Articles de revues sur le sujet « Anisotropie distribuée »
Pour voir les autres types de publications sur ce sujet consultez le lien suivant : Anisotropie distribuée.
Créez une référence correcte selon les styles APA, MLA, Chicago, Harvard et plusieurs autres
Consultez les 50 meilleurs articles de revues pour votre recherche sur le sujet « Anisotropie distribuée ».
À côté de chaque source dans la liste de références il y a un bouton « Ajouter à la bibliographie ». Cliquez sur ce bouton, et nous générerons automatiquement la référence bibliographique pour la source choisie selon votre style de citation préféré : APA, MLA, Harvard, Vancouver, Chicago, etc.
Vous pouvez aussi télécharger le texte intégral de la publication scolaire au format pdf et consulter son résumé en ligne lorsque ces informations sont inclues dans les métadonnées.
Parcourez les articles de revues sur diverses disciplines et organisez correctement votre bibliographie.
1
Rongkonusa, Melisa, Gerald Tamuntuan et Guntur Pasau. « Analisis Anisotropi Suseptibilitas Magnetik Batuan Beku Lengan Utara Sulawesi ». Jurnal MIPA 6, no 1 (2 mai 2017) : 8. http://dx.doi.org/10.35799/jm.6.1.2017.15846.
Texte intégralRésumé :
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
2
Hasheminejad, S. M., et M. Maleki. « Effect of Interface Anisotropy on Elastic Wave Propagation in Particulate Composites ». Journal of Mechanics 24, no 1 (mars 2008) : 79–93. http://dx.doi.org/10.1017/s1727719100001581.
Texte intégralRésumé :
ABSTRACTThe scattering of time harmonic plane longitudinal and transverse elastic waves in a composite consisting of randomly distributed identical isotropic spherical inclusions embedded in an isotropic matrix with anisotropic interface layers is examined. The interface region is modeled as a spherically isotropic shell of finite thickness with five independent elastic constants. The Frobenius power series solution method is utilized to deal with the interface anisotropy and the effect of random distribution of particulates in the composite medium is taken into account via a recently developed generalized self-consistent multiple scattering model. Numerical values of phase velocities and attenuations of coherent plane waves as well as the effective elastic constants are obtained for a moderately wide range of frequencies, particle concentrations, and interface anisotropies. The numerical results reveal the significant dependence of phase velocities and effective elastic constants on the interface properties. They show that interface anisotropy can moderately depress the effective phase velocities and the elastic moduli, but leave effective attenuation nearly unaffected, especially at low and intermediate frequencies. Limiting cases are considered and good agreements with recent solutions have been obtained.
3
Liu, Honglei, Wenhao Shi et Tianhong Yang. « Numerical Modeling on Anisotropy of Seepage and Stress Fields of Stratified Rock Slope ». Mathematical Problems in Engineering 2020 (7 avril 2020) : 1–10. http://dx.doi.org/10.1155/2020/4956025.
Texte intégralRésumé :
Stratified rock mass is a common rock mass structure and distributed widely on the earth’s crust. High-density distribution of stratified structural planes in the stratified rock mass has a great influence on the mechanics properties of the rock mass, such as anisotropy of stress and seepage. Therefore, anisotropy is the inherent characteristic that must be considered in the stratified rock mass as well as the stratified rock slope stability. According to the anisotropic characteristics of stratified rock mass, an anisotropic seepage-stress coupled model for the mechanical behavior of stratified rock slope is proposed based on the anisotropy elasticity theory. The model is validated by simulating seepage and stress fields of an idealized slope using the finite element method. The deformation and stress-dependent permeability of the slope are predicted and compared well with the previous study, thus confirming its capability in characterizing the response of rock slope that is dominantly affected by rock anisotropy. Finally, the model is used to simulate the anisotropic properties of a stratified rock slope of Fushun west open-pit mine, China. The simulation is in good agreement with the actual measurement, which means the proposed model is capable of simulating anisotropic properties of the stratified rock slope.
4
Stiskalek, Richard, John Veitch et Chris Messenger. « Are stellar-mass binary black hole mergers isotropically distributed ? » Monthly Notices of the Royal Astronomical Society 501, no 1 (21 novembre 2020) : 970–77. http://dx.doi.org/10.1093/mnras/staa3613.
Texte intégralRésumé :
ABSTRACT The Advanced LIGO and Advanced Virgo gravitational wave detectors have detected a population of binary black hole mergers in their first two observing runs. For each of these events, we have been able to associate a potential sky location region represented as a probability distribution on the sky. Thus, at this point we may begin to ask the question of whether this distribution agrees with the isotropic model of the Universe, or if there is any evidence of anisotropy. We perform Bayesian model selection between an isotropic and a simple anisotropic model, taking into account the anisotropic selection function caused by the underlying antenna patterns and sensitivity of the interferometers over the sidereal day. We find an inconclusive Bayes factor of 1.3: 1, suggesting that the data from the first two observing runs are insufficient to pick a preferred model. However, the first detections were mostly poorly localized in the sky (before the Advanced Virgo joined the network), spanning large portions of the sky and hampering detection of potential anisotropy. It will be appropriate to repeat this analysis with events from the recent third LIGO observational run and a more sophisticated cosmological model.
5
Trach, V. M., A. V. Podvornyi et N. B. Zhukova. « Stability of non-thin anisotropic cylindrical shells in spatial position under distributed lateral pressure ». Bulletin of Taras Shevchenko National University of Kyiv. Series : Physics and Mathematics, no 2 (2023) : 152–55. http://dx.doi.org/10.17721/1812-5409.2023/2.26.
Texte intégralRésumé :
A three-dimensional approach to solving the problem of stability of non-thin cylindrical anisotropic layered shells under distributed lateral pressure is proposed. Based on the modified Hu-Washizu variational principle, a three-dimensional system of homogeneous differential stability equations is obtained for the calculation of shells, the anisotropy of which is characterized by a material with one plane of elastic symmetry. The solution of the three-dimensional system was carried out using the Bubnov-Galerkin methods and numerical discrete orthogonalization. The influence of an increase in the number of cross-laid layers of the same thickness on the stability of an anisotropic cylindrical shell is studied. The results of the solution are presented by graphs and their analysis is given.
6
Li, Wei, Douglas R. Schmitt, Maria Tibbo et Changchun Zou. « A program to calculate the state of stress in the vicinity of an inclined borehole through an anisotropic rock formation ». GEOPHYSICS 84, no 5 (1 septembre 2019) : F103—F118. http://dx.doi.org/10.1190/geo2018-0097.1.
Texte intégralRésumé :
A borehole existing in any geologic formation concentrates the far-field tectonic and overburden stresses amplifying the magnitudes of certain stress components near the borehole. It is important to understand the magnitudes and patterns of this stress concentration because these lead to damage and can even collapse the borehole if sufficiently strong. The solution of the stress distributed near a borehole can be complicated considering the elastic anisotropy of rocks. We have developed programs (ASCIB3D) in MATLAB and Python to model the stress distribution around an inclined borehole in an arbitrarily oriented anisotropic medium. The program is built on the Lekhnitskij-Amadei solution. The input orientation of the far-field stresses and the elastic stiffness matrix of the medium into the program are geology angles instead of the rotation angles shown in previous studies, making the code more convenient for users. The sign convention for the inverse function, which is ignored in previous studies, is discussed in detail. The results indicate that the program ASCIB3D is a useful tool for modeling the stress distributed around an inclined borehole in the anisotropic formation and analyzing the effect of anisotropy and borehole inclination on stress distribution. The inclination and azimuth of the borehole and the anisotropy of the rocks affect the orientation and strength of the stress concentration.
7
Abbasnejadfard, Morteza, Morteza Bastami et Afshin Fallah. « Investigation of anisotropic spatial correlations of intra-event residuals of multiple earthquake intensity measures using latent dimensions method ». Geophysical Journal International 222, no 2 (21 mai 2020) : 1449–69. http://dx.doi.org/10.1093/gji/ggaa255.
