Journal articles on the topic 'Tilted Additive Model'
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Boroumand, Farzaneh, Mohammad Taghi Shakeri, Touka Banaee, Hamidreza Pourreza, and Hassan Doosti. "An Analysis of the Areas Occupied by Vessels in the Ocular Surface of Diabetic Patients: An Application of a Nonparametric Tilted Additive Model." International Journal of Environmental Research and Public Health 18, no. 7 (April 2, 2021): 3735. http://dx.doi.org/10.3390/ijerph18073735.
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(1) Background: As diabetes melllitus (DM) can affect the microvasculature, this study evaluates different clinical parameters and the vascular density of ocular surface microvasculature in diabetic patients. (2) Methods: In this cross-sectional study, red-free conjunctival photographs of diabetic individuals aged 30–60 were taken under defined conditions and analyzed using a Radon transform-based algorithm for vascular segmentation. The Areas Occupied by Vessels (AOV) images of different diameters were calculated. To establish the sum of AOV of different sized vessels. We adopt a novel approach to investigate the association between clinical characteristics as the predictors and AOV as the outcome, that is Tilted Additive Model (TAM). We use a tilted nonparametric regression estimator to estimate the nonlinear effect of predictors on the outcome in the additive setting for the first time. (3) Results: The results show Age (p-value = 0.019) and Mean Arterial Pressure (MAP) have a significant linear effect on AOV (p-value = 0.034). We also find a nonlinear association between Body Mass Index (BMI), daily Urinary Protein Excretion (UPE), Hemoglobin A1C, and Blood Urea Nitrogen (BUN) with AOV. (4) Conclusions: As many predictors do not have a linear relationship with the outcome, we conclude that the TAM will help better elucidate the effect of the different predictors. The highest level of AOV can be seen at Hemoglobin A1C of 9% and AOV increases when the daily UPE exceeds 600 mg. These effects need to be considered in future studies of ocular surface vessels of diabetic patients.
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Chen, Huaizhen, Tiansheng Chen, and Kristopher A. Innanen. "Estimating tilted fracture weaknesses from azimuthal differences in seismic amplitude data." GEOPHYSICS 85, no. 3 (May 1, 2020): R135—R146. http://dx.doi.org/10.1190/geo2019-0344.1.
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Tilted transverse isotropy (TTI) provides a useful model for the elastic response of a medium containing aligned fractures with a symmetry axis oriented obliquely in the vertical and horizontal coordinate directions. Robust methods for determining the TTI properties of a medium from seismic observations to characterize fractures are sought. Azimuthal differencing of seismic amplitude data produces quantities that are particularly sensitive to TTI properties. Based on the linear slip fracture model, we express the TTI stiffness matrix in terms of the normal and tangential fracture weaknesses. Perturbing stiffness parameters to simulate an interface separating an isotropic medium and a TTI medium, we derive a linearized P-to-P reflection coefficient expression in which the influence of tilt angle and fracture weaknesses separately emerge. We formulate a Bayesian inversion approach in which amplitude differences between seismic data along two azimuths, interpreted in terms of the reflection coefficient approximation, are used to determine fracture weaknesses and tilt angle. Tests with simulated data confirm that the unknown parameter vector involving fracture weakness and tilted fracture weaknesses is stably estimated from seismic data containing a moderate degree of additive Gaussian noise. The inversion approach is applied to a field surface seismic data acquired over a fractured reservoir; from it, interpretable tilted fracture weaknesses, consistent with expected reservoir geology, are obtained. We determine that our inversion approach and the established inversion workflow can produce the properties of systems of tilted fractures stably using azimuthal seismic amplitude differences, which may add important information for characterization of fractured reservoirs.
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Gong, J., D. L. Wu, and V. Limpasuvan. "Meridionally-tilted ice cloud structures in the tropical Upper Troposphere as seen by CloudSat." Atmospheric Chemistry and Physics Discussions 14, no. 17 (September 26, 2014): 24915–42. http://dx.doi.org/10.5194/acpd-14-24915-2014.
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Abstract. It remains challenging to quantify global cloud properties and uncertainties associated with their impacts on climate change because of our poor understanding of cloud three-dimensional (3-D) structures from observations and unrealistic/unconsidered characterization of 3-D cloud effects in Global Climate Models (GCMs). In this study we find cloud 3-D effects can cause significant error in cloud ice and radiation measurements if it is not taken into account appropriately. One of the cloud 3-D complexities, the slantwise tilt structure, has not received much attention in research and even little report is given on its global perspective. A novel approach is presented here to analyze the ice cloud water content (IWC) profiles retrieved from CloudSat and a joint radar-lidar product (DARDAR). By integrating IWC along different tilt angles, we find that Upper-Troposphere (UT) ice cloud mass between 11 and 17 km is tilted poleward from active convection centers in the tropics. This systematic tilt in cloud mass structure is expected from the mass conservation principle of the Hadley circulation with the divergent flow of each individual convection/convective system from down below, and its existence is further confirmed from cloud-resolving scale Weather Research and Forecasting (WRF) model simulations. Thus, additive effects of tilted cloud structures can induce 5–20% variability by nature or an error in satellite cloud/hydrometeor ice retrievals if simply converting it from slant to nadir column. A surprising finding is the equatorward tilt in middle tropospheric (5–11 km) ice clouds, which is also evident in high-resolution model simulations but not in coarse-resolution simulations with cumulus parameterization. The observed cloud tilt structures are intrinsic properties of tropical clouds, producing synoptic distributions around the ITCZ. These findings imply that current interpretations based on over-simplified cloud vertical structures could lead to substantial cloud measurement errors and induce subsequent impact on understanding cloud radiative, dynamical and hydrological properties.
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Gong, J., D. L. Wu, and V. Limpasuvan. "Meridionally tilted ice cloud structures in the tropical upper troposphere as seen by CloudSat." Atmospheric Chemistry and Physics 15, no. 11 (June 9, 2015): 6271–81. http://dx.doi.org/10.5194/acp-15-6271-2015.
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Abstract. It remains challenging to quantify global cloud properties and uncertainties associated with their impacts on climate change because of our poor understanding of cloud three-dimensional (3-D) structures from observations and unrealistic characterization of 3-D cloud effects in global climate models (GCMs). In this study we find cloud 3-D effects can cause significant error in cloud ice and radiation measurements if it is not taken into account appropriately. One of the cloud 3-D complexities, the slantwise tilt structure, has not received much attention in research and even less has been reported considering a global perspective. A novel approach is presented here to analyze the ice cloud water content (IWC) profiles retrieved from CloudSat and a joint radar–lidar product (DARDAR). By integrating IWC profiles along different tilt angles, we find that upper-troposphere (UT) ice cloud mass between 11 and 17 km is tilted poleward from active convection centers in the tropics [30° S, 30° N]. This systematic tilt in cloud mass structure is expected from the mass conservation principle of the Hadley circulation with the divergent flow of each individual convection/convective system from down below, and its existence is further confirmed from cloud-resolving-scale Weather Research and Forecasting (WRF) model simulations. Thus, additive effects of tilted cloud structures can introduce 5–20% variability by its nature or produce errors to satellite cloud/hydrometeor ice retrievals if simply converting it from slant to nadir column. A surprising finding is the equatorward tilt in middle tropospheric (5–11 km) ice clouds, which is also evident in high-resolution model simulations but not in coarse-resolution simulations with cumulus parameterization. The observed cloud tilt structures are intrinsic properties of tropical clouds, producing synoptic distributions around the Intertropical Convergence Zone (ITCZ). These findings imply that current interpretations based on over-simplified cloud vertical structures could lead to considerable cloud measurement errors and have a subsequent impact on understanding cloud radiative, dynamical and hydrological properties.
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WARDHANI, PRIMASARI, PEI-I. TSAI, PEI-YU CHEN, YU-YOU CHEN, and CHING-CHI HSU. "A COMPUTATIONAL STUDY OF DIFFERENT ADDITIVE MANUFACTURING-BASED TOTAL ANKLE REPLACEMENT DEVICES USING THREE-DIMENSIONAL HUMAN LOWER EXTREMITY MODELS WITH VARIOUS ANKLE POSTURES." Journal of Mechanics in Medicine and Biology 19, no. 02 (March 2019): 1940014. http://dx.doi.org/10.1142/s0219519419400141.
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Total ankle replacement (TAR) surgery is one of the useful methods to treat ankle arthritis. Selective laser melting that is an additive manufacturing (AM) technique has made it possible to fabricate orthopedic implants. However, there are rare studies to analyze AM implants using finite element method. Thus, the purpose of this study was to investigate the effect of the various porous designs with three types of tibial shapes for five ankle postures using three-dimensional (3D) human lower extremity models. The variable-axis-mobile-bearing (VAMB) TAR models were developed in one solid TAR design and three porous TAR designs on the tibial and talar components. Additionally, three shape designs (curved, flat, and tilted) of the tibial component were also evaluated. Each TAR design was assembled on the human lower extremity model with standing, inversion, eversion, plantar flexion, and dorsiflexion ankle postures. The results showed that there was a minor effect among the solid and porous TAR designs on the implant stability, the bone stress, and the implant stress. However, those performances in the plantar flexion were significantly reduced compared to that in the other ankle postures. Although the porous TAR designs have a higher risk of implant failure and bone breakage, it may have better bone-implant bonding ability. This study could help engineers and surgeons to understand the design rationale and biomechanics of AM-based TAR devices.
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Li, Rong, and Jun Xiong. "A numerical prediction of residual stress for a thin-walled part with geometrical features fabricated by GMA-based additive manufacturing." Rapid Prototyping Journal 26, no. 2 (September 19, 2019): 299–308. http://dx.doi.org/10.1108/rpj-08-2018-0193.
