ABSTRACT
Due to the large wall thickness difference and serious instability in the large-scale ring rolling process, most studies on the feed curve are not suitable for a large-scale ring. The production cost of the large-scale ring is high, and if plastic instability occurs, it will cause a great waste of resources. Therefore, in this study, a staged feed strategy based on the evolution of ring instability is proposed with the objective of controlling the rolling stability of a large-scale ring. Firstly, based on the law of rolling instability evolution, the rolling stage during the rolling process is divided. Secondly, the coordination of all rolling stages is proposed as a factor to design the feed curve. The feed scheme is determined using the central composite design (CCD) method, and then the established mathematical model is applied to obtain the radial feed curves of a large-scale flat ring with a 5 m diameter for different schemes. Next, the designed feed curve was submitted to finite element method (FEM) simulation. According to the FE simulation results, a rolling map for controlling roundness error, eccentricity and vibration is established. Finally, the feed curve in the stable region is input to the FE simulation and the production trial to obtain the results of roundness error, eccentricity and vibration. A comparison of the simulation and production trial results shows that they are in good agreement, which proves the reliability of the feed curve designed based on the stable rolling region in the roll map. Moreover, the machining amount for both the simulation and production trial is below the maximum machined value.
ABSTRACT
Background: The aim of this study was to investigate the specific mechanisms underlying the human health-promoting effects of the forest environment at Huangguoshu Falls, Guizhou, China. Methods: Ninety-five participants were recruited and an eye tracker was used to record fixation and sweep indices. A questionnaire was also used to evaluate the effects of different subject environments on human emotions, perceived recovery and preferences. Thereafter, 24 participants with chronic fatigue syndrome (CFS) were recruited and the participants' fatigue and stress-related scale indices and inflammatory factor levels were examined. Serum metabolites of the participants under different time waterfall forest interventions were detected by ultra performance liquid chromatography-quadrupole-time of flight mass spectrometry (UHPLC-Q/TOF-MS). Results: Eye tracking paradigm analysis showed that the "waterfall" element was the most interesting element for participants and that the "charm" of the waterfall forest environment could be well perceived by participants. Scores on the Fatigue Scale, Anxiety Scale and Depression Scale decreased as the duration of treatment in the waterfall forest environment increased. Levels of inflammatory factors decreased after treatment in the waterfall forest environment. At the same time the level of antioxidants, represented by L-ascorbic acid, increased significantly. Conclusions: The charm of the Huangguoshu waterfall scenery could be perceived by the participants and have a positive modulating effect on mood and cognitive function. In addition, the unique mixture of negative oxygen ions in this environment can increase the content of endogenous antioxidants and balance the metabolism of choline and amino acids.
ABSTRACT
Background: Forest therapy has been proven to have beneficial effects on people with depression and anxiety. However, it remains unknown whether the waterfall forest environment (WF) affects the physical and psychological health of patients with chronic fatigue and how the WF regulates chronic stress. Methods: Twenty-four patients with chronic fatigue were randomly divided into two groups: the WF group and the urban (U) group. Scores on the Hamilton Anxiety Scale (HAMA), Hamilton Depression Scale (HAMD), and Fatigue Scale-14 (FS-14) were evaluated before and after environmental intervention. Detection of physiological indexes and inflammatory factor levels and immunological analysis were also performed. In addition, the chronic stress rat model was constructed, and the effects of the WF on hopelessness and liver damage of rats were investigated. Results: Patients with chronic fatigue in the WF group showed a significant decrease in FS-14, HAMA, and HAMD scores compared with the U group. The expression levels of glutathione peroxidase and superoxide dismutase were remarkably higher in the WF group than in the U group. However, the expression levels of malondialdehyde and inflammatory factors (IL-1ß, TNF-α, IL-6, and IL-10) were remarkably decreased after the intervention of the WF. In addition, animal experiments confirmed that the WF improved hopelessness, liver damage, and excitability of neurons of chronic stress rats. Mechanistically, the WF reduced the liver damage caused by chronic stress in rats by inhibiting the NOX4/ROS/NF-κB signaling pathway. Conclusions: Collectively, the WF had a positive effect on immune enhancement and physical and psychological health in patients with chronic fatigue and might inhibit chronic stress by regulating the NOX4/ROS/NF-κB signaling pathway.