Texte intégralRésumé :
SUMMARY Considering spatial correlation of multiple earthquake intensity measures (IMs) is of particular importance in loss assessment of spatially distributed assets. This subject has been investigated in previous studies under the assumption of isotropy. Considering the fact that the assumption of isotropy is not valid in general, the present study employs a non-separable covariance model based on latent dimensions method to investigate anisotropic properties of spatial correlations and cross-correlations of intra-event residuals of multiple earthquake IMs. This method leads to the generation of valid covariance matrix in order to model anisotropic spatially distributed multivariate random fields. Two sets of IMs are considered in this study; the first set consists of peak ground intensity values (acceleration, velocity, and displacement), and the second set consists of spectral accelerations at three different periods. Data of 10 earthquake events in California and Japan are utilized in this study to estimate parameters of marginal and cross-covariance models. Moreover, parameters of covariance model of regional site condition, which is considered as average shear wave velocity of top 30 m of soil profile (Vs30), are obtained in order to investigate the effect of local sited conditions on spatial correlations of IMs. It is shown that maximum range and anisotropy ratio of covariance models of intra-event residuals of IMs are correlated with those of Vs30 values. Also, it is observed that the anisotropy direction of residuals of IMs is consistent with anisotropy direction of Vs30 values. Finally, predictive models are proposed to obtain marginal and cross-covariance functions for different earthquake IMs considering anisotropy.
8
MALARZ, K. « A SIMPLE SOLID-ON-SOLID MODEL OF EPITAXIAL FILM GROWTH : SUBMONOLAYER SUBSTRATE COVERAGE ». International Journal of Modern Physics C 11, no 08 (décembre 2000) : 1561–66. http://dx.doi.org/10.1142/s0129183100001449.
Texte intégralRésumé :
In this work, we investigate the influence of substrate temperature on the surface morphology for substrate coverage below one monolayer. The model of film growth is based on random deposition enriched by limited surface diffusion. Also, anisotropy in the growth is involved. We found from computer simulations for the simple cubic lattice and solid-on-solid model that the surface morphology changes with increasing temperature from isotropically distributed isolated small islands through anisotropic 1D stripes to larger 2D anisotropic islands and again randomly distributed single atoms. The transition is also marked in height–height correlation function dependence on temperature as directly seen by snapshots from simulations. The results are in good qualitative agreement with already published results of kinetic Monte Carlo simulations as well as with some experimental data.
9
Безверхний, А. И., А. Д. Таланцев, Ю. Е. Калинин, А. В. Ситников, В. A. Никитенко, О. В. Коплак, О. С. Дмитриев et Р. Б. Моргунов. « Магнитная анизотропия многослойных гетероструктур [(Co-=SUB=-41-=/SUB=-Fe-=SUB=-39-=/SUB=-B-=SUB=-20-=/SUB=-)-=SUB=-x-=/SUB=-(SiO-=SUB=-2-=/SUB=-)-=SUB=-100-x-=/SUB=-/Bi-=SUB=-2-=/SUB=-Te-=SUB=-3-=/SUB=-]-=SUB=-47-=/SUB=- ». Физика твердого тела 61, no 2 (2019) : 266. http://dx.doi.org/10.21883/ftt.2019.02.47124.235.
Texte intégralRésumé :
AbstractMagnetic anisotropy values are obtained for [(Co_41Fe_39B_20)_ x (SiO_2)_100 – _ x /Bi_2Te_3]_47 heterostructures consisting of SiO_2 alternating layers, CoFeB nanoparticles distributed in them, and Bi_2Te_3 layers with ferromagnetic resonance and magnetometry. The heterostructures have anisotropy of ~10^6 erg/cm^3, which orients the magnetic moment in films plane. The films are not solid, but they disintegrate into CoFeB nanoparticles with an average diameter of 5 nm during deposition, which corresponds to the blocking magnetization temperature of ~30 K during their saturation magnetization of M _ S = 720 emu/cm^3. The relationship between anisotropy constant and thickness of the layers of the heterostructures is nonmonotonic due to competition between surface and bulk anisotropies of the ferromagnetic granules, which the films are made of.
10
Kumar, Rajneesh, et Raj Rani Gupta. « Deformation due to various sources in a fibre-reinforced anisotropic generalized thermoelastic medium ». Canadian Journal of Physics 87, no 2 (février 2009) : 179–87. http://dx.doi.org/10.1139/p09-017.
Texte intégralRésumé :
The present investigation is concerned with the deformation of a fibre-reinforced, anisotropic, generalized thermoelastic medium subjected to mechanical and thermal sources acting on the plane surface. Close-form solutions for stresses and temperature distribution are derived using Laplace transforms for time and Fourier transforms for space. As an application of the approach concentrated, uniformly distributed, and linearly distributed sources are taken. A numerical inversion technique is applied to obtain the solution in the physical domain. Effects of anisotropy and thermal relaxation are shown graphically on the resulting quantities.
11
Zheng, Kun, Yu Miao, Tong Li, Shuang-Long Yang, Li Xi, Yang Yang, Dun Zhao et De-Sheng Xue. « Anti-function solution of uniaxial anisotropic Stoner–Wohlfarth model ». Chinese Physics B 31, no 4 (1 avril 2022) : 040202. http://dx.doi.org/10.1088/1674-1056/ac401e.
Texte intégralRésumé :
The anti-trigonometric function is used to strictly solve the uniaxial anisotropic Stoner–Wohlfarth (SW) model, which can obtain the relation of the angle α(θ) between the magnetization (the anisotropy field) and the applied magnetic field. Using this analytic solution, the hysteresis loops of uniaxial anisotropic SW particles magnetized in typical directions could be numerically calculated. Then, the hysteresis loops are obtained in randomly distributed SW particle ensembles while ignoring the dipole interaction among them with the analytic solution. Finally, the correctness of the analytic solution is verified by the exact solutions of remanence, switching field, and coercivity from the SW model. The analytic solution provides an important reference for understanding the magnetizing and magnetization reversal processes of magnetic materials.
12
Thomopoulos, Stavros, Gregory M. Fomovsky, Preethi L. Chandran et Jeffrey W. Holmes. « Collagen Fiber Alignment Does Not Explain Mechanical Anisotropy in Fibroblast Populated Collagen Gels ». Journal of Biomechanical Engineering 129, no 5 (15 février 2007) : 642–50. http://dx.doi.org/10.1115/1.2768104.
Texte intégralRésumé :
Many load-bearing soft tissues exhibit mechanical anisotropy. In order to understand the behavior of natural tissues and to create tissue engineered replacements, quantitative relationships must be developed between the tissue structures and their mechanical behavior. We used a novel collagen gel system to test the hypothesis that collagen fiber alignment is the primary mechanism for the mechanical anisotropy we have reported in structurally anisotropic gels. Loading constraints applied during culture were used to control the structural organization of the collagen fibers of fibroblast populated collagen gels. Gels constrained uniaxially during culture developed fiber alignment and a high degree of mechanical anisotropy, while gels constrained biaxially remained isotropic with randomly distributed collagen fibers. We hypothesized that the mechanical anisotropy that developed in these gels was due primarily to collagen fiber orientation. We tested this hypothesis using two mathematical models that incorporated measured collagen fiber orientations: a structural continuum model that assumes affine fiber kinematics and a network model that allows for nonaffine fiber kinematics. Collagen fiber mechanical properties were determined by fitting biaxial mechanical test data from isotropic collagen gels. The fiber properties of each isotropic gel were then used to predict the biaxial mechanical behavior of paired anisotropic gels. Both models accurately described the isotropic collagen gel behavior. However, the structural continuum model dramatically underestimated the level of mechanical anisotropy in aligned collagen gels despite incorporation of measured fiber orientations; when estimated remodeling-induced changes in collagen fiber length were included, the continuum model slightly overestimated mechanical anisotropy. The network model provided the closest match to experimental data from aligned collagen gels, but still did not fully explain the observed mechanics. Two different modeling approaches showed that the level of collagen fiber alignment in our uniaxially constrained gels cannot explain the high degree of mechanical anisotropy observed in these gels. Our modeling results suggest that remodeling-induced redistribution of collagen fiber lengths, nonaffine fiber kinematics, or some combination of these effects must also be considered in order to explain the dramatic mechanical anisotropy observed in this collagen gel model system.
