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1

Sulfonation modification of guar gum and its performance as a fracturing fluids thickener

Yi Yonggen, Wu Lanbing, Zhang Jie, Wang Haiyang, Xie Xuan, Gang Chen

Polish Journal of Chemical Technology

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2024

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Vol. 26, nr 3

29--38

EN

To solve the contradiction between reducing water-insoluble content and maintaining high viscosity in the preparation of modified guar gum for oilfi eld fracturing fluid, in this work, sodium 3-chloro-2-hydroxypropylsulfonate was used as a modifier to prepare sulfonated guar gum. Orthogonal and single-factor extrapolation experiments were conducted to explore the effects of reaction conditions and the optimal process was determined as follows: reaction temperature of 26° C, reaction time of 2.0 h, sodium hydroxide as a mass fraction of guar gum of 1.0%, and sodium 3-chloro-2-hydroxypropyl sulfonate dosage as a mass fraction of guar gum of 0.5%. Furtherly, the temperature stability, filtration property, and inhibition of formation clay of the sulfonated products were investigated. The results showed that the apparent viscosity of 0.6% solution of guar gum was increased by 33%, the water-insoluble content was decreased by 0.42%, and the temperature stability, filtration resistance, and clay inhibition were all improved. Especially, the viscosity of cross-linked sulfonated guar gum is 100% higher than that of unmodified guar gum. The structure of sulfonated guar gum was characterized and confi rmed by infrared spectrum, DSC, thermogravimetric, and elemental analysis.

2

Low-Frequency Sound Absorption Potential of Subwavelength Absorbers Based on Coupled Micro-Slit Panels

Qian Yujie, Gao Zhengyuan, Zhang Jie

Archives of Acoustics

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2024

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Vol. 49, nr 1

121--128

EN

Due to space limitations during installation, reducing low-frequency noise has always been a challenging area. Sub-wavelength structures are typically favored in such scenarios for noise reduction. This paper explores the potential of micro-slit panels (MSP) for low-frequency sound absorption. To further optimize the panel thickness, coupled MSPs (CMSP) with a distance between two MSPs of less than 1 mm are proposed. Firstly, the low-frequency absorption performances of a single MSP based on two optimized schemes – the cavity-depth optimal scheme (COS) and the panel thickness optimal scheme (TOS) – are examined and compared with those of existing ultrathin metamaterials. The results demonstrate that MSP has significant potential for low frequency sound absorption, and COS allows for a smaller overall structural thickness but a larger panel thickness than TOS. Secondly, to reduce the panel thickness, the CMSP is developed and the theoretical model of its acoustic impedance is established and validated by experiments. Then, based on the theoretical model, the low-frequency absorption potential of CMSP is optimized using COS. The results show that both the overall thickness and the panel thickness of the CMSP absorber are reduced while maintaining better performance. Furthermore, the proposed absorber achieves a subwavelength scale since its total thickness can be as small as 0.138λ.

3

Study on REE occurrence in a Svanbergite and basic ore characteristics

Ma Keyu, Zhang Jie, Deng Qiufeng, Men Pengpeng, Zhang Yusong, Shi Xiulin

Physicochemical Problems of Mineral Processing

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2022

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Vol. 58, iss. 3

art. no. 147377

EN

Svanbergite in Sichuan Province, China is a special middle-low grade phosphorus ore. It contains rare earth elements (REEs), aluminum, and strontium that can be exploited and utilized. In this study, several methods were used to systematically study the occurrence of REEs in the ore and basic ore characteristics. The ore, which was rich in REEs, Al, and Sr, was classified as marine sedimentary low-grade phosphorus ore. The main ore mineral was crandallite and pyrite, and independent REE minerals were not found. Crandallite was the main carrier mineral of useful elements, including P, REEs, Al, and Sr. REE+ was inferred to mainly exist in crandallite via isomorphism by replacing Ca2+ and H+. The crandallite was mainly characterized as fine-grained, and minerals were closely disseminated. The results from this study will provide a valuable reference for expanding available REE resources and the efficient comprehensive utilization of svanbergite.

