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Constitutive model of stone masonry is an important foundation and prerequisite for physical calculation and finite element numerical simulation of stone masonry. In order to further study the constitutive relationship of stone masonry under uniaxial compression, based on the theory of damage mechanics, the two-parameter Weibull distribution function was applied to reflect the damage variable, and its parameters were determined according to the characteristic conditions of the whole process of the stress-strain curve of stone masonry under uniaxial compression. The uniaxial compression damage constitutive model of stone masonry was derived and established, and the correctness of the constitutive model was verified by the existing test data. The constitutive model was compared with the typical masonry constitutive model. Finally, the finite element analysis of the existing stone masonry arch bridge test was carried out to verify the applicability of the constitutive model. The results show that the model is in good agreement with the uniaxial compression test results of existing stone masonry. The established model verifies the general law of masonry damage evolution and accords with the general trend of typical masonry constitutive model. The model can be applied to the finite element analysis and calculation of masonry structure with good applicability. [ABSTRACT FROM AUTHOR]

The purpose of this project is to guide students in independently designing experiments based on problemoriented approach, taking a commonplace phenomenon (white flocs formed during laundry) as the starting point. The measurement of surface tension is integrated into the process of exploring the underlying chemical principles of daily life phenomena, and an exploratory experimental model that follows a “problem identification-practical explorationtextbook consolidation” framework is established by combining a diverse array of techniques, thereby reinforcing the students’ understanding of colloid and interface chemistry. The revised experiment offers richer content, greater challenges, enhanced comprehensiveness, and increased engagement, effectively fostering students’ abilities to analyze and solve problems and nurturing their inquisitive thinking. Furthermore, this experiment ensures a high degree of safety, ease of operation, and requires no specialized equipment, making it highly suitable for undergraduate instructional labs. [ABSTRACT FROM AUTHOR]

The coastal waters along the northern Shandong Peninsula waters is rich in fishery resources, which is the passing fishing ground for economic organisms to enter the Bohai Sea to spawn and leave for winter. In recent years, overfishing and pollution have caused considerable damage to fishery resources there, and zooplankton has been adversely affected. Based on sampling data in this area from 2016 to 2017, the spatial and temporal distribution, structure community, dominant species and diversity indices of zooplankton community were analyzed. 39 species of zooplankton and 13 classes zooplankton larvae were record during the four surveys, which belonged to 11 phyla and most species were found in autumn. The dominant species had obvious seasonal change, Calanus sinicus, Labidocera bipinnata and Sagitta crassa were the main dominant species record, among them, Calanus sinicus was the dominant species in four surveys. Influenced by the Bolai coastal current, Yellow Sea warm current and Yellow Sea cold water mass, the seasonal variation of zooplankton abundance was obvious, with the highest abundance (147.1 ind·m–3) in spring and the lowest abundance (37.3 ind·m–3) in winter. The horizontal distribution of zooplankton abundance was uneven, with higher abundance in the western ocean near Zhifu Island in spring and autumn, while the concentration center located in the eastern ocean near Weihai in summer and winter. [ABSTRACT FROM AUTHOR]

In offshore fracturing operation, formulating a fracturing fluid with fresh water results in high transportation cost and long time of formulation. If seawater is used to formulate the fracturing fluid, a large amount of chelating agents which crosslink in alkaline environment shall be used, and this results in high material cost, while the ability of the fracturing fluid formulated to resist high temperature may not be satisfactory. To solve this problem, an organic titanium zirconium crosslinking agent is stepwise synthesized with reactants tetra-isopropyl titanate and zirconium sulphate etc. Characterization of the reaction product with NMR and SEM (after precipitation of the crosslinking agent) shows that the crosslinking agent is an organic chelating agent. The particle sizes of the crosslinking agent are distributed in a range of 1 nm to 100 nm, as measured with dynamic and static synchronous laser scattering instrument, and this indicates that the crosslinking agent has excellent reactivity. This crosslinking agent can crosslink in neutral conditions, a good property for formulating fracturing fluids with high salinity waters such as seawater. The microstructure of the crosslinking product is a stable honeycomb-like hexagonal grid structure. With this organic titanium-zirconium crosslinking agent, the fracturing fluids formulated have better viscoelasticity than the fracturing fluids formulated with crosslinking agents containing only titanium. The high temperature resistance of the fracturing fluids formulated using the organic titanium-zirconium crosslinking agent is 180 ℃. Field application of this new crosslinking agent in formulating a fracturing fluid with seawater for fracturing a high temperature well of CNOOC in south China Sea has obtained good results [ABSTRACT FROM AUTHOR]