Loading...
Search for: tamaddoni--h---hossein
0.112 seconds

    Document Biped hopping control bazsed on spring loaded inverted pendulum model [electronic resource]

    , Article Int. Journal of Humanoid Robotics ; Vol. 7, No. 2, pp. 263-280, 2010 Tamaddoni, H. (Hossein) ; Jafari, Farid ; Meghdari, Ali ; Sohrabpour, Saeed ; Sharif University of Technology
    Abstract
    Human running can be stabilized in a wide range of speeds by automatically adjusting muscular properties of leg and torso. It is known that fast locomotion dynamics can be approximated by a spring loaded inverted pendulum (SLIP) system, in which leg is replaced by a single spring connecting body mass to ground. Taking advantage of the inherent stability of SLIP model, a hybrid control strategy is developed that guarantees a stable biped locomotion in sagittal plane. In the presented approach, nonlinear control methods are applied to synchronize the biped dynamics and the spring-mass dynamics. As the biped center of mass follows the mass of the mass-spring model, the whole biped performs a... 

    A novel method of gait synthesis for bipedal fast locomotion

    , Article Journal of Intelligent and Robotic Systems: Theory and Applications ; Volume 53, Issue 2 , 2008 , Pages 101-118 ; 09210296 (ISSN) Meghdari, A ; Sohrabpour, S ; Naderi, D ; Tamaddoni, S. H ; Jafari, F ; Salarieh, H ; Sharif University of Technology
    2008
    Abstract
    Common methods of gait generation of bipedal locomotion based on experimental results, can successfully synthesize biped joints' profiles for a simple walking. However, most of these methods lack sufficient physical backgrounds which can cause major problems for bipeds when performing fast locomotion such as running and jumping. In order to develop a more accurate gait generation method, a thorough study of human running and jumping seems to be necessary. Most biomechanics researchers observed that human dynamics, during fast locomotion, can be modeled by a simple spring loaded inverted pendulum system. Considering this observation, a simple approach for bipedal gait generation in fast... 

    Effects of Soil-Pile-Structure Interaction on the Seismic Response of a Bridges

    , M.Sc. Thesis Sharif University of Technology Tamaddoni, Nima (Author) ; Ahmadi, Mohammad Mahdi (Supervisor)
    Abstract
    A large number of structures subjected to the seismic loading have been damaged or have experienced failure in different parts such as the pile structure or even in the entire structure due to unanticipated effects of the soil-pile-structure interaction.The complexity of problems regarding the soil-pile-structure interaction is an influencing factor in prediction of the behavior of structure during the earthquakes. In this study, the effect of the interaction on the dynamic response of bridges was investigated using the finite element software ABAQUS. The primary purpose of this study, as previously described, is to study the effects of the soil-structure interaction on a bridge located on a... 

    Biped hopping control bazsed on spring loaded inverted pendulum model

    , Article International Journal of Humanoid Robotics ; Volume 7, Issue 2 , 2010 , Pages 263-280 ; 02198436 (ISSN) Tamaddoni, S. H ; Jafari, F ; Meghdari, A ; Sohrabpour, S ; Sharif University of Technology
    2010
    Abstract
    Human running can be stabilized in a wide range of speeds by automatically adjusting muscular properties of leg and torso. It is known that fast locomotion dynamics can be approximated by a spring loaded inverted pendulum (SLIP) system, in which leg is replaced by a single spring connecting body mass to ground. Taking advantage of the inherent stability of SLIP model, a hybrid control strategy is developed that guarantees a stable biped locomotion in sagittal plane. In the presented approach, nonlinear control methods are applied to synchronize the biped dynamics and the spring-mass dynamics. As the biped center of mass follows the mass of the mass-spring model, the whole biped performs a... 

    Temperature dependence study of nonocontact AFM images using molecular dynamics simulations [electronic resource]

    , Article Int. Journal of Modern Physics ; 2012, Vol. 5, pp. 418-432 Nejat Pishkenari, H. (Hossein) ; Meghdar, Ali ; Sharif University of Technology
    Abstract
    The effect of temperature on the noncontact atomic force microscopy (NC-AFM) surface imaging is investigated with the aid of molecular dynamics (MD) analysis based on the Sutton-Chen (SC) interatomic potential. Particular attention is devoted to the tip and sample flexibility at different temperatures. When a gold coated probe is brought close to the Au (001) surface at high temperatures, the tip and surface atoms are pulled together and their distance becomes smaller. The tip and sample atoms displacement varies in the different environment temperatures and this leads to the different interaction forces. Along this line, to study the effect of temperature on the resulting images, we have... 

