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  • Instrumentation

    Research field: Sensor & Actuator, Levitation

    Expert: َAlizade

    Phone: 02182883505

    Address:

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Application of Threadless Screw to Precise Linear Positioning

Yousef Hojjat, Mohammad Shirkosh
Journal PaperInternational Journal of Precision Engineering and Manufacturing , Volume 22 , Issue 2, 2021 February , {Pages 355-364 }

Abstract

This paper presents a mechanism for linear movement which could be called threadless screw, in which a roller is pushed toward a rotating plain shaft and rotates with it. The roller moves on a helical path when its axis is not parallel to the axis of the shaft. Therefore, the roller moves in direction of the shaft axis, just as linear movement of a nut on a screw. The lead of this mechanism is not only a function of diameter of the shaft, but also the angle between axes of the roller and the shaft which gives the possibility to change the lead continuously from very fine to very rough leads. On the other hand the accuracy of this mechanism depends on the accuracy of a plain cylindrical surface which can be fabricated very accurately compare

Formability Enhancement of Ultra-Fine Grained Pure Copper Sheets Produced by Accumulative Roll Bonding Aided by Electromagnetic Forming

Y Hojjat, G Faraji, HM Naeini
Journal Paper , , {Pages }

Abstract

Self-sensing feature of the ultrasonic nano-displacement actuator in Metglas/PMN-PT/Metglas magnetoelectric composite

M Sadeghi, Y Hojjat, M Khodaei
Journal PaperJournal of Materials Science: Materials in Electronics , Volume 31 , Issue 1, 2020 January 1, {Pages 740-751 }

Abstract

Self-sensing feature allows an actuator to be used as a sensor. Magnetoelectric (ME) composites consist of piezoelectric and magnetostrictive layers. ME composite is a proper candidate for the self-sensing feature in a wireless actuator due to its concurrent magnetic-charge order. In this study, the self-sensing feature of a nano-displacement ME actuator is investigated. The ME structure design, as well as the effect of geometric parameter and resonance frequency on the ME signal, is evaluated using a numerical modeling. The Metglas/PMN-PT/Metglas composite was fabricated as an ME actuator. The displacement measurement was conducted using a laser Doppler. The effect of bias field and excitation frequency on sensitivity, linearity, resolutio

Study on magnetorheological damper stiffness shift

Mohammad H Jafarkarimi, Shahryar Ghorbanirezaei, Yousef Hojjat, Vahid Sabermand
Journal PaperSmart Structures and Systems , Volume 25 , Issue 3, 2020 March 1, {Pages 279 }

Abstract

Electrical current is usually used to change the damping force of Magnetorheological Dampers (MRDs). However, changing the electrical current could shift the stiffness of the system, the phenomenon that was not considered carefully. This study aims to evaluate this shift. A typical MRD was designed, optimized, and fabricated to do some accurate and detailed experimental tests to examine the stiffness variation. The damper is equipped with a circulating system to prevent the deposition of particles when it is at rest. Besides that, a vibration setup was developed for the experimental study. It is capable of generating vibration with either constant frequency or frequency sweep and measure the amplitude of vibration. The damper was tested by

Introduction, simulation and experimental investigation of a planar positioner based on permanent magnet linear synchronous motor technology

Yousef Hojjat, Behzad Ghavami Namin
Journal PaperModares Mechanical Engineering , Volume 19 , Issue 12, 2019 December 15, {Pages 0-0 }

Abstract

This open-access journal is published under the terms of the Creative Commons Attribution-NonCommercial 4.0 International License which permits Share (copy and redistribute the material in any medium or format) and Adapt (remix, transform, and build upon the material) under the Attribution-NonCommercial terms.

Effects of film viscoelasticity on dynamic behavior of dielectric elastomer minimum energy structure

Hamed Vatanjou, Yousef Hojjat, MohammadReza Karafi
Journal PaperModares Mechanical Engineering , Volume 19 , Issue 11, 2019 November 15, {Pages 0-0 }

Abstract

This open-access journal is published under the terms of the Creative Commons Attribution-NonCommercial 4.0 International License which permits Share (copy and redistribute the material in any medium or format) and Adapt (remix, transform, and build upon the material) under the Attribution-NonCommercial terms.

