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Parameterization based shape optimization : theory and practical implementation aspects
Marko Kegl, 2005, izvirni znanstveni članek

Opis: This paper presents an approach to parameterization based shape optimization of statically loaded elastic structures. The shape parameterization is based on the design element technique and a rational Bezicr body is used to serve as the design element. Practical implementation issues related to the introduction of design variables are discussed briefly. The design sensitivity calculation is based on the discrete approach. The proposed solution process layout is based on a stand-alone optimization program which makes use of compatiblc analysis programs called simulators. For illustrationpurpose an example problem containing shape and sizing design variables is formulated and solved. The range of use of the proposed approachis illustrated with three further examples.
Ključne besede: mechanics, structure parameterization, shape optimal design, finite element mesh, body parameterization, design element, Bezier body
Objavljeno: 01.06.2012; Ogledov: 1011; Prenosov: 50
URL Povezava na celotno besedilo

EVA: expressive multipart virtual agent performing gestures and emotions
Izidor Mlakar, Matej Rojc, 2011, izvirni znanstveni članek

Opis: Embodied Conversational Agents (ECAs) play an important role in the development of personalized and expressive human-machine interaction, allowing users to interact with a system over several communication channels, such as: natural speech, facial expression, and different body gestures. This paper presents a novel approach to the generation of ECAs for multimodal interfaces, by using the proprietary EVA framework. EVAćs articulated 3D model is mesh-based and built on the multipart concept. Each of its 3D submodels (body-parts) supports both bone and morph target-based animation, in order to simulate natural human movement. Each body movement's structural characteristics can be described by the composite movement of one or more elementary units (bones and/or morphs), and its temporal characteristics by the durations of each of the movementćs stages (expose, present, dissipate). EVA scripts provide a means of defining and fine-tuning body motion in the form of predefined gestures, or complex behavioural events (provided by external behaviour modelling sources). Since behavioural events can also be described as a combination of tuned predefined gestures and the movements of elementary units, a small number of predefined gestures can form infinite sets of gestures that ECA can perform. ECA EVA, as presented in this paper, provides both: a personalization of its behaviour (gesture level), and a personalization of its outlook.
Ključne besede: bone and morph based animation, distributive, expressive ECA, mesh based articulated model
Objavljeno: 01.06.2012; Ogledov: 1140; Prenosov: 27
URL Povezava na celotno besedilo

Selestina Gorgieva, 2014, doktorska disertacija

Opis: This work presents the methodological study, processing and optimization of novel, technologically acceptable procedure for in situ coating of polypropylene (PP) mesh (used for hernia treatment) with physico-chemically, mechanically and micro-structurally different gelatin (GEL) scaffolds to assess implant composite biocompatibility impact. In order to systematically follow the experimental work progress and respective achievements, whole research path is subdivided into three main sections. In the first section, the procedure for fabrication of gradiently micro-porous GELscaffolds on the cryo-unit’s cooling plate surface, using spatiotemporal and temperature- controlled gelation and freezing, followed by lyophylizaton was studied. Subsequently, cross-linking procedure using different molarities of reagents (EDC and NHS) and reaction media (100% PBS or 20/80% PBS/EtOH mixture) was performed for variable time extensions (1-24 h), rendering scaffolds physico-chemical properties. In this way, scaffolds with micro-structures having porosity gradient from 100 µm to 1000 µm and pores with rounded to ellipsoid morphology were formed, which, in combination with ethanol (EtOH) addition in cross-linking media modulates the swelling capacity towards twice lower percentages (~600%) comparing with scaffolds cross-linked in 100% PBS. Whilst the presence of EtOH reduce the cross-linking kinetic by retaining the scaffolds’ micro-structure formed during freezing, the 100% PBS and higher EDC molarity resulted in 40% cross-linking degree, being expressed as a thermal resistance up to 73 °C. The presented integral fabrication procedure was shown to allow tuning of both, the physical and micro-structural properties of scaffold, utilized in preparation of materials for specific biomedical applications. In the second part, the complex relation between surface and interface-related physico-chemical properties and gradient micro-structuring of 3D GELscaffolds, being fabricated by simultaneous temperature- controlled freeze-thawing cycles and in situ cross-linking using variable conditions (pH and molarity of carbodiimide reagent) and fibroblast cells viability (by tracking of their spreading and morphology) was established. Rarely- populated cells with rounded morphology and small elongations were observed on scaffolds with apparently negatively- charged surface with a lower cross-linking degree (CD) and consequently higher molecular mobility and availability of cell-recognition sequences, in comparison with the prominently- elongated and densely- populated cells on a scaffold’s with positively- charged surface, higher CD and lower mobility. Surface micro-structure effect was demonstrated by cell’s vacuolization and their pure inter-communication being present on scaffold’s bottom side with smaller pores (25±19 µm) and thinner pore walls (9±5 µm), over the air- exposed side with twice bigger pores (56±38 µm) and slightly thicker pore walls (12±6 µm). Strong correlation of preparation conditions (pH and reagents molarity) with CD (r2=0.96) and moderate correlation with local molecular mobility (r2 =-0.44), as well as micro-structure features being related to temperature gradient, imply on possibility to modulate scaffold’s properties in a direction to guide cell’s viability and most likely its genotype development. The third part presents an innovative strategy for the fabrication of bio-active PPmesh-GELscaffold composites with a potential for abdominal hernia treatment, where mesothelial cells in-growth have to be stimulated together with fibroblasts on-site proliferation, while formation of fibrin-developing, viscera-to-abdominal wall adhesions should be reduced, together with bacteria- related infections. In this respect, the plasma pre-activated PPmesh was coated with micro-structured GELscaffold, with pore size in 50 µm to 100 µm range at the upper-side and loosely- porous network at the composite bottom side, being modulated by sample thickness and freezing end- temperature applied. Simultaneously, the
Ključne besede: gelatin, targeted cross-linking, controlled freezing, gradiental micro-porosity, scaffold, surface and interface chemistry, physico-mechanical properties, polypropylene mesh, composite, biocompatibility.
Objavljeno: 07.05.2014; Ogledov: 1245; Prenosov: 95
.pdf Celotno besedilo (4,98 MB)

