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Experimental investigation on using CO_(2)/H_(2)O emulsion with high water cut in enhanced oil recovery

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Petroleum science 2024年第2期21卷 974-986页

作者： xi-Dao Wu Peng xiao Bei Liu Guang-Jin Chen Jian-Hua Pang State Key Laboratory of Heavy Oil Processing China University of PetroleumBeijing102249China Ocean Intelligence Technology Center Shenzhen Institute of Guangdong Ocean UniversityShenzhen518120GuangdongChina

CO_(2) emulsions used for EOR have received a lot of interest because of its good performance on CO_(2)mobility ***,most of them have been focusing on the high quality CO_(2) emulsion(high CO_(2) fraction),while CO_(2) emulsion with high water cut has been rarely *** this paper,we carried out a comprehensive experimental study of using high water cut CO_(2)/H_(2)O emulsion for enhancing oil ***,a nonionic surfactant,alkyl glycosides(APG),was selected to stabilize CO_(2)/H_(2)O emulsion,and the corresponding morphology and stability were evaluated with a transparent PVT ***,plugging capacity and apparent viscosity of CO_(2)/H_(2)O emulsion were measured systematically by a sand pack displacement apparatus connected with a 1.95-m long capillary ***,a high water cut(40 vol%) CO_(2)/H_(2)O emulsion was selected for flooding experiments in a long sand pack and a core sample,and the oil recovery,the rate of oil recovery,and the pressure gradients were *** results indicated that APG had a good performance on emulsifying and stabilizing CO_(2) *** inversion from H_(2)O/CO_(2) emulsion to CO_(2)/H_(2)O emulsion with the increase in water cut was ***_(2)/H_(2)O emulsions with lower water cuts presented higher apparent viscosity,while the optimal plugging capacity of CO_(2)/H_(2)O emulsion occurred at a certain water ***,the displacement using CO_(2)/H_(2)O emulsion provided 18.98% and 13.36% additional oil recovery than that using pure CO_(2) in long sand pack and core tests,*** work may provide guidelines for EOR using CO_(2) emulsions with high water cut.

关键词： CO_(2)/H_(2)O emulsion High water cut CO_(2) mobility control Enhanced oil recovery

Topological superconductors with spin-triplet pairings and Majorana Fermi arcs

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Chinese Physics B 2024年第8期33卷 453-458页

作者：黄石罗熙 College of science University of Shanghai for Science and TechnologyShanghai 200093China

We construct a three-dimensional topological superconductor Bogoliubov–de Gennes(BdG)Hamiltonian with the normal state being a three-dimensional topological *** introducing inter-orbital spin-triplet pairings term△3,there are topological Majorana nodes in the bulk and they are connected by Majorana Fermi arcs on the surface,similar to the case of Weyl ***,by adding an inversion-breaking term to the normal state,momentum-independent pairing terms with different parities can coexist in the Bd G Hamiltonian,which creates more Majorana modes similar to Andreev bound states and a richer phase diagram.

关键词： topological surface states topological superconductors topological nodes Weyl points Majorana Fermi arcs

A unified Minorization-Maximization approach for estimation of general mixture models

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Applied Mathematics(A Journal of Chinese Universities) 2024年第2期39卷 343-362页

作者： HUANG xi-fen LIU Deng-ge ZHOU Yun-peng ZHU Fei School of Mathematics Yunnan Normal UniversityKunming 650092China Department of Statistics and Actuarial science The University of Hong KongHong KongChina

The mixed distribution model is often used to extract information from heteroge-neous data and perform modeling *** the density function of mixed distribution is complicated or the variable dimension is high,it usually brings challenges to the parameter es-timation of the mixed distribution *** application of MM algorithm can avoid complex expectation calculations,and can also solve the problem of high-dimensional optimization by decomposing the objective *** this paper,MM algorithm is applied to the parameter estimation problem of mixed distribution *** method of assembly and decomposition is used to construct the substitute function with separable parameters,which avoids the problems of complex expectation calculations and the inversion of high-dimensional matrices.

