Modelling of flood waves based on wave propagation : algorithms with bed efflux and influx including a coupled-pipe network solver

Flood propagation over urban areas can cause an interaction between the free-surface flow and large underground pipe networks used for storm drainage and sewage, causing outflows and inflows at the bed. The associated waves may collide with each other and the surface waves. In this thesis the shallow water equations are used to model this type of wave interaction over dry or wet beds with bathymetry gradients and friction terms. The proposed shallow water scheme is solved based on finite volume high-resolution Godunov-type methods. The solver is well-balanced and can accurately balance the source terms and flux-gradients for the steady-state solutions. The solver also utilises a new type of Riemann wave speed to provide depth-positive results over nearly dry beds and dry states. Additionally a new type of source term is introduced in the continuity equation to model pipe inflow and outflow conditions at bed connections. For the standard one-dimensional shallow water equations the numerical results are validated with analytical solutions or other reference solutions provided in the literature. This includes the incipient Riemann problems for nearly dry and dry-states, steady flow over a hump in a rectangular channel and the wave propagation problem. Eventually, the generation of dry bed in the middle, over discontinuous topography is considered. Close agreement is achieved between the shallow water scheme and analytical or reference solutions for the above test cases. For the shallow water problems with influx/efflux source terms comparisons are made with STAR-CD, a commercial Navier-Stokes solver for general fluid flow prediction. The shallow water model is first used to simulate vertical flows through finite gaps in the bed. Next, the interaction of the vertical flows with a dam-break flow is considered for both dry and wet beds. An efflux number, En, is defined based on the vertical efflux velocity and the gap length. A parameter study is undertaken to investigate the effect of the one-dimensional approximation of the present model, for a range of non-dimensional efflux numbers. It is found that the shallow flow model gives sensible predictions at all times provided En0.5. Dam break flow over an underground connecting pipe is also considered for the one-dimensional efflux problems. To solve two-dimensional problems the shallow water scheme uses the dimensional-splitting method which solves each one-dimensional Riemann problem in the x- and y-directions separately. The cross-derivative terms for second-order accuracy are incorporated by solving another Riemann problem in the orthogonal direction. For two-dimensional problems first the dam-break problems are considered over wet and dry beds. Then, flood propagation over complex terrain is demonstrated. Next, efflux discharge is modelled in isolation over a dry bed and then with dam-break interaction, comparing with STAR-CD results. Again very good agreement is shown between the two-dimensional shallow water model and STAR-CD for the efflux numbers of En<0.5. For modelling the inundation problem over an underground pipe network the solver is coupled with the general underground pipe network solver to calculate the efflux discharge as the flood waves pass through the pipe network. For analysing the pipe network with unknown effluxes an additional set of equations is incorporated into the solution of a general pipe network solver. The shallow water solver coupled to an underground pipe network is then used to simulate dam-break interaction with pipe networks with 9 and 25 nodes to demonstrate the versatility of the method.EThOS - Electronic Theses Online ServiceGBUnited Kingdo

The Study of Environmental Problems Consideration in Guidance School Empirical Sciences Textbooks

The purpose of the present study is to analyze the content of the guidance school experimental sciences textbooks in Iran in terms of environmental problems consideration. For this purpose, three experimental sciences textbooks of guidance school were analyzed by using content analysis method. The statistical population is three experimental sciences textbooks of guidance school in the academic year of 2012-2013. Therefore, sampling method was not used in this study and the statistical population and sample population were the same. This study was done by using checklist content analysis tool including four major components such as environmental problems of air, water, soil and sound and 45 sub-components.  The William Scott formula was used to determine the reliability of data collection tool and its reliability amount was .82. The research findings showed that environmental problems are ignored in the guidance school experimental sciences textbooks. The most attention was paid to the environmental problems in the third grade experimental science textbook and the lowest attention was paid in the second grade experimental science textbook of guidance school. In relation to the environmental problems, the most attention was paid to the soil problems and the lowest attention was paid to sound problems in experimental sciences textbooks of guidance school. These findings necessitate paying attention to more important issue of the educational content formulating and editing by scientific and literary experts in educational content formulating regarding environmental problems in these books. Therefore, due to the industrialization path of today’s society and educational system evolution and review of the content of the textbooks, textbook authors should consider educational content

The Study of Environmental Problems Consideration in Guidance School Empirical Sciences Textbooks