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Purpose An accurate prediction of process-induced residual stress is necessary to prevent large distortion and cracks in gas metal arc (GMA)-based additive manufactured parts, especially thin-walled parts. The purpose of this study is to present an investigation into predicting the residual stress distributions of a thin-walled component with geometrical features. Design/methodology/approach A coupled thermo-mechanical finite element model considering a general Goldak double ellipsoidal heat source is built for a thin-walled component with geometrical features. To confirm the accuracy of the model, corresponding experiments are performed using a positional deposition method in which the torch is tilted from the normal direction of the substrate. During the experiment, the thermal cycle curves of locations on the substrate are obtained by thermocouples. The residual stresses on the substrate and part are measured using X-ray diffraction. The validated model is used to investigate the thermal stress evolution and residual stress distributions of the substrate and part. Findings Decent agreements are achieved after comparing the experimental and simulated results. It is shown that the geometrical feature of the part gives rise to an asymmetrical transversal residual stress distribution on the substrate surface, while it has a minimal influence on the longitudinal residual stress distribution. The residual stress distributions of the part are spatially uneven. The longitudinal tensile residual stress is the prominent residual stress in the central area of the component. Large wall-growth tensile residual stresses, which may cause delamination, appear at both ends of the component and the substrate–component interfaces. Originality/value The predicted residual stress distributions of the thin-walled part with geometrical features are helpful to understand the influence of geometry on the thermo-mechanical behavior in GMA-based additive manufacturing.
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Wang, Yuan, Jianrun Zhang, Lan Chen, Naifei Ren, Lei Li, Bo Wu, and Xinzhou Zhang. "The effect of structural-acoustic coupling on the sound field in a trapezoidal enclosure." Noise Control Engineering Journal 67, no. 3 (May 1, 2019): 180–89. http://dx.doi.org/10.3397/1/376716.
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The sound field characteristics in a trapezoidal enclosure surrounded by a flexible wall, which is adjacent to the tilted one, are investigated and compared with the case of a rectangular enclosure. The acoustic modes of trapezoidal enclosure are obtained by the coupling of the modes of rectangular enclosure that bounds it. The coupling system model is then built between trapezoidal enclosure modes and flexible wall modes using modal coupling theory. Based on the coupled system model, the effect of flexible wall modal density on the resonance frequencies and the decay times of coupled system are analyzed. Compared with the case of rectangular enclosure, the variation of the resonance frequency and the decay time of enclosure-controlled system mode is determined by its mode indices and tilted wall location when the panel modal density is changed. When the modal indices of trapezoidal sound field in the two directions unparallel to the tilted wall are equal to zero simultaneously, the effect of inclination angle on the resonance frequencies and decay times of these coupled system modes can be neglected. Otherwise, the coupling system modes behaviors are changed with the elevation angle. In addition, the coupling selection between the modes of trapezoidal enclosure and flexible wall is discussed in detail.
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Wu, Fei, Junchan Wang, Yuzhuang Zhou, Xiaoxin Song, Chengxin Ju, Chengming Sun, and Tao Liu. "Estimation of Winter Wheat Tiller Number Based on Optimization of Gradient Vegetation Characteristics." Remote Sensing 14, no. 6 (March 10, 2022): 1338. http://dx.doi.org/10.3390/rs14061338.
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Tiller are an important biological characteristic of wheat, a primary food crop. Accurate estimation of tiller number can help monitor wheat growth and is important in forecasting wheat yield. However, because of leaf cover and other factors, it is difficult to estimate tiller number and the accuracy of estimates based on vegetation indices is low. In this study, a gradual change feature was introduced to optimize traditional prediction models of wheat tiller number. Accuracy improved in optimized models, and model R2 values for three varieties of winter wheat were 0.7044, 0.7060, and 0.7357. The optimized models improved predictions of tiller number in whole wheat fields. Thus, compared with the traditional linear model, the addition of a gradual change feature greatly improved the accuracy of model predictions of wheat tiller number.
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Nozari, K., and S. Shafizadeh. "Realization of blue spectrum in generalized Galileon super-inflation models." International Journal of Modern Physics D 26, no. 03 (February 3, 2017): 1750016. http://dx.doi.org/10.1142/s021827181750016x.
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In the spirit of Galileon inflation and by considering some sorts of noncanonical kinetic terms in the action, we realize a stage of super-inflation leading to a blue-tilted tensor perturbation. We show also that addition of Galileon-like term to the action leads to avoidance of ghost instabilities in this setup.
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Ivanov, Yuriy, and Alexey Stovas. "S-wave singularities in tilted orthorhombic media." GEOPHYSICS 82, no. 4 (July 1, 2017): WA11—WA21. http://dx.doi.org/10.1190/geo2016-0642.1.
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Quasi S-wave propagation in low-symmetry anisotropic media is complicated due to the existence of point singularities (conical points) — points in the phase space at which slowness sheets of the split S-waves touch each other. At these points, two eigenvalues of the Christoffel tensor (associated with the quasi S-waves) degenerate into one and polarization directions of the S-waves, which lay in the plane orthogonal to the polarization of the quasi longitudinal wave, are not uniquely defined. In the vicinity of these points, slowness sheets of the S-waves have complicated shapes, leading to rapid variations in polarization directions, multipathing, and cusps and discontinuities of the shear wavefronts. In a tilted orthorhombic medium, the point singularities can occur close to the vertical, distorting the traveltime parameters that are defined at the zero offset. We have analyzed the influence of the singularities on these parameters by examining the derivatives of the slowness surface up to the fourth order. Using two orthorhombic numerical models of different shear anisotropy strength and with different number of singularity points, we evaluate the complexity of the slowness sheets in the vicinity of the conical points and analyze how the traveltime parameters are affected by the singularities. In particular, we observe that the hyperbolic region associated with the singularity points in a model with moderate to strong shear anisotropy spans over a big portion of the slowness surfaces and the traveltime parameters are strongly affected outside the hyperbolic region. In general, the fast shear mode is less affected by the singularities; however, the effect is still very pronounced. Moreover, the hyperbolic region associated with the singularity points on the slow S-wave affects the slowness surface of the fast mode extensively. In addition, we evaluate a relation between the slowness surface Gaussian curvature and the relative geometric spreading, which has anomalous behavior due to the singularities.
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Jeffery, Nicole, and Beth Wingate. "The Effect of Tilted Rotation on Shear Instabilities at Low Stratifications." Journal of Physical Oceanography 39, no. 12 (December 1, 2009): 3147–61. http://dx.doi.org/10.1175/2009jpo4138.1.
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Abstract A linear stability analysis of the inviscid stratified Boussinesq equations is presented given a steady zonal flow with constant vertical shear in a tilted f plane. Full nonhydrostatic terms are included: 1) acceleration of vertical velocity and 2) Coriolis force terms arising from the meridional component of earth’s rotation vector. Calculations of growth rates, critical wavenumbers, and dominance regimes for baroclinic and symmetric instabilities are compared with results from the traditional nonhydrostatic equations, which include a strictly vertical rotation vector, as well as results from the hydrostatic equations. The authors find that for positive zonal z shear, tilted rotation enhances the dominance regime of symmetric instabilities at the expense of baroclinic instabilities and maintains symmetric instabilities at larger scales than previously indicated. Furthermore, in contrast to former studies, it is determined that hydrostatic growth rates for both instabilities are not maximal. Rather, growth rates peak in the fully nonhydrostatic equations for parameter regimes physically relevant and consistent with abyssal ocean stratifications and weak zonal z shears and oceanic measurements of the Labrador Sea and Southern Ocean. In addition, the authors find that zonal shear modifies the frequency range of subinertial inertio–gravity waves. Tilted rotation effects break the base flow shear reflection symmetry present in the traditional and hydrostatic models. Thus, only in the fully nonhydrostatic model does weak negative zonal z shear stabilize the flow and decrease the subinertial frequency range.
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SETO, OSAMU, and JUN'ICHI YOKOYAMA. "PERTURBATIONS FROM D-TERM INFLATION." Modern Physics Letters A 22, no. 25n28 (September 14, 2007): 2035–38. http://dx.doi.org/10.1142/s0217732307025273.
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We investigated a simple D-term inflation with taking account of higher order corrections in the Kähler potential. These terms may solve the cosmic string problem in D-term inflation model. The mass per unit length of cosmic strings formed after inflation can be suppressed enough. In addition, the change of the potential slope leads simultaneously a more tilted scalar spectral index ns ≃ 0.96 – 0.97 than that in the model without these corrections.
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Hetherington, C. J. D. "High-Resolution Image Simulation of a Tilted Crystal." Proceedings, annual meeting, Electron Microscopy Society of America 48, no. 1 (August 12, 1990): 68–69. http://dx.doi.org/10.1017/s0424820100179099.
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Most high resolution images are not directly interpretable but must be compared with simulations based on model atomic structures and appropriate imaging conditions. Typically, the only parameters that are adjusted, in addition to the structure models, are crystal thickness and microscope defocus. Small tilts of the crystal away from the exact zone axis have only rarely been considered. It is shown here that, in the analysis of an image of a silicon twin intersection, the crystal tilt could be accurately estimated and satisfactorily included in the simulations.The micrograph shown in figure 1 was taken as part of an HREM study of indentation-induced hexagonal silicon. In this instance, the intersection of two twins on different habit planes has driven the silicon into hexagonal stacking. However, in order to confirm this observation, and in order to investigate other defects in the region, it has been necessary to simulate the image taking into account the very apparent crystal tilt. The inability to orientate the specimen at the exact [110] zone was influenced by i) the buckling of the specimen caused by strains at twin intersections, ii) the absence of Kikuchi lines or a clearly visible Laue circle in the diffraction pattern of the thin specimen and iii) the avoidance of radiation damage (which had marked effects on images taken a few minutes later following attempts to realign the crystal.) The direction of the crystal tilt was estimated by observing which of the {111} planes remained close to edge-on to the beam and hence strongly imaged. Further refinement of the direction and magnitude of the tilt was done by comparing simulated images to experimental images in a through-focal series. The presence of three different orientations of the silicon lattice aided the unambiguous determination of the tilt. The final estimate of a 0.8° tilt in the 200Å thick specimen gives atomic columns a projected width of about 3Å.
