检索结果-南通市图书馆

comparative study of Eu^(3+)-activated LnOcl(Ln=La and Gd) phosphors and their Judd-Ofelt analysis

Journal of Rare Earths 2015年第9期33卷 946-953页

作者： N.Dhananjaya c.shivakumara Rohit Saraf Sukanti Behera H.Nagabhushana Department of Physics B.M.S. Institute of Technology and Management Solid State and Structural chemistry Unit Indian Institute of Science c. N. R. Rao center for Advanced Materials Tumkur University

Eu3＋-activated layered LnOcI （Ln=La and Gd） phosphors were synthesized by the conventional solid-state method at relatively low temperature （700 ℃） and shorter duration of 2 h. The structural parameters were refined by the Rietveld refinement analysis and confirmed by the high resolution transmission electron microscopy （HRTEM）. Both the compounds were crystallized in the tetragonal structure with space group P4/nmm （No. 129）. The homogeneity of the elements were ana- lyzed by TEM mapping and found to be uniformly distributed. The photoluminescence spectra revealed that the intensity of 5D0--7F2 transition （619 nm） was more intense in Eu3＋-activated GdOc1 compared to LaOc1. This was due to the property of Gd3＋ ions to act as an intermediate sublattice to facilitate the energy transfer to Eu3＋ ions. Intensity parameters and radiative properties such as transition probabilities, radiative lifetime and branching ratio were calculated using the Judd-Ofelt theory. The cIE color coordinates result revealed that the Eu3＋-activated GdOc1 （0.641, 0.354） phosphor was close to the commercial red phosphors like, Y203：Eu3＋（0.645, 0.347）, Y202S：Eu3＋（0.647, 0.343） and National Television System committee （NTSc）（0.67, 0.33）. The results suggest that the present GdOcI：Eu3＋ compound acts as a potential candidate for red phosphor materials.

关键词： LaOc1 GdOc1 phosphors Judd-Ofelt cIE rare earths

来源：

维普期刊数据库

同方期刊数据库评论

在线全文

学校读者我要写书评

暂无评论

Performance Analysis of Thermoacoustic Refrigerator of 10 W cooling Power Made up of Poly-Vinyl-chloride for Different Parallel Plate Stacks by Using Helium as a Working Fluid

引用

Journal of Thermal Science 2021年第6期30卷 2037-2055页

作者： N V shivakumara BHEEMSHA Arya Department of Mechanical Engineering BMS College of EngineeringBengaluru 560019India Department of Mechanical Engineering Government PolytechnicChannasandraBengaluru 560067India

Refrigerants are usually provided in the conventional refrigeration system although the refrigerants produce chlorofluorocarbons(cFcs)and Hydro-chlorofluorocarbons(HcFcs),which are hazardous to the ***,these disadvantages can be overcome by using air or inert gas in the thermoacoustic refrigeration *** the present experimental work,helium is used as a working gas with an operating pressure range of 0.2 MPa to 1.0 MPa in order to study the performance of thermoacoustic refrigerator(TAR)which is fabricated using Poly-Vinyl-chloride(PVc).The parallel plate stacks with different porosity ratios have been considered to study the performance of *** temperature difference between the hot and cold heat exchanger and acoustic dynamic pressure were recorded by using Bruel and Kjaer data acquisition system under different operating *** effect of different operating parameters such as operating frequency(200 Hz to 600 Hz),cooling load(2 W to 10 W)and drive ratio(0.6%to 1.6%)have also been considered to study the performance of *** TAR also modeled in DeltaEc software and the results are compared with the experimental outcomes and found to be in good *** experimental results show that-2.1℃is the lowest temperature measured at cold heat exchanger by achieving the highest temperature difference of about 32.9℃.An improvement is around 36%as compared to that of previous experiments that used aluminium *** highest coefficient of Performance(cOP)and the Relative coefficient of Performance(cOPR)are found to be 2.024 and 0.217,respectively.

关键词： thermoacoustic refrigerator parallel plate stack porosity ratio temperature difference cOP cOPR

来源：

维普期刊数据库

同方期刊数据库评论

在线全文

学校读者我要写书评

暂无评论

The Onset of Ferromagnetic convection in a Micropolar Ferromagnetic Fluid Layer Heated from Below

引用

Journal of Electromagnetic Analysis and Applications 2013年第3期5卷 120-133页

作者： c. E. Nanjundappa I. S. shivakumara K. Srikumar Department of Mathematics Ambedkar Institute of Technology Bangalore India Department of Mathematics East Point College of Engineering for Women Bangalore India. UGc-cAS in Fluid Mechanics Department of Mathematics Bangalore University Bangalore India

The onset of ferromagnetic convection in a micropolar ferromagnetic fluid layer heated from below in the presence of a uniform applied vertical magnetic field has been investigated. The rigid-isothermal boundaries of the fluid layer are considered to be either paramagnetic or ferromagnetic and the eigenvalue problem is solved numerically using the Galerkin method. It is noted that the paramagnetic boundaries with large magnetic susceptibility χ delays the onset of ferromagnetic convection the most when compared to very low magnetic susceptibility as well as ferromagnetic boundaries. Increase in the value of magnetic parameter M1 and spin diffusion (couple stress) parameter N3 is to hasten, while increase in the value of coupling parameter N1 and micropolar heat conduction parameter N5 is to delay the onset of ferromagnetic convection. Further, increase in the value of M1, N1, N5 and χ as well as decrease in N3 is to diminish the size of convection cells.

关键词： Micropolar Ferrofluid Ferromagnetic convection Paramagnetic Boundaries Rigid Boundaries Magnetic Susceptibility

来源：

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

欢迎您,

建议与咨询留下您的常用邮箱和电话号码，以便我们向您反馈解决方案和替代方法

时间限定

文献类型

馆藏选择

核心期刊

语言

文献类型

帮助

文字说明：

检索规则说明：

检索范例：

分类表

所选分类

限定检索结果

文献类型

馆藏范围

日期分布

学科分类号

主题

机构

作者

语言

在线全文

在线全文

在线全文

请选择保存的检索档案：

请选择收藏分类：

通借通还

欢迎您,

建议与咨询 留下您的常用邮箱和电话号码，以便我们向您反馈解决方案和替代方法

时间限定

文献类型

馆藏选择

核心期刊

语言

文献类型

帮助

文字说明：

检索规则说明：

检索范例：

分类表

所选分类

限定检索结果

文献类型

馆藏范围

日期分布

学科分类号

主题

机构

作者

语言

在线全文

在线全文

在线全文

请选择保存的检索档案： 新增检索档案 确定 取消

请选择收藏分类： 新增自定义分类 确定 取消

通借通还

建议与咨询留下您的常用邮箱和电话号码，以便我们向您反馈解决方案和替代方法

请选择保存的检索档案：

请选择收藏分类：