scholarly journals On the Use of Microwave Holography to Detect Surface Defects of Rails and Measure the Rail Profile

Sensors ◽  
2019 ◽  
Vol 19 (6) ◽  
pp. 1376 ◽  
Author(s):  
Andrey Zhuravlev ◽  
Vladimir Razevig ◽  
Sergey Ivashov ◽  
Aleksey Skrebkov ◽  
Viktor Alekseev
Keyword(s):  
Experimental Data ◽  
Electromagnetic Waves ◽  
Surface Defects ◽  
Back Propagation ◽  
Surface Profile ◽  
Small Scale ◽  
Radar Images ◽  
Comparable Accuracy ◽  
Radar Measurements ◽  
Object Of Study

The use of microwave holography for detecting rail surface defects is considered in this paper. A brief review of available sources on radar methods for detecting defects on metal surfaces and rails is given. An experimental setup consisting of a two-coordinate electromechanical scanner and a radar with stepped frequency signal in the range from 22.2 to 26.2 GHz is described, with the help of which experimental data were obtained. Fragments of R24 rails with surface defects in their heads were used as the object of study. The radar images of rail defects were obtained by the described method based on back propagation of a wavefront. It is shown that polarization properties of electromagnetic waves can be used to increase the contrast of small-scale surface defects. A method of estimating rail surface profile by radar measurements is given and applied to the experimental data. Comparison of the longitudinal rail head profiles obtained by radar and by direct contact measurements showed that the radar method gives comparable accuracy.

INTERACTION OF SHORT-WAVE ELECTROMAGNETIC WAVES WITH SMALL-SCALE IONOSPHERIC INHOMOGENEITIES OF THE POLAR IONOSPHERE (part II)

2020 ◽  
pp. 45-56
Author(s):  
G. A. Zhbankov ◽  
N. P. Danilkin
Keyword(s):  
Experimental Data ◽  
Electromagnetic Waves ◽  
Field Experiments ◽  
Short Wave ◽  
Small Scale ◽  
Concentration Change ◽  
Polar Ionosphere ◽  
Vertical Ground ◽  
Simulation Results ◽  
The Impact

The results of a comparative analysis of the data of computational and field experiments reflecting the peculiarities of the impact of small-scale inhomogeneities of electron concentration in the Earth's ionosphere on the characteristics of radio wave propagation during vertical ground-based and satellite sounding of the ionosphere are presented. It has been proved that these inhomogeneities are the cause of noticeable distortions of traces in ionograms. The simulation results confirm the possibility of determining the degree of concentration change in a small-scale inhomogeneous structure from experimental data.

Simulation and prediction of optical characterization of casting (Adamantan-Fulgide) thin films using (CTANNs) approach

2019 ◽  
Vol 33 (11) ◽  
pp. 1950093 ◽  
Author(s):  
A. M. A. EL-Barry ◽  
D. M. Habashy
Keyword(s):  
Experimental Data ◽  
Thin Films ◽  
Back Propagation ◽  
Optical Characterization ◽  
Experimental Information ◽  
Training Algorithm ◽  
Energy Gaps ◽  
Resilient Back Propagation ◽  
Good Agreement

For reinforcement, the photochromic field and the cooperation between the theoretical and experimental branches of physics, the computational, theoretical artificial neural networks (CTANNs) and the resilient back propagation (R[Formula: see text]) training algorithm were used to model optical characterizations of casting (Admantan-Fulgide) thin films with different concentrations. The simulated values of ANN are in good agreement with the experimental data. The model was also used to predict values, which were not included in the training. The high precision of the model has been constructed. Moreover, the concentration dependence of both the energy gaps and Urbach’s tail were, also tested. The capability of the technique to simulate the experimental information with best accuracy and the foretelling of some concentrations which is not involved in the experimental data recommends it to dominate the modeling technique in casting (Admantan-Fulgide) thin films.

Benchmark of a Novel Aero-Elastic Simulation Code for Small Scale VAWT Analysis

2018 ◽  
Vol 141 (4) ◽  
Author(s):  
David Marten ◽  
Matthew Lennie ◽  
George Pechlivanoglou ◽  
Christian Oliver Paschereit ◽  
Alessandro Bianchini ◽  
...  
Keyword(s):  
Experimental Data ◽  
Wind Turbine ◽  
Open Source ◽  
Structural Model ◽  
Element Model ◽  
Small Scale ◽  
Elastic Model ◽  
Element Analysis ◽  
Simulation Code ◽  
Highly Nonlinear