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Forthmann, Boris, and Denis Dumas. "Quantity and Quality in Scientific Productivity: The Tilted Funnel Goes Bayesian." Journal of Intelligence 10, no. 4 (November 1, 2022): 95. http://dx.doi.org/10.3390/jintelligence10040095.
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The equal odds baseline model of creative scientific productivity proposes that the number of high-quality works depends linearly on the number of total works. In addition, the equal odds baseline implies that the percentage of high-quality works and total number of works are uncorrelated. The tilted funnel hypothesis proposes that the linear regression implied by the equal odds baseline is heteroscedastic with residual variance in the quality of work increasing as a function of quantity. The aim of the current research is to leverage Bayesian statistical modeling of the equal odds baseline. Previous work has examined the tilted funnel by means of frequentist quantile regression, but Bayesian quantile regression based on the asymmetric Laplace model allows for only one conditional quantile at a time. Hence, we propose additional Bayesian methods, including Poisson modeling to study conditional variance as a function of quantity. We use a classical small sample of eminent neurosurgeons, as well as the brms Bayesian R package, to accomplish this work. In addition, we provide open code and data to allow interested researchers to extend our work and utilize the proposed modeling alternatives.
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Wang, Ganlin, and Jing Chen. "A Vector Data Model for Efficiently Rendering Large Vector Maps on Global 3D Terrain Surfaces." ISPRS International Journal of Geo-Information 11, no. 4 (April 4, 2022): 234. http://dx.doi.org/10.3390/ijgi11040234.
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Visualizing vector data on 3D terrain surfaces is a basic and essential function in 3D GIS. However, due to the complexity of vector data structures, efficient and effective organization of the vector data is a key issue for the efficient display of vector data in 3D. In this paper, we present a new Vector Tiled Pyramid Model to organize and manage vector data so that they can be visualized on 3D terrain surfaces more effectively. In the Vector Tiled Pyramid Model, vector data at different scales within the same geographical extent are stored as separate levels. Each vector level in our proposed model is divided into vector tiles of fixed sizes organized in a grid index. This improves the efficiency of visualizing vector data on 3D terrain surfaces. Preliminary experimental results suggest that the proposed Vector tiled Pyramid Model, compared with the traditional vector database scheme, can help us to visualize vector data on 3D terrain surfaces more efficiently. In addition, this advantage is more evident when a vector tile at a lower level (large-scale) is requested and visualized on 3D terrain surfaces.
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Khatri, Hemant, and Pavel Berloff. "Tilted drifting jets over a zonally sloped topography: effects of vanishing eddy viscosity." Journal of Fluid Mechanics 876 (August 9, 2019): 939–61. http://dx.doi.org/10.1017/jfm.2019.579.
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Oceanic multiple jets are seen to possess spatio-temporal variability imposed by varying bottom topography resulting in jets that can drift and merge. The dynamics of multiple jets over a topographic zonal slope is studied in a two-layer quasi-geostrophic model. The jets tilt from the zonal direction and drift meridionally. In addition to the tilted jets, other large-scale spatial patterns are observed, which are extracted using the principal component analysis. The variances of these patterns are strongly influenced by the values of eddy viscosity and bottom friction parameters. The contribution of the tilted jets to the full flow field decreases with decreasing friction and viscosity parameters, and purely zonal large-scale modes, propagating in the meridional direction, populate the flow field. Linear stability analysis and two-dimensional kinetic-energy spectrum analysis suggest that the zonal modes gain energy from ambient eddies as well as from the tilted jets through nonlinear interactions. However, viscous dissipation and bottom friction tend to suppress the nonlinear interactions, which results in the inhibition of the upscale energy transfer from eddies to the zonal modes. These simulations suggest that, in the presence of topography, alternating jet patterns may be sustained through interactions among various large-scale modes. This is different from the classical zonal jet formation arguments, in which direct eddy forcing maintains the jets.
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Jansen, D., M. G. Llorens, J. Westhoff, F. Steinbach, S. Kipfstuhl, P. D. Bons, A. Griera, and I. Weikusat. "Small-scale disturbances in the stratigraphy of the NEEM ice core: observations and numerical model simulations." Cryosphere 10, no. 1 (February 12, 2016): 359–70. http://dx.doi.org/10.5194/tc-10-359-2016.
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Abstract. Disturbances on the centimetre scale in the stratigraphy of the North Greenland Eemian Ice Drilling (NEEM) ice core (North Greenland) can be mapped by an optical line scanner as long as the ice has visual layering, such as, for example, cloudy bands. Different focal depths allow, to a certain extent, a three-dimensional view of the structures. In this study we present a detailed analysis of the visible folds, discuss their characteristics and frequency, and present examples of typical fold structures. We also analyse the structures with regard to the deformation boundary conditions under which they formed. The structures evolve from gentle waves at about 1500 m to overturned z folds with increasing depth. Occasionally, the folding causes significant thickening of layers. Their similar fold shape indicates that they are passive features and are probably not initiated by rheology differences between alternating layers. Layering is heavily disturbed and tracing of single layers is no longer possible below a depth of 2160 m. C axes orientation distributions for the corresponding core sections were analysed, where available, in addition to visual stratigraphy. The data show axial-plane parallel strings of grains with c axis orientations that deviate from that of the matrix, which shows a single maximum fabric at the depth where the folding occurs. Numerical modelling of crystal viscoplastic deformation and dynamic recrystallisation was used to improve the understanding of the formation of the observed structures during deformation. The modelling reproduces the development of bands of grains with a tilted-lattice orientation relative to the single maximum fabric of the matrix, and also the associated local deformation. We conclude from these results that the observed folding can be explained by formation of these tilted-lattice bands.
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Neverov, Vladimir, and Vladimir Shelukhin. "Recursive Settling of Particles in Shear Thinning Polymer Solutions: Two Velocity Mathematical Model." Polymers 14, no. 19 (October 10, 2022): 4241. http://dx.doi.org/10.3390/polym14194241.
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Processing of the available experimental data on particles settling in shear-thinning polymer solutions is performed. Conclusions imply that sedimentation should be recursive, since settling also occurs within the sediment. To capture such an effect, a mathematical model of two continua has been developed, which corresponds to experimental data. The model is consistent with basic thermodynamics laws. The rheological component of this model is a correlation formula for gravitational mobility. This closure is justified by comparison with known experimental data available for particles settling in vertical vessels. In addition, the closure is validated by comparison with analytical solutions to the Kynch one-dimensional equation, which governs dynamics of particle concentration. An explanation is given for the Boycott effect and it is proven that sedimentation is enhanced in a 2D inclined vessel. In tilted vessels, the flow is essentially two-dimensional and the one-dimensional Kynch theory is not applicable; vortices play an important role in sedimentation.
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Straub, Katherine H., Patrick T. Haertel, and George N. Kiladis. "An Analysis of Convectively Coupled Kelvin Waves in 20 WCRP CMIP3 Global Coupled Climate Models." Journal of Climate 23, no. 11 (June 1, 2010): 3031–56. http://dx.doi.org/10.1175/2009jcli3422.1.
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Abstract Output from 20 coupled global climate models is analyzed to determine whether convectively coupled Kelvin waves exist in the models, and, if so, how their horizontal and vertical structures compare to observations. Model data are obtained from the World Climate Research Program’s (WCRP’s) Coupled Model Intercomparison Project phase 3 (CMIP3) multimodel dataset. Ten of the 20 models contain spectral peaks in precipitation in the Kelvin wave band, and, of these 10, only 5 contain wave activity distributions and three-dimensional wave structures that resemble the observations. Thus, the majority (75%) of the global climate models surveyed do not accurately represent convectively coupled Kelvin waves, one of the primary sources of submonthly zonally propagating variability in the tropics. The primary feature common to the five successful models is the convective parameterization. Three of the five models use the Tiedtke–Nordeng convective scheme, while the other two utilize the Pan and Randall scheme. The 15 models with less success at generating Kelvin waves predominantly contain convective schemes that are based on the concept of convective adjustment, although it appears that those schemes can be improved by the addition of convective “trigger” functions. Three-dimensional Kelvin wave structures in the five successful models resemble observations to a large degree, with vertically tilted temperature, specific humidity, and zonal wind anomalies. However, no model completely captures the observed signal, with most of the models being deficient in lower-tropospheric temperature and humidity signals near the location of maximum precipitation. These results suggest the need for improvements in the representations of shallow convection and convective downdrafts in global models.
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Thomsen, Rene O., and Ian Lerche. "Application of Hydrodynamic Modeling to Investigate the Origin of an Observed Tilted Oil-water Contact." Energy Exploration & Exploitation 16, no. 4 (August 1998): 325–43. http://dx.doi.org/10.1177/014459879801600403.
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Two oil fields on structural closures, about 5 km apart and separated by a syncline, are investigated for possible hydrodynamic control of a significant tilt of the oil-water contact (OWC). In addition a possible deeper extent of an oil-leg into the syncline due to hydrodynamic forces is investigated. The first task was to test the applicability of a steady state simulation model for investigating the response of a hydrocarbon-water interface to changing hydrodynamic conditions; then to use the results of the modeling and associated sensitivity analysis to help conclude on the origin and the dynamic forces involved in sustaining the observed tilt of the OWC. Finally the results also suggest further developments of the simulation model. The modeling and sensitivity analysis led to the following conclusions: a) it was possible within the framework of a steady-state model to simulate successfully the observed behavior of the OWC using the resultant force perpendicular to the observed strike of the tilted OWC; b) the observed behavior of the OWC is likely the combined result of a regional tectonic tilt and a significant regional hydrodynamic drive; c) the present-day hydrodynamic drive is adequate to sustain the observed tilt of the OWC; d) it is unlikely that there is a significantly deeper extent of the oil-leg in the Beta field due to the hydrodynamic drive. The investigation also resulted in a discussion of further improvements of the simulation model, focusing on parameter resolution and sensitivity analysis using an inverse scheme to provide a procedure for systematic searches for the combination of parameter values that best fit observations.
