The Effect of Collateral Value on Investment: A Case Study of Iranian Industrial Plants

, M.Sc. Thesis Sharif University of Technology Nikpour, Ali (Author) ; Mahmoudzadeh, Amineh (Supervisor) ; Madanizadeh, Ali (Supervisor)

Abstract

This study investigates the collateral channel in the Iranian economy and presents key findings regarding the impact of collateral values on firms’ investment behavior. Introducing a novel measure of financial constraints, the research employs this variable to strengthen the empirical identification of the collateral channel. The results provide clear evidence for the existence of a collateral channel in Iran, particularly in investments related to construction and land acquisition. Firms facing tighter financial constraints exhibit a stronger propensity to invest in these areas when the value of real estate collateral increases. These findings support the presence of the collateral channel...

Distributed Denial of-Service (DDoS)Attack Detection in SDN-based Cloud

, M.Sc. Thesis Sharif University of Technology Nikpour, Amir (Author) ; Jalili, Rasool (Supervisor)

Abstract

SDN-based cloud is created by new thechnologies. This infrastructure is more programmable, manageable and configurable. However SDN-based cloud is vulnerable to the DDoS attacks. A lot of researches has been accomplished to prevent these kind of attacks. Solutions that proposed in these papers are based on machine learning, statistical analysis of traffic or combination of these approaches. In this research an efficient method has been introduced, for detecting DDOS attack in SDN-based cloud environment. Detection system is based on extreme learning machine (ELM). ELMs has been pruned with genetic algorithm (GAP-ELM). Detection of attack in the proposed system, has been accomplished with...

Adaptive online prediction of operator position in teleoperation with unknown time-varying delay: simulation and experiments

, Article Neural Computing and Applications ; 2020 Nikpour, M ; Yazdankhoo, B ; Beigzadeh, B ; Meghdari, A ; Sharif University of Technology

Springer Science and Business Media Deutschland GmbH 2020

Abstract

One of the most important problems in teleoperation systems is time delay and packet loss in the communication channel, which can affect transparency and stability. One way to overcome the time delay effects in a teleoperation system is to predict the master-side motion. In this way, when data is received in the slave side, it will be considered as the current position of the master robot and, thus, complete transparency could be achieved. The majority of the previous works regarding operator position prediction have considered known and constant time delay in the system; however, in the real applications, time delay is unknown and variable. In this paper, an adaptive online prediction...

Adaptive online prediction of operator position in teleoperation with unknown time-varying delay: simulation and experiments

, Article Neural Computing and Applications ; Volume 33, Issue 13 , 2021 , Pages 7575-7592 ; 09410643 (ISSN) Nikpour, M ; Yazdankhoo, B ; Beigzadeh, B ; Meghdari, A ; Sharif University of Technology

Springer Science and Business Media Deutschland GmbH 2021

Abstract

One of the most important problems in teleoperation systems is time delay and packet loss in the communication channel, which can affect transparency and stability. One way to overcome the time delay effects in a teleoperation system is to predict the master-side motion. In this way, when data is received in the slave side, it will be considered as the current position of the master robot and, thus, complete transparency could be achieved. The majority of the previous works regarding operator position prediction have considered known and constant time delay in the system; however, in the real applications, time delay is unknown and variable. In this paper, an adaptive online prediction...

Effect of Translational Degrees of Freedom of Intervertebral Joints on Prediction of Spinal Load and Muscle Forces in AnyBody Modeling System

, M.Sc. Thesis Sharif University of Technology Nikpour, Hassan (Author) ; Arjmand, Navid (Supervisor) ; Parnianpour, Mohammad (Co-Advisor)

Abstract

Biomechanical models are indispensable tools in predictions of muscle forces and joint loads towards design of prevention and treatment programs. In most of these models intervertebral joints are modeled as hinge joints thus neglecting the existing translational degrees of freedom (DOFs). This simplification can alter the results of the model as changes in model kinematics affect the prediction of the joint and muscle forces. The current study aims to evaluate the likely effect of this simplification on the predictions of the musculoskeletal model of AnyBody Modeling System (AMS) for muscle forces and spinal loads. Clinical application of this study is in assessing the limitation of...

