479 research outputs found
Kernel-function based algorithms for semidefinitie optimization
No full textRecently, Y.Q. Bai, M. El Ghami and C. Roos [3] introduced a new class of so-called eligible kernel functions which are defined by some simple conditions. The authors designed primal-dual interiorpoint methods for linear optimization (LO) based on eligible kernel functions and simplified the analysis of these methods considerably. In this paper we consider the semidefinite optimization (SDO) problem and we generalize the aforementioned results for LO to SDO. The iteration bounds obtained are analogous to the results in [3] for LO.Software TechnologyElectrical Engineering, Mathematics and Computer Scienc
Oscillatory behaviour during the oxidation of methane over palladium metal catalysts
No full textOscillatory reactions over palladium foil and wire catalysts during the oxidation of methane have been investigated over a wide range of reaction temperatures and argon/methane/oxygen feed gas compositions. Characterisation of the catalyst has also been carried out using scanning electron microscopy (SEM) techniques, which revealed the presence of a porous surface. This suggested that the metal surface has undergone a change since the reaction commenced, and using X-ray powder diffraction (XRD) techniques the palladium phase was shown to be the dominant phase present. Hysteresis phenomena were observed in the activity of the reaction as the temperature was cycled up and down, showing that the metal surface was continually changing throughout the reaction. The activation energies of the reaction during the high reactivity mode, PdO, and low reactivity mode, Pd, were also calculated. Oscillation rates were observed to depend on the dominant surface. Oscillations were frequent when the high reactivity mode was dominant while the activation energy of this mode was found to be low. When the low reactivity mode was dominant, the oscillations were slower and the activation energy was three times larger. The results obtained imply that the behaviour of the palladium surface, switching back and forth from the reduced state to the oxidised state, is responsible for the oscillatory behaviour seen in this system
Oscillatory behaviour during the partial oxidation of methane over cobalt wires and foils
Get PDFThe oscillatory behaviour over cobalt wire and foil catalysts was examined at atmospheric pressure under various reaction temperatures and argon/methane/oxygen feed gas compositions for the partial oxidation of methane. Rough and porous oxide layers on the catalyst surface were confirmed by scanning electron microscopy (SEM) and X-ray diffraction (XRD) techniques. The results obtained from the experimental studies indicated that the oscillatory behaviour exhibited during methane oxidation was related to the behaviour of the catalyst surface switching back and forth from the reduced state to the oxidised state. The reduction of the oxide layer followed by the almost immediate re-oxidation of the metal can be accounted for only if the oxide layer formed by oxidation is different from the oxide layer existing during reduction
Inequality and Migration: A Behavioral Link
Get PDFWe provide an analytical-behavioral explanation for the observed positive relationship between income inequality, as measured by the Gini coefficient, and the incentive to migrate. We show that a higher total relative deprivation of a population leads to a stronger incentive to engage in migration for a given level of a population’s income; that total relative deprivation is positively related to the Gini coefficient; and that, consequently, the Gini coefficient and migration are positively correlated, holding the population’s income constant.Income inequality, Relative deprivation, The Gini coefficient, The incentive to migrate
Bounds for the Gutman-Milovanovic index and some applications
Get PDFIn this paper, we examine the Gutman-Milovanovic index and establish new upper and lower bounds for it. These bounds include terms related to the general sum connectivity index, the general second Zagreb index, and the hyperbolicity constant of the underlying graph. Also, we model physicochemical properties of polyaromatic hydrocarbons using the Gutman-Milovanovic index.Open Access funding provided thanks to the CRUE-CSIC agreement with Springer Nature.. The research of third author (Y.Q.) has been partially supported by Grant CEX2019-000904-S, funded by: MCIN/AEI/10.13039/501100011033
Structural And Magnetic Study Of A Diluted Magnetic Semiconductor: Fe-doped Ceo 2 Nanoparticles
