检索结果-南通市图书馆

Chinese Journal of Aeronautics 2006年第B12期19卷 151-155页

作者： yang fan BI Xiao-fang School of Materials Science and Engineering Beijing University of Aeronautics and Astronautics 100083 Beijing China

The effects of the thickness of MgO and Fe on the electronic structure and magnetic properties of Fe/MgO/Fe magnetic tunnel junction was studied using the first principle method. Two series of models with MgO of different thicknesses： Fe（3）MgO（t）Fe（3）（t-=1,3,5,7） and with Fe of varied thicknesses： Fe（t）MgO（3）Fe（t）（t=3,4,5,6,7） were established. Calculated results show that in all the models the magnetic moment of Fe increases at the Fe/MgO interface and surface as compared with that of the inner layers. The mag- netic moment of each Fe layer was found to be independent of MgO thicknesses, while the spin-polarization of Fe layer at the interface shows a slight change in function of the MgO thicknesses. The tunneling magnetoresistance （TMR） ratio estimated by the Julliere model has the same change tendency as the spin-polarization has, and the largest value is obtained at the MgO thickness of 5 atomic layers. When the Fe thickness increases, the spin-polarization of interface Fe layer follows up an increase with a decrease. The highest TMR value is achieved when the Fe thickness is of 4 atomic layers.

关键词： Fe/MgO/Fe electronic structure tunnel magnetoresistance thicknesses

A Study on Literary Criticism from the Perspective of Ethics--Taking Amy Tan's Works for Example

在线全文

学校读者我要写书评

暂无评论

学术界 2017年第3期 275-282页

作者： yang Yali yang fan Northeast Agricultural University Harbin Heilongjiang 150030 Harbin Institute of Technology Harbin Heilongjiang 150001

Amy Tan is a master of describing the ethical relationship between people, and her novels focus particularly on family ethics. After interpretation of the setting of the ethical knots,the trend of the ethical lines, and the structure of ethics in her novels from the perspective of literary ethics,we find out that every novel has its own characteristics and angle,and they share some commonality too. The analysis of the formation and deconstruction of the ethical knots,the ethical lines and the ethical structure in her novels give us an insight into Amy Tan's ethical philosophy that she wants to convey to readers through her novels,that is,harmonious relationship will ultimately be built as long as people communicate sincerely, regardless of barriers and contradictions. This is not only the ethical ideas the author wants to convey,but also the ethical orientation of her works.

关键词：伦理学作品文学视野伦理关系和谐关系小说道德

High-response n-butanol gas sensor based on ZnO/In_(2)O_(3) heterostructure

在线全文

学校读者我要写书评

暂无评论

Rare Metals 2023年第1期42卷 198-209页

作者： Zhen-Yu Yuan fan yang Hong-Min Zhu fan-Li Meng Medhat Ibrahim College of Information Science and Engineering Northeastern UniversityShenyang110819China Spectroscopy Department National Research CentreGiza12622Egypt

In this study,ZnO/In_(2)O_(3)-heterostructured nanosheets were prepared using a one-step hydrothermal *** effects of ZnO content on the gas-sensing performance were discussed,with ZnO/In_(2)O_(3)-2 exhibiting the highest performance among the prepared *** response of ZnO/In_(2)O_(3)-2 to n-butanol was 302 at 26℃,which was 11.93 times higher than that of pure In_(2)O_(3).Among the eight tested gases,ZnO/In_(2)O_(3)-2 displayed the highest response to ***,the lower detection limit of the ZnO/In_(2)O_(3)nanosheets was reduced from 10×10^(-6)to 0.1×10^(-6)(for pure In_(2)O_(3)nanosheets)toward *** is because the doping of Zn2+increases the number of oxygen vacancies on the sensor surface and allows the formation of an n-n heterostructure between ZnO and In_(2)O_(3),which increases the initial resistance of the sensor.

