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1
Guo, Li. "Shape blending using discrete curvature-variation functional /". View abstract or full-text, 2005. http://library.ust.hk/cgi/db/thesis.pl?IEEM%202005%20GUO.
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Chung, Jinpyung 1967. "Functional requirements to shape generation in CAD". Thesis, Massachusetts Institute of Technology, 2002. http://hdl.handle.net/1721.1/29628.
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Thesis (Ph. D.)--Massachusetts Institute of Technology, Dept. of Mechanical Engineering, June 2003.Includes bibliographical references (p. 119-121).
An outstanding issue in computer-aided design (CAD) is the creation of geometric shapes from the description of functional requirements (FRs). This thesis presents a method that can generate assembled shapes from the given FRs without human intervention. To achieve this goal, the design process follows a V-model of decomposition and integration based on axiomatic design. The V-model consists of three main sub-processes; (1) a top-down decomposition of FRs and design parameters (DPs), (2) mapping of DPs into geometric entities, and (3) a bottom-up integration of the geometric entities. A shape decomposition technique is used in the V-model to generate solid cells from the geometric entities in the CAD models based on FRs. These cells are stored and reused during the integration process. A set of cells mapped to an FR is called a functional geometric feature (FGF) to differentiate it from geometric features defined by only geometric characteristics. Each FGF has mating faces as its pre-defined interfaces. Links of FR-DP-FGF-INTERFACES and their hierarchies are made and stored in the database as fundamental units for automatic assembled shape generation. The retrieval of proper FGF from the database is performed by matching a query FR with stored FRs by a lexical search based on the frequency of words and the sequence of the words in the FR statements using a synonym checking system. The language-matching rate is calculated as a value of FRmetric between 0 and 1. A computer algorithm automatically combines and assembles the retrieved FGFs. Genetic algorithm (GA) searches for the best combination for matching interface types and generates assembly sequences.
(cont.) From the highest-valued chromosome, the computer algorithm automatically assembles FGFs by coordinating, orienting, and positioning with reference to the given mating conditions and calculates geometric interface-ability to a value of INTERFACEmetric between 0 and 1. The higher the values of FRmetric and INTERFACEmetric, the better the generated design solution for the given FRs that must be satisfied. The process of top-down decomposition and bottom-up integration reduces the number of possible combinations of interfacing FGFs. Design matrix visually relates FRs to FGFs. The method presented in this thesis has demonstrated that a "functional CAD" can aid designers in generating conceptual design solutions from functional descriptions, in reusing existing CAD models, and in creating new designs.
by Jinpyung Chung.
Ph.D.
3
Zhang, Jun. "Shape control in synthesis of functional nanocrystals". Diss., Online access via UMI:, 2009.
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Adiguzel, O. "Phase Transition and Functional Characteristics of Shape Memory Alloys". Thesis, Sumy State University, 2012. http://essuir.sumdu.edu.ua/handle/123456789/35059.
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Shape-memory alloys are a new class of functional materials with a peculiar property known as shape
memory effect. These alloys have an ability to recover a particular shape. The origin of this phenomenon
lies in the fact that the material changes its internal crystalline structure with changing temperature.
Copper based ternary alloys exhibit shape memory effect in metastable - phase field. These alloys undergo
two ordered transitions on cooling, and bcc structures turn into B2(CsCl) or DO3(Fe3Al) -type ordered
structures. The ordered structures martensitically undergo the non-conventional layered structures on further
cooling. These structures are called as 3R, 9R or 18R martensites depending on the stacking sequences
on the close-packed planes of the matrix.
When you are citing the document, use the following link http://essuir.sumdu.edu.ua/handle/123456789/35059
5
Li, Wenhua. "Shape Control and Functional Properties of Copper Chalcogenide Colloidal Nanocrystals". Doctoral thesis, Universitat de Barcelona, 2013. http://hdl.handle.net/10803/131051.
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The high quality CuxS nanocrystals were synthesized (Chapter 3) and the profound understanding and skills to prepare colloidal nanocrystals has been obtained and improved. It revealed a very simple synthetic route not only for the systematic investigation on the size control of the copper sulfide nanodisks but also for studying the influence of different stoichiometric ratios on the shape of copper sulfide nanocrystals. An increase of the precursor concentration in the growth solution resulted in the formation of tetradecahedral and dodecahedral nanocrystals. XRD results showed these nanodisks had a similar composition close to Cu1.78S as spherical nanocrystals, however, the tetradecahedral and dodecahedral nanocrystals were characterized with a composition close to Cu1.96S as deduced from their djurleite crystal phase. An oriented attachment was proposed as growth mechanism for polyhedrons growth and the slow nucleation rate allows an accurate control of the size and morphology of CuxS nanocrystals, from spheres and disks to tetradecahedrons and dodecahedrons by tuning the precursor concentration from 0.05 M to 1.0 M and reaction conditions. Dodecahedrons with different size can be easily prepared by elongating the reaction time. These nanocrystals can be used as cathodes in all-vanadium redox flow batteries and showed a significant improvement of the cathodic reaction reversibility, especially the dodecahedrons.
The CuxSe nanocubes with mean edge length of 17 nm±0.9 nm were synthesized (Chapter 4). The role of various metal ions playing on shape of CuxSe nanocrystals was discussed during the synthesis. The underlying mechanism was illustrated by preparing copper selenide nanocubes in the presence of Al ions whereas there was no any Al detected on the surface or within the final cubes. The morphology control is proved to be thermodynamically directed during the ripening regime and it exemplified the shape-direction of semiconductor nanocrystals by metal ions for the first time. It is a platform to produce cubic nanoparticles with different composition by cation exchange such as Ag2Te nanocubes. The plasmonic properties of the obtained nanocubes were further characterized and it demonstrated the strong plasmonic absorption peak at 950 nm.
A reproducible procedure to prepare highly monodisperse copper telluride nanocubes, nanoplates and nanorods was presented in Chapter 5. The procedure is based on the reaction of a copper salt with trioctylphosphine telluride (TOP-Te) in the presence of Lithium bis(trimethylsilyl) amide (LiN(SiMe3)2), trioctylphosphine (TOP), trioctylphosphine oxide (TOPO) and oleylamine (OLA). The high reaction temperature as 220 °C was found to be necessary to obtain cube-shaped NPs with narrow size distributions. By tuning the precursor ratio of Cu:Te, the size of these nanocubes could be controlled in the range between 10 and 20 nm. When decreasing the reaction temperature to 190 °C and the growth time to 15 min, highly homogeneous copper telluride nanoplates were produced. An increase of the TOP concentration from 0.125 ml to 0.75 ml resulted in the formation of nanorods. It was proposed the LiN(SiMe3)2 to activate the formation of a Cu-oleylamido complex and it is the actual species reacting with TOP-Te. The Cu-oleyamido complexes and/or lithium oleylamine may play a key role stabilizing the NP surface during growth. Copper telluride nanocubes and nanoplates display a strong near-infrared optical absorption at 900nm associated to localized surface plasmon resonances. This plasmon resonance can be exploited for the design of surface-enhanced Raman scattering (SERS) sensors for unconventional optical probes such as nile red containing oxygen based functional groups. This is the first time using Cu-chalcogenide as probes for SERS application and demonstrates its potential interest in future. Preliminary analysis of the use of copper telluride nanocubes as cytotoxic and photothermal agents is also discussed herein.Inicialment vam establir les condicions per preparar Cu(x)S. Com a mecanisme de creixement es va proposar el que es coneix amb el nom d’oriented attachment, en el qual els nanocristalls s’uneixen en una determinada orientació per formar altres formes més complexes. Establint les condicions en les quals es donava aquest mecanisme podíem produir nanocristalls de Cu2-xS amb un acurat control sobre la seva composició i/o forma, des de partícules esfèriques fins a nanopartícules en forma de disc o bé acanat amb partícules amb forma tetradecaèdríca o dodecaèdríca. Aquest control es va aconseguir simplement variant la concentració del precursor i les condicions de reacció. El segon sistema que es va estudiar va ser la producció de nanocristalls de Cu(x)Se. En el nostre treball preteniem descobrir nous procediments per sintetitzar nanocristalls de Cu(x)Se controlant la seva morfologia. Es va descubrir que es podia controlar la forma final dels nanocristalls de Cu(x)Se simplement introduint ions metàl•lics a la solució. En particular, en presència d’ions d’alumini es van produir nanocubs amb una longitud lateral de 17 nm ± 0.9 nm. Addicionalment es van estudiar les propietats plasmòniques d’aquests nanocubs. També es van utilizar aquests cubs de seleniur de coure com a base per produir cubs d’altres semiconductors a travès de l’intercanvi catiònic. Com a exemple es van produir cubs de Ag(2)Te. Finalment, es va estudiar el calcogenur binari, Cu(x)Te. Es va desenvolupar un mètode de síntesi per produïr nanocubs, nanoplaques i nanorods altament monodispersos. Es va observar que els paràmetres clau per controlar la forma eren la temperatura i la quantitat de surfactants. En canvi, per controlar el tamany es va observar que el paràmetre més important era la proporció entre Cu i Te present a la solució. Aquests nanocristalls posseïen propietats plasmòniques amb un pic d’absorpció al voltant dels 900 nm.
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Paine, Jeffrey Steven Nelson. "Multi-functional SMA hybrid composite materials and their applications /". This resource online, 1994. http://scholar.lib.vt.edu/theses/available/etd-06062008-162936/.
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Paulsson, Niklas. "Shape and dynamical consequences of the functional response of Daphnia magna". Thesis, Umeå universitet, Institutionen för ekologi, miljö och geovetenskap, 2013. http://urn.kb.se/resolve?urn=urn:nbn:se:umu:diva-80025.
