The physical model of an electrohydraulic actuation system with pressure-reducing cylinder end cushioning has been obtained. In order to arrive at the closure of the model, experimental models for actuator friction and the characteristics of the relief, non-return and proportional valves have been constructed. The variation in discharge through the proportional valve with both pressure and command signal has been modeled by training a neural network with experimental data. For the characterization of the discharge through the proportional valve, besides square root of the pressure drop in each metered orifice, polynomial forms of command signal for the discharge coefficients have been used. Such a direct characterization of the discharge with the command signal eliminates the orifice opening as an intermediate variable. A simple friction model that retains all the features of the existing complex models has been developed. Parameters such as maximum dynamic friction and the corresponding velocity have been introduced for this purpose. All these nonlinear subsystem models have been integrated together in MATLAB/Simulink frame to predict the actuation dynamics. The variations in the predicted and experimental displacements of the piston against different command signals have been found to be quite close to each other.

The role of hydraulic systems is quite evident especially in the case of heavy machineries employed in industries, where the utilisation of high forces amid large stiffness is the prerequisite. Nevertheless, there has been substantial effort put forward in the development of advanced control strategies which finally addressed the issue of the position control. Proportional–integral–derivative control strategy happens to be one among them, which is a versatile and widely renowned approach involved in the position control in this study. Although, it is quite frequently observed that the hydraulic actuation system possesses strong nonlinearities. In this article, two different actuator position control strategies, that is, swash plate control of main pump and speed control strategy of prime mover are compared. In swash plate control strategy, the proportional–integral–derivative controller adjusts the swash plate of main pump through servo mechanism, whereas in the speed control strategy, the proportional–integral–derivative controller adjusts the speed of the electric motor through variable-frequency drive. For this purpose, two MATLAB-Simulink models are developed and validated experimentally. It is found that swash plate control strategy has better dynamic and control performance than the speed control strategy catering same position demand of the linear actuator.

Transverse vibration creates strong vorticity to the plane perpendicular to flow direction which leads to the radial mixing of fluid and, therefore, the results of heat transfer are significantly improved. Comparative studies of effects on heat transfer were investigated through a well-valid CFD model. Water and water-based nanofluid were selected as working substances, flowing through a pipe subjected to superimposed vibration applied to the wall. To capture the vibration effect in all aspects; simulations were performed for various parameters such as Reynolds number, solid particle diameter, volume fraction of nanofluid, vibration frequency, and amplitude. Temperature, solid particle diameter and volume fractiondependent viscosity have been considered; whereas, the thermal conductivity of nanofluid has been defined to the function of temperature, particle diameter and Brownian motion. Due to transverse vibrations, the thermal boundary layer is rapidly ruined. It increases the temperature in the axial direction for low Reynolds number flow that results in high heat transfer. As the Reynolds number increases, vibration effect is reduced for pure liquid, while there is noticeable increase for nanofluid. The rate of increment of heat transfer by varying volume fraction and particle diameter shows the usual feature as nanofluid under steady-state flow, but when subjected to vibration is much higher than pure liquid. As the frequency increases, the vibration effects are significantly reduced, and in amplitude they are profounder than frequency. The largest increase of about 540% was observed under the condition of vibrational flow compared to a steady-state flow.

Introduction:The purpose of the present study was to design, develop, and characterize the transdermal patches containing Simvastatin for the management of blood lipid levels. Materials and Methods: Transdermal patches of Simvastatin were prepared by the solvent casting method. The prepared patches were evaluated for physicochemical characteristics such as thickness, weight variation, folding endurance, percentage moisture uptake, percentage moisture content, percentage drug content, and ex-vivo permeation study. Eudragit polymer grades ERL100 and ERS100 were used in 6:4 and 8:2 ratio to prepare the formulations. Formulations were prepared using 2 3 factorial designs. Stability studies of the films were subjected to the environmental conditions at a temperature of 45°C, 75% relative humidity for 45 days. Results: The permeation parameters like flux, amount of drug permeated, and permeability coefficient were obtained. It was found that all these values were highest for formulation F8. Conclusion: Based on all parameters, formulation F8 was considered as the best formulation.

ABSRACTVehicular ad hoc network (VANET) is an important component of Intelligent Transportation Systems. In VANET, active safety systems is seems as the main benefit of it, in which vehicles are exchanging safety messages to increase the passenger safety on road. At the present time, vehicles are exposed to many security threats; and for the security, availability of network is must be obtained at every time. The availability of the network is extremely needed when a vehicle sends any safety information to other one. In this regard, DoS attacks are very dangerous in VANET because they adversely affect the network availability. One of them is oppress the node resources by flooding of messages to the victim vehicle; which is a common form of Denial of Service (DoS) attacks, in which a malicious node sends a large number of (False) safety message to the victim node. In this paper, an efficient method is proposed to defend against DoS attacks. According to our method each vehicle in a network has limited capacity of massage (safety message) receiving, without having any security risk and this limited capacity is defined by our (QLA) algorithm. This is a very simple method and can be easily deploy in network. Simulation results show that the approach is very effective and efficient against denial of service attack in VANET.