height distribution
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2022 ◽  
Vol 14 (2) ◽  
pp. 311
Author(s):  
Cheng-Yen Chiang ◽  
Kun-Shan Chen ◽  
Ying Yang ◽  
Yang Zhang ◽  
Lingbing Wu

This paper investigates the radar image statistics of rough surfaces by simulating the scattered signal’s dependence on the surface roughness. Statistically, the roughness characteristics include the height probability density (HPD) and, to the second-order, the power spectral density (PSD). We simulated the radar backscattered signal by computing the far-field scattered field from the rough surface within the antenna beam volume in the context of synthetic aperture radar (SAR) imaging. To account for the non-Gaussian height distribution, we consider microscopic details of the roughness on comparable radar wavelength scales to include specularly, singly, and multiply scatterers. We introduce surface roughness index (RSI) to distinguish the statistical characteristics of rough surfaces with different height distributions. Results suggest that increasing the RMS height does not impact the Gaussian HPD surface but significantly affects the Weibull surface. The results confirm that as the radar frequency increases, or reaches a relatively larger roughness, the surface’s HPD causes significant changes in incoherent scattering due to more frequent multiple scattering contributions. As a result, the speckle move further away from the Rayleigh model. By examining individual RSI, we see that the Gaussian HPD surface is much less sensitive to RMS height than the Weibull HPD surface. We demonstrate that to retrieve the surface parameters (both dielectric and roughness) from the estimated RCS, less accuracy is expected for the non-Gaussian surface than the Gaussian surface under the same conditions. Therefore, results drawn from this study are helpful for system performance evaluations, parameters estimation, and target detection for SAR imaging of a rough surface.


2021 ◽  
Vol 6 (4) ◽  
pp. 259-266
Author(s):  
S. O. Markov ◽  
E. V. Murko ◽  
F. S. Nepsha

Grain size distribution as a structural characteristic of waste rock and bulk masses in the course of mining and construction works acquires quantitative values in the process of rock blasting and hauling of rock mass. Such physical-mechanical and structural-textural parameters of a rock mass, as the ultimate strength of rocks and rock mass, fracturing, diameter of the natural rock jointing, have a significant impact on the blasted rock mass grain size distribution. On the other hand, such characteristics as stability, permeability of waste rock masses largely depend on the lithology and grain size distribution of the loosened rocks composing waste rock dumps and their height distribution within a dump. The paper describes the findings of the study of the grain size distribution of waste rock masses of Kuzbass coal strip mines and the features of its spatial variations within the masses. The textures of the bulk masses and physical and technical properties of the stacked rocks were studied both at the Kuzbass waste rock sites and in laboratory conditions. The grain size distribution of the fine lump part of the dumps with the lump size up to 50 mm was investigated by sieve method according to GOST 12536–2014, and the medium and large lump part was studied using oblique photoplanimetry. The field observations showed that the bottom part of the rock dumps, dumped by peripheral bulldozer or excavator methods was composed of coarse fraction with average lump size of: d<sub>cr</sub> = 0.8–1 m, while the middle part, of rock lumps of d<sub>cr</sub> = 0.4–0.6 m, and the upper part, mainly of fine fraction with lump size of less than 0.1 m. The ratio of length, width, and thickness of the blasted rock lumps was 1:0.85:0.8, which corresponds to elongated-flattened shape of the lumps. This requires significant number of coordinates for describing the lump positions in the rock mass, as well as taking into account the moments of inertia when modeling the motion of such lumps until they reach a stable position. Up-to-date non-commercial or commercial software and corresponding hardware can be used to take into account non-isometric shape of the lumps when modeling their motion.


2021 ◽  
Author(s):  
Md. Abdul Motin ◽  
Andreas Steiger-Thirsfeld ◽  
Michael Stöger-Pollach ◽  
Günther Rupprechter

