bluuebunny/crossref_metadata_2025 huggingface dataset:
A Comparative Time Differential Perturbed Angular Correlation Study of the Nuclear Quadrupole Interaction in HfF4·HF·2H2O Using 180mHf and 181Hf(β–)181Ta as Nuclear Probes: Is Ta an Innocent Spy?
Authors: Butz Tilman , Das Satyendra K. , Manzhur Yurij
Published: February 2015

We report on a comparative study of the nuclear quadrupole interaction of the nuclear probes 180
mHf and 181Hf(β −)181Ta in HfF4
・HF・2H2O using time differential perturbed angular correlations (TDPAC) at 300 K. For the first probe, assuming a Lorentzian frequency distribution, we obtained ω
Q
= 103(4) Mrad/s, an asymmetry parameter η = 0.68(3), a linewidth δ = 7.3(3.9)%, and full anisotropy within experimental accuracy. For the second probe, assuming a Lorentzian frequency distribution, we obtained three fractions: (1) with 56.5(7)%, ω
Q
= 126.64(4) Mrad/s and η = 0.9241(4) with a rather small distribution δ = 0.40(8)% which is attributed to HfF4
・HF・2H2O; (2) with 4.6(4)%, ωQ = 161.7(3) Mrad/s and η = 0.761(4) assuming no line broadening which is tentatively attributed to a small admixture of Hf2OF6
・H2O; (3) the remainder of 39.0(7)% accounts for a rapid loss of anisotropy and is modelled by a perturbation function with a sharp frequency multiplied by an exponential factor exp(−λ t) with λ = 0.55(2) ns−1. Whereas the small admixture of Hf2OF6
・H2O escapes detection by the 180
mHf probe, there is no rapid loss of roughly half the anisotropy as is the case with 181Hf(β −)181Ta. This loss could in principle be due to fluctuating electric field gradients originating from movements of nearest neighbour HF adducts and/or H2O molecules after nuclear transmutation to the foreign atom Ta which are absent for the isomeric probe. Alternatively, paramagnetic Ta ions could lead to fluctuating magnetic dipole fields which, when combined with fluctuating electric field gradients, could also lead to a rapid loss of anisotropy. In any case, Ta is not an “innocent spy” in this compound. Although 180
mHf is not a convenient probe for conventional spectrometers, the use of fast digitizers and software coincidences would allow to use all γ -quanta in the stretched cascade which would greatly improve the efficiency of the spectrometer. 180
mHf could also serve as a Pu analogue in toxicity studies.
EPR Spectra of Some Cu2+-Doped Metal Carbonates and Disorder Phase Transition in K3H(CO3)2
Authors: Demir Dilek , Köksal Fevzi , Kazak Canan , Köseoğlu Rahmi
Published: February 2015

Cu2+-doped K3H(CO3)2, Rb2CO3, and Rb2KH(CO3)2 single crystals were investigated by electron paramagnetic resonance (EPR) spectroscopy. The EPR spectrum of K3H(CO3)2 indicates two different sites for Cu2+ at room and at low temperatures. But the signals for the two sites overlap at 318 K which is attributed to a disorder phase transition. Each of the other compounds exhibits one site. The Cu2+ ion seems to substitute the K+ and Rb+ ions and the charge compensations are fulfilled by the proton vacancies in K3H(CO3)2, and another K+ and Rb+ in the other compounds. The spin Hamiltonian parameters g and A for each compound are determined and discussed.
A Common Selection Rule for Organic Reactions in Terms of Signs of Direct and Indirect Interorbital Interactions
Authors: Gineityte Viktorija
Published: February 2015

The semilocalized approach to chemical reactivity suggested recently is overviewed with respect to both theory and applications. The principal attention is paid to formulation of a common selection rule for organic reactions and to demonstration of its validity to various heterolytic (i. e. nucleophilic and electrophilic) and pericyclic processes. The total energy of the whole reacting system (E) is represented in this approach in the form of power series with respect to all interfragmental interactions (fragments coincide with individual chemical bonds, phenyl rings, etc.). For any reaction, a certain decisive k-th-order energy correction E
(k) may be revealed, the sign of which depends on the actual way of the process. The allowed and forbidden reactions are then defined as those described by negative (stabilizing) and positive (destabilizing) corrections E
(k), respectively. The condition which ensures the negative sign of E
(k) resolves itself into a universal requirement of coinciding signs of the principal direct and indirect interactions of basis orbitals localized on separate fragments (e. g. bond orbitals). This result forms the basis for the above-mentioned selection rule. Allowed (forbidden) ways of heterolytic reactions are exemplified by the back (frontal) attack of a nucleophile upon a substituted alkane in the SN2 process, the meta (ortho, para) attacks of electrophile upon the pyridine molecule, the addition of electrophile to the Cβ (Cα ) atom of a donor-containing derivative of ethene (D-CαH=Cβ H2), the trans (cis)-β -elimination processes of substituted alkanes, etc. Application of the same rule to pericyclic reactions is demonstrated to yield predictions coinciding with those of other approaches including the famous Woodward-Hoffmann rule.
Computing the Fourier Transform via Homotopy Perturbation Method
Authors: Babolian Esmail , Saeidian Jamshid , Paripour Mahmood
Published: February 2015

In this paper, the homotopy perturbation method (HPM) is applied to compute the Fourier transform (FT) of functions on R. The basic properties of the Fourier transform are again obtained by HPM and examples assuring the applicability of HPM are presented.
A Direct Transformation Method and its Application to Variable Coefficient Nonlinear Equations of Schrödinger Type
Authors: Zhang Li-Hua , Liu Xi-Qiang
Published: February 2015

