Mir Mohammad Ettefagh

• PhD
• Professor (Associate) at University of Tabriz

This study focuses on wave energy harvesting by leveraging the impact-induced frequency of sea waves. It introduces a novel double-buoyed model based on the existing single-buoyed system to address the shortcomings of previous systems. Notably, the traditional single-buoyed system, which is characterized by a long beam extending to the sea floor, p...

Structural health monitoring is vital for the early detection of damage, enabling effective life cycle management of structures. Detecting compound damage, where multiple types of damage occur simultaneously in different sections of a structure, is particularly challenging, especially when some of the damages are subtle or minor. Existing methods t...

Structural health monitoring (SHM) is crucial in the early stage of damage formation for the life-cycle service of offshore structures. The influence of soils on vibration-based damage detection systems in offshore structures is a critical issue but has received less attention in previous literature. Due to the complexity of offshore structures and...

In the realm of advanced materials engineering, the development of hybrid nanocomposites has garnered significant attention due to their superior mechanical properties and potential applications. The primary aim of this research is to develop a surface hybrid nanocomposite using Al1050 aluminium alloy (5 mm thickness) as the base material through f...

This study employs friction stir processing to create a surface alloy using Al1050 aluminum as the base material, with Cu powder applied to enhance surface properties. Various parameters, including tool rotation speed, feed rate, and the number of passes, are investigated for their effects on the microstructure and mechanical properties of the resu...

Gantry cranes play a pivotal role in various industrial applications, and their reliable operation is paramount. While routine inspections are standard practice, certain defects, particularly in less accessible components, remain challenging to detect early. In this study, first a finite element model is presented, and the damage is introduced usin...

Engineering has many necessary fields, and Structural Health Monitoring (SHM) is one of the most important of them. Sometimes in industrial environments, it is difficult and even impossible to collect data containing different real damages. Therefore, the problem of data acquisition represents a primary challenge in designing damage detection syste...

One of the most important issues regarding cars is the type of optimal car steering mechanism, which has been extensively researched in this field due to its importance. In this research, the Ackerman steering mechanism for the front-axle steerable vehicle has been investigated. At first, the researches of the predecessors have been described with...

Monitoring structural damage is critical for preserving the service life of engineering systems. In varying operational environments, the working loads are changing all the time and they are typically unknown; in such environments, access to damage data is difficult and sometimes even impossible, and generally, intact data of the system is availabl...

The purpose of this research is to investigate different milling parameters for optimization to achieve the maximum rate of material removal with the minimum tool wear and surface roughness. In this study, a tool wear factor is specified to investigate tool wear parameters and the amount of material removed during machining, simultaneously. The sec...

In the current study, the simultaneous effect of warping function and elastic layer on the natural frequency of torsional vibration of nano-bars in the presence of a magnetic field is investigated, because changes in the elastic layer with considering the specified interval of diameter ratio for a nano-bar cause that maximum frequency occurred at v...

In this research, the control of a hexarot parallel mechanism is investigated. Parallel kinematic simulators or machine tools manipulators suffer from many problems to have a good motion tracking. The inverse kinematics and dynamic formulation that have been developed recently via the Newton–Euler method for a general hexarot mechanism is briefly p...

Floating wind turbines may encounter severe situations because of harsh environments. Higher cost of repair and maintenance of floating wind turbines have led researches to focus on damage detection methods that can prevent sudden failures. This paper presents an applicable method of damage detection and structural health monitoring for floating wi...

This paper discusses the damage identification in the mooring line system of a floating wind turbine (FWT) exposed to various environmental loads. The proposed method incorporates a non-probabilistic method into artificial neural networks (ANNs). The non-probabilistic method is used to overcome the problem of uncertainties. For this purpose, the in...

Due to difficulties in identifying localized and incipient bearing faults, most proposed fault diagnosis methods focus on detecting these faults. However, it is not clear to what extent of fault severity the proposed methods are capable of detecting. In other words, the crucial issue remains in the literature as to what is the criteria for defining...

Work shoe soles are a useful tool for decreasing the amplitude of vibration transmissibility to the human body for subjects exposed to foot-transmitted vibration (FTV) in the workplace. The main objective of this paper is to identify the viscoelastic safe area of work shoe soles in the sitting posture using a biomechanical model. To identify the mo...

Fundamentally, Structural Health Monitoring (SHM) of mechanical systems is essential to avoid their catastrophic failure. The first key contribution of this paper is presenting a new method for damage detection of mechanical systems in presence of the uncertainties such as modeling errors, measurement errors, varying loading conditions and environm...