After almost 20 years of absence from research agendas, interest in the vertical axis wind turbine (VAWT) technology is presently increasing again, after the research stalled in the mid 90's in favor of horizontal axis wind turbines (HAWTs). However, due to the lack of research in past years, there are a significantly lower number of design and certification tools available, many of which are underdeveloped if compared to the corresponding tools for HAWTs. To partially fulfill this gap, a structural finite element analysis (FEA) model, based on the Open Source multiphysics library PROJECT::CHRONO, was recently integrated with the lifting line free vortex wake (LLFVW) method inside the Open Source wind turbine simulation code QBlade and validated against numerical and experimental data of the SANDIA 34 m rotor. In this work, some details about the newly implemented nonlinear structural model and its coupling to the aerodynamic solver are first given. Then, in a continuous effort to assess its accuracy, the code capabilities were here tested on a small-scale, fast-spinning (up to 450 rpm) VAWT. The study turbine is a helix shaped, 1 kW Darrieus turbine, for which other numerical analyses were available from a previous study, including the results coming from both a one-dimensional beam element model and a more sophisticated shell element model. The resulting data represented an excellent basis for comparison and validation of the new aero-elastic coupling in QBlade. Based on the structural and aerodynamic data of the study turbine, an aero-elastic model was then constructed. A purely aerodynamic comparison to experimental data and a blade element momentum (BEM) simulation represented the benchmark for QBlade aerodynamic performance. Then, a purely structural analysis was carried out and compared to the numerical results from the former. After the code validation, an aero-elastically coupled simulation of a rotor self-start has been performed to demonstrate the capabilities of the newly developed model to predict the highly nonlinear transient aerodynamic and structural rotor response.

scholarly journals Estimation of the Turbulent Fraction in the Free Atmosphere from MST Radar Measurements

2005 ◽  
Vol 22 (9) ◽  
pp. 1326-1339 ◽  
Author(s):  
Richard Wilson ◽  
Francis Dalaudier ◽  
Francois Bertin
Keyword(s):  
Dissipation Rate ◽  
Spectral Width ◽  
Unbiased Estimation ◽  
Small Scale ◽  
Doppler Width ◽  
Free Atmosphere ◽  
Dissipation Rates ◽  
Sampling Volume ◽  
Radar Measurements ◽  
Width Measurements

Abstract Small-scale turbulence in the free atmosphere is known to be intermittent in space and time. The turbulence fraction of the atmosphere is a key parameter in order to evaluate the transport properties of small-scale motions and to interpret clear-air radar measurements as well. Mesosphere–stratosphere–troposphere (MST)/stratosphere–troposphere (ST) radars provide two independent methods for the estimation of energetic parameters of turbulence. First, the Doppler spectral width σ2 is related to the dissipation rate of kinetic energy εk. Second, the radar reflectivity, or C2n, relates to the dissipation rate of available potential energy εp. However, these two measures yield estimates that differ with respect to an important point. The Doppler width measurements, and related εk, are reflectivity-weighted averages. On the other hand, the reflectivity estimate is a volume-averaged quantity. The values of εp depend on both the turbulence intensity and the turbulent fraction within the radar sampling volume. Now, the two dissipation rates εp and εk are related quantities as shown by various measurements within stratified fluids (atmosphere, ocean, lakes, or laboratory). Therefore, by assuming a “canonical” value for the ratio of dissipation rates, an indirect method is proposed to infer the turbulent fraction from simultaneous radar measurements of reflectivity and Doppler broadening within a sampling volume. This method is checked by using very high resolution radar measurements (30 m and 51 s), obtained by the PROUST radar during a field campaign. The method is found to provide an unbiased estimation of the turbulent fraction, within a factor of 2 or less.

scholarly journals Organoleptic, Sensory and Biochemical Traits of Arabica Coffee and their Arabusta Hybrids

2021 ◽  
Author(s):  
Kahiu Ngugi ◽  
Jane Jerono Cheserek ◽  
Chrispine Ogutu Omondi
Keyword(s):  
Experimental Data ◽  
Genetic Diversity ◽  
Genetic Variation ◽  
Coffea Arabica ◽  
Small Scale ◽  
Arabica Coffee ◽  
Biochemical Compounds ◽  
Small Scale Farmers ◽  
Organoleptic Traits ◽  
Cup Quality

Coffee as a cash crop, reduces food insecurity by providing regular incomes and is a major foreign exchange earner in more than fifty tropical countries where it is grown either as Arabica (Coffea arabica) or Robust (Coffea canepora). In Kenya which grow some Robusta but mostly Arabica coffee, the production has been declining, mainly because world coffee prices have plummeted to about 5 USD for a 650Kg of un-hulled beans per acre. The only way world prices are likely to increase and benefit the small-scale farmers, is by improving the cup quality and enabling these countries to sell their coffee in specialty markets. This review, underscores the importance of analyzing and estimating organoleptic, sensory and biochemical compounds diversity in Arabica coffee, since these are the factors that determine cup quality. In an attempt to do so, the chapter presents experimental data that analyzed various sensory and organoleptic traits of Arabica coffee and their Arabusta hybrids that proves that tremendous genetic diversity exists in coffee genotypes grown in Kenya and it is possible to utilize this genetic variation to improve cup quality.