13
Izzati Khalidah Khalid, Nor Fadzillah Mohd Mokhtar et Nurul Hafizah Zainal Abidin. « Thermogravitational Convection in a Controlled Rotating Darcy-Brinkman Nanofluids Layer Saturated in an Anisotropic Porous Medium Subjected to Internal Heat Source ». Journal of Advanced Research in Numerical Heat Transfer 14, no 1 (11 octobre 2023) : 70–90. http://dx.doi.org/10.37934/arnht.14.1.7090.
Texte intégralRésumé :
Thermogravitational convection in a controlled rotating Darcy-Brinkman nanofluids layer saturated in an anisotropic porous medium heated from below is Thermogravitational convection in a controlled rotating Darcy-Brinkman nanofluids layer saturated in an anisotropic porous medium heated from below is investigated. The presence of a uniformly distributed internal heat source and considers the Brinkman model for different boundary conditions: rigid-rigid, free-free, and lower-rigid and upper-free are considered. The effect of a control strategy involving sensors located at the top plate and actuators positioned at the bottom plate of the nanofluids layer is analysed. Linear stability analysis based on normal mode technique is employed. The resulting eigenvalue problem is solved numerically using the Galerkin method implemented with Maple software. The model used for the nanofluids associates with the mechanisms of Brownian motion and thermophoresis. The influences of the internal heat source strength, mechanical anisotropy parameter, modified diffusivity ratio, nanoparticles concentration Darcy-Rayleigh number and nanofluids Lewis number are found to advance the onset of convection. Conversely, the Darcy number, thermal anisotropy parameter, porosity, rotation, and controller effects are observed to slow down the process of convective instability.investigated. The presence of a uniformly distributed internal heat source and considers the Brinkman model for different boundary conditions: rigid-rigid, free-free, and lower-rigid and upper-free are considered. The effect of a control strategy involving sensors located at the top plate and actuators positioned at the bottom plate of the nanofluids layer is analysed. Linear stability analysis based on normal mode technique is employed. The resulting eigenvalue problem is solved numerically using the Galerkin method implemented with Maple software. The model used for the nanofluids associates with the mechanisms of Brownian motion and thermophoresis. The influences of the internal heat source strength, mechanical anisotropy parameter, modified diffusivity ratio, nanoparticles concentration Darcy-Rayleigh number and nanofluids Lewis number are found to advance the onset of convection. Conversely, the Darcy number, thermal anisotropy parameter, porosity, rotation, and controller effects are observed to slow down the process of convective instability.
14
Wang, Bitao, Michele Cappellari et Yingjie Peng. « Physical explanation for the galaxy distribution on the (λR, ε) and (V/σ, ε) diagrams or for the limit on orbital anisotropy ». Monthly Notices of the Royal Astronomical Society : Letters 500, no 1 (janvier 2020) : L27—L31. http://dx.doi.org/10.1093/mnrasl/slaa176.
Texte intégralRésumé :
ABSTRACT In the (λR, ε) and (V/σ, ε) diagrams for characterizing dynamical states, the fast-rotator galaxies (both early type and spirals) are distributed within a well-defined leaf-shaped envelope. This was explained as due to an upper limit to the orbital anisotropy increasing with galaxy intrinsic flattening. However, a physical explanation for this empirical trend was missing. Here, we construct Jeans Anisotropic Models (JAM), with either cylindrically or spherically aligned velocity ellipsoid (two extreme assumptions), and each with either spatially constant or variable anisotropy. We use JAM to build mock samples of axisymmetric galaxies, assuming on average an oblate shape for the velocity ellipsoid (as required to reproduce the rotation of real galaxies), and limiting the radial anisotropy β to the range allowed by physical solutions. We find that all four mock samples naturally predict the observed galaxy distribution on the (λR, ε) and (V/σ, ε) diagrams, without further assumptions. Given the similarity of the results from quite different models, we conclude that the empirical anisotropy upper limit in real galaxies, and the corresponding observed distributions in the (λR, ε) and (V/σ, ε) diagrams, are due to the lack of physical axisymmetric equilibrium solutions at high β anisotropy when the velocity ellipsoid is close to oblate.
15
Zhao, Mengzhuo, Hu Zhang, Cancan Chen, Chenxia Wang, Yan Liu, Juan Li et Tiejun Cui. « The Classification of Reflectance Anisotropy and Its Application in Albedo Retrieval ». Atmosphere 13, no 8 (26 juillet 2022) : 1182. http://dx.doi.org/10.3390/atmos13081182.
Texte intégralRésumé :
The land surface albedo reflects the ability of the surface to reflect solar radiation and is a critical physical variable in the study of the Earth’s energy budget and global climate change. Algorithms for the retrieval of albedo usually require multi-angle measurements due to surface anisotropy. However, most of the satellites cannot currently provide sufficient and well-distributed observations; therefore, the accuracy of remotely sensed albedo is constrained. Based on the Moderate-Resolution Imaging Spectroradiometer (MODIS) Bidirectional Reflectance Distribution Function (BRDF) and albedo product (MCD43A1), this study proposed a method to further subdivide reflectance anisotropy and build an updated database of BRDF archetype, using both the Anisotropic Flat Index (AFX) and Perpendicular Anisotropic Flat Index (PAFX). The BRDF archetypes were used to fit the corresponding MODIS BRDF, and the optimal number of BRDF archetype categories was determined according to the tendency of fitting error. The effect of surface anisotropy and observation noise on albedo retrieval were explored based on simulated MODIS reflectance. Finally, the BRDF archetype A2P2 was taken as prior knowledge to retrieve albedo from a different number of MODIS observations, and the result was validated by the high-quality MODIS albedo product. The results show that the fitting error between BRDF archetypes and MODIS BRDF shows a rapid decline when introducing the PAFX in the classification process. A 3-by-3 matrix of BRDF archetypes, which occupy 73.44% and 70.13% of the total decline in the red and NIR band, can be used to represent the characteristics of reflectance anisotropy. The archetype A2P2 may be used as prior knowledge to improve the albedo retrieval from insufficient observations. The validation results based on MODIS observations show that the archetype A2P2-based albedo can reach root-mean-square errors (RMSEs) of no more than 0.03.
16
Vélez, José A., Georgios P. Tsoflias, Ross A. Black, Cornelis J. Van der Veen et Sridhar Anandakrishnan. « Distribution of preferred ice crystal orientation determined from seismic anisotropy : Evidence from Jakobshavn Isbræ and the North Greenland Eemian Ice Drilling facility, Greenland ». GEOPHYSICS 81, no 1 (1 janvier 2016) : WA111—WA118. http://dx.doi.org/10.1190/geo2015-0154.1.
Texte intégralRésumé :
Preferred crystal orientation fabrics (COFs) within an ice sheet or glacier are typically found from ice cores. We conducted experiments at the North Greenland Eemian Ice Drilling (NEEM) facility ice core location, where COF data were available at Jakobshavn Isbræ west Greenland, to test if COF can be determined seismically. We used observations of anisotropic seismic wave propagation on multioffset gathers and englacial imaging from a 2D reflection profile. Anisotropy analysis of the NEEM data yielded mean c-axes distributed over a conical region of 30° to 32° from vertical. No internal ice seismic reflectors were imaged. Direct COF measurements collected in the ice core agreed with the seismic observations. At Jakobshavn Isbræ, we used a multioffset gather and a 2D reflection profile, but we lacked ice core data. Englacial reflectors allowed the determination of ice column interval properties. Anisotropy analysis found that the upper 1640 m of the ice column consisted of cold ([Formula: see text]) and mostly isotropic ice with c-axes distributed over a conical region of 80° from vertical. The lower 300 m of the ice column was characterized by warm ([Formula: see text]) ice with COF. These observations were consistent with complex ice fabric development and temperature estimations over the same region of Jakobshavn Isbræ. This study demonstrated that the ice sheet and glacier ice anisotropy information can be gained from seismic field observations.
