检索结果-南通市图书馆

Chinese Science Bulletin 2007年第20期52卷 2847-2853页

作者： YU ChunMei ZHENG JianPing GRIFFIN w l Faculty of Earth Sciences China University of Geosciences Wuhan 430074 China State Key laboratory of Geological Processes and Mineral Resource China University of Geosciences Wuhan 430074 China GEMOC ARC National Key Center Department of Earth and Planetary Sciences Macquarie University Sydney NSW 2109 Australia

In situ Re-Os isotopes of sulfides in peridotitic xenoliths from Cenozoic Hannuoba basalts were analyzed by lAM-MC-ICPMS. The suifides developed two types of occurrences including silicate-enclosed and interstitial. In the enclosed sulfides, 187Os/188Os vary from 0.1124 to 0.1362 and 187Re/188Os from 0.0026 to 1.8027. In the interstitial ones, 187Os/188Os have a range from 0.1174 to 0.1354 and 187Re/188Os from 0.0365 to 1.4469. The oldest age, calculated by TRD for the enclosed sulfides, is 2.1 Ga. An isochron age of 2.3±1.2 Ga is obtained by five grains of enclosed sulfides and primitive mantle. The sulfides used have lower Re-Os isotopic ratio than primitive mantle. Meanwhile, an isochron age of 645±225 Ma is given by all in- terstitial sulfides and the enclosed sulfides with higher Re-Os isotopic ratio due to Re addition after man- tle formation. In addition, the model age of 1.3 Ga recorded by one interstitial sulfide, having similar TDM and TRD, should be meaningful to deep thermal event. The coexistence of different ages, revealed by in situ Re-Os isotope, indicates frequently-occurring mantle events beneath Hannuoba area.

关键词：地幔捕虏体中国北方矿石

STUDY　ON　THE　FlUORESCENCE　OF　THE　SYSTEM　SAMARIUM／2－BENZOYl－1，3－INDONE／CETYlTRIMETHYlAMMONIUM　BROMIDE　AND　ITS　ANAlYTICAl　APPlICATION

在线全文

学校读者我要写书评

暂无评论

Chinese Chemical letters 1996年第6期7卷 593-596页

作者： Jiang, w wang, l Si, ZK Zhu, GY SHANDONG UNIV DEPT CHEMJINAN 250100PEOPLES R CHINA SHANDONG MED UNIV DEPT PHARMJINAN 250012PEOPLES R CHINA

The fluoereence systecm Sm-BID-CTAB has been discovered and its fluorescence characteristics have *** excitation and ernission wavelengths are 360 um and 650 nm, respctively. The fluoescenceintensity is a linear function of the concentration of samariunt in the range 5.0×10-5-2.0×10-7 mol/*** limit is 5.0×10-9 mol/l. Standatd addition method is used for the determination of samarium insynthetic rare earth sample with satisfactory results

关键词： ITS BROMIDE AND ANAlYTICAl

Numerical Simulation of Temperature Distribution and ThermalStress Field in a Turbine Blade with Multilayer-Structure TBCs by a Fluid–Solid Coupling Method

在线全文

学校读者我要写书评

暂无评论

Journal of Materials Science & Technology 2016年第5期32卷 452-458页

作者： w.Z.Tang l.Yang w.Zhu Y.C.Zhou J.w.Guo C.lU Key laboratory of Key Film Materials and Application for Equipment(Hunan Province) School of Materials Science and EngineeringXiangtan UniversityXiangtan 411105China Key laboratory of low Dimensional Materials and Application Technology of Ministry of Education School of Materials Science and EngineeringXiangtan UniversityXiangtan 411105China Hunan Provincial Key laboratory of Thin Film Materials and Devices School of Materials Science and EngineeringXiangtan UniversityXiangtan 411105China School of Mechanical Engineering Xiangtan University Xiangtan 411105China Department of Mechanical Engineering Curtin UniversityPerthWA 6845Australia

To study the temperature distribution and thermal-stress field in different service stages, a two-dimensional model of a turbine blade with thermal barrier coatings is developed, in which the conjugate heat transfer analysis and the decoupled thermal-stress calculation method are adopted. Based on the simulation results, it is found that a non-uniform distribution of temperature appears in different positions of the blade surface, which has directly impacted on stress field. The maximum temperature with a value of 1030 ℃ occurs at the leading edge. During the steady stage, the maximum stress of thermally grown oxide （TGO） appears in the middle of the suction side, reaching 3.75 GPa. At the end stage of cooling, the maximum compressive stress of TGO with a value of-3.5 GPa occurs at the leading edge. Thus, it can be predicted that during the steady stage the dangerous regions may locate at the suction side, while the leadine edge mav be more Drone to failure on cooling.

