检索结果-南通市图书馆

Numerical investigation on compressible flow around a cylinder in proximity to the heated wall

在线全文

学校读者我要写书评

暂无评论

Journal of Hydrodynamics 2024年第3期36卷 519-533页

作者： Yu-lu Liu Jun-wang Qu Yi-zhou Tao yong-guang Lyu Xiang Qiu Shanghai Institute of Technology School of ScienceShanghai201418China Shanghai Key Laboratory of Mechanics in Energy Engineering Shanghai Institute of Applied Mathematics and MechanicsSchool of Mechanics and Engineering ScienceShanghai UniversityShanghai200072China

In this study,direct numerical simulations were conducted to investigate the compressible flow around a circular cylinder near a heated wall at a Reynolds number(Re)of 500 and a Mach number(Ma)of *** heating ratio T^(*)ranging from 1.0 to 1.6 represents the different situations of a heated wall,whereas the gap ratio ranges from 0.3 to *** study analyzed the impact of heating effect and wall proximity on flow characteristics and aerodynamic *** results indicated that the stability of the flow was enhanced as the gap ratio decreased or the heating ratio *** the calculation of enstrophy,it was found that the strength of shedding vortices weakens with a decrease in gap ratio or an increase in heating ***,the mean drag coefficient decreases as the heating ratio increases or the gap ratio *** contrast,the mean lift coefficient initially decreases and then increases as the gap ratio ***,the drag reduction mechanism was analyzed by examining the pressure distribution on the surface of the cylinder.

关键词： Compressible flow wall proximity heating effect stability enstrophy

Exploring charge and spin fluctuations in infinite-layer cuprate SrCuO_(2)from a phonon perspective

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

Science China(Physics,Mechanics & Astronomy) 2024年第8期67卷 159-167页

作者： Xin Du Pei-Han Sun Ben-Chao Gong Jian-Feng Zhang zhong-Yi lu Kai Liu Department of Physics and Beijing Key Laboratory of Opto-electronic Functional Materials&Micro-nano Devices Renmin University of ChinaBeijing 100872China Department of Physics School of ScienceJiangsu University of Science and TechnologyZhenjiang 212100China Institute of Physics Chinese Academy of SciencesBeijing 100190China Key Laboratory of Quantum State Construction and Manipulation(Ministry of Education) Renmin University of ChinaBeijing 100872China

The infinite-layer cuprate ACu O_(2)(A=Ca,Sr,Ba)possesses the simplest crystal structure among numerous cuprate superconductors and can serve as a prototypical system to explore the unconventional *** on the first-principles electronic structure calculations,we have studied the electronic and magnetic properties of the infinite-layer cuprate SrCuO_(2)from a phonon *** find that interesting fluctuations of charges,electrical dipoles,and local magnetic moments can be induced by the atomic displacements of phonon modes in SrCuO_(2)upon the hole *** all optical phonon modes of SrCuO_(2)in the antiferromagnetic Néel state,only the A_(1g)mode that involves the full-breathing O vibrations along the Cu-O bonds can cause significant fluctuations of local magnetic moments on O atoms and dramatic charge redistributions between Cu and O ***,due to the atomic displacements of the A_(1g)mode,both the charge fluctuations on Cu and the electrical dipoles on O show a dome-like evolution with increasing hole doping,quite similar to the experimentally observed behavior of the superconducting T_(c);in comparison,the fluctuations of local magnetic moments on O display a monotonic enhancement along with the hole *** analyses indicate that around the optimal doping,there exists a large softening in the frequency of the A_(1g)phonon mode and a van Hove singularity in the electronic structure close to the Fermi level,suggesting potential electron-phonon *** work reveals the important role of the full-breathing O phonon mode playing in the infinite-layer SrCuO_(2),which may provide new insights in understanding the cuprate superconductivity.