A Mechanical model for flexible exercise bars to study the influence of the initial position of the bar on lumbar discs and muscles forces

, Article Proceedings of the Annual International Conference of the IEEE Engineering in Medicine and Biology Society, EMBS, 25 August 2015 through 29 August 2015 ; Volume 2015-November , 2015 , Pages 3917-3920 ; 1557170X (ISSN) ; 9781424492718 (ISBN) Khalaf, K ; Abdollahi, M ; Nikkhoo, M ; Hoviattalab, M ; Asghari, M ; Ashouri, S ; Nikpour, S ; Kahrizi, S ; Parnianpour, M ; Sharif University of Technology

Institute of Electrical and Electronics Engineers Inc 2015

Abstract

A single-degree-of-freedom model is considered for flexible exercise bars based on the lumped-element approach. By considering the side segment of a flexible bar as a cantilever beam with an equivalent mass at the free end, its free-vibration response, as well as the forced response under the excitation of the grip, are expressed parametrically. Experiments are performed on a particular flexible bar (FLEXI-BAR) in order to obtain numerical values for quantifying the model's parameters. The model is also computationally simulated to study the response of the flexible bar to various excitations. The results are imported into a multi-segment musculoskeletal software (AnyBody), where the effect...

Technical English for mechanical engineers

, Book Alemi, Minoo ; Meghdari,Ali

Sharif University Press 2014

Abstract

Local educational institutions produce in-house English for Specific Purpose (ESP) materials according to the curriculum policies designated and developed by the Ministry of Higher Education In Iran. To this end, this book aims to be used in the Iranian setting at the tertiary level for undergraduate students majoring in Mechanical Engineering. Moreover, the style of English usage in this ESP textbook is American.
Regarding the content of the textbook, it has both thematic organizations in which the topics are relevant and includes sufficient treatment of the target language areas necessary for the students. The principle organizing approach of this textbook is theme-based. In addition,...

Feedback control of the neuro-musculoskeletal system in a forward dynamics simulation of stair locomotion [electronic resource]

, Article Proc. of IMechE Part H: Journal of Engineering in Medicine ; 2009, Vol. 223, No. 6, pp. 663-675 Journal of NeuroEngineering and Rehabilitation ; Volume 11, Issue 1, 30 April 2014, Article number 78 Selk Ghafari, A. (Ali) ; Meghdari, Ali ; Vossough, Gholam Reza ; Sharif University of Technology

Abstract

The aim of this study is to employ feedback control loops to provide a stable forward dynamics simulation of human movement under repeated position constraint conditions in the environment, particularly during stair climbing. A ten-degrees-of-freedom skeletal model containing 18 Hill-type musculotendon actuators per leg was employed to simulate the model in the sagittal plane. The postural tracking and obstacle avoidance were provided by the proportional—integral—derivative controller according to the modulation of the time rate change of the joint kinematics. The stability of the model was maintained by controlling the velocity of the body's centre of mass according to the desired centre of...

Design and Construction of a Soft Actuated Exoskeleton for Hand Rehabilitation of Stroke Patients

, M.Sc. Thesis Sharif University of Technology Razavi Zadehgan, Ali Akbar (Author) ; Ghafari, Ali (Supervisor) ; Meghdari, Ali (Supervisor)

Abstract

The main goal of this thesis is the design and development of a rehabilitation device for helping patients “to improve blood circulation” & retain and recover their abilities if possible that were lost during the stroke or a accident like that (my research in karaj/iran shows that it is possible by just movement of the specific body part). The focus is on hand in this thesis because Injuries to the hand are common and can be very debilitating since our hands are our primary means for interacting with our world. For rehabilitation in case of human hand there are several practices that should be done for patients either in home or in a rehabilitation center, time and money that is supposed to...

