Journal articles on the topic 'Topography'
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1
Vetter, William M., Hidekazu Tsuchida, Isaho Kamata, and Michael Dudley. "Simulation of Threading Edge Dislocation Images in X-Ray Topographs of Silicon Carbide Homo-Epilayers." Materials Science Forum 527-529 (October 2006): 411–14. http://dx.doi.org/10.4028/www.scientific.net/msf.527-529.411.
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Among the types of dislocation seen in homo-epilayers of SiC grown upon 4H-SiC wafers with an 8° surface offcut are basal plane dislocations propagated into the epilayer at an 8° inclination, and threading edge dislocations. These types may be imaged by monochromatic synchrotron x-ray topography in the grazing-incidence reflection geometry using the 11 2 8 reflection. Equations needed to apply the ray-tracing method of computer simulating x-ray topographic defect images in this experimental geometry were derived and used to simulate images of the threading edge dislocations. Simulations of the threading edge dislocations showed 4 μm wide white ovals with narrow arcs of dark contrast at their ends, inclined relative to the g-vector of the topograph according to the sign of their Burgers vector. These resembled the experimental topographs, inasmuch as was possible at the maximum resolution of x-ray topographs.
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Vetter, W. M., H. Tsuchida, I. Kamata, and M. Dudley. "Simulation of threading dislocation images in X-ray topographs of silicon carbide homo-epilayers." Journal of Applied Crystallography 38, no. 3 (May 13, 2005): 442–47. http://dx.doi.org/10.1107/s0021889805005819.
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Three types of dislocation are seen in homo-epilayers of SiC grown on 4H-SiC wafers with an 8° surface offcut: axial screw dislocations, basal plane dislocations propagated into the epilayer at an 8° inclination and threading edge dislocations. These types may be imaged by monochromatic synchrotron X-ray topography in the grazing-incidence reflection geometry using the 11\overline 28 reflection. Equations needed to apply the ray-tracing method of computer simulating X-ray topographic defect images in this experimental geometry were derived and used to simulate images of all three. Simulations for axial screw dislocations appear as white circles surrounded by narrow dark rings, and those for basal plane dislocations as linear white streaks, both consistent with experimental topographs. Simulations of the threading edge dislocations showed 4 µm wide white ovals with narrow arcs of dark contrast at their ends, inclined relative to the g vector of the topograph according to the sign of their Burgers vector. These images resembled the experimental topographs inasmuch as was possible at the maximum resolution of X-ray topographs.
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Lovelace, Jeffrey J., Cameron R. Murphy, Reinhard Pahl, Keith Brister, and Gloria E. O. Borgstahl. "Tracking reflections through cryogenic cooling with topography." Journal of Applied Crystallography 39, no. 3 (May 10, 2006): 425–32. http://dx.doi.org/10.1107/s0021889806012763.
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The mosaic structure of a single protein crystal was analyzed by reflection profiling and topography using highly parallel and monochromatic synchrotron radiation. Fine-φ-sliced diffraction images (0.002° stills) were collected using a conventional large-area CCD detector in order to calculate reflection profiles. Fine-φ-sliced topographic data (0.002°) stills were collected with a digital topography system for three reflections in a region where the Lorentz effect was minimized. At room temperature, several different mosaic domains were clearly visible within the crystal. Without altering the crystal orientation, the crystal was cryogenically frozen (cryocooled) and the experiment was repeated for the same three reflections. Topographs at cryogenic temperatures reveal a significantly increased mosaicity, while the original domain structure is maintained. A model for the observed changes during cryocooling is presented.
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Yosanny, Agustinna, Muhammad Ismail, and Handoko Said. "Perancangan Augmented Reality untuk Peta Topografi." ComTech: Computer, Mathematics and Engineering Applications 4, no. 2 (December 1, 2013): 1173. http://dx.doi.org/10.21512/comtech.v4i2.2587.
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Topography is the science about the earth's surface and other objects such as planets, satellites, and asteroids. Topography is studied at school and is found quite difficult to understand because it requires imagination to understand the meaning of contour maps as well as the lines. To motivate students in learning topography,we design an learning application of interactive topographic map with 3D features using Augmented reality technology. In this research we implement analysis and design method. The result achieved is a learning topographic map application based on augmented reality. The conclusion that can be drawn is the teaching and learning of topography can be more interesting with 3D features so that students can more easily recognize the meaning of contour lines in a topographic map.
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Zivkovic, Dragica, and Aleksandar Valjarevic. "Digital analyses of cartometric Fruska Gora guidelines." Glasnik Srpskog geografskog drustva 93, no. 3 (2013): 1–10. http://dx.doi.org/10.2298/gsgd1303001z.
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Modern geo morphological topography research have been using quantity statistic and cartographic methods for topographic relief features, mutual relief features, mutual connection analyses on the grounds of good quality numeric parameters etc. Topographic features are important for topographic activities are important for important natural activities. Important morphological characteristics are precisely at the angle of topography, hypsometry, and topography exposition and so on. Small yet unknown relief slants can deeply affect land configuration, hypsometry, topographic exposition etc. Expositions modify the light and heat of interconnected phenomena: soil and air temperature, soil disintegration, the length of vegetation period, the complexity of photosynthesis, the fruitfulness of agricultural crops, the height of snow limit etc.
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Winter, J. M., R. E. Green, and K. A. Green. "Application of Synchrotron and Flash X-Ray Topography to Improved Processing of Electronic Materials." Advances in X-ray Analysis 35, A (1991): 239–45. http://dx.doi.org/10.1154/s0376030800008880.
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AbstractWhite beam transmission topography was used to image defect structures in gallium arsenide single crystal substrates representative of those used for microwave integrated circuit fabrication. A scanning topographic camera was developed for Beamline X-19C at the National Synchrotron Light Source. Acquiring film topographs within a particular range of scan rates and x-ray fluxes was found to produce distorted images. The distortions were shown to be thermoelastic, arising from inhomogeneous deposition of thermal energy through the absorption of residual x-rays. The problem could be circumvented using faster scans with some sacrifice in spatial resolution. Real time electrooptic topographs were recorded using x-ray fluxes about one percent of those used for the film topographs. The potential for reducing the flux requirement to even lower levels which would be accessible to flash x-ray generators is considered.
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Shragge, Jeffrey. "Reverse time migration from topography." GEOPHYSICS 79, no. 4 (July 1, 2014): S141—S152. http://dx.doi.org/10.1190/geo2013-0405.1.
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Migration of seismic data from topography using methods based on finite-difference (FD) approximation to acoustic wave propagation commonly suffers from a number of imaging drawbacks due to the difficulty of applying FD stencils to irregular computational meshes. Altering the computational geometry from Cartesian to a topographic coordinate system conformal to the data acquisition surface can circumvent many of these issues. The coordinate transformation approach allows for acoustic wave propagation and the crosscorrelation and inverse-scattering imaging conditions to be posed and computed directly in topographic coordinates. Resulting reverse time migration (RTM) images may then be interpolated back to the Cartesian domain using the known inverse mapping. Orthogonal 2D topographic coordinates can be developed using known conformal mapping transforms and serve as the computational mesh for performing migration from topography. Impulse response tests demonstrate the accuracy of the 2D generalized acoustic wave propagation. RTM imaging examples show the efficacy of performing migration from topography directly from the data acquisition surface on topographic meshes and the ability to image complex near-surface structure even in the presence of strong lateral velocity variation.
