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101.
Retrieving the heat transfer coefficient for jet impingement from transient temperature measurements
Arkadiusz Ryfa Ryszard A. Bialecki 《International Journal of Heat and Fluid Flow》2011,32(5):1024-1035
Algorithm of retrieving the heat transfer coefficient (HTC) from transient temperature measurements is presented. The unknown distributions of two types of boundary conditions: the temperature and heat flux are parameterized using a small number of user defined functions. The solutions of the direct heat conduction problems with known boundary temperature and flux are expressed as a superposition of auxiliary temperature fields multiplied by unknown parameters. Inverse problem is formulated as a least squares fit of calculated and measured temperatures and is cast in a form of a sum of two objective functions. The first results originates from an inverse problem for retrieving the boundary temperature the second comes from the inverse problem for reproducing the boundary heat flux. The final form of the objective function is obtained by enforcing constant in time value of the heat transfer coefficient. This approach leads to substantial regularization of the results, when compared with the standard technique, where HTC is calculated from separately reconstructed temperature and heat flux on the boundary. The validation of the numerical procedure is carried out by reconstructing a known distribution of the HTC using simulated measurements laden by stochastic error. The proposed approach is also used to reconstruct the distribution of the HTC in a physical experiment of heating a cylindrical sample using an impinging jet. 相似文献
102.
Łukasz Kosiński 《Journal of Geometric Analysis》2011,21(4):902-919
We give a characterization of non-hyperbolic pseudoconvex Reinhardt domains in ℂ2 for which the answer to the Serre problem is positive. Moreover, all non-hyperbolic pseudoconvex Reinhardt domains in ℂ2 with non-compact automorphism group are explicitly described. 相似文献
103.
Martowicz Adam Kantor Sławomir Pieczonka Łukasz Bryła Jakub Roemer Jakub 《Meccanica》2021,56(4):841-854
Meccanica - The work is devoted to the numerical aspects of the modeling tool elaborated to simulate the phenomenon of solid phase transformation in shape memory alloys. Particularly, a nonlocal... 相似文献
104.
KATARZYNA BUCIOR ANDRZEJ PATRYKIEJEW OREST PIZIO STEFAN SOKOŁOWSKI ZOFIA SOKOŁOWSKA 《Molecular physics》2013,111(6):721-731
We investigate the fluid—fluid demixing transitions in the case of adsorption of so-called symmetric binary mixtures in slit-like pores at temperatures higher than the bulk gas—liquid critical temperature. The aim of the study is to determine how the demixing of such mixtures in the pores depends on the bulk phase composition and on the parameters characterizing the pore. The calculations have been carried out by means of a density functional theory. In the case of an equimolar bulk mixture, the demixing transition inside the pore occurs only when the adsorption potentials of both species are identical. The occurrence of this transition is manifested by a cusp in the adsorption isotherm. For nonequimolar bulk phase compositions, the transition can also take place if the adsorption energies of both components are different. However, the difference in the adsorption energies should be small enough, otherwise a continuous demixing takes place. For non-equimolar compositions two branches of the grand canonical potential intersect, whereas for equimolar bulk composition they meet tangentially. We have determined phase behaviour for several model systems. 相似文献
105.
We report on studies of changes in the emission spectra (excited at 808 nm) of the Yb-doped Ca4NdO(BO3)3 single crystals due to the photothermal effects caused by the pulsed Nd:YAG laser. Increase of the sample's surface temperature after laser treatment leads to significant enhancement of the 1040 to 1060 nm emission (ascribed to the Nd3+ 4F3/2 → 4I9/2, 4I11/2 transitions) and simultaneous decrease of the 975 to 1050 nm emission (corresponding to the Yb3+ 2F5/2 → 2F7/2 transition). We explain such an increase of the Nd3+ luminescence by thermally activated Yb3+ → Nd3+ energy transfer. 相似文献
106.