    A new model for robust facility layout problem [electronic resource]

    , Article Information Sciences, Elsevier ; Volume 278, 10 September 2014, Pages 498–509 Neghabi, H. (Hossein) ; Eshghi, Kourosh ; Salmani, Mohammad Hassan ; Sharif University of Technology
    Abstract
    The Facility Layout Problem (FLP) is the problem of locating each department in a long plant floor without any overlap between departments in order to minimize the material handling cost. The main purpose of this study is to show the effectiveness of a robust approach to solve FLP. In this study, it is assumed that the departments’ length and width are not predetermined. For modeling this kind of uncertainty, the size of each department is considered as a bounded variable and two new parameters are also introduced to implement a robust approach. Moreover, a new adaptive algorithm is designed to determine the robust layout with respect to the decision makers’ requirements. Furthermore, the... 

    A rewiring mechanism to improve synchronization in Kuramoto networks

    , Article Journal of Statistical Mechanics: Theory and Experiment ; Volume 2022, Issue 11 , 2022 ; 17425468 (ISSN) Hossein Ghorban, S ; Hesaam, B ; Sarbazi Azad, H ; Sharif University of Technology
    Institute of Physics  2022
    Abstract
    The emergence of synchronization among a set of individual oscillators that are coupled in a network is an amazing physical phenomenon that appears in many different systems, from natural sciences to even human behavior. The phenomenon has attracted the attention of many researchers in many fields of science and engineering by the science behind its unique collective behavior without some kind of external organization. One of the most popular models for the dynamical evolution of coupled phase oscillators is the Kuramoto model, which gives a simple yet powerful formalization together with a numerical measure called the degree of synchronization. The crucial role of structural properties of... 

    Validity and size-dependency of cauchy–born hypothesis with Tersoff potential in silicon nano-structures

    , Article Computational Materials Science ; Volume 63 , October , 2012 , PP. 168–177 Khoei, A. R. (Amir Reza) ; Dormohammadi, H. (Hossein) ; Sharif University of Technology
    2012
    Abstract
    One of the most popular constitutive rules that correlate the continuum and atomic properties in multi-scale models is the Cauchy–Born (CB) hypothesis. Based on this constitutive law of continuum media, it assumes that all atoms follow the deformation subjected to the boundary of crystal. In this paper, the validity and failure of CB hypothesis are investigated for the silicon nano-structure by comparison of the continuum and atomic properties. In the atomistic level, the stresses and position of atoms are calculated using the molecular dynamics (MD) simulation based on the Tersoff inter-atomic potential. The stresses and strains are compared between the atomistic and continuous media to... 

    The role of reactants and droplet interfaces on nucleation and growth of ZnO nanorods synthesized by vapor-liquid-solid (VLS) mechanism

    , Article Journal of Alloys and Compounds ; Volume 455, Issue 1-2 , 2008 , Pages 353-357 ; 09258388 (ISSN) Hejazi, S. R ; Madaah Hossein, H. R ; Ghamsari, M. S ; Sharif University of Technology
    2008
    Abstract
    Short ZnO nanorods and long ZnO nanowires have been produced on SiO2 and Si substrates by VLS and VS mechanisms via a double tube chemical vapor transport and condensation (CVTC) process. The role of reactants and droplet interfaces on the nucleation and growth of ZnO nanorods have been investigated. A conceptual model for nucleation of ZnO nanorods has been proposed by describing the half-oxidation and reduction reactions at the growth front. The importance of Zn vapor in the nucleation phenomena has been studied by changing starting materials. Atomic force microscopy (AFM), scanning electron microscopy (SEM), and EDX analysis have been used to characterize ZnO nanorods and investigate the... 

    Adsorption and oxidation of dye and tetracycline over hydrothermally synthesized polyresorcinol – Ferrite nanoparticles

    , Article Desalination and Water Treatment ; Volume 212 , 2021 , Pages 376-389 ; 19443994 (ISSN) Kaveh, R ; Alijani, H ; Hossein Beyki, M ; Jafari Pirouz, M ; Sharif University of Technology
    Desalination Publications  2021
    Abstract
    This study focuses on developing an efficient material that integrates high adsorption performances of dye and antibiotics as well as effective oxidation activity of it. Herein, we report a facile method to synthesize polyresorcinol@CoFe2 O4 via a one-step hydrothermally route. The prepared composite possesses multifunctional performance for methylene blue (MB) and tetracycline (TC) removal with appropriate magnetic separation operation and significant removal ability with an adsorption capacity of 51.48 and 28.16 mg g–1, respectively. Meanwhile, the aforementioned composite exhibits a high oxidation activity toward MB and TC molecules where the adsorption capacity increases to 1,723 and 120... 