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Zhou, Chaoguang, Junru Jiao, Sonny Lin, John Sherwood, and Sverre Brandsberg-Dahl. "Multiparameter joint tomography for TTI model building." GEOPHYSICS 76, no. 5 (September 2011): WB183—WB190. http://dx.doi.org/10.1190/geo2010-0395.1.
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Model building for tilted transversely isotropic media has commonly been performed by a single parameter tomography that updates the velocity in the symmetry direction, while the orientation of the symmetry axis and Thomsen parameters [Formula: see text] and [Formula: see text] are typically estimated from the migration stack and well data. Unfortunately, well data are often not available. In addition, when they are available, their lateral sampling is typically very sparse and their vertical sampling usually spans only a limited range of depths. In order to obtain spatially varying anisotropic models, with or without well data, we developed a multiparameter joint tomographic approach that simultaneously inverts for the velocity in the symmetry axis direction, [Formula: see text] and [Formula: see text]. We derived a set of reflection tomography equations for slowness in the symmetry axis direction and Thomsen parameters [Formula: see text] and [Formula: see text]. In order to address the nonuniqueness of the tomography, we developed a regularization strategy that uses an independent regularization operator and regularization factor for each individual anisotropy parameter. Synthetic tests found that ambiguity exists between the anisotropy parameters and that velocity has a better resolution than [Formula: see text] and [Formula: see text]. They also confirmed that joint tomography provides a better data fit than single parameter tomography. The field example was used to test a way to incorporate the sonic data in the model building process and limit the tomographic updates on certain anisotropy parameters by adjusting the regularization.
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Rocha, Daniel, Nicolay Tanushev, and Paul Sava. "Anisotropic elastic wavefield imaging using the energy norm." GEOPHYSICS 82, no. 3 (May 1, 2017): S225—S234. http://dx.doi.org/10.1190/geo2016-0424.1.
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Based on the energy conservation principle, we derive a scalar imaging condition for anisotropic elastic wavefield migration. Compared with conventional imaging conditions that correlate displacement components or potentials from source and receiver wavefields, the proposed imaging condition does not suffer from polarity reversal, which degrades the image quality after stacking over shots. Our imaging condition also accounts for the directionality of the wavefields in space and time, leading to the attenuation of backscattering artifacts, which commonly appear in elastic reverse time migration images in the presence of strong model contrasts. In addition, our new imaging condition does not require wave-mode decomposition, which demands significant additional cost for elastic wavefields in anisotropic media. To properly image structures, we rely on the anisotropy parameters used in migration, as one would do for any other imaging condition. Our imaging condition is suitable for arbitrary anisotropy. We show the successful application of the anisotropic energy imaging condition by performing numerical experiments on simple and complex geologic models. We compare its quality with conventional counterparts by simulating complex geologic settings with vertical or tilted transverse isotropy.
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Wearne, Susan, Theodore Raphan, and Bernard Cohen. "Control of Spatial Orientation of the Angular Vestibuloocular Reflex by the Nodulus and Uvula." Journal of Neurophysiology 79, no. 5 (May 1, 1998): 2690–715. http://dx.doi.org/10.1152/jn.1998.79.5.2690.
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Wearne, Susan, Theodore Raphan, and Bernard Cohen. Control of spatial orientation of the angular vestibuloocular reflex by the nodulus and uvula. J. Neurophysiol. 79: 2690–2715, 1998. Spatial orientation of the angular vestibuloocular reflex (aVOR) was studied in rhesus monkeys after complete and partial ablation of the nodulus and ventral uvula. Horizontal, vertical, and torsional components of slow phases of nystagmus were analyzed to determine the axes of eye rotation, the time constants (Tcs) of velocity storage, and its orientation vectors. The gravito-inertial acceleration vector (GIA) was tilted relative to the head during optokinetic afternystagmus (OKAN), centrifugation, and reorientation of the head during postrotatory nystagmus. When the GIA was tilted relative to the head in normal animals, horizontal Tcs decreased, vertical and/or roll time constants (Tcvert/roll) lengthened according to the orientation of the GIA, and vertical and/or roll eye velocity components appeared (cross-coupling). This shifted the axis of eye rotation toward alignment with the tilted GIA. Horizontal and vertical/roll Tcs varied inversely, with Tchor being longest and Tcvert/roll shortest when monkeys were upright, and the reverse when stimuli were around the vertical or roll axes. Vertical or roll Tcs were longest when the axes of eye rotation were aligned with the spatial vertical, respectively. After complete nodulo-uvulectomy, Tchor became longer, and periodic alternating nystagmus (PAN) developed in darkness. Tchor could not be shortened in any of paradigms tested. In addition, yaw-to-vertical/roll cross-coupling was lost, and the axes of eye rotation remained fixed during nystagmus, regardless of the tilt of the GIA with respect to the head. After central portions of the nodulus and uvula were ablated, leaving lateral portions of the nodulus intact, yaw-to-vertical/roll cross-coupling and control of Tcvert/roll was lost or greatly reduced. However, control of Tchor was maintained, and Tchor continued to vary as a function of the tilted GIA. Despite this, the eye velocity vector remained aligned with the head during yaw axis stimulation after partial nodulo-uvulectomy, regardless of GIA orientation to the head. The data were related to a three-dimensional model of the aVOR, which simulated the experimental results. The model provides a basis for understanding how the nodulus and uvula control processing within the vestibular nuclei responsible for spatial orientation of the aVOR. We conclude that the three-dimensional dynamics of the velocity storage system are determined in the nodulus and ventral uvula. We propose that the horizontal and vertical/roll Tcs are separately controlled in the nodulus and uvula with the dynamic characteristics of vertical/roll components modulated in central portions and the horizontal components laterally, presumably in a semicircular canal-based coordinate frame.
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Lees, Lynn Hollen. "The challenge of political change: urban history in the 1990s." Urban History 21, no. 1 (April 1994): 7–19. http://dx.doi.org/10.1017/s0963926800010671.
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Urban history is a rapidly expanding, flourishing field in Europe. Nevertheless, urban scholars would do well to re-examine the paradigms within which they have been working as the field today lacks central questions and general interpretive models. Moreover, the common focus on urban biography or upon one region within a single nation-state has become increasingly outmoded, given the international scale of economic processes and migration flows. More attention to topics treated within a European-wide or even international context is needed. In addition, urban history as currently defined is tilted towards social and economic concerns to the neglect of the political arena.
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Dewangan, Pawan, and Ilya Tsvankin. "Modeling and inversion of PS-wave moveout asymmetry for tilted TI media: Part 2 — Dipping TTI layer." GEOPHYSICS 71, no. 4 (July 2006): D123—D134. http://dx.doi.org/10.1190/1.2210987.
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Dipping transversely isotropic layers with a tilted symmetry axis (TTI media) cause serious imaging problems in fold-and-thrust belts and near salt domes. Here, we apply the modified [Formula: see text] method introduced in Part 1 to the inversion of long-offset PP and PS reflection data for the parameters of a TTI layer with the symmetry axis orthogonal to the bedding. The inversion algorithm combines the time- and offset-asymmetry attributes of the PSV-wave with the hyperbolic PP- and SS-wave moveout in the symmetry-axis plane (i.e., the vertical plane that contains the symmetry axis). The weak-anisotropy approximations for the moveout-asymmetry attributes, verified by numerical analysis, indicate that small-offset (leading) terms do not contain independent information for the inversion. Therefore, the parameter-estimation algorithm relies on PS data recorded at large offsets (the offset-to-depth ratio has to reach at least two), which makes the results generally less stable than those for a horizontal TTI layer in Part1. The least-resolved parameter is Thomsen’s coefficient [Formula: see text]that does not directly influence the moveout of either pure or converted modes. Still, the contribution of the PS-wave asymmetry attributes helps to constrain the TTI model for large tilts [Formula: see text] of the symmetry axis [Formula: see text]. The accuracy of the inversion for large tilts can be improved further by using wide-azimuth PP and PS reflections. With high-quality PS data, the inversion remains feasible for moderate tilts [Formula: see text], but it breaks down for models with smaller values of [Formula: see text] in which the moveout asymmetry is too weak. The tilt itself and several combinations of the medium parameters (e.g., the ratio of the P- and S-wave velocities in the symmetry direction), however, are well constrained for all symmetry-axis orientations. The results of Parts 1 and 2 show that 2D measurements of the PS-wave asymmetry attributes can be used effectively in anisotropic velocity analysis for TTI media. In addition to providing an improved velocity model for imaging beneath TTI beds, our algorithms yield information for lithology discrimination and structural interpretation.
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Song, XinKe, DeMin Chen, QingMing Long, and BaoHua Qu. "Development of spring torsion bar type negative stiffness damping device and applied research." Journal of Physics: Conference Series 2137, no. 1 (December 1, 2021): 012040. http://dx.doi.org/10.1088/1742-6596/2137/1/012040.