Abstract With comparable molar quantities, chromotropic acid reacts with compounds containing aldehyde groups -CHO e.g. with formadehyde or glyoxylic acid to form cyclic compounds with rings containing four chromotropic acid fragments — cyclotetrachromotropylene derivatives. The cyclic compounds, due to the presence of a cavity in the molecule, can play the part of host and complex smaller molecules, which has been confirmed on the basis of triethylamine by the 1H-NMR measurements. Using spectrophotometric method the stability constant of 1:1 complex formed between Ti(IV) and cyclic compound chromotropic acid with formaldehyde has been determined - K = (9,0 ± 0,1) 104. 相似文献
107.
Małgorzata Norek Grzegorz Łuka Marek Godlewski Tomasz Płociński Marta Michalska-Domańska Wojciech J. Stępniowski 《Applied Physics A: Materials Science & Processing》2013,111(1):265-271
Luminescent properties of ZnO nanorods covered with Ag nanoparticles are examined. Nanorods were synthesized on AAO templates using Atomic Layer Deposition (ALD) technique. Two types of the samples were prepared with different arrangement of ZnO nanorods and doping conditions. Nanorods of the second type were codoped with Al, to stimulate defect-related emissions. The ZnO material fills heterogeneously the interior of the AAO nanopores and has hexagonal, wurtzite structure. Both types of structures exhibit a broad defect-related emission at about 440 nm, most probably related to recombination at zinc interstitial (Zni) defects. This emission in samples with a random distribution of ZnO:Al nanorods and finer Ag nanoparticles is enhanced by factor of ~2.5 upon Ag deposition. The so-obtained material is interesting from the point of view of its application in blue range emitting diodes. 相似文献
108.
Dagmara Jacewicz Aleksandra Dąbrowska Agnieszka Łapińska Lech Chmurzyński 《Transition Metal Chemistry》2006,31(5):575-579
The cis-[Cr(phen)2(O2CO)]+ ion was prepared through the displacement of two molecules of water from the cis-[Cr(phen)2(OH2)2]3+ by the bidentate carbonate anion. It underwent two-phase hydrolysis reactions under acidic conditions (0.1 < [H+] < 2.7 m) at 5, 10, 15, 20 and 25 °C. Via slow carbonato chelate ring opening (first step k1slow) and a second fast decarboxylation(k2fast value). The first step was preceded by protonation of the coordinate bidentate carbonate ligand. The second step exhibited
no pH dependence, while k1slow values increased with acid concentration that suggested the presence of both protonated and deprotonated reactant species.
Based on these observations we have proposed a hydrolysis mechanism featuring H2O-induced ring-opening of the coordinate CO32− group in the first step k1slow followed by loss of CO32− from two intermediates, [Cr(phen)2(O2COH)]2+ (k1slow) and [Cr(phen)2(OH2)(O2COH)]2+ (k2fast). 相似文献
109.
J. Łojewska A. Lubańska P. Miśkowiec T. Łojewski L.M. Proniewicz 《Applied Physics A: Materials Science & Processing》2006,83(4):597-603
This study deals with the quantitative and qualitative interpretation of transmission FTIR spectra of aged model paper samples to prepare the basis for a kinetic model of cellulose degradation involving mixed hydrolytic and oxidative mechanism. The ageing experiments were performed in situ under various conditions (pure water vapour, dried air, 100, 150 °C) to discriminate between hydrolytic and oxidative paths. Our focus was on the spectra between 1500–1900 cm-1, where the products of paper ageing appear in the form of various carbonyl groups. A procedure of spectra standardization was used to interpret the bands area in terms of the conversion of carbon atoms in cellulose. From the time evolution of the bands the overall kinetic curves were generated. The positions of the carbonyl bands were verified by independent experiments and theoretical calculations (DFT method). A simple model involving a hydrolytic reaction route and first order kinetics was positively tested on the available experimental basis. PACS 81.05.-t; 82.20.Wt; 87.15.Rn 相似文献
110.
WIESŁAWA NIZIOL 《Compositio Mathematica》1997,109(1):67-97
Let k be a perfect field of a positive characteristic p, K-the fraction field of the ring of Witt vectors W(k) Let X be a smooth and proper scheme over W(k). We present a candidate for a cohomology theory with coefficients in crystalline local systems: p -adic étale local systems on X_K characterized by associating to them so called Fontaine-crystals on the crystalline site of the special fiber X
k. We show that this cohomology satysfies a duality theorem. 相似文献