关键词： first-principles calculations cuprate superconductors phonon charge and spin fluctuations

Cobalt-based heterogeneous catalysts for photocatalytic carbon dioxide reduction

在线全文

学校读者我要写书评

暂无评论

Tungsten 2024年第2期6卷 410-421页

作者： Hong Yuan Jian-Hua Mei Yun-Nan Gong Di-Chang zhong Tong-Bu lu MOE International Joint Laboratory of Materials Microstructure Institute for New Energy Materials and Low Carbon TechnologiesSchool of Materials Science and EngineeringTianjin University of TechnologyTianjin 300384China

Solar light-driven CO_(2)reduction to high value-added chemicals has considered as an outstanding way to solve energy crisis and climate ***,various photocatalysts have been developed to achieve this *** them,cobaltbased heterogeneous catalysts have attracted great interest because of their promising performance,product selectivity and ***,we systematically summarize the research progress of various cobalt-based heterogeneous catalysts for the photoreduction of CO_(2),such as single-atom cobalt,and cobalt-based oxides,nitrides,sulfi des,phosphides,metal-organic frameworks and covalent-organic ***,the advantages and structure-activity relationship of these catalysts in photocatalytic CO_(2)reduction reaction are ***,the challenges and prospects for constructing cobaltbased heterogeneous catalysts with high effi ciency are highlighted.

关键词： Cobalt Heterogeneous catalysts CO_(2)reduction Photocatalysis

High-Precision Flow Numerical Simulation and Productivity Evaluation of Shale Oil Considering Stress Sensitivity

在线全文

学校读者我要写书评

暂无评论

Fluid Dynamics & Materials Processing 2024年第10期20卷 2281-2300页

作者： Mingjing lu Qin Qian Anhai zhong Feng Yang Wenjun He Min Li Petroleum Engineering Technology Research Institute of Shengli Oilfield SINOPECDongying257000China Postdoctoral Scientific Research Working Station of Shengli Oilfield SINOPECDongying257000China

Continental shale oil reservoirs,characterized by numerous bedding planes and micro-nano scale pores,feature significantly higher stress sensitivity compared to other types of ***,research on suitable stress sensitivity characterization models is still *** this study,three commonly used stress sensitivity models for shale oil reservoirs were considered,and experiments on representative core samples were *** fitting and comparing the data,the“exponential model”was identified as a characterization model that accurately represents stress sensitivity in continental shale oil *** validate the accuracy of the model,a two-phase seepage mathematical model for shale oil reservoirs coupled with the exponential model was *** model was discretely solved using the finite volume method,and its accuracy was verified through the commercial simulator *** study evaluated the productivity of a typical horizontal well under different engineering,geological,and fracture *** results indicate that considering stress sensitivity leads to a 13.57%reduction in production for the same matrix ***,as the fracture half-length and the number of fractures increase,and the bottomhole flowing pressure decreases,the reservoir stress sensitivity becomes higher.

关键词： Shale oil horizontal wells Embedded Discrete Fracture Model(EDFM) stress sensitivity numerical simulation sensitivity analysis

Structural transformation from Waugh-type to Keggin-type polyoxomolybdate-based crystalline material for photo/electrocatalysis

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

Rare Metals 2024年第5期43卷 2241-2250页

作者： Pei-Sen Wang Zi-Tong Wang Ya-Ya Tan Peng Chen Xue-Cheng Zhang lu-Nan Zhang yong-Ge Wei lu-Bin Ni School of Chemistry and Chemical Engineering Yangzhou UniversityYangzhou 225002China Key Lab of Organic Optoelectronics and Molecular Engineering of Ministry of Education Department of ChemistryTsinghua UniversityBeijing 100084China State Key Laboratory of Natural and Biomimetic Drugs Peking UniversityBeijing100191China

An inorganicDorganic hybrid crystalline material(SiMo_(12)O_(40))[Cu(2,2'-bipy)_(2)]_(2)·2H_(2)O(Complex 1,2,2'-bipy=2,2'-bipyridine)was synthesized for the first time by using 2,2'-bipy and transition metal copper to convert Waugh-type polyoxometalate[MnMo_(9)O_(3)_(2)]_(6-)into a Keggin polyoxometalate structure[SiMo_(12)O_(40)]^(4-)under hydrothermal conditions in glass *** crystal tests and a series of characterizations were carried out on Complex *** structure of Complex 1 is composed of[SiMo_(12)O_(40)]^(4-)and[Cu^(Ⅱ)(2,2'-bipy)_(2)]^(2+).The five-coordinated Cu is connected to two 2,2'-bipy through CuDN bonds,forming an approximately square ***,Complex 1 exhibited good photocatalytic performance for methylene blue degradation and electrocatalytic nitrite reduction properties simultaneously.