Full textAbstract:
Abstract Mini-tiller is the most commonly used machine for agricultural production in hilly areas of our country the traditional micro-tiller will produce strong vibration during the working process, which will cause physical injury to the operator while reducing the reliability of the micro-tiller. In response to this problem, a technical solution for arranging a spring torsion bar type negative stiffness vibration damping device on the tiller was proposed, and a spring torsion bar type vibration damping device with stable mechanical performance, economical and practical, and negative stiffness characteristics was developed. A mathematical model of the vibration source of the micro-tiller was established to analyze the vibration parameters of the micro-tiller. On this basis, SolidWorks is used to carry out three-dimensional modeling of the tiller and the vibration reduction device, and Adams is used for vibration simulation analysis. The vibration parameter curve before and after the addition of the vibration reduction device at the handle of the tiller is collected and mathematically analyzed. The results show that the spring torsion bar type negative stiffness damping device has a good damping effect, and the damping rate for displacement in the x, y, and z directions are all above 30%.
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Beleggia, M., R. Capelli, and G. Pozzi. "Interpretation of Holographic and Lorentz Images of an Array of Reverse Biased P-N Junctions in a Semi-Infinite Specimen." Microscopy and Microanalysis 5, S2 (August 1999): 954–55. http://dx.doi.org/10.1017/s1431927600018092.
Full textAbstract:
The problem of observing reverse-biased p-n junctions by means of transmission electron microscopy techniques is very challenging both from the experimental and theoretical points of view. In particular, in addition to standard Lorentz microscopy techniques, whose image contrast is able to give some information on the region of high field, also holographic methods have been successfully applied and an interference map of the twodimensional phase on the specimen plane obtained.In this work we consider, in particular, the theoretical and interpretative aspects, as we have improved a model for the electric field associated to a periodic array of alternating p and n stripes lying in a half plane (physically corresponding to an array of zero-width step junctions) by taking into account that the junctions are tilted with respect to the specimen edge.
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Rahaman Khan, Md Hasinur, and J. Ewart H. Shaw. "Variable selection for accelerated lifetime models with synthesized estimation techniques." Statistical Methods in Medical Research 28, no. 3 (November 9, 2017): 937–52. http://dx.doi.org/10.1177/0962280217739522.
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We develop variable selection approaches for accelerated failure time models, consisting of a group of algorithms based on a synthesis of two widely used techniques in the area of variable selection for survival analysis—the Buckley–James method and the Dantzig selector. Two algorithms are based on proposed modified Buckley–James estimating methods that are designed for high-dimensional censored data. Another two algorithms are based on a two-stage weighted Dantzig selector method where weights are obtained from the two proposed synthesis-based algorithms. The methods are easy to understand and they perform estimation and variable selection simultaneously. Furthermore, they can deal with collinearity among the covariates. We conducted several simulation studies and one empirical analysis with a microarray dataset; these studies demonstrated satisfactory variable selection performance. In addition, the microarray data analysis shows the methods performing similarly to three other correlation-based greedy variable selection techniques in the literature—sure independence screening, tilted correlation screening (TCS), and partial correlation (PC) simple. This empirical study also found that the sure independence screening technique considerably improves the performance of most of the proposed methods.
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Yakushin, S., M. Dai, J. Suzuki, T. Raphan, and B. Cohen. "Semicircular canal contributions to the three-dimensional vestibuloocular reflex: a model-based approach." Journal of Neurophysiology 74, no. 6 (December 1, 1995): 2722–38. http://dx.doi.org/10.1152/jn.1995.74.6.2722.
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1. We studied the contribution of the individual semicircular canals to the generation of horizontal and torsional eye movements in cynomolgus monkeys. Eye movements were elicited by sinusoidal rotation about a vertical (gravitational) axis at 0.2 Hz with the animals tilted in various attitudes of static forward or backward pitch. The gains of the horizontal and torsional components of the vestibuloocular reflex (VOR) were measured for each tilt position. The gains as a function of tilt position were fit with sinusoidal functions, and spatial gains and phases were determined. After control responses were recorded, the semicircular canals were plugged, animals were allowed to adapt, and the test procedure was repeated. Animals were prepared with only the anterior and posterior canals intact [vertical canal (VC) animals], with only the lateral canals intact [lateral canal (LC) animal], and with only one anterior and the contralateral posterior canals intact [right anterior and left posterior canal (RALP) animals; left anterior and right posterior canal (LARP) animals]. 2. In normal animals, the gain of the horizontal (yaw axis) velocity of the compensatory eye movements decreased as they were pitched forward or backward, and a torsional velocity appeared, reversing phase at the peak of the horizontal gain. After the anterior and posterior canals were plugged (LC animal), the horizontal component was reduced when the animal was tilted backward; the gain was zero with about -60 degrees of backward tilt. The spatial phase of the torsional component had the same characteristics. This is consistent with the fact that both responses were produced by the lateral canals, which from our results are tilted between 28 and 39 degrees above the horizontal stereotaxic plane. 3. After both lateral canals were plugged (VC animals), horizontal velocity was reduced in the upright position but increased as the animals were pitched backward relative to the axis of rotation. Torsional velocities, which were zero in the upright position in the normal animal, were now 180 degrees out of phase with the horizontal velocity. The peak values of the horizontal and torsional components were significantly shifted from the normal data and were closely aligned with each other, reaching peak values at approximately -56 degrees pitched back (-53 degrees horizontal, -58 degrees torsional). The same was true for the LARP and RALP animals; the peak values were at -59 degrees pitched back (-55 degrees horizontal, -62 degrees torsional). Likewise, in the LC animal the peak yaw and roll gains occurred at about the same angle of forward tilt, 35 degrees (30 degrees horizontal, 39 degrees torsional). Thus, in each case, the canal plugging had transformed the VOR from a compensatory to a direction-fixed response with regard to the head. Therefore there was no adaptation of the response planes of the individual canals after plugging. 4. The data were compared with eye velocity predictions of a model based on the geometric organization of the canals and their relation to a head coordinate frame. The model used the normal to the canal planes to form a nonorthogonal coordinate basis for representing eye velocity. An analysis of variance was used to define the goodness of fit of model predictions to the data. Model predictions and experimental data agreed closely for both normal animals and for the animals with canal lesions. Moreover, if horizontal and roll components from the LC and VC animals were combined, the summation overlay the response of the normal monkeys and the predictions of the model. In addition, a combination of the RALP and LARP animals predicted the response of the lateral-canal-plugged (VC) animals. 5. When operated animals were tested in light, the gains, peak values, and spatial phases of horizontal and roll eye velocity returned to the preoperative values, regardless of the type of surgery performed. This indicates that vision compensated for the lack o
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Vanek, Jan. "Open-Charm Hadron Measurements in Au+Au Collisions at √sNN = 200 GeV by the STAR Experiment." Universe 5, no. 9 (September 7, 2019): 196. http://dx.doi.org/10.3390/universe5090196.
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Study of the open-charm hadron production in heavy-ion collisions is crucial for understanding the properties of the Quark-Gluon Plasma. In these papers, we report on a selection of recent STAR measurements of open-charm hadrons in Au+Au collisions at s NN = 200 GeV , using the Heavy-Flavor Tracker. In particular, the nuclear modification factors of D 0 and D ± mesons, elliptic and directed flow of D 0 mesons, D s /D 0 and Λ c / D 0 yield ratios are discussed. The observed suppression of D 0 and D ± mesons suggests strong interactions of the charm quarks with the QGP. The measured elliptic flow of D 0 mesons is large and follows the NCQ scaling, suggesting that charm quarks may be close to thermal equilibrium with the QGP medium. Both D s /D 0 and Λ c / D 0 yield ratios are found to be enhanced in Au+Au collisions. The enhancement can be explained by models incorporating coalescence hadronization of charm quarks. In addition, the directed flow of the D 0 mesons is measured to be negative and larger than that of light-flavor mesons which is in a qualitative agreement with hydrodynamic model predictions with a tilted QGP bulk.
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Nowada, M., T. Sakurai, and T. Mukai. "GEOTAIL observation of tilted X-line formation during flux transfer events (FTEs) in the dayside magnetospheric boundary layers." Annales Geophysicae 22, no. 8 (September 7, 2004): 2907–16. http://dx.doi.org/10.5194/angeo-22-2907-2004.
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Abstract. The magnetic field and plasma structures during two successive crossings of the subsolar magnetospheric boundary layers (i.e. MagnetoPause Current Layer (MPCL) and Low-Latitude Boundary Layer (LLBL)) under the southward-dawnward IMF are examined on the basis of the data obtained by the GEOTAIL spacecraft. A significant and interesting feature is found, that is, Flux Transfer Events (FTEs) occur in association with the formation of the tilted X-line. During the first inbound MPCL/LLBL crossing, the ion velocity enhancement (in particular, the Vl component negatively increases) can be observed in association with simultaneous typical bipolar signature (positive followed by negative) in the Bn component. In addition, a clear D-shaped ion distribution whose origin is the magnetosheath can also be found in the dawnward direction. A few minutes later, the satellite experiences outbound MPCL crossing. The negative enhancement of the Vm component can be found as well as the positive enhancement of the Vl component. Simultaneously, a typical bipolar signature with the polarity (negative followed by positive) opposite that observed in the first encounter can also be observed. The ions from the magnetosheath flow predominantly in the duskward direction, although the D-shaped ion distribution cannot be observed. These results indicate that the satellite initially observes one part of a reconnected flux tube formed by FTEs whose magnetospheric side is anchored to the Southern Hemisphere. The ions confined in this partial flux tube are flowing in the south-dawnward direction. Then, the satellite observes the other part of the reconnected flux tube whose magnetospheric side is anchored to the Northern Hemisphere. The ions confined in this flux tube flow dominantly in the north-duskward direction. Furthermore, it can be considered that the second MPCL crossing is a direct cut through the diffusion region of FTEs because the LLBL is absent in the vicinity of the MPCL. On the basis of these results, it can be concluded that the satellite was passing near the tilted X-line. The information obtained through this study is expected to be of great use in discriminating between the anti-parallel (steady-state) reconnection and tilted X-line models on the dayside MPCL.
