Showing papers in "Canadian Journal of Physics in 2014"
TL;DR: In this paper, an exact solution for cylindrically symmetric modified Gauss-Bonnet gravity was obtained, which can be interpreted as the exterior metric of a cosmic string.
Abstract: Herein we obtain an exact solution for cylindrically symmetric modified Gauss–Bonnet gravity. This metric is a generalization of the vacuum solution of Levi–Civita in general relativity. It describes an isotropic perfect fluid one-parameter family of the gravitational configurations, which can be interpreted as the exterior metric of a cosmic string. By setting the Gauss–Bonnet coupling parameter to zero, we recover the vacuum solution in the Einstein gravity as well.
90 citations
TL;DR: In this article, a number of modern techniques used for the analysis of works of art are discussed in terms of their applications and the kind of information on the condition of artworks that can be extracted.
Abstract: This article discusses a number of modern techniques used for the analysis of works of art. The most widely used approaches as well as lesser known ones are outlined in terms of their applications and the kind of information on the condition of artworks that can be extracted. Special attention is paid to the method of thermographic analysis of works of pictorial art. The principles of the technique, various computational approaches, and safety concerns are discussed. A set of examples is provided for the demonstration of the capabilities of thermographic assessment, including a range of real canvas and panel paintings exhibited in museums and in private collections.
82 citations
TL;DR: In this paper, the authors presented cylindrically symmetric solutions for a type of Gauss-Bonnet gravity, and derived the full system of field equations and showed that there exist seven families of exact solutions for three forms of viable models.
Abstract: We present detailed cylindrically symmetric solutions for a type of Gauss–Bonnet gravity. We derive the full system of field equations and show that there exist seven families of exact solutions for three forms of viable models. By applying the method based on the effective fluid energy momentum tensor components, we evaluate the mass per unit length for the solutions. From a dynamical point of the view, by evaluating the null energy condition for these configurations, we show that in some cases the azimuthal pressure breaks the energy condition. This violation of the null energy condition predicts the existence of a cylindrical wormhole.
80 citations
TL;DR: In this article, the influence of the gravitational fields produced by a topology such as cosmic string space-time on a Klein-Gordon oscillator in the presence of a uniform magnetic field was studied.
Abstract: In this article, we study the influence of the gravitational fields produced by a topology such as cosmic string space–time on a Klein–Gordon oscillator in the presence of a uniform magnetic field....
68 citations
TL;DR: In this article, the authors considered a charged black hole with a scalar field coupled to gravity in (2 + 1)-dimensions and computed the logarithmic corrections to the corresponding system using two approaches.
Abstract: We consider a charged black hole with a scalar field that is coupled to gravity in (2 + 1)-dimensions. We compute the logarithmic corrections to the corresponding system using two approaches. In the first method we take advantage of thermodynamic properties. In the second method we use the metric function that is suggested by conformal field theory. Finally, we compare the results of the two approaches.
67 citations
TL;DR: In this paper, the structural, electronic, and optical properties of the half-Heusler CoCrZ (Z = Al, Ga) were studied using the full-potential with the mixed basis (APW + lo...
Abstract: To study the structural, electronic, and optical properties of the half-Heusler CoCrZ (Z = Al, Ga), we have performed ab initio calculations using the full-potential with the mixed basis (APW + lo)...
65 citations
TL;DR: In this article, the authors discuss how intuitive rules theory (Stavy and Tirosh. 1996) can be applied as a conceptual framework for understanding why students' difficulties in understanding kinematic graphs may occur.
Abstract: The ability to form and interpret kinematic graphs is an essential skill for students studying physics. The literature, however, details a variety of students’ difficulties in this regard. The present article discusses how intuitive rules theory (Stavy and Tirosh. Int. J. Sci. Educ. 18, 653 (1996)) can be applied as a conceptual framework for understanding why some of these difficulties may occur. It suggests, moreover, that explicit teaching regarding students’ use of intuitive rules in interpreting kinematic graphs may deepen students’ general understanding of graphs in physics.
63 citations
TL;DR: In this article, the dual phase lag theory was introduced to study the effect of the rotation on a two-dimensional problem of micropolar thermoelastic isotropic medium with two temperatures.
