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In this research, fatigue tests on full-size specimens are conducted for a steel cross-beam joint before and after reinforcement. Combined with a three-dimensional (3D) numerical simulation, the 3D stress parameters, and their redistribution rules study anew with a web crack and new crack initiation locations and fatigue weakness details are predicted. The research results include the following: 1) The empirical formula parameter m of the Z-axis stress for the new crack tip is approximately 0.05. 2) The fatigue performance of the web’s new crack tips is significantly improved by bolting reinforced steel plates, the stress range is reduced by 60%-98.78%, and the original crack stops growing in size. The health monitoring system can choose the predicted weak details as valid monitoring points so that the fatigue damage can be intelligently perceived after the reinforcement of steel bridges.

Two new compounds, compounds 1 and 2, were obtained from the culture of a marine-derived fungus Talaromyces sp. MCCC 3A01752, together with 13 known compounds (3–15). Their structures were elucidated based on detailed analysis of NMR, HRESIMS, ECD spectra and OR value. Compound 1 exhibited antibacterial potential against Staphylococcus aureus with a MIC value of 100 μM and cytotoxic activity against gastric cancer cell line MKN1 with a IC50 value of 78.0 μM. [ABSTRACT FROM AUTHOR]

High fluoride groundwater is not only harmful to the human body but also affects microbial community structure. To explore the influence of high fluoride groundwater environment on microbial diversity, 15 groups of groundwater samples were collected from Kuitun River Basin and subjected to high-throughput 16S rDNA gene sequencing, with the analysis focused on the chemical characteristics of high and low fluoride groundwater, microbial community structure, and the relationship between microbial community and environment. The results showed that the groundwater in the study area had weak alkalinity, and relatively high total dissolved solids (TDS). The average fluoride (F-) content was 1.5 mg/L, and the groundwater type was identified as HCO3·SO4-Na. The low fluoride group samples exhibited higher species abundance and diversity with similar microbial communities. In contrast, the high fluoride group samples displayed significant differences in microbial communities. Proteobacteria, Actinobacteria, and Bacteroidetes were identified as the dominant bacterial phyla in the groundwater. At the family level, the dominant bacteria belong to Proteobacteria. The concentrations of chemical oxygen demand (COD), TDS, and F- were found to be significantly correlated with the microbial community structure in groundwater, and these concentrations were negatively correlated with the abundance of most bacterial phyla. This study demonstrated that high fluoride groundwater environment suppressed the abundance and diversity of microorganisms. However, the microbial community was able to mitigate the toxicity of high fluoride groundwater through metabolic pathways, leading to the formation of a unique microbial community structure. These findings highlight the importance of microbial community self-regulation in the prevention and control of high fluoride groundwater pollution. [ABSTRACT FROM AUTHOR]

[Objective]This paper is to study the effects of the number of water inlets, the number of teeth of the trapezoidal flow channel and the number of outlets on the anti-clogging performance of the single-wing labyrinth drip irrigation belt. We designed nine groups of working conditions for numerical simulation.[Method]Physical experiments, numerical simulations, linear mathematical models were used to study water and sand flow in a single-wing labyrinth drip irrigation belt when the flow rate was 1.8 L/h, as well as the influence of different inlet and outlet numbers and trapezoidal flow channel teeth on the flow index and flow coefficient of the drip irrigation belt.[Result]The SST k-ω two-equation for low Reynolds number turbulence model is more suitable for numerical simulation of flow field in the single-wing labyrinth drip irrigation belt. From the inlet to the trapezoidal channel and then to the outlet, the mass concentration of sediment particles gradually decreases; the fifth water inlet of drip irrigation belt is the main water inlet, and the third water outlet is the main water outlet; the number of water inlets, trapezoidal channel teeth, and the number of water outlets have a minimal impact on flow regime index; the their impact on the flow coefficient is ranked in the order of trapezoidal channel teeth>number of water outlets>number of water inlets; a multivariate linear model between the flow coefficient and the three factors was constructed, with a decision coefficient being 0.987.[Conclusion]When the size of the trapezoidal labyrinth flow path is the same, the smaller the number of teeth in the trapezoidal flow path was, the greater the internal flow velocity in the flow path would be. This facilitates discharge of sediment particles from the flow path. The constructed flow coefficient and three factor formula can achieve accurate irrigation at the outlet location, making reasonable use of land resources. [ABSTRACT FROM AUTHOR]

