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VDM: A model for vector dark matter
, Article Journal of Cosmology and Astroparticle Physics ; Volume 2012, Issue 10 , 2012 ; 14757516 (ISSN) ; Rezaeiakbarieh, A ; Sharif University of Technology
IOP
2012
Abstract
We construct a model based on a new U(1) X gauge symmetry and a discrete Z 2 symmetry under which the new gauge boson is odd. The model contains new complex scalars which carry U(1) X charge but are singlets of the Standard Model. The U(1) X symmetry is spontaneously broken but the Z 2 symmetry is maintained, making the new gauge boson a dark matter candidate. In the minimal version there is only one complex scalar field but by extending the number of scalars to two, the model will enjoy rich phenomenology which comes in various phases. In one phase, CP is spontaneously broken. In the other phase, an accidental Z 2 symmetry appears which makes one of the scalars stable and therefore a dark...
Numerical Investigation of Various Parameters Influence in Atrium Efficiency Improvements for Building’s Natural Ventilation
, M.Sc. Thesis Sharif University of Technology ; Moosavi, Ali (Supervisor)
Abstract
In order to improve the efficiency of atriums, effective parameters in ventilation and acceleration of airflow are numerous. Nevertheless, parameters such as shape and height of atrium, geometry of the inlet and outlets, opening areas and the presence of heat sources in each store play a vital role. In structures higher than one floor, there is no significant airflow in the upper floors and the ventilation of atrium is unpleasant for residents. Air movement in the building is done by buoyancy-driven force and hot air upward movement due to pressure differences.This study attempts to improve the natural ventilation performance with changing mentioned parameters. So for this purpose, 3D...
Decaying vector dark matter as an explanation for the 3.5 keV line from galaxy clusters
, Article Journal of Cosmology and Astroparticle Physics ; Vol. 2014, issue. 11 , 2014 ; ISSN: 14757516 ; Akbarieh, A. R ; Sharif University of Technology
2014
Abstract
We present a Vector Dark Matter (VDM) model that explains the 3.5 keV line recently observed in the XMM-Newton observatory data from galaxy clusters. In this model, dark matter is composed of two vector bosons, V and V', which couple to the photon through an effective generalized Chern-Simons coupling, gV. V' is slightly heavier than V with a mass splitting mV' - mV 3.5 keV. The decay of V' to V and a photon gives rise to the 3.5 keV line. The production of V and V' takes place in the early universe within the freeze-in framework through the effective gV coupling when mV' < T < Λ, Λ being the cut-off above which the effective gV coupling is not valid. We introduce a high energy model that...
Natural explanation for 130 GeV photon line within vector boson dark matter model
, Article Physics Letters, Section B: Nuclear, Elementary Particle and High-Energy Physics ; Volume 724, Issue 1-3 , 2013 , Pages 84-87 ; 03702693 (ISSN) ; Akbarieh, A. R ; Sharif University of Technology
2013
Abstract
We present a dark matter model for explaining the observed 130 GeV photon line from the galaxy center. The dark matter candidate is a vector boson of mass mV with a dimensionless coupling to the photon and Z boson. The model predicts a double line photon spectrum at energies equal to mV and mV(1-mZ2/4mV2) originating from the dark matter annihilation. The same coupling leads to a mono-photon plus missing energy signal at the LHC. The entire perturbative parameter space can be probed by the 14 TeV LHC run. The model has also a good prospect of being probed by direct dark matter searches as well as the measurement of the rates of h→γγ and h→Zγ at the LHC
Cosmic Neutrinos at Neutrino Telescopes CP-violation, Source Properties and Beyond the Standard Model Physics
, Ph.D. Dissertation Sharif University of Technology ; Farzan, Yasaman (Supervisor)
Abstract
In this thesis, we studied the oscillation of neutrino flavors and the measurement of mixing parameters through the detection of cosmic neutrinos at neutrino telescopes. Most of the astrophysical explosions predict the emission of neutrino flux and kilometer-scale detectors are under construction for the observation of these neutrinos. Detection of astrophysical neutrinos opens a new window to understand the neutrino properties and also the properties of astrophysical sources.In this thesis first we review the phenomenology of neutrino flavor oscillation and characteristics of neutrino mass matrix. By introducing a new class of invariants (under general transformation of lepton fields bases)...
