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Two-stage reciprocating small oil-free air compressors have been widely used in various fields due to their high exhaust pressure and low power consumption, but the vibration and noise problems seriously affect the comfort of use. In order to improve the compressor vibration, the theory of dynamic balancing of a two-stage reciprocating air compressor was developed and a virtual prototype simulation was carried out using Adams software to establish an objective function to optimize the balance block counterweight of its crankshaft-piston system. Subsequently, in view of the close connection between the motor and thel compressor structure, the theoretical study and analysis of the dynamic balance of the crankshaft piston system and the motor rotor as a whole was carried out, and the dynamic balance scheme was further improved. Based on the above dynamic balance theory, vibration and noise tests are carried out and the noise are all reduced to a certain extent, verifying the reasonableness of the dynamic balance theory of the two-stage reciprocating small air compressor.

In order to provide a comprehensive reference for the study of carbon dioxide displacement of coalbed methane, this paper explores the influence of different influencing factors on coal adsorption capacity, analyzes the gas migration and adsorption principle in coal bed, as well as the difference and relationship between different adsorption models, and introduces the pilot test and application of CO2-enhanced coalbed methane recovery in different countries. Using VOSviewer software and CNKI metrological visualization analysis function, this paper analyzes the annual publication trend and keyword time trend of CO2-ECBM related literature in CNKI and Web of Science databases, and discusses the problems existing in CO2-ECBM. The results show that coal rank and pore structure, temperature and pressure, moisture content and other factors can affect coal adsorption capacity in different forms. Gas migration in coal seam is a complex system composed of adsorption/desorption-diffusion-seepage. The best adsorption model should be considered in studying coal adsorption gas. Based on VOSviewer analysis, CO2-ECBM research is a hot topic in China. The research direction has gradually shifted from macroscopic geological storage evaluation to reveal the mechanism of coal storage and displacement gas from microscopic or molecular levels such as pore structure and composition of coal, and multi-field coupling simulation of CO2-ECBM.

The majority of a coal mine's goaf is semi-closed complex porous medium space, which is a critical place for coal spontaneous combustion disasters. To investigate the flow diffusion pattern of inorganic compounds in fractured coal in the goaf, as well as the capacity to put out coal fires. It examine the viscosity properties of an inorganic material slurry as a function of water/material ratio and time. By building a three-dimensional grouting test platform in the lab, simulating the broken coal body with sand and gravel, designing orthogonal tests to run multiple groups of grouting tests, and analyzing the effects of factors besides grouting pressure, water/material ratio, and air space ratio on the slurry diffusion radius. The effect of grouting pressure on the pattern of slurry diffusion radius of inorganic material and the water/material ratio under the action of grouting pressure is studied. The test of inorganic materials to extinguish coal pile fire is done, and the fire extinguishing and cooling ability is assessed in comparison to mud of the same grade, based on a prior research of inorganic materials to suppress CO formation in coal oxidation warming. According on the findings, the three-dimensional grouting test platform can pass the grouting test of loose sand and gravel bodies at various grouting pressures. The effects of grouting pressure, water/material ratio, and air space ratio on slurry dispersion are discovered to be multivariate power function relationships rather than linear correlations. The related slurry diffusion radius equation is established, and the variables impacting the parameters of the slurry diffusion range are evaluated, with the grouting pressure and water/material ratio having a substantial impact on slurry diffusion. Inorganic materials, as opposed to mud, require less time to extinguish coal pile fires and are less prone to scatter. It can form an oxygen barrier through continually covering the surface of coal. The study's findings might give a solid foundation for the avoidance of slurry and fire suppression of inorganic materials in the goaf. [ABSTRACT FROM AUTHOR]

Background: Hot flashes are a common side effect of endocrine therapy (ET) that contribute to poor quality of life and decreased treatment adherence. Methods: Patients with breast cancer wo were receiving ET and experiencing hot flashes were enrolled through three parallel, randomized trials conducted in the United States, China, and South Korea. Participants were randomized to either immediate acupuncture (IA) or delayed acupuncture control (DAC). IA participants received 20 acupuncture sessions over 10 weeks, whereas DAC participants received usual care, then crossed over to acupuncture with a reduced intensity. The primary end point was a change in score on the endocrine symptom subscale of the Functional Assessment of Cancer Therapy (FACT)‐Endocrine Symptoms between baseline and week 10. Secondary end points included the hot flash score and the FACT‐Breast score. A planned pooled analysis of individual patient data was performed using longitudinal mixed models. Results: In total, 158 women with stage 0–III breast cancer were randomized (United States, n = 78; China, n = 40; South Korea, n = 40). At week 10, IA participants reported statistically significant improvements in the endocrine symptom subscale score (mean change ± standard error: 5.1 ± 0.9 vs. 0.2 ± 1.0; p =.0003), the hot flash score (−5.3 ± 0.9 vs. −1.4 ± 0.9; p <.003), and the FACT‐Breast total score (8.0 ± 1.6 vs. −0.01 ± 1.6; p =.0005) compared with DAC participants. The effect of the acupuncture intervention differed by site (p =.005). Conclusions: Acupuncture led to statistically and clinically meaningful improvements in hot flashes, endocrine symptoms, and breast cancer‐specific quality of life in women undergoing ET for breast cancer in the United States, China, and South Korea. In a pooled analysis of three parallel trials, acupuncture significantly reduced hot flashes and other endocrine symptoms in women with stage 0–III breast cancer undergoing endocrine therapy in the United States, China, and South Korea. In the women studied, acupuncture led to statistically and clinically meaningful improvements in hot flashes, endocrine symptoms, and breast cancer‐specific quality of life. [ABSTRACT FROM AUTHOR]