Sharif Digital Repository

In this study, based on the reduced from of elasticity displacement field for a long laminate, an analytical method is established to exactly obtain the interlaminar stresses near the free edges of generally laminated composite plates under the extension and bending. The constant parameters, which describe the global deformation of a laminate, are properly computed by means of the improved first-order shear deformation theory. Reddys layerwise theory is subsequently utilized for analytical and numerical examinations of the boundary layer stresses within arbitrary laminated composite plates. A variety of numerical results are obtained for the interlaminar normal and shear stresses along the... 

Mobile robots as automatic machines have the capability to move around various environments and have considered because of wide range of applications in the industrial settings. It is vital for a mobile robot to determine its errors in indeterminate conditions and provide a robust and high performance controller along with trajectory control. Hence, the research has attempted to give a learning-based controller method for wheeled mobile robots in the presence of disturbance. The proposed method, use LQR controller and the Bat algorithm based on machine learning agents to calculate and identify control errors and satisfy the stability. The wheeled mobile robot should track the reference path... 

This study investigates the chaos control in the permanent magnet synchronous motor (PMSM) using a Lyapunov-based model predictive approach subject to data loss. PMSM, as a rich nonlinear dynamic, can demonstrate chaotic behavior when its parameters are in a certain area. Thus, the performance of the system will degrade in this condition. Moreover, in some networked applications, especially in the modern automation industry, data can be lost at the sensor-controller and controller-actuator links. It will lead the system to illustrate the chaotic behavior. Thus, by assuming a PMSM under data loss, a Lyapunov-based predictive model is applied to control the chaos in the PMSM in the presence of... 

Within elasticity theory, the reduced form of a displacement field is obtained for general cross-ply composite laminates subjected to a bending moment. The firstorder shear deformation theory of plates and Reddy's layerwise theory are then utilized to determine the global deformation parameters and the local deformation parameters appearing in the displacement fields, respectively. For a special set of boundary conditions an elasticity solution is developed to verify the validity and accuracy of the layerwise theory. Finally, various numerical results are presented within the layerwise theory for edge-effect problems of several cross-ply laminates under the bending moment. The results... 

This study investigates the leader-following formation control problem for the networked second-order autonomous arial robot systems under directed topology. It is assumed that the leader's velocity is time varying and formation control will be achieved under the assumption. The formation controller will be designed to form the desired formation of all followers and reached the consensus of velocity. Moreover, it has assumed that agents may expose to a false data injection as a cyber-attack and this affair can affect the transferred sensor information that agents share with each other and break the formation. Finally, a Kalman filter and a chi-square anomaly detector is proposed to detect... 

Within the tunneling Hamiltonian formulation for the eight-component spinors, the Josephson critical supercurrent has been calculated in a planar superconductor-normal graphene-superconductor junction. Coupling between superconductor regions and graphene is taken into account by a tunneling Hamiltonian which contains two types of tunneling, intravalley and intervalley tunneling. Within the present tunneling approach, we find that the contributions of two kinds of tunneling to the critical supercurrent are completely separable. Therefore, it is possible to consider the effect of the intervalley tunnelings in the critical supercurrent. The incorporation of these type of processes into the... 

In this study, based on the reduced form of elasticity displacement field for a long laminate, an analytical method is established to exactly obtain the interlaminar stresses near the free edges of generally laminated composite plates subjects to extension, torsion, and bending. The constant parameters being in the displacement field, which describe the global deformation of a laminate, are appropriately calculated by using the improved first-order shear deformation theory. Reddy's layerwise theory is subsequently employed for analytical and numerical examinations of the boundary layer stresses within arbitrary laminated composite plates. Various numerical results are developed for the... 

In this paper we define critical graphs as minimal graphs that support a given set of rates for the index coding problem, and study them for both the one-shot and asymptotic setups. For the case of equal rates, we find the critical graph with minimum number of edges for both one-shot and asymptotic cases. For the general case of possibly distinct rates, we show that for one-shot and asymptotic linear index coding, as well as asymptotic non-linear index coding, each critical graph is a union of disjoint strongly connected subgraphs (USCS). On the other hand, we identify a non-USCS critical graph for a one-shot non-linear index coding problem. In addition, we show that the capacity region of... 

Energy-harvesting devices have been widely used to generate electrical power. Through the use of energy harvesting techniques, ambient vibration energy can be captured and converted into usable electricity in order to create self-powering systems. In the present study, to further improve the efficiency of energy-harvesting devices, a nonlinear piezomagnetoelastic energy harvester is proposed in two different configurations that is parallel and series. In order to optimize the generated electrical power, the physical parameters of the harvester are chosen as the design variables. Classical and Metaheuristic algorithms, namely, random search, genetic algorithm, and simulated annealing are... 

Energy-harvesting devices have been widely used to generate electrical power. Through the use of energy harvesting techniques, ambient vibration energy can be captured and converted into usable electricity in order to create self-powering systems. In the present study, to further improve the efficiency of energy-harvesting devices, a nonlinear piezomagnetoelastic energy harvester is proposed in two different configurations that is parallel and series. In order to optimize the generated electrical power, the physical parameters of the harvester are chosen as the design variables. Classical and Metaheuristic algorithms, namely, random search, genetic algorithm, and simulated annealing are... 

Although viability of low-salinity waterflooding (LSWF) at the laboratory scale has been proven, there are some challenges associated with its field application, which sheds uncertainties on its economic success. One of the challenges is the minimum required volume of low-salinity water, which should be injected to the reservoir due to the salt dispersion in porous media. Once the low-saline brine is injected into the reservoir, mixing of injected (low-salinity) and resident (high-salinity) brines occurs and the developed mixing zone grows continuously as the front moves from the injection well toward the production well. Increase in the salinity of the front reduces the efficiency of LSWF.... 

In situ mixing by dispersive transport of salt and viscous fingering between the injected low-salinity (LS) brine and high-salinity (HS) formation brine can jeopardize the performance of low-salinity waterflooding (LSWF). In our previous papers, we demonstrated that in situ mixing can be suppressed by polymer-enhanced low-salinity waterflooding (PELS), in which a small amount of a viscosifying agent, such as a polymer, is added to the LS stream. Nevertheless, effective mixing control with PELS depends upon several factors and operational conditions, which have not yet been addressed. Therefore, this research focuses on the investigation of the impact of injection parameters, such as the... 

This paper presents an optimisation model for polymer electrolyte membrane fuel cell system based on simultaneous power maximisation and cost minimisation. The results show that, by employing appropriate relation between the objectives, the innovative design could be proposed. Genetic algorithm is applied to solve the optimisation problem. Power maximisation results reveal that at maximum amount of power (1.95 kW), unit cost of energy is $0.64. In contrast, minimisation of cost decreases unit cost of energy to $0.33. In this condition, output power is reduced approximately to 0.93 kW. To consider both optimisation problems concurrently, weighting method and Pareto set are employed. Our... 

In the present study, an analytical solution is proposed to determine the interlaminar stresses in long symmetric laminated composite plates subjected to shearing loads. An improved first-order shear deformation theory (IFSDT) and a simplified IFSDT (SIFSDT) are utilized to calculate the unknown constants appearing in the reduced elasticity displacement field which actually demonstrate the global deformations of the plate. Then the numerical values of the interlaminar normal and shear stresses are established through the laminates by using Reddy's layerwise theory. Finally, several numerical examples are presented to study the interlaminar stresses in the interfaces of the layers and through...