Academic literature on the topic 'Anisotropi'
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Journal articles on the topic "Anisotropi"
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Pranowo, Waskito, and Sonny Winardhi. "Application of Velocity Variation with Angle (VVA) Method on an Anisotropic Model with Thomsen Delta Anisotropy Parameters." Jurnal Geofisika 16, no. 2 (September 19, 2018): 6. http://dx.doi.org/10.36435/jgf.v16i2.371.
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Anisotropic properties will influence seismic propagation, for example it will affect wave velocity. One of well-known anisotropi equation for Transversaly Isotropic media is weak anisotropy with Thomsen's notation. Supriyono [2011] tried to estimate all of these variables by using velocity variation with angle (VVA) attribute. This research uses synthetic data, which is CMP Gather to know limitations of VVA attribute, to identify the error values, and to determine the best indicator of anisotropic eect. This research also uses another analysis method, which is grid search inversion to estimate VP0. From this research, Both VVA and grid search invesion still produce signcant error. The effects which will appear because of anisotropic property's presence are hockey-stick and over NMO-stretching.
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Rongkonusa, Melisa, Gerald Tamuntuan, and Guntur Pasau. "Analisis Anisotropi Suseptibilitas Magnetik Batuan Beku Lengan Utara Sulawesi." Jurnal MIPA 6, no. 1 (May 2, 2017): 8. http://dx.doi.org/10.35799/jm.6.1.2017.15846.
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Telah dilakukan penelitian untuk menentukan pola anisotropi suseptibilitas magnetik dan status singkapan batuan beku dari pola yang diperoleh. Pengukuran anisotropi suseptibilitas magnetic dilakukan pada lima sampel batuan beku dari Sulawesi Utara menggunakan Bartington MS2B. Arah pengukuran sampel disesuaikan dengan desain Tauxe. Hasilnya menunjukkan bahwa suseptibilitas maksimum terdistribusi disekitar arah utara dan timur. Sedangkan suseptibilitas intermediet dan minimum terdistribusi disekitar Utara-Timur dan Timur-Selatan. Elipsoida suseptibilitas cenderung prolate atau lebih lonjong. Batuan beku yang dianalisis merupakan kelompok batuan terobosan yang mekanisme lelehannya terjadi secara vertikal.A research has been conducted to determine the anisotropic pattern of magnetic susceptibility and the status of igneous rocks exposure from the obtained pattern. We have measured the anisotropy of magnetic susceptibility on five samples of igneous rock from North Sulawesi by Bartington MS2B. The position of samples were adjusted according to the Tauxe’s design. The result shows that the maximum susceptibility is distributed around northward and eastward, while the intermediate and minimum susceptibility are distributed around nortward-eastward and eastward-southward. The susceptibility ellipsoid tends to be prolate or more oval. This shows that the igneous rocks that have been analyzed are group of intrusive rocks which melting mechanism occurs through vertical fracture.enetie
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Luthfin, Ahmad, Adi Susilo, and Teguh Suroso. "PEMODELAN BAWAH PERMUKAAN METODE PRE-STACK TIME MIGRATION (PSTM) ISOTROPY DAN METODE PSTM ANISOTROPY HIGH ORDER MOVEOUT (HOM)." JURNAL NEUTRINO 8, no. 2. APRIL (May 2, 2016): 58. http://dx.doi.org/10.18860/neu.v8i2.3265.
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Struktur bawah permukaan memiliki perlapisan yang sangat komplek, sehingga memungkinkan penjalaran gelombang seismik memiliki kecepatan yang berbeda tergantung arah rambatnya. Hal inilah yang mendasari perlunya proses pengolahan data dengan melibatkan parameter anisotropi (<em>η</em>). Umumnya data seismik memiliki nilai anisotropi dengan presentase tertentu, sehingga tidak semua data harus diproses dengan proses anisotropi. Ketepatan metode migrasi yang digunakan dapat menghasilkan gambar penampang struktur bawah permukaan dengan resolusi yang tinggi. Penelitian ini bertujuan untuk memodelkan struktur bawah permukaan dengan menggunakan metode PSTM isotopi (lapisan isotropi) sedangkan untuk lapisan anisotropi dimodelkan dengan metode PSTM anisotropi HOM. Hasil dari metode PSTM isotropi berupa citra, dimana lapisan pertama pada CMP 2073-CMP 2413 hasilnya jelek (beresolusi rendah), tetapi untuk lapisan kedua dan ketiga tampak bagus (beresolusi tinggi). Pada saat diproses dengan PSTM anisotropi, peneliti menggunakan nilai (<em>η) </em>sekitar 0,25 pada lapisan pertama. Berdasarkan hasil PSTM anisotropi pada CMP 2073-CMP 2413 model lapisan pertama menghasilkan citra beresolusi lebih tinggi (lebih bagus), sedangkan model lapisan kedua dan ketiga tidak mengalami kenaikan resolusi yang signifikan. Hal ini karena rasio <em>far offset</em> dan kedalaman lapisan pertama besar menyebabkan lapisan pertama mengalami efek anisotropi, sedangkan lapisan kedua dan ketiga tidak mengalami efek anisotropi
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Febriardi, Julius, and Wahyu Triyoso. "Estimasi Parameter Koreksi Anisotropi Seismik Melalui Pendekatan Nonhyperbolic Moveout Pada Gather Konvensional, DMO, dan CRS." Jurnal Geofisika 15, no. 1 (November 18, 2019): 15. http://dx.doi.org/10.36435/jgf.v15i1.404.
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Sifat anisotropi pada suatu medium menyebabkan adanya perbedaan kecepatan rambat gelombang berdasarkan arah rambatnya. Medium bersifat transvere isotropy memiliki nilai kecepatan yang berbeda ke arah lateral dan vertikal. Medium bersifat vertical transverse isotropy (VTI) memiliki kecepatan lateral yang lebih besar daripada kecepatan vertikal. Perbedaan ini menyebabkan timbulnya efek hockey stick, terutama pada offset jauh. Karena informasi pada offset jauh amat penting, maka efek ini perlu dikoreksi terlebih dahulu sebelum melanjutkan ke tahapan pemrosesan data selanjutnya. Untuk mendapat pemahaman yang lebih baik, maka dibuat model sintetik VTI yang diproses menggunakan normal moveout (NMO), dip moveout (DMO) dan common reflection surface (CRS). Untuk menghilangkan efek dipping dan agar didapatkan hasil velocity analysis yang baik, DMO dan CRS dilakukan. Pilihan ini atas pertimbangan bahwa metode DMO dapat menghilangkan sifat dip- dependent pada gather seismik, dan analisis kecepatan paling mudah dilakukan pada metode CRS. Hasil perbandingan metode DMO dan CRS menunjukkan bahwa CRS menunjukkan S/N ratio yang lebih baik dan memiliki ketidakpastian yang lebih kecil dalam analisis kecepatan yang berpengaruh langsung dalam estimasi parameter koreksi anisotropi. Nilai parameter koreksi anisotropi diestimasi pada CDP yang ditentukan menggunakan pendekatan nonhyperbolic moveout. Nilai rata-rata yang diperoleh pada masing-masing metode menunjukkan hasil yang berbeda. Nilai ηeff yang paling mendekati nilai η model adalah pada metode DMO dan CRS.
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Nurhasan, Abdullah, Dadang Ramdan, Zuardin Azzaino, Alexis Badai Samudra, and Rino Saputra. "Fault Related Stress and Fractures Analysis using the Anisotropy Signatures from Azimuthal Amplitude Variation in Lematang Trend, South Sumatera Basin." Jurnal Geofisika 18, no. 2 (December 22, 2020): 27. http://dx.doi.org/10.36435/jgf.v18i2.444.
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Evaluasi reservoir terrekahkan harus didasari pengetahuan tentang arah rekah dominan dan stress horizontal yang berlaku pada area studi demi mendapatkan rekomendasi arah pengeboran yang optimal. Namun demikian, informasi tentang stress yang banyak ditemukan adalah pada skala regional, global, maupun skala sumuran. Dalam hal pemodelan pada skala reservoir, data seismic dapat dijadikan penghubung kedua skala yang berjauhan tersebut.
Kehadiran rekahan dan stress pada batuan dapat menyebabkan karakter anisotropi di reservoir. Pada skala seismic, sifat anisotropi sebuah media dapat diamati dari perubahan amplitude dan waktu tempuh terhadap azimuth rambat dan pantulan gelombang seismic. Pada makalah ini, kami menggunakan data seismic pre-stack selangkah di depan metode Amplitude Versus Offset (AVO) dan Extended Elastic Impedance (EEI) yang masih mengandalkan perubahan amplitude terhadap sudut pantul, dengan mengamati perubahan amplitude terhadap azimuth (AVAZ). Untuk pencapai tujuan tersebut, kami memproses ulang data seismic 3D dengan menggunakan metode Offset Vector Tile (OVT) sehingga informasi azimuth tersimpan dengan baik.