Testing the application of Free Flapping Foils (FFF) as a method to improve adhesion in an electrostatic wall-climbing robot

Vahid Sabermand, Shahryar Ghorbanirezaei, Yousef Hojjat
Journal PaperJournal of Adhesion Science and Technology , Volume 33 , Issue 23, 2019 December 2, {Pages 2579-2594 }

Abstract

In this paper, extensive testing on an electrostatic wall-climbing robot is carried out to examine the electrostatic adhesion force when using the Free Flapping Foils (FFF) method. This method is successfully applied to an electrostatic robot to enable it to stick more firmly, by about three times, on walls with different materials, including wood, plaster, granite, glass and climb wall with a continuous movement. The innovation in this paper is that successful tests were carried out, when using thin flexible electrodes made from aluminium foil and free movement of those electrodes. The FFF electrodes are flexible enough to get the shape and roughness of the wall and increases the contact surface. Thus, they increase the adhesion force and

Design, analysis, and optimization of a magnetoelectric actuator using regression modeling, numerical simulation and metaheuristics algorithm

M Sadeghi, Y Hojjat, M Khodaei
Journal PaperJournal of Materials Science: Materials in Electronics , Volume 30 , Issue 17, 2019 September 1, {Pages 16527-16538 }

Abstract

In this study, a new method was proposed for the design of composite magnetoelectric actuator. Design of experiment (DOE) was utilized to investigate the mutual effect of geometric parameters. Moreover, the effect of impedance phase angle, magnetic field, and bias field were studied through finite element (FE) modeling. Resonance frequency, displacement value, magnetoelectric coefficient, and mode shape were considered as response variables. Analysis of variance (ANOVA), regression modeling and response surface method (RSM) were used to investigate the pair-wise effect of input parameters on the response variables. ANOVA results showed that the magnetoelectric length and piezoelectric thickness are the most important parameters affecting th

Nonlinear dynamic analysis of dielectric elastomer minimum energy structures

H Vatanjou, Y Hojjat, M Karafi
Journal PaperApplied Physics A , Volume 125 , Issue 9, 2019 September 1, {Pages 583 }

Abstract

This paper presents a theoretical study of nonlinear dynamic behavior of a dielectric elastomer minimum energy structure (DEMES). While planar Dielectric Elastomer Actuators (DEA) solely poses material nonlinearity in their model, geometrical nonlinearity imposes additional challenge to model DEMES. Considering dielectric elastomer and bending frame, respectively, as a hyper-elastic film and an elastic beam, Euler–Lagrange equation is employed to derive the equation of motion of actuator subject to a harmonic voltage. Fixed point analysis of the equation of motion demonstrates supercritical pitchfork bifurcation with respect to film pre-stretch as bifurcation parameter. It is shown by simulation results that the system poss

Design and fabrication of a new piezoelectric paper feeder actuator without mechanical parts

Shahryar Ghorbanirezaei, Yousef Hojjat, Mojtaba Ghodsi
Journal PaperSmart Structures and Systems , Volume 24 , Issue 2, 2019 January , {Pages 183-191 }

Abstract

A piezoelectric paper feeder actuator using Micro Virtual Roller (MVR) is proposed, designed, fabricated and tested. This actuator can drive a sheet of paper forward or backward without any mechanical parts, such as the costly and heavy rollers used in traditional paper feeders. In this paper feeder actuator, two vibrating stators which produce traveling waves are used to drive the paper. The vibrations of the stators are similar to those of piezoelectric motors and follow a similar procedure to move the paper. A feasibility study simulated the actuator in COMSOL Multiphysics Software. Traveling wave and elliptical trajectories were obtained and the dimensions of the stator were optimized using FEM so that the paper could move at top speed.