17
Allen, Rebecca, et Shuyu Sun. « Computing and Comparing Effective Properties for Flow and Transport in Computer-Generated Porous Media ». Geofluids 2017 (2017) : 1–24. http://dx.doi.org/10.1155/2017/4517259.
Texte intégralRésumé :
We compute effective properties (i.e., permeability, hydraulic tortuosity, and diffusive tortuosity) of three different digital porous media samples, including in-line array of uniform shapes, staggered-array of squares, and randomly distributed squares. The permeability and hydraulic tortuosity are computed by solving a set of rescaled Stokes equations obtained by homogenization, and the diffusive tortuosity is computed by solving a homogenization problem given for the effective diffusion coefficient that is inversely related to diffusive tortuosity. We find that hydraulic and diffusive tortuosity can be quantitatively different by up to a factor of ten in the same pore geometry, which indicates that these tortuosity terms cannot be used interchangeably. We also find that when a pore geometry is characterized by an anisotropic permeability, the diffusive tortuosity (and correspondingly the effective diffusion coefficient) can also be anisotropic. This finding has important implications for reservoir-scale modeling of flow and transport, as it is more realistic to account for the anisotropy ofboththe permeability and the effective diffusion coefficient.
18
Newman, Daniel, John Lindsay et Jaclyn Cockburn. « Measuring Hyperscale Topographic Anisotropy as a Continuous Landscape Property ». Geosciences 8, no 8 (28 juillet 2018) : 278. http://dx.doi.org/10.3390/geosciences8080278.
Texte intégralRésumé :
Several landforms are known to exhibit topographic anisotropy, defined as a directional inequality in elevation. The quantitative analysis of topographic anisotropy has largely focused on measurements taken from specific landforms, ignoring the surrounding landscape. Recent research has made progress in measuring topographic anisotropy as a distributed field in natural landscapes. However, current methods are computationally inefficient, as they require specialized hardware and computing environments, or have a limited selection of scales that undermines the feasibility and quality of multiscale analyses by introducing bias. By necessity, current methods operate with a limited set of scales, rather than the full distribution of possible landscapes. Therefore, we present a method for measuring topographic anisotropy in the landscape that has the computational efficiency required for hyperscale analysis by using the integral image filtering approach to compute oriented local topographic position (LTP) measurements, coupled with a root-mean-square deviation (RMSD) model that compares directional samples to an omnidirectional sample. Two tools were developed: One to output a scale signature for a single cell, and the other to output a raster containing the maximum anisotropy value across a range of scales. The performances of both algorithms were tested using two data sets containing repetitive, similarly sized and oriented anisotropic landforms, including a dune field and a drumlin field. The results demonstrated that the method presented has the robustness and sensitivity to identify complex hyperscale anisotropy such as nested features (e.g., a drumlin located within a valley).
19
Zhu, Wei, Luanxiao Zhao et Rui Shan. « Modeling effective elastic properties of digital rocks using a new dynamic stress-strain simulation method ». GEOPHYSICS 82, no 6 (1 novembre 2017) : MR163—MR174. http://dx.doi.org/10.1190/geo2016-0556.1.
Texte intégralRésumé :
We have developed a dynamic stress-strain simulation methodology to compute effective elasticity on digital rocks in a wide range of frequency based on the rotated staggered grid finite-difference method. The primary advantage of this simulator lies in characterizing the anisotropic behavior of complex porous rocks by setting specified boundary conditions along specified directions: The edges perpendicular to the propagating wave are applied with a strain boundary condition, and the edges parallel to the propagating wave are applied with a periodic boundary condition. The accuracy of the simulator is validated by comparing the simulating results in microinhomogeneous porous media containing randomly distributed inclusions and aligned oriented cracks, with that obtained by effective medium theories of self-consistent approximation in isotropic and anisotropic domains. This dynamic simulator can successfully capture anisotropic magnitude of rocks containing needle-like inclusions with different degrees of alignment. For real digital rock saturated with viscoelastic fluids, it is able to predict the dependence of velocities and attenuating factors on the frequency. We found that the magnitude of dispersion increases with the increase of pore fluid viscosity. Therefore, this method offers a robust and effective tool to compute effective elastic properties and anisotropy for real complex porous rocks.
20
Abrashkevych, Yurii, Hryhorii Machyshyn, Oleksandr Marchenko, Maksym Balaka et Olena Zhukova. « Mechanical strength increasing of abrasive reinforced wheel ». Strength of Materials and Theory of Structures, no 108 (30 mai 2022) : 295–308. http://dx.doi.org/10.32347/2410-2547.2022.108.295-308.
Texte intégralRésumé :
The mechanical strength of unreinforced abrasive wheels is determined by centrifugal and bending forces, but their distribution during reinforcement is unknown. It was assumed that the stresses are distributed evenly, but a comparison of calculations on the theory of elasticity and real characteristics on a special stand showed complete discrepancy. Tensile tests of the wheels made it possible to compare the stresses results in the circumferential and radial directions. Was found that the reinforced wheel is an anisotropic body. Anisotropy can be reduced by displacing one reinforcement mesh relatively to the other by angle of 45°. In this paper, a mathematical model of the stress-strain state of the abrasive reinforced wheel was developed, taking into account the anisotropy of its properties. To determine the centrifugal forces, the theory of elasticity for an orthotropic body is applied. The bending forces that arise in the working wheel were determined during solving the problem of the distribution of deformations in the anisotropic annular plate rigidly fixed along the inner contour. As a result of experimental studies, it was found that stresses reach 8...23 MPa, which can be compared with the ultimate strength of the wheel matrix. The elastic module of the wheel matrix is noticeably greater than the elastic module of the reinforcing mesh, which practically does not perceive the load at the initial stage. The developed mathematical model of the strength indicators for abrasive reinforced wheels makes it possible to predict their reliability and safe operation.
21
Li, Xiangchun, Zhenxing An, Qi Zhang, Xiaolong Chen, Xinwei Ye et Suye Jia. « Analysis of Resistivity Anisotropy of Loaded Coal Samples ». Advances in Materials Science and Engineering 2020 (4 juin 2020) : 1–13. http://dx.doi.org/10.1155/2020/9016583.
Texte intégralRésumé :
In this paper, an experimental study of the variation of resistivity of coal samples in different bedding directions at 1 MHz frequency was performed by establishing an experimental system for resistivity testing of coal under triaxial stress. The low-pressure nitrogen gas adsorption (LP-N2GA) experiment and scanning electron microscopy (SEM) were obtained to analyze the pore-fracture structural characteristics of coal samples and the influence on resistivity anisotropy. Furthermore, the fundamental cause of anisotropy of coal resistivity is expounded systematically. The results show that the resistivity of loaded coal decreased first before increasing. The ionic conductance and the high degree of metamorphism slow down the decrease of resistivity. The distribution of pore and fracture structures is anisotropic. The connected pores and fractures are mainly distributed along the parallel bedding direction. The weak plane of bedding, diagenetic fractures, and plane fracture structures of parallel bedding result in the increase of fractures in the direction of vertical bedding, so increasing the potential barrier. Therefore, the resistivity in the vertical bedding direction is higher than that of the parallel bedding. Loading coal resistivity anisotropy degree is a dynamic change trend; the load increases anisotropy significantly under axial pressure, and the degree of anisotropy has a higher discreteness under confining pressure. It is mainly the randomness of the internal pore-fracture compaction, closure, and development of the heterogeneous coal under the confining pressure; the more rapid the decline in this stage, the larger the stress damage degree.
