Search for: prototypes
0.007 seconds
Total 60 records

    Quick deployment of open-source hardware and software for a dual-channel biosignal recorder

    , Article 2013 IEEE International Conference on Smart Instrumentation, Measurement and Applications, ICSIMA 2013 ; 2013 ; 9781479908431 (ISBN) Zahedi, E ; Sharif University of Technology
    Access to a prototype during R&D can play a crucial role in early identification of the weaknesses in the design. Under circumstances that a particular commercial subsystem with the exact required specific features is unavailable, the realization of such a prototype can be delayed. In this paper, an example of rapid prototyping for a dual-channel biosignal data acquisition system based on the open-source concept is described. The selected biosignal is the finger photoplethysmogram. Except for Matlab, all other software components are open-source. The hardware design of the optical sensor utilized to record the signals is also open-source, making the system extremely affordable with the... 

    Direct laser sintering of iron-graphite powder mixture

    , Article Materials Science and Engineering A ; Volume 383, Issue 2 , 2004 , Pages 191-200 ; 09215093 (ISSN) Simchi, A ; Pohl, H ; Sharif University of Technology
    In the present work, the role of graphite addition on the laser sintering of iron powder was studied. Powder mixtures containing iron and 0.4, 0.8, 1.2, and 1.6 wt.% graphite were prepared by blending elemental powders. These powders were sintered layer-by-layer under nitrogen atmosphere using a continuous wave CO2 laser beam. A laser power of 70-225 W, scan rate of 50-600 mm s-1, scan line spacing of 0.1-0.3 mm, and layer thickness of 0.1 mm was used. It was found that the processing parameters play a key role on the densification of the iron-graphite powder mixtures. The addition of graphite enhances the densification of the iron powder and improves the surface quality of the laser... 

    Rapid design space exploration of DSP applications using programmable SOC devices - A case study

    , Article 15th Annual IEEE International ASIC/SOC Conference, ASIC/SOC 2002, 25 September 2002 through 28 September 2002 ; Volume 2002-January , 2002 , Pages 273-277 ; 10630988 (ISSN); 0780374940 (ISBN) Hashempour, M ; Sharifì, S ; Gudarzi, M ; Hessabi, S ; Sharif University of Technology
    Institute of Electrical and Electronics Engineers Inc  2002
    In this paper, we present results of our experiments in implementation of a widely used DSP primitive on a programmable SoC (System-on-a-Chip) Device. The DSP primitive is a 16-bit digital FIR filter which we implemented on Triscend E5 CSoC® family. Experimental results show that by properly breaking the DSP task into hardware and software parts, one can achieve higher throughput compared to DSP processor implementations, while having more flexibility and less time-to-design compared to full-hardware realizations. Programmable SoC device facilitates rapid design-space exploration, which we employed to optimize our mixed hardware-software architecture. We compared our filter throughput to... 

    Analyzing chor specifications by translation into FSP

    , Article Electronic Notes in Theoretical Computer Science ; Volume 255 , 2009 , Pages 159-176 ; 15710661 (ISSN) Roohi, N ; Salaun, G ; Mirian, H ; Sharif University of Technology
    A choreography specifies activities and interactions among a set of services from a global point of view. From this specification, local implementations or peers can be automatically generated. Generation of peers that precisely implement the choreography specification is not always possible: this problem is known as realizability. This paper presents an encoding of the Chor choreography calculus into the FSP process algebra. This encoding allows to: (i) validate and verify Chor specifications using the FSP toolbox (LTSA), (ii) generate peer protocols from its choreography specified in Chor, (iii) test for realizability of the Chor specification, and (iv) generate Java code from FSP for... 

    An improved methodology for design of custom-made hip prostheses to be fabricated using additive manufacturing technologies

    , Article Rapid Prototyping Journal ; Volume 18, Issue 5 , 2012 , Pages 389-400 ; 13552546 (ISSN) Rahmati, S ; Abbaszadeh, F ; Farahmand, F ; Sharif University of Technology
    Emerald  2012
    Purpose - The purpose of this paper is to present an improved methodology for design of custom-made hip prostheses, through integration of advanced image processing, computer aided design (CAD) and additive manufacturing (AM) technologies. Design/methodology/approach - The proposed methodology for design of custom-made hip prostheses is based on an independent design criterion for each of the intra-medullary and extra-medullary portions of the prosthesis. The intra-medullar part of the prosthesis is designed using a more accurate and detailed description of the 3D geometry of the femoral intra-medullary cavity, including the septum calcar ridge, so that an improved fill and fit performance... 

