检索结果-南通市图书馆

Numerical Analysis of Perforation during Hydraulic Fracture Initiation Based on Continuous-Discontinuous Element Method

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

Computer Modeling in Engineering & Sciences 2024年第8期140卷 2103-2129页

作者： Rui zhang Lixiang Wang jing Li Chun Feng Yiming zhang School of Civil and Transportation Engineering Hebei University of TechnologyTianjin300401China Key Laboratory for Mechanics in Fluid Solid Coupling Systems Institute of MechanicsChinese Academy of SciencesBeijing100190China School of Civil Engineering and Architecture Zhejiang Sci-Tech UniversityHangzhou310018China Jinyun Institute Zhejiang Sci-Tech UniversityLishui321400China

Perforation is a pivotal technique employed to establish main flow channels within the reservoir formation at the outset of hydraulic fracturing *** perforation designs is critical for augmenting the efficacy of hydraulic fracturing and boosting oil or gas *** this study,we employ a hybrid finite-discrete element method,known as the continuous–discontinuous element method(CDEM),to simulate the initiation of post-perforation hydraulic fractures and to derive enhanced design *** model incorporates the four most prevalent perforation geometries,as delineated in an engineering technical ***-world perforations deviate from the ideal cylindrical shape,exhibiting variable cross-sectional profiles that typically manifest as an initial constriction followed by an expansion,a feature consistent across all four perforation *** simulations take into account variations in perforation hole geometries,cross-sectional diameters,and perforation *** findings show that perforations generated by the 39g DP3 HMX perforating bullet yield the lowest breakdown pressure,which inversely correlates with increases in sectional diameter and perforation ***,this study reveals the relationship between breakdown pressure and fracture degree,providing valuable insights for engineers and designers to refine perforation strategies.

关键词： Hydraulic fracturing real perforation shape breakdown pressure perforation layout design CDEM

Discovery of New Iridoids as Farnesoid X Receptor Agonists from Morinda officinalis: Agonistic Potentials and Molecular Stimulation

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

Chinese Journal of Chemistry 2021年第5期39卷 1288-1296页

作者： Zhi-Lin Luan Fei Qiao Wen-Yu Zhao Wen-Hua Ming Zhen-Long Yu Jie Liu Sheng-Yun Dai Shuang-Hui Jiang Chao-Jie Lian Cheng-Peng Sun bao-jing zhang Jian Zheng Shuang-Cheng Ma Xiao-Chi Ma Dalian Key Laboratory of Metabolic Target Characterization and Traditional Chinese Medicine Intervention College of PharmacyCollege of Integrative MedicineDalian Medical UniversityDalianLiaoning 116044China National Institutes for Food and Drug Control Beijing 102629China

The investigation of Morinda officinalis led to the isolation of twelve compounds(1-12),including three new iridoid glycosides morindallns A-C(1-3)and nine known compounds(4-12).Their structural identifications were conducted using HRMS,1D and 2D NMR,and electronic circular dichroism(ECD)spectra as well as quantum chemical *** 6 displayed the most significantly agonistic activity against farnesoid X receptor(FXR)with an EC_(50) value of 7.18 μM,and its agonistic effect was verified through the investigation of FXR downstream target genes including small heterodimer partner 1(SHP1),bile salt export pump(BSEP),and organic solute transporter subunit alpha and beta(OSTα and OSTβ).The potential interaction of compound 6 with FXR was analyzed by molecular docking and molecular dynamics stimulation,revealing that amino acid residues Leu287;Thr288,and Ser332 played a crucial role in the activation of compound 6 towards *** findings suggested that compound 6 could be regarded as a potential candidate for the development of FXR agonists.

关键词： Morinda officinalis Iridoid Farnesoid X receptor Agonistic effect

FPGA implementation of 500-MHz high-count-rate high-time-resolution real-time digital neutron-gamma discrimination for fast liquid detectors

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

Nuclear Science and Techniques 2024年第8期35卷 101-113页

作者： Hui‑Yin Shen jing‑Long zhang Jie zhang Jian‑Hang Zhou College of Nuclear Technology and Automation Engineering Chengdu University of TechnologyChengdu 610059China Southwestern Institute of Physics P.O.Box 432Chengdu 610041China

Fast neutron flux measurements with high count rates and high time resolution have important applications in equipment such as *** this study,real-time neutron and gamma discrimination was implemented on a self-developed 500-Msps,12-bit digitizer,and the neutron and gamma spectra were calculated directly on an FPGA.A fast neutron flux measurement system with BC-501A and EJ-309 liquid scintillator detectors was developed and a fast neutron measurement experiment was successfully performed on the HL-2 M tokamak at the Southwestern Institute of Physics,*** experimental results demonstrated that the system obtained the neutron and gamma spectra with a time accuracy of 1 *** count rates of up to 1 Mcps,the figure of merit was greater than 1.05 for energies between 50 keV and 2.8 MeV.