    Content-Based medical image transmission against randomly-distributed passive eavesdroppers

    , Article 2021 IEEE International Conference on Communications Workshops, ICC Workshops 2021, 14 June 2021 through 23 June 2021 ; 2021 ; 9781728194417 (ISBN) Letafati, M ; Behroozi, H ; Hossein Khalaj, B ; Jorswieck, E. A ; Sharif University of Technology
    Institute of Electrical and Electronics Engineers Inc  2021
    Abstract
    In this paper, a content-aware medical image transmission scheme is investigated over a multiple-input single-output (MISO) channel in wireless healthcare systems. The multi-antenna-aided access point, as a source node, wishes to wirelessly send medical images of a patient to a trusted destination node, while multiple randomly-located totally passive and non-colluding eavesdroppers (Eves) try to wiretap the transmission. Considering the fact that not all regions of an image have the same importancy level from the security view-point, we first segment the image into two parts: the region of interest (RoI), which more likely contains important diagnostic information regarding the medical image... 

    Secure consensus averaging in sensor networks using random offsets

    , Article 2007 IEEE International Conference on Telecommunications and Malaysia International Conference on Communications, ICT-MICC 2007, Penang, 14 May 2007 through 17 May 2007 ; 2007 , Pages 556-560 ; 1424410940 (ISBN); 9781424410941 (ISBN) Kefayati, M ; Talebi, M. S ; Hossein Khalaj, B ; Rabiee, H. R ; Sharif University of Technology
    2007
    Abstract
    In this work, we have examined the distributed consensus averaging problem from a novel point of view considering the need for privacy and anonymity. We have proposed a method for incorporating security into the scalable average consensus mechanisms proposed in the literature. Random Offsets Method (ROM) is lightweight, transparent and flexible since it is not based on cryptography, does not require any change in the fusion system and can be used optionally by some nodes who care about their privacy. In this method, which is based on noisiflcation of nodes' information, we achieve robustness against n - 1 colluding adversaries in a network of n nodes, which is maximum level of robustness... 

    Light Duty Vehicles' Emission Reduction Potentials in Megacities
    Using New Powertrain Technologies (Case Study: Tehran)

    , M.Sc. Thesis Sharif University of Technology Askariyeh, Mohammad Hashem (Author) ; Erhami, M. (Mohammad) (Supervisor) ; Pourzahedi, H. (Hossein) (Supervisor)
    Abstract
    Tehran is one of the most polluted megacities in the world, and based on different studies, vehicular sources are responsible for most of the criteria pollutant emissions in this city. The number of vehicles on the streets has been increased drastically leading to growing amount of emission and this trend is continuing. In order to reduce the amount of vehicular emission, it is vital to investigate the factors affecting vehicles emission in this city. This could help to find efficient solutions to improve the situation. Hence, a low-cost methodology to estimate the vehicular emissions is developed. In this... 

    On statistical learning of simplices: Unmixing problem revisited

    , Article Annals of Statistics ; Volume 49, Issue 3 , 2021 , Pages 1626-1655 ; 00905364 (ISSN) Najafi, A ; Ilchi, S ; Saberi, A. H ; Motahari, S. A ; Hossein Khalaj, B ; Rabiee, H. R ; Sharif University of Technology
    Institute of Mathematical Statistics  2021
    Abstract
    We study the sample complexity of learning a high-dimensional simplex from a set of points uniformly sampled from its interior. Learning of simplices is a long studied problem in computer science and has applications in computational biology and remote sensing, mostly under the name of “spectral unmixing.” We theoretically show that a sufficient sample complexity for reliable learning of a K-dimensional simplex up to a total-variation error of ε is O(Kε2 log Kε ), which yields a substantial improvement over existing bounds. Based on our new theoretical framework, we also propose a heuristic approach for the inference of simplices. Experimental results on synthetic and real-world datasets... 

