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    Modular framework kinematic and fuzzy reward reinforcement learning analysis of a radially symmetric six-legged robot

    , Article Life Science Journal ; Volume 10, Issue SUPPL 8 , 2013 , Pages 120-129 ; 10978135 (ISSN) Shahriari, M ; Osguie, K. G ; Khayyat, A. A. A ; Sharif University of Technology
    2013
    Abstract
    Hexapod robots gives us the ability to study walking robots without facing problems such as stability in many aspects. It has a great deal of flexibility in movement even if a leg becomes malfunctioned. Radially symmetric (hexagonal) hexapods have more flexibility in movement than rectangular leg alignments. Because of symmetry they can move in any direction and time efficiently. Inverse kinematic problem of this kind of hexapods is solved through a modular mobile view considering six degrees of freedom for the trunk. Then typical tripod and wave gaits are analyzed and simulated through the presented formulation. In Reinforcement Learning algorithm for walking it is important how to make... 

    Effect of compressive glass fiber-reinforced polymer bars on flexural performance of reinforced concrete beams

    , Article ACI Structural Journal ; Volume 119, Issue 6 , 2022 , Pages 5-18 ; 08893241 (ISSN) Hassanpour, S ; Khaloo, A ; Aliasghar Mamaghani, M ; Khaloo, H ; Sharif University of Technology
    American Concrete Institute  2022
    Abstract
    This research studies the effect of glass fiber-reinforced polymer (GFRP) bars as compressive reinforcement in reinforced concrete (RC) beam members. Three singly and six doubly reinforced GFRP-RC beams were tested under a four-point loading configuration. The effect of compressive reinforcement on the load-bearing capacity, ductility, stiffness, and failure mode is determined. Also, the compressive performance of GFRP bars is evaluated by testing GFRP-RC cylinders. According to the results, GFRP bars in compression had a limited contribution to enhancing flexural strength, and the maximum increment in the flexural capacity of doubly reinforced beams compared to singly reinforced specimens... 

    Study the effect of architectural modification on fracture behavior of Al-DRA composite

    , Article Mechanics of Advanced Materials and Structures ; Vol. 21, issue. 8 , 2014 , Pages 662-668 ; ISSN: 15376494 Jamali, M ; Khalili, S ; Bagheri, R ; Simchi, A ; Sharif University of Technology
    Abstract
    An architectural modification method was utilized to improve fracture toughness of discontinuously reinforced aluminum (DRA) composites. Al-DRA composites having a structure similar to that of reinforced concrete were fabricated. The number of reinforcing DRA rods within Al matrix and volume fraction of SiC particles in DRA were altered to evaluate their effect on fracture behavior of these materials. It was found that architectural modification does not have any destructive influence on elastic modulus and yield strength of the composite. Moreover, the success of this method on toughness improvement strongly depends on the occurrence of debonding between Al and DRA regions upon loading  

    Interface behavior between carbon-fiber polymer and sand

    , Article Journal of Testing and Evaluation ; Volume 44, Issue 1 , 2016 , Pages 385-390 ; 00903973 (ISSN) Toufigh, V ; Ouria, A ; Desai, C. S ; Javid, N ; Toufigh, V ; Saadatmanesh, H ; Sharif University of Technology
    ASTM International  2016
    Abstract
    Interface shear strength between soil and structural materials is dependent on the confining pressure. To increase the confining pressure, different methods of reinforcement and materials, such as carbon-fiber-reinforced polymer (CFRP) can be used. The shear strength of CFRP-improved soil is dependent on the interface properties of the soil and CFRP. The objective of this study is to investigate the interface properties (friction angle and adhesion) of sand and FRP experimentally using the direct shear test apparatus. To increase the surface roughness to improve the interface properties, a layer of sand was placed on saturated carbon fiber during the curing period [spark plasma sintering... 

    Environmental effects on the bond at the interface of fiber-reinforced polymer and masonry brick

    , Article Journal of Reinforced Plastics and Composites ; Volume 36, Issue 18 , 2017 , Pages 1355-1368 ; 07316844 (ISSN) Toufigh, V ; Yarigarravesh, M ; Mofid, M ; Sharif University of Technology
    Abstract
    This study examined the bond at the interface of masonry bricks and fiber-reinforced polymer when exposed to five environments. Three fabrics (aramid, carbon, and glass) and one type of epoxy resin were used. A total of 375 brick-fiber-reinforced polymer specimens were made using wet lay-up technic and exposed to chemical solutions at four pH values (2.5, 7, 10, and 12.5) and substitute seawater. The effect of dry heat on the bond at the interface was also investigated. Single-lap shear tests were then carried out on the samples after 2, 4, 6, 8, 10, and 13 weeks of exposure. The experimental results indicated that freshwater and seawater had a considerable effect on the bond strength of... 