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Chu, Xuefeng, Xinhua Jia, and Yang Liu. "Quantification of wetting front movement under the influence of surface topography." Soil Research 56, no. 4 (2018): 382. http://dx.doi.org/10.1071/sr17071.
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Soil surface topography affects fundamental hydrologic processes, such as infiltration and soil water percolation. Topographic variations potentially alter both the magnitude and directions of unsaturated flow. The objective of this study is to evaluate the effects of surface topography on wetting front moving patterns under different rainfall and soil conditions through combined experimental and numerical modelling studies. Specifically, laboratory-scale infiltration and unsaturated flow experiments and HYDRUS-2D modelling were conducted for different topographic surfaces, rainfall intensities, and soil types. The simulated and observed wetting front distributions were compared and evaluated. Two different stages were observed: topography-dominated two-dimensional flow and uniform one-dimensional flow. A uniformly distributed wetting front was eventually achieved although soil surfaces had dissimilar topographic characteristics. However, the timing or duration to reach such a uniform flat wetting front varied, mainly depending on surface topography, rainfall characteristics, and soil hydraulic properties. The findings from this study are important to better understand the mechanism of topography-controlled unsaturated flow, wetting front movement, and overland flow generation, and to further improve modelling of soil water flow and transport processes under such complex conditions across different scales.
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Chen, Cheng, Yigang Wang, and Huiming Huang. "Investigations of Topographic Effect on Radial Current in South Yellow Sea." Polish Maritime Research 24, s3 (November 27, 2017): 123–29. http://dx.doi.org/10.1515/pomr-2017-0114.
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Abstract Large scaled projects are conducted in South Yellow Sea in recent years. Topographic effect and tidal current are key issues to the coastal engineering and the ocean engineering. In this study, field surveys were conducted to investigate the tidal level, current velocity, and current direction in South Yellow Sea. A numerical model was developed to simulate the radial current field based on the field data. To investigate the mechanism of the radial current field, the actual topography and a smoothed topography were applied in the numerical model, respectively. Results show that, the current field appeares radial because of the tidal system rather than the submarine topography. Local topography centralized the radiation centre and shifted the high-velocity zones. The actual topographic effect is proposed, and results show that local topography increases the flood tide velocity and decreases the ebb tide velocity. Lagrangian residual currents are calculated to illustrate possible sediment sources and transport routes.
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Biahun, Ratsibor. "Maps of Minsk of the late XVIII – early XIX century as the sources on social topography of the city." Genesis: исторические исследования, no. 3 (March 2020): 39–59. http://dx.doi.org/10.25136/2409-868x.2020.3.32406.
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This article examines the maps of Minsk of the late XVIII – early XIX century as the sources on social topography of the city. Socio-topographic approach in history implies combining topographic data and social research. City maps have been traditionally viewed as the sources for reconstructing urban topography. However, they often contain valuable data on population of the city, thus it is suggested viewing the maps of Minsk as the carriers of two types of information – topographic and social. Having prepared a review of twenty city maps, the author demonstrates the context of their emergence and provides brief description. The importance of city maps for reconstruction of its topography is underlined. Bases on studying the cartographic content of maps, the author reproduces the image of Minsk of the late XVIII – early XIX; determines the records on social characteristics of urban population. The meaning of cartographic sources for examination of social topography of Minsk is defined.
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Yin, Zhen, Chen Zuo, Emma J. MacKie, and Jef Caers. "Mapping high-resolution basal topography of West Antarctica from radar data using non-stationary multiple-point geostatistics (MPS-BedMappingV1)." Geoscientific Model Development 15, no. 4 (February 18, 2022): 1477–97. http://dx.doi.org/10.5194/gmd-15-1477-2022.
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Abstract. The subglacial bed topography is critical for modelling the evolution of Thwaites Glacier in the Amundsen Sea Embayment (ASE), where rapid ice loss threatens the stability of the West Antarctic Ice Sheet. However, mapping of subglacial topography is subject to uncertainties of up to hundreds of metres, primarily due to large gaps of up to tens of kilometres in airborne ice-penetrating radar flight lines. Deterministic interpolation approaches do not reflect such spatial uncertainty. While traditional geostatistical simulations can model such uncertainty, they become difficult to apply because of the significant non-stationary spatial variation of topography over such large surface area. In this study, we develop a non-stationary multiple-point geostatistical (MPS) approach to interpolate large areas with irregular geophysical data and apply it to model the spatial uncertainty of entire ASE basal topography. We collect 166 high-quality topographic training images (TIs) of resolution 500 m to train the gap-filling of radar data gaps, thereby simulating realistic topography maps. The TIs are extensively sampled from deglaciated regions in the Arctic as well as Antarctica. To address the non-stationarity in topographic modelling, we introduce a Bayesian framework that models the posterior distribution of non-stationary TIs assigned to the local line data. Sampling from this distribution then provides candidate training images for local topographic modelling with uncertainty, constrained to radar flight line data. Compared to traditional MPS approaches that do not consider uncertain TI sampling, our approach results in a significant improvement in the topographic modelling quality and efficiency of the simulation algorithm. Finally, we simulate multiple realizations of high-resolution ASE topographic maps. We use the multiple realizations to investigate the impact of basal topography uncertainty on subglacial hydrological flow patterns.
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Balmforth, Neil J., and Thomas Peacock. "Tidal Conversion by Supercritical Topography." Journal of Physical Oceanography 39, no. 8 (August 1, 2009): 1965–74. http://dx.doi.org/10.1175/2009jpo4057.1.
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Abstract Calculations are presented of the rate of energy conversion of the barotropic tide into internal gravity waves above topography on the ocean floor. The ocean is treated as infinitely deep, and the topography consists of periodic obstructions; a Green function method is used to construct the scattered wavefield. The calculations extend the previous results of Balmforth et al. for subcritical topography (wherein waves propagate along rays whose slopes exceed that of the topography everywhere), by allowing the obstacles to be arbitrarily steep or supercritical (so waves propagate at shallower angles than the topographic slopes and are scattered both up and down). A complicated pattern is found for the dependence of energy conversion on ε, the ratio of maximum topographic slope to wave slope, and the ratio of obstacle amplitude and separation. This results from a sequence of constructive and destructive interferences between scattered waves that has implications for computing tidal conversion rates for the global ocean.
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Cai, Yiheng, Fuxing Wan, Shinan Lang, Xiangbin Cui, and Zijun Yao. "Multi-Branch Deep Neural Network for Bed Topography of Antarctica Super-Resolution: Reasonable Integration of Multiple Remote Sensing Data." Remote Sensing 15, no. 5 (February 28, 2023): 1359. http://dx.doi.org/10.3390/rs15051359.