Abstract: In the present paper, we introduce the dual-phase lag theory to study the effect of the rotation on a two-dimensional problem of micropolar thermoelastic isotropic medium with two temperatures. A normal mode method is proposed to analyze the problem and obtain numerical solutions for the displacement, the conductive temperature, the thermodynamic temperature, the microrotation, and the stresses. The results of the physical quantities have been obtained numerically and illustrated graphically. The results show the effect of phase lag of the heat flux τq, a phase lag of temperature gradient τθ and two-temperature parameter on all the physical quantities.
62 citations
TL;DR: In this paper, the effects of variable viscosity and thermal conductivity on peristaltic flow of a Newtonian fluid in a vertical asymmetric channel were discussed, and the long wavelength approximation was used to linearize the governing equations.
Abstract: This paper discusses the effects of variable viscosity and thermal conductivity on peristaltic flow of a Newtonian fluid in a vertical asymmetric channel. Both viscosity and thermal conductivity are considered as a function of temperature. The long wavelength approximation is used to linearize the governing equations. The system of the governing nonlinear partial differential equation is solved using the perturbation method. Solutions are obtained for the velocity field, the temperature and the concentration. Asymmetry in the flow is induced by traveling waves of different phase and amplitude that propagate along the channel walls. The numerical results show that variable viscosity and thermal conductivity have significant influence on velocity, temperature, and mass transfer. The importance of pertinent flow parameters entering into the flow modeling is discussed.
55 citations
TL;DR: In this article, the electronic properties, elastic properties, and ideal tensile strengths for Ti2AlN and Ti4AlN3 were conducted using first-principles density functional calculations.
Abstract: Investigations into the electronic properties, elastic properties, and ideal tensile strengths for Ti2AlN and Ti4AlN3 were conducted using first-principles density functional calculations. The electronic band structures and density of states show metallic conductivity in which Ti 3d states dominate for Ti2AlN and Ti4AlN3. Moreover, the hybridization peak of Ti 3d and N 2p lies at a lower energy than that of Ti 3d and Al 3p, which suggests that the Ti 3d – N 2p bond is stronger than the Ti 3d – Al 3p bond. The variations of elastic constants with pressure indicate that Ti2AlN and Ti4AlN3 possess higher mechanical stability in the pressure range 0–100 GPa. By calculating the bulk-modulus-to-shear-modulus ratio and Cauchy pressure, we predict that Ti2AlN and Ti4AlN3 are brittle. We show that the structural failure of these ternary compounds can be ascribed to the breakage of weak Ti–Al bonds under uniaxial tension and that layered structural stability is determined by the strength of the Ti–Al bond under ten...
40 citations
TL;DR: In this paper, the rotation of a magneto-thermo-elastic solid with voids subjected to thermal loading due to a laser pulse was investigated and the bounding plane surface was heated by a non-Gaussian laser.
Abstract: This investigation deals with the rotation of magneto-thermoelastic solid with voids subjected to thermal loading due to laser pulse. The bounding plane surface is heated by a non-Gaussian laser be...
TL;DR: In this paper, the authors investigated the five-dimensional Kaluza-Klein space time with wet dark fluid (WDF), which is a candidate for dark energy (DE), in the framework of f(R, T) gravity.
Abstract: In this paper, we have investigated the five-dimensional Kaluza–Klein space time with wet dark fluid (WDF), which is a candidate for dark energy (DE), in the framework of f(R, T) gravity. R and T d...
TL;DR: In this article, the development and application of p-and n-type hydrogenated microcrystalline silicon oxide (μc-SiOx:H) alloys in tandem thin film silicon solar cells was reported.
Abstract: We report on the development and application of p- and n-type hydrogenated microcrystalline silicon oxide (μc-SiOx:H) alloys in tandem thin film silicon solar cells. Our results show that the optic...
TL;DR: In this article, a class of spherically symmetric space-time solutions to F(R) gravity without matter field (pure gravity) is investigated and it is shown that there is an essential singularity at the origin.
Abstract: We consider a class of spherically symmetric space–time to obtain some interesting solutions in F(R) gravity without matter field (pure gravity). We investigate the geometry of the solutions and find that there is an essential singularity at the origin. In addition, we show that there is an analogy between obtained solutions with the black holes of Einstein-Λ-power Maxwell invariant theory. Furthermore, we find that these solutions are equivalent to the asymptotically Lifshitz black holes. Also, we calculate d2F/dR2 to examine the Dolgov–Kawasaki stability criterion.
TL;DR: In this article, temperature-sensitive thin films based on spinel-type semiconducting ceramics of different chemical compositions were fabricated and studied and their multilayers of p+-p and p-p+p structures were found to possess good electrophysical characteristics before and after long-term ageing test at 170 °C.
Abstract: Temperature-sensitive thick films based on spinel-type semiconducting ceramics of different chemical composition Cu0.1Ni0.1Co1.6Mn1.2O4 (with p+-types of electrical conductivity), Cu0.1Ni0.8Co0.2Mn1.9O4 (with p-types of electrical conductivity), and their multilayers of p+-p and p-p+-p structures were fabricated and studied. These thick-film elements possess good electrophysical characteristics before and after long-term ageing test at 170 °C. It is shown that degradation processes connected with diffusion of metallic Ag into grain boundaries occur in one-layer p- and p+-conductive thick films. The p+-p structures were of high stability, the relative electrical drift being no more than 1%. Positron trapping processes in so-called “free” thick-film structures based on spinel-type Cu0.1Ni0.8Co0.2Mn1.9O4 ceramics are studied. It is shown that two-state positron trapping model is appropriate for an adequate description of changes caused by additional glass phase in these materials. The observed behaviour of d...
TL;DR: Simulation results show that for both shortest path routing strategy and efficient routing strategy, the traffic capacity of two-layer networks is significantly improved and the structure of the upper-layer network can be optimized freely based on the method.
Abstract: The study of traffic dynamics on multilayered networks is a hot issue, where the network topology is composed of two layers of subnetworks, such as wired–wireless networks and peer-to-peer networks...
TL;DR: InSe2 nanoparticles with tetragonally distorted phase have been prepared by mechanically alloying the synthesized bulk AIS powder at room temperature in a planetary ball mill under Ar in an attempt to create QDs.
Abstract: A quantum dot (QD) solar cell is an emerging field in solar cell research that uses QDs as the photovoltaic material. QDs have band gaps that are tunable across a wide range of energy levels by changing the QD size. Embedding different sized dots within the absorbing layer encourages harnessing the maximum spectrum energy. Also, other effects like a very high surface to volume ratio and quantum transport make them attractive for future devices. AgInSe2 (AIS) nanoparticles with tetragonally distorted phase have been prepared by mechanically alloying the synthesized bulk AIS powder at room temperature in a planetary ball mill under Ar in an attempt to create QDs. Nanoparticles are formed of ∼10 nm in size. These ball-milled nanoparticles contain different shapes and the Rietveld analysis of X-ray powder diffraction data reveals their detailed structural features. High resolution transmission electron microscope images also detect the presence of the tetragonal phase in ball-milled samples. Peak broadening (...
TL;DR: In this paper, the Lagrangian and conserved SUSY charges are expressed in terms of the (anti-)chiral supervariables to demonstrate the invariance of Lagrangians as well as the nilpotency of the conserved charges.
Abstract: We derive the on-shell as well as off-shell nilpotent supersymmetric (SUSY) symmetry transformations for the N = 2 SUSY quantum mechanical model of a (0 + 1)-dimensional (1D) free SUSY particle by exploiting the SUSY-invariant restrictions on the (anti-)chiral supervariables of the SUSY theory that is defined on a (1, 2)-dimensional supermanifold (parametrized by a bosonic variable t and a pair of Grassmannian variables θ and θ¯ with θ2=θ ¯ 2 =0,θθ ¯ +θ ¯ θ=0 ). Within the framework of our novel approach, we express the Lagrangian and conserved SUSY charges in terms of the (anti-)chiral supervariables to demonstrate the SUSY invariance of the Lagrangian as well as the nilpotency of the SUSY conserved charges in a simple manner. Our approach has the potential to be generalized to the description of other N = 2 SUSY quantum mechanical systems with physically interesting potential functions. To corroborate the preceding assertion, we apply our method to derive the N = 2 continuous and nilpotent SUSY transfor...
TL;DR: In this paper, a metric with hyperscaling violation was used to study the form factor of QCD and the dependence of form factor on momentum numerically, and the authors showed that the effect of the violation on form factor was negligible.
Abstract: In this paper we use a metric with hyperscaling violation and study form factor of QCD. We find the effects of hyperscaling violation on the form factor and obtain the dependence of the form factor on momentum numerically. Here by using the hyperscaling violation metric we do not need hard-wall and soft-wall models.
TL;DR: The structures and vibrational spectra of inorganic aerosols, including ammonium sulfate (NH4)2SO4, ammonium nitrate NH4NO3, and sodium nitrate NaNO3 are investigated at the periodic ab initio quan as discussed by the authors.
Abstract: The structures and vibrational spectra of inorganic aerosols, including ammonium sulfate (NH4)2SO4, ammonium nitrate NH4NO3, and sodium nitrate NaNO3 are investigated at the periodic ab initio quan
TL;DR: In this article, the density functional theory based stability analysis of zirconium nitride and hafnium oxide in its rocksalt (B1), CsCl (B2), and zinc blende (B3) type phases is discussed.
Abstract: The present paper discusses the density functional theory based stability analysis of zirconium nitride and hafnium nitride in its rocksalt (B1), CsCl (B2), and zinc blende (B3) type phases. The ground state total energy calculation approach of the system has been used through the generalized gradient approximation parameterized with revised Perdew–Burke–Ernzerhof as exchange correlation functional. The present theoretical analysis confirms the stability trend of phases from most stable to less stable as B1 → B2 → B3. The study also reports the analysis of elastic properties of these nitrides in its most stable B1-type phase.
TL;DR: In this paper, a two-dimensional problem in a transversely isotropic thermoelastic medium without energy dissipation and with two temperatures due to a thermal source is investigated.
Abstract: A two-dimensional problem in a transversely isotropic thermoelastic medium without energy dissipation and with two temperatures due to a thermal source is investigated. As an application of the problem, a particular type of continuous thermal source has been taken to illustrate the utility of the approach. The problem is solved numerically by using a finite element method. The displacement components, conductive temperature, and stress components have been obtained numerically and illustrated graphically for our particular model. Some special cases of interest are also discussed. The implementation of finite element method codes used C++. Numerical work is also performed for a suitable material with the aim of illustrating the results.
TL;DR: In this article, the effect of rotation on the thermomicrostretch elastic solid was investigated in the context of the generalized thermoelasticity Lord-Shulman theory with one relaxation time and Green-Lindsay theory with two relaxation times, as well as the classical dynamical coupled theory.
Abstract: The present investigation is aimed at studying the effect of rotation on the thermomicrostretch elastic solid. The formulation is applied in the context of the generalized thermoelasticity Lord–Shulman theory with one relaxation time and Green–Lindsay’s theory with two relaxation times, as well as the classical dynamical coupled theory. The problem has been solved numerically using a finite element method. Numerical results for the temperature distribution, the displacement components, the force stresses, the couple stresses, and the microstress distribution are represented graphically. The results indicate that the effects of rotation are very pronounced. Comparisons are made with the results in the presence and absence of rotation and in the presence and absence of microstretch constants between the two theories.
TL;DR: In this paper, an implementation of an efficient numerical method for solving the system of coupled nonlinear fractional diffusion equations (NFDEs) is introduced, based upon a combination between the properties of the Legendre approximations and finite difference method (FDM).
Abstract: In this article, an implementation of an efficient numerical method for solving the system of coupled nonlinear fractional diffusion equations (NFDEs) is introduced. The proposed system has many applications, such as porous media and plasma transport. The fractional derivative is described in the Caputo sense. The method is based upon a combination between the properties of the Legendre approximations and finite difference method (FDM). The proposed method reduces NFDEs to a system of ordinary differential equations that are solved using FDM. Special attention is given to the study of the convergence analysis and deducing the upper bound of the error of the resulting approximate solution. A numerical example is given to show the validity and the accuracy of the proposed method.
TL;DR: In this article, the study of two-dimensional stagnation point flow and heat transfer from a warm, laminar liquid flow of a nanofluid towards a melting stretching sheet is presented.
Abstract: The present analysis deals with the study of two-dimensional stagnation-point flow and heat transfer from a warm, laminar liquid flow of a nanofluid towards a melting stretching sheet. Using similarity transformations, the governing differential equations were transformed into coupled, nonlinear ordinary differential equations, which were then solved numerically by using the Runge–Kutta fourth-order method along with the shooting technique for two types of nanoparticles namely copper (Cu) and silver (Ag) in the water-based fluid with Prandtl number Pr = 6.2, the skin friction coefficient, the local Nusselt number, the velocity and the temperature profiles are presented graphically and discussed.
TL;DR: In this paper, a Clifford Cl(5, C) unified gauge field theory formulation of conformal gravity is reviewed along with its implications for the Pati-Salam (PS) group SU(4) × SU(2)L × SU (2)R, and trinification grand unified theory models of three fermion generations.
Abstract: A Clifford Cl(5, C) unified gauge field theory formulation of conformal gravity and U(4) × U(4) × U(4) Yang–Mills in 4D, is reviewed along with its implications for the Pati–Salam (PS) group SU(4) × SU(2)L × SU(2)R, and trinification grand unified theory models of three fermion generations based on the group SU(3)C × SU(3)L × SU(3)R. We proceed with a brief review of a unification program of 4D gravity and SU(3) × SU(2) × U(1) Yang–Mills emerging from 8D pure quaternionic gravity. A realization of E8 in terms of the Cl(16) = Cl(8) ⊗ Cl(8) generators follows, as a preamble to F. Smith’s E8 and Cl(16) = Cl(8) ⊗ Cl(8) unification model in 8D. The study of chiral fermions and instanton backgrounds in CP2 and CP3 related to the problem of obtaining three fermion generations is thoroughly studied. We continue with the evaluation of the coupling constants and particle masses based on the geometry of bounded complex homogeneous domains and geometric probability theory. An analysis of neutrino masses, Cabbibo–Koba...
TL;DR: In this article, it is argued that the average energy of the soft quanta is such that the typical geometric size of the field source can be roughly interpreted as their de Broglie wavelength.
Abstract: A crucial ingredient in the large-N quantum portrait of black holes proposed by Dvali and Gomez is the estimate of the number of soft quanta that make up the classical gravitational field. It is argued here that the coherent state formalism provides a way to calculate that number directly. As a consequence, the average energy of the soft quanta is such that the typical geometric size of the field source can be roughly interpreted as their de Broglie wavelength. The calculation is done for the electromagnetic field and for Newtonian gravity, and it is argued that the number of soft quanta should be unchanged in general relativity because of the long range nature of gravity.
TL;DR: In this article, the influence of Bi doping on the thermal, electrical, and optical properties of Ge2Sb2Te5 thin films was investigated and the existence of two Bi concentration ranges with different influence of dopant on the properties of thin films were established.
Abstract: The influence of Bi doping on the thermal, electrical, and optical properties of Ge2Sb2Te5 thin films was investigated. The existence of two Bi concentration ranges with different influence of dopant on the properties of thin films was established. At low concentrations (0.5–1.0 wt.% of Bi), anomalous deviations of physical properties from monotonous concentration dependences were observed. This effect is explained by the use of percolation theory, where formation of infinite clusters is accompanied by critical phenomena at critical concentrations.
TL;DR: In this paper, the role of H2 during deposition has been investigated: it is demonstrated that H2 is needed to remove F by forming HF molecules, when all atomic F has been removed from the plasma, the remaining atomic H can then contribute to μc-Si:H growth.
Abstract: Hydrogenated microcrystalline silicon is of great interest as the intrinsic layer in thin film solar cells. It is generally accepted that optimized cells use an I-layer with a crystalline fraction ranging from 50% to 70%. We report here on the use of fully crystallized layers deposited from SiF4/H2/Ar gas mixtures. A VOC of 536 mV and a JSC of 25.4 mA/cm2 have been obtained in PIN solar cells using a fully crystallized intrinsic material. Fourier transform photocurrent spectroscopy measurements show that the films have a very low defect density down to 5.1 × 1014 cm−3. The role of H2 during deposition has been investigated: it is demonstrated that H2 is needed to remove F by forming HF molecules. When all atomic F has been removed from the plasma, the remaining atomic H can then contribute to μc-Si:H growth.