Search results for "fluid mechanics"
showing 10 items of 100 documents
Multicommutation as a powerful new analytical tool
2002
This review presents the state of the art of the emerging continuous-flow methodology based on solenoid valves. This uses flow networks to deliver sample and reagent solutions by controlling the time of flow through the ON/OFF modes of solenoid valves and takes advantage of existing flow injection analysis (FIA) or sequential injection analysis (SIA) device or manifold configurations. It allows one to insert a single plug of sample (or reagent) into the carrier or carrier-reagent stream, mimicking the approaches of FIA or SIA. In addition to the modes used in FIA and SIA, the methodology provides a different mode, based on delivery of a series of alternating sequential insertions of very sm…
Geometric approaches to particle physics
2008
Geometric approaches to particle physics have opened up new perspectives and unifying insights. After a few historical remarks I discuss the essence of the concept of G-theory: a primordial symmetry acting on a manifold and on the fields defined on it. This is then illustrated by the finite-dimensional case of Kaluza-Klein theories and by the infinite-dimensional case of chiral anomalies in Yang-Mills theories. In the latter case, a new and unifying description of topological and global anomalies is obtained.
Simultaneous dissolution profiles of two drugs in pharmaceutical formulations by an FIA manifold
2002
Abstract This article deals with the simultaneous determination of dissolution profiles of two drugs with overlapped spectra, present in the same pharmaceutical formulation. The official procedure for the dissolution profile is adapted to the continuous-flow methodology; the dissolution vessel is connected to an FIA manifold, in which the sample aliquots from the dissolution vessel are treated in order to adjust to the suitable pH and dilution degree to be monitored. The resulting solution is injected into the carrier stream, an acetic acid–acetate buffer at pH 4.3 and forced to the flow-cell of the spectrophotometer. The simultaneous determination of both profiles is based on the first der…
Active spike transmission in the neuron model with a winding threshold manifold
2012
International audience; We analyze spiking responses of excitable neuron model with a winding threshold manifold on a pulse stimulation. The model is stimulated with external pulse stimuli and can generate nonlinear integrate-and-fire and resonant responses typical for excitable neuronal cells (all-or-none). In addition we show that for certain parameter range there is a possibility to trigger a spiking sequence with a finite number of spikes (a spiking message) in the response on a short stimulus pulse. So active transformation of N incoming pulses to M (with M>N) outgoing spikes is possible. At the level of single neuron computations such property can provide an active "spike source" comp…
Classification générique de synthèses temps minimales avec cible de codimension un et applications
1997
In this article we consider the problem of constructing the optimal closed loop control in the time minimal control problem, with terminal constraints belonging to a manifold of codimension one, for systems of the form v = X + uY, v ϵ R2, R3, |u| ≤ 1 under generic assumptions. The analysis is localized near the terminal manifold and is motivated by the problem of controlling a class of chemical systems.
Comparison of implementations of the lattice-Boltzmann method
2008
AbstractSimplicity of coding is usually an appealing feature of the lattice-Boltzmann method (LBM). Conventional implementations of LBM are often based on the two-lattice or the two-step algorithm, which however suffer from high memory consumption and poor computational performance, respectively. The aim of this work was to identify implementations of LBM that would achieve high computational performance with low memory consumption. Effects of memory addressing schemes were investigated in particular. Data layouts for velocity distribution values were also considered, and they were found to be related to computational performance. A novel bundle data layout was therefore introduced. Address…
Technology in Mathematics Teaching
2019
This chapter introduces the chapter of the book, in situating it in a trajectory of two researchers.
Editorial – About a ‚PLATO‘
2017
While learning has constantly been an object of research in manifold disciplines and fields, it has generally been understood in a positive sense. In the Age of Information, we are witnessing an increasing number of phenomena in the context of knowledge construction and accumulation that we describe as “negative learning”. This includes, for example, the deliberate circulation of counterfactual knowledge leading to negative learning outcomes, i.e., deficient decision-making and acting, like medical errors.
Analyse expérimentale et numérique du comportement de véhicules terrestres en présence d'un vent latéral instationnaire
2013
The automotive manufacturers are nowadays more and more interested in crosswind aerodynamics. Indeed, the driver is subjected every day to strong side air flows, for example when overtaking another vehicle or when passing through a lateral wind wall, generated by terrain topography (as in the case of the passage near the empty space between two buildings).The aerodynamic efforts generated in these situations can lead to undesired lateral deviations,which can be dramatic if the driver is surprised. Different experimental studies, reproducing the effects of a dynamic yaw angle, pointed out the issues of the steady methods, commonly used to qualify the vehicle crosswind behaviour. Little is st…
Crisis and credit: social and political challenges of the Malian tea market
2020
This article examines the manifold facets of crisis situations in Mali since the 1990s. Most prominent was la crise, the political crisis of 2012 that resulted from the rise of armed separatist gro...