关键词： Polyoxometalates Inorganic-organic hybrid materials Photocatalytic Electrocatalytic

Multi-scale persistent spatiotemporal transformer for long-term urban traffic flow prediction

在线全文

学校读者我要写书评

暂无评论

Journal of Electronic Science and Technology 2024年第1期22卷 53-69页

作者： Jia-Jun zhong yong Ma Xin-Zheng Niu Philippe Fournier-Viger Bing Wang Zu-kuan Wei School of Computer Science and Engineering University of Electronic Science and Technology of ChinaChengdu611731China College of Computer Science&Software Engineering Shenzhen UniversityShenzhen518060China School of Computer Science Southwest Petroleum UniversityChengdu610500China

Long-term urban traffic flow prediction is an important task in the field of intelligent transportation,as it can help optimize traffic management and improve travel *** improve prediction accuracy,a crucial issue is how to model spatiotemporal dependency in urban traffic *** recent years,many studies have adopted spatiotemporal neural networks to extract key information from traffic ***,most models ignore the semantic spatial similarity between long-distance areas when mining spatial *** also ignore the impact of predicted time steps on the next unpredicted time step for making long-term ***,these models lack a comprehensive data embedding process to represent complex spatiotemporal *** paper proposes a multi-scale persistent spatiotemporal transformer(MSPSTT)model to perform accurate long-term traffic flow prediction in *** adopts an encoder-decoder structure and incorporates temporal,periodic,and spatial features to fully embed urban traffic data to address these *** model consists of a spatiotemporal encoder and a spatiotemporal decoder,which rely on temporal,geospatial,and semantic space multi-head attention modules to dynamically extract temporal,geospatial,and semantic *** spatiotemporal decoder combines the context information provided by the encoder,integrates the predicted time step information,and is iteratively updated to learn the correlation between different time steps in the broader time range to improve the model’s accuracy for long-term *** on four public transportation datasets demonstrate that MSPSTT outperforms the existing models by up to 9.5%on three common metrics.

关键词： Graph neural network Multi-head attention mechanism Spatio-temporal dependency Traffic flow prediction

Collision-avoidance strategy for a spinning electrodynamic tether system

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

Astrodynamics 2024年第2期8卷 247-259页

作者： Linxiao Li Aijun Li Hongshi lu Changqing Wang Yuriy Mikhailovich Zabolotnov yong Guo School of Automation Northwestern Polytechnical UniversityXi’an 710129China Institute of IT and Cybernatics Samara National Research UniversitySamara 443086Russia

Spinning electrodynamic tether systems(SEDTs)have promising potential for the active removal of space debris,the construction of observation platforms,and the formation of artificial ***,owing to the survivability problem of long tethers,designing collision-avoidance strategies for SEDTs with space debris is an urgent *** study focuses on the design of collision-avoidance strategies for SEDTs with an electrodynamic force(Ampere force).The relative distance between the debris and the SEDT is first derived,and then two collision-avoidance strategies are proposed according to the two different *** debris collides closer to a lighter subsatellite,a stationary avoidance strategy is proposed to change the spatial position of the subsatellite by adjusting only the angular motion of the tether,which maintains the original orbit of the *** debris collides closer to a heavier main spacecraft,a comprehensive avoidance strategy is proposed to change the spatial position of the SEDT by slightly modifying the orbital height and changing the tether angular motion *** numerical results illustrate that the proposed strategies promptly avoid potential collisions of an SEDT with space debris without significant changes in the orbital parameters of the SEDT.

