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    Design and implementation of a new body weight support (BWS) system

    , Article 5th RSI International Conference on Robotics and Mechatronics, IcRoM 2017, 25 October 2017 through 27 October 2017 ; 2018 , Pages 69-75 ; 9781538657034 (ISBN) Hamidi Rad, M ; Behzadipour, S ; Sharif University of Technology
    Institute of Electrical and Electronics Engineers Inc  2018
    Abstract
    Gait training is a critical rehabilitation procedure for patients suffering from walking problems. It, however, puts the therapist in high orthopedic risk since he should prevent the patient from possible falling. Body weight support system is a new technology helping such patients and the involved therapist by unloading a percent of the patient's weight. A new over-ground body weight support is introduced in this article. The system is composed of two main modules namely unloading and traction. The unloading module is capable of suspending an individual's weight up to 1000N dynamically. The whole system is attached to an overhead rail, moving over the head of the patient by the traction... 

    Critical state concepts for a cemented gravely sand

    , Article Electronic Journal of Geotechnical Engineering ; Volume 10 E , 2005 ; 10893032 (ISSN) Hamidi, A ; Haeri, S. M ; Sharif University of Technology
    2005
    Abstract
    The shear behavior of a cemented gravely sand that can be considered as the representative of Tehran alluvium has been studied using triaxial equipment. Artificially cemented samples were prepared using gypsum plaster as the cementing agent. The plaster was mixed with the base soil at the weight percentages between 1.5 and 6. The critical state concepts were used to illustrate the mechanical behavior of tested soil. © 2005 ejge  

    Block adaptive compressive sensing for distributed MIMO radars in clutter environment

    , Article Proceedings International Radar Symposium, 10 May 2016 through 12 May 2016 ; Volume 2016-June , 2016 ; 21555753 (ISSN) ; 9781509025183 (ISBN) Abtahi, A ; Mohajer Hamidi, S ; Marvasti, F ; Sharif University of Technology
    IEEE Computer Society  2016
    Abstract
    For the target parameter estimation in MIMO radars in the presence of strong clutter, non-adaptive compressive sensing methods have a poor performance. On the other hand, the adaptive ones usually need higher data acquisition time. In this paper, we propose an adaptive compressive sensing method called L-BGT that has tolerable data acquisition time. furthermore, we have presented the essential changes in a distributed MIMO radar to exploit an adaptive group testing compressive sensing method  

    Uncertainty analysis of wind-wave predictions in Lake Michigan

    , Article China Ocean Engineering ; Volume 30, Issue 5 , 2016 , Pages 811-820 ; 08905487 (ISSN) Nekouee, N ; Ataie Ashtiani, B ; Hamidi, S. A ; Sharif University of Technology
    Springer Verlag  2016
    Abstract
    With all the improvement in wave and hydrodynamics numerical models, the question rises in our mind that how the accuracy of the forcing functions and their input can affect the results. In this paper, a commonly used numerical third-generation wave model, SWAN is applied to predict waves in Lake Michigan. Wind data are analyzed to determine wind variation frequency over Lake Michigan. Wave predictions uncertainty due to wind local effects are compared during a period where wind has a fairly constant speed and direction over the northern and southern basins. The study shows that despite model calibration in Lake Michigan area, the model deficiency arises from ignoring wind effects in small... 

    On new nonlinearity in third-order elastic modulus for vibrational analysis of FG porous beam based on nonlocal strain gradient and surface energy by modified homotopy perturbation method

    , Article European Physical Journal Plus ; Volume 137, Issue 4 , 2022 ; 21905444 (ISSN) Hosseini, S. A ; Alizadeh Hamidi, B ; Maboudi, G ; Sharif University of Technology
    Springer Science and Business Media Deutschland GmbH  2022
    Abstract
    In the current study, by considering both material and geometry nonlinearity, the nonlinear free vibration of functionally graded porous nanobeams based on the nonlocal strain gradient theory is investigated. Generally, the third-order elastic modulus, von Karman strain–displacement relationship, is assumed to incorporate the nonlinearity into the differential equation of the problem. In this paper, for the first time, the nonlinear vibrational response of the nanobeam does not merely depend on the geometric nonlinearity. Also, material nonlinearity of the bulk and surface layers is taken into consideration. Governing equations and the related boundary conditions are obtained by utilizing... 