Particles in the early Universe: Interface of Cosmology and Particles Massive Neutrinos and Cosmology
, M.Sc. Thesis Sharif University of Technology ; Golshani, Mehdi (Supervisor) ; Farzan, Yasaman (Supervisor)
Abstract
Neutrino flavor oscillations are clear evidence of massive neutrinos. It has been for more than a decade that neutrino physics became one of active topics in the field of particle physics and various experiments started studying the flavor oscillation of neutrinos. Unfortunately, experiments studying the flavor oscillations are only sensitive to the mass square difference, and they are incapable of providing more information about the absolute mass scale of neutrinos. Additionally, sterile neutrinos having non-standard interactions are under vast investigations and studies. Determination of neutrino masses and their effective number is among the most challenging problems by which...
Efficient Multicasting in Cognitive Wireless Sensor Networks
, M.Sc. Thesis Sharif University of Technology ; Movaghar Rahimabadi, Ali (Supervisor)
Abstract
Today with growth of wireless communications and progress of small and cheap sensors which have capability of communication and calculation, wireless sensor networks are important and useful topic. But due to energy restrictions, efficient use of resources and increasing network lifetime, have been considered as key factors in network design. In this regard, using efficient multicast routing in energy consumption, for an efficient data transmission to specific number of nodes instead of all nodes code updates, information requests, task assignments and etc., is necessary.On the other hand these networks use unlicensed spectrum and suffer from collision due to congestion caused by other...
Multiclass fuzzy user equilibrium with endogenous membership functions and risk-taking behaviors
, Article Journal of Advanced Transportation ; 2016 ; 01976729 (ISSN) ; Lou, Y ; Hsu, Y. T ; Shabanpour, R ; Shafahi, Y ; Sharif University of Technology
John Wiley and Sons Ltd
2016
Abstract
Over the last decades, several approaches have been proposed in the literature to incorporate users' perceptions of travel costs, their bounded rationality, and risk-taking behaviors into network equilibrium modeling for traffic assignment problem. While theoretically advanced, these models often suffer from high complexity and computational cost and often involve parameters that are difficult to estimate. This study proposes an alternative approach where users' imprecise perceptions of travel times are endogenously constructed as fuzzy sets based on the probability distributions of random link travel times. Two decision rules are proposed accordingly to account for users' heterogeneous...
Ultrafine Co nanoislands grafted on tailored interpenetrating N-doped carbon nanoleaves: An efficient bifunctional electrocatalyst for rechargeable Zn-air batteries
, Article Chemical Engineering Journal ; Volume 431 , 2022 ; 13858947 (ISSN) ; Chen, L ; Yang, H ; Zhang, Y ; Peng, Y ; Luo, X ; Ahmad, A ; Ramzan, N ; Xu, Y ; Shi, Y ; Sharif University of Technology
Elsevier B.V
2022
Abstract
Zeolitic imidazole frameworks (ZIFs) provide an exciting platform to design and fabricate non-precious-metal carbon-based catalysts for oxygen reduction/evolution reaction (ORR/OER). Herein, we elaborately design a facile enzyme-assisted synthetic strategy that enables to tailor the ZIFs precursors into structural stable decussation shape, which derived Co nanoislands grafted on decussate N-doped carbon nanoleaves (D-Co@NC) can well retain the interpenetrating nanostructure. Benefiting from the combined advantages of compositions and interpenetrating nanostructures, D-Co@NC possesses 5.2 times higher exposed electrochemical active area than the conventional dodecahedral one, thus endowing...
Interaction of glazing parameters, climatic condition and interior shadings: performing energy and cost analysis in a residential building in Iran
, Article Energy Efficiency ; Volume 13, Issue 1 , 21 December , 2020 , Pages 159-176 ; Gholipour, Y ; Saboohi, Y ; Yan, W ; Sharif University of Technology
Springer
2020
Abstract
In this paper, the interaction between various window specifications and different climate conditions is investigated. For this purpose, simultaneous effects of several aspects including glazing system, glass type, filling gas, glass thickness, window frame fraction, and interior shading are considered under three different climatic conditions. To evaluate the energy performance of various considered alternatives, the energy simulation of a base case building is evaluated in a computer environment. Using the validated model, the energy analysis is quantitatively performed, and cost-benefit analyses from the viewpoints of both residents and government are carried out based on the domestic and...