Lossless geometry compression through changing 3D coordinates into 1D
Yongkui Liu, Lijun He, Peng-jie Wang, Linghua Li, Borut Žalik, 2013, izvirni znanstveni članek

Opis: A method of lossless geometry compression on the coordinates of the vertexes for grid model is presented. First, the 3D coordinates are pre-processed to be transformed into a specific form. Then these 3D coordinates are changed into 1D data by making the three coordinates of a vertex represented by only a position number, which is made of a large integer. To minimize the integers, they are sorted and the differences between two adjacent vertexes are stored in a vertex table. In addition to the technique of geometry compression on coordinates, an improved method for storing the compressed topological data in a facet table is proposed to make the method more complete and efficient. The experimental results show that the proposed method has a better compression rate than the latest method of lossless geometry compression, the Isenburg-Lindstrom-Snoeyink method. The theoretical analysis and the experiment results also show that the important decompression time of the new method is short. Though the new method is explained in the case of a triangular grid, it can also be used in other forms of grid model.
Ključne besede: triangular mesh, model, lossless, compression
Objavljeno: 12.07.2017; Ogledov: 747; Prenosov: 201
.pdf Celotno besedilo (332,44 KB)
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The use of the mesh free methods (radial basis functions) in the modeling of radionuclide migration and moving boundery value problems
Leopold Vrankar, Franc Runovc, Goran Turk, 2007, izvirni znanstveni članek

Opis: Recently, the mesh free methods (radial basis functions-RBFs) have emerged as a novel computing method in the scientific and engineering computing community. The numerical solution of partial differential equations (PDEs) has been usually obtained by finite difference methods (FDM), finite element methods (FEM) and boundary elements methods (BEM). These conventional numerical methods still have some drawbacks. For example, the construction of the mesh in two or more dimensions is a nontrivial problem. Solving PDEs using radial basis function (RBF) collocations is an attractive alternative to these traditional methods because no tedious mesh generation is required. We compare the mesh free method, which uses radial basis functions, with the traditional finite difference scheme and analytical solutions. We will present some examples of using RBFs in geostatistical analysis of radionuclide migration modeling. The advection-dispersion equation will be used in the Eulerian and Lagrangian forms. Stefan's or moving boundary value problems will also be presented. The position of the moving boundary will be simulated by the moving data centers method and level set method.
Ključne besede: mesh free methods, radial basis functions, finite difference methods, finite elemnt methods, boundary elements methods, geostatistics, Eulerian method, Lagrangian method, level set method
Objavljeno: 18.05.2018; Ogledov: 363; Prenosov: 30
.pdf Celotno besedilo (214,16 KB)
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Bluetooth krmiljenje plezajočega robota za vzdrževanje mostov
Dejan Vrtič Pal, 2018, diplomsko delo

Opis: Vzdrževanje mostov je lahko zamudno in zahtevno delo, zato ga je smiselno opravljati s plezajočim robotom. Ker dodatna teža robotu predstavlja večjo breme, želimo minimizirati ožičenje z brezžično komunikacijo, v našem primeru bluetooth komunikacijo. Namen tega dela je bil, ugotoviti, kako lahko bluetooth komunikacijo uspešno izvedemo na plezajočem robotu in če je bluetooth komunikacija optimalna rešitev za robota za plezanje. V teoretičnem uvodu smo predstavili robota in opredelili bluetooth protokol. V praktičnem delu smo spoznali kinematični model robota za plezanje in razčlenili potrebo po prenosu podatkov pri različnih gibih robota. Pregledali smo bluetooth vmesnike na tržišču in izbrali najustreznejšega za potrebe robota za plezanje. Bluetooth komunikacijo smo izvedli in preizkusili s pomočjo treh mikrokrmilnikov dsPIC33FJ64MC802 in s pomočjo treh različnih Bluetooth modulov HC-05, RN-42 in RN4871. Pri izvedbi brezžične bluetooth komunikacije smo poskušali zagotoviti dovolj veliko hitrost prenosa podatkov pri najmanjšem številu potrebnih bluetooth modulov (najnižjih stroških). Ugotavljali smo ali zmoremo s pomočjo Bluetooth komunikacije pošiljati podatke vsakemu krmilniku osi robota in prijemalu robota v času, ki je krajši od 1 tisočinke sekunde. Prenos je bil daljši, kot smo načrtovali (30 mili sekund) in je imel domet, ki je bil večji od pričakovanega (več kot 10m za bluetooth 2. razreda). Ugotovili smo, da je izvedba bluetooth komunikacije mogoča. A za to da najdemo boljšo rešitev so potrebni dodatni preizkusi.
Ključne besede: plezajoči robot za vzdrževanje mostov, bluetooth komunikacija, UART (univerzalni asinhronski sprejemnik-oddajnik), MESH, PTP (od točke do točke)
Objavljeno: 16.07.2018; Ogledov: 619; Prenosov: 87
.pdf Celotno besedilo (5,75 MB)

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