scholarly journals Temporal Variability of River Inflow to the Lake Baikal and Reservoirs of the Angara Cascade of HPS

2018 ◽  
Author(s):  
Keyword(s):  
Lake Baikal ◽  
Hydrological Regime ◽  
Statistical Characteristics ◽  
Optimum Control ◽  
Seasonal Fluctuations ◽  
Pair Correlations ◽  
The Matrix ◽  
Prolonged Observation ◽  
Discretization Interval

Main properties of long-term and seasonal fluctuations of runoff are studied based on the prolonged observation of the inflow to reservoirs of the Angarsk cascade of HPS. Statistical characteristics (parameters of distributions) of seasonal and annual inflow are estimated. The analysis of sequence of annual inflow to the Lake Baikal led to the conclusion about heterogeneity of the long-term fluctuations. It is shown that spatial variability of runoff value in the studied region, which is high, is defined by differences in conditions of the hydrological regime formation. This variability is expressed as the matrix of pair correlations characterized by small values. With the inflow to the Lake Baikal as an example, the parameters of a seasonal inflow for two uniform periods providing a possibility of stochastic modeling of the inflow with a discretization interval one month are estimated. For the months with negative values of an inflow, the application of the IV-type distribution of Pearson is recommended. The results received in the work are intended for the solution of the optimum control of the Angarsk reservoir cascade problems.

scholarly journals Long-term changes of river discharge regime in Latvia

2008 ◽  
Vol 39 (2) ◽  
pp. 133-141 ◽  
Author(s):  
Maris Klavins ◽  
Valery Rodinov
Keyword(s):  
Climate Variability ◽  
River Discharge ◽  
Water Resource Management ◽  
Regional Climate ◽  
Hydrological Regime ◽  
High Water ◽  
Regime Changes ◽  
Long Term Changes ◽  
Discharge Regime

The study of changes in river discharge is important for regional climate variability characterization and for development of an efficient water resource management system. The hydrological regime of rivers and their long-term changes in Latvia were investigated. Four major types of river hydrological regimes, which depend on climatic and physicogeographic factors, were characterized. These factors are linked to the changes observed in river discharge. Periodic oscillations of discharge, and low- and high-water flow years are common for the major rivers in Latvia. A main frequency of river discharge regime changes of about 20 and 13 years was estimated for the studied rivers. A significant impact of climate variability on the river discharge regime has been found.

scholarly journals Climatological and statistical characteristics of the Haines Index for North America

2007 ◽  
Vol 16 (2) ◽  
pp. 139 ◽  
Author(s):  
Julie A. Winkler ◽  
Brian E. Potter ◽  
Dwight F. Wilhelm ◽  
Ryan P. Shadbolt ◽  
Krerk Piromsopa ◽  
...  
Keyword(s):  
North America ◽  
Spatial Variability ◽  
Atmospheric Pressure ◽  
Statistical Characteristics ◽  
Potential Contribution ◽  
Extensive Analysis ◽  
Temperature And Humidity ◽  
Humidity Measurements ◽  
Operational Tool

The Haines Index is an operational tool for evaluating the potential contribution of dry, unstable air to the development of large or erratic plume-dominated wildfires. The index has three variants related to surface elevation, and is calculated from temperature and humidity measurements at atmospheric pressure levels. To effectively use the Haines Index, fire forecasters and managers must be aware of the climatological and statistical characteristics of the index for their location. However, a detailed, long-term, and spatially extensive analysis of the index does not currently exist. To meet this need, a 40-year (1961–2000) climatology of the Haines Index was developed for North America. The climatology is based on gridded (2.5° latitude × 2.5° longitude) temperature and humidity fields from the NCEP/NCAR reanalysis. The climatology illustrates the large spatial variability in the Haines Index both within and between regions using the different index variants. These spatial variations point to the limitations of the index and must be taken into account when using the Haines Index operationally.

