The effective medium for a cylinder with cylindrical inclusions

2021 ◽  
Vol 150 (4) ◽  
pp. 2600-2612
Author(s):  
John A. Fawcett
Keyword(s):  
Effective Medium ◽  
Cylindrical Inclusions

scholarly journals A proof that multiple waves propagate in ensemble-averaged particulate materials

2019 ◽  
Vol 475 (2229) ◽  
pp. 20190344 ◽  
Author(s):  
Artur L. Gower ◽  
I. David Abrahams ◽  
William J. Parnell
Keyword(s):  
Acoustic Waves ◽  
Volume Fraction ◽  
Effective Medium Theory ◽  
Effective Medium ◽  
Inhomogeneous Material ◽  
Ensemble Averaging ◽  
Reflection And Transmission ◽  
Medium Theory ◽  
Transmission Coefficients ◽  
Cylindrical Inclusions

Effective medium theory aims to describe a complex inhomogeneous material in terms of a few important macroscopic parameters. To characterize wave propagation through an inhomogeneous material, the most crucial parameter is the effective wavenumber . For this reason, there are many published studies on how to calculate a single effective wavenumber. Here, we present a proof that there does not exist a unique effective wavenumber; instead, there are an infinite number of such (complex) wavenumbers. We show that in most parameter regimes only a small number of these effective wavenumbers make a significant contribution to the wave field. However, to accurately calculate the reflection and transmission coefficients, a large number of the (highly attenuating) effective waves is required. For clarity, we present results for scalar (acoustic) waves for a two-dimensional material filled (over a half-space) with randomly distributed circular cylindrical inclusions. We calculate the effective medium by ensemble averaging over all possible inhomogeneities. The proof is based on the application of the Wiener–Hopf technique and makes no assumption on the wavelength, particle boundary conditions/size or volume fraction. This technique provides a simple formula for the reflection coefficient, which can be explicitly evaluated for monopole scatterers. We compare results with an alternative numerical matching method.

Effective Medium Approximation for Composite from Three-layered Spherical Particles

PIERS Online ◽  
2009 ◽  
Vol 5 (4) ◽  
pp. 365-368 ◽  
Author(s):  
D. M. Dolgushin ◽  
Anton P. Anzulevich ◽  
V. D. Buchelnikov ◽  
I. V. Bychkov ◽  
Dmitri V. Louzguine-Luzgin
Keyword(s):  
Effective Medium ◽  
Spherical Particles ◽  
Effective Medium Approximation

Pengembangan E-modul Berbasis Smartphone Pada Materi Integral Tak Tentu Berorientasi Keterampilan Abad Ke-21

2020 ◽  
Vol 3 (2) ◽  
pp. 222-233
Author(s):  
Veronika Fany Monica Yuniarti ◽  
Nurul Anriani ◽  
Cecep Anwar H. F. Santosa
Keyword(s):  
Research And Development ◽  
21St Century ◽  
Mathematics Teacher ◽  
21St Century Skills ◽  
Research Method ◽  
Effective Medium ◽  
Developmental Research ◽  
High Category ◽  
Research Show

Abstrak: Penelitian ini bertujuan untuk menghasilkan aplikasi e-modul berbasis smartphone pada materi integral tak tentu berorientasi keterampilan abad ke-21 yang valid, praktis, dan efektif. Penelitian menggunakan metode Research and Development (R&D) dari Borg dan Gall yang dimodifikasi menjadi enam langkah. Hasil penelitian menyatakan bahwa hasil skor validasi ahli materi sebesar 4.2 termasuk kategori valid, ahli media diperoleh 3.8 termasuk kategori valid dan guru matematika diperoleh 3.7 termasuk kategori valid. Sedangkan hasil efektivitas diperoleh dari persentase ketuntasan 70% dengan kategori tinggi, dan n-gain sebesar 0,7682 termasuk kategori interpretasi tinggi. Lebih jauh, hasil praktis diperoleh 44.55 jumlah rata-rata skor pernyataan yang termasuk kategori sangat praktis dan 39.80 jumlah rata-rata skor pernyataan yang termasuk kategori praktis. Berdasarkan hasil tersebut maka dapat disimpulkan bahwa pengembangan aplikasi e-modul berbasis smartphone merupakan media yang valid, praktis, dan efektif. Abstract: The research aims to produce a valid, practical, and effective smartphone-based e-module applications 21st-century skills-oriented integral material. The Research method was developmental research (R&D) according to Borg and Gall which was modified into six steps. The results of the research show that the validity of material experts score is 4.2 (valid category), media experts obtained is 3.8 (valid category) and the mathematics teacher score is 3.7 (valid category). While the effectiveness results obtained from the percentage of completeness of 70% with a high category and n-gain of 0.7682 including the high interpretation category. As well as the practical results obtained 44.55 the average number of statements in the very practical category and 39.80 the average number of statements in the practical category. Based on these results it can be concluded that the development of smartphone-based e-module applications is a valid, practical, and effective medium.

