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Beam System (beam + system)

Distribution by Scientific Domains
Engineering85%

Selected Abstracts

Fuzzy sliding-mode control with rule adaptation for nonlinear systems

EXPERT SYSTEMS, Issue 4 2006
Lon-Chen Hung
Abstract: A fuzzy sliding-mode control with rule adaptation design approach with decoupling method is proposed. It provides a simple way to achieve asymptotic stability by a decoupling method for a class of uncertain nonlinear systems. The adaptive fuzzy sliding-mode control system is composed of a fuzzy controller and a compensation controller. The fuzzy controller is the main rule regulation controller, which is used to approximate an ideal computational controller. The compensation controller is designed to compensate for the difference between the ideal computational controller and the adaptive fuzzy controller. Fuzzy regulation is used as an approximator to identify the uncertainty. The simulation results for two cart,pole systems and a ball,beam system are presented to demonstrate the effectiveness and robustness of the method. In addition, the experimental results for a tunnelling robot manipulator are given to demonstrate the effectiveness of the system. [source]

Quantitative structural damage detection using high-frequency piezoelectric signatures via the reverberation matrix method

INTERNATIONAL JOURNAL FOR NUMERICAL METHODS IN ENGINEERING, Issue 5 2007
W. Yan
Abstract High-frequency structural analysis so far has been a major issue in dynamic analysis, for which many conventional methods such as finite element method and transfer matrix method are unable to perform well. Since the electromechanical impedance technique for structural health monitoring (SHM) operates at very high frequencies, the reverberation matrix method (RMM), which was just developed a few years ago, is employed to study dynamics of the monitored structures, which are bonded with piezoelectric lead zirconate titanate (PZT) patches. A piecewisely homogeneous Euler,Bernoulli beam model is introduced to approximate the non-homogeneous beam and only one-dimensional axial vibration of PZT wafers is considered. The imperfect interfacial bonding between PZT patches and the host beam is investigated based on a shear lag model. Using a hybrid technique combining electromechanical impedance method and RMM, an analytical expression of impedance (or admittance) related to the response of the coupled model of PZT patch-bonding layer-host beam system is derived for SHM. The proposed method is examined by comparing with other theoretical methods as well as by means of a test on an intelligent system using a steel beam with two symmetrically installed PZT wafers. It could be further applied to predicting the dynamics of monitored Timoshenko beams, continuous beams, and framed structures as well. Copyright © 2006 John Wiley & Sons, Ltd. [source]

Triangular planar array of a pyramidal adaptive antenna for satellite communications at 1.7 GHz

MICROWAVE AND OPTICAL TECHNOLOGY LETTERS, Issue 11 2009
J. L. Masa-Campos
Abstract Nowadays, satellite communications are basic for the human lifestyle. In this way, a smart, conformal, and multiarray antenna (GEODA) is being developed in order to receive signals from several satellites simultaneously in the 1.7 GHz working band. An adaptive beam system is able to follow the signals from the satellite constellation. The complex structure of the antenna is based in a 3D composition of planar arrays with triangular shape. These arrays are divided into subarrays of three patches (Cells), composing the single control element for the arrays main beam direction management. Fifteen cells (45 radiating elements) compose each triangular array of the GEODA antenna. In this article, a triangular array prototype is implemented and measured. Likewise, an individual characterization of the array components is presented. © 2009 Wiley Periodicals, Inc. Microwave Opt Technol Lett 51: 2633,2639, 2009; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.24692 [source]

Nanostructuring of an AlGaInP light emitting diode for surface plasmon enhanced emission of light output

PHYSICA STATUS SOLIDI (A) APPLICATIONS AND MATERIALS SCIENCE, Issue 8 2008
R. M. Perks
Abstract This work describes a successful post fabrication method of applying a plasmonic grating to the surface of a mounted AlGaInP LED device. A Carl Zeiss 1540 XB Focused Ion beam system was used to mill holes in a thin gold layer with a periodicity of around 540 nm. Measurements of the total light output of the device compared with a standard un-textured device show that the plasmonic grating was found to significantly affect the light output characteristics such that the overall light output was reduced. This is attributed to the fact that only p-polarised light can interact with the hole array. Furthermore, the onset of saturation in the textured device was not evident as compared with the un-textured device. This is attributed to improved current spreading in the device due to the top gold layer. (© 2008 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [source]

Damped vibrations of the beam systems in rotational transportation

PROCEEDINGS IN APPLIED MATHEMATICS & MECHANICS, Issue 1 2009
kiewskiArticle first published online: 5 MAR 2010
The major aim of this thesis is dynamical analysis of systems in rotational transportation with taking into consideration in the mathematical models the damping forces. The dissipation of energy in form of damping is inseparable connected with motion of analyzed systems. Up to now modelling of rod and beam systems in transportation was very often based on simplification and reduction of damping effect and on the other side the considerations very rarely apply to systems where the transportation effect was took into consideration. In this thesis the dynamical flexibility of the damped beam systems in transportation was presented. Analyzing systems were assumed as simple homogenous beam systems with symmetrical cross-section constant on whole length of the system. Most popular technical applications of such systems are put into use in propellers and sails of wind power plant, main, auxiliary rotors of helicopters, turbines, etc. (© 2009 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim) [source]