    Efficient multi-modal fusion on supergraph for scalable image annotation

    , Article Pattern Recognition ; Volume 48, Issue 7 , July , 2015 , Pages 2241-2253 ; 00313203 (ISSN) Amiri, S. H ; Jamzad, M ; Sharif University of Technology
    Elsevier Ltd  2015
    Different types of visual features provide multi-modal representation for images in the annotation task. Conventional graph-based image annotation methods integrate various features into a single descriptor and consider one node for each descriptor on the learning graph. However, this graph does not capture the information of individual features, making it unsuitable for propagating the labels of annotated images. In this paper, we address this issue by proposing an approach for fusing the visual features such that a specific subgraph is constructed for each visual modality and then subgraphs are connected to form a supergraph. As the size of supergraph grows linearly with the number of... 

    Rapid manufacturing

    , Article Collaborative Engineering: Theory and Practice ; 2008 , Pages 127-152 ; 9780387473192 (ISBN) Asiabanpour, B ; Mokhtar, A. R ; Houshmand, M ; Sharif University of Technology
    Springer US  2008
    This chapter defines rapid manufacturing (RM) as a technique for manufacturing solid objects by the sequential delivery of energy and/or material to specified points in space. Current practice is to control the manufacturing process by using a computer-generated mathematical model. This chapter compares the large speed and cost advantages of RM to alternative polymer or metal manufacturing techniques such as powder metallurgy manufacturing or die casting. Moreover, the RM as an application of solid freeform fabrication for direct manufacturing of goods is addressed. Unlike methods such as computer numerical control (CNC) milling, these techniques allow the fabricated parts to be of high... 

    Densification and microstructural evaluation during laser sintering of M2 high speed steel powder

    , Article Materials Science and Technology ; Volume 20, Issue 11 , 2004 , Pages 1462-1468 ; 02670836 (ISSN) Simchi, A ; Asgharzadeh, H ; Sharif University of Technology
    In the present work, the densification and microstructure of M2 high speed steel powder processed by direct laser sintering method was studied. Test specimens were produced using a 200 W continuous wave CO2 laser beam at different scan rates ranging from 50 to 175 mm s-1. The building process was performed under argon and nitrogen atmospheres in order to evaluate the role of sintering atmosphere. It was found that the sintered density strongly depends on the laser scan rate and thus on the duration time of the laser beam on the surface of the powder particles. Generally, with a decrease in the scan rate higher densification was obtained. However, formation of large cracks and delamination of... 

    On the development of direct metal laser sintering for rapid tooling

    , Article Journal of Materials Processing Technology ; Volume 141, Issue 3 , 2003 , Pages 319-328 ; 09240136 (ISSN) Simchi, A ; Petzoldt, F ; Pohl, H ; Sharif University of Technology
    An iron based powder blend has been developed for rapid tooling using a direct laser sintering process. The powder consists of a mixture of different elements including Fe, C, Cu, Mo and Ni. High sintering activities were obtained by tailoring the powder characteristics and optimizing the chemical constituents. The manufacturing of complex-shaped parts is possible at rates of 6.75 cm3/h according to CAD data. The residual porosity is less than 5 vol.%. The bending strength is around 900 MPa and the artifact hardness is 490 HV30. To further improve the service life of tools, the processed parts are sintered again in a vacuum furnace at 1260 °C for 30 min. This enables to manufacture precision... 

    Design and implementation of TSC type SVC using a new approach for electrical quantities measurement

    , Article 2001 IEEE Porto Power Tech Conference, Porto, 10 September 2001 through 13 September 2001 ; Volume 2 , 2001 , Pages 262-267 ; 0780371399 (ISBN); 9780780371392 (ISBN) Tabandeh, M ; Alavi, M. H ; Marami, M ; Dehnavi, G. R ; Sharif University of Technology
    In this paper, a compact algorithm for balancing the load and correction of power factor in three-phase three-wire system is presented. Susceptances of SVC in each phase are computed as a function of real and imaginary parts of line current. This calculation is based on unity power factor and elimination of negative sequence of currents. A laboratory prototype of Thyristor Switched Capacitor (TSC) at 380V and 45KVAR is designed and implemented. Also, a new approach for measuring active and reactive power, power factor and voltage is presented. This measuring technique is based on integration of current signal over a specific part of voltage signal period. Finally, a brief description of... 