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Bed topography and roughness play important roles in numerous ice-sheet analyses. Although the coverage of ice-penetrating radar measurements has vastly increased over recent decades, significant data gaps remain in certain areas of subglacial topography and need interpolation. However, the bed topography generated by interpolation such as kriging and mass conservation is generally smooth at small scales, lacking topographic features important for sub-kilometer roughness. DeepBedMap, a deep learning method combined with multiple surface observation inputs, can generate high-resolution (250 m) bed topography with realistic bed roughness but produces some unrealistic artifacts and higher bed elevation values in certain regions, which could bias ice-sheet models. To address these issues, we present MB_DeepBedMap, a multi-branch deep learning method to generate more realistic bed topography. The model improves upon DeepBedMap by separating inputs into two groups using a multi-branch network structure according to their characteristics, rather than fusing all inputs at an early stage, to reduce artifacts in the generated topography caused by earlier fusion of inputs. A direct upsampling branch preserves large-scale subglacial landforms while generating high-resolution bed topography. We use MB_DeepBedMap to generate a high-resolution (250 m) bed elevation grid product of Antarctica, MB_DeepBedMap_DEM, which can be used in high-resolution ice-sheet modeling studies. Moreover, we test the performance of MB_DeepBedMap model in Thwaites Glacier, Gamburtsev Subglacial Mountains, and several other regions, by comparing the qualitative topographic features and quantitative errors of MB_DeepBedMap, BEDMAP2, BedMachine Antarctica, and DeepBedMap. The results show that MB_DeepBedMap can provide more realistic small-scale topographic features and roughness compared to BEDMAP2, BedMachine Antarctica, and DeepBedMap.
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Landais, F., F. Schmidt, and S. Lovejoy. "Universal multifractal Martian topography." Nonlinear Processes in Geophysics 22, no. 6 (November 30, 2015): 713–22. http://dx.doi.org/10.5194/npg-22-713-2015.
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Abstract. In the present study, we investigate the scaling properties of the topography of Mars. Planetary topographic fields are well known to roughly exhibit (mono)fractal behavior. Indeed, the fractal formalism reproduces much of the variability observed in topography. Still, a single fractal dimension is not enough to explain the huge variability and intermittency. Previous studies have claimed that fractal dimensions might be different from one region to another, excluding a general description at the planetary scale. In this article, we analyze the Martian topographic data with a multifractal formalism to study the scaling intermittency. In the multifractal paradigm, the apparent local variation of the fractal dimension is interpreted as a statistical property of multifractal fields. We analyze the topography measured with the Mars Orbiter Laser altimeter (MOLA) at 300 m horizontal resolution, 1 m vertical resolution. We adapted the Haar fluctuation method to the irregularly sampled signal. The results suggest a multifractal behavior from the planetary scale down to 10 km. From 10 to 300 m, the topography seems to be simple monofractal. This transition indicates a significant change in the geological processes governing the Red Planet's surface.
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Landais, F., F. Schmidt, and S. Lovejoy. "Universal multifractal Martian topography." Nonlinear Processes in Geophysics Discussions 2, no. 4 (July 18, 2015): 1007–31. http://dx.doi.org/10.5194/npgd-2-1007-2015.
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Abstract. In the present study, we investigate the scaling properties of the topography of Mars. Planetary topographic fields are well known to roughly exhibit (mono)fractal behavior. Indeed, the fractal formalism is reproduces much of the variability observed in topography. Still, a single fractal dimension is not enough to explain the huge variability and intermittency. Previous studies have claimed that fractal dimensions might be different from one region to an other, excluding a general description at the planetary scale. In this article, we are analyzing the Martian topographic data with a multifractal formalism to study the scaling intermittency. In the multifractal paradigm, the apparent local variation of the fractal dimension is interpreted as a statistical property of multifractal fields. We analyze the topography measured with the laser altimeter MOLA at 300 m horizontal resolution, 1 m vertical resolution. We adapted the Haar fluctuation method to the the irregularly sampled signal. The results suggest a multifractal behavior from planetary scale down to 10 km. From 10 km to 300 m, the topography seems to be simple monofractal. This transition indicates a significant change in the geological processes governing the Red Planet's surface.
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Zhao, Baojun, and Jiaxin Wang. "Forced solitary wave and vorticity with topography effect in quasi-geostrophic modelling." Advances in Mechanical Engineering 15, no. 1 (January 2023): 168781322211402. http://dx.doi.org/10.1177/16878132221140212.
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A forced KdV equation including the special topography effect is derived to describe nonlinear long wave and solitary eddy based on the quasi-geostrophic potential vorticity model. We obtain the theoretical solution of the equation and the concrete form of stream function through perturbation theory and multi-scale analysis methods. It is found that the joint effect of weak shear basic flow and topography can change the cyclone and anticyclone structure of eddy, and in the meantime topographic structure affects the East-West propagation direction of solitary wave. Finally, according to the interaction between nonlinear long wave and topography by pseudo spectral numerical method, the topographic height is related to the amplitude, wavelength and wave velocity of the excited wave train, and the topography affects not only the spatial structure of wave, but also the amplitude of wave.
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Goff, Benjamen. "Medicalizing Topography: The French Army and Mediterranean Climates, 1760–1860." Canadian Journal of Health History 41, no. 1 (May 1, 2024): 37–66. http://dx.doi.org/10.3138/cjhh.624-122022.
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This article details how the French army employed medical topography as a tool of military occupation throughout the Mediterranean world from the mid-eighteenth to mid-nineteenth century. It departs from other works by focusing exclusively on medical topography's military applications. Medical topographies charted the connections between health and the environment by observing a location's features, such as soil, air, and water quality, as well as elevation, prevailing winds, common local diseases, sources of potential contagion, and the cleanliness of urban environments. Because a medical-topographic study took time to write and implement, its findings provided little utility during active conflict. Only after the fighting ceased during a campaign could the army make use of a medical topography's findings by taking measures such as draining swamps, relocating hospitals in unhealthy environments, and issuing climate-appropriate gear.
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White, Andrew J., and N. Robb McDonald. "The Motion of a Point Vortex near Large-Amplitude Topography in a Two-Layer Fluid." Journal of Physical Oceanography 34, no. 12 (December 1, 2004): 2808–24. http://dx.doi.org/10.1175/jpo2658.1.
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Abstract This work examines the dynamics of point vortices in a two-layer fluid near large-amplitude, sharply varying topography like that which occurs in continental shelf regions. Topography takes the form of an infinitely long step change in depth, and the two-layer stratification is chosen such that the height of topography in the upper layer is a small fraction of the overall depth, enabling quasigeostrophic theory to be used in both layers. An analytic expression for the dispersion relation of free topographic waves in this system is found. Weak vortices are studied using linear theory and, if located in the lower layer, propagate mainly because of their image in the topography. Depending on their sign, they are able to produce significant topographic wave radiation in their wakes. Upper-layer vortices propagate much slower and produce relatively small amplitude topographic wave radiation. Contour dynamics results are used to investigate the nonlinear regions of parameter space. For lower-layer vortices, linear theory is a good approximation, but for upper-layer vortices complicated features evolve and linear theory is only valid for weak vortices.
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Lin, Changhong, Sumei Zhong, Esben Auken, Hongzhu Cai, Handong Tan, Miao Peng, and Wenxin Kong. "The effects of 3D topography on controlled-source audio-frequency magnetotelluric responses." GEOPHYSICS 83, no. 2 (March 1, 2018): WB97—WB108. http://dx.doi.org/10.1190/geo2017-0429.1.
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We have investigated the 3D topographic effects on controlled-source audio-frequency magnetotelluric data. Two 3D topographic models are considered: a trapezoidal-hill model and a trapezoidal-valley model. Different responses are generated, including the amplitude of the electric field, the amplitude of the magnetic field, the apparent resistivity, and phase data. The responses distorted by the 3D topography are simulated for the source located next to and on the hill/valley. Our study indicates that all electric field, magnetic field, apparent resistivity, and phase data are influenced by 3D topography, but to different extents. These topographic effects depend on the transmission-receiver-topography geometry, the transmission frequency, earth resistivity, and the roughness of the surface. The effects in the near-field generated by topography in the survey area are quite different from those in the far-field because of the existence of the source. Compared with those in the far-field zone, the magnetic field and phase data in the near-field zone are less distorted, but more distortions can be found on the electric field and apparent resistivity data over the hill and valley models. Our results also indicate that not only can the 3D topography in the receiver area lead to strong distortions, but also that at the source position can lead to strong distortions. We concluded our study by quantifying the roughness with which the topographic distortion can be ignored, setting the accepted data distortion to a maximum of 10%.