22
Thiessen, Ryan, et Thomas Hillen. « Anisotropic Network Patterns in Kinetic and Diffusive Chemotaxis Models ». Mathematics 9, no 13 (2 juillet 2021) : 1561. http://dx.doi.org/10.3390/math9131561.
Texte intégralRésumé :
For this paper, we are interested in network formation of endothelial cells. Randomly distributed endothelial cells converge together to create a vascular system. To develop a mathematical model, we make assumptions on individual cell movement, leading to a velocity jump model with chemotaxis. We use scaling arguments to derive an anisotropic chemotaxis model on the population level. For this macroscopic model, we develop a new numerical solver and investigate network-type pattern formation. Our model is able to reproduce experiments on network formation by Serini et al. Moreover, to our surprise, we found new spatial criss-cross patterns due to competing cues, one direction given by tissue anisotropy versus a different direction due to chemotaxis. A full analysis of these new patterns is left for future work.
23
Jiménez-Mejía, Raúl E., Rodrigo Acuna Herrera et Pedro Torres. « Analysis of Spatially Doped Fused Silica Fiber Optic by Means of a Hamiltonian Formulation of the Helmholtz Equation ». Advances in Materials Science and Engineering 2018 (2018) : 1–11. http://dx.doi.org/10.1155/2018/5806947.
Texte intégralRésumé :
This paper discusses an alternative method for calculating modal parameters in optical fibers such as propagation constants, transverse distributions, and anisotropy, due to linear and nonlinear phenomena acting as perturbations caused by doped silica regions. This method is based on a Hamiltonian formulation of the Helmholtz equation and the stationary perturbation theory, which allows a full-vectorial description of the electric field components when linear anisotropic inhomogeneities and Kerr nonlinearity are included. Linear and nonlinear parameters can be found for each propagating mode, and its accuracy has been successfully tested when compared to numerical calculations from the vector finite element method, and the results are published in the literature. This method facilitates the calculation of the spatial-distributed perturbation effects on individual electric field components for each propagating mode.
24
Lim, Hyuk, et Jennifer C. Hou. « Distributed localization for anisotropic sensor networks ». ACM Transactions on Sensor Networks 5, no 2 (mars 2009) : 1–26. http://dx.doi.org/10.1145/1498915.1498917.
Texte intégral
25
Ikelle, L. T., S. K. Yung et F. Daube. « 2-D random media with ellipsoidal autocorrelation functions ». GEOPHYSICS 58, no 9 (septembre 1993) : 1359–72. http://dx.doi.org/10.1190/1.1443518.
Texte intégralRésumé :
The integration of surface seismic data with borehole seismic data and well‐log data requires a model of the earth which can explain all these measurements. We have chosen a model that consists of large and small scale inhomogeneities: the large scale inhomogeneities are the mean characteristics of the earth while the small scale inhomogeneities are fluctuations from these mean values. In this paper, we consider a two‐dimensional (2-D) model where the large scale inhomogeneities are represented by a homogeneous medium and small scale inhomogeneities are randomly distributed inside the homogeneous medium. The random distribution is characterized by an ellipsoidal autocorrelation function in the medium properties. The ellipsoidal autocorrelation function allows the parameterization of small scale inhomogeneities by two independent autocorrelation lengths a and b in the horizontal and the vertical Cartesian directions, respectively. Thus we can describe media in which the inhomogeneities are isotropic (a = b), or elongated in a direction parallel to either of the two Cartesian directions (a > b, a < b), or even taken to infinite extent in either dimension (e.g., a = infinity, b = finite: a 1-D medium) by the appropriate choice of the autocorrelation lengths. We also examine the response of seismic waves to this form of inhomogeneity. To do this in an accurate way, we used the finite‐difference technique to simulate seismic waves. Special care is taken to minimize errors due to grid dispersion and grid anisotropy. The source‐receiver configuration consists of receivers distributed along a quarter of a circle centered at the source point, so that the angle between the source‐receiver direction and the vertical Cartesian direction varies from 0 to 90 degrees. Pulse broadening, coda, and anisotropy (transverse isotropy) due to small scale inhomogeneities are clearly apparent in the synthetic seismograms. These properties can be recast as functions of the aspect ratio [Formula: see text] of the medium, especially the anisotropy and coda. For media with zero aspect ratio (1-D media), the coda energy is dominant at large angles. The coda energy gradually becomes uniformly distributed with respect to angle as the aspect ratio increases to unity. Our numerical results also suggest that, for small values of aspect ratio, the anisotropic behavior (i.e., the variations of pulse arrival times with angle) of the 2-D random media is similar to that of a 1-D random medium. The arrival times agree with the effective medium theory. As the aspect ratio increases to unity, the variations of pulse arrival times with angle gradually become isotropic. To retain the anisotropic behavior beyond the geometrical critical angle, we have used a low‐frequency pulse with a nonzero dc component.
26
Shevtsova, Maria, Evgenia Kirillova, Eugeny Rozhkov, Valery Chebanenko, Sergey Shevtsov, Jiing Kae Wu et Shun Hsyung Chang. « Piezoelectric Based Lamb Waves Generation and Propagation in Orthotropic CFRP Plates : II. Influence of Interfacial Stress Distribution ». Materials Science Forum 962 (juillet 2019) : 227–35. http://dx.doi.org/10.4028/www.scientific.net/msf.962.227.
Texte intégralRésumé :
This paper investigates the Lamb wave generation by the surface bonded circular piezoelectric (PZT) actuator and wave propagation within the orthotropic Carbon Fiber Reinforced Plastic (CFRP) plate considering the anisotropy of the elastic and damping properties of the materials; existence of the adhesive layer; and dependence of the interfacial stress distribution on the surface between host plate and actuator, on the anisotropy of the plate material, and on the excited frequency, wavelength and plate thickness. This part of our investigation includes FE based study of the shear stress distribution on the interface between circular PZT actuator and surface of orthotropic CFRP plate, and its dependence on the excited wavelength and plate thickness. The anisotropic elastic and damping properties of the plate material, which are used in the implemented finite element (FE) model, have been preliminary determined in the first part of our investigation. We compare the behavior of the wave generation, propagation and attenuation that are studied using this model with the similar dependencies obtained at the simulation of the non-dissipating plate excited by the periodical radially oriented force, which is distributed along the circumference bounding the actuator, i.e. 3D pin-force excitation case. The proposed results can be used at the design of SHM for the composite structures with the structural anisotropy and damping, and at making a reasonable choice of the frequency, type, dimensions and optimum placement of the actuators and sensors.
27
Zhao, Wei, Fei Shao, Song Ye et and Wei Zheng. « LSRR-LA : An Anisotropy-Tolerant Localization Algorithm Based on Least Square Regularized Regression for Multi-Hop Wireless Sensor Networks ». Sensors 18, no 11 (15 novembre 2018) : 3974. http://dx.doi.org/10.3390/s18113974.
Texte intégralRésumé :
As is well known, multi-hop range-free localization algorithms demonstrate pretty good performance in isotropic networks in which sensor nodes distribute evenly and densely. However, these algorithms are easily affected by network topology, causing a significant decrease in positioning accuracy. To improve the localization performance in anisotropic networks, this paper presents a multi-hop range-free localization algorithm based on Least Square Regularized Regression (LSRR). By building a mapping relationship between hop counts and real distances, we can regard the process of localization as a regularized regression. Firstly, the proximity information of the given network is measured. Then, a mapping model between the geographical distances and the hop distances is constructed by LSRR. Finally, each sensor node finds its own position via this mapping. The Average Localization Error (ALE) metric is used to evaluate the proposed method in our experiments, and results show that, compared with similar methods, our approach can effectively decrease the effect of anisotropy, thus considerably improving the positioning accuracy.
