Search for: valves--mechanical
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    Numerical investigation on the effect of the size and number of stages on the tesla microvalve efficiency

    , Article Journal of Mechanics ; Volume 29, Issue 3 , 2012 , Pages 527-534 ; 17277191 (ISSN) Mohammadzadeh, K ; Kolahdouz, E. M ; Shirani, E ; Shafii, M. B ; Sharif University of Technology
    In the present study, the effect of the number of stages of Tesla Micro-Valve (TMV), as well as the dependency of Reynolds number, Re, on the valve performance has been analyzed. For this purpose, different layouts include one to four-stage with different sizes are investigated numerically. The main criterion for evaluation of valves performance is diodicity, Di. Unsteady and steady flow in valve have been simulated and compared. It is shown that although there are some difference but the trend is similar for both responses. Finally, 2-D and steady state computations of the fluid flow have been utilized that reveal a strong dependence of Di on Re and pressure drop, ΔP. The results showed... 

    A new model for dynamic analysis of side mounted diffuser valve micropumps

    , Article 8th Biennial ASME Conference on Engineering Systems Design and Analysis, ESDA2006, Torino, 4 July 2006 through 7 July 2006 ; Volume 2006 , 2006 ; 0791837793 (ISBN); 9780791837795 (ISBN) Ahmadian, M. T ; Mehrabian, A ; Sharif University of Technology
    American Society of Mechanical Engineers  2006
    Valveless micropumps are widely used due to simple structure, durability and low maintenance. Understanding the fluid-membrane interaction and performance criteria is still a challenging problem for the scientists. In this work, a new model for side mounted valve micropumps is developed to obtain dynamic response of micropump with respect to piezoelectric actuation. The parameters of this model are obtained in terms of actuation frequency and geometrical dimensions of the micropump. Balancing elastic, inertial and damping forces result in the governing equation of the micropump system model. Analytical studies for the bottom mounted valve micropump indicate pump flux is independent of the... 

    Analysis and optimized design of a packaged liquid chiller (part I -Analytical modelling)

    , Article 2005 ASME Summer Heat Transfer Conference, HT 2005, San Francisco, CA, 17 July 2005 through 22 July 2005 ; Volume 4 , 2005 , Pages 461-466 ; 0791847314 (ISBN); 9780791847312 (ISBN) Heydari, A ; Kargar, S ; Sharif University of Technology
    The purpose of this work is to develop a physical simulation model for the purpose of studying the effect of various design parameters on the performance of a packaged liquid chiller. A computer model which simulates the steady-state cyclic performance of a vapor compression chiller is developed for the purpose of performing detailed physical design analysis of actual industrial chillers. The model can be used for optimizing design and for detailed energy efficiency analysis of packaged liquid chillers. The simulation model takes into account presence of all chiller components such as compressor, shell-and-tube condenser and evaporator heat exchangers, thermostatic expansion valve and... 

    Valve fault diagnosis in internal combustion engines using acoustic emission and artificial neural network

    , Article Shock and Vibration ; Vol. 2014 , 2014 ; ISSN: 10709622 Jafari, S. M ; Mehdigholi, H ; Behzad, M ; Sharif University of Technology
    This paper presents the potential of acoustic emission (AE) technique to detect valve damage in internal combustion engines. The cylinder head of a spark-ignited engine was used as the experimental setup. The effect of three types of valve damage (clearance, semicrack, and notch) on valve leakage was investigated. The experimental results showed that AE is an effective method to detect damage and the type of damagein valves in both of the time and frequency domains. An artificial neural network was trained based on time domain analysis using AE parametric features (AErms, count, absolute AE energy, maximum signal amplitude, and average signal level). The network consisted of five, six, and... 

    Rotary magnetohydrodynamic micropump based on slug trapping valve

    , Article Journal of Microelectromechanical Systems ; Volume 20, Issue 1 , December , 2011 , Pages 260-269 ; 10577157 (ISSN) Moghadam, M. E ; Shafii, M. B ; Sharif University of Technology
    A novel rotary magnetohydrodynamic (MHD) (RMHD) micropump is presented in this paper in order to both benefit exclusive advantages from the MHD micropumps and eliminate the current obstacles in their implementation. Lorentz force, which is the actuation mechanism in RMHD, is used to propel a mercury slug in a circular microchannel in order to suck the working fluid from the inlet and pump it to the outlet. This idea is integrated with a valve which prevents the working fluid from passing through, while allowing the mercury slug to pass, during each pumping loop. The performance of a fabricated RMHD is evaluated, considering parameters such as pressure difference, running duration, electric... 

