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Reduced multiple model predictive control of an heating, ventilating, and air conditioning system using gap metric and stability margin
, Article Building Services Engineering Research and Technology ; Volume 43, Issue 5 , 2022 , Pages 589-603 ; 01436244 (ISSN) ; Haeri, M ; Sharif University of Technology
SAGE Publications Ltd
2022
Abstract
In this paper, a reduced multiple-model predictive controller based on gap metric and stability margin is presented to control heating, ventilating, and air conditioning (HVAC) systems. To tackle the strong nonlinearity and large number of degrees of freedom in HVAC system, two approaches, called Reduced Order Model Bank-Multiple Model (ROMB-MM) and Multiple Model-Reduced Order Model (MM-ROM), are introduced. In the first approach, the order reduction is performed prior to multiple models selection and in the second one multiple models selection is implemented before the model order reduction. Furthermore, soft switching is employed to enhance the closed-loop performance as well as to gain...
Improving the performance of helical motion resolver based on accurate modelling of longitudinal end effect
, Article IET Electric Power Applications ; Volume 16, Issue 10 , 2022 , Pages 1212-1222 ; 17518660 (ISSN) ; Nasiri Gheidari, Z ; Sharif University of Technology
John Wiley and Sons Inc
2022
Abstract
Using multiple position sensors in the control system of Two-Degrees of Freedom (2-DOF) motors causes it more complicated than that of conventional 1-DOF ones. However, employing a 2-DOF position sensor in comparison with two independent sensors, reduces the complexity, mass and volume of the system. The common 2-DOF sensors are able to determine the position in linear, rotational, and helical motion. Yet, they suffer from accuracy reduction due to the longitudinal end effect. Therefore, analytical modelling and the relevant compensation methods are discussed. The accuracy of the model is approved by comparing its results with those of 3D time transient finite element method. Afterwards, the...
Comparisons of lumbar spine loads and kinematics in healthy and non-specific low back pain individuals during unstable lifting activities
, Article Journal of Biomechanics ; Volume 144 , 2022 ; 00219290 (ISSN) ; Arjmand, N ; Kahrizi, S ; Sharif University of Technology
Elsevier Ltd
2022
Abstract
Evaluation of spinal loads in patients with low back pain (LBP) is essential to prevent further lumbar disorders. Many studies have investigated the relationship between lifting task variables and lumbar spine loads during manual lifting activities. The nature of the external load (stable versus unstable loads) is an important variable that has received less attention. Therefore, the present study aimed to measure trunk kinematics and estimate compressive-shear loads on the lumbar spine under lifting a 120 N stable load and 120 ± 13.63 N sensual unstable load in 16 healthy and 16 non-specific LBP individuals during lifting activities. The maximal lumbar loads were estimated using a...
Numerical simulation of vortex-induced vibration of a smooth circular cylinder at the subcritical regime
, Article Proceedings of the Institution of Mechanical Engineers Part M: Journal of Engineering for the Maritime Environment ; Volume 236, Issue 4 , 2022 , Pages 916-937 ; 14750902 (ISSN) ; Nemati Kourabbasloo, N ; Mohtat, P ; Tanha, A ; Sharif University of Technology
SAGE Publications Ltd
2022
Abstract
The present paper focuses on the simulation of vortex-induced vibration (VIV) of a rigid, smooth circular cylinder with elastic supports subject to a cross-flow at the subcritical regime of Reynolds number, 30,000
A one-DOF passive glove for thumb rehabilitation
, Article Scientia Iranica ; Volume 29, Issue 4 B , 2022 , Pages 1806-1816 ; 10263098 (ISSN) ; Zohoor, H ; Haghighi, S. E ; Soleimanimehr, H ; Sharif University of Technology
Sharif University of Technology
2022
Abstract
Wearable robots are becoming increasingly practical to use to rehabilitate wounded parts of the body as the number of injuries to the hand, particularly fingers, has increased. Wearable robots are designed to help people save time and money. This exoskeleton is intended to rehabilitate the thumb such that it may do an opposing movement with one Degree Of Freedom (DOF) and a cable system. Two drums, one on the thumb and the other on the tip of the assistive finger place the cables, which feature a cable adjusting screw that can be adjusted for fingers of various lengths. To choose the assistive finger from 4 intact fingers, the two perspectives of the cable length changes and finger forces...
