Modeling of offshore pile driving noise using a semi-analytical variational formulation

Underwater noise radiated from offshore pile driving got much attention in recent years due to its threat to the marine environment. This study develops a three-dimensional semi-analytical method, in which the pile is modeled as an elastic thin cylindrical shell, to predict vibration and underwater acoustic radiation caused by hammer impact. The cylindrical shell, subject to the Reissner–Naghdi’s thin shell theory, is decomposed uniformly into shell segments whose motion is governed by a variational equation. The sound pressures in both exterior and interior fluid fields are expanded as analytical functions in frequency domain. The soil is modeled as uncoupled springs and dashpots distributed in three directions. The sound propagation characteristics are investigated based on the dispersion curves. The case study of a model subject to a non-axisymmetric force demonstrates that the radiated sound pressure has dependence on circumferential angle. The case study including an anvil shows that the presence of the anvil tends to lower the frequencies and the amplitudes of the peaks of sound pressure spectrum. A comparison to the measured data shows that the model is capable of predicting the pile driving noise quantitatively. This mechanical model can be used to predict underwater noise of piling and explore potential noise reduction measures to protect marine animal

Optimization of extraction and antioxidant activities of polyphenols from honey peachkernel by ultrasonic-assisted enzymolysis approach

Objective: This study aimed to explore the potential use of honey peach kernel as a by-product of characteristic agricultural product processing. Methods: The processing technology was optimized based on a single factor test and response surface test by analyzing the effects of enzyme addition amount, ultrasonic temperature, ethanol concentration, and ultrasonic time on the extraction amount of peach kernel polyphenols. Additionally, the antioxidant activities of the extracted polyphenols were studied. Results: The results showed that the optimal extraction parameters were as follows: enzyme adding quantity 5%, ultrasonic temperature 63 ℃, ethanol concentration 60%, and ultrasonic time 37 min. Under this condition, the extraction amount of polyphenols was 8.63 mg/g. The antioxidant results showed that the scavenging rates of ABTS free radical, DPPH free radical, OH free radical, and O-2 free radical were 75.22%, 85.91%, 44.72%, and 45.76%, respectively. The IC50 of the four free radicals were 0.099, 0.098, 0.332, and 0.320 mg/mL, respectively. Conclusion: The approach of ultrasonic-assisted enzymolysis can effectively extract the polyphenols in the honey peach kernel, the polyphenols of the honey peach kernel had good antioxidant activity

Contribution of Atmospheric Oxygenated Organic Compounds to Particle Growth in an Urban Environment

Gas-phase oxygenated organic molecules (OOMs) can contribute substantially to the growth of newly formed particles. However, the characteristics of OOMs and their contributions to particle growth rate are not well understood in urban areas, which have complex anthropogenic emissions and atmospheric conditions. We performed long-term measurement of gas-phase OOMs in urban Beijing during 2018-2019 using nitrate-based chemical ionization mass spectrometry. OOM concentrations showed clear seasonal variations, with the highest in the summer and the lowest in the winter. Correspondingly, calculated particle growth rates due to OOM condensation were highest in summer, followed by spring, autumn, and winter. One prominent feature of OOMs in this urban environment was a high fraction (similar to 75%) of nitrogen-containing OOMs. These nitrogen-containing OOMs contributed only 50-60% of the total growth rate led by OOM condensation, owing to their slightly higher volatility than non-nitrate OOMs. By comparing the calculated condensation growth rates and the observed particle growth rates, we showed that sulfuric acid and its clusters are the main contributors to the growth of sub-3 nm particles, with OOMs significantly promoting the growth of 3-25 nm particles. In wintertime Beijing, however, there are missing contributors to the growth of particles above 3 nm, which remain to be further investigated.Peer reviewe

Molecular Composition of Oxygenated Organic Molecules and Their Contributions to Organic Aerosol in Beijing

The understanding at a molecular level of ambient secondary organic aerosol (SOA) formation is hampered by poorly constrained formation mechanisms and insufficient analytical methods. Especially in developing countries, SOA related haze is a great concern due to its significant effects on climate and human health. We present simultaneous measurements of gas-phase volatile organic compounds (VOCs), oxygenated organic molecules (OOMs), and particle-phase SOA in Beijing. We show that condensation of the measured OOMs explains 26-39% of the organic aerosol mass growth, with the contribution of OOMs to SOA enhanced during severe haze episodes. Our novel results provide a quantitative molecular connection from anthropogenic emissions to condensable organic oxidation product vapors, their concentration in particle-phase SOA, and ultimately to haze formation.Peer reviewe

Sedimentary Evolution Laws and Main Controlling Factors of the Nenjiang Formation in the Songnan Da’anbei Area, China