Silica chloride/wet SiO2 as a novel heterogeneous system for the deprotection of acetals under mild conditions [electronic resource]

, Article Phosphorus, Sulfur, and Silicon and the Related Elements ; Volume 178:2667-2670, Issue 12, 2003 Mirjalili, B. F. (BiBi Fatemeh) ; Pourjavadi, Ali ; Zolfigol, Mohammad Ali ; Bamoniri, Abdolhamid

Abstract

A combination of silica chloride and wet SiO2 was used as an effective deacetalizating agent for the conversion of acetals to their corresponding carbonyl derivatives under mild and heterogeneous condition

Earthquake Branch

, M.Sc. Thesis Sharif University of Technology Bagher Shemirani, Ali Reza (Author) ; Bakhshi, Ali (Supervisor)

Abstract

In the past few decades, shaking tables are widely used to evaluate system response of structures under seismic excitations. These devices are used without any fundamental research performed on a shaking table system as an entity model. In most of these studies for simplicity, it is assumed that there exist no considerable vibration and displacement around the shaking tables, and no attention is paid to the peripheral substances such as soil settled under the foundation.
In this thesis, result of ambient vibration test on shaking table system (solid deck, concrete foundation and soil layer) has been presented. Precise sensors known as low frequency and high accuracy accelerometers have...

Selective synthesis of conjugated enynes from α-arylalkynols using LiCl-Acidic Al2O3 under solvent-free conditions [electronic resource]

, Article Journal of Chemical Research ; Volume 2002, Number 8, 1 August 2002, pp. 378-380(3) Pourjavadi, A. (Ali) ; Bagheri Marandi, Gholam

Abstract

Free Content Selective synthesis of conjugated enynes from α-arylalkynols using LiCl-Acidic Al2O3 under solvent-free conditions

Selective preparation of fluorescent 1,8-naphthalimides using acidic alumina under microwave irradiation [electronic resource]

, Article Journal of Chemical Research ; 01/2001; 2001(11):485-487 Pourjavadi, A. (Ali) ; Bagheri Marandi, Gholam

Abstract

7H-benzimidazo[2,1-a]benz[de]isoquinolin-7-one compounds were prepared in a selective manner by reaction between o-phenylenediamines and appropriate 1,8-naphthalenedicarboxylic anhydrides using acidic alumina under microwave irradiation

Comparison between Performance of Stone Columns and RAPs from the Bearing Capacity and Settlement Reduction Viewpoints

, M.Sc. Thesis Sharif University of Technology Golestani Dariani, Ali Akbar (Author) ; Pak, Ali (Supervisor)

Abstract

Out of several ground improvement techniques available, stone columns have been widely used. This technique has been successfully applied to increase the bearing capacity and to reduce the settlement for foundation of structures like liquid storage tanks, earthen embankments, raft foundations, etc., where a relatively large settlement is permissible. This technique has, generally, been proven successful in increasing the stiffness of weak soils, upgrading their safe bearing capacity, and reducing their total and differential settlements, as well as speeding up their consolidation process. The beneficial effects of stone column installation in weak deposits is manifested in the form of...

Performance of Partially Filled Mini-Channels with Porous Media

, M.Sc. Thesis Sharif University of Technology Azimi, Adel (Author) ; Nouri, Ali (Supervisor) ; Moosavi, Ali (Co-Advisor)

Abstract

Laminar forced convection flow through a channel partially filled with a porous material was numerically studied in this thesis. The Navier-Stokes and Brinkman-Forchheimer equations were used to model the fluid flow in the free and porous regions, respectively. Coupling of the pressure and velocity fields was resolved using the SIMPLEC algorithm. The local thermal equilibrium was adopted in the energy equation. The effects of the thermal conductivity ratio, Darcy number, porosity, Reynolds number and height of the porous insert on velocity and temperature field were investigated. The results show that the flow behavior and its associated heat transfer are susceptible to the variation of the...

