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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
11

Historický vývoj zanášení horní nádrže VD Nové Mlýny / Historical development of sediment deposition in upper reservoir of Nové Mlýny dam

Komorová, Magdaléna January 2020 (has links)
Master thesis is about historical deposition of sediments in the upper reservoir of Nové Mlýny from first fill up with water until present time. Beginning of the thesis concentrates on introduction of types of sediments and their behavior in rivers and reservoirs, sediment deposition in reservoirs and measures against sedimentation in reservoir. Part of the thesis consist of the creation of numerical one-dimensional model with transport of sediments on sections of rivers Dyje, Jevišovka and in the upper reservoir. Output data evaluation consist of analysis of sediment’s volume, development of bed in time and variation of bed evaluation in reservoir. Master thesis evaluates the development of water surface with different stages of sedimentation.
12

Stabilizace břehu zatopené pískovny u Hulína / Stabilization of the flooded sand pit near Hulín

Tomšej, Lukáš January 2022 (has links)
The diploma thesis assesses the current state of the Hulín gravel and sand plant and pays attention to abrasions of severely damaged banks of the reservoir. With the help of the design of a suitable biotechnical stabilization, the receding of the shoreline in the section of interest will be prevented. The basis for the processing of appropriate bank stabilization proposals is the results achieved using a method of determining shore retreat. The individual developed variants of the bank remediation solution emphasize the use of vegetation support, especially suitable bank stands to ensure the stability of the banks and protection against abrasion.
13

Constructed wetland for post-treatment of phosphorus in wastewater : An initial assessment of potential design and application to a small-scale water treatment plant in Åre municipality, Sweden

Arnemo, Johan January 2023 (has links)
In recent years, the treatment of phosphorus in Nyland's water treatment plant (located in Åre municipality) has been substandard. The problem has persisted despite attempts to lower the concentration to meet the emission requirements. A desire to find alternative, more environmentally friendly treatment methods has therefore been expressed from the municipality.Aside from the requirements, there is a desire to keep nutrient levels in the recipient (Indalsälven) low to preserve its natural state. A recognized method for treating wastewater is the use of constructed wetlands, where the characteristics of a natural wetland are enhanced and taken advantage of.The assessment of which type of constructed wetland that would be most beneficial to apply, was done by rating and weighting a number of characteristics of importance for lowering the phosphorus concentration. A first-order area-based model was used to estimate the size of the wetland.This report found that there is a suitable site to build a free water surface wetland in the vicinity of the water treatment plant. The wetland would act as a polishing step in the treatment train. As there is an element of uncertainty in treatment performance when a living ecosystem as wetlandis used, it is advised to enlarge this study and include more design aspects to refine the layout and configuration. / <p>2023-06-02</p>
14

Long-Term Nutrient Removal and Nutrient Mass Balance of a Free Water Surface Constructed Wetland Polishing Municipal Lagoon Effluent

Patel, Meetkumar 11 January 2023 (has links)
A large pilot-scale free water surface (FWS) constructed wetland polishing effluent from an annual (spring) discharge municipal lagoon was operated for ten years followed by eleven years of dormancy and then restarted with an increase in operating depth. No significant effect of system aging was observed on Biological Oxygen Demand (BOD), total phosphorus (TP), and soluble reactive phosphorus (SRP) removal efficiencies, although internal TP water column concentrations in the first wetland and pond cells increased with time due to resuspension of accumulated sediments. Nitrate and ammonium removal efficiencies were higher during the start-up period due to plant establishment, while organic nitrogen and nitrate removal efficiencies increased during the restart period, likely due to a combination of the increased operating depth and accumulated sediments. No seasonal temperature effect was observed for nitrate or BOD removal efficiency, however, TP removal efficiencies increased with increasing influent concentrations due to seasonal algae growth. TSS removal efficiency increased significantly during the restart period, most likely due to an increase in the operating depth. Phosphorus was found to be mostly stored in the soil, followed by sediment and plants, while nitrogen was found to be stored more in plants, followed by soil and sediment. The wetland system was shown to be effective at the long-term removal of organic matter (BOD5 < 10 mg/L) and TP (87% average removal efficiency), while TSS removal efficiency increased to 97% with an increase in operating depth from 25 to 50 cm.
15

