VDM: A model for vector dark matter

, Article Journal of Cosmology and Astroparticle Physics ; Volume 2012, Issue 10 , 2012 ; 14757516 (ISSN) Farzan, Y ; 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 Farzan, Shahin (Author) ; 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 Farzan, Y ; 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) Farzan, Y ; 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 Esmaili Taklimi, Arman (Author) ; 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 Rezaie, Mehdi (Author) ; 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 Farzan Heydari, Mohammad (Author) ; 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...

Synthesis of TiO2 nano powder by the sol-gel method and its use as a photocatalyst

, Article Journal of the Iranian Chemical Society ; Volume 7, Issue SUPPL. 1 , 2010 , Pages S154-S160 ; 1735207X (ISSN) Karami, A ; Sharif University of Technology

2010

Abstract

In this work the titanium dioxide powder was prepared by the optimized and simple Sol-Gel method and then characterized. The gelling pH was set to values of 3 (TiO2-A), 7 (TiO2-N) and 9 (TiO2-B) to observe the effect on the properties of the material. In these three cases nanoparticulated materials were obtained with particle sizes between 10nm and 20nm. The larger surface areas were obtained at pH 3, which is several times larger than the others. Furthermore, with the gelling condition pH 3, it was possible to synthesize pure anatase phase titania. Some preliminary results on the test of the photocatalytic activity of the synthesized materials in the reduction of nitric oxide are presented....

Study on modification of colloidal silica surface with magnesium ions

, Article Journal of Colloid and Interface Science ; 2009 , Pages 379-383 ; 00219797 (ISSN) Karami, A ; Sharif University of Technology

2009

Abstract

The prepared colloidal silica via ion exchange was modified by adding Mg+2 ions in the surface growth process of colloidal silica. The particle size of the modified colloidal silica was decreased by increasing the seed concentration, whereas that of colloidal silica was slightly increased as the seeds concentration exceed 15 wt%. But the trend of changes in surface area was completely reversed. Magnesium ions on surface of the modified colloidal silica were identified by the measurement of energy-dispersive X-ray spectrometry (EDS). After modifying with Mg+2 ions, the iso-electric point (IEP) of colloidal silica in pH ∼ 2 without modification, disappears over the whole pH range. © 2008...

The influence of chromium substitution on an iron-titanium catalyst used in the selective catalytic reduction of NO

, Article Journal of Catalysis ; Volume 292 , August , 2012 , Pages 32-43 ; 00219517 (ISSN) Karami, A ; Salehi, V ; Sharif University of Technology

Elsevier 2012

Abstract

A series of Cr-substituted Fe-Ti compounds were prepared by the co-precipitation method and were systematically investigated as catalysts for the selective catalytic reduction (SCR) of NO by NH 3. A variety of analytical techniques revealed that the Cr substitution amount affects the N 2 selectivity, SCR activity, redox behavior of NH 3/NO x, adsorption ability, and structure of catalysts in terms of surface properties, porosity, mobility of lattice oxygen, oxidative ability of Cr species, ratio of Bronsted acid sites and Lewis acid sites, NO x adsorption capacity, and structural disorder and distortion. In a series of Fe aCr 1-aTiO x (a = 1, 0.75, 0.5, 0.2, 0) catalysts, Fe 0.5Cr 0.5TiO x...

Numerical modeling of incline plate LiBr absorber

, Article Heat and Mass Transfer/Waerme- und Stoffuebertragung ; Volume 47, Issue 3 , November , 2011 , Pages 259-267 ; 09477411 (ISSN) Karami, S ; Farhanieh, B ; Sharif University of Technology

2011

Abstract

Among major components of LiBr-H 2O absorption chillers is the absorber, which has a direct effect on the chillier size and whose characteristics have significant effects on the overall efficiency of absorption machines. In this article, heat and mass transfer process in absorption of refrigerant vapor into a lithium bromide solution of water-cooled incline plate absorber in the Reynolds number range of 5

A numerical study on the absorption of water vapor into a film of aqueous LiBr falling along a vertical plate

, Article Heat and Mass Transfer/Waerme- und Stoffuebertragung ; Volume 46, Issue 2 , 2009 , Pages 197-207 ; 09477411 (ISSN) Karami, S ; Farhanieh, B ; Sharif University of Technology

2009

Abstract

Absorber is an important component in absorption machines and its characteristics have significant effects on the overall efficiency of absorption machines. This article reports a model of simultaneous heat and mass transfer process in absorption of refrigerant vapor into a lithium bromide solution of water - cooled vertical plate absorber in the Reynolds number range of 5 < Re < 150. The boundary layer assumptions were used for the transport of mass, momentum and energy equations and the fully implicit finite difference method was employed to solve the governing equations in the film flow. Dependence of lithium bromide aqueous properties to the temperature and concentration and film...

Improvement of dry sliding tribological properties of polyamide 6 using diamond nanoparticles

, Article Tribology International ; Volume 115 , 2017 , Pages 370-377 ; 0301679X (ISSN) Karami, P ; Shojaei, A ; Sharif University of Technology

Elsevier Ltd 2017

Abstract

In the present study, it was revealed that incorporation of nanodiamond containing carboxylic group (ND-COOH) decreased considerably specific wear rate (∼30%) and COF (∼60%) of polyamide 6 (PA6) at 1 wt% loading. Compared with ND-COOH, amino functionalized ND enhanced further wear performance of PA6 which was associated with its finer dispersion as well as greater influence on the improvement of mechanical properties, toughness and crystallinity of PA6. Surface temperature increment caused by frictional heat was in close agreement with COF and wear characteristics of the samples. Optical microscopy images revealed that NDs promote the abrasive wear mechanism in PA6/ND composites. © 2017...