No full textThis paper reports the effect of Fe doping on the structure and room temperature ferromagnetism of CeO 2 nanoparticles. X-ray diffraction and the selective area electron diffraction measurements performed on the Ce 1-xFe xO 2 (0 ≤ x ≤ 0.07) nanoparticles showed a single-phase nature with a cubic structure, and none of the samples showed the presence of any secondary phase. The mean particle size, which was calculated using transmission electron microscopy, increased with the increase in the Fe content. The DC magnetization measurements that were performed at room temperature showed that all the samples exhibited ferromagnetism. The saturation magnetic moment increased with the increase in the Fe content. Copyright© 2011 American Scientific Publishers All rights reserved.111555559Ohno, H., (1998) Science, 281, p. 951Prinz, G.A., (1998) Science, 282, p. 1660Sharma, S.D., (2001) Am. Sci., 89, p. 516Dietl, T., Ohno, H., Matsukura, F., Cibert, J., Ferrand, D., (2000) Science, 287, p. 1019Ohno, H., Sen, A., Matsukura, F., Oiwa, A., Endo, A., Katsumoto, S., Lye, Y., (1996) Appl. Phys. Lett., 69, p. 363Ohno, H., (1999) J. of Magn. Mater., 200, p. 110Bouloudenine, M., Viart, N., Colis, S., Kortus, J., Dinia, A., (2005) Appl. Phys. Lett., 87, p. 052501Jaffe, J.E., Droubay, T.C., Chambers, S.A., (2005) J. of Appl. Phys., 97, p. 073908Weng, H., Yang, X., Dong, J., Mizuseki, H., Kawasaki, M., Kawazoe, Y., (2004) Phys. Rev. B, 69, p. 125219Coey, J.M.D., Venkatesan, M., Fitzgerald, C.B., (2005) Nat. Mater., 4, p. 173Venkateshan, M., Fitzgerald, C.B., Coey, J.M.D., (2004) Nature, 430, p. 630Coey, J.M.D., Douvalis, A.P., Fitzgerald, C.B., Venkatesan, M., (2004) Appl. Phys. Lett., 84, p. 1332Rossignol, S., Madier, Y., Duprez, D., (1999) Catal. Today, 50, p. 173Shiono, M., Kobayashi, K., Nguyen, T.L., Hosoda, K., Kato, T., Ota, K., Dokiya, M., (2004) Solid-state Ionics, 170, p. 1Trovarelli, A., Leitenburg, C.D., Dolcetti, G., (1997) Chem. Tech., 27, p. 32Wen, Q.Y., Zhang, H.W., Song, Y.Q., Yang, Q.H., Zhu, H., Xiao, J.Q., (2007) J. Phys.: Condens. Mater., 19, p. 246205Song, Y.Q., Zhang, H.W., Wen, Q.Y., Peng, L., Xiao, J.Q., (2008) J. Phys.: Condens. Mater., 20, p. 255210Song, Y.Q., Zhang, H.W., Wen, Q.Y., Zhu, H., Xiao, J.Q., (2007) J. Appl. Phys., 102, p. 043912Fernandes, V., Klein, J.J., Mattoso, N., Mosca, D.H., Silveira, E., Ribeiro, E., Schreiner, W.H., De Oliveira, A.J.A., (2007) Phy. Rev. B, 75, pp. 121304RVodungbo, B., Zheng, Y., Vidal, F., Demaille, D., Etgens, V.H., Mosca, D.H., (2007) Appl. Phys. Lett., 90, p. 062510Hirano, M., Kato, E., (1996) J. Am. Ceram. Soc., 79, p. 777Chen, P.L., Chen, I.W., (1996) J. Am. Ceram. Soc., 79, p. 3129Chu, X., Chung, W., Schmidt, L.D., (1996) J. Am. Ceram. Soc., 76, p. 2115Zhou, X.D., Huebner, W., Anderson, H.U., (2002) Appl. Phys. Lett., 80, p. 3814Kumar, S., Kim, Y.J., Koo, B.H., Lee, C.G., (2009) IEEE Trans. Magn., 45, p. 2439Thurber, A., Reddy, K.M., Shutthanandan, V., Engelhard, M.H., Wang, C., Hays, J., Punnoose, A., (2007) Phys. Rev. B, 76, p. 165206Rubio, J., Oteo, J.L., Villegas, M., Duran, P., (1997) J. of Mater. Sci., 32, p. 643Zhang, Y.W., Rui, S., Liao, C.S., Yan, C.H., (2003) J. Phys. Chem. B, 107, p. 10159Yan, B., Zhu, H., (2008) J. Nanopart. Res., 10, p. 127
A Faithful Braid Group Action on the Stable Category of Tricomplexes
No full textBicomplexes of vector spaces frequently appear throughout algebra and geometry. In Section 2, we explain how to think about the arrows in the spectral sequence of a bicomplex via its indecomposable summands. Polycomplexes seem to be much rarer. In Section 3 of this paper, we rethink a well-known faithful categorical braid group action via an action on the stable category of tricomplexes.M.K. was partially supported by grants DMS-1406065, DMS-1664240, and DMS-1807425 from the NSF, while Y.Q. was partially supported by the NSF grant DMS-1947532 when working on this paper. The first author learned algebraic topology for the first time from the Russian classic by Dmitry Fuchs and Anatolii Fomenko [6] (in its first edition named Homotopic Topology), while the second author enjoyed teaching graduate courses out of this reprinted classic at his previous work institution. It is our great pleasure to dedicate this short note to Dmitry Fuchs on the occasion of his eightieth anniversary
Y.Q. Liu2, T.Y. Wang2, T.H. Zhang3 andM.H. Liu2
No full textA novel kind of supramolecular polymer filament with a diameter of 2-5 mu m was artificially synthesized, which is in fact a bundle of self-assembled nanotubes with a diameter of about 40 nm. The filament can be drawn from a special alkaline aqueous solution directly and free standing in room temperature, which has never been performed earlier. A microtensile tester was developed with the aid of an electronic balance to investigate the mechanical properties of the new filament. Monotonic and load-unload tensile tests were performed, respectively. The maximum tensile strength and the elastic modulus of the filament were 23.8 MPa and 1.9 GPa, respectively, which were higher than previous supramolecular polymers and comparable to some covalent-linked polymers.</p
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