    A Second-Order Sliding Mode Observer for Fault Detection and Isolation of Turbocharged SI Engines

    , Article IEEE Transactions on Industrial Electronics ; Volume 62, Issue 12 , June , 2015 , Pages 7795-7803 ; 02780046 (ISSN) Salehi, R ; Vossoughi, G ; Alasty, A ; Sharif University of Technology
    Institute of Electrical and Electronics Engineers Inc  2015
    This paper proposes a novel method for detection and isolation of wastegate (WG) faults in a turbocharged (TC) gasoline engine. This paper starts with a fault effect analysis on the WG faults, including WG stuck open and stuck closed, which is an early step in a detection strategy design. Then, a second-order sliding-mode observer (SOSMO) is proposed to capture the exhaust manifold dynamics. The observer uses experimentally validated engine models to estimate the WG position and a virtual force. The virtual force represents the external disturbances that disrupt the WG operation and enables the proposed SOSMO to estimate the WG position robust to the faults. Using this force, a detection and... 

    Inhomogeneous swelling behavior of temperature sensitive PNIPAM hydrogels in micro-valves: Analytical and numerical study

    , Article Smart Materials and Structures ; Volume 24, Issue 4 , February , 2015 ; 09641726 (ISSN) Mazaheri, H ; Baghani, M ; Naghdabadi, R ; Sohrabpour, S ; Sharif University of Technology
    Institute of Physics Publishing  2015
    In this work, inhomogeneous swelling of the temperature-sensitive PNIPAM hydrogel is investigated with application to micro-valves. In this regard, a modified model is considered, and an analytical solution of the inhomogeneous swelling of a hydrogel jacket coated on a rigid pillar is performed, which is valuable for the conceptual design of the micro-valve. Then, finite element implementation of the modified model is carried out, and its validity is verified by both the analytical and experimental results. Thereafter, thermo-mechanical behavior of the micro-valve is investigated considering the coupling between the inhomogeneous swelling of the jacket and contact problems due to the... 

    Simulation and experimental validation of flow-current characteristic of a sample hydraulic servo valve

    , Article Scientia Iranica ; Volume 17, Issue 5 B , 2010 , Pages 327-336 ; 10263098 (ISSN) Sadooghi, M. S ; Seifi, R ; Saadat Foumani, M ; Sharif University of Technology
    This paper presents a novel model to simulate the flow-current characteristic curve of an electro-hydraulic servo valve in steady state condition. This characteristic curve has three major zones: dead zone, linear zone and saturation zone. By using the presented approach, we can simulate the behavior of all types of valves including under lapped, critical center (zero lapped) and over lapped valves. A hydraulic tester has been designed and constructed for validation of the results. It can test the performance of flow-current and some other properties of the valve. Comparison of experimental and simulated curves describes that the model has an acceptable accuracy in determining the four... 

    Investigation of switching time and pressure head effects on hydro magnetic micro-pump and flow controller

    , Article 2008 Proceedings of the ASME Fluids Engineering Division Summer Conference, FEDSM 2008, 10 August 2008 through 14 August 2008, Jacksonville, FL ; Volume 2 , 2009 , Pages 463-470 ; 9780791848418 (ISBN) Esmaily Moghadam, M ; Shafii, M. B ; Fluids Engineering Division, ASME ; Sharif University of Technology
    The significant importance of micro-scaled devices in medicine, lab-on-a-chip, and etc resulted in a vast variety of researches. The idea behind the novel hydro magnetic micro-pump and flow controller is that ferromagnetic particles, mixed and dispersed in a carrier fluid, can be accumulated and retained at specific sites to form pistons in a micro-tube using some external magnetic field sources along the micro-tube. This external magnetic field is related to some solenoids, which are turned on and off alternatively. Depending upon dragging speed of these pistons, which itself is a function of switching time, this device can be used to either increase (pumping) or decrease (valving) the flow... 