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Zhang, Ying, Shikun Dai, Qianjiang Zhang, Qingrui Chen, and Jiaxuan Ling. "Numerical Modeling of Anisotropic Magnetic Field for High Susceptibility in Undulating Topography." Journal of Physics: Conference Series 2651, no. 1 (December 1, 2023): 012084. http://dx.doi.org/10.1088/1742-6596/2651/1/012084.
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Abstract Most minerals with high magnetism have anisotropic characteristics, and the magnetic field distribution will be affected by topography. Based on the numerical modeling of magnetic field of anisotropic ferromagnetic body, this paper introduces the undulating topographic surface, sets up multiple horizontal planes with different depths between the highest point and the lowest point of the undulating terrain, calculates the magnetic field of these horizontal planes, and finally obtains the distribution of magnetic anomaly field on undulating topographic surface through interpolation. The correctness of undulating topography calculation is verified by comparison with the analytical solution. It is of great significance for inversion imaging of strong magnetic bodies in undulating topography.
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Zhao, Yujin, Liaoying Zhao, Huaguo Zhang, and Bin Fu. "LSTM-Based Remote Sensing Inversion of Largescale Sand Wave Topography of the Taiwan Banks." Remote Sensing 13, no. 16 (August 21, 2021): 3313. http://dx.doi.org/10.3390/rs13163313.
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Shallow underwater topography has important practical applications in fisheries, navigation, and pipeline laying. Traditional multibeam bathymetry is limited by the high cost of largescale topographic surveys in large, shallow sand wave areas. Remote sensing inversion methods to detect shallow sand wave topography in Taiwan rely heavily on measured water depth data. To address these problems, this study proposes a largescale remote sensing inversion model of sand wave topography based on long short-term memory network machine learning. Using multi-angle sun glitter remote sensing to obtain sea surface roughness (SSR) information and by learning and training SSR and its corresponding water depth information, the sand wave topography of a largescale shallow sea sand wave region is extracted. The accuracy of the model is validated through its application to a 774 km2 area in the sand wave topography of the Taiwan Banks. The model obtains a root mean square error of 3.31–3.67 m, indicating that the method has good generalization capability and can achieve a largescale topographic understanding of shallow sand waves with some training on measured bathymetry data. Sand wave topography is widely present in tidal environments; our method has low requirements for ground data, with high application value.
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Poulin, F. J., and G. R. Flierl. "The Influence of Topography on the Stability of Jets." Journal of Physical Oceanography 35, no. 5 (May 1, 2005): 811–25. http://dx.doi.org/10.1175/jpo2719.1.
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Abstract In this article, the effect shelflike topography has on the stability of a jet that flows along the smooth shelf is addressed. The linear stability problem is solved to determine for which nondimensional parameters a shelf can either destabilize or stabilize a jet. These calculations reveal an intricate dependence of growth rate on topography. In particular, the authors determine that retrograde topography (with the shallow water on the left) always stabilizes the jet (in relation to the flat-bottom equivalent), whereas prograde topography (with the shallow water on the right) can either stabilize or destabilize the jet depending on the particular values of the Rossby number and topographic parameters. For Rossby numbers of order 1 and larger, prograde topography is strictly stabilizing. For small Rossby numbers, small-amplitude topography destabilizes whereas large topography stabilizes. The nonlinear evolution of these instabilities is explored to confirm the predictions from the linear theory and, also, to illustrate how stabilization is directly related to fluid transport across the shelf.
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Kalishchuk, Oksana, and Lyudmyla Strilchuk. "The Main Directions of Historical and Topographic Research of Ukrainian Cities." Історико-політичні проблеми сучасного світу, no. 44 (December 15, 2021): 91–104. http://dx.doi.org/10.31861/mhpi2021.44.91-104.
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The article analyzes the main directions and problems of historical and topographic research of Ukrainian cities of the Middle Ages and early modern times. One of the important areas of historical research is the study of the historical topography of settlements at different stages of their evolution. A necessary condition for such research is the study of the historical topography of settlements at different stages of development. Quite often the reason for insufficient study of the historical and topographic dominants of the medieval city is the limited number of narrative evidence on the history of the city, among which there is no detailed topographic description. In this case, of course, the integrated use of verbal, cartographic and archaeological sources becomes especially important. Only the combination of data of toponymy, historical topography with archaeological and written sources, their mutual verification and addition can give interesting scientific results. Without the data of historical topography, the study of spatial history, historical urbanism is inconceivable, it is the basis of sociotopography. The study of the topography of the medieval city includes a number of problematic issues: time and sequence of foundations of different parts of the city and lost buildings, toponymy and its changes, the degree of authenticity of chronicles and other written sources, archaeological material, city boundaries, roads, etc. Attention to the problems of the historical topography of Ukrainian cities in different periods is due to the need to develop and comprehensively reproduce the characteristics of urban development. Consideration of various aspects of the historical topography of medieval and early modern cities of Ukraine allows us to trace the dynamics of powerful urban centers in time and space. However, today, many historical cities of Ukraine have not become the object of comprehensive scientific research. Among other areas of historical topography studies, the creation of virtual models of urban fortifications in 3d format with reference to the Global Position System has recently become relevant. After all, the latest technology allows you to see deeper and solve those scientific problems, the formulation of which until recently looked fantastic.
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Barthel, Alice, Andrew McC. Hogg, Stephanie Waterman, and Shane Keating. "Jet–Topography Interactions Affect Energy Pathways to the Deep Southern Ocean." Journal of Physical Oceanography 47, no. 7 (July 2017): 1799–816. http://dx.doi.org/10.1175/jpo-d-16-0220.1.
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AbstractIn the Southern Ocean, strong eastward ocean jets interact with large topographic features, generating eddies that feed back onto the mean flow. Deep-reaching eddies interact with topography, where turbulent dissipation and generation of internal lee waves play an important role in the ocean’s energy budget. However, eddy effects in the deep ocean are difficult to observe and poorly characterized. This study investigates the energy contained in eddies at depth, when an ocean jet encounters topography. This study uses a two-layer ocean model in which an imposed unstable jet encounters a topographic obstacle (either a seamount or a meridional ridge) in a configuration relevant to an Antarctic Circumpolar Current frontal jet. The authors find that the presence of topography increases the eddy kinetic energy (EKE) at depth but that the dominant processes generating this deep EKE depend on the shape and height of the obstacle as well as on the baroclinicity of the jet before it encounters topography. In cases with high topography, horizontal shear instability is the dominant source of deep EKE, while a flat bottom or a strongly sheared inflow leads to deep EKE being generated primarily through baroclinic instability. These results suggest that the deep EKE is set by an interplay between the inflowing jet properties and topography and imply that the response of deep EKE to changes in the Southern Ocean circulation is likely to vary across locations depending on the topography characteristics.
