Iranian Journal of Physics Research
https://ijpr.iut.ac.ir/
Iranian Journal of Physics Researchendaily1Wed, 23 Aug 2023 00:00:00 +0430Wed, 23 Aug 2023 00:00:00 +0430Study the Effects of Gaussian distribution of coherence length of the source on the diffraction from single slit and circular aperture using Monte Carlo simulation
https://ijpr.iut.ac.ir/article_3391.html
We study the Fraunhofer diffraction from a single slit as well as a circular aperture in a situation where the light source is monochromatic but partially coherent. In this paper, we try to bring the problem closer to reality and do not fix the coherence length and consider a Gaussian distribution function for it. Numerical study of the effects of coherence parameters with Gaussian distribution on a far field diffraction pattern is performed. In the case of a single slit, as the coherence length decreases, no significant deviation occurs at its central peak, but at higher diffraction levels, a decrease is apparent, depending on the Gaussian distribution of the coherence length. For circular apertures, the parameters of the coherence length distribution function affect the shape of the light intensity distribution and the first-order diffraction pattern decreases, and with a relative decrease in coherence length, the first-order circular diffraction pattern gradually disappears.&nbsp;Investigation of ZnS-Mg thin films prepared by sol-gel method
https://ijpr.iut.ac.ir/article_3392.html
In this paper, different aspects of making ZnS and ZnS-Mg thin films coated on germanium (Ge) substrate are studied by the sol-gel method. The main goal is to preserve the optical window property of ZnS-Mg thin films that can be used in infrared thermal imaging systems. First, the method of synthesizing transparent and stable sols of ZnS and ZnS-Mg is studied. In this regard, the best molar ratio of materials, the best temperature, and the best conditions for the preparation of ZnS and ZnS-Mg sols are presented. Subsequently, the essential aspects of the spin coating of thin films on the germanium (Ge) substrate are evaluated. These components include; the best rotation speed, best drying temperature, and the best annealing temperature under Argon gas. Furthermore, according to Fourier-transform infrared spectroscopy (FTIR), X-ray diffraction (XRD), and UV-VIS transmission spectroscopy, we characterized the chemical bond, crystal structure, and the optical window property of infrared spectrum transmission for the ZnS-Mg thin films which deposited on Germanium substrate. Finally, the preservation and existence of the optical window property of the infrared transmission spectrum in ZnS-Mg thin films are shown.Investigating and comparing the penetration mechanism and diffusion path of sodium and lithium in the structure of NaSICONs
https://ijpr.iut.ac.ir/article_3393.html
The design and identification of solid electrolytes can lead to finding safer and more efficient solid state batteries in a wider temperature range for fuel cells. There are more than 200,000 crystal structures in the ICSD database for finding solid electrolytes, and among them, more than 44,000 experimental structures have been considered in the search for solutions for advances in energy storage. Therefore, before making solid electrolytes, we need new calculation methods so that we can choose the appropriate structure among all these existing structures with the help of it, more quickly and accurately than in the past. Super ionic conductor solids are one of the main components in energy storage and conversion, and the development of these new conductors is impossible without a comprehensive understanding of ion migration mechanisms in these structures. NaSICON is an oxide-based solid electrolyte with a three-dimensional framework. NZP (NaZr2P3O12) and rhombohedral LiZr2P3O12 (LZP) are the two prototypes of all NaSICONs. In this research, with a new computational approach, we showed that by changing the sodium ion with lithium in the structure of NaSICONs, the amount of activation energy, which plays a decisive role in the design and production of all-solid-state batteries, changes and we have answered the question whether with this change, the path of movement of sodium and lithium ions inside the crystal structure remains constant or not.Investigating the effect of massive stars on the dynamical evolution of open clusters, using optimal and random sampling
https://ijpr.iut.ac.ir/article_3394.html
Massive OB stars have an important effect on the dynamical evolution of open star clusters. In the simulation of star clusters, the sampling method to determine the mass function of the cluster affects the number and mass of massive stars. Two methods of "optimal sampling" and "random sampling" have been proposed to initialize the cluster stars. In the random sampling method, the mass of the heaviest star and the number of massive stars change randomly, which affects the dynamical evolution of young open clusters. Our investigations show that, if nature follows a random sampling method in star formation, the evolutionary path of low-mass clusters with the same initial conditions can be completely different, depending on the number of OB stars. Therefore, in models with more OB stars and thus more stellar remnants, they lose at a faster rate and dissolve in a shorter time. It is also shown in this paper that the retention of stellar remnants in the cluster plays an important role in the evolution of the cluster. In models with more massive stars, the dissolution rate increases if stellar remnants are retained in the cluster. However, considering the realistic models for these young and low-mass clusters in which most of the stellar remnants leave the cluster immediately after formation, the difference between the evolutionary tracks of the models with OB-min and OB-max stars decreases.Two-dimensional study of long rod particles in a nematic liquid crystal with tangential and perpendicular anchorings
https://ijpr.iut.ac.ir/article_3395.html
In this research, we have investigated the interaction of two identical, very long, and parallel rod particles with planar and homeotropic anchorings in a two-dimensional nematic liquid crystal. The parallel axis of the rods is perpendicular to the nematic field at far distances. The planar and homeotropic anchorings on the surface of particles are perpendicular to the axis of the rods. This nematic field behavior leads to the two-dimensional director around the particles. To this end, we have approximated the study of the interaction of two identical rods in three dimensions to the study of the circular sections of these particles in two-dimensions. The nematic equilibrium field around the circular sections is obtained from the numerical minimization of the Landaude Genns free energy and the surface energy anchorings. The created particles and defects cause short-range and long-range interactions between particles. At far distances, the interaction between particles shows a quadrupole behavior compared to electrostatics. The interaction energy between particles at close contact has a symmetrical behavior around the spatial configuration of 45 degrees, which includes two equilibrium arrangements of the equilibrium configuration at zero and 90 degrees.Simulating the sensing properties of silver nanoparticles for identifying molecular structures using modified discrete dipole approximation method
https://ijpr.iut.ac.ir/article_3396.html
By making a modification to the usual discrete dipole approximation (DDA) method, the effect of different molecules on the plasmonic properties of silver nanoparticles was investigated. Several calculations were performed for molecules with different structures, sizes and concentrations. The obtained results indicated that considering that the modified DDA method is very sensitive to the geometrical details and the type of atoms of the guest molecule, the smallest change in the dimensions and also the type of atoms of the guest molecule leads to a change in the peak wavelength of the absorption spectrum of silver nanoparticle. These changes are unique for different molecules with good accuracy.Space charge solitary waves in warm charged particle beams in resistive wall transport channels
