Study of three-dimensional optical-transformation devices based on analytical field-transformation theory

2010 ◽  
Author(s):  
Qiang Cheng
Keyword(s):  
Three Dimensional ◽  
Transformation Theory ◽  
Field Transformation ◽  
Optical Transformation

Three Dimensional Modeling and Aerodynamic Analysis of MW Wind Turbine Blade

2011 ◽  
Vol 305 ◽  
pp. 274-278
Author(s):  
Hong Pan ◽  
Wen Lei Sun ◽  
Lian Ying He
Keyword(s):  
Wind Turbine ◽  
Turbine Blade ◽  
Three Dimensional ◽  
Aerodynamic Performance ◽  
Wind Turbine Blade ◽  
Transformation Theory ◽  
Aerodynamic Analysis ◽  
Blade Element Theory ◽  
Three Dimensional Modeling ◽  
Dimensional Modeling

Wind turbine blade is one of the key components of wind turbine, and its aerodynamic performance largely determine the reliability of wind turbine. This paper use the momentum - blade element theory, and correction by Prandtl, Wilson correction, Glauert correction and other methods to modify the model of the blade to come to the aerodynamic model, then using the point of the coordinate transformation theory each the airfoil two dimensional coordinate will conversion into space coordinates, using UG of three-dimensional modeling software to model, and finally the aerodynamic performance of airfoil is analyzed. Through modeling and aerodynamic analysis, for the following structure optimization and control strategy laid a foundation.

Homogeneous near-perfect invisible ground and free space cloak

2017 ◽  
Vol 31 (09) ◽  
pp. 1750059 ◽  
Author(s):  
Mohamad Fazeli ◽  
Seyyed Hassan Sedighy ◽  
Hamid Reza Hassani
Keyword(s):  
Incident Wave ◽  
Free Space ◽  
Single Step ◽  
Wave Direction ◽  
Transformation Theory ◽  
Design Flexibility ◽  
Mapping Process ◽  
Optical Transformation ◽  
Constitutive Parameters ◽  
Incident Wave Direction

A general approach to design near perfect invisible ground and free space cloaks is introduced in this paper. The proposed method which is based on the optical transformation theory, leads to homogeneous constitutive parameters for the cloaks without any singularities. Moreover, the single-step mapping process with linear relations achieves an uncomplicated designing process. Invisibility performance obtained by using this approach does not depend on the incident wave direction, also. The simplicity and design flexibility of the introduced approach with the homogeneity of extracted parameters greatly facilitate the design and fabrication processes of the both proposed ground and free space invisible cloaks. The numerical simulations prove the capability and universality of the proposed design approach.

FDTD Study of the Surface Waves Detection in Apertureless Scanning Near-Field Microscopy

2008 ◽  
Author(s):  
G. Parent ◽  
S. Fumeron ◽  
D. Lacroix
Keyword(s):  
Surface Waves ◽  
Near Field ◽  
Fdtd Method ◽  
Three Dimensional ◽  
Far Field ◽  
Dimensional Model ◽  
Three Dimensional Model ◽  
Experimental Tool ◽  
Field Transformation ◽  
Difference Time

Recent studies have shown the importance of surface waves in heat transfer near interfaces. The scanning near field optical microscopy (SNOM) provides an experimental tool to investigate the thermal electromagnetic field near surfaces. In this work, we present a three dimensional model of SNOM devices. This model is based on the finite-difference-time domain (FDTD) method associated to a near to far field transformation. Near field and far field scattered by a silicon tetrahedral tip and by a pecfectly conducting one are presented and discussed.

Optical Transformation Theory

Metamaterials ◽  
2009 ◽  
pp. 21-48 ◽  
Author(s):  
Wei Xiang Jiang ◽  
Tie Jun Cui
Keyword(s):  
Transformation Theory ◽  
Optical Transformation

scholarly journals Three-dimensional omnidirectional acoustic illusion

2021 ◽  
Author(s):  
Chuanjie Hu ◽  
Yuhang Yin ◽  
Huanyang Chen
Keyword(s):  
Acoustic Waves ◽  
Three Dimensional ◽  
Acoustic Metamaterials ◽  
Transformation Theory ◽  
Precise Control ◽  
Fabry Perot ◽  
Sonar Systems ◽  
Novel Method ◽  
Passive Acoustic ◽  
Incident Waves

Abstract Acoustic waves are ubiquitous in human everyday experience, therefore, precise control over the deformation of acoustic waves is always extremely desirable, which can be used, for example, to transform or hide objects from incident waves. Acoustic illusion devices are generally implemented by transformation acoustics, which can deceive ears or sonar systems. Challenges remain, the complexed and extreme material parameters prescribed by coordinate transformation theory make the implementations particularly difficult, even with the help of acoustic metamaterials. Here, a novel method based on Fabry-Perot resonances offers a feasible solution for achieve three-dimensional (3D) omnidirectional passive acoustic illusion. We theoretically demonstrated perfect 3D acoustic illusion via Mie theory, reduced version is further designed numerically and implemented experimentally. In the future, our work opens new possibilities for the implementation of modern acoustic illusion devices, such as camouflage for anti-sonar detection.

Numerical Analysis of the Iridescent Ring Around Cavitation Erosion Pit on Stainless Steel Surface

2016 ◽  
Vol 138 (9) ◽  
Author(s):  
Fu Mengru ◽  
Ge Han
Keyword(s):  
Stainless Steel ◽  
Numerical Analysis ◽  
Stress Concentration ◽  
Steel Surface ◽  
Cavitation Erosion ◽  
Three Dimensional ◽  
Ultrasonic Cavitation ◽  
Stainless Steel Surface ◽  
Energy Transformation ◽  
Transformation Theory

In ultrasonic cavitation, iridescent rings always occur around erosion pits on steel surface. These colorful halos can reflect the experienced temperature of the steel surface, but the reason for their formation is controversial. In this study, the development of an erosion pit and the iridescent ring around it on stainless steel (1Cr18Ni9Ti) surface was numerically investigated based on the energy transformation theory. The results revealed that the experienced temperature of ring areas with the shape of three-dimensional hemisphere could reach as high as 1685 K, and the position of material's highest temperature was exactly at the position of stress concentration.

Ear Recognition Based on Point Feature

2013 ◽  
Vol 380-384 ◽  
pp. 3840-3845
Author(s):  
Ying Tian ◽  
De Bin Zhang
Keyword(s):  
Force Field ◽  
Recognition Rate ◽  
Image Resolution ◽  
Feature Points ◽  
Transformation Theory ◽  
Scale Invariant ◽  
Ear Recognition ◽  
Field Transformation ◽  
Human Ear ◽  
Point Feature

In order to improve recognition rate of human ear, a method based on point feature of image for ear recognition is proposed in this paper. Firstly force field transformation theory is applied to human ear image two times in our method. It can extract the structural feature points and contour feature points of ear respectively and compose feature point set. Then feature points described by the scale invariant feature transformation descriptor. At last nearest neighbor classifier is employed for ear recognition. Feature points extracted from ear image using force field transformation are stable, reliable and discriminative, and they are insensitive to variations in image resolution. Constructing descriptor can resolve the problems caused by lower recognition owing to illumination change, scaling transformation, rotation and minute alteration caused by pose transformation. The experimental results show that the proposed algorithm not only can effectively improve ear recognition rate but also has quite good robustness.

A New Method to Measure Inertial Parameters of Rigid Body Based on Energy Decay Theory

2010 ◽  
Vol 146-147 ◽  
pp. 151-155
Author(s):  
Ning Sun ◽  
Jin Wang ◽  
Fang Hua Lei
Keyword(s):  
Reference System ◽  
Three Dimensional ◽  
Measuring Method ◽  
Energy Decay ◽  
Moment Of Inertia ◽  
New Method ◽  
Transformation Theory ◽  
Inertial Parameters ◽  
Rotation Transformation ◽  
The Moment

Most measuring methods used now can only measure the rigid body’s six inertial parameters like the moment of inertia, the product of inertia and the centre of inertia toward to two-dimensional reference system. So a new method which can measure all the nine inertial parameters toward to three-dimensional reference system is proposed. The moment of inertia of object rotating the axis is obtained by energy decay method. Through using the translation and rotation transformation theory of product of inertia, the formula of moment of inertia including the information of product of inertia and centre of inertia is deduced. Then equations are built to solve all the parameters. Furthermore, a measuring instrument is designed based on the aerostatic bearing. Results show that this new method is available and by analyzing the experimental data, suggestions are made to improve this measuring method.

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