检索结果-南通市图书馆

Modal Parameter Identification Method of Jacket Platform Structure Based on AFDD and Optimized FBFFT

在线全文

学校读者我要写书评

暂无评论

China Ocean Engineering 2023年第3期37卷 393-407页

作者： LENG jian-cheng ma Jin-yong FAN Zong-heng QIAN Wan-dong feng Hui-yu School of Mechanical Science and Engineering Northeast Petroleum UniversityDaqing 163318China

Offshore platforms are susceptible to structural damage due to prolonged exposure to random loads,such as wind,waves,and *** is particularly true for platforms that have been in service for an extended *** the modal parameters of offshore platforms is crucial for damage diagno sis,as it serves as a prerequisite and foundation for the ***,it holds great significance to prioritize the identification of these *** at the shortcomings of the traditional Fast Bayesian Fast Fourier Transform(FBFFT) method,this paper proposes a modal parameter identification method based on Automatic Frequency Domain Decomposition(AFDD) and optimized *** introducing the AFDD method and Powell optimization algorithm,this method can automatically identify the initial value of natural frequency and solve the objective function efficiently and *** order to verify the feasibility and effectiveness of the proposed method,it is used to identify the modal parameters of the IASC-ASCE benchmark model and the j acket platform structure model,and the Most Probable Value(MPV) of the modal parameters and their respective posterior uncertainties are successfully *** identification results of the IASC-ASCE benc hmark model are compared with the identification re sults of the MODE-ID method,which verifies the effectivene ss and accuracy of the proposed method for identifying modal *** provides a simple and feasible method for quantifying the influence of uncertain factors such as environmental parameters on the identification results,and also provide s a reference for modal parameter identification of other large structures.

关键词： jacket platform uncertain modal parameter identification FBFFT method environmental excitation AFDD method Powell optimization

Recent advances in alloy-based anode materials for potassium ion batteries

在线全文

学校读者我要写书评

暂无评论

Rare Metals 2020年第9期39卷 970-988页

作者： Shi-Han Qi Ji-Wei Deng Wen-Chao Zhang Yue-Zhan feng jian-Min ma State Key Laboratory of High-Performance Complex manufacturing College of Mechanical and Electrical EngineeringCentral South UniversityChangsha 410083China School of Physics and Electronics Hunan UniversityChangsha 410082China Institute for Superconducting and Electronic materials(ISEM) School of MechanicalMaterialsMechatronics&Biomedical EngineeringFaculty of Engineering and Information SciencesUniversity of WollongongWollongongNSW 2500Australia Key Laboratory of materials Processing and Mold(Zhengzhou University) Ministry of EducationZhengzhou UniversityZhengzhou 450002China

Potassium ion batteries(PIBs)are regarded as one of promising low-cost energy storage *** long cycle life and high energy density has been considered as important tasks for developing high-performance *** alloy-based anodes for PIBs have attracted great attentions because of their high theoretical capacity and relatively low operating *** this review,the latest advance in the related alloy-based anodes was ***,the correlations among the morphology and potassium storage performance,phase transition mechanisms,the formation of solid electrolyte interphases and ionic transport kinetics are critically *** is expected that this review will provide meaningful guidance and possible pathways for the developments of alloy-based anodes for PIBs.

关键词： Potassium ion batteries Anode Alloy-based alloys Performance Nanostructures

Modeling study on the flow patterns of gas–liquid flow for fast decarburization during the RH process

在线全文

学校读者我要写书评

暂无评论

International Journal of Minerals,Metallurgy and materials 2018年第2期25卷 153-163页

作者： Yi-hong Li Yan-ping Bao Rui Wang Li-feng ma jian-sheng Liu Collaborative Innovation Centre of Taiyuan Heavy machinery Equipment and School of materials Science and Engineering Taiyuan University of Science and Technology State Key Laboratory of Advanced Metallurgy University of Science and Technology Beijing School of materials Science and Engineering North University of China

A water model and a high-speed video camera were utilized in the 300-t RH equipment to study the effect of steel flow patterns in a vacuum chamber on fast decarburization and a superior flow-pattern map was obtained during the practical RH process. There are three flow patterns with different bubbling characteristics and steel surface states in the vacuum chamber： boiling pattern（BP）, transition pattern（TP）, and wave pattern（WP）. The effect of the liquid-steel level and the residence time of the steel in the chamber on flow patterns and decarburization reaction were investigated, respectively. The liquid-steel level significantly affected the flow-pattern transition from BP to WP, and the residence time and reaction area were crucial to evaluate the whole decarburization process rather than the circulation flow rate and mixing time. A superior flow-pattern map during the practical RH process showed that the steel flow pattern changed from BP to TP quickly, and then remained as TP until the end of decarburization.

