Topographic Details Research Articles

Surface integrity in tangential turning of hybrid MMC A359/B4C/Al2O3 by abrasive waterjet

This paper deals with the abrasive waterjet turning of newly developed hybrid MMC A359/B4C/Al2O3 produced by electromagnetic stir casting. The justification of the fabrication was revealed by microstructural images and x-ray diffraction results. The main aim of the study is to analyse the machining behaviour of produced hybrid MMC under abrasive waterjet turning. The surfaces created at different traverse speed were discussed in terms of surface integrity and surface texture. Optical profilometer was used to generate surface roughness report and 3D visualization of the machined surface. Olympus LEXT OLS 3100 laser confocal microscope was used to collect 2D and 3D surface topographical details of the machined surface. Surface morphology was discussed by FE-SEM images to evaluate surface defects. Residual stresses and microhardness test through the depth profile were also carried out to analyse the machined surface and subsurface. It has been found a perfectly round, slightly undulated surface which shows ploughing nature. The results also reveal the higher rate of material removal with rough cutting.

Anti-spoof touchless 3D fingerprint recognition system using single shot fringe projection and biospeckle analysis

Fingerprint is a unique, un-alterable and easily collected biometric of a human being. Although it is a 3D biological characteristic, traditional methods are designed to provide only a 2D image. This touch based mapping of 3D shape to 2D image losses information and leads to nonlinear distortions. Moreover, as only topographic details are captured, conventional systems are potentially vulnerable to spoofing materials (e.g. artificial fingers, dead fingers, false prints, etc.). In this work, we demonstrate an anti-spoof touchless 3D fingerprint detection system using a combination of single shot fringe projection and biospeckle analysis. For fingerprint detection using fringe projection, light from a low power LED source illuminates a finger through a sinusoidal grating. The fringe pattern modulated because of features on the fingertip is captured using a CCD camera. Fourier transform method based frequency filtering is used for the reconstruction of 3D fingerprint from the captured fringe pattern. In the next step, for spoof detection using biospeckle analysis a visuo-numeric algorithm based on modified structural function and non-normalized histogram is proposed. High activity biospeckle patterns are generated because of interaction of collimated laser light with internal fluid flow of the real finger sample. This activity reduces abruptly in case of layered fake prints, and is almost absent in dead or fake fingers. Furthermore, the proposed setup is fast, low-cost, involves non-mechanical scanning and is highly stable.

Density interface topography recovered by inversion of satellite gravity gradiometry observations

A radial integration of spherical mass elements (i.e. tesseroids) is presented for evaluating the six components of the second-order gravity gradient (i.e. second derivatives of the Newtonian mass integral for the gravitational potential) created by an uneven spherical topography consisting of juxtaposed vertical prisms. The method uses Legendre polynomial series and takes elastic compensation of the topography by the Earth’s surface into account. The speed of computation of the polynomial series increases logically with the observing altitude from the source of anomaly. Such a forward modelling can be easily applied for reduction of observed gravity gradient anomalies by the effects of any spherical interface of density. An iterative least-squares inversion of measured gravity gradient coefficients is also proposed to estimate a regional set of juxtaposed topographic heights. Several tests of recovery have been made by considering simulated gradients created by idealistic conical and irregular Great Meteor seamount topographies, and for varying satellite altitudes and testing different levels of uncertainty. In the case of gravity gradients measured at a GOCE-type altitude of \(\sim \)300 km, the search converges down to a stable but smooth topography after 10–15 iterations, while the final root-mean-square error is \(\sim \)100 m that represents only 2 % of the seamount amplitude. This recovery error decreases with the altitude of the gravity gradient observations by revealing more topographic details in the region of survey.

SWAT Modeling for Depression-Dominated Areas: How Do Depressions Manipulate Hydrologic Modeling?

