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51.
52.
Yilmaz Dereli 《Numerical Methods for Partial Differential Equations》2012,28(1):235-247
In this study, traveling wave solutions of the modified regularized long wave (MRLW) equation are simulated by using the meshless method based on collocation with well‐known radial basis functions. The method is tested for three test problems which are single solitary wave motion, interaction of two solitary waves and interaction of three solitary waves. Invariant values for all test problems are calculated, also L2, L∞ norms and values of the absolute error for single solitary wave motion are calculated. Numerical results by using the meshless method with different radial basis functions are presented. Figures of wave motions for all test problems are shown. Altogether, meshless methods with radial basis functions solve the MRLW equation very satisfactorily.© 2010 Wiley Periodicals, Inc. Numer Methods Partial Differential Eq 28: 235–247, 2012 相似文献
53.
We propose a new law for the deceleration parameter that varies linearly with time and covers Berman’s law where it is constant.
Our law not only allows one to generalize many exact solutions that were obtained assuming constant deceleration parameter,
but also gives a better fit with data (from SNIa, BAO and CMB), particularly concerning the late time behavior of the universe.
According to our law only the spatially closed and flat universes are allowed; in both cases the cosmological fluid we obtain
exhibits quintom like behavior and the universe ends with a big-rip. This is a result consistent with recent cosmological
observations. 相似文献
54.
This paper is concerned with the dynamic assignment of servers to tasks in queueing networks where demand may exceed the capacity
for service. The objective is to maximize the system throughput. We use fluid limit analysis to show that several quantities
of interest, namely the maximum possible throughput, the maximum throughput for a given arrival rate, the minimum arrival
rate that will yield a desired feasible throughput, and the optimal allocations of servers to classes for a given arrival
rate and desired throughput, can be computed by solving linear programming problems. We develop generalized round-robin policies
for assigning servers to classes for a given arrival rate and desired throughput, and show that our policies achieve the desired
throughput as long as this throughput is feasible for the arrival rate. We conclude with numerical examples that illustrate
the points discussed and provide insights into the system behavior when the arrival rate deviates from the one the system
is designed for. 相似文献
55.
Borate based thermoluminescence dosimeters (TLD) show high sensitivity and good TL characteristics. One of the promising material amongst the dosimeters is Dy doped CaB4O7. Spectrally resolved thermoluminescence of Dy doped CaB4O7 shows three glow peaks at about 50 °C, 240 °C and 380 °C, the intensity of the 240 °C glow peak being the maximum. All TL experiments were conducted on a high sensitivity TL spectrometer at Sussex University with a heating rate of 50 °C min?1. Two main emissions associated with the Dy dopant are observed at ~480 and 580 nm. The samples were subjected to a series of treatments including excitation by X-rays and UV laser radiation. As part of the present research CaB4O7:Dy materials were subjected to two different heat treatments; quenching and slow cooling in order to investigate the changes in TL characteristics. 相似文献
56.
The present work reports the application of the WCl6–e?–Al–CH2Cl2 catalyst system to the ring‐opening metathesis polymerization of norbornene. Analysis of the polynorbornene microstructure by means of 1H and 13C NMR spectroscopy indicates that the polymer contains a mainly cis stereoconfiguration of the double bonds (σc = 0.61) and a blocky distribution (rtrc > 1) of cis and trans double bonds (rtrc = 3.37). This catalytic system is reluctant to facilitate the competing addition reactions of cycloalkenes while proceeding with the polymerization reactions with good conversions and at short periods. Copyright © 2004 John Wiley & Sons, Ltd. 相似文献
57.
Babu PC Sundaraganesan N Dereli Ö Türkkan E 《Spectrochimica acta. Part A, Molecular and biomolecular spectroscopy》2011,79(3):562-569
The FT-IR spectrum of 2,6-di-tert-butyl-4-methylphenol [butylated hydroxy toluene] was recorded in the region 4000-400 cm(-1). The FT-Raman spectrum of butylated hydroxy toluene was also recorded in the region 3500-50 cm(-1). The molecular structure and vibrational frequencies of butylated hydroxy toluene (BHT) have been investigated with combined experimental and theoretical study. Two stable conformers of the title compound were obtained from the result of geometry optimizations of these possible conformers. The conformer 1 is (approximately 2.6 kcal/mol) more stable than conformer 2. Geometry optimizations and vibrational frequency calculations were performed by BLYP and B3LYP methods using 6-31G(d), 6-31G(d,p) and 6-31+G(d,p) as basis sets. The scaled frequencies were compared with experimental spectrum and on the basis of this comparison; assignments of fundamental vibrational modes were examined. Comparison of the experimental spectra with harmonic vibrational wavenumbers indicates that B3LYP/6-31G(d) results are more accurate. Predicted electronic absorption spectra of BHT from TD-DFT calculation have been analyzed and compared with the experimental UV-vis spectrum. The calculated HOMO and LUMO energies show that the charge transfer occurs within the molecule. 相似文献
58.
Single crystal of gammairradiated 2,6-di-tert-butyl-4-methylphenol (BHT) was investigated using an electron paramagnetic resonance (EPR) technique at different orientations in the magnetic field at room temperatures. Taking into consideration the chemical structure and the experimental spectra of the irradiated single crystal of BHT, we assumed that one phenoxyltype paramagnetic species was produced having an unpaired electron localized at the methyl fragment side of the phenyl ring. Depending on this assumption, one possible radical was modeled using the B3LYP/6-311+G(d) level of density-functional theory. EPR parameters were calculated for these modeled radical using the B3LYP/TZVP and B3LYP/EPR-III level. The averaged value of isotropic hydrogen hyperfine coupling constants of rotating methyl functional group of phenoxyl radical is calculated for the first time. Theoretically calculated values of the modeled radical are in reasonably good agreement with the experimental data determined from the spectra (differences in averaged coupling constant values smaller than 5%, and differences in isotropic g values fall into 1 ppt). 相似文献
59.
M. Talha Gokmen Busra Dereli Bruno G. De Geest Filip E. Du Prez 《Particle & Particle Systems Characterization》2013,30(5):438-444
Existing methods for preparing complex particles, i.e., hollow porous, depend on either multiple steps or a complex reactor design. Here, a straightforward method to prepare unique polymer particles with complex shapes via the use of simple equipment and readily available chemicals is reported. Beads, capsules, and rods with uniform size and interconnected pores are obtained through the formation of high internal phase emulsion (HIPE) droplets in a microfluidic channel. The method is applicable to a broad range of (meth)acralates. Controlling physical properties, such as viscosity and emulsion stability, is key to control the shape of the resulting particles. Post‐modification of the particles via click chemistry, their application in liquid marble formation, and their use as droplet reactors are also demonstrated. 相似文献
60.
We investigate the non-minimal couplings between the electromagnetic fields and gravity through the natural logarithm of the
curvature scalar. After we give the Lagrangian formulation of the non-minimally coupled theory, we derive field equations
by a first order variational principle using the method of Lagrange multipliers. We look at static, spherically symmetric
solutions that are asymptotically flat. We discuss the nature of horizons for some candidate black hole solutions according
to various values of the parameters R
0 and a
1. 相似文献