112 research outputs found

    Paper 99: design guidelines versus practices for the Upper Seascheldt, the inland waterway connection between Antwerp and Ghent

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    Design guidelines for inland waterways are so far a national matter. PIANC InCom Working Group 141 "Design Guidelines for Inland Waterways" is nevertheless working on a report with a summary of existing guidelines and a methodology for the concept and detailed design of canals and rivers. For tidal rivers the design is a difficult process and an example is given through the accessibility of the Upper-Seascheldt for CEMT class IV and Va inland vessels between the port of Antwerp and the locks in Merelbeke. A combined evaluation based on concept design guidelines for canals, practices measured during a full-scale voyage and detailed design using ship handling simulators is discussed and illustrated

    Bank effects for KVLCC2

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    A study is presented on ship–bank interaction effects in which viscous-flow solvers are used to predict the hydrodynamic forces and moments on the ship. The ship under consideration is the KRISO Very Large Crude Carrier (KVLCC2). For this hull form, Flanders Hydraulics Research (FHR) has conducted shallow water model tests in their towing tank equipped with surface-piercing banks and a vertical quay wall. The forces and moments on the KVLCC2 model were obtained for various water depths and lateral distances to the banks. Additionally, the wave elevation was measured between the quay wall and the ship model. In this study, two different CFD codes are used to predict the loads on the KVLCC2 as a function of the water depth and lateral position in the channel. The effect of propeller suction and free surface modelling on the results is quantified. Furthermore, comparisons will be made with CFD results from literature and potential flow computations to highlight the benefits of each approach. It will be shown that with careful setup of the computations, reliable predictions of the ship–bank interaction effects can be obtained

    What is new in uremic toxicity?

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    Uremic syndrome results from a malfunctioning of various organ systems due to the retention of compounds which, under normal conditions, would be excreted into the urine and/or metabolized by the kidneys. If these compounds are biologically active, they are called uremic toxins. One of the more important toxic effects of such compounds is cardio-vascular damage. A convenient classification based on the physico-chemical characteristics affecting the removal of such compounds by dialysis is: (1) small water-soluble compounds; (2) protein-bound compounds; (3) the larger “middle molecules”. Recent developments include the identification of several newly detected compounds linked to toxicity or the identification of as yet unidentified toxic effects of known compounds: the dinucleotide polyphosphates, structural variants of angiotensin II, interleukin-18, p-cresylsulfate and the guanidines. Toxic effects seem to be typically exerted by molecules which are “difficult to remove by dialysis”. Therefore, dialysis strategies have been adapted by applying membranes with larger pore size (high-flux membranes) and/or convection (on-line hemodiafiltration). The results of recent studies suggest that these strategies have better outcomes, thereby clinically corroborating the importance attributed in bench studies to these “difficult to remove” molecules

    Three-dimensional Numerical Modeling and Computational Fluid Dynamics Simulations to Analyze and Improve Oxygen Availability in the AMC Bioartificial Liver

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    A numerical model to investigate fluid flow and oxygen (O(2)) transport and consumption in the AMC-Bioartificial Liver (AMC-BAL) was developed and applied to two representative micro models of the AMC-BAL with two different gas capillary patterns, each combined with two proposed hepatocyte distributions. Parameter studies were performed on each configuration to gain insight in fluid flow, shear stress distribution and oxygen availability in the AMC-BAL. We assessed the function of the internal oxygenator, the effect of changes in hepatocyte oxygen consumption parameters in time and the effect of the change from an experimental to a clinical setting. In addition, different methodologies were studied to improve cellular oxygen availability, i.e. external oxygenation of culture medium, culture medium flow rate, culture gas oxygen content (pO(2)) and the number of oxygenation capillaries. Standard operating conditions did not adequately provide all hepatocytes in the AMC-BAL with sufficient oxygen to maintain O(2) consumption at minimally 90% of maximal uptake rate. Cellular oxygen availability was optimized by increasing the number of gas capillaries and pO(2) of the oxygenation gas by a factor two. Pressure drop over the AMC-BAL and maximal shear stresses were low and not considered to be harmful. This information can be used to increase cellular efficiency and may ultimately lead to a more productive AMC-BAL

    Assessment of mass transfer efficiency in a hemodialyzer

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    Simulation study to assess the effect of ship beam on the navigable flow conditions in Paris

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    Traversing the river Seine in Paris is challenging for inland vessels due to the density and diversity of local traffic that is encountered in a confined environment. The waterway authority, Voies navigables de France (VNF), commissioned a study to assess the relevance of the current regulations when vessels of varying types cross Paris. A first simulation study showed that regulations based on length only may be too restrictive for ships with smaller beams [1]. This paper presents additional simulations executed on a full mission bridge simulator with ships of reduced beam. The main bottlenecks happen at different locations depending on the ship’s beam and ships with smaller beam can sail at higher water levels than the ships considered in the first study. The maximum water levels for which safe passage is possible were determined for each ship. Finally, recommendations have been formulated, which were then discussed with VNF and stakeholders

    Influence of composition and hot rolling parameters on the magnetic and mechanical properties of fully processed non-oriented low-Si electrical steels

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    The influence of composition (Si, Al, Mn, P and B) and hot rolling parameters on the properties of fully processed ultra-low carbon, low Si, non oriented electrical steels was investigated. Nine steels were examined. using twelve combinations of slab reheating temperature, finishing temperature and coiling temperature. It was found that maximisation of the polarisation through composition generally causes an increase in core losses. Hot band and final grain size influence the magnetic and mechanical properties more than composition. The grain boundary segregation of P results in finer grains and lower polarisations. Increasing the Mn and/or Al content coarsens the final grains as a result of coarser MnS and/or AIN precipitates
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