vessel debris cooling behavior was conducted based on the Fukushima-Daiichi Nuclear Power Plant (1F) data and the site data such as pressure, temperature, gamma ray level and live camera pictures. It was estimated that the debris relocated to the pedestal was in partial contact with liquid water for about initial two days. With the reduction of the sea water injection flowrate, the debris, existed mainly in the pedestal region, became “dry”, in which the debris was only weakly cooled by vapor and this condition lasted for about four days until the increase of the sea water injection. During this dry period, the pedestal debris was heated up and it took further days to re-flood the heated up debris.

Non-contact detection methods based on computer vision are widely used in industrial production. When collecting images, different light source schemes are often used to meet the detection requirements of different objects. The image styles collected under different lighting scenes are diverse, and the image semantic segmentation model trained with a specific dataset has unsatisfactory performance when processing images in different domain. This paper designs a mechanical part image semantic segmentation model based on domain adaptation and GAN. In order to verify the effectiveness of the proposed method, this paper collects and labels some gear images and constructs a dataset. The first step is to train encode-decoder structure with an enhanced memory module with source dataset to achieve semantic segmentation, then the dataset is transformed into a target domain by GAN, and finally the image semantic segmentation model is fine-tuned with the target dataset. The advantage is that since the cycle-consistency loss is used to constrain the spatial structure of the reconstructed image, the two datasets can share a semantic segmentation label. Experiments show that the image semantic segmentation method based on domain adaptation has achieved good results on different styles of gear parts image datasets, and achieved a pixel accuracy of 94.1%.

Plume interference effects on the discharge characteristics and thruster performance for two heads system were investigated to evaluate the optimum design of the Hall thruster cluster system using the anode-layer head. An anode-layer head with a racetrack shape acceleration channel was designed in this study to better capture the interference effects. The racetrack-shaped head has straight parts and can certainly capture the plume interference effect. The system is termed a side by side (SBS) Hall thruster system because the two heads are positioned in a straight line to sandwich one hollow cathode. The SBS system’s discharge characteristics and thruster performance were assessed. It was indicated that the thruster performance was better improved in SBS operations than the sum of the single operations. The thruster performance is also influenced by the interaction of the two heads’ magnetic field directions. The effect of the plume interference on the amplitude increase point, which is the inner coil current when the discharge current oscillation amplitude increases rapidly, was evaluated to examine the stable operation range. The increased point also depends on the interaction of the magnetic field directions. These findings suggest that plume interference has an impact on the ionization through the backflow electron. Furthermore, a head susceptible to plume interference substantially impacts the behavior of the total discharge current due to individual head differences.