    Non-fragile control and synchronization of a new fractional order chaotic system

    , Article Applied Mathematics and Computation ; Volume 222 , 2013 , Pages 712-721 ; 00963003 (ISSN) Asheghan, M. M ; Delshad, S. S ; Hamidi Beheshti, M. T ; Tavazoei, M. S ; Sharif University of Technology
    2013
    Abstract
    In this paper, we address global non-fragile control and synchronization of a new fractional order chaotic system. First we inspect the chaotic behavior of the fractional order system under study and also find the lowest order (2.49) for the introduced dynamics to remain chaotic. Then, a necessary and sufficient condition which can be easily extended to other fractional-order systems is proposed in terms of Linear Matrix Inequality (LMI) to check whether the candidate state feedback controller with parameter uncertainty can guarantee zero convergence of error or not. In addition, the proposed method provides a global zero attraction of error that guarantees stability around all existing... 

    Generation of motional entangled coherent state in an optomechanical system in the single photon strong coupling regime

    , Article Journal of Modern Optics ; Volume 62, Issue 19 , Jul , 2015 , Pages 1685-1691 ; 09500340 (ISSN) Mahmoudi, Z ; Shakeri, S ; Hamidi, O ; Zandi, M. H ; Bahrampour, A ; Sharif University of Technology
    Taylor and Francis Ltd  2015
    Abstract
    The single-photon strong coupling in the deep-resolved sideband of the optomechanical system induces photon blockade (PB) effect. For the PB cavity, an initial mechanical coherent state evolves into superposition of phonon cat states entangled with the cavity Fock states. Measurement of the cavity photon number states produces phonon even and odd cat states. The information leakage effect of two photon states on the fidelity of cat states is calculated, it is shown that for low average phonon number this effect is negligible and decreases by increasing the two photon cavity state. The Lindblad equation is solved numerically to obtain the environmental effects on the fidelity of cat states  

    Hydrogen storage in single- and multi-walled carbon nanotubes and nanotube bundles

    , Article Australian Journal of Basic and Applied Sciences ; Volume 5, Issue 7 , 2011 , Pages 483-490 ; 19918178 (ISSN) Hamidi, S ; Golnabi, H ; Sharif University of Technology
    2011
    Abstract
    This article describes the hydrogen storage capacity in different carbon nanotubes. The hydrogen storage capacities in the armchair, zigzag, and chiral nanotubes are investigated. The hydrogen storing capacities as a function of the carbon nanotube (CNT) diameter are investigated for the single-walled (SWNT), multi-walled (MWNT), and CNT bundles and results are compared. Hydrogen storage capacity in SWNTs is increased by increasing the nanotube diameter. For diameter d=0.3887 nm of (5,0) CNT the hydrogen capacity is 0.99%, while for the (17,17) SWNT with a diameter d=2.289 nm the capacity is increased to 5.06%. In comparison of different MWNTs for a common external diameter d=1.6064 nm the... 

    An Investigation on the Effect of Filler Type and Content on the Performance of Asphaltic Materials

    , M.Sc. Thesis Sharif University of Technology Hamidi, Arman (Author) ; Motamed, Arash (Supervisor)
    Abstract
    The objective of this research is evaluating the effect of filler type and content on the characteristics of asphaltic materials. The properties of the asphalt mixture are greatly influenced by its components. As asphalt mixtures are composed of two prominent components, aggregates and binder, the change in type and contents of these materials may lead to altering the performance of asphalt mixtures. Aggregates in the asphalt mixtures are categorized into three groups based on their particle sizes: coarse aggregate, fine aggregate and mineral filler. The effect of filler on the characteristics of asphalt mixtures can be examined by changing the type and content of filler and holding the... 