In this paper, the generalized variable coefficient nonlinear Schrödinger (NLS) equation and the cubic-quintic nonlinear Schrödinger (CQNLS) equation with variable coefficients are directly reduced to simple and solvable ordinary differential equations by means of a direct transformation method. Taking advantage of the known solutions of the obtained ordinary differential equations, families of exact nontravelling wave solutions for the two equations have been constructed. The characteristic feature of the direct transformation method is, that without much extra effort, we circumvent the integration by directly reducing the variable coefficient nonlinear evolution equations to the known ordinary differential equations. Another advantage of the method is that it is independent of the integrability of the given nonlinear equation. The method used here can be applied to reduce other variable coefficient nonlinear evolution equations to ordinary differential equations.
New Solitary Wave Solution for the Boussinesq Wave Equation Using the Semi-Inverse Method and the Exp-Function Method
Authors: Liu Wenjun
Published: February 2015

Using the semi-inverse method, a variational formulation is established for the Boussinesq wave equation. Based on the obtained variational principle, solitary solutions in the sech-function and expfunction forms are obtained
Molecular Structure, Vibrational Spectra and Chemical Shift Properties of C12H9ClO4 and C12H9BrO4 Crystals by Density Functional Theory and ab initio Hartree-Fock Calculations
Authors: Günay Nergin , Tarcan Erdogan , Avcı Davut , Esmer Kadir , Atalay Yusuf
Published: February 2015

The molecular geometry, vibrational spectra, and gauge including atomic orbital (GIAO), individual gauges for atoms in molecules (IGAIM), and continuous set of gauge transformations (CSGT) 1H and 13C chemical shift values of ethyl 6-chloro-2-oxo-2H-chromene-3-carboxylate (C12H9ClO4-(I)) and ethyl 6-bromo-2-oxo-2H-chromene-3-carboxylate (C12H9BrO4-(II)) in the ground state have been calculated by using the Hartree-Fock (HF) and density functional method (B3LYP) with 6- 31G+(d,p) basis set. The results of the optimized molecular structure are presented and compared with the experimental X-ray diffraction. The computed vibrational frequencies were used to determine the types of molecular motions associated with the spectra of the experimental bands observed. Also, calculated 1H and 13C chemical shift values were compared with the experimental ones.
Surface Magnetic Effects in an Alternating Superlattice
Authors: Xu Zhi , Kuang Xiao-Yu
Published: February 2015

We investigate the surface magnetism of the alternating superlattice with localized spin-1/2. Using

the mean-field approximation method, we discuss not only the correlation between the critical value

j0C of the exchange constant in the surface layer and interlayer exchange constants, but also the connection

between j0C and the bulk exchange constant jA. The calculated results are in good agreement

with the former theoretical calculations. Based on the solutions, we show the relations between the

critical parameter c = JS/JA and the bulk exchange constants as well as the surface transition temperature.

JS is the exchange constant in the first two surface layers. Comparing with the earlier theoretical

works, our results show the effect of the surface modification more gradual.
Study of Thermodynamic and Transport Properties of Glycine, Diglycine, and Triglycine in Aqueous Tartrazine at Different Temperatures
Authors: Ali Anwar , Patel Rajan , Khan Shahjahan , Bhushan Vidiksha
Published: February 2015

The densities (ρ), viscosities (η), and refractive indices (nD) of (0.01, 0.05, 0.10, 0.15, and 0.20 m) amino acid, glycine, and peptides, diglycine and triglycine in 0.01 m aqueous tartrazine solution were determined at 288.15, 293.15, 298.15, 303.15, 308.15, and 313.15 K. The density data were utilized to evaluate apparent molar volumes (φv) which, in turn, were used to determine partial molar volumes (φv ◦) using Masson’s equation. The transfer volumes were also calculated. The viscosity data were analyzed using the Jones-Dole equation to determine the viscosity coefficients and the activation parameters. The activation parameters of viscous flow were obtained to throw light on the mechanism of viscous flow. The molar refraction was calculated using the refractive index data. The results were interpreted in the light of ion-ion, ion-nonpolar, and nonpolar-nonpolar interactions and the effect of increasing hydrophobicity as we move from glycine to triglycine on these interactions in presence of the dye tartrazine was also investigated.
Role of Oxygen on Phase Behaviour of Benzylidene Aniline – A Comparative Study
Authors: Ajeetha Narayana , Ojha Durga P.
Published: February 2015

Four structurally related Schiff’s base compounds are synthesized and their mesogenic properties are characterized by using Thermal Microscopy (TM) and Differential Scanning Calorimetry (DSC). The position of oxygen is varied from either sides of the bridging site, oxygen introduced on both sides and the oxygen is removed from the bridging site for the values of n = 8 and m = 5. The influence of oxygen atom to the extent of increase in thermal range, depression in melting temperature, elevation of clearing temperature is observed for all four compounds, viz. N (p-n-Octyloxy benzylidene) p-n-Pentyl aniline (8O.5), N (p-n-Octyl benzylidene) p-n-Pentyloxy aniline (8.O5), N (p-n-Octyloxy benzylidene) p-n-Pentyloxy aniline (8O.O5), and N (p-n-Octyl benzylidene) p-n- Pentyl aniline (8.5). The shift in the position of oxygen from the aldehyde to the aniline side and the removal of oxygen has a greater effect as they become room temperature liquids, whereas the oxygen on the aldehyde side and the oxygen on both sides of the rigid core moiety effect only the clearing temperatures. The results obtained are discussed in the light of the earlier data available on Schiff’s base nO.m compounds
Response to the Comment by A. Georges on the Author’s Paper “Nonlinear Models for Relativity Effects in Electromagnetism, Z. Naturforsch. 64a, 327 (2009)”
Authors: Devasia Santosh
Published: February 2015

