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排序方式: 共有169条查询结果,搜索用时 15 毫秒
1.
The effect of tempering on the magnetic Barkhausen noise (MBN) signal profile was studied in case-carburised EN36 steel using a range of magnetic excitation frequencies and a number of frequency ranges for analysis of the MBN signal. The MBN level generally increases with tempering due to coarsening of the microstructure. With higher values of excitation frequency, fEX, the MBN profile exhibits a single peak, but with low values of fEX, double peaks are observed. The MBN peak obtained with higher fEX was found to correlate well with hardness changes in a region, down to 100 μm below the surface. The analysis of the MBN signal produced with low fEX, in narrow frequency ranges selected by software frequency filtering, showed variations in the extent of changes in the relative height of the two MBN peaks in the profile. After taking into account the skin depth-frequency relation for the MBN signal, variations in the values of the two MBN peaks in different analysing frequency ranges were found to correlate well with hardness variations at different depths down to 425 μm below the surface. An empirical relationship has been established between the hardness-depth profile and the MBN measurements. 相似文献
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Planar Heterojunction Perovskite Solar Cells Incorporating Metal–Organic Framework Nanocrystals 下载免费PDF全文
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S. N. Moorthy 《Starch - St?rke》1985,37(9):307-308
Acetyl and propionyl derivatives of cassava starch were prepared using perchloric acid catalysis. The temperature for obtaining optimum yield and degree of substitution (DS) was 30°C. The clarity and sol stability of the derivatives are improved, while viscosity is reduced. 相似文献
4.
A. Mohan BabuB.C. Jamalaiah J. Suresh KumarT. Sasikala L. Rama Moorthy 《Journal of Alloys and Compounds》2011,509(2):457-462
Lead tungsten tellurite (LTT) glasses doped with different Dy3+ ion concentrations have been prepared and characterized through optical absorption, photoluminescence and decay measurements. The glassy nature of the LTT host has been confirmed through the XRD measurements. The three phenomelogical intensity parameters Ωλ (λ = 2, 4, 6) have been determined from the absorption spectral intensities using the Judd-Ofelt (J-O) theory. The hypersensitivity of 6H15/2 → 6F11/2 transition based on the magnitude of Ω2 parameter has also been discussed. By using the J-O intensity parameters several radiative properties such as spontaneous transition probabilities (AR), fluorescence branching ratios (βR) and radiative lifetimes (τR) have been determined. The effect of Dy3+ ion concentration on the emission intensities of 4F9/2 → 6HJ′ (J′ = 15/2, 13/2, 11/2 and 9/2) transitions has also been reported. 相似文献
5.
S.A.Saleem B.C.Jamalaiah A.Mohan Babu K.Pavani L.Rama Moorthy 《中国稀土学报(英文版)》2010,28(2):189-193
Glasses with chemical composition of (in mol.%): 26 RF-20 PbO-10 TeO2-43 H3BO3-1 EuO3 (RLTB) were prepared by conventional melt quenching method. The Judd-Ofelt intensity parameters Ω2 and Ω6 were obtained from the absorption intensities of 7F0→5D2 and 7F0→5L6 transitions, respectively. In order to overcome the problem of applicability of Judd-Ofelt analysis at room temperature due to the overlapping of the transitions originating from 7F0 and 7F1 levels of Eu3+ ion, the effect of the thermalization on the population of energy levels was taken into account. The photoluminescence spectra contained five emission bands originating from the 5D0 metastable state to 7FJ (J=0, 1, 2, 3, 4) lower lying states. The decay profiles were found to be single exponential in all the three glasses. The measured lifetimes (τmes) were in good agreement with the calculated lifetimes (τcal) obtained by using the thermally corrected Judd-Ofelt intensity parameters. 相似文献
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Assemblies of two horizontal coaxial flexible tubes with loosely held spacers to maintain the annular gap between the coaxial tubes, are generally used in nuclear reactor for carrying hot fluid inside the inner tube with an insulating gas filled annulus between the outer and inner tubes to reduce heat losses. The appropriate location of these spacers is important for maintaining coaxiality and preventing contact between inner and outer tubes due to bending creep of inner tube. Determination of spacer locations is therefore an important task. The conventional method of inspection may be costly and time consuming. This paper presents a non-intrusive technique based on vibration measurement, developed for the detection of such spacer spring locations in the assembly of the two coaxial tubes. The technique is based on a parameter identification approach. It involves the identification of spacer locations by updating the position parameters of the spacer in a Finite Element (FE) structural model through the optimization of an error criterion based on the difference between measured and computed natural frequencies of the assembly of the two coaxial tubes. A gradient-based method is used for optimization in the FE model updating problem. The proposed technique has been validated by numerical simulation as well as on a laboratory scale experimental setup. 相似文献
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