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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
31

NUMERICAL INVESTIGATION OF THERMAL TRANSPORT MECHANISMS DURING ULTRA-FAST LASER HEATING OF NANO-FILMS USING 3-D DUAL PHASE LAG (DPL) MODEL

Kunadian, Illayathambi 01 January 2004 (has links)
Ultra-fast laser heating of nano-films is investigated using 3-D Dual Phase Lag heat transport equation with laser heating at different locations on the metal film. The energy absorption rate, which is used to model femtosecond laser heating, is modified to accommodate for three-dimensional laser heating. A numerical solution based on an explicit finite-difference method is employed to solve the DPL equation. The stability criterion for selecting a time step size is obtained using von Neumann eigenmode analysis, and grid function convergence tests are performed. DPL results are compared with classical diffusion and hyperbolic heat conduction models and significant differences among these three approaches are demonstrated. We also develop an implicit finite-difference scheme of Crank-Nicolson type for solving 1-D and 3-D DPL equations. The proposed numerical technique solves one equation unlike other techniques available in the literature, which split the DPL equation into a system of two equations and then apply discretization. Stability analysis is performed using a von Neumann stability analysis. In 3-D, the discretized equation is solved using delta-form Douglas and Gunn time splitting. The performance of the proposed numerical technique is compared with the numerical techniques available in the literature.
32

Digital sculpture : technical and aesthetic considerations applicable to current input and output modes of additive fabricated sculpture

Kuhn, C., De Lange, R, De Beer, D.J. January 2009 (has links)
Published Article / This article examines the synergy between aesthetic and technical issues surrounding current input and output modes applicable to digital sculpture built by means of additive fabrication technologies. The scope is limited to select sculptural aspects that either transcend, question or fall short when measured against traditional manufacturing and aesthetic modes. Presented are a range of technical as well as aesthetic aspects that have impacted on this ''new form'' of sculpture delivery. It is indicated that irrespective of current strengths and weaknesses, for the evolving sculptor, an interactive creative partnership between technologies equally positions this ''new form'' of sculpture delivery as a leading role player towards defining a new digital aesthetic.
33

Development and characterisation of a three-dimensional in vitro hepatic fish model to investigate xenobiotic metabolism

Baron, Matthew Graham Joesph January 2014 (has links)
Regulatory and academic studies use large numbers of fish annually. The use of fish primary cells offers an in vitro alternative for the assessment of chemical toxicity and the evaluation of environmental samples in ecotoxicology. Their uses however are not without limitations which includes short culture periods (i.e. longevity and loss of organ-specific functionality over time). Three-dimensional (3-D spheroid) technology is now established for in vitro mammalian toxicity studies and offers significant advantages for environmental applications in a model fish species. This thesis reports development of a reproducible six-well plate, gyratory-mediated method for rainbow trout (Oncorhynchus mykiss) hepatocyte spheroid culture and compares morphological, functional and biochemical status with two-dimensional (2-D) monolayer hepatocytes. The work further assesses the bio-transformation potential of developed 3-D spheroids to a range of environmentally relevant pharmaceuticals. The study suggests that mature spheroids retain some organotypic responses over-time in culture including morphological (viz., smooth outer surface, tight cell–cell contacts); functional (viz., histo-architecture; cell adhesion molecule expression) and biochemical properties (viz., protein, glucose, albumin- and enzyme levels) that is superior to conventional 2-D monolayer cells. These 3-D spheroids also demonstrate a capacity for the metabolism of environmentally-relevant pharmaceuticals that could be utilised to better understand their bio-accumulation potential in fish. This is an important step forward for developing alternative in vitro tools in future fish ecotoxicological studies as well as for fundamental understanding of the interaction of chemicals with biomolecules which could potentially lead to detrimental responses at different levels of biological organisation.
34

Printed/additively manufactured and compact antennas for IoT and wearable applications

Nate, Kunal A. 27 May 2016 (has links)
The research provided in this thesis focuses on the development of the novel additively manufactured antennas using the additive 3-D and material inkjet printing fabrication as well as the conventional subtractive manufacturing by using milling machine for the compact Internet of Things (IoT) and wearable applications. The initial part of the work focuses on the different ways of fabrication of the additively manufactured antenna that includes Finite Deposition Method (FDM) and PolyJet 3-D printing technique for the substrate material fabrication. And the material inkjet printing for the conductive radiating antenna element fabrication. The document discusses the unconventional issue of the surface roughness in the 3-D printed substrates materials. The later part focuses on the designing and testing techniques for the compact electrically small antennas (ESA) for the compact IoT applications.
35

