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A semi-analytical model for coupled flow in stress-sensitive multi-scale shale reservoirs with fractal characteristics

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Petroleum Science 2024年第1期21卷 327-342页

作者： Qian Zhang Wen-dong Wang Yu-Liang Su Wei Chen Zheng-dong lei lei Li Yong-Mao Hao Key Laboratory of Unconventional Oil&Gas Development(China University of Petroleum(East China)) Ministry of EducationQingdao266580ShandongChina School of Petroleum Engineering China University of Petroleum(East China)Qingdao266580ShandongChina Shale Oil Development Branch Changqing Oilfield CompanyPetroChinaQingyang745708GansuChina PetroChina Research Institute of Petroleum Exploration&Development Beijing100083China

A large number of nanopores and complex fracture structures in shale reservoirs results in multi-scale flow of oil. With the development of shale oil reservoirs, the permeability of multi-scale media undergoes changes due to stress sensitivity, which plays a crucial role in controlling pressure propagation and oil flow. This paper proposes a multi-scale coupled flow mathematical model of matrix nanopores, induced fractures, and hydraulic fractures. In this model, the micro-scale effects of shale oil flow in fractal nanopores, fractal induced fracture network, and stress sensitivity of multi-scale media are considered. We solved the model iteratively using Pedrosa transform, semi-analytic Segmented Bessel function, Laplace transform. The results of this model exhibit good agreement with the numerical solution and field production data, confirming the high accuracy of the model. As well, the influence of stress sensitivity on permeability, pressure and production is analyzed. It is shown that the permeability and production decrease significantly when induced fractures are weakly supported. Closed induced fractures can inhibit interporosity flow in the stimulated reservoir volume (SRV). It has been shown in sensitivity analysis that hydraulic fractures are beneficial to early production, and induced fractures in SRV are beneficial to middle production. The model can characterize multi-scale flow characteristics of shale oil, providing theoretical guidance for rapid productivity evaluation.

关键词： Multi-scale coupled flow Stress sensitivity Shale oil Micro-scale effect Fractal theory

Tracking lithiation with transmission electron microscopy

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Science China Chemistry 2024年第1期67卷 291-311页

作者： Xincheng lei Jianxiong Zhao Jiayi Wang dong Su Beijing National Laboratory for Condensed Matter Physics Institute of PhysicsChinese Academy of SciencesBeijing 100190China South China Academy of Advanced Optoelectronics&International Academy of Optoelectronics at Zhaoqing South China Normal UniversityGuangzhou 510006China

Li-ion batteries(LIBs)have dominated energy-storage techniques for portable electronic devices and electric cars,and are expanding their territory into the large-scale energy *** energy storage of LIBs is realized by the reversible shuttle of lithium ions between *** is essential to track the lithium diffusion and obtain a profound insight into the lithiation mechanism during the work cycle of *** electron microscopy(TEM)is a powerful tool for the structural characterization,which can provide the information about the lithiation at the atomic *** this review,we summarize the research frontiers of TEM applications on *** introduce the techniques for the direct observation of Li species in LIB-related ***,the application of cryo-TEM is ***,in-situ TEM technique is further discussed since it shows great advantages in studying the dynamical structure changes of *** perspectives and strategies in this review offer feasible guidance for researchers to further improve the performance of LIBs.

关键词： lithium-ion battery electrode materials transmission electron microscopy cryo-TEM in-situ TEM

Selective photosynthesis of Z-olefins through crystalline metal-organic cage-initiated expeditious cascade reactions

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Carbon Energy 2024年第3期6卷 118-131页

作者： Jia-Ni Lu Yunze Huang Yuan-Sheng Xia Long-Zhang dong lei Zhang Jing-Jing Liu Lan-Gui Xie Jiang Liu ya-Qian Lan Jiangsu Key Laboratory of New Power Batteries School of Chemistry and Materials ScienceJiangsu Collaborative Innovation Centre of Biomedical Functional MaterialsNanjing Normal UniversityNanjingChina School of Chemistry South China Normal UniversityGuangzhouChina

