m. abolfazl mokhtari

In this article, the use of vibration absorbers to dampen the vibrations created by the helicopter engine has been described. During their flight mission, helicopters are affected by many vibrations, which can be considered as one of the most important sources of vibrations in helicopters, which cause different and intense dynamic environments such as the effects of vibrations with sinusoidal input and step and triangle to the helicopter, in between, the vibration environment with sinusoidal input has the main contribution in destroying and weakening the overall performance of the helicopter and the possible failure of the flight mission. By using the design of the damper system of the article, which is actually a combination of active absorbers with LQR PID algorithm and passive, which, at low frequencies, the active control function and its combination with the elastomeric base absorber is 20% more optimal than the passive absorber and 10 % is more optimal than the active absorber and since the helicopter engine is subjected to various vibrations with a high vibration amplitude during its flight mission, the designed system significantly reduces the generated vibrations and up to 96% of these vibrations in It will dampen the average performance of the engine and in different working conditions.

Aerodynamic parameter estimation is an integral part of aerospace system design and life cycle process. Recent advances in computational power have allowed the use of online parameter estimation techniques in varied applications such as reconfigurable or adaptive control, system health monitoring, and fault tolerant control. The combined problem of state and parameter identification leads to a nonlinear filtering problem; furthermore, many aerospace systems are characterized by nonlinear models as well as noisy and biased sensor measurements. Extended Kalman filter (EKF) is a commonly used algorithm for recursive parameter identification due to its excellent filtering properties and is based on a first order approximation of the system dynamics. Recently, the unscented Kalman filter (UKF) has been proposed as a theoretically better alternative to the EKF in the field of nonlinear filtering and has received great attention in navigation, parameter estimation, and dual estimation problems. However, the use of UKF as a recursive parameter estimation tool for aerodynamic modeling is relatively unexplored. In this paper we compare the performance of three recursive parameter estimation algorithms for aerodynamic parameter estimation of two aircraft from real flight data.

Nowadays, industrial systems deal with a wide range of constraints. Input saturation and lack of system model are two types of these constraints. In this paper, a separate model free adaptive data-driven controller for a nonlinear system called a simulator with the conventional configuration of a main single-tailed propeller, twin rotor MIMO system (TRMS) in the presence of input saturation is presented. In the proposed controller, the design of the control input signal only depends on the input and output data of the system and the system model is not used. The purpose of this paper is to control the horizontal and vertical angles of the TRMS system. For this purpose, at first, using the model of TRMS that has been presented for this system in previous articles, a model of the relevant system is expressed and then only using the input and output data obtained from that model, control the defined angles with a separate model free adaptive data-driven control method. Finally, the performed simulations demonstrate the effectiveness of the proposed method for the TRMS, by using two difference reference signals named variable steps and sinusoidal.

In this paper, artificial intelligence is applied for real-time object detection in Tello quadcopters. For this purpose, the YOLOv3 detection algorithm is employed. The results indicate that the YOLOv3 network can detect the target with above 95 percent accuracy at a speed of 15 frames-per-second for different ambient lighting and background conditions. After detecting the target, the errors are calculated and given to the control system to track the target in real-time. The designed controllers efficiently follow the target and prevent flying robots from losing sight of the target.

A fault tolerant control is designed for a four-legged bird. This control consists of two parts: status control and position control. Position control is performed by a fuzzy controller and position control is performed by a PD controller. In the next step, the parity space method is implemented in order to diagnose and estimate the defect. In addition to finding the analytical relationship of the defect, in this article, position control will also be performed. Operator saturation and its effects on system performance is another issue not seen in reviewed articles. In this paper, operator saturation is considered and consequently the maximum fault tolerable by the system will be estimated. Using fault signals, control redesign operations have been performed to tolerate faults and correct control inputs; So using the PID controller, the annoying outputs created by the fault are zeroed. The defect is assumed to be of the operative type and two scenarios have been assumed for its occurrence.

In this paper, a model-independent adaptive sliding mode control method based on time-delay estimation (TDE) for a three degrees of freedom (3-DOF) helicopter in the presence of external disturbances and types of uncertainties is presented. In this approach, the switching gain of sliding mode is determined adaptively in order to increase the efficiency in tracking the reference path and reduce the chattering. In the adaptation law which causes rapid convergence to the sliding surface, a small and arbitrary neighborhood of sliding mode polynomials is used. In this neighborhood, it is considered that the derivatives of the adaptive gain are inversely proportional to the sliding variables. In this approach, to avoid using the dynamic model that is accompanied by modeling error, the time delay estimation approach has been used. In the time delay estimation, creating a time delay signal eliminates system dynamics and uncertainties. The uniformly ultimately bounded (UUB) stability of the closed-loop system is also shown. Finally, the efficiency of the proposed approach is investigated by studying the simulation on a 3-DOF helicopter.

This paper proposes an optimal H adaptive observer based on Linear Matrix Inequality (LMI) for fault estimation (FE) with a sliding mode adaptive fault tolerance (FTC) controller (ASM) to propose a fault for the three-degree helicopter model. Has been. In this approach, the system states and the effects of the types of faults (shrinkage, loss of efficiency and locking of the operator) occurring in the operator, uncertainties in system dynamics and operators in the presence of external perturbation and noise are estimated by the adaptive observer. The saturation phenomenon is also considered in this study. Since in practice, for the large control signals, the actuators become saturated, the saturation effect of the actuators is modeled and the saturation effect is estimated by the observer. In the end, simulation results are presented on the dynamics of three degrees of freedom helicopter to demonstrate the effectiveness of the proposed approach, which results in satisfactory and satisfactory performance of the proposed algorithm.

