Optical Electromagnetics II

2006 ◽  
Author(s):  
Michael E. Thomas
Keyword(s):  
Large Scale ◽  
Constitutive Relations ◽  
Plane Waves ◽  
Index Of Refraction ◽  
Formal Structure ◽  
Optical Propagation ◽  
Electromagnetic Power ◽  
Microscopic Models ◽  
Considerable Detail

In this chapter the same basic topics are addressed as in the previous chapter, but now in the presence of matter. This greatly complicates the description of optical propagation and continues to be the primary topic of the remaining chapters. A formal structure is developed to handle absorption and scattering phenomena in general. The modeling of optical propagation is reduced to having to know the complex index of refraction of the medium. A macroscopic description represents the large-scale observable character of optical propagation. At this level, many models are phenomenological, but lead to important general properties, definitions, formulas, and the establishment of basic concepts. Because microscopic models to be presented in future chapters contain considerable detail, this section is an important prerequisite to the remaining text. Again, plane waves are a useful tool for the description of optical propagation. The Poynting vector, causality, and Poynting’s theorem are used to develop and derive quantities and relationships concerning radiometry and the flow of electromagnetic power at optical frequencies. Consider Maxwell’s equations again, but in the presence of linear isotropic matter. Now the constitutive relations will play a more important role and are the foundation of classical dispersion theory.

scholarly journals Simulation of Cyclic Loading on Pipe Elbows Using Advanced Plane-Stress Elastoplasticity Models1

2020 ◽  
Vol 143 (2) ◽  
Author(s):  
Konstantinos Chatziioannou ◽  
Yuner Huang ◽  
Spyros A. Karamanos
Keyword(s):  
Cyclic Loading ◽  
Large Scale ◽  
Mechanical Response ◽  
Low Cycle Fatigue ◽  
Constitutive Relations ◽  
Cyclic Plasticity ◽  
Integration Scheme ◽  
Repeated Loading ◽  
Finite Element Software ◽  
Hardening Models

Abstract This work investigates the response of industrial steel pipe elbows subjected to severe cyclic loading (e.g., seismic or shutdown/startup conditions), associated with the development of significant inelastic strain amplitudes of alternate sign, which may lead to low-cycle fatigue. To model this response, three cyclic-plasticity hardening models are employed for the numerical analysis of large-scale experiments on elbows reported elsewhere. The constitutive relations of the material model follow the context of von Mises cyclic elasto-plasticity, and the hardening models are implemented in a user subroutine, developed by the authors, which employs a robust numerical integration scheme, and is inserted in a general-purpose finite element software. The three hardening models are evaluated in terms of their ability to predict the strain range at critical locations, and in particular, strain accumulation over the load cycles, a phenomenon called “ratcheting.” The overall good comparison between numerical and experimental results demonstrates that the proposed numerical methodology can be used for simulating accurately the mechanical response of pipe elbows under severe inelastic repeated loading. Finally, this paper highlights some limitations of conventional hardening rules in simulating multi-axial material ratcheting.

Optical Propagation in Solids

2006 ◽  
Author(s):  
Michael E. Thomas
Keyword(s):  
Thin Films ◽  
Optical Properties ◽  
Solid State ◽  
Optical Fibers ◽  
Optical Materials ◽  
Photonic Devices ◽  
Index Of Refraction ◽  
Optical Detectors ◽  
Optical Propagation ◽  
Valence Bands

This chapter emphasizes the linear optical properties of solids as a function of frequency and temperature. Such information is basic to understanding the performance of optical fibers, lenses, dielectric and metallic mirrors, window materials, thin films, and solid-state photonic devices in general. Optical properties are comprehensively covered in terms of mathematical models of the complex index of refraction based on those discussed in Chapters 4 and 5. Parameters for these models are listed in Appendix 4. A general review of solid-state properties precedes this development because the choice of an optical material requires consideration of thermal, mechanical, chemical, and physical properties as well. This section introduces the classification of optical materials and surveys other material properties that must be considered as part of total optical system design involving solidstate optics. Solid-state materials can be classified in several ways. The following are relevant to optical materials. Three general classes of solids are insulators, semiconductors, and metals. Insulators and semiconductors are used in a variety of ways, such as lenses, windows materials, fibers, and thin films. Semiconductors are used in electrooptic devices and optical detectors. Metals are used as reflectors and high-pass filters in the ultraviolet. This type of classification is a function of the material’s electronic bandgap. Materials with a large room-temperature bandgap (Eg > 3eV) are insulators. Materials with bandgaps between 0 and 3 eV are semiconductors. Metals have no observable bandgap because the conduction and valence bands overlap. Optical properties change drastically from below the bandgap, where the medium is transparent, to above the bandgap, where the medium is highly reflective and opaque. Thus, knowledge of its location is important. Appendix 4 lists the bandgaps of a wide variety of optical materials. To characterize a medium within the region of transparency requires an understanding of the mechanisms of low-level absorption and scattering. These mechanisms are classified as intrinsic or extrinsic. Intrinsic properties are the fundamental properties of a perfect material, caused by lattice vibrations, electronic transitions, and so on, of the atoms composing the material.