The semi-hydrogenation of alkyne to form Z-olefins with high conversion and high selectivity is still a huge challenge in the chemical ***,flammable and explosive hydrogen as the common hydrogen source of this reaction increases the cost and danger of industrial ***,we connect the photocatalytic hydrogen evolution reaction and the semihydrogenation reaction of alkynes in series and successfully realize the high selective production of Z-alkenes using low-cost,safe,and green water as the proton *** the cascade reaction,a series of isomorphic metal–organic cage catalysts(Co_(x)Zn_(8−x)L_(6),x=0,3,4,5,and 8)are designed and synthesized to improve the yield of the photocatalytic hydrogen *** them,Co_(5)Zn_(3)L_(6) shows the highest photocatalytic activity,with a H_(2) generation rate of 8.81 mmol g^(−1) h^(−1).Then,Co_(5)Zn_(3)L_(6) is further applied in the above tandem reaction to efficiently reduce alkynes to Z-alkenes under ambient conditions,which can reach high conversion of>98%and high selectivity of>99%,and maintain original catalytic activity after multiple ***“one-pot”tandem reaction can achieve a highly selective and safe stepwise conversion from water into hydrogen into Z-olefins under mild reaction conditions.

关键词： alkyne semi-hydrogenation hydrogen evolution reaction metal-organic cages photocatalysis Z-olefins

Optimal investment based on relative performance and weighted utility

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Applied Mathematics(A Journal of Chinese Universities) 2024年第2期39卷 328-342页

作者： WANG lei dong Ying-hui HUA Chun-rong Department of Mathematics Suzhou University of Science and TechnologySuzhou 215009China Changshu Institute of Technology Changshu 215500China

This paper studies the optimal portfolio allocation of a fund manager when he bases decisions on both the absolute level of terminal relative performance and the change value of terminal relative performance comparison to a predefined reference point. We find the optimal investment strategy by maximizing a weighted average utility of a concave utility and an Sshaped utility via a concavification technique and the martingale method. Numerical results are carried out to show the impact of the extent to which the manager pays attention to the change of relative performance related to the reference point on the optimal terminal relative performance.

关键词： relative performance weighted utility S-shaped utility concavification

Power equipment vibration visualization using intelligent sensing method based on event-sensing principle

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Global Energy Interconnection 2024年第2期7卷 228-240页

作者： Mingzhe Zhao Xiaojun Shen lei Su Zihang dong Tongji University No.1239 Siping RoadYangpu DistrictShanghai 200092P.R.China State Grid Shanghai Municipal Electric Power Company Electric Power Science Research Institute Shanghai 200437P.R.China Department of Electrical and Electronic Engineering Imperial College LondonLondonSW72AZU.K.

Vibration measurements can be used to evaluate the operation status of power equipment and are widely applied in equipment quality inspection and fault ***-sensing technology can sense the change in surface light intensity caused by object vibration and provide a visual description of vibration *** on the analysis of the principle underlying the transformation of vibration behavior into event flow data by an event sensor,this paper proposes an algorithm to reconstruct event flow data into a relationship correlating vibration displacement and time to extract the amplitude-frequency characteristics of the vibration signal.A vibration measurement test platform is constructed,and feasibility and effectiveness tests are performed for the vibration motor and other power *** results show that event-sensing technology can effectively perceive the surface vibration behavior of power and provide a wide dynamic ***,the vibration measurement and visualization algorithm for power equipment constructed using this technology offers high measurement accuracy and *** results of this study provide a new noncontact and visual method for locating vibrations and performing amplitude-frequency analysis on power equipment.

关键词： Power equipment Event sensing Non contact measurement Graphic display Feasibility

Local search yields a PTAS for fixed-dimensional k-means problem with penalties

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Journal of the Operations Research Society of China 2024年第2期12卷 351-362页

作者： Fan Yuan Da-Chuan Xu dong-lei Du dong-Mei Zhang Beijing Institute for Scientific and Engineering Computing Beijing University of TechnologyBeijing 100124China Faculty of Management University of New BrunswickFrederictonNB E3B 9Y2Canada School of Computer Science and Technology Shandong Jianzhu UniversityJinan 250101ShandongChina

We study a problem called the k-means problem with penalties(k-MPWP),which is a natural generalization of the typical k-means *** this problem,we have a set D of client points in R^(d),a set F of possible centers in R^(d),and a penalty cost Pj>O for each point j∈*** are also given an integer k which is the size of the center point *** want to find a center point set S■F with size k,choose a penalized subset of clients P■D,and assign every client in D\P to its open *** goal is to minimize the sum of the squared distances between every point in D\P to its assigned centre point and the sum of the penalty costs for all clients in *** using the multi-swap local search technique and under the fixed-dimensional Euclidean space setting,we present a polynomial-time approximation scheme(PTAS)for the k-MPWP.