    Investigation uncovered the impact of anions on CO2 absorption by low viscous ether functionalized pyridinium ionic liquids

    , Article Journal of Molecular Liquids ; Volume 336 , August , 2021 ; 01677322 (ISSN) Hossein, S ; Dong, H ; Zeng, S ; Umair Ahmad, M ; Khurum Shehzad, F ; Wu, H ; Zhang, Y ; Sharif University of Technology
    Elsevier B. V  2021
    Abstract
    Ionic liquids, which are designable and nonvolatile, have become a hot topic in the field of CO2 separation from industrial gases. In order to utilize the nonvolatile and low heat capacity of ionic liquids, it is necessary to solve the problem of high viscosity of pure ionic liquids. In the present study, ether functionalized pyridinium ion [E1Py]+ with good biodegradability and low viscosity was selected as cation. Ions containing cyano groups were used as anions, such as thiocyanate ion [SCN]-, dicyanamide ion [N(CN)2]-, tricyanomethanide ion [C(CN)3]-. Three ionic liquids with low viscosity were synthesized and characterized by 1HNMR, 13CNMR and FTIR. The physiochemical properties of... 

    Calculation of the Energy Release Rate of Nano-Cracks in FCC Materials Via the Many Body Atomic Scale FEM

    , M.Sc. Thesis Sharif University of Technology Ostad Hossein, Alireza (Author) ; Mohammadi Shodja, Hossein (Supervisor)
    Abstract
    Since the classical continuum theory fails to deal with the problems associated with defects, stress concentrators, and relevant deformation phenomena in solids, alternative approaches that can detect the atomistic nature of materials' fracture are required. The deficiency of the capture the size effect which yields delusively high values for some components of the stress field right on the edge of the stress concentrators, and its weakness in describing the complex interaction between small inhomogeneities, cracks and the like when they are only a few nanometers apart, are among some of the disadvantages of the classical approach. In recent years, however, atomistic methods are emerging to... 

    Semisolid Stir Joining of As-Cast Silicon-Aluminum Bronze

    , M.Sc. Thesis Sharif University of Technology Ferasat, Keyvan (Author) ; Kokabi, Amir Hossein (Supervisor) ; Ashuri, Hossein (Supervisor)
    Abstract
    Aluminum Bronzes have many applications in marine environments. These alloys suffer from both hot cracking and cold cracking. In order to overcome the hot cracking and cold cracking, Semisolid Stir Joining method and a proper thermal cycle was used respectively. Effects of temperature, stirring rate, and tool type were investigated in Semisolid Stir joining method. In this method, butt joint design was used in order to place specimens, and the specimens were heated up to specific temperatures (920, 925, 930°C). A stirrer (Cylindrical and Grooved tool) with three rotational speeds (800, 1200, 1600 RPM) was introduced into the stir weld seam. Welded specimens were cooled to the 900°C... 

    The Study of Eliminating Gender Gap in Iran Labor Market on Participation Rate of Married Urban Women

    , M.Sc. Thesis Sharif University of Technology Asghari, Fatemeh (Author) ; Rahmati, Mohammad Hossein (Supervisor) ; Joshaghani, Hossein (Supervisor)
    Abstract
    The low female labor force participation rate in the Iranian labor market relative to the global average and even to countries that do not differ significantly from the socio-economic characteristics of our country is one of the important questions of the Iranian labor market. In this study, we seek to answer the question of whether the economic participation rate of married women will increase if the gender gaps in wages, job findings and job losses among women and men are eliminated in the Iranian labor market. To answer this question using household expenditure and income data and labor force data, we show that between the two categories of occupations, in terms of the share of women's... 

    On endurance of erasure codes in SSD-based storage systems

    , Article Computer Architecture and Digital Systems (CADS), 17th CSI International Symposium on ; Article number 6714239 , 2013 , Pages 67-72 ; 9781479905621 Alinezhad Chamazcoti, S. (Saeideh) ; Miremadi, Gh. (Sayyed Ghassem) ; Asadi, H. (Hossein) ; Sharif Univesity of Technology
    2013
    Abstract
    The wear-out of flash-based Solid-State Drives (SSDs) is a main concern that significantly affects their reliability. One major parameter that accelerates SSD wear-out is the number of write-cycles committed to flash chips. The number of write-cycles in SSD-based disk subsystem is highly dependent on the erasure code implemented in Redundant Array of Independent Disks (RAIDs). In this paper, we investigate the impact of erasure codes and the configuration of storage subsystems (i.e., the number of disks participated in the RAID array and stripe unit size) on the endurance of storage systems. The number of write-cycles is considered as a metric to evaluate the endurance of storage system. We...