Flow in Open Channel with Complex Solid Boundary

Guo, Yakun 20 July 2015 (has links)
yes / A two-dimensional steady potential flow theory is applied to calculate the flow in an open channel with complex solid boundaries. The boundary integral equations for the problem under investigation are first derived in an auxiliary plane by taking the Cauchy integral principal values. To overcome the difficulties of a nonlinear curvilinear solid boundary character and free water surface not being known a priori, the boundary integral equations are transformed to the physical plane by substituting the integral variables. As such, the proposed approach has the following advantages: (1) the angle of the curvilinear solid boundary as well as the location of free water surface (initially assumed) is a known function of coordinates in physical plane; and (2) the meshes can be flexibly assigned on the solid and free water surface boundaries along which the integration is performed. This avoids the difficulty of the traditional potential flow theory, which seeks a function to conformally map the geometry in physical plane onto an auxiliary plane. Furthermore, rough bed friction-induced energy loss is estimated using the Darcy-Weisbach equation and is solved together with the boundary integral equations using the proposed iterative method. The method has no stringent requirement for initial free-water surface position, while traditional potential flow methods usually have strict requirement for the initial free-surface profiles to ensure that the numerical computation is stable and convergent. Several typical open-channel flows have been calculated with high accuracy and limited computational time, indicating that the proposed method has general suitability for open-channel flows with complex geometry.
16

A non-invasive airborne wave monitor

Nichols, Andrew, Tait, Simon J., Horoshenkov, Kirill V., Shepherd, Simon J. January 2013 (has links)
This work presents a new acoustical method for remote measurement of the surface characteristics of the dynamic air-water interface in turbulent free-surface flows. The technique uses the reflection of a monochromatic ultrasonic wave by the dynamically rough air-water interface to measure the water surface position. It is found that with careful selection of the acoustical components and their configuration, the phase of the reflected signal responds to the local fluctuations in the fluid interface at the point of specular acoustic reflection. In order for the method to be applicable, three criteria must be satisfied: (1) the dominant wavelength of the surface under investigation must be greater than the first Fresnel zone corresponding to the wavelength and component geometry of the acoustical system; (2) the mean magnitude of the instantaneous local surface gradient must not exceed 0.025; and (3) the root-mean-square wave height must be greater than 1% of the acoustic wavelength. Under these conditions the mean error of the system is within 5% (and usually within 1%) of the acoustic wavelength, and is generally within 10% of the wave amplitude for turbulence generated waves, and 3% of the amplitude for gravity waves. This error may be reduced by optimising the acoustic wavelength for the surface of interest. For turbulent depth limited flows, the surface waves fall well within the criteria, and the absolute errors are independent of wave height, so for larger wave heights, the relative error can be considerably lower. The technique provides a robust system for monitoring the dynamics of free surface flows, which is non-invasive, low cost, and low power. The method has been tested on laboratory flows but should be applicable to remote sensing of free surface properties on a local scale in field environments where invasive techniques are difficult to implement such as might be found in coastal, river and wastewater environments.
17

EMG analýza vlivu vodního prostředí na rehabilitaci u pacientů s Parkinsonovou nemocí / An electromyographical analysis of the influence of water environment on the rehabilitation of patients with Parkinson's disease

Kotalíková, Kateřina January 2013 (has links)
Title: An electromyographical analysis of the influence of water environment on the rehabilitation of patients with Parkinson's disease Aims: The main aim of this Master's thesis was to compare electrical activity of selected muscles of patients with Parkinson's disease via electromyography during gate aground and in water environment. Furhter aim was to determine co-contraction level of leg muscles of patients with Parkinson's disease during gait aground and in water environment. Methods: This thesis is a case study, which was conducted on five probands, two of which were men and three women of age 67,4±7,1. With the use of surface electromyography, an activity was evaluated of m.tibialis anterior, m.gastrocnemius, m. rectus femoris, m. biceps femoris and mm. erectores spinae in place of Th -L junction. Acquired EMG signal was analized and then a standarized level of muscle activity during gait in different environments was evaluated, aground and in water, and afterward a dynamic co-contraction level was evaluated. Results: The results show consistent standardized activity of monitored muscles in water environment, which describes a chronic influence of pathological central program accompanying Parkinson's disease, where a change in coordination pattern is not observed, typical for movement in...
18