    Design of an optimum torque actuator for augmenting lower extremity exoskeletons in biomechanical framework

    , Article 2011 IEEE International Conference on Robotics and Biomimetics, ROBIO 2011 ; 2011 , Pages 1979-1983 ; 9781457721373 (ISBN) Safavi, S ; Ghafari, A. S ; Meghdari, A ; Sharif University of Technology
    This research presents virtual prototyping and performance evaluation of a series elastic torque actuator developed for augmenting lower extremity exoskeletal systems employing biomechanical framework. For this purpose, experimental kinematical data of the lower extremity were collected for walking and backpack load carrying. Forward dynamics simulation of the movements under investigation is performed in a biomechanical framework consisting of a musculoskeletal model with ten degrees-of-freedom actuated by eighteen Hill-type musculotendon actuators per leg to perform the muscle functional analysis. Muscle torque analysis results employed for optimal design and selection of components in the... 

    Novel methodology in design of custom-made hip prosthesis

    , Article Innovative Developments in Design and Manufacturing - Advanced Research in Virtual and Rapid Prototyping, 6 October 2009 through 10 October 2009, Leiria ; 2010 , Pages 117-126 ; 9780415873079 (ISBN) Abbaszadeh, F ; Rahmati, S ; Farahmand, F ; Fatollahzadeh, R ; Sharif University of Technology
    Medical applications of rapid prototyping have an increasing trend, making the future of RP more and more promising. These applications may include design, development, and manufacture of medical devices and instrumentation, as well as implant design, anatomical modeling, surgical planning, surgical implants, and prosthesis fabrication. This paper provides a new methodology for customized hip prosthesis that could provide high accuracy of femoral canal reconstruction via 3D modeling of prosthesis stem, 3D modeling of prosthesis neck, and facilitating the communication between the designer and surgeon. Combining RP technologies and rapid tooling with this novel custom-made hip prosthesis,... 

    An overview on five approaches for translating cad data into manufacturing information

    , Article Journal of Advanced Manufacturing Systems ; Volume 8, Issue 1 , 2009 , Pages 89-114 ; 02196867 (ISSN) Asiabanpour, B ; Mokhtar, A ; Hayasi, M ; Kamrani, A ; Nasr, E. A ; Sharif University of Technology
    All Rapid Prototyping and CNC material removal processes use information which is extracted from a CAD system. There are several ways to convert CAD data into usable manufacturing information. In this paper, five methods of translating CAD data into a usable manufacturing format are explained. These five methods are data translation from CAD files in STL, DXF, STEP-NC, and IGES formats as well as a platform-dependent area method of manufacturing information in a desirable format. For each method, algorithms and details about the CAD data translation into usable manufacturing and prototyping processes formats are presented. Finally, applications of each approach and its pros and cons are... 

    Design and Prototyping of a Fast Acting Gyroscopic Actuator for Vehicle Stability Applications

    , M.Sc. Thesis Sharif University of Technology Samani, Armin (Author) ; Durali, Mohammad (Supervisor)
    Cars with high center of gravity, such as SUV-Sport Utility Vehicles- have high tendency to roll over in high speeds and rapid maneuvers. An idea formerly proposed is to use a high speed rotating disc like a gyroscope on the onset of the rollover to exert a high stabilizing moment on the vehicle, and consequently prevent rollovers. Also using two counter rotating discs with opposite nutation will prevent interference with the car other degrees of freedom. To reduce the interference of the spinning discs with the vehicle dynamics, the discs are to be brought to speed by the action of a high accelerating mechanism during the rollover process(similar to the action of an airbag). This project... 

    Design, analysis, and experimental evaluation of a novel three-fingered endoscopic large-organ grasper

    , Article Journal of Medical Devices, Transactions of the ASME ; Volume 7, Issue 2 , 2013 ; 19326181 (ISSN) Mirbagheri, A ; Farahmand, F ; Sharif University of Technology
    The currently available laparoscopic instruments are unable to manipulate and grasp the large intra-abdominal organs, such as spleen and kidney, with sufficient stability and safety. This paper describes a novel three-fingered endoscopic instrument, based on parallelogram mechanism, which can fully constrain the large organs and provide an effective grasping function. We first evaluated the efficacy of the design using a 3D model and finite element analysis. Then, a fully functional prototype was fabricated for experimental evaluations, including force propagation and pull force limitation characteristics. Finally, the instrument's capability for effective grasping was investigated on animal... 