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The zooplankter genus Daphnia have been one of the most popular model organism for studies on population dynamics for a long time. Most models constructed as a part of these studies use a Type II Hollings functional response and whether the Type III response typeoccurs in Daphnia sp. or not has been the subject of debate. Recent studies, however, reveal evidence of a Type III response and challenge this opinion. This study explains and illustrates the theoretical instability of a system modelled with the type II response and the more stable nature of a type III system through the use of both simulations and graphs.Furthermore, both a short term experiment in which Daphnia magna were fed Monoraphidium minutum so that the functional response could be studied and a long term experiment with the purpose of constructing a model that describes the population dynamics were performed. The functional response experiment indicated the possibility of a type III functional response, but due to large variation within low food density treatments it cannot be clearly distinguished from a type II response. The general trend, however, seems to indicate that if there is a type III response, it is not stabilizing. Unfortunately, the long termdynamics experiment suffered from too much unexplainable D. magna mortality to conclude anything besides the fact that enrichment seems to increase the maximum number Daphniaof individuals the system may sustain. Future studies should consider the improvements suggested of the experimental design to help prevent similar problems.
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Corum, Katharine Witkin. "Theoretical discovery of shape reactivity relationships in aluminum nanoclusters". Diss., University of Iowa, 2016. https://ir.uiowa.edu/etd/6718.
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Keggin-based aluminum nanoclusters have been noted to be efficient sorbents for the adsorption of arsenic, copper, lead, and zinc from water. Obtaining a molecular-level understanding of the adsorption processes associated with these molecules is of fundamental importance and could pave the way for rational design strategies for water treatment. Furthermore, due to their size and the availability of experimental crystal structures, Al nanoclusters are computationally tractable at the atomistic modeling level.
The adsorption of contaminants onto metal-oxide surfaces with nanoscale Keggin-type structural topologies has been established, but identification of the reactive sites and the exact binding mechanism are lacking. In more common surface studies the two main factors that affect reactivity have been found to be charge and functional group identity. Since Al nanoclusters each have a distinct shape we introduce the effects of shape as a third factor. In all the work presented in this dissertation, it is extremely apparent that the shape of the aluminum particle plays the most important role in nanoparticle reactivity studies.
We first focus on the reactivity of three aluminum polycations: [Al13O4(OH)24(H2O)12]7+ (Al13), [Al30O8(OH)56(H2O)26]18+ (Al30), and [Al32O8(OH)60(H2O)30]20+ (Al32). Using outer-sphere adsorption of sulfate and chloride as probe adsorbents, density functional theory (DFT) calculations determined that the reactivity can be represented as a function of particle topology, and not functional group identity or charge. Further exploring the shape-reactivity relationship of Al30 we reveal that cations and anions have opposing trends and ion reactivity can be generalized. It is determined that all cations favor the adsorption sites on the caps of Al30 and all anions favor adsorption in the beltway (middle) region. This result is supported by the visualization of the electrostatic potential of Al30 and three-dimensional induced charge density maps. The middle of the cluster is more positive than the caps, and this promotes anion adsorption in the beltway and cation adsorption on the caps.
Next we explore the reactivity of co-adsorption (outer-sphere anions and inner-sphere cations) onto Al30 through a collaborative approach. Al30 with two surface-bound Cu2+ cations (Cu2Al30-S) was experimentally crystallized in the presence of disulfonate anions; however, in the Cu2Al30-S structure the cations bind to the beltway region of the cluster. Using DFT we determined that the counter anions play a key (and governing) role in the crystallization of Cu2Al30-S. This result that outer-sphere adsorption dictates inner-sphere adsorption does not appear in surface calculations, it is unique to Keggin studies.
Seeing that all anions favor adsorption to the beltway region and all cations favor adsorption to the cap region we set out to determine if any reactivity patterns can be reversed. In order to do this inner-sphere As(V) and P(V) adsorption is modeled onto Al30 through another collaborative approach. The experimental crystal structure of (TBP)2[Al2(μ4-O8)(Al28(μ2-OH)56(H2O)26)]14+ (where TBP = t-butylphosphonate (CH3)3CPO3) has been synthesized, and using DFT calculations we can alter the R-group of P(V) or the DFT As(V) analogue to see if the inner-sphere anion ever prefers to bind to the cap region instead of the beltway. We observe that no matter the intrinsic properties of the R-group the anion always prefers to bind to the beltway region, which once again shows that the shape-reactivity relationship plays a major role in Keggin based structure reactivity.
Since As(V) is such a harmful ion we extend our As(V) adsorption studies to aluminum surfaces. As(V) has been experimentally shown to bind to aluminum surfaces in a bidentate binuclear configuration. By modeling a variety of configurations we can confirm and explain that the bidentate binuclear configuration is most stable due to the least amount of strain on the As(V) atom. Aluminum surfaces are common DFT models to study but are computationally expensive, due to this fact some people choose to model small Al octahedral cluster models instead. Comparing the reactivity of both systems we see a significant difference in energy magnitudes and ranges and can conclude that small Al octahedral cluster models cannot take place of aluminum surfaces.
All in all, the work presented in this dissertation provides an important contribution in our understanding of Keggin based Al compounds. Keggin based compounds are very sparsely studied computationally and this work helps to fill a knowledge gap. Hopefully the insights obtained from this work can help guide future Keggin based studies.
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Ying, Jia. "Structural Change and Its Assessment by Fluorescence Spectroscopy in Functional Polymers". 京都大学 (Kyoto University), 2014. http://hdl.handle.net/2433/192187.
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Ji, Wei. "Spatial Partitioning and Functional Shape Matched Deformation Algorithm for Interactive Haptic Modeling". Ohio University / OhioLINK, 2008. http://rave.ohiolink.edu/etdc/view?acc_num=ohiou1226364059.
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FORTINI, ANNALISA. "Functional characterization of thermally activated shape memory alloys for innovative adaptive structures". Doctoral thesis, Università degli studi di Ferrara, 2016. http://hdl.handle.net/11392/2403483.
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Il continuo impiego dei materiali a memoria di forma come elementi attivi deriva dall’effetto a memoria di forma e dalle peculiari proprietà meccaniche di questi materiali, tra le quali la capacità di recuperare elevate deformazioni (fino al 10 %), l’elevato rapporto potenza su peso e la capacità di generare elevati sforzi (fino a 800 MPa). Le leghe a memoria di forma sono spesso utilizzate all’interno di materiali polimerici, eventualmente rinforzati con fibre, per realizzare strutture attive deformabili le cui proprietà posso essere modificate in risposta a stimoli esterni. La possibilità di integrare materiali intelligenti all’interno di sistemi attuativi rappresenta una interessante scelta tecnologica ed una soluzione alternativa all’impiego di sistemi meccanici convenzionali, nello sviluppo di meccanismi con migliore semplicità costruttiva e fattibilità.
La possibilità di utilizzare elementi in lega a memoria di forma per la realizzazione di strutture deformabili è di particolare interesse nelle applicazioni aerodinamiche dove tale soluzione costruttiva permette di limitare l’introduzione di elementi di controllo che alterano il flusso. Il concetto di pale a geometria variabile, che possono modificare la loro forma in modo attivo, riducendo (o eliminando) così l’impiego di sistemi di controllo, rappresenta una soluzione estremamente interessante. Sebbene vi siano numerose pubblicazioni e brevetti riguardanti l’impiego di elementi in lega a memoria di forma per il miglioramento dell’efficienza aerodinamica e strutturale dei dispositivi nel settore automotive, studi specifici relativi al comportamento di pale a geometria variabile ottenute con leghe a memoria di forma non sono presenti in letteratura.
Scopo del presente lavoro è lo sviluppo e la caratterizzazione sperimentale di un innovativo concetto di pala a geometria variabile, ideata per l’impiego all’interno di ventole di raffreddamento di motori a combustione interna di macchine movimento terra. La pala in oggetto prevede una struttura composita formata da una matrice polimerica, che fornisce l’elasticità al corpo palare, al cui interno sono alloggiate lamine in lega a memoria di forma che rappresentano gli elementi attivi.
Al fine di studiare la fattibilità del sistema in termini di adeguato comportamento flessionale delle lamine all’interno della struttura composita della pala, la prima parte del lavoro ha riguardato la caratterizzazione sperimentale del materiale in lega NiTi. La caratterizzazione termica ha permesso l’ottimizzazione dei parametri di trattamento termomeccanico di memorizzazione della forma (temperatura, tempo e grado di deformazione), i quali sono stati determinati sperimentalmente al fine di massimizzare l’effetto a memoria di forma della lamina. Il recupero della forma da parte del materiale, come risultato delle trasformazioni allo stato solido termicamente attivate, è stato valutato prendendo in considerazione l’evoluzione del valore percentuale di recupero della forma all’aumentare
Acknoledgments
del numero di cicli di attivazione eseguiti. I risultati sperimentali hanno permesso di stabilire il trattamento termomeccanico più adatto in relazione al recupero a flessione da parte della lamina. Partendo quindi dall’esigenza di valutare la capacità di attivazione della lamina in lega NiTi quando inserita all’interno di una matrice polimerica, è stato progettato e realizzato un primo prototipo di struttura composita costituito da una singola lamina collocata all’interno di una matrice polimerica. La capacità di deformazione a flessione è stata studiata attraverso l’esecuzione di cicli di attivazione ripetuti. Le attivazioni termiche hanno previsto l’impiego sia di un sistema a fluido sia di un sistema a flusso d’aria.
