Isfahan University of Technology,
The Physics Society of IranIranian Journal of Physics Research1682-695724120240521Who are considered as authors of the article?Who are considered as authors of the article?3482FAReza AsgariEditor-in-ChiefJournal Article20240713https://ijpr.iut.ac.ir/article_3482_af076ff9a9377e5d1ab93c7099d98487.pdfIsfahan University of Technology,
The Physics Society of IranIranian Journal of Physics Research1682-695724120240521Controllability in nonlinear dynamical systems: a compartmental modelControllability in nonlinear dynamical systems: a compartmental model18345510.47176/ijpr.24.1.11606FAFarinaz RoshaniDepartment of Physics, Alzahra University, Tehran, Iran0000-0001-6487-5509Zeinab Mardi GheshlaghiDepartment of Physics, Alzahra University, Tehran, Iran0009-0000-7860-6748Journal Article20221207Controllability is our ability to steer a dynamic system to a desired final state in finite time. A compartmental model is general mathematical modeling used to predict the time evolution of complex systems. We consider a three-dimensional nonlinear system with a transition threshold. It has only one steady state (equilibrium fixed point) which it reachs a long period. Our goal is to drive this system towards the desired stable fixed point at the beginning of the dynamics (finite time). The nonlinear system was investigated as a compartmental model. We used the control strategy of multidimensional dynamical systems and proposed the canonical transformation from which the control function was obtained. In order to show that the fixed points of the system are stable, we used the linear stability method and the Gershgorin circle theorem. By numerically solving the differential equations after control, the system reached the desired fixed points in a finite time. We plotted the state space for different fixed points, and four regions were obtained. We found the points where the control function can steer the system to a stable state in a finite time. We found fixed points that are non-physical.Controllability is our ability to steer a dynamic system to a desired final state in finite time. A compartmental model is general mathematical modeling used to predict the time evolution of complex systems. We consider a three-dimensional nonlinear system with a transition threshold. It has only one steady state (equilibrium fixed point) which it reachs a long period. Our goal is to drive this system towards the desired stable fixed point at the beginning of the dynamics (finite time). The nonlinear system was investigated as a compartmental model. We used the control strategy of multidimensional dynamical systems and proposed the canonical transformation from which the control function was obtained. In order to show that the fixed points of the system are stable, we used the linear stability method and the Gershgorin circle theorem. By numerically solving the differential equations after control, the system reached the desired fixed points in a finite time. We plotted the state space for different fixed points, and four regions were obtained. We found the points where the control function can steer the system to a stable state in a finite time. We found fixed points that are non-physical.https://ijpr.iut.ac.ir/article_3455_6a895a050af3fc353c632d56c09153eb.pdfIsfahan University of Technology,
The Physics Society of IranIranian Journal of Physics Research1682-695724120240521The study of θφ component of the viscous stress tensor in the protoplanetary discsThe study of θφ component of the viscous stress tensor in the protoplanetary discs919344410.47176/ijpr.24.1.71709FAMehdi Nezhad KahnoojiFaculty of Physics, Shahid Bahonar University of Kerman, Kerman, IranMaryam GhasemnezhadFaculty of Physics, Shahid Bahonar University of Kerman, Kerman, IranJournal Article20230701Observation and numerical documents have shown that the protoplanetary discs (PPDs) around the young stellar objects (YSOs) are gravitationally unstable. The self-gravity can be important in PPDs.<strong> </strong>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<strong> </strong>studied the hydrodynamical equations in the presence of component of the viscous stress<strong> </strong>tensor (t_θφ) in the spherical coordinates (r,θ,φ) by using the semi- analytical self- similar solutions in the steady state and axisymmetric assumptions.