In the case of a compound fault diagnosis of rotating machinery, when two failures with unequal severity occur in distinct parts of the system, the detection of a minor fault is a complicated and challenging task. In this case, the minor fault is overshadowed by the more severe one, and the characteristics of the compound fault are prone to the mor...

Structural health monitoring of mechanical systems is essential to avoid their catastrophic failure. In this article, an effective deep neural network is developed for extracting the damage-sensitive features from frequency data of vibration signals to damage detection of mechanical systems in the presence of the uncertainties such as modeling erro...

Aims Postponing muscular fatigue and preventing injuries of the lower extremity during running are common desires for professional runners. These favorites may significantly be provided via reducing the energy dissipation (ED) at the lower limb soft-tissues (LLST). It is obvious that footwear plays a main role in this matter. Use of a pair of sport...

Structural control of a system can be achieved by employing different control methods. The effectiveness of a control technique straightly depends on the performance of the control device. Among control devices, the tuned liquid column gas damper (TLCGD) has shown high vibration control capabilities. In this study, a newly developed damping system...

Variational mode decomposition is a powerful signal processing technique that can adaptively decompose a multi-component signal into a number of modes, via solving an optimization problem. The optimal performance of this method in signal decomposition and avoiding of the mode mixing problem strictly relies on the true selection of decomposition par...

In this study, vibrations of human gastrocnemius during an exhaustive run protocol are considered for analysis. Previous studies have shown increased vibration intensity and damping coefficient within the soft tissue with fatigue. The question of this study was to investigate if the vibration settling time remains constant during a prolonged runnin...

Biological findings show that the activity of the calf muscle group is controlled by the central nervous system during running. The central nervous system tries to retain the peak values of the ground reaction force at constant levels as well as to minimize the vibration amplitude of soft tissues of the lower leg. Furthermore, these objectives are...

Knowing how a musical instrument vibrates can benefit the tonal characteristics shaping of the instrument. In this research, an approach for investigating the mode shapes and natural frequencies of Setar body is addressed. First, mechanical properties of wood used in the production of Setar are analyzed experimentally. Then a numerical modal test i...

Recently, a new type of automatic ball balancer (ABB), called the ball-spring autobalancer (AB), has been proposed, which substantially eliminates the drawbacks of the traditional ABBs. In previous studies, the dynamics of the Jeffcott planar rotor equipped with ball-spring AB has been investigated. In the Jeffcott model, it is assumed that the ABB...

This paper proposes a novel super-twisting PID sliding mode controller (STPIDSMC) using a multi-objective optimization bat algorithm (MOBA-STPIDSMC) for the control of a MEMS gyroscope. In order to enhance the robustness of the control system, a sliding surface based on PID controller is designed. The chattering phenomenon in PID sliding mode contr...

This paper proposes a new adaptive neural network integral sliding-mode controller using a bat algorithm (BA-ANNISMC) to control a biped robot. The conventional integral sliding-mode controller (ISMC) is discontinuous in nature due to the combination of nominal control and discontinuous feedback control. The phenomenon of chattering occurs when the...

Stability and dynamic modeling of the floating wind turbine (FWT) is a crucial challenge in designing of the type of structures. In this paper, the tension leg platform (TLP) type FWT is modeled as a multibody system considering the flexibility between the nacelle and tower. The flexibility of the FWT is modeled as a torsional spring and damper. It...

The vibration of the machine tool has important effect on machining quality of parts. So, in this paper, the dynamic behavior and modal parameters of the vertical moving table of the 4-DOF parallel machine tool are studied using the FEM and experimental methods. The prepared model of the vertical moving table in Solidworks is exported to ANSYS envi...

The cavitation phenomenon, which is rampant in axial flow pumps, should be avoided due to its undesirable effects on the pump’s performance. Therefore, in this study the cavitation performance of an axial flow pump is monitored based on vibration signals. For this purpose, experimental vibration data is collected for five different levels of cavita...

Introduction: Repetitive sock loads are the results of interaction between human musculature system and the ground during daily tasks such as walking. The magnitude and the frequency of these loads are functions of muscle activity and shoe-ground stiffness parameters. Soft tissue vibration is one result of these loads and its characteristics could...

One of the new methods for electrical powering of the bridge health monitoring systems is applying energy harvesting systems using bridge vibration. In this method, the piezoelectric material is employed for converting mechanical energy into electrical energy. The advantage of this method is based on not implementing the battery charging system. In...