Informasi yang digunakan untuk menginterpretasi orientasi rewkahan dan tress horizontal maximum adalah orientasi dan magnitude anisotropi. Hasil studi ini menunjukkan rekahan dan stress yang bersifat local dapat dengan yang bersifat regional dan global. Hal ini menunjukkan bahwa arah pengeboran optimal tidak harus dikontrol oleh arah stress global.
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Xiong, Zonghou. "Electromagnetic fields of electric dipoles embedded in a stratified anisotropic earth." GEOPHYSICS 54, no. 12 (December 1989): 1643–46. http://dx.doi.org/10.1190/1.1442633.
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The anisotropy of electrical conductivity in earth formations may be caused by crystal anisotropies of minerals, as well as by minilayers which occur frequently in sedimentary environments. The effects of anisotropy on the propagation of electromagnetic (EM) fields have been studied by many geophysicists. For instance, Kong (1972) and Wait (1981) solved the EM propagation problem for vertically anisotropic layered earths; O’Brien and Morrison (1967), for a horizontally anisotropic multilayer half‐space; Chetayev (1960), as well as Reddy and Rankin (1971), for media of dipping anisotropies; and Al’tgauzen (1969), for more complicated anisotropic media with a tensor dielectric constant of five components.
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Febriyanti, Eka, Amin Suhadi, Dedi Priadi, and Rini Riastuti. "ANALISIS MAMPU BENTUK BAHAN BAKU SELONGSONG MUNISI Cu-Zn 70/30 SETELAH DEFORMASI PADA SUHU 500ºC = ANALYSIS FORMABILITY OF RAW MATERIALS CU - ZN MUNITIONS CASINGS 70/30 AFTER DEFORMATION AT TEMPERATURE 500ºC." Majalah Ilmiah Pengkajian Industri 9, no. 3 (September 5, 2015): 175–78. http://dx.doi.org/10.29122/mipi.v9i3.1648.
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casing because both processes have important role to derive raw material into the required form, dimensions and characteristics. Cu-Zn 70/30 alloy is raw material which normally used as munition casing however, its formability after deformation and heat treatment is not widely known. Therefore, this research has an objective to study the effect of deformation at warm temperature on cold formability by introducing thermomechanical controlled processed in warm rolling. Warm rolling have been conducted by double pass reversible method on 25% x 2, 30% x 2, and 35% x 2 at temperature 500oC. Evaluation of formability have been done by limited tensile test up to 20% elongation and full tensile test until rupture. The result of this research indicates that the best formability of Cu-Zn 70/30 is obtained on specimen which are deformed by warm rolling at actual degree of deformation 38.7%. Formability testing result for his specimen under designated warm rolling parameter has an elongation 10 % with strain hardening coefficient 0.00228, average normal anisotropy value 0.5452, and plannar anisotropy value Δr<1 is: -0.42. ABSTRAKDeformasi dan perlakuan panas selalu menyertai proses pembuatan selongsong peluru karena kedua proses tersebutlah yang mampu mengatur bahan baku menjadi bentuk dan dimensi yang diinginkan serta sesuai dengan karakteristik yang dikehendaki. Padaun Cu-Zn 70/30 adalah bahan baku yang digunakan untuk pembuatan selongsong peluru, namun mampu bentuk paduan ini akibat deformasi dan perlakuan panas belum banyak diketahui. Oleh karena itu pada penelitian ini bertujuan untuk mempelajari pengaruh deformasi yang dilakukan pada suhu hangat terhadap mampu bentuk dingin dengan metode thermomechanical controlled processed menggunakan teknologi canai hangat. Teknologi canai hangat dilakukan dengan metode double pass reversible sebanyak 25% x 2, 30% x 2, dan 35% x 2 pada suhu 500oC. Pengamatan mampu bentuk dilakukan dengan pengujian tarik hanya sampai perpanjangan 20% serta uji tarik sampai putus. Hasil dari penelitian menunjukkan bahwa sifat mampu bentuk terbaik diperoleh pada benda uji yang dideformasi canai hangat di temperatur 500oC dengan derajat deformasi aktual sebesar 38.7%. Apabila dilihat dari sifat mampu bentuknya maka benda uji yang dideformasi canai hangat pada kondisi parameter penelitian ini memiliki nilai elongasi sebesar 10 % dengan nilai koefisien pengerasan regang yang tinggi sebesar 0.00228, nilai anisotropi normal rata-rata sebesar 0.5452, dan nilai anisotropi planar yaitu Δr<1 sebesar -0.42.
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Hood, J. A. "A simple method for decomposing fracture‐induced anisotropy." GEOPHYSICS 56, no. 8 (August 1991): 1275–79. http://dx.doi.org/10.1190/1.1443149.
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A heterogeneous mixture of isotropic elements may appear homogeneous and anisotropic when the scale of its fabric is smaller than the seismic wavelengths that measure it (Backus, 1962). These fabrics can result from thin layering or from oriented microcracks or fractures. In many situations the anisotropy is quite complex, resulting, for example, from fractures in previously anisotropic media. Since these anisotropies combine, the effect of each must be separated to permit the study of either the fractures or the preexisting anisotropy.
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Ramadhan, Muhammad Gilang, Ayuna Santika Putri, Andang Kurniawan, and Amir Mustofa Irawan. "PRIORITAS ARAH PENEMPATAN TITIK PENGAMATAN KECEPATAN VERTIKAL DI KALIMANTAN MENGGUNAKAN ANALISIS ANISOTROPI." Jurnal Meteorologi Klimatologi dan Geofisika 5, no. 3 (April 29, 2019): 63–71. http://dx.doi.org/10.36754/jmkg.v5i3.76.
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Keberadaan hutan sebagai paru-paru dunia berperan penting dalam menghasilkan gas oksigen. Pulau Kalimantan merupakan salah satu paru-paru dunia karena luas hutannya yang mencapai 40,8 juta hektar. Namun, pada saat ini kualitas dan kuantitas hutan di Pulau Kalimantan mengalami penurunan drastis akibat adanya deforestasi dan kebakaran hutan. Kebakaran hutan di Pulau Kalimantan menjadi sorotan dunia karena persebaran asapnya menyebabkan polusi udara di berbagai wilayah Indonesia. Dampak dari persebaran asap kebakaran hutan dipengaruhi oleh kecepatan angin vertikal pada daerah tersebut. Penelitian ini bertujuan untuk menambah bahan pertimbangan dalam menentukan titik pengamatan kecepatan vertikal angin di Pulau Kalimantan, sehingga dapat diketahui prioritas sebaran penempatan titik pengamatan yang dapat digunakan sebagai upaya mitigasi persebaran asap kebakaran hutan. Data kecepatan angin vertikal Pulau Kalimantan pada bulan Juni sampai Oktober mulai tahun 2008 – 2017 disajikan dalam bentuk spasial. Analisis data angin tersebut menggunakan metode variogram permukaan dengan piranti lunak SAGA. Berdasarkan analisis anisotropi, diperoleh hasil bahwa pengamatan kecepatan vertikal angin di Pulau Kalimantan cenderung mempunyai prioritas arah Timur-Barat pada bulan Juni sampai Agustus, prioritas arah Tenggara-Barat Laut pada bulan September, dan prioritas arah Timur Laut-Barat Daya pada Bulan Oktober. Analisis dan pemodelan kecepatan angin vertikal pada Pulau Kalimantan secara umum mendapatkan pola dominan prioritas arah Timur-Barat, sehingga prioritas penempatan titik pengamatan kecepatan vertikal pada Pulau Kalimantan efektif jika membentuk pola oval yang memanjang dari Utara ke Selatan.
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Yu, Jing, Yongmei Zhang, Yuhong Zhao, and Yue Ma. "Anisotropies in Elasticity, Sound Velocity, and Minimum Thermal Conductivity of Low Borides VxBy Compounds." Metals 11, no. 4 (April 1, 2021): 577. http://dx.doi.org/10.3390/met11040577.
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Anisotropies in the elasticity, sound velocity, and minimum thermal conductivity of low borides VB, V5B6, V3B4, and V2B3 are discussed using the first-principles calculations. The various elastic anisotropic indexes (AU, Acomp, and Ashear), three-dimensional (3D) surface contours, and their planar projections among different crystallographic planes of bulk modulus, shear modulus, and Young’s modulus are used to characterize elastic anisotropy. The bulk, shear, and Young’s moduli all show relatively strong degrees of anisotropy. With increased B content, the degree of anisotropy of the bulk modulus increases while those of the shear modulus and Young’s modulus decrease. The anisotropies of the sound velocity in the different planes show obvious differences. Meanwhile, the minimum thermal conductivity shows little dependence on crystallographic direction.