Responses to the comments in A. Georges, Z. Naturforsch. 64a, 872 (2009) on the author’s paper are given
The Dispersion Relation for the 1/sinh2 Potential in the Classical Limit
Authors: Campbell Joel
Published: February 2015

The dispersion relation for the inverse hyperbolic potential is calculated in the classical limit. This is shown for both the low amplitude phonon branch and the high amplitude soliton branch. It is shown that these results qualitatively follow the previously found ones for the inverse squared potential where explicit analytic solutions are known
Alignment of Buckingham Parameters to Generalized Lennard-Jones Potential Functions
Authors: Lim Teik-Cheng
Published: February 2015

The Lennard-Jones(12-6) and the Exponential-6 potential functions are commonly used in computational softwares for describing the van der Waals interaction energy. Some softwares allow switching between these two potentials under prescribed condition(s) that attempt to connect the parameter relationship between the two functions. Here we propose a technique by which the parameter relationship between both potentials is extracted by simultaneously imposing an equal force constant at the well depth’s minimum and an equal mean interatomic energy from the point of equilibrium to the point of total separation. The former imposition induces good agreement for the interatomic compression and a small change in the interatomic distance near the equilibrium while the latter enables good agreement for large interatomic separation. The excellent agreement exhibited by the plots validates the technique of combined criteria proposed herein
Metal Binding by Humic Substances – Characterization by High-Resolution Lanthanoide Ion Probe Spectroscopy (HR-LIPS)
Authors: Marmodée Bettina , Klerk Joost de , Ariese Freek , Gooijer Cees , Kumke Michael U.
Published: February 2015

In ultra-low-temperature experiments at 4.7 K the luminescence of Eu(III) bound to different hydroxy- and methoxybenzoic acids and to humic substances (HS) was investigated. The benzoic acid derivatives were used as simple model compounds for common metal-binding structures in HS. The Eu(III) luminescence was directly excited by means of a pulsed dye laser, scanning through the 5D0 ← 7F0 transition of Eu(III) and subsequently high-resolution total luminescence spectra (TLS) were recorded. Based on the thorough analysis of the high-resolution TLS conclusions were drawn with respect to the number of different complexes formed and to the symmetry of the complexes. The crystal-field strength parameter Nν (B2q) was dependent on the electrostatic forces induced by the ligands as well as on the symmetry of the complexes. The formation of thermodynamically stable complexes was found to be slow even for small model ligands such as 2-hydroxybenzoic acid. Comparison between the model compounds and HS clearly revealed that the carboxylate group is the dominant binding site in HS. Indices for the formation of chelates, e. g. similar to 2-hydroxybenzoic acid, were not found for HS
Defective BN Nanotubes: A Density Functional Theory Study of B-11 and N-14 NQR Parameters
Authors: Giahi Masoud , Mirzaei Mahmoud
Published: February 2015

A density functional theory (DFT) study is performed to investigate the influence of structural defects on the electronic structure properties of perfect boron nitride nanotubes (BNNTs). To this aim, as representative models, the single-walled (6,0) BNNT consisting of 36 boron, 36 nitrogen, and 12 hydrogen atoms and the single-walled (4,4) BNNT consisting of 36 boron, 36 nitrogen, and 16 hydrogen atoms are considered. The nuclear quadrupole resonance (NQR) parameters are calculated and compared in two perfect and defective models of the considered BNNTs. The results indicate that due to formation of non-hexagonal rings in the defective model because of removing a B-N bond, the NQR parameters at the sites of first neighbouring nuclei are significantly influenced by imposed perturbation, however, the sites of other nuclei, farther from perturbation, remain almost unchanged. The calculations are performed at the level of the BLYP method and 6-31G* standard basis set using the GAUSSIAN 98 package
Existence, Asymptotic Behaviour, and Blow up of Solutions for a Class of Nonlinear Wave Equations with Dissipative and Dispersive Terms
Authors: Polat Necat , Kaya Doğan
Published: February 2015

We consider the existence, both locally and globally in time, the asymptotic behaviour, and the blow up of solutions to the initial boundary value problem for a class of nonlinear wave equations with dissipative and dispersive terms. Under rather mild conditions on the nonlinear term and the initial data we prove that the above-mentioned problem admits a unique local solution, which can be continued to a global solution, and the solution decays exponentially to zero as t →+∞. Finally, under a suitable condition on the nonlinear term, we prove that the local solutions with negative and nonnegative initial energy blow up in finite time.
Novel Asymptotic SolitonWaves for the Nonlinear Schrödinger Equation with Varying Gain/Loss and Frequency Chirping
Authors: Lai Xian-Jing , Zhang Jie-Fang
Published: February 2015