Modeling hydrologic processes for depression-dominated areas such as the North American Prairie Pothole Region is complex and reliant on a clear understanding of dynamic filling-spilling-merging-splitting processes of numerous depressions over the surface. Puddles are spatially distributed over a watershed and their sizes, storages, and interactions vary over time. However, most hydrologic models fail to account for these dynamic processes. Like other traditional methods, depressions are filled as a required preprocessing step in the Soil and Water Assessment Tool (SWAT). The objective of this study was to facilitate hydrologic modeling for depression-dominated areas by coupling SWAT with a Puddle Delineation (PD) algorithm. In the coupled PD-SWAT model, the PD algorithm was utilized to quantify topographic details, including the characteristics, distribution, and hierarchical relationships of depressions, which were incorporated into SWAT at the hydrologic response unit (HRU) scale. The new PD-SWAT model was tested for a large watershed in North Dakota under real precipitation events. In addition, hydrologic modeling of a small watershed was conducted under two extreme high and low synthetic precipitation conditions. In particular, the PD-SWAT was compared against the regular SWAT based on depressionless DEMs. The impact of depressions on the hydrologic modeling of the large and small watersheds was evaluated. The simulation results for the large watershed indicated that SWAT systematically overestimated the outlet discharge, which can be attributed to the failure to account for the hydrologic effects of depressions. It was found from the PD-SWAT modeling results that at the HRU scale surface runoff initiation was significantly delayed due to the threshold control of depressions. Under the high precipitation scenario, depressions increased the surface runoff peak. However, the low precipitation scenario could not fully fill depressions to reach the overflow thresholds in the selected sub-basins. These results suggest the importance of depressions as gatekeepers in watershed modeling.

Delineation of River Watershed and Stream Network Using ILWIS 3.7.1 Academic

The delineation of watersheds can be carried out manually using topographic maps but these maps are mostly outdated and scarce for most parts of Nigeria and may be of different scales for large watersheds that require several sheets of the map. Watershed boundaries need to be delineated accurately because the areas and perimeters of watersheds are used in many hydrological analyses. This study is aimed at delineating the River Dep watershed and stream network using remote sensing and GIS technologies and comparing the shape and pattern with the one previously delineated manually using topographic maps and areal photographs. The 90m SRTM Digital Elevation Model used for the study was obtained from the Global Land Facility Cover site and processed in ERDAS Imagine 9.2 before exporting to ILWIS 3.7.1 ACADEMIC. The watershed area obtained from the GIS delineation processes was 10640km while it was 9600km from the report of the one delineated by manual methods in 1980. The same 1980 manually delineated watershed when scanned, imported, georeferenced and digitised in ILWIS 3.7.1 gave a watershed area of 10244km. The differences in the watershed area could be due to the effect of input data or inability of some topographic details to be captured for the estimation using traditional delineation. The study showed similarity in shape and pattern however for both watersheds and stream networks delineated using the two methods. The study shows the capability of the ILWIS DEM hydro-processing tools for watershed and stream network delineation and recommends its use.

Topography of selectively laser melted surfaces: A comparison of different measurement methods

Selective laser melting (SLM) of metals produces surface topographies that are challenging to measure. Multiple areal surface topography measurement technologies are available, which allow reconstruction of information rich, three-dimensional digital surface models. However, the capability of such technologies to capture intricate topographic details of SLM parts has not yet been investigated. This work explores the topography of a SLM Ti6Al4V part, as reconstructed from measurements by various optical and non-optical technologies. Discrepancies in the reconstruction of local topographic features are investigated through alignment and quantitative assessment of local differences. ISO 25178-2 areal texture parameters are computed as further comparison indicators.

Complexity of the Class B Phenotype in Autosomal Dominant Retinitis Pigmentosa Due to Rhodopsin Mutations.

PurposePreviously, patients with RHO mutations and a class A phenotype were found to have severe early-onset loss of rod function, whereas patients with a class B phenotype retained rod function at least in certain retinal regions. Here class B patients were studied at different disease stages to understand the topographic details of the phenotype in preparation for therapies of this regionalized retinopathy.MethodsA cohort of patients with RHO mutations and class B phenotype (n = 28; ages 10–80 years) were studied with rod and cone perimetry and optical coherence tomography (OCT).ResultsAt least three components of the phenotype were identified in these cross-sectional studies. Patients could have hemifield dysfunction, pericentral loss of function, or a diffuse rod sensitivity loss across the visual field. Combinations of these different patterns were also found. Colocalized photoreceptor layer thicknesses were in agreement with the psychophysical results.ConclusionsThese disorders with regional retinal variation of severity require pre-evaluations before enrollment into clinical trials to seek answers to questions about where in the retina would be appropriate to deliver focal treatments, and, for retina-wide treatment strategies, where in the retina should be monitored for therapeutic efficacy (or safety).