Dissertations / Theses on the topic "Anisotropi"
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Isachsen, Marit. "Effekt av anisotropi på udrenert skjærstyrke i naturlige skråninger." Thesis, Norges teknisk-naturvitenskapelige universitet, Institutt for bygg, anlegg og transport, 2012. http://urn.kb.se/resolve?urn=urn:nbn:no:ntnu:diva-18653.
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Anisotropi har stor innvirkning på den udrenerte skjærstyrken i leire. I dag er NGI-ADP modellen implementert i elementmetodeprogrammet Plaxis, men modellen tar kun hensyn til anisotropi på deviatoriske spenninger, og egner seg derfor best under initialt flatt terreng. Denne masteroppgaven tar utgangspunkt i en forenklet variant av ADP-modellen, presentert av Kristoffer Rabstad i hans hovedoppgave våren 2011. Modellen er kalt ADPXX, og tar også hensyn til anisotropi på initiale skjærspenninger, på horisontale og vertikale plan. ADPXX-modellen viste en større effekt av anisotropi på grunn av initiale skjærspenninger enn forventet, hvilket er bakgrunnen for oppgaven.Materialmodellens egenskaper er analysert i ulike initialtilstander. Det har vist seg at det er vanskelig å gi aktiv og passiv styrke som input som funksjon av initial effektiv vertikal overlagring. Styrketakene må relateres til de effektive initiale hovedspenningene uansett hvilken retning disse måtte ha. Endringer i modellen og i programkoden er utført for bedre tilnærming til reell materialoppførsel ved å justere grad av anisotropi ut fra initialspenningen, på en konsistent måte innen rammen av et Mohr Coulomb (MC) flytekriterium. Dette innebærer at graden av anisotropi varierer gjennom materialet. For enkelhets skyld er det antatt at anisotropi på skjærspenninger gir like stort bidrag som anisotropi på deviatoriske spenninger. Modellens egenskaper er demonstrert gjennom eksempler, både på en naturlig skråning og på to fiktive idealskråninger. Modellen oppfører seg som forventet. I tilfeller der spenningene øker proporsjonalt, som i en vanlig stabilitetsanalyse av en naturlig skråning, vil modellen gi samme resultat som MC. I situasjoner der en ytre last fører til spenningsrotasjon, vil den brukerdefinerte modellen gi lavere kapasitet. Forskjellen minker dersom skråningen initialt har lav sikkerhet mot brudd.
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Chen, Xiaoming. "Two-dimensional constrained anisotropic inversion of magnetotelluric data." Phd thesis, Universität Potsdam, 2012. http://opus.kobv.de/ubp/volltexte/2012/6316/.
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Tectonic and geological processes on Earth often result in structural anisotropy of the subsurface, which can be imaged by various geophysical methods. In order to achieve appropriate and realistic Earth models for interpretation, inversion algorithms have to allow for an anisotropic subsurface. Within the framework of this thesis, I analyzed a magnetotelluric (MT) data set taken from the Cape Fold Belt in South Africa. This data set exhibited strong indications for crustal anisotropy, e.g. MT phases out of the expected quadrant, which are beyond of fitting and interpreting with standard isotropic inversion algorithms. To overcome this obstacle, I have developed a two-dimensional inversion method for reconstructing anisotropic electrical conductivity distributions.
The MT inverse problem represents in general a non-linear and ill-posed minimization problem with many degrees of freedom: In isotropic case, we have to assign an electrical conductivity value to each cell of a large grid to assimilate the Earth's subsurface, e.g. a grid with 100 x 50 cells results in 5000 unknown model parameters in an isotropic case; in contrast, we have the sixfold in an anisotropic scenario where the single value of electrical conductivity becomes a symmetric, real-valued tensor while the number of the data remains unchanged. In order to successfully invert for anisotropic conductivities and to overcome the non-uniqueness of the solution of the inverse problem it is necessary to use appropriate constraints on the class of allowed models. This becomes even more important as MT data is
not equally sensitive to all anisotropic parameters. In this thesis, I have developed an algorithm through which the solution of the anisotropic inversion problem is calculated by minimization of a global penalty functional consisting of three entries: the data misfit, the model roughness constraint and the anisotropy constraint. For comparison, in an isotropic approach only the first two entries are minimized. The newly defined anisotropy term is measured by the sum of the square difference of the principal conductivity values of the model. The basic idea of this constraint is straightforward. If an isotropic model is already adequate to explain the data, there is no need to introduce electrical anisotropy at all.
In order to ensure successful inversion, appropriate trade-off parameters, also known as regularization parameters, have to be chosen for the different model constraints. Synthetic tests show that using fixed trade-off parameters usually causes the inversion to end up by either a smooth model with large RMS error or a rough model with small RMS error. Using of a relaxation approach on the regularization parameters after each successful inversion iteration will result in smoother inversion model and a better convergence. This approach seems to be a sophisticated way for the selection of trade-off parameters. In general, the proposed inversion method is adequate for resolving the principal conductivities defined in horizontal plane. Once none of the principal directions of the anisotropic structure is coincided with the predefined strike direction, only the corresponding effective conductivities, which is the projection of the principal conductivities onto the model coordinate axes direction, can be resolved and the information about the rotation angles is
lost.
In the end the MT data from the Cape Fold Belt in South Africa has been analyzed. The MT data exhibits an area (> 10 km) where MT phases over 90 degrees occur. This part of data cannot be modeled by standard isotropic modeling procedures and hence can not be properly interpreted. The proposed inversion method, however, could not reproduce the anomalous large phases as desired because of losing the information about rotation angles. MT phases outside the first quadrant are usually obtained by different anisotropic anomalies with oblique anisotropy strike. In order to achieve this challenge, the algorithm needs further developments. However, forward modeling studies with the MT data have shown that surface highly conductive heterogeneity in combination with a mid-crustal electrically anisotropic zone are required to fit the data. According to known geological and tectonic information the mid-crustal zone is interpreted as a deep aquifer related to the fractured Table Mountain Group rocks in the Cape Fold Belt.Tektonische und geologische Prozesse verursachen häufig eine strukturelle Anisotropie des Untergrundes, welche von verschiedenen geophysikalischen Methoden beobachtet werden kann. Zur Erstellung und Interpretation geeigneter, realistischer Modelle der Erde sind Inversionsalgorithmen notwendig, die einen anisotropen Untergrund einbeziehen können. Für die vorliegende Arbeit habe ich einen magnetotellurischen (MT) Datensatz vom Cape Fold Gürtel in Südafrika untersucht. Diese Daten weisen auf eine ausgeprägte Anisotropie der Kruste hin, da z.B. die MT Phasen außerhalb des erwarteten