    The effect of filler type and content on rutting resistance of asphaltic materials

    , Article International Journal of Pavement Research and Technology ; Volume 12, Issue 3 , 2019 , Pages 249-258 ; 19966814 (ISSN) Hamidi, A ; Motamed, A ; Sharif University of Technology
    Springer  2019
    Abstract
    This research evaluates the effect of filler type and content on rutting resistance of asphaltic materials by using laboratory experiments. To examine the effect of filler type, two traditional fillers (Silica sandstone powder and Portland cement) and a new recycled lime powder (Eggshell) were considered. To investigate the effect of filler content, three different filler contents were used. Marshall Stability test was performed on full mixes in order to determine the optimum binder content of the mixtures. Then, the static creep test was performed on Fine Aggregate Matrix (FAM) samples. The permanent strain after 10 minutes of recovery (PS-660) was considered as the indicator of potential... 

    Robust outer synchronization between two complex networks with fractional order dynamics

    , Article Chaos ; Volume 21, Issue 3 , 2011 ; 10541500 (ISSN) Asheghan, M. M ; Míguez, J ; Hamidi Beheshti, M. T ; Tavazoei, M. S ; Sharif University of Technology
    2011
    Abstract
    Synchronization between two coupled complex networks with fractional-order dynamics, hereafter referred to as outer synchronization, is investigated in this work. In particular, we consider two systems consisting of interconnected nodes. The state variables of each node evolve with time according to a set of (possibly nonlinear and chaotic) fractional-order differential equations. One of the networks plays the role of a master system and drives the second network by way of an open-plus-closed-loop (OPCL) scheme. Starting from a simple analysis of the synchronization error and a basic lemma on the eigenvalues of matrices resulting from Kronecker products, we establish various sets of... 

    Risk analysis of liquefaction potential in South West Tehran

    , Article Amirkabir (Journal of Science and Technology) ; Volume 15, Issue 58 D , 2004 , Pages 521-534 ; 10150951 (ISSN) Hamidi, A ; Haeri, S. M ; Shirazi, A ; Olyaei, M. N ; Bakhshi, A ; Sharif University of Technology
    2004

    An analytical model for evaluation of wireless mesh networks

    , Article 2008 International Symposium on Telecommunications, IST 2008, Tehran, 27 August 2008 through 28 August 2008 ; October , 2008 , Pages 295-300 ; 9781424427512 (ISBN) Hamidi Sepehr, F ; Ashtiani, F ; Sharif University of Technology
    2008
    Abstract
    Wireless mesh networks (WMNs) are well-promising future networks especially for ubiquitous connection to Internet. In this paper, we propose an analytical model in order to evaluate the maximum stable throughput of a WMN based on a simplified version of IEEE 802.11s MAC protocol. Our modeling approach is based on a multi-class open queueing network. In this respect, we map some of the important features of IEEE 802.11s MAC protocol, esp., its contention-based and contention-free periods onto different parameters of the proposed queueing network. By solving the related traffic equations and applying the stability condition, we determine the maximum stable throughput, i.e., the maximum packet... 

    Modeling and Optimization of Energy Engineering Department Building HVAC System Operation by Online Monitoring of Indoor Conditions

    , M.Sc. Thesis Sharif University of Technology Hamidi, Mohammad Bagher (Author) ; Rajabi, Abbas (Supervisor)
    Abstract
    Increasing global final energy demand and the use of fossil fuels to meet this amount of energy demand have raised concerns about environmental impacts of fossil fuel consumption and the reduction of fossil energy reserves. Among the energy consumer sectors including industry, transport activities, agriculture, and households, the household sector is one of the most important sectors, regarding its share of total final energy consumption. Heating and cooling systems, which mainly use fossil fuels, are the biggest energy consumers in the household sector. Hence, optimal management of the heating and cooling systems can play an effective role in reducing energy costs in buildings. In this... 

    An Agent-based Architecture for Reverse Logistics in Cloud Manufacturing

    , M.Sc. Thesis Sharif University of Technology Hamidi Moghaddam, Simin (Author) ; Houshmand, Mahmoud (Supervisor)
    Abstract
    Cloud Manufacturing (CMfg) which is one of the newest and important business models, can have a great effect in enterprises' success by sharing information and production resources among them. Due to the semi-made products which should be transferred between distributed production centers, Logistics and Transportation concept in CMfg are very important. Reverse Logistics (RL) that is the flow of used products from customer to manufacturer, by its role in recycling and proper disposal of components, has a great impact on industry effect on environment and helps enteprises to make better profit. Despite this importance, working on RL in CMfg has not been paid attention to in former researches.... 