Lo studio sperimentale condotto sul prototipo di struttura composita con una singola lamina è stato propedeutico al successivo sviluppo della pala a geometria variabile. L’analisi della sua capacità di deformazione è stata condotta attraverso il confronto tra quattro diverse matrici polimeriche al fine di stabilire il miglior compromesso tra rigidezza e deformazione flessionale per la specifica applicazione in esame. Le modifiche di forma della pala, derivanti dall’effetto a memoria di forma delle lamine, sono state studiate sperimentalmente mediante l’impiego di una galleria del vento appositamente progettata e realizzata, al fine di riprodurre le reali rampe termiche degli scambiatori di calore. I risultati sperimentali hanno evidenziato la possibilità di realizzare un sistema di controllo passivo per ventilatori assiali applicati nel settore automotive sfruttando un sistema di attuazione con leghe a memoria di forma in grado produrre modifiche della geometria palare che ne migliorano il comportamento aerodinamico.The ongoing employment of Shape Memory Alloys (SMAs) as solid-state actuators results from the Shape Memory Effect (SME) and the unique mechanical characteristics of these materials, including high reversible strain (up to 10 %), high-power to weight ratio and the ability to generate high recoverable stresses (up to 800 MPa). SMAs are frequently combined within polymeric materials, also reinforced with embedded fibres, to produce adaptive structures whose properties could be tuned in response to external stimuli. The integration of smart materials in actuation systems represents an excellent technological opportunity and an alternative solution to conventional mechanical systems for the development of mechanisms with improved simplicity and reliability. The possibility to use SMA elements for morphing structures is particularly attractive for aerodynamic applications where this actuation solution prevents the introduction of flow-disturbing control elements. The notion of smart advanced blades, which can control themselves and reduce (or eliminate) the need for an active control system, is a highly attractive solution in blade technology. Despite a large number of publications and patents relating to the employment of SMAs for enhancing aerodynamic and structural efficiency of automotive applications, specific studies on the behaviour of SMA-based morphing blades are not available in literature. The aim of this work is the development and the experimental characterisation of a novel concept of morphing blade, intended for cooling fan of internal combustion engines for earth moving machines. The variable-geometry blade comprises a composite structure made up of a polymeric compound, for the elastically deformable body of the blade, with embedded SMA strips as active elements. To assess the reliability of the SMA strip to provide the proper bending behaviour in the composite structure of the blade, the first phase of the work concerned the experimental characterisation of the NiTi material. The thermal characterisation allows to study the best shape setting parameters (temperature, time and strain) which were experimentally tuned to maximise the SME in the NiTi strip. The recovery behaviour of the SMA material, as a result of the thermally activated solid to solid phase transformations, was assessed by considering the percentage of shape recovery with the increasing number of thermal cycles. The experimental findings enabled to set the proper thermomechanical treatment related to the bending recovery performance of the strip. Starting from the need to evaluate the actuation ability of the NiTi strip when it is indirectly embedded into a polymeric matrix, a proof of concept of composite structure, comprising a single strip and a polymeric compound was design on purpose. The bending ability of the structure was evaluated by means of repeated recovery cycles. Thermal activations were achieved by means of a fluid flow and an airstream flow heating/cooling systems. Acknoledgments The experiments performed on the concept of the single strip composite structure were useful for the development of the morphing blade. The study of its morphing capability was conducted by comparing the behaviour of four different polymeric compounds in order to establish the best compromise between stiffness and deflection behaviour for the intended application. The shape changes of the blade, arising from the SME behaviour of the embedded thermomechanically treated NiTi strips, were experimentally evaluated through a purpose-built wind tunnel, developed to reproduce the actual automotive thermal ramps of the heat exchanger. Experimental findings highlighted the opportunity to generate an innovative passive control system applied to an automotive cooling axial fan wherein the SMA driven activation enables the production of favourable aerodynamic shape changes.
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Shin, James. "Shape Memory Elastomers and Fatty Acid Organogelators: Functional Materials from Small Molecule Additives". University of Akron / OhioLINK, 2013. http://rave.ohiolink.edu/etdc/view?acc_num=akron1383340291.
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Peng, Bangan. "FUNCTIONAL 4D PRINTING BY 3D PRINTING SHAPE MEMORYPOLYMERS VIA MOLECULAR, MORPHOLOGICAL AND GEOMETRICALDESIGNS". University of Akron / OhioLINK, 2020. http://rave.ohiolink.edu/etdc/view?acc_num=akron1605873309517501.
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Lee, Wing-cheung, i 李永祥. "Functional coatings on Ti-6A1-4V and NiTi shape memory alloy for medical applications". Thesis, The University of Hong Kong (Pokfulam, Hong Kong), 2011. http://hub.hku.hk/bib/B4715052X.
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Due to its excellent biocompatibility and mechanical properties, Ti-6Al-4V alloy has been extensively used in the medical field, especially as a material for hard tissue replacement. Owing to the unique shape memory and superelastic properties, NiTi shape memory alloy (SMA, with 50.8 at.% of Ni) has been investigated for load-bearing applications in orthopedics and dentistry. Since the longevity of current metal implants is approximately 10 to 15 years, many patients need to have revision surgeries in their lifetime. Therefore, there is great interest in the long-term stability, biocompatibility, bioactivity and other properties of Ti-6Al-4V and NiTi SMA implants. Implant-associated infections also pose serious threat to the success of metal implants. The goal of this project was to investigate several low-temperature surface modification techniques, including anodization and electrochemical deposition, and formulate coatings for potential clinical applications. Accordingly, several types of coatings were synthesized on Ti-6Al-4V and NiTi SMA substrates. Various aspects of the coatings, such as morphology, chemical composition, crystallinity, phase and bioactivity, were analyzed.
Firstly, a systematic study on the formation of titania nanotubes on Ti-6Al-4V by anodization was performed. Anodizing voltage and time were varied for comparisons. A dense and compact titania nanotube layer was synthesized on Ti-6Al-4V by anodizing at 25 V for 20 min. The titania nanotubes formed were rutile. After annealing at 500oC for 1 h, the titania nanotubes became anatase. The anatase phase exhibited better wettability than the rutile phase.
Secondly, dense and compact apatite coatings were formed on NiTi SMA samples through electrochemical deposition using mainly double-strength simulated body fluid (2SBF) as the electrolyte. The deposition conditions were varied and apatite coating characteristics studied. With the inclusion of collagen molecules (0.1 mg/ml) in the electrolyte (2SBFC), apatite/collagen composite coatings were fabricated. Collagen fibrils were not only observed on the surface of composite coatings but also were embedded inside in the coatings and at the coating-substrate interface. Results obtained from transmission electron microscopic and X-ray diffraction analyses showed that the apatite crystals in apatite coatings and apatite/collagen composite coatings were calcium-deficient carbonated hydroxyapatite. Apatite/collagen composite coatings exhibited excellent hydrophilicity, whereas apatite coatings displayed hydrophobic surfaces.
Finally, gentamicin-loaded, tobramycin-loaded, and vancomycin-loaded apatite coatings and apatite/collagen composite coatings were synthesized on NiTi SMA samples through electrochemical deposition using different drug concentrations in the electrolytes. A comparative study of apatite coatings and apatite/collagen composite coatings as drug delivery vehicles were conducted. Different aspects of antibiotic-loaded coatings (surface characteristics, chemical composition, wettability, etc.) and in vitro release behaviour were investigated. The antibiotics were physically embedded in coatings during coating formation. Upon sample soaking in phosphate-buffered saline (PBS), the release profiles established for antibiotic-loaded coatings demonstrated different levels of initial burst release and subsequent steady release characteristics. Apatite coatings and apatite/collagen coatings displayed preferential incorporation of specific antibiotics. For instance, apatite/collagen coatings showed better vancomycin incorporation than apatite coatings and the incorporation of vancomycin was better than tobramycin for apatite/collagen coatings. Apatite coatings demonstrated better tobramycin incorporation than apatite/collagen composite coatings.published_or_final_version
Mechanical Engineering
Master
Master of Philosophy
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Hughes, Adam. "Determining the shape of a liquid droplet : from microscopic theory to coarse grained models". Thesis, Loughborough University, 2015. https://dspace.lboro.ac.uk/2134/19985.
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This thesis investigates the wetting of simple liquids using two density functional theory (DFT) models. The first model is a discrete lattice-gas model and the second a continuum DFT model of a hard-sphere reference system with an additional attractive perturbation. The wetting properties of liquids are principally investigated by studying the binding, or interface, potential of the fluid and this thesis presents a method by which a binding potential can be fully calculated from the microscopic DFT. The binding potentials are used to investigate the behaviour of the model fluid depending on the range to which particle interactions are truncated. Long ranged particle interactions are commonly truncated to increase computational efficiency but the work in this thesis shows that in making this truncation some important aspects of the interfacial phase behaviour are changed. It is demonstrated that in some instances by reducing the interaction range of fluid particles a shift in phase behaviour from wetting to non wetting occurs. The binding potential is an input to larger scale coarse grained models and this is traditionally given as an asymptotic approximation of the binding potential. By using the full binding potential, calculated from the DFT model, as an input, excellent agreement can be found between the results from the microscopic DFT model and the larger scale models. This is first verified with the discrete lattice-gas model where the discrete nature of the model causes some non-physical behaviour in the binding potentials. The continuum DFT model is then applied which corrects this behaviour. An adaptation to this continuum model is used to study short ranged systems at high liquid densities at state points below the `Fisher-Widom' line. The form of the decay of the density profiles and binding potentials now switches from monotonic to oscillatory. This model leads to highly structured liquid droplets exhibiting a step-like structure.
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Paine, Jeffrey S. "Multi-functional SMA hybrid composite materials and their applications". Diss., Virginia Tech, 1994. http://hdl.handle.net/10919/38219.
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Shape memory alloy (SMA) materials such as nitinol have unique properties associated with the shape recovery effect and the material’s phase changes that have been used in a variety of actuator and sensing applications. By embedding SMA elements into host composite materials, control or modification of the SMA hybrid composite’s structural properties can be accomplished inservice, thereby increasing the hybrid composite’s structural functionality. Previous studies addressed increasing composite materials’ functionality by enabling in-service control of their dynamic response. Utilizing the SMA’s substantial recovery stress and capacity to dissipate strain energy to increase the hybrid composite’s static functionality is addressed herein. Specific applications for SMA hybrid composites include improving composite material’s impact damage resistance and composite cylinder stress and deflection control.