3-D Direction of Arrival Estimation with Two Antennas

Yu, Xiaoju, Xin, Hao 10 1900 (has links)
ITC/USA 2011 Conference Proceedings / The Forty-Seventh Annual International Telemetering Conference and Technical Exhibition / October 24-27, 2011 / Bally's Las Vegas, Las Vegas, Nevada / Inspired by human auditory system, an improved direction of arrival (DOA) technique using only two antennas with a scatterer in between them to achieve additional magnitude cues is proposed. By exploiting the incident-angle-dependent magnitude and phase differences between the two monopole antennas and applying 2-D / 3-D multiple signal classification algorithms (MUSIC), the DOA of an incident microwave signal can be estimated. Genetic algorithm is applied to optimize the scatterer geometry for the 3-D DOA estimation. The simulated results of both the azimuth and three-dimensional DOA estimation have shown an encouraging accuracy and sensitivity by incorporating a lossy scatterer.
36

Surveying, modelling and visualisation of geological structures in the Tunbergettunnel

Surur, Anwar January 2008 (has links)
<p>The 3-d visualisation of a section of the Tunberget tunnel and important fracture zones was accomplished by combination of the topographic surface, measurements at the surface of fracture planes together with surfaces of dolerite dykes, results from magnetic modeling of dolerite dykes and tunnel mapping data.</p><p>The topographic surface was represented as elevation contours with 1 m equidistance. The fracture and dolerite surfaces were measured geodetically in the field from a net of 20 total station locations. Each surface was measured at 3 points to determine its strike and dip. Totally 44 strike and dip estimates were obtained. The extent at depth of the dolerite dykes was also estimated based on magnetic measurements along 3 profiles. The location of the dykes was also known from geological tunnel mapping.</p><p>ArcGIS and RockWorks have been used to process the data and to generate a 3-d visualization of the geometrical relation between targeted geological structures, the dolerite dykes and the tunnel. The area is of interest to be studied in more detail as the fracture zones and the parallel dolerite dykes connect the tunnel with a large wetland complex.</p> / QC 20100707
37

Etude de l'infuence de la séparation des degrés de liberté pour la manipulation 3-D à l'aide de surfaces tactiles multipoints / Study of the influence of the separation of degrees of freedom for 3-D manipulation using multitouch displays

Martinet, Anthony 03 October 2011 (has links)
Inventées au milieu des années 1980, nous assistons actuellement au développement à grande échelle des interfaces tactiles multipoints. Par comparaison avec la souris, les écrans multipoints nécessitent un nouveau processus d'étude afin de comprendre les changements apportés par cette technologie. Le travail déjà effectué avec d'autres périphériques d'entrée doit être repris à zéro afin de formuler de nouvelles théories pour la création d'interfaces tactiles multipoints. La manipulation à trois dimensions (3-D) d'un objet nécessite le contrôle de six degrés de liberté. Trois sont responsables de la position de l'objet et trois contrôlent son orientation. Dans ce mémoire, nous nous focalisons sur la manipulation 3-D d'un objet à l'aide de surfaces tactiles multipoints. Plus précisément, nous avons étudié le lien entre le périphérique d'entrée (ici la surface multipoint) et la tâche à effectuer (ici la manipulation 3-D). En premier lieu, nous avons introduit une taxonomie pour la représentation des techniques d'interaction 3-D spécifiques aux écrans multipoints. Cette taxonomie nous a permis de mettre en avant l'influence des stratégies de conception des techniques en termes d'intégration de degrés de liberté. Par la suite, nous avons mené une étude concernant les techniques d'interactions permettant le positionnement 3-D d'un objet. Nous avons présenté deux nouvelles techniques, tirant profit des capacités offertes par les écrans multipoints. L'évaluation de ces techniques nous révéla des conclusions quant à la coordination de l'utilisateur dans la réalisation de la tâche. Enfin, nous avons introduit une nouvelle technique d'interaction de manipulation 3-D. Cette technique a été évaluée plus rapide que les techniques existantes et nous avons pu déterminer les raisons expliquant cette performance accrue. Ces travaux, qui s'intéressent à la coordination de l'utilisateur lors de la réalisation de tâches 3-D à l'aide de surfaces multipoints, recommandent une approche favorisant la séparation des degrés de liberté, dans le but de pouvoir paralléliser les actions de l'utilisateur afin de tirer profit de la bande passante d'entrée plus importante offerte par les écrans multipoints. / Invented in the mid-1980s, we are currently witnessing large-scale development of multitouch interfaces. Compared with the traditional mouse, multitouch displays require rethinking from scratch interaction techniques in order to understand the changes brought by this technology and formulate new theories. Manipulating three-dimensional (3-D) objects require the control of six degrees of freedom. Three are responsible for the object's position and three control the orientation. In this work, we focused on 3-D manipulation of an object using multitouch displays. Specifically, we studied the relationship between the input device (the multitouch display) and the task (3-D manipulation). First, we introduced a taxonomy for the representation of 3-D interaction techniques specific to multitouch displays. This taxonomy allowed us to highlight the influence of design strategies in terms of integration of degrees of freedom.Subsequently, we conducted a study of interaction techniques for 3-D positioning of an object. We presented two new techniques, which take advantage of capabilities offered by multitouch displays. The evaluation of these techniques revealed us results regarding the user coordination in realizing the task. Finally, we introduced a new interaction technique to handle 3-D manipulation. This technique was evaluated faster than existing techniques and we were able to determine the reasons for the improved performance.This work, which focus on the user coordination when using multitouch displays to perform 3-D tasks, recommend an approach that favors the separation of degrees of freedom, in order to parallelize the user actions so as to take advantage of the extra input bandwidth offered by this type of input devices.
38

