Numerical Simulation of Gear Heat Distribution in Meshing Process Based on Thermal-structural Coupling

The thermal balance state of high-speed and heavy-load gear transmission system has an important influence on the performance and failure of gear transmission and the design of gear lubrication system. Excessive surface temperature of gear teeth is the main cause of gluing failure of gear contact surface. To investigate the gear heat distribution in meshing process and discuss the effect of thermal conduction on heat distribution,a finite element model of spur gear is presented in the paper which can represent general involute spur gears. And a simulation approach is use to calculate gear heat distribution in meshing process. By comparing with theoretical calculation, the correctness of the simulation method is verified, and the heat distribution of spur gear under the condition of heat conduction is further analyzed. The difference between the calculation results with heat conduction and without heat conduction is compared. The research has certain reference significance for dry gear hobbing and the same type of thermal-structural coupling analysis

Tumor Mutation Burden Predicts Relapse in Papillary Thyroid Carcinoma With Changes in Genes and Immune Microenvironment

BackgroundThe risk factors of papillary thyroid carcinoma (PTC) recurrence are meaningful for patients and clinicians. Tumor mutation burden (TMB) has been a biomarker for the effectiveness of immune checkpoint inhibitor (ICI) and prognosis in cancer. However, the role of TMB and its latent significance with immune cell infiltration in PTC are still unclear. Herein, we aimed to explore the effect of TMB on PTC prognosis.Material and MethodsRNA-seq and DNA-seq datasets of PTC patients were downloaded from The Cancer Genome Atlas (TCGA) database. The Gene Ontology (GO) and gene set enrichment analysis (GSEA 4.0.1) were applied further to explore potential differences in PTC patients’ biological functions. The differentially expressed genes (DEGs) and immune microenvironment between the high and low TMB groups were determined.ResultsTMB had the highest AUC score than other clinical indicators in ROC analysis on recurrence-free survival, and a higher TMB score was related to a worse prognosis. Further, GSEA showed a higher level of oxidative phosphorylation (OXPHOS) in the high TMB group, and four genes correlated with recurrence-free survival rate were identified. The abundance of CD8+ T cells and M1 macrophages in the high TMB group was significantly lower than that in the low TMB group.ConclusionsOur study found that TMB was a better predictor variable at evaluating the risk of PTC recurrence. Moreover, TMB-related genes conferred dramatically correlated prognosis, which was worth exploring in guiding postoperative follow-up and predicting recurrence for PTC patients

Anisotropy and energy evolution mechanism of rock mass under true triaxial loading-unloading

In the process of underground excavation, the surrounding rock is in a very complex stress environment, especially under the influence of its anisotropy, the occurrence of dynamic disaster is hidden. In this paper, the loading and unloading tests of sandstone in different principal stress directions were carried out by using the true triaxial unloading disturbed rock test system. The mechanical properties and failure characteristics of true triaxial under different principal stresses were studied, the energy evolution mechanism in other directions induced by loading and unloading of different principal stresses was analyzed. Results showed that under the influence of rock mass secondary stress anisotropy, during the cyclic loading and unloading process of the first principal stress, the strain in other directions shows opposite deformation. The volumetric strain compresses first and then expands, and the final volumetric strain shows a macroscopic phenomenon of expansion. When the third principal stress of high confining pressure rock mass is unloaded, the first principal stress produces a compression deformation, while the second and third principal stresses produce an expansion deformation. The deformation of the second principal stress is less than that of the third principal stress, and the deformation in unloading direction changes from linear elastic state to elastic-plastic nonlinear state. The accumulated energy of rock mass is a great difference between the first principal stress unloading and the third principal stress unloading. The energy variation characteristics of unloading in the dominant direction determine the energy accumulation and release law in the other two induced directions. The limit stored energy of the third principal stress unloading rock decreases, and the second principal stress accelerates the rock failure with the increase of the first principal stress, which verifies that the rock is easier to be destroyed by unloading than by loading. The higher the unloading rate of the third principal stress, the higher the energy released and the lower the dissipated energy, and the lower the energy density and total accumulated energy density in the unloading direction of rock mass. The main cause of dynamic accidents is the accumulation and release of energy in rock mass. The secondary anisotropy of rock mass has a great influence on the ultimate stored energy of rock mass. The study on the influence characteristics of three-dimensional loading and unloading secondary stress on the ultimate stored energy of rock mass provides a reference for preventing rock burst