In stress and deflection control of cylindrical structures, SMA actuators are placed within the composite cylinder to form an active compound cylinder. The active SMA elements can significantly reduce the internal pressure-induced radial dilation and creep so that under severe loading, piston to cylinder tolerances may be maintained. Similar to a conventional metallic compound cylinder, the active compound cylinder also reduces peak cylinder hoop stresses. Hybridizing composites with nitinol improves their impact resistance because of nitinol’s tremendous capacity to absorb impact strain energy through the stress-induced martensitic phase transformation. The amount of impact damage is reduced and the material’s resistance to impact perforation at various velocities is improved. The experimental response of nitinol hybrid composites and the associated mechanics are presented. The unique toughness and resistance to permanent deformation that is a result of the stress-induced martensitic phase transformation enables the nitinol to absorb on the order of 4 times the strain energy of high alloy steel and 16 times that of many graphite/epoxy composites.
In most static applications where SMA elements are used for reinforcement, maintaining the integrity of the interface between the SMA elements and the host polymeric matrix composite material is critical to operation. The relationship between preparation of SMA elements for hybrid composite fabrication and interfacial bond strength is presented to address this issue. The mechanics of interfacial shear failure between SMA element and composite is also presented.Ph. D.
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Corman, Etienne. "Functional representation of deformable surfaces for geometry processing". Thesis, Université Paris-Saclay (ComUE), 2016. http://www.theses.fr/2016SACLX075/document.
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La création et la compréhension des déformations de surfaces sont des thèmes récurrent pour le traitement de géométrie 3D. Comme les surfaces lisses peuvent être représentées de multiples façon allant du nuage de points aux maillages polygonales, un enjeu important est de pouvoir comparer ou déformer des formes discrètes indépendamment de leur représentation. Une réponse possible est de choisir une représentation flexible des surfaces déformables qui peut facilement être transportées d'une structure de données à une autre.Dans ce but, les "functional map" proposent de représenter des applications entre les surfaces et, par extension, des déformations comme des opérateurs agissant sur des fonctions. Cette approche a été introduite récemment pour le traitement de modèle 3D, mais a été largement utilisé dans d'autres domaines tels que la géométrie différentielle, la théorie des opérateurs et les systèmes dynamiques, pour n'en citer que quelques-uns. Le principal avantage de ce point de vue est de détourner les problèmes encore non-résolus, tels que la correspondance forme et le transfert de déformations, vers l'analyse fonctionnelle dont l'étude et la discrétisation sont souvent mieux connues. Cette thèse approfondit l'analyse et fournit de nouvelles applications à ce cadre d'étude. Deux questions principales sont discutées.Premièrement, étant donné deux surfaces, nous analysons les déformations sous-jacentes. Une façon de procéder est de trouver des correspondances qui minimisent la distorsion globale. Pour compléter l'analyse, nous identifions les parties les moins fiables du difféomorphisme grâce une méthode d'apprentissage. Une fois repérés, les défauts peuvent être éliminés de façon différentiable à l'aide d'une représentation adéquate des champs de vecteurs tangents.Le deuxième développement concerne le problème inverse : étant donné une déformation représentée comme un opérateur, comment déformer une surface en conséquence ? Dans une première approche, nous analysons un encodage de la structure intrinsèque et extrinsèque d'une forme en tant qu'opérateur fonctionnel. Dans ce cadre, l'objet déformé peut être obtenu, à rotations et translations près, en résolvant une série de problèmes d'optimisation convexe. Deuxièmement, nous considérons une version linéarisée de la méthode précédente qui nous permet d'appréhender les champs de déformation comme agissant sur la métrique induite. En conséquence la résolution de problèmes difficiles, tel que le transfert de déformation, sont effectués à l'aide de simple systèmes linéaires d'équationsCreating and understanding deformations of surfaces is a recurring theme in geometry processing. As smooth surfaces can be represented in many ways from point clouds to triangle meshes, one of the challenges is being able to compare or deform consistently discrete shapes independently of their representation. A possible answer is choosing a flexible representation of deformable surfaces that can easily be transported from one structure to another.Toward this goal, the functional map framework proposes to represent maps between surfaces and, to further extents, deformation of surfaces as operators acting on functions. This approach has been recently introduced in geometry processing but has been extensively used in other fields such as differential geometry, operator theory and dynamical systems, to name just a few. The major advantage of such point of view is to deflect challenging problems, such as shape matching and deformation transfer, toward functional analysis whose discretization has been well studied in various cases. This thesis investigates further analysis and novel applications in this framework. Two aspects of the functional representation framework are discussed.First, given two surfaces, we analyze the underlying deformation. One way to do so is by finding correspondences that minimize the global distortion. To complete the analysis we identify the least and most reliable parts of the mapping by a learning procedure. Once spotted, the flaws in the map can be repaired in a smooth way using a consistent representation of tangent vector fields.The second development concerns the reverse problem: given a deformation represented as an operator how to deform a surface accordingly? In a first approach, we analyse a coordinate-free encoding of the intrinsic and extrinsic structure of a surface as functional operator. In this framework a deformed shape can be recovered up to rigid motion by solving a set of convex optimization problems. Second, we consider a linearized version of the previous method enabling us to understand deformation fields as acting on the underlying metric. This allows us to solve challenging problems such as deformation transfer are solved using simple linear systems of equations
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Anderson, Ricky D. "A parts classification and coding system utilizing functional and shape characteristics in a matrix-code structure". Ohio : Ohio University, 1992. http://www.ohiolink.edu/etd/view.cgi?ohiou1171483811.
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Monastyrsky, G. E., P. Ochin, A. V. Gilchuk i V. I. Kolomytsev. "Spark plasma sintering the spark-erosion powders of functional alloys". Thesis, Sumy State University, 2011. http://essuir.sumdu.edu.ua/handle/123456789/20798.
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Various shape memory alloys (Ti-Ni-Hf, Ni-Al and Cu-Al-Ni) were elaborated by
spark plasma sintering method from the micron, submicron and nano- sized particles
prepared by spark-erosion method in cryogenic liquid from preliminary melted master
alloys. These alloys are being developed as one of the alternatives for the intermediate
temperature applications (100-900oC). Spark plasma sintering method is express
method, which provides lower temperature and shorter holding time of sintering. It
makes possible to sinter materials from the pre-alloyed powders and eliminate the
intensive grains growth and precipitating processes influencing the mechanical and
functional properties of functional materials. The effects of processing parameters on the
martensitic transformation and microstructure of the sintered compacts were
investigated using XRD and SEM study. Temperatures of sintering were chosen
according to the assessed data of the decomposition, oxidation and others processes
carrying out in material. Although the precipitating processes were usually not
completely depressed, the intensive grain growth was also not found in most cases. Most
of the microstructure peculiarities of as processed powder were inherited by the sintered
material.
When you are citing the document, use the following link http://essuir.sumdu.edu.ua/handle/123456789/20798
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Huwe, Johann Reinhold [Verfasser]. "Histogram-Functional-Shape-Methode zur automatischen Schweregradeinteilung von Fibrose und Emphysem an Lungenlappen / Johann Reinhold Huwe". Gießen : Universitätsbibliothek, 2020. http://d-nb.info/1223461874/34.
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Rusinovn, P. O., J. M. Blednova i E. Y. Balayev. "Formation of Multi-functional TiNi Surface Layers via High-speed Flame Spraying". Thesis, Sumy State University, 2013. http://essuir.sumdu.edu.ua/handle/123456789/35286.
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This paper examines the formation of multisurface layers of a material with shape memory effect characteristics, using high-speed flame spraying of TiNi. The control parameters of the process were analysed and optimized spraying regimes applied in order to ensure the formation of a structure with grain size 30 - 170 nm and adhesion strength greater than 60 MPa.
When you are citing the document, use the following link http://essuir.sumdu.edu.ua/handle/123456789/35286
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Yu, Jie. "Classification of Genotype and Age of Eyes Using RPE Cell Size and Shape". Digital Archive @ GSU, 2012. http://digitalarchive.gsu.edu/math_theses/118.
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Retinal pigment epithelium (RPE) is a principal site of pathogenesis in age-related macular de-generation (AMD). AMD is a main source of vision loss even blindness in the elderly and there is no effective treatment right now. Our aim is to describe the relationship between the morphology of RPE cells and the age and genotype of the eyes. We use principal component analysis (PCA) or functional principal component method (FPCA), support vector machine (SVM), and random forest (RF) methods to analyze the morphological data of RPE cells in mouse eyes to classify their age and genotype. Our analyses show that amongst all morphometric measures of RPE cells, cell shape measurements (eccentricity and solidity) are good for classification. But combination of cell shape and size (perimeter) provide best classification.
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Roug-Hellichius, Liselotte. "Babble, grunts and words : a study of phonetic shape and functional use in the beginnings of language /". Stockholm : Department of linguistics, Stockholm University, 1998. http://catalogue.bnf.fr/ark:/12148/cb37684329j.
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Mara, Kyle Reid. "Evolution of the Hammerhead Cephalofoil: Shape Change, Space Utilization, and Feeding Biomechanics in Hammerhead Sharks (Sphyrnidae)". Scholar Commons, 2010. http://scholarcommons.usf.edu/etd/3502.
