Improvement of the method of combined plans for the analysis of channel re-formations of a water body on the example of the oka river section

The article discusses the ways of improving the method of combined plans for a water body channel reformations analysis on the example of a section of the Oka River. The main disadvantages of the existing classical approach to the analysis of channel processes through the channel surveys separate isobaths’combination are highlighted. A new approach to combining digital models of the river bed relief obtained from the hydrographic surveys results is proposed. Two directions of surface comparison are shown for the subsequent analysis of channel processes. For a qualitative assessment of channel changes, it is proposed to construct a new surface of vertical deformations and visualize it in color gradation or using lines of equal vertical deformations. For a quantitative assessment of channel processes, the use of a cartogram of vertical channel deformations is considered, and the numerical parameters for assessing the stability of the river channel are introduced. For the considered section of the Oka river channel, the main indicators of channel processes were obtained and analyzed using the proposed updated method. Separately, the calculation of the most optimal grid size was performed when constructing a cartogram of vertical channel deformations.

Passive Ultra High Frequency RFID sensor with reference tag for crack detection of aluminum alloy structure

It can be ensured safe and reliable operation of a metallic structure by monitoring the positions which are easy to crack. Because the channel changes with the environment, a tag sensor in the ultra high frequency (UHF) is vulnerable to interference. This paper aims to investigate the reliability of passive RFID sensor systems with a reference tag for crack detection of aluminum alloy structures when the condition of reading distance and surrounding environment changes. The impedance and gain of tags are simulated, which provides theoretical basis for experimental analysis. With an increase of crack depth, the impedance of the sensor tag shifts to the low frequency direction, and the reference tag changes slightly. When dual tags are placed orthogonally, the gain of the sensor tag changes greatly, which means that it is more sensitive to crack depth. The backscatter power of the sensor tag shows a decline trend, and the power of the reference tag remains unchanged. The sensor features a linear response with the variation of crack depth. The sensitivity of crack characterization is better when dual tags are placed orthogonally.

Optical and mathematical method for studying electrode discharge spots with a liquid electrode

High-speed visualization of the discharge with a liquid cathode, color image processing were performed. The area of cathode spots concentration was identified. Statistical characteristics of the distribution of cathode spots were obtained in order to determine the range in which the intensity code of the green color channel changes, the polygon function of the empirical distribution of the intensity code for the green color channel. The graphical dependence on the frequency of the cathode spot indication hit into the specified interval of the color intensity code was created.

The formation and geometry characteristics of boulder bars due to outburst floods triggered by overtopped landslide dam failure

Boulder bars are a common form of riverbed morphology that could be affected by landslide dams. However, few studies have focused on the formation and geometry characteristics of boulder bars due to outburst floods triggered by landslide dam failure. In such a way, eight group landslide dam failure experiments with a movable bed length of 4 to 7 times the dam length with 25 boulder bars were carried out. In addition, 38 boulder bars formed in the field triggered by four landslide dam failures were investigated. The aim of this paper is to study the formation and geometry characteristics of boulder bars along the riverbeds. The results show that boulder bars are formed after peak discharge of outburst flow. The number of boulder bars is 0.4 to 1.0 times the ratio of riverbed length to dam bottom length. Besides, boulder bars have the characteristic of lengthening upstream during the failure process. A boulder bar's upstream edge has a more extensive development than a boulder bar's downstream edge. The length of a boulder bar along the channel changes faster than the boulder bar's width and height. After the dam failure, the boulder bar's length is about 8 to 14 times its width. The relationship between the ratio of boulder bar length to width and the boulder bar's dimensionless length could be described with a hyperbolic equation. The dimensionless area of the boulder bar increases linearly with the dimensionless area of the river section, and the linear ratio is about 0.5. With the field data, this demonstrates that the formation and geometry characteristics of boulder bars in tests are consistent with the field boulder bars. Therefore, the results in this paper are credible and can be applied to the riverbed's geomorphological characteristics analysis triggered by overtopped landslide dam failure. The plentiful experimental and field data could contribute to the community boulder bar research.