From Spectacles to Dance

2020 ◽  
pp. 181-214
Author(s):  
Keith Howard
Keyword(s):  
North Korea ◽  
Large Scale ◽  
Modern Dance ◽  
Dance Notation ◽  
Set Up

This chapter first explores a large-scale dance spectacle in which 50,000 twenty-something citizens celebrated Kim Il Sung’s birthday in 2000. It then looks at how mass performance spectacles have developed in North Korea, exploring their distinguishing characteristics. Next, a historical and contextual discussion is given (which expands from a brief consideration in the previous chapter), linking to dance, and explaining how the content of mass spectacles are notated and disseminated. This leads to an exploration and explanation of the chamo p’yogibŏp alphabet-based dance notation, developed in Pyongyang and first used in notation scores in the late 1980s. Then, inherited forms of dance (folkloric, indigenous, international), what they became, and the leading dancer Ch’oe Sŭnghŭi (1911–1968) are explored to set up an overview of the characteristics of dance in North Korea. The account foregrounds Ch’oe Sŭnghŭi’s adaptations of modern dance.

scholarly journals Exact Solutions Superimposed with Nonlinear Plane Waves

2016 ◽  
Vol 2016 ◽  
pp. 1-7
Author(s):  
B. S. Desale ◽  
Vivek Sharma
Keyword(s):  
Exact Solution ◽  
Plane Wave ◽  
Incompressible Fluid ◽  
Exact Solutions ◽  
Large Scale ◽  
Plane Waves ◽  
Boussinesq Equations ◽  
Integral Curves ◽  
Nonlinear Plane ◽  
Scale Motion

The flow of fluid in atmosphere and ocean is governed by rotating stratified Boussinesq equations. Through the literature, we found that many researchers are trying to find the solutions of rotating stratified Boussinesq equations. In this paper, we have obtained special exact solutions and nonlinear plane waves. Finally, we provide exact solutions to rotating stratified Boussinesq equations with large scale motion superimposed with the nonlinear plane waves. In support of our investigations, we provided two examples: one described the special exact solution and in second example, we have determined the special exact solution superimposed with nonlinear plane wave. Also, we depicted some integral curves that represent the flow of an incompressible fluid particle on the planex1+x2=L(constant)as the particular case.

Process modeling, joint-property characterization and construction of joint connectors for mechanical fastening by self-piercing riveting

2014 ◽  
Vol 10 (4) ◽  
pp. 631-658 ◽  
Author(s):  
Mica Grujicic ◽  
Jennifer Snipes ◽  
S. Ramaswami ◽  
Fadi Abu-Farha
Keyword(s):  
Mechanical Properties ◽  
Finite Element ◽  
Large Scale ◽  
Constitutive Relations ◽  
Computational Cost ◽  
Three Dimensional ◽  
Modeling And Simulations ◽  
Content Type ◽  
Material Parameters ◽  
Computational Analyses

Purpose – The purpose of this paper is to propose a computational approach in order to help establish the effect of various self-piercing rivet (SPR) process and material parameters on the quality and the mechanical performance of the resulting SPR joints. Design/methodology/approach – Toward that end, a sequence of three distinct computational analyses is developed. These analyses include: (a) finite-element modeling and simulations of the SPR process; (b) determination of the mechanical properties of the resulting SPR joints through the use of three-dimensional, continuum finite-element-based numerical simulations of various mechanical tests performed on the SPR joints; and (c) determination, parameterization and validation of the constitutive relations for the simplified SPR connectors, using the results obtained in (b) and the available experimental results. The availability of such connectors is mandatory in large-scale computational analyses of whole-vehicle crash or even in simulations of vehicle component manufacturing, e.g. car-body electro-coat paint-baking process. In such simulations, explicit three-dimensional representation of all SPR joints is associated with a prohibitive computational cost. Findings – It is found that the approach developed in the present work can be used, within an engineering optimization procedure, to adjust the SPR process and material parameters (design variables) in order to obtain a desired combination of the SPR-joint mechanical properties (objective function). Originality/value – To the authors’ knowledge, the present work is the first public-domain report of the comprehensive modeling and simulations including: self-piercing process; virtual mechanical testing of the SPR joints; and derivation of the constitutive relations for the SPR connector elements.

