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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) ; Seifi, R ; Saadat Foumani, M ; Sharif University of Technology
2010
Abstract
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) ; Shafii, M. B ; Fluids Engineering Division, ASME ; Sharif University of Technology
2009
Abstract
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...
Detection and Compensation of Oscillation in Control Loops: The Multiplicity of Oscillation Causes
, M.Sc. Thesis Sharif University of Technology ; Tavazoei, Mohammad Saleh (Supervisor)
Abstract
In this research, oscillation in control loop caused by control valve stiction, external harmonic disturbance, poor controller tuning or their combination, is recognized and compensated. In control valve stiction based study, flaws in one of the important modeling methods are described and some modifications are proposed. For diagnosis of oscillation source, signal is decomposed to its fundamental modes and oscillation in each mode is investigated. Then, from the existence of harmonics in decomposed modes, stiction is diagnosed. Also, relation between peak differences in autocorrelation functions of other modes, results to external harmonic disturbance or poor controller tuning as...
Performance of valveless diffuser micropumps under harmonic piezoelectric actuation
, 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) ; Saidi, M. H ; Mehrabian, A ; Bazargan, M ; Kenarsari, S. D ; Sharif University of Technology
American Society of Mechanical Engineers
2006
Abstract
Valveless piezoelectric micropumps are in wide practical use due to their ability to conduct particles with absence of interior moving mechanical parts. The objective of this paper is to obtain the fluid flow response to actuation frequency of a passive diffuser valve under harmonic pressures. In this regards a 2D model of a micropump valves and chambers is analyzed. The analysis is performed for 10Kpa back pressure on micropump chamber and actuation frequencies within the range of 1Hz to 10 KHz. Results show the highest velocity in the direction of diffuser axis occurs at the narrow diffuser neck while flow direction reverses every half period. For low frequencies, a parabolic velocity...
Design of a hybrid controller for pressure swing adsorption processes
, Article IEEE Transactions on Control Systems Technology ; 2018 ; 10636536 (ISSN) ; 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
Abstract
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...
Flexibility Analysis Aortic Valve under Mineral
, M.Sc. Thesis Sharif University of Technology ; Ahmadian, Mohammad Taghi (Supervisor) ; Firoozbakhsh, Keykhosrow (Supervisor)
Abstract
In humans, the heart is roughly the size of a large fist and weighs between about 280 to 340 grams in men and 230 to 280 grams in women. Your body has about 5.6 liters of blood. The human heart is an organ that pumps blood throughout the body via the circulatory system, supplying oxygen and nutrients to the tissues and removing carbon dioxide and other wastes. Any damage to the heart, will affect on the other organs. They are four valves within the heart, in which aortic valve is the most important and crucial part of the heart. Calcium sediment on aortic valve leaflets causes reduction in the flexibility of the leaflets, one of the most common heart diseases. In this study, the flexibility...
Modeling and Dynamic Analysis of Anti-Lock Braking System Modulator
, M.Sc. Thesis Sharif University of Technology ; Behzad, Mahdi (Supervisor)
Abstract
Anti-lock brakes car as one of the most fundamental and vehicle stability control system is considered. Solenoid valves, one-way valves, Accumulator, damper orifices and other components is a crucial role in the anti-lock system performance, so that the performance of the system and thus affect the dynamic performance of the vehicle. This is the most important part of the anti-lock brake System and These components are all new brake system.In this study a complete modeling of hydraulic control unit and obtain sufficient data to model the dynamic behavior of the hydraulic control unit to be seen. operators working in higher frequencies are weak and virtually reached saturation and efficient...
Investigation of the Effects of Variable Valve Timing and Lift on Knock Limits of Spark Ignited Gasoline Engine
, M.Sc. Thesis Sharif University of Technology ; Saeidi, Mohammad Hasan (Supervisor) ; Hosseini, Vahid (Supervisor)
Abstract
Knock is an abnormal phenomena in combustion engines and one the main limiter elements in increasing engine efficiency. From years ago, recognition and elimination of this phenomenon had studied by investigators and various approaches to anticipation had presented. One of the newest methods is using of property variety in air and fuel mixture with using technologies like Variable Valve Timing (VVT) system.
The purpose of this work is development a simple model in basis physics of 3 zone, homogeneous, ignition combustion with a partial kinetics model that this model can predict the knock phenomenon onset with good precision for various qualities of mixture. This study survey effect of...
The purpose of this work is development a simple model in basis physics of 3 zone, homogeneous, ignition combustion with a partial kinetics model that this model can predict the knock phenomenon onset with good precision for various qualities of mixture. This study survey effect of...