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The relationship between form and function is often used to elucidate the biological role of a structure. Hammerhead sharks offer a unique opportunity to study form and function through phylogeny. Because sphyrnid sharks display a range of cranial morphologies this group can be used to address questions about the evolution of cranial design and investigate the effects of changes in head morphology on feeding structures and bite force. Geometric morphometrics, volumetric analyses, morphological dissections, and phylogenetic analyses of the cephalofoil were used to gain insight into changes in cranial design through evolutionary history. External morphometrics and internal volumetric analyses indicated that while the external shape of the cephalofoil and placement of the sensory structures is variable through evolutionary history, the volumes of the internal cranial elements do not change. Constructional constraints within the cephalofoil were confined to sensory structures while feeding morphology remained relatively unchanged. Analysis of the morphology and biomechanics of the feeding apparatus revealed that through phylogeny the feeding system does not change among sphyrnid species. However, size-removed bite force was lower than predicted for all sphyrnid species except Sphyrna mokarran. Despite differences in head morphology between sphyrnid and carcharhinid sharks, the feeding bauplan is conserved in sphyrnid sharks with few changes to the feeding structures. Instead the chondrocranial and sensory structures are modified around the relatively static feeding core. Finally, the durophagous S. tiburo was found to consume hard prey in a manner that is biomechanically and morphologically different from other durophagous fishes. Furthermore, the diet of S. tiburo is constrained by the properties of its preferred prey.
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Huang, Ruqi. "Two contributions to geometric data analysis : filamentary structures approximations, and stability properties of functional approaches for shape comparison". Thesis, Université Paris-Saclay (ComUE), 2016. http://www.theses.fr/2016SACLS559/document.
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En ce moment même, d'énormes quantités de données sont générées, collectées et analysées. Dans de nombreux cas, ces données sont échantillonnées sur des objets à la structure géométrique particulière. De tels objets apparaissent fréquemment dans notre vie quotidienne. Utiliser ce genre de données pour inférer la structure géométrique de tels objets est souvent ardue. Cette tâche est rendue plus difficile encore si les objets sous-jacents sont abstraits ou encore de grande dimension. Dans cette thèse, nous nous intéressons à deux problèmes concernant l'analyse géométrique de données. Dans un premier temps, nous nous penchons sur l'inférence de la métrique de structures filamentaires. En supposant que ces structures sont des espaces métriques proches d'un graphe métrique nous proposons une méthode, combinant les graphes de Reeb et l'algorithme Mapper, pour approximer la structure filamentaire via un graphe de Reeb. Notre méthode peut de plus être facilement implémentée et permet de visualiser simplement le résultat. Nous nous concentrons ensuite sur le problème de la comparaison de formes. Nous étudions un ensemble de méthodes récentes et prometteuses pour la comparaison de formes qui utilisent la notion de carte fonctionnelles. Nos résultats théoriques montrent que ces approches sont stables et peuvent être utilisées dans un contexte plus général que la comparaison de formes comme la comparaison de variétés Riemanniennes de grande dimension. Enfin, en nous basant sur notre analyse théorique, nous proposons une généralisation des cartes fonctionnelles aux nuages de points. Bien que cette généralisation ne bénéficie par des garanties théoriques, elle permet d'étendre le champ d'application des méthodes basées sur les cartes fonctionnellesMassive amounts of data are being generated, collected and processed all the time. A considerable portion of them are sampled from objects with geometric structures. Such objects can be tangible and ubiquitous in our daily life. Inferring the geometric information from such data, however, is not always an obvious task. Moreover, it’s not a rare case that the underlying objects are abstract and of high dimension, where the data inference is more challenging. This thesis studies two problems on geometric data analysis. The first one concerns metric reconstruction for filamentary structures. We in general consider a filamentary structure as a metric space being close to an underlying metric graph, which is not necessarily embedded in some Euclidean spaces. Particularly, by combining the Reeb graph and the Mapper algorithm, we propose a variant of the Reeb graph, which not only faithfully approximates the metric of the filamentary structure but also allows for efficient implementation and convenient visualization of the result. Then we focus on the problem of shape comparison. In this part, we study the stability properties of some recent and promising approaches for shape comparison, which are based on the notion of functional maps. Our results show that these approaches are stable in theory and potential for being used in more general setting such as comparing high-dimensional Riemannian manifolds. Lastly, we propose a pipeline for implementing the functional-maps-based frameworks under our stability analysis on unorganised point cloud data. Though our pipeline is experimental, it undoubtedly extends the range of applications of these frameworks
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Litherland, Trevis J. "On the limiting shape of random young tableaux for Markovian words". Diss., Atlanta, Ga. : Georgia Institute of Technology, 2008. http://hdl.handle.net/1853/26607.
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Thesis (Ph.D)--Mathematics, Georgia Institute of Technology, 2009.Committee Chair: Houdre, Christian; Committee Member: Bakhtin, Yuri; Committee Member: Foley, Robert; Committee Member: Koltchinskii, Vladimir; Committee Member: Lifshitz, Mikhail; Committee Member: Matzinger, Heinrich; Committee Member: Popescu, Ionel. Part of the SMARTech Electronic Thesis and Dissertation Collection.
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Aubailly, Simon. "From coarse-grained to atomistic molecular modeling : how structure and dynamics shape intra-molecular communication and functional sites in proteins". Thesis, Orléans, 2017. http://www.theses.fr/2017ORLE2002/document.
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Dans cette thèse, nous nous sommes intéressés à la relation subtile qui existe entre lesstructures complexes des protéines et leurs fonctions encore plus raffinées que ces dernièreseffectuent. Basés sur deux descriptions différentes des protéines, à l’échelle de acide-aminé età l’echelle atomique, un de nos objectifs était de connecter des indicateurs structuraux calculésà partir de la topologie des protéines à des sites fonctionnels tels que les sites catalyiquesdans les enzymes. Un autre pan de la recherche de cette thèse était d’utiliser nos outils baséssur la structure et de mettre au point de nouvelles simulations numériques pour étudier lesdéterminants basiques structuraux et dynamiques de la communication intramoléculaire dansles protéines. Une première découverte fut de montrer comment l’analyse des modes normauxet la théorie des reseaux complexes conduisent à la prédiction des sites catalytiques dans lesenzymes. De plus, nous avons travaillé sur un groupe relativement peu connu de modes nor-maux qui ont la particularité d’être localisés à deux endroits très eloignés dans la structure desprotéines. Ces modes bilocalisés ont permis de réaliser des transferts d’énergie à des distancesconsidérables (plus de 70 Å). Finalement, des expériences de refroidissement effectuées sur unsystème protéine-eau décrit à l’échelle atomique ont dévoilé que le refroidissement induit unelocalisation spontanée d’énergie, indiquant certaines déformations des anneaux du benzenecomme possible centres de stockage de l’énergie dans les protéinesIn this thesis we have focused on the elusive relation that exists in proteins between theircomplex structures and the even more complex and sophisticated functions that they perform.Based on two different descriptions of proteins, at residue and atomistic scale, one of ouraims was to connect structural indicators computed from the topology of protein scaffoldsto hot spots in proteins such as catalytic sites in enzymes. Another goal of this thesis wasto employ our structure-based tools and set up original simulation scheme to investigate thebasic structural and dynamical determinants of intramolecular communication in proteins.As a first important finding, we have shown how normal mode analysis and specific graph-theoretical approaches lead to the prediction of catalytic sites in enzymes. Moreover, wehave concentrated our attention on an overlooked class of normal modes, that are stronglylocalized at two widely separated locations in protein scaffolds. These bilocalized modesturned out to efficiently mediate energy transfer even across considerable distances (morethan 70 Å). Finally, cooling experiments performed on a protein-water system described atatomic level have unveiled complex cooling-induced spontaneous energy localization patterns,pointing to specific deformation modes of benzene rings as potential energy-storage centers
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Russo, Claudio. "Dual-curing thiol-acrylate-epoxy thermosets for functional applications". Doctoral thesis, Universitat Rovira i Virgili, 2021. http://hdl.handle.net/10803/672432.
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Avui en dia, cada vegada més aplicacions exigeixen materials amb un disseny complex, missió complicada en
polímers termoestables, i per això el curat dual és una eina extremament útil en el disseny de termoestables. El curat
dual s'obté amb una combinació de dos processos d'entrecreuament de xarxa seqüencials o simultani. Els beneficis
del processat dual es basen en la seva flexibilitat en el processat i en la possibilitat de millorar les propietats del
material curat mitjançant processats en una etapa o en multi etapes. En aquest treball, vam desenvolupar un nou
sistema de doble curat basat en dos reaccions tipus "clic": l'addició de tiol-acrilat de Michael (primera etapa) i la
reacció tiol-epoxi (segona etapa). Aprofitant el sistema desenvolupat, es va demostrar que el processat mitjançant
curat en dues etapes tenia un gran valor potencial en l'aplicació com a unions adhesives, ja que permet un control
dimensional precís de la capa adhesiva i una major resistència adhesiva que el curat en un únic pas. Finalment, el
sistema de doble curat tiol-acrilat-epoxi es va utilitzar per desenvolupar polímers d'activació elèctrica amb memòria de
forma. La capacitat de resposta / activació elèctrica es va obtenir incorporant una làmina elèctricament conductora en
el polímer amb memòria de forma obtingut a partir d'un sistema tiol-acrilat-epoxi i aprofitant el processat dual. En
aquest disseny, el tradicional escalfament directe per calor extern (és a dir, forn) es reemplaça per un escalfament
intern per efecte Joule produït a la capa conductora quan s'aplica un voltatge i que es demostra més eficient.Hoy en día, cada vez más aplicaciones exigen materiales con un diseño complejo, misión complicada en polímeros termoestables, y por ello el curado dual es una herramienta extremamente útil en el diseño de termoestables. El curado dual se obtiene con una combinación de dos procesos de entrecruzamiento de red secuenciales o simultaneo. Los beneficios del procesado dual se basan en su flexibilidad en el procesado y en la posibilidad de mejorar las propiedades del material curado mediante procesados en una etapa o en multi etapas. En este trabajo, desarrollamos un novedoso sistema de doble curado basado en dos reacciones tipo "clic": la adición de tiol-acrilato de Michael (primera etapa) y la reacción tiol-epoxi (segunda etapa). Aprovechando el sistema desarrollado, se demostró que el procesado mediante curado en dos etapas tenía un gran valor potencial en aplicaciones como uniones adhesivas, puesto que permite un control dimensional preciso de la capa adhesiva y una mayor resistencia adhesiva que el curado en un único paso. Finalmente, el sistema de doble curado tiol-acrilato-epoxi se utilizó para desarrollar polímeros de activación eléctrica con memoria de forma. La capacidad de respuesta/activación eléctrica se obtuvo incorporando una lámina eléctricamente conductora en el polímero con memoria de forma obtenido a partir de un sistema tiol-acrilato-epoxi y aprovechando el procesado dual.