The purpose of the present study is to analyze the content of the guidance school experimental sciences textbooks in Iran in terms of environmental problems consideration. For this purpose, three experimental sciences textbooks of guidance school were analyzed by using content analysis method. The statistical population is three experimental sciences textbooks of guidance school in the academic year of 2012-2013. Therefore, sampling method was not used in this study and the statistical population and sample population were the same. This study was done by using checklist content analysis tool including four major components such as environmental problems of air, water, soil and sound and 45 sub-components.  The William Scott formula was used to determine the reliability of data collection tool and its reliability amount was .82. The research findings showed that environmental problems are ignored in the guidance school experimental sciences textbooks. The most attention was paid to the environmental problems in the third grade experimental science textbook and the lowest attention was paid in the second grade experimental science textbook of guidance school. In relation to the environmental problems, the most attention was paid to the soil problems and the lowest attention was paid to sound problems in experimental sciences textbooks of guidance school. These findings necessitate paying attention to more important issue of the educational content formulating and editing by scientific and literary experts in educational content formulating regarding environmental problems in these books. Therefore, due to the industrialization path of today’s society and educational system evolution and review of the content of the textbooks, textbook authors should consider educational content

Discrete-Time Domain Modeling of a High-Power Medium-Voltage Resonant Converter

LLC resonant converters are widely used indiverse industrial applications, due in part to their highefficiency and high power density. In spite of their numerousadvantages, these converters are still considered themost challenging converters from a modeling and controlperspective. Several factors contribute to this complexity,including the nonlinear behavior and different operatingmodes. Therefore, a high-power medium-voltage resonantconverter is modeled in this manuscript, and its dynamicbehavior is investigated. The nonlinear model simulationperformed by MATLAB/Simulink and the electrical circuitsimulation performed by PLECS are then compared toverify the accuracy of the obtained model

Influence of T shape baffles arrangement on flow hydraulic characteristics in fishways

Hydraulic structures constructed along the rivers cause disturbances in the natural process of aquatic life and the ecosystem of the region. In order to solve this problem, fishway structure is widely used to facilitate the communication path between downstream and upstream of hydraulic structures crossing the river and to eliminate the inability of fish to swim upstream and also to facilitate their movement downstream of dams. The different types of this structure should be designed to absorb the type of migratory fish in the area and to pass them safely and out of the outlet, without injuring the fish or creating unnecessary delays for the adult spawning fish. Therefore, in the present study, in order to determine the optimal configuration of the T shape baffles used in the path, three types of arrangements were numerically simulated using OpenFOAM software and K-ε turbulence model. These three types of arrangements are consecutive, alternate and also reversed. Then, the results of the numerical model were validated by comparing it with the results of the related laboratory model. The findings indicate that the numerical model is in good agreement with the laboratory results. Among the three configurations, taking into account different factors, the reverse location of T-shaped baffles with 68.3% backwater, 86.2% flow at less than 0.5 m/s, 84.1% turbulent kinetic energy values less than 0.02 square meters per square second and also 61% energy dissipation percentage, had the best performance

A Quadratic Boost Converter Suitable for Fuel Cell-Powered Electric Vehicles

This study presents a non-inverting transformer-lessBoost converter with a higher voltage conversion ratio, resultingin quadratic growth of the output voltage with modest incrementsin the duty cycle rate. The continuous input current of thisconverter simplifies the input filter design and enhances fuelcells’ lifetime and stability. Additionally, compared to existingarchitectures, this converter reduces the voltage and currentstresses on semiconductor components, making it a promisingalternative to other quadratic Boost converters. As a result, thistopology appears to be a viable alternative for the remainingquadratic Boost converters. The inclusion of common-groundswitches, which eliminate the need for additional components forgate driver isolation, is one of the main features that make thistopology distinct. As a result, the converter fabrication cost andsize are reduced. The proposed converter’s steady-state analysis isthoroughly explained. Stresses placed on semiconductor devices.Then, a meaningful comparison between the proposed circuitand its counterparts is provided to understand this converter’sunique attributes

Sensitivity Analysis of Weakly Compressible Moving Particle Semi-Implicit Method in a Dam-Break Flow Simulation

Lagrangian approaches such as the Moving Particle Semi-Implicit method and Smoothed particle Hydrodynamics are the latest techniques in Computational Fluids Dynamics and have attracted the attention of many researchers. Due to the Lagrangian nature of such practices, they can simulate various problems with large deformations and a variety of boundary conditions which has led to their application in many complex engineering problems. Therefore, the accuracy of the results obtained using these methods is substantial, while various parameters affect the accuracy of the simulation. In this paper, the sensitivity of a dam-break flow simulated by the Weakly Compressible Moving Particle Semi-Implicit method associated with the particle size and Courant number is analyzed. The analysis is performed in two circumstances. First, the Courant number is fixed, and the sensitivity relative to particle size is investigated. Then, sensitivity relative to the Courant number is studied in fixed particle size. In general, it can be concluded that the smaller the particle size and Courant number, the higher accuracy and computational cost

Post-Traumatic Pulmonary Pseudocyst following Blunt Chest Trauma; a Case Report

Traumatic pulmonary pseudocyst is a rare complication of chest trauma that has been poorly documented and usually resolves without specific treatment. Here, we present a case of pulmonary pseudocyst in a child with chest trauma without obvious symptoms. It is important to consider this diagnosis in patients with chest trauma to avoid unnecessary invasive procedures