Quadranten liegen und nicht durch standardisierte isotrope Inversionsalgorithmen angepasst und ausgewertet werden können. Um dieses Problem zu beheben, habe ich eine zweidimensionale Inversionsmethode entwickelt, welche eine anisotrope elektrische Leitfähigkeitsverteilungen in den Modellen zulässt. Die MT Inversion ist im allgemeinen ein nichtlineares, schlecht gestelltes Minimierungsproblem mit einer hohen Anzahl an Freiheitsgraden. Im isotropen Fall wird jeder Gitterzelle eines Modells ein elektrischer Leitfähigkeitswert zugewiesen um den Erduntergrund nachzubilden. Ein Modell mit beispielsweise 100 x 50 Zellen besitzt 5000 unbekannte Modellparameter. Im Gegensatz dazu haben wir im anisotropen Fall die sechsfache Anzahl, da hier aus dem einfachen Zahlenwert der elektrischen Leitfähigkeit ein symmetrischer, reellwertiger Tensor wird, wobei die Anzahl der Daten gleich bleibt. Für die erfolgreiche Inversion von anisotropen Leitfähigkeiten und um die Nicht-Eindeutigkeit der Lösung des inversen Problems zu überwinden, ist eine geeignete Einschränkung der möglichen Modelle absolut notwendig. Dies wird umso wichtiger, da die Sensitivität von MT Daten nicht für alle Anisotropieparameter gleich ist. In der vorliegenden Arbeit habe ich einen Algorithmus entwickelt, welcher die Lösung des anisotropen Inversionsproblems unter Minimierung einer globalen Straffunktion berechnet. Diese besteht aus drei Teilen: der Datenanpassung, den Zusatzbedingungen an die Glätte des Modells und die Anisotropie. Im Gegensatz dazu werden beim isotropen Fall nur die ersten zwei Parameter minimiert. Der neu definierte Anisotropieterm wird mit Hilfe der Summe der quadratischen Abweichung der Hauptleitfähigkeitswerte des Modells gemessen. Die grundlegende Idee dieser Zusatzbedingung ist einfach. Falls ein isotropes Modell die Daten ausreichend gut anpassen kann, wird keine elektrische Anisotropie zusätzlich in das Modell eingefügt. Um eine erfolgreiche Inversion zu garantieren müssen geeignete Regularisierungsparameter für die verschiedenen Nebenbedingungen an das Modell gewählt werden. Tests mit synthetischen Modellen zeigen, dass bei festgesetzten Regularisierungsparametern die Inversion meistens entweder in einem glatten Modell mit hohem RMS Fehler oder einem groben Modell mit kleinem RMS Fehler endet. Die Anwendung einer Relaxationsbedingung auf die Regularisierung nach jedem Iterationsschritt resultiert in glatteren Inversionsmodellen und einer höheren Konvergenz und scheint ein ausgereifter Weg zur Wahl der Parameter zu sein. Die vorgestellte Inversionsmethode ist im allgemeinen in der Lage die Hauptleitfähigkeiten in der horizontalen Ebene zu finden. Wenn keine der Hauptrichtungen der Anisotropiestruktur mit der vorgegebenen Streichrichtung übereinstimmt, können nur die dazugehörigen effektiven Leitfähigkeiten, welche die Projektion der Hauptleitfähigkeiten auf die Koordinatenachsen des Modells darstellen, aufgelöst werden. Allerdings gehen die Informationen über die Rotationswinkel verloren. Am Ende meiner Arbeit werden die MT Daten des Cape Fold Gürtels in Südafrika analysiert. Die MT Daten zeigen in einem Abschnitt des Messprofils (> 10 km) Phasen über 90 Grad. Dieser Teil der Daten kann nicht mit herkömmlichen isotropen Modellierungsverfahren angepasst und daher mit diesen auch nicht vollständig ausgewertet werden. Die vorgestellte Inversionsmethode konnte die außergewöhnlich hohen Phasenwerte nicht wie gewünscht im Inversionsergebnis erreichen, was mit dem erwähnten Informationsverlust der Rotationswinkel begründet werden kann. MT Phasen außerhalb des ersten Quadranten können für gewöhnlich bei Anomalien mit geneigter Streichrichtung der Anisotropie gemessen werden. Um diese auch in den Inversionsergebnissen zu erreichen ist eine Weiterentwicklung des Algorithmus notwendig. Vorwärtsmodellierungen des MT Datensatzes haben allerdings gezeigt, dass eine hohe Leitfähigkeitsheterogenität an der Oberfläche in Kombination mit einer Zone elektrischer Anisotropie in der mittleren Kruste notwendig sind um die Daten anzupassen. Aufgrund geologischer und tektonischer Informationen kann diese Zone in der mittleren Kruste als tiefer Aquifer interpretiert werden, der im Zusammenhang mit den zerrütteten Gesteinen der Table Mountain Group des Cape Fold Gürtels steht.
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Taouk, Habib. "Wave propagation in general anisotropic media." Ohio : Ohio University, 1986. http://www.ohiolink.edu/etd/view.cgi?ohiou1183380228.
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Ljungberg, Adam, and Nathalie Schmidt. "Deformationsstrukturer i ett duplext rostfritt stål (SAF 2507)." Thesis, Högskolan Dalarna, Materialteknik, 2014. http://urn.kb.se/resolve?urn=urn:nbn:se:du-15770.
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För att kunna förbättra processer och användning av det duplexa rostfria stålet SAF 2507 måste dess deformationsegenskaper undersökas och förklaras. Genom EBSD-analyser har deformationsstrukturer och polfgurer tagits fram för att kunna beskriva materialets beteende vid deformation. Även Taylorfaktorer, E-moduler och Poissons tal har tagits fram för att kunna undersöka materialets anisotropi. Experimenten har utförts på prov av SAF 2507 som har deformerats plastiskt till olika töjningar. Det som undersökts är odeformerat prov, prov som dragits enaxligt till 7,7 % och 24,3 % töjning, samt ett prov som är cykliskt belastat till 3 % töjning. Det undersökta stålet tillverkas genom två olika metoder, men i denna rapport har enbart det extruderade stålet undersökts. Genom att jämföra hur stålets olika mekaniska egenskaper beter sig under plastisk deformation har resultatet blivit att stålets ferritfas beter sig anisotropt med en antydan till ökande isotropi vid ökande deformation. Austenitfasen beter sig däremot isotropt och blir varken mer eller mindre isotropt vid ökande deformation. Substrukturerna i ferritfasen ökar tydligt vid ökande deformation, och ses framför allt i austenitfasen efter 24 % deformation.In order to improve the processes and the use of the duplex stainless steel SAF 2507, its deformation properties has to be investigated and explained. Through EBSD-analysis deformation structures and pole figures have been developed to describe the behavior of the material during deformation. Also Taylor factors, Young’s modules and Poisson's ratio have been developed in order to investigate the material's anisotropy. The experiments have been performed on samples of SAF 2507 which has been plastically deformed at different strains. The strains studied are undeformed sample, samples drawn uniaxial drawn to 7.7 % and 24.3 % elongation, and one sample which is cyclically loaded to 3% elongation. The steel we have investigated is produced by two different methods, but in this report, only the extruded steel is investigated. By comparing how different mechanical properties of the steel behave during plastic deformation, the result shows that the steel’s ferrite phase behaves anisotropically with a hint of increasing isotropy when the deformation is increasing. The austenite phase behaves isotropic and does not become more or less isotropic with increasing deformation. The substructures in the ferrite phase are clearly increasing with increasing deformation, and are seen mainly in the austenite phase after 24 % deformation.
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Vallefuoco, Donato. "Numerical study of unconfined and confined anisotropic turbulence." Thesis, Lyon, 2017. http://www.theses.fr/2017LYSEC053/document.