关键词： Thermal barrier coatings Temperature distribution Thermal-stress field Conjugate heat transfer Decoupled thermal-stress calculation Fluid–solid coupling

Enhancement of Gain in l-Band Bismuth-Based Erbium-Doped Fibre Amplifier Using an Un-pumped EDF and Midway Isolator

在线全文

学校读者我要写书评

暂无评论

Chinese Physics letters 2004年第12期21卷 2452-2453页

作者： w.Y.Chong S.w.Harun H.Ahmad Photonicslaboratory DepartmentofPhysicsUniversityofMalaya50603KualaLumpur FacultyofEngineering MultimediaUniversityJalanMultimedia63100CyberjayaSelangorMalaysia

A hybrid l-band erbium-doped fibre amplifier (EDFA) with enhanced gain characteristic is demonstrated without a significant noise figure penalty. It uses a backward C-band amplified stimulated emission from both the ends of a bismuth-based EDFA system to pump an unpumped erbium-doped fibre (EDF) for gain enhancing. The maximum gain enhancement of 4.0dB is obtained at wavelength 1604nm with EDF length of 20m. The gain spectrum is reasonably flat in this amplifier compared with the amplifier without an EDF. The gain varies from 27.4dB to 30.2dB at wavelength region 1564--1608nm with incorporation of 20m EDF. Noise figure also varies from 6.0 to 7.7dB at this wavelength region.

关键词： Condensed matter: electrical magnetic and optical Optics quantum optics and lasers

Stress-Induced Martensitic Transformation of Zr_(50)Cu_(25)Ni_(10)Co_(15) Nanocrystals Embedded in an Amorphous Matrix

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 Materials Science & Technology 2017年第3期33卷 276-280页

作者： w.H.Gao X.Y.Yi X.l.Meng G.Song w.Cai l.C.Zhao School of Materials Science and Engineering Harbin Institute of Technology Department of Mechanical Engineering University of Houston

The stress induced martensitic phase transformation of spherical ZrCu nanocrystals embedded in an amorphous matrix was studied in this paper. Microstructural observations revealed that the martensitic transformation of the nanocrystal was hindered by the surrounding amorphous coating. The existence of two-step transformation from the austenite phase（B2） to the base structure martensite（B19＇） and finally to the most stable superstructure martensite（Cm） was also demonstrated. The Cm martensite with（021） type I twinning symmetrically accommodation was surrounded by the B19＇ martensite with dislocation morphologies.

关键词： Nanocrystals ZrCu Martensitic phase transformation Shape memory Transmission electron microscopy

Generic phase portrait analysis of finite-time singularities and generalized Teleparallel gravity

在线全文

学校读者我要写书评

暂无评论

Chinese Physics C 2017年第12期41卷 133-154页

作者： w. El Hanafy G.G.l. Nashed Centre for Theoretical Physics The British University in Egypt P.O. Box 43 El Sherouk City Cairo 11837 Egypt Mathematics Department Faculty of Science Ain Shams University Cairo 11566 Egypt Egyptian Relativity Group (ERG) Cairo University Giza 12613 Egypt

we analyze the four common types of finite-time singularity using a generic framework of the phase portrait geometric approach. This technique requires the Friedmann system to be written as a one-dimensional autonomous system. we employ a scale factor that has been used widely in the literature to realize the four finite- time singularity types, then we give a detailed discussion for each case showing possible novel models. Moreover, we show how different singularity types can play essential roles in different cosmological scenarios. Among several modified gravity theories, we show that the f（T） cosmology is compatible with the phase portrait analysis, since the field equations include Hubble derivatives only up to first order. Therefore, we reconstruct the f（T） theory which generates these phase portraits. we also perform a complementary analysis using the effective equation of state. Furthermore, we investigate the role of the torsion fluid in realizing the cosmic singularities.

关键词： inflation bounce big brake ACDM teleparallel gravity

long-Term Trends in Extreme Temperatures in Hong Kong and Southern China

在线全文

学校读者我要写书评

暂无评论

Advances in Atmospheric Sciences 2011年第1期28卷 147-157页

作者： T.C.lEE E.w.l.GINN Hong Kong Observatory

The observed long-term trends in extreme temperatures in Hong Kong were studied based on the meteorological data recorded at the Hong Kong Observatory Headquarters from 1885-2008. Results show that, over the past 124 years, the extreme daily minimum and maximum temperatures, as well as the length of the warm spell in Hong Kong, exhibit statistically significant long-term rising trends, while the length of the cold spell shows a statistically significant decreasing trend. The time-dependent return period analysis also indicated that the return period for daily minimum temperature at 4°C or lower lengthened considerably from 6 years in 1900 to over 150 years in 2000, while the return periods for daily maximum temperature reaching 35°C or above shortened drastically from 32 years in 1900 to 4.5 years in 2000. Past trends in extreme temperatures from selected weather stations in southern China from 1951-2004 were also assessed. Over 70% of the stations studied yielded a statistically significant rising trend in extreme daily minimum temperature, while the trend for extreme maximum temperatures was found to vary, with no significant trend established for the majority of stations.