Design and evaluation of hedge trimmer robot
, Article Computers and Electronics in Agriculture ; Volume 199 , 2022 ; 01681699 (ISSN) ; Massah, J ; Jamzad, M ; Sharif University of Technology
Elsevier B.V
2022
Abstract
An autonomous hedge trimmer robot was developed to reduce the harmful effects of traditional hedge trimming method (gasoline-powered hedge trimmer) on operators' bodies and increase the speed and quality of the operation. The robot had five degrees of freedom (PRRRR) structure and was geometrically optimized to simplify the control strategy, enabling it to trim simple, stepped, and circular forms. The control system, consisting of a host computer, servo motors and servo drivers, and controller, guided the robot platform, manipulator, and end-effector as it approached and trimmed the hedge. By using a recognition algorithm and vision-based navigation system, the robot was able to detect the...
Multi-scale dispersive gradient elasticity model with rotation for the particulate composite
, Article Composite Structures ; Volume 294 , 2022 ; 02638223 (ISSN) ; Toufigh, V ; Sharif University of Technology
Elsevier Ltd
2022
Abstract
Research on the characteristics of composites material has received enormous interest in recent years. The multi-scale nature of composite material leads to employing advanced techniques. Moreover, the presence of a wave with the high-frequency source adds complexity to the analysis. In this paper, a novel multi-scale elasticity model was developed to predict the wave dispersion property of particulate composites. The methodology was based on the simultaneous participation of translational and rotational degrees of freedom in motion equations. The method scheme of gaining motion equations was accomplished by using Taylor's expansion as a continualization method. The framework of the motion...
Recycling forward and backward frequency-multiplexed modes in a waveguide coupled to phased time-perturbed microrings for low-footprint neuromorphic computing
, Article Optical Materials Express ; Volume 12, Issue 3 , 2022 , Pages 1198-1213 ; 21593930 (ISSN) ; Memarian, M ; Mehrany, K ; Sharif University of Technology
The Optical Society
2022
Abstract
Optical structures can serve as low-power high-capacity alternatives of electronic processors for more efficient neuromorphic computing, but can suffer from large footprints and weak scalability. In this work, properly phased time-perturbed microrings side-coupled to a waveguide are utilized to realize a compact processor for linear transformations. We build up a synthetic frequency dimension to provide sufficient degrees of freedom, where the linear time-varying structures enable the linear intermixing and transformation of frequency-multiplexed data. Moreover, non-reciprocal and asymmetric flow of data in the forward and backward modes, due to phasing of the perturbations, helped to build...
The association between motor modules and movement primitives of gait: A muscle and kinematic synergy study
, Article Journal of Biomechanics ; Volume 134 , 2022 ; 00219290 (ISSN) ; Karami, H ; Baniasad, M ; Shojaeefard, M ; Farahmand, F ; Sharif University of Technology
Elsevier Ltd
2022
Abstract
In spite of the extensive literature on the analysis of the muscle synergies during gait, the functionality of these synergies has not been studied in detail. This study explored the relationship between the motor modules and the kinematic maneuvers involved in human walking. Motion and surface electromyography data (of 28 trunk and lower extremity muscles) were acquired from ten healthy subjects during ten trials of self-selected speed gait each. The joint angle trajectories were half-wave rectified and divided into two independent positive directional degrees-of-freedom. The muscle and kinematic synergies were both extracted using the non-negative matrix factorization (NNMF) technique and...
Satellite attitude PDE-based controller design considering fluid fuel sloshing in planar maneuver
, Article Aerospace Science and Technology ; Volume 122 , 2022 ; 12709638 (ISSN) ; Salarieh, H ; Nejat Pishkenari, H ; Sharif University of Technology
Elsevier Masson s.r.l
2022
Abstract
Due to significance of high-accuracy attitude control, the fuel sloshing effects on the satellite attitude should be considered, more precisely. This work deals with the attitude control of a liquid propellant-filled satellite considering the incompressible fuel sloshing in the planar maneuver. The satellite consists of a rigid body, a partially-filled tank and a flexible diaphragm. Hamilton's principle is employed to derive nonlinear coupled PDEs-ODEs governing the coupled satellite-diaphragm propellant tank system. Afterwards, to dispense with the spillover instability, a PDE-based controller is designed to realize the satellite attitude control while tracking a desired pitch angle and...