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Ardi, Dennise Tanoko, Yue Gang Li, Kelvin Hau Kong Chan, Liam Blunt, and M. R. Bache. "The Role of Surface Topography on Fatigue Behaviour of Nickel Based Superalloys." Advanced Materials Research 891-892 (March 2014): 48–53. http://dx.doi.org/10.4028/www.scientific.net/amr.891-892.48.
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Advanced areal (three-dimensional) characterisation of surface topography was applied to laboratory scale fatigue test specimens manufactured from the nickel based superalloy Alloy720Li. Finishing was deliberately manipulated to offer four distinct grades of topography. Subsequent low cycle fatigue performance was then correlated to a range of parameters selected to represent the surface topography. The aim of the ongoing study is to predict fatigue performance and aid to establish correlations between topographic parameters and fatigue life.
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Scott, Chelsea Phipps, Matthew Beckley, Minh Phan, Emily Zawacki, Christopher Crosby, Viswanath Nandigam, and Ramon Arrowsmith. "Statewide USGS 3DEP Lidar Topographic Differencing Applied to Indiana, USA." Remote Sensing 14, no. 4 (February 11, 2022): 847. http://dx.doi.org/10.3390/rs14040847.
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Differencing multi-temporal topographic data (radar, lidar, or photogrammetrically derived point clouds or digital elevation models—DEMs) measures landscape change, with broad applications for scientific research, hazard management, industry, and urban planning. The United States Geological Survey’s 3D Elevation Program (3DEP) is an ambitious effort to collect light detection and ranging (lidar) topography over the United States’ lower 48 and Interferometric Synthetic Aperture Radar (IfSAR) in Alaska by 2023. The datasets collected through this program present an important opportunity to characterize topography and topographic change at regional and national scales. We present Indiana statewide topographic differencing results produced from the 2011–2013 and 2016–2020 lidar collections. We discuss the insights, challenges, and lessons learned from conducting large-scale differencing. Challenges include: (1) designing and implementing an automated differencing workflow over 94,000 km2 of high-resolution topography data, (2) ensuring sufficient computing resources, and (3) managing the analysis and visualization of the multiple terabytes of data. We highlight observations including infrastructure development, vegetation growth, and landscape change driven by agricultural practices, fluvial processes, and natural resource extraction. With 3DEP and the U.S. Interagency Elevation Inventory data, at least 37% of the Contiguous 48 U.S. states are already covered by repeat, openly available, high-resolution topography datasets, making topographic differencing possible.
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Dauphin-Ducharme, Philippe, W. Jeffrey Binns, Michael E. Snowden, David W. Shoesmith, and Janine Mauzeroll. "Determination of the local corrosion rate of magnesium alloys using a shear force mounted scanning microcapillary method." Faraday Discussions 180 (2015): 331–45. http://dx.doi.org/10.1039/c4fd00276h.
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The successful development of scanning probe techniques to characterize corrosion in situ using multifunctional probes is intrinsically tied to surface topography signal decoupling from the measured electrochemical fluxes. One viable strategy is the shear force controlled scanning microcapillary method. Using this method, pulled quartz micropipettes with an aperture of 500 nm diameter were used to resolve small and large variations in topography in order to quantify the local corrosion rate of microgalvanically and galvanically corroded Mg alloys. To achieve topography monitoring of corroded surfaces, shear force feedback was employed to position the micropipette at a reproducible working height above the substrate. We present proof of concept measurements over a galvanic couple of a magnesium alloy (AE44) and mild steel along with a microgalvanically corroded ZEK100 Mg alloy, which illustrates the ability of shear force to track small (1.4 μm) and large (700 μm) topographic variations from high aspect ratio features. Furthermore, we demonstrate the robustness of the technique by acquiring topographic data for 4 mm along the magnesium–steel galvanic couple sample and a 250 × 30 μm topography map over the ZEK100 Mg alloy. All topography results were benchmarked using standard optical microscopies (profilometry and confocal laser scanning microscopy).
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Fewster, P. F., and N. L. Andrew. "Interpretation of the diffuse scattering close to Bragg peaks by X-ray topography." Journal of Applied Crystallography 26, no. 6 (December 1, 1993): 812–19. http://dx.doi.org/10.1107/s0021889893006259.
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Perturbations from crystal perfection will result in diffuse X-ray scattering, which can be imaged by topography to yield defect information without the swamping contribution of perfect-crystal scattering. This paper illustrates the importance of the probe shape for obtaining topographic images in this diffuse region not only to aid interpretation but to isolate the contributors to this scattering. The diffuse scattering in the vicinity of the Bragg peaks of GaAs, Si and Ge substrate crystals has been mapped to very high resolution and the diffuse scattering has been imaged by topography. It was found that the majority of the scattering emanates from surface damage and dislocations and not point defects or thermal diffuse scattering (TDS). These latter two components are found to be second-order effects in general and are only just discernable as a very weak background intensity in highly perfect crystals. This topography method is very sensitive to surface damage. This is because the associated diffuse scattering close to a Bragg peak can be used to form an image. Therefore, this relatively intense scattering provides a topograph within a few hours for assessing substrate-surface quality. The sensitivity of the method is illustrated with images of surface defects and dislocations in very perfect semiconductors. A procedure for measuring the diffuse scattering emanating from microdefects is also presented.
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Yamaguchi, Hirotaka, and Hirofumi Matsuhata. "Threading Dislocations in 4H-SiC Observed by Double-Crystal X-Ray Topography." Materials Science Forum 725 (July 2012): 7–10. http://dx.doi.org/10.4028/www.scientific.net/msf.725.7.
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Threading dislocations in 4H-SiC wafer were observed by using a double crystal X-ray topography technique. The incident beam was collimated by the first crystal so that the angular divergence was reduced to sufficiently smaller than the rocking curve of a diffraction of the specimen (the second crystal). At off-Bragg angles, cross-sectional projection of threading dislocations appeared on the topographic images. From these results, we found that outcrops of the screw dislocation at the wafer surfaces suffered from significant strain, giving strong contrast on the topograph even under the condition, $\vec{g}\cdot\vec{b}=0$. In addition, the edge and screw components in the mixed dislocations were clearly distinguished.
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Ibrahim, O., S. Bogan, and G. O. Waring. "Patterns of Corneal Topography after Penetrating Keratoplasty." European Journal of Ophthalmology 6, no. 1 (January 1996): 1–5. http://dx.doi.org/10.1177/112067219600600101.
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Background The topography of corneas after penetrating keratoplasty is highly variable. We classify the topography into five groups. Methods We performed videokeratography on 45 clear compact penetrating keratoplasties, with all sutures removed. Three ophthalmologists classified the keratographs independently into five previously defined topographic groups, based on the pattern of the normalized color-coded videokeratograph. Results The five topographic patterns included: prolate bow tie, 14 (30%); oblate bow tie, 14 (30%); mixed prolate and oblate bow tie, 8 (17%); asymmetric, 3 (9%); and steep/flat, 6 (14%). The three ophthalmologists agreed in their initial classification in 87% of the cases and after discussion, in 96%. Conclusion The topography of the cornea after penetrating keratoplasty can be classified into five qualitative groups by trained observers, with good clinical reliability.
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Maurer, K., T. Dierks, and R. Rupprecht. "Computerized electroencephalographic topography (CET) during sleep: Topographic hypnograms." Psychiatry Research 29, no. 3 (September 1989): 435–38. http://dx.doi.org/10.1016/0165-1781(89)90115-7.