When combined faults happen in different parts of the rotating machines, their features are profoundly dependent. Experts are completely familiar with individuals faults characteristics and enough data are available from single faults but the problem arises, when the faults combined and the separation of characteristics becomes complex. Therefore,...

One of the new methods for reducing the vibrations of rotors with variable imbalance is implementing automatic ball balancer (ABB). Although the ABB has numerous advantages, it has one major deficiency; increasing the rotor vibration amplitude at transient state that limits the use of this type of balancers. In the previous studies for diminishing...

A voice is a sound which is created by vibration of the vocal cords, which means that, the vocal cords approach to each other by passing the air through the larynx and followed by different sounds. This vibration is under the influence of the statuses of tongue, teeth and lips, as well as the other effective factors. This vibrating air causes some...

A voice is a sound which is created by vibration of the vocal cords, which means that, the vocal cords approach to each other by passing the air through the larynx and followed by different sounds. This vibration is under the influence of the statuses of tongue, teeth and lips, as well as the other effective factors. This vibrating air causes some...

This paper proposes a control scheme based on the fraction integral terminal sliding mode control and adaptive neural network. It deals with the system model uncertainties and the disturbances to improve the control performance of the inchworm robot manipulator. A fraction integral terminal sliding mode control applies to the inchworm robot manipul...

A voice is a sound which is created by vibration of the vocal cords, which means that, the vocal cords approach to each other by passing the air through the larynx and followed by different sounds. This vibration is under the influence of the statuses of tongue, teeth and lips, as well as the other effective factors. This vibrating air causes some...

Structural health monitoring (SHM) is essential for ensuring the structural safety performance during the service life. The process is of paramount importance in the case of the floating wind turbine (FWT) due to the structural parts, subjected to the marine environmental risky conditions. In this paper a fuzzy-based damage detection method, using...

Several mass-spring-damper (MSD) models have been developed to study biodynamical characteristics of the body during running, especially the ground reaction force. The MSD models are mainly categorized into passive and active models. Plenty of the passive models have been proposed in which compliant properties of the elements modeling the soft tiss...

This paper proposes a novel adaptive fractional order PID sliding mode controller (AFOPIDSMC) using a Bat algorithm to control of a Caterpillar robot manipulator. A fractional order PID (FOPID) control is applied to improve both trajectory tracking and robustness. Sliding mode controller (SMC) is one of the control methods which provides high robus...

Structural health monitoring is essential for ensuring the structural safety performance during the service life. The process is of paramount importance in the case of the Pelamis wave energy converter due to the structural parts being subjected to the marine environmental risky conditions and consequently, power take-off system damage. In this pap...

An understanding of the dynamic behavior of the carbon nanotubes (CNTs) conveying fluid is very important for exploring the applications in nanoscale systems. Due to the molecular network disruption, the passing flow has multiphase nature. In this regard, the nonlinear vibration behavior of the CNT conveying multiphase flow is investigated by consi...

Structural Health Monitoring (SHM) of Tension Leg Platform (TLP) is very crucial for preventing catastrophic and sudden collapse of the structures. One of the methods of monitoring these structures is implementing SHM sensors. Supplying energy for these sensors for a long period is a challenging problem. So, one of the new methods of supplying ener...

A new fault classification/diagnosis method based on artificial immune system (AIS) algorithms for the structural systems is proposed. In order to improve the accuracy of the proposed method, i.e., higher success rate, Gaussian and non-Gaussian noise generating models are applied to simulate environmental noise. The identification of noise model, k...

Damage identification of the offshore floating wind turbine by vibration/dynamic signals is one of the important and new research fields in the Structural Health Monitoring (SHM). In this paper a new damage identification method is proposed based on meta-heuristic algorithms using the dynamic response of the TLP (Tension-Leg Platform) floating wind...

There are many researches on the vibration behavior of the multi-phase flow in the pipes. However, there isn’t any general statistical study on the dynamic response of such systems. Therefore in this paper, at the first step, the nonlinear equation governing the transverse vibration of the pipe is derived using the Hamilton's principle. The nonline...

One of the new methods for powering low-power electronic devices at sea is a wave energy harvesting system. In this method, piezoelectric material is employed to convert the mechanical energy of sea waves into electrical energy. The advantage of this method is based on avoiding a battery charging system. Studies have been done on energy harvesting...