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Pour les écoulements turbulents d’intérêt pratique, la turbulence interagit avec le confinement et les forces externes, ce qui cause inhomogénéité et anisotropie statistiques. Isoler leur contribution à des statistiques ciblées est indispensable pour comprendre les différents phénomènes physiques. Le but de cette thèse a donc été d’acquérir une meilleure connaissance de l’anisotropie en fonction de la direction et de l’échelle dans un ensemble de contextes idéalisés et réalistes. On a utilisé une caractérisation statistique dans l’espace spectral ainsi que dans l’espace de séparation. La caractérisation dans l’espace spectral concerne les statistiques anisotropes de turbulence sous forme de spectres directionnels d’énergie, polarisation et hélicité. La caractérisation dans l’espace de séparation s’appuie sur les moments des incréments de vitesse à deux points du deuxième et troisième ordre, et sur les corrélations de vitesse à deux points. Tout d’abord, on a étudié l’effet du forçage spectral de grandes échelles. Les schémas de forçage considérés sont le schéma de forçage de type Euler, non hélicitaire et hélicitaire, et le schéma ABC. On a montré que les deux forçages ont un inconvénient, dans le sens que, si le nombre de modes suffisamment excités est petit, de l’anisotropie se produit même aux petites échelles. Dans le cas du forçage Euler, cela dépend de la gamme de nombres d’onde forcés ainsi que de leur hélicité. Le forçage ABC, pour lequel le niveau d’hélicité injectée ne peut pas être contrôlé, n’excite que six modes et donc il produit toujours de l’anisotropie et à toutes les échelles résolues. Ensuite, on a analysé l’anisotropie en fonction de l’échelle et de la direction pour la turbulence homogène en rotation. Chose étonnante, l’anisotropie se produit à toutes les échelles même si la rotation est faible. En particulier, on a identifié deux gammes d’échelles anisotropes qualitativement différentes. Aux grandes échelles, l’anisotropie directionnelle est plus grande et décroît avec le nombre d’onde. Aux petites échelles, elle est beaucoup plus faible—mais encore significative—et croit lentement avec le nombre d’onde jusqu’aux échelles dissipatives. Une autre conclusion intéressante et originale de cette partie du travail concerne le rôle de l’échelle de Zeman et son lien avec l’anisotropie aux différentes échelles de l’écoulement. D’après des travaux précédents, l’échelle de Zeman devrait être l’échelle de longueur caractéristique qui sépare les échelles affectées par la rotation par les échelles isotropes. Après une plus ample investigation, en utilisant simulations à différents paramètres, on a découvert que l’échelle de séparation entre grande et faible anisotropie est plutôt l’échelle de longueur caractéristique pour laquelle les effets de rotation et de dissipation s’équilibrent. Ce résultat, toutefois, n’est pas en contradiction avec l’argument de Zeman sur le rétablissement de l’isotropie dans la limite asymptotique de viscosité nulle, comme l’échelle de séparation s’annule à nombre de Reynolds infini, et donc seulement la gamme d’anisotropie décroissante devrait persister et les échelles beaucoup plus petite que celle de Zeman pourraient récupérer l’isotropie. Enfin, on a considéré l’écoulement de von Kármán entre deux disques équipés de pales en contre-rotation dans une cavité cylindrique. On a répété l’analyse dans l’espace de séparation dans plusieurs petites sous-régions, afin d’enquêter les analogies possibles entre la dynamique de l’écoulement et celle de la turbulence homogène en rotation. On a découvert que, dans les régions du domaine où l’écoulement a un taux de rotation moyen plus grand, les distributions des statistiques dans l’espace de séparation montrent certaines des caractéristiques typiques de la turbulence en rotationIn turbulent flows of practical interest, turbulence interacts with confinement and external forces, leading to statistical inhomogeneity and anisotropy. Isolating their contributions to some targeted statistics is indispensable for understanding the underlying physical phenomena. The aim of this thesis has therefore been to gain further insight into direction- and scale-dependent anisotropy in a set of idealized and realistic contexts. Both spectral space and separation space statistical characterizations have been employed. The spectral characterization concerns the anisotropic statistics of turbulence under the form of directional energy, polarization and helicity spectra. The separation space characterization is built on two-point second- and third-order velocity increment moments, and two-point velocity correlations. First, we studied the effect of large-scale spectral forcing. The considered forcing methods are the non-helical and the helical Euler scheme, and the ABC-scheme. We showed that both forcings have a drawback in that, if the number of sufficiently excited modes is too low, anisotropy is bound to arise even at small scales. In the case of Euler forcing, this depends on both the range of forcing wavenumbers and its helicity contents. The ABC forcing, for which the amount of injected helicity cannot be controlled, excites only six modes and therefore always generates anisotropy at all resolved scales. Our second step was to analyze the scale- and direction-dependent anisotropy of homogeneous rotating turbulence. Surprisingly, anisotropy arises at all scales even at low rotation rate. In particular, we identified two anisotropic ranges with different features. In the large scales, directional anisotropy is larger and decreases with wavenumber. At smaller scales, it is much weaker—although still significant—and slowly increases with wavenumber all the way to the dissipative scales. Another interesting and original conclusion of this part of the work concerns the role of the Zeman scale and its link with the flow scale-dependent anisotropy. The Zeman scale was previously argued to be the characteristic lengthscale separating rotation-affected scales 2 from isotropic ones. Upon closer investigation using several simulations at different parameters, we found that the separating scale between large and weak anisotropy is rather the characteristic lengthscale at which rotation and dissipation effects balance. This result, however, does not contradict Zeman’s argument about isotropy recovery in the asymptotic limit of vanishing viscosity, since the separating scale vanishes at infinite Reynolds number, and therefore only the decreasing anisotropy range should persist and scales much smaller than the Zeman one may recover isotropy. Finally, we considered the von Kármán flow between two counter-rotating bladed disks in a cylindrical cavity. We repeated the separation space analysis in different small sub-regions, in order to question the possible analogies in the flow dynamics with that of homogeneous rotating turbulence. We found that, in the regions of the domain where the mean flow has a larger average rotation rate, the distributions of the statistics in separation space display some of the features typical of rotating turbulence
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Ferraro, Filippo Jacopo. "Magnetic anisotropies and exchange bias in ultrathin cobalt layers for the tunnel anisotropic magnetoresistance." Thesis, Université Grenoble Alpes (ComUE), 2015. http://www.theses.fr/2015GREAY086/document.
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Dans le cadre de l’étude des phénomènes magnétiques et de la spintronique qui sont présents aux échelles nanoscopiques nous avons étudié différents aspects des structures asymétriques de Pt/Co/AlOx. L’un des objectifs de cette thèse est le contrôle de l’oxydation et des propriétés magnétiques de ces multicouches. Nous avons combiné les mesures de structures (réflexion de Rayon-X), transports (Effet Hall anormal), et magnétiques (VSM-SQUID) afin de déterminer les rôles des effets magnétiques et d’interfaces. Un objectif était d’analyser le rôle de quelques monocouches (MCs) de CoO (qui peut se former lors de la sur oxydation de l’Al) sur les propriétés de la multicouche. Nous avons utilisé une technique de déposition avec un gradient d’épaisseur pour contrôler l’oxydation à l’échelle nanométrique. Nous avons établis que quelques monocouches (MCs) de CoO a un impact sur l’anisotropie de a multicouche. Pour approfondir l’effet de la couche de CoO, nous avons construit des bicouches ultrafines de Co(0.6nm)/CoO(0.6nm). Nous avons effectué des mesures refroidi sur champ sur ce système et trouvé un fort effet de couplage d'échange. Ces résultats indiquent que la couche CoO garde une forte anisotropie même en dans la limite des monocouches et permet de réfuter certains modèles sur l’effet d’échange bias et indique que les couches, couramment négligé, de CoO doivent être prises en considération dans le bilan énergétiques du système. Nous avons construits un appareil de mesure perpendiculaire de la magnétorésistance tunnel anisotrope (TAMR) à partir de la structure Pt/Co/AlOx. La TAMR est un effet de spintronique relativement récent dans lequel la rotation d’aimantation dans une électrode magnétique (combiné avec un couplage spin-orbite) peut entrainer un changement de la probabilité de l’effet tunnel, ce qui se manifeste comme un effet de magnétorésistance. Nous avons démontré qu’un contrôle précis de l’état d’oxydation est essentiel pour l’effet TAMR. La forte anisotropie magnétique induite nous permet d’atteindre des valeurs de TAMR plus grande comparée à celle des structures Pt/Co/AlOxIn the context of studying magnetic and spintronics phenomena occurring at the nanoscale, we investigated several aspects of Pt/Co/AlOx asymmetric structures. One of the objectives of this thesis was the control of the oxidation and the tailoring of the magnetic properties of these multilayers. We combined structural (X-Ray Reflectivity), transport (Anomalous Hall Effect) and magnetic measurements (VSM-SQUID), to study the interplay of magnetic and interfacial effects. One objective was to analyze the role that few monolayers (MLs) of CoO (which can form when overoxidizing the Al layer), could have on the properties of the stack. We used a wedge deposition techniques to control the oxidation on a subnanometer scale. We established that few MLs of CoO largely affect the total anisotropy of the stack. To further investigate the impact of the CoO, we engineered ultrathin Co(0.6nm)/CoO(0.6nm) bilayers. We performed field cooled measurements on this system and we found a large exchange bias anisotropy. These results indicate that the CoO keeps a large anisotropy even in the ML regime, help to rule out some of the models proposed to explain the exchange bias effect and imply that the usually neglected CoO presence must be considered in the energy balance of the system. We build perpendicular Tunneling Anisotropic MagnetoResistance (TAMR) devices based on the Pt/Co/AlOx structure. The TAMR is a relatively new spintronics effect in which the rotation of the magnetization in a single magnetic electrode (combined with the Spin-Orbit Coupling) can cause a change of the tunnel probability, which manifests as a magnetoresistance effect. We demonstrated that a careful control of the interface oxidation is crucial for the TAMR effect. The large induced magnetic anisotropy allowed us to achieve enhanced TAMR values compared to similar Pt/Co/AlOx structures
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Quarta, Francesco. "Implementazione numerica di modelli algebrici espliciti per il flusso termico e il tensore degli sforzi di Reynolds in moti turbolenti anisotropi stazionari." Master's thesis, Alma Mater Studiorum - Università di Bologna, 2019.
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In questo lavoro di tesi si è implementato un modello anisotropo per la turbolenza nel codice di calcolo agli elementi finiti FEMuS, in modo da sopperire alle mancanze derivanti dall'assunzione di Boussinesq per quanto riguarda il tensore degli sforzi di Reynolds e del flusso termico turbolento. Entrambe queste grandezze sono state implementate attraverso modelli algebrici espliciti e il codice così sviluppato è stato utilizzato per simulare il moto turbolento oltre un gradino con parete riscaldata per una corrente di sodio liquido. La bontà dei risultati è stata validata attraverso il confronto con diverse simulazioni DNS e sperimentali per la medesima configurazione.