    Design of Transmit Code & Receive Filter in Radar Via Manifold Optimization

    , M.Sc. Thesis Sharif University of Technology Attar Hamidi, Farzin (Author) ; Karbasi, Mohammad (Supervisor)
    Abstract
    The problem of joint design of transmit code and receive filter is considered in many application scenarios of multiple input multiple output (MIMO) radar systems. The performance of the joint design problem is evaluated with the signal-to-interference ratio (SINR) metric in the presence of noise. In such problems, the optimization problem is to maximize SINR on the receiver side with the constraints that are applied on the transmitted waveform. Our proposed method, RTR, is a manifold-based geometric method that performs better than the SDP method in terms of algorithm execution speed and calculation complexity. For simulation, we took sampled and real TIR with Target Aspect Angle (TAA) in a... 

    Kolyvagin’s Theorem

    , M.Sc. Thesis Sharif University of Technology Hamidi, Mohammad Masih (Author) ; Rastegar, Arash (Supervisor)
    Abstract
    Kolyvagin’s theorem, stated in the late 1980s, is a very important theorem in the theory of elliptic curves, which, together with Gross-Zagier’s work, results in a special case of the Birch and Swinerton-Dyer conjecture, which relates algebraic and analytic properties of the rational elliptic curves to each other. Although the correctness of this conjecture, in general, is an open problem, Kolyvagin’s idea and the concepts he introduced while proving his theorem are very powerful and can be applied to more general situations. The purpose of writing this dissertation is to collect the equivalent forms of Kolyvagin’s theorem with proofs of the main results. We will also give a brief overview... 

    Optical Conductivity of Fermi Arc States

    , M.Sc. Thesis Sharif University of Technology Hamidi Ravari, Zeinab (Author) ; Jafari, Akbar (Supervisor)
    Abstract
    Recently, some materials, such as Weyl and Dirac semimetals, have been found in condensed matter physics whose band structure behaves like Weyl fermions of elementary particles near some points of the first Birillouin zone. The Weyl equation that governs these materials, have boundary because they are finite. By applying proper boundary conditions, two-dimensional surface states have been emerged. these states are called fermi arc sates because the surface corresponding to the fermi energy is not a closed surface. Surface states are mixed with bulk states because by getting close to the end of fermi arcs, surface states tend to bulk states con-tinuously. Being able to distinguish between... 

    Point Cloud Semantic Segmentation with Limited Supervision using Deep Neural Networks

    , M.Sc. Thesis Sharif University of Technology Hamidi Hesarsorkh, Hassan (Author) ; Kasaei, Shohreh (Supervisor)
    Abstract
    One of the most common forms of three-dimensional data is point clouds. In addition to its high flexibility in storing three-dimensional space, this type of data is the closest type of data to the output of three-dimensional sensors. Semantic segmentation of point clouds is a fundamental operation on this type of data, with applications in robotics, self-driving cars, virtual reality, remote sensing, and other fields that work with this type of data. Since deep learning models require abundant data for training, this type of data is not an exception to this rule with these models. However, the problem is that collecting and labeling this type of data is more difficult and costly compared to... 

    Consistency of Lasso Estimator

    , M.Sc. Thesis Sharif University of Technology Hamidi, Nima (Author) ; Haji Mirsadeghi, Mir Omid (Supervisor)
    Abstract
    In this thesis, we are going to study the consistency properties of one of the most well-known linear estimators – LASSO estimator. First, we bring up some necessary background for introducing this estimator. Then, we are able to introduce primary and secondary forms of LASSO estimator. After that, we prove that primary form of the LASSO estimator is weakly consistent under certain weak conditions. We, also, prove a much stronger statement about the secondary form. We prove that the secondary form is strongly consistent. What’s more, with extra assumptions, we specify the convergence rate of the estimator. Finally, we propose a method for determining free parameter of primary form of LASSO,...