This paper analysis spatial asymptotic waves propagation in nonuniform optical fiber. It finds an appropriate transformation such that the nonlinear variable-coefficient Schr¨odinger equation transform into the nonlinear Schr¨odinger equation with varying gain/loss and frequency chirping. It obtains solitonlike and periodic self-similar asymptotic waves by using the transformation. We analyze the evolution properties of some novel self-similar solutions. In addition, the nature of our self-similar asymptotic wave hints to the possibility of designing optical amplifier and focusing of spatial waves to overcome inevitable energy losses while performing in the optical nonlinear media.
Nonlinear Ion Acoustic Waves in a Magnetized Dusty Plasma in the Presence of Nonthermal Electrons
Authors: Saha Taraknath , Chatterjee Prasanta , Amin Mohamed Ruhul
Published: February 2015

The Kadomtsev-Petviashili (KP) equation is derived for weakly nonlinear ion acoustic waves in a magnetized dusty plasma in the presence of nonthermal electrons. Soliton solutions are obtained in both the one-dimensional and two-dimensional framework. For the one-dimensional soliton solution the ‘tanh’ method is considered while the two-dimensional solution is obtained by a method introduced by S.V. Manacov et al., Phys. Lett. A 63, 205 (1977). It is found that in case of the onedimensional solution, both compressive and rarefactive solitary waves exist which could be obtained depending on the ratio of the electron and ion density. It is also seen that the nonthermal distribution of electrons has some significant effect in the shape of both the one-dimensional and two-dimensional solitary wave.
Thermodynamic Properties of CaSiO3 Perovskite at High Pressure and High Temperature
Authors: Liu Zi-Jiang , Tan Xiao-Ming , Guo Yuan , Zheng Xiao-Ping , Wu Wen-Zhao
Published: February 2015

The thermodynamic properties of tetragonal CaSiO3 perovskite are predicted at high pressures and temperatures using the Debye model for the first time. This model combines the ab initio calculations within local density approximation using pseudopotentials and a plane wave basis in the framework of density functional theory, and it takes into account the phononic effects within the quasi-harmonic approximation. It is found that the calculated equation of state is in excellent agreement with the observed values at ambient condition. Based on the first-principles study and the Debye model, the thermal properties including the Debye temperature, the heat capacity, the thermal expansion and the entropy are obtained in the whole pressure range from 0 to 150 GPa and temperature range from 0 to 2000 K.
The Solution of the Variable Coefficients Fourth-Order Parabolic Partial Differential Equations by the Homotopy Perturbation Method
Authors: Dehghan Mehdi , Manafian Jalil
Published: February 2015

In this work, the homotopy perturbation method proposed by Ji-Huan He [1] is applied to solve both linear and nonlinear boundary value problems for fourth-order partial differential equations. The numerical results obtained with minimum amount of computation are compared with the exact solution to show the efficiency of the method. The results show that the homotopy perturbation method is of high accuracy and efficient for solving the fourth-order parabolic partial differential equation with variable coefficients. The results show also that the introduced method is a powerful tool for solving the fourth-order parabolic partial differential equations.
Optimum Path of a Flying Object with Exponentially Decaying Density Medium
Authors: Abbasbandy Said , Pakdemirli Mehmet , Shivanian Elyas
Published: February 2015

In this paper, a differential equation describing the optimum path of a flying object is derived. The density of the fluid is assumed to be exponentially decaying with altitude. The equation is cast in to a dimensionless form and the exact solution is given. This equation is then analyzed by homotopy analysis method (HAM). The results showed in the figures reveal that this method is very effective and convenient.
Application of Variational Iteration Method for nth-Order Integro-Differential Equations
Authors: Abbasbandy Said , Shivanian Elyas
Published: February 2015

In this paper, the variational iteration method is proposed to solve Fredholm’s nth-order integrodifferential equations. The initial approximation is selected wisely which satisfies the initial conditions. The results reveal that this method is very effective and convenient in comparison with other methods.
Energy Level Crossing and Entanglement
Authors: Steeb Willi-Hans
Published: February 2015

We consider a Hamilton operator in a finite dimensional Hilbert space with energy level crossing. We discuss the question how energy level crossing and entanglement of states in this Hilbert space are intertwined. Since energy level crossing is related to symmetries of the Hamilton operator we also derive these symmetries and give the reduction to the invariant Hilbert subspaces.
A Low Field Fluorine-Electron Double Resonance Study for GALV and BDPA in Some Aliphatic and Aromatic Solvents
Authors: Peksoz Ahmet , Yalciner Aytac , Cimenoglu Mehmet Akif
Published: February 2015

Dynamic nuclear polarization experiments were performed to study the solutions of the stable free radicals Galvinoxyl and α,γ -Bisdiphenylene-β -phenyl allyl complex with benzene (1 : 1) in some highly fluorinated aliphatic and aromatic solvents. The measurements were performed at four different temperatures to test the dipolar and the scalar part of the coupling between the fluorine nucleus (19F) and the unpaired electron. It was found that in the samples with Galvinoxyl the dipolar interactions are more effective for the aromatic solvents, while the scalar interactions are more effective for the aliphatics. An alteration from negative to positive region for the nuclear-electron coupling parameter informing on scalar or dipole-dipole interaction was observed only for 2,2,3,4,4,4-Hexafluoro- 1-butanol solvent with increasing temperature. The nuclear-electron coupling parameter varies between −0.003 and 0.228 in all aliphatic solvents and between 0.180 and 0.318 in aromatic solvents. Overhauser enhancement was not observed in the samples prepared with Hexadecafluoroheptane, Heptafluorobutyric acid, and Nonafluoropentanoic acid for both free radicals in all temperatures. These solvents may have scavenging effects on the radicals due to their behaviour.
Electrochemical Behaviour and Electrorefining of Cobalt in NaCl-KCl-K2TiF6 Melt
Authors: Kuznetsov Sergey A. , Kazakova Olga S. , Makarova Olga V.
Published: February 2015

