检索结果-南通市图书馆

Surface Nanocrystallization (SNC) of Metallic Materials-Presentation of the Concept behind a New Approach

在线全文

学校读者我要写书评

暂无评论

journal of Materials Science & technology 1999年第3期15卷 193-197页

作者： lu, K lu, j Chinese Acad Sci Met Res Inst State Key Lab RSA Shenyang 110015 Peoples R China Univ technol troyes LASMIS F-10000 Troyes France

In this paper, a concept of surface nanocrystallization (SNC) of metallic materials is introduced. three types of SNC processes are classified. Different SNC mechanisms and possible techniques for SNC are discussed with emphasis on mechanically induced surface self-nanocrystallization. Further development and prospects are addressed with respect to the properties and behaviors of the materials with a nanocrystalline surface. Enhancement of the behavior of the engineering materials by means of the SNC technology and its industrial application possibilities are analyzed.

关键词： SNC of Metallic Materials-Presentation of the Concept behind a New Approach Figure

负责任的社会科学数据治理的内涵、特征与层次

在线全文

学校读者我要写书评

暂无评论

现代情报 2025年第1期45卷 124-134页

作者：王英卢国强湖北大学历史文化学院湖北武汉430062 吉林大学商学与管理学院吉林长春130012

[目的/意义]“十四五”国家哲学社会科学发展规划的背景下,负责任的数据治理成为促进社会科学数据开放共享、推进社会科学研究与创新的重要驱动力,亟须探索负责任的社会科学数据治理的基础理论。[方法/过程]运用主题分析法,探寻负责任... 详细信息

[目的/意义]“十四五”国家哲学社会科学发展规划的背景下,负责任的数据治理成为促进社会科学数据开放共享、推进社会科学研究与创新的重要驱动力,亟须探索负责任的社会科学数据治理的基础理论。[方法/过程]运用主题分析法,探寻负责任的数据治理的概念要素及维度,按照国际标准ISO704:2009的概念关系,结合社会科学数据的特性,阐释负责任的社会科学数据治理的内涵及其与相关概念的关系、特征、层次与内容,旨在构建一个较为全面且系统的概念体系。[结果/结论]负责任的社会科学数据治理是多元主体在现有的数据治理环境之下,运用相应的治理机制和手段,将负责任的研究与创新的理念和原则融入社会科学数据全生命周期,以确保所有涉及社会科学数据的流程和成果的责任性的过程,具有责任性、反思性、前瞻性、开放性和工具性特征,可划分为战略层、数据层和活动层。

关键词：社会科学数据负责任的数据治理数据治理

A corrected particle method with high-order taylor expansion for solving the viscoelastic fluid flow

维普期刊数据库评论

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

Acta Mechanica Sinica 2017年第1期33卷 20-39页

作者： t. jiang j. L. Ren W. G. lu B. Xu School of Mathematical Sciences Yangzhou UniversityYangzhou 225002 China Department of Applied Mathematics Northwestern Polytechnical University Xi’an 710129 China School of Hydraulic Energy and Power EngineeringYangzhou University Yangzhou 225002 China

In this paper, a corrected particle method based on the smoothed particle hydrodynamics (SPH) method with high-order taylor expansion (CSPH-Ht) for solving the viscoelastic flow is proposed and investigated. the validity and merits of the CSPH-Ht method are first tested by solving the nonlinear high order Kuramoto-Sivishinsky equation and simulating the drop stretching, respectively. then the flow behaviors behind two stationary tangential cylinders of polymer melt, which have been received little attention, are investigated by the CSPH-Ht method. Finally, the CSPH-Ht method is extended to the simulation of the filling process of the viscoelastic fluid. the numerical results show that the CSPH-Ht method possesses higher accuracy and stability than other corrected SPH methods and is more reliable than other corrected SPH methods.