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Al Husaini, Mohammed Abdulla Salim, Mohamed Hadi Habaebi, Teddy Surya Gunawan, and Md Rafiqul Islam. "Self-Detection of Early Breast Cancer Application with Infrared Camera and Deep Learning." Electronics 10, no. 20 (October 18, 2021): 2538. http://dx.doi.org/10.3390/electronics10202538.
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Breast cancer is the most common cause of death in women around the world. A new tool has been adopted based on thermal imaging, deep convolutional networks, health applications on smartphones, and cloud computing for early detection of breast cancer. The development of the smart app included the use of Mastology Research with the Infrared Image DMR-IR database and the training of the modified version of deep convolutional neural network model inception V4 (MV4). In addition to designing the application in a graphical user interface and linking it with the AirDroid application to send thermal images from the smartphone to the cloud and to retrieve the suggestive diagnostic result from the cloud server to the smartphone. Moreover, to verify the proper operation of the app, a set of thermal images was sent from the smartphone to the cloud server from different distances and image acquisition procedures to verify the quality of the images. Four effects on the thermal image were applied: Blur, Shaken, Tilted, and Flipping were added to the images to verify the detection accuracy. After conducting repeated experiments, the classification results of early detection of breast cancer, generated from the MV4, illustrated high accuracy performance. The response time achieved after the successful transfer of diagnostic results from the smartphone to the cloud and back to the smartphone via the AirDroid application is six seconds. The results show that the quality of thermal images did not affect by different distances and methods except in one method when compressing thermal images by 5%, 15%, and 26%. The results indicate 1% as maximum detection accuracy when compressing thermal images by 5%, 15%, and 26%. In addition, the results indicate detection accuracy increased in Blurry images and Shaken images by 0.0002%, while diagnostic accuracy decreased to nearly 11% in Tilted images. Early detection of breast cancer using a thermal camera, deep convolutional neural network, cloud computing, and health applications of smartphones are valuable and reliable complementary tools for radiologists to reduce mortality rates.
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Maxwell, Reed M., Laura E. Condon, and Peter Melchior. "A Physics-Informed, Machine Learning Emulator of a 2D Surface Water Model: What Temporal Networks and Simulation-Based Inference Can Help Us Learn about Hydrologic Processes." Water 13, no. 24 (December 17, 2021): 3633. http://dx.doi.org/10.3390/w13243633.
Full textAbstract:
While machine learning approaches are rapidly being applied to hydrologic problems, physics-informed approaches are still relatively rare. Many successful deep-learning applications have focused on point estimates of streamflow trained on stream gauge observations over time. While these approaches show promise for some applications, there is a need for distributed approaches that can produce accurate two-dimensional results of model states, such as ponded water depth. Here, we demonstrate a 2D emulator of the Tilted V catchment benchmark problem with solutions provided by the integrated hydrology model ParFlow. This emulator model can use 2D Convolution Neural Network (CNN), 3D CNN, and U-Net machine learning architectures and produces time-dependent spatial maps of ponded water depth from which hydrographs and other hydrologic quantities of interest may be derived. A comparison of different deep learning architectures and hyperparameters is presented with particular focus on approaches such as 3D CNN (that have a time-dependent learning component) and 2D CNN and U-Net approaches (that use only the current model state to predict the next state in time). In addition to testing model performance, we also use a simplified simulation based inference approach to evaluate the ability to calibrate the emulator to randomly selected simulations and the match between ML calibrated input parameters and underlying physics-based simulation.
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Dewez, T. J. B. "Reconstructing 3D coastal cliffs from airborne oblique photographs without ground control points." ISPRS Annals of Photogrammetry, Remote Sensing and Spatial Information Sciences II-5 (May 28, 2014): 113–16. http://dx.doi.org/10.5194/isprsannals-ii-5-113-2014.
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Coastal cliff collapse hazard assessment requires measuring cliff face topography at regular intervals. Terrestrial laser scanner techniques have proven useful so far but are expensive to use either through purchasing the equipment or through survey subcontracting. In addition, terrestrial laser surveys take time which is sometimes incompatible with the time during with the beach is accessible at low-tide. By comparison, structure from motion techniques (SFM) are much less costly to implement, and if airborne, acquisition of several kilometers of coastline can be done in a matter of minutes. In this paper, the potential of GPS-tagged oblique airborne photographs and SFM techniques is examined to reconstruct chalk cliff dense 3D point clouds without Ground Control Points (GCP). The focus is put on comparing the relative 3D point of views reconstructed by Visual SFM with their synchronous Solmeta Geotagger Pro2 GPS locations using robust estimators. With a set of 568 oblique photos, shot from the open door of an airplane with a triplet of synchronized Nikon D7000, GPS and SFM-determined view point coordinates converge to X: ±31.5 m; Y: ±39.7 m; Z: ±13.0 m (LE66). Uncertainty in GPS position affects the model scale, angular attitude of the reference frame (the shoreline ends up tilted by 2°) and absolute positioning. Ground Control Points cannot be avoided to orient such models.
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Kozmus Trajkovski, Klemen, Dejan Grigillo, and Dušan Petrovič. "Optimization of UAV Flight Missions in Steep Terrain." Remote Sensing 12, no. 8 (April 19, 2020): 1293. http://dx.doi.org/10.3390/rs12081293.
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Unmanned aerial vehicle (UAV) photogrammetry is one of the most effective methods for capturing a terrain in smaller areas. Capturing a steep terrain is more complex than capturing a flat terrain. To fly a mission in steep rugged terrain, a ground control station with a terrain following mode is required, and a quality digital elevation model (DEM) of the terrain is needed. The methods and results of capturing such terrain were analyzed as part of the Belca rockfall surveys. In addition to the national digital terrain model (NDTM), two customized DEMs were developed to optimize the photogrammetric survey of the steep terrain with oblique images. Flight heights and slant distances between camera projection centers and terrain are analyzed in the article. Some issues were identified and discussed, namely the vertical images in steep slopes and the steady decrease of UAV heights above ground level (AGL) with the increase of height above take-off (ATO) at 6%-8% rate. To compensate for the latter issue, the custom DEMs and NDTM were tilted. Based on our experience, the proposed optimal method for capturing the steep terrain is a combination of vertical and oblique UAV images.
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Ludwig, Miroslav, and Ingrid Bauerová. "Steric Effects in the Base-Catalyzed Cyclization of 1-[2-(Methoxycarbonyl)phenyl]-3-(2-substituted Phenyl)triazenes." Collection of Czechoslovak Chemical Communications 63, no. 12 (1998): 2075–84. http://dx.doi.org/10.1135/cccc19982075.
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Eleven model 1-[2-(methoxycarbonyl)phenyl]-3-(2-substituted phenyl)triazenes were synthesized and their cyclization kinetics examined in aqueous-methanolic buffer solutions (51 wt.% methanol) at various pH values. 3(2-Substituted phenyl)benzo[d][1,2,3]triazin-4(3H)-ones were identified as the cyclization products. The log kobs vs pH plot was linear with a slope of unity. Investigation of the steric and electronic effects of substituents in the ortho position revealed that substituents at the ring which is bonded to the N(3) nitrogen affect the cyclization rate through their steric effect only, while their electronic effects are statistically insignificant. This fact was explained in terms of the ring being tilted from the plane in which the remaining part of the conjugate base anion of the model substrate lies. The assumed and confirmed BAc2 mechanism involving specific base catalysis begins by deprotonation of the triazene giving rise to the conjugate base, continues with formation of a tetrahedral intermediate, and ends with elimination of the methanolate ion. Other mechanisms, such as the elimination-addition mechanism via a ketene intermediate or the mechanism involving general base catalysis, are unlikely.
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Williamson, Melinda M., Gail W. T. Wilson, and David C. Hartnett. "Controls on bud activation and tiller initiation in C3 and C4 tallgrass prairie grasses: the role of light and nitrogen." Botany 90, no. 12 (December 2012): 1221–28. http://dx.doi.org/10.1139/b2012-091.
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Population dynamics of perennial grasses in tallgrass prairie ecosystems are strongly influenced by vegetative outgrowth from their belowground bud banks. We examined the role of light and nitrogen in regulating tiller initiation and tested an integrated model of controls on bud dormancy and activation in several C3 and C4 grasses. In addition, we assessed the interaction of nitrogen and light quantity and red – far red spectral composition on tiller initiation. Belowground perennating organs of three C3 and three C4 species were grown under full light or dark conditions, amended with one of four nitrogen concentrations (0 to 350 ppm N). Dormant buds were also subjected to full light under different spectral compositions or to continuous darkness. Our results among C3 grasses support the integrated model as light and nitrogen played important and interacting roles in the regulation of bud banks. However, differences in responses among C4 grasses and a lack of light × nitrogen interactions suggest that an alternative model may be necessary for this functional group. Our results provide predictions of responses to nitrogen enrichment or light imitations in prairie ecosystems due to interacting disturbances such as reduction in fire frequencies, alterations in grazing intensities, or climate change.
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ADLER, STEPHEN L. "MODELING THE FLYBY ANOMALIES WITH DARK MATTER SCATTERING: UPDATE WITH ADDITIONAL DATA AND FURTHER PREDICTIONS." International Journal of Modern Physics A 28, no. 15 (June 16, 2013): 1350074. http://dx.doi.org/10.1142/s0217751x13500747.