    Design of a hybrid controller for pressure swing adsorption processes

    , Article IEEE Transactions on Control Systems Technology ; 2018 ; 10636536 (ISSN) Fakhroleslam, M ; Bozorgmehri Boozarjomehry, R ; Fatemi, S ; De Santis, E ; Di Benedetto, M. D ; Pola, G ; Sharif University of Technology
    Institute of Electrical and Electronics Engineers Inc  2018
    The aim of this paper is to synthesize a hybrid controller for pressure swing adsorption (PSA) processes. Since the process is described by a set of partial differential algebraic equations, first a local reduced-order model (LROM) for the process is developed and is formalized as a hybrid system. A hybrid controller is designed for purity control of the process in the presence of external disturbances by determining the maximal safe set of the LROM. A hybrid backward reachability analysis is performed for this purpose. Considering a realistic scenario for PSA processes where the states are not available and the number of measurement sensors is very limited, the desired states are estimated... 

    An experimental platform for macro-scale fluidic medium molecular communication

    , Article IEEE Transactions on Molecular, Biological, and Multi-Scale Communications ; 2020 Khaloopour, L ; Nasiri Kenari, M ; Rouzegar, S. V ; Azizi, A ; Hosseinian, A ; Farahnak Ghazani, M ; Bagheri, N ; Mirmohseni, M ; Arjmandi, H ; Mosayebi, R ; Sharif University of Technology
    Institute of Electrical and Electronics Engineers Inc  2020
    The macro-scale molecular communication (MC) recently received considerable attention because of its potential applications. Since most of the experimental research in MC focuses on the micro-scale cases, it is necessary to study and implement experiments to investigate the concept’s feasibility as well as to validate the models and parameters. In this paper, a macro-scale flow-based MC platform with fluidic medium is developed, in a semi-cylindrical channel with laminar flow condition. The transmission medium we consider is water in the plexi pipe, a transmitter releases Hydrochloric acid molecules into this pipe and a chemical sensor is used as the receiver. We propose an LTI model for the... 

    Thermo-hydrodynamic modeling of a single bubble nozzle-diffuser phase change micropump

    , Article 6th International Conference on Nanochannels, Microchannels, and Minichannels, ICNMM2008, Darmstadt, 23 June 2008 through 25 June 2008 ; Issue PART B , June , 2008 , Pages 1237-1243 ; 0791848345 (ISBN); 9780791848340 (ISBN) Saidi, M. S ; Saeedi, M. H ; Pirouzpanah, S ; Nikparto, A ; ASME ; Sharif University of Technology
    Nowadays, the potential of phase change process in liquids at micro scale attracts the scientists to fabricate this type of micropumps. Such micropumps have widely found applications in industrial and medical equipments such as recent printers. Not using mechanical parts such as valves, and having small sizes and high and controllable mass flow rates are the advantages of these micropumps. In the nozzle diffuser phase change micropump a heat pulse generates a bubble in a chamber; therefore, the pressure pulse which is generated by the bubble, causes the bubble to expand suddenly with high rate, then the pressure of bubble reduces to the vapor pressure and causes negative rate of expansion to... 

    Semiactive viscous tensile bracing system

    , Article Journal of Structural Engineering ; Volume 135, Issue 4 , 2009 , Pages 425-436 ; 07339445 (ISSN) Rahani, E.K ; Bakhshi, A ; Golafshani, A.A ; Sharif University of Technology
    Structural control using energy dissipater devices is emerging as a heavily researched strategy in earthquake engineering. Among several control systems, semiactive control is usually possible and efficient. In this research, a semiactive energy dissipating bracing system based on a viscous damper is proposed. In the conventional bracing systems, it is assumed that the braces can buckle under compression. Therefore, a semiactive on-off brace strategy is implemented to improve the conventional brace performance. Further, an energy absorbing mechanism is implemented. In the proposed system, the buckling of the member is prevented by implementing a one-way valve device. The permanent story... 

    Hydromagnetic micropump and flow controller. part a: experiments with nickel particles added to the water

    , Article Experimental Thermal and Fluid Science ; Volume 33, Issue 6 , 2009 , Pages 1021-1028 ; 08941777 (ISSN) Esmaily Moghadam, M ; Shafii, M. B ; Alavi Dehkordi, E ; Sharif University of Technology
    The novel idea of the Hydromagnetic Micropump and Flow Controller (HMFC) is used in this paper to construct a laboratory setup capable of bidirectional pumping and controlling the flow in microtubes. A laboratory setup, which contains no moving parts, is integrated with a pressure-driven flow setup to make the presented HMFC device. The device operation is based on controllable motion of magnetic particles, added to the carrier fluid, caused by the magnetic field, produced by solenoids located just next to the microtube. The magnitude of these forces is proportional to the strength and gradient of magnetic field which, in turn, is related to the electrical current and arrangement of the...