Improvement of Stability of Haptic Force Interaction with Virtual Environments Using a Haptic Interface with a Separate Tracker

, M.Sc. Thesis Sharif University of Technology Mashayekhi, Ahmad (Author) ; Meghdari, Ali (Supervisor) ; Nahvi, Ali (Supervisor)

Abstract

In the present study, a new version of haptic devices is presented in which user’s hand is in contact with the device just while collision with virtual surface. In this system, the position of user’s finger can be traced by using a camera and the haptic device follows user’s finger at the distance of about two centimeters. While the haptic device approaches to the virtual surface, gradually reduces its speed and stops about two centimeters distant of virtual plane. Then user’s hand collides with the haptic device which is static. Greater fidelity, transparency, more stability and also no need to large actuators are of the advantages of this system. In this project, first we present a new...

Simulation of the Biomolecule Imaging and Manipulation Via AFM by Molecular Dynamics Method

, M.Sc. Thesis Sharif University of Technology Kheiroddin, Mohsen (Author) ; Meghdari, Ali (Supervisor) ; Moosavi, Ali (Supervisor)

Abstract

In this thesis we try to find optimized parameters for imaging and manipulation of a biosample with AFM. For this we have prepared a numerous Molecular Dynamics simulation and find some reliable result. So, first we have focused on imaging process in Non contact mode (the less harmful mode). Then we headed into the manipulation process. The main problem about manipulating a biosample is the environment. In imaging section, the process of imaging a biomolecule by AFM is modeled using molecular dynamics simulations. Since the large normal force exerted by the tip on the biosample in contact and tapping modes may damage the sample structure and produce irreversible deformation, the non-contact...

Characterzing Variation of Small Strain Shear Modulus of Unsaturated Sand During Hydraulic Hysteresis with Bender Elements

, M.Sc. Thesis Sharif University of Technology Shahbazan, Parisa (Author) ; Pak, Ali (Supervisor) ; Khosravi, Ali (Supervisor)

Abstract

Results of previous studies on silt and clay indicated that variations in the small strain shear modulus, Gmax, during drying had a non-linear increasing trend with matric suction with greater values upon wetting. However, due to different material properties and inter-particle forces, different behaviour in Gmax is expected for sand. Although considerable research has been devoted in recent years to characterize the behaviour of Gmax of sand during drying, rather less attention has been paid to the effect of hydraulic hysteresis on Gmax and its variations during wetting. In the study presented herein, an effort was made to characterize the variation of Gmax for specimens of sand during...

Sequential Competitive Facility Location In Continuous Geometric Space

, M.Sc. Thesis Sharif University of Technology Lavasani, Ali Mohammad (Author) ; Abam, Mohammad Ali (Supervisor)

Abstract

Abstract The problem of competetive facility location can be defined as follows: There are a number of customers in the form of points in space, and two players arrange a number of facilities in the form of points in space, given some limitations, respectively. Each customer’s connection to each facility has a cost for the customer and an advantage for the facility, and each customer wants to be connected to at most one of the facilities which has the lowest cost for him. The goal is to find the strategy of placing the facilities and determining the cost which the facility receives from the customer, in such a way that the player’s profit is maximised.In this thesis, we first sought to...

Distributed Verifiable Computing: Algorithms and Analysis

, M.Sc. Thesis Sharif University of Technology Rahimi, Ali (Author) ; Maddah Ali, Mohammad Ali (Supervisor)

Abstract

Zero knowledge proofs allow a person (prover) to convince another person (verifier) that he has performed a specific computation on a secret data correctly, and has obtained a true answer, without having to disclose the secret data. QAP (Quadratic Arithmetic Program) based zkSNARKs (zero knowledge Succinct Non-interactive Argument of Knowledge) are a type of zero knowledge proof. They have several properties that make them attractive in practice, e.g. verifier's work is very easy. So they are used in many areas such as Blockchain and cloud computing. But yet prover's work in QAP based zkSNARKs is heavy, therefore, it may not be possible for a prover with limited processing resource to run...