Shallow-water deltas serve as a critical area for the exploration and development of terrestrial lacustrine oil and gas reservoirs. Current research on oil and gas exploration and development in China’s terrestrial lacustrine basins primarily focuses on their delta front facies zones. Despite extensive discussions on the sedimentary characteristics of shallow-water deltas by predecessors, there is a lack of comprehensive analysis on the combined effects of dynamic factors such as climate change, lake level fluctuations, and sediment supply. This paper, through a detailed examination of 12 core samples and integrating data from 493 exploratory, appraisal, and development wells in the study area, establishes a stratigraphic correlation framework using well–seismic integration techniques. It identifies two main sedimentary facies types in the southern Da’anbei area of the Songliao Basin: shallow-water deltas and lake facies, which can be further subdivided into four sub-facies and nine microfacies. Two depositional models for the shallow-water deltas of the Southern Songliao Nenjiang Formation are established: a deeper water background with channel-river mouth bar sequences forming the delta front framework and a shallower water background with channel-sheet sand sequences forming the delta front framework. This paper also discusses the controlling effects of paleoclimate, sediment supply, and lake level changes on sedimentary evolution, providing a scientific basis for the exploration of lithologic oil and gas reservoirs in the Nenjiang Formation of the study area and the deployment of horizontal wells

Characteristics and formation period of fractures in the reservoirs of Permian Maokou Formation, Zigong area, Southwest Sichuan Basin

Objective Fractures commonly occur in the marine carbonate reservoirs of Permian Maokou Formation in Zigong area of Sichuan Basin and have important impacts on reservoir properties, seepage patterns and hydrocarbon enrichment. Methods Cores, thin sections, image logs and experimental test data were used to clarify the type of fracture genesis and development characteristics, analyse the time of fracture formation, and determine the period of fracture formation. Results The results show that the marine carbonate reservoirs of Maokou Formation in Zigong area are divided into two types, namely, tectonic fractures and diagenetic fractures, among which the tectonic fractures include tectonic shear fractures and tectonic tensile fractures, and the diagenetic fractures include horizontal bedding fractures and diagenetic sutures. Tectonic shear fractures dominate Maokou Formation reservoir and occur mainly in the NEE and NNE directions. The fracture inclination angle ranges from 20° to 80°, and the extension length is less than 60 cm. The fracture degree of filling is low, and the validity is good. Combined with the analysis and test data, the reservoir fractures of Maokou Formation in Zigong area were determined to have formed by 3 stages of structural movement. The first stage included the late Hercynian and early Indosinian periods, approximately 240-220 Ma. Under the SW stress derived from the clockwise movement of the South China Plate, a small number of shear fractures developed, and the fractures were mostly filled with minerals, representing the secondary development period of fractures. The second stage occurred in the late Yanshan-early Himalayan period, approximately 78-69 Ma, and a large number of tectonic fractures developed under the NW-trending stress generated by the Xuefeng uplift in Jiangnan, which was the main period of fracture formation in the study area. The third period was the late Himalayan period, approximately 13-0 Ma. Fractures were formed under the NEE compressive stress generated by the collision of Indian Ocean Plate, and most of the fractures were unfilled, indicating good effectiveness. Conclusion The above fracture-related research provides the basis for establishing favourable exploration zones in the study area

Comparative study on the inhibiting mechanism of inhibitor with primary amine groups and quaternary ammonium groups for sodium bentonite

Shale hydration and swelling is the main obstacle to the development of shale gas utilizing water-based drilling fluids (WBDFs). In this work, the inhibition mechanism of alkylammonium inhibitor and alkylamine inhibitor adsorbed on sodium bentonite (Na+Bent) are investigated using infrared spectroscopy (FT-IR), scanning electron microscopy (SEM), X-ray diffraction (XRD), zeta potential, particle size distribution tests, and thermogravimetry analysis (TGA). The results suggest that HTB and HMD can be inserted into the interlamination of Na+Bent and minimize the basal spacing compared to hydrated Na+Bent. HTB and HMD are inserted between the Na+Bent layers in a single-layer tiled manner and replace the sodium ions that are firmly fixed between the layers. Eventually, water molecules are removed from the interlayer Na+Bent. The interaction between the quaternary ammonium group and Na+Bent is more significant than between the primary amine group and Na+Bent. The inhibition performance suggests that HTB inhibits Na+Bent hydration and swelling more substantially than other inhibitors, indicating that the inhibition performance of the two quaternary ammonium groups is greater than that of the two primary amine groups. Therefore, HTB can be used as intercalation inhibition in WBDFs and has tremendous application value