    Real-Time IDS using reinforcement learning

    , Article 2008 2nd International Symposium on Intelligent Information Technology Application, IITA 2008, Shanghai, 21 December 2008 through 22 December 2008 ; Volume 2 , January , 2008 , Pages 593-597 ; 9780769534978 (ISBN) Sagha, H ; Bagheri Shouraki, S ; Hosein, K ; Mahdi, D ; Sharif University of Technology
    2008
    Abstract
    In this paper we proposed a new real-time learning method. The engine of this method is a fuzzy-modeling technique which is called ink drop spread (IDS). IDS method has good convergence and is very simple and away from complex formula. The proposed method uses a reinforcement learning approach by an actor-critic system similar to Generalized Approximate Reasoning based Intelligent Control (GARIC) structure to adapt the IDS by delayed reinforcement signals. Our system uses Temporal Difference (TD) learning to model the behavior of useful actions of a control system. It is shown that the system can adapt itself, commencing with random actions. © 2008 IEEE  

    Investigation of various concrete materials to simulate seismic response of RC structures

    , Article Structures ; Volume 29 , 2021 , Pages 1322-1351 ; 23520124 (ISSN) Asgarpoor, M ; Gharavi, A ; Epackachi, S ; Sharif University of Technology
    Elsevier Ltd  2021
    Abstract
    This paper focuses on the performance evaluation of several concrete models in reinforced concrete (RC) structures subjected to seismic loading. Despite many studies conducted on implementing different characteristics of concrete in constitutive models, there is an essential need for investigating the ability of these models in predicting the behavior of structures in seismic applications. In this paper, several developed plasticity-based constitutive models with the combination of fracture and continuum damage models are investigated for application in seismic loading conditions. Damage-based isotropic and anisotropic models and smeared cracking approach have been applied as complementary... 

    Dynamic performance of concrete slabs reinforced with steel and GFRP bars under impact loading

    , Article Engineering Structures ; Volume 191 , 2019 , Pages 62-81 ; 01410296 (ISSN) Sadraie, H ; Khaloo, A ; Soltani, H ; Sharif University of Technology
    Elsevier Ltd  2019
    Abstract
    Reinforced concrete slabs are common structural elements that could be exposed to impact loading. Although use of reinforced concrete slabs and utilization of Fiber Reinforced Polymer (FRP) as alternative to traditional steel reinforcement slabs are growing, but the influence of various parameters on their response under impact loads is not properly evaluated. This study investigated the effect of rebar's material, amount and arrangement of reinforcements, concrete strength and slab thickness on dynamic behavior of reinforced concrete slabs using both laboratory experiments and numerical simulations. Performance of fifteen 1000 × 1000 mm concrete slabs, including two 75 mm thick plain slabs,... 

    A simplified MCFT for shear capacity scaling of R/C beams

    , Article 16th European Conference of Fracture, 3 July 2006 through 7 July 2006 ; 2006 , Pages 1363-1364 ; 9781402049712 (ISBN) Kazemi, M. T ; Broujerdian, V ; Sharif University of Technology
    Kluwer Academic Publishers  2006
    Abstract
    It is well known that shear strength of beams without stirrups shows a strong size effect. At present, several formulas of size effect are used by some codes and suggested by various researchers. Most of those formulas are not in agree with fracture mechanics. Recently, a simple formula based on modified compression field theory, MCFT, was proposed (Collins and Kuchma [1], Lubell et al. [2]), which shows a size effect stronger than the size effect formula based on fracture mechanics, proposed by Bazant (e.g. Bazant and Kazemi [3], Bazant and Yu [4]). In this paper it is shown that with some refined considerations, formulas are resulted in agree with Fracture Mechanics concept. In the derived... 

    Behavior of square concrete columns strengthened with Carbon Fiber Reinforced Polymer (CFRP) strips

    , Article 1st International Conference on Concrete Repair, Rehabilitation and Retrofitting, ICCRRR 2005, Cape Town, 21 November 2005 through 23 November 2005 ; 2006 , Pages 471-473 ; 0415396549 (ISBN); 9780415396547 (ISBN) Taleie, S. M ; Moghaddam, H ; Sharif University of Technology
    2006
    Abstract
    Reinforced concrete columns with insufficient transverse steel reinforcement are not capable to dissipate seismic energy due to lack of necessary ductility. In this research, six RC columns with poor transverse reinforcements are tested under cyclic and axial loads as control columns and retrofitted ones. Prestressed and non-pre-stressed CFRP strips used as external transverse reinforcement to evaluate the benefits of active and passive confinement. Results indicate that additional confinement due to the use of CFRP strips enhances the strength, ductility and energy dissipation capacity of columns. The advantages of active confinement versus passive confinement are demonstrated too. © 2006... 

