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The Zhujiang Formation in the Baiyun Sag, Pearl River Mouth Basin, China, is formed primarily in a deep-water continental slope environment. Its chronostratigraphic framework is based on biostratigraphy and sequence stratigraphy, and its geological dating is based on micropaleontological data. This makes it difficult to obtain precise absolute ages for various geological events. In this study, gamma ray (GR) well log data from Wells Y1, Y2, and Y3 were used as paleoclimate proxies, and spectral and wavelet analyses were used to conduct cyclostratigraphic research. The results show that the Milankovitch cycles were preserved in the Zhujiang Formation in the Baiyun Sag. Stratigraphic cycles controlled by 405 and 95 ka orbital eccentricity, 40.4 ka orbital obliquity, and 23.5 ka orbital precession cycles can be identified; the signal of stratigraphic cycles controlled by the 405 ka long eccentricity cycle is the strongest. The floating astronomical time scale is constructed based on 405 ka orbital eccentricity cycle tuning of the GR series. The precise durations of the Zhujiang Formation in Wells Y1, Y2, and Y3 are 7.13, 6.93, and 7.18 Ma, and the average deposition rates are 4.68, 5.91, and 5.33 cm/ka, respectively. The Zhujiang Formation was divided into 17 fourth-, 76 fifth-, and 174 sixth-order cycles using the 405, 95, and 40.4 ka orbital periods as the dividing scales, respectively. This study provides a quantitative method for high-precision isochronous stratigraphic division and correlation in deep-water sedimentary systems.

The application of oil-bearing joint that is widely used in various mechanical equipment can effectively improve the dynamic characteristics of integrated machineries. A fractal contact model of oil-bearing joint considering the effect of asperity interaction is proposed in this article. The equivalent stiffness and damping of oil-bearing joint are divided into a solid contact portion and a liquid contact portion. On the basis of elastic mechanics and fractal theory, the deformation of a single asperity of solid contact part is deduced. The stiffness and damping model considering the asperity interaction are obtained from the relationship between normal load and deformation. The stiffness and damping expression of the liquid contact part are also deduced based on the generalized Reynolds equation. It is concluded that the equivalent stiffness increases with the increase of the fractal dimension and the decrease of the fractal roughness parameter. At the same time, increasing the hydrodynamic viscosity can demonstrably improve the contact stiffness. Experiment shows that the proposed model is more in line with the actual load-stiffness relationship. The model considers the factor of asperity interaction and provides a theoretical basis for predicting the dynamic characteristics of oil-bearing joint. An accurate theoretical model of the dynamic characteristics for the oil-bearing joint surface was established. Identification of the dynamic properties of the oil-bearing joint surface using frequency response functions. The factors influencing the stiffness of solid portion and liquid portion were studied, respectively. [ABSTRACT FROM AUTHOR]