检索结果-南通市图书馆

Journal of Systems Engineering and Electronics 2023年第3期34卷 804-814页

作者： CAO Hui DUAN Fuhai DUAN yu’nan School of Mechanical Engineering Dalian University of TechnologyDalian 116024China

The reliability-based selective maintenance(RSM)decision problem of systems with components that have multiple dependent performance characteristics(PCs)reflecting degradation states is addressed in this paper.A vine-Copulabased reliability evaluation method is proposed to estimate the reliability of system components with multiple ***,the marginal degradation reliability of each PC is built by using the Wiener stochastic process based on the PC’s degradation *** joint degradation reliability of the component with multiple PCs is established by connecting the marginal reliability of PCs using *** addition,two RSM decision models are developed to ensure the system accomplishes the next *** genetic algorithm(GA)is used to solve the constraint optimization problem of the models.A numerical example illustrates the application of the proposed RSM method.

关键词： D-vine genetic algorithm(GA) reliability-based selective maintenance(RSM) redundant system Wiener stochastic process

Effect of tungsten oxide on ceria nanorods to support copper species as CO oxidation catalysts

在线全文

学校读者我要写书评

暂无评论

Journal of Rare Earths 2021年第1期39卷 43-50,I0002页

作者： yu'nan Li Lin Gan Rui Si Hubei Collaborative Innovation Center for Advanced Organic Chemical Materials Ministry of Education Key Laboratory for the Green Preparation and Application of Functional Materials and School of Material Science and EngineeringHubei UniversityWuhan 430062China Zhangjiang Laboratory Shanghai Synchrotron Radiation FacilityShanghai 201204China

In this work,tungsten oxide with different concentrations(0,0.4 at%,2.0 at%and 3.2 at%)was introduced to the ceria nanorods via a deposition-precipitation(DP)approach,and copper species of ca.10 at%were sequentially anchored onto the modified ceria support by a similar DP *** aim of the study was to investigate the effect of the amount of tungsten oxide(0,0.4 at%,2.0 at%,and 3.2 at%)modifier on the copper-ceria catalysts for CO oxidation reaction and shed light on the structure-activity *** the aids of multiple characterization techniques including N2 adsorption,high-resolution transmission electron microscopy(HRTEM),powder X-ray diffraction(XRD),X-ray absorption fine structure(XAFS),and temperature-programmed reduction by hydrogen(H2-TPR)in combination with the catalytic performance for CO oxidation reaction,it is found that the copper-ceria samples maintain the crystal structure of the fluorite fcc CeO2 phase with the same nanorod-like morphology with the introduction of tungsten oxide,while the textural properties(the surface area,pore volume and pore size)of ceria support and copper-ceria catalysts are changed,and the oxidation states of copper and tungsten are kept the same as Cu2+and W6+before and after the reaction,but the introduction of tungsten oxide(WO3)significantly changes the metal-support interaction(transfer the CuOx clusters to Cu-[Ox]-Ce species),which delivers to impair the catalytic activity of copper-ceria catalysts for CO oxidation reaction.

关键词： Copper catalyst Ceria Tungsten oxide CO oxidation Structure-activity relationship Rare earths

Research on identification model of element logging shale formation based on IPSO-SVM

在线全文

学校读者我要写书评

暂无评论

Petroleum 2022年第2期8卷 185-191页

作者： He Zhang yu'nan Li School of Mechatronic Engineering Southwest Petroleum UniversityChengdu610500China

In the process of shale gas drilling,geo-steering plays an important role in shale gas *** paper analyzes the constituent elements of shale formation,and selects the most suitable constituent elements of shale formation.A particle swarm optimization algorithm based on improved inertia weight and acceleration factor is proposed to optimize the parameters of support vector *** lithology identification model of shale formation is established based on *** to the experimental analysis based on the field historical data,the recognition rate of IPSO-SVM is increased by 17.79%,10.17%and 8.05%,respectively,compared with SVM,GA-PSO and *** terms of running time,the running time of IPSO-SVM is 13.76s and 9.5s shorter than that of GA-PSO,PSO-SVM,*** comparing the experimental results of different models,IPSO-SVM has the advantages of strong robustness,strong reliability,high accuracy and fast convergence *** provides a theoretical basis for precise geo-steering and finding the optimal shale layer.

关键词： Element logging Particle swarm optimization Geo-steering SVM Shale

Adaptive Local Linear Quantile Regression

在线全文

学校读者我要写书评

暂无评论

Acta Mathematicae Applicatae Sinica 2011年第3期27卷 509-516页

作者： yu-nan Su Mao-zai Tian Center for Applied Statistics School of Statistics Remin University of China Beijing 100872 China

In this paper we propose a new method of local linear adaptive smoothing for nonparametric conditional quantile regression. Some theoretical properties of the procedure are investigated. Then we demonstrate the performance of the method on a simulated example and compare it with other methods. The simulation results demonstrate a reasonable performance of our method proposed especially in situations when the underlying image is piecewise linear or can be approximated by such images. Generally speaking, our method outperforms most other existing methods in the sense of the mean square estimation （MSE） and mean absolute estimation （MAE） criteria. The procedure is very stable with respect to increasing noise level and the algorithm can be easily applied to higher dimensional situations.

