Discrete element modelling of fluidised bed spray granulation

A novel discrete element spray granulation model capturing the key features of fluidised bed hydrodynamics, liquid-solid contacting and agglomeration is presented. The model computes the motion of every individual particle and droplet in the system, considering the gas phase as a continuum. Micro scale processes such as particle-particle collisions, droplet-particle coalescence and agglomeration are directly taken into account by simple closure models. Simulations of the hydrodynamic behaviour of a batch granulation process are presented to demonstrate the potential of the model for creating\ud insight into the influence of several key process conditions such as fluidisation velocity, spray rate and spray pattern on powder product characteristics

Guide to the Linfield College Photograph Collection

This collection contains photographs, glass lantern and plastic slides, and film negatives depicting the many-layered facets of life at Linfield College on its McMinnville and Portland campuses. The photography features (without limit to): students, faculty and staff, commencements, guest speakers and performers, buildings, activities and clubs, athletics, the arts (studio and performance), residence life, social, and study scenes

Modelling of simultaneous mass and heat transfer with chemical reaction using the Maxwell-Stefan theory II. Non-isothermal study

In Part I a general applicable model has been developed which calculates mass and heat transfer fluxes through a vapour/gas-liquid interface in case a reversible chemical reaction with associated heat effect takes place in the liquid phase. In this model the Maxwell-Stefan theory has been used to describe the mass transport. Also in Part I the isothermal absorption of a pure gas A in a solvent containing a reactive component B has been studied. In this paper the influence of thermal effects on the mass transfer rates is investigated, with special attention to the concentrated systems. The thermal effects arise as a consequence of enthalpy changes due to phase transitions and chemical reaction. Account is taken of the influence of temperature gradients on (i) the solubility of the gaseous component in the liquid phase, (ii) the chemical reaction rate and (iii) the mass transfer coefficients in the liquid phase. Numerical simulations show that, when compared to the corresponding isothermal case, the thermal effects can affect the mass transfer rates by as much as a factor of 30. In case of high Lewis numbers the numerically calculated mass transfer rates can very well be predicted from an approximate analytical expression, which has been presented in this paper. In most cases this is also a reasonable estimate of the mass transfer rate in case the Lewis number equals unity. In case of a second-order chemical reaction it was shown that thermal effects may change the maximum enhancement factor and consequently shift the absorption from the instantaneous regime to the pseudo-first-order regime. Further, it is concluded that there may exist non-isothermal gas-li1uid absorption systems where minor changes in parameters appearing in the heat balance, e.g. binary mass transfer coefficients, chemical reaction rate constant, Lé number or heat transfer coefficients, may result in drastically altered system behaviour. For situations in which thermal effects are significant, also the vaporization of the liquid mixture should be taken into account, especially when the calculated interface temperature is near or exceeds the boiling temperature of the liquid

Weak localization in mesoscopic hole transport: Berry phases and classical correlations

We consider phase-coherent transport through ballistic and diffusive two-dimensional hole systems based on the Kohn-Luttinger Hamiltonian. We show that intrinsic heavy-hole light-hole coupling gives rise to clear-cut signatures of an associated Berry phase in the weak localization which renders the magneto-conductance profile distinctly different from electron transport. Non-universal classical correlations determine the strength of these Berry phase effects and the effective symmetry class, leading even to antilocalization-type features for circular quantum dots and Aharonov-Bohm rings in the absence of additional spin-orbit interaction. Our semiclassical predictions are quantitatively confirmed by numerical transport calculations

A numerical study of a method for measuring the effective in situ sound absorption coefficient

The accuracy of a method [Wijnant et al., “Development and applica- tion of a new method for the in-situ measurement of sound absorption”, ISMA 31, Leuven, Belgium (2010).], for measurement of the effective area-averaged in situ sound absorption coefficient is investigated. Based on a local plane wave assump- tion, this method can be applied to sound fields for which a model is not available. Investigations were carried out by means of finite element simulations for a typical case. The results show that the method is a promising method for determining the effective area-averaged in situ sound absorption coefficient in complex sound fields

Herijking EHS Noord-Holland : een toets vanuit het perspectief van ruimtelijke samenhang

De realisatie van de Ecologische Hoofdstructuur in de Provincie Noord-Holland ligt achter op schema. Hierom hebben Gedeputeerde Staten van Noord-Holland besloten te onderzoeken of via een herbegrenzing een groter deel van de EHS nog is te realiseren. De gebieden die in aanmerking komen voor herbegrenzing zijn beoordeeld op de ruimtelijke samenhang van het gebied zelf én de mate waarin het gebied bijdraagt aan de omgeving. Op basis van de analyses mag geconcludeerd worden dat de beoogde herbegrenzing in Noord-Holland goed is voor de ruimtelijke samenhang van de provinciale EHS. Tevens zijn er twee quick-scan analyses uitgevoerd die een positief beeld laten zien van de herbegrenzingen op het niveau van Natuurdoelen en in relatie tot Natura2000-gebieden

Azimuth axis optical alignment system Final report

Azimuth axis optical alignment system to monitor and measure attitude or angular position of remote object about azimuth axis using phase information imposed on returning beam of ligh

Larch Status A

LARCH is a model that is used by the Netherlands Environmental Assessment Agency (PBL) for ex-ante and ex-post evaluations of Dutch nature policies. LARCH generates the potential habitat networks of a species. LARCH will not predict the actual distribution of a specie

The density of states of chaotic Andreev billiards

Quantum cavities or dots have markedly different properties depending on whether their classical counterparts are chaotic or not. Connecting a superconductor to such a cavity leads to notable proximity effects, particularly the appearance, predicted by random matrix theory, of a hard gap in the excitation spectrum of quantum chaotic systems. Andreev billiards are interesting examples of such structures built with superconductors connected to a ballistic normal metal billiard since each time an electron hits the superconducting part it is retroreflected as a hole (and vice-versa). Using a semiclassical framework for systems with chaotic dynamics, we show how this reflection, along with the interference due to subtle correlations between the classical paths of electrons and holes inside the system, are ultimately responsible for the gap formation. The treatment can be extended to include the effects of a symmetry breaking magnetic field in the normal part of the billiard or an Andreev billiard connected to two phase shifted superconductors. Therefore we are able to see how these effects can remold and eventually suppress the gap. Furthermore the semiclassical framework is able to cover the effect of a finite Ehrenfest time which also causes the gap to shrink. However for intermediate values this leads to the appearance of a second hard gap - a clear signature of the Ehrenfest time.Comment: Refereed version. 23 pages, 19 figure