In this study, the effect of nanoparticles addition on the behavior of 12-layer glass/epoxy composite plates, under quasi-static shear loading, was investigated experimentally. In this research, the effect of parameters such as the addition of hydroxide modified carbon nanotubes to the composite structure, three loading speeds of 5, 250 and 500 mm/min and three forms of permeable geometry on quasi-static test results were investigated. The results showed that adding nanoparticles to the composite structure increased the strength, fracture strain and flexibility of the composite, which would allow the penetrant to exit the composite later. Also, as the loading rate increases, the strength of the composite against the permeant increases and as the permeate geometry changes, the fracture mechanism changes.

In this paper, a free model robust control is designed to track the position of three degrees of freedom (3-DOF) helicopter model in the presence of a variety of external uncertainties and disturbances. In this work, the adaptive time-delay control eliminates non-linear dynamics of helicopter, uncertainties, and external disturbances by generating a time-delay signal. The purpose of applying the adaptive law in the time-delay control is to online, automated and appropriate adjustment the gains in order to increase the speed of convergence and efficiency in the tracking operation in the presence of fluctuation tolerance. On the other hand, a sliding mode controller is used in the control structure to achieve robust performance against the time-delay estimation (TDE) error due to use of the time-delay signal. The uniformly ultimately bounded (UUB) stability of the closed-loop system has also been proved using Lyapunov stability theory. Finally, the effectiveness of the designed control approach is demonstrated using simulations on a 3-DOF helicopter in the presence of perturbations and uncertainties.

Quadrotor is an underactuated and nonlinear coupled system. in this paper for controlling the dynamic of the system, feedback linearization (FL) method is used to convert the nonlinear model to a simple linear one. Moreover, a combination of fractional order PID (FOPID) with FL is used to improve the tracking ability. Tuning the parameters of NFOPID, because of two more orders of integral and derivation is a complicated task; therefore neural networks (NNs) method is used to cope with this duty. Back propagation (BP) algorithm is used to train the weights of the NNs. Because of the flexibility and online learning of the NNs, the proposed controller can be robust against uncertainties and disturbances. The fractional order operator has infinite dimension and for practical implementation modified Oustaloup's method is used in this paper. and finally the results of the simulations also validate the effectiveness and robustness of the proposed scheme.

Rising fuel prices and limited fossil fuels have motivated scientists to find some new methods to recover the heat dissipation from the internal combustion engines exhaust gases in recent decades. Only 30 percent of the fuel energy is converted to the useful work and the rest of it is lost through the exhaust gases of the engine and the engine coolant system. In this paper this issue has been considered and hence two different configurations of organic Rankine cycle with two operating fluids R113 and R123 have been designed and energy and exergy analysis have been applied in order to recovering the heat dissipation from the six cylinder internal combustion engine exhaust gases (in full load operating mode). Next, the performance of these cycles has been optimized by sensitivity analysis to find the optimum working temperature and pressure of these two cycles. the results shows the optimum points of the system which is calculated by the mention technique.

In the current paper thermal buckling of cylindrical shells reinforced with GPL graphene sheets subjected to uniform temperature rise is investigated. Nanocomposite shell reinforced by graphene platelets (GPLs). It is assumed that the GPLs are randomly oriented and uniformly distributed along in each layer. Variation of volume fraction from each layer to other is based on the several functionally graded types. The effective material properties are obtained using the Halpin-Tsai rule. The equilibrium equations are obtained considering the first order shear deformation shell theory, Donnell assumption, and Von-karman type of geometrical nonlinearity. The linear obtained stability equations are discrete utilizing the generalized differential quadrature procedure along the shell domain. Then the eigenvalue problem is solved and critical buckling temperature is calculated. In the section of numerical results, after validation, the effects of geometric parameter, boundary conditions, mass fraction of GPL, and also type of functionally graded on the stability of structure are studied.

This paper presents the design and construction of a laboratory model for tracking a moving target object using image processing. The aerial robot is used as a follower and the ground robot is used as a target object. A one-degree-of-freedom robot is used instead of an aerial robot, and a moving mobile robot is used as a ground robot to move at different speeds. The distance error between the ground robot and the aerial robot is calculated using image processing and fed back to the aerial robot controller. The dynamic model is used to design the position controller. PID, PID-fuzzy controllers, and optimal linear integral control are designed using a dynamic model, and simulation is performed in MATLAB software. Using simulation to evaluate the performance of three controllers has been designed. The controller is selected using 4 criteria. The performance of the proposed controller is evaluated by implementing the controller on a laboratory model. The aerial robot controller for real-time tracking of the target object and the object of sight is not out air Robot. The novelty of this paper is the design of an inexpensive laboratory model for the real-time implementation of moving a target object with a moving tracker.

The Army of the Islamic Republic of Iran and the Islamic Revolutionary Guards Corps are two military armies of Velayat-e Faqih and the Islamic Republic of Iran's holy system, both of which are defending the country's existence and the political system and guarding national dignity. Stable national security is one of the most important goals and interests of the country that can be provided by the armed forces of the country. One of the important factors influencing national security in the conditions of the region is the unity and complementary of other armed forces, especially the Islamic Republic of Iran and the Revolutionary Guards Corps. The insecurities found in the Middle East over the last few years have led to the strengthening of the Islamic Republic of Iran's political and military situation in the region contrary to US desire. Iran's attempts to stabilize the region and confront the occupation of terrorist groups in Iraq and Syria have forced the United States to expose its scenario of complex psychological operations by increasing the threat of Iran's military presence to the region, one from these scenarios, creating divisions, divisions and bipolarity of our society is about different issues. The doping of the armed forces of Iran, especially the army and the Sepah Pasdaran, is one of the goals of these scenarios that could undermine national security. Therefore, in this paper, this unity and synergy are explained in accordance with the guidelines and views of the Supreme Leader Imam Khamenei.