关键词： quantile regression local linear regression adaptive smoothing automatic choice of window size Robustness

Theoretical elastoplastic analysis for foundations with geosynthetic-encased columns

在线全文

学校读者我要写书评

暂无评论

Journal of Zhejiang University-Science A(Applied Physics & Engineering) 2012年第7期13卷 506-518页

作者： yuan-yu DUAN Yi-ping ZHANG Dave CHAN Ya-nan yu College of Civil Engineering and Architecture Zhejiang UniversityHangzhou 310058China Department of Civil and Environmental Engineering University of AlbertaEdmontonAlbertaCanada

As a new technique in ground improvement, geosynthetic-encased columns (GECs) have promising applications in soft soil foundation. By assuming yielding occurs in the columns while the surrounding soil and the geosynthetic remain elastic, an elastoplastic analytical procedure for foundations improved by GECs is proposed. The radial stresses that the geosynthetic provides and the elastoplastic deformations of the foundation resting on a rigid base are derived. A comparison with finite element analysis shows that the proposed method is effective and can provide a reasonable prediction of a GEC's deformation. Subsequent parametric analysis indicates that higher geosynthetic stiffness leads to better performance of the composite foundation. The optimum length of encasement is related to the load acting on the foundation and the permissible vertical and radial displacements of the column. Moreover, as the dilation angle of the column increases, the settlement decreases, especially under high loading. The influence of the encasement is more significant in soils with smaller elastic modulus.

关键词： Geosynthetic-encased columns (GECs) Equal vertical strain Elastoplastic deformation Analytical procedure

Surface Roughness Simulation During Rotational-Magnetorheological Finishing of Poppet Valve Profiles

在线全文

学校读者我要写书评

暂无评论

nanomanufacturing and Metrology 2022年第3期5卷 259-273页

作者： Manjesh Kumar Manas Das nan yu Department of Mechanical Engineering Indian Institute of TechnologyGuwahati 781039India School of Engineering The University of EdinburghEdinburgh EH89YLUK Department of Mechanical Engineering SRM University APAndhra Pradesh522502India

Surface finishing is essential for various applications in the aerospace *** of the applications is the poppet valve,which is used for leak-proof sealing of high-pressure gases in aerospace gas propulsion *** combustion engine also typically employs a poppet valve as an intake and exhaust ***-finishing a poppet valve is difficult because of its complex narrow *** precise nano-finished poppet valve perfectly fits on its seat and reduces hydrocarbon *** rotational-magnetorheological fluid-based finishing process can be used effectively for these complicated *** polishing agent in this process is magnetorheological fluid,and rheological properties are controlled by a permanent *** article presents the uniform finishing of the poppet valve's narrow ridge profile,which is analyzed through finite element analysis(FEA),wherein the outcomes are uniform shear stress,normal stress,and magnetic flux density distributions along the poppet ridge *** study of forces exerting on abrasive grains and surface roughness simulation is also conducted using FEA *** experiment is subsequently performed to verify the simulation results for poppet profile *** obtained experimental and simulated surface roughness values are *** the finishing process,the maximum percentage improvement of surface roughness is obtained as 93.71%.The rotational-magnetorheological fluid-based finishing process has high accuracy and reliability for specific applications.

关键词： Finite element analysis nano-finishing Nickel-aluminum bronze alloy Poppet valve Magnetorheological fluid Surfaceroughness simulation

Absorption and Fluorescence Emission Spectra of Molecules Containing Azo and/or Oxadiazole Units

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

Chemical Research in Chinese Universities 2013年第4期29卷 776-781页

作者： WANG Chang-sheng yu nan LIU Peng School of Chemistry and Chemical Engineering Liaoning Normal University Dalian 116029 P. R. China

The ground state structures of a series of organic molecules containing azo and/or oxadiazole units were obtained by means of density functional theory B3LYP/6-3IG（d） method. The first singlet excited state structures were optimized by virtue of singlet-excitation configuration interaction CIS/6-31G（d） method. The absorption and fluorescence emission spectra were then evaluated via the time-dependent density functional theory B3LYP and PBE1PBE methods with 6-31 l＋＋G（3df,2p） basis set. The calculation results show that compared with those of their parent molecules A-H, B-H, C-H, D-H, the absorption and emission wavelength values of all the derivatives show red shifts. The derivatives containing both the oxadiazole and methoxyl units are good candidates for longer absorption wavelength materials. The effects of azo, oxadiazole, and methoxyl units on the absorption and emission wavelength were discussed.

