177,849 research outputs found
Measurements in a Carousel (Metingen in een Carrousel)
No full textThis report is essentially a report of the measurements in the carousel of the laboratory for Fluid Mechanics of the Delft University of Technology made accessible for a slightly wider public. A comprehensive documentation about the considered investigation, both concerning the theoretical background and concerning the elaboration of the experimental evidence can be found in: Booij, R., (1994), "Measurements of the flow field in a rotating annular flume ", Communications on Hydraulic and Geotechnical Engineering, report no. 94-2, Laboratory for Fluid Mechanics, Faculty of Civil Engineering, Delft University of Technology. To make the report more widely accessible a short explanation and description of the contents of every subdivision in English is added. The original text in Dutch by M.M.L. Melis is retained because an integral translation would be too time consuming. The added pages with English text are numbered El, etc.Hydraulic EngineeringCivil Engineering and Geoscience
Prosodic constituents in the representation of consonantal sequences in Polish
No full textThe aim of this paper is to show what role prosodic constituents, especially the foot and the prosodic word play in Polish phonology. The focus is placed on their function in the representation of extrasyllabic consonants in word-initial, word-medial, and word-final positions.
The paper is organized as follows. In the first section, I show that the foot and the prosodic word are well-motivated prosodic constituents in Polish prosody. In the second part, I discuss consonant clusters in Polish focussing on segments that are not parsed into a syllable due to violations of the Sonority Sequencing Generalisation, i.e. extrasyllabic segments. Finally, I analyze possible representations of the extrasyllabic consonants and conclude that both the foot and the prosodic word play a crucial role in terms of licensing. My proposal differs from the ones by Rubach and Booij (1990b) and Rubach (1997) in that I argue that the word-initial sonorants traditionally called extrasyllabic are licenced by the foot and not by the prosodic word (cf. Rubach and Booij (1990b)) or the syllable (cf. Rubach (1997)). For my analysis I adopt the framework of Optimality Theory, cf. McCarthy and Prince (1993), Prince and Smolensky (1993), in which derivational levels are abandoned and only surface representations are evaluated by means of universal constraints
Development of cauliflower and its consequences for cultivation
No full textFrom a number of cauliflower crops, grown during several years, plant development was related to the environmental conditions (mainly temperature). After transplanting three developmental phases could be recognized: juvenility, curd induction and curd growth, Variation in time of curd maturity was mainly due to a variation in time of curd initiation (morphological transition of the apex). Time of curd initiation was determined by the time on which juvenility (characterized by the number of initiated leaves) ended and temperature during the period after juvenility. Higher temperatures during the period of curd induction delayed curd initiation and increased the total number of initiated foliage leaves of a plant.Curd induction could be affected by a GA 4+7 application, resulting in an advance of curd maturity, especially when curd initiation of a crop was delayed due to high temperature.Curd weight at maturity was reduced if plant weight at the time of curd initiation was low, conditions which enhanced development but reduced growth caused buttoning.Bracting was induced by high temperature, and when ethephon was applied just after all plants within a crop had initiated a curd, bracting incidence was enhanced severely. Genetic differences in sensitivity for bracting induced by ethephon were apparent.Prospects of cultural measures to reduce the variation in time of maturity in relation to rapidly changing environmental conditions are discussed
Measurements of the rate of adjustment of the secondary flow in a curved open channel with varying discharge
No full textPrediction of bottom changes in rivers and tidal channels require a thorough knowledge of the secondary flow, as this flow gives rise to bottom slopes transverse to the main flow direction. In the model used in this research, the computation of the secondary flow field is based upon an, independently computed, depth averaged main flow field. In the computation of the secondary flow it can often be assumed fully developed, i.e. adjusted to the local variables: depth, main flow velocity, etc. In case of variation of bottom topography or of main flow properties in the flow direction, the secondary flow will not be adjusted to these local variables, but will retain information about the situation considered parcels of water have met earlier during their flow. An analogous misadjustment will occur in case of time dependent main flow properties. A theoretical investigation about the degree of adjustment of secondary flow was reported by Booij and Kalkwijk (1982). They describe the rate of adjustment by a relaxation length in case of variation in the flow direction and by a relaxation time in case of variation in time. Both are defined by the reduction of the misadjustment to a factor l/e of the original misadjustment with respect to the local variables. For the value of the Chezy coefficient of 50 m^1/2/s, the relaxation length L of the secondary flow was found to be about 15 times the water depth hand the relaxation time T was found to be about the time needed by the depth averaged flow to cover a distance equal to this relaxation length.Hydraulic EngineeringCivil Engineering and Geoscience
Onderzoek aanslibbing jachthaven "het Steel" te Roermond
