Conjoined-network induced highly tough hydrogels by using copolymer and nano-cellulose for oilfield water plugging

Jintao Li,Peng Wei,Yahong Xie,Ziteng Liu,Hongjie Chen,Long He 한국공업화학회 2022 Journal of Industrial and Engineering Chemistry Vol.109 No.-

Hydrogels have been widely adopted for in-depth water control in mature oilfields, however, the poormechanical properties limit their application. Herein, a conjoined-network induced hydrogel was preparedthrough the in-situ free radical copolymerization of acrylamide (AM), Acrylic acid (AA) and N,N0-methylenebis(acrylamide) (MBA) in the presence of nano-cellulose (CNF/ACNF), and the coordinationeffect between aluminium ion and carboxyl. The results showed that a small amount of nano-cellulose(0.2 %) increased the compressive strength of the hydrogel by 7 times. The presence of nano-celluloseendowed the hydrogel with excellent thermal stability and high shearing elasticity, at the same time,could effectively reduced the swelling rate that hindered its disintegration in practical application. Theevaluation of sand-pack plugging suggested that the double cross-linked nano-cellulose hydrogel presenteda significant capacity for efficient water plugging, where the breakthrough pressure gradientwas as high as 23.73 MPa, the plugging rate reached 99.9%, and the maximum residual resistance factorwas 3902.06. This work provided a novel design of hydrogel with high compressive strength and satisfactorystability for water shutoff and conformance control in heterogeneous oil reservoirs.

Machining Error Inspection of T-Spline Surface by On- Machine Measurement

Jintao Lai,Jianzhong Fu,Hongyao Shen,Wenfeng Gan,Zichen Chen 한국정밀공학회 2015 International Journal of Precision Engineering and Vol. No.

A new method for machining error inspection of T-spline surface by on-machine measurement (OMM) is investigated in this study. With the presented method, a relatively small number of sampling points are needed to evaluate the machining error of the surface. The sampling strategy based on the dominant of the control vertex is proposed. Based on the inspection data, the machined surfacecan be obtained through a T-spline surface reconstruction algorithm. Verification experiments showed that the inspection errorbetween the OMM method and the coordinate measuring machine (CMM) method is within 13.3%. Simulation results shows that thefitting error in critical area can be improved with less additional sampling points while the surface is presented in T-spline surface.

Sampling for Remote Estimation of an Ornstein-Uhlenbeck Process through Channel with Unknown Delay Statistics

Chen, Yuchao,Tang, Haoyue,Wang, Jintao,Yang, Pengkun,Tassiulas, Leandros 한국통신학회 2023 Journal of communications and networks Vol.25 No.5

In this paper, we consider sampling an Ornstein-Uhlenbeck (OU) process through a channel for remote estimation. The goal is to minimize the mean square error (MSE) at the estimator under a sampling frequency constraint when the channel delay statistics is unknown. Sampling for MSE minimization is reformulated into an optimal stopping problem. By revisiting the threshold structure of the optimal stopping policy when the delay statistics is known, we propose an online sampling algorithm to learn the optimum threshold using stochastic approximation algorithm and the virtual queue method. We prove that with probability 1, the MSE of the proposed online algorithm converges to the minimum MSE that is achieved when the channel delay statistics is known. The cumulative MSE gap of our proposed algorithm compared with the minimum MSE up to the $(k+1)$-th sample grows with rate at most $\mathcal{O}(\ln k)$. Our proposed online algorithm can satisfy the sampling frequency constraint theoretically. Finally, simulation results are provided to demonstrate the performance of the proposed algorithm.

Cavitation Behavior of Oriented PP and Multilayered PP/PE Film During Uniaxial Stretch: In-situ Synchrotron X-ray Study

Zhenxian Chen,Bijin Xiong,Jintao Zhu 한국고분자학회 2022 한국고분자학회 학술대회 연구논문 초록집 Vol.47 No.1

Food search and transport in red imported fire ants (Hymenoptera: Formicidae) under wet conditions

Lin Jintao,Yang Xinya,Lyu Hailong,Chen Xuan,Wang Lei,Wang Cai,Wen Xiujun 한국응용곤충학회 2024 Journal of Asia-Pacific Entomology Vol.27 No.1

The red imported fire ant, Solenopsis invicta Buren, has invaded various wetlands such as beaches, swamps, and mangrove forests. We hypothesize that S. invicta can effectively forage food in these habitats. Here, the food searching and transport by S. invicta on each substrate (sand or soil with freshwater or artificial seawater) at different saturation levels (70%, 100%, 130%, or 160%) were evaluated. Ants walked on unsubmerged substrates (70%- and 100%-saturated) to search for food, and surprisingly, they swam and passed 130%- or 160%-saturated substrates that were submerged with thin layers of water. Saturation level may significantly affect duration of food search and/or transport, depending on substrate types. The number of foraging ants rapidly increased and decreased on the food-releasing platform located on the 70%-saturated substrate and remained stable on the platform located on the 100%-saturated substrate. However, only a few ants were found on the platform located on waterlogged substrates throughout the experiment. In addition, no food was successfully transported passing the waterlogged substrate. We also compared food search and transport among four substrates (sand or soil with freshwater or seawater) at the 70%- or 100%-saturation level. Ants spent similar time searching for food and transporting food on the platform, but minimal food was transported passing the soil with freshwater or seawater. Our results showed that S. invicta can successfully search for food but fail to transport food on waterlogged substrates. In addition, both substrate types and saturation level affected food transport under unsubmerged conditions.

