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Evaluation of the injection and plugging ability of a novel epoxy resin in cement cracks

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Petroleum Science 2024年第2期21卷 1211-1220页

作者： Guang-Yao Leng Wei Yan Hai-mu Ye Er-Dong Yao Ji-Bin Duan Zheng-xian Xu Ke-Pei li Jing-Ru Zhang Zhong li State Key Laboratory of Petroleum Resource&Prospecting China University of Petroleum(Beijing)Beijing102249China CNPC liaohe Oilfield Gas Storage Co.LTD Panjin124000LiaoningChina CNOOC Research Institute Co. Ltd.Beijing100028China

Sustained casing pressure(SCP)is a crucial issue in the oil and gas production *** resins,exhibiting exceptional compressive strength,ductility,and shear bonding strength,have the potential to form reliable *** injectivity and sealing capacity of the epoxy resin is crucial parameters for the success of shallow remediation *** study aimed to develop and assess a novel solid-free resin sealant as an alternative to Portland cement for mitigating fluid *** investigation evaluated the viscosity,compressive strength,and brittleness index of the epoxy resin sealant,as well as its tangential and normal shear strengths in conjunction with casing *** flow characteristics and sealing abilities of conventional cement and epoxy resin were comparatively analyzed in *** results showed that the application of a viscosity reducer facilitated control over the curing time of the epoxy resin,ranging from 1.5 to 6 h,and reduced the initial viscosity from 865.53 to 118.71 m Pa,*** mechanical properties of the epoxy resin initially increased with a rise in curing agent content before experiencing a minor *** epoxy resin containing 30%curing agent exhibited optimal mechanical *** a 14-day curing period,the epoxy resin's compressive strength reached81.37 MPa,2.12 times higher than that of cement,whereas the elastic modulus of cement was 2.99 times greater than that of the epoxy *** brittleness index of epoxy resin is only 3.42,demonstrating high flexibility and *** tangential and normal shear strengths of the epoxy resin exceeded those of cement by 3.17 and 2.82 times,*** a 0.5 mm-wide crack,the injection pressure of the epoxy resin remained below 0.075 MPa,indicating superior injection and flow ***,the injection pressure of cement surged dramatically to 2.61 MPa within 5 *** breakthrough pressure of0.5 PV epoxy resin reached 7.53 MPa,decreasing the crack's perme

关键词： Sustained casing pressure Epoxy resin sealant Curing agent Viscosity reducer Mechanical properties Crack sealing

limit Theorems for Critical Galton-Watson Processes with Immigration Stopped at Zero

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Acta Mathematica Sinica,English Series 2024年第2期40卷 435-450页

作者： Dou Dou li Mei ZHANG xian Yu ZHANG College of Statistics and Data Science Faculty of ScienceBeijing University of TechnologyBeijing 100124P.R.China Laboratory of Mathematics and Complex Systems(Ministry of Education) School of Mathematical SciencesBeijing Normal UniversityBeijing 100875P.R.China

In this paper,we consider a critical Galton-Watson branching process with immigration stopped at zero *** precise estimation on the probability generating function of the n-th population are obtained,and the tail prob... 详细信息

关键词： Branching immigration critical life period limit theorems

Evaluation of transmission risk of respiratory particles under different ventilation strategies in an elevator

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Building Simulation 2024年第5期17卷 771-784页

作者： liangyu Zhu xian li Bujin Feng Fan liu School of Civil Engineering and Architecture Linyi UniversityLinyi276000China College of Agriculture Shandong Agricultural UniversityTaian271018China School of Environment and Architecture University of Shanghai for Science and TechnologyShanghai200093China

People in elevators are at risk of respiratory infection because the elevator cabin is crowded and has poor *** exhaled particles may be inhaled by the susceptible person,deposited on the surface and suspended in the elevator,which can result in direct and indirect ***,whether the air vent designs adopted in the elevator can effectively reduce the transmission risk of respiratory particles remains *** this study,the dispersion of particles under four common ventilation strategies used in the commercial elevator was investigated by proven computational fluid dynamics(CFD)*** flow field was simulated with the RNG κ-ξ turbulence model and the Lagrangian method was adopted to track particle *** effects of air vent layout and airflow rate on particle transmission were *** found that more than 50% of exhaled particles(average value)were suspended in the cabin and difficult to discharge under the investigated ventilation *** deposited fraction of particles on the susceptible person reached up to 39.14% for infiltration ventilation,which led to a high risk of contact *** the ventilation rate could not significantly reduce the inhalation proportion of particles due to the poor airflow distribution inside the elevator.A more proper ventilation strategy should be explored for the elevator to control transmission risk.

