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    Designing, modeling and wrench feasible workspace analysis of a 3D cable suspended robot for heavy loads handling applications

    , Article 39th International Symposium on Robotics, ISR 2008, Seoul, 15 October 2008 through 17 October 2008 ; 2008 , Pages 934-939 Hamedi, J ; Zohoor, H ; Sharif University of Technology
    The objective of this paper is designing, modeling and wrench feasible workspace analysis of a 3D cable suspended robot as IRPM (Incompletely Restrained Positioning Mechanism). This type of robots supports a load platform in space by less than or equal to six spatially arranged cables. We use the model of 6 cables spanned in the same manner as a Stewart parallel mechanism. This mechanism is suitable for the accurate positioning of heavy loads. Concentrating on the operations of heavy loads handling, studying the workspace and ways of increasing it is of high importance. Several workspaces exist amongst which the constant and total orientation statically reachable combined and wrench feasible... 

    Automatic droop control for a low voltage DC microgrid

    , Article IET Generation, Transmission and Distribution ; Volume 10, Issue 1 , 2016 , Pages 41-47 ; 17518687 (ISSN) Khorsandi, A ; Ashourloo, M ; Mokhtari, H ; Iravani, R ; Sharif University of Technology
    Institution of Engineering and Technology 
    A DC microgrid (DC-MG) provides an effective mean to integrate various sources, energy storage units and loads at a common dc-side. The droop-based, in the context of a decentralised control, has been widely used for the control of the DC-MG. However, the conventional droop control cannot achieve both accurate current sharing and desired voltage regulation. This study proposes a new adaptive control method for DC-MG applications which satisfies both accurate current sharing and acceptable voltage regulation depending on the loading condition. At light load conditions where the output currents of the DG units are well below the maximum limits, the accuracy of the current sharing process is... 

    Optimal tension distribution and stiffness control of a spatial under-constrained cable suspended robot

    , Article Proceedings of the IASTED International Conference on Modelling, Identification and Control, 15 February 2010 through 17 February 2010 ; February , 2010 , Pages 270-275 ; 10258973 (ISSN) Hamedi, J ; Zohoor, H ; Sharif University of Technology
    In under-constrained spatial cable suspended robots, maximum number of cables are equivalent to the number of degree of freedom, therefore the equations of kinetostatic have unique solutions and invention of positive cable tensile forces in these robots must come into being by redundant cables, springs or by Moving Platform (MP) weight. In this research, MP weight is considered to create tension in cables so both increasing workspace volume and decreasing possibility of cable encounter with together can be created because of using less cables. The range of MP weight to generate tension in cables is calculated by using Interval method, optimum weight is selected and then optimal tension... 

    Fabrication of porous NiTi-shape memory alloy objects by partially hydrided titanium powder for biomedical applications

    , Article Materials and Design ; Volume 30, Issue 10 , 2009 , Pages 4483-4487 ; 02641275 (ISSN) Sadrnezhaad, S. K ; Hosseini, S. A ; Sharif University of Technology
    Porous NiTi-shape memory alloy (SMA) is a promising biomaterial with desirable mechanical property and appropriate biocompatibility for human implant manufacturing. In this research, porous NiTi-SMAs have been successfully produced by using thermohydrogen process (THP). This process has capability of production of homogenous structures, appropriate pore-size distributions and short sintering times. The THP-SMA samples produced in this research have a low Young's modulus (19.8 GPa) and a high tensile strength of 255 MPa. These properties are close to those of the natural bone and can meet the mechanical property demands of the hard-tissue implants for heavy load-bearing applications. The...