The goal of this thesis was to develop a process of producing small monodisperse alginate gel beads. The phenomenon of controlled jet break-up of alginate solution jet with assisted vibration was used to form uniform sodium alginate droplets which were subsequently crosslinked with divalent calcium ion to form gel beads. Producing uniform alginate beads below 500 microns has been a problem which previous researchers have faced. Also, there is no commercially viable system available which can produce microbeads of uniform size. This study was an attempt to solve some of these problems. Vibration was applied to the alginate solution jet in both axial and transverse direction to cause jet break-up. Also, different modes of transmitting the vibration to the jet, like vibrating the full assembly or vibrating a diaphragm, were investigated. This resulted in construction of different types of bead generator apparatus. The droplet formation involves the formation of a jet through an orifice and superposition of vibration in order to control the break-up the jet. Both of these fluid flow phenomena depend on the properties of the liquid used to form the droplets. Specifically, the viscoelastic properties of the liquid play a major role in determining the break-up dynamics of the jet. The rheology of the Keltone LV (alginate) solutions (1-2% w/v) was studied using a rotational Bohlin CS-50 Rheometer and a Clark High Shear Capillary Viscometer. The best results were obtained by using the axial vibrating diaphragm droplet generator. Good monodispersed beads (160-1000 microns) were produced by using two different size orifices 100 micron and 200 microns. The vibration frequency range used was 200-6000 Hz and the flowrate range was 2-7 ml/min. The alginate droplets were crosslinked in 0.1 M calcium chloride and the shrinkage of the alginate droplets due to gelation was studied over a period of 7 days. Based on our study a design for producing sub-100 micron size beads has been proposed which uses a piezoceramic crystal for producing high frequency vibrations. / Graduation date: 1997

Thesis (M.S.M.E.)--University of Delaware, 2006. / Principal faculty advisor: Ajay K. Prasad, Dept. of Mechanical Engineering. Includes bibliographical references.

This thesis presents the results of an experimental and analytical study of single-port buoyant turbulent jets discharged into shallow water. The experimental results include the measured downstream dilution, centerline concentration and trajectory. Independent parameters considered were Froude number, submerged depth, discharge angle and velocity ratio. Results indicate that decreasing the discharge depth provides earlier occurrence of surface effect and greatly decreases dilution. Dilution increases with decreasing Froude number. Increasing the discharge angle from the horizontal into cross current increases the dilution ratio. The effect of ambient current on dilution depends on the angle of discharge. For cross-flow discharges, the dilution rate decreases with increasing ambient current, while for co-flow discharge the reverse trend was observed. As plumes reach the water surface, the dilution rate increases with increasing ambient velocity. The jets bend over rapidly for cross-flow discharges when large ambient currents are present. The analytical portion of this report presents an integral method proposed by Davis (1975) for merging multiple buoyant jets. This merging model was used to simulate the single-port buoyant jet in shallow water. This was done by using an image method where the submerged depth was simulated by the spacing between images. The entrainment function as presented by Kannberg and Davis (1978) was used except for a modification within the zone of merged plumes. Comparisons of the model prediction were made with experimental data. Results indicate that good predictions are obtained for buoyant jets discharging at 0 and 45 degrees into shallow water by using the image method as long as the Froude number is above 13.5. For lower Froude number and vertical discharges, model predictions are only fair. / Graduation date: 1991

No description available.

Thesis (Ph. D.)--University of Sydney, 1992. / Bibliography: leaves 211-219. Also available in print form.

Thèse : Astronomie : Université, Faculté des sciences de Paris : 1831. / Titre provenant de l'écran-titre.

Thesis (doctoral)--Friedrich-Wilhelms-Universität Berlin, 1862. / Vita. Includes bibliographical references.

Thesis (doctoral)--Cranfield Institute of Technology, 1991. / BLDSC reference no.: DX94724.

Thesis (Ph. D.)--University of Texas at Austin, 2001. / Vita. Includes bibliographical references. Available also from UMI/Dissertation Abstracts International.

Thesis (M. Phil.)--Hong Kong University of Science and Technology, 2002. / Includes bibliographical references (leaves 54-57). Also available in electronic version. Access restricted to campus users.