Interference alignment for the k-user MIMO interference channel
, Article IEEE Transactions on Information Theory ; Volume 68, Issue 3 , 2022 , Pages 1401-1411 ; 00189448 (ISSN) ; Motahari, A. S ; Khandani, A. K ; Sharif University of Technology
Institute of Electrical and Electronics Engineers Inc
2022
Abstract
We consider the K-user Multiple Input Multiple Output (MIMO) Gaussian interference channel with M antennas at each transmitter and N antennas at each receiver. It is assumed that channel coefficients are constant real numbers and are available at all transmitters and at all receivers. The main objective of this paper is to characterize the number of Degrees of Freedom (DoF) of this channel. Using the real interference alignment technique introduced in Motahari et al., 2014, we show that MN M+N K degrees of freedom can be achieved for almost all channel realizations. Also, a new upper-bound on the DoF of this channel is provided. This upper-bound coincides with our achievable DoF for K K u...
Robust D-stabilization analysis of fractional-order control systems with complex and linearly dependent coefficients
, Article IEEE Transactions on Systems, Man, and Cybernetics: Systems ; Volume 52, Issue 3 , 2022 , Pages 1823-1837 ; 21682216 (ISSN) ; Fathi Jegarkandi, M ; Sharif University of Technology
Institute of Electrical and Electronics Engineers Inc
2022
Abstract
This article focuses on the robust D-stabilization analysis of fractional-order control systems where each of the system and the controller may be of fractional order. The coefficients of the system are considered as complex linear functions of interval uncertain parameters, so this article deals with fractional-order polytopic systems. First, a necessary and sufficient condition is introduced for the robust D-stabilization of the closed-loop control system based on the zero exclusion condition and the value set concept. Then, the geometric pattern of the value set of the characteristic polynomial is obtained analytically using the exposed vertices. Second, a function is presented to check...
Effect of permeability heterogeneity on the dissolution process during carbon dioxide sequestration in saline aquifers: two-and three-dimensional structures
, Article Geomechanics and Geophysics for Geo-Energy and Geo-Resources ; Volume 8, Issue 2 , 2022 ; 23638419 (ISSN) ; Mahmoodpour, S ; Singh, M ; Omrani, S ; Sharif University of Technology
Springer Science and Business Media Deutschland GmbH
2022
Abstract
Abstract: The convection–diffusion process of carbon dioxide (CO2) dissolution in a saline reservoir is investigated to shed light on the effects of the permeability heterogeneity. Using sequential Gaussian simulation method, random permeability fields in two and three-dimension (2D and 3D) structures are generated. Quantitative (average amount of the dissolved CO2 and dissolution flux) and qualitative (pattern of the dissolved CO2 and velocity streamlines) measurements are used to investigate the results. A 3D structure shows a slightly higher dissolution flux than a 2D structure in the homogeneous condition. Results in the random permeability fields in 2D indicates an increase in the...
Seismic displacement ratios for soil-pile-structure systems allowed to uplift
, Article Soil Dynamics and Earthquake Engineering ; Volume 155 , 2022 ; 02677261 (ISSN) ; Vafaei, A ; Dolatshahi, K. M ; Sharif University of Technology
Elsevier Ltd
2022
Abstract
In this paper, the soil-pile-structure interaction effects on seismic displacement demands are investigated using various dimensionless parameters. The code prescribed procedures for estimating seismic displacement demands are built upon fixed-base structure assumption and neglect the effect of foundation uplift. Tensile index, the ratio of the summation of the tensile strength of all piles to the weight of the structure, is introduced as a novel dimensionless ratio for the seismic assessments. The seismic behavior of the structures with a small tensile index is close to the structures with uplift-allowed shallow foundations. Structures with a large tensile index behave like tied foundation...
Degrees of freedom of the K-User Interference channel assisted by active and passive IRSs
, Article IEEE Transactions on Communications ; Volume 70, Issue 5 , 2022 , Pages 3063-3080 ; 00906778 (ISSN) ; Jamali, V ; Nasiri Kenari, M ; Schober, R ; Sharif University of Technology
Institute of Electrical and Electronics Engineers Inc
2022
Abstract
In this paper, we study the degrees of freedom (DoF) region and sum DoF of the time-selective K-user interference channel in the presence of intelligent reflecting surfaces (IRSs). We consider both active and passive IRSs. While both types of IRS can attenuate the amplitude and change the phase of a reflected electromagnetic wave, active IRSs are also capable of amplifying the wave. We derive inner and outer bounds for the DoF region and lower and upper bounds for the sum DoF of the K-user interference channel in the presence of an active IRS and prove that the maximum value of K for the sum DoF can be achieved if the number of IRS elements exceeds a certain finite value. The analysis...
