Search

Research background: Twisties symptoms have attracted the world's attention in the sports field since the 2020 Tokyo Olympics. Aim: However, studies on the symptoms and causes, inducing mechanisms, and relationships between DP/DR (Depersonalization/Derealization Disorder) and anxiety and depression for athletes have been sparse for both the general population and athletes. The literature on the twisties issue of athletes is quite scarce in the past. Research method: Adopting the criteria appealing to PRISMA Items to review the subject twisties in a broader mode and combing with the IPO (Input-Process-Output) model for triangulation testing purpose, this study categorized the literature to explore input variables causing athletes’ twisties and identified process variables in psychological mechanisms bridging suppression and finally discussed the existing possible ways in helping athletes to solve problems caused by twisties. Results: The authors formed 6 propositions in summarizing twisties' influential factors and mechanisms and tried to propose solutions to reduce the stress and the relevant twisties symptom of athletes. (1) Promotion of Athletes' Mental Toughness to Resist Stressors. (2) Interventions that correct for cognitive misinterpretations and appropriate relaxation and mindfulness practice in correcting a range of attention might reduce DP/DR. (3) Monitoring the athlete's HRV test results to ensure the Athlete's ability to resist pressure. (4) Avoid organizational stressors. (5) Written Emotional Disclosure method. (6) Improve various support systems for athletes: dual career paths. (7) Athletes' Stressful Awareness about the impact of gender, seniority, and environment. Conclusion: Through the theoretical dialogue on the symptom of twisties, this study helps promote the development of the research of “twisties” and depersonalization-derealization symptoms (DDS); both have been under-researched.

This paper firstly compares the common virtual reality technology production methods, determines the reasonable lower limb rehabilitation exercise modeling method, establishes a more accurate human lower limb musculoskeletal rehabilitation posture mechanism model, analyzes the passive movement work mode of lower limb rehabilitation exercise, and simulates the changes of human musculoskeletal changes during passive movement of lower limb rehabilitation which exercise robots were analyzed. Secondly, the research is on robust controller for omni-directional mobile lower limb rehabilitation based on artificial intelligence and medical big data. The error dynamic model of omni-directional moving lower limb rehabilitation exercise system is established, and the technical problems of standard design, dissipative and gain are analyzed. By constructing the storage function and using the inverse push method, the nonlinear robust controller for omnidirectional moving lower limb rehabilitation motion is designed. The stability of this control law is proved based on Lyapunov's theorem. Finally, an experimental study on the omni-directional moving lower limb rehabilitation exercise system and rehabilitation evaluation system. Seven human gait and online detection methods for rehabilitation exercise were proposed. The simulation study on the omni-directional moving lower limb rehabilitation robot using nonlinear robust controller is carried out to verify the effectiveness and correctness of the lower limb exercise rehabilitation method.

In this work, the tensile-shear mechanical behaviors of friction stir spot weld and adhesive hybrid joint were performed from both numerical and experimental viewpoints. Weld through (WT) and flow in (FI) processes were studied in this research. The focus was to evaluate joint defects, tensile-shear failure load (TSFL), failure energy, failure mode and stress distribution of the joint. In FI joints, keyhole and hook defects appeared in the weld zone and the areas of material removed from the base metal were filled with adhesive. In the WT joints, the adhesive layer close to the weld zone was carbonized due to the welding heat. Meanwhile, under the rotating movement of welding tool, the adhesive impurities entered the stirring zone (SZ) and heat affected zone (HAZ) of the weld, which decreased mechanical performances of WT joints. Compared to the friction stir spot welding (FSSW) joint, the TSFL value, stiffness and failure energy of FI joint were increased by 2.7, 1.1 and 8.14 times, respectively. In order to study the stress distribution of the joints, a finite element (FE) model, which considered the weld structure and mechanical properties of weld regions, was implemented. Moreover, the adhesive layer was simplified by the cohesive zone model (CZM). FE results show that the FI process effectively decreases the stress concentration of the weld edge from 243.09 to 15.5 MPa, under the 2 kN tensile load. The weld can block the adhesive crack propagation, and the adhesive optimized the stress distribution of FI joints through a synergistic effect. So, the use of FI process for aluminum alloy connection is strongly recommended, especially in crucial structure areas.

This paper introduced a hybrid joining system including friction stir spot welding (FSSW) and adhesive bonding, named friction stir spot weld bonding (FSSWB). In order to avoid adhesive layer carbonization, FSSWB was processed by flow-in method. The aim of this study was to evaluate the effect of adhesive ductility and joint configuration on the tensile-shear performances of AA6061 aluminum alloy. Two types of adhesives were considered: brittle epoxy (AV138) and ductile epoxy (Araldite 2015). Besides, hybrid joints involve three types of joint configurations (AV138, Araldite 2015 and dual adhesive). A finite element (FE) model of hybrid joints failure process was established based on the extended finite element method (XFEM) and cohesive zone model (CZM). The tensile-shear failure load (TSFL) prediction values and joint failure process were in good agreement with the experiments. Compared to FSSW, the TSFL values for the three types of hybrid joint increased by 166.5%, 294.8% and 173.8% respectively. In addition, the stresses at the hook tip of the three hybrid joints were decreased by 85.56%, 79.31% and 83.67%. From the study, it was found that the use of ductile adhesives at two sides of joint was more helpful to increase the load-bearing capacity of FSSWB joints. [ABSTRACT FROM AUTHOR]