<strong> </strong>This component of the viscous stress tensor is related to the transport outward of angular momentum by outflows. The solutions indicate that<strong> </strong>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_θφ makes the disc colder, and thinner and outflows form in the regions with lower latitudes. We have shown that the effect of t_θφ in the mid-plane of the disc is more effective than t_rφ (turbulent viscosity).Observation and numerical documents have shown that the protoplanetary discs (PPDs) around the young stellar objects (YSOs) are gravitationally unstable. The self-gravity can be important in PPDs.<strong> </strong>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<strong> </strong>studied the hydrodynamical equations in the presence of component of the viscous stress<strong> </strong>tensor (t_θφ) in the spherical coordinates (r,θ,φ) by using the semi- analytical self- similar solutions in the steady state and axisymmetric assumptions.<strong> </strong>This component of the viscous stress tensor is related to the transport outward of angular momentum by outflows. The solutions indicate that<strong> </strong>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_θφ makes the disc colder, and thinner and outflows form in the regions with lower latitudes. We have shown that the effect of t_θφ in the mid-plane of the disc is more effective than t_rφ (turbulent viscosity).https://ijpr.iut.ac.ir/article_3444_df0abc9e52307bae0c67ccedbb5558aa.pdfIsfahan University of Technology,
The Physics Society of IranIranian Journal of Physics Research1682-695724120240521Studying the effect of oscillating electric field in time and space on neuronal activity using the extended point neuron modelStudying the effect of oscillating electric field in time and space on neuronal activity using the extended point neuron model2133348310.47176/ijpr.24.1.01766FAMaryam GhorbaniBiomedical Engineering Branch, Department of Electrical Engineering, Faculty of Engineering, Ferdowsi University of Mashhad, Mashhad, IranFiroozeh Naderkam FirooziBiomedical Engineering Branch, Department of Electrical Engineering, Faculty of Engineering, Ferdowsi University of Mashhad, Mashhad, IranSeyyed Nader RasuliSchool of Physics, Institute for Research in Fundamental Sciences (IPM), Tehran, IranJournal Article20231013According to the electrical-chemical structure of nerve cells, it is expected that applying electrical stimulation affects the dynamics of neural networks, and strengthens or weakens brain activity. On this basis, in the last two decades, the use of electrical stimulation to treat neurological disorders such as depression, epilepsy, Parkinson's, etc. has gained wide acceptance.But the response of nerve tissue to external stimulation is not linear, that is, empirical studies on animal models as well as computational modeling show that changes in the amplitude and pattern of changes in electrical stimulation can lead to completely different results. However, in most stimulation methods, the electric field resulting from direct injection of current to the head (and brain) is relatively low in intensity. But the incomplete understanding of the mechanism and complexities of electrical stimulation sometimes forces physicians to adopt a trial-and-error approach<strong>.</strong> It means that it actually puts the patient at risk. Using computational modeling, we have analytically calculated the response of the single neuron membrane to the extracellular current stimulation that oscillates in space and time, and investigated the effect of different characteristics of the extracellular stimulation on the neuronal response. In particular, we have for the first time fully considered the spatial non-homogeneity of the electric field, and its effect on neuron activity, using the extended point model, which is simple but contains the geometrical information of the neuron. The obtained results show that the time-frequency-dependent response of neurons strongly depends on the spatial frequency and phase of stimulation. In fact, the intensity of field non-homogeneity in space can affect the frequency behavior of the neuron. The results of this study help to design optimal methods for nerve tissue stimulation, as well as to estimate the amount of risks caused by unwanted exposure to electric fields.According to the electrical-chemical structure of nerve cells, it is expected that applying electrical stimulation affects the dynamics of neural networks, and strengthens or weakens brain activity. On this basis, in the last two decades, the use of electrical stimulation to treat neurological disorders such as depression, epilepsy, Parkinson's, etc. has gained wide acceptance.But the response of nerve tissue to external stimulation is not linear, that is, empirical studies on animal models as well as computational modeling show that changes in the amplitude and pattern of changes in electrical stimulation can lead to completely different results. However, in most stimulation methods, the electric field resulting from direct injection of current to the head (and brain) is relatively low in intensity. But the incomplete understanding of the mechanism and complexities of electrical stimulation sometimes forces physicians to adopt a trial-and-error approach<strong>.