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Liang, Zhong Wei, Chun Liang Zhang, Yi Jun Wang, and Yi Dan Hu. "Positioning of Characteristic Points in IC Chip’s Micro-Topography Based on Cross Correlation Matching and Image Projection Transformation." Advanced Materials Research 139-141 (October 2010): 1996–2001. http://dx.doi.org/10.4028/www.scientific.net/amr.139-141.1996.
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In accurate optical inspection of IC chip, it is necessary to recognize and calibrate the IC micro-topography completely and accurately. Positioning method of characteristic points in IC chip’s micro-topography based on cross correlation matching and image projection transformation is investigated to realize high precision detection of surface topography. On the basis of extracting wavelet high-frequency components of IC topography conjugate images which is shot by high- definition CCD cameras from different space positions, the coordinate information of some selected topography’s characteristic points is shown. Cross correlation matching is applied to definite the characteristic point’s relative positions in the projected images, then relationship of image projection transformation is established for calculating and determining the characteristic point’s absolute coordinates, which facilitates following topography detection of IC chip. Experiment analysis and data comparison indicate that accurate coordinate positioning results of characteristic points can be obtained by this method, the research basis for following IC topography model structuring and micro- flaw characteristic detecting can also be provided.
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Gong, Ming-Hao, and Yan-Ling Song. "Topographic habitat features preferred by the Endangered giant panda Ailuropoda melanoleuca: implications for reserve design and management." Oryx 45, no. 2 (April 2011): 252–57. http://dx.doi.org/10.1017/s0030605310001043.
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AbstractThe effect of landscape on populations is of great importance, especially given the number of species inhabiting patchy landscapes. Developments in geographical information systems are facilitating a greater application of spatial analyses to threatened species, such as the Endangered giant panda Ailuropoda melanoleuca, for which habitat patchiness and quality are key limiting factors. Of all factors that influence the suitability of habitat for the giant panda, topography is not subject to change. Here, we report a spatial and statistical analysis of the high quality topographic habitat preferred by the giant panda across its stronghold in the Qinling Mountains, China. High quality topographic habitat, as indicated by a combination of elevation, slope and aspect, covers 92,788 ha, accounting for 15% of the current range of the species. The distribution of the giant panda closely follows patterns of topography and areas with patches of high quality topographic habitat are strongly associated with areas supporting greater numbers of giant pandas. However, comparisons between our model and the existing reserve system reveals a number of inadequacies. Some of the reserves contain little high quality topographic habitat and many patches of high quality topographic habitat are unprotected. Given the importance of topography and the decisive role it plays in shaping habitat, landscapes containing high quality topographic features must be a critical consideration in the design of reserves for the giant panda. The existing system of nature reserves is heavily weighted towards judicial and administrative boundaries, to the detriment of other factors such as topography.
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Yang, Junjun, Zhicai Luo, Liangcheng Tu, Shanshan Li, Jingxue Guo, and Diao Fan. "On the Feasibility of Seafloor Topography Estimation from Airborne Gravity Gradients: Performance Analysis Using Real Data." Remote Sensing 12, no. 24 (December 15, 2020): 4092. http://dx.doi.org/10.3390/rs12244092.
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Compared with airborne gravimetry, a technique frequently used to infer the seafloor topography at places inaccessible to ship soundings due to the presence of ice shelf or ice mélange, airborne gravity gradiometry inherently could achieve higher spatial resolution, thus it is promising for improved inference of seafloor topography. However, its estimation capability has not been demonstrated by real projects. Theoretical analysis through admittance shows that compared with gravity disturbance, gravity gradient is more sensitive to the short-wavelength seafloor topography but diminishes faster with the increase of the distance between the seafloor and airplane, indicating its superiority is recovering short-wavelength topographic features over shallow waters. We present the first numerical experiment that estimates seafloor topography from a 0.4-km resolution, real airborne gravity gradients. It is shown that airborne gravity gradiometry can recover smaller topographic features than typical airborne gravimetry, but the estimation accuracy is only ±17 m due to the presence of subsurface density variations. The long-wavelength effect of the subsurface density variations can be removed with the aid of constraining bathymetry inside the study area, whereas the short wavelengths cannot. This study expands the applications of airborne gravity gradiometry, and helps glaciologists understand its performance in seafloor topography estimation.
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Pegler, Samuel S., Herbert E. Huppert, and Jerome A. Neufeld. "Topographic controls on gravity currents in porous media." Journal of Fluid Mechanics 734 (October 9, 2013): 317–37. http://dx.doi.org/10.1017/jfm.2013.466.
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AbstractWe present a theoretical and experimental study of the propagation of gravity currents in porous media with variations in the topography over which they flow, motivated in part by the sequestration of carbon dioxide in saline aquifers. We consider cases where the height of the topography slopes upwards in the direction of the flow and is proportional to the $n\text{th} $ power of the horizontal distance from a line or point source of a constant volumetric flux. In two-dimensional cases with $n\gt 1/ 2$, the current evolves from a self-similar form at early times, when the effects of variations in topography are negligible, towards a late-time regime that has an approximately horizontal upper surface and whose evolution is dictated entirely by the geometry of the topography. For $n\lt 1/ 2$, the transition between these flow regimes is reversed. We compare our theoretical results in the case $n= 1$ with data from a series of laboratory experiments in which viscous glycerine is injected into an inclined Hele-Shaw cell, obtaining good agreement between the theoretical results and the experimental data. In the case of axisymmetric topography, all topographic exponents $n\gt 0$ result in a transition from an early-time similarity solution towards a topographically controlled regime that has an approximately horizontal free surface. We also analyse the evolution over topography that can vary with different curvatures and topographic exponents between the two horizontal dimensions, finding that the flow transitions towards a horizontally topped regime at a rate which depends strongly on the ratio of the curvatures along the principle axes. Finally, we apply our mathematical solutions to the geophysical setting at the Sleipner field, concluding that topographic influence is unlikely to explain the observed non-axisymmetric flow.
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Kennedy, Rebecca S. H., and Thomas A. Spies. "An assessment of dead wood patterns and their relationships with biophysical characteristics in two landscapes with different disturbance histories in coastal Oregon, USA." Canadian Journal of Forest Research 37, no. 5 (May 2007): 940–56. http://dx.doi.org/10.1139/x06-298.
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Understanding the relative importance of landscape history, topography, vegetation, and climate to dead wood patterns is important for assessing pattern–process relationships related to dead wood and associated biodiversity. We sampled dead wood at four topographic positions in two landscapes (1400–2100 km2) that experienced different wildfire and salvage histories in coastal Oregon. Study objectives were to (i) determine whether and how the landscapes differed in dead wood amounts and characteristics and (ii) evaluate relationships between dead wood characteristics and potentially related biophysical variables associated with historical and current vegetation, topography, climate, soils, and ecoregion. Despite differences in history, the two landscapes differed little in total dead wood volume; however, they differed in dead wood volume by structural type, decay class, and source (legacy/nonlegacy). Dead wood varied by topographic position, and topography was of greatest importance compared with other factors. In this mountainous region, upper topographic positions may be source areas for dead wood and riparian areas and streams sinks for dead wood. Climate explained more variance in dead wood in the landscape that burned earlier and was not salvaged. Landscape-scale patterns of dead wood are evident in landscapes with different disturbance histories and despite finer-scale variation in topography, vegetation, and other biophysical attributes.