scholarly journals Karakteristik Kewirausahaan Petani Muda Skala Kecil Berorientasi Pasar

2020 ◽  
Vol 8 (2) ◽  
pp. 106
Author(s):  
Gema Wibawa Mukti ◽  
Rani Andriani Budi Kusumo ◽  
Yosini Deliana
Keyword(s):  
Rural Areas ◽  
Random Sampling ◽  
Sampling Method ◽  
Business Processes ◽  
Land Ownership ◽  
Small Scale ◽  
Managerial Skills ◽  
Entrepreneurial Characteristics ◽  
Object Of Study

This study aims to identify entrepreneurial characteristics possessed by young farmers. Young farmers who are the object of study are horticulture farmers in Kabupaten Bandung Barat. This study tries to explain the characteristics of farmers in terms of entrepreneurship. This study focuses on young farmers in Cisarua, Parongpong, and Lembang Subdistricts, with land ownership of no more than two hectares (small scale). The determination of the sample is done by a stratified random sampling method. The strata in this study are young farmers under the age of 40 and farming in the sub-sector of horticulture products in Kabupaten Bandung Barat. The next step is to determine the sample in the study as many as 120 farmers. Farmers who play a role as entrepreneurs are not only experts in the production process, but they have visionary results-oriented business managerial skills. The results of the study show that the majority of respondents have moderate (moderate) entrepreneurial characteristics. This is more due to the farming climate in rural areas which is still moderate, not oriented to professionalism and entrepreneurship. However, young farmers have a desire to develop, so that their business processes are different from those of farmers in general, where young farmers are starting to implement professional work methods in their gardens. The entrepreneurial approach has been seen in the way they do business, where they always want to be better, always look for the latest information, create innovations in the garden, apply management in their farming and take risks.

scholarly journals A Proposed Approach to Determine the Edges in SAR images

2020 ◽  
pp. 185-192
Author(s):  
Rabab Farhan Abbas
Keyword(s):  
Edge Detection ◽  
Electromagnetic Waves ◽  
Operator Method ◽  
Bézier Curve ◽  
Bezier Curve ◽  
Edge Image ◽  
Sar Images ◽  
Wavelet Method ◽  
Radar Images ◽  
Sobel Operator

Radar is the most eminent device in the prolonged scattering era The mechanisms involve using electromagnetic waves to take Synthetic Aperture Radar (SAR) images for long reaching. The process of setting edges is one of the important processes used in many fields, including radar images, which assists in showing objects such as mobile vehicles, ships, aircraft, and meteorological and terrain forms. In order to accurately identify these objects, their edges must be detected. Many old-style methods are used to isolate the edges but they do not give good results in the  determination process. Conservative methods use an operator to detect the edges, such as the Sobel operator which is used to perform edge detection where the edge does not appear well.      The proposed method which combines Ridgelet transform, Bezier curve and Sobel operator is used to detect edges very efficiently. Ridghelet transform resolves the harms in the wavelet transform and it can well detect the edges in images. Bezier curve can profit gradual variation of the data and their mutability. Hence, the efficiency of the edged image is improved and, when used with Sobel operator, the quality of the edge image become very good. The data show that the advocated method has superior fallouts over the Sobel edge detection and the wavelet method in both subjective and impartial experiments. While the Peak Signal to Noise Ratio(PSNR) values were equal to 9.3812, 9.8918, 9.6521 and 9.0743using the Sobel operator method and to10.2564, 10.7927, 10.5612and 10.8633 using the wavelet method, they were increased in the proposed method to 12.6542, 12.9514, 12.8574 and 12.3013 respectively.

scholarly journals A 5-yr 40-km-Resolution Global Climatology of Superrefraction for Ground-Based Weather Radars

2009 ◽  
Vol 48 (1) ◽  
pp. 89-110 ◽  
Author(s):  
Philippe Lopez
Keyword(s):  
United States ◽  
Electromagnetic Waves ◽  
Vertical Gradient ◽  
Radar Data ◽  
The United States ◽  
Horizontal Resolution ◽  
Trade Wind ◽  
Late Afternoon ◽  
The Balkans ◽  
Radar Images