Cuprum Metal-Organic-Framework and Polyacrylonitrile-Derived Cu-N-C Electrocatalyst for Application in Zinc-Air Batteries

Yajun Zhao,Jintao Chen,Xiaorui Li,Jiaqing Zhang,Yanan Li,Yajun Zhao,Liye Cao,Xiaoshi Jin 성균관대학교(자연과학캠퍼스) 성균나노과학기술원 2020 NANO Vol.15 No.02

Cu-N-C electrocatalyst was successfully prepared with Cu-BTC and polyacrylonitrile as templates by electrospinning and in-situ growth method. The effect of various N-doped content on the electrochemical performance of the catalyst were investigated and the Cu-N-C-0.25 exhibited the best OER/ORRcatalytic activities. When it was applied to the cathode of the zinc-air batteries, the power density of Cu-N-C-0.25 was 209.1 mW cm -2, which exceeded that of the commercial Pt/C + IrO2 hybrid catalyst (157 mW cm -2). The excellent electrochemical performance may be attributed to large number of active sites and high specific surface area on Cu-N-C electrocatalyst. It will be a promising alternative to precious metal catalysts containing Pt, Ir or Ru and their oxides.

Experimental investigation on shear capacity of partially prefabricated steel reinforced concrete columns

Yong Yang,Yang Chen,Jintao Zhang,Yicong Xue,Ru-yue Liu,Yunlong Yu 국제구조공학회 2018 Steel and Composite Structures, An International J Vol.28 No.1

This paper experimentally and analytically elucidates the shear behavior and shear bearing capacity of partially prefabricated steel reinforced concrete (PPSRC) columns and hollow partially prefabricated steel reinforced concrete (HPSRC) columns. Seven specimens including five PPSRC column specimens and two HPSRC column specimens were tested under static monotonic loading. In the test, the influences of shear span aspect ratio and difference of cast-in-place concrete strength on the shear behavior of PPSRC and HPSRC columns were investigated. Based on the test results, the failure pattern, the loaddisplacement behavior and the shear capacity were focused and analyzed. The test results demonstrated that all the column specimens failed in shear failure mode with high bearing capacity and good deformability. Smaller shear span aspect ratio and higher strength of inner concrete resulted in higher shear bearing capacity, with more ductile and better deformability. Furthermore, calculation formula for predicting the ultimate shear capacity of the PPSRC and HPSRC columns were proposed on the basis of the experimental results.

Numerical semi-empirical modeling of lidar attenuation characteristics in atmosphere

Tan Zhuangbin,Zhang Yan,Yang Yang,Chen Jintao,Qu Chengzhi,Ma Feifan 한국물리학회 2022 THE JOURNAL OF THE KOREAN PHYSICAL SOCIETY Vol.81 No.12

Long-distance measurement of lidar is a critical problem in various felds, such as airborne lidar detection, surveying, and mapping. Attenuation characteristic is the key factor afecting the lidar detection capability. However, some long-distance measurement methods based on the widely used and validated theoretical models are usually inefcient, while others relying on empirical models have limited applications due to experimental difculties. This study proposes a semi-empirical model of long-distance measurement based on the Beer–Lambert–Bouguer law adopting mathematical methods. Compared to the theoretical model, the calculation efciency of the semi-empirical model we constructed has been improved by more than two orders of magnitude, and the accuracy can reach more than 98% of the theoretical model. Compared to other empirical models, its accuracy is closer to the theoretical model, and the computational efciency is similar. It can be more efectively applied to the actual long-distance detection scene.

Synthesis of g-C3N4/CQDs composite and its photocatalytic degradation property for Rhodamine B

Jin Tao,Liu Chengbao,Chen Feng,Qian Junchao,Qiu Yongbin,Meng Xianrong,Chen Zhigang 한국탄소학회 2022 Carbon Letters Vol.32 No.6

To solve the problem of water pollution, researchers have proposed a photocatalytic degradation technology, in which the key factor is the development of efficient photocatalytic materials. Graphitic carbon nitride (g-C3N4), an n-type semiconductor, has been widely studied due to its suitable band gap (2.7 eV), low cost, easy preparation, non-toxicity, and high photostability. However, the pure-phase g-C3N4 still has defects such as low specific surface area, insufficient visible light absorption, low charge mobility, few active sites for interfacial reaction, and easy recombination of photogenerated electron–hole pairs, which leads to the lower photocatalytic activity of g-C3N4. Aiming at the problems mentioned above, this paper focus on the synthesis of g-C3N4-based composites with high photocatalytic activity via lemon juice induction method. Thiourea and lemon juice were selected as precursors, and carbon quantum dots (CQDs) as electron mediators were introduced anchoring on the surface of g-C3N4 to build g-C3N4/CQDs with compact interface. The results showed that small-sized CQDs are uniformly distributed on the surface of g-C3N4, and the g-C3N4/CQDs composite has a 2D0D structure, which reduces the recombination of photogenerated electron–hole pairs. The photocatalytic degradation efficiency of 4% g-C3N4/CQDs for RhB reaches the highest data of 90.9%, and the photocatalytic degradation rate is 0.016 min−1, which is about 2.3 times that of g-C3N4. After four cycles of photocatalytic reaction, the photocatalytic degradation efficiency of the material remained at 81.7%. Therefore, the g-C3N4/CQDs synthesized via lemon juice induction has a more stable microstructure, and the charge separation efficiency is greatly improved, which is suitable for practical photocatalytic environmental protection.