28
Kumar, Sandeep, Y. K. Kim, T. Kang, Min Sup Hur et Moses Chung. « Evolution of magnetic field in a weakly relativistic counterstreaming inhomogeneous e−/e+ plasmas ». Laser and Particle Beams 38, no 3 (24 juillet 2020) : 181–87. http://dx.doi.org/10.1017/s0263034620000233.
Texte intégralRésumé :
AbstractThe nonlinear evolution of electron Weibel instability in a symmetric, counterstream, unmagnetized electron–positron e−/e+ plasmas is studied by a 2D particle-in-cell (PIC) method. The magnetic field is produced and amplified by the Weibel instability, which extracts energy from the plasma anisotropy. A weakly relativistic drift velocity of 0.5c is considered for two counterstreaming e−/e+ plasma flows. Simulations show that in a homogeneous e−/e+ plasma distribution, the magnetic field amplifies exponentially in the linear regime and rapidly decays after saturation. However, in the case of inhomogeneous e−/e+ plasma distribution, the magnetic field re-amplifies at post-saturation. We also find that the amount of magnetic field amplification at post-saturation depends on the strength of the density inhomogeneity of the upstream plasma distribution. The temperature calculation shows that the finite thermal anisotropy exists in the case of an inhomogeneous plasma distribution which leads to the second-stage magnetic field amplification after the first saturation. Such density inhomogeneities are present in a variety of astrophysical sources: for example, in supernova remnants and gamma-ray bursts. Therefore, the present analysis is very useful in understanding these astrophysical sources, where anisotropic density fluctuations are very common in the downstream region of the relativistic shocks and the widely distributed magnetic field.
29
Kosachev, V. S., A. N. Ostrikov et A. А. Yashonkov. « Mathematical modeling of snacks drying process from minced fish in a fluidized bed ». Proceedings of the Voronezh State University of Engineering Technologies 84, no 2 (22 août 2022) : 17–26. http://dx.doi.org/10.20914/2310-1202-2022-2-17-26.
Texte intégralRésumé :
A mathematical model of snacks drying process from minced fish in a fluidized bed with distributed parameters of the heat exchange process between the surface of an anisotropic body and the environment is proposed. The solution of the problem of non-stationary heat transfer by heat conduction using the Galerkin method is considered. The trial and verification functions of the method used, implemented in the PTC MathCAD engineering calculation environment, are linearly independent, represent the first elements of a complete system of polynomial functions and satisfy the boundary and initial conditions. Theoretical and experimental studies have been carried out, which allow considering the process of drying snacks from minced fish in a fluidized bed and scientifically substantiate options for its improvement. According to the results of experimental studies, the adequacy of the obtained mathematical model is shown. It is proved that with a uniform initial temperature distribution during preheating, the temperature inhomogeneity increases up to the moment of a phase transition on the surface of dried object. The importance of taking into account the preheating phase of wet material is established, since at this stage a temperature profile is formed, which is characterized by significant heterogeneity. This is especially important, since temperature heterogeneity directly affects the quality of the food product. The possibility of taking into account anisotropy in heat transfer processes using a three-dimensional mathematical model of transport with distributed parameters is confirmed. The developed technique allows significantly increasing the accuracy of an anisotropic boundary value problem solving by replacing the operation of integrating the stiffness matrix elements with a system of differential equations by algebraic formulas.
30
Markides, Christos F., et Stavros K. Kourkoulis. « Anisotropic discs loaded by parabolically distributed pressure ». Procedia Structural Integrity 2 (2016) : 2659–66. http://dx.doi.org/10.1016/j.prostr.2016.06.332.
Texte intégral
31
Lin, Che-Yu, Bayode E. Owolabi et Chao-An Lin. « Polymer-turbulence interactions in a complex flow and implications for the drag reduction phenomenon ». Physics of Fluids 34, no 4 (avril 2022) : 043106. http://dx.doi.org/10.1063/5.0086686.
Texte intégralRésumé :
We present direct numerical simulation data for turbulent duct flow of a finite-extensibility non-linear elastic dumbbell model with the Peterlin approximation (FENE-P) fluid in the high drag reduction regime. While the secondary flow pattern is qualitatively similar to that in a Newtonian fluid, its magnitude is significantly reduced, resulting in a less uniformly distributed velocity profile and hence smaller gradients at the wall. The Reynolds stress tensor in the polymer-laden flow was found to be increasingly anisotropic with most of the turbulent kinetic energy retained in the streamwise component, [Formula: see text]. We introduce a novel approach for investigating polymer stretching using the anisotropy invariant map of the polymer stress tensor and observe the persistence of both uniaxial and biaxial extension. Analysis of the transport equation for the mean kinetic energy indicates that polymer stretching and relaxation is a highly dissipative process; hence, the introduction of an additional channel for dissipation in a flow is key to drag reduction.
32
Brainerd, Tereasa G., et Masaya Yamamoto. « Satellite galaxies in the Illustris-1 simulation : anisotropic locations around relatively isolated hosts ». Monthly Notices of the Royal Astronomical Society 489, no 1 (12 août 2019) : 459–69. http://dx.doi.org/10.1093/mnras/stz2102.
Texte intégralRésumé :
ABSTRACT We investigate the locations of satellite galaxies in the z = 0 redshift slice of the hydrodynamical Illustris-1 simulation. As expected from previous work, the satellites are distributed anisotropically in the plane of the sky, with a preference for being located near the major axes of their hosts. Due to misalignment of mass and light within the hosts, the degree of anisotropy is considerably less when satellite locations are measured with respect to the hosts’ stellar surface mass density than when they are measured with respect to the hosts’ dark matter surface mass density. When measured with respect to the hosts’ dark matter surface mass density, the mean satellite location depends strongly on host stellar mass and luminosity, with the satellites of the faintest, least massive hosts showing the greatest anisotropy. When measured with respect to the hosts’ stellar surface mass density, the mean satellite location is essentially independent of host stellar mass and luminosity. In addition, the satellite locations are largely insensitive to the amount of stellar mass used to define the hosts’ stellar surface mass density, as long as at least 50–70 per cent of the hosts’ total stellar mass is used. The satellite locations are dependent upon the stellar masses of the satellites, with the most massive satellites having the most anisotropic distributions.
33
Khokhar, Tajammal H., M. F. Bashir et G. Murtaza. « Anomalous skin effects in anisotropic kappa distributed plasmas ». Physics of Plasmas 24, no 7 (juillet 2017) : 072105. http://dx.doi.org/10.1063/1.4989730.
Texte intégral
34
Zhong, Yu, Marc Lambert, Dominique Lesselier et Xudong Chen. « Electromagnetic Response of Anisotropic Laminates to Distributed Sources ». IEEE Transactions on Antennas and Propagation 62, no 1 (janvier 2014) : 247–56. http://dx.doi.org/10.1109/tap.2013.2286835.
Texte intégral
35
Ayaz, S., Imran A. Khan, Z. Iqbal et G. Murtaza. « Alfvén waves in temperature anisotropic Cairns distributed plasma ». Communications in Theoretical Physics 72, no 3 (24 février 2020) : 035502. http://dx.doi.org/10.1088/1572-9494/ab5fb3.
Texte intégral
36
Wu, Chia-Jung, Yi-Yun Chen, Cheng-Jie Wang, Guo-Yi Shiu, Chin-Han Huang, Heng-Jui Liu, Hsiang Chen, Yung-Sen Lin, Chia-Feng Lin et Jung Han. « Anisotropic properties of pipe-GaN distributed Bragg reflectors ». Nanoscale Advances 2, no 4 (2020) : 1726–32. http://dx.doi.org/10.1039/c9na00743a.