</strong> It means that it actually puts the patient at risk. Using computational modeling, we have analytically calculated the response of the single neuron membrane to the extracellular current stimulation that oscillates in space and time, and investigated the effect of different characteristics of the extracellular stimulation on the neuronal response. In particular, we have for the first time fully considered the spatial non-homogeneity of the electric field, and its effect on neuron activity, using the extended point model, which is simple but contains the geometrical information of the neuron. The obtained results show that the time-frequency-dependent response of neurons strongly depends on the spatial frequency and phase of stimulation. In fact, the intensity of field non-homogeneity in space can affect the frequency behavior of the neuron. The results of this study help to design optimal methods for nerve tissue stimulation, as well as to estimate the amount of risks caused by unwanted exposure to electric fields.https://ijpr.iut.ac.ir/article_3483_622bf02f457cfc6f5be2748b7a33b4c2.pdfIsfahan University of Technology,
The Physics Society of IranIranian Journal of Physics Research1682-695724120240521Modeling the optical response of plasmonic nanoparticlesModeling the optical response of plasmonic nanoparticles3550348710.47176/ijpr.24.1.11828FAYeganeh RanjouriPhysics Department, Zanjan University, Zanjan, IranHamid NadjariPhysics Department, Zanjan University, Zanjan, Iran0000-0001-6971-5694Journal Article20240121In this research, the optical response of gold and silver plasmonic nanoparticles to incident plane wave with intensity of 13.3 W/cm<sup>2</sup> has been modeled for two geometrical structures of a whole sphere and a quarter sphere in the radial range 1 to 500 nm. The Helmholtz equation was solved by the FEM method and by applying the PEC and PMC boundary conditions with the appropriate mesh selection, for each of the geometrical structures independently, and the corresponding absorption and scattering spectra were obtained. The scattering pattern for gold nanoparticles at selected radii of 20, 50, 80, 100 and 500 nm shows that the minimum scattering intensity for the first three radii occurs at angles of 90, 85 and 65 degrees, respectively. As the radius increases, the minima are observed far away from the 90- degree angle, and the number of them also increases. Modeling at radii greater than 100 nm leads to the production of plasmonic nanojets while dipolar behavior occurs below 30 nm radius. We have determined the radial range of the maximum surface enhancement of the electric field for silver nanoparticles. The tunability of the SPR location with the dielectric constant of the medium and the radius of the nanoparticles has been investigated. We have shown that the red shift for 5, 10, 15, 20, 25 and 30 nm nanoparticles equals to 56, 72, 206, 232, 252 and 262 nm, respectively.In this research, the optical response of gold and silver plasmonic nanoparticles to incident plane wave with intensity of 13.3 W/cm<sup>2</sup> has been modeled for two geometrical structures of a whole sphere and a quarter sphere in the radial range 1 to 500 nm. The Helmholtz equation was solved by the FEM method and by applying the PEC and PMC boundary conditions with the appropriate mesh selection, for each of the geometrical structures independently, and the corresponding absorption and scattering spectra were obtained. The scattering pattern for gold nanoparticles at selected radii of 20, 50, 80, 100 and 500 nm shows that the minimum scattering intensity for the first three radii occurs at angles of 90, 85 and 65 degrees, respectively. As the radius increases, the minima are observed far away from the 90- degree angle, and the number of them also increases. Modeling at radii greater than 100 nm leads to the production of plasmonic nanojets while dipolar behavior occurs below 30 nm radius. We have determined the radial range of the maximum surface enhancement of the electric field for silver nanoparticles. The tunability of the SPR location with the dielectric constant of the medium and the radius of the nanoparticles has been investigated. We have shown that the red shift for 5, 10, 15, 20, 25 and 30 nm nanoparticles equals to 56, 72, 206, 232, 252 and 262 nm, respectively.https://ijpr.iut.ac.ir/article_3487_19f67253bf5bbd5065e9b12d203c120a.pdfIsfahan University of Technology,