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Huang, X. R., M. Dudley, W. M. Vetter, W. Huang, W. Si, and C. H. Carter Jr. "Superscrew dislocation contrast on synchrotron white-beam topographs: an accurate description of the direct dislocation image." Journal of Applied Crystallography 32, no. 3 (June 1, 1999): 516–24. http://dx.doi.org/10.1107/s0021889899002939.
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A kinematic (geometrical) diffraction simulation model has been developed to provide understanding of direct dislocation images on synchrotron white-beam X-ray topographs, and has been successfully applied to illustrate the contrast formation mechanisms involved in images of micropipe-related superscrew dislocations in silicon carbide crystals. The coincidence of the simulations with the contrast features of the superscrew dislocation images, recorded using a series of synchrotron topography techniques, shows that this model is capable of revealing the detailed diffraction behavior of the highly distorted region around the dislocation core and determining the quantitative characteristics of the dislocations. The simulation technique is thus demonstrated to be a simple but efficient method for interpretation of synchrotron topographs, and may be applied to explain the topographic contrast characters of general crystal defects.
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Mauro, Luisetto. "Topography in Cancer Science." Cancer Research and Cellular Therapeutics 3, no. 2 (November 19, 2019): 01–02. http://dx.doi.org/10.31579/2640-1053/061.
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Chiba, Susumu, and Takashi Noda. "Factors maintaining topography-related mosaic of barnacle and mussel on a rocky shore." Journal of the Marine Biological Association of the United Kingdom 80, no. 4 (August 2000): 617–22. http://dx.doi.org/10.1017/s0025315400002435.
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Substratum heterogeneity on rocky shores can affect the distribution pattern of sessile epibenthic organisms. The rocky shore at Usujiri, southern Hokkaido, Japan, is composed of well-developed, columnar jointed dolerites. In this area, landscape is characterized by a mosaic of barnacle and mussels, where species composition in patches differs among typical topographic-classes, i.e. barnacles dominate on horizontal planes and vertical planes while mussels only inhabit in grooves. To determine the factors maintaining those distribution patterns, the recruitment of dominant sessile species in the typical topographic-classes with and without adults of barnacles and mussels were examined by field experiment. The results showed that the distribution pattern was determined by recruitment, and the recruitment pattern was strongly affected by rock-surface topography. Moreover, the presence of conspecific adults contributed to the maintenance of this topography-related mosaic by facilitating recruitment. These results show: (1) the presence of resource division for rocky topography among barnacles and mussels; and (2) that intraspecific positive interaction rather than interspecific competition may play important role in maintaining the topography-related mosaic of barnacle and mussels at Usujiri.
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Nigamadyanov, N. R., M. B. Tsykunov, G. E. Ivanova, and V. I. Lukyanov. "Analisis of posture in school-age children according to optical topography." N.N. Priorov Journal of Traumatology and Orthopedics 26, no. 4 (December 15, 2019): 43–45. http://dx.doi.org/10.17116/vto201904143.
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Purpose of study: the study of posture in school children in three planes according to computer optical topography. Patients and methods. A screening examination of 1835 children was performed using computer optical topography of the back, the average age was 11.2±1.7 years, girls 930 (50.6%), boys 905 (49.3%). Results and conclusion. The study showed that computer optical topography is a highly effective method for screening diagnostics of posture disorders in school children, posture disorders are a common condition, according to the topographic classification of posture disorders, occur in 69.46% of school age children.
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Zhang, Yu, Joseph Pedlosky, and Glenn R. Flierl. "Shelf Circulation and Cross-Shelf Transport out of a Bay Driven by Eddies from an Open-Ocean Current. Part I: Interaction between a Barotropic Vortex and a Steplike Topography." Journal of Physical Oceanography 41, no. 5 (May 1, 2011): 889–910. http://dx.doi.org/10.1175/2010jpo4496.1.
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Abstract This paper examines interaction between a barotropic point vortex and a steplike topography with a bay-shaped shelf. The interaction is governed by two mechanisms: propagation of topographic Rossby waves and advection by the forcing vortex. Topographic waves are supported by the potential vorticity (PV) jump across the topography and propagate along the step only in one direction, having higher PV on the right. Near one side boundary of the bay, which is in the wave propagation direction and has a narrow shelf, waves are blocked by the boundary, inducing strong out-of-bay transport in the form of detached crests. The wave–boundary interaction as well as out-of-bay transport is strengthened as the minimum shelf width is decreased. The two control mechanisms are related differently in anticyclone- and cyclone-induced interactions. In anticyclone-induced interactions, the PV front deformations are moved in opposite directions by the point vortex and topographic waves; a topographic cyclone forms out of the balance between the two opposing mechanisms and is advected by the forcing vortex into the deep ocean. In cyclone-induced interactions, the PV front deformations are moved in the same direction by the two mechanisms; a topographic cyclone forms out of the wave–boundary interaction but is confined to the coast. Therefore, anticyclonic vortices are more capable of driving water off the topography. The anticyclone-induced transport is enhanced for smaller vortex–step distance or smaller topography when the vortex advection is relatively strong compared to the wave propagation mechanism.
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Kulynych, Jessica. "Topography." River Teeth: A Journal of Nonfiction Narrative 24, no. 1 (September 2022): 11–28. http://dx.doi.org/10.1353/rvt.2022.0016.
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Merryfield, William J., and Greg Holloway. "Inviscid quasi-geostrophic flow over topography: testing statistical mechanical theory." Journal of Fluid Mechanics 309 (February 25, 1996): 85–91. http://dx.doi.org/10.1017/s0022112096001565.
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Numerical simulations are employed in a detailed test of the statistical mechanical description of topographic turbulence. Predictions of steady flows correlated with topography are given particular attention. Agreement between numerical and statistical mechanical results is demonstrated for a large range of parameter values, and over an ensemble of random choices of topography and initial conditions.
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Steigmeier, E. F., and H. Auderset. "Light scattering topography and photoluminescence topography." Applied Physics A Solids and Surfaces 50, no. 6 (June 1990): 531–40. http://dx.doi.org/10.1007/bf00323444.
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Xu, Guo Dong, Zheng Hua Zhou, Jing Shan Bo, and Wei Hua Fang. "Effect of Ridge Topography on Earthquake Ground Motion." Advanced Materials Research 594-597 (November 2012): 1696–701. http://dx.doi.org/10.4028/www.scientific.net/amr.594-597.1696.
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The ridge topography can substantially influence seismic ground motion and, in general, causes the amplification of seismic ground motion amplitude at ridges. Fortunately, sets of three-component accelerogram, obtained by the observation arrays for topographic effect at Zigong Xishan, Jiangyou Doutuan and Qingchuan Sanguo from the great Wenchuan earthquake and its aftershocks, provided basic data for analyzing the effect of ridge topography on seismic ground motion. On the base of these acceleration records, peak ground acceleration and response spectrum ratios are calculated, and examined and compared in order to grasp the effect of ridge topography on ground motion. The findings showed that ridge topography has the remarkable effect on seismic ground motion, in which the amplification characteristics varies depending on the shape of ridge topography, and the amplification effect of the horizontal directions are not similar to the vertical direction, and in some periods are even less than 1.0.
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Petty, A. A., M. C. Tsamados, N. T. Kurtz, S. L. Farrell, T. Newman, J. P. Harbeck, D. L. Feltham, and J. A. Richter-Menge. "Characterizing Arctic sea ice topography using high-resolution IceBridge data." Cryosphere Discussions 9, no. 6 (November 24, 2015): 6495–543. http://dx.doi.org/10.5194/tcd-9-6495-2015.