AbstractA surface science based approach was applied to model carbon supported Pd nanoparticle catalysts. Employing physical vapour deposition of Pd on sputtered surfaces of highly oriented pyrolytic graphite (HOPG), model catalysts were prepared that are well-suited for characterization by X-ray photoelectron spectroscopy (XPS) and scanning tunneling microscopy (STM). Analysis of the HOPG substrate before and after ion-bombardment, and of Pd/HOPG before and after annealing, revealed the number of “nominal” HOPG defects (~ 1014 cm−2) as well as the nucleation density (~ 1012 cm−2) and structural characteristics of the Pd nanoparticles (mean size/height/distribution). Two model systems were stabilized by UHV annealing to 300 °C, with mean Pd particles sizes of 4.3 and 6.8 nm and size/height aspect ratio up to ~ 10. A UHV-compatible flow microreactor and gas chromatography were used to determine the catalytic performance of Pd/HOPG in ethylene (C2H4) hydrogenation up to 150 °C under atmospheric pressure, yielding temperature-dependent conversion values, turnover frequencies (TOFs) and activation energies. The performance of Pd nanocatalysts is compared to that of polycrystalline Pd foil and contrasted to Pt/HOPG and Pt foil, pointing to a beneficial effect of the metal/carbon phase boundary, reflected by up to 10 kJ mol−1 lower activation energies for supported nanoparticles. Graphical Abstract


Author(s):  
Ihor Kasiianyk ◽  
Ihor Rybak ◽  
Olha 29. Matuz ◽  
Lybov Kasiianyk ◽  
Yaroslav Vitvitskiy

The publication highlights the regional conditions for the implementation of paleotours, as the basic components of the structure of the complex route "Terra Podolica", the territory of Podolsk Transnistria. The main features of paleotours on the basis of territorial locations with the characteristic of technical aspects of their realization are revealed. Leading fossils have been identified that can become regional paleobrends and can be used as a means of promoting geotourism. The conditions for effective implementation of paleotours in the regional recreational complex of the Podolsk region are established. The analysis of efficiency of perspective formats of development of geotourism on the basis of regional conditions is carried out. The development of geotourism in the Podolsk region has strong prerequisites: resource base, tourist flow and developed tourist infrastructure. At the same time, among the specialized forms, only the speleological direction is actively developing. Other geotourism components are limited to mentions or brief demonstrations of individual objects during sightseeing tours. Popularization of the direction is just beginning, and geotourism products are in the state of development and experimental testing. In particular, the paleontological direction, which has examples of successful implementation of abstract implementation (for example: dinosaur parks without reference to the region), using the resource capabilities of Podillya effective formats can become branded. The main theoretical aspects to be addressed are: focusing on particularly interesting regional fossils that can be interpreted as values ​​and reveal through their prism geological history, features of modern landscapes and, if possible, regional cultural and economic phenomena, selection of effective forms of interactive interaction and development on their basis of competitive tourist products, formation and equipment of locations for realization of tourist products, popularization of the direction and interest in its realization of local economic, educational and nature protection subjects. In middle Transnistria, the valley and river landscapes change markedly from west to east (or vice versa). The main reason for this is the differences in lithological structure, emphasized by the shape of the slopes, the color of the rocks and the height distribution of plant tiers. This in turn affects the configuration of settlements, patterns of location of buildings, architectural composition of buildings, distribution of farmland. In combination with historical traditions, unique landscape and cultural entities are formed, promising for the organization of thematic tours. The visual change of geological deposits in the region is due to the lithological features of the structure, especially the Domezozoic tier. It is clearly visible in river valleys and weakly expressed in watersheds. In general, each large tributary of the Dniester corresponds to an "individual" lithological complex. Its features are preserved along the meridional extension of the watercourse with bright local manifestations in areas of tectonic activity. The effect of contrast occurs when laying a route across river valleys, when passing the watershed, the observer falls into another "landscape reality" Paleontological tours are considered by the authors focused on increasing the tourist attractiveness of the region, attracting untapped resources, optimizing tourist products within specific locations, developing innovative areas and forms of tourism and interaction with local economic systems of united territorial communities. The specifics of the organization of paleotours allows you to create a new economic niche with a staffing offer for specialists in natural specialties. Key words: geotourism, paleotours, Podolia¢/


2021 ◽  
Vol 13 (23) ◽  
pp. 4915
Author(s):  
Zhenmin Niu ◽  
Nai’ang Wang ◽  
Nan Meng ◽  
Jiang Liu ◽  
Xueran Liang ◽  
...  