The Physics Society of IranIranian Journal of Physics Research1682-695724120240521Investigation of the Effect of Yttrium Doping on Oxygen Ion Diffusion in Zirconia using DFT Method for Enhancing SOFC Electrolyte DesignInvestigation of the Effect of Yttrium Doping on Oxygen Ion Diffusion in Zirconia using DFT Method for Enhancing SOFC Electrolyte Design5159348410.47176/ijpr.24.1.21803FAMohammadAli AhmadzadehDepartment of Materials Engineering, Isfahan University of Technology, Isfahan, IranMasoud PanjepourDepartment of Materials Engineering, Isfahan University of Technology, Isfahan, Iran0000-0002-5310-6891S. Javad HashemifarDepartment of Physics, Isfahan University of Technology, Isfahan, Iran0000-0002-2589-8772Journal Article20231216Solid Oxide Fuel Cells (SOFCs) have gained significant attention as a developing technology for clean and sustainable energy production. The electrolyte, a key component of SOFCs, is crucial in optimizing their performance. Enhancing oxygen ion conductivity in these electrolytes is essential for improving the efficiency and reducing the operating temperature of SOFCs. One effective approach is doping the electrolyte with impurity elements. Thus, the main objective of this research is to investigate the influence of yttrium doping on oxygen ion diffusion in zirconia, the most commonly used commercial electrolyte. Using Density Functional Theory (DFT) calculations, the effect of yttrium doping and its position on the activation energy was examined. The results indicate that yttrium, regardless of its doping position in zirconia, reduces the activation energy for oxygen ion diffusion. However, the position of the yttrium significantly affects the diffusion pathway, as oxygen prefers to diffuse through a path where the yttrium is absent. Furthermore, the results suggest that yttrium creates preferred oxygen vacancy sites within the structure.Solid Oxide Fuel Cells (SOFCs) have gained significant attention as a developing technology for clean and sustainable energy production. The electrolyte, a key component of SOFCs, is crucial in optimizing their performance. Enhancing oxygen ion conductivity in these electrolytes is essential for improving the efficiency and reducing the operating temperature of SOFCs. One effective approach is doping the electrolyte with impurity elements. Thus, the main objective of this research is to investigate the influence of yttrium doping on oxygen ion diffusion in zirconia, the most commonly used commercial electrolyte. Using Density Functional Theory (DFT) calculations, the effect of yttrium doping and its position on the activation energy was examined. The results indicate that yttrium, regardless of its doping position in zirconia, reduces the activation energy for oxygen ion diffusion. However, the position of the yttrium significantly affects the diffusion pathway, as oxygen prefers to diffuse through a path where the yttrium is absent. Furthermore, the results suggest that yttrium creates preferred oxygen vacancy sites within the structure.https://ijpr.iut.ac.ir/article_3484_450e48132bfe11e2e49f33c25e9a01a2.pdfIsfahan University of Technology,
The Physics Society of IranIranian Journal of Physics Research1682-695724120240521Using Bohmian trajectories in gravitational reduction of the wave functionUsing Bohmian trajectories in gravitational reduction of the wave function6173348510.47176/ijpr.24.1.11791FAFaramarz RahmaniDepartment of Physics, Faculty of Basic Sciences, Ayatollah Boroujerdi University, Boroujerd, Iran0009-0006-7599-585XMehdi SadeghiDepartment of Physics, Faculty of Basic Sciences, Ayatollah Boroujerdi University, Boroujerd, IranJournal Article20231120In this research, we study the gravitational reduction of the wave function, which has been investigated in standard quantum mechanics. As a new look at the problem, we investigate the reduction of the wave function by studying the dynamics of the particle motion, which can be defined in the quantum Bohmian framework. In this regard, quantities such as the critical mass of reduction, reduction time, and reduction temperature, which are similar to the Unruh temperature, are systematically obtained.In this research, we study the gravitational reduction of the wave function, which has been investigated in standard quantum mechanics. As a new look at the problem, we investigate the reduction of the wave function by studying the dynamics of the particle motion, which can be defined in the quantum Bohmian framework. In this regard, quantities such as the critical mass of reduction, reduction time, and reduction temperature, which are similar to the Unruh temperature, are systematically obtained.https://ijpr.iut.ac.ir/article_3485_b415de5b5d3448c56c2885cb6f788382.pdfIsfahan University of Technology,