The electrorefining of cobalt in NaCl-KCl-K2TiF6 (20 wt%) melt has been investigated. It was shown that complexes of Ti(III) and Co(II) appeared in the melt due to the reaction 2Ti(IV) + Co → 2Ti(III) + Co(II) and this reaction was entirely shifted to the right hand side. On the base of linear sweep voltammetry diagnostic criteria it was found that the discharge of Co(II) to Co metal is controlled by diffusion. The limiting current density of discharge Co(II) to metal in NaCl-KCl-K2TiF6 (20 wt%) melt was determined by steady-state voltammetry. The electrorefining of cobalt was carried out in hermetic electrolyser under argon atmosphere. Initial cathodic current density was changed from 0.2 Acm−2 up to 0.7 Acm−2, the electrolysis temperature varied within 973 - 1123 K. Behaviour of impurities during cobalt electrorefining was discussed. It was shown that electrorefining led to the elimination of most of the interstitial impurities (H2, N2, O2, C), with the result that the remaining impurity levels below 10 ppm impart high ductility to cobalt.
Characterization of Pure and Mixed Langmuir and Langmuir-Blodgett Films of Some Fluorescent Naphthalimide Dyes
Authors: Bielejewska Natalia , Stolarski Roland , Bauman Danuta
Published: February 2015

Langmuir and Langmuir-Blodgett (LB) films formed of some fluorescent dyes, derivatives of 4-aminonaphthalimide, and their binary mixtures with the liquid crystal 4-heptyl-4’-cyanobiphenyl (7CB) have been studied. Surface pressure versus mean molecular area isotherms for Langmuir films have given information about the alignment of molecules in a monomolecular layer at the air/water interface. The absorption and fluorescence spectra of LB films have revealed the occurrence of aggregates among dye molecules. In the ground electronic state some fraction of aggregates of J-type have appeared, while in the excited state the excimers have been created. The latter statement has been confirmed by additional absorption and fluorescence measurements performed for dyes dissolved in 7CB and placed in sandwich cells of 10 μm in thickness.
Viscosity of Mixtures of α-Tocopherol Acetate + Mesitylene
Authors: Szwajczaka Elżbieta , Stagraczyński Ryszard , Herba Henryk , Świergielb Jolanta , Jadżyn Jan
Published: February 2015

The paper presents results of the share viscosity measurements performed as a function of temperature and concentration for mixtures of α-tocopherol acetate (vitamine E acetate) and mesitylene, two liquids of essentially different viscosity (four order of magnitude difference at 280 K). The viscosity/ temperature dependence for pure α-tocopherol acetate as well as for the mixtures studied can be well described with the Vogel-Fulcher-Tammann equation. The viscosities of the mixtures exhibit a strong negative deviation from the rule of additive dependence on concentration and for increasing temperature the maximum value of the deviation shows an exponential decreasing.
Local Structure Determination of Tetragonal Cr2+ Center in CdS Semiconductor
Authors: Tan Xiao-Ming , Kuang Xiao-Yu , Zhou Kang-Wei
Published: February 2015

Recently, many studies for the local structure of 3d5 ions in octahedrally coordinated compounds are made by simulating the EPR parameters on the basis of the complete energy matrix. However, for the 3d4 ions in tetrahedrally coordinated compounds, the studies are relatively fewer. In this work, by diagonalizing the complete energy matrix for a d4 configuration in a tetragonal ligand-field within a strong-field representation, the local structure around Cr2+ in CdS crystal is studied. Our results show that there exists a compression distortion in the local lattice structure. From our calculations, the distortion parameters ΔR = −0.022 A° and Δθ = −1.410° are obtained.
Symmetry Reduction, Exact Solutions, and Conservation Laws of the (2+1)-Dimensional Dispersive Long Wave Equations
Authors: Dong Zhong Zhou , Chen Yong
Published: February 2015

By means of the generalized direct method, we investigate the (2+1)-dimensional dispersive long wave equations. A relationship is constructed between the new solutions and the old ones and we obtain the full symmetry group of the (2+1)-dimensional dispersive long wave equations, which includes the Lie point symmetry group S and the discrete groups D. Some new forms of solutions are obtained by selecting the form of the arbitrary functions, based on their relationship. We also find an infinite number of conservation laws of the (2+1)-dimensional dispersive long wave equations.
Application of the Elliptically Polarized Radio Frequency Fields in Spin-3/2 Nuclear Quadrupole Resonance Spectroscopy
Authors: Sklyar Anna , Sinyavsky Nikolay , Ostafin Michal , Nogaj Boleslaw
Published: February 2015

A possibility to excite the spin-3/2 quadrupolar nuclei in sites with a non-zero asymmetry parameter of the electric field gradient (EFG) tensor by means of an elliptically polarized radio frequency (RF) magnetic fields is discussed. Closed analytical formulas for the intensities of nuclear quadrupole resonance (NQR) nutation spectra and nutation frequencies of powder samples were obtained. Characteristic singularities in the nutation spectra were determined which allow the measurement of the asymmetry parameter η. It was found that in the general case of η ≠ 0 the excitation of the nuclear

spins in +m and −m states by using the circularly polarized RF fields is not fully selective.
Total Electron Scattering Cross Sections of He, Ne, Ar, Kr and Xe in the Energy Range 100 eV to 10 000 eV
Authors: Tan Xiao-Ming , Yang Chuan-Lu , Wang Mei-Shan , Zhang Zhi-Hong
Published: February 2015