The processing and integration of map elements during a recognition memory task is mirrored in eye-movement patterns

Grid lines and visual detail in topographic maps support the encoding and recognition of object locations. Perception-based and knowledge-based functions are discussed to contribute to these effects, but little is known about how participants process such map elements. An eye-tracking study was conducted where participants were asked to learn object locations in topographic maps. The behavioural data of this recognition memory paradigm support the assumption of memory-enhancing functions of grids and topographic detail. Eye-movement data reveal that during encoding, grids and topographic detail trigger attentional shifts towards to-be-learned object locations. These eye-movement patterns are likely one factor contributing to an improved memory performance. Moreover, already the first fixations on a map are affected by the experimental manipulations. This result is particularly visible in the recognition phase and apparently indicates that grids and topographic detail get integrated into the mental representation of the map.

Корсуньский поход князя Владимира: историографические аспекты

The beginning of excavations in Chersonesus, the search of the church where Grand Prince Vladimir was christened, led to the need to compare archeological data and topographic details mentioned in the written sources. However, the historiography of the late 19th – early 20th century turns to such aspects of the Korsun Campaign as the sequence of events preceding it, the disposition of the Russian armed forces by the city walls and the time of their entry into Chersonesus/Korsun. The systematic excavations of the Chersonesus site during the mid-20th century revealed layers of ruins with items dating back to the 10th century and coins of the times of Vasily II which caused archaeologists to conclude that Vladimir’s armed forces’ invasion into Korsun led to the destruction of the city. The paper focuses on the discussion of reasons and times of the ruin layers formation of the late 10th or early 11th century. Until as long as the last fourth of the 20th century, all the monographs on Chersonesus had ascribed the complete destruction of Chersonesus at the end of the 10th century (A. L. Yakobson) to the Rus’-Byzantine War (D. L. Talis). Additionally, there also existed a hypothesis that Chersonesus was supposed to have been captured as a result of an agreement between Vladimir and the Byzantine imperial court as its inhabitants supported the uprising against the existing authorities (A. Poppe, A. Podskalsky). An analysis of the findings of the ruin layer, and the logical sequence of events of the times of the Korsun Campaign makes it possible to suppose that the formation of ruin layers of the early 11th century may have been a result of a natural disaster and that Vladimir did not destroy Chersonesus. This does not, however, exclude the possibility of local fires that could have happened during his and his armed forces’ stay in the city (A. I. Romanchuk, V. V. Khapayev, N. M. Bogdanova). Moreover, having critically considered A. Poppe’s point of view on the inhabitants of Chersonesus’ support of the mutineers and, as a result, the destruction of Chersonesus, D. D. Obolensky pointed to the fact that the source tradition does not have any evidence of the events in question and the conclusion of a large-scale fire contradicts the logic: Grand Prince Vladimir was waiting for the return of his embassy with Princess Anna from Constantinople, it was here that he was christened and got married. However, as Polish diplomat Martin Bronevsky wrote (1st half of the 17th century), except for priests, Vladimir took with him a number of icons and bronze doors. At present, there are two points of view on the destructions of Chersonesus of the late 10th and early 11th centuries: a natural disaster (first fourth of the 11th century) or the plundering of the city by Grand Prince Vladimir. Apart from that, during the period in question as well as before that, there could happen local fires (domestic reasons) but the scale of such layers is not comparable to the aftermath of an earthquake.