Muscle tuning paradigm proposes that the mechanical properties of soft tissues are tuned in such a way that its vibration amplitude become minimized. Therefore, the vibrations of soft tissue are heavily damped. However, it has been hypothesized that the ability of muscle tuning decreases with fatigue. This study investigated the changes in vibratio...

The importance of substituting the conventional fossil fuels by clean energies exhorts the scientists and specialists of this major to present new and effective methods for this substitution. These new methods must have enough capability for utilizing the clean energies more than the previous operated methods. The main goal of this research is base...

Modelling and simulation of the bridge response during vehicle crossing is of the utmost importance in bridge design. In previous works some studies have been conducted on this issue, but parametric statistical investigations and reliability analysis of the bridge response are not studied in the reported literature. In this research, after modellin...

In this paper, a novel 6-DOF parallel manipulator with coaxial actuated arms is introduced and investigated. This mechanism has six rotating arms, and by rotation of arms about the base, positioning and desired movement of the mechanism is achieved. Sine parallel mechanisms have a nonlinear motion while moving from an initial position to a desired...

Early prediction of damages using vibration signal is essential in avoiding the failure in structures. Among different damage-detection approaches, the finite-element model updating and modal analysis-based methods are of most importance due to their applicability and feasibility. Owing to some restrictions in nodal measurements in experimental cas...

Condition monitoring and fault diagnosis of rotating machinery are very significant and practically challenging fields in industries for reducing maintenance costs. Fault diagnosis may be interpreted as a classification problem; therefore artificial intelligence-based classifiers can be efficiently used to classify normal and faulty machine conditi...

In recent years, ANN (artificial neural network) method has been used as an effective method for analyses of the characteristic parameters in internal combustion engines. Also, determination of the best network structure is an important part of the research work in this branch. So, this subject is the main idea of the current study. The most reliab...

In this paper, ABC (Artificial Bee Colony), PSO (Particle Swarm Optimization), TS (Tabu Search) and SA (Simulated Annealing) algorithms are applied to estimate the elastic constant of the laminated composite beam by means of measuring vibration frequency of the beam using experimental modal analysis. For this purpose, a proper object function is de...

Synthesis of four-bar Ackermann steering mechanism was considered as an optimization problem for generating the best function between input and output links. The steering mechanism was designed through two heuristic optimization methods, namely, artificial immune system (AIS) algorithm and genetic algorithm (GA). The optimization was implemented us...

In this paper, a novel 6-DOF parallel manipulator with coaxial actuated arms is introduced and investigated. This mechanism has six rotating arms, and by rotation of arms about the base, positioning and desired movement of the mechanism is achieved. Sine parallel mechanisms have a nonlinear motion while moving from an initial position to a desired...

Kinematic analysis and workspace determination of hexarot-a novel 6-DOF parallel manipulator with a rotation-symmetric arm system . Robotica, Available on CJO 2014 doi:10.1017/S0263574714000988 Request Permissions : Click here Downloaded from http://journals.cambridge.org/ROB, IP address: SUMMARY Parallel mechanisms possess several advantages such...

Frequency response and vibration study of friction-welded specimens with different fatigue life properties is very important. Friction stir spot welding (FSSW) is one of the welding methods applied in different types of manufacturing processes such as in the vehicle and aerospace industries. Therefore the main purpose of this paper is better unders...

Evaluation of fatigue life of vehicles by using a real road test is very expensive; therefore, numerical methods such as Finite Element Method (FEM) are nowadays very popular for evaluating fatigue life. In this study, a method based on FEM is proposed for predicting fatigue strength of the chassis when designing and optimizing a semi-heavy truck....

In this paper, artificial bee colony, and particle swarm optimisation algorithms are used for the synthesis of the four-bar mechanisms in path generating process based on optimisation methods for the fist time. The main goal is to extract the optimised dimension of mechanism links to transmit coupler point in the desired path with minimum error. In...

In this paper, a new method for dynamic balancing of double four-bar crank slider mechanism by metaheuristic-based optimization algorithms is proposed. For this purpose, a proper objective function which is necessary for balancing of this mechanism and corresponding constraints has been obtained by dynamic modeling of the mechanism. Then PSO, ABC,...

The detection of changes in the dynamic behavior of structures is an important issue in structural safety assessment. The development of detection methods assumes greater significance in the case of offshore platforms because the inherent problems are compounded by the harsh environment. Here, we describe an instrumented physical model for the stru...