The total cross sections for electron scattering from He, Ne, Ar, Kr and Xe in the energy range from 100 eV to 10 000 eV have been calculated based on the optical-model potential. Our theoretical results are compared with the available experimental data. The consistency between them is also discussed. At higher energies (over 2000 eV for He, over 5000 eV for Ne, Ar, Kr and Xe), the total cross sections of electron scattering from these atoms are scarce, so our calculations will give a reference for further experimental and theoretical studies.
Exact Solutions for a Class of Nonlinear Singular Two-Point Boundary Value Problems: The Decomposition Method
Authors: Ebaid Abd Elhalim
Published: February 2015

Many problems in applied mathematics and engineering are usually formulated as singular two-point boundary value problems. A well-known fact is that the exact solutions in closed form of such problems were not obtained in many cases. In this paper, the exact solutions for a class of nonlinear singular two-point boundary value problems are obtained to the first time by using Adomian decomposition method
Analytical and Numerical Solutions of a Generalized Hyperbolic Non-Newtonian Fluid Flow
Authors: Pakdemirli Mehmet , Sarı Pınar , Solmaz Bekir
Published: February 2015

The generalized hyperbolic non-Newtonian fluid model first proposed by Al-Zahrani [J. Petroleum Sci. Eng. 17, 211 (1997)] is considered. This model was successfully applied to some drilling fluids with a better performance in relating shear stress and velocity gradient compared to power-law and the Hershel-Bulkley model. Special flow geometries namely pipe flow, parallel plate flow, and flow between two rotating cylinders are treated. For the first two cases, analytical solutions of velocity profiles and discharges in the form of integrals are presented. These quantities are calculated by numerically evaluating the integrals. For the flow between two rotating cylinders, the differential equation is solved by the Runge-Kutta method combined with shooting. For all problems, the power-law approximation of the model is compared with the generalized hyperbolic model, too.
Homotopy Solution for Non-Similarity Boundary-Layer Flow near a Stagnation Point
Authors: You Xiangcheng , Xu Hang
Published: February 2015

In this paper, non-similarity boundary-layer flow of a Newtonian fluid near an asymmetric plane stagnation point with a dimensionless external flow velocity ue = x/(x+1) is studied. The original boundary-layer equations are transferred into a nonlinear partial differential equation (PDE) with variable coefficients. An analytic technique for strongly nonlinear equations, namely the homotopy analysis method (HAM), is applied to replace the nonlinear PDE by an infinite number of linear ordinary differential equations (ODEs) with constant coefficients. An artificial parameter, called the convergence-control parameter, is introduced to ensure the convergence of solution series. Accurate analytical approximations of skin friction and boundary-layer thickness are obtained, and the effect of the external flow velocity on the non-similarity flows is investigated. This approach has general meanings and can be applied to many other non-similarity boundary-layer flows.
New Soliton Solutions of Chaffee-Infante Equations Using the Exp-Function Method
Authors: Sakthivel Rathinasamy , Chun Changbum
Published: February 2015

In this paper, the exp-function method is applied by using symbolic computation to construct a variety of new generalized solitonary solutions for the Chaffee-Infante equation with distinct physical structures. The results reveal that the exp-function method is suited for finding travelling wave solutions of nonlinear partial differential equations arising in mathematical physics
Magneto Thermal Convection in a Compressible Couple-Stress Fluid
Authors: Singh Mahinder , Kumar Pardeep
Published: February 2015

The problem of thermal instability of compressible, electrically conducting couple-stress fluids in the presence of a uniform magnetic field is considered. Following the linearized stability theory and normal mode analysis, the dispersion relation is obtained. For stationary convection, the compressibility, couple-stress, and magnetic field postpone the onset of convection. Graphs have been plotted by giving numerical values of the parameters to depict the stability characteristics. The principle of exchange of stabilities is found to be satisfied. The magnetic field introduces oscillatory modes in the system that were non-existent in its absence. The case of overstability is also studied wherein a sufficient condition for the non-existence of overstability is obtained.
Soliton Solution, Bäcklund Transformation, and Conservation Laws for the Sasa-Satsuma Equation in the Optical Fiber Communications
Authors: Liu Ying , Gao Yi-Tian , Xu Tao , Lü Xing , Sun Zhi-Yuan , Meng Xiang-Hua , Yu Xin , Gai Xiao-Ling
Published: February 2015

Under investigation in this paper, with symbolic computation, is the Sasa-Satsuma (SS) equation which can describe the propagation of ultra short pulses in optical fiber communications. By virtue of the Ablowitz-Kaup-Newell-Segur procedure, the Lax pair for the SS equation is directly established. Based on such a Lax pair, a Bäcklund transformation is constructed, through which the explicit onesoliton solution is derived.Meanwhile, an infinite number of conservation laws is provided to indicate the integrability of the SS equation in the Liouville sense. To further understand the stability of the one-soliton solution, we employ the split-step Fourier method to simulate the propagation of the soliton pulses under the finite initial perturbations. In addition, the interaction of two adjacent pulses with different separation distances is investigated through numerical simulation. Analytic and numerical results discussed in this paper are expected to be applied to the description of the optical pulse propagation.
Approximate Solution of Generalized Ginzburg-Landau-Higgs System via Homotopy Perturbation Method
Authors: Lu Ju-Hong , Zheng Chun-Long
Published: February 2015