关键词： Neutron-gamma discrimination Liquid scintillation detector Real-time spectrum analyzer

Defect engineered nickel hydroxide nanosheets for advanced pseudocapacitor electrodes

维普期刊数据库

同方期刊数据库评论

在线全文

学校读者我要写书评

暂无评论

Nano Research 2024年第6期17卷 5233-5242页

作者： Yaohang Gu Yuxuan zhang Xuanyu Wang Ateer bao Bo Ni Haijun Pan Xiaoyan zhang Xiwei Qi School of Materials Science and Engineering Northeastern UniversityShenyang 110189China College of Metallurgy and Energy North China University of Science and TechnologyTangshan 063210China Key Laboratory of Dielectric and Electrolyte Functional Material Hebei Province School of Resources and MaterialsNortheastern University at QinhuangdaoQinhuangdao 066004China School of Resources and Materials Northeastern University at QinhuangdaoQinhuangdao 066004China

While the past years have witnessed great achievement in pseudocapacitors,the inauguration of electrode materials of high-performance still remains a formidable ***,the capacity and rate capability of the electrode depends largely on its electrical conductivity,which ensures fast charge transfer kinetics in both the grain bulk and grain ***,nickel hydroxides with oxygen vacancies are facilely fabricated via a hydrothermal *** active materials exhibit a high specific capacitance of 3250 F·g^(−1)and a high areal of capacitance of 14.98 F·cm^(−2)at 4.6 mA·cm^(−2).The asymmetric supercapacitor device based on our material delivers a high energy density of~71.6 Wh·kg^(−1)and a power density of~17,300 W·kg^(−1)and could retain~95%of their initial capacitance even after 30,000 *** addition,the defect-rich hydroxides demonstrate higher electrical conductivity as well as dielectric constant,which is responsible for the superior pseudocapacitive *** new scientific strategy in terms of taking the advantages of oxygen vacancies might open up new opportunities for qualified pseudocapacitive materials of overall high performances not only for nickel hydroxides but also for other metal hydroxides/oxides.

关键词： pseudocapacitors nickel hydroxides oxygen vacancies electrical conductivity

A Li_(3)P nanoparticle dispersion strengthened ultrathin Li metal electrode for high energy density rechargeable batteries

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

Nano Research 2024年第5期17卷 4031-4038页

作者： Lin Fu Xiancheng Wang bao zhang Zihe Chen Yuanjian Li Yongming Sun Provincial Guizhou Key Laboratory of Green Chemical and Clean Energy Technology School of Chemistry and Chemical EngineeringGuizhou UniversityGuiyang 550025China Wuhan National Laboratory for Optoelectronics Huazhong University of Science and TechnologyWuhan 430074China School of Physical and Mathematical Sciences Nanyang Technological UniversitySingapore 637371Singapore Institute of Materials Research and Engineering Agency for Science Technology and Research(A*STAR)Singapore 138634Singapore

Achievement of lithium(Li)metal anode with thin thickness(e.g.,≤30µm)is highly desirable for rechargeable high energy density ***,the fabrication and application of such thin Li metal foil electrode remain challenging due to the poor mechanical processibility and inferior electrochemical performance of metallic ***,mechanico-chemical synthesis of robust ultrathin Li/Li_(3)P(LLP)composite foils(~15µm)is demonstrated by employing repeated mechanical rolling/stacking operations using red P and metallic Li as raw *** in-situ formed Li+-conductive Li_(3)P nanoparticles in metallic Li matrix and their tight bonding strengthen the mechanical durability and enable the successful fabrication of free-standing ultrathin Li metal composite ***,it also reduces the electrochemical Li nucleation barrier and homogenizes Li plating/stripping *** matching to high-voltage LiCoO_(2),the full cell with a low negative/positive(N/P)capacity ratio of~1.5 offers a high energy density of~522 W·h·kg^(-1) at 0.5 C based on the mass of cathode and *** into account its facile manufacturing,potentially low cost,and good electrochemical performance,we believe that such an ultrathin composite Li metal foil design with nanoparticle-dispersion-strengthened mechanism may boost the development of high energy density Li metal batteries.

关键词： lithium metal anode high energy density battery mechanico-chemical synthesis ultrathin Li/Li_(3)P composite foil low negative/positive capacity ratio

Adaptive evolution of scn4aa in Takifugu and Tetraodon

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

Aquaculture and Fisheries 2024年第5期9卷 745-752页

作者： Hexing Wu Yonglai Hu jing Wang Xiaoling Gong baolong bao Key Laboratory of Exploration and Utilization of Aquatic Genetic Resources(Shanghai Ocean University) Ministry of EducationInternational Research Center for Marine Biosciences at Shanghai Ocean UniversityMinistry of Science and TechnologyNational Demonstration Center for Experimental Fisheries Science EducationShanghai Ocean UniversityShanghai201306China

Tetrodotoxin(TTX)is a potent neurotoxin firstly discovered in the ovary of *** genetic basis of voltage-gated sodium channel resistance to TTX has been widely studied,but it remains unclear in the evolution history of voltage-gated sodium channel resistance to TTX in pufferfish with different TTX *** this study,six scn4aa coding sequences of pufferfish were firstly cloned and sequenced,then used to investigate the adaptive evolution of scn4aa associated with TTX concentration and reconstruct ancestral sequences with seven scn4aa of other *** result of CODEML(codon substitution model)program from the PAML(phylogenetic analysis by maximum likelihood)package shows only in the genus of Takifugu,which contains TTX highly in the liver,under positive *** result also indicates that three of four positively selected sites are located in the intracellular regions,which may compensate for normal *** ancestral sequence reconstruction may suggest that the replacements providing weak toxin resistance might have appeared first in scn4aa,then the genus Takifugu evolved stronger resistance to TTX *** results contribute to the explanation of the evolutional history of voltage-gated sodium channel resistance to TTX in pufferfish.