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Edström, Alexander. "Theoretical and Computational Studies on the Physics of Applied Magnetism : Magnetocrystalline Anisotropy of Transition Metal Magnets and Magnetic Effects in Elastic Electron Scattering." Doctoral thesis, Uppsala universitet, Materialteori, 2016. http://urn.kb.se/resolve?urn=urn:nbn:se:uu:diva-304666.
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In this thesis, two selected topics in magnetism are studied using theoretical modelling and computational methods. The first of these is the magnetocrystalline anisotropy energy (MAE) of transition metal based magnets. In particular, ways of finding 3d transition metal based materials with large MAE are considered. This is motivated by the need for new permanent magnet materials, not containing rare-earth elements, but is also of interest for other technological applications, where the MAE is a key quantity. The mechanisms of the MAE in the relevant materials are reviewed and approaches to increasing this quantity are discussed. Computational methods, largely based on density functional theory (DFT), are applied to guide the search for relevant materials. The computational work suggests that the MAE of Fe1-xCox alloys can be significantly enhanced by introducing a tetragonality with interstitial B or C impurities. This is also experimentally corroborated. Alloying is considered as a method of tuning the electronic structure around the Fermi energy and thus also the MAE, for example in the tetragonal compound (Fe1-xCox)2B. Additionally, it is shown that small amounts (2.5-5 at.%) of various 5d dopants on the Fe/Co-site can enhance the MAE of this material with as much as 70%. The magnetic properties of several technologically interesting, chemically ordered, L10 structured binary compounds, tetragonal Fe5Si1-xPxB2 and Hexagonal Laves phase Fe2Ta1-xWx are also investigated. The second topic studied is that of magnetic effects on the elastic scattering of fast electrons, in the context of transmission electron microscopy (TEM). A multislice solution is implemented for a paraxial version of the Pauli equation. Simulations require the magnetic fields in the sample as input. A realistic description of magnetism in a solid, for this purpose, is derived in a scheme starting from a DFT calculation of the spin density or density matrix. Calculations are performed for electron vortex beams passing through magnetic solids and a magnetic signal, defined as a difference in intensity for opposite orbital angular momentum beams, integrated over a disk in the diffraction plane, is observed. For nanometer sized electron vortex beams carrying orbital angular momentum of a few tens of ħ, a relative magnetic signal of order 10-3 is found. This is considered realistic to be observed in experiments. In addition to electron vortex beams, spin polarised and phase aberrated electron beams are considered and also for these a magnetic signal, albeit weaker than that of the vortex beams, can be obtained.Felaktigt ISBN i den tryckta versionen: 9789155497149
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Azevedo, Carlos Alberto Cabral de. "Formulação alternativa para análise de domínios não-homogêneos e inclusões anisotrópicas via MEC." Universidade de São Paulo, 2007. http://www.teses.usp.br/teses/disponiveis/18/18134/tde-18102007-110753/.
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Este trabalho trata da análise de problemas planos de chapa compostos por materiais anisotrópicos, definidas em uma região ou no domínio por completo, utilizando-se o método dos elementos de contorno. As soluções fundamentais para problemas anisotrópicos, embora existentes, mostram-se difíceis de serem utilizadas devido à complexidade de sua formulação matemática ou da necessidade de se encontrar partes da solução numericamente. Nesse sentido, a formulação alternativa mostrada nesse trabalho permite o estudo de meios anisotrópicos utilizando-se as soluções fundamentais para meios isotrópicos nas representações integrais de problemas planos com campo de tensões iniciais. A região do domínio com propriedades anisotrópicas ou diferentes das propriedades elásticas de um meio isotrópico usado como referência é discretizada em células triangulares, enquanto que o contorno do problema é discretizado em elementos lineares. As componentes do tensor de tensões iniciais da região anisotrópica são definidas como uma correção das tensões elásticas do material isotrópico de referência através de uma matriz de penalização. Essa matriz, por sua vez, é obtida através de relações envolvendo as constantes elásticas de rigidez do meio desejado e os coeficientes elásticos de flexibilidade do meio isotrópico de referência. Essa técnica é particularmente adequada para a análise de inclusões anisotrópicas onde há a necessidade de discretizar apenas uma parte pequena do domínio, aumentando, portanto, pouco o número de graus de liberdade do sistema. Os resultados obtidos com a formulação proposta são comparados com os resultados numéricos existentes na literatura.This work deals with elastic 2D problems characterized by the presence of zones with different materials and anisotropic inclusions using the boundary element method. The anisotropy can be assumed either over the whole domain or defined only over some particular inclusions, which is the most usual case. Fundamental solutions for anisotropic domains, although well-known, lead to more complex formulations and may introduce difficulties when the analysis requires more complex material models as for instance plastic behavior, finite deformations, etc. The alternative formulation proposed in this work can be applied to anisotropic bodies using the classical fundamental solutions for 2D elastic isotropic domains plus correction given by an initial stress field. The domain region with anisotropic properties or only with different isotropic elastic parameters has to be discretized into cells to allow the required corrections, while the complementary part of the body requires only boundary discretization. The initial stress tensor to be applied to the anisiotropic region is defined as the isotropic material elastic stress tensor correction by introducing a local penalty matrix. This matrix is obtained by the difference between the elastic parameters between the reference values and the anisotropic material. This technique is particularly appropriate for anisotropic inclusion analysis, in which the domain discretization is required only over a small region, therefore increasing very little the number of degrees of freedom of the final algebraic system. The numerical results obtained by using the proposed formulation have demonstrated to be very accurate in comparison with either analytical solutions or the other numerical values.
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Koabaz, Mahmoud. "Contribution à l’étude des ondes de LAMB dans une plaque anisotrope : théorie et expérience." Thesis, Bordeaux 1, 2010. http://www.theses.fr/2010BOR14071/document.
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Le rayonnement d'une source ultrasonore située sur l'une des interfaces d'une plaque anisotrope est étudié. Le calcul du tenseur de Green est effectué dans le cas général d'un problème 3D. Une décomposition en multiples réflexions /réfractions, constituant une série de rayons au sein de la plaque, est utilisée pour une comparaison théorie-expérience dans le cas d'un mono cristal de Cuivre. La vitesse de phase et la vitesse d'énergie sont mesurées en fonction de la fréquence ou de la direction d'observation, pour une plaque de carbone-époxy unidirectionnels, et comparées avec la théorieThe ultrasonic radiation from a source located on one of the interfaces of an anisotropic plateis studied. The calculation of the Green tensor is performed in the general case of a 3Dproblem. Decomposition into multiple reflections /refractions, as a series of rays in the plate,is used for comparison between theory and experiment in the case of a single crystal of copper. The phase velocity and energy velocity are measured in terms of frequency ordirection of observation, for a plate of unidirectional carbon-epoxy, and compared withtheory
Books on the topic "Anisotropi"
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Groupe français de rhéologie. Colloque national. Rhéologie des matériaux anisotropes =: Rheology of anisotropic materials. Toulouse: Cepadues-Éditions, 1986.
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International Workshop on Seismic Anisotropy (6th 1994 Trondheim, Norway). Seismic anisotropy. Tulsa, Okla: Society of Exploration Geophysicists, 1996.
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Li, Quan, ed. Anisotropic Nanomaterials. Cham: Springer International Publishing, 2015. http://dx.doi.org/10.1007/978-3-319-18293-3.
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Vannucci, Paolo. Anisotropic Elasticity. Singapore: Springer Singapore, 2018. http://dx.doi.org/10.1007/978-981-10-5439-6.
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Freger, G. E. Spirally Anisotropic Composites. Berlin, Heidelberg: Springer Berlin Heidelberg, 2004.
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Givargizov, E. I. Highly anisotropic crystals. Dordrecht: D. Reidel Pub. Co., 1987.
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Freger, G. E., V. N. Kestelman, and D. G. Freger. Spirally Anisotropic Composites. Berlin, Heidelberg: Springer Berlin Heidelberg, 2004. http://dx.doi.org/10.1007/978-3-662-09975-9.
Full textBook chapters on the topic "Anisotropi"
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Giusfredi, Giovanni. "Propagazione della luce in mezzi anisotropi." In Manuale di Ottica, 751–902. Milano: Springer Milan, 2015. http://dx.doi.org/10.1007/978-88-470-5744-9_7.
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Pacault, A., J. Hoarau, and J. Favède. "Anisotropie Diamagnétique — Diamagnetic Anisotropy." In Eigenschaften der Materie in Ihren Aggregatzuständen, 141–67. Berlin, Heidelberg: Springer Berlin Heidelberg, 2013. http://dx.doi.org/10.1007/978-3-662-43334-8_2.
