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Securing offshore resources development: A mathematical investigation into gas leakage in long-distance flexible pipes

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Petroleum Science 2024年第4期21卷 2734-2744页

作者： Xiang-An Lu liang-liang Jiang Jian-Sheng Zhang Min-Gui Wang Guangling College of Yangzhou University Department of Chemical and Petroleum Engineering University of Calgary Department of Energy and Power Engineering Tsinghua University

Gas flexible pipes are critical multi-layered equipment for offshore oil and gas development. Under high pressure conditions, small molecular components of natural gas dissolve into the polymer inner liner of the flexible pipes and further diffuse into the annular space, incurring annular pressure build-up and/or production of acidic environment, which poses serious challenges to the structure and integrity of the flexible pipes. Gas permeation in pipes is a complex phenomenon governed by various factors such as internal pressure and temperature, annular structure, external temperature. In a long-distance gas flexible pipe, moreover, gas permeation exhibits non-uniform features, and the gas permeated into the annular space flows along the metal gap. To assess the complex gas transport behavior in long-distance gas flexible pipes, a mathematical model is established in this paper considering the multiphase flow phenomena inside the flexible pipes, the diffusion of gas in the inner liner, and the gas seepage in the annular space under varying permeable properties of the annulus. In addition, the effect of a variable temperature is accounted. A numerical calculation method is accordingly constructed to solve the coupling mathematical equations. The annular permeability was shown to significantly influence the distribution of annular pressure. As permeability increases, the annular pressure tends to become more uniform, and the annular pressure at the wellhead rises more rapidly. After annular pressure relief followed by shut-in, the pressure increase follows a convex function. By simulating the pressure recovery pattern after pressure relief and comparing it with test results, we deduce that the annular permeability lies between 123 and 512 m D. The results help shed light upon assessing the annular pressure in long distance gas flexible pipes and thus ensure the security of gas transport in the emerging development of offshore resources.

关键词： Offshore resources development Transport security Long-distance flexible pipes Gas leakage Heat and mass transfer model Finite difference calculation

Event-triggered predefined-time control for full-state constrained nonlinear systems: A novel command filtering error compensation method

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Science China(Technological Sciences) 2024年第9期67卷 2867-2880页

作者： PAN YingNan CHEN YiLin liang HongJing College of Control Science and Engineering Bohai UniversityJinzhou 121013China School of Automation Engineering University of Electronic Science and Technology of ChinaChengdu 611731China Laboratory of Electromagnetic Space Cognition and Intelligent Control Beijing 100089China

In this paper, a command filter-based adaptive fuzzy predefined-time event-triggered tracking control problem is investigated for uncertain nonlinear systems with time-varying full-state constraints. By designing a sliding mode differentiator, the inherent computational complexity problem within the predefined-time backstepping framework is solved. Different from the existing command filter-based finite-time and fixed-time control strategies that the convergence time of the filtering error is adjusted through the system initial value or numerous parameters, a novel command filtering error compensation method is presented,which tunes one control parameter to make the filtering error converge in the predefined time, thereby reducing the complexity of design and analysis of processing the filtering error. Then, an improved event-triggered mechanism(ETM) that builds upon the switching threshold strategy, in which an inverse cotangent function is designed to replace the residual term of the ETM,is proposed to gradually release the controller's dependence on the residual term with increasing time. Furthermore, a tan-type nonlinear mapping technique is applied to tackle the time-varying full-state constraints problem. By the predefined-time stability theory, all signals in the uncertain nonlinear systems exhibit predefined-time stability. Finally, the feasibility of the proposed algorithm is substantiated through two simulation results.

关键词： predefined-time control command filtering error compensation method event-triggered mechanism time-varying full-state constraints uncertain nonlinear systems

The higher-order topological pumping explored in the 2D acoustic crystal

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Science China(Physics,Mechanics & Astronomy) 2024年第2期67卷 127-133页

作者： Yanqiu Wang Bin liang Jianchun Cheng Key Laboratory of Modern Acoustics Ministry of EducationInstitute of AcousticsDepartment of PhysicsNanjing UniversityNanjing 210093China Collaborative Innovation Center of Advanced Microstructures Nanjing UniversityNanjing 210093China

The topological pumping has been instrumental in advancing our understanding of topological phase transitions in various physical systems,which can be extended to uncover intriguing higher-order topological phases in the lower-dimensional ***,we propose a theoretical exploration of topological dipole pumping on an acoustic square superlattice by cyclically modulating intracell couplings,which shares the topological nature of an extended three-dimensional system with chiral hinge *** the multipole chiral numbers,we characterize the higher-order topological phases that arise during the *** evolution of topological phase transitions is verified by numerical simulations and shows corner states are transferred across the *** findings can inspire the construction of chiral hinge states in artificial crystals,opening up new possibilities for the design of devices allowing the unidirectional propagation of sound.

