Search results for "Diss"
showing 10 items of 2500 documents
Development and validation of a nonlinear dynamic impact model for a notch impact
2015
Finite element simulations are being more and more applied when studying the crash-worthiness of vehicles during impact. This paper deals with setting up such a simulation and discusses several ways to simplify and verify a simulated crash. For this purpose, a notch impact-testing machine will be released from a certain angle and crash into a model constructed with three different wall thicknesses. The plastic and elastic deformation is measured in the front of the model and is then used for validation of the simulation. In the end, the simulation was found to be in good agreement with the real crash data.
New Expression of the Hydraulic Jump Roller Length
2012
AbstractThis paper presents the results of an experimental investigation on the roller length of both classical and B-jumps on smooth beds. Using the measurements conducted in this investigation and those available in the literature, a new relationship is proposed for estimating the roller length of classical and B-jumps on smooth beds. Finally, it is demonstrated that the proposed equation is also applicable to estimate the roller length of hydraulic jumps on rough horizontal beds.
Hydraulic jumps on rough beds
2007
This paper presents the results of an experimental investigation on the hydraulic jump on horizontal rough beds. Experiments were carried out to study the effect of bed roughness on both the sequent depth ratio and the roller length. The investigation allowed the writers to positively test the reliability of a new solution of the momentum equation for the sequent depth ratio as a function of the Froude number and the ratio between the roughness height and the upstream supercritical flow depth. The applicability of some empirical relationships for estimating the roller length was also tested.
How Circular Dichroism in Time- and Angle-Resolved Photoemission Can Be Used to Spectroscopically Detect Transient Topological States in Graphene
2020
Pumping graphene with circularly polarized light is the archetype of light-tailoring topological bands. Realizing the induced Floquet-Chern-insulator state and demonstrating clear experimental evidence for its topological nature has been a challenge, and it has become clear that scattering effects play a crucial role. We tackle this gap between theory and experiment by employing microscopic quantum kinetic calculations including realistic electron-electron and electron-phonon scattering. Our theory provides a direct link to the build up of the Floquet-Chern-insulator state in light-driven graphene and its detection in time- and angle-resolved photoemission spectroscopy (ARPES). This approac…
On the validity of non-Markovian master equation approaches for the entanglement dynamics of two-qubit systems
2010
In the framework of the dissipative dynamics of coupled qubits interacting with independent reservoirs, a comparison between non-Markovian master equation techniques and an exact solution is presented here. We study various regimes in order to find the limits of validity of the Nakajima–Zwanzig and the time-convolutionless master equations in the description of the entanglement dynamics. A comparison between the performances of the concurrence and the negativity as entanglement measures for the system under study is also presented.
Trace element fractionation through halite crystallisation: Geochemical mechanisms and environmental implications
2019
Halite is an important mineral for industry, agriculture and food production. It crystallises after water evaporation, while the progressive growth of dissolved metal ions in brines is occurring. Then, halite exploitation may provide the delivery of metal ions in the environment and the mechanism of this trace element accumulation should be studied. In this work we investigate the distribution of lanthanides and Y (hereafter named Rare Earth Elements, REE), Zr and Hf between crystallising halite and brines in the Dead Sea as geochemical tools for recognising the mechanism of metal ion removal from brines and accumulation in halite. Halite forms cubic crystals where octahedral planes sometim…
Simulation and control of dissolved air flotation and column froth flotation with simultaneous sedimentation.
2020
Abstract Flotation is a separation process where particles or droplets are removed from a suspension with the aid of floating gas bubbles. Applications include dissolved air flotation (DAF) in industrial wastewater treatment and column froth flotation (CFF) in wastewater treatment and mineral processing. One-dimensional models of flotation have been limited to steady-state situations for half a century by means of the drift-flux theory. A newly developed dynamic one-dimensional model formulated in terms of partial differential equations can be used to predict the process of simultaneous flotation of bubbles and sedimentation of particles that are not attached to bubbles. The governing model…
Mesophilic co-digestion of dairy manure and lipid rich solid slaughterhouse wastes: process efficiency, limitations and floating granules formation.
2014
Lipid and protein rich solid slaughterhouse wastes are attractive co-substrates to increase volumetric biogas production in co-digestion with dairy manure. Addition of decanter sludge (DS), containing 42.2% of lipids and 35.8% of proteins (total solids basis), up to 5% of feed mixture resulted in a stable process without any indication of long chain fatty acids (LCFA) or free ammonia (NH3) inhibition and in 3.5-fold increase of volumetric biogas production. Contrary, only lipids addition as technical fat (TF) at over 2% of feed mixture resulted in formation of floating granules (FG) and process efficiency decrease. Formed FG had low biodegradability and its organic part was composed of lipi…
An extension of ASM2d including pH calculation
2003
This paper presents an extension of the Activated Sludge Model No. 2d (ASM2d) including a chemical model able to calculate the pH value in biological processes. The developed chemical model incorporates the complete set of chemical species affecting the pH value to ASM2d describing non-equilibrium biochemical processes. It considers the system formed by one aqueous phase, in which biochemical processes take place, and one gaseous phase, and is based on the assumptions of instantaneous chemical equilibrium under liquid phase and kinetically governed mass transport between the liquid and gas phase. The ASM2d enlargement comprises the addition of every component affecting the pH value and an i…
Colloidal stability of nanoparticles derived from simulated cloud-processed mineral dusts
2013
AbstractLaboratory simulation of cloud processing of three model dust types with distinct Fe-content (Moroccan dust, Libyan dust and Etna ash) and reference goethite and ferrihydrite were conducted in order to gain a better understanding of natural nanomaterial inputs and their environmental fate and bioavailability. The resulting nanoparticles (NPs) were characterised for Fe dissolution kinetics, aggregation/size distribution, micromorphology and colloidal stability of particle suspensions using a multi-method approach. We demonstrated that the: (i) acid-leachable Fe concentration was highest in volcanic ash (1mMg−1 dust) and was followed by Libyan and Moroccan dust with an order of magnit…