Synthesis of substituted 2,2′ and 4,4′-bithiazoles in various solvents
, Article Indian Journal of Chemistry - Section B Organic and Medicinal Chemistry ; Volume 40, Issue 6 , 2001 , Pages 498-499 ; 03764699 (ISSN) ; Beni, Y. A
2001
Abstract
Some tetra substituted derivatives of 2,2′ and 4,4′ bithiazoles have been synthesized and characterized in various solvents
Mathematical modeling of the reaction in an iron ore pellet using a mixture of hydrogen, water vapor, carbon monoxide and carbon dioxide: An isothermal study
, Article Advanced Powder Technology ; Volume 17, Issue 3 , 2006 , Pages 277-295 ; 09218831 (ISSN) ; Motamed Hashemi, M. Y ; Saboohi, Y ; Sharif University of Technology
VSP BV
2006
Abstract
A mathematical time-dependent and isothermal model based on the grain model has been developed to simulate the kinetic and thermal behaviors of a porous iron oxide pellet undergoing chemical reactions with a mixture of hydrogen, carbon monoxide, carbon dioxide and water vapor. Its novelty consists in fact that it can deal with a multi-species reducing gas and oxide pellet. In spite of previous models in which the pure reductant was applied as reducing gas, this model can indicate an actual view of pellet reduction including the effects of reducing gas utility and reducing gas ratio. A finite volume fully implicit technique was applied for solving the governing equations. The model has been...
A thermodynamically consistent electro-chemo-mechanical theory for modeling axonal swelling
, Article Journal of the Mechanics and Physics of Solids ; Volume 145 , 2020 ; Naghdabadi, R ; Sohrabpour, S ; Li, Y ; Hu, Y ; Sharif University of Technology
Elsevier Ltd
2020
Abstract
In the present study, for the first time, a thermodynamically consistent large deformation theory is developed to model the multi physics problem of axonal swelling which is the hallmark of most of the brain diseases. To this end, the relevant axonal compartments are first explained and the corresponding model parts are introduced. Next, the problem is formulated as an open thermodynamic system and the corresponding constitutive and evolution equations are extracted utilizing the balance laws. Here, a multiplicative decomposition of the deformation gradient is used to capture the active behavior of the axonal actin cortex. Specific free energy functions are given for the model parts to...
Probabilistic data-driven framework for performance assessment of retaining walls against rockfalls
, Article Probabilistic Engineering Mechanics ; Volume 70 , 2022 ; 02668920 (ISSN) ; Mahsuli, M ; Zhang, Y ; Xue, Y ; Huang, H ; Sharif University of Technology
Elsevier Ltd
2022
Abstract
Rockfall is a significant hazard to sites that are located at the foot of rock slopes. In such sites, there is a notable need to evaluate the potential for rockfall, estimate the extent of areas at risk, and design retaining structures to reduce the risk of rockfall-induced. This paper presents a probabilistic framework for predicting the formation and progression of rockfalls and for evaluating the performance of retaining walls under rockfalls. To this end, first a probabilistic model for the rock projectile motion on a slope is presented. The model accounts for prevailing uncertainties, i.e., the trigger points, rock shape, projectile path, and slope material properties, which include...
Inflationary power asymmetry from primordial domain walls
, Article Journal of Cosmology and Astroparticle Physics ; Vol. 2014, issue. 11 , 2014 ; ISSN: 14757516 ; Akrami, Y ; Firouzjahi, H ; Solomon, A. R ; Wang, Y ; Sharif University of Technology
2014
Abstract
We study the asymmetric primordial fluctuations in a model of inflation in which translational invariance is broken by a domain wall. We calculate the corrections to the power spectrum of curvature perturbations; they are anisotropic and contain dipole, quadrupole, and higher multipoles with non-trivial scale-dependent amplitudes. Inspired by observations of these multipole asymmetries in terms of two-point correlations and variance in real space, we demonstrate that this model can explain the observed anomalous power asymmetry of the cosmic microwave background (CMB) sky, including its characteristic feature that the dipole dominates over higher multipoles. We test the viability of the...
Modeling and design of an oscillatory current-sharing control strategy in dc microgrids
, Article IEEE Transactions on Industrial Electronics ; Volume 62, Issue 11 , May , 2015 , Pages 6647-6657 ; 02780046 (ISSN) ; Ghazanfari, A ; Mohamed, Y. A. R. I ; Karimi, Y ; Sharif University of Technology
Institute of Electrical and Electronics Engineers Inc
2015
Abstract
This paper presents an effective control scheme in dc microgrids to precisely share the load current oscillatory and dc components among distributed generation (DG) units. The proposed control strategy includes current and voltage control blocks. The current control block consists of oscillatory and dc current-sharing units. The main idea of the proposed method is to share the load current oscillatory and dc components among the DG units based on their rated power, by assigning appropriate output impedance values and droop coefficients to each DG unit. The voltage control block is a multiloop voltage control unit employed to control the microgrid voltage. The detailed model of the proposed...
