نتایج جستجو برای: cylindrical structure

تعداد نتایج: 1589059  

پایان نامه :وزارت علوم، تحقیقات و فناوری - دانشگاه صنعتی امیرکبیر(پلی تکنیک تهران) - دانشکده مهندسی مکانیک 1387

هدف از این پژوهش استفاده از روش المان محدود به منظور تحلیل ارتعاشات پیوسته استوانه ای ..با لایه های پیزوالکتریک می باشد. به این منظور ابتدا پاسخ استاتیکی پیوسته فوق تحت بار مکانیکی و الکتریکی به دست آمده است و سپس فرکانسهای طبیعی و همچنین پاسخ دینامیکی چنین پوسته ای مطالعه گردیده است. در ابتدا معادلات حاکم بر رفتار دینامیکی پوسته استوانه ای ..با لایه های پیزوالکتریک با استفاده از اصل هامیلتون ...

2010
H. N. G. Wadley

Two ultrasonic techniques for reconstructing the internal temperature distribution in metal bodies-timeof-flight tomography and dimensional resonance profiling-are described. An analysis of the tomographic reconstruction of temperature (including ray refraction effects) in a cylindrical body is presented together with initial experimental results. Dimensional resonance profiling is a new techni...

Journal: :Philosophical transactions. Series A, Mathematical, physical, and engineering sciences 2009
Rebecca Vandiver Alain Goriely

Cylindrical forms are among one of Nature's fundamental building blocks. They serve many different purposes, from sustaining body weight to carrying flows. Their mechanical properties are generated through the often complex arrangements of the walls. In particular, in many structures that have elastic responses, such as stems and arteries, the walls are in a state of tension generated by differ...

Journal: :Physical review letters 2001
L Hornekaer N Kjaergaard A M Thommesen M Drewsen

We report on structural properties of two-component Coulomb crystals in a linear Paul trap. The crystals consist of two laser cooled ion species, 24Mg+ and 40Ca+. The lighter 24Mg+ ions form an inner cylindrical crystal structure surprisingly similar to that of an infinitely long single component crystal, while the outermost shell of the surrounding 40Ca+ ions have a spheroidal shape, which is ...

2015
Wenbo Duan Fengshou Gu Iain Dupère Shan Zhong Andrew Ball

The free vibration of a fluid/structure system consisting of a cylindrical blockage submerged in a liquid enclosed by a cylindrical shell is investigated for the purpose of pipe line transportation monitoring. The wavenumbers are obtained and the reflection and transmission characteristics of these waves at the blockage interfaces are investigated theoretically. Reflection and transmission rati...

2004
Ravish S. Masti M. G. Sainsbury

Cylindrical shells are used in a variety of applications. In some of these applications it is necessary to limit the vibrations of lightly-damped shells by applying a damping treatment that does not significantly increase the weight. This paper explores the use of partial coating of a cylindrical shell with a constrained viscoelastic layer for obtaining optimal damping. The placement of damping...

2006
Halim Boutayeb Anne-Claude Tarot Kouroch Mahdjoubi H. Boutayeb

The focusing characteristics of 2D-Cylindrical Electromagnetic Band Gap (CEBG) structures constituted of metallic wires and with defects are analyzed numerically for directive antennas application. The introduction of defects into the periodic structures consists of removing one or multiple wires. The simulations were carried out with a Finite Difference Time Domain (FDTD) code, where the excit...

2011
J. A. Brandão Faria

A matrix technique for the computation of the perunit-length internal impedance of radially inhomogeneous cylindrical structures is presented. The cylindrical structure is conceptually divided into a number of layers, each layer being characterized by its constitutive parameters, conductivity, permeability, and permittivity. Within this general framework, compound conductors, compound capacitor...

Journal: :Nanotechnology 2009
Ch Deneke J Schumann R Engelhard J Thomas C Müller M S Khatri A Malachias M Weisser T H Metzger O G Schmidt

The structure and magnetic properties of an InGaAs/Fe(3)Si superlattice in a cylindrical geometry are investigated by electron microscopy techniques, x-ray diffraction and magnetometry. To form a radial superlattice, a pseudomorphic InGaAs/Fe(3)Si bilayer has been released from its substrate self-forming into rolled-up microtubes. Oxide-free interfaces as well as areas of crystalline bonding ar...

2009
Simeon Trieu Xiaomin Jin Bei Zhang Tao Dai Kui Bao Xiang-Ning Kang Guo-Yi Zhang

The Gallium Nitride (GaN) Light-Emitting-Diode (LED) bottom refection grating simulation and results are presented. A microstructure GaN bottom grating, either conical holes or cylindrical holes, was calculated and compared with the non-grating (flat) case. A time monitor was also placed just above the top of the LED to measure both time and power output from the top of the LED. Many different ...

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