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161.
Unsteady flow in a semi-infinite contracting or expanding pipeis reinvestigated using long series analysis. The proposed seriesmethod is useful in analysing the problem for a moderately largeconstant ( = aa/, where a = a(t), the radius of the pipe isa function of time, a(t) is the velocity of the wall, and iskinematic viscosity). For positive values of (expansion ofthe pipe) accuracy of the series representing shear stress andpressure gradient is increased from = 2.89 to = 6.0 by extractingthe singularity followed by completion of the series. For negativevalues of (contraction of the pipe), we revert the series whichresults into the increase of the region of validity of the transposedseries from = -25.0 to = -2.89. Later we use Padé approximantsfor summing them. Also, the asymptotic solution for large valuesof is obtained and it agrees closely with pure numerical valuesof shear stress at the wall and pressure gradient. 相似文献
162.
The univariate spline quasi-interpolants (QIs) studied in this paper are approximation operators using B-spline expansions
with coefficients that are linear combinations of discrete values of the function to be approximated. When working with nonuniform
partitions, the main challenge is to find QIs that have both good approximation orders and uniform norms which are bounded
independently of the given partition. Near-best QIs are obtained by minimizing an upper bound for the infinity norm of QIs
depending on a certain number of free parameters, thus reducing this norm. This paper is devoted to the study of some families
of near-best discrete quasi-interpolants (dQIs) of approximation order 3.
相似文献
163.
164.
Metal complexes of mercaptoamines—III. Different behaviour of β- and γ-(N,N-dimethyl)-mercaptoamines
The complexes Ni6(MPDMA)12, [Ni6(MPDMAH)12]X12 X = (I, ClO4) and Pd2(MPDMA)2Cl2 (MPDMA = t-S(CH2)3N(CH3)2) have been prepared and characterized. An X-ray diffraction study shows that the structure of [Ni6(MPDMAH)12] (ClO4)12 consists of a cyclic hexanuclear array of nickel atoms linked by sulphur bridging ligands. Infrared and electronic spectra show that there is no chelation in any of the nickel complexes. However, coordination through the nitrogen atoms occurs in the palladium complex. This behaviour differs from that of the homologous β-mercaptoamine, which forms monomeric chelate complexes with both nickel and palladium. 相似文献
165.
We propose a method for image encryption by multiple-step random phase encoding with an undercover multiplexing operation. The true image is stored in a multiple record we call encodegram; and then we can reconstruct it by the use of the appropriate random phase masks and a retrieval protocol. To increase the security of the true hidden image and confuse unauthorized receivers, we add to the encodegram an encoded fake image with different content. This fake image has only a small effect on the retrieval of the true hidden image, owing to the specific property of this protocol. In the decryption step, we can reveal the true image by applying the inverse protocol to two cyphertexts, one the encodegram containing the true image along with the fake image; and the other helping to get the random phase key to achieve the true image. Computer simulations verify the validity of this method for image encryption. Digital implementation of the method makes it particularly suitable for the remote transmission of information. 相似文献
166.
In this work, Fresnel's mirror and Young's double-slit experiments are compared. Numerical calculations show that Fresnel's experiment and Young's experiment present significant differences between their interference patterns when the optical source is extended rather than point-like. Those differences agree with the analogous between the overlapping of two quasi-monochromatic beams on the temporal domain (the analogous of Young's experiment) and these same beams superimposed previous modulation with sawtooth-wave (the analogous of Fresnel's interferometer). The implemented algorithms allow evaluating the cases of fully spatially coherence, fully spatially incoherence and spatially partially coherence. Computer simulations are presented to show the validity of our proposal. 相似文献
167.