    A novel pre-processing method to reduce noise effects in a prototype-based clustering algorithm

    , Article 2008 International Conference on Information and Knowledge Engineering, IKE 2008, Las Vegas, NV, 14 July 2008 through 17 July 2008 ; July , 2008 , Pages 587-593 ; 1601320752 (ISBN); 9781601320759 (ISBN) Taghikhaki, Z ; Minaei, B ; Masoum, A ; Sharif University of Technology
    In this paper we introduce a preprocessing method to reduce noise effects in noise prone environments. Prototype based clustering algorithms are sensitive to noise because the effect of noisy data are as same as effect of true data and this affects on calculation of clusters center and then reduces accuracy. Therefore, these algorithms can not be applied in noise-prone environments and if this is applied there, we can not trust to the results. To overcome such problems we reduce and in some cases eliminate the noisy data. Also a part of our method is applied on the source of generated data in a network. Then noisy data that the number of them is high in noisy environments are eliminated and... 

    Clad height control in laser solid freeform fabrication using a feedforward PID controller

    , Article International Journal of Advanced Manufacturing Technology ; Volume 35, Issue 3-4 , 2007 , Pages 280-292 ; 02683768 (ISSN) Fathi, A ; Khajepour, A ; Toyserkani, E ; Durali, M ; Sharif University of Technology
    In this paper, a feedforward proportional-integral-derivative (PID) controller is developed to effectively control the clad height in laser solid freeform fabrication (LSFF). The scanning velocity is selected as the input control variable and the clad height is chosen as the output. A novel knowledge-based Hammerstein model, including a linear dynamic and a nonlinear memoryless block, is developed, and its parameters are identified offline using experimental data. The architecture of the controller consists of a PID and a feedforward module, which is the inverse of the identified model. The advantage of adding a feedforward path to the PID controller is evaluated experimentally, in which the... 

    An optimum design and simulation of an innovative mobile robotic nurse unit to assist paraplegic patients

    , Article Proceedings of the IEEE International Conference on Mechatronics 2004, ICM'04, Istanbul, 3 June 2004 through 5 June 2004 ; 2004 , Pages 141-147 ; 0780385993 (ISBN) Meghdari, A ; Hosseinkhannazer, H ; Selkghafari, A ; Sharif University of Technology
    This paper describes a nursing robot system currently under development at the Center of Excellence in Design, Robotics and Automation. Our goal was to design and fabricate of a robot specifically for paraplegic patients and the design procedure led to a plan which can be employed in any hospital environment. Through the design procedure, the team members conducted a survey on the robot client's needs and disabilities which provided a unique view on mechanical design features, in addition to, performing dynamical analysis on the designed mechanisms. Dynamical Simulation of mechanisms helped us to find the best design and solutions as well as optimization of parts has resulted in a matchless... 

    Overhead-free polymorphism in network-on-chip implementation of object-oriented models

    , Article Proceedings - Design, Automation and Test in Europe Conference and Exhibition, DATE 04, Paris, 16 February 2004 through 20 February 2004 ; Volume 2 , 2004 , Pages 1380-1381 ; 0769520855 (ISBN); 9780769520858 (ISBN) Goudarzi, M ; Hessabi, S ; Mycroft, A ; Sharif University of Technology
    We unify virtual-method despatch (polymorphism implementation) and network packet-routing operations; virtual-method calls correspond to network packets, and network addresses are allocated such that routing the packet corresponds to dispatching the call. As the run-time routing structure is inherent in Network-on-Chip platforms, this unification implements polymorphism/or free.1  

    Modeling of the Mechanical Behavior of Rapid Prototyped Scaffolds Based on Their Pore Architecture and Introducing a Prototyping Method to Produce Ceramic Scaffolds

    , Ph.D. Dissertation Sharif University of Technology Amirkhani, Soodeh (Author) ; Bagheri, Reza (Supervisor) ; Baghaban Eslaminejad, Mohamad Reza (Supervisor)
    Mechanical behavior of tissue engineering scaffolds plays a key role in their biological performance; however the effect of microstructural features on mechanical behavior of such scaffolds is still under investigation. The objective of this study was to investigate the influence of pore architecture and relative density on mechanical behavior of rapid prototyped scaffolds. In this regard, scaffolds with different cubic, hexagonal and trigonal unit cells were designed. These unit cells were repeated in different arrangements in 3D space to produce different nodal connectivities. The internal dimension of pores varied from 500 to 600 μm. Plastic models of scaffolds then fabricated by 3D...