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51.
研究一维热传导方程热源反问题.给出基于最小二乘支持向量机(LS-SVM)求解的半解析表达式,此外还给出一种参数调节方法以及算法稳定性的证明.数值实验表明该方法具有较高的数值精度和稳定性. 相似文献
52.
A series of hydrophobically modified polyacrylamide and polyacrylamide-co-poly(acrylic acid) gels with systematically varying hydrophobicity were prepared by free-radical polymerization of acrylamide,
n-alkylacrylamides (n = 10, 12, and 14), and acrylic acid. The swelling of these gels was examined in water and in both anionic and cationic surfactant
solutions. It was found that the gels which incorporated acrylic acid showed extremely high swelling in water. Maximum swelling
was observed in gels which incorporated 10 mol% acrylic acid. The swelling of these gels was much less in solutions of both
anionic and cationic surfactants than in water. The gels which did not incorporate acrylic acid demonstrated little swelling
in water, but showed increased swelling in both anionic and cationic surfactant solutions with increased hydrophobicity of
the gel.
Received: 1 February 1999 Accepted in revised form: 5 March 1999 相似文献
53.
54.
Chaohai Wang Jeonghun Kim Jing Tang Jongbeom Na Yong‐Mook Kang Minjun Kim Hyunsoo Lim Yoshio Bando Jiansheng Li Yusuke Yamauchi 《Angewandte Chemie (International ed. in English)》2020,59(5):2066-2070
Carbon aerogels (CAs) with 3D interconnected networks hold promise for application in areas such as pollutant treatment, energy storage, and electrocatalysis. In spite of this, it remains challenging to synthesize high‐performance CAs on a large scale in a simple and sustainable manner. We report an eco‐friendly method for the scalable synthesis of ultralight and superporous CAs by using cheap and widely available agarose (AG) biomass as the carbon precursor. Zeolitic imidazolate framework‐8 (ZIF‐8) with high porosity is introduced into the AG aerogels to increase the specific surface area and enable heteroatom doping. After pyrolysis under inert atmosphere, the ZIF‐8/AG‐derived nitrogen‐doped CAs show a highly interconnected porous mazelike structure with a low density of 24 mg cm?3, a high specific surface area of 516 m2 g?1, and a large pore volume of 0.58 cm?3 g?1. The resulting CAs exhibit significant potential for application in the adsorption of organic pollutants. 相似文献
55.
J. J. Whitmore F. Persi W. S. Toothacker P. A. Elcombe J. C. Hill W. W. Neale W. D. Walker W. Kowald P. Lucas L. Voyvodic R. Ammar D. Coppage R. Davis J. Gress S. Kanekal N. Kwak J. M. Bishop N. N. Biswas N. M. Cason V. P. Kenney M. C. K. Mattingly R. C. Ruchti W. D. Shephard 《Zeitschrift fur Physik C Particles and Fields》1994,62(2):199-227
56.
Apparent molal heat capacities as a function of the degree of neutralization have been determined for dilute aqueous solutions of poly(acrylic acid) (PAA), poly(methacrylic acid) (PMA), copoly(maleic acid-ethylene) (MAEt), and copoly(maleic acid-styrene) (MASt) using direct flow microcalorimetry. Apparent molal volumes were measured as well. Both molal heat capacity and molal volume decrease with increasing ionization of the polymer. The effect of the hydrophobic interactions of the methyl group or phenyl group was obtained from the difference in the molal quantities of PMA and PAA, or MASt and MAEt. No evidence of hydrophobic effects, as determined from the heat capacity, was found for the conformational transition of PMA, but the hydration of the phenyl groups in MASt was found to be changed significantly at a degree of neutralization of 0.4. 相似文献
57.
58.
Seong Hojun Cho Kyoungah Yun Junggwon Kwak Kiyeol Jun Jin Hyung Kim Sangsig 《Solid State Sciences》2010,12(8):1328-1331
In this study, we demonstrate the photogating effects of p-type HgTe nanoparticles (NPs) on an n-type ZnO nanowire (NW). The photogating effects are due to the charge separation of the charge carriers photogenerated in the NPs under illumination and the subsequent accumulation of the photogenerated electrons in the pn junction of the NPs and the NW. The presence of the electrons in the junction reduces the current in the ZnO NW. The photogating effects are proved by the different photocurrent behavior of the ZnO NW to which the HgTe NPs are attached from that of a bare ZnO NW. In addition, the dependence of the photogating effects on the power of the incident light is discussed. 相似文献
59.
This paper analyzes the evolution of the dependence structure for various time window intervals, known as Epps effect, using the Trade and Quote data of 663 actively traded stocks in Korean stock market. It is found that the random matrix theory analysis could not represent the dependence structure of the stock market in the microstructure regime. The Cook-Johnson copula is introduced as a parsimonious alternative method to handle this problem, and the existence of the Epps effect is confirmed for the 663 stocks using high frequency data. It was also found that large capitalization companies tend to have a stronger dependence structure, except for the largest capitalization group, since the phenomenon of price level resistance leads to the weak dependence structure in the largest capitalization group. In addition, grouping the industry as a sub-portfolio is an appropriate approach for hour interval traders, whereas this approach is not a strategy recommended for high frequency traders. 相似文献
60.
Albrecht H Binder U Harder G Lembke-Koppitz I Philipp A Schmidt-Parzefall W Schröder H Schulz HD Wurth R Donker JP Drescher A Matthiesen U Scheck H Spaan B Spengler J Wegener aD Gabriel JC Schubert KR Stiewe J Waldi R Weseler S Brown NN Edwards KW Frisken WR Fukunaga C Gilkinson DJ Gingrich DM Goddard M Kapitza H Kim PC Kutschke R MacFarlane DB McKenna JA McLean KW Nilsson AW Orr RS Padley P Patel PM Prentice JD Seywerd HC Stacey BJ Yoon T Yun JC Ammar R Coppage D Davis R Kanekal S Kwak N 《Physical review letters》1986,56(6):549-552