https://ijpr.iut.ac.ir/article_3397.html
In this article, a one-dimensional kinetic model is used to obtain space charge solitary waves in a beam of hot charged particles into a transmission channel with a resistance wall of radius rw. The axial electric field is obtained as , where &nbsp;and&nbsp;are geometric constants. In addition, due to the resistance of the wall, an electric field &nbsp;appears. The moments of the Vlasov equation for the water bag distribution function are converted into fluid equations and these fluid equations are reduced to the kdv equation using the reduced perturbation method. The shape of the fast and slow space charge solitary waves caused by the beam of hot charged particles in the presence of wall resistance is obtained by numerically examining the KdV equation at different times. Finally, it is revealed that with the increase of the wall resistance, the growth(attenuation) rate of the relative amplitude of the slow (fast) space charge soliton waves caused by the beams of charged particles increases.Simulations of DNA damage types and frequencies induced by carbon ions
https://ijpr.iut.ac.ir/article_3398.html
Carbon ions&rsquo; dose distribution, in comparison with lighter hadrons, has certain therapeutic advantages due to their relatively higher biological effectiveness in tumors. Simulating the physical and chemical interactions of carbon ions in a sphere of liquid water of cellular scales, we derived the mean number of deposited energies per unit dose per a DNA segment of 216 bp as a function of deposited energy. As such, the frequency of complex damage was obtained from the point of view of a multiplicity of damage points on the DNA strands. Furthermore, the damage yields for different types of single- and double-strand breaks were obtained and, specifically, the mean number of simple single- and double-strand breaks per DNA segment were calculated as a function of deposited energyStudy the effect of ion type on the transport properties of implanted tantalum interfaces of multilayer structures
https://ijpr.iut.ac.ir/article_3399.html
In this paper, the effect of ion type has been considered to study transport through the structures in which their interfaces have been produced by the ion implantation process. The interfaces are tantalum based and the argon and nitrogen ions have been considered at an energy of 30 keV and in different doses at ambient temperatures. For studying the surface morphology of the ion implanted rough thin films, The Atomic Force Microscopy (AFM) analysis has been used. The average roughness has been determined. Decreasing the transmission probability is the main outcome of the rough interfaces/samples. The results show that the interfaces which have been produced by argon ion implantation are rougher than nitrogen cases. Also, the peak to valley ratio reduces in two cases. Moreover, with increasing nitrogen ion doses, the current density has been reduced as a function of voltage. As it is predicted, the transmission probability decreases because of the rough interfaces which have been generated by ion implantation process. As a consequence of the scattering process (because of the interfacial roughness), the resonant tunneling peak current decreases and also, the peak to valley ratio (PVR) reduces. The samples which were prepared by argon ion implantation were rougher than nitrogen ones. Also, with increasing the nitrogen ion doses, the current density has been decreased as a function of voltage.The effect of light polarization on the thermoplasmonic properties of an array of hexagonal dimer nanoparticles
https://ijpr.iut.ac.ir/article_3406.html
Surface plasmons have been used recently to generate heat nanosources, the intensity of which can be tuned, for example, with the wavelength of the excitation radiation&nbsp;and polarization. We present versatile analytical investigations for the three&ndash;dimensional computation of the temperature rise in complex planar arrays of metallic nanoparticles. In the case of elongated particles sustaining transverse and longitudinal plasmon modes, we show a simple temperature rise control of the surrounding medium when turning the incident polarization. In this article, the results of analytical simulation for the temperature distribution are presented in a planer array of gold hexagonal dimer nanoparticles and it is investigated how the temperature distribution of the array will change by changing the polarization angle of the incident light and wavelength. The polarization angle of the incident light is considered in 0 degrees (parallel to the dimer axis) and 45 degrees, and 90 degrees (perpendicular to the dimer axis) and, &nbsp;according to the resonance wavelengths in each polarization, the temperature distribution and value have been simulated. In 90-degree polarization, light absorption is the most, and the highest wavelength of it occurred at 1334 nm, and this wavelength causes high-temperature changes in the array.Group theoretic approach to calculate the ξ- pseudo Dirac operator and its spectrum on AdS2
https://ijpr.iut.ac.ir/article_3402.html
&xi;-pseudo Dirac operator has recently been constructed with the help of &xi;-pseudo modules and appropriate projectors on AdS2 space. In this article, this operator will be constructed with the help of group theory. For this purpose, firstly, the spin structure of AdS2 space is built and then,with the help of relations related to right and left actions and Maurer-Cartan forms, &xi;- pseudo Dirac operator and then its scalar form in, instanton and non-instanton mode is introduced will be and at the end its spectrum is also calculated in different states of this &xi;-pseudo operator.
.Strong indirect coupling of a magnet with a piezoelectric in a microwave cavity
https://ijpr.iut.ac.ir/article_3403.html
A system consisting of a magnetic material and a piezoelectric material placed within a microwave cavity is considered. The strong and long-range coupling between the piezoelectric material and the magnetic material mediated by the microwave cavity has been studied. We have shown that the realization of the strong coupling regime is not only possible between each of these materials with the microwave cavity, but also between the magnetic material and the piezoelectric material.The effect of electron-phonon interaction on the phonon transmission coefficient of an atomic nanostructure
https://ijpr.iut.ac.ir/article_3404.html
In this paper, we study the phonon transmission coefficient of an infinite atomic chain in a small part of &nbsp;it &nbsp;there is electron-phonon interaction, with the help of Green&rsquo;s function. From the electronic viewpoint, the system is considered in the nearest neighbor tight-binding approach and for phonons in the interacting region, it is investigated within the next nearest neighbor harmonic approximation. In the suggested model, we assume that the electronic cloud of the localized atomic orbitals causes the variation of the force constant between the neighbor atoms in the interacting part of the chain. The variation in these force constants makes changes to the elements of the dynamic matrix of the system and consequently, the phonon transmission coefficient will be changed. Therefore, the present formalism gives the phonon transmission coefficient as a function of electronic and phononic parameters of the system as well as the strength of electron-phonon interaction. Finally, we also tried to address the physics of the problem by presenting some numerical results.Gaussian regular black holes in pure quadratic gravity
https://ijpr.iut.ac.ir/article_3405.html