关键词： modeling study flow pattern vacuum chamber residence time decarburization RH process

Factors influencing oil recovery by surfactant-polymer flooding in conglomerate reservoirs and its quantitative calculation method

在线全文

学校读者我要写书评

暂无评论

Petroleum Science 2022年第3期19卷 1198-1210页

作者： feng-Qi Tan Chun-Miao ma jian-Hua Qin Xian-Kun Li Wen-Tao Liu College of Earth and Planetary Sciences University of Chinese Academy of SciencesBeijing100049China Key Laboratory Computational Geodynamics Chinese Academy of SciencesBeijing100049China Xinjiang Oilfield Company PetroChinaKaramayXinjiang834000China

This study aims to clarify the factors influencing oil recovery of surfactant-polymer(SP)flooding and to establish a quantitative calculation model of oil recovery during different displacement stages from water flooding to SP *** conglomerate reservoir of the Badaowan Formation in the seventh block of the Karamay Oilfield is selected as the research object to reveal the start-up mechanism of residual oil and determine the controlling factors of oil recovery through SP flooding experiments of natural cores and microetching *** experimental results are used to identify four types of residual oil after water flooding in this conglomerate reservoir with a complex pore structure:oil droplets retained in pore throats by capillary forces,oil cluster trapped at the junction of pores and throats,oil film on the rock surface,isolated oil in dead-ends of flow *** the four types of residual oil identified,the SP solution can enhance oil recovery by enlarging the sweep volume and improving the oil displacement ***,the viscosity-increasing effect of the polymer can effectively reduce the permeability of the displacement liquid phase,change the oil-water mobility ratio,and increase the water ***,the stronger the shear drag force of the SP solution,the more the crude oil in a porous medium is ***,the surfactant can change the rock wettability and reduce the absorption capacity of residual oil by lowering interfacial *** the same time,the emulsification further increases the viscosity of the SP solution,and the residual oil is recovered effectively under the combined effect of the above two *** the four start-up mechanisms of residual oil identified after water flooding,enlarging the sweep volume and improving the oil displacement efficiency are interdependent,but their contribution to enhanced oil recovery are *** SP flooding system primarily enlarges the sweep volume by increasing viscos

关键词： Conglomerate reservoir Water flooding Surfactant-polymer flooding Residual oil type Influencing factor Enhanced oil recovery Computational model

Evolution of Er^(3+) Distribution in the Oxyfluoride Glass Ceramics with Heating

在线全文

学校读者我要写书评

暂无评论

Chinese Journal of Structural Chemistry 2007年第3期26卷 303-308页

作者： ma En CHEN Da-Qin HU Zhong-jian LIU feng HUANG Zi-Xiang BAO feng WANG Yuan-Sheng State Key Laboratory of Structural Chemistry Fujian Institute of Research on theStructure of Matter Chinese Academy of Sciences Fuzhou Fujian 350002 China

The distribution characteristics of Er^3＋ ions doped in the oxyfluoride glass ceramics containing LaF3 nanocrystals heat-treated at 650 ℃ for different durations were investigated. The results of the integral absorption cross-section analysis demonstrated that the partition fraction of Er^3＋ in LaF3 nanocrystals increases with prolonging of heating time, The anomalous phenomena of Er^3＋ emissions in the up-and the down-conversion fluorescence spectra are well explained based on the calculated results.

关键词： oxyfluoride glass ceramics rare earth nanocrystal up-conversion integral absorption cross-section

FLOW OF OLDROYD-B FLUID IN ROTATING CURVED SQUARE DUCTS

在线全文

学校读者我要写书评

暂无评论

Journal of Hydrodynamics 2007年第1期19卷 36-41页

作者： ZHANG Ming-kan SHEN Xin-rong ma jian-feng ZHANG Ben-zhao Institute of Fluid Engineering Zhejiang University Hangzhou 310027 China

The fully developed Oldroyd-B fluid flow through rotating square ducts was numerically studied. The effects of the rotation on secondary flow, axial velocity, and axial normal stress were examined in detail. The results indicated that all of the secondary flow, the axial flow, and the axial normal stress were evidently affected by the rotation. The Taylor-Proudman phenomenon could be observed in the flow. For the secondary flow, the four vortices structure and the six vortices structure were described. Recent studies also showed the effects of rotation on the axial normal stress.