(Objective) Emitter cologging is a common issue in drip irrigation. This paper studies the effects of laying slope, sediment content and operating pressure on irrigation uniformity and flow drop of the inlaid patch drip irrigation in attempts to reduce clogging of the drip irrigation belt.(Method) The experiment was design using a uniform orthogonal test plan with three factors and three levels: laying slope (-1, 0, 1%), sediment content (1, 2, 3 g/L) and operating pressure (40, 70, 100 kPa). The experiment was conducted in a laboratory using 30 m drip irrigation belts.(Result) The factors that influence irrigation uniformity are ranked in the order of sediment content > laying slope > operating pressure. The factors that impact flow drop are ranked in the order of sand content > operating pressure > laying slope. Regression models for estimating irrigation uniformity and flow drop using the sediment content and operating pressure were accurate, with its standardized root mean square errors being 2.98% and 2.42%.(Conclusion) Sediment content is an important factor affecting the clogging of the inlaid patch drip irrigation belt. The models we presented to link sediment content, laying slope and operating pressure to irrigation uniformity and flow rate drop were accurate and can be used for design. [ABSTRACT FROM AUTHOR]

By means of physical modeling and numerical simulation, this paper makes a systematic study on oil displacement mechanism by air injection in low permeability reservoirs. Based on the findings, production performance by air drive is studied through the application of a real low permeability reservoir model. Studies show that air intake capacity is far greater than water intake capacity in low permeability reservoirs. Therefore, air injection, which can effectively supplement and maintain reservoir pressure, can build effective pressure displacement system much easier than water injection. Low-temperature oxidization reaction will occur between oil and the oxygen in air, which consumes oxygen and forms nitrogen drive. At the same time, CO2 and large amounts of heat are generated, and the temperature in some parts of the reservoir can reach about 200°C. Nitrogen drive contributes 69%; temperature increasing and CO2 generation contribute 26.7% and 4.3% respectively for the total recovery of air drive. Recovery factors by air drive, nitrogen drive and water drive are also studied respectively by using the real low permeability reservoir model. Recovery factor by air drive for 30 years reaches 21.5%, and it is twice as large as that of water drive, which is 10.6% for the same period. Production performance is significantly improved. Air drive is an effective way for improving production performance and increasing recovery factor. 摘 要: 采用物理模拟和数值模拟相结合的方法，系统研究了低渗油藏注空气开发的驱油机理，在此基础上应用实际低渗油藏模型研究了空气驱的开发效果。研究表明，低渗油藏吸气能力远大于吸水能力，注空气比注水更容易建立起有效的压力驱替系统，起到有效补充或维持油层压力的作用。空气中的氧气与原油发生低温氧化反应，消耗掉氧气形成氮气驱，同时产生大量热量和二氧化碳，部分油藏温度升高到200 ℃左右。氮气驱对空气驱总采收率的贡献为69%，温度升高和二氧化碳对采收率的贡献分别为26.7%、4.3%。应用实际低渗油藏模型研究了空气驱、氮气驱和水驱的采收率，空气驱30 a的采收率达到了21.5%，较水驱30 a年采收率10.6%提高了1倍，开发效果得到明显改善。空气驱是低渗油藏改善开发效果、 提高采收率的有效方式。图11表2参13 Key words: low permeability reservoir, air injection, nitrogen drive, displacement mechanism, low-temperature oxidation, recovery factor