In this work, we study some introductory properties of the regular Gaussian black holes in pure quadratic gravity. The results show the relative advantages of this model with respect to the similar case in Einstein gravity.Enhanced broadband light absorption by WSe2 mono layers via surface plasmon structures
https://ijpr.iut.ac.ir/article_3407.html
During the last decade, electronic and photonic properties of two-dimensional materials like graphene and transition metal dicalcogenides, have attracted the attention of research in nanophotonics and optoelectronics. Unlike graphene with zero energy gap, transition metal dicalcogenides like WSe2, in their bulk state, have extreme and indirect energy gaps. Moreover, direct bandgaps have approached in visible and infrared regime by reducing the thickness of them to one layer. However, because of their inherent small atomic thickness, these materials face a severe challenge in interaction of light and matter that leads to weak absorption and emission of light. For instance, monolayers of WSe₂ with a thickness of 0.649 nm and an energy gap of 1.64 eV, absorb less than 10 % of incoming light. Therefore, increasing the amount of light absorption in monolayers of WSe₂ and other transition metal dicalcogenides has become an important issue for practical applications in electronic and photonic devices. One solution is the integration of these monolayers and surface plasmon structures. In this paper, we upgrade light absorption in visible and near infrared area to broad band mode by designing a simple unit cell. It is found that the mean absorption of the proposed absorber in the wavelength range of 600 &ndash; 850 nm is about 93 %. We have to mention that these simulations have been done by Lumrical software that is based on discretization of Maxwell equations in time and space domains based on the finite difference time domain method.Review of testing black hole candidates with electromagnetic radiation
https://ijpr.iut.ac.ir/article_3408.html
Astrophysical black holes are thought to be Kerr solution of general relativity but there is not yet observational evidence to prove them. One can study the emission of electromagnetic waves around them to test their geometry of space time. In this review article, we consider the deviation from Kerr solution to test the strong gravity regime of General Relativity. We introduce and employ black hole shadow, X-ray reflection spectroscopy, iron line reverberation mapping, quasi-periodic oscillations, and continuum-fitting method to solve the degeneracy problem.Experimental investigation and simulation of an ion anemometer and studying the effect of the air boundary layer on its performance
https://ijpr.iut.ac.ir/article_3409.html
In this article, an attempt has been made to measure the speed of air flow by releasing and tracking electric ions in it. In fact, if an electrical discharge plasma is exposed to air flow, some of its ions move along with the flow, and ion anemometers measure the air speed by tracking these ions. In this research, a wind tunnel has been designed and prepared. Then an ion anemometer is made and installed on its wall. According to the obtained results, the effect of the boundary layer adjacent to the wall on the movement of ions causes the speed measured by the ion anemometer to show a certain proportion with the speed of the air flowing inside the wind tunnel. In order to properly understand the physical mechanism involved in this problem, first the movement of ions in the boundary layer has been investigated using simulation and then it has been studied more analytically. The results of the experiments, together with the simulation data and the analytically calculated values, show that the tracked ions, instead of moving in the uniform background flow, move downstream in the boundary layer adjacent to the wall at a lower speed, so that this proportionality phenomenon defines the measured velocities and shows the effect of the boundary layer on the performance of ion anemometers.Investigating and analysis of the properties of coherent states of a deformed nonlinear harmonic oscillator
https://ijpr.iut.ac.ir/article_3410.html
In this research, we study the coherent states of a deformed nonlinear harmonic oscillator. We use the perturbation theory to compute eigenstates and eigen-values for a deformed nonlinear harmonic oscillator and then define the generalized coherent states based on the Gazeau-Klauder formulation. Then, using the Mandel parameter and the second-order correlation function, we will investigate the statistical properties of the system. The analysis shows that the coherent states for a deformed and non-deformed nonlinear harmonic oscillator follows the sub-Poissonian and super-Poissonian statistics, and exhibits the antibunching and bunching effects, respectively. In addition, we show that the anti-correlation function for a deformed nonlinear oscillator is strongly fluctuating and irregular. Also, the anti-correlation function of a non-deformed nonlinear harmonic oscillator shows the phenomena of collapse and revival of fractional revelations. We also examine the limits of different parameters so that the obtained results are valid.Rapid fabrication of ordered 2D binary colloidal crystals at the air-water interface by engineering the surface properties of water and polymer microspheres
https://ijpr.iut.ac.ir/article_3411.html
In this work, the fabrication of centimeter-sized 2D binary colloidal crystals, composed of monodisperse poly(methyl methacrylate) (PMMA) microspheres with diameters of 1039 and 238 nm, using the self-assembly method at the air-water interface is studied. In this method, a colloidal suspension of large and small spheres mixed with ethanol is gently injected onto a glass substrate. After injection, the colloidal spheres rapidly spread on the water surface and form a monolayer of polymer microspheres that can be transferred onto any other substrates. A challenging issue in fabricating 2D binary colloidal crystals is the regular penetration of smaller microspheres into the empty spaces between larger ones. It has been shown in this work that the use of sodium dodecyl sulfate (SDS) surfactant and adjusting the pH of water by adding sodium hydroxide (NaOH) leads to ordered penetration of small spheres. Moreover, optimal concentrations of SDS and pH for fabricating large and regular crystals at the air-water interface have been obtained. The fabricated 2D binary colloidal crystals have various applications in different fields, such as photonic devices, chemical/biosensors, chromatography, biomedical devices, cell culture tools etcA finite model for electrodynamics by introducing a form factor fHD2(ℓ2□)=1+(-ℓ2□)2 into the kinetic term of Maxwell theory
https://ijpr.iut.ac.ir/article_3412.html
In this paper, a higher-derivative model for electrodynamics is presented in a&nbsp; D+1 dimensional Minkowski space-time by introducing a form factor into the kinetic term of Maxwell theory as -1/4&micro;0 F&micro;&nu;F&micro;&nu;&rarr; -1/4&micro;0 F&micro;&nu;FHD2(ℓ2□)F&micro;&nu; , where &nbsp;is a characteristic length scale. Our calculations show that for D&Ecirc;&Icirc;{3, 4, 5} the electrostatic potential of a point charge is finite at the position of the point charge in this higher-derivative modification of Maxwell's theory. For D=3 the explicit form of the potential and the electric field of a point charge are obtained analytically in this higher-derivative electrodynamics. According to numerical estimations, the upper bound for the characteristic length scale ℓ is ℓmax ~1/100ℓelectroweak &nbsp;, where ℓelectroweak= 10-18m is the electroweak length scale. Finally, it should be emphasized that for ℓ&lt;&lt;1 the results of this paper are compatible with the results of ordinary Maxwell theory.Hydrodynamics interaction between two beads in the presence of the temperature gradient,, the effect of coupling between beads on the Soret coefficient.