Morphological and mechanical properties of polyamide 6/nanodiamond composites prepared by melt mixing: effect of surface functionality of nanodiamond

, Article Polymer International ; Volume 66, Issue 4 , 2017 , Pages 557-565 ; 09598103 (ISSN) Karami, P ; Shojaei, A ; Sharif University of Technology

John Wiley and Sons Ltd 2017

Abstract

Surface chemistry of as-received nanodiamond (ND) was first tailored by dry thermal oxidation to obtain carboxylated ND (ND-COOH) and by wet chemistry to obtain ethylenediamine-functionalized ND (ND-EDA). Then, the surface-functionalized ND particles were dispersed in polyamide 6 (PA6) using the melt-mixing method. Transmission optical and scanning electron microscopies indicated a fine dispersion at low nanodiamond concentrations, e.g. 0.25 wt%, particularly with ND-EDA. Differential scanning calorimetry revealed that ND-EDA favoured the α-phase crystal and enhanced the degree of crystallinity of PA6. Experimental data indicated that ND-EDA had considerably improved tensile properties at...

Smooth residual generation for robust isolation of faults in manipulators using joint torque sensors

, Article 58th IEEE Conference on Decision and Control, CDC 2019, 11 December 2019 through 13 December 2019 ; Volume 2019-December , 2019 , Pages 2922-2927 ; 07431546 (ISSN); 9781728113982 (ISBN) Karami, S ; Namvar, M ; Sharif University of Technology

Institute of Electrical and Electronics Engineers Inc 2019

Abstract

Reliability of model-based failure detection and isolation (FDI) methods depends on the amount of uncertainty in a system model. Recently, it has been shown that the use of joint torque sensing results in a simplified manipulator model that excludes hardly identifiable link dynamics and other nonlinearities. We present a geometric approach to fault detection and isolation (FDI) for robotic manipulators using joint torque sensor in presence of model uncertainty. A systematic procedure is introduced for representing a robotic system model using joint torque sensor being affine with respect to faults and disturbances. The proposed FDI filter has smooth dynamics with freely selectable functions...

A geometric approach to fault detection and isolation in robotic manipulators

, Article Proceedings of the IEEE Conference on Decision and Control, 17 December 2018 through 19 December 2018 ; Volume 2018-December , 2019 , Pages 391-396 ; 07431546 (ISSN); 9781538613955 (ISBN) Karami, S ; Namvar, M ; Sharif University of Technology

Institute of Electrical and Electronics Engineers Inc 2019

Abstract

We present a geometric approach for fault detection and isolation (FDI) in robotic manipulators in presence of model uncertainty. A systematic procedure is introduced for representing robotic system model being affine with respect to faults and disturbances. The proposed residual generator has smooth dynamics with freely selectable functions and it does not require high gains or threshold adjustment for the FDI purpose. No assumption on amplitude of faults and their rate is used. The solvability conditions for the FDI problem lead to a quotient observable subspace unaffected by all unknown inputs except the faults. Simulation example demonstrates localization of faults in presence of...

Comparing the Besancon Galaxy Model with Hipparcos data

, M.Sc. Thesis Sharif University of Technology Karami, Mansour (Author) ; Rahvar, Sohrab (Supervisor)

Abstract

e H-R diagram for stars within 100 parsecs from the sun were simulated using Padova isorones, Besanc¸on Galaxy disc model and various star formation rates. using Chi-square test the different star formation rates were compared. the results favours an increasing star formation rate

Positioning, Tracking and Shape Control in Micro-Beams Via Electrostatic Actuators and Incomplete State Feedback

, M.Sc. Thesis Sharif University of Technology Karami, Farzad (Author) ; Salarieh, Hassan (Supervisor)

Abstract

Systems that are electrostatically actuated have found a vast role in MEMS application. This technology is used in optical systems, sensors, micro switches, and deformable mirrors. Raising the use of these systems in fields that needs better performance highlighted the need to accurate study of dynamics and control of electrostatic actuated systems in micro scale. This work is dedicated to design of an estimation and control system for a micro-beam that is actuated by electrostatic. After a comprehensive survey on pervious works that are done on dynamic, applications, fabrication and control of these systems dynamic of the system is fully derived. The environmental factors like fringing...

3D Reconstruction of Football Player Using Multi-view Videos

, M.Sc. Thesis Sharif University of Technology Karami, Mansoureh (Author) ; Kasaei, Shohreh (Supervisor)

Abstract

One major problem in sport match analysis and interpretation is that there are restricted viewpoints of the game. 3D reconstruction allows us to have virtual replay from any viewpoint so that the events such as penalties can be detected easily. For achieving this purpose, we use many cameras with overlapped views that cover almost all parts of the field. After some preprocessing, 3D reconstruction and texture mapping, we can enhance the viewer experience by having arbitrary viewpoint of the match. In this research, we use two different visual hull methods for 3D reconstruction. In the first method, the visual hull of an object is computed efficiently and robustly from image contours. This...

Designing a Multi-Model Sliding Mode Controller for a Magnetic Levitation System

, M.Sc. Thesis Sharif University of Technology Karami, Sasan (Author) ; Haeri, Mohammad (Supervisor)

Abstract

In this project a complete simulator for a two-winding, 25cm air gap Maglev system by considering the pratical constaritns, position and velocity observer and the current sensor dynamics was derived. In order to control the ball in any desired position a twisting sliding mode controller was designed as the basic controller in the rest of project. The designed controller can not transfer the ball in far trajectory. In first step we modify that to reach a better performance by changing the value of current, passing through the coils in steady state. In the second step, the far trajectories are divided to a finite number of sub-trajectory such that the ball can pass these sub-trajectory by...