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Application of the optical flow method to velocity determination in hydraulic structure models
(2016)
As with most high-velocity free-surface flows, stepped spillway flows become self-aerated when the drop height exceeds a critical value. Due to the step-induced macro-roughness, the flow field becomes more turbulent than on a similar smooth-invert chute. For this reason, cascades are oftentimes used as re-aeration structures in wastewater treatment. However, for stepped spillways as flood release structures downstream of deoxygenated reservoirs, gas transfer is also of crucial significance to meet ecological requirements. Prediction of mass transfer velocities becomes challenging, as the flow regime differs from typical previously studied flow conditions. In this paper, detailed air-water flow measurements are conducted on stepped spillway models with different geometry, with the aim to estimate the specific air-water interface. Re-aeration performances are determined by applying the absorption method. In contrast to earlier studies, the aerated water body is considered a continuous mixture up to a level where 75% air concentration is reached. Above this level, a homogenous surface wave field is considered, which is found to significantly affect the total air-water interface available for mass transfer. Geometrical characteristics of these surface waves are obtained from high-speed camera investigations. The results show that both the mean air concentration and the mean flow velocity have influence on the mass transfer. Finally, an empirical relationship for the mass transfer on stepped spillway models is proposed.
Optical flow estimation is known from Computer Vision where it is used to determine obstacle movements through a sequence of images following an assumption of brightness conservation. This paper presents the first study on application of the optical flow method to aerated stepped spillway flows. For this purpose, the flow is captured with a high-speed camera and illuminated with a synchronized LED light source. The flow velocities, obtained using a basic Horn–Schunck method for estimation of the optical flow coupled with an image pyramid multi-resolution approach for image filtering, compare well with data from intrusive conductivity probe measurements. Application of the Horn–Schunck method yields densely populated flow field data sets with velocity information for every pixel. It is found that the image pyramid approach has the most significant effect on the accuracy compared to other image processing techniques. However, the final results show some dependency on the pixel intensity distribution, with better accuracy found for grey values between 100 and 150.
Optimization of the reaeration potential on embankment stepped spillways in skimming flow regime
(2008)
Optimierung des potentiellen Sauerstoffeintrags auf Treppenschussrinnen mit gemäßigter Neigung
(2009)
Sensitivity of phase detection techniques in aerated chute flows to hydraulic design parameters
(2012)
Hydraulic modeling is the classical approach to investigate and describe complex fluid motion. Many empirical formulas in the literature used for the hydraulic design of river training measures and structures have been developed using experimental data from the laboratory. Although computer capacities have increased to a high level which allows to run complex numerical simulations on standard workstation nowadays, non-standard design of structures may still raise the need to perform physical model investigations. These investigations deliver insight into details of flow patterns and the effect of varying boundary conditions. Data from hydraulic model tests may be used for calibration of numerical models as well. As the field of hydraulic modeling is very complex, this chapter intends to give a short overview on capacities and limits of hydraulic modeling in regard to river flows and hydraulic structures only. The reader shall get a first idea of modeling principles and basic considerations. More detailed information can be found in the references.
Inhaltsverzeichnis - Bachelorarbeiten
1. Testamentsgestaltung bei Patchworkfamilien – Lösungsansätze für typische
Praxisprobleme unter Berücksichtigung der Interessenlagen der Parteien
- Ronja Bundrock 4 - 58
2. Die Haftung des AG-Vorstands gegenüber der Gesellschaft in unterneh-
mensinternen und -externen Krisen
- Nico Kremers 59 - 122
3. The Relationship of the Ex-Ante Uncertainty about the Value of a Stock
and its IPO Underpricing – An Analysis of the German Market
- Lennard Pankok 123 - 179
4. Attractiveness Bias in Venture Capital – An Analysis of Investor Decision
Making in “Die Höhle der Löwen”
- Theresa Maria Weisheit 180 - 242
Inhaltsverzeichnis – Masterarbeiten
Erhöhung der Energieautarkie in der Backbranche – Anwendung von bidi-
rektionalem Laden und dessen Auswirkungen auf die Geschäftsprozesse
und Informationssysteme
- Jasper Spoede 243 - 355
Hochtemperaturtechnik
(1990)
Hochtemperaturtechnik. Interne Arbeitssitzung des GVC-Fachausschusses 'Hochtemperaturtechnik'
(1989)
Multi-interface level sensors and new development in monitoring and control of oil separators
(2006)
In the oil industry, huge saving may be made if suitable multi-interface level measurement systems are employed for effectively monitoring crude oil separators and efficient control of their operation. A number of techniques, e.g. externally mounted displacers, differential pressure transmitters and capacitance rod devices, have been developed to measure the separation process with gas, oil, water and other components. Because of the unavailability of suitable multi-interface level measurement systems, oil separators are currently operated by the trial-and-error approach. In this paper some conventional techniques, which have been used for level measurement in industry, and new development are discussed.
In Zeiten von Schnelllebigkeit ändern immer mehr Menschen bewusst ihren Umgang mit alltäglichen Dingen. Was dabei häufig in den Hintergrund rückt, ist das Thema "bewusste Kleidung". Beeinflusst durch sogenannte Fast-Fashion-Modeketten und Social Media leben wir in einer regelrechten Wegwerfgesellschaft. „Entschleunigen“ beschäftigt sich mit den Schattenseiten der Modeindustrie, zeigt aber ebenso (neue) Wege auf, die auf eine bessere Zukunft für uns und unsere Umwelt hoffen lassen. Aufgeteilt in zwei Kapitel gibt „Entschleunigen“ einen Einblick in den ökologischen und sozialen Fußabdruck der Modeindustrie und stellt zum anderen die Gegenseite vor, bei der Wert auf faire Produktion und Nachhaltigkeit gelegt wird. Das Buch „Entschleunigen“ soll über die Missstände in der Textilbranche informieren, jedoch im Umkehrschluss dazu motivieren, diese mit einfachen Mitteln zu verbessern.