A Review of International Green Economy and Green Tax Policies

Elahe Pourkarimi, Yousef Hojjat
Journal Paper , Volume 1 , Issue 1, 2019 September 1, {Pages 29-36 }

Abstract

The global green economy mechanism is considered in some international environmental documents to achieve sustainable development. Promoting environmental-friendly technologies, protecting natural capital, improving employment and reducing poverty, along with expanding investment and technology, are based on green economy policies. Green taxation is one of the tools of the green economy policy for the deployment of sustainable technologies. This research is based on the analysis of law and environmental documents with the green economy approach. From the most important green tax strengths, weaknesses, opportunities and threats (SWOT) has been identified in this paper, deployment of environmentally friendly technologies, the possibility of r

Effects of Dielectric Film Viscoelasticity on Dynamic Behavior of Dielectric Elastomer Minimum Energy Structure

H Vatanjou, Y Hojjat, MR Karafi
Journal Paper , , {Pages }

Abstract

Development of a hybrid DEP-SAW device for trapping/sensing target cells

R Ghayour, Y Hojjat, MR Karafi, H Sadeghiyan
Journal PaperApplied Acoustics , Volume 141 , 2018 December 1, {Pages 355-361 }

Abstract

For detecting cells by Surface Acoustic Wave sensors, a sacrificial layer with antigens is usually used to trap cells. This paper introduces a new idea where Dielectrophoresis force traps target cells instead of a sacrificial layer that reacts with target cells and sensed by the surface acoustic wave. Therefore, one can use the sensors more than once, and it is possible to trap different types of cells with different dielectric properties. The device is simulated, and the main parameters of a Dielectrophoresis trapping system and Surface Acoustic Wave sensor, have been introduced and optimized. The effects of focused and unfocused electrode are studied numerically on the displacement of the sensor. Eventually, the feasibility of using the h

The effect of temperature on tensile behavior and microstructure of Al-3 vol% SiC nanocomposite

Mohammadreza Soltani, Amir Atrian
Journal PaperIranian Journal of Manufacturing Engineering , Volume 5 , Issue 2, 2018 October 23, {Pages 08-Jan }

Abstract

In this study, high-temperature tensile behavior of Al-3 vol% SiC nanocomposite is investigated. To fabricate the samples, SiC nano reinforcements and Al matrix were mixed using an attrition milling. The mixed powders were then subjected to cold pressing and hot extrusion at temperature of 500? C. Tensile behavior at different temperatures along with density measurement and microstructural examinations were studied. The results represent a 40% improvement in ultimate tensile strength of Al-3vol% SiC nanocomposite in comparison with non-reinforced sample at ambient temperature. Also, a rise in temperature up to 270 ? C during the tensile test led to an increase of the maximum elongation. Moreover, this temperature rise caused to 50% and 44%

Reduction of magneto rheological dampers stiffness by incorporating of an eddy current damper

Ali Asghar Maddah, Yousef Hojjat, Mohammad Reza Karafi, Mohammad Reza Ashory
Journal PaperJournal of Sound and Vibration , Volume 396 , 2017 May 26, {Pages 51-68 }

Abstract

In this paper, a hybrid damper is developed to achieve lower stiffness compared to magneto rheological dampers. The hybrid damper consists of an eddy current damper (ECD) and a Magneto Rheological Damper (MRD). The aim of this research is to reduce the stiffness of MRDs with equal damping forces. This work is done by adding an eddy current passive damper to a semi-active MRD. The ECDs are contactless dampers which show an almost viscous damping behavior without increasing the stiffness of a system. However, MRDs increase damping and stiffness of a system simultaneously, when a magnetic field is applied. Damping of each part is studied theoretically and experimentally. A semi-empirical model is developed to explain the viscoelastic behavior

Development of a new method for experimental dielectrophoresis force measurement in the microfluidic cell sorting actuators

Hesam Sadeghian, Yousef Hojjat, Masoud Soleimani
Journal PaperModares Mechanical Engineering , Volume 17 , Issue 3, 2017 May 15, {Pages 150-158 }

