ASP2024 alumni online presentations (2)
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Introduction and Welcome address
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Swampland conjectures for higher spin AdS3 gravity
We give Swampland constraints on the three dimensional Landscape of Anti-de Sitter higher spin gravity in the Chern-Simons formulation with connection valued in various split real forms of Lie algebras. We derive the finiteness conjecture by computing the upper bound on the rank of possible gauge groups then we refine it using the AdS distance conjecture. We discuss the implications of this Swampland constraint on the spectrum of higher spin gravity theories and we contrast it with the gravitational exclusion principle, required from BTZ black hole consideration, to excerpt a constraint on the Chern-Simons level k. The relevance and potential extensions of these results to 4D theories will be addressed as well.
Keywords: Swampland program, Quantum gravity, AdS3 Landscape, Higher spin gravity, BTZ black hole, AdS/CFT correspondence.
Speaker: Rajae Sammani -
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The effect of noncommutativity on the charged 4D-EGB black hole in AdS space–time
In this paper, we obtain a solution of a static spherically symmetric charged black hole inspired by noncommutative geometry in the context of the regularized 4D-Einstein–Gauss–Bonnet theory in AdS space. The derived metric recovers the standard solutions’ limits. It tends to the commutative case solution found in [P. G. S. Fernandes, Phys. Lett. B 805, 135468 (2020)] at large distance r+θ→∞ and the general relativity solution with smeared mass and charge as α→0. The charged solution obtained is singular at the origin in contrast to its neutral version, which is regular. The thermodynamic quantities have been modified due to the influence of noncommutativity. The heat capacity was used to investigate the local thermal stability. The black hole has been discovered to be locally stable for small and large radii, but unstable for middle radii.
Speaker: Hicham Lekbich (Moulay Ismail University) -
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Gravitational fine-grained entropy enhancements.
Entanglement entropy can be computed directly by describing the density matrix of the associated system. For gravitational systems such as black holes, the radiation entropy has a geometrical construction given by extremal surfaces. However, due to the quantum characteristics of black holes, this surface can be generalized to quantum extremal surfaces. We outline the derivation of gravitational fine-grained entropy using the quantum version of extreme surfaces. We provide evidence about a new method to compute von Neumann entropy.
Speaker: SAFAE TARIQ -
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Weak/strong gauge duality in M-Theory on K3xK3
Testing the Swampland conjectures in the context of string theory on Calabi-Yau threefolds has led to interesting results,both mathematically and physically. We generalize results of fibration structure of Calabi-Yau fourfold with finite volume in infinite distances in the moduli space. By applying these results to compactifications of M-theory on K3xK3 we relate weak coupling and strong coupling regimes to each other, which allows for non perturbative treatement of the three dimensional Effective field theory. This allows testing the Asymptotic Weak Gravity Conjecture in three dimensions.
Speaker: Mohammed CHARKAOUI (Faculté des sciences Université Mohammed V) -
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Study of a proposed new solar to electricity converter based on electron-photon interaction, a theoretical study
This work is a theoretical study of a proposed novel system whose purpose is to convert solar radiation to electrical energy. The study proposed an electron chamber with trapped electrons inside it. The trapped electrons were then excited by photons of specific frequency. The excited electrons were allowed to escape the chamber across a circular boundary to an evacuated coil-shaped path. The radius of the boundary was constrained to vary periodically with time. The movement of the electron within the system under the influence of light was modeled and the resultant equation simulated in MATLAB software with a test charged-particles with each particle having a radius of 2.38 𝜇𝑚 which was basically clumped-up electrons to form a test particle. The simulation results showed that the proposed system would generate D.C voltage and current with profile similar to that of D.C generator. The results further showed that resultant voltage was directly proportional to frequency and intensity of the photons. The results suggested that the proposed system had the potential of attaining efficiencies as high as 90% since it was not affected by the electron-hole recombination problem. The results also suggested that the efficiencies are strongly
dependent on the frequency of the incident photons, hence best suitable for space explorations.Speaker: Mr Steven Ochola (Maasai Mara University) -
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Investigating Gas Adsorption and Diffusion Dynamics in Zeolite-Based Membranes for Post-Combustion CO₂ Capture
Manda Timothy, Solomon Omwoma and Livingstone Ochilo
Jaramogi Oginga Odinga University of Science and Technology
Email: mandatimothy2016@gmail.com, tmanda98@yahoo.com
Abstract
One of the most important technologies for reducing greenhouse gas emissions is carbon capture and storage (CCS). CO2 is the main gas responsible for global warming. Post-combustion carbon capture is a popular method of carbon capture that is used in power plants and industrial processes to extract CO₂ from flue gases that are created during the combustion of fossil fuels. Conventional techniques, including chemical absorption using solvents like amines, are limited in their large-scale application due to issues with high energy consumption, solvent degradation, and high operating expenses. In order to get over these restrictions, this study investigates the use of zeolite-based membranes as a CO2 capture substitute, with an emphasis on enhancing the post-combustion capture process's effectiveness and financial sustainability.