Bedforms, bed material, and bedload transport in a salt-wedge estuary: Fraser River, British Columbia

1989 ◽  
Vol 26 (7) ◽  
pp. 1440-1452 ◽  
Author(s):  
R. A. Kostaschuk ◽  
M. A. Church ◽  
J. L. Luternauer
Keyword(s):  
British Columbia ◽  
River Discharge ◽  
Bedload Transport ◽  
Fraser River ◽  
Seasonal Fluctuations ◽  
Salt Wedge ◽  
Migration Rates ◽  
Material Load ◽  
Bed Material

The lower main channel of the Fraser River, British Columbia, is a sand-bed, salt-wedge estuary in which variations in velocity, discharge, and bedform characteristics are contolled by river discharge and the tides. Bed-material composition remains consistent over the discharge season and in the long term. Changes in bedform height and length follow but lag behind seasonal fluctuations in river discharge. Migration rates of bedforms respond more directly to river discharge and tidal fall than do height and length. Bedform characteristics were utilized to estimate bedload transport in the estuary, and a strong, direct, but very sensitive relationship was found between bed load and river discharge. Annual bedload transport in the estuary is estimated to be of the order of 0.35 Mt in 1986. Bedload transport in the estuary appears to be higher than in reaches upstream, possibly because of an increase in sediment movement along the bed to compensate for a reduction in suspended bed-material load produced by tidal slack water and the salt wedge.

Entropy estimation of the fragments of chest X-ray images

2021 ◽  
pp. 20-26
Author(s):  
Aleksei Aleksandrovich Rumyantsev ◽  
Farkhad Mansurovich Bikmuratov ◽  
Nikolai Pavlovich Pashin
Keyword(s):  
Neural Network ◽  
Neural Networks ◽  
Binary Classification ◽  
Statistical Characteristics ◽  
Type I ◽  
Deep Convolutional Neural Networks ◽  
Preliminary Calculation ◽  
X Ray ◽  
The Matrix ◽  
Chest X Ray

The subject of this research is medical chest X-ray images. After fundamental pre-processing, the accumulated database of such images can be used for training deep convolutional neural networks that have become one of the most significant innovations in recent years. The trained network carries out preliminary binary classification of the incoming images and serve as an assistant to the radiotherapist. For this purpose, it is necessary to train the neural network to carefully minimize type I and type II errors. Possible approach towards improving the effectiveness of application of neural networks, by the criteria of reducing computational complexity and quality of image classification, is the auxiliary approaches: image pre-processing and preliminary calculation of entropy of the fragments. The article provides the algorithm for X-ray image pre-processing, its fragmentation, and calculation of the entropy of separate fragments. In the course of pre-processing, the region of lungs and spine is selected, which comprises approximately 30-40% of the entire image. Then the image is divided into the matrix of fragments, calculating the entropy of separate fragments in accordance with Shannon’s formula based pm the analysis of individual pixels. Determination of the rate of occurrence of each of the 255 colors allows calculating the total entropy. The use of entropy for detecting pathologies is based on the assumption that its values differ for separate fragments and overall picture of its distribution between the images with the norm and pathologies. The article analyzes the statistical values: standard deviation of error, dispersion. A fully connected neural network is used for determining the patterns in distribution of entropy and its statistical characteristics on various fragments of the chest X-ray image.

scholarly journals Exploring and Quantifying River Thermal Response to Heatwaves

Water ◽  
2018 ◽  
Vol 10 (8) ◽  
pp. 1098 ◽  
Author(s):  
Sebastiano Piccolroaz ◽  
Marco Toffolon ◽  
Christopher Robinson ◽  
Annunziato Siviglia
Keyword(s):  
Water Temperature ◽  
River Water ◽  
Thermal Response ◽  
Hydrological Regime ◽  
Management Policy ◽  
Extreme Weather Events ◽  
Thermal Dynamics ◽  
Depth Analysis ◽  
River Water Temperature

Most of the existing literature on river water temperature focuseds on river thermal sensitivity to long-term trends of climate variables, whereas how river water temperature responds to extreme weather events, such as heatwaves, still requires in-depth analysis. Research in this direction is particularly relevant in that heatwaves are expected to increase in intensity, frequency, and duration in the coming decades, with likely consequences on river thermal regimes and ecology. In this study we analyzed the long-term temperature and streamflow series of 19 Swiss rivers with different hydrological regime (regulated, low-land, and snow-fed), and characterized how concurrent changes in air temperature and streamflow concurred to affect their thermal dynamics. We focused on quantifying the thermal response to the three most significant heatwave events that occurred in Central Europe since 1950 (July–August 2003, July 2006, and July 2015). We found that the thermal response of the analyzed rivers contrasted strongly depending on the river hydrological regime, confirming the behavior observed under typical weather conditions. Low-land rivers were extremely sensitive to heatwaves. In sharp contrast, high-altitude snow-fed rivers and regulated rivers receiving cold water from higher altitude hydropower reservoirs or diversions showed a damped thermal response. The results presented in this study suggest that water resource managers should be aware of the multiple consequences of heatwave events on river water temperature and incorporate expected thermal responses in adaptive management policy. In this respect, additional efforts and dedicated studies are required to deepen our knowledge on how extreme heatwave events can affect river ecosystems.