Mega-dunes in the lake group area of the Badain Jaran Sand Sea, China, are generally taller than dunes in the non-lake group area. This spatial distribution of dune heights may provide a new perspective on the controversy regarding the dunes’ formation mechanism. In this study, we calculated the relative heights and slopes of individual dunes based on a digital elevation model, and we confirmed the height distribution of abnormally tall dunes in the lake group area of the sand sea. It was also found that slopes of more than 10° in the lake group area are more common than those in the non-lake group area. Based on meteorological observations, coupled with the measurement of water content in the sand layers, we propose a conceptual model demonstrating that moisture exchange between the lakes and soil via non-rainfall water will humidify dune slopes and form a more favorable accumulation environment for aeolian sand, thus increasing dune heights. Although long-term observations are yet to be carried out, the present study can be used as evidence for understanding the basis of dune formation in the lake group area and assessing groundwater utilization in deserts.


Electronics ◽  
2021 ◽  
Vol 10 (23) ◽  
pp. 2941
Author(s):  
Amir Hoshang Ramezani ◽  
Siamak Hoseinzadeh ◽  
Zhaleh Ebrahiminejad ◽  
Milad Sangashekan ◽  
Saim Memon

In the present study, the microstructural and statistical properties of unimplanted in comparison to argon ion-implanted tantalum-based thin film surface structures are investigated for potential application in microelectronic thin film substrates. In the study, the argon ions were implanted at the energy of 30 keV and the doses of 1×1017, 3×1017, and 7×1017 (ion/cm2) at an ambient temperature. Two primary goals have been pursued in this study. First, by using atomic force microscopy (AFM) analysis, the roughness of samples, before and after implantation, has been studied. The corrosion apparatus wear has been used to compare resistance against tantalum corrosion for all samples. The results show an increase in resistance against tantalum corrosion after the argon ion implantation process. After the corrosion test, scanning electron microscopy (SEM) analysis was applied to study the sample morphology. The elemental composition of the samples was characterized by using energy-dispersive X-ray (EDX) analysis. Second, the statisticalcharacteristics of both unimplanted and implanted samples, using the monofractal analysis with correlation function and correlation length of samples, were studied. The results show, however, that all samples are correlated and that the variation of ion doses has a negligible impact on the values of correlation lengths. Moreover, the study of height distribution and higher-order moments show the deviation from Gaussian distribution. The calculations of the roughness exponent and fractal dimension indicates that the implanted samples are the self-affine fractal surfaces.


2021 ◽  
Vol 2021 ◽  
pp. 1-17
Author(s):  
Zhang Ziguang ◽  
Yihang Li ◽  
Jiesheng Zhang ◽  
Tao Xu ◽  
Guangyong Cao ◽  
...  

The self-stability height of the foundation pit sidewall is an important criterion for evaluating the safety degree and designing the supporting structure. The strength reduction elastic-plastic finite element numerical calculation method has been adopted in this paper. Based on comparative analysis of the stability characteristics for deep foundation pit in binary strata of upper soil and lower rock under multiple working conditions, the potential fracture surface of deep foundation pit and the evolution law of corresponding safety factor have been revealed under different Hs and H. A new idea that the vertical soil sidewall height (Hs) and the vertical rock sidewall height (Hr) are used as two independent evaluation indexes, respectively, for deep foundation pit stability in binary strata of upper soil and lower rock has been put forward. The distribution characteristics and variation law of Hs0 and Hr0 under different Hs and different H have been revealed, respectively. The spatial distribution map of the self-stabilizing height for deep foundation pit vertical sidewall in upper soil and lower rock binary stratum has been constructed, and the mathematical fitting equation between Hr0 and Hs has been obtained. Finally, combined with the implementation effect of the deep foundation pit project of Ningxia Road Station for Qingdao Metro Line 3, the rationality of the conclusions is verified. The research results provide theoretical basis for quickly determining the self-stability characteristics of foundation pit vertical sidewall.