关键词： High-response N-N heterostructure N-butanol Gas sensor

A Better Semi-online Algorithm for Q3/s_1=s_2≤s_3/C_(min) with the Known Largest Size

在线全文

学校读者我要写书评

暂无评论

Acta Mathematicae Applicatae Sinica 2012年第1期28卷 111-116页

作者： Sheng-yi CAI Qi-fan yang Department of Mathematics Zhejiang UniversityHangzhou 310027China School of Mathematics&Information Science Wenzhou UniversityWenzhou 325035China

This paper investigates the semi-online machine covering problem on three special uniform machines with the known largest size. Denote by sj the speed of each machine, j = 1, 2, 3. Assume 0 〈 s1 = s2 = r 〈 t = s3, and let s = t/r be the speed ratio. An algorithm with competitive ratio max（2, 3s＋6/s＋6 is presented. We also show the lower bound is at least max（2, 38 3s/s＋6）. For s ≤ 6, the algorithm is an optimal algorithm with the competitive ratio 2. Besides, its overall competitive ratio is 3 which matches the overall lower bound. The algorithm and the lower bound in this paper improve the results of Luo and Sun.

关键词： analysis of algorithms scheduling machine covering semi-online competitive ratio

Compressed sensing based channel estimation used in non-sample-spaced multipath channels of OFDM system

在线全文

学校读者我要写书评

暂无评论

The Journal of China Universities of Posts and Telecommunications 2015年第2期22卷 31-37页

作者： Chen Baohao Cui Qimei yang fan National Engineering Laboratory for Mobile Network Security Beijing University of Posts and Telecommunications

By virtue of an increase in spectral efficiency by reducing the transmitted pilot tones, the compressed sensing （CS） has been widely applied to pilot-aided sparse channel estimation in orthogonal frequency division multiplexing （OFDM） systems. The researches usually assume that the channel is strictly sparse and formulate the channel estimation as a standard compressed sensing problem. However, such strictly sparse assumption does not hold true in non-sample-spaced multiple channels. The authors in this article proposed a new method of compressed sensing based channel estimation in which an over-complete dictionary with a finer delay grid is applied to construct a sparse representation of the non-sample-spaced multipath channels. With the proposed, the channel estimation was formulated as the model-based CS problem and a modified model-based compressed sampling matching pursuit （CoSaMP） algorithm was applied to reconstruct the discrete-time channel impulse response （CIR）. Simulation indicates that the new method proposed here outperforms the traditional standard CS-based methods in terms of mean square error （MSE） and bit error rate （BER）.

关键词： channel estimation model-based compressed sensing non-sample-spaced multipath channels

Three-Component Reaction for Construction of Spiro[indoline- 3,7＇-thiazolo[3,2-a]pyridines] and Spiro[benzo[4,5]- thiazolo[3,2-a]pyridine-3,3＇-indolines]

在线全文

学校读者我要写书评

暂无评论

Chinese Journal of Chemistry 2015年第12期33卷 1371-1379页

作者： fan yang Jing Sun Chaoguo Yan College of Chemistry & Chemical Engineering Yangzhou University Yangzhou Jiangsu 225002 China

The three-component reaction of thiazole （benzothiazole）, dialkyl but-2-ynedioate, and isatinylidene malononi- triles in toluene at 110-120 ℃ in a sealed tube afforded a mixture of cis/trans-isomers of functionalized di- astereoisomeric spiro[indoline-3,7＇-thiazolo[3,2-a]pyridines] and spiro[benzo[4,5]thiazolo[3,2-a]pyridine-3,3＇-in- dolines] in good yields. Both cis-isomers and trans-isomers were successfully separated out and fully characterized with spectroscopy and single crystal determination. Under similar conditions, the three-component reaction con- taining 2-（1,3-dioxo-lH-inden-2（3H）-ylidene）malononitrile resulted in spiro[indene-2,7＇-thiazolo[3,2-a]pyridine] derivatives.

关键词： multicomponent reaction spirooxindole thiazole benzothiazole electron-deficient alkyne malononi-trile

WEAK-STRONG UNIQUENESS FOR THREE DIMENSIONAL INCOMPRESSIBLE ACTIVE LIQUID CRYSTALS

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 Mathematica Scientia 2024年第4期44卷 1415-1440页

作者： fan yang Congming LI School of Mathematical Sciences CMA-ShanghaiShanghai Jiao Tong UniversityShanghai 200240China

The hydrodynamics of active liquid crystal models has attracted much attention in recent years due to many applications of these *** this paper,we study the weak-strong uniqueness for the Leray-Hopf type weak solutions to the incompressible active liquid crystals in R^(3).Our results yield that if there exists a strong solution,then it is unique among the Leray-Hopf type weak solutions associated with the same initial data.

