排序方式: 共有69条查询结果,搜索用时 15 毫秒
1.
In the present work, according to the concept of extended homogeneous balance method and with help of Maple, we get auto-Bäcklund transformations for a (2 + 1)-dimensional nonlinear evolution equation. Subsequently, by using these auto-Bäcklund transformation, exact explicit solutions of this equation are obtained. 相似文献
2.
Ozer Atakoglu Ozge Yalcin Mustafa Gurhan Ozmen Suleyman Fatih 《Journal of Radioanalytical and Nuclear Chemistry》2021,328(2):701-706
Journal of Radioanalytical and Nuclear Chemistry - Iron phosphate glasses with melting temperatures of?~?1300 °C were developed to immobilize spent nuclear fuels. The... 相似文献
3.
A new analytical approach based on fractionation was introduced for lead in lipstick samples. Different separation techniques including n-hexane, glycerol extraction, and activated carbon adsorption were used to characterize the lipid fraction, polar and aromatic components of the samples. Additionally, artificial saliva and food stimulant extractions were used for the risk assessment studies. Trace metal levels in fractions were determined by inductively coupled plasma-mass spectrometry. Method validation parameters in the total element determinations were defined in terms of detection limits, accuracy, and precision. The limits of detection and quantification were 0.02 and 0.07 mg kg?1 for Pb; whereas the repeatability and reproducibility of the results based on percent relative standard deviation were 3.0% and 7.2% for lead, respectively. 相似文献
4.
We report the first preparation of furo- and thieno-fused 1,3-diazepine-4,6-dione derivatives starting from ethyl 2-(2-methoxy-2-oxoethyl)-3-furancarboxylate and -thiophencarboxylate. The ester functionalities connected to the hetero-ring were converted regiospecifically into the desired amides. The ester groups attached to the methylene unit were converted into isocyanates via Curtius rearrangement. The ring-closure reaction was performed in the presence of lithium bis(trimethylsilyl)amide at room temperature to give furo- and thieno-fused diazepinone derivatives. 相似文献
5.
The modified simple equation method is an interesting technique to find new and more general exact solutions to the fractional differential equations in nonlinear sciences. In this paper, the method is applied to construct exact solutions of (2+1)-dimensional conformable time-fractional Zoomeron equation and the conformable space-time fractional EW equation. 相似文献
6.
The head-on collision of a planar shock wave with a dust-air suspension is studied numerically. In this study the suspension
is placed inside a conduit adjacent to its rigid end-wall. It is shown that as a result of this collision two different types
of transmitted shock waves are possible, depending on the strength of the incident shock wave and the dust loading ratio in
the suspension. One possibility is a partially dispersed shock wave, the other is a compression wave. The flow fields resulting
in these two options are investigated. It is shown that in both cases, at late times after the head-on reflection of the transmitted
shock wave from the conduit end-wall a negative flow (away from the end-wall) is evident. The observed flow behavior may suggest
a kind of dust particle lifting mechanism that could shed new light on the complex phenomenon of dust entrainment behind sliding
shock waves.
相似文献
7.
Perfluorochemicals (PFCs) are clinically and biotechnologically important species. In this work, the potentiometric titration method in nonaqueous
media is proposed for the determination of acidity constant values of six different perfluorinated compounds. The saturated
and nonsaturated perfluoroacids, perfluorocarnosine, and perfluoroalkyl-β-alanine were potentiometrically titrated in acetonitrile,
N,N-dimethylformamide, acetone, ethanol, methanol, and pyridine with tetrabutylammonium hydroxide. The half-neutralization
potentials and acidity constants of PFCs have been calculated from the titration curves by using the computerized derivative
method. Except for RF-Carnosine, all of the potentiometric titration curves of the PFCs exhibited one stoichiometric and well-defined endpoints
in all of the solvents employed. The reproducibility and sensitivity of the method were evaluated.
The text was submitted by the authors in English. 相似文献
8.
O.O. Cellek S. Memis U. Bostanci S. Ozer C. Besikci 《Physica E: Low-dimensional Systems and Nanostructures》2004,24(3-4):318-327
We investigate different gain characteristics observed on quantum well infrared photodetectors (QWIPs) fabricated with various material systems, and the effects of barrier material properties on the device characteristics through detailed ensemble Monte Carlo simulations. When the energy spacing between the central and satellite valleys is increased, the improvement in the excited electron lifetime is found to be much stronger than that in the average electron velocity in the device. According to our results, relatively high gain observed in InP/In0.53Ga0.47As QWIPs under large bias is not due to the higher mobility in InP as suggested earlier; it can mainly be attributed to higher excited electron lifetime as a result of relatively large Γ–L energy spacing. We discuss the details of the fast part of the Al0.3Ga0.7As/GaAs QWIP transient photoresponse, which exhibits three regions with different decay characteristics under a short pulse of radiation. The duration of the final region, during which the electrons excited near the emitter are extracted from the collector, is observed to be considerably long due to the dispersion of the photoelectrons. The photoresponse time rapidly decreases with increasing bias under low bias, and nearly saturates at 10 ps under large bias being 40% larger than the average transit time estimated by dividing the device length to the average steady-state electron velocity in device. We also investigate the effects of the interface reflections on the photoresponse time. 相似文献
9.
In order to produce an accurate noise map of a city or a region, it is necessary to make noise measurements at certain locations and these measurements must be modeled with the most suitable mathematical algorithm. A homogeneous and representative distribution of the noise measurement points is the first key factor in the production of sound noise maps. The second key element is the calculation of the noise values of gridding points based on noise measurement points according to the selected mathematical calculation method and the generation of maps according to these gridding points. In this study, a noise map of the Isparta city center and its periphery was produced using inverse distance weighted (IDW), Kriging and multiquadric interpolation methods with different parameters and four grid resolution. Then, the influence of parameter selection for each method was investigated in themself by taking into account grid resolution, namely 10 ∗ 10 m, 50 ∗ 50 m, 100 ∗ 100 m and 200 ∗ 200 m, and the performance of three method with 50 ∗ 50 m grid resolution were compared with each other. In addition, the noise mapping of the city of Isparta were produced by Kriging method with respect to maximum, average and minimum noise data and they were evaluated by considering the national environmental noise thresholds. 相似文献
10.
In this article, the inverse problem of the differential inclusion theory is studied. For a given ε>0 and a continuous set valued map t→W(t), t∈[t0,θ], where W(t)⊂Rn is compact and convex for every t∈[t0,θ], it is required to define differential inclusion so that the Hausdorff distance between the attainable set of the differential inclusion at the time moment t with initial set (t0,W(t0)) and W(t) would be less than ε for every t∈[t0,θ]. 相似文献