No full textHet afstudeeronderzoek bestaat uit vier onderdelen, te weten: \u95 Onderzoek om enig gevoel te krijgen voor de mogelijkheden en beperkingen en de te hanteren coëfficiënten en grootheden bij toepassing van TRISULA voor het modelleren van door langsstroom aangedreven havenstromingen. \u95 Onderzoek naar het huidige aanslibbingsmechanisme van jachthaven 'het Steel' te Roermond voor verschillende Maasafvoeren. \u95 Onderzoek naar havenstromingen zoals deze optreden bij een langjarig gemiddelde Maasafvoer, een Maasafvoer die eens per jaar optreedt resp. eens per 10 jaar optreedt. Hierbij is het stromingsmodel TRISULA toegepast. \u95 Onderzoek naar verschillende aanpassingen om de uitwisseling met de Maas en hiermee de aanslibbing van de jachthaven te verminderen. Verschillende aanpassingen zijn met TRISULA gesimuleerd. Als oefening om inzicht te krijgen in de mogelijkheden cq. beperkingen bij toepassing van TRISULA voor dit onderzoek, is een laboratoriumonderzoek naar de uitwisseling tussen rivier en haven gesimuleerd. Bij de simulaties van dit laboratoriumonderzoek blijkt duidelijk dat de weergegeven havenstromingen sterk afhankelijk zijn van de toegepaste (constante) waarde voor de turbulente viscositeit. Een empirische benadering van Booij (1991) voor de toe te passen waarde, waarbij deze afhangt van stroomsnelheid in de rivier en de breedte van de havenmonding, is een bruikbaar hulpmiddel om de waarde hiervoor te schatten. Tevens bestaat er een afhankelijkheid van de toe te passen viscositeitswaarde met de roostergrootte. Bij simulaties waarbij 3D-effecten een (grote) rol spelen worden de optredende havenstromingen met een 2D berekening niet goed weergegeven.Hydraulic EngineeringCivil Engineering and Geoscience
Appropriate Similarity Measures for Author Cocitation Analysis
No full textWe provide a number of new insights into the methodological discussion about author cocitation analysis. We first argue that the use of the Pearson correlation for measuring the similarity between authors’ cocitation profiles is not very satisfactory. We then discuss what kind of similarity measures may be used as an alternative to the Pearson correlation. We consider three similarity measures in particular. One is the well-known cosine. The other two similarity measures have not been used before in the bibliometric literature. Finally, we show by means of an example that our findings have a high practical relevance.information science;Pearson correlation;cosine;similarity measure;author cocitation analysis
Iodine-123 and Fluorine-18 radiolabeled analogues of WAY-100635 as potential radioligands for imaging the 5-HT1A receptor in the brain
No full textDongen, G.A.M.S. [Promotor]van Booij, J. [Promotor]Herscheid, J.D.M. [Copromotor
"Closing the R&D Gap, Evaluating the Sources of R&D Spending"
No full textBoth spending and tax policies have been implemented in the United States with the goal of stimulating private sector research and development (R&D). Karier questions whether current R&D policy, especially the research and experimentation tax credit, can contribute to closing the gap between nondefense expenditures on R&D in the United States and such expenditures in other countries, such as Japan and Germany. He also explores possible changes to our current R&D policy to make it more effective.
Going Beyond Counting First Authors in Author Co-citation Analysis
No full textThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
Three-dimensional modelling of secondary flow in river bends
No full textThe flow in a river bend has a large influence on the cross-sectional profile of the bend. Due to the curvature of the bend a secondary flow, which is perpendicular to the main flow, occurs. The secondary flow is directed outwards in the upper part of the cross-section and inwards in the lower part of the cross-section. It causes by means of the transverse transport of main flow momentum a redistribution of the main flow. This redistribution of the main flow and the sediment transport by the secondary flow cause a typical river bend profile, a steep sloping bank in correspondence with a large depth near the outer wall and a smoothly sloping bank in correspondence with a small depth near the inner wall. To be able to predict (the changes of) the profile and the position of a river bend one must understand the flow pattern and the related sediment transport. To account for the flow pattern several numerical simulation programs have been developed. Since, nowadays, it is impossible to calculate the flow exactly, due to the turbulence, it has to be modelled and some assumptions and approximations have to be made. At Delft Hydraulics a program package (Delft3D) has been developed to simulate these flow cases and their sediment transports. In this thesis research has been done to what extent Trisula, the part that accounts for the prediction of the fluid movement, is capable of predicting the flow in river bends. At first a description of the flow pattern in river bends and a summary of the possibilities of the turbulence modelling are given as well as an abstract of the previous research, both numerically and experimentally, to gain insight in the phenomenon. To verify Trisula an experiment in an 'infinite river bend' has been done at the University of Padua at the Institute of Hydraulics 'G Poleni'. Due to the sensitivity of the boundary conditions this experiment gave not satisfying results so the program had to be checked with other measurement. The measurements of De Vriend were used to verify the computational results of a strongly curved bend and the measurements of Booij were used to verify the computational results of a smoothly curved bend. From the research to the simulation of the flow in river bends, it appeared that Trisula is able to predict the main features that occur in a river bend although the magnitude, especially of the radial velocities, is sometimes too small. The velocity distributions over the vertical and the development and decay of the secondary flow throughout a river bend are predicted rather well. One of the most striking features is the impossibility of trisula to predict the counterrotating secondary flow near the outer wall at sufficiently large Dean numbers due to the incorrect modelling of the turbulenceHydraulic EngineeringCivil Engineering and Geoscience
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