Design of Steam Turbine Control Valves Seat on Site Machinning Robot
, M.Sc. Thesis Sharif University of Technology ; Durali, Mohammad (Supervisor)
Abstract
Designing a part of an on site repair system for refurbishing steam turbine high pressure control valve has been done in this project. The main role of this control valve is to control the input flow to the turbine in different working condition . However, due to high temperature and pressure, the seat is exposed to erosion. R epairing this part in workshop requires great amount of time and cost, because the valve is a part of the turbine body and must be cut and rewelded to the turbine body. S o using an on-site repair method is highly needed. In addition, due to the limited visibility and access to the valve seat, and accurate...
Effects of Blood Pressure on Venous Tortuosity and Valves
, M.Sc. Thesis Sharif University of Technology ; Fallah Rajabzadeh, Famida (Supervisor)
Abstract
Blood vessels are subjected to complex mechanical loads, including internal pressure, external pressure, axial stress due to connection to tissues, and the twist caused by movement of the body. The veins and venous valves, which are responsible for returning blood to the heart, become bent and twisted (tortuosity) for various reasons. This venous tortuosity causes valve insufficiency and changes the hemodynamic pattern of blood flow and varicose veins. Studies show that more than a third of old people suffer from varicose veins. These injuries have made it important to study the physical mechanism of venous tortuosity and the function of venous valves.The purpose of this study is to...
Design and Developing the Production Know-How of Large Servo-Hydraulic Valves
, M.Sc. Thesis Sharif University of Technology ; Durali, Mohammad (Supervisor)
Abstract
The focus of this project was on gaining the knowledge of design characteristics and manufacturing of a hydraulic servo valve. Hence, in the first stage, the model of the valve was considered. After investigating the important parameters which influence the performance of the valve, the effect of each parameter on the valve's efficiency was examined. One of the most important characteristics of the valve is the amount of lapping between the spool and sleeve. Numerical analysis was done and all the characteristic curves were elicited. Equations governing the dynamics of the plant including a servo valve, servo actuator and dynamic model of the turbine and waterway were presented. Then the...
A novel revolving piston minipump
, Article Sensors and Actuators, B: Chemical ; Volume 218 , October , 2015 , Pages 237-244 ; 09254005 (ISSN) ; Shafii, M. B ; Moosavi, A ; Amiri Hezave, H ; Sharif University of Technology
Elsevier
2015
Abstract
In this study, a novel prototype high-efficiency miniature pump that uses magnetic properties of a ferrofluid in both pumping and valving mechanisms is presented. The minichannel consisting of a cylindrical pumping chamber, a check valve, an inlet and an outlet, comprises six bonded layers of PMMA. A cylindrical permanent magnet that is placed inside the chamber and is externally actuated by a motorized off-center permanent magnet, functions as a revolving piston which sweeps the perimeter of the cylinder. Ferrofluid is used to cover the gaps between the magnetic piston and the channel walls, also serves as a separating plug between the inlet and the outlet of the chamber preventing...
Diffuser miniature pump with an extra ferrofluidic valve
, Article Microfluidics and Nanofluidics ; Volume 19, Issue 5 , November , 2015 , Pages 1235-1244 ; 16134982 (ISSN) ; Shafii, M. B ; Moosavi, A ; Sharif University of Technology
Springer Verlag
2015
Abstract
This paper presents the prototype design and fabrication of a magnetically actuated miniature pump that utilizes self-sealing capability of ferrofluid-covered permanent magnets in both pumping and valving mechanisms. The valving action is performed by employing one active valve along with two nozzle/diffuser elements. Two cylindrical permanent magnets are placed inside the flat-wall channels: One magnet acts as the active valve and the other one serves as a reciprocating piston actuating the working fluid. In order to seal the gaps between the channel walls and the permanent magnet of the valve/piston, ferrofluid is used to cover the surfaces of both magnets. The valve and the piston are...
Analytical relations for long-droplet breakup in asymmetric T junctions
, Article Physical Review E - Statistical, Nonlinear, and Soft Matter Physics ; Volume 91, Issue 5 , May , 2015 ; 15393755 (ISSN) ; Moosavi, A ; Hannani, S. K ; Sharif University of Technology
American Physical Society
2015
Abstract
We develop accurate analytical relations for the droplet volume ratio, droplet length during breakup process, and pressure drop of asymmetric T junctions with a valve in each of the branches for producing unequal-sized droplets. An important advantage of this system is that after manufacturing the system, the size of the generated droplets can be changed simply by adjusting the valves. The results indicate that if the valve ratio is smaller than 0.65, the system enters a nonbreakup regime. Also the pressure drop does not depend on the time and decreases by increasing the valve ratio, namely, opening the degree of valve 1 to valve 2. In addition, the results reveal that by decreasing...