关键词： MM algorithm mixed distribution model parameter estimation assembly decomposition tech-nology parameter separation

Melt-spun Al_(70-X)Si_(30)Mn_X (X=0,3,5,7,10) anode in lithium-ion batteries

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science china(Technological sciences) 2009年第8期52卷 2288-2294页

作者： SUN ZhanBo1, LI XuePeng1, WANG xiaoDong1, HU Qing1, ZHAO MingShu1, ZHU YaoMin2, LI Yan2 & SONG xiaoPing1 1 School of science, State Key Laboratory for Mechanical Behavior of Materials, xi’an Jiaotong university, xi’an 710049, china 2 School of Materials science and Engineering, Henan university of science and Technology, Luoyang 471003, china 1. School of science State Key Laboratory for Mechanical Behavior of Materials Xi’an Jiaotong University Xi’an 710049 China 2. School of Materials science and Engineering Henan University of Science and Technology Luoyang 471003 China

Al70-XSi30MnX (X=0, 3, 5, 7, 10, mol%) ribbons were prepared by melt spinning. A supersaturated solid solution of Si and Mn in fcc Al and some microstructures consisting of nano grains were obtained. Some alloys with nano-sized grains exhibited high discharge capacities and favorable cycle properties. The capacity of more than 400 mAh/g could be obtained in melt-spun Al67Si30Mn3 alloy after 20 cycles and more than 300 mAh/g after 40 cycles. Li/Si and Li/Al compounds in the anodes of pure Al and pure Si were not detected in Al-Si-Mn alloys inserted by Li. It is considered that the formation of the supersaturated solid solution and refinement of microstructures have prevented the alloys from the forming the compounds with superfluous Li. As a result, the electrochemical properties have been improved.

关键词： Al-Si-Mn alloy melt spinning microstructure electrochemical property

Tree‑Inspired Structurally Graded Aerogel with Synergistic Water,Salt,and Thermal Transport for High‑Salinity Solar‑Powered Evaporation

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Nano-Micro Letters 2024年第11期16卷 19-37页

作者： xiaomeng Zhao Heng Zhang Kit‑Ying Chan xinyue Huang Yunfei Yang xi Shen Department of Aeronautical and Aviation Engineering The Hong Kong Polytechnic UniversityHung HomKowloonHong Kong SARPeople’s Republic of China Research Institute for Sports science and Technology The Hong Kong Polytechnic UniversityHung HomKowloonHong Kong SARPeople’s Republic of China Research Institute for Advanced Manufacturing The Hong Kong Polytechnic UniversityHung HomKowloonHong Kong SARPeople’s Republic of China

Solar-powered interfacial evaporation is an energy-efficient solution for water *** requires solar absorbers to facilitate upward water transport and limit the heat to the surface for efficient ***,downward salt ion transport is also desired to prevent salt ***,achieving simultaneously fast water uptake,downward salt transport,and heat localization is challenging due to highly coupled water,mass,and thermal ***,we develop a structurally graded aerogel inspired by tree transport systems to collectively optimize water,salt,and thermal *** arched aerogel features root-like,fan-shaped microchannels for rapid water uptake and downward salt diffusion,and horizontally aligned pores near the surface for heat localization through maximizing solar absorption and minimizing conductive heat *** structural characteristics gave rise to consistent evaporation rates of 2.09 kg m^(-2) h^(-1) under one-sun illumination in a 3.5 wt%NaCl solution for 7 days without *** in a high-salinity solution of 20 wt%NaCl,the evaporation rates maintained stable at 1.94 kg m^(-2) h^(-1) for 8 h without salt crystal *** work offers a novel microstructural design to address the complex interplay of water,salt,and thermal transport.