关键词： curved ducts Oldroyd-B fluid rotating axialnormal stress

Strategies for the construction of supramolecular assemblies from poly-NHC ligand precursors

在线全文

学校读者我要写书评

暂无评论

Science China Chemistry 2021年第5期64卷 701-718页

作者： Yang Li jian-Gang Yu Li-Li ma man Li Yuan-Yuan An Ying-feng Han Key Laboratory of Synthetic and Natural Functional Molecule Chemistry FM&EM International Joint LaboratoryCollege of Chemistry and Materials ScienceNorthwest UniversityXi’an 710127China College of Chemical and material Engineering Quzhou UniversityQuzhou 324000China State Key Laboratory of Structural Chemistry Fujian Institute of Research on the Structure of MatterChinese Academy of SciencesFuzhou 350002China

The field of supramolecular assemblies has developed rapidly in the last few decades,thanks in a large part to their diverse *** assemblies have been mostly based on Werner-type coordination motifs in which metal centres are coordinated by nitrogen or oxygen ***,N-heterocyclic carbene(NHC)ligands have been employed as carbon donors not only because of their appealing structures but also due to the extensive applications in catalysis,biomedicine and material science of the resulting *** the last decade,NHC-based supramolecular assemblies have witnessed rapid growth and extensive application in molecular recognition,luminescent materials and *** different topological systems,a diverse selection of poly-NHC precursors and synthetic strategies is crucial to precisely control the synthesis of supramolecular *** synthetic strategies have been developed to synthesise two-dimensional(2D)molecular metallacycles and three-dimensional(3D)metallacages from a wide range of poly-NHC precursors,including a straightforward one-pot strategy,supramolecular transmetalation,stepwise synthesis,an improved one-pot strategy involving self-sorting behaviour of 3D metallacages and a subtle variation strategy of poly-NHC ligand *** review offers a summary of the synthetic strategies applied for the construction of different poly-NHC-based supramolecular assemblies,particularly emphasizes recent progress in the synthesis of large and complex supramolecular assemblies from poly-NHC precursors,and further attention is given to their application in postsynthetic modifications(PSMs),host-guest chemistry,luminescent properties and biomedical applications.

关键词： N-heterocyclic carbene organometallic chemistry supramolecular chemistry synthetic strategies applications

Parameter design for a vibration absorber with time-delayed feedback control

在线全文

学校读者我要写书评

暂无评论

Acta Mechanica Sinica 2019年第3期35卷 624-640页

作者： feng Wang jian Xu School of Aerospace Engineering and Applied Mechanics Tongji UniversityShanghai 200092China

Traditional passive vibration absorbers are effective only when their natural frequencies are close to those of the excitations. To solve this problem, a vibration absorber with time-delayed feedback control is proposed to suppress vibration of the primary system under excitation with changing frequency. Firstly, the mechanical model of the delay coupled system is established. Then, the displacement transfer ratio of the system is obtained. The stability of the system is analyzed since delay may result in destabilization. Next, in order to design the control parameters, the vibration absorption performances of the proposed time-delayed vibration absorber are studied. The vibration absorption region is shown. The results show that time-delayed feedback control is able to change the response of the system. The effective vibration absorption frequency band is adjustable by tuning the control gain and time delay. The effective frequency band can be widened when choosing appropriate control parameters. The vibration absorption performances can be greatly improved by the time-delayed absorber. In addition, the optimum control parameters are obtained. Finally, the experimental prototype is constructed. Several tests with different control parameters are taken. The experimental and analytical results match quite well.

关键词： Vibration absorber Time-delayed feedback control Vibration absorption Experiments Parameter design

Effects of CeO_2 on the XPS valence band spectra of coal under the combustion initialization stage at 400℃

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

International Journal of Minerals,Metallurgy and materials 2013年第4期20卷 338-344页

作者： Cheng-lin Qi jian-liang Zhang Chao ma Gen-sheng feng Zhong-ping Song State Key Laboratory of Advanced Metallurgy University of Science and Technology Beijing Shougang Research Institute of Technology

In order to get the catalytic mechanism of CeO2 on graphite and coal at 400℃, the morphologies of coal, graphite, and CeO2 before and after combustion were analyzed through X-ray photoelectron spectroscopy （XPS）. It is found that the particle size of coal is mostly between 11.727 and 64.79 μm, while the particle size of CeO2 is between 1.937 and 11.79 μm. The agglomeration of coal and CeO2 can be seen by scanning electron microscopy （SEM） after reaction. XPS results show that with the addition of CeO2, the intensity of binding energy gets stronger, but there is no energy peak transition. Comparing the character of coal with and without the addition of CeO2, it can be seen that the C C bond fractures first at 400℃, while the C-H energy-band takes electrons at the same time to be far away from the Fermi level, and the O 2s, O 2p, and C sp hybrid orbitals are all excited. Adding CeO2 can enhance the activity of the whole coal. In addition, through XPS analysis, combined with the oxygen transfer theory and the electron transfer theory, the catalytic mechanism of CeO2 for pulverized coal combustion could be obtained.

关键词： coal combustion cerium oxide valence bands catalysis binding energy X-ray photoelectron spectroscopy pulverized fuel