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Random Polytopes
, M.Sc. Thesis Sharif University of Technology ; Alishahi, Kasra (Supervisor)
Abstract
Random Polytopes, the first occurrence of which dates back to the famous Sylvester’s four points problem in the 1860s, is a branch of geometric probability, typically concerning the convex hull of some random points chosen from a convex subset of Rd. In this thesis we have studied some special kind of random polytopes; the one that is the convex hull of some independent random points chosen from a convex body (a convex, compact set with interior point) according to the uniform distribution. It was a new approach from A. Rényi and R. Sulanke in 1963 to consider this type when the number of random points tends to infinity.This thesis consists of three main parts: The first part is devoted to...
A low voltage, high speed current mode sample and hold for high precision applications
, Article 2005 European Conference on Circuit Theory and Design, Cork, 28 August 2005 through 2 September 2005 ; Volume 1 , 2005 , Pages 269-272 ; 0780390660 (ISBN); 9780780390669 (ISBN) ; Bakhtiar, M. S ; Sharif University of Technology
2005
Abstract
This paper presents a zero-voltage switching current mode sample and hold(S/H) circuit. The proposed S/H has 12 bit linearity at 180MHz sampling rate for 1.5v supply voltage. The S/H circuit is designed for 0.18μm CMOS technology
A high speed, high resolution, low voltage currentmode sample and hold
, Article IEEE International Symposium on Circuits and Systems 2005, ISCAS 2005, Kobe, 23 May 2005 through 26 May 2005 ; 2005 , Pages 1417-1420 ; 02714310 (ISSN) ; Bakhtiar, M. S ; Sharif University of Technology
2005
Abstract
A low voltage current mode sample and hold (S/H) in 0.18μm technology with 1.5v supply voltage is presented. This S/H has 12-bit linearity, i.e., gain and nonlinearity errors of S/H are less than 0.02μA for 100uA input current. Maximum sampling rate for this structure is 100 MHz (using double sampling technique). © 2005 IEEE
A Comparative Study between Available Lifting Tools for Assessment of Risk of Back Injuries
, M.Sc. Thesis Sharif University of Technology ; Arjmand, Navid (Supervisor)
Abstract
Epidemiological studies have identified manual material handling and lifting as risk factors in occupational low back pain (LBP). There are many lifting analysis tools to estimate the risk of injury during a specific lifting task. One for using these tools, needs to know the limitations of each tool and be noticed where a tool cannot be used. The purpose of this study is to compare different biomechanical models of lumbar spine and find out their characteristics.Five models are chosen for this study which are: the University of Michigan’s Static Strength Prediction Program ( ) software, the revised Hand-Calculation Back Compressive Force (HCBCF) equation, the simple polynomial equation of...
Protection of the Topological Edge Quantum Order in A Spin Chain with Cluster Interactions and Coupled to Fermions
, M.Sc. Thesis Sharif University of Technology ; Langari, Abdollah (Supervisor)
Abstract
Out-of-equilibrium systems have garnered increasing interest in recent years. These many-body systems do not exhibit ergodic behavior, even in the presence of generic interactions, allowing locally stored quantum information to remain accessible for extended periods through local observables. Due to these exotic characteristics, such systems are ideal candidates for the realization of quantum computing. Many-body localized systems serve as a prime example of these non-ergodic systems. In the absence of thermalization, long-range quantum order can persist even in highly excited states, contrasting with thermal systems where long-range order can only exist in the ground state of gapped...
Emergent statistical bubble localization in a Z2 lattice gauge theory
, Article Physical Review B ; Volume 99, Issue 5 , 2019 ; 24699950 (ISSN) ; Mohseni Rajaee, M ; Langari, A ; Sharif University of Technology
American Physical Society
2019
Abstract
We introduce a clean cluster spin chain coupled to fully interacting spinless fermions, forming an unconstrained Z2 lattice gauge theory (LGT), which possesses dynamical proximity effect controlled by the entanglement structure of the initial state. We expand the machinery of interaction-driven localization to the realm of LGTs such that for any starting product state, the matter fields exhibit emergent statistical bubble localization, which is driven solely by the cluster interaction, having no topologically trivial noninteracting counterpart, and thus is of a pure dynamical many-body effect. In this vein, our proposed setting provides possibly the minimal model dropping all the...
