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961.
N. Unnikrishnan Nair K. K. Sudheesh 《Annals of the Institute of Statistical Mathematics》2008,60(3):591-603
In the present paper a general theorem that links characterizations of discrete life distributions based on relationship between
failure rate and conditional expectations with those in terms of Chernoff-type inequalities is proposed. Exact expression
for lower bounds to the variance is calculated for distributions belonging to the modified power series family, Ord family
and mixture geometric models. It is shown that the bounds obtained here contain the Cramer–Rao and Chapman–Robbins inequalities
as special cases. An application of the results to real data is also provided. 相似文献
962.
Characterizations of multivariate life distributions 总被引:1,自引:0,他引:1
N. Unnikrishnan Nair 《Journal of multivariate analysis》2008,99(9):2096-2107
Characterizations of multivariate distributions has been a topic of great interest in applied statistics literature for the last three decades. In this paper, we develop characterizations of multivariate lifetime distributions by relationship between multivariate failure rates (reversed failure rates) and the left (right) truncated expectations of functions of random variables. We, then, discuss the application of the results to derive a multivariate Stein type identity. 相似文献
963.
S. P. Nair P. M. Pardalos V. A. Yatsenko 《Journal of Optimization Theory and Applications》2007,134(3):533-547
In this paper, we analyze various control algorithms that have been proposed for controlling spatiotemporal chaos in a globally
coupled map lattice (CML) system. We reformulate the choice of feedback parameters in such systems as a constrained optimization
problem and provide numerical and experimental results on the choice of optimal parameters for controlling the mean global
Lyapunov exponent of a lattice. Finally, we propose a scheme to use this optimization technique to solve a learning problem
in which such a CML system can be used to emulate the dynamics of an epileptic brain.
This work was supported by NIH-NIBIB and CRDF grants. 相似文献
964.
Eliane Maria Loiola Nair Maria Maia de Abreu Paulo Oswaldo Boaventura-Netto Peter Hahn Tania Querido 《European Journal of Operational Research》2007
The quadratic assignment problem (QAP), one of the most difficult problems in the NP-hard class, models many real-life problems in several areas such as facilities location, parallel and distributed computing, and combinatorial data analysis. Combinatorial optimization problems, such as the traveling salesman problem, maximal clique and graph partitioning can be formulated as a QAP. In this paper, we present some of the most important QAP formulations and classify them according to their mathematical sources. We also present a discussion on the theoretical resources used to define lower bounds for exact and heuristic algorithms. We then give a detailed discussion of the progress made in both exact and heuristic solution methods, including those formulated according to metaheuristic strategies. Finally, we analyze the contributions brought about by the study of different approaches. 相似文献
965.
Stereoselective synthesis of highly functionalized tetrahydrofurans via the 1,3-dipolar cycloaddition reaction of acyclic carbonyl ylides to activated alkenes is described. 相似文献
966.
In the search for silicon technology compatible substrate for III-nitride epitaxy, we present a proof-of-concept for forming epitaxial SiC layer on Si(1 1 1). A C/Si interface formed by ion sputtering is exposed to 100-1500 eV Ar+ ions, inducing a chemical reaction to form SiC, as observed by core-level X-ray photoelectron spectroscopy (XPS). Angle dependent XPS studies shows forward scattering feature that manifest the epitaxial SiC layer formation, while the valence band depicts the metal to insulator phase change. 相似文献
967.
S. Saravana Kumar M. Abdul Khadar K. G. M. Nair S. Dhara P. Magudapathy 《Journal of Raman spectroscopy : JRS》2008,39(12):1900-1906
ZnS nanocrytsals of size ∼2.5 nm were prepared by chemical precipitation technique. Pressed pellets of nanostructured ZnS were implanted with He+ ions at doses of 5 × 1014, 1 × 1015 and 5 × 1015 ions/cm2. Raman spectra of both unimplanted and He+ ion implanted samples were recorded with ultraviolet (UV) excitation. LO, 2LO, 2TO, (LO + TA) and (2TO − TA) modes of ZnS were observed in the resonance Raman spectra of the unimplanted nanostructured ZnS samples. In addition, a surface mode was observed at 294 cm−1. With the implantation of He+ ions, the 2TO mode disappeared and 2LO mode became prominent and this observation was attributed to the decrease in band gap of ZnS nanocrytsals due to ion implantation. The exciton–LO phonon coupling strength was determined from the intensity ratio of 2LO to LO modes and it was observed that the exciton–LO phonon coupling strength increases with increase in implantation dose. In the present work, we report for the first time the observation of 2TO mode in the resonance Raman spectrum of nanostructured ZnS and also the modification of exciton–LO phonon coupling strength of semiconductor nanoparticles by ion implantation. Copyright © 2008 John Wiley & Sons, Ltd. 相似文献
968.
G. Amarendra B.K. Panigrahi S. Abhaya Christopher David R. Rajaraman K.G.M. Nair C.S. Sundar Baldev Raj 《Applied Surface Science》2008,255(1):139-141
The void swelling behavior of heavy ion irradiated D9 steel has been investigated using variable low energy positron beam. The normalized defect-sensitive S-parameter shows up a large increase in the depth region corresponding to the maximum radiation damage as a function of irradiation temperature. From the variation of S-parameter as a function of irradiation temperature, the peak swelling temperature has been deduced and the results are discussed. 相似文献
969.
K. K. Abdullah N. Ramachandran K. Karunakaran Nair B. R. S. Babu Antony Joseph Rajive Thomas K. M. Varier 《Pramana》2008,70(4):633-641
We have carried out photon attenuation measurements at several energies in the range from 49.38 keV to 57.96 keV around the
K-absorption edges of the rare earth elements Sm, Eu, Gd, Tb, Dy and Er using 59.54 keV gamma rays from 241Am source after Compton scattering from an aluminium target. Pellets of oxides of the rare earth elements were chosen as mixture
absorbers in these investigations. A narrow beam good geometry set-up was used for the attenuation measurements. The scattered
gamma rays were detected by an HPGe detector. The results are consistent with theoretical values derived from the XCOM package.
相似文献
970.
Single crystals of potassium acid phthalate (KAP) and amino acid (DL‐Alanine, L‐Methionine) doped KAP were grown from aqueous solutions by slow cooling method. The grown crystals were characterized using powder X Ray diffraction (XRD) and Fourier Transform Infrared (FTIR) analysis. The thermal stability of KAP in the presence of dopants was analysed using Thermogravimetric and Differential Scanning caloriemetric (TGA/ DSC) studies and the maximum temperature for non linear optical application of this compound in the presence of dopants was found out. The transmittance of KAP was found to increase in the presence of dopants. Etch pits were observed for all the crystals using different etchants. Vickers microhardness tests were performed to study the mechanical stability of the crystals. The hardness of DL‐alanine doped KAP is more than that of L‐alanine doped KAP crystal. The dielectric constant and loss were determined as a function of temperature. Frequency response of the dielectric constant and dielectric loss factor have been studied over the frequency range of 50Hz – 5MHz. Second harmonic generation (SHG) was confirmed in all the crystals using the Kurtz and Perry powder technique. (© 2008 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim) 相似文献