    Effect of utilizing glass fiber-reinforced polymer on exural strengthening of rc arches

    , Article Scientia Iranica ; Volume 26, Issue 4A , 2019 , Pages 2299-2309 ; 10263098 (ISSN) Moradi, H ; Khaloo, A. R ; Shekarchi, M ; Kazemian, A ; Sharif University of Technology
    Sharif University of Technology  2019
    Abstract
    An experimental study of the. flexural behavior of Reinforced-Concrete (RC) arches strengthened with Glass Fiber-Reinforced Polymer (GFRP) layers was performed. A total of 36 specimens including 3 un-strengthenod (control) and 33 strengthened RC arches were tested under centrally concentrated point load. The variables of this study were steel reinforcement ratio, number of GFRP layers, and location and arrangement of GFRP layers. Failure mode, load-displacement response of specimens, crack propagation patterns, and GFRP debonding were examined. The extrados strengthening method was shown to Ix1 more effective than the intrados strengthening one in improving the failure load and rigidity of... 

    Numerical and experimental investigation on a BRB confined with partially carbon fiber reinforced polymer (CFRP)

    , Article Engineering Structures ; Volume 223 , 2020 Bashiri, M ; Toufigh, V ; Sharif University of Technology
    Elsevier Ltd  2020
    Abstract
    Buckling-restrained braces (BRBs) have been spread widely, especially in high seismic hazard zones due to their excellent energy absorption capacity. BRBs are composed of a main load-carrying steel core restrained with other elements mostly made of concrete and steel casing to preserve it from buckling. Although BRBs provide excellent cyclic behavior, a problem is with their heaviness, which leads to difficulties such as installation and transportation. This study presents a numerical and experimental investigation on a BRB with a new proposed restraining system composed of concrete panels confined with partially carbon fiber reinforced polymer (CFRP) strips to reduce the weight of the... 

    Experimental comparison of cyclic behavior of RC columns strengthened with TRC and FRP

    , Article Bulletin of Earthquake Engineering ; Volume 19, Issue 7 , 2021 , Pages 2941-2970 ; 1570761X (ISSN) Azadvar, N ; Zargaran, M ; Rahimzadeh Rofooei, F ; Attari, N. K. A ; Sharif University of Technology
    Springer Science and Business Media B.V  2021
    Abstract
    Seven half-scale reinforced concrete (RC) columns with supporting beam were experimentally studied under combined axial and lateral cyclic loading. The specimens were categorized in two groups based on reinforcement ratios. Three specimens were strengthened with carbon fiber reinforced polymer (CFRP) and glass fiber reinforced polymer (GFRP) sheets. Other specimens were strengthened using a high strength mortar reinforced with textile mesh (textile reinforced concrete (TRC)). Strengthening of specimens were carried out using a vertical layer and a horizontal layer of FRP sheet or two vertical and two horizontal layers of textile meshes for TRC specimens. Since the weight of each layer of... 

    Enhancement of bond characteristics of ribbed-surface GFRP bars with concrete by using carbon fiber mat anchorage

    , Article Construction and Building Materials ; Volume 134 , 2017 , Pages 507-519 ; 09500618 (ISSN) Ashrafi, H ; Bazli, M ; Vatani Oskouei, A. V ; Sharif University of Technology
    Abstract
    The bond of fiber-reinforced polymer (FRP) reinforcement is expected to be more sensitive to the strength and geometry of the ribs than conventional steel reinforcement. In this study, the effect of carbon fiber mat anchorage on the pullout behavior of glass fiber-reinforced polymer (GFRP) bars embedded in normal concrete is studied. The studied parameters were the compressive strength of the concrete (16 MPa, 24 MPa, and 37 MPa), and, the length and diameter of the anchorage. In total, 15 variables were studied. Ribbed GFRP bars with 10 mm nominal diameter and 80 mm embedment length, ld, (which is 8 times the bar diameter) were considered. Based on the results for concretes with the... 