The Relationship Between Magnetism and Microstructure of Ethylene Pyrolysis Furnace Tubes after a Long-term Service

2018 ◽  
Vol 24 (5) ◽  
pp. 478-487 ◽  
Author(s):  
Jingfeng Guo ◽  
Tieshan Cao ◽  
Congqian Cheng ◽  
Xianming Meng ◽  
Jie Zhao
Keyword(s):  
Saturation Magnetization ◽  
Outer Region ◽  
Cr Content ◽  
Pyrolysis Furnace ◽  
The Matrix ◽  
Furnace Tube ◽  
Primary Carbides ◽  
The Relationship ◽  
Very High

AbstractThe magnetism and microstructure of Cr25Ni35Nb and Cr35Ni45Nb alloy tubes after 5 years of service were investigated in this paper. The saturation magnetization of the Cr25Ni35Nb alloy tube in the thickness direction is more than 20 emu/g, and the tube becomes ferromagnetic. The inner and outer walls of Cr35Ni45Nb alloy tubes also become ferromagnetic. But the saturation magnetization of the Cr35Ni45Nb alloy tubes approaches to zero in the center zone. The primary carbides M7C3 and NbC are changed into M23C6 and G phase at the outer region of the furnace tube. However, the M23C6-type carbides were replaced by carbon-rich carbides M7C3 at the carburization zone. Cr-depleted zones are formed at the inner and outer walls of the furnace tubes owing to oxidation. Carburization and oxidation reduce the Cr content of the matrix. Accordingly, the saturation magnetization is very high at the carburization zone and Cr-depleted zone. The magnetism of Cr25Ni35Nb and Cr35Ni45Nb alloy tubes has a high correlation with the Cr content of the matrix. Carburization and oxidation are the main reasons that make the paramagnetic ethylene pyrolysis furnace tube change to ferromagnetic.

scholarly journals Longer Growing Seasons Cause Hydrological Regime Shifts in Central European Forests

Forests ◽  
2021 ◽  
Vol 12 (12) ◽  
pp. 1656
Author(s):  
Petr Kupec ◽  
Jan Deutscher ◽  
Martyn Futter
Keyword(s):  
Regime Shift ◽  
Hydrological Regime ◽  
Annual Runoff ◽  
Order Effects ◽  
Runoff Generation ◽  
Central European ◽  
European Forests ◽  
Water Limitation ◽  
Growing Seasons

In this study, we present evidence for a hydrological regime shift in upland central European forests. Using a combination of long-term data, detailed field measurements and modelling, we show that there is a prolonged and persistent decline in annual runoff: precipitation ratios that is most likely linked to longer growing seasons. We performed a long term (1950–2018) water balance simulation for a Czech upland forest headwater catchment calibrated against measured streamflow and transpiration from deciduous and coniferous stands. Simulations were corroborated by long-term (1965–2018) borehole measurements and historical drought reports. A regime shift from positive to negative catchment water balances likely occurred in the early part of this century. Since 2007, annual runoff: precipitation ratios have been below the long-term average. Annual average temperatures have increased, but there have been no notable long term trends in precipitation. Since 1980, there has been a pronounced April warming, likely leading to earlier leaf out and higher annual transpiration, making water unavailable for runoff generation and/or soil moisture recharge. Our results suggest a regime shift due to second order effects of climate change where increased transpiration associated with a longer growing season leads to a shift from light to water limitation in central European forests. This will require new approaches to managing forests where water limitation has previously not been a problem.

scholarly journals Floristic composition and taxonomic structure of algae in the hyperhaline reservoirs of the northwestern Azov Sea coast (Ukraine)