关键词： spinning electrodynamic tether systems(SEDTs) collision analysis collision avoidance

Exceptional catalytic effect of novel rGO-supported Ni-Nb nanocomposite on the hydrogen storage properties of MgH_(2)

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

Journal of Materials Science & Technology 2024年第5期172卷 83-93页

作者： Samuel Guemou Liuting Zhang Shuai Li Yiqun Jiang Tao zhong Zichuan lu Ren Zhou Fuying Wu Qian Li School of Energy and Power Instrumental Analysis CenterJiangsu University of Science and TechnologyZhenjiang 212003China National Engineering Research Center for Magnesium Alloys&National Key Laboratory of Advanced Casting Technologies&College of Materials Science and Engineering Chongqing UniversityChongqing 400044China Chongqing Institute of New Energy Storage Materials and Equipment Chongqing 401135China Max Planck Institute for Iron Research Düsseldorf 40237Germany

The design of an excellent active catalyst to improve the sluggish kinetic and thermodynamic properties of magnesium hydride(MgH_(2))remains a great challenge to achieve its practical *** this study,a novel Ni-Nb/rGO nanocomposite catalyst was successfully prepared by one-spot hydrothermal and sub-sequent calcination *** novel Ni-Nb/rGO nanocomposite exhibits an exceptional catalytic effect on improving MgH_(2) sorption ***,the onset desorption temperature of MgH_(2)+10 wt%Ni-Nb/rGO composite is reduced to 198℃,much lower than that of undoped MgH_(2)(330℃).In-terestingly,the composite can release 5.0,5.9,and 6.0 wt%H_(2) within 10 min at 245,260,and 275℃,***,the dehydrogenated MgH_(2)+10 wt%Ni-Nb/rGO composite starts to absorb hydrogen even at room temperature with approximate 2.75 wt%H_(2) uptake at 75℃under 3 MPa H_(2) pressure within 30 min and exhibits excellent stability by maintaining 6.0 wt%hydrogen content after 20 cycles at 300℃.Chou’s model suggests that the de/hydrogenation kinetics of Ni-Nb/rGO-modified MgH_(2) switches from surface penetration model to diffusion model at lower ***,the ac-tivation energies(E a)for the de/hydrogenation of MgH_(2)+10 wt%Ni-Nb/rGO are reduced to 57.8 kJ/mol and 33.9 kJ/mol,which are significantly lower than those of undoped MgH_(2).The work demonstrates that the addition of a novel ternary Ni-Nb/rGO catalyst is an effective strategy to not only boost the sorption kinetics of MgH_(2) but also maintain its cycling property.

关键词： Hydrogen storage materials Magnesium hydride Ni-Nb/rGO Kinetic analysis Catalytic mechanism

Review on regulation of MnS in non-qquenched and tempered steel

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

Journal of Iron and Steel Research International 2024年第4期31卷 779-789页

作者： Guo-xing Qiu Qing Du Feng lu De-jun Miao yong-kun Yang Xiao-ming Li School of Metallurgical Engineering Xi'an University of Architecture and TechnologyXi'an 710055ShaanxiChina Laigang Technique Center Shandong Iron and Steel Group Co.Ltd.Jinan 271104ShandongChina

An overview of the current research status and control methods of MnS in non-quenched and tempered steel was *** a low-melting plastic inclusion,the morphology and distribution of MnS were influenced by various production ***,control of MnS is a systematic problem that must be integrated into the entire production *** on the production process,the factors affecting the morphology and distribution of MnS in steel were *** effects of oxygen activity,manganese,sulfur,and some alloys on MnS inclusion precipitation were summarized,mainly including MnS modification treatment and oxygen-sulfide composite precipitation *** is believed that MnS precipitates during the solidification process of steel,and controlling the solidification cooling rate could effectively regulate the size and morphology of MnS,avoiding the precipitation of ***,by changing the deformation rate,deformation amount,deformation temperature during the hot deformation process,and heating time and temperature during heat treatment,the distribution and morphology of MnS could be *** the fine control of the above process parameters,the number of II-MnS in steel could be effectively reduced,and their morphology could be improved,thereby enhancing the performance of non-quenched and tempered steel and promoting its wider ***,applying laboratory research results to industrial production is an important direction for future research efforts in this field.

关键词： MnS Non-quenched and tempered steel Control technology Process parameter Morphology Distribution