Performance and Robustness Improvements in Ultrasonic Transportation Against Large-Scale Streaming

2016 ◽  
Vol 138 (2) ◽  
Author(s):  
Kun Jia ◽  
Ke-ji Yang ◽  
Bing-Feng Ju
Keyword(s):  
Elastic Constant ◽  
Lead Zirconate Titanate ◽  
Large Scale ◽  
Acoustic Radiation ◽  
Plane Waves ◽  
Acoustic Streaming ◽  
Sound Field ◽  
Radiation Force ◽  
Lead Zirconate ◽  
Potential Well

Acoustic streaming generated from the traveling-wave component of a synthesized sound field often has considerable influence on ultrasonic manipulations, in which the behavior of microparticles may be disturbed. In this work, the large-scale streaming pattern in a chamber with three incident plane waves is simulated, illustrating a directional traveling stream pattern and several vortical structures. Based on the numerical results, the trapping capability of an acoustic potential well is quantitatively characterized according to several evaluation criteria: the boundary and elastic constant of the acoustic potential well, the acoustic radiation force offset ratio, and the elastic constant offset ratio. By optimizing these parameters, the constraint of the acoustic potential well can be strengthened to promote the performance and robustness of the ultrasonic transportation. An ultrasonic manipulation device employing three 1.67-MHz lead zirconate titanate (PZT) transducers with rectangular radiation surface is prototyped and performance tested. The experimental results show that the average fluctuations of a microparticle during transportation have been suppressed into a region less than 0.01 times the wavelength. Particle displacement from equilibrium is no longer observed.

scholarly journals Introducing SiOC as novel dielectric platform for photonic integration

2020 ◽  
Vol 16 (1) ◽  
pp. 81-84
Author(s):  
Faisal Ahmed Memon ◽  
Imran Ali Qureshi ◽  
Abdul Latif Memon ◽  
Erum Saba
Keyword(s):  
Thin Films ◽  
Refractive Index ◽  
Large Scale ◽  
Rf Sputtering ◽  
Silicon Oxycarbide ◽  
Index Of Refraction ◽  
Photonic Integration ◽  
Index Contrast ◽  
Photonic Waveguides ◽  
First Time

In this paper, we explore the potential of silicon oxycarbide (SiOC) as a novel dielectric platform for integrated photonics and present photonic waveguides. The interesting features of SiOC are its wide tunable window of refractive index and low absorption, that are considered key for large scale photonic integration. It is possible to tune SiOC refractive index from silica glass (1.45) to silicon carbide (3.2) that allows to realize a myriad of photonic passive devices. We have prepared SiOC thin films by employing reactive RF sputtering technique and examined their structural and optical properties using several techniques such as SEM, AFM, ellipsometry, profilometry, and prism coupling. For the first time, SiOC thin films with index of refraction of 1.554 at the standard telecom wavelength 1.55 μm are exploited for the fabrication of photonic waveguides and the propagation losses around 0.37 dB/mm are measured. SiOC photonic waveguides exhibit relatively higher index contrast with silica cladding when compared to traditional Ge-doped silica platform.

scholarly journals A non-invasive radar system for automated behavioural tracking: application to sheep

2020 ◽  
Author(s):  
Alexandre Dore ◽  
Cristian Pasquaretta ◽  
Dominique henry ◽  
Edmond Ricard ◽  
Jean-François Bompard ◽  
...  
Keyword(s):  
Large Scale ◽  
Spatial Scales ◽  
Tracking System ◽  
Genetic Selection ◽  
Radar Data ◽  
Millimetre Wave ◽  
Non Invasive ◽  
Electromagnetic Power ◽  
Automated Quantification ◽  
Behavioural Phenotyping

AbstractAutomated quantification of the behaviour of freely moving animals is increasingly needed in ethology, ecology, genetics and evolution. State-of-the-art approaches often require tags to identify animals, high computational power for data collection and processing, and are sensitive to environmental conditions, which limits their large-scale utilisation. Here we introduce a new automated tracking system based on millimetre-wave radars for real time robust and high precision monitoring of untagged animals. To validate our system, we tracked 64 sheep in a standard indoor behavioural test used for genetic selection. First, we show that the proposed radar application is faster and more accurate than conventional video and infrared tracking systems. Next, we illustrate how new behavioural estimators can be derived from the radar data to assess personality traits in sheep for behavioural phenotyping. Finally, we demonstrate that radars can be used for movement tracking at larger spatial scales, in the field, by adjusting operating frequency and radiated electromagnetic power. Millimetre-wave radars thus hold considerable promises for high-throughput recording of the behaviour of animals with various sizes and locomotor modes, in different types of environments.

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