The Physics Society of IranIranian Journal of Physics Research1682-695724120240521Fabrication of buckypapers using single-walled carbon nanotubes and investigation of its ability in water purificationFabrication of buckypapers using single-walled carbon nanotubes and investigation of its ability in water purification7581348610.47176/ijpr.24.1.81743FAMansoor FarbodPhysics Department Shahid Chamran University of Ahvaz, Ahvaz, Iran0000-0002-9774-705XSeyedeh Kosar EkraminasabPhysics Department Shahid Chamran University of Ahvaz, Ahvaz, IranAmeneh AhangarpourPhysics Department Shahid Chamran University of Ahvaz, Ahvaz, IranJournal Article20230829and deposited on a PTFE filter by vacuum filtration and then separated. The average pore size of the buckypapers produced by 30 and 50 mg of single-walled carbon nanotubes was 80 and 41 nm, respectively. The thermal conductivity of the produced buckypaper was 319.044 W/m.K, which is very close to the reported values. The electrical resistance of the samples increased with decreasing temperature, indicating a semiconductive behavior. To investigate the refining ability of the produced buckypapers, 100 ml of purified household water was passed through them by vacuum filtration and the water characteristics were measured before and after passing through the filters. The results showed that by increasing the thickness of the buckypapers, the hardness and conductivity of water decreased. So, for urban water samples, electrical conductivity and hardness decreased from 1709 µS/cm and 1706 mg/L, after passing through the 70 mg filter to 1592 µS/cm and 1582 mg/L, respectively. The experiments showed that the 50 and 70 mg buckypapers had a better performance than the PTFE filters.and deposited on a PTFE filter by vacuum filtration and then separated. The average pore size of the buckypapers produced by 30 and 50 mg of single-walled carbon nanotubes was 80 and 41 nm, respectively. The thermal conductivity of the produced buckypaper was 319.044 W/m.K, which is very close to the reported values. The electrical resistance of the samples increased with decreasing temperature, indicating a semiconductive behavior. To investigate the refining ability of the produced buckypapers, 100 ml of purified household water was passed through them by vacuum filtration and the water characteristics were measured before and after passing through the filters. The results showed that by increasing the thickness of the buckypapers, the hardness and conductivity of water decreased. So, for urban water samples, electrical conductivity and hardness decreased from 1709 µS/cm and 1706 mg/L, after passing through the 70 mg filter to 1592 µS/cm and 1582 mg/L, respectively. The experiments showed that the 50 and 70 mg buckypapers had a better performance than the PTFE filters.https://ijpr.iut.ac.ir/article_3486_39a57a163d878ff343678a401df3a651.pdfIsfahan University of Technology,
The Physics Society of IranIranian Journal of Physics Research1682-695724120240521Fabrication of zinc oxide and phosphorus optical thin films and comparison of their effect on silicon solar cell efficiencyFabrication of zinc oxide and phosphorus optical thin films and comparison of their effect on silicon solar cell efficiency8387348810.47176/ijpr.24.4.11795FASaeed SalehpourPhysics Department, Faculty of Basic Sciences, University of Mazandaran, Babolsar, IranJournal Article20231129In this study, we investigated the application of the photoluminescence of red phosphorus nanoparticles in increasing solar cell efficiency. Additionally, red phosphorus can also decrease surface reflection in silicon solar cells, thereby further increasing their efficiency. To demonstrate the impact of phosphorus's photoluminescence properties on cell efficiency, a layer of zinc oxide, known for its anti-reflective properties, is first deposited on the cell surface. By minimizing surface reflection and reducing the influence of phosphorus's anti-reflective effects on the efficiency, we can attribute any efficiency gains to the photoluminescence of red phosphorus. Initially, 50 nm zinc oxide was deposited on the silicon solar cell surface using the PVD method. Optical spectroscopy analysis showed that this layer effectively reduced surface reflection. However, subsequent measurement of the cell efficiency under standard AM1.5G radiation demonstrated a decrease in efficiency. Subsequently, 90 nm red phosphorus