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61.
Veenachary Vadla Puli Venkata Sreenivas Babu S. Narendra Prasad G. Prasad N. V. 《Journal of Materials Science: Materials in Electronics》2022,33(28):22614-22627
Journal of Materials Science: Materials in Electronics - Aurivillius intergrowth multiferroic phases are inspiring to many researchers owing to their scientific and technological application point... 相似文献
62.
Clean Technologies and Environmental Policy - There is increasing urgency towards integration of renewable sources into electricity generation so as to minimize greenhouse gas (GHG) emissions.... 相似文献
63.
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65.
Ricardo Martínez Venkata Sreenivas Puli Ram S. Katiyar 《Journal of Materials Science: Materials in Electronics》2013,24(8):2790-2795
Impedance spectroscopy measurements were carried out on lead based, 0.25 (PbZr0.52Ti0.48O3) + 0.25 (PbFe0.50Ta0.50O3) + 0.25 (PbFe0.67W0.33O3) + 0.25 (PbFe0.50Nb0.50O3) (PZT–PFT–PFW–PFN) solid solution over a wide range of temperatures (400–650 K) and frequencies (100 Hz–1 MHz). Impedance data showed the presence of both grains and grain boundaries effects in the electrical transport properties of quaternary. The role of the grains and grain boundaries to the impedance become more prominent around the phase transition (~420 K). Two thermally activated processes were found from the temperature dependences of the relaxation time (τ). Activation energies calculated from relaxation times obtained from imaginary part of impedance were estimated ~1.21 and ~1.84 eV over 400–490 K and 490–650 K respectively. The sum of the activation energies for the grain and grain boundary resistances is basically of the same order of magnitude that is from the impedance at high temperatures. A constant phase element is used in the equivalent electrical circuits for fitting of experimental impedance data. The nature of variation of the grain and grain boundary resistance with temperature suggested negative temperature coefficient of resistance behavior. 相似文献
66.
Sreenivas Jayanti Michel Valette 《International Journal of Heat and Mass Transfer》2005,48(9):1825-1839
The critical heat flux (CHF) condition is an important parameter in the design and operation of nuclear reactor fuel rod assemblies. It has traditionally been evaluated using look-up tables or empirical correlations. In the present paper, a set of relations, in the form of a one-dimensional three-field model, is presented which enables a mechanistic prediction of high-quality CHF known as dry out. This also allows a more fundamental treatment of post-dry out heat transfer. The ensemble of relations is validated by comparing the predictions with data obtained from the TPTF test series of JAERI and the THTF test series of ORNL. The rod bundles have been modelled on a sub-channel basis. The effect of spacer grids on the flow and heat transfer has been studied by including their geometrical characteristics only. Good predictions of the dry out location and the post-dry out variation of the rod temperature are obtained over the range of parameters investigated in these tests, namely, in the pressure range of 30-130 bar, mass flux range of 50-800 kg/m2 s and inlet condition ranging from sub-cooled to an inlet quality of 0.89. 相似文献
67.
A simple method for the design of monotonic lowpass analogue filters is presented. In this method, the coefficients involved in the design of these filters are obtained as the eigenvector corresponding to the smallest eigenvalue of a symmetric positive-definite matrix 相似文献
68.
Alexei A. Gaivoronski Leyuan Y. Shi Ramavarapu S. Sreenivas 《Discrete Event Dynamic Systems》1992,2(2):121-138
Augmented infinitesimal perturbation analysis (APA) was introduced by Gaivoronski [1991] to increase the purview of the theory of Infinitesimal Perturbation Analysis (IPA). In reference [Gaivoronski 1991] it is shown that an unbiased estimate for the gradient of a class of performance measures of DEDS represented bygeneralized semi-Markov processes (GSMPs) (cf. [Glynn 1989] can be expressed as a sum of an IPA-estimate and a term that takes into account the event order changes. In this paper we present an alternate approach to establishing the result of Gaivoronski, and from this we derive a necessary and sufficient condition for the validity of the IPA algorithm for this class of performance measures. Finally we validate our results by simulation examples.This research was supported by the National Science Foundation under grant number ECS-85-15449, Office of Naval Research Grants Nos. N00014-90-K-1093 and N00014-89-J-1023 and by Army Grant No. DAAL-03-86-K-0171. 相似文献
69.
This study aims to examine whether rapid communications exert more influence/impact on subsequent research. Citation analysis
of Short Communications (SCs) and Main Articles (MAs) from 1983 and 1990 for 5 high impact biomedical journals was carried
out for a five year period following publication.
The mean citations cumulated for the five year period showed no consistent trend. Some journals showed more citations for
SCs while some showed more for MAs. The mean citations (range) for SCs and MAs for the 1983 and 1990 papers respectively were
as follows:Gene: 14.13 (0-61) and 38.79 (0-677), 9.73 (0-93) and 13.17 (0-44);Journal of Clinical Investigation (JCI): 79.77 (3-202) and 27.52 (0-86), 50.52 (0-254) and 33.53 (0-151);Journal of Experimental Medicine (JEM): 39.80 (0-200) and 49.20 (0-403), 47.26 (0-258) and 50.27 (0-173); andJournal of Biological Chemistry (JBC); 36.21 (0-380) and 19.67 (0-53), 37.19 (0-273) and 26.84 (0-185). SCs ofJournal of Cell Biology (JCB) had a mean citation of 25.84 per article with a range of 0-98, while the MAs had a mean citation of 33.13 with the
range 4-122 during 1983-87.
The citation peak was seen about three years after publication for all the journals during both the periods. The mean cumulative
citations showed a progressive increase over the five years for both types of papers, in all journals and for both the 5 year
periods. The initial differences observed persisted even four years after the year of publication. No significant differences
were observed in the distribution of the cumulative 5 year citations between the SCs and MAs. An index of speed of citation
per article showed no substantial differences between SCs and MAs with MAs showing an edge over SCs. Both MAs and SCs of all
the journals showed nearly same average time per citation per article further confirming that the SCs do not enjoy the advantage
of speedier citation.
The results show that the generally perceived feeling of SCs getting cited more frequently and faster does not appear to be
valid. Hence, the practice of publishing SCs on a priority basis is perhaps not warranted. 相似文献
70.
Ordinal optimization of DEDS 总被引:8,自引:0,他引:8
In this paper we argue thatordinal rather thancardinal optimization, i.e., concentrating on finding good, better, or best designs rather than on estimating accurately the performance value of these designs, offers a new, efficient, and complementary approach to the performance optimization of systems. Some experimental and analytical evidence is offered to substantiate this claim. The main purpose of the paper is to call attention to a novel and promising approach to system optimization.This work is supported by NSF grants CDR-88-03012, DDM-89-14277, ONR contracts N00014-90-J-1093, N00014-89-J-1023, and army contracts DAAL-03-83-K-0171, DAAL-91-G-0194. 相似文献