Nowadays, more and more applications demand materials with complex shape designs which is a difficult task when working with thermosetting polymers. Dual-curing processing is an extremely valuable tool for thermosets design. It consists in the combination of two sequential of simultaneous crosslinking process. The benefits of dual-curing processing rely on its processing flexibility and the properties enhancement of cured parts by single- or multi-stage scenarios. In this work, we developed a novel dual-curing system based on two “click” reactions: the thiol-acrylate Michael addition (first stage) and thiol-epoxy reaction (second stage). Exploiting the developed system, dual-curing processing was proved to have high potentiality in adhesive bonding application, allowing accurate dimensional control of the adhesive layer and higher adhesive strength than on-step curing. Finally, thiol-acrylate-epoxy dual-curing system was used to develop electroresponsive shape-memory polymers. The electroresponsive ability was obtained incorporating an electrically conductive layer into a thiol-acrylate-epoxy shape-memory polymer taking advantage of the dual-processing. In this design, the direct heating from external sources (i.e., oven) is replaced by a more efficient internal Joule heating produced in the conductive layer when an controlled voltage is applied. The electro activation of the SME resulted in significantly faster recovery and, using a custom-made thermoelectric control, a precise control of the recovery process was achieved
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Delyon, Alexandre. "Shape Optimisation Problems Around the Geometry of Branchiopod Eggs". Electronic Thesis or Diss., Université de Lorraine, 2020. http://www.theses.fr/2020LORR0123.
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Dans cette thèse nous nous intéressons à un problème de mathématiques appliquées à la biologie. Le but est d'expliquer la forme des œufs d'Eulimnadia, un petit animal appartenant à la classe des Branchiopodes, et plus précisément les Limnadiides. En effet, d'après la théorie de l'évolution il est raisonnable de penser que la forme des êtres vivants où des objets issus d'êtres vivants est optimisée pour garantir la survie et l'expansion de l'espèce en question. Pour ce faire nous avons opté pour la méthode de modélisation inverse. Cette dernière consiste à proposer une explication biologique à la forme des œufs, puis de la modéliser sous forme d'un problème de mathématique, et plus précisément d'optimisation de forme, que l'on cherche à résoudre pour enfin comparer la forme obtenue à la forme réelle des œufs. Nous avons étudié deux modélisations, l'une amenant à des problèmes de géométrie et de packing, l'autre à des problèmes d'optimisation de forme en élasticité linéaire. Durant la résolution du premier problème issue de la modélisation, une autre question mathématique s'est naturellement posée à nous, et nous sommes parvenus à la résoudre, donnant lieu à l'obtention du diagramme de Blaschke Santalo (A,D,r) complet. En d'autre mots nous pouvons répondre à la question suivante : étant donné trois nombres A,D, et r positifs, est-il possible de trouver un ensemble convexe du plan dont l'aire est égale à A, le diamètre égal à D, et le rayon du cercle inscrit égal à r ?In this thesis we are interested in a problem of mathematics applied to biology. The aim is to explain the shape of the eggs of Eulimnadia, a small animal belonging to the class Branchiopods}, and more precisely the Limnadiidae. Indeed, according to the theory of evolution it is reasonable to think that the shape of living beings or objects derived from living beings is optimized to ensure the survival and expansion of the species in question. To do this we have opted for the inverse modeling method. The latter consists in proposing a biological explanation for the shape of the eggs, then modeling it in the form of a mathematical problem, and more precisely a shape optimisation problem which we try to solve and finally compare the shape obtained to the real one. We have studied two models, one leading to geometry and packing problems, the other to shape optimisation problems in linear elasticity. After the resolution of the first modeling problem, another mathematical question naturally arose to us, and we managed to solve it, resulting in the complete Blaschke-Santalò (A,D,r) diagram. In other words we can answer the following question: given three positive numbers A,D, and r, and it is possible to find a convex set of the plane whose area is equal to A, diameter equal to D, and radius of the inscribed circle equal to r
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Mues, Andreas Wilhelm [Verfasser]. "Functional Integration of Floral Plant Traits: Shape and Symmetry, Optical Signal, Reward and Reproduction in the Angiosperm Flower / Andreas Wilhelm Mues". Bonn : Universitäts- und Landesbibliothek Bonn, 2020. http://d-nb.info/1218301872/34.
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Schreiner, Fernanda Reis. "Gramática de formas e o mobiliário modular multifuncional : um estudo de caso". reponame:Biblioteca Digital de Teses e Dissertações da UFRGS, 2009. http://hdl.handle.net/10183/25890.
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Esta pesquisa relaciona a teoria da Gramática de Formas (STINY;GIPS, 1972) com os princípios de modulação (HUANG, 2000), para subsidiar um método de antecipação das alternativas de composição capaz de prever a intervenção do usuário. O objeto de investigação, o móvel Vertibral, projetado por Joseph Keenan, é um conjunto de quatro módulos, compostos por 12 requadros lineares de madeira articulados permitindo a interpenetração (WONG,1998) para arranjo entre os módulos. A pesquisa baseia-se na recuperação da gênese do projeto Vertibral a partir de um modelo teórico (associação entre Gramática de Formas e modulação), e seguiu as seguintes etapas: análise do vocabulário do objeto da investigação; identificação e quantificação das relações espaciais possíveis entre dois módulos com a organização de matrizes; exercício de geração de regras formais e arranjos a partir das 232 relações espaciais quantificadas, em relação ao solo quantificadas; e, por último, comparação dos arranjos gerados por participantes do experimento de usabilidade, do tipo Co-discovery (KEMP;GELDEREN, 1996 e DUMAS;REDISH,1993), com relações espaciais quantificadas. A determinação de um método baseado nas etapas deste estudo de caso pode prever a multifuncionalidade para a concepção de um objeto, como o mobiliário.This research associates the Shape Grammar theory (STINY; GIPS, 1972) to modulation principles (Huang, 2000) as to structure a method for predicting the user’s intervention in modular furniture arrays. The research object, the furniture Vertibral, designed by Joseph Keenan, is constituted by a set of four modules, consisting of 12 wood articulated linear frameworks allowing interpenetration (WONG, 1998) for modules arrangement. The research departs from the retrieval of the Vertibral design principles and follows four steps model: a)object’s vocabulary analysis; b)identification and measurement of possible spatial relationships between two modules with matrices organization; c) generation exercise of formal rules and arrays from 232 computed spatial relations with ground plane reference; and d) comparison of produced arrays made for a usability experiment, according to Co-discovery method (KEMP; GELDEREN, 1996 and DUMAS;REDISH, 1993), with spatial relationships computed. The four stages method seems to have lead to a very high degree of success in creating reliable proxys for multi-functional furniture design.
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Bernardino, Gabriel. "Computational anatomy as a driver of understanding structural and functional cardiac remodeling". Doctoral thesis, Universitat Pompeu Fabra, 2019. http://hdl.handle.net/10803/668213.
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We present a statistical shape analysis framework to identify cardiac shape remodelling while accounting for individual´s natural variability and apply it in two clinical applications: comparing triathletes with controls, and comparing individuals who were born small-for-their-gestational-age (SGA) and controls. We were able to identify the shape remodelling due to the practice of endurance sport: it consisted a dilation of the left ventricle and an increase of the left ventricular myocardial mass. In the right ventricle (RV), the increase of volume was concentrated in the outflow. This changes in shape correlated with a better performance during exercise. In SGA, we found subtle differences in the RV that correlated with worse performance during exercise. These differences were bigger when SGA condition was combined with cardiovascular risk factors: smoking and overweight. Finally, we present a geometry processing technique for parcellating the RV cavity in 3 subvolumes for regional analysis without point-to-point correspondence.Presentamos un framework de análisis estadístico de forma para identificar remodelado cardiaco teniendo en cuenta la variabilidad natural de cada individuo. Utilizamos este framework en dos aplicaciones clínicas: triatletas e individuos nacidos pequeños-para-su-edad-gestacional (SGA). Identificamos el remodelado cardiaco en el caso de los triatletas: consistente en una dilatación del ventrículo izquierdo y un aumento de la masa miocárdica. En el ventrículo derecho (RV) la dilatación estaba concentrada en el tracto de salida. Este remodelado correlaciona con una mejor respuesta al ejercicio. En el análisis de SGA, encontramos sutiles cambios en el RV que correlacionaban con una peor respuesta al ejercicio. Estos cambios de forma fueron mayores si SGA se encontraba combinada con otros factores de riesgo cardiaco: tabaco y sobrepeso. Finalmente, presentamos una parcelación de la cavidad del RV en 3 subvolumenes para el análisis regional del RV cuando no es posible la correspondencia punto-a-punto.
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Moore, Timothy E. "Investigating the functional and adaptive significance of leaf size and shape variation in Jamesbrittenia (Scrophulariaceae (s.s). tribe Manulae) : an experimental and comparative approach". Bachelor's thesis, University of Cape Town, 2007. http://hdl.handle.net/11427/26300.