Mapping Mistakes: The Cartographic Confusion of Ancient Kleitor

The ancient Greek city of Kleitor lies in a small valley in north central Arkadia. Although only recently the target of systematic excavations, the first plan of its remains was published almost 200 years ago. While this earliest plan is essentially correct in the details, it is also a simple schematic representation with little topographical detail. When a revised plan of the site – comprising a much more skillful representation of the topography – was published in the late 19th century, it soon supplanted the original in the scholarship. Hidden behind its topographic accuracy and artistic flourishes, however, lies the fact that the mapping of the archaeological remains themselves was incorrect. Consequently, as this plan continued to be modified and reproduced throughout the following century, so too were its mistakes duplicated and exaggerated. Showing the cartographical evolution in the representation of ancient Kleitor and its reception by scholars, this paper demonstrates how scholars have constructed their interpretations of the remains around the unintentional predisposition to equate artistic quality with accuracy, and the consequences of this bias on the archaeological interpretations of the site.

Global Topographic Slope Enforcement to Ensure Connectivity and Drainage in an Urban Terrain

AbstractSources of high-resolution topographic data, such as LiDAR, characterize urban terrains in great detail and can provide a resource for distributed hydrologic modeling. Incorporating these data in a distributed hydrologic modeling framework is complicated by the numerous real and artificial pits, barriers, and surface depressions contained in the urban landscape. These features create difficulties with simulating surface drainage that must be resolved to ensure model stability and convergence. This study presents a methodology to calculate distributed slope fields from LiDAR-based digital elevation models (DEM) that addresses this problem and preserves topographic details. This global slope enforcement approach ensures complete domain drainage, and the effects are demonstrated by performing a rainfall-recession test on an impervious domain using a distributed hydrologic model (ParFlow) of an urban watershed in Baltimore. This study shows that the fraction of rainfall input retained as surface stora...

Generating and characterizing the mechanical properties of cell-derived matrices using atomic force microscopy

Mechanical interaction between cells and their surrounding extracellular matrix (ECM) controls key processes such as proliferation, differentiation and motility. For many years, two-dimensional (2D) models were used to better understand the interactions between cells and their surrounding ECM. More recently, variation of the mechanical properties of tissues has been reported to play a major role in physiological and pathological scenarios such as cancer progression. The 3D architecture of the ECM finely tunes cellular behavior to perform physiologically relevant tasks. Technical limitations prevented scientists from obtaining accurate assessment of the mechanical properties of physiologically realistic matrices. There is therefore a need for combining the production of high-quality cell-derived 3D matrices (CDMs) and the characterization of their topographical and mechanical properties. Here, we describe methods that allow to accurately measure the young modulus of matrices produced by various cellular types. In the first part, we will describe and review several protocols for generating CDMs matrices from endothelial, epithelial, fibroblastic, muscle and mesenchymal stem cells. We will discuss tools allowing the characterization of the topographical details as well as of the protein content of such CDMs. In a second part, we will report the methodologies that can be used, based on atomic force microscopy, to accurately evaluate the stiffness properties of the CDMs through the quantification of their young modulus. Altogether, such methodologies allow characterizing the stiffness and topography of matrices deposited by the cells, which is key for the understanding of cellular behavior in physiological conditions.

Improving the global applicability of the RUSLE model – adjustment of the topographical and rainfall erosivity factors

Abstract. Large uncertainties exist in estimated rates and the extent of soil erosion by surface runoff on a global scale. This limits our understanding of the global impact that soil erosion might have on agriculture and climate. The Revised Universal Soil Loss Equation (RUSLE) model is, due to its simple structure and empirical basis, a frequently used tool in estimating average annual soil erosion rates at regional to global scales. However, large spatial-scale applications often rely on coarse data input, which is not compatible with the local scale on which the model is parameterized. Our study aims at providing the first steps in improving the global applicability of the RUSLE model in order to derive more accurate global soil erosion rates. We adjusted the topographical and rainfall erosivity factors of the RUSLE model and compared the resulting erosion rates to extensive empirical databases from the USA and Europe. By scaling the slope according to the fractal method to adjust the topographical factor, we managed to improve the topographical detail in a coarse resolution global digital elevation model. Applying the linear multiple regression method to adjust rainfall erosivity for various climate zones resulted in values that compared well to high resolution erosivity data for different regions. However, this method needs to be extended to tropical climates, for which erosivity is biased due to the lack of high resolution erosivity data. After applying the adjusted and the unadjusted versions of the RUSLE model on a global scale we find that the adjusted version shows a global higher mean erosion rate and more variability in the erosion rates. Comparison to empirical data sets of the USA and Europe shows that the adjusted RUSLE model is able to decrease the very high erosion rates in hilly regions that are observed in the unadjusted RUSLE model results. Although there are still some regional differences with the empirical databases, the results indicate that the methods used here seem to be a promising tool in improving the applicability of the RUSLE model at coarse resolution on a global scale.