关键词： extreme temperature long-term trend Hong Kong southern China

Achieving ultrahigh electromechanical properties with high TC in PNN-PZT textured ceramics

在线全文

学校读者我要写书评

暂无评论

Journal of Materials Science & Technology 2024年第8期175卷 258-265页

作者： Q.wang l.Bian K.li Y.C.liu Y.l.Yang B.Yang w.w.Cao School of Instrumentation Science and Engineering Harbin Institute of TechnologyHarbin 150080China Guangdong Provincial Key laboratory of Electronic Functional Materials and Devices Huizhou UniversityHuizhou 516001China Conversion and Storage School of Chemistry and Chemical EngineeringHarbin Institute of TechnologyHarbin 150080China

textured Pb(Ni_(1/3)Nb_(2/3))O_(3)-PbZrO_(3)-PbTiO_(3)(PNN-PZT)ceramics were prepared by templated grain growth(TGG)technique using 0.36PNN-x PZ-(0.64-x)PT(x=0.23,0.25 and 0.27)powder *** template content was derived to achieve the best electromechanical properties of textured *** piezoelectric coefficient d33=1165 pC/N,Curie temperature T_(C)=197℃,longitudinal mode electrome-chanical coupling factor k33=0.86 and a very large effective piezoelectric strain coefficient d_(33)^(*)=2041 pm/V were simultaneously achieved at the morphotropic phase boundary(MPB)composition(x=0.25)with 3 vol.%BaTiO_(3)(BT)*** structures of textured ceramics were analyzed in detail to reveal the origin of these high piezoelectric and electromechanical properties.

关键词： Pb(Ni_(1/3)Nb_(2/3))O_(3)-PbZrO_(3)-PbTiO_(3)(PNN-PZT) ceramics MPB composition Texture engineering Electromechanical properties Domain structure

Vibration and power flow analysis of periodically reinforced plates

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

Science China(Technological Sciences) 2011年第5期54卷 1141-1153页

作者： H. A. XU w. l. lI Department of Mechanical Engineering Wayne State University 5050 Anthony Wayne Drive Detroit MI48202 U.S.A.

In this paper an analytical method is proposed to investigate the vibration and power flows of periodically reinforced plate with general boundary conditions. Both the plate and stiffening beams are modeled as 3D structural components, and the couplings at the interfaces are specified in terms of 3D elastic joints. The displacement function for each stiffening beam is expressed as a modified Fourier cosine series, and the transverse and in-plane displacements for the plate are similarly expressed as the 2D versions of the modified Fourier cosine series expansions. The unknown Fourier coefficients are calculated using the Rayleigh-Ritz technique. The key advantages of the proposed method include: 1) it is capable of dealing with arbitrary boundary and coupling conditions, 2) it allows modeling any number of reinforcing beams with arbitrary lengths, and 3) the structural intensity, power flows, and kinetic energy distributions are readily calculated analytically from the displacement functions through appropriate mathematical (differential) operations, to name a few. The power flow characteristics of periodically reinforced plates are studied against various influencing factors, such as, plate and beam boundary conditions, coupling conditions, excitation locations, and dislocations resulting from minor misplacement of a reinforcing beam.

关键词： vibrations reinforced plates periodic structures analytical methods

Survey of insect visitation of ornamental flowers in Southover Grange garden, lewes, UK

在线全文

学校读者我要写书评

暂无评论

Insect Science 2015年第5期22卷 700-705页

作者： Mihail Garbuzov Elizabeth E. w.samuelaon Francis l. w. Ratnieks laboratory of Apiculture & Social Insects School of Life Sciences University of Sussex Falmer Brighton BN1 9QG United Kingdom

Ornamental flowers commonly grown in ttrban gardens and parks can be of value to flower-visiting insects. However, there is huge variation in the number of insects attracted among plant varieties. In this study, we quantified the insect attractiveness of 79 varieties in full bloom being grown in a public urban garden that is popular due to its beautiful flowers and other attractions. The results showed very clearly that most varieties （77%, n = 61） were either poorly attractive or completely unattractive to insect flower visitors. Several varieties （19%, n = 15） were moderately attractive, but very few （4%, n = 3） were highly attractive. Closer examination of Dahlia varieties showed that ＂open＂ flowered forms were approximately 20 times more attractive than ＂closed＂ flowered forms. These results strongly suggest that there is a great potential for making urban parks and gardens considerably more bee- and insect-friendly by selecting appropriate varieties.

关键词： bumble bees Dahlia double flowers honey bees pollinating insects wildlifefriendly gardening