Helical motion wound-rotor resolver
, Article IEEE Sensors Journal ; Volume 22, Issue 10 , 2022 , Pages 9371-9377 ; 1530437X (ISSN) ; Nasiri Gheidari, Z ; Sharif University of Technology
Institute of Electrical and Electronics Engineers Inc
2022
Abstract
In this paper an integrated core, high reliability, linear-rotational resolver with a simple slotless configuration is proposed. The moving part of the proposed resolver has only one helical winding. While, its stator needs at least two individual windings to be able to determine the linear and angular position in simultaneous linear and rotational, helical, motions. Three different configurations are proposed for the stator's windings: (1) helical and horizontally skewed winding (2) helical and vertically skewed winding (3) horizontally and vertically skewed windings. The influence of the mentioned configurations is discussed in the terms of sensor's accuracy in independent and simultaneous...
Winding function model for predicting performance of 2-DOF wound rotor resolver
, Article IEEE Transactions on Transportation Electrification ; Volume 8, Issue 2 , 2022 , Pages 2062-2069 ; 23327782 (ISSN) ; Nasiri Gheidari, Z ; Sharif University of Technology
Institute of Electrical and Electronics Engineers Inc
2022
Abstract
Two-degree-of-freedom (2-DOF) electrical machines require position sensors for their motion control. In comparison with using two independent sensors, using a 2-DOF sensor enhances the closed-loop control system's performance. However, due to the 3-D structure of the 2-DOF sensor, its performance evaluation needs 3-D analysis. Also, due to helical motion the accuracy deterioration of the sensor, under mechanical faults needs more attention. Although the finite element method (FEM) is the best way to simulate such sensors, most of the commercial packages for transient finite element simulations are not able to consider two separate motions simultaneously. Furthermore, FEM has a high...
Active flow control of a wing section in stall flutter by dielectric barrier discharge plasma actuators
, Article Physics of Fluids ; Volume 34, Issue 7 , 2022 ; 10706631 (ISSN) ; Ebrahimi, A ; Amandolese, X ; Sharif University of Technology
American Institute of Physics Inc
2022
Abstract
This paper investigates the potential of using an active flow control technique to modify stall flutter oscillations of a NACA (National Advisory Committee for Aeronautics) 0015 wing section. Wind tunnel experiments have been performed with a test-rig that provides the elastic degree of freedom in pitch. Measurements of the clean airfoil are taken at preset angles of θ 0 = 6 ° - 12 °, and for Reynolds numbers of R e c = 6.2 × 10 4 - 1.25 × 10 5, which reveal the dependency of the stall flutter oscillations to Rec and θ0. Then, flow control experiments are carried out at θ 0 = 10 ° and R e c = 1.04 × 10 5. Two dielectric barrier discharge plasma actuators have been employed simultaneously to...
Remote monitoring and control of the 2-DoF robotic manipulators over the internet
, Article Robotica ; Volume 40, Issue 12 , 2022 , Pages 4475-4497 ; 02635747 (ISSN) ; Haghi, S ; Farhadi, A ; Sharif University of Technology
Cambridge University Press
2022
Abstract
This article is concerned with remote monitoring and control of the 2-degrees of freedom (DoF) robotic manipulators, which have nonlinear dynamics over the packet erasure channel, which is an abstract model for communication over the Internet, WiFi, or Zigbee modules. This type of communication is subject to imperfections, such as random packet dropout and rate distortion. These imperfections cause a significant challenge for monitoring and control of robotic manipulators in the industrial environments because sensitive data, such as sensor data and control commands may not ever reach to their destination resulting in significant performance degradation. Therefore, the effects of these...
A model for determining the arrangement and geometric specifications of infill walls in the architectural design to improve the seismic behavior of buildings
, Article Architectural Engineering and Design Management ; 2022 ; 17452007 (ISSN) ; Mehdizadeh Saradj, F ; Tabeshpour, M. R ; Sharif University of Technology
Taylor and Francis Ltd
2022
Abstract
Experiences of past earthquakes show that the infill wall is one of the non-structural elements which has the highest collapse potential of the structure. Although architects are responsible for designing the form and arrangement of walls, little research has been done in this regard with the aim of architectural design. In this research, a method was developed to control the infill walls in the basic architectural design. In this method, architectural design features are preserved, and only by applying minor modifications to the specifications of walls, undesirable effects such as short column, soft story, and torsion are prevented and without using more materials, additional potential for...