Texte intégral
37
Fahmy, Mohamed Abdelsabour. « 3D Boundary Element Model for Ultrasonic Wave Propagation Fractional Order Boundary Value Problems of Functionally Graded Anisotropic Fiber-Reinforced Plates ». Fractal and Fractional 6, no 5 (29 avril 2022) : 247. http://dx.doi.org/10.3390/fractalfract6050247.
Texte intégralRésumé :
This paper proposes a three-dimensional (3D) local boundary element model based on meshless moving least squares (MLS) method for ultrasonic wave propagation fractional order boundary value problems of functionally graded anisotropic (FGA) fiber-reinforced plates. The problem domain is split into several circular sub-domains. The nodal points are randomly distributed across the examined region. Each node is the focal point of a circular sub-domain that encircles it. The Laplace-transform approach is used to solve dynamic issues. In the local weak form of the governing equations for the converted quantities, a unit test function is utilized. The Gauss divergence theorem to the weak-form is used to produce local boundary-domain integral equations. A meshless approximation is achieved using the MLS method. To find time-dependent solutions, an inverse Laplace-transform approach is used. The effects of the fractional order parameter, functionally graded material, anisotropy, and the time characteristic of the laser pulse are investigated. The proposed method's validity and performance are demonstrated for a two-dimensional problem with excellent agreement with the finite element method.
38
Gao, Yuexin, Mengdao Xing, Liang Guo et Zijing Zhang. « Extraction of Anisotropic Characteristics of Scattering Centers and Feature Enhancement in Wide-Angle SAR Imagery Based on the Iterative Re-Weighted Tikhonov Regularization ». Remote Sensing 10, no 12 (19 décembre 2018) : 2066. http://dx.doi.org/10.3390/rs10122066.
Texte intégralRésumé :
The anisotropic characteristic reflects discriminating features of the geometry of a scattering center. In this study, we propose a novel method based on the iterative re-weighted Tikhonov regularization (IRWTR) to achieve the extraction of anisotropic characteristics of scattering centers in the wide-angle SAR synthetic aperture radar (SAR) imaging. Moreover, based on the extracted anisotropic scattering behaviors, the incomplete imaging results of the distributed scattering centers are restored. In this paper, we first discussed the scattering property in SAR imagery from the perspective of attributed scattering center model (ASCM). The reason for the incomplete imaging results of the distributed scattering centers was also discussed based on the ASCM. Subsequently, we modeled the aspect-dependent amplitude responses of a scattering center as a linear combination of a set of orthogonal basis. Consequently, the extraction of anisotropic characteristics can be transformed into an inverse problem, which was solved by the proposed IRWTR with high efficiency and accuracy. After the extraction, we attempted to restore the complete image of a distributed scattering center, which consisted of only two points. The enhanced SAR image can reveal the actual shape of a target. Processing results of electromagnetic computation data validated that the proposed method is effective and efficient.
39
Liu, Shiqi, Huanling Wang, Weiya Xu, Xiao Qu et W. C. Xie. « Numerical Brazilian split test of pre-cracked granite with randomly distributed micro-components ». Engineering Computations 37, no 8 (27 mars 2020) : 2641–57. http://dx.doi.org/10.1108/ec-03-2019-0123.
Texte intégralRésumé :
Purpose The purpose of this paper is to investigate the mechanical behavior and propagation of cracks of numerical granite samples through the Brazilian split test and to provide a reference for predicting the behavior of real granite samples. Design/methodology/approach The numerical models of granite containing two fissures are established using the parallel bond model (PBM) and the smooth joint model (SJM) in PFC2D. The peak stresses, number of cracks and anisotropic ratios are obtained to study the influence of the mineral composition and the angle of inclination of rock bridge on the strength, failure mode and deformation characteristics. Findings The numerical results obtained show that the mineral composition has a marginal influence on the peak stress. When the angle of inclination of rock bridge β increases, the peak stress drops to its minimum value at β = 90° and then gradually increases to a relatively low level. The behavior of cracks falls into three categories based on the distribution of cracks. By analyzing the stress–strain curve and the process of crack propagation for sample No. 4 with β = 60°, it is found that the process of failure can be divided into four stages and tensile cracks dominate. The anisotropic ratios of peak stress and a number of cracks obtained show that the peak stress is low anisotropic and the number of cracks is medium anisotropic. Originality/value This paper presents a numerical simulation method to analyze mechanical behavior and propagation of cracks under different conditions. The proposed method and the results obtained are useful for predicting the behavior of real granite samples in laboratory and engineering projects.
40
Formalev, V. F., S. A. Kolesnik et B. A. Garibyan. « Heat Transfer with Absorption in Anisotropic Thermal Protection of High-Temperature Products ». Herald of the Bauman Moscow State Technical University. Series Natural Sciences, no 5 (86) (octobre 2019) : 35–49. http://dx.doi.org/10.18698/1812-3368-2019-5-35-49.
Texte intégralRésumé :
The purpose of the research was to study the non-stationary heat transfer in anisotropic thermal protection under the action of unsteady heat flows distributed along the body, when there are thermal energy sinks inside the body, the energy being proportional to temperature, due to endothermic physical and chemical transformations. Thermal protection is made of anisotropic material, such as phenol-formaldehyde fiberglass, asboplastics, carbon-carbon plastics, etc. A new analytical solution has been obtained for the problem of plate heating under the action of unsteady heat flows distributed along the body. Using this solution, we studied the temperature fields when the components and orientation angles of the main axes of the thermal conductivity tensors of anisotropic heat-shielding materials were changed. Findings of research show that with increasing time, the temperature field inside the plate is localized and does not extend further than the limiting isotherm.
41
Dou, Rulin, et Weijuan Shi. « Fast and Accurate Hop-based Positioning based on Anchor-skeleton for Anisotropic Networks ». Recent Advances in Electrical & ; Electronic Engineering (Formerly Recent Patents on Electrical & ; Electronic Engineering) 13, no 8 (3 décembre 2020) : 1110–18. http://dx.doi.org/10.2174/2352096513999200407100441.
Texte intégralRésumé :
Background: The hop-based positioning method is a straightforward, low-cost, and feasible positioning method. Methods: Most previous hop-based algorithms assume that the network is isotropic and uniformly distributed, which often does not reflect real-world conditions. In practice, the network may be anisotropic, which makes the hop count between nodes may not match the real distance well. Results: As a result of this issue for hop-based positioning methods, in this paper, we propose a novel scheme that builds a skeleton model between anchor nodes to represent the anisotropy of a network. During the process of building the skeleton model, we use the corrected Akaike's Information Criterion (AICc), which can assist in the construction of a reliable and high accuracy skeleton model. With the help of the skeleton model with AICc, an unknown node can get a more accurate and reliable estimated position. Conclusion: The results of both theoretical analysis and experimental simulation show that the optimal hop-distance conversion model can be achieved, and compared to other similar algorithms, the proposed algorithm can obtain the position estimation result in a fast and accurate manner.
42
Liu, Guang, Liwen Zhang, Yang Gan, Yan Wang, Dengke Chen, Yuguo Dai, Lin Feng, Pengfei Zhang et Huawei Chen. « Liquid transport with direction guidance and speed enhancement from gradient and magnetized micro-cilia surface ». Applied Physics Letters 120, no 19 (9 mai 2022) : 191603. http://dx.doi.org/10.1063/5.0089149.
Texte intégralRésumé :
Liquid transport regulation has attracted wide attention recently due to its potential applications in micro-fluidic devices, heat management, and mechanical engineering. Various liquid regulation strategies for direction guiding and speed enhancing have been developed with inspirations from nature, such as desert beetles and Nepenthes alata peristome with either gradient wettability or anisotropic structures, whereas their combined strategies for enhanced liquid regulations have barely been discussed due to the unclear coupling mechanisms. Herein, inspired by liquid transporting structure on Ligia exotica's leg, a smart flexible surface with gradient distributed and magnetized micro-cilia array is proposed to realize liquid spreading regulations in speed and direction. Different gradients and magnetic fields have been compared for liquid regulating performances, where the anisotropy ratio of liquid spreading could be enhanced from 0 on uniform surface to ∼0.3 on gradients surface, to even ∼0.6 by coupling magnetic field. The underlying liquid regulating mechanism has been established based on the mutual effects of liquid pinning and capillarity at different cilium inclined angles, cilium gap distance, and surface wettability. Finally, several liquid regulation applications are explored and offer potentials for fields of medicine and heat management.