Study on fluorescence characteristics of the Ho 3+ :ZBLAN fiber under ~640 nm excitation

Abstract(#br)We investigated the absorption and emission characteristics of the Ho 3+ :ZBLAN fiber under ~640 nm excitation. Based on the Judd-Ofelt theory, a detailed spectroscopic analysis on excited states 5 I 6 and 5 I 7 of the Ho 3+ -ion was performed. The population dynamics was conducted by using the rate equation method, and a set of analytical expressions for population densities of various levels were obtained at steady state. Moreover, the fluorescence intensities of the 5 S 2 , 5 F 4 → 5 I 7 , 5 I 8 and 5 I 6 → 5 I 7 , 5 I 8 and 5 I 7 → 5 I 8 transitions were measured in different pumping powers. The simulated and experimental results are quite consistent. This work could provide the spectral information for optimal design of the visible oscillations in the Ho 3+ :ZBLAN fiber excited at ~640 nm

Conceptional Designs of the Rotation Mechanism with Antiphase Energy Harvester

Due to the increased demand for a sustainable source of energy, the research on energy harvesting has increased in the last twenty years. Energy harvesting aims to gain energy from the ambient environment and convert this energy into electrical power. There are different kinds of renewable energy sources and vibration energy harvesting (VEH) is the most promising source owing to its low maintenance cost. This paper focuses on an electromagnetic vibration energy harvester based on the concept of rotational energy harvesting. The proposed device uses a rotating rotor with permanent magnets and moves the repulsive magnet block up and down. The block is connected to an antiphase harvester, which creates power by cutting the magnetic flux density. The antiphase was proven to double the voltage when the antiphase was moving. To improve the vibration amplitude of the magnet block and the antiphase, springs were added to the proposed design. In the concept, four configurations—with and without different spring positions—were proposed. The experimental results showed that when the spring was placed in the upper and bottom part of the moving part, the spring at the bottom would generate the largest vibration amplitude. Based on Faraday’s Law of Induction, voltage is proportional to the velocity or vibration amplitude. Hence, for both cases, at least six times the voltage was generated compared to the design without added springs

Effect of Calcination Conditions on the Performance of Co-precipitation Catalyst

The Fe-Co-Ce composite catalysts were prepared by co-precipitation method, and the effect of calcination temperature and calcination time on the performances of the Fe-Co-Ce composite catalysts were investigated. The results indicated that the optimum calcination temperature and calcination time of the Fe-Co-Ce composite catalysts were 450 °C and 7 h, respectively. Using the catalysts which prepared under the optimum calcination conditions catalytic wet oxidation of methyl orange simulated wastewater, after 90 min, the COD, COD removal rate, absorbance, decolorization rate and pH of the methyl orange simulated wastewater were 737.7, 70.5%, 0.348, 95.3%, and 5.31, respectively. According to the analyses of the SEM, FTIR, and TG-DTA curves, the components of the catalysts which prepared under the optimum calcination conditions distributed evenly, and the chemical compositions of the catalysts including C-O, -OH, and H-O-H, showing a good thermal stability

Effect of Calcination Conditions on the Performance of Co-precipitation Catalyst

The Fe-Co-Ce composite catalysts were prepared by co-precipitation method, and the effect of calcination temperature and calcination time on the performances of the Fe-Co-Ce composite catalysts were investigated. The results indicated that the optimum calcination temperature and calcination time of the Fe-Co-Ce composite catalysts were 450 °C and 7 h, respectively. Using the catalysts which prepared under the optimum calcination conditions catalytic wet oxidation of methyl orange simulated wastewater, after 90 min, the COD, COD removal rate, absorbance, decolorization rate and pH of the methyl orange simulated wastewater were 737.7, 70.5%, 0.348, 95.3%, and 5.31, respectively. According to the analyses of the SEM, FTIR, and TG-DTA curves, the components of the catalysts which prepared under the optimum calcination conditions distributed evenly, and the chemical compositions of the catalysts including C-O, -OH, and H-O-H, showing a good thermal stability