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The adaptive significance of variety in leaf forms remains a mystery for many plant groups. This study aimed, using a combined experimental and comparative approach, to investigate the functional significance of leaf size and shape variation, as well as the patterns of leaf form variation in the genus Jamesbrittenia within the context of phylogenetic history. Leaf sizes 63-measured Jamesbrittenia varied between 0.006cm² (in J. microphylla) and 6.52cm² (in J. megaphylla). Correlations between leaf form and the environment suggest leaf size and shape are primarily adapted to water availability, with only leaf dimension being significantly associated with temperature, while, soil fertility shows no relationship with leaf size. Life history is important, however, as broader leaved annuals and species with shorter-lived leaves are associated with more arid habitats. Results of the experimental trials suggest that the primary function leaf size and shape reduction is to reduce water loss, and not to increase heat shedding. While larger leaves transpire more on a leaf-by-leaf basis, transpiration may be higher in broader leaved species at the whole-plant due to higher total plant transpiration. Thus, it is suggested a reduction in leaf size and dimension in Jamesbrittenia is an adaptation to more arid environments. Alternatively, a change in life history may enable a plant to escape harsh periods and capitalise on favourable times. A small- to intermediate-leaved, perennial ancestor is inferred for Jamesbrittenia, which was associated with arid regions in either the summer or winter rainfall regions of southern Africa. Shifts to an annual life history in Jamesbrittenia are associated with a shift to drier habitats, particularly in the arid winter rainfall region of South Africa.
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Telschow, Fabian Joachim Erich [Verfasser], Stephan F. [Akademischer Betreuer] [Gutachter] Huckemann i Axel [Gutachter] Munk. "Equivariant Functional Shape Analysis in SO(3) with Applications to Gait Analysis / Fabian Joachim Erich Telschow ; Gutachter: Stephan F. Huckemann, Axel Munk ; Betreuer: Stephan F. Huckemann". Göttingen : Niedersächsische Staats- und Universitätsbibliothek Göttingen, 2016. http://d-nb.info/1118846907/34.
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Oliveira, Felipe Gomes de. "Estimação da profundidade por meio da fusão de dados de energia visual de múltiplas câmeras". Universidade Federal do Amazonas, 2011. http://tede.ufam.edu.br/handle/tede/4147.
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This research presents a visual data fusion approach to recover dense depth map from sequences of images. The conventional methods to estimate depth map have many drawbacks with respect to environment illumination changes and camera positioning. We propose a Global optimization data fusion strategy to improve the measurements from stereo and focus depth maps. Di erent from typical stereo and focus fusion techniques, we use a single pair of stereo cameras to acquire series of images scenes without occlusion and illumination constraints. Then, we use Energy Functional fusion to associate the geometric coherence with multiple frames. In order to evaluate the results we de ned a metric using similarity measurements between traditional stereo and the proposed approach. The experiments are performed in real scene images, and the estimated mapping was superior than those found using traditional stereo methods, which demonstrates the good performance and robustness of our approach.
Este trabalho propõe uma abordagem de Fusão de Dados Visuais para estimar a estrutura tridimensional de uma cena a partir de sequências de imagens obtidas por meio de duas ou mais câmeras. Os métodos convencionais para estimar mapas de profundidade apresentam desvantagens relacionadas a mudanças na iluminação do ambiente e posicionamento de câmeras. Por essa razão, foi proposta uma estrategia de Fusão de Dados baseada em minimiza c~ao de energia para aprimorar as medições proporcionadas pela disparidade entre pixels de uma imagem e pela variação de foco. A abordagem proposta faz uso de uma rede distribuída de sensores visuais utilizando um par de câmeras estéreo sem restrições de oclusão ou iluminação no processo de captura de imagens. A função de energia foi usada para integrar múltiplos frames e inferir a coerência geométrica contida na cena. Para avaliar os resultados obtidos foram utilizadas métricas da literatura através de medições de similaridade entre técnicas de estéreo tradicionais e a estrategia desenvolvida. Os experimentos foram conduzidos a partir de imagens de cenas reais, e as informações de profundidade estimadas foram qualitativamente superior que os resultados obtidos pelos métodos tradicionais. Tais informações demonstram a qualidade dos resultados alcançados pela técnica proposta.
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Presles, Benoît. "Caractérisation géométrique et morphométrique 3-D par analyse d'image 2-D de distributions dynamiques de particules convexes anisotropes. Application aux processus de cristallisation". Thesis, Saint-Etienne, EMSE, 2011. http://www.theses.fr/2011EMSE0632/document.
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La cristallisation en solution est un procédé largement utilisé dans l'industrie comme opération de séparation et de purification qui a pour but de produire des solides avec des propriétés spécifiques. Les propriétés concernant la taille et la forme ont un impact considérable sur la qualité finale des produits. Il est donc primordial de pouvoir déterminer la distribution granulométrique (DG) des cristaux en formation. En utilisant une caméra in situ, il est possible de visualiser en temps réel les projections 2D des particules 3D présentes dans la suspension. La projection d'un objet 3D sur un plan 2D entraîne nécessairement une perte d'informations : déterminer sa taille et sa forme à partir de ses projections 2D n’est donc pas aisé. C'est tout l'enjeu de ce travail: caractériser géométriquement et morphométriquement des objets 3D à partir de leurs projections 2D. Tout d'abord, une méthode basée sur le maximum de vraisemblance des fonctions de densité de probabilité de mesures géométriques projetées a été développée pour déterminer la taille d'objets 3D convexes. Ensuite, un descripteur de forme stéréologique basé sur les diagrammes de forme a été proposé. Il permet de caractériser la forme d'un objet 3D convexe indépendamment de sa taille et a notamment été utilisé pour déterminer les facteurs d'anisotropie des objets 3D convexes considérés. Enfin, une combinaison des deux études précédentes a permis d'estimer à la fois la taille et la forme des objets 3D convexes. Cette méthode a été validée grâce à des simulations, comparée à une méthode de la littérature et utilisée pour estimer des DGs d'oxalate d'ammonium qui ont été comparées à d’autres méthodes granulométriquesSolution crystallization processes are widely used in the process industry as separation and purification operations and are expected to produce solids with desirable properties. The properties concerning the size and the shape are known to have a considerable impact on the final quality of products. Hence, it is of main importance to be able to determine the granulometry of the crystals (CSD) in formation. By using an in situ camera, it is possible to visualize in real time the 2D projections of the 3D particles in the suspension.The projection of a 3D object on a 2D plane necessarily involves a loss of information. Determining the size and the shape of a 3D object from its 2D projections is therefore not easy. This is the main goal of this work: to characterize geometrically and morphometrically 3D objects from their 2D projections. First of all, a method based on the maximum likelihood estimation of the probability density functions of projected geometrical measurements has been developed to estimate the size of 3D convex objects. Then, a stereological shape descriptor based on shape diagrams has been proposed. It enables to characterize the shape of a 3D convex object independently of its size and has notably been used to estimate the value of the anisotropy factors of the 3D convex objects. At last, a combination of the two previous studies has allowed to estimate both the size and the shape of the 3D convex objects. This method has been validated with simulated data, has been compared to a method from the literature and has been used to estimate size distributions of ammonium oxalate particles crystallizing in water that have been compared to other CSD methods
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黃美香 i Mee-heung Cecilia Wong. "Shape analysis". Thesis, The University of Hong Kong (Pokfulam, Hong Kong), 1994. http://hub.hku.hk/bib/B31211999.
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Wong, Mee-heung Cecilia. "Shape analysis /". [Hong Kong : University of Hong Kong], 1994. http://sunzi.lib.hku.hk/hkuto/record.jsp?B13637642.
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Mitra, Saptarshee. "Experimental and numerical characterization of functional properties of sand molds produced by additive manufacturing (3D printing by jet binding) in a fast foundr". Thesis, Paris, ENSAM, 2019. http://www.theses.fr/2019ENAM0043.
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Les techniques traditionnelles pour la production des moules et des noyaux en sable utilisés en fonderie pour la coulée de métaux sont actuellement en cours de remplacement par des méthodes de fabrication additive, afin d'aider l’industrie aérospatiale/automobile à fabriquer des pièces de forme complexe d'une manière pratique. Le but de ce travail de recherche est d'étudier les propriétés fonctionnelles des moules imprimés en 3D utilisés lors de la coulée des pièces de forme complexe pour des applications d'ingénierie. Premièrement, le comportement mécanique des moules en sables imprimés en 3D a été analysé et caractérisé pour de différents paramètres du processus d'impression. Ensuite, les propriétés mécaniques et de transport de masse des moules en sable 3DP ont été étudiées. Les pièces imprimées en 3D pour la fonderie sont souvent fabriquées avec un type de technologie de fabrication additive appelé « powder-binder-jetting process » (processus de projection de liant de poudre). Des mesures sur trois points de la force de flexion, la densité, la porosité et la perméabilité, ont été effectués sur les moules fabriqués avec la technologie additive. En plus, l’influence de la température et de la fraction volumique du liant sur les propriétés mécaniques et de transport de masse a également été étudiée. Par ailleurs, la perméabilité des moules en sable imprimé a aussi été caractérisée par micro-tomographie de rayons X, permettant la modélisation avancée de la microstructure poreuse en suivant plusieurs étapes : 1) tomodensitométrie de petits échantillons de moules 3DP, 2) reconstruction volumétrique 3D de données, 3) simulation numérique pour la prédiction de la perméabilité à partir de volumes reconstruits et 4) modélisation du réseau de pores pour déterminer la distribution de la taille des pores et des constrictions. Des expériences ont également été conçues pour étudier les moules imprimés en 3D en termes de leur érosion lors de la coulée des métaux. Cela a permis d’identifier les paramètres optimaux du procédé d’impression 3D des moules, non seulement en termes de leurs propriétés mécaniques et de transport de masse, mais aussi pour minimiser l'érosion du moule durant la coulée métallique. Une méthode de détermination de la résistance à l'érosion des moules en sable a également été proposée, sur la base de la mesure du volume de la surface érodée à l'aide d'une technique d'ingénierie inverse moderneNowadays, traditionally manufactured sand molds and cores for metal casting are being progressively replaced by additively processed sand molds in aerospace/automotive industry, facilitating the production of quality cast parts with complex shapes. The type of additive manufacturing technology used to manufacture 3DP parts in foundries is known as powder-binder-jetting process. In this technology, the molds are produced without the use of any kind of additive tools and in a completely automated way using the layer based construction method. One of the most popular binder systems used in the manufacturing of 3DP mold is a furan-based resin binder, which holds the grain particles together. Their amounts and ratios can influence significantly the 3D printed mold properties, affecting casting quality. Therefore, it is essential to characterize the effects process parameters on the functionality of the 3DP molds. In the present work, the mechanical behavior of 3DP sand molds with varying printing process parameters was first investigated, followed by mass transport properties. To do so, a series of three-point bending strength tests, density measurements, porosity measurements and permeability tests were performed on the 3DP molds. Furthermore, the influence of time, temperature and binder volume fraction on the mechanical and mass transport properties was also investigated. Advanced modelling of the pore space was performed by using the reconstructed images provided by X-ray computed tomography, following different steps: X-ray CT scanning of small 3DP mold specimen, 3D volumetric reconstruction of data, numerical simulations for the prediction of permeability from the reconstructed volume, and pore network modelling for the determination of the pore size distribution. Experiments were also designed to investigate the 3D printed molds in terms of mold erosion during metal casting, in order to select the molding parameters to print 3D printed parts not only with good mechanical and mass transport properties but also to minimize the mold erosion during metal casting. Furthermore, a reverse engineering method for determination of the erosion resistance of sand molds has been established, to study the volume of the eroded surface
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Zhang, Kaiyu. "Shape-function modelling of horse hoof". Thesis, Loughborough University, 2008. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.516221.