Abstract

Dielectrophoresis is a phenomenon with wide application in the cell sorting system, in which the dielectrophoresis force acts on a dielectric particle located in the non-uniform electric field. In this study, governing equations on this phenomenon are presented and a new method for measuring dielectrophoresis force is developed. This method is based on measuring drag force on particle and solving the equilibrium equations. For this purpose drag force is measured in two directions, parallel and perpendicular to electrodes. To evaluate the method, an actuator has been developed which has paralleled electrodes with 50 widths and 50 intervals and a PDMS channel with height of 80 is mounted on them. In experimental result, the exerted dielectrop

Development of Gasoline Direct Injector using giant magnetostrictive materials

Mojtaba Ghodsi, Nasser Hosseinzadeh, Abdullah ?zer, Hamid Rajabzadeh Dizaj, Yousef Hojjat, Nader Garjasi Varzeghani, Mohammad Reza Sheykholeslami, Soheil Talebian, Mohammad Hadi Ghodsi, Amer Al-Yahmadi
Journal PaperIEEE Transactions on Industry Applications , Volume 53 , Issue 1, 2017 January , {Pages 521-529 }

Abstract

This paper presents a conceptual design and control of a novel gasoline direct injector (GDI) using giant magnetostricitve material, Terfenol-D, as an actuation component. Electromagnetic and fluid analyses are accomplished to investigate the influence of some parameters, such as nozzle length, pressure of input fuel, and cone angle of injector's needle. Experimental results obtained from fabricated GDI show good agreement with the numerical results provided by the 3-D finite-element analysis. Furthermore, the fabricated GDI is controlled by fuzzy and PID controllers. It was shown that fuzzy controllers provide faster response with less accuracy compared to the PID controller. Consequently, there is a tradeoff between fast response and stea

Interdigitated electrode design and optimization for dielectrophoresis cell separation actuators

Hesam Sadeghian, Yousef Hojjat, Masoud Soleimani
Journal PaperJournal of Electrostatics , Volume 86 , 2017 April 1, {Pages 41-49 }

Abstract

Among all particle separation approaches, dielectrophoresis actuators which use electric properties difference between particles, have turned into strong separating tools. This way, the particles in the fluid within non-uniform electric field experience the dielectrophoresis force. The amount and direction of this force depend on the fluid and particle polarization, particle size and electric field gradient. In this paper after presenting governing equations concerning the dielectrophoresis phenomenon, a microfluidic actuator introduced in which an interdigitated electrode pattern is applied in. Voltage, pitch, and width to pitch ratio of electrode as well as channel height are of the most important geometrical parameters of this actuator w

Investigation of Effective Parameters of Drop-on-Demand Droplet Generator

Mojtaba Ghodsi, M Ghodsi, Y Hojjat, H Sadeghian, H Ziaiefar, M Mohammadzaheri, A Al-Yahmedi
Journal PaperThe Journal of Engineering Research [TJER] , Volume 14 , Issue 2, 2017 June 30, {Pages 182-190 }

Abstract

This article presents a design and development of a drop-on-demand (DOD) droplets generator. This generator uses molten metal as a liquid and can be used in fabrication, prototyping and any kind of printing with solder droplets. This setup consists of a vibrator solenoid with tunable frequency to produce a semi-spherical shape of molten metal, close to the surface of fabrication. This design also has a nozzle with micro-size orifice, a rod for transmitting force and a heater to melt the metal and keep it in superheat temperature. This DOD can produce droplets in different sizes (less than 550 ?m) by controlling the vibration frequency of solenoid. This ability together with the accuracy of the droplets in positioning (the error is less than

ارائه روشی نوین برای اندازه گیری تجربی نیروی دی‌الکتروفورز در عملگرهای میکروفلویدیک جداسازی سلول‌‎

صادقیان, حجت, یوسف, سلیمانی, مسعود‎
Journal Paper , , {Pages }

Abstract

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