关键词： topological phases of matter Thouless pumping acoustic metamaterial

Polyelectrolyte Complexes and Coacervates Formed by De novo-Designed Peptides and Oligonucleotide

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Chinese Journal of Polymer Science 2024年第9期42卷 1333-1340,I0007页

作者： Tian-Hao Ren De-Hai liang Beijing National Laboratory for Molecular Sciences Department of Polymer Science and Engineering and the Key Laboratory of Polymer Chemistry and Physics of the Ministry of EducationCollege of Chemistry and Molecular EngineeringPeking UniversityBeijing100871China

The liquid-liquid phase separation of biopolymers in living cells contains multiple interactions and occurs in a dynamic *** the regulation mechanism is still a *** this work,we designed a series of peptides(XXLY)_(6)SSSGSS and studied their complexation and coacervation behavior with single-stranded ***“X”and“Y”are varied to combine known amounts of charged and non-charged amino acids,together with the introduction of secondary structures and pH *** show that the electrostatic interaction,which is described as charge density,controls both the strength of complexation and the degree of chain relaxation,and thus determines the growth and size of the *** hydrophobic interaction is prominent when the charges are ***,the secondary structures of peptides exhibit profound effect on the morphology of the phases,such as solid phase to liquid phase *** study gains insight into the phase separation under physiological *** is also helpful to create coacervates with desirable structures and functions.

关键词： Polyelectrolyte complex Coacervate Peptides Secondary structure Electrostatic interaction

A Fully-Integrated Memristor Chip for Edge Learning

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Nano-Micro Letters 2024年第9期16卷 123-127页

作者： Yanhong Zhang liang Chu Wenjun Li School of Electronics and Information Hangzhou Dianzi UniversityHangzhou 310018People’s Republic of China

It is still challenging to fully integrate computing in memory chip as edge learning *** recent work published on Science,a fully-integrated chip based on neuromorphic memristors was developed for edge learning as artificial neural networks with functionality of synapses,dendrites,and somas.A crossbar-array memristor chip facilitated edge learning including hardware realization,learning algorithm,and cycle-parallel sign-and threshold-based learning(STELLAR)*** motion control and demonstration platforms were executed to improve the edge learning ability for adapting to new scenarios.

关键词： Computing in memory Edge learning Fully-integrated chip

基于用户意图理解的社交网络跨媒体搜索与挖掘

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智能系统学报 2017年第6期12卷 761-769页

作者：崔婉秋杜军平周南梁美玉北京邮电大学智能通信软件与多媒体北京市重点实验室北京100876

随着在线社交网络的盛行,网络用户不仅对信息资讯的获取速度和实时性提出了更高的要求,对个性化和精确化的搜索需求日益增长。为了提升搜索引擎的质量以及其结果列表的准确性,需要深层次地挖掘用户搜索意图。本文分析了用户搜索意图理... 详细信息

随着在线社交网络的盛行,网络用户不仅对信息资讯的获取速度和实时性提出了更高的要求,对个性化和精确化的搜索需求日益增长。为了提升搜索引擎的质量以及其结果列表的准确性,需要深层次地挖掘用户搜索意图。本文分析了用户搜索意图理解在线社交网络跨媒体进行精准搜索与挖掘的研究现状,包括知识图谱在线社交网络多模态信息感知、面向用户搜索意图匹配的跨媒体大数据深度语义学习方面的应用,以及用户搜索意图理解的在线社交网络精准搜索与挖掘的应用等。最后,对未来研究存在的问题和可能面临的挑战进行了展望。

关键词：在线社交网络用户搜索意图知识图谱深度语义学习精准搜索关键词

Divalent anion intercalation and etching-hydrolysis strategies to construct ultra-stable electrodes for seawater splitting

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Science China Chemistry 2024年第2期67卷 687-695页

作者： Jiajia Lu Yang Liu Han-Pu liang Key Laboratory of Biofuels Qingdao Institute of Bioenergy and Bioprocess TechnologyChinese Academy of SciencesQingdao266101China Henan Provincial Key Laboratory of Nanocomposites and Applications Institute of Nano-Structured Functional MaterialsHuanghe Science and Technology CollegeZhengzhou450006China School of Materials Science and Engineering Henan Normal UniversityXinxiang453007China Center of Materials Science and Optoelectronics Engineering University of Chinese Academy of SciencesBeijing100049China Shandong Energy Institute Qingdao266101China