O. Azzolini M. T. Barrera J. W. Beeman F. Bellini M. Beretta M. Biassoni C. Brofferio C. Bucci L. Canonica S. Capelli L. Cardani P. Carniti N. Casali L. Cassina M. Clemenza O. Cremonesi A. Cruciani A. D’Addabbo I. Dafinei S. Di Domizio F. Ferroni L. Gironi A. Giuliani P. Gorla C. Gotti G. Keppel M. Martinez S. Morganti S. Nagorny M. Nastasi S. Nisi C. Nones D. Orlandi L. Pagnanini M. Pallavicini V. Palmieri L. Pattavina M. Pavan G. Pessina V. Pettinacci S. Pirro S. Pozzi E. Previtali A. Puiu F. Reindl C. Rusconi K. Schäffner C. Tomei M. Vignati A. Zolotarova 《The European Physical Journal C - Particles and Fields》2018,78(5):428
The CUPID-0 detector hosted at the Laboratori Nazionali del Gran Sasso, Italy, is the first large array of enriched scintillating cryogenic detectors for the investigation of \(^{82}\)Se neutrinoless double-beta decay (\(0\nu \beta \beta \)). CUPID-0 aims at measuring a background index in the region of interest (RoI) for \(0\nu \beta \beta \) at the level of 10\(^{-3}\) counts/(keV kg years), the lowest value ever measured using cryogenic detectors. CUPID-0 operates an array of Zn\(^{82}\)Se scintillating bolometers coupled with bolometric light detectors, with a state of the art technology for background suppression and thorough protocols and procedures for the detector preparation and construction. In this paper, the different phases of the detector design and construction will be presented, from the material selection (for the absorber production) to the new and innovative detector structure. The successful construction of the detector lead to promising preliminary detector performance which is discussed here. 相似文献
168.
We study the stability of the Solid Fuel Model, which represents a thermal reaction of a solid material. This model corresponds to a nonlinear eigenvalue problem of two
strongly coupled nonlinear reaction–diffusion equations, with different boundary conditions on each unknown. We obtain a strong
bifurcation criterion for the steady problem and estimates for the blow-up time in the unsteady case. In addition, numerical
solutions of both the steady and unsteady problem are presented to illustrate the results. 相似文献
169.
Juancarlos Mendez-B Gilberto Gonzalez-Avalos Noe Barrera Gallegos Gerardo Ayala-Jaimes Carlos Rubio-Maya 《Entropy (Basel, Switzerland)》2022,24(9)
The bond graph methodology for modelling an integrated energy distillation column is applied in this paper. The distillation column is built by five trays for a binary mixture. However, due to its modular construction in a bond graph, the number of trays can be increased. In order to link the analysis tools of systems modeled in the bond graph to the mathematical model given to a distillation column, a junction structure of the proposed bond graph is presented. Hence, this junction structure is a way to obtain the state space representation of the modeled column in bond graphs. Likewise, it is well known that distillation columns determine a class of nonlinear systems, so throughout this paper, these systems in a bond graph approach can be analyzed. In order to learn the behavior of the distillation column in the physical domain, simulation results using 20-Sim software are shown. In addition, with the simulation of two case studies consisting of two mixtures with different relative volatilities, the versatility of the column model in a bond graph is presented. In both cases, the increase in the feed flow, the mole fraction of the light component in the feed or the distillate reflux that enriches the concentration of light in the column determine an increase in the mole fraction of light in the distillate and in the bottom reflow. Further, the control design for a distillation column in the physical domain can be extended. 相似文献
170.
A. Barrera F. TzompantziR. Gómez 《Journal of photochemistry and photobiology. A, Chemistry》2012,227(1):45-50
The photocatalytic activity of 1.0 wt% PdO supported on Al2O3-Nd2O3 binary oxides prepared by the sol-gel method was studied in the photodegradation of 2,4-dichlorophenoxyacetic acid (2,4-D). The photocatalysts were characterized by N2 physisorption, XRD and UV-vis spectroscopy. PdO supported on γ-Al2O3 photo-degrades the 2,4-D, however the addition of Nd2O3 to γ-Al2O3 notably improves the photocatalytic activity. As the concentration of Nd2O3 in the binary oxide increases from 2 to 10 wt%, the photodegradation of 2,4-D is highly enhanced. The catalytic test for PdO supported on pure Nd2O3 showed scarce photocatalytic activity. Total organic carbon (TOC) analysis showed that the 2,4-D has been completely destroyed on the PdO/Al2O3-Nd2O3 photocatalysts after 6 h under irradiation. 相似文献