Linkages Between Sinuosity Index and Flood Sustainability: A Study of Morna River (Maharashtra), India

The morphological changes in the river channel over periods that occur due to the flood events, affected the sinuosity index of the river channel. The river characteristic like sinuosity also determines the intensity of flood in a channel. Recent flood losses have increased as a result of variability in rainfall; simultaneously such problems are coming up with sustainable development. The attempted research study has been carried out to evaluate and understand the river channel changes and bank stability of the Morna river in Maharashtra. The research work also identified the pattern/planform of the river. Morna river meets Warna river near the Mangle village. Most of the streams in the upper basin area are non-perennial. The occurrence of floods takes place due to seasonal rainfall. An index of Sinuosity was used to analyze variation in river courses, as well as identify stability and instability. Therefore, this may facilitate predicting probable riverbank erosion sites and also support sustainable flood management planning for these sites during forthcoming flood events. The sinuosity index of the Morna river ranges from 1.09 to 1.44. The sinuosity indexes for the Morna river and tributaries of its sub-basins/watersheds have been calculated using geospatial techniques. The disparities in sinuosity indexes of the Morna basin and sub-watersheds having a good correlation with slope of the river , fluvial processes, water discharge and hydraulic aspects of the river channel. Seasonal potential flood risk for the agricultural land may be found at the confluence of the Warna river and its tributary Morna river when it receives heavy rainfall in upstream.

An Adaptive Decision Feedback Equalisation For Broadband Powerline Communication System

Power line networks can be used to increase accessibility of broadband communication services in developing countries. Nevertheless, power line networks are affected by stochastic channel alterations triggered by load connection and disconnection, branched line lengths, branches, etc. This impairment affects the implementation of Broadband Power Line Communication (BPLC) system. This paper therefore proposes an Adaptive Decision Feedback Equalisation (ADFE) technique to overcome the stochastic channel changes in powerline communication channels. An appropriate power-line channel model is selected and channel impulse responses are obtained from the selected channel model. The impulse responses are obtained and used for simulation to analysing the the performance of ADFE technique. The ADFE is simulated and then results are analyzed through comparisons with other equalizers in order to examine its performance. Simulation results prove that the adaptive decision feedback equalizer performs better to overcome the effects of stochastic changes in power-line network compared to other techniques.

Channel Width Variation Phases of the Major Rivers of the Campania Region (Southern Italy) over 150 Years: Preliminary Results

In recent decades, rivers in Southern Italy experienced remarkable channel changes. Studies on this topic are relatively recent, and yet, far from defining a morpho-evolutionary trend that is common to all rivers of this area. The types and roles of the different controlling factors are still debated. In this study, we present preliminary results about the width channel changes of major rivers in the Campania region (Southern Italy) in the last 150 years. The aim is to provide new insights that are useful to define morpho-evolutionary trajectories at a regional scale and shed light on the roles played by controlling factors. To this aim, we carried out a GIS-aided geomorphological analysis of topographic maps and orthophotos. The results showed the existence of at least three main phases of channel width variations. Between the 1870s and 1930s (Phase 1), most of the rivers experienced widening. Between the 1930s and late 1990s (Phase 2), all of the rivers underwent dramatic narrowing at high rates. Finally, from the 1990s onwards, no dominant trend was found and variations were negligible. Land-use changes at the basin scale and rainfall changes at a decadal scale are likely the main controlling factors, while variations in human disturbances and local factors seem responsible for changes in general trends.

Historical cartographic and topo-bathymetric database on the French Rhône River (17th–20th century)

Space and time analyses of channel changes, especially within large rivers subject to high levels of human impact, are critical to address multiple questions about rivers in the Anthropocene era. The reconstruction of long-term (> 150 year) evolutionary trajectories permits an understanding of how natural and anthropogenic factors impact hydromorphological and ecological processes in rivers, helps with the design of sustainable management and restoration options, and may also help in the assessment of future changes. However, the reconstruction of channel changes can be challenging: historical data are often scattered across many archives, and the quantity and accuracy of information generally decreases as one goes back in time. This data article provides a historical database of 350 cartographic and topo-bathymetric resources on the French Rhône River (530 km in length) compiled from the 17th to mid-20th century, with a temporal focus prior to extensive river training (1860s). The data were collected in 14 national, regional, and departmental archive services. A table describes the properties of each archived data item and its associated iconographic files. Some of the historical maps are available in a georeferenced format. A GIS layer enables one-click identification of all archive data available for a given reach of the French Rhône River. This database provides substantial new material for deeper analyses of channel changes over a longer time period and at a finer time step compared with previously available data. The database has several potential applications in geomorphology, retrospective hydraulic modelling, historical ecology, and river restoration, as well as permitting comparisons with other multi-impacted rivers worldwide. The dataset is available at https://doi.org/10.1594/PANGAEA.922437 (Arnaud et al., 2020a). Iconographic extracts of the 350 archived items are available at http://photo.driihm.fr/index.php/category/52 (last access: 2 May 2021).