关键词： analysis of parabolic and elliptic types weak-strong uniqueness active liquid crystals weak solution energy equality

Behavior of Nb influence on structure and properties of 30Cr13 cast martensitic stainless steel

在线全文

学校读者我要写书评

暂无评论

Journal of Iron and Steel Research International 2019年第5期26卷 462-471页

作者： yang-fan Jin Tuo Zhang Qi-yu Zang Yi-tao yang School of Materials Science and Engineering Shanghai University Shanghai 200444 China

The microstructure, mechanical properties and corrosion resistance of 30Cr13 martensitic stainless steel (MSS) with different Nb contents were investigated by using the optical microscope, scanning electron microscope, X-ray diffractometer, HRC hardness measurement apparatus and tensile testing machine. Nb was found to retard the formation of austenite and promote the precipitation of carbides by calculating. The results showed that the addition of 0.2 wt.% Nb elements could improve the strength and corrosion resistance of 30Cr13 martensitic stainless steels while the reduction in toughness was less because of the inhibited effect on Cr-rich carbides precipitation by Nb addition. Specially, M23C6-type carbides almost disappeared in 0.6Nb-MSS. Moreover, the main existent form of Nb element was NbC and the strong carbide-forming ability of Nb element increased the quantity of carbides with the morphology changing from sphericaltype to chain-type. 0.2Nb-MSS shows excellent strength, adequate toughness and sufficient corrosion resistance for the application.

关键词： Niobium addition Martensitic stainless steel Microstructure Mechanical property Corrosion resistance

Modeling of growth stress gradient effect on the oxidation rate at high temperature

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

Journal of Zhejiang University-Science A(Applied Physics & Engineering) 2010年第10期11卷 789-793页

作者： fan yang Bin LIU Dai-ning fanG Applied Mechanics Laboratory Department of Engineering Mechanics Tsinghua University Beijing 100084 China State Key Laboratory for Turbulence and Complex Systems College of Engineering Peking University Beijing 100871 China

A new oxidation kinetics model is established for high-temperature oxidation. We assume that the interface reaction is fast enough and the oxidation rate is controlled by diffusion process at high temperature. By introducing the growth stress gradient we modify the classical oxidation parabolic law. The modified factor of the oxidation rate constant is a function of growth strain, environment oxygen concentration, and temperature. The modeling results show that the stress gradient effect on the oxidation rate cannot be ignored. Growth strain will dominate whether the stress gradient effect promotes or slows down the oxidation process. The stress gradient effect becomes weaker at higher temperature. This effect is amplified at higher concentrations of environmental oxygen. Applied mechanical loads do not affect the oxidation rate. This model is available for high temperature oxidation of metals and alloys.

关键词： High temperature Modeling Growth stress gradient Oxidation rate

Dealumination and desilication for Al-rich HZSM-5 zeolite via steam-alkaline treatment and its application in methanol aromatization

在线全文

学校读者我要写书评

暂无评论

Frontiers of Chemical Science and Engineering 2019年第3期13卷 543-553页

作者： Yuehua fang fan yang Xuan He Xuedong Zhu State Key Laboratory of Chemical Engineering School of Chemical EngineeringEast China University of Science and TechnologyShanghai 200237China

The hierarchical HZSM-5 was prepared via dealumination and desilication of commercial Al-rich HZSM-5, and characterized by X-ray diffraction, 27Al magic-angle spinning nuclear magnetic resonance, inductively coupled plasma mass spectrometry, scanning electron microscope, transmission electron microscope, N2 adsorption-desorption, NH3 temperature-programmed desorption, performed thermogravimetric and Raman spectrum. The results showed that partial framework of HZSM-5 was removed after steam treatment at 0.15 MPa, 500℃ for 3 h. HZSM-5 with high specific surface area and much mesoporosity was obtained by the subsequent alkaline treatment. The regulation of acid quantity was achieved by altering the concentration of alkaline. Dealumination and desilication of Al-rich HZSM-5 zeolites became more effective using a combination of steam and alkaline treatments than using alkaline treatment alone. Methanol aromatization reaction was employed to evaluate the catalytic performance of treated HZSM-5 at 0.15 MPa, 450℃ and MHSV of 1.5 h^-1. The results indicated that after steam treatment, HZSM-5 further treated with 0.2 mol/L NaOH exhibits the best catalytic performance: the selectivity of aromatics reached 42.1% and the lifetime of catalyst attained 212 h, which are much better than untreated HZSM-5.

关键词： steam treatment alkaline treatment,hierarchical ZSM-5 methanol aromatization