Abstract The propagation of electromagnetic waves emitted from ground-based meteorological radars is determined by the stratification of the atmosphere. In extreme superrefractive situations characterized by strong temperature inversions or strong vertical gradients of moisture, the radar beam can be deflected toward the ground (ducting or trapping). This phenomenon often results in spurious returned echoes and misinterpretation of radar images such as erroneous precipitation detection. In this work, a 5-yr global climatology of the frequency of superrefractive and ducting conditions and of trapping-layer base height has been produced using refractivity computations from ECMWF temperature, moisture, and pressure analyses at a 40-km horizontal resolution. The aim of this climatology is to better document how frequent such events are, which is a prerequisite for fully benefiting from radar data information for the multiple purposes of model validation, precipitation analysis, and data assimilation. First, the main climatological features are summarized for the whole globe: high- and midlatitude oceans seldom experience superrefraction or ducting whereas tropical oceans are strongly affected, especially in regions where the trade wind inversion is intense and lying near the surface. Over land, seasonal averages of superrefraction (ducting) frequencies reach 80% (40%) over tropical moist areas year-round but remain below 40% (15%) in most other regions. A particular focus is then laid on Europe and the United States, where extensive precipitation radar networks already exist. Seasonal statistics exhibit a pronounced diurnal cycle of ducting occurrences, with averaged frequencies peaking at 60% in summer late afternoon over the eastern half of the United States, the Balkans, and the Po Valley but no ducts by midday. Similarly high ducting frequencies are found over the southwestern coast of the United States at night. A potentially strong reduction of ducting occurrences with increased radar height (especially in midlatitude summer late afternoon) is evidenced by initiating refractivity vertical gradient computations from either the lowest or the second lowest model level. However, installing radar on tall towers also brings other problems, such as a possible amplification of sidelobe clutter echoes.

scholarly journals Urban Building Change Detection in SAR Images Using Combined Differential Image and Residual U-Net Network

2019 ◽  
Vol 11 (9) ◽  
pp. 1091 ◽  
Author(s):  
Lu Li ◽  
Chao Wang ◽  
Hong Zhang ◽  
Bo Zhang ◽  
Fan Wu
Keyword(s):  
Change Detection ◽  
Rapid Development ◽  
Ratio Method ◽  
Small Scale ◽  
City Management ◽  
Spatiotemporal Resolution ◽  
Sar Images ◽  
Difference Image ◽  
Radar Images ◽  
Log Ratio

With the rapid development of urbanization in China, monitoring urban changes is of great significance to city management, urban planning, and cadastral map updating. Spaceborne synthetic aperture radar (SAR) sensors can capture a large area of radar images quickly with fine spatiotemporal resolution and are not affected by weather conditions, making multi-temporal SAR images suitable for change detection. In this paper, a new urban building change detection method based on an improved difference image and residual U-Net network is proposed. In order to overcome the intensity compression problem of the traditional log-ratio method, the spatial distance and intensity similarity are combined to generate a weighting function to obtain a weighted difference image. By fusing the weighted difference image and the bitemporal original images, the three-channel color difference image is generated for building change detection. Due to the complexity of urban environments and the small scale of building changes, the residual U-Net network is used instead of fixed statistical models and the construction and classifier of the network are modified to distinguish between different building changes. Three scenes of Sentinel-1 interferometric wide swath data are used to validate the proposed method. The experimental results and comparative analysis show that our proposed method is effective for urban building change detection and is superior to the original U-Net and SVM method.

scholarly journals Dam-Break Flows: Comparison between Flow-3D, MIKE 3 FM, and Analytical Solutions with Experimental Data

2018 ◽  
Vol 8 (12) ◽  
pp. 2456 ◽  
Author(s):  
Hui Hu ◽  
Jianfeng Zhang ◽  
Tao Li
Keyword(s):  
Experimental Data ◽  
Free Surface ◽  
Analytical Solution ◽  
Water Depth ◽  
3D Model ◽  
Real Life ◽  
Surface Profile ◽  
Dam Break ◽  
Computational Time ◽  
Free Surface Profile

The objective of this study was to evaluate the applicability of a flow model with different numbers of spatial dimensions in a hydraulic features solution, with parameters such a free surface profile, water depth variations, and averaged velocity evolution in a dam-break under dry and wet bed conditions with different tailwater depths. Two similar three-dimensional (3D) hydrodynamic models (Flow-3D and MIKE 3 FM) were studied in a dam-break simulation by performing a comparison with published experimental data and the one-dimensional (1D) analytical solution. The results indicate that the Flow-3D model better captures the free surface profile of wavefronts for dry and wet beds than other methods. The MIKE 3 FM model also replicated the free surface profiles well, but it underestimated them during the initial stage under wet-bed conditions. However, it provided a better approach to the measurements over time. Measured and simulated water depth variations and velocity variations demonstrate that both of the 3D models predict the dam-break flow with a reasonable estimation and a root mean square error (RMSE) lower than 0.04, while the MIKE 3 FM had a small memory footprint and the computational time of this model was 24 times faster than that of the Flow-3D. Therefore, the MIKE 3 FM model is recommended for computations involving real-life dam-break problems in large domains, leaving the Flow-3D model for fine calculations in which knowledge of the 3D flow structure is required. The 1D analytical solution was only effective for the dam-break wave propagations along the initially dry bed, and its applicability was fairly limited.

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