https://ijpr.iut.ac.ir/article_3417.html
In this investigation we try to find out the effect of the internal structure of the molecules in the Soret effect. Accordingly, we modeled a molecule as two trapped beads which are exposed to the external temperature gradient. we find the average of the total force that this system exerts on the fluid. we know that this average in the absence of any temperature field will be zero. Then we find the Soret coefficient proportional to this Force, At the end, we solve all the equations again by the considering of the space-dependent viscosity.Folding model potentials using the LOCV-DDAEI for 16O+16O elastic scattering
https://ijpr.iut.ac.ir/article_3418.html
The elastic scattering of 16O+16O systems at several incident energies are analyzed, in the framework of double folding model, using the density-dependent averaged effective two-body interaction (DDAEI). The DDAEI is generated via the lowest order constrained variational (LOCV) method for the symmetric nuclear matter (SNM), using the input bare Reid68 nucleon-nucleon (NN) potential. A new energy dependent factor, g(E), is introduced to the LOCV-DDAEI to get a more realistic description of heavy ion (HI) scattering, at the different incident energies. It is shown that a linear energy dependent function, provides a good agreement with the energy dependence of the nuclear optical potential, and causes to increase the convergence speed of iteration method in evaluating the exchange part of folded potential, such that the computing time is considerably decreased. The calculated cross sections of the 16O+16O systems in the above framework, are compared with the available experimental data. It is demonstrated that a quite good description of HI scattering can be obtained, using the above LOCV-DDAEI, by adjusting the parameters of the linear energy dependent factor, g(E).Investigation of entanglement of atomic systems near coherent perfect absorber materials
https://ijpr.iut.ac.ir/article_3419.html
Recently, coherent perfect absorbers have received much attention from researchers in the field of the classical optics. Such absorbers, known as a time-reversal of lasers, provide perfect absorption of the incident light. Considering the very attractive features of these materials, in this paper, we investigat the quantum optics of these materials. To do this, we consider two coherent perfect absorber structures and assume two identical two-level atoms, one of the atoms is prepared in its ground state and the other in the excited state, are placed on both sides of the coherent perfect absorber slabs. We compute the spontaneous emission rate, Lamb shift, and collective decay of atoms near two slabs, and then investigate the entanglement dynamics of the atomic system using the concurrence. We find that these parameters exhibit a damped oscillatory behavior with increasing the distance between the atoms and the slabs. In contrast to the classical regime, we also observe that these structures are not the perfect absorbers in the quantum regime.Quantum Key Distribution in Computer Networks
https://ijpr.iut.ac.ir/article_3420.html
The secure transfer of keys between two parties, is one of the primary problems in cryptography. The possibility that the key can be manipulated or intercepted by way of an eavesdropper is the cause for the concern. A promising way to this problem is Quantum Key Distribution (QKD). The secure distribution of keys that may be used to encrypt and decrypt messages is made feasible by this approach, which makes use of the idea of quantum mechanics. QKD offers a degree of protection that can not be done by means of classical cryptography techniques, and has remarkable capability for application in a scope of fields in which secure correspondence is crucial. QKD is a field of study that has brought various conventions pointed toward empowering the safe alternate of cryptographic keys between two parties, Alice and Bob. Two key protocols within this field are the BB84 which was designed by Bennett and Brassard and E91 which was proposed by Ekert. While other protocols have been developed, many draw inspiration from these two foundational approaches. We focused specifically on the E91 protocol and explored its potential for the safe transfer of entangled pairs within computer networks. This protocol utilizes entanglement between particles as a means of verifying the security of the key exchange. Our investigation centered around testing the entanglement swapping for two particles using the E91 protocol, with the aim of developing a novel method for the secure transmission of entangled pairs via computer networks. Our findings suggest promising avenues for future work in implementing secure entanglement swapping in practical applications.Entanglement Amplification by Three-Level Laser Coupled to Vacuum reservoir
https://ijpr.iut.ac.ir/article_3421.html
In this paper we have studied the squeezing and entanglement properties ofthe cavity light generated by a three-level laser. In this quantum optical system, Nthree-level atoms available in an open cavity, coupled to a two-mode vacuum reservoir, are pumped to the top level by means of electron bombardment at constantrate. Applying the solutions of the equations ofevolution for the expectation values of the atomic operators and the quantum Langevin equations for the cavity mode operators, we have calculated the mean,variance of the photon number, the quadrature squeezing, entanglement amplification as well as the normalized second-order correlationfunction for the cavitylight. In addition, we have shown that the presenceof the spontaneous emission process leads to a decrease in the mean and varianceof the photon number.Pressure Induced Structural Phase Transition and Influence of Pressure on the Electronic and Mechanical Properties of TiPdSn: An Ab Initio Study
https://ijpr.iut.ac.ir/article_3422.html
Structural, electronic, mechanical and optical properties of half-Heusler alloy TiPdSn were investigated from first-principles calculation as well as the structural phase transition under pressure. The projected augmented wave (PAW) type of pseudopotential within the generalized gradient approximation (GGA) was used during the calculation. The obtained results revealed that TiPdSn is a semiconductor with an indirect band gap. Also the results from the mechanical property showed that TiPdSn is ductile and mechanically stable. TiPdSn is seen to undergo structural phase transition from cubic to two different structures namely type1 and type2 which crystallize in hexagonal structure and the transition pressures recorded were 4.53GPa for type 1 and 25.3 GPa for type 2. Optical properties revealed that TiPdSn has a static dielectric function of 21.47 and a refractive index of 4.63. The band gap of the alloy decreases and later increases as pressure increases.String Cosmological Model in 5 Dimensional Space-Time: Interacting with Viscous Fluid
https://ijpr.iut.ac.ir/article_3423.html
Considering bulk viscosity as (i) constant quantity and (ii) functions of cosmic time, the field equations in 5-dimensional Bianchi type-I model in the context of general theory of relativity, has been obtained and solved in this paper by the use of certain physical assumptions, which are agreeing with the present observational findings. In both cases, the model represents an exponentially expanding and accelerating Universe that starts with volume 0 and stops with infinite volume. The model has an initial singularity and will eventually approach the de-Sitter phase (q=-1). It also satisfies the energy conditions "Energy density&ge;0 and particle density&ge;0". This model represents a matter-dominated Universe that agrees with current observational data. The model is anisotropic one and shearing throughout its evolution for n&ne;1Investigation of ultra-high energy cosmic ray mass composition by the ground based detectors
https://ijpr.iut.ac.ir/article_3424.html
Mass composition of cosmic rays and thus determining their sources, especially at high energies, is one of the most important parts of astroparticle physics and cosmic ray science which also can help to know the universe better. Many different methods have been used to estimate the mass composition so far, which the most important of them has been done by Pierre Auger observatory group. At present work, in order to estimate the mass composition of cosmic rays, two different ways (first using from muonic component and second, maximum atmospheric depth) are used which they have been done by comparing experimental data and simulated ones. An increase in the mass composition and low flux of photons is observed at high energies. The diagram of maximum atmospheric depth in terms of energy, which is produced by extrapolation and interpolation statistical method, raises and falls meaningfully that is compatible to the results of Pierre Auger observatory. At higher energies, the percentage of primary particles have a tendency to heavier particles and in low energies the primary particles are lighter. Also, the most important breaks in the energy spectrum of cosmic rays are seen.در کار فعلی، کامپوزیت هیبریدی جدید با مخلوط کردن نانوکلوئید طلا به صورت فیزیکی تهیه شده است
https://ijpr.iut.ac.ir/article_3425.html
In current work, new hybrid composite have been prepared by mixing gold nanocolloid physically with PVA-Fe2O3. Morphological, compositional, structure and optical properties of hybrid composites were studied by transmission electron microscope (TEM), scanning electron microscope (SEM), energy dispersive spectroscopy (EDS), Fourier transform infrared spectroscopy (FTIR), X-ray diffraction (XRD) and UV-visible spectroscopy (UV-VIS). XRD results showed that both Au and Fe2O3 have peaks in the structure and that confirmed by EDS and FTIR results. Microscopes results indicated the nanosized nature of prepared materials. UV&ndash;vis spectrum show absorption edge at 440 nm which relates to PVA-Fe2O3 mixed with Au which means there is a red shift after incorporation of Au in the composites. And the energy gap of composite became equal to 2.48 eV after adding Au solution.Ni_ZnO doped nanorod/glass prepared by chemical bath deposition.