Understanding Who is Having a Taste(off) Nigeria

2020 ◽  
Vol 25 (4) ◽  
pp. 425-440
Author(s):  
Martinette Kruger ◽  
Adam Viljoen ◽  
Oghenetejiri Digun-Aweto
Keyword(s):  
Cultural Identity ◽  
South African ◽  
Developing Country ◽  
Effective Medium ◽  
Cultural Immersion ◽  
The South ◽  
Market Segments ◽  
Culinary Tourism ◽  
The Many ◽  
Multiethnic Societies

Events and festivals, especially those focused on food, showcase the many nuances within a culture and can be seen to be an effective medium to transfer cultural identity or tradition. Cultural phenomena such as food festivals are integral to cultural immersion, especially in multicultural/multiethnic societies such as Nigeria. Emphasizing the importance of investigating the culinary festival market in Nigeria, TasteOff is an example in a developing country that identifies the market segments based on a multisegmentation approach that includes (i) travel motives, (ii) the important "festivalscape" factors, and (iii) future culinary event preferences. This research contributes dually to (i) a better understanding of culinary tourism in Africa, especially since much attention is placed on the South African scenario, and (ii) the needs and preferences of Africa's largest economy, Nigeria.

scholarly journals Spectral Induced Polarization Survey with Distributed Array System for Mineral Exploration: Case Study in Saudi Arabia

Minerals ◽  
2020 ◽  
Vol 10 (9) ◽  
pp. 769 ◽  
Author(s):  
Fouzan A. Alfouzan ◽  
Abdulrahman M. Alotaibi ◽  
Leif H. Cox ◽  
Michael S. Zhdanov
Keyword(s):  
Effective Medium Theory ◽  
Coupling Effect ◽  
Pilot Project ◽  
Drill Hole ◽  
Induced Polarization ◽  
Effective Medium ◽  
Inductive Coupling ◽  
Geothermal Resources ◽  
Spectral Induced Polarization ◽  
Distributed Array

The Saudi Arabian Glass Earth Pilot Project is a geophysical exploration program to explore the upper crust of the Kingdom for minerals, groundwater, and geothermal resources as well as strictly academic investigations. The project began with over 8000 km2 of green-field area. Airborne geophysics including electromagnetic (EM), magnetics, and gravity were used to develop several high priority targets for ground follow-up. Based on the results of airborne survey, a spectral induced polarization (SIP) survey was completed over one of the prospective targets. The field data were collected with a distributed array system, which has the potential for strong inductive coupling. This was examined in a synthetic study, and it was determined that with the geometries and conductivities in the field survey, the inductive coupling effect may be visible in the data. In this study, we also confirmed that time domain is vastly superior to frequency domain for avoiding inductive coupling, that measuring decays from 50 ms to 2 s allow discrimination of time constants from 1 ms to 5 s, and the relaxation parameter C is strongly coupled to intrinsic chargeability. We developed a method to fully include all 3D EM effects in the inversion of induced polarization (IP) data. The field SIP data were inverted using the generalized effective-medium theory of induced polarization (GEMTIP) in conjunction with an integral equation-based modeling and inversion methods. These methods can replicate all inductive coupling and EM effects, which removes one significant barrier to inversion of large bandwidth spectral IP data. The results of this inversion were interpreted and compared with results of drill hole set up in the survey area. The drill hole intersected significant mineralization which is currently being further investigated. The project can be considered a technical success, validating the methods and effective-medium inversion technique used for the project.

Characteristics of Effective-Medium-Cladded Dielectric Waveguides

2020 ◽  
pp. 1-1
Author(s):  
Wei Jie Gao ◽  
Wendy Lee ◽  
Xiongbin Yu ◽  
Masayuki Fujita ◽  
Tadao Nagatsuma ◽  
...  
Keyword(s):  
Effective Medium ◽  
Dielectric Waveguides
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