4

Estimation of lateral correlation length from deep seismic refection profle based on stochastic model

Yong Fan, Lu Qingtian, Feng Jie, Zhang Jie, Luo Shuiyu

Acta Geophysica

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2021

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Vol. 69, no. 4

1297--1312

EN

The fractal nature of crustal seismic velocity heterogeneity makes the interpretation of deep seismic refection data difcult by conventional methods developed in oil and gas exploration. Thus, several statistical approaches have been introduced as promising tools for interpreting the complex refection patterns of deep seismic data. Because stochastic models have been successfully used to describe the heterogeneity of crustal rocks, stochastic parameter estimation has become a potentially powerful tool for recovering information on geometric geological variations. However, there are many factors that infuence parameter estimation, with limited data being a profound one. We present a novel algorithm to estimate the lateral correlation length, an important stochastic parameter, from deep seismic refection data. First, an autoregressive power spectrum-based method was introduced to calculate the autocorrelation function from limited data. Second, the average multi-trace 1D autocorrelation function was used to replace the 2D autocorrelation function to improve the computation efciency, accuracy, and stability. Compared with other algorithms, a velocity model test showed that our method exhibited signifcantly better performance for a small dataset. Then, an appropriately sized sliding window of synthetic seismic data was applied to map the relative variations of lateral stochastic parameters. The results indicated that our method could distinguish the lateral variations in stochastic parameters as well as vertical changes. Finally, the geological meaning of diferent seismic refection patterns was discussed after applying our methods to deep seismic refection feld data. The results demonstrated that lateral correlation can clearly identify Moho discontinuity, crustal refections, and some sedimentary structures.

5

Feasibility study of RANS in predicting propeller cavitation in behind-hull conditions

Zhang Yuxin, Wu Xiao-ping, Lai Ming-yan, Zhou Guo-ping, Zhang Jie

Polish Maritime Research

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2020

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nr 4

26--35

EN

The propeller cavitation not only affects the propulsive efficiency of a ship but also can cause vibration and noise. Accurate predictions of propeller cavitation are crucial at the design stage. This paper investigates the feasibility of the Reynolds-averaged Navier–Stokes (RANS) method in predicting propeller cavitation in behind-hull conditions, focusing on four aspects: (i) grid sensitivity; (ii) the time step effect; (iii) the turbulence model effect; and (iv) ability to rank two slightly different propellers. The Schnerr-Sauer model is adopted as the cavitation model. A model test is conducted to validate the numerical results. Good agreement on the cavitation pattern is obtained between the model test and computational fluid dynamics. Two propellers are computed, which have similar geometry but slightly different pitch ratios. The results show that RANS is capable of correctly differentiating the cavitation patterns between the two propellers in terms of the occurrence of face cavitation and the extent of sheet cavitation; moreover, time step size is found to slightly affect sheet cavitation and has a significant impact on the survival of the tip vortex cavitation. It is also observed that grid refinement is crucial for capturing tip vortex cavitation and the two-equation turbulence models used – realizable k-ε and shear stress transport (SST) k-ω – yield similar cavitation results.

6

The demand analysis of oceanic T-S-V 3D reconstruction on wide-swath SSH data features based on ROMS and 4DVAR

Zhou Chaojie, Zhang Jie, Yang Jungang, Cao Lei

Oceanologia

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2020

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No. 62 (3)

309--325

EN

Future wide-swath altimetry missions will provide high-resolution information about ocean surface elevation, and facilitate the characterization of meso- and sub-mesoscale ocean activities. In this study, the demand analysis of three-dimensional (3D) oceanic state reconstruction on wide-swath SSH data features was evaluated using a data assimilation strategy. Three groups of experiments were performed to determine if the wide-swath altimetry observations would improve the three-dimensional (3D) field estimates of ocean temperature-salinity-velocity (T-S-V), and to evaluate how the spatial and temporal resolution and accuracy of the wide-swath altimetry observations affected the ocean state estimation. The Regional Ocean Modeling System and the four-dimensional variational data assimilation method were used in the experiments, with numerical simulation for the Taiwan region at a resolution of 1/10° as the example. The sensitivity of the 3D ocean state construction to the wide-swath altimetry measurements was also investigated. The results showed that the wide-swath sea surface height (SSH) measurements would have an overall positive impact on the 3D T-S-V field and that the positive effect would increase as the resolution and accuracy of the observations increased, but the net benefits would gradually decrease. Among the three examined features of the wide-swath altimetry observations, the temporal resolution had the most influence on the 3D ocean state analysis.