Current Issue : April - June Volume : 2017 Issue Number : 2 Articles : 5 Articles
In order to prevent the backward flow of piezoelectric pumps, this paper presents\na single-active-chamber piezoelectric membrane pump with multiple passive check valves. Under the\ncondition of a fixed total number of passive check valves, by means of changing the inlet valves and\noutlet valves� configuration, the pumping characteristics in terms of flow rate and backpressure are\nexperimentally investigated. Like the maximum flow rate and backpressure, the testing results show\nthat the optimal frequencies are significantly affected by changes in the number inlet valves and\noutlet valves. The variation ratios of the maximum flow rate and the maximum backpressure are up\nto 66% and less than 20%, respectively. Furthermore, the piezoelectric pump generally demonstrates\nvery similar flow rate and backpressure characteristics when the number of inlet valves in one kind of\nconfiguration is the same as that of outlet valves in another configuration. The comparison indicates\nthat the backflow from the pumping chamber to inlet is basically the same as the backflow from the\noutlet to the pumping chamber. No matter whether the number of inlet valves or the number of outlet\nvalves is increased, the backflow can be effectively reduced. In addition, the back pressure fluctuation\ncan be significantly suppressed with an increase of either inlet valves or outlet valves. It also means\nthat the pump can prevent the backflow more effectively at the cost of power consumption. The pump\nis very suitable for conditions where more accurate flow rates are needed and wear and fatigue of\ncheck valves often occur....
A feedback control system for mitigating flow separation was developed by using a string-type dielectric-barrier-discharge (DBD)\nplasma actuator and a fiber Bragg grating (FBG) sensor. Tangential jets were induced from the string-type DBD plasma actuator,\nwhich was located at 5% chord from the leading edge of an NACA0024 airfoil.The FBG sensor was attached to the interior surface\nnear the root of the cantilever beam modeled on the pressure surface of the airfoil.The strain at the cantilever root was reflected in\nthe form of Bragg wavelengths (...
Active front steering (AFS) is an emerging technology to improve the vehicle cornering\nstability by introducing an additional small steering angle to the driver�s input. This paper proposes\nan AFS system with a variable gear ratio steering (VGRS) actuator which is controlled by using the\nsliding mode control (SMC) strategy to improve the cornering stability of vehicles. In the design of\nan AFS system, different sensors are considered to measure the vehicle state, and the mechanism of\nthe AFS system is also modelled in detail. Moreover, in order to improve the cornering stability of\nvehicles, two dependent objectives, namely sideslip angle and yaw rate, are considered together in\nthe design of SMC strategy. By evaluating the cornering performance, Sine with Dwell and accident\navoidance tests are conducted, and the simulation results indicate that the proposed SMC strategy is\ncapable of improving the cornering stability of vehicles in practice....
Hydraulic power and other kinds of disturbance in a linear motor-direct drive actuator (LM-DDA) have a great impact on the\nperformance of the system. A mathematical model of the LM-DDA system is established and a double-loop control system is\npresented. An extended state observer (ESO) with switched gain was utilized to estimate the influence of the hydraulic power and\nother load disturbances. Meanwhile, Radial Basis Function (RBF) neural network was utilized to optimize the parameters in this\nintelligent controller. The results of the dynamic tests demonstrate the performance with rapid response and improved accuracy\ncould be attained by the proposed control scheme....
In this paper the practical possibilities of strength verification analysis of composite\nmaterials used in the manufacture of selected components of railway wagons are presented.\nReal laboratory stand for measurements in a scale controlled by PLC controller were made.\nThe study of different types of connections of composite materials with sheet metal is\npresented. In one of the chapter of this paper principles construction of testing stand with\npneumatic cylinder were presented. Mainly checking of displacements and stresses generated\non the sheet as a result of pneumatic actuators load for composite boards was carried out. The\nuse of the controller with operating panel allows to easy programming testing cycle. The user\ncan define the force generated by the actuator by change of air pressure in cylinder.\nAdditionally the location of acting cylinders and their jump can be changed by operator. The\nexamination of the volume displacements was done by displacement sensor, and the tensile\nstrain gauge. All parameters are written in CatmanEasy - data acquisition software. This article\npresents the study of stresses and displacements in the composite plates joined with sheet\nmetal, in summary of this article, the authors compare the obtained results with the computer\nsimulation results in the article: \"Simulation of stresses in an innovative combination of\ncomposite with sheet\"....
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