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Giles, Paul A. "Iterated function systems and shape representation". Thesis, Durham University, 1990. http://etheses.dur.ac.uk/6188/.
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We propose the use of iterated function systems as an isomorphic shape representation scheme for use in a machine vision environment. A concise description of the basic theory and salient characteristics of iterated function systems is presented and from this we develop a formal framework within which to embed a representation scheme. Concentrating on the problem of obtaining automatically generated two-dimensional encodings we describe implementations of two solutions. The first is based on a deterministic algorithm and makes simplifying assumptions which limit its range of applicability. The second employs a novel formulation of a genetic algorithm and is intended to function with general data input. Keywords: Machine Vision, Shape Representation, Iterated Function Systems, Genetic Algorithms.
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Jackson, Todd Robert. "The geometric design of functional shapes". Thesis, Massachusetts Institute of Technology, 1997. http://hdl.handle.net/1721.1/42610.
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Rouhani, Mohammad. "Shape Representation and Registration using Implicit Functions". Doctoral thesis, Universitat Autònoma de Barcelona, 2012. http://hdl.handle.net/10803/129637.
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Les representacions de forma i registre són dos problemes importants tant en la visió per computador com en els gràfics. La representació d'un núvol de punts a través d'una funció implícita proporciona major nivell d'informació alhora de descriure les dades. Aquesta representació pot ser més compacta, més robusta al soroll i als \textit{outlier}, pel que pot ser explotada diferents aplicacions de visió per computador. La primera part d'aquesta tesi aborda representacions de forma implícites que inclouen tant la representació mitjançant \textit{B-splines} i polinomials. Primer es proposa una aproximació per mesurar la distancia geomètrica entre un núvol de punts i una superfície implícita. L'anàlisi de la distancia proposada mostra una estimació acurada amb un comportament suau. Aquesta distància és usada en un algorisme d'ajustament quadràtic basat en RANSAC. A més a més, atès que la informació de gradient de la distància respecte els paràmetres de la superfície pot ser calculat analíticament, els paràmetres de la superfície poden ser refinats utilitzant l'algorisme de Levenberg-Marquadt. Seguint un enfocament diferent, un algorisme d'ajustament algebraic es pot utilitzar per representar un objecte a través de \textit{B-splines} implícites. El resultat és una superfície suau i flexible que pot ser representada en diferents nivells de detall. Aquesta propietat ha estat explotada per solucionar el problema de registració a la segona part de la tesi. En el mètode de registració proposat, el model és substituït amb la representació implícita proposada en la primera part, i desprès la registració punt a punt és converteix en una registració punt a model en un nivell superior d'abstracció. Aquesta representació es pot beneficiar de diferents distancies per accelerar el proces de registració sense haver de cercar correspondències. Finalment, el problema de registre de models no rígids és abordat mitjançant d'una aproximació de la distància quadràtica que està basada en la informació de la curvatura del conjunt de models. Aquesta aproximació s'utilitza en un model \textit{Free Form Deformation} (FFD) per actualitzar la seva xarxa de control. Després és mostra com una aproximació acurada de la distància pot beneficiar el problema de registració no-rígida.Shape representation and registration are two important problems in computer vision and graphics. Representing the given cloud of points through an implicit function provides a higher level information describing the data. This representation can be more compact more robust to noise and outliers, hence it can be exploited in different computer vision application. In the first part of this thesis implicit shape representations, including both implicit B-spline and polynomial, are tackled. First, an approximation of a geometric distance is proposed to measure the closeness of the given cloud of points and the implicit surface. The analysis of the proposed distance shows an accurate distance with smooth behavior. The distance by itself is used in a RANSAC based quadratic fitting method. Moreover, since the gradient information of the distance with respect to the surface parameter can be analytically computed, it is used in Levenberg-Marquadt algorithm to refine the surface parameters. In a different approach, an algebraic fitting method is used to represent an object through implicit B-splines. The outcome is a smooth flexible surface and can be represented in different level from coarse to fine. This property has been exploited to solve the registration problem in the second part of the thesis. In the proposed registration technique the model set is replaced with an implicit representation provided in the first part; then, the point-to-point registration is converted to a point-to-model one in a higher level. This registration error can benefit from different distance estimations to speed up the registration process even without need of correspondence search. Finally, the non-rigid registration problem is tackled through a quadratic distance approximation that is based on the curvature information of the model set. This approximation is used in a free form deformation model to update its control lattice. Then it is shown how an accurate distance approximation can benefit non-rigid registration problem.
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Praßni, Jörg-Stefan, Timo Ropinski, Jörg Mensmann i Klaus Hinrichs. "Shape-based Transfer Functions for Volume Visualization". University of Münster, Germany, 2010. http://urn.kb.se/resolve?urn=urn:nbn:se:liu:diva-93039.
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We present a novel classification technique for volume visualization that takes the shape of volumetric features into account. The presented technique enables the user to distinguish features based on their 3D shape and to assign individual optical properties to these. Based on a rough pre-segmentation that can be done by windowing, we exploit the curve-skeleton of each volumetric structure in order to derive a shape descriptor similar to those used in current shape recognition algorithms. The shape descriptor distinguishes three main shape classes: longitudinal, surface-like, and blobby shapes. In contrast to previous approaches, the classification is not performed on a per-voxel level but assigns a uniform shape descriptor to each feature and therefore allows a more intuitive user interface for the assignment of optical properties. By using the proposed technique, it becomes for instance possible to distinguish blobby heart structures filled with contrast agents from potentially occluding vessels and rib bones. After introducing the basic concepts, we show how the presented technique performs on real world data, and we discuss current limitations.
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Guerfi, Malik. "Les polynômes de Laguerre-Hahn affines discrets". Paris 6, 1988. http://www.theses.fr/1988PA066275.
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On montre que les polynômes semiclassiques sont des polynômes de Laguerre-Hahn affines et réciproquement. On étudie les polynômes corécursifs et les polynômes associés des polynômes de Laguerre Hahn affines. On généralise tous ces résultats aux polynômes semiclassiques discrets (avec l'opérateur de Hahn)
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Trey, Baptiste. "Existence et régularité des formes optimales pour des problèmes d'optimisation spectrale Free boundary regularity for a multiphase shape optimization problem. Communications in Partial Dfferential Equations Regularity of optimal sets for some functional involving eigenvalues of an operator in divergence form Existence and regularity of optimal shapes for elliptic operators with drift. Calculus of Variations and Partial Differential Equations". Thesis, Université Grenoble Alpes, 2020. http://www.theses.fr/2020GRALM019.
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Dans cette thèse, on étudie l'existence et la régularité des formes optimales pour certains problèmes d'optimisation spectrale qui font intervenir un opérateur elliptique avec condition de Dirichlet.On s'intéresse d'abord au problème de la minimisation de la valeur propre principale d'un opérateur avec un terme de transport borné.Que le terme de transport soit fixé ou non, ce problème admet une solution parmi les quasi-ouverts, et si le terme de transport est en outre le gradient d'une fonction Lipschitzienne, alors les solutions sont des ouverts localement de classe C^{1,alpha} en dehors de points exceptionnels.On étudie ensuite en dimension deux la régularité des solutions à un problème d'optimisation à plusieurs phases pour la première valeur propre du Laplacien de Dirichlet.Enfin, on s'intéresse aux ensembles optimaux pour la somme des k premières valeurs propres d'un opérateur elliptique sous forme divergence. On montre que les k premières fonctions propres sur un ensemble optimal sont lipschitziennes de sorte que les ensembles optimaux sont ouverts, et on étudie ensuite la régularité de la frontière des ensembles optimauxIn this thesis, we study the existence and the regularity of optimal shapes for some spectral optimization problems involving an elliptic operator with Dirichlet boundary condition.First of all, we consider the problem of minimizing the principal eigenvalue of an operator with bounded drift under inclusion and volume constraints.Whether the drift is fixed or not, this problem admits solutions among the class of quasi-open sets, and if the drift is furthermore the gradient of a Lipschitz continuous function, then the solutions are open sets and C^{1,alpha}-regular except on a set of exceptional points.Next, we study in dimension two the regularity of the solutions to a multi-phase optimization problem for the first eigenvalue of the Dirichlet Laplacian.Finally, we focus on the optimal sets for the sum of the first k eigenvalues of an operator in divergence form. We prove that the first k eigenfunctions on an optimal set are Lipschitz continuous so that the optimal sets are open sets, and we then study the regularity of the boundary of the optimal sets
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Lei, Thomas T. (Thomