Effective property evaluation and analysis of three-dimensional periodic lattices and composites through Bloch-wave homogenization

2019 ◽  
Vol 145 (3) ◽  
pp. 1259-1269 ◽  
Author(s):  
Ganesh U. Patil ◽  
Kathryn H. Matlack
Keyword(s):  
Three Dimensional ◽  
Effective Property ◽  
Bloch Wave ◽  
Property Evaluation

scholarly journals A Low-Complexity Region-Based Authentication Algorithm for 3D Polygonal Models

2017 ◽  
Vol 2017 ◽  
pp. 1-11 ◽  
Author(s):  
Yuan-Yu Tsai ◽  
Tsung-Chieh Cheng ◽  
Yao-Hsien Huang
Keyword(s):  
Three Dimensional ◽  
Low Complexity ◽  
Secret Key ◽  
Authentication Code ◽  
Geometrical Properties ◽  
Property Evaluation ◽  
Adaptive Embedding ◽  
Local Properties ◽  
Embedding Rate ◽  
Polygonal Models

This study proposes a low-complexity region-based authentication algorithm for three-dimensional (3D) polygonal models, based on local geometrical property evaluation. A vertex traversal scheme with a secret key is adopted to classify each vertex into one of two categories: embeddable vertices and reference vertices. An embeddable vertex is one with an authentication code embedded. The algorithm then uses reference vertices to calculate local geometrical properties for the corresponding embeddable vertices. For each embeddable vertex, we feed the number of reference vertices and local properties into a hash function to generate the authentication code. The embeddable vertex is then embedded with the authentication code, which is based on a simple message-digit substitution scheme. The proposed algorithm is of low complexity and distortion-controllable and possesses a higher and more adaptive embedding capacity and a higher embedding rate than most existing region-based authentication algorithms for 3D polygonal models. The experimental results demonstrate the feasibility of the proposed algorithm.

Manufacturing Technique and Property Evaluation of RFPET/TPET Hybrid Nonwoven Fabric

2013 ◽  
Vol 365-366 ◽  
pp. 1165-1168
Author(s):  
Jia Horng Lin ◽  
Ya Lan Hsing ◽  
Wen Hao Hsing ◽  
Jin Mao Chen ◽  
Ching Wen Lou
Keyword(s):  
Tensile Strength ◽  
Polyethylene Terephthalate ◽  
Three Dimensional ◽  
Far Infrared ◽  
Nonwoven Fabric ◽  
Air Permeability ◽  
Infrared Emissivity ◽  
Environment Protection ◽  
Nonwoven Fabrics ◽  
Property Evaluation

Heat energy plays a significant role in resources and industries, which makes the development of energy-saving and thermal retention materials important to environment protection. This study combines three-dimensional hollow Polyethylene Terephthalate (TPET) fibers, recycled far-infrared polyethylene terephthalate (RFPET) fibers, and low melting temperature polyethylene terephthalate (LPET) fibers at various ratios to make the RFPET/TPET hybrid nonwoven fabric. The tensile strength, tearing strength, air permeability, and far infrared emissivity of the fabrics are evaluated. With a blending ratio of 8:0:2, the hybrid nonwoven fabrics have the optimum tensile strength of 145 N, tear strength of 184 N, and air permeability of 205 cm3/cm2/s.

scholarly journals Analytical formulation of three-dimensional dynamic homogenization for periodic elastic systems

2012 ◽  
Vol 468 (2142) ◽  
pp. 1629-1651 ◽  
Author(s):  
A. N. Norris ◽  
A. L. Shuvalov ◽  
A. A. Kutsenko
Keyword(s):  
Effective Medium Theory ◽  
Equations Of Motion ◽  
Three Dimensional ◽  
Expansion Method ◽  
Bloch Wave ◽  
Dimensional System ◽  
Medium Theory ◽  
Material Parameters ◽  
Elastic Systems ◽  
Arbitrary Frequency

Homogenization of the equations of motion for a three-dimensional periodic elastic system is considered. Expressions are obtained for the fully dynamic effective material parameters governing the spatially averaged fields by using the plane wave expansion method. The effective equations are of Willis form with coupling between momentum and stress and tensorial inertia. The formulation demonstrates that the Willis equations of elastodynamics are closed under homogenization. The effective material parameters are obtained for arbitrary frequency and wavenumber combinations, including but not restricted to Bloch wave branches for wave propagation in the periodic medium. Numerical examples for a one-dimensional system illustrate the frequency dependence of the parameters on Bloch wave branches and provide a comparison with an alternative dynamic effective medium theory, which also reduces to Willis form but with different effective moduli.

Effective Dynamic Properties of Microstructured Heterogeneous Materials

2012 ◽  
Author(s):  
Ankit Srivastava ◽  
Sia Nemat-Nasser
Keyword(s):  
Wave Propagation ◽  
Explicit Form ◽  
Constitutive Equations ◽  
Effective Properties ◽  
Dynamic Properties ◽  
Effective Property ◽  
Bloch Wave ◽  
Periodic Composites ◽  
Effective Dynamic ◽  
Dynamic Effective Properties

Central to the idea of metamaterials is the concept of dynamic homogenization which seeks to define frequency dependent effective properties for Bloch wave propagation. While the theory of static effective property calculations goes back about 60 years, progress in the actual calculation of dynamic effective properties for periodic composites has been made only very recently. Here we discuss the explicit form of the effective dynamic constitutive equations. We elaborate upon the existence and emergence of coupling in the dynamic constitutive relation and further symmetries of the effective tensors.

Object Properties Mediating Visual Object Discrimination in the Cat

1964 ◽  
Vol 19 (2) ◽  
pp. 343-350 ◽  
Author(s):  
Walter F. Daves ◽  
Eugene Boostrom
Keyword(s):  
Three Dimensional ◽  
Effective Property ◽  
Visual Object ◽  
Object Discrimination ◽  
Outline Shape ◽  
Object Properties ◽  
Dimensional Shape ◽  
Three Dimensional Shape

In two experiments 25 cats were trained to discriminate objects differing in several properties and then tested to determine which properties provided the basis for discrimination. In both experiments outline shape was a more effective property than texture or three-dimensional shape. In Exp. 1 texture and three-dimensional shape were more effective when the rough, angular (as opposed to the smooth, rounded) object was positive. In Exp. 2 texture was effective when the rough object was positive whether or not the visually “rough” object was also factually rough. Evidence from both experiments indicates that Ss' reactions were primarily determined by the properties of the positive object, and without regard for the properties of the negative object.

On the accuracy of structure-factor measurements in GaAs by CBED

1988 ◽  
Vol 46 ◽  
pp. 824-825
Author(s):  
J.M. Zuo ◽  
M. O'Keeffe ◽  
J.C.H. Spence
Keyword(s):  
Structure Factor ◽  
Phonon Scattering ◽  
Three Dimensional ◽  
Bloch Wave ◽  
Bragg Angle ◽  
Order Structure ◽  
Structure Factors ◽  
Convergent Beam ◽  
Electron Energy Loss ◽  
Low Order

By comparing the experimental intensity in convergent-beam electron diffraction (CBED) patterns along the [h,0,0], [h,h,0] and [h,h,h] systematics directions with three-dimensional Bloch-wave calculations, we have refined the low-order structure factor amplitudes of GaAs. (For Si, see) The experimental data were collected using a Philips EM400 electron microscope and a Gatan model 607 electron energy loss spectrometer (EELS) tuned to the elastic peak. By placing the scan coils of the microscope under the control of a PDP11 computer, the CBED patterns could be scanned over the EELS entrance slit. Data were collected at 120kV and -183°C to reduce phonon scattering and contamination. The angular resolution was 0.6% of the (200) Bragg angle. The refinement parameters in the calculations were high voltage (obtained from HOLZ lines), thickness (obtained from outer CBED fringes), absorption potentials (from the asymmetry of the (000) disk) and the low-order structure factors Vg (from inner peaks).

Sliding property Evaluation of Three Dimensional Printer Model Using Metal-Containing PLA Resin

2019 ◽  
Vol 2019.27 (0) ◽  
pp. 107
Author(s):  
Yuya Matsutake ◽  
Tomoya Wakabayashi ◽  
Tomohiro Sato ◽  
Ken-ichi Saitoh ◽  
Masanori Takuma ◽  
...  
Keyword(s):  
Three Dimensional ◽  
Property Evaluation ◽  
Printer Model

Efficient Computation of Thermoacoustic Modes in Annular Combustion Chambers Based on Bloch-Wave Theory

2015 ◽  
Author(s):  
Georg A. Mensah ◽  
Jonas P. Moeck
Keyword(s):  
Rotational Symmetry ◽  
Three Dimensional ◽  
Wave Theory ◽  
Bloch Wave ◽  
Computational Effort ◽  
Mode Shapes ◽  
Efficient Computation ◽  
Burner Flame ◽  
Flame Response ◽  
Type Boundary

Most annular combustors feature a discrete rotational symmetry so that the full configuration can be obtained by copying one burner–flame segment a certain number of times around the circumference. A thermoacoustic model based on the Helmholtz equation then admits special solutions of the so-called Bloch type that can be obtained by considering one segment only. We show that a significant reduction in computational effort for the determination of thermoacoustic modes can be achieved by exploiting this concept. The framework is applicable even in complex cases including a non-homogeneous temperature field and a frequency-dependent, spatially distributed flame response. A parametric study on a three-dimensional combustion chamber model is conducted using both the full scale chamber simulation and a one-segment model with the appropriate Bloch-type boundary conditions. The results for both computations are compared in terms of mode frequencies and growth rates as well as the corresponding mode shapes. This comparison demonstrates the benefits of the Bloch-wave based analysis. It is further shown that even the effect of circumferential asymmetries can be assessed based on computations of one burner–flame segment only by resorting to spectral perturbation theory.

Secondary Instabilities of Convective Rolls in Porous Media

2003 ◽  
Author(s):  
M. C. Neel ◽  
L. Nisse
Keyword(s):  
Three Dimensional ◽  
Sufficient Conditions ◽  
Bloch Wave ◽  
Sufficient Condition ◽  
Schmidt Method ◽  
Onset Of Convection ◽  
Infinite Extent ◽  
Necessary And Sufficient ◽  
Secondary Instabilities ◽  
Convective Rolls

Necessary and sufficient conditions are presented for spectral instability of convective rolls in a horizontal porous layer of infinite extent, just above the onset of convection. The analytical method, based upon the notion of Bloch wave, takes account of three dimensional perturbations, without any restriction concerning the wave vector. The Lyapunov-Schmidt method allows to compute higher orders in the expansion of the dispersion relation, involving growth rates and parameters of the disturbances. They are necessary for to arrive at a sufficient condition for spectral stability of rolls. Amplifying Bloch waves are determined.

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