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Tax, Chantal M. W., Elena Kleban, Muhamed Baraković, Maxime Chamberland, and Derek K. Jones. "Magnetic Resonance Imaging of $$T_2$$- and Diffusion Anisotropy Using a Tiltable Receive Coil." In Mathematics and Visualization, 247–62. Cham: Springer International Publishing, 2021. http://dx.doi.org/10.1007/978-3-030-56215-1_12.
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AbstractThe anisotropic microstructure of white matter is reflected in various MRI contrasts. Transverse relaxation rates can be probed as a function of fibre-orientation with respect to the main magnetic field, while diffusion properties are probed as a function of fibre-orientation with respect to an encoding gradient. While the latter is easy to obtain by varying the orientation of the gradient, as the magnetic field is fixed, obtaining the former requires re-orienting the head. In this work we deployed a tiltable RF-coil to study $$T_2$$ T 2 - and diffusional anisotropy of the brain white matter simultaneously in diffusion-$$T_2$$ T 2 correlation experiments.
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Wit, A. L. "Anisotropy and anisotropic reentry in myocardial infarction." In Myocardial Ischemia and Arrhythmia, 83–94. Heidelberg: Steinkopff, 1994. http://dx.doi.org/10.1007/978-3-642-72505-0_7.
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Diersch, Hans-Jörg G. "Anisotropy." In FEFLOW, 227–35. Berlin, Heidelberg: Springer Berlin Heidelberg, 2013. http://dx.doi.org/10.1007/978-3-642-38739-5_7.
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Wackernagel, Hans. "Anisotropy." In Multivariate Geostatistics, 62–65. Berlin, Heidelberg: Springer Berlin Heidelberg, 2003. http://dx.doi.org/10.1007/978-3-662-05294-5_9.
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Brosius, Alexander, and Dorel Banabic. "Anisotropy." In CIRP Encyclopedia of Production Engineering, 1–8. Berlin, Heidelberg: Springer Berlin Heidelberg, 2016. http://dx.doi.org/10.1007/978-3-642-35950-7_6679-3.
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Gooch, Jan W. "Anisotropic." In Encyclopedic Dictionary of Polymers, 41. New York, NY: Springer New York, 2011. http://dx.doi.org/10.1007/978-1-4419-6247-8_668.
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Gooch, Jan W. "Anisotropy." In Encyclopedic Dictionary of Polymers, 41. New York, NY: Springer New York, 2011. http://dx.doi.org/10.1007/978-1-4419-6247-8_669.
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Chen, Zengtao, and Cliff Butcher. "Anisotropy." In Micromechanics Modelling of Ductile Fracture, 75–100. Dordrecht: Springer Netherlands, 2013. http://dx.doi.org/10.1007/978-94-007-6098-1_3.
Full textConference papers on the topic "Anisotropi"
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Lo, M. H., P. M. Tu, C. H. Wang, H. C. Kuo, S. C. Wang, H. W. Zan, C. Y. Chang, S. C. Hsu, Y. J. Cheng, and S. C. Huang. "Multilayer Epitaxial Lateral Overgrowth of Light Emitting Diode with Anisotropi-cally Etched GaN/sapphire Interface." In 2009 International Conference on Solid State Devices and Materials. The Japan Society of Applied Physics, 2009. http://dx.doi.org/10.7567/ssdm.2009.e-5-3l.
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Hilgert, Oliver, Susanne Höhler, and Holger Brauer. "Anisotropic HFI Welded Steel Pipes for Strain Based Design." In 2016 11th International Pipeline Conference. American Society of Mechanical Engineers, 2016. http://dx.doi.org/10.1115/ipc2016-64194.
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Generally isotropic behavior is assumed and demanded in line pipe specifications. Especially in strain based design, compressive and tensile strain capacity models rely on iso-tropic assumptions. On the other hand every pipe has got an anisotropic material characteristic which effects the performance in strain based design. In this contribution HFI-welded steel tubes are investigated due to their underlying material anisotropy. Depending on their basic strip weld material and production process the anisotropy differs from UOE or spiral welded pipes. Especially, in radial direction of steel pipe mechanical properties are challenging to gain. Thus two methods are suggested to characterize the anisotropic parameters in all three pipe directions. A small scale approach evaluating Lankford values and a full scale method evaluating Hill factors are applied. While Lankford method relies on strains, Hills method relies on stresses. Both methods are explained and validated by internal pressure and full scale bending tests. Using the anisotropy parameters, their effect on strain based design is analyzed — both experimentally and numerically. In the end it is shown that distinct anisotropies can provide a benefit for HFI-welded steel tubes concerning strain capacity in strain based design applications.
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lavsky, J., G. G. Long, A. J. Allen, L. Leblanc, M. Prystay, and C. Moreau. "Anisotropic Microstructure of Plasma-Sprayed Deposits." In ITSC 1998, edited by Christian Coddet. ASM International, 1998. http://dx.doi.org/10.31399/asm.cp.itsc1998p1577.
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Abstract The microstructure of plasma-sprayed deposits (PSD) is dominated by two void systems - interlamellar pores and intralamellar cracks - each with a different anisotropy. Varying anisotropics and crack-to-pore ratios within PSDs are responsible for the anisotropic properties observed in the deposits. While it is difficult to apply standard porosity measurement techniques to the assessment of anisotropic microstructures, novel techniques utilizing different approaches have recently emerged. Image analysis (IA) of impregnated PSD samples is the most direct technique. The structure is stabilized by impregnation and then polished and imaged. The limitations of IA lie in the impregnation process and in the subsequent polishing. Also, the images produced from anisotropic materials can be difficult to interpret quantitatively. The technique of small-angle neutron scattering (SANS) has recently been successfully applied to the study of PSDs. The major advantages of SANS are that it does not require sample preparation and that quantitative information can be gotten about the separate crack and pore systems, including their distinctive anisotropics. However, the relationship between the SANS results and the underlying structure is more complex and less intuitive than for IA, and the availability of the SANS technique is limited by the need to have access to a powerful neutron source, such as a reactor. Also, the two techniques present different views of the microstructure because of the different sensitivities in different parts of the size range. This paper compares results from IA and SANS from a set of thick plasma-sprayed ceramic deposits possessing a range of crack/pore microstructures, and discusses how the two techniques might complement one another.
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Unnikrishnan, Ginu U., Glenn D. Barest, David B. Berry, Amira I. Hussein, and Elise F. Morgan. "Influence of Specimen-Specific Trabecular Anisotropy on QCT-Based Finite Element Analyses of Lumbar Vertebra." In ASME 2012 Summer Bioengineering Conference. American Society of Mechanical Engineers, 2012. http://dx.doi.org/10.1115/sbc2012-80114.
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Quantitative computed tomography (QCT)-based finite element (FE) models provide better predictions of vertebral strength compared to traditional methods currently used in clinical diagnosis [1]. In QCT-based FE models, the intra- and inter-specimen variations in trabecular anisotropy are often ignored, despite evidence that the biomechanical behavior of the vertebra depends on the architecture of the vertebral trabecular bone [2]. A realistic representation of the specimen-specific, trabecular anisotropy in the FE models of vertebrae would potentially improve predictions of vertebral failure. The overall goal of this study was to evaluate the importance of incorporating specimen-specific, trabecular anisotropy for QCT-based FE predictions of vertebral stiffness and deformation patterns. The major aims of this study were (a) to compare the QCT-based FE results obtained with a constant, anisotropic, material model (the “generic-anisotropic” model) for trabecular bone to those obtained with a specimen-specific, anisotropic, material model and (b) to study the influence of degree of anisotropy (DA) on the FE predictions of vertebral stiffness.
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Wang, B. X., and C. Y. Zhao. "Polarized Radiative Transfer in Anisotropic Disordered Media With Short-Range Order." In ASME 2017 Heat Transfer Summer Conference. American Society of Mechanical Engineers, 2017. http://dx.doi.org/10.1115/ht2017-5051.
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The aim of this study is to present a general method to investigate radiative transfer in disordered media with a subwave-length, anisotropic short-range order and provide a fundamental understanding on the interplay between polarized radiative transfer and microstructural anisotropy as well short-range order. We show the anisotropy of short-range order, described by an anisotropic correlation length in Gaussian random permittivity model, induces a significant anisotropy of radiative properties. Here the photon scattering mean free path is derived using the Feynman diagrammatic expansion of self-energy, and the transport mean free path and phase function are calculated based on the diagrammatic representation of the irreducible vertex in the Bethe-Salpeter equation. We further consider the transport of polarized light in such media by directly solving Bethe-Salpeter equation (BSE) for photons, without the use of traditional vector radiative transfer equation (VRTE). The present method advantageously allows us to elegantly relate anisotropic structural parameters to polarized radiative transport properties and obtain more fundamental physical insights, because the approximations in all steps of our derivation are given explicitly with reasonable explanations from the exact ab-initio BSE. Moreover, through a polarization eigen-channel expansion technique for intensity tensor, we show that values of transport mean free path in different polarization eigen-channels are rather different, which are also strongly affected by structural anisotropy and short-range order. As a conclusion, this study depicts some fundamental physical features of polarized radiative transfer in disordered media, and is also valuable for potential applications of utilizing anisotropic short-range order in disordered media in manipulation of polarized radiative transfer.
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Thomopoulos, Stavros, and Jeffrey W. Holmes. "A Structural Basis for Anisotropy in Cardiac Fibroblast Populated Collagen Gels." In ASME 2004 International Mechanical Engineering Congress and Exposition. ASMEDC, 2004. http://dx.doi.org/10.1115/imece2004-61209.
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The development of anisotropic mechanical properties is critical for the successful function of many soft tissues. Load bearing tissues naturally develop varying degrees of anisotropy, presumably in response to their specific loading environment. For example, the scar tissue that forms after a myocardial infarction is structurally and mechanically anisotropic. To better understand the scar mechanics, we first need to develop structure-function relationships for collagen fiber networks. In order to improve the healing after myocardial infarction, a better understanding of the mechanical anisotropy is necessary. An in vitro collagen gel system can be used to control individual fiber network components and to determine the effect of each component on the mechanical properties of the gel. Previously, we demonstrated the ability to promote two different collagen gel structures, with two different levels of mechanical anisotropy [1]. The goal of the current study was to quantitatively relate the observed mechanical anisotropy to the collagen fiber structure. It was hypothesized that the anisotropy could be explained with a simple structural model, where the gel behavior is derived from the behavior of the individual fibers within the gel (i.e., the properties of the fibers, their orientation, and their level of slack).
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Nguyen, T. Dung, Houssem Badreddine, and Khémais Saanouni. "Non-Associative Finite Strain Plasticity Coupled With Anisotropic Ductile Damage for Metal Forming." In ASME 2012 11th Biennial Conference on Engineering Systems Design and Analysis. American Society of Mechanical Engineers, 2012. http://dx.doi.org/10.1115/esda2012-82797.
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This paper presents the formulation of an advanced mechanical model describing a wide class of anisotropic elastoplastic constitutive equations accounting for the strong coupling with the anisotropic ductile damage. This model is developed within the framework of thermodynamics of irreversible processes with state variables and the continuum damage mechanics. The plastic anisotropy is accounted for through a non-associative theory for which a plasticity yield criterion and the plastic potential are defined separately but considering the strong coupling between both phenomena. The damage anisotropy is defined by using a second rank tensor. The effect of damage on the mechanical fields (stress, hardening, plastic strain, etc…) is described by a fourth rank damage effect operator that is defined in the context of the hypothesis of total energy equivalence. A rotating frame formulation is used to fulfil the objectivity of the constitutive equations under finite transformation. Finally, in order to illustrate the predictive capabilities of the model, the parametric studies with some simple loading case are investigated and the results discussed on the light of the anisotropic character of the ductile damage and its interaction with the anisotropy of plastic flow.
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Kweon, Soondo, and Daniel S. Raja. "Damage and Anisotropy Evolution in the Free End Shear Problem." In ASME 2015 International Mechanical Engineering Congress and Exposition. American Society of Mechanical Engineers, 2015. http://dx.doi.org/10.1115/imece2015-52965.
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The evolution of microstructure occurs in the deformation of metals via texture evolution. The effect of the microstructural evolution, i.e., anisotropy evolution, on the free end shear problem is investigated. An anisotropic ductile fracture model that takes into account the evolution of the orthotropic axes in the matrix is employed to perform the above task. With the model, a well-known experiment that provides the evidence of anisotropy evolution, the free end cyclic torsion test, is simulated. For the simulation of the free end cyclic torsion test, an explicit numerical scheme for the free end shear simulation is proposed and performed to reproduce the experimental result of the free end torsion test. The simulation result reveals the physics of the shear damage process, which is that porosity evolves in the shear deformation of (induced) anisotropic materials due to the evolution of anisotropy. A series of the free end shear simulations reveal the effect of the interaction among the matrix anisotropy, porosity and void shape onto the deformation pattern and the ductile damage process of porous materials.
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Gaith, Mohamed S., and I. Alhayek. "The Measurement of Overall Elastic Stiffness and Bulk Modulus in Anisotropic Materials: Semiconductors." In ASME 2009 International Mechanical Engineering Congress and Exposition. ASMEDC, 2009. http://dx.doi.org/10.1115/imece2009-10097.
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In this study, the correlation between macroscopic and microscopic properties of the II-IV semiconductor compounds ZnX (X = S, Se, Te) is investigated. Based on constructing orthonormal tensor basis elements using the form-invariant expressions, the elastic stiffness for cubic system materials is decomposed into two parts; isotropic (two terms) and anisotropic parts. A scale for measuring the overall elastic stiffness of these compounds is introduced and its correlation with the calculated bulk modulus and lattice constants is analyzed. The overall elastic stiffness is calculated and found to be directly proportional to bulk modulus and inversely proportional to lattice constants. A scale quantitative comparison of the contribution of the anisotropy to the elastic stiffness and to measure the degree of anisotropy in an anisotropic material is proposed using the Norm Ratio Criteria (NRC). It is found that ZnS is the nearest to isotropy (or least anisotropic) while ZnTe is the least isotropic (or nearest to anisotropic) among these compounds. The norm and norm ratios are found to be very useful for selecting suitable materials for electro-optic devices, transducers, modulators, acousto-optic devices.
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Raghupathy, Ramesh, Spencer P. Lake, Edward A. Sander, and Victor H. Barocas. "Generalized Anisotropic Inverse Mechanics: Mechanical Anisotropy Correlates With Structural Anisotropy in Collagen Based Tissue Equivalents." In ASME 2010 Summer Bioengineering Conference. American Society of Mechanical Engineers, 2010. http://dx.doi.org/10.1115/sbc2010-19215.
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Few elastographic methods handle both anisotropy and inhomogeneity. Much of the focus has been on inhomogeneous materials that are locally isotropic. However, most load-bearing tissues (heart, ligament, blood vessels) are highly anisotropic, and the underlying structure is distinct and essential for function. With disease or damage, this structure is altered, and hence the potential for an elastographic tool that identifies regional changes in anisotropy is high. In this study we present a generalized anisotropic inverse mechanics (GAIM) method that is applicable to soft tissues and demonstrate its performance on tissue equivalents which serve as a convenient test case due to their inhomogeneity and the ease of pre-specifying the fiber alignment pattern.
Reports on the topic "Anisotropi"
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Pechan, M. J. Magnetic multilayer interface anisotropy. Office of Scientific and Technical Information (OSTI), January 1992. http://dx.doi.org/10.2172/6958467.
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Pechan, M. J. Magnetic multilayer interface anisotropy. Office of Scientific and Technical Information (OSTI), January 1991. http://dx.doi.org/10.2172/5158883.
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Pechan, M. J. Magnetic multilayer interface anisotropy. Office of Scientific and Technical Information (OSTI), January 1990. http://dx.doi.org/10.2172/6554380.
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Lee, Hung-Mou, and Chen-Kuo Yu. A Theorem of Anisotropic Absorbers. Fort Belvoir, VA: Defense Technical Information Center, March 1997. http://dx.doi.org/10.21236/ada323831.
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Cheng, C. Z. Magnetospheric equilibrium with anisotropic pressure. Office of Scientific and Technical Information (OSTI), July 1991. http://dx.doi.org/10.2172/5730952.
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Nikkel, D. J., D. S. Nath, A. A. Brown, and J. Casey. Modeling of Anisotropic Inelastic Behavior. Office of Scientific and Technical Information (OSTI), February 2000. http://dx.doi.org/10.2172/793453.
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Sahu, D., A. Langner, and Thomas F. George. Specific Heat of Anisotropic Superconductors. Fort Belvoir, VA: Defense Technical Information Center, July 1990. http://dx.doi.org/10.21236/ada225031.
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Li, Liang-shi. Anisotropy in CdSe quantum rods. Office of Scientific and Technical Information (OSTI), January 2003. http://dx.doi.org/10.2172/827094.
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Evans, Jordan Andrew. Nuclear Reactor Materials and Anisotropy. Office of Scientific and Technical Information (OSTI), December 2019. http://dx.doi.org/10.2172/1578013.
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Moss, W., and J. Levatin. MOSSFRAC: An anisotropic 3D fracture model. Office of Scientific and Technical Information (OSTI), August 2006. http://dx.doi.org/10.2172/894759.
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