Given their high surface area, adjustable pore sizes, and superior adsorption capabilities, zeolite-based membranes present a viable option that allows selective CO2 separation via molecular sieving and chemical interactions. The project intends to maximize selectivity and capture efficiency while reducing the energy penalty related to regeneration by integrating these membranes into the CO2 capture process. The process's economic viability is further enhanced by the membranes' capacity to regenerate themselves through changes in pressure or temperature, which guarantees their reuse without causing a large amount of material loss. This strategy increases the effectiveness of CO2 capture while simultaneously adhering to the principles of the circular economy by allowing the captured CO2 to be used in a variety of industrial processes, like enhanced oil recovery or the creation of synthetic fuel. The results of this study will address significant inefficiencies in the current approaches and progress efforts to reduce CO2 emissions by assisting in the development of more affordable and sustainable CCS systems.
Key words: post combustion, carbon capture, zeolite based membranesSpeaker: Timothy Manda -
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Analysis of Alpha and Lithium-7 Particle Energy Deposition in BNCT using Geant4 Simulation
This study investigates the microdosimetry of Boron Neutron Capture Therapy (BNCT) using high-fidelity Monte Carlo simulations to quantify the energy deposition distributions from alpha and lithium-7 particles in cellular structures.
We employ Geant4 to model various physics lists and water representations, aiming to optimize the accuracy of BNCT simulations. Dosimetry and microdosimetry studies using these Monte Carlo techniques examined the behavior of the produced alpha and lithium-7 particles and their energy deposition in different cellular compartments. Our findings contribute to the understanding of BNCT’s effects at the cellular level, which is crucial for advancing treatment planning and minimizing side effects.Speaker: Khadija CHAREF (HASSAN II University) -
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Physical properties of Gra-doped ZnFe2O4 thin films for solar cells application
The Zinc ferrite (ZnFe2O4) has significantly attracted many researchers due to their chemical and thermal stability [1] and their narrow band gap [2]. In this present research we successfully studied the influence of Graphene (Gra) doping on the physical properties of zinc ferrite thin films. The undoped and Gra-doped ZnFe2O4 nanofilms were grown onto glass substrates using spray pyrolysis technique at a substrate temperature of about 450°C. The elaboration process was followed by an annealing process in air at 500°C for 2 hours. We present in this investigation the effect of graphene on the structural (by XRD), optical (by Spectrophotometry), electrical (by I-V curves and Impedance spectroscopy) and morphological (by SEM and AFM) properties of ZnFe2O4. The X-ray diffraction results comfirmed that the prepared undoped and Gra-doped ZnFe2O4 had cubic spinel crystal structure with preferentiel orientations along the (311) plan. The Transmission increase from 71 to 81% with increasing the doping concentration. For the band gap, it decreases from 2.57 to 2.31 eV as the graphene cocentration is increased. The solar cell designed with the structure ZnO/ZnFe2O4/CIGS was optimased and tested using Silvaco software. The simulation proves that the graphene doped ZnFe2O4 used as buffer layer improve the efficiency of the solar cell.
The experimental results further revealed that Graphene doping had a considerable effect on the structural, electrical, optical and morphological properties of ZnFe2O4.Speaker: Fatma Ezzahra Dhif (Faculté des Sciences de Tunis) -
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COMPARATIVE STUDY OF INTERNAL DOSE CALCULATION: MONTE CARLO VERSUS MIRD METHOD
The Monte Carlo method and the method proposed by the Medical Internal Radiation Dose (MIRD) committee are among the most widely used methods for estimating absorbed dose in nuclear medicine. In fact, The MIRD committee is a committee of the Society of Nuclear Medicine, set up in 1965 to develop methods, models, assumptions and a standard mathematical scheme for assessing the internal radiation doses of administered radiopharmaceuticals.
The Monte Carlo method is very useful as it takes into account the complexity of to take into geometric models and the different radionuclide emissions.
In what follows, we compare the two, focusing on the calculation of absorbed doses to target organs.
Speaker: Fatima Zahra AHLAF -
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Modified Alfvén wave of multi-ion species in the upper ionosphere of Mars
Cold-modified Alfven waves of multi-ion species propagating perpendicular to an ambient magnetic field have been investigated. We derive the linear dispersion relation for any number of species. In addition to the conduction current density, we consider the displacement current density. The derived dispersion relation suggests a magnetized plasma mode to propagate at the long-wavelength for every ion species. At the short-wavelength, the propagating mode for every ion species saturates at a resonance frequency equal to the cyclotron frequency of that ion. The Alfven wave mode is shown to be the long-wavelength mode for the heaviest ion species, while the Whistler wave mode corresponds to the less massive ion species. It is found that the displacement current density excites another mode to exist in the electron fluid, which is known as the magnetized plasma analog of Langmuir mode. The consequences of varying the magnetic field, and the total plasma density and the mixing ratios of the ion species on the resonance, the cutoff frequencies, and the propagating modes are inspected. Investigation of this model on the observed linear ULF waves on the upper ionosphere of Mars is introduced.
Speaker: Ahmed Bakr (Egypt University of Informatics)
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