The thermal deformation of high-speed motorized spindle will affect its reliability, so fully considering its thermal characteristics is the premise of optimal design. In order to study the thermal characteristics of high-speed motorized spindles, a coupled model of thermal-flow-structure was established. Through experiment and simulation, the thermal characteristics of spiral cooling motorized spindle are studied, and the U-shaped cooled motorized spindle is designed and optimized. The simulation results show that when the diameter of the cooling channel is 7 mm, the temperature of the spiral cooling system is lower than that of the U-shaped cooling system, but the radial thermal deformation is greater than that of the U-shaped cooling system. As the increase of the channel diameter of U-shaped cooling system, the temperature and radial thermal deformation decrease. When the diameter is 10 mm, the temperature and radial thermal deformation are lower than the spiral cooling system. And as the flow rate increases, the temperature and radial thermal deformation gradually decrease, which provides a basis for a reasonable choice of water flow rate. The maximum error between experiment and simulation is 2°C, and the error is small, which verifies the accuracy and lays the foundation for future research.

Augmented reality (AR) technology, as a computer simulation technology, combines various technologies such as virtual reality, computer vision, computer network, and human-computer interaction. AR has been widely used in medicine. The introduction of AR can effectively help doctors complete preoperative planning, intraoperative guidance, postoperative evaluation and medical training. Oral medicine is a major branch of modern medicine. AR can enhance the doctor’s visual system, making the internal structure of the oral clearer and effectively reducing the difficulty of oral repair/surgery. Real-time tracking, registration, display, and interactive technologies for AR will play an important role in oral medicine. Among them, the registration technology has become an important indicator for evaluating the AR system, and it is also the main bottleneck restricting the stability and applicability of the current AR system. Therefore, we reviewed the registration technology of AR in oral medicine. Firstly, we conducted a hot spot analysis of AR keywords based on Citespace. And then, the registration technology is divided into static registration and real-time registration according to the actual clinical application, among which static registration is divided into rigid registration and non-rigid registration. We discussed problems and limitations of static registration and real-time registration in oral applications at this stage. Finally, the future direction of AR registration technology in oral medicine is proposed.

The reptile search algorithm (RSA) is a swarm-based metaheuristic algorithm inspired by the encirclement and hunt mechanisms of crocodiles. Compared with other algorithms, RSA is competitive but still suffers from low population diversity, unbalanced exploitation and exploration, and the tendency to fall into local optima. To overcome these shortcomings, a modified variant of RSA, named MRSA, is proposed in this paper. First, an adaptive chaotic reverse learning strategy is employed to enhance the population diversity. Second, an elite alternative pooling strategy is proposed to balance exploitation and exploration. Finally, a shifted distribution estimation strategy is used to correct the evolutionary direction and improve the algorithm performance. Subsequently, the superiority of MRSA is verified using 23 benchmark functions, IEEE CEC2017 benchmark functions, and robot path planning problems. The Friedman test, the Wilcoxon signed-rank test, and simulation results show that the proposed MRSA outperforms other comparative algorithms in terms of convergence accuracy, convergence speed, and stability.