    Flexural Behavior of Concrete Beams Strengthened by Classical Method and Comparing The Results with Strengthening by FRP

    , M.Sc. Thesis Sharif University of Technology Moradkhani Pour, Behnam (Author) ; Khaloo, Alireza (Supervisor)
    Abstract
    Retrofitting and strengthening existing structures is one of the most important concepts of structural and earthquake engineering. Strengthening of structures could be due to changes in application and applied load, errors in calculation, mistakes in construction, weakness of old codes, structural height increases and changes in environmental conditions. Different methods for increasing the flexural strength and ductility of reinforced concrete beams, as one of the major structural components, have been presented. This research presents an experimental study on the strengthening of reinforced concrete beams by reinforced concrete jackets (classical method) and Fiber Reinforced Polymer (FRP)... 

    Meta Reinforcement Learning for Domain Generalization

    , M.Sc. Thesis Sharif University of Technology Riyahi Madvar, Maryam (Author) ; Rohban, Mohammad Hossein (Supervisor)
    Abstract
    Deep reinforcement learning has achieved better cumulative rewards than humans in many environments like Atari. One drawback of these methods is their data inefficiency which makes training time-consuming, and in some cases having this amount of data is infeasible. Meta reinforcement learning can use past experiences to enable agents to adapt to new tasks faster and makes neural networks to train in a short amount of time.One of the methods in meta reinforcement learning is inferring tasks which helps exploitation policy to have good performance in new tasks. There’s a need to improve exploration policy as well as exploitation policy by gaining informative transitions about the new task.... 

    Optimising operational cost of a smart energy hub, the reinforcement learning approach

    , Article International Journal of Parallel, Emergent and Distributed Systems ; 2014 ; ISSN: 17445760 Rayati, M ; Sheikhi, A ; Ranjbar, A. M ; Sharif University of Technology
    Abstract
    The concept of smart grid (SG) has been introduced to improve the operation of the power systems. In modern structures of power systems, different reasons prompt researchers to suggest integrated analysis of multi-carrier energy systems. Considering synergy effects of the couplings between different energy carriers and utilising intelligent technologies for monitoring and controlling of energy flow may change energy system management in the future. In this paper, we propose a new solution which is entitled ‘smart energy hub’ (SEH) that models a multi-carrier energy system in a SG. SEH solutions allow homeowners to manage their energy consumption to reduce their electricity and gas bill. We... 

    Wind farm optimal connection to transmission systems considering network reinforcement using cost-reliability analysis

    , Article IET Renewable Power Generation ; Volume 7, Issue 6 , 2013 , Pages 603-613 ; 17521416 (ISSN) Taherkhani, M ; Hosseini, S. H ; Sharif University of Technology
    2013
    Abstract
    In this study, a novel network reinforcement model incorporating optimal wind farms (WFs) integration to power systems is proposed. Based on the reinforcement model, new transmission lines are added to the network for eliminating the transmission network congestion. In addition, a methodology for determining the WFs optimal capacities, the economical WF lines transfer rates and the appropriate reinforcement plan, whereas maximising the total benefit using cost-reliability analysis is presented. In this way, the objective of the proposed optimisation problem has been divided into a master problem and two subproblems. Benders decomposition is employed to connect the master and subproblems of... 

    Flexural behaviour of small steel fibre reinforced concrete slabs

    , Article Cement and Concrete Composites ; Volume 27, Issue 1 , 2005 , Pages 141-149 ; 09589465 (ISSN) Khaloo, A. R ; Afshari, M ; Sharif University of Technology
    2005
    Abstract
    Influence of length and volumetric percentage of steel fibres on energy absorption of concrete slabs with various concrete strengths is investigated by testing 28 small steel fibre reinforced concrete (SFRC) slabs under flexure. Variables included; fibre length, volumetric percentage of fibres and concrete strength. Test results indicate that generally longer fibres and higher fibre content provide higher energy absorption. The results are compared with a theoretical prediction based on random distribution of fibres. The theoretical method resulted in higher energy absorption than that obtained in experiment. A design method according to allowable deflection is proposed for SFRC slabs within... 

    Effect of SiC on microstructural features and compressive properties of aluminum foam [electronic resource]

    , Article Scientia Iranica ; 2014 Malekjafarian, M ; Sadrnezhaad, S.K ; Sharif Univercity of Technology
    Abstract
    Composite aluminum-SiC foam was manufactured by injection of air and addition of reinforcement particles into the liquid aluminum. Microstructure and mechanical properties of the Al/SiC foams were investigated by scanning electron microscopy and compression tests. Results showed that both the cell size and the wall thickness augmented with increasing of the SiC reinforcement particles; while SiC particles resulted in the reduction of the plateau border length. With more SiC particles, plateau stress became larger; but maximum plateau strain became smaller. The stress-strain curves exhibited serrations in the plateau region due to addition of the SiC particles