3D-Printed Flexible Polylactic Acid/ Thermoplatic Polyurethane (PLA/TPU) Stents for Esophageal Malignancies

Unknown Date (has links)
Palliation therapy for dysphagia using esophageal stents is the current treatment of choice for those patients with inoperable esophageal malignancies. However, the stents currently used in the clinical setting, regardless of the type of metal mesh or plastic mesh stents (covered/uncovered), may cause complications, such as tumor ingrowth and stent migration into the stomach. Furthermore, metal mesh stents have limited capacities for loading anti-cancer drugs. To effectively reduce/overcome those complications and enhance the efficacy of drug release, we designed and 3D-printed a tubular, flexible polymer stent with spirals, and then load anti-cancer drug, paclitaxel, on the stent for drug release. Non- spiral 3D-printed tubular and mesh polymer stents served as controls. The self-expansion and anti migration properties, cytotoxicity, drug release profile, and cancer cell inhibition of the 3D-printed stent were fully characterized. Results showed the self-expansion force of the 3D-printed polymer stent with spirals was slightly higher than the stent without spirals. The anti-migration force of the 3D-printed stent with spirals was significantly higher than the anti-migration force of a non-spiral stent. Furthermore, the stent with spirals significantly decreased the migration distance compared to the migration distance of the non-spiral 3D-printed polymer stent. The in vitro cytotoxicity of the new stent was examined through the viability test of human esophagus epithelial cells, and results indicated that the polymer stent does not have any cytotoxicity. The results of in vitro cell viability of esophageal cancer cells further indicated that the paclitaxel in the spiral stent treated esophageal cancer cells much more efficiently than that in the mesh stent. Furthermore, the results of the in vitro drug release profile and drug permeation showed that the dense tubular drug-loaded stent could efficiently be delivered more paclitaxel through the esophageal mucosa/submucosa layers in a unidirectional way than mesh stent that delivered less paclitaxel to the esophageal mucosa/submucosa but more to the lumen. In summary, these results showed that the 3D-printed dense polymer stent with spirals has promising potential to treat esophageal malignancies. / Includes bibliography. / Dissertation (Ph.D.)--Florida Atlantic University, 2019. / FAU Electronic Theses and Dissertations Collection
39

Toward a Surface Primal Sketch

Ponce, Jean, Brady, Michael 01 April 1985 (has links)
This paper reports progress toward the development of a representation of significant surface changes in dense depth maps. We call the representation the Surface Primal Sketch by analogy with representation of intensity changes, image structure, and changes in curvature of planar curves. We describe an implemented program that detects, localizes, and symbolically describes: steps, where the surface height function is discontinuous; roofs, where the surface is continuous but the surface normal is discontinuous; smooth joins, where the surface normal is continuous but a principle curvature is discontinuous and changes sign; and shoulders, which consists of two roofs and correspond to a step viewed obliquely. We illustrate the performance of the program on range maps of objects of varying complexity.
40

On Interpreting Stereo Disparity

Wildes, Richard P. 01 February 1989 (has links)
The problems under consideration center around the interpretation of binocular stereo disparity. In particular, the goal is to establish a set of mappings from stereo disparity to corresponding three-dimensional scene geometry. An analysis has been developed that shows how disparity information can be interpreted in terms of three-dimensional scene properties, such as surface depth, discontinuities, and orientation. These theoretical developments have been embodied in a set of computer algorithms for the recovery of scene geometry from input stereo disparity. The results of applying these algorithms to several disparity maps are presented. Comparisons are made to the interpretation of stereo disparity by biological systems.

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