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The conventional technique for positioning seafloor geophones in ocean bottom seismic exploration encounters several challenges, including the significant impact of outliers on positioning results, underutilization of high-precision observations, and low efficiency in real-time data processing. These issues inevitably affect the quality of seismic exploration outcomes. To address these challenges and enhance the accuracy of geophone positioning, this paper proposes a rigorous real-time acoustic positioning method for geophones based on sequential adjustment and Baarda's outlier detection approach. The proposed method comprises three key steps: grouping the original acoustic observations, constructing the intra-group acoustic positioning model, and synthesizing the positioning results across the different groups. The validity and practicality of this approach are confirmed through a simulation experiment as well as the field experiment conducted in the Bohai Sea, China. The results demonstrate that the proposed method effectively eliminates outliers in the original observations and maximizes the utilization of high-quality observations. Compared to traditional acoustic positioning methods, it significantly reduces positioning errors from meters to decimeters, and in some cases can achieve centimeter-level precision. When the sound velocity profile in the operating sea area is measured, the method can attain the posterior standard deviation at the millimeter level and positioning errors within 10 cm. When the sound velocity profile is unknown, the method can achieve the posterior standard deviation at centimeter-level and positioning errors of approximately 20 cm. [ABSTRACT FROM AUTHOR]

When exposed to corrosive environments, metals, which are relatively common industrial materials, undergo serious corrosion, leading to significant economic losses. Therefore, studying the corrosion rate of metals in their early stages holds great pedagogical significance. This study employs a standard specimen of 20# steel as an experimental object, designing the experimental teaching of metal corrosion rate under varying temperatures, PH levels, and hydrated salt materials. The weightlessness method determines the overall corrosion rate of the metal, while the electrochemical method determines the localized corrosion rate of the metal. When the experimental temperature is 80℃ and 100℃, the corrosion rate of 20# steel is the largest; both are 0.00800g·m−2·d−1, and the charge transfer resistance increases gradually when the temperature is −20℃~5℃, and decreases gradually when the temperature is 5℃~100℃. The corrosion rate of the metal did not change much at pH=7 and 8, and the corrosion rate reached 0.688 mm/a, and the impedance curve polarization resistance Rp was the smallest when pH=5, and its corrosion resistance was poor under acidic conditions. The average corrosion rates in MgSO4·7H2O, and CaCl2·6H2O and Ba(OH)2·8H2O were 0.0030g/m−2h−1, 0.0018g/m−2h−1, and 0.0050 g/m−2h−1, respectively. Teaching experiments were used to carry out the present study. The study aims to let students experience the process of metal corrosion through teaching experiments and better help them solve cognitive difficulties in metal corrosion.

Currently, the pollution and clogging problems of injection wells in low-permeability reservoirs are becoming more and more serious, leading to a series of issues, such as the decline of fluid production in wells and the increase of pressure in injection wells. To cope with these challenges, SY organic polyacid solution was developed in this paper and its dissolution efficiency was thoroughly investigated. The experimental results show that SY organic polyacid solution has a high dissolution rate of 88.7%, which exhibits excellent scale dissolution effect, and the solvent's dissolution has a good slow-release performance to ensure the long-lasting action time. At the same time, the corrosion rate of the solvent on the N80 steel sheet is only 0.6291 g/m²-h, much lower than the industry standard, which effectively protects the safety of the construction pipeline and production column. In addition, the dissolution rate of SY organic polyacid on clay reaches 10.14% in five minutes, indicating that it prevents the ground collapse caused by excessive dissolution of clay and has good profound penetration ability. In summary, using SY organic polyacid solution can effectively solve multiple problems such as reservoir mud, inorganic scale, organic scale and water injection fouling oil, which provides an effective solution for the contamination and clogging of water injection wells in low permeability reservoirs.