Setting Diverging Colors for a Large-Scale Hypsometric Lunar Map Based on Entropy

A hypsometric map is a type of map used to represent topographic characteristics by filling different map areas with diverging colors. The setting of appropriate diverging colors is essential for the map to reveal topographic details. When lunar real environmental exploration programs are performed, large-scale hypsometric maps with a high resolution and greater topographic detail are helpful. Compared to the situation on Earth, fewer lunar exploration objects are available, and the topographic waviness is smaller at a large scale, indicating that presenting the topographic details using traditional hypsometric map-making methods may be difficult. To solve this problem, we employed the Chang’E2 (CE2) topographic and imagery data with a resolution of 7 m and developed a new hypsometric map-making method by setting the diverging colors based on information entropy. The resulting map showed that this method is suitable for presenting the topographic details and might be useful for developing a better understanding of the environment of the lunar surface.

Impact of DEM Resolution on Puddle Characterization: Comparison of Different Surfaces and Methods

DEM-based topographic characterization and quantification of surface depression storage are critical to hydrologic and environmental modeling. Mixed conclusions have been obtained from previous studies on the relationship between maximum depression storage (MDS) and DEM grid spacing, which is affected by different factors, such as topographic characteristics, surface delineation methods and DEM interpolation/aggregation methods. The objective of this study was to evaluate the effects of DEM resolution on topographic characterization with the consideration of these three factors. Twenty-three topographic surfaces (including ideal surfaces, laboratory-scale soil surfaces and watershed-scale land surfaces) were selected, and five software packages, ArcHydro, PCRaster, HEC-GeoHMS, TauDEM and PD (puddle delineation), were used for surface delineation. Our results indicated that MDS, maximum ponding area (MPA) and the number of puddles (NP) decreased with increasing grid spacing for most smoother surfaces due to the loss of topographic detail. For most rough surfaces (e.g., mountain-type surfaces with significant variations in surface elevations), however, the changing patterns of MDS and MPA varied with an increase in grid spacing mainly due to the unreal “artificial depressions/puddles” generated during the interpolation/aggregation process. This study emphasizes the importance of topographic characteristics, DEM resolution and surface delineation methods.

The application of scanning near field optical imaging to the study of human sperm morphology.

BackgroundThe morphology of spermatozoa is a fundamental aspect to consider in fertilization, sperm pathology, assisted reproduction and contraception. Head, neck, midpiece, principal and terminal part of flagellum are the main sperm components to investigate for identifying morphological features and related anomalies. Recently, scanning near-field optical microscopy (SNOM), which belongs to the wide family of nanoscopic techniques, has opened up new routes for the investigation of biological systems. SNOM is the only technique able to provide simultaneously highly resolved topography and optical images with a resolution beyond the diffraction limit, typical of conventional optical microscopy. This offers the advantage to obtain complementary information about cell surface and cytoplasmatic structures.ResultsIn this work human spermatozoa both healthy and with morphological anomalies are analyzed by SNOM, to demonstrate the potentiality of such approach in the visualization of sperm morphological details. The combination of SNOM topography with optical (reflection and transmission) images enables to examine typical topographic features of spermatozoa together with underlying cytoplasmic structures. Indeed the head shape and inner components as acrosome and nucleus, and the organization of mitochondria in the midpiece region are observed. Analogously for principal tract of the tail, the ridges and the columns are detected in the SNOM topography, while their internal arrangement can be observed in the corresponding SNOM optical transmission images, without requiring specific staining procedures or invasive protocols.ConclusionsSuch findings demonstrate that SNOM represents a versatile and powerful tool to describe topographical and inner structural details of spermatozoa simultaneously. This analysis could be helpful for better characterizing several morphological anomalies, often related to sperm infertility, which cannot be examined by conventional techniques all together.Electronic supplementary materialThe online version of this article (doi:10.1186/s12951-014-0061-5) contains supplementary material, which is available to authorized users.