In this study vibration-based delamination detection is achieved using the artificial immune system (AIS) method. The approach is based upon mimicking immune recognition mechanisms that possess features such as adaptation, evolution, and immune learning. The identification of the delamination location and its length in the composite beam is formula...

In this study, ABC (Artificial Bee Colony) and BGA (Binary Genetic Algorithm) algorithms are used to synthesis of the four-bar mechanisms for path generating. The main goal is to extract the optimized dimension of mechanism links to transmit coupler point in the desired path with minimum error. In addition, the object mechanism has dimensional limi...

In this paper, synthesis of the steering mechanism is optimized using Artificial Immune System (AIS) Algorithm and Genetic Algorithm for best function generation. A four-bar mechanism is employed as the Ackermann steering mechanism. For the first time the optimization in this problem is implemented with two methods. In the first method the length a...

In this paper modal analysis of third stage blade in a gas turbine is investigated and vibration modes of blade are found. The blade made of nickel-base alloy which specified as IN738LC alloy. Using optical imaging method the cloud of points with high accuracy has been obtained. This cloud of points has been processed with Geomagic software and a m...

Machine tool vibrations have great impact on machining process. In this paper the dynamic behavior and modal parameters of milling machine is presented. For this purpose, the CAD model of the milling machine structure is provided in CATIA and then Natural frequencies and mode shapes of the machine tool structure are carried out through FEM modal an...

Machine tool vibrations have great impact on machining process. In this paper the dynamic behavior and modal parameters of surface grinding machine is presented. For this purpose, the CAD (computer aided design) model of the surface grinding machine structure is provided in catia and then Natural frequencies and mode shapes of the machine tool stru...

Machine tool vibrations have great impact on machining process. Dynamic parameters such as the modal frequencies and damping constant of their components are the essential technical information required in engineering analysis and design. In addition, this information is needed for numerical simulations and finite element modeling to predict the re...

In this paper, synthesis of the steering mechanism is optimized using Artificial Immune System (AIS) Algorithm for best function generation. A four-bar mechanism is employed as the Ackermann steering mechanism. For the first time the optimization in this problem is implemented with two methods. In the first method the length are selected as optimiz...

Machine tool vibrations have great impact on machining process. In this paper, the dynamic behavior and modal parameters of grinding machine are presented. For this purpose, the CAD model of the grinding machine structure is provided in CATIA and then Natural frequencies and mode shapes of the machine tool structure are carried out through FEM moda...

Machine tool vibrations have great impact on machining process. In this paper the dynamic behavior and modal parameters of surface grinding machine is presented. For this purpose, the CAD (computer aided design) model of the surface grinding machine structure is provided in catia and then Natural frequencies and mode shapes of the machine tool stru...

Steel jacket-type platforms are the common kind of the offshore structures and health monitoring is an important issue in their safety assessment. In the present study, a new damage detection method is adopted for this kind of structures and inspected experimentally by use of a laboratory model. The method is investigated for developing the robust...

In this study a vibration-based Delamination detection is achieved using artificial immune system (AIS) method. The approach is based upon mimicking immune recognition mechanisms that possess features such as adaptation, evolution, and immune learning. A model for determining composite beam natural frequencies evaluated. Detection accuracy and pred...

The estimation of a crack location and depth in a cantilever beam is formulated as an optimization problem and the optimal location and depth are found by minimizing the cost function which is based on the difference of the first four measured and calculated natural frequencies. Calculated natural frequencies are obtained using a rotational spring...

In this paper, the steering mechanism is optimized through Artificial Immune System (AIS) for function generation. A four-bar mechanism is employed as the Ackermann steering mechanism. The optimization is implemented with two procedures: lengths as optimization parameters and distribution of precision points as optimization parameters. For the firs...

Reduction of transmitted vibrations of tractor cabin which is caused by road roughness is the major objective of this study; consequently operator health can be achieved. This objective is carried out via experimental measurements and finite element modeling. For this purpose the vertical acceleration of the cabin as well as the rear axle of the tr...

Machine tool vibrations have great impact on machining process. In this paper the dynamic behavior and modal parameters of milling machine is presented. For this purpose, the CAD model of the milling machine structure is provided in CATIA and then Natural frequencies and mode shapes of the machine tool structure are carried out through FEM modal an...

Structural monitoring is essential for ensuring the structural safety performance during the service life. The process is of paramount importance in case of the offshore jacket-type platforms due to the underwater structural parts subjected to the marine environmental conditions. This work is an experimental investigation on a laboratory model of a...