was deposited onto the zinc oxide layer using the PVD method. Optical spectroscopy results indicated that this new layer actually increased surface reflection. Remarkably, the efficiency measurement showed a significant relative increase of approximately 37%. This efficiency boost can be attributed to the photoluminescence properties of phosphorus nanoparticles, which absorb UV light and emit visible light, making it more efficiently absorbed by silicon solar cells.In this study, we investigated the application of the photoluminescence of red phosphorus nanoparticles in increasing solar cell efficiency. Additionally, red phosphorus can also decrease surface reflection in silicon solar cells, thereby further increasing their efficiency. To demonstrate the impact of phosphorus's photoluminescence properties on cell efficiency, a layer of zinc oxide, known for its anti-reflective properties, is first deposited on the cell surface. By minimizing surface reflection and reducing the influence of phosphorus's anti-reflective effects on the efficiency, we can attribute any efficiency gains to the photoluminescence of red phosphorus. Initially, 50 nm zinc oxide was deposited on the silicon solar cell surface using the PVD method. Optical spectroscopy analysis showed that this layer effectively reduced surface reflection. However, subsequent measurement of the cell efficiency under standard AM1.5G radiation demonstrated a decrease in efficiency. Subsequently, 90 nm red phosphorus was deposited onto the zinc oxide layer using the PVD method. Optical spectroscopy results indicated that this new layer actually increased surface reflection. Remarkably, the efficiency measurement showed a significant relative increase of approximately 37%. This efficiency boost can be attributed to the photoluminescence properties of phosphorus nanoparticles, which absorb UV light and emit visible light, making it more efficiently absorbed by silicon solar cells.https://ijpr.iut.ac.ir/article_3488_533532602ac7cca19a2ef6862184e37e.pdfIsfahan University of Technology,
The Physics Society of IranIranian Journal of Physics Research1682-695724120240521Investigating the dynamics of radio wave propagation in the plasma sheath around the hypersonic space vehicleInvestigating the dynamics of radio wave propagation in the plasma sheath around the hypersonic space vehicle8997348910.47176/ijpr.24.1.21796FASima AlilouPhysics Department, University of Tabriz, Tabriz, Iran0000-0001-5236-0153Laya ShahrassaiPhysics Department, University of Tabriz, Tabriz, Iran0000-0001-6395-6200Samad SobhanianPhysics Department, University of Tabriz, Tabriz, Iran0000-0002-2695-2400Journal Article20231207The radio blackout occurring in hypersonic spacecraft re-entry is a very fundamental problem, primarily because of the relatively long (several minutes) blackout period. In this research, the role of injected solid dielectric particulate into the plasma sheath formed around the spacecraft in mitigating the radio communication cut-off between the ground-based station and the space vehicle is studied analytically. Considering the propagation dynamics of radio waves in the dusty plasma formed by solid particle injection and using Fresnel’s formulae, the effect of dust particle number density and its dimension is investigated in the frequency range of 1-20GHz. In addition, the effect of the incident angle of the wave with the hypersonic shuttle nose surface has also been studied.The radio blackout occurring in hypersonic spacecraft re-entry is a very fundamental problem, primarily because of the relatively long (several minutes) blackout period. In this research, the role of injected solid dielectric particulate into the plasma sheath formed around the spacecraft in mitigating the radio communication cut-off between the ground-based station and the space vehicle is studied analytically. Considering the propagation dynamics of radio waves in the dusty plasma formed by solid particle injection and using Fresnel’s formulae, the effect of dust particle number density and its dimension is investigated in the frequency range of 1-20GHz. In addition, the effect of the incident angle of the wave with the hypersonic shuttle nose surface has also been studied.https://ijpr.iut.ac.ir/article_3489_e8802929a6f55893fe6b68d73f924f75.pdfIsfahan University of Technology,
