Shock wave/turbulent boundary layer interaction in the flow field of a tri-dimension wind tunnel

The first results of a thorough experimental analysis of a strong three-dimensional shock-wave/turbulent boundary-layer interaction occurring in a three dimensional transonic channel are presented. The aim of this experiment is to help in the physical understanding of a complex field, including several separations, and to provide a well documented case to test computational methods. The flowfield has been probed in many points by means of a three-component laser Doppler velocimeter. The results presented relate only to the mean velocity field. They clearly show the formation in the flow of a strong vortical motion resulting from the shock wave interaction

Omgaan met robotisering en digitalisering. We hoeven het wiel niet opnieuw uit te vinden

Contains fulltext : 147369.pdf (author's version ) (Open Access)Veel van de huidige discussies over robotisering en arbeidsmarkt doen denken aan discussies van vroeger: over ‘wetenschappelijk bedrijfsbeheer’ in de jaren tien en twintig van de vorige eeuw, over automatisering in de jaren zestig en over micro-elektronica in de jaren tachtig. De omstandigheden waren steeds anders, maar de dilemma’s min of meer dezelfde. We hebben daarvan kunnen leren dat ‘winnaars en verliezers’ niet zozeer het gevolg zijn van technologische ontwikkelingen alswel van hoe belanghebbenden arbeid en arbeidsmarkt organiseren. De gekozen oplossingen zijn steeds min of meer hetzelfde: functieverbetering, werkoverleg, competentieontwikkeling en medezeggenschap op organisatieniveau, sociale dialoog op sector- en landelijk niveau, aangevuld met stimuleringsregelingen van de overheid, onderzoek en maatschappelijk debat. En natuurlijk moet het onderwijs meebewegen en anticiperen. We hoeven dus niet het wiel opnieuw uit te vinden. Hoe de toekomst eruit zal zien is moeilijk te voorspellen. We kunnen dan ook maar beter inzetten op het creëren van het optimale innovatie- en veranderpotentieel. Een samenleving die dat breed heeft weten te realiseren kan elke ontwikkeling en verrassing aan

Noncooperative Collusion and Price Wars with Individual Demand Fluctuations

We analyze whether noncooperative collusive equilibria are harder to sustain when individual demand levels are not fixed but are able to fluctuate. To do this, we extend a Bertrand type model of price competition to allow for fluctuating market shares when prices are equal. We find that, the larger the market share fluctuations may be, the higher the discount factor should be to sustain a collusive equilibrium in trigger strategies. The intuition behind this is fairly straightforward. When individual demand in the collusive state is suddenly low, the gains from collusion go down. Moreover, the firm with the low demand can capture a larger share of the market by deviating from the collusive strategy. The incentive to deviate therefore becomes larger when the individual market share decreases. We also look at the existence of a specific type of semi-collusive equilibrium when individual market shares are either common knowledge or private knowledge. We find that there exist equilibria in which competitive periods (price wars) occur with probability 1 and on the equilibrium path.mathematical economics;

Competition versus Collusion: The Impact of Consumer Inertia

We consider a model of dynamic price competition to analyze the impact of consumer inertia on the ability of firms to sustain high prices. Three main consequences are identified, all of which contrast with predictions of the standard model of collusion: (i) maintaining high prices does not require punishment strategies when firms are sufficiently myopic, (ii) if buyers are sufficiently inert, then high prices can be sustained for all discount factors, and (iii) the ability to maintain high prices may depend non-monotonically on the level of the discount factor when the industry exhibits network externalities and demand is sufficiently viscous. These results provide a number of interesting insights with regard to competitive and collusive pricing behavior. In particular, we illustrate how direct communication between firms may facilitate collusion.microeconomics ;

Contingent Employment in the Netherlands

In the last decade the Dutch labour market has demonstrated an admirable capacity to generate jobs. Consequently, the unemployment rate has significantly decreased. However, the newly generated jobs are a-typical in the sense that they are not full-time jobs based on open-ended contracts. Instead, the job growth has relied on the growth of part-time and contingent jobs. While the creation of part-time jobs seems to be employee-driven, contingent employment, in contrast, seems to be driven by motives of employers to gain numerical flexibility. Data from the Netherlands show that, with the exception of student workers, contingent work is predominantly involuntary.This paper analyses the growth of contingent employment in the Netherlands.flexibility;'temps';contingent employment;labour market policies;temporary work agencies

De bespeelbaarheid van grassportvelden : toetsing van enkele criteria op grassportvelden in Friesland in het najaar van 1976 en het voorjaar van 1977

De gevoeligheid van de grond voor verdichten wordt sterk beïnvloed door de granulaire samenstelling, het humusgehalte en de vochtspanning. Op grassportvelden is bovendien de kwaliteit van de graszode van invloed op de gevoeligheid voor verdichten en daardoor op de bespeelbaarheid. Een redelijke indicatie voor de dichtheid van de zode is de bedekkingsgraad. De bedekkingsgraad wordt sterk beïnvloed door de bespelingsintensiteit

Simulating microbial degradation of organic matter in a simple porous system using the 3-D diffusion-based model MOSAIC

This paper deals with the simulation of microbial degradation of organic matter in soil within the pore space at a microscopic scale. Pore space was analysed with micro-computed tomography and described using a sphere network coming from a geometrical modelling algorithm. The biological model was improved regarding previous work in order to include the transformation of dissolved organic compounds and diffusion processes. We tested our model using experimental results of a simple substrate decomposition experiment (fructose) within a simple medium (sand) in the presence of different bacterial strains. Separate incubations were carried out in microcosms using five different bacterial communities at two different water potentials of −10 and −100 cm of water. We calibrated the biological parameters by means of experimental data obtained at high water content, and we tested the model without changing any parameters at low water content. Same as for the experimental data, our simulation results showed that the decrease in water content caused a decrease of mineralization rate. The model was able to simulate the decrease of connectivity between substrate and microorganism due the decrease of water content

Développement d’une solution d’informatique décisionnelle au sein de Guérin et Guinnard électricité SA

Ce travail a pour mission la création d’une solution d’informatique décisionnelle au sein de Guérin et Guinnard électricité SA. Comme décrit dans le mandat du travail de Bachelor, ce projet est constitué de plusieurs objectifs. Le principal est celui de délivrer une application à l’entreprise, utile à la prise de décisions. Les objectifs accessoires sont l’établissement d’un état des lieux du matériel informatique et du système d’information, une analyse des besoins selon les informations dont l’entreprise dispose ou peut disposer et l’élaboration d’une solution pour la création d’une application. (Pot, Mandat du travail de Bachelor, 2013) La méthodologie consiste, dans un premier temps, à établir à un état des lieux du système d’informations. Avec les informations disponibles, une solution est conçue en collaboration avec les exigences de l’entreprise. La dernière étape consiste à la création de l’application et à son instauration dans l’entreprise. Le résultat étant en accord avec les objectifs ci-dessus, de nombreux constats ont été observés quant à la gestion de l’information au sein de l’entreprise, ce qui permet l’élaboration de recommandations quant à l’importance de la saisie, la création d’informations supplémentaires et pertinentes. Ce travail permet également à l’entreprise d’avoir une importante prise de conscience et une remise en question face à son système d’information