43
Kim, Meeri. « Combining gradient and inclined cilia for enhanced directional liquid transport ». Scilight 2022, no 19 (13 mai 2022) : 191104. http://dx.doi.org/10.1063/10.0011407.
Texte intégral
44
Panagou, Dimitra, Dusan M. Stipanovic et Petros G. Voulgaris. « Distributed Dynamic Coverage and Avoidance Control Under Anisotropic Sensing ». IEEE Transactions on Control of Network Systems 4, no 4 (décembre 2017) : 850–62. http://dx.doi.org/10.1109/tcns.2016.2576403.
Texte intégral
45
Van Cauwelaert, F., et B. Eckmann. « The anisotropic beam submitted to a uniformly distributed load ». Materials and Structures 27, no 3 (avril 1994) : 148–52. http://dx.doi.org/10.1007/bf02473028.
Texte intégral
46
Nagayama, Tsutomu, et Atsushi Sanada. « Planar Distributed Full-Tensor Anisotropic Metamaterials for Transformation Electromagnetics ». IEEE Transactions on Microwave Theory and Techniques 63, no 12 (décembre 2015) : 3851–61. http://dx.doi.org/10.1109/tmtt.2015.2487275.
Texte intégral
47
Miller, S. E., H. Abramovich et Y. Oshman. « Active distributed vibration control of anisotropic piezoelectric laminated plates ». Journal of Sound and Vibration 183, no 5 (juin 1995) : 797–817. http://dx.doi.org/10.1006/jsvi.1995.0287.
Texte intégral
48
Bezrodna, I., V. Svystov et D. Bezrodny. « ANALYSIS OF ACOUSTIC ANISOTROPY PARAMETERS OF PYROXENE-MAGNETITE ROCKS OF THE PISCHANKA STRUCTURE ». Visnyk of Taras Shevchenko National University of Kyiv. Geology, no 1 (88) (2020) : 40–45. http://dx.doi.org/10.17721/1728-2713.88.06.
Texte intégralRésumé :
The analysis of the results of acoustic properties of rocks study of Pischans`ka iron-ore structure is presented. The aim of the work is to establish the features of the distribution of acoustic properties and parameters of acoustic anisotropy in samples of core rocks selected from the well No. 3 of the Pischans`ka structure to determine the nature of its occurrence. A sample of 35 samples from the depth range 144-273 m is divided into 3 groups of rocks, namely: magnetite-pyroxene, quartz-magnetitepyroxene and biotite-amphibole crystalline shales. Based on an invariant polarization method, a number of acoustic laboratory measurements have been carried out. The values of the measured phase velocities "quasi-longitudinal" and two "quasi-transverse" waves at the stage of measurements showed significant acoustic anisotropy of the rocks. The ranges of the measured speeds of the collection samples are 7661 ÷ 5046 m / s for longitudinal waves and 4232 ÷ 2648 m/s for transverse ones. The difference in values measured for each of the sides of the cubic rhombic dodecahedron is from 100 to 800 m / s and from 0 to 500 m/s for Vp and Vs, respectively. The parameters of an acoustic ellipsoid were calculated, on the basis of which the division of samples into 3 main groups has been performed, according to the acoustic texture: acoustically linear, shale and rhombic. Separately, a group of samples with a more complex texture was discovered. The analysis of coefficients of anisotropy by different methods is carried out: longitudinal, transverse and relative acoustic anisotropy. Most of the samples are characterized by low or average acoustic anisotropy (from 2 to 7 %). A group of highly anisotropic rocks (11–14 %), represented by samples of biotite-amphibole crystalline silicates, is singled out. According to the parameters of the acoustic tensor of most samples, the transverse isotropic type of symmetry inherent to samples from the depth intervals 174–220 m and 222–232 m, while the smaller part is rhombic, is inherent. Differences in the parameters of anisotropy of samples can be explained by the significant heterogeneity of their textures, namely: micro cracks, minerals of various sizes, shapes and orientations. The results of the research show that the acoustic properties of the samples are quite heterogeneously distributed along the investigated depth range. This indicates the difficult conditions for the formation of rocks at different depths and the presence of different types of deformations, which accompanied the formation of the Pischans`ka structure.
49
HAYTON, JAMES A., EMMANUELLE PAULIAC-VAUJOUR et PHILIP J. MORIARTY. « ANISOTROPIC ASSEMBLY OF COLLOIDAL NANOPARTICLES : EXPLOITING SUBSTRATE CRYSTALLINITY ». Nano 02, no 06 (décembre 2007) : 361–65. http://dx.doi.org/10.1142/s1793292007000714.
Texte intégralRésumé :
We show that the crystal structure of a substrate can be exploited to drive the anisotropic assembly of colloidal nanoparticles. Pentanethiol-passivated Au particles of ~ 2 nm diameter deposited from toluene onto hydrogen-passivated Si (111) surfaces form linear assemblies (rods) with a narrow width distribution. The rod orientations mirror the substrate symmetry, with a high degree of alignment along principal crystallographic axes of the Si (111) surface. There is a strong preference for anisotropic growth with rod widths substantially more tightly distributed than lengths. Entropic trapping of nanoparticles provides a plausible explanation for the formation of the anisotropic assemblies we observe.
50
Nagaya, Takayoshi, Atsushi Okamoto, Ryosuke Oyanagi, Yusuke Seto, Akira Miyake, Masaoki Uno, Jun Muto et Simon R. Wallis. « Crystallographic preferred orientation of talc determined by an improved EBSD procedure for sheet silicates : Implications for anisotropy at the slab–mantle interface due to Si-metasomatism ». American Mineralogist 105, no 6 (1 juin 2020) : 873–93. http://dx.doi.org/10.2138/am-2020-7006.
Texte intégralRésumé :
Abstract Talc is widely distributed over the Earth's surface and is predicted to be formed in various tectonic settings. Talc is a very soft and anisotropic sheet silicate showing very low friction behavior. Therefore, the formation of talc is expected to weaken the strength of talc-bearing rocks and may be associated with the initiation of subduction, and with a decrease in the coupling coefficient resulting in aseismic movements along faults and shear zones within subduction zones. For these reasons, understanding the crystallographic preferred orientation (CPO) of talc is important to quantify the anisotropy and physical properties of the host rock. However, it is difficult to measure a significant number of talc crystal orientations and to evaluate the accuracy of the measurements using electron-backscattered diffraction (EBSD). Therefore, talc CPO has not been reported, and there is uncertainty regarding the estimation of the strength of deformed talc-bearing rocks. Using methods developed for antigorite, we report the first successful EBSD measurements of talc CPO from a talc schist formed due to Simetasomatism of ultramafic rocks by subduction zone fluids. We used a combination of W-SEM and FE-SEM measurements to examine domains of various grain sizes of talc. In addition, we used TEM measurements to evaluate the accuracy of the EBSD measurements and discuss the results of talc CPO analysis. Talc CPO in the present study shows a strong concentration of the pole to the (001) plane normal to the foliation. The strongest concentration of the [100] direction is parallel to the lineation. The talc schist produces similar S-wave splitting and P- and S-wave anisotropy as antigorite schist in deeper domains, thus identifying talc-rich layers in subduction zones may require a combination of geophysical surveys, seismic observations, and anisotropy modeling. The presence of strong talc CPO in rocks comprising the slab–mantle interface boundary may promote spatial expansion of the slip area during earthquakes along the base of the mantle wedge.