关键词： Approximation algorithm k-means Local search Penalty

Exceptional points enhance sensing in silicon micromechanical resonators

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Microsystems & Nanoengineering 2024年第1期10卷 17-25页

作者： Man-Na Zhang lei dong Li-Feng Wang Qing-An Huang Key Laboratory of MEMS of the Ministry of Education Southeast UniversityNanjing 210096China

Exceptional points(EPs)have recently emerged as a new method for engineering the response of open physical systems,that is,systems that interact with the *** systems at the EPs exhibit a strong response to a small ***,we show a method by which the sensitivity of silicon resonant sensors can be enhanced when operated at *** our experiments,we use a pair of mechanically coupled silicon micromechanical resonators constituting a parity-time(PT)-symmetric *** perturbations introduced on the mechanically coupled spring cause the frequency to split from the EPs into the PT-symmetric regime without broadening the two spectrum linewidths,and this frequency splitting scales with the square root of the perturbation *** overall signal-tonoise ratio is still greatly enhanced,although the measured noise spectral density of the EP sensing scheme has a slight increase comparable to the traditional *** results pave the way for resonant sensors with ultrahigh sensitivity.

关键词： resonant symmetric points

Nanocrystalline WSe_(2)excels at high-performance anode for Na storage via a facile one-pot hydrothermal method

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Tungsten 2024年第1期6卷 248-258页

作者： Hai-yan Zou lei Fang Gang Yu dong Wang State Key Laboratory of Chem/Bio-Sensing and Chemometrics Provincial Hunan Key Laboratory for Graphene Materials and DevicesCollege of Chemistry and Chemical EngineeringHunan UniversityChangsha 410082China Changxing County Quality and Technology Supervision and Testing Center Huzhou 313100China

For the next large-scale energy storage systems,sodium-ion batteries(SIBs)with excellent electrochemical performance are ***,the exploration of anode materials with high specific capacity,fascinating cycling stability and rate capability is still *** transition metal dichalcogenides(TMDs),tungsten diselenide(WSe_(2))has been regarded as an effective anode material for SIBs and has been extensively studied,due to high theoretical capacity and unique twodimensional layered ***,nanocrystalline WSe_(2)is prepared by a facile one-pot hydrothermal *** with the micro-scale WSe_(2),benefiting from the high specific surface area of highly ordered nano-flake structures and short ion/electron transport paths,nanocrystalline WSe_(2)shows excellent electrochemical performance in Na *** 1000 cycles at a current density of 2 A·g^(-1),a high specific capacity of 264.4 mA·h·g^(-1)is still *** full cell matched with the Na_(3)V_(2)(PO_(4))_(3) cathode can deliver an excellent reversible specific capacity of 196.5 mA·h·g^(-1)after 100 cycles at 0.5 A·g^(-1).

关键词： Tungsten diselenide Transition metal dichalcogenides Hydrothermal Sodium-ion batteries Layered structure

Reflective ultrathin light-sheet microscopy with isotropic 3D resolutions

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Photonics Research 2024年第2期12卷 271-281页

作者： YUE WANG DASHAN dong WENKAI yaNG RENXI HE MING lei KEBIN SHI State Key Laboratory for Mesoscopic Physics Department of PhysicsPeking UniversityBeijing 100871China State Key Laboratory of Membrane Biology School of Life Sciencesand Biomedical Pioneering Innovation Center(BIOPIC)Peking UniversityBeijing 100871China School of Physics Xi’an Jiaotong UniversityXi’an 710049China Collaborative Innovation Center of Extreme Optics Shanxi UniversityTaiyuan 030006China Peking University yangtze Delta Institute of Optoelectronics Nantong 226010China

Light-sheet fluorescence microscopy(LSFM)has played an important role in bio-imaging due to its advantages of high photon efficiency,fast speed,and long-term imaging *** perpendicular layout between LSFM excitation and detection often limits the 3D resolutions as well as their ***,we report on a reflective type light-sheet microscope with a mini-prism used as an optical path *** conventional high NA objectives can be used both in excitation and detection with this *** resolutions in 3D down to300 nm could be achieved without *** proposed method also enables easy transform of a conventional fluorescence microscope to high performance light-sheet microscopy.

关键词： resolution excitation light