关键词： Azo Azobenzene Oxadiazole Absorption spectrum Fluorescence emission spectrum Excited state

Vesicular Li3V2(PO4)3/C hollow mesoporous microspheres as an efficient cathode material for lithium-ion 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 2019年第8期12卷 1937-1942页

作者： Hongxia Sun Haoran Du Mengkang yu Kuangfu Huang nan yu Baoyou Geng College of Chemistry and Materials Science Anhui Key Laboratory of Functional Molecular SolidsMinistry of EducationThe Key Laboratory oj Electrochemical Clean Energy of Anhui Higher Education InstitutesAnhui Normal UniversityNO. 189 South Jiuhua RoadWuhu 241002China

Vesicular lithium vanadium phosphate/carbon hollow mesoporous microspheres were fabricated using a facile polyvinylpyrrolidone-assisted aerosol-spray-assisted method and subsequent heat-treatment. While changing the content of polyvinylpyrrolidone, we found that carbon content was adjustable on the surface of lithium vanadium phosphate. By optimizing the carbon content among the composites, the electrochemical performance can be enhanced significantly. The results of electrochemical performance tests suggested that the samples exhibited good cycle performance and high discharge capability in the voltages between 3.0-4.8 V. The observed excellent electrochemical performances could be attributed to the proper content of carbon coating and the vesicular hollow mesoporous microsphere structure, increasing the transmission rate of lithium ions and reducing the structural change during charging and discharging effectively.

关键词： U3V2(PO4)3 aerosol-spray-assisted approach polyvinylpyrrolidone vesicular hollow microsphere electrochemical properties

Reproductive cycle of Ophiopholis mirabilis (Echinodermata: Ophiuroidea) in Zhangzi Island area, northern Yellow Sea

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 Oceanology and Limnology 2021年第1期39卷 173-184页

作者： nan yu Song SUN Guangtao ZHANG Fang ZHANG CAS Key Laboratory of Marine Ecology and Environmental Sciences Institute of OceanologyChinese Academy of SciencesQingdao 266071China Laboratory for Marine Ecology and Environmental Science Qingdao National Laboratory for Marine Science and TechnologyQingdao 266237China Center for Ocean Mega-Science Chinese Academy of SciencesQingdao 266071China University of Chinese Academy of Sciences Beijing 100049China Jiaozhou Bay Marine Ecosystem Research Station Chinese Academy of SciencesQingdao 266071China

Ophiopholis mirabilis is a common species with a high population density on the western coasts of the northern Pacifi c *** number of *** has been increasing recently in the scallop aquaculture zone(the Zhangzi Island area,northern Yellow Sea)in *** explore the mechanism of its population variation,the reproductive cycle of *** was investigated in this area(39°04′N;122°51′E)from February 2017 through January 2018 and determined by the monthly gonad index(GI),histological examinations of the gonads and the oocyte size-frequency *** had a clear annual reproductive cycle that was synchronous between males and *** temperature and food availability played important roles in *** *** GI value was less reliable for determining reproductive activity in *** because the nutritive tissues within the gonads may be utilized to synthesize gametes,leading to a decrease in GI during *** histological results also show that abundant nutritive phagocytes were present in the gonads of ***,which,together with the germ cells,aff ected the weight of the *** addition,the mature oocytes of *** were relatively small(75–150μm),indicating that the larval development was *** study provided insights into the reproductive patterns and biology of *** and is an essential basis for the quantity control of this species in aquaculture areas.

关键词： reproductive biology Ophiuroidea the northern Pacifi c Ocean Ophiopholis mirabilis

Radiomics-clinical nomogram for response to chemotherapy in synchronous liver metastasis of colorectal cancer:Good,but not good enough

在线全文

学校读者我要写书评

暂无评论

World Journal of Gastroenterology 2022年第9期28卷 973-975页

作者： Han Yan Tu-nan yu Department of Colorectal Surgery Sir Run Run Shaw HospitalSchool of MedicineZhejiang UniversityHangzhou 310016Zhejiang ProvinceChina Department of General Surgery Sir Run Run Shaw HospitalSchool of MedicineZhejiang UniversityHangzhou 310016Zhejiang ProvinceChina

There remains a persistent unmet need to detect the disease nonresponse(nonDR)subgroup before adjuvant therapy in synchronous liver metastasis patients with colorectal ***’s radiomics-clinical nomogram shows potential for the early detection of nonDR subgroups,but it is not good enough owing to at least three limitaions,which we address in this letter to the ***,the study did not explore RAS/BRAF mutations,HER2 amplifications,*** complement the current ***,the nomogram was not validated in left-and rightsided tumors ***,the most critical factor for determining the success of adjuvant therapy should be resectability rather than tumor size shrinkage,which was used in the study.

关键词： Synchronous liver metastasis Colorectal cancer Radiomics