Using the homotopy perturbation method, a class of nonlinear generalized Ginzburg-Landau-Higgs systems (GGLH) is considered. Firstly, by introducing a homotopic transformation, the nonlinear problem is changed into a system of linear equations. Secondly, by selecting a suitable initial approximation, the approximate solution with arbitrary degree accuracy to the generalized Ginzburg- Landau-Higgs system is derived. Finally, another type of homotopic transformation to the generalized Ginzburg-Landau-Higgs system reported in previous literature is briefly discussed.
Integrability Test and Travelling-Wave Solutions of Higher-Order Shallow- Water Type Equations
Authors: Maldonado Mercedes , Molinero María Celeste , Pickering Andrew , Prada Julia
Published: February 2015

We apply the Weiss-Tabor-Carnevale (WTC) Painlev´e test to members of a sequence of higher-order shallow-water type equations. We obtain the result that the equations considered are non-integrable, although compatibility conditions at real resonances are satisfied. We also construct travelling-wave solutions for these and related equations.
Application of He’s Variational Iteration Method to Nonlinear Integro-Differential Equations
Authors: Yildirim Ahmet
Published: February 2015

In this paper, an application of He’s variational iteration method is applied to solve nonlinear integro-differential equations. Some examples are given to illustrate the effectiveness of the method. The results show that the method provides a straightforward and powerful mathematical tool for solving various nonlinear integro-differential equations
Application of the Decomposition Method of Adomian for Solving the Pantograph Equation of Order m
Authors: Shakeri Fatemeh , Dehghan Mehdi
Published: February 2015

In many fields of the contemporary science and technology, systems with delaying links often appear. By a delay differential equation (DDE), we mean an evolutionary system in which the (current) rate of change of the state depends on the historical status of the system. Delay models play a relevant role in different fields such as biology, economy, control, and electrodynamics and hence have been attracted a lot of attention of the researchers in recent years. In this study, the numerical solution of a well-known delay differential equation, namely, the pantograph equation is investigated by means of the Adomian decomposition method and then a numerical evaluation is included to demonstrate the validity and applicability of this procedure
Effect of Carbon Content on the Mechanical Properties of Medium Carbon Steels
Authors: Calik Adnan , Duzgun Akin , Sahin Osman , Ucar Nazim
Published: February 2015

The mechanical properties of medium-carbon steels with a carbon content ranging from 0.30 to 0.55 wt.% were investigated by tensile and microhardness tests at room temperature. It was observed that the higher carbon content results in an increase in yield stress and ultimate tensile stress, while the elongation remains essentially constant. The results were explained by the hindering of dislocation motion associated with solid solution hardening
Reconstruction of the Diffusion Operator from Nodal Data
Authors: Yang Chuan-Fu
Published: February 2015

In this paper, we deal with the inverse problem of reconstructing the diffusion equation on a finite interval. We prove that a dense subset of nodal points uniquely determine the boundary conditions and the coefficients of the diffusion equation. We also provide constructive procedure for them.
Quantum-Chemical ab initio Calculations on the Three Isomers of Diborabenzene (C4H4B2)
Authors: Singh Jaswinder , Wang Yuekui , Raabe Gerhard
Published: February 2015

Quantum-chemical ab initio calculations up to the ZPE+CCSD(T)/aug-cc-pVTZ//MP2/6- 311++G** level were performed on three possible structural isomers of diborabenzene (C4H4B2). All three molecules were found to be local minima on the C4H4B2 energy surface and to have closed shell singlet ground states. While the ground states of the 1,3- and 1,4-isomer are planar and of C2v and D2h symmetry, respectively, 1,2-diborabenzene is non-planar with a C2 axis passing through the center of the BB bond and the middle of the opposite carbon-carbon bond as the only symmetry element. The energetically most favourable 1,3-diborabenzene was found to be about 19 and 36 kcal/mol lower in energy than the 1,2- and the 1,4-isomer. Planar 1,3- and 1,4-diborabenzene have three doubly occupied π orbitals while non-planar 1,2-diborabenzene has also three doubly occupied orbitals which can be derived from the π orbitals of its 3.7 kcal/mol energetically less favourable planar form (“π-like” orbitals). The lowest unoccupied orbitals of all three isomers have σ symmetry with large coefficients at the two boron atoms. These orbitals are lower in energy than the lowest unoccupied molecular orbitals (LUMOs) of e. g. benzene and pyridine and might cause pronounced acceptor properties which could be one of the reasons for the elusiveness of the title compounds. The results of bond separation reactions show that cyclic conjugation stabilizes all three diborabenzenes relative to their isolated fragments. The most effective stabilization energy of about 24 kcal/mol was found for the energetically lowest 1,3-isomer. This value amounts to approximately one third of the experimental value for the bond separation energy of pyridine. In all cases the energetically lowest triplet states are significantly (16 - 24 kcal/mol) higher in energy than the singlet ground states. Also among the triplets the 1,3-isomer is the energetically most fabourable species.
Short and Medium-Range Order in Liquid Ternary Al80Co10Ni10, Al72.5Co14.5Ni13, and Al65Co17.5Ni17.5 Alloys
Authors: Roik Oleksandr S. , Samsonnikov Oleksiy , Kazimirov Volodymyr , Sokolskii Volodymyr
Published: February 2015