关键词： Smoothed particle hydrodynamics High-order taylor expansion Viscoelastic fluid Extended pom-pom model

学科类培训机构缩减对学生在校时长的影响:基于“双减”政策的评估研究

在线全文

学校读者我要写书评

暂无评论

华东师范大学学报（教育科学版） 2025年第1期43卷 37-48页

作者：陆伟魏易杭州师范大学经亨颐教育学院杭州311121 北京大学中国教育财政科学研究所北京100871

对校外培训机构的治理整顿是“双减”改革的重要内容之一。本文使用大众点评网学科类培训机构的商铺信息,结合高德地图地理编码和搜索POI应用接口,以及全国中小学教育信息化使用情况调查等数据,实证检验了学科类校外培训机构缩减对学生... 详细信息

对校外培训机构的治理整顿是“双减”改革的重要内容之一。本文使用大众点评网学科类培训机构的商铺信息,结合高德地图地理编码和搜索POI应用接口,以及全国中小学教育信息化使用情况调查等数据,实证检验了学科类校外培训机构缩减对学生在校时长的影响。研究发现:(1)“双减”期间,全国层面学科类培训机构的缩减比例约为88%。(2)学校周边学科类培训机构的缩减程度越高,学生每天待在学校内的时间也越多,也即校内教育与校外教育出现一定程度的替代,且这种替代效应在弱势阶层群体中更为明显;在北上广深四个一线城市不明显,但在其他众多二三线城市可以观察到。(3)学校周边学科类培训机构的缩减程度越高,学生在学校内完成课后作业的概率也越高,而在校外辅导班完成课后作业的概率则越低;但培训机构缩减对学生完成课后作业的总时长没有影响。

关键词： “双减” 学科类培训机构校外培训在校时长

Structural subgrid-scale modeling for large-eddy simulation: A review

在线全文

学校读者我要写书评

暂无评论

Acta Mechanica Sinica 2016年第4期32卷 567-578页

作者： Hao lu Christopher j.Rutland School of Energy and Power Engineering Huazhong University of Science and Technology Engine Research Center Mechanical EngineeringUniversity of Wisconsin-Madison

Accurately modeling nonlinear interactions in turbulence is one of the key challenges for large-eddy simulation（LES） of turbulence. In this article, we review recent studies on structural subgrid scale modeling, focusing on evaluating how well these models predict the effects of small scales. the article discusses a priori and a posteriori test results. Other nonlinear models are briefly discussed, and future prospects are noted.

关键词： turbulence turbulent viscosity priori dissipation posteriori scalar A review scales Reynolds

Mechanism of soft x-ray continuum radiation from low-energy pinch discharges of hydrogen and ultra-low field ignition of solid fuels

在线全文

学校读者我要写书评

暂无评论

Plasma Science and technology 2017年第9期19卷 7-34页

作者： R MILLS j LOtOSKI Y lu Brilliant Light Power Inc.493 Old Trenton RoadCranburyNJ 08512United States of America

EUV continuum radiation（10–30 nm） arising only from very low energy pulsed pinch gas discharges comprising some hydrogen was first observed at Black Light Power, Inc. and reproduced at the Harvard Center for Astrophysics（Cf A）. the source was determined to be due to the transition of H to the lower-energy hydrogen or hydrino state H（1/4） whose emission matches that observed wherein alternative sources were eliminated. the identity of the catalyst that accepts 3 · 27.2 eV from the H to cause the H to H（1/4） transition was determined to HOH versus 3H. the mechanism was elucidated using different oxide-coated electrodes that were selective in forming HOH versus plasma forming metal atoms as well as from the intensity profile that was a mismatch for the multi-body reaction required during 3H catalysis. the HOH catalyst was further shown to give EUV radiation of the same nature by igniting a solid fuel comprising a source of H and HOH catalyst by passing a low voltage, high current through the fuel to produce explosive plasma. No chemical reaction can release such high-energy light. No high field existed to form highly ionized ions that could give radiation in this EUV region that persisted even without power input. this plasma source serves as strong evidence for the existence of the transition of H to hydrino H（1/4） by HOH as the catalyst and a corresponding new power source wherein initial extraordinarily brilliant light-emitting prototypes are already producing photovoltaic generated electrical power. the hydrino product of a catalyst reaction of atomic hydrogen was analyzed by multiple spectroscopic techniques. Moreover, the m H catalyst was identified to be active in astronomical sources such as the Sun, stars and interstellar medium wherein the characteristics of hydrino match those of the dark matter of the Universe.