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Abstract. We present an analysis of Arctic sea ice topography using high resolution, three-dimensional, surface elevation data from the Airborne Topographic Mapper, flown as part of NASA's Operation IceBridge mission. Surface features in the sea ice cover are detected using a newly developed surface feature picking algorithm. We derive information regarding the height, volume and geometry of surface features from 2009–2014 within the Beaufort/Chukchi and Central Arctic regions. The results are delineated by ice type to estimate the topographic variability across first-year and multi-year ice regimes. The results demonstrate that Arctic sea ice topography exhibits significant spatial variability, mainly driven by the increased surface feature height and volume (per unit area) of the multi-year ice that dominates the Central Arctic region. The multi-year ice topography exhibits greater interannual variability compared to the first-year ice regimes, which dominates the total ice topography variability across both regions. The ice topography also shows a clear coastal dependency, with the feature height and volume increasing as a function of proximity to the nearest coastline, especially north of Greenland and the Canadian Archipelago. A strong correlation between ice topography and ice thickness (from the IceBridge sea ice product) is found, using a square-root relationship. The results allude to the importance of ice deformation variability in the total sea ice mass balance, and provide crucial information regarding the tail of the ice thickness distribution across the western Arctic. Future research priorities associated with this new dataset are presented and discussed, especially in relation to calculations of atmospheric form drag.
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Lee, Jinsun, Md Shahjahan Hossain, Mohammad Taheri, Awse Jameel, Manas Lakshmipathy, and Hossein Taheri. "Characterization of Surface Topography Features for the Effect of Process Parameters and Their Correlation to Quality Monitoring in Metal Additive Manufacturing." Metrology 2, no. 1 (February 7, 2022): 73–83. http://dx.doi.org/10.3390/metrology2010005.
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Layering deposition methodology in metal additive manufacturing (AM) and the influence of different processing parameters, such as energy source level and deposition speed, which can change the melt pool condition, are known to be the important influencing factors on properties of components fabricated via AM. The effect of melt pool conditions and geometry on properties and quality of fabricated AM components has been widely studied through experimental and simulation techniques. There is a need for better understanding the influence of solidified melt pool topography on characteristics of next deposition layer that can be applied to complex surfaces, especially those with sparse topographical features, such as those that occur in AM deposition layers. Topography of deposited layers in metal additive manufacturing is a significant aspect on the bonding condition between the layers and defect generation mechanism. Characterization of the topography features in AM deposition layers offers a new perspective into investigation of defect generation mechanisms and quality evaluation of AM components. In this work, a feature-based topography study is proposed for the assessment of process parameters’ influence on AM deposition layers topography and defect generation mechanism. Titanium alloy (Ti6Al4V) samples deposited on steel substrate, by direct energy deposition (DED) AM technique at different process conditions, were used for the assessment. Topography datasets and analysis of shape and size differences pertaining to the relevant topographic features have been performed. Different AM process parameters were investigated on metallic AM samples manufactured via direct energy deposition (DED) and the potential defect generation mechanism was discussed. The assessment of the topography features was used for correlation study with previously published in-situ monitoring and quality evaluation results, where useful information was obtained through characterization of signature topographic formations and their relation to the in-situ acoustic process monitoring, as the indicators of the manufacturing process behavior and performance.
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Wang, Xin, and Shibiao Bai. "Indicative Effect of Excess Topography on Potential Risk Location of Giant Ancient Landslides—A Case Study in Lengqu River Section." Applied Sciences 13, no. 14 (July 11, 2023): 8085. http://dx.doi.org/10.3390/app13148085.
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In order to identify giant ancient landslides more effectively and to quantify the risk of giant ancient landslides, this study takes a Lengqu River section located on the Qinghai–Tibet Plateau as an example and then uses the red relief image map (RRIM) method to enhance the digital elevation model (DEM) for topographic 2D visualization to identify giant ancient landslides. Then, the relationships between giant ancient landslides (GALs), resurgent GALs, the deposition of inactive GALs and the excess topography of hillslopes under 30° threshold are analyzed separately. A total of 54 GALs are identified at last by using the RRIM method; 77.75% of GALs are still located on excess topography, 68.38% of resurgent GALs occurred on excess topography, and 62.21% of the deposition of inactive GALs are on non-excess topography. The RRIM method provides a new way to identify giant ancient landslides. The excess topography provides an indication of the risk of new landslides through the destructive effect of GALs on the threshold hillslope, and the preliminary investigation of the quantitative relationship between the resurrection of GALs and excess topography also shows that there is a certain pattern between the resurrection of GALs and the excess topography under the natural state, so the excess topography has a certain indication of the generation of new landslides and secondary resurrection at the original GAL positions.
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Owen, Caroline M., John Patterson, and Richard B. Silberstein. "Olfactory Modulation of Steady- State Visual Evoked Potential Topography in Comparison with Differences in Odor Sensitivity." Journal of Psychophysiology 16, no. 2 (January 2002): 71–81. http://dx.doi.org/10.1027//0269-8803.16.2.71.
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Summary Research was undertaken to determine whether olfactory stimulation can alter steady-state visual evoked potential (SSVEP) topography. Odor-air and air-only stimuli were used to determine whether the SSVEP would be altered when odor was present. Comparisons were also made of the topographic activation associated with air and odor stimulation, with the view toward determining whether the revealed topographic activity would differentiate levels of olfactory sensitivity by clearly identifying supra- and subthreshold odor responses. Using a continuous respiration olfactometer (CRO) to precisely deliver an odor or air stimulus synchronously with the natural respiration, air or odor (n-butanol) was randomly delivered into the inspiratory airstream during the simultaneous recording of SSVEPs and subjective behavioral responses. Subjects were placed in groups based on subjective odor detection response: “yes” and “no” detection groups. In comparison to air, SSVEP topography revealed cortical changes in response to odor stimulation for both response groups, with topographic changes evident for those unable to perceive the odor, showing the presence of a subconscious physiological odor detection response. Differences in regional SSVEP topography were shown for those who reported smelling the odor compared with those who remained unaware of the odor. These changes revealed olfactory modulation of SSVEP topography related to odor awareness and sensitivity and therefore odor concentration relative to thresholds.
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Nuber, André, Edgar Manukyan, and Hansruedi Maurer. "Ground topography effects on near-surface elastic full waveform inversion." Geophysical Journal International 207, no. 1 (July 20, 2016): 67–71. http://dx.doi.org/10.1093/gji/ggw267.
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Abstract The effects of neglecting ground surface topography variations in elastic full waveform inversion are investigated using two classes of synthetic example. The models include various high-contrast velocity and density anomalies, as they are often observed in near-surface applications. The first type of example shows that failing to account for even small amplitude fluctuations in topography introduces velocity artefacts in the near-surface part of the tomogram as well as degrades significantly the spatial resolution of features at greater depths. The disturbances are particularly severe when the topographic fluctuations have wavelengths comparable to the minimum seismic wavelength. The second type of synthetic example considers long wavelength topography variations of various amplitudes. It is found that neglecting topography with an amplitude fluctuation greater than half the minimum seismic wavelength leads to appreciable inversion image artefacts. Therefore, the incorporation of surface topography, even if it appears minor, is essential for successful elastic full waveform inversion of land seismic data.