Effect of starting materials on the wear performance of NiTi-based composites
, Article Wear ; Volume 334-335 , July , 2015 , Pages 35-43 ; 00431648 (ISSN) ; Ebadzadeh, T ; Vaezi, M. R ; Yoon, E. Y ; Kim, Y. J ; Kang, J. Y ; Kim, H. S ; Simchi, A ; Sharif University of Technology
Elsevier Ltd
2015
Abstract
NiTi alloys have exhibited significant potential as a matrix of wear resistant composites. In this study, in order to examine the effect of starting materials on the wear performance of NiTi-based composites, both elemental Ni/Ti and prealloyed NiTi powders were used to fabricate NiTi-6wt% nano-Al2 O3 composites using hot isostatic pressing (HIP). Nanoindentation and microhardness test results indicate that the composite samples produced from the elemental Ni/Ti powders exhibited higher hardness and lower pseudoelasticity properties than those of the samples fabricated from the prealloyed NiTi powders; this is attributed to the higher amount of...
Distributed user association and femtocell allocation in heterogeneous wireless networks
, Article IEEE Transactions on Communications ; Vol. 62, issue. 8 , 2014 , p. 3027-3043 ; Louie, R. H. Y ; Han, Z ; Vucetic, B ; Li, Y ; Sharif University of Technology
2014
Abstract
Deployment of low-power low-cost small access points such as femtocell access points (FAPs) constitute an attractive solution for improving the existing macrocell access points' (MAPs) capacity, reliability, and coverage. However, FAP deployment faces challenging problems such as interference management and the lack of flexible frameworks for deploying the FAPs by the service providers (SPs). In this paper, we propose a novel solution that jointly associates the user equipment (UE) to the APs, and allocates the FAPs to the SPs such that the the total satisfaction of the UEs in an uplink OFDMA network is maximized. We model the competitive behaviors among the UEs, FAPs, and SPs as a dynamic...
Trichloroethylene degradation by PVA-coated calcium peroxide nanoparticles in Fe(II)-based catalytic systems: enhanced performance by citric acid and nanoscale iron sulfide
, Article Environmental Science and Pollution Research ; Volume 28, Issue 3 , 2021 , Pages 3121-3135 ; 09441344 (ISSN) ; Shan, A ; Sun, Y ; Gu, X ; Lyu, S ; Zhou, Y ; Sharif University of Technology
Springer Science and Business Media Deutschland GmbH
2021
Abstract
In this study, the enhanced trichloroethylene (TCE) degradation performance was investigated by polyvinyl alcohol coated calcium peroxide nanoparticles (PVA@nCP) as an oxidant in Fe(II)-based catalytic systems. The nanoscale iron sulfide (nFeS), having an average particle size of 115.4 nm, was synthesized in the laboratory and characterized by SEM, TEM, HR-TEM along with EDS elemental mapping, XRD, FTIR, ICP-OES, and XPS techniques. In only ferrous iron catalyzed system (PVA@nCP/Fe(II)), TCE degradation was recorded at 58.9% in 6 h. In comparison, this value was increased to 97.5% or 99.7% with the addition of citric acid (CA) or nFeS in PVA@nCP/Fe(II) system, respectively. A comparative...
Trichloroethylene degradation by PVA-coated calcium peroxide nanoparticles in Fe(II)-based catalytic systems: enhanced performance by citric acid and nanoscale iron sulfide
, Article Environmental Science and Pollution Research ; Volume 28, Issue 3 , 2021 , Pages 3121-3135 ; 09441344 (ISSN) ; Shan, A ; Sun, Y ; Gu, X ; Lyu, S ; Zhou, Y ; Sharif University of Technology
Springer Science and Business Media Deutschland GmbH
2021
Abstract
In this study, the enhanced trichloroethylene (TCE) degradation performance was investigated by polyvinyl alcohol coated calcium peroxide nanoparticles (PVA@nCP) as an oxidant in Fe(II)-based catalytic systems. The nanoscale iron sulfide (nFeS), having an average particle size of 115.4 nm, was synthesized in the laboratory and characterized by SEM, TEM, HR-TEM along with EDS elemental mapping, XRD, FTIR, ICP-OES, and XPS techniques. In only ferrous iron catalyzed system (PVA@nCP/Fe(II)), TCE degradation was recorded at 58.9% in 6 h. In comparison, this value was increased to 97.5% or 99.7% with the addition of citric acid (CA) or nFeS in PVA@nCP/Fe(II) system, respectively. A comparative...