关键词： Tetrodotoxin Voltage-gated sodium channel scn4aa Adaptive evolution Pufferfish

The posterior selection method for hyperparameters in regularized least squares method

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

Control Theory and Technology 2024年第2期22卷 184-194页

作者： Yanxin zhang jing Chen Yawen Mao Quanmin Zhu School of Science Jiangnan UniversityWuxi214122JiangsuChina The Science and Technology on Near-Surface Detection Laboratory Wuxi214122JiangsuChina Department of Engineering Design and Mathematics University of the West of EnglandBristolBS161QYUK

The selection of hyperparameters in regularized least squares plays an important role in large-scale system identification. The traditional methods for selecting hyperparameters are based on experience or marginal likelihood maximization method, which are inaccurate or computationally expensive. In this paper, two posterior methods are proposed to select hyperparameters based on different prior knowledge (constraints), which can obtain the optimal hyperparameters using the optimization theory. Moreover, we also give the theoretical optimal constraints, and verify its effectiveness. Numerical simulation shows that the hyperparameters and parameter vector estimate obtained by the proposed methods are the optimal ones.

关键词： Regularization method Hyperparameter System identification Least squares algorithm

A new gnetalean macrofossil from the Lower Cretaceous of the Laiyang Basin, eastern China

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

Plant Diversity 2024年第5期46卷 678-682页

作者： Peihong Jin Mingzhen zhang baoxia Du jing zhang Bainian Sun Key Laboratory of Petroleum Resources Northwest Institute of Eco-Environment and ResourcesChinese Academy of SciencesGansu ProvinceLanzhou 730000China Key Laboratory Western China's Mineral Resources of Gansu Province Lanzhou UniversityLanzhou 730000China

Gnetophytes are a key group of plant for understanding seed plant phylogeny,partly because of their unique and elusive morphology,such as xylem with vessels,phloem with chaperones,reticular veins,and double fertilization(Endress,1996).In particular,the ovule bears a membranous integument,the upper part of which extends beyond the seed envelope to form a micropylar ***,gnetophytes occupy a unique evolutionary position in the phylogeny of seed plants and apparently represent a transition between angiosperms and other gymnosperms(Ran et al.,2018).Modern gnetophytes consist of only three families:Ephedraceae,Gnetaceae,and Welwitschiaceae,and each family contains only one ***(Ephedra L.)are the earliest diverging group of Gnetales,with a total of 70 extant species,and usually occur in cold and arid places in Asia,Europe,northern Africa,western North America and South America(Price,1996;Yang et al.,2017b).

关键词： phylogeny occupy Cretaceous

Analysis of phase preservation and interferometric offset test in sparse SAR imaging

维普期刊数据库

同方期刊数据库评论

在线全文

学校读者我要写书评

暂无评论

Science China(Information Sciences) 2024年第2期67卷 219-231页

作者： Zhongqiu XU Bingchen zhang Guangzuo LI Xueli ZHAN Yanfei bao Yirong WU Key Laboratory of Spatial Information Processing and Application System Technology Chinese Academy of Sciences Aerospace Information Research Institute Chinese Academy of Sciences School of Electronic Electrical and Communication EngineeringUniversity of Chinese Academy of Sciences PLA Academy of Military Sciences

Sparse synthetic aperture radar(SAR) imaging has emerged as a reliable microwave imaging scheme in the recent decade and excels in down-sampling reconstruction and full-sampling performance improvements such as noise, sidelobe, speckle, and ambiguity suppression. To utilize complex image products of sparse reconstruction for improvement in polarimetric, interferometric, and tomographic SAR imaging, it is necessary to evaluate the phase preservation of sparse SAR imaging. In this study, we first introduce the general alternating direction method of multipliers(ADMM) as the universal framework for sparse reconstruction algorithms and adopt chirp scaling algorithm(CSA)-based azimuth-range decouple operators to avoid expensive data storage and processing. Further, we theoretically analyze the phase preservation of the sparse reconstruction algorithm through a comparison with the reconstruction results of CSA. Finally,we conduct the interferometric offset test on the sparse reconstruction results of simulated and real Gaofen-3(GF-3) SAR data, demonstrating the phase-preserving ability of sparse methods.

关键词： sparse SAR imaging phase preservation interferometric offset test general ADMM azimuth-range decouple