Vliv teploty vody na elektrickou aktivitu svalu / Effect of water temperature on the electrical activity of muscle

Novotná, Petra January 2011 (has links)
Title: Effect of water temperature on the electrical activity of muscle Objective: Main objective of this work is to determine the spatiotemporal changes in muscle activation depending on different properties of the environment. All this at a defined muscle power output. Measured by hand dynamometer. Methods: This is a case study. Is processed and analyzed the relationship of the forearm muscles against the aquatic environment (different temperatures - 15 řC, 24 řC and 35 řC) and against dry. Muscular power output is defined and measured by hand dynamometer. Muscular power output was determined as isometric contraction flexors of wrist and fingers of dominant hand. It all in three different modes. The research group were included 5 healthy individuals (3 women, 2 men). As objectivization method was determined surface electromyography. Findings: There is no influence of water temperature (15 řC, 24 řC and 35 řC) on spatiotemporal activation of muscle. It all at a defined muscle power output. There is also no changes on spatiotemporal activation of muscle in aquatic and dry. Keywords: muscle contraction, temperature, water environment, surface electromyography, Water Surface EMG
19

Investigating the potential of remote sensing for long-term limnological analysis at pan-continental scales

Politi, Eirini January 2010 (has links)
Lakes are key indicators of environmental change and major repositories of biodiversity and ecosystem services. However, studies of lake response to drivers of change at a pan-European scale are exceptionally rare. The need for such studies has been given renewed impetus by concerns over climate change and because of international policyrelated schemes, such as the EU Water Framework Directive that has made it legal requirement to repeatedly assess and monitor the ecological status of European lakes toward their effective management and sustainable use. This has introduced the need for methods that can be widely applied across large spatial and temporal scales and produce comparable results. Remote sensing is a promising method for providing such information, but the spatial transferability and temporal repeatability of methods and relationships observed remains untested. In this project, an extensive dataset of field measurements was compiled covering temperature, chlorophyll a and Secchi disk depth in 23 European lakes spanning the last 30 years. The characteristics of these lake systems were explored and similarities in their ecological behavior identified, thus providing the basis for their grouping. Then the potential of remote sensing for estimating and monitoring lake water quality at wide spatial and temporal scales was assessed and thus the long remote sensing archive at the NEODAAS DSRS was fundamental for the purposes of this project. Using NOAA AVHRR, Terra/Aqua MODIS and field data from lakes that represented three main lake groups, the spatial and temporal reliability of 26 existing water quality estimation algorithms was assessed. Following this, the best performing algorithms were applied to all study sites and the effect of scale and spatial resolution upon reliable estimation of key water quality parameters was evaluated. It was demonstrated that the NOAA AVHRR and Terra/Aqua MODIS were both capable of producing highly accurate (R2 &gt; 0.9) lake surface temperature estimates in lakes with variable characteristics and a variety of thermal spatial features, and longterm patterns within the study sites could be studied with NOAA AVHRR data despite the relatively coarse spatial resolution of the sensor. Restricting factors to the latter were the size and shape of lakes and the frequency of cloud cover. By contrast, the development of a universal Terra/Aqua MODIS algorithm for the estimation of chlorophyll a and Secchi disk depth in variable lakes was more challenging due to the optical complexity of Case II waters. Terra/Aqua MODIS data showed a potential, but the use of a different technique (e.g. multivariate regression or neural networks) and/or a different sensor (e.g. Envisat MERIS) could potentially improve the predictive accuracy of the algorithms.
20

Modellierung historischer Abflussverhältnisse für die Hochwasserprognose

Kirsch, Franziska, Pohl, Reinhard 11 February 2015 (has links) (PDF)
Um historische Durchflussangaben an Flüssen, die in die Hochwasserstatistik eingehen, überprüfen und bewerten zu können, werden 1-D- und 2-D-Wasserspiegellagenberechnungen unter Verwendung historischer morphologischer Daten durchgeführt. Die Methodik sowie ihre Möglichkeiten und Grenzen werden am Beispiel der Elbe im Stadtgebiet von Dresden erläutert.Es wird deutlich, dass die notwendigen Korrekturen auch Auswirkungen auf die Hochwasserstatistik und damit auf die Schutzgrade haben.

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