The Physics Society of IranIranian Journal of Physics Research1682-695724120240521M-theory giant gravitons from the perspective of type IIA superstring theoryM-theory giant gravitons from the perspective of type IIA superstring theory97110349010.47176/ijpr.24.1.11819FAReza Abbaspour TamijaniPhysics Department, Faculty of Basic Sciences, Tarbiat Modares University, PO Box 14155-4838, Tehran, IranJournal Article20240109In this paper, we study the low-energy dynamics of the giant graviton of M-theory and its 10-dimensional interpretation in type IIA superstring theory. Considering a background geometry of the form <em>AdS<sub>7</sub> x S<sup>4</sup></em> in M-theory and assuming a giant graviton as a spherical M2-brane probe wrapping a 2-sphere and rotating along a great circle of S<sup>4</sup>, after compactifying the theory to 10 dimensions, we find that the giant is identical to a spherical D2-brane with a uniform <em>U</em>(1) magnetic flux on its worldvolume. Hence we find the relations between 11-dimensional quantities of a giant graviton and their 10-dimensional equivalents.In this paper, we study the low-energy dynamics of the giant graviton of M-theory and its 10-dimensional interpretation in type IIA superstring theory. Considering a background geometry of the form <em>AdS<sub>7</sub> x S<sup>4</sup></em> in M-theory and assuming a giant graviton as a spherical M2-brane probe wrapping a 2-sphere and rotating along a great circle of S<sup>4</sup>, after compactifying the theory to 10 dimensions, we find that the giant is identical to a spherical D2-brane with a uniform <em>U</em>(1) magnetic flux on its worldvolume. Hence we find the relations between 11-dimensional quantities of a giant graviton and their 10-dimensional equivalents.https://ijpr.iut.ac.ir/article_3490_4ce05a571ecb86c89a66737104054fce.pdfIsfahan University of Technology,
The Physics Society of IranIranian Journal of Physics Research1682-695724120240521Relativistic radiation transfer for plane–parallel flows with the radiative equilibriumRelativistic radiation transfer for plane–parallel flows with the radiative equilibrium111119349110.47176/ijpr.24.1.81738FAFahimeh HabibiDepartment of Physics, University of Birjand, Birjand, Iran0000-0001-7991-5964Journal Article20230815In this research, we investigate the relativistic radiative transfer in the atmosphere of a geometrically thin disc with finite optical depth. Using the plane-parallel approximation, we consider the flow one-dimensional and along the z-axis. Under the assumption of a constant flow speed and using a variable Eddington factor, we analytically solved the relativistic transfer equations in a moving frame for the case of radiative equilibrium and in the presence of an internal heating source. Then, the analytical solutions were obtained for the emergent intensity as well as other radiative quantities. Our results show that the flow speed and the total optical depth of this disc significantly affect the radiation quantities. We also demonstrate that different quantities of radiation are a function of optical depth. However, the combined effects of speed, internal heating and total optical depth of the disc may changed the type of this dependence.In this research, we investigate the relativistic radiative transfer in the atmosphere of a geometrically thin disc with finite optical depth. Using the plane-parallel approximation, we consider the flow one-dimensional and along the z-axis. Under the assumption of a constant flow speed and using a variable Eddington factor, we analytically solved the relativistic transfer equations in a moving frame for the case of radiative equilibrium and in the presence of an internal heating source. Then, the analytical solutions were obtained for the emergent intensity as well as other radiative quantities. Our results show that the flow speed and the total optical depth of this disc significantly affect the radiation quantities. We also demonstrate that different quantities of radiation are a function of optical depth. However, the combined effects of speed, internal heating and total optical depth of the disc may changed the type of this dependence.https://ijpr.iut.ac.ir/article_3491_2fad6af1eb89790b40e253554cefc09e.pdfIsfahan University of Technology,
The Physics Society of IranIranian Journal of Physics Research1682-695724120240521Generation of double attosecond pulses with the same intensity and carrier-envelope phaseGeneration of double attosecond pulses with the same intensity and carrier-envelope phase121130349210.47176/ijpr.24.1.01768FAAli NavidDepartment of laser and optical engineering, University of Bonab, Bonab, Iran0000-0003-1730-3342Reza AghbolaghiDepartment of laser and optical engineering, University of Bonab, Bonab, IranSoheila MajidiDepartment of laser and optical engineering, University of Bonab, Bonab, IranJournal Article20231022In this paper, we theoretically study the generation of double attosecond pulses with the same