关键词： particle dispersion transmission risk elevator ventilation strategy computational fluid dynamics(CFD)

multi-sensor multispectral reconstruction framework based on projection and reconstruction

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Science China(Information Sciences) 2024年第3期67卷 246-262页

作者： Tianshuai li Tianzhu liU xian li Yanfeng GU Yukun WANG Yushi CHEN School of Electronics and Information Engineering Harbin Institute of Technology Heilongjiang Province Key Laboratory of Space-Air-Ground Integrated Intelligent Remote Sensing

The scarcity and low spatial resolution of hyperspectral images(HSIs) have become a major problem limiting the application of the images. In recent years, spectral reconstruction(SR) has been applied to convert multispectral images(MSIs) with abundant quantities and high spatial resolution into HSIs. With the launch of several new multispectral(MS) satellites with a short repeat period, the simultaneous acquisition of images from multiple MS sensors in the same area is gradually becoming feasible. Unfortunately, existing SR methods only consider the reconstruction of the MSIs of a single sensor without considering using MSIs from different MS sensors to obtain a better construction effect through their complementary bands. However,multi-sensor SR is characterized by two problems: inconsistency in the amplitude information of real multisensor imaging and difficulty in the extraction of the complex correlations of bands from different *** solve these problems, this paper proposes a multi-sensor SR framework based on a two-step approach in which the problems of amplitude inconsistency and band information extraction are solved using an ideal projection network and an ideal multi-sensor SR network, respectively. The effectiveness of the proposed method is verified by experiments on three datasets.

关键词： spectral reconstruction spectral superresolution hyperspectral image multispectral image neural networks multi-sensor

Tracking direct and indirect impact on technology and policy of transformative research via ego citation network

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Journal of Data and Information Science 2024年第3期9卷 65-87页

作者： xian li Xiaojun Hu College of Computer and Information Science Southwest UniversityChongqing 400037China Medical Information Center Zhejiang University School of MedicineHangzhou 310058China

Purpose:The disseminating of academic knowledge to nonacademic audiences partly relies on the transition of subsequent citing *** study aims to investigate direct and indirect impact on technology and policy originating from transformative research based on ego citation ***/methodology/approach:Key Nobel Prize-winning publications(NPs)in fields of gene engineering and astrophysics are regarded as a proxy for transformative *** this contribution,we introduce a network-structural indicator of citing patents to measure technological impact of a target article and use policy citations as a preliminary tool for policy ***:The results show that the impact on technology and policy of NPs are higher than that of their subsequent citation generations in gene engineering but not in *** limitations:The selection of Nobel Prizes is not balanced and the database used in this study,Dimensions,suffers from incompleteness and inaccuracy of citation *** implications:Our findings provide useful clues to better understand the characteristics of transformative research in technological and policy ***/value:This study proposes a new framework to explore the direct and indirect impact on technology and policy originating from transformative research.

关键词： Transformative research Nobel Prize winning articles Citation networks Technological impact Policy impact

Low-noise and low-power pixel sensor chip for gas pixel detectors

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Nuclear Science and Techniques 2024年第3期35卷 142-152页

作者： Zhuo Zhou Shi-Qiang Zhou Dong Wang xiang-Ming Sun Chao-Song Gao Peng-Zhen Zhu Wei-Ping Ren Jun liu mu-xian li Chen lian Chun-Lai Dong PLAC Key Laboratory of Quark and Lepton Physics(MOE)Central China Normal UniversityWuhan 430079China

Topmetal-M2 is a large-area pixel sensor chip fabricated using the GSMC 130 nm CMOS process in *** pixel array of Topmetal-M2 consists of pixels of 400 rows×512 columns with a pixel pitch of 45μm×45μ*** array is divided into 16 subarrays,with pixels of 400 rows×32 columns per *** pixel incorporates two charge sensors:a diode sensor and a Topmetal *** in-pixel circuit primarily consists of a charge-sensitive amplifier for energy measurements,a discriminator with a peak-holding circuit,and a time-to-amplitude converter for time-of-arrival *** pixel of Topmetal-M2 has a charge input range of~0-3 k e-,a voltage output range of~0-180 mV,and a charge-voltage conversion gain of~59.56μV∕e-.The average equivalent noise charge of Topmetal-M2,which includes the readout electronic system noise,is~43.45 e-.In the scanning mode,the time resolution of Topmetal-M2 is 1 LSB=1.25μs,and the precision is^()7.41μ*** an operating voltage of 1.5 V,Topmetal-M2 has a power consumption of~49 mW∕cm~*** this article,we provide a comprehensive overview of the chip architecture,pixel working principles,and functional behavior of ***,we present the results of preliminary tests conducted on Topmetal-M2,namely,alpha-particle and soft X-ray tests.

