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1.
This paper considers the weighted extended b-splines as basis function for finite element method in electromagnetics and compares with the standard finite element method applied to the two-point boundary value problems with different boundary conditions. This new approach, which provides more accurate results than standard finite element method, is presented to compare other numerical techniques and applied to one-dimensional electromagnetic problems. Computed results are compared with other numerical results in literature. 相似文献
2.
Güllü Canan Hazar Güle 《Mathematical Methods in the Applied Sciences》2019,42(16):5398-5402
By , we denote the set of all sequences such that Σ?nan is summable V whenever Σan is summable U, where U and V are two summability methods. Recently, Sar?göl has characterized the set for k > 1,α > ?1 and arbitrary positive sequences Now, in the present paper, we characterize the sets , k > 1 and , k ≥ 1 for arbitrary positive sequences Hence we extend these results to the range α≥ ? 1. In this way, some open problems in this topic are also completed. 相似文献
3.
The photodissociation dynamics of ethynyl radical, C(2)H, involving seven electronic states is studied by classical trajectory calculations. Initial values of the trajectories are selected based on relative absorption intensities calculated by Mebel et al. The energies and the derivatives are interpolated by three-dimensional cubic spline interpolator using an extended data pool. Mean square errors and standard deviations in interpolation of energies for 450 data points are found to be in the range 3.1 x 10(-6)-1.4 x 10(-5) and 1.7 x 10(-3)-3.8 x 10(-3) hartrees, respectively. The photofragments of C(2) and H are produced mainly in the X (1)Sigma(g) (+), a (3)Pi(u), b (3)Sigma(g) (-), c (3)Sigma(u) (+), A (1)Pi(u), B (1)Delta(g) electronic states of C(2) as product. The avoided crossings do not appear to be in the main dissociation pathways. The internal distributions are in good accord with the experimental results where comparison is possible, suggesting that the fragmentation mechanism of C(2)H(2) into C(2) and H is a two step process involving C(2)H radical as an intermediate with a life time long enough to allow complete collection of the phase space in the experiments. 相似文献
4.
Foaming injected gas is a useful and promising technique for achieving mobility control in porous media. Typically, such foams are aqueous. In the presence of foam, gas and liquid flow behavior is determined by bubble size or foam texture. The thin-liquid films that separate foam into bubbles must be relatively stable for a foam to be finely textured and thereby be effective as a displacing or blocking agent. Film stability is a strong function of surfactant concentration and type. This work studies foam flow behavior at a variety of surfactant concentrations using experiments and a numerical model. Thus, the foam behavior examined spans from strong to weak.Specifically, a suite of foam displacements over a range of surfactant concentrations in a roughly 7m2, one-dimensional sandpack are monitored using X-ray computed tomography (CT). Sequential pressure taps are employed to measure flow resistance. Nitrogen is the gas and an alpha olefin sulfonate (AOS 1416) in brine is the foamer. Surfactant concentrations studied vary from 0.005 to 1wt%. Because foam mobility depends strongly upon its texture, a bubble population balance model is both useful and necessary to describe the experimental results thoroughly and self consistently. Excellent agreement is found between experiment and theory. 相似文献
5.
In this paper we study the temporal dynamics of the Co(OH) 2/NH 4OH Liesegang system with redissolution by complex formation with ammonia using UV-vis spectrophotometry with a special setup. The formation of precipitate bands is accompanied with band redissolution at the top, and because of such precipitation-redissoultion dynamics, the bands appear as a propagating wave. The spectrophotometric technique developed in this study allows us to study at the kinetics of formation of the bands and their redissolution in great details. The formation, growth, and dissolution of multiple bands are monitored by the time evolution of the absorbance. It was found that the individual band formation is sudden and takes between 15 min to half an hour to form before the next band appears. The speed of formation of bands was different for different bands and the maxima of these speeds fit a Gaussian curve. The content of cobalt hydroxide in these bands was calculated and is shown to increase to a maximum away from the interface and then decreases. The bands later grow by further precipitation. This growth was demonstrated to be nonlinear in time. On the other hand, the dissolution of bands was shown to take place simultaneously and collectively among the multiple bands under study. The effect of the concentration of Co (+2) ions on the dynamics of band formation and dissolution was studied. A time law for this Liesegang system was also determined. The system was also found to be very sensitive to temperature fluctuations. 相似文献
6.
Stoichiometric hydroxyapatite (HA) nanoparticles were synthesized by a wet chemical method. Calcium nitrate tetra hydrate used as calcium source and dibasic ammonium phosphate used as phosphorous source. Calcium nitrate tetra hydrate and dibasic ammonium phosphate solutions were prepared by dissolving the salts in distilled water. Stoichiometric hydroxyapatite nanoparticles used by artificial bone powders and synthesized by a wet chemical method were analyzed using EDXRF method.The concentrations of K, Ca, Ti, V, Cr, Fe, Ni, Cu, Sr and Pb for artificial bone powders have been determined. Besides, Calcium contents were evaluated according to the agitation time and temperature in the production process. 相似文献
7.
Karolina Kiebasa ahin Bayar Esin Apaydin Varol Joanna Srescek-Nazzal Monika Bosacka Piotr Midlicki Jarosaw Serafin Rafa J. Wrbel Beata Michalkiewicz 《Molecules (Basel, Switzerland)》2022,27(21)
Cost-effective activated carbons for CO2 adsorption were developed from molasses using H2SO4, H3PO4, HCl, NaOH, and KOH as activating agents. At the temperature of 0 °C and a pressure of 1 bar, CO2 adsorption equal to 5.18 mmol/g was achieved over activated carbon obtained by KOH activation. The excellent CO2 adsorption of M-KOH can be attributed to its high microporosity. However, activated carbon prepared using HCl showed quite high CO2 adsorption while having very low microporosity. The absence of acid species on the surface promotes CO2 adsorption over M-HCl. The pore size ranges that are important for CO2 adsorption at different temperatures were estimated. The higher the adsorption temperature, the more crucial smaller pores were. For 1 bar pressure and temperatures of 0, 10, 20, and 30 °C, the most important were pores equal and below: 0.733, 0.733, 0.679, and 0.536 nm, respectively. 相似文献
8.
We study commutativity of rings R with the property that for each nonperiodic element x of R there exists a positive integer K = K(x) such that xk is central for all k≥K. 相似文献
9.
Rahmani M Leng KW Ismail HB Hin TY Sukari MA Ali AM Kulip J 《Natural product research》2004,18(1):85-88
A new flavonoid, dihydroglychalcone-A, was isolated from the leaves extract of Glycosmis chlorosperma in addition to two known sulphur-containing amides, dambullin and gerambullin. The structure of the new compound was assigned as 2'-hydroxy-4,6'-dimethoxy-3',4'-(2",2"-dimethylpyrano)dihydrochalcone. The extract of the leaves was also found to exhibit antimicrobial and cytotoxic activities. 相似文献