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We continue our exploration of whether the flyby anomalies can be explained by scattering of spacecraft nucleons from dark matter gravitationally bound to the Earth, with the addition of data from five new flybys to that from the original six. We continue to use our model in which inelastic and elastic scatterers populate shells generated by the precession of circular orbits with normals tilted with respect to the Earth's axis. With 11 data points and eight parameters in the model, a statistically meaningful fit is obtained with a chi-squared of 2.7. We give plots of the anomalous acceleration along the spacecraft trajectory, and the cumulative velocity change, for the five flybys which exhibit a significant nonzero anomaly. We also discuss implications of the fit for dark matter–nucleon cross-sections, give the prediction of our fit for the anomaly to be expected from the future Juno flyby, and give predictions of our fit for flyby orbit orientation changes. In addition, we give formulas for estimating the flyby temperature increase caused by dark matter inelastic scattering, and for the fraction of flyby nucleons undergoing such scatters. Finally, for circular satellite orbits, we give a table of predicted secular changes in orbit radius. These are much too large to be reasonable — comparing with data for COBE and GP-B supplied to us by Edward Wright (after the first version of this paper was posted), we find that our model predicts changes in orbit radius that are too large by many orders of magnitude. So the model studied here is ruled out. We conclude that further modeling of the flyby anomalies must simultaneously attempt to fit constraints coming from satellite orbits.
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Alkhalifah, Tariq. "Traveltime approximations for transversely isotropic media with an inhomogeneous background." GEOPHYSICS 76, no. 3 (May 2011): WA31—WA42. http://dx.doi.org/10.1190/1.3555040.
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A transversely isotropic (TI) model with a tilted symmetry axis is regarded as one of the most effective approximations to the Earth subsurface, especially for imaging purposes. However, we commonly utilize this model by setting the axis of symmetry normal to the reflector. This assumption may be accurate in many places, but deviations from this assumption will cause errors in the wavefield description. Using perturbation theory and Taylor’s series, I expand the solutions of the eikonal equation for 2D TI media with respect to the independent parameter [Formula: see text], the angle the tilt of the axis of symmetry makes with the vertical, in a generally inhomogeneous TI background with a vertical axis of symmetry. I do an additional expansion in terms of the independent (anellipticity) parameter [Formula: see text] in a generally inhomogeneous elliptically anisotropic background medium. These new TI traveltime solutions are given by expansions in [Formula: see text] and [Formula: see text] with coefficients extracted from solving linear first-order partial differential equations. Pade approximations are used to enhance the accuracy of the representation by predicting the behavior of the higher-order terms of the expansion. A simplification of the expansion for homogenous media provides nonhyperbolic moveout descriptions of the traveltime for TI models that are more accurate than other recently derived approximations. In addition, for 3D media, I develop traveltime approximations using Taylor’s series type of expansions in the azimuth of the axis of symmetry. The coefficients of all these expansions can also provide us with the medium sensitivity gradients (Jacobian) for nonlinear tomographic-based inversion for the tilt in the symmetry axis.
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Soulayman, S., and W. Sabbagh. "Optimum Tilt Angle at Tropical Region." International Journal of Renewable Energy Development 4, no. 1 (February 15, 2015): 48–54. http://dx.doi.org/10.14710/ijred.4.1.48-54.
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: One of the important parameters that affect the performance of a solar collector is its tilt angle with the horizon. This is because of the variation of tilt angle changes the amount of solar radiation reaching the collector surface. Meanwhile, is the rule of thumb, which says that solar collector Equator facing position is the best, is valid for tropical region? Thus, it is required to determine the optimum tilt as for Equator facing and for Pole oriented collectors. In addition, the question that may arise: how many times is reasonable for adjusting collector tilt angle for a definite value of surface azimuth angle? A mathematical model was used for estimating the solar radiation on a tilted surface, and to determine the optimum tilt angle and orientation (surface azimuth angle) for the solar collector at any latitude. This model was applied for determining optimum tilt angle and orientation in the tropical zones, on a daily basis, as well as for a specific period. The optimum angle was computed by searching for the values for which the radiation on the collector surface is a maximum for a particular day or a specific period. The results reveal that changing the tilt angle 12 times in a year (i.e. using the monthly optimum tilt angle) maintains approximately the total amount of solar radiation near the maximum value that is found by changing the tilt angle daily to its optimum value. This achieves a yearly gain in solar radiation of 11% to 18% more than the case of a solar collector fixed on a horizontal surface.
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Duchaud, Jean-Laurent, Cyril Voyant, Alexis Fouilloy, Gilles Notton, and Marie-Laure Nivet. "Trade-Off between Precision and Resolution of a Solar Power Forecasting Algorithm for Micro-Grid Optimal Control." Energies 13, no. 14 (July 10, 2020): 3565. http://dx.doi.org/10.3390/en13143565.
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With the development of micro-grids including PV production and storage, the need for efficient energy management strategies arises. One of their key components is the forecast of the energy production from very short to long term. The forecast time-step is an important parameter affecting not only its accuracy but also the optimal control time discretization, hence its efficiency and computational burden. To quantify this trade-off, four machine learning forecast models are tested on two geographical locations for time-steps varying from 2 to 60 min and horizons from 10 min to 6 h, on global irradiance horizontal and tilted when data was available. The results are similar for all the models and indicate that the error metric can be reduced up to 0.8% per minute on the time-step for forecasts below one hour and up to 1.7% per ten minutes for forecasts between one and six hours. In addition, it is shown that for short term horizons, it may be advantageous to forecast with a high resolution then average the results at the time-step needed by the energy management system.
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Xu, Wei, Ruibo Li, Chonghua Fang, Pingping Huang, Weixian Tan, and Yaolong Qi. "Azimuth Multichannel Reconstruction Based on Advanced Hyperbolic Range Equation." Remote Sensing 13, no. 22 (November 21, 2021): 4705. http://dx.doi.org/10.3390/rs13224705.
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To acquire high-resolution wide-swath (HRWS) imaging capacity, the displaced phase center multichannel azimuth beam (DPCMAB) technology is usually adopted in spaceborne synthetic aperture radar (SAR), while multichannel reconstruction must be carried out before imaging process due to azimuth nonuniform sampling. Up to now, almost all azimuth multichannel reconstruction algorithms have been mainly based on conventional hyperbolic range equation (CHRE), but the accuracy of the CHRE model is usually not suitable for the HRWS mode, especially for high resolution and large squint observation cases. In this study, the azimuth multichannel signal model based on the advanced hyperbolic range equation (AHRE) is established and analyzed. The major difference between multichannel signal models based on CHRE and AHRE is the additional time-varying phase error between azimuth channels. The time-varying phase error is small and can be ignored in the monostatic DPCMAB SAR system, but it must be considered and compensated in the distributed DPCMAB SAR system. In addition to the time-varying phase error, additional Doppler spectrum shift and extended Doppler bandwidth should be considered in the squint case during azimuth multichannel reconstruction. The azimuth multichannel reconstruction algorithm based on AHRE is proposed in this paper. Before multichannel reconstruction and combination, time-varying phase errors between azimuth channels were first compensated, and the range-frequency-dependent de-skewing function was derived to remove the two-dimension (2D) spectrum tilt to avoid azimuth under-sampling. Then, azimuth multichannel data were reconstructed according to the azimuth multichannel impulse response based on AHRE. Finally, the range-frequency dependent re-skewing function was introduced to recover the tilted 2D spectrum. Simulation results on both point and distributed targets validated the proposed azimuth multichannel reconstruction approach.
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Berry, I. D., S. P. Owocki, M. E. Shultz, and A. ud-Doula. "Electron scattering emission in the light curves of stars with centrifugal magnetospheres." Monthly Notices of the Royal Astronomical Society 511, no. 4 (February 4, 2022): 4815–25. http://dx.doi.org/10.1093/mnras/stac322.
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ABSTRACT Strongly magnetic, rapidly rotating B-type stars with relatively weak winds form centrifugal magnetospheres (CMs), as the stellar wind becomes magnetically confined above the Kepler co-rotation radius. Approximating the magnetic field as a dipole tilted by an angle β with respect to the rotation axis, the CM plasma is concentrated in clouds at and above the Kepler radius along the intersection of the rotational and magnetic equatorial planes. Stellar rotation can bring such clouds in front of the stellar disc, leading to absorption of the order of 0.1 mag ($\sim 10 {{\ \rm per\ cent}}$ of continuum flux). However, some stars with prominent CMs, such as σ Ori E, show an emission bump in addition to absorption dips, which has been so far unexplained. We show that emission can occur from electron scattering towards the observer when CM clouds are projected off the stellar limb. Using the rigidly rotating magnetosphere model, modified with a centrifugal breakout density scaling, we present a model grid of photometric light curves spanning parameter space in observer inclination angle i, magnetic obliquity angle β, critical rotation fraction W, and optical depth at the Kepler radius τK. We show that τK of order unity can produce emission bumps of the magnitude ∼0.05 seen in σ Ori E. We discuss the implications for modelling the light curves of CM stars, as well as future work for applying the radiative transfer model developed here to 3D magnetohydrodynamic simulations of CMs.
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Fracasso, Michela, Fedor Gömöry, Mykola Solovyov, Roberto Gerbaldo, Gianluca Ghigo, Francesco Laviano, Andrea Napolitano, Daniele Torsello, and Laura Gozzelino. "Modelling and Performance Analysis of MgB2 and Hybrid Magnetic Shields." Materials 15, no. 2 (January 17, 2022): 667. http://dx.doi.org/10.3390/ma15020667.
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Superconductors are strategic materials for the fabrication of magnetic shields, and within this class, MgB2 has been proven to be a very promising option. However, a successful approach to produce devices with high shielding ability also requires the availability of suitable simulation tools guiding the optimization process. In this paper, we report on a 3D numerical model based on a vector potential (A)-formulation, exploited to investigate the properties of superconducting (SC) shielding structures with cylindrical symmetry and an aspect ratio of height to diameter approaching one. To this aim, we first explored the viability of this model by solving a benchmark problem and comparing the computation outputs with those obtained with the most used approach based on the H-formulation. This comparison evidenced the full agreement of the computation outcomes as well as the much better performance of the model based on the A-formulation in terms of computation time. Relying on this result, the latter model was exploited to predict the shielding properties of open and single capped MgB2 tubes with and without the superimposition of a ferromagnetic (FM) shield. This investigation highlighted that the addition of the FM shell is very efficient in increasing the shielding factors of the SC screen when the applied magnetic field is tilted with respect to the shield axis. This effect is already significant at low tilt angles and allows compensating the strong decrease in the shielding ability that affects the short tubular SC screens when the external field is applied out of their axis.