A low voltage, high speed, high resolution class AB switched current sample and hold
, Article ISCAS 2006: 2006 IEEE International Symposium on Circuits and Systems, Kos, 21 May 2006 through 24 May 2006 ; 2006 , Pages 1039-1042 ; 02714310 (ISSN); 0780393902 (ISBN); 9780780393905 (ISBN) ; Jahanian, A ; Sharif Bakhtiar, M ; Sharif University of Technology
2006
Abstract
A high speed, high resolution switched-current sample and hold (SI S/H) based on a new class AB transconductance stage is presented. Simulations performed on the SI S/H in standard 0.18um CMOS technology with 1.5v supply voltage indicate low power dissipation, high sampling speed and high SNR. © 2006 IEEE
A novel coupled musculoskeletal finite element model of the spine – Critical evaluation of trunk models in some tasks
, Article Journal of Biomechanics ; Volume 119 , 2021 ; 00219290 (ISSN) ; Arjmand, N ; Shirazi Adl, A ; Sharif University of Technology
Elsevier Ltd
2021
Abstract
Spine musculoskeletal (MS) models make simplifying assumptions on the intervertebral joint degrees-of-freedom (rotational and/or translational), representation (spherical or beam-like joints), and properties (linear or nonlinear). They also generally neglect the realistic structure of the joints with disc nuclei/annuli, facets, and ligaments. We aim to develop a novel MS model where trunk muscles are incorporated into a detailed finite element (FE) model of the ligamentous T12-S1 spine thus constructing a gold standard coupled MS-FE model. Model predictions are compared under some tasks with those of our earlier spherical joints, beam joints, and hybrid (uncoupled) MS-FE models. The coupled...
Seismic Rehabilitation of Reinforced Concrete Structures Using Eccentric Steel Bracing
, M.Sc. Thesis Sharif University of Technology ; Kazemi, Mohammad Taghi (Supervisor)
Abstract
The seismic performance of a low-rise nonductile reinforced concrete (RC) building rehabilitated using eccentric steel bracing is investigated. At first three-story building was Modeled using sap 2000 computer program then analyzed and getting the results. The effectiveness of the eccentric steel bracing in rehabilitating the building was examined. The effect of distributing the steel bracing over the height of the RC frame on the seismic performance of the rehabilitated building was studied. The behavior of the nonductile RC frame members is represented by a beam–column element capable of modeling the strength deterioration and the effect of the axial force on the yield moment and the...
Meson Thermalizationin AdS/CFT Correspondence
, M.Sc. Thesis Sharif University of Technology ; Arfaie, Hesameddin (Supervisor) ; Ali-Akbari, Mohammad (Supervisor)
Abstract
AdS/CFT correspondence is a suitable framework for studying strongly coupled gauge theories. It corresponds a strongly coupled gauge theory to a classical gravity theory with an extra dimension. Quark-gluon plasma which is produced in accelerators is strongly coupled. We use AdS/CFT correspondence to calculate Meson thermalization time by approximating the collisions by a sudden change of baryon number chemical potential. On the gravity side, this is followed with an apparent horizon formation on probe-brane which is the signal of thermalization
P2P D DoS Detection
, M.Sc. Thesis Sharif University of Technology ; Khansari, Mohammad (Supervisor) ; Akbari, Behzad (Co-Advisor)
Abstract
attacks have become such a serious problem that according to the recent security firms’ reports, more than five thousands attacks are launched per day, whichcould lead to lots of damage and loss of online businesses. When a P2P system has millions of concurrently active peers, there is the risk that an attacker misuses these clients, or diverts their generated traffic to launch DDoS attack.As we will see, since BitTorrent has gained more popularity among other P2P protocols,and ithas the most number of concurrent active users,it may lead to destructivedamagesif exploited by attackers for lunching DDoS attack. Thus, we have focused on DDoS detection over this protocol.In this study, first,we...
Comparative evaluation of six quantitative lifting tools to estimate spine loads during static activities
, Article Applied Ergonomics ; Volume 48 , 2015 , Pages 22-32 ; 00036870 (ISSN) ; Arjmand, N ; Shirazi Adl, A ; Plamondon, A ; Schmidt, H ; Sharif University of Technology
Elsevier Ltd
2015
Abstract
Different lifting analysis tools are commonly used to assess spinal loads and risk of injury. Distinct musculoskeletal models with various degrees of accuracy are employed in these tools affecting thus their relative accuracy in practical applications. The present study aims to compare predictions of six tools (HCBCF, LSBM, 3DSSPP, AnyBody, simple polynomial, and regression models) for the L4-L5 and L5-S1 compression and shear loads in twenty-six static activities with and without hand load. Significantly different spinal loads but relatively similar patterns for the compression (R2>0.87) were computed. Regression models and AnyBody predicted intradiscal pressures in closer agreement with...
Experimental study on enhanced oil recovery by low salinity water flooding on the fractured dolomite reservoir
, Article Iranian Journal of Chemistry and Chemical Engineering ; Volume 40, Issue 5 , 2021 , Pages 1703-1719 ; 10219986 (ISSN) ; Gerami, S ; Safekordi, A. A ; Bahramian, A. R ; Ganjeh Ghazvini, M ; Sharif University of Technology
Iranian Institute of Research and Development in Chemical Industries
2021
Abstract
Enhanced Oil Recovery from carbonate reservoirs is a major challenge especially in naturally fractured formations where spontaneous imbibition is a main driving force. The Low Salinity Water Injection (LSWI) method has been suggested as one of the promising methods for enhanced oil recovery. However, the literature suggests that LSWI method, due to high dependence on rock mineralogy, injected and formation water salt concentration, and complexity of reactions is not a well-established technology in oil recovery from carbonate reservoirs. The underlying mechanism of LSWI is still not fully understood. Due to lack of LSWI study in free clay dolomite fractured reservoir, and to investigate of...