intensity, a similar carrier-envelope phase, and controllable duration with arbitrary time delay. The desired pulses are generated in a high harmonic generation process on the interaction of a pulsed femtosecond driver laser by asymmetric molecular ion HeH<sup>2+</sup>. High harmonic generation is investigated by numerical solving the one -dimensional- time dependent Schrödinger equation. To find out the optimized diving laser parameters an appropriate cost function is defined in genetic algorithm. The frequency spectrum of the desired pulses is selected from an appropiate part of high harmonics using a spectral filter. We show that the two mentioned pulses are generated at the time interval of one cycle of the laser electric field of the driving laser when the field direction is antiparallel to the molecule's permanent dipole moment. Finally, by calculating the characteristics of the generated pulses and comparing them with the desired ones, the efficiency of the presented method is fully confirmed.In this paper, we theoretically study the generation of double attosecond pulses with the same intensity, a similar carrier-envelope phase, and controllable duration with arbitrary time delay. The desired pulses are generated in a high harmonic generation process on the interaction of a pulsed femtosecond driver laser by asymmetric molecular ion HeH<sup>2+</sup>. High harmonic generation is investigated by numerical solving the one -dimensional- time dependent Schrödinger equation. To find out the optimized diving laser parameters an appropriate cost function is defined in genetic algorithm. The frequency spectrum of the desired pulses is selected from an appropiate part of high harmonics using a spectral filter. We show that the two mentioned pulses are generated at the time interval of one cycle of the laser electric field of the driving laser when the field direction is antiparallel to the molecule's permanent dipole moment. Finally, by calculating the characteristics of the generated pulses and comparing them with the desired ones, the efficiency of the presented method is fully confirmed.https://ijpr.iut.ac.ir/article_3492_f966d66cdd67f60582d5da0b5c94ff18.pdfIsfahan University of Technology,
The Physics Society of IranIranian Journal of Physics Research1682-695724120240521In-plane spin-polarized supercurrent on the topological Josephson junctionIn-plane spin-polarized supercurrent on the topological Josephson junction131140349310.47176/ijpr.20.4.21849FAMorteza SalehiPhysics Department, Bu-Ali Sina University0000-0001-6839-1990Journal Article20240215In this work, we consider a topological Josephson junction that contains conventional superconductors and ferromagnet leads on the surface of three-dimensional topological insulators. We use Bogoliubov-deGennes formalism to show in-plane magnetization with a component perpendicular to the superconductor interface that alters the Andreev bound states and creates an Andreev zone. This effect reduces the magnitude of the supercurrent. Also, magnetization changes the spin arrangement of surface states and creates spin-polarized supercurrent. Because of strong spin-momentum interaction on topological insulators, the spin-polarized supercurrent has in-plane components with maximum value in m_x~Δ_0⁄2. On the other hand, the parallel component of in-plane magnetization creates an anomalous supercurrent that flows in the absence of a superconducting phase difference. The dissipation-less spin-polarized supercurrent has great importance from the application point of view in designing spintronics devices.In this work, we consider a topological Josephson junction that contains conventional superconductors and ferromagnet leads on the surface of three-dimensional topological insulators. We use Bogoliubov-deGennes formalism to show in-plane magnetization with a component perpendicular to the superconductor interface that alters the Andreev bound states and creates an Andreev zone. This effect reduces the magnitude of the supercurrent. Also, magnetization changes the spin arrangement of surface states and creates spin-polarized supercurrent. Because of strong spin-momentum interaction on topological insulators, the spin-polarized supercurrent has in-plane components with maximum value in m_x~Δ_0⁄2. On the other hand, the parallel component of in-plane magnetization creates an anomalous supercurrent that flows in the absence of a superconducting phase difference. The dissipation-less spin-polarized supercurrent has great importance from the application point of view in designing spintronics devices.https://ijpr.iut.ac.ir/article_3493_60a32d910920ef9d19889a9c765cbfc6.pdf