关键词： ignition continuum brilliant catalysis matches elucidated reproduced spectroscopic figure helium

Gamma-Ray Bursts: Afterglows and Central Engines

在线全文

学校读者我要写书评

暂无评论

Chinese journal of Astronomy and Astrophysics 2001年第1期1卷 1-20页

作者： K.S.Cheng t.lu DepartmentofPhysics UniversityofHongKongPokfulamRoadHongKong DepartmentofAstronomy NanjingUniversit

Gamma-ray bursts (GRBs) are the most intense transient gamma-ray events in the sky; this, together with the strong evidence (the isotropic and inhomogeneous distribution of GRBs detected by BAStE) that they are located at cosmological distances, makes them the most energetic events ever known. For example, the observed radiation energies of some GRBs are equivalent to the total convertion into radiation of the mass energy of more than one solar mass. this is thousand times stronger than the energy of a supernova explosion. Some unconventional energy mechanism and extremely high conversion efficiency for these mysterious events are required. the discovery of host galaxies and association with supernovae at cosmological distances by the recently launched satellite of BeppoSAX and ground based radio and optical telescopes in GRB afterglow provides further support to the cosmological origin of GRBs and put strong constraints on their central engine. It is the aim of this article to review the possible central engines, energy mechanisms, dynamical and spectral evolution of GRBs, especially focusing on the afterglows in multi-wavebands.

关键词： gamma-rays: bursts - shock waves - ISM: jets and outflows- radiation mechanisms: non-thermal

A Hyper-ellipsoid Model for Metallurgical Process Modelling by Genetic Algorithm

在线全文

学校读者我要写书评

暂无评论

journal of Materials Science & technology 1998年第6期14卷 567-568页

作者： Li, jF Li, CH Chen, NY lu, t Chinese Acad Sci Shanghai Inst Met Shanghai 200050 Peoples R China Univ SW Louisiana Lafayette LA 70504 USA

A hyper-ellipsoid model, using genetic algorithm as method of computation, has been proposed to be used in certain metallurgical processes. It is especially suitable for the modelling of the metallurgical processes wi... 详细信息

关键词： Metallurgy

Acoustic Emission Monitoring and Microscopic Investigation of Cracks in ERCuNi Cladding

在线全文

学校读者我要写书评

暂无评论

journal of Materials Science & technology 2003年第3期19卷 201-205页

作者： S.P.lu O.Y.Kwon K.j.Lee t.B.Kim Department of Mechanical Engineering Inha University253 Yonghyun-dongInchon 402-751KoreaDepartment of Mechanical EngineeringInha University253 Yonghyun-dongInchon 402-751KoreaDepartment of Mechanical EngineeringInha University253 Yonghyun-dongInchon 402-751KoreaDepartment of Mechanical EngineeringInha University253 Yonghyun-dongInchon 402-751Korea

A corrosion resistant CuNi cladding was deposited on SM45C (equivalent to AISI1045) substrate by DC inverse arc welding. During the welding process, a three channel acoustic emission (AE) monitoring system was applied to detect the crack signals generating from both the cladding process and after cladding. Characteristics of the welding crack signal and noise signal had been analyzed systematically. Based on the record time of the signal, the solidification crack and delayed crack were distinguished. By two-dimensional AE source location, the crack position was located, and then investigated by scanning electron microscopy (SEM). Results showed that the AE system could detect the welding crack with high sensitivity and the two-dimensional source location could accurately determine the crack position. Microstructures of the cladding and heat affected zone (HAZ) were examined. Dendrites in the cladding and coarse grains in the HAZ were found.

关键词： Cladding Acoustic emission monitoring Crack CuNi alloy