Search

This paper considers the vehicle control process in emergency lane change (ELC). The control method is divided into two parts: before crossing the obstacle and after crossing it. The first part is done by a feed-forward controller inspired by the driver’s behavior pattern in the ELC maneuver. This controller is compensated by a neural network system and two proportional-integral (PI) and proportional-derivative (PD) controllers, which correct the output of the feed-forward controller to follow the path more accurately. The second part consists of two PD controllers responsible for controlling and steering the vehicle in the main path after crossing the obstacle. The main novelty of the proposed method is that the computational burden is low because of using a feed-forward controller, which is the main source of the calculation’s burden. So as a result, the controller system can cover the ELC maneuver in under 2 seconds in various lateral displacements to bypass the obstacle and prevent collisions. The co-simulations are performed in CarSim software and MATLAB/Simulink, which shows that the control system can appropriately steer the vehicle and follow the desired at different speeds, in the presence of road friction and parameter uncertainty.

The vibration analysis and control of containers with heavy loaded fluid is undertaken in this paper. The problem of fluid–structure vibration is viewed and analyzed from several viewpoints including both analytical methods and numerical techniques. In order to effectively control the fluid–structure vibration, one of the side walls is made flexible where two piezoelectric patches are utilized to sense the distributed displacements resulting from fluid-structure movements, while the other one is used to actively control the vibration. For this, a boundary control technique is used to actively control the multi-modal vibration of fluid–structure. The simulation results for the analytical models are further validated using a comprehensive finite element method. Before applying the proposed controller, the results show that the fluid vibration is different in different heights and distances. However, the simulation results indicate that the piezoelectrically-excited beam is able to suppress the vibrations of all the positions very effectively and quickly. These results prove the feasibility of utilizing piezoelectrically-excited beams in vibration control of fluid–structure.

In this paper, boundary control of a composite shell vibrations containing fluid (partially filled with a fluid) is studied. The linear boundary control laws consisting of forces and moments from the boundaries of the composite shell stabilize the vibrations. The fluid has free surface and boundary stabilization is attained without using in domain attached actuators. This research utilizes semigroup techniques and LaSalle invariant set theorem to prove the boundary stabilization.

This article seeks to detect urban change by integrating multi-temporal remotely sensed data over a 19-year period in Gorgan area of Golestan Province in north of Iran. The authors demonstrate that mostly range and agricultural land have changed into residential areas, and establish parameters that can used to assess the rate of change. Such tools can produce information that helps managers make more informed decisions on urban expansion, conservation and sustainable use.

In this paper, general spatial trajectory tracking problem of a flexible plate is studied. To obtain dynamic equations of motion of the plate, Hamiltonian dynamics is used and then Lagrange’s equations of the plate dynamics and the corresponding expressions for boundary conditions are derived. Resulting equations show that the coupled plate dynamics including plate vibration and its rigid spatial motion take place in two different time domains. By using two-time scale (TTS) control theory, a control scheme is elaborated that makes the orientation and position of selected points of the plate track a desired trajectory while suppressing the plate’s vibration. TTS composite controller has two parts: one is a tracking controller designed for the slow (rigid) subsystem, and the other one is a stabilizing controller for the fast (flexible) subsystem. For the fast subsystem, the proposed boundary control method does not require any information about vibration of the interior points of the plate; nor requires discretizing the partial differential equation of the plate vibration to a set of ordinary differential equations. This part of the control commands consists of feedback of the velocities at the boundary points of the plate. So, the method avoids the need for instruments to measure data from vibration of any points inside the plate or designing an observer for estimating this information. Also the proposed method prevents control spillover due to discretization and resorting to truncation of the model. Simulation results show that the fast stabilizing control commands at the boundary are able to remove undesirable vibration of the flexible plate and the slow controller provides very good trajectory tracking with acceptable actuating forces/moments.

There are two main approaches for prediction of the mechanical properties of composite materials; macro-mechanical and micro-mechanical approaches. At the micromechanical level, analytical, experimental, and semi-empirical methods have been developed to predict the stiffness of composite materials. In this study, these methods have been reviewed and modified to predict the damping properties of composites. In order to validate these theories, experimental techniques using a universal testing machine were performed to extract the specific damping capacity (SDC). The results show that the presented experimental technique can be employed successfully to measure the damping and stiffness properties of composites. In addition, it is concluded that semi-empirical approaches that consider the experimental correlation factors are closer to reality than purely analytical micromechanical methods. This study shows that the analytical micromechanical approaches are not suitable to predict the damping properties because of different mechanisms of energy dissipation that have not been discussed in this article.