关键词： Composite aerogel Graded structure Solar-powered evaporation Thermal insulation Salt rejection

Confluence of asymmetric catalysis and electrosynthesis in sustainable chemical transformations

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science china Chemistry 2024年第3期67卷 755-758页

作者： Qinglin Zhang Kang Liang chang Guo Hefei National Research Center for Physical sciences at the Microscale and Department of Chemistry University of Science and Technology of ChinaHefei 230026China

Electrosynthesis has gained widespread recognition for its extraordinary ability to precisely control the redox *** outstanding capability enables the direct conversion of non-functionalized substrates into reactive intermediates by utilizing easily accessible starting materials, eliminating the need for preliminary functionalization procedures and allowing for unconventional bond activations.

关键词： Confluence of asymmetric catalysis and electrosynthesis in sustainable chemical transformations

NONLINEAR GALERKIN METHOD AND CRANK-NICOLSONMETHOD FOR VISCOUS INCOMPRESSIBLE FLOW

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Journal of Computational Mathematics 1999年第2期17卷 139-158页

作者： Yin-nian He Dong-sheng Li Kai-Tai Li(College of science, xi’an Jiaotong university, xi’an 710019, china) 西安交通大学基础科学部陕西西安

In this article we discuss a new full discrete scheme for the numerical solution of the Navier-Stokes equations modeling viscous incompressible flow. This scheme consists of nonlinear Galerkin method using mixed finite elements and Crank-Nicolson method. Next, we provide the second-order convergence accuracy of numerical solution corresponding to this scheme. Compared with the usual Galerkin scheme, this scheme can save a large amount of computational time under the same convergence accuracy. (Author abstract) 8 Refs.

关键词： nonlinear Galerkin method Crank-Nicolson method viscous incompressible flow

(2,n)secret sharing scheme for gray and color images based on Boolean operation

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science china(Information sciences) 2012年第5期55卷 1151-1161页

作者： DONG Lin 1,WANG DaoShun 1,LI ShunDong 2 & DAI YiQi 1 1 Department of Computer science and Technology,Tsinghua university,Beijing 100084,china 2 School of Computer science,Shaanxi Normal university,xi'an 710062,china 1. Department of Computer science and Technology Tsinghua University Beijing 100084 China2. School of Computer Science Shaanxi Normal University Xi’an 710062 China

Traditional secret sharing (SS) schemes can reconstruct the secret precisely,but have high com-putation *** secret sharing (VSS) schemes use human visual system to reconstruct the secret without cryptographic computation,but have pixel expansion and loss of *** et *** a (2,n)-SS scheme for binary images based on Boolean operation,which has low computation complexity,no pixel expansion and the contrast is 1/*** this paper,we first construct an r runs (2,n)-SS scheme to improve the contrast of Wang et al.'s binary (2,n)-SS *** we present two approaches to construct r runs (2,n)-SS schemes for grayscale image and color *** two approaches are both based on Boolean operation,while one approach uses halftone technology and the other uses bit level *** proposed schemes have low computation complexity and almost ideal contrast.

关键词： secret sharing scheme Boolean operation halftone contrast

FINITE ELEMENT NONLINEAR GALERKIN COUPLINGMETHOD FOR THE EXTERIOR STEADY NAVIER-STOKESPROBLEM

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Journal of Computational Mathematics 1999年第6期17卷 595-608页

作者： Yin-nian He Kai-tai Li Fu-hai Gao(College of science, xi’an Jiaotong university, xi’an 710049, china) xian Jiao Tong Univ Coll Sci Xian 710049 Peoples R China

In this paper we represent a new numerical method for solving the steady Navier-Stokes equations in three dimensional unbounded domain. The method consists in coupling the boundary integral and the finite element nonlinear Galerkin methods. An artificial smooth boundary is introduced seperating an interior inhomogeneous region from an exterior one. The Navier-Stokes equations in the exterior region are approximated by the Oseen equations and the approximate solution is represented by an integral equation over the artificial boundary. Moreover, a finite element nonlinear Galerkin method is used to approximate the resulting variational problem. Finally, the existence and error estimates are derived.

关键词： Navier-Stokes equations Oseen equations boundary integral finite element nonlinear Galerkin method