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Redden, R. "The effect of epistasis on chromosome mapping of quantitative characters in wheat. II. Agronomic characters." Australian Journal of Agricultural Research 42, no. 3 (1991): 335. http://dx.doi.org/10.1071/ar9910335.
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Chromosome mapping of agronomic characters in wheat was attempted using the complete chromosome substitution series for both 'Hope' and 'Kenya Farmer' varieties as donors and 'Chinese Spring' as recipient variety, grown in replicated yield trials at four sites in South Australia. Grain yield, fertile tiller numbers, 1000-grain weight, fertile spikelets per spike, total dry weight, spike length and green tiller number were estimated from plot subsamples. Overall between chromosome interactions were found for all characters except total dry weight at one or more sites. The patterns of substitution line effects were similar for both series and did not correspond to differences between donor and recipient varieties. Within site variation was low relative to treatment effects at two sites. Sixty four significant substitution line effects were detected in the Hope series, and 67 in the Kenya Farmer series. A simple additive model for the effects of substituted chromosomes was inadequate because of epistasis. Overall epistatic effects can be predicted from the selection history and adaptation pattern of the recipient variety. Genes from the donor variety for complex growth characters cannot be satisfactorily mapped by substitution line analysis.
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Su, ChungHwei, and ShiuanCheng Wang. "Analysis of tilted neutral planes for tall space fires with unsymmetrical openings using numerical simulation and Schlieren photography technique." International Journal of Numerical Methods for Heat & Fluid Flow 29, no. 11 (November 4, 2019): 4213–36. http://dx.doi.org/10.1108/hff-01-2019-0052.
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Purpose The purpose of this paper is to analyze the variations in the neutral plane when a tall space with unsymmetrical openings is on fire. The neutral plane of the fire scene is an important index of a natural smoke exhaust system. The numerical simulation method and the Schlieren photography technique were used as analysis tools. The results of model experiments and numerical simulation were compared with each other to confirm the rationality of the conclusions. The results were to discuss the characteristics of various cases and showed that the neutral planes of the fire scene were not always horizontal. Design/methodology/approach The numerical simulation method and the Schlieren photography technique were used as analysis tools. The flow patterns of hot air in various cases were recorded using the flow visualization technique. In addition, the renowned simulation software, fire dynamics simulator (FDS), was used for case analysis. The Schlieren photography technique was used for 1/12.5 model experiments with six smokeless candles burned, and FDS was used for a numerical simulation. In terms of the case of unilateral vents, the exhaust efficiency was discussed when the exhaust vent and air inlet were located on the same side or different sides. Findings This study demonstrates that makeup air flowing in from the inlets and openings has a significant impact on the effectiveness of natural smoke exhaust systems. The results illustrated that the neutral planes were tilted in some cases. In some cases, the results showed that one side was the air inlet and the other side was the exhaust vent, even if the openings were at the same height in some cases. These phenomena have rarely been discovered or studied in the past. The exhaust efficiency was not always better when the vent was located in the rooftop. Originality/value This study analyzed the neutral plane of a fire scene using the common unsymmetrical opening spaces in the Taiwan region as an example. The phenomenon of non-horizontal neutral plane has rarely been studied in the past. The temperature of the discharged hot gas was low because of an efficient exhaust effect, which reduced the heat and smoke storage in the space. The results obtained by these two methods were consistent, and showed that the cases with the same opening area had different smoke extraction efficiencies, meaning the smoke extraction effect cannot be judged only by the opening areas.
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Al-Rawahi, N. Z., Y. H. Zurigat, and N. A. Al-Azri. "Prediction of Hourly Solar Radiation on Horizontal and Inclined Surfaces for Muscat/Oman." Journal of Engineering Research [TJER] 8, no. 2 (December 1, 2011): 19. http://dx.doi.org/10.24200/tjer.vol8iss2pp19-31.
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In this paper, hourly terrestrial radiation: direct beam, diffuse and global solar radiation are modelled and calculated based on daily measured data for a horizontal surface. In addition, the same parameters were modelled for inclined surfaces. Most of the parameters modelled in this work represent a part of the input data required by building thermal simulation and solar energy systems software. Important trends of the solar radiation on tilted surfaces as a function of time and direction are being presented and discussed. The comparison of some of the results with measured data from other sources shows good agreement. The effect of tilt angle and orientation on the incident solar radiation fluxes arepresented along with optimum surface tilt angles and directions for maximum solar radiation collection in Muscat area. The results presented in this paper are quite useful for quick estimation of solar radiation for calculations of cooling load and solar collector performance. Also, the models and the computer code developed in this work form the backbone of any computer-aided building thermal design and solar systems design calculations.
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Jansen, D., M. G. Llorens, J. Westhoff, F. Steinbach, S. Kipfstuhl, P. D. Bons, A. Griera, and I. Weikusat. "Small-scale disturbances in the stratigraphy of the NEEM ice core: observations and numerical model simulations." Cryosphere Discussions 9, no. 5 (October 29, 2015): 5817–47. http://dx.doi.org/10.5194/tcd-9-5817-2015.
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Abstract. Disturbances on the centimetre scale in the stratigraphy of the NEEM ice core (North Greenland) can be mapped by an optical line scanner as long as the ice does have a visual layering, such as, for example, cloudy bands. Different focal depths allow, to a certain extent, a three dimensional view of the structures. In this study we present a detailed analysis of the visible folds, discuss their characteristics and frequency and present examples of typical fold structures. We also analyse the structures with regard to the deformation boundary conditions under which they formed. The structures evolve from gentle waves at about 1500 m to overturned z-folds with increasing depth. Occasionally, the folding causes significant thickening of layers. Their similar-fold shape indicates that they are passive features and are probably not initiated by rheology differences between alternating layers. Layering is heavily disturbed and tracing of single layers is no longer possible below a depth of 2160 m. c-axes orientation distributions for the corresponding core sections were analysed where available in addition to visual stratigraphy. The data show axial-plane parallel strings of grains with c-axis orientations that deviate from that of the matrix, which shows a single-maximum fabric at the depth where the folding occurs. Numerical modelling of crystal viscoplasticity deformation and dynamic recrystallisation was used to improve the understanding of the formation of the observed structures during deformation. The modelling reproduces the development of bands of grains with a tilted orientation relative to the single maximum fabric of the matrix, and also the associated local deformation. We conclude from these results that the observed folding is a consequence of localized deformation at the boundaries of kink bands.
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Nguyen, Tuan Anh. "Improving the Stability of the Passenger Vehicle by Using an Active Stabilizer Bar Controlled by the Fuzzy Method." Complexity 2021 (December 23, 2021): 1–20. http://dx.doi.org/10.1155/2021/6569298.
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The rollover phenomenon is a particularly dangerous problem. This phenomenon occurs when the driver travels at high speed and suddenly steers. Under the influence of centrifugal force, the body vehicle will be tilted and cause the wheels to lift off the road. To solve this problem, the method of using an active stabilizer bar has been proposed. The active stabilizer bar is controlled automatically by a previously designed controller. The performance of the active stabilizer bar depends on the selected control method. Previous research often only used a half-car dynamics model combined with a linear single-track dynamics model to simulate the vehicle’s oscillation. In addition, most of the research focuses only on the use of linear control methods for the active stabilizer bar. Therefore, the performance of the stabilizer bar is not guaranteed. This paper focuses on establishing the model of spatial dynamics combined with the nonlinear double-track dynamics model that fully describes the vehicle’s oscillation most accurately. Besides, the fuzzy control method is proposed to control the operation of the hydraulic stabilizer bar. This is a completely novel model, and it is suitable for the actual traveling conditions of the vehicle. Also, simulations are done based on different scenarios. The results of the paper showed that the values of the roll angle, the difference in the vertical force at the wheels, and the displacement of the unsprung mass were significantly reduced when the vehicle used the active stabilizer bar, which is controlled by an intelligent control method. Therefore, the stability and safety of the vehicle have been guaranteed. This result will be the basis for performing other more complex research in the future.
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Shiravi, Shahram. "Static Parametric Stress-Strain Analysis for Asphaltic Concrete Core of Rockfill Dams." Journal of Applied Engineering Sciences 12, no. 1 (May 1, 2022): 87–96. http://dx.doi.org/10.2478/jaes-2022-0013.
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Abstract This study was conducted to investigate the effect of variations in the asphaltic concrete core Rockfill dam geometric parameters on the core behavior at different upper, middle, and lower points under two-dimensional static stress-strain analysis. The mentioned analysis was performed using SIGMA/W software. In the modeling and analysis process, the geometry of a large number of dams constructed around the world was studied and many numerical models with variations in eight classes of height, three dams upstream/downstream slope modes, and three different asphaltic core positions and thicknesses on a rigid foundation were created and analyzed. In addition, for each of the above models, four dam operation stages including “End of Construction”, “Full Reservoir”, “Half-Full Reservoir”, and “Rapid Drawdown” were considered. The results show, in four different stages of construction and impounding and three different slope modes, the maximum stress as well as horizontal and vertical displacements at the upper, middle, and lower points of the core increase with increasing height. In all models, increasing upstream and downstream slopes results in an increase in the amount of vertical displacement for all construction and impounding stages at the upper, middle, and lower points of the core. In the middle and lower points of the core, with increasing height, the amount of deviatoric stress increases for all construction and impounding conditions. In addition, for all operation cases, the maximum strain increases in all points of the vertical and tilted cores as the core thickness increases. Additional results are presented in the next sections.