Evaluation of a novel extra-cardiac Fontan procedure with implantation of a biocompatible membrane
, Article IRBM ; Volume 36, Issue 5 , 2015 , Pages 287-292 ; 19590318 (ISSN) ; Firoozabadi, B ; Saidi, M. S ; Monjezi, M ; Navabi Shirazi, M. A ; Malakan Rad, E ; Sharif University of Technology
Elsevier Masson SAS
2015
Abstract
Fontan operation is a final palliative surgical treatment for patients with a single ventricle (SV) physiology. One of the common disadvantages of Fontan operation is to generate a non-pulsatile flow instead of the normal pulsatile flow produced by contraction of the ventricle. Theoretically, in SV patients, maintaining the antegrade flow through pulmonary valve can produce flow pulsatility in the right and left pulmonary arteries. However, it not only increases the energy loss in the Fontan of total cavopulmonary pathway (TCPC), but also imposes an extra load on pulmonary arteries as well as the ventricle. In this study, the potential capability of pulmonary valve of the patient that can be...
Using an all-speed method to predict high frequency pressure spikes of water hammer with column separation
, Article 13th International Energy Conversion Engineering Conference, IECEC 2015, 27 July 2015 through 29 July 2015 ; July , 2015 ; 9781624103766 (ISBN) ; Beige, A. A ; Schneider, G. E ; Sharif University of Technology
American Institute of Aeronautics and Astronautics Inc, AIAA
2015
Abstract
To extend a procedure to ensure the safe operation of a water reactor, we develop a numerical method to compute the high frequency pressure spikes of water hammer with liquid column separation in pipes. In this regard, we first extend a finite-volume all-speed method to solve the full one-dimensional Navier-Stokes equations. This method is capable of simulating gas and liquid phases as well as the vapor-liquid one. On the other hand, the current extended method should be capable of capturing high frequency pressure spikes, which are formed due to water hammer and column separation in pipes. The existence of such high frequency spikes has been recently reported experimentally by other...
Profit-based unit commitment of integrated CHP-thermal-heat only units in energy and spinning reserve markets with considerations for environmental CO2 emission cost and valve-point effects
, Article Energy ; Volume 133 , 2017 , Pages 621-635 ; 03605442 (ISSN) ; Ardehali, M. M ; Sharif University of Technology
Elsevier Ltd
2017
Abstract
For the purposes of lowering environmental emission cost and increasing economic profit, energy efficient combined heat and power (CHP) units can be integrated with conventional separate heat and power production units to meet heat and power demands. The goal of this study is to develop and examine a novel heuristic and deterministic optimization algorithm for solving the profit-based unit commitment (PBUC) problem for a generation company with integrated CHP-thermal-heat only system for (i) satisfying demands for heat and power, (ii) selling spinning reserve for power, (iii) reducing environmental CO2 emission cost, and (iv) accounting for valve-point effects for steam turbines. For...
Design and fabrication of a centrifugal microfluidic disc including septum valve for measuring hemoglobin A1c in human whole blood using immunoturbidimetry method
, Article Talanta ; Volume 190 , 2018 , Pages 134-139 ; 00399140 (ISSN) ; Saadatmand, M ; Bakhtiari, M. R ; Eghbal, M ; Sharif University of Technology
Elsevier B.V
2018
Abstract
Diabetes mellitus is a global endemic with a rapidly increasing prevalence in both developing and developed countries. Recently, hemoglobin A1c has been recommended by the American Diabetes Associations as a possible substitute for fasting blood glucose for the diagnosis of diabetes, because it is an indicator of long-term glycemic control. Also, centrifugal microfluidic systems have good potential for use in the point of care testing systems. In this study, a centrifugal microfluidic disc was designed and manufactured to measure hemoglobin A1c in whole blood using an immunoturbidimetry based method. Also, a new passive valve, named septum valve, was presented to precisely control the entry...
Thermal performance assessment of an evaporative condenser-based combined heat pump and humidification-dehumidification desalination system
, Article Desalination ; Volume 496 , 2020 ; Shafii, M. B ; Sharif University of Technology
Elsevier B.V
2020
Abstract
A new design for heat pump integrated humidification-dehumidification (HDH-HP) desalination cycles was proposed in the current experimental study. An evaporative condenser was designed and fabricated instead of a separate humidifier, heater, and air/water-cooled condensers find in previous HDH-HP systems. Meanwhile, the air dehumidification process in this work directly occurred inside the heat pump evaporator. The effect of several operating parameters such as ambient wet-bulb temperature, spraying saline water and airflow rates, compressor speed, superheat, and evaporator saturation temperature control modes of the electronic expansion valve (EEV) on freshwater production and GOR were...
An experimental platform for macro-scale fluidic medium molecular communication
, Article IEEE Transactions on Molecular, Biological, and Multi-Scale Communications ; 2020 ; 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
Abstract
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...