A local short-to-intermediate range order of liquid Al80Co10Ni10, Al72.5Co14.5Ni13, and Al65Co17.5Ni17.5 alloys was examined by X-ray diffraction and the reverse Monte Carlo modelling. The comprehensive analysis of three-dimensional models of the liquid ternary alloys was performed by means of the Voronoi-Delaunay method. The existence of a prepeak on the S(Q) function of the liquid alloys is caused by medium range ordering of 3d-transition metal atoms in dense-packed polytetrahedral clusters at temperatures close to the liquidus. The non-crystalline clusters, represented by aggregates of pentagons that consist of good tetrahedra, and chemical short-range order lead to the formation of the medium range order in the liquid binary Al-Ni, Al-Co and ternary Al-Ni-Co alloys.
Dielectric Relaxation of Binary Mixtures of Tetrahydrofuran and N-Methylformamide in Benzene Solution Using Microwave Absorption Studies
Authors: Kumar Raman , Kumar Raman , Rangra Vir S.
Published: February 2015

Using standard standing wave microwave X-band technique and following Gopala Krishna’s single frequency (9.90 GHz) concentration variational method, the dielectric relaxation times τ and the dipole moments μ of dilute solutions of Tetrahydrofuran (THF), N-methylformamide (NMF), and THF+NMF binary mixtures in benzene solutions have been calculated at different temperatures (25°C, 30°C, 35°C, and 40°C). The energy parameters (ΔHε , ΔFε , ΔSε ) for the dielectric relaxation process for the THF+NMF binary mixture containing 30 mol% THF have been calculated at 25°C, 30°C, 35°C, and 40°C and compared with the corresponding viscosity parameters. A good agreement between the free energy of activation from these two sets of values shows that the dielectric relaxation process like the viscous flow process can be treated as a rate process. From relaxation time behaviour of THF and NMF binary mixture in benzene solution, solute-solute types of the molecular association has been proposed.
Nonlinear Stretching Flow with Thermal Radiation
Authors: Hayat Tasawar , Noureen Rabia , Javed Tariq
Published: February 2015

This work concerns with the radiation effects on rotating boundary layer flow of an electrically conducting incompressible fluid over a nonlinear stretching surface. The viscous fluid fills the porous space. The flow is permeated by a constant magnetic field applied in the transverse direction. Two types of temperatures are prescribed to the surface. The resulting problems of velocity and temperature are obtained using the homotopy analysis method (HAM). Convergence of the developed series solutions is carefully checked. Graphical results of the velocity and temperature fields for various values of the parameters of the problems are presented and discussed.
Solution of Fractional Diffusion Equation with a Moving Boundary Condition by Variational Iteration Method and Adomian Decomposition Method
Authors: Das Subir , Rajeev Subir
Published: February 2015

In this paper, the approximate analytic solutions of the mathematical model of time fractional diffusion equation (FDE) with a moving boundary condition are obtained with the help of variational iteration method (VIM) and Adomian decomposition method (ADM). By using boundary conditions, the explicit solutions of the diffusion front and fractional releases in the dimensionless form have been derived. Both mathematical techniques used to solve the problem perform extremely well in terms of efficiency and simplicity. Numerical solutions of the problem show that only a few iterations are needed to obtain accurate approximate analytical solutions. The results obtained are presented graphically.
Natural Convection in a Porous Medium Bounded by a Long Vertical WavyWall and a Parallel Flat Wall
Authors: Tiwari Ambrish K. , Singh Ashok K.
Published: February 2015

This paper presents natural convection in a porous medium bounded by a long vertical wavy wall and a parallel wall. The shape of the wavy wall is assumed to follow a profile of cosine curve. The wall is kept at a constant heat flux while the parallel wall is kept at a constant temperature. The governing systems of nonlinear partial differential equations in their non-dimensional form are linearised by using the perturbation method in terms of amplitude and the analytical solutions for velocity and temperature fields have been obtained in terms of various parameters occurring in the model. A numerical study of the analytical solution is performed with respect to the realistic fluid air in order to illustrate the interactive influences of governing parameters on the temperature and velocity fields as well as skin friction and Nusselt number. It is found that in the case of maximum waviness (positive and negative), the velocity component along the wall has a reverse trend near the flat wall. It is observed that the parallel flow through the channel at zero waviness is greater than at maximum waviness (positive and negative) while the same trend occurs for perpendicular flow in the opposite direction. Examination of the Nusselt number shows that in the presence and absence of a heat source, the heat flows from the porous region towards the walls but in the presence of a sink, the heat flows from the walls into the porous region.
Rotating Flow of a Micropolar Fluid Induced by a Stretching Surface
Authors: Javed Tariq , Ahmad Iftikhar , Abbas Zaheer , Hayat Tasawar
Published: February 2015

This investigation deals with the boundary layer flow of a micropolar fluid over a stretching surface. The flow is considered in a rotating frame of reference. The governing nonlinear partial differential equations are reduced to coupled nonlinear ordinary differential equations. The set of similarity equations has been solved analytically employing the homotopy analysis method (HAM). The series solutions are given for velocity and microrotation, and the convergence of these solutions are explicitly discussed. Attention has been focused to the variations of the emerging parameters on the velocity and microrotation are discussed through graphs.
Application of the Laplace Decomposition Method to Nonlinear Homogeneous and Non-Homogenous Advection Equations
Authors: Khan Yasir , Austin Francis
Published: February 2015

In this paper, we apply the Laplace decomposition method to obtain series solutions of nonlinear advection equations. The equations are Laplace transformed and the nonlinear terms are represented by Adomian polynomials. The results are in good agreement with those obtained by the Adomian decomposition method and the variational iteration method but the convergence is faster.