Algologia ◽  
2020 ◽  
Vol 30 (4) ◽  
pp. 393-405
Author(s):  
A.M. Solonenko ◽  
◽  
O.G. Bren ◽  
Keyword(s):  
Water Exchange ◽  
Salt Water ◽  
Floristic Composition ◽  
Hydrological Regime ◽  
Taxonomic Structure ◽  
Azov Sea ◽  
The Family ◽  
Saline Habitats ◽  
Saline Land

The article represents the results of long-term algological studies of hyperhaline reservoirs of the northwestern coast of the Azov Sea. The features of the floristic composition and taxonomic structure of algae in aquatic (water column and bottom), aquatic-terrestrial (water’s edge, dried up water bodies, drying area) and terrestrial (elevated non-flooding areas) habitats of these objects are displayed. A specificity of the studied algoflora lies in the absence of representatives of certain characteristic phyla for the salt-water and non-saline land and water habitats of the territory of Ukraine. It was established that species composition of the studied reservoirs is depleted in comparison with other non-saline and marine ecosystems. Totally, 123 algae species were identified. They represente 7 phyla, 10 classes, 27 orders, 47 families, 68 genera. The largest number of species included three phyla: Cyanoprocaryota – 65 species (52.9% of the total number of identified species), Bacillariophyta – 26 (21.1%), Chlorophyta – 22 (17.9%). The first places among the six leading orders were taken by cyanoprocaryotes from Oscillatoriales, Nostocales, Chroococcales and diatoms from Naviculales. The most numerous species at the family level are trichomous cyanoprocaryotes from Nostocaceae, Pseudanabaenaceae, and Phormidiaceae. There were found 23 leading genera – their species richness exceeds the average indicator (1.81 species). According to the results of original studies, it was noted that all taxonomic levels of algoflora of the hyperhaline reservoirs shows features of not only saline habitats, but also of the freshwater, marine and terrestrial extreme ecosystems. Such diversity of the algal population indicates an unstable hydrological regime and complex relations of water exchange between the hyperhaline reservoirs and nearby terrestrial and aquatic habitats.

scholarly journals Fishery in the Tobol-Ishim interfluve in the neolithic and early metal age

2018 ◽  
Vol 7 (4) ◽  
pp. 182-192
Author(s):  
Viktor Alekseevich Zakh
Keyword(s):  
Water Level ◽  
Bronze Age ◽  
Iron Age ◽  
Life Support ◽  
Hydrological Regime ◽  
Economic Activities ◽  
Deep Foundation ◽  
Metal Age ◽  
North Western

Landscapes of the Tobol-Ishim interfluve were not stable in the Holocene and varied from forests and drowned floodplains at the beginning of the V and III millennia BC to steppificated territories with a lowered water level at the beginning of the Atlantic Period and in the middle of the Subboreal Period, which determined the main types of economic activities, one of them was fishing. Changes in hydrological regime of water bodies influenced the methods of fishing, including the use of different traps. Thus, in the Neolithic, when the water level decreased, the location of settlements in the system river-creek-lake (for example, Mergen 6), a large number of fish bones, bone harpoons, fishing spears, fishing tackles for catching pike and a total absence of plummets were indicative of individual fishing for large fish and, perhaps, of stop net fishery, which was facilitated by a decrease in the width of watercourses and tombolos. Stop net (stake net) fishery led to a settled lifestyle of the population, collective activities and the emergence of long-term settlements with deep foundation pits of dwellings. When the water level in rivers and lakes increased and floods became more frequent, the life support system changed, the population began to develop coasts more widely, its mobility increased, and they started to build framed above-ground dwellings. Following those changes, biconic, cigar-shaped, and corniculate plummets emerged in the Tobol River Basin and on the adjacent western and north-western territories in the III and early II millennium BC. When the water level was high, it was efficient to fish using traps, seines and, probably, nets, although the latter could also be used in drive hunting for shedding geese and ducks. Subrectangular plummets with one or two ties for fastening, and disk-shaped plummets with a tie in the center had been prevailing since the beginning of the II millennium BC; they existed until the first third of the I millennium BC. This period, the transition time from the Bronze Age to the Early Iron Age, is characterized by the absence of clay plummets, while there are large accumulations of fish scales and bones in the settlement layers. We can suppose that the population of that time (local Late Bronze Age population, mixed with northern migrants who made utensils with cross ornamentation) switched from net fishing to stop net fishing.

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