2021 ◽  
Vol 14 (11) ◽  
pp. 7153-7165
Author(s):  
Oscar S. Sandvik ◽  
Johan Friberg ◽  
Moa K. Sporre ◽  
Bengt G. Martinsson

Abstract. In this study we describe a methodology to create high-vertical-resolution SO2 profiles from volcanic emissions. We demonstrate the method's performance for the volcanic clouds following the eruption of Sarychev in June 2009. The resulting profiles are based on a combination of satellite SO2 and aerosol retrievals together with trajectory modelling. We use satellite-based measurements, namely lidar backscattering profiles from the Cloud-Aerosol Lidar with Orthogonal Polarization (CALIOP) satellite instrument, to create vertical profiles for SO2 swaths from the Atmospheric Infrared Sounder (AIRS) aboard the Aqua satellite. Vertical profiles are created by transporting the air containing volcanic aerosol seen in CALIOP observations using the FLEXible PARTicle dispersion model (FLEXPART) while preserving the high vertical resolution using the potential temperatures from the MERRA-2 (Modern-Era Retrospective analysis for Research and Application) meteorological data for the original CALIOP swaths. For the Sarychev eruption, air tracers from 75 CALIOP swaths within 9 d after the eruption are transported forwards and backwards and then combined at a point in time when AIRS swaths cover the complete volcanic SO2 cloud. Our method creates vertical distributions for column density observations of SO2 for individual AIRS swaths, using height information from multiple CALIOP swaths. The resulting dataset gives insight into the height distribution in the different sub-clouds of SO2 within the stratosphere. We have compiled a gridded high-vertical-resolution SO2 inventory that can be used in Earth system models, with a vertical resolution of 1 K in potential temperature, 61 ± 56 m, or 1.8 ± 2.9 mbar.


2021 ◽  
Author(s):  
◽  
Peter Hauer

<p>The detection and characterisation of micro- and nanoscale particles has become increasingly important in many scientific fields, spanning from colloidal science to biomedical applications. Resistive Pulse Sensing (RPS) and its derivative Tuneable Resistive Pulse Sensing (TRPS), which both use the Coulter principle, have proven to be useful tools to detect and analyse particles in solution over a wide range of sizes. While RPS uses a fixed size pore, TRPS uses a dynamically stretchable pore in a polyurethane membrane, which has the advantages that the pore geometry can be tuned to increase the device's sensitivity and range of detection. The technique has been used to accurately determine the size, concentration and charge of many different analytes.  However, the information obtained using TRPS does not give any insight into the particle's composition. In an attempt to overcome this, an experimental technique was developed in order to obtain simultaneous, time-resolved, high-resolution optical spectra of particles passing through the pore. Due to the ordered and controllable fashion in which the particles are guided through the sensing region, this approach has an advantage over diffusion based optical techniques. The experimental setup for the coordinated electrical and optical measurements involves many underlying physical phenomena, e.g. microuidics, electrokinetic effects, and Gaussian beam optics. A significant proportion of this work was therefore devoted to the development and the optimisation of the experimental setup by adapting a commercial TRPS device and a spectrometer with an attached microscope. Methods to engineer the spot size of a Gaussian beam to account for the different pore diameters, and the development of algorithms to filter, analyse and coordinate the recorded data are essential to the technique.  The results using fluorescently labelled polystyrene particle sets with diameters from 190nm to 2 µm show that matching rates between the electrical and optical measurements of over 90% can repeatedly be achieved. Mixtures of particle species with similar diameters but with different fluorescent labels were used to demonstrate the technique's capability to characterise the analyte on a particle-by-particle basis and extend the information that can be obtained by TRPS alone. It was also shown that the data acquired with the electrical and optical measurements complement each other and can be used to better understand the TRPS technique itself. The influence of experimental parameters, such as the particle velocity, the beam size and the optical detection volume, on the intensity of the optical signals and the matching rates was studied intensively. These studies showed that the technique requires a careful experimental design to achieve the best results. Overall, the developed technique enhances the particle-by-particle specificity of conventional RPS measurements, and could be useful for a range of particle characterization and bio-analysis applications.  Alongside the experiments, semi-analytic modelling and simulations using the Finite Element Method (FEM) were used to understand the particle motion through the pores, to interpret the experimental data, and predict the optical signals. The models were also used to assist the design and the optimization of the experiments. The FEM models were implemented with increasing physical detail and show superior understanding of the TRPS signals compared to the semi-analytic model, which is conventionally used in the TRPS field. The physical phenomena considered included o -axis trajectories, particle-field interactions for both fluid and electric fields, and the non-homogeneous distribution of ions close to the charged membrane and particle interfaces. Several effects which have been observed experimentally could be explained, including the intrinsic pulse height distribution, the current rectification, and the occurrence of bi-phasic pulses, demonstrating the benefits of FEM methods for RPS.</p>


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