Static and Dynamic Aspects of Black Silicon Formation

We present a combination of experimental data and modeling that explains some of the important characteristics of black silicon (BSi) developed in cryogenic reactive ion etching (RIE) processes, including static properties (dependence of resulting topography on process parameters) and dynamic aspects (evolution of topography with process time). We generate a phase diagram predicting the RIE parameter combinations giving rise to different BSi geometries and show that the topographic details of BSi explain the metamaterial characteristics that are responsible for its low reflectivity. In particular, the unique combination of needle and hole features of various heights and depths, which is captured by our model and confirmed by focused ion beam nanotomography, creates a uniquely smooth transition in refractive index. The model also correctly describes dynamical characteristics, such as the dependence of aspect ratio on process time, and the prediction of new etching fronts appearing at topographical saddle points during the incipient stages of BSi development--a phenomenon reported here for the first time.

Use of Terrestrial Laser Scans for High-Resolution Documentation and 3D Modeling of “Desert Kites”

Over 3,000 Desert Kites are known in Southwest Asia. However, most are known only by the study of Google Earth images, and the majority have never been visited or surveyed by foot or thoroughly documented. The high-resolution documentation of such constructions is imperative but limited in many cases, due to the harsh conditions and the use of local undressed stones for building. We introduce here the use of a LiDAR scanner and its contribution to the study of kites, with a case study from the southern Negev, Israel. In particular, the derived 3D models provide an excellent basis for addressing research foci, such as topographic details, the area between the arms and inside the heads, inclination, and especially the volumes of the built walls. Such data enhance our understanding of the construction efforts on the one hand, and the details of the topographic settings on the other.

Illuminated up close: near-field optical microscopy of cell surfaces

Invented in the 1990s, near-field optical microscopy (NSOM) was the first optical microscopy method to hold the promise of finally breaking the diffraction barrier in studies of biological samples. This promise, though, failed to materialize at that time, largely owing to the inability to image soft samples, such as cell surfaces, without damage. However, steady technical improvements have now produced NSOM devices that can routinely achieve images of cell surfaces with sub-100nm resolution in aqueous solution. Further, beyond just optical information, these instruments can also provide simultaneous topographic, mechanical, and/or chemical details of the sample, an ability not yet matched by any other optics-based methodology. With the long recognized important roles of many biological processes at cell surfaces in human health and disease, near-field probing of cell surfaces is indeed now well poised to directly illume in biomedicine what has, until recently, been unknowable with classic light microscopy. From the Clinical EditorThis paper presents a novel and important near-field microscopy-based method directly enabling the imaging of cell surfaces with sub-100nm resolution. Unlike other optics-based methods, the presented technique can also provide topographic, mechanical and chemical details of the samples.

Effect of temperature and potassium chloride impurity on the relative ⟨101̅0⟩ tilt grain boundary and surface free energies in ice.

The ratio of the grain boundary free energies relative to the surface free energies γgb/γs can be determined by measuring the root angles of the grooves formed at the intersection of the grain boundary with the free surface. The grooves were copied by plastic replicas, and the topographic details were revealed with a laser confocal 3D microscope. Values of γgb/γs were determined for high purity and potassium chloride doped ice bicrystals annealed at -5 and -18 °C. The studied samples were ⟨101̅0⟩/ψ tilt grain boundaries with ψ between 10 and 180°. The used KCl concentrations were 1 and 10 μmol/l, and the conductivity of the pure ice was 0.3 μS. ⟨101̅0⟩/60° grain boundary relative energies were also determined for different grain boundary inclinations. All the γgb/γs obtained values were analyzed and compared using the CSL (coincidence site lattice) theory. For pure samples annealed at -18 °C, an important variation of γgb/γs with the grain boundary inclination was found. In general, a remarkable correspondence between CSL planar density Γ and γgb/γs was observed. Results also showed that the increase of temperature and the impurity changes significantly γgb/γs.