Developing stable electrodes for seawater splitting remains a great challenge due to the detachment of catalysts at a large operating current and severe anode corrosion caused by ***,divalent anion intercalation and etching-hydrolysis strategies are deployed to synthesize the ultra-stable anode,dendritic Fe(OH)_(3) grown on Ni(SO_4)_(0.3)(OH)_(1.4)–Ni(OH)_(2).Experimental results reveal that the anode exhibits good activity and excellent stability in alkaline simulated *** 500 h,the current density operated at 1.72 V remains 99.5%,about 210 m A cm^(-2).The outstanding stability originates from the etchinghydrolysis strategy,which strengthens the interaction between the catalyst and the carrier and retards thus the detachment of catalysts at a large current ***,theoretical simulations confirm that the intercalated divalent anions,such as SO_4^(2-) and CO_(3)^(2-),can weaken the adsorption strength of chlorine on the surface of catalysts and hinder the coupling and hybridization between chlorine and nickel,which slows down the anode corrosion and improves catalytic ***,the twoelectrode system shows the remarkable 95.1% energy efficiency at 2,000 A m-2and outstanding stability in 6 mol L^(-1) KOH +seawater at 80 ℃.

关键词： seawater splitting stability divalent anion intercalation etching-hydrolysis

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基于卷积神经网络的微博话题内容搜索方法

计算机科学与探索 2019年第5期13卷 753-764页

作者：周南杜军平姚旭梁美玉薛哲 LEE JangMyung 北京邮电大学智能通信软件与多媒体北京市重点实验室计算机学院北京100876 釜山国立大学电子工程系韩国釜山46241

针对由于微博文本的数据特性造成的传统信息搜索方法无法直接实现微博话题内容搜索的问题,提出了一种基于卷积神经网络的微博话题内容搜索方法,对微博安全话题内容进行搜索和匹配排序。该方法包括基于深度卷积神经网络的微博内容筛选和... 详细信息

针对由于微博文本的数据特性造成的传统信息搜索方法无法直接实现微博话题内容搜索的问题,提出了一种基于卷积神经网络的微博话题内容搜索方法,对微博安全话题内容进行搜索和匹配排序。该方法包括基于深度卷积神经网络的微博内容筛选和微博内容匹配两部分。微博内容筛选依据深度卷积特征表示进行微博内容筛选,微博内容匹配通过卷积特征非线性变换对筛选结果进行匹配排序。微博内容筛选和微博内容匹配对国民安全话题相关的微博文本内容局部特征进行处理,对筛选结果进行相似度计算从而实现相似度匹配。实验结果表明该方法在微博搜索性能上优于现有同类方法,并验证了所提出方法针对安全话题的微博文本内容搜索的有效性。

关键词：微博搜索深度卷积神经网络深度学习搜索排序信息搜索

Oscillatory Dynamics of Heterogeneous Stem Cell Regeneration

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Communications on Applied Mathematics and Computation 2024年第1期6卷 431-453页

作者： Xiyin liang Jinzhi Lei School of Mathematical Sciences Center for Applied MathematicsTiangong UniversityTianjin300387China

Stem cell regeneration is an essential biological process in the maintenance of tissue homeostasis;dysregulation of stem cell regeneration may result in dynamic diseases that show oscillations in cell *** heterogeneity and plasticity are necessary for the dynamic equilibrium of tissue homeostasis;however,how these features may affect the oscillatory dynamics of the stem cell regeneration process remains poorly ***,based on a mathematical model of heterogeneous stem cell regeneration that includes cell heterogeneity and random transition of epigenetic states,we study the conditions to have oscillation solutions through bifurcation analysis and numerical *** results show various model system dynamics with changes in different parameters associated with kinetic rates,cellular heterogeneity,and *** show that introducing heterogeneity and plasticity to cells can result in oscillation dynamics,as we have seen in the homogeneous stem cell regeneration ***,increasing the cell heterogeneity and plasticity intends to maintain tissue homeostasis under certain *** current study is an initiatory investigation of how cell heterogeneity and plasticity may affect stem cell regeneration dynamics,and many questions remain to be further studied both biologically and mathematically.

关键词： Stem cell regeneration Heterogenous Hopf bifurcation Hematopoietic dynamical disease