https://ijpr.iut.ac.ir/article_3426.html
In this paper, Ni-doped ZnO nanorods (NRs) with concentrations of (0%, 1%, 2%, and 4%) were successfully grown on glass slides by Chemical bath deposition CBD at (85-90) &deg;C. X-ray diffraction (XRD), Field Emission Scanning Electron Microscopy (FESEM), and UV- Vis spectrum were performed to characterize the prepared films. The results of the X-ray diffraction measurements of the samples showed that all the prepared films were of a crystalline structure of the hexagonal type with the dominance of growth in the (002) direction and a decrease in the intensity of the peak characteristic with increased Ni-doped. The FESEM images show the average diameters of ZnO NRs, Ni (1%) NRs, Ni (2%) NRs and Ni (4%) NRs, there is a clear increase in the rate of the average diameters by increasing the percentage of doping. The band gap of seed layers ZnO and undoped ZnO nanorods /glass was found to be 3.25 eV and 3.2 eV respectively. The values of the optical energy gap of Ni-doped ZnO are about (3.12, 3.09, 3) eV with an increase in the rate of doping. The results of the optical and structure measurements also included calculating parameters micro strain (&epsilon;),about the Ni doped ZnO (0%, 1%, 2%, and 4%) films for (100),(002),and(101).Enhancement of Spontaneous Emission and Material Gain from CdSe/CdS Quantum Dot
https://ijpr.iut.ac.ir/article_3427.html
This study looks at the material gain and enhanced spontaneous emission of CdSe(1-x)S(x)/ZnS and CdSe(1-x)S(x)/ZnO quantum dot (QD) structures. cadmium selenide (CdSe) QDs, cadmium sulfide (CdS) wetting layer (WL), zinc oxide (ZnO) and zinc sulfide (ZnS) as a barrier layers were investigated to achieve QDs semiconductor with active region (B). The energy levels and band alignment between layers are predicted using the quantum disk model. Gain is an estimation for the transverse electric (TE) and magnetic (TM) modes in QDs structures, taking into consideration the momentum matrix element. The mole-fraction (x) and contributions of the barriers (ZnO and ZnS) material in enhanced gain and spontaneous emission were investigated in this manuscript. When ZnS is used as a barrier material, the spontaneous emission is found to be 11.75&times;1019 (eV.sec.cm3)&minus;1 at x~0.69 and wavelength 324 nm, and the material gain has maximum values of order 5.671&times;104 cm&minus;2 for TM and 3.743&times;107for TE modes, respectively. Whenever the barrier is changed to ZnO, the results are different; at x~0.438 and wavelength 365 nm, the spontaneous emission becomes 2.965&times;1019 (eV.sec.cm3)&minus;1 and the gain has maximum values of order 2.118&times;104cm&minus;2 for TM and 1.242&times;105cm&minus;2for TE mode.The Role of the Temperature Anisotropy in the Deuterium-Tritium Fuel Ignition Under the Effect of Relativistic Shock Waves
https://ijpr.iut.ac.ir/article_3428.html
This study explores the impact of temperature anisotropy on the ignition criterion of deuterium-tritium fuel in nuclear fast ignition fusion schemes that rely on short-pulse lasers-generated shock waves. The results indicate that increasing the temperature anisotropy parameter, &beta;=T&perp;/T∥, unexpectedly increases the fraction of 𝛼-particles created and deposited into the ignition domain. For &beta; is less than1, the maximum confinement parameter is less than 4 g/cm2. While for &beta; is greater than 1, the maximum confinement parameter is more than 4 g/cm2.The fusion energy fraction decreases during the laser pulse irradiation of the fuel (1 picosecond). By increasing the temperature anisotropy parameter, &beta;=T/&perp;T∥, by a factor of 100, the value of plasma density times the hot spot dimension required for fuel ignition can be increased by 38%. For &beta;&lt;1, the fusion energy fraction deposited decreases with time and reaches its minimum value of about 0.1 at the end of the laser pulse.Formation of Self-Organized TiO2 Nanotube Arrays and Its Photoelectrochemical Response
https://ijpr.iut.ac.ir/article_3429.html
In this study, TiO2 nanotube arrays (TNTAs) are produced using an efficient, low-cost, and ecofriendly environmental anodization process in an electrolyte containing Glycerin. The TNTAs were annealed for 2 hours at 500 &deg;C. X-ray diffraction (XRD), scanning electron microscopy (FES-SEM), UV-Vis diffuse reflectance spectroscopy (DRS), photoluminescence (PL), and photoelectrochemical properties (PEC) were used to analyze the sample. According to the obtained findings, the photoelectrochemical response of the TiO2 film was accomplished with a current density (Jph) of 0.196 mAcm-2 and photoconversion efficiency of 0.14%.Graphitic carbon nitride/MIL-88B(Fe) Nanocomposite for Methylene Blue Dye Removal from Aqueous Solution by UV-Visible Light Active Photo-Fenton Reaction
https://ijpr.iut.ac.ir/article_3430.html
In the present research, g-C3N4/MIL-88B(Fe) nanocomposite photocatalyst was successfully synthesized by the solvothermal method. The morphology, crystal structure, chemical functionalities, and optical properties of the obtained nanocomposite were investigated by scanning electron microscopy (SEM), transmission electron microscopy (TEM), X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), and UV-Vis diffuse reflectance spectroscopy (DRS), respectively. According to the SEM and TEM images, spindle-shaped MIL- 88B(Fe) nanostructures were synthesized with an average length and width of 2 and 1 &mu;m, respectively. Furthermore, g-C3N4 nanoparticles with an average diameter of 30 nm were observed on the surface of the MIL-88B(Fe). Based on the XRD results, the presence of both g-C3N4 and MIL-88B(Fe) nanostructures in the prepared composite was confirmed. Also, the presence of functional groups of the MIL-88B(Fe) and g-C3N4 was determined by FTIR. Based on DRS analysis and Tauc's plot, the band gap energy of the prepared composite was measured as 2.1 eV, which indicated that the prepared composite could absorb light in the visible region. The degradation of organic pollutant methylene blue (MB) in the g-C3N4/MIL- 88B(Fe)+light+H2O2 system was investigated to evaluate the photo-Fenton activity of the prepared composite in comparison with light and light+H2O2 systems. The results showed that the presence of g-C3N4/MIL-88B(Fe) composite increased the degradation rate of MB pollutant under the photo-Fenton process by 8.1 and 2.8 times higher than the mentioned systems, respectively. Thus, MB removal efficiency reached 100% within 20 min of illumination. The superiority of the g- C3N4/MIL-88B(Fe)+light+H2O2 system can be attributed to the retardation of electron-hole recombination due to the presence of two nanostructures of g-C3N4 and MIL-88B(Fe) in heterojunction, which has led to an increase in the efficiency of the photo-Fenton reaction.Relativistic effects in the study of structure and electronic properties of UO2 within DFT+U method
https://ijpr.iut.ac.ir/article_3431.html
Electrons of orbitals near to nuclei of heavy atoms acquire speeds comparable to the speed of light in vacuum. Therefore, to study the properties of crystals containing heavy atoms, it is necessary to take into account the relativistic effects. In this work, using the first-principles DFT+U method, we have calculated the electronic structure and geometric properties of uranium dioxide UO2 within full-relativistic, scalar-relativistic, and non-relativistic formulations, and compared the results. It is shown that: (i) the non-relativistic scheme gives results very far form experimental values for both lattice constant and bang gap; (ii) in full-relativistic case which the spin-orbit effects are included, the Kohn-Sham band-gap is increased by 6.2% and the lattice constant decreases by 0.05% compared to scalar-relativistic one. Therefore, in the study of geometric properties of UO2, using the scalar-relativistic regime is quite accurate and one does not need to perform much more expensive full-relativistic calculations whenever one does not study the electronic excitation properties.Spin transfer torque in graphene-based domain walls
