4,334 research outputs found
Drift-flux modeling of hyper-concentrated solid-liquid flows in dredging applications
No full textTransporting large amounts of sand is mostly done hydraulically in dredging and mining. This method of sand transport is efficient and is used in land reclamation projects or extraction of oil from tar sands. Large pieces of equipment, such as pumps and pipe line systems, dredging vessels etc., are used enabling the sand water mixtures to be transported hydraulically. Therefore, a good understanding of the hydrodynamical behavior of sand water mixtures is eminent in order to further improve these kind of systems. In this thesis a numerical model has been developed which describe the hydraulic behavior of sediment fluid mixtures. In the model the volume concentration of solids varies from 0.0 to 0.6. Moreover, the model is able to describe mixtures consisting of multiple sized sand particles.Offshore and Dredging Engineerin
J.C. Steyn Collection index
No full textThis index describes the J. C. Steyn collection which includes background material for 3 biographies by J.C. (Jaap) Steyn namely N.P. van Wyk Louw, P.J. Cillié and MER (M.E. Rothman). Prof. J.C. Steyn (1939-) is an educationist, linguist and author. Correspondence ; clippings ; photographs ; book reviews ; articles ; speeches ; varia compiled in 23 pamphlet boxes
Particle-driven gravity currents: Theory and Experimental results
No full textParticle-driven gravity currents cause major geological problems. Turbidity currents are highly erosive and can be damaging to structures on the sea bottom such as telecommunication cables. Understanding the mechanisms of sediment transport and deposition is required to predict the erosive powers of turbidity currents (and of the distribution of turbidite deposits) which are fully dependent on the behavior of gravity currents. For this reason, the main question of this thesis was formulated: Which physical parameters of the gravity current are of importance for its behaviour? The lock-exchange release experiment is a frequently used method to study gravity currents in a laboratory and was also used in this thesis. In order to answer the main question, the following parameters were investigated and their influence specifically on the 4 phases, the run-out length and the PSD: particle size, bed roughness and temperature. The influence of particles size was researched using mono-dispersed vs bi-dispersed experiments. In the bed roughness experiments, sandpaper was attached to the bottom and compared to smooth bed experiments. Finally, to investigate the influence of temperature on the gravity current, experiments with warm water were compared to experiments with colder water. From these experiments, the most notable results are summarized below.PSD : For all experiments applies that at low concentration the particles segregate over the run-out length of the gravity current. Smaller particles travelled further than the bigger particles with a higher settling velocity. This does not occur at higher concentrations and the PSD over the entire run-out length is similar.Four Phases: In all experiments, the four phases could clearly be identified with one exception: the first phase in the rough bed experiments was difficult to distinguish.Run out length: Some interesting findings were made that were in line with literature: adding fine particles to the mixture of the current cause the run-out length of the current to increase. However, it was also found that if the initial concentration is increased, this effect decreases.Furthermore experiments showed that an increase in temperature can cause the current to travel less far when compared to experiments performed with water with lower temperature. In the light of this research, the following recommendation are made:Temperature should be taken into account for modelling gravity currents. Otherwise this can lead to an overestimation regarding the run-out length and an underestimation of the deposit density.Furthermore, to get more insight in the effect of the particle sizes in the currents, it would be highly recommended to conduct more experiments with a greater difference between particle sizes. This would allow for a better assessment of the magnitude of the effect of hindered settlingOffshore and Dredging Engineerin
Product Innovation Knowledge Transfer for Developing Countries: Towards a systematic Transfer Approach
No full textThe transfer of knowledge on product innovation to small- and medium-sized enterprises and local knowledge institutions in developing countries is expected to be one of the key drivers for competiveness and economical growth, and a part of the solution to environmental and social challenge. In that respect, this PhD study focuses on how the process of the current knowledge transfer takes place and how it can be improved. A combination of literature review and empirical research has resulted into a conceptual framework to describe the complex and dynamic process of product innovation knowledge transfer to developing countries. In order to improve this process, a systematic approach has been developed and operationalized by a needs assessment tool and a design manual: The UNEP Design for Sustainability for Developing Economies (D4S-DE) Manual (www.d4s-de.org). Both tools have been tested in practice by practitioners and have been evaluated by an academic review board.Design EngineeringIndustrial Design Engineerin
Where do we draw lines: professional relationship boundaries and the child and youth care practitioner
No full textThe question of professional relationship boundaries is a poignant one, in light of the many boundary grey-zones that are created by the variety of young people’s needs, practice settings and professional relationship contexts within the field of child and youth care. In order to support practitioners’ development of critical thought and awareness of professional boundaries, this paper applies a professional relationship boundaries conceptual framework to child and youth care work, and the literature is consulted to explore the impacts of boundary violations, influences on individual’s boundaries, cues to indicate blurring boundaries, and key strategies to maintain balanced boundaries
Anthropometry of the Beaver, Sekani, and Carrier Indians:
No full textby J.C. Boileau GrantBulletin (National Museum of Canada) ; 81. Bulletin (National Museum of Canada). Anthropological series. ; 18
J.C. Painter letter to Benjamin Lundy
No full textLetter from J.E. Painter to (presumably) Benjamin Lundy, answering a request for information about the history and operations of the Underground Railroad. Letter includes details of a story of an ex-slave transported on the Underground Railroad through Ohio and stories of the plight of other fugitive slaves crossing the Ohio River.
Benjamin Lundy (1789-1839) was a prominent Quaker abolitionist best known for his development of abolitionist periodicals. His "Genius of Universal Emancipation" was first published in 1821 from his home in Mt. Pleasant, Ohio, and enjoyed a wide circulation across the antebellum United States. In the 1820s, the young William Lloyd Garrison came to work for The Genius. Benjamin Lundy traveled widely seeking subscriptions to The Genius, giving talks about the anti-slavery movement, and observing and documenting the conditions of enslaved people across the Americas. He was also involved in the establishment of freed slave colonies in Mexico
Turbulent wakes of plates with non-equilibrium similarity scalings
No full textWe have conducted hot wire anemometry measurements of six different axisymmetric turbulent wakes which demonstrate the existence in all these wakes of non-equilibrium mean flow profile scalings and of the underlying self-preservation and non-equilibrium dissipation scalings. These mean flow profile scalings are different from those of all documented canonical boundary-free turbulent shear flows to date, all of which have been established for very far downstream regions
Energy dissipation and flux laws for unsteady turbulence
No full textDirect Numerical Simulations of spatially periodic unsteady turbulence show that the high Reynolds number scalings of the instantaneous energy dissipation rate and interscale energy flux at intermediate wavenumbers are qualitatively different from the well-known cornerstone scalings of equilibrium turbulence where and are time-dependent rms velocity and integral length-scales. Instead, they both scale as where and are length and velocity scales characterizing initial/overall unsteady turbulence conditions
De werktuigen voor het bemalen van onze polders en boezems gedurende de afgeloopen 20 jaren
No full textRede, uitgesproken op 15 September 1919, bij overdracht van de waardigheid van Rector-Magnificus. Prof. ir. J.C. Dijxhoorn was rond de 1e wereldoorlog hoogleraar Werktuigbouwkunde aan de TU. Hij was ook Rector Magnificus van 1916-1919. Bij de overdracht van dit rectoraat heeft hij een lezing gegeven over de ontwikkeling van de Nederlandse gemalen in de periode van 1900 – 1920. [Transcriptie: H.J. Verhagen]Mechanical, Maritime and Materials EngineeringWerktuigbouwkund
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