关键词： Charge collection Gas detectors Semiconductor detectors X-ray detectors

An adaptive 3D reconstruction method for asymmetric dual-angle multispectral stereo imaging system on UAV platform

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Science China(Information Sciences) 2024年第8期67卷 285-299页

作者： Chen WANG xian li Yanfeng GU Zixu WANG School of Electronics and Information Engineering Harbin Institute of Technology Beijing Institute of Control and Electronic Technology

A multispectral imaging system often cannot capture 3D spatial information owing to hardware limitations, which diminishes the effectiveness across various domains. To address this problem, we have developed a multispectral stereo imaging system along with an adaptive 3D reconstruction algorithm. Unlike existing unmanned aerial vehicle stereo imaging systems, our multispectral stereo imaging system uses two multispectral cameras with asymmetric spectral bands positioned at different angles. This design enables the acquisition of a higher number of bands and lateral spatial information while maintaining a lightweight structure. This system introduces challenges such as large geometric distortions and intensity differences between multiple bands. To accurately recover 3D spatial information, we propose an adaptive 3D reconstruction method. This method employs a position and orientation system-assisted projection transformation and a normalized threshold adjustment strategy. Finally, mutual information is used to reconstruct the multispectral images densely, effectively addressing nonlinear differences and generating a comprehensive multispectral point cloud. Our stereo system was used for two real data collections in different regions, and the efficacy of the proposed 3D reconstruction method was validated by comparing it with existing methods and commercial software.

关键词： 3D reconstruction feature extraction multispectral images stereo imaging system unmanned aerial vehicle

Upgrading waste NO_(x) into amino acids via electrocatalysis on Co nanoparticles encapsulated in hollow carbon nanofibers

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Science China Chemistry 2024年第6期67卷 1946-1952页

作者： Jiahui xian Kaixing Cai Peisen liao Shihan Wang Guangqin li Key Laboratory of Bioinorganic and Synthetic Chemistry of Ministry of Education LIFMIGCMESchool of ChemistrySun Yat-Sen UniversityGuangzhou510275China

Electrocatalytic conversion of waste nitrogen oxide(NO_(x))into value-added nitrogenous chemicals,especially amino acid,is an emerging strategy to alleviate NO_(x)***,this process suffers from the coexistence of multiple competitive reactions leading to complex product distribution and low efficiency,and thus the rational design and modulation of efficient catalysts remains a formidable ***,well-designed Co nanoparticles encapsulated in hollow carbon nanofiber(CoHCNF)were constructed to promote the amino acid electrosynthesis via dealing waste NO_(x)coupling with biomass-derived keto *** to the rapid reactant diffusion,electron transport and efficient contact with abundant accessible Co catalytic sites stemmed from the unique hollow nanotubular structure,Co-HCNF manifested impressive glycine synthesis performance in one-pot adopting NO as the nitrogen source with Faradaic efficiency(FE)of 41.7%and a corresponding yield rate of 222.3μmol h^(-1)as well as 120 h robust ***,it also demonstrates an excellent performance with the FE of 42.8%for NO_(3)~-solution as the nitrogen ***,this strategy displays a broad universality for the synthesis of other amino *** work not only highlights the importance of hollow-structuring electrocatalyst towards upgrading wasted NO_(x)species into amino acids,but also promotes the further development of electrosynthetic systems for high-valued N-containing organic chemicals.

关键词： electrocatalysis NO_(x)reduction amino acid porous materials hollow structure

Hybrid vibration isolation optimization of a flexible manipulator based on neural network agent model

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Chinese Journal of Aeronautics 2024年第5期37卷 482-505页

作者： Yongxin ZHANG liang li Dingguo ZHANG Wei-Hsin liAO xian GUO School of Science Nanjing University of Science and TechnologyNanjing 210094China Department of Mechanical and Automation Engineering The Chinese University of Hong KongHong KongChina

Segmented Active Constrained Layer Damping(SACLD)is an intelligent vibration-damping structure,which could be applied to the sectors of aviation,aerospace,and transportation engineering to reduce the vibration of flexible ***,machine learning technology is widely used in the engineering field because of its efficient multi-objective *** dynamic simulation of a rotational segmental flexible manipulator system is presented,in which enhanced active constrained layer damping is carried out,and the neural network model of Genetic Algorithm-Back Propagation(GA-BP)algorithm is *** suppression and structural optimization of the SACLD manipulator model are studied based on vibration mode and damping *** modal responses of the SACLD manipulator model at rest and rotation are *** addition,the four model indices are optimized using the GA-BP neural network:axial incision size,axial incision position,circumferential incision size,and circumferential incision ***,the best model for vibration suppression is obtained.

关键词： Machine learning Vibration suppression Flexible manipulator Segmented active constrained layer damping Structural optimization