https://ijpr.iut.ac.ir/article_3432.html
A scattering matrix formalism is employed to calculate the spin transfer torque in a graphene-based domain wall in the ballistic regime. We have suggested a new method for manipulating the direction of domain wall motion by both the length of the DW and magnetic barrier that is the ratio of induced exchange field to Fermi energy. It has also shown that spin current density give us more insight about the transmission of spin-polarized electrons and We have shown a method for changing the direction of DW motion.تقویت حسگر گاز سولفید هیدروژن (H2S) بر اساس نیمه هادی اکسید فلز (NiO) نازک
https://ijpr.iut.ac.ir/article_3433.html
The morphological and structural properties of NiO films have been studied to find out the possibility of exploit it as a gas sensor. The thin film of the nickel oxide has been obtained by a chemical spray pyrolysis technique on glass substrates using various concentrations of nickel nitrate hexahydrate [Ni(NO3)2:6H2O] aqueous solution. The produced films were characterized using X-Ray diffraction and atomic force microscopy. The investigations revealed that the crystal structure are a cubic polycrystalline with preferential orientation along the (111) plane. The topographical analyse (AFM) shows that the values of the grain size increasing with increase the concentration, where average of the grain diameter raised from 42.04-110.058 nm of 0.01 M and 0.1M concentrations respectively. The gas sensing results demonstrate that sensitivity of nickel oxide semiconductor films to the hydrogen sulfide gas are affected by the size of the growing crystallites and the operating temperatureOptical and thermochromic properties of yttrium iron garnet paint
https://ijpr.iut.ac.ir/article_3434.html
In this study, we investigated the optical and high-temperature thermochromic characteristics of yttrium iron garnet powder and paint. The powders were produced using the solid-state reaction technique, and the thermochromic paint was sprayed over an Al alloy substrate. X-ray diffraction patterns, optical and field emission scanning electron microscopes, and UV-Vis and FTIR spectrophotometers were used to assess the structural, surface morphology and optical characteristics of the materials. The thermochromic characteristics of the materials were investigated by extracting the chromatic coordinates L*b*a* from digital pictures taken at temperatures ranging from 25 to 210 &deg;C. The results reveal that when the temperature rises, the color of the paint changes from dark green to dark brown. The charge transfer between oxygen and iron ions, as well as the electron transition across the orbitals of the d layer, could be responsible for the reversible color change. The paint has strong thermal stability up to 350 &deg;C which is suitable for high-temperature thermochromic applications.Gravitational Collapse of the Galactic Dark Matter
https://ijpr.iut.ac.ir/article_3435.html
A spherically symmetric matter collapses under its own gravity. Forthe Milky way, the time scale of collapse for a spherical halo with NFWdensity is 26My which is very small compared to the age of the MilkyWay. The effect of a pressure, obeying a polytrope equation of state isinvestigated. It is shown that for p~&rho;^(9/8), the time scale would be of theorder of 1 Gy. It is also argued that such a polytrope, if considered to bein equilibrium, could explain the rotation curve of the milky way.Synthesis of high transparency of F doped NiO monocrystalline thin films by spray deposition
https://ijpr.iut.ac.ir/article_3436.html
F doped NiO monocrystallineFinding Larger Tensor-to-Scalar Ratio in the Framework of Trans-Planckian Censorship Conjecture
https://ijpr.iut.ac.ir/article_3437.html
Trans-Planckian censorship conjecture prohibits that the sub-Planckian wavelengths during inflation to become classical. Under standard assumptions on the speeds of the tensor-to-scalar ratio, which set the speed of these perturbations equal to the light speed, the upper bound on the tensor-to scalar ratio is reduced to the extent that there will be no prospect for the detection of tensor perturbations in the CMB. In this article, we show that with reducing the speed of tensor perturbations one can enhance the tensor-t-scalar ratio to an observable limit without violating the criteria of the effective field theory of inflation.3D Wave Expansion Solution in Spherical Multilayer Structures for Acoustic Illusion
https://ijpr.iut.ac.ir/article_3438.html
In this paper, a technique for creating an ideal acoustic illusion in three dimensions based on transformation acoustic theory and solutions of acoustic wave equations in terms of spherical harmonics is presented. The technique employs a three-dimensional structure consisting of concentric spherical shells made of homogeneous and isotropic materials that alter the scattering pattern of acoustic waves. To examine changes in the scattering pattern, the expansion coefficients in the scattered acoustic wave equation are calculated, and the scattering pattern in each layer of the structure is computed. By placing an object inside the core of this structure, the desired acoustic illusion is created. The foregoing acoustic illusion is identified by comparing the scattering pattern of this object inside the core structure to that of another object with different acoustic parameters and sizes (transformed). One of the advantages of this technique is the elimination of the limitation of cylindrical devices in the z-axis due to the spherical nature of the acoustic parameters of the structure and their independence of angles in spherical coordinates. This technique is a useful method for increasing accuracy in medical tissue imaging using ultrasound devices. In other words, by utilizing this technique, one can take advantage of higher-quality images of sensitive tissues in ultrasound devices.Investigation of the beam loading effects in a constant-impedance traveling wave acceleration tube
https://ijpr.iut.ac.ir/article_3439.html
In a high power linear accelerator, the current factor is a limiting parameter and affects the energy gain of the particles. Beam has the ability to excite acceleration modes and higher-Order. The beam effects in the excitation of acceleration modes are known as beam loading. In this article, the beam loading effect for a constant impedance traveling wave accelerating tube in S band is simulated by CST software and the results are compared with the theoretical relation obtained from energy conservation. The main purpose of this article is to investigate the effects of beam loading in constant impedance acceleration structures. The comparison of the results shows that there is a good match between the simulation and the theoretical relationship. The results show that the beam loading effects cannot be compensated by changing the radiofrequency design. The results of this study will be used to design a high-powered accelerator with an energy of 30 MeV and an average power of 30 kW in the S band.Optimization of some input Parameters of a pulsed TEA CO2 Laser based on the generalized Landau-Teller equations
https://ijpr.iut.ac.ir/article_3440.html
In this paper, the six-temperature kinetic model based on the generalized landau-Teller equations is used to optimize a pulsed TEA CO2 laser input parameters. This model was numerically solved by regarding the equations governing the electrical discharge media to obtain density of electrons. In this study, for the first time, the dissociation of the CO2 molecule and the production of CO as a time evaluation equation were dynamically coupled with other rate equations. The time behavior of the discharge current and voltage and laser output pulse power was simulated for CO2:N2:He gases mixture ratio, which are 1:1:3, respectively. Also, the optimum values of the input parameters including the reflectivity of the output mirror, the capacity of the pre-ionization capacitor, and the capacity and charging voltage of the storage capacitor were calculated to obtain the maximum output peak power. The obtained results are significant in the optimum design of TEA CO2 oscillators.Hidden Symmetry of Three Dimensional Rotating Black Hole
https://ijpr.iut.ac.ir/article_3441.html
In This work, we study explicit and hidden symmetries of curved space-time. The explicit and hidden symmetries share the feature that their generators in the phase space of probe particle are constants of motion. Their difference is that the generator of hidden symmetry is given by the contraction of Killing tensor by two or more particle momenta while for the explicit symmetry, this generator is linear in particle momentum. Therefore, we can read the Killing tensors of a curved space-time using the constants of motions associated with its probe particle. The Killing tensors of four-dimensional and also higher-dimensional geometries have been studied. In this work, we answer the question about the existence of hidden symmetry in the three-dimensional rotating black hole. To this end, we independently analyze two types of probes: free particle and scalar field. Using the related constants of motion, we show that the Killing tensor of this three-dimensional black hole is trivial.Phase behavior of hard rods between two walls: Phase change of particles without occurring phase transition
https://ijpr.iut.ac.ir/article_3442.html
In this study, we investigated the phase behavior of rods with square ( ) and circular (diameter D) cross sections between two hard walls using the Parsons-Lee theory and applying the Zwanzig approximation. Our focus is to find wall-to-wall separations (H) and size of particles in which the phase of the system changes without occurring a phase transition. It was determined that if the distance between the plates is smaller than the length of the particles, for any particle whose length (L) to diameter ratio is greater than 1, the second order phase transition occurs and most of the particles are placed in a certain direction parallel to the plates, which this type of phase transition takes place at lower densities with increasing particle&rsquo;s aspect ratio. We also came to the conclusion that if the distance between the plates is greater than and , despite the phase change of the system with increasing particle density, no phase transition will occur. In addition, it was found that the cylindrical shaped particles show some unexpected behaviors, which could be due to the inappropriate performance of the applied theory or their real physical behavior, which requires more detailed studies to resolve the ambiguity.Behavior of the transition region on the wave propagation at the solar atmosphere
https://ijpr.iut.ac.ir/article_3443.html
Studying of megnetohydrodynamic waves in solar magnetic structures such as coronal loops, spicules, etc. can be very important for investigating the problem of heating the Sun&rsquo;s outer atmosphere. For this purpose, a magnetic flux tube was considered in the presence of steady flow and sheared magnetic field in a stratified atmospheric layer. The transition region is a boundary layer between the solar chromosphere and corona, which has very rapid changes in temperature and density. The effect of the transition region on the damping of Alfven waves and temperature changes with height were applied in the assumed flux tube. The Cartesian two-dimensional model was used to solve the magnetohydrodynamic equations and the results were obtained from the damping in the form of graphs of temporal and spatial changes of the perturbed velocity and magnetic field. The graphs showed that the damping of Alfven waves is more visible with time than with space, so the more rapid the damping occurs, the more energy will be transferred to the corona.The study of θφ component of the viscous stress tensor in the protoplanetary discs
https://ijpr.iut.ac.ir/article_3444.html
Observation and numerical documents have shown that the protoplanetary discs (PPDs) around the young stellar objects (YSOs) to be gravitationally unstable. The self-gravity can be important in PPDs . The gravitational instability and outflow (mass-loss) are dominant mechanisms for transporting outward angular momentum and inward accretion in the disc cold mid-plane. The structure of the self-gravitating accretion discs depends strongly on the rate at which it cools. In this paper, we have studied the hydrodynamical equations in the presence of &theta;&phi; component of the viscous stress tensor (t_&theta;&phi;) in the spherical coordinates (r,&theta;,&phi;) by using the semi analytical self similar solutions in the steady state and axisymmetric assumptions. This component of the viscous stress tensor is related to transport outward angular momentum by outflows. The solutions indicate that the disc is gravitationally instable. The gravitational instability as a viscose source leads to heat the disc. Our results have shown the Toomre parameter (Q) decreases by increasing the cooling rate because the heating supplied by gravitational instability is not enough to counteract cooling and so the disk will fragment and produce planets. The results have shown that t_&theta;&phi; makes the disc colder and thinner and outflows form in the regions with lower latitude. We have shown that the effect of t_&theta;&phi; in the mid-plane of the disc is more effective than t_r&phi; (turbulent viscosity).Investigating Ion Acoustic Waves in Dusty Plasmas Containing Warm Ions, Non-thermal Electrons and Positrons with Cairns Distribution
https://ijpr.iut.ac.ir/article_3445.html
This study investigated nonlinear ion acoustic solitons in a dusty plasma system, consisting of negatively charged dust particles, dynamic warms ions, electrons and positrons with non-thermal Cairns distributions. The nonlinear differential equation governing this system was obtained in two steps using the reductive perturbation method. In the first step, the nonlinear differential equation KdV was obtained considering lower-order powers. The results showed the nonlinear coefficient of the mentioned equation was zero at the critical value in the desired system and this equation could not describe the solitons propagated in the system. In the next step, the modified KdV equation was obtained like the previous section using the reductive perturbation method, taking into account higher-order power. The results showed dispersion coefficients were the same in both cases. However, the nonlinear coefficient was more complicated in the modified case. In both cases, static solutions of solitons were investigated, and the effect of various parameters, including non-equilibrium of electrons and positrons, on the wave structure was examined in detail. The results revealed unlike Maxwell&rsquo;s distribution, in which only positive solitons could be propagated, both positive and negative solitons could be propagated in this system. Also, the presence of non-equilibrium particles could increase the soliton amplitude and width. The obtained results could be used in space and laboratory plasma systems.g-SiC and g-SiC2 Siligraphenes as two Multifunctional H2S Sensing Materials
https://ijpr.iut.ac.ir/article_3446.html
The main purpose of this article is to investigate the capability of g-SiC and g-SiC2 siligraphenes in detecting H2S gas through diverse sensing mechanisms, using density functional theory. The results of our calculations demonstrate that the adsorption of H2S molecule onto both siligraphenes is a physical and exothermic process. The Physical adsorption process helps sensing materials to recover soon (few nanoseconds) after gas removal at room temperature. Investigation of geometric and electronic properties of g-SiC and g-SiC2 in combination with H2S molecule shows that both materials have the gas-detection ability through thermal- and resistance-based mechanisms. For example, the electrical conductance of g-SiC changes by 38% in result of gas adsorption. In addition, the presence of H2S molecule on the g-SiC surface, changes the type of its majority carriers and makes it possible to use this material in Seebeckeffect-based H2S sensors. Overall, various sensing mechanisms besides short recovery time, make g-SiC and g-SiC2 great candidates to be used in H2S gas sensor as sensing material.Anisotropic magnetoresistance in La0.4Pr0.3Ca0.3MnO3 thin films
https://ijpr.iut.ac.ir/article_3447.html
The paper presents a study on the magnetoresistance (MR) and anisotropic magnetoresistance (AMR) properties of La0.4Pr0.3Ca0.3MnO3 (LPCMO) thin films. The thin films were grown using pulsed laser deposition method on LaAlO3 (LAO) (111) and MgO (MGO) (100) substrates, with a thickness of approximately 90 nm as estimated by X-Ray reflectometry (XRR) method. The LPCMO sample on the LAO substrate exhibited a lower metal-insulation transition than the one on MgO substrate due to high compressive stress. The MR was found to be 57% and 98% for LPCMO/LAO and LPCMO/MGO films, respectively. The LPCMO/MGO sample also showed a significantly higher MR (80%) compared to LPCMO/LAO sample (32%), indicating its potential application.The effects of charge on the persistence length of biopolymers
https://ijpr.iut.ac.ir/article_3448.html
Flexibility and rigidity of biopolymers in mechanical structure have been investigated several times. Persistence length of a polymer is an exact factor to specify value of flexibility. No doubt that existence of charge on the polymers would have effect on the value of flexibility and therefore change in the persistence length of the polymer. In this study by use of molecular dynamic simulation and Gaussian chain model (bead-spring model), we have investigated the effect of electric charge and salt concentration on the persistence length of the biopolymers in the cell. This simulation has been able to provide acceptable detail in the results.Encoding and transmission of information based on Radial Carpet beams and convolutional neural network detection
https://ijpr.iut.ac.ir/article_3449.html
Radial carpet beams are a novel form of structured light that falls under the category of combined half-integer Bessel-like beams. This study introduces the radial carpet beam as a means of information transmission and a solution for expanding the information encoding freedoms. The method employed for detecting and classifying these beams is the convolutional neural network (CNN). To conduct the study, a dataset consisting of 16 different classes of radial carpet modes was prepared. These modes were propagated through underwater turbulence conditions over a distance of 120 cm. The convolutional neural network used in the study was based on the widely recognized DenseNet-201 architecture, utilizing transfer learning techniques. The trained model achieved a 97% accuracy in mode detection and classification. Subsequently, the performance of the proposed model was evaluated by transmitting and receiving a 4-bit grayscale image measuring 150 x 200 pixels through an underwater communication link based on radial carpet modes. The evaluation results clearly demonstrate the potential for achieving new encoding options with radial carpet beams. Moreover, the convolutional neural network method proves to be an optimal approach for detecting and classifying structured light beams. This method alleviates the challenges associated with using multiple optical components in coherent detection techniques, which traditionally rely on diffraction gratings. In addition to simplifying optical system configuration, it also reduces implementation costs and volume, particularly in optical communication applications.Comparison of direct DNA damage by protons and oxygen, carbon, and helium ions using Geant4-DNA code
https://ijpr.iut.ac.ir/article_3450.html
Ionizing radiations can directly affect cells by inducing DNA breaks. This impact includes single-stranded and double-stranded failures; which may cause cell death and mitotic failure. In the present study; With the help of an atomic DNA model built in the Geant4-DNA code and its initial validation, direct DNA damage by interaction with carbon ions 114/u2 MeV, 134/21 MeV/u oxygen, 62/83 MeV/u helium and radiation 62MeV protons have been investigated. For this purpose; After the initial validation, the results of single-stranded, double-stranded fractures and double-stranded fracture efficiency at depths of 5 to 30.7 mm were evaluated for the mentioned ions. The ratio of single strand breaks for oxygen ions at 5 mm (and the location of the Bragg peak: 30.7 mm), 1.85 (1.55), 4.19 (9.42) and 10.6, respectively. (22/24) is more than carbon ions, helium and proton rays. On the other hand; The two-strand break at a depth of 5 mm for oxygen, carbon, helium and proton ions is equal to 0.09, 0.05, 0.01 and 0.005 respectively. These values were calculated as 2.09, 1.34, 0.22, and 0.03 at the place of the Bragg peak (with a significant increase). results show; Heavy ions behave much more effectively than light ions and protons in terms of biological effects (in the form of single- and double-strand breaks), therefore, they are more effective options for inhibiting or controlling cancer cells.Study of the impact of polarization and shape factor on the nonlinear optical
response of a hybrid molecule including a semiconductor quantum dot coupled
two metallic nanoparticles: second harmonic generation
https://ijpr.iut.ac.ir/article_3451.html
In this paper, the generation of second-harmonic from a hybrid molecule composed of two metal nanoparticles withellipsoidal shape coupled to a semiconductor quantum dot when a control laser field is applied to the system by usingthe density matrix approach is investigated. This applied field induces a polarization in the semiconductor quantum dotand both different plasmonic nanoparticles, and the polarized metal nanoparticles interact with the quantum dot throughdipole&ndash;dipole interaction. We demonstrate that SHG strongly depends on the shape factor and the light polarization foroblate and prolate spheroidal plasmonic nanoparticles coupled with quantum dot when the applied field is parallel orperpendicular to the axis of the system. The study of the light-matter interaction in such hybrid molecule canuseful to design the optical devices based on the plasmon-exciton-plasmon interaction.Study of temperature distribution in a metallic nanograting based on a Kerr nonlinear material irradiated by a nanosecond pulsed laser
https://ijpr.iut.ac.ir/article_3452.html
In this article, we investigate the temperature distribution in a one-dimensional metallic nanograting heated by a nanosecond Gaussian pulse laser using the finite element method. It is assumed that the nanograting slits are filled with a Kerr-type nonlinear material. The results indicate a strong dependency of the system's temperature distribution on the incident laser fluence. Also, the temperature distributions are completely diffferent for linear and nonlinear regimes at high laser fluences around the pulse peak and after that. Indeed, exciting the nonlinear optical Kerr effect, especially at high laser fluences, leads to a change in the temperature response of the nonlinear regime compared to the linear one. Moreover, depending on the applied laser wavelength, there is a possibility of increasing or decreasing the temperature compared to the linear case. On the other hand, one can not enhance the laser fluence to any amount, as this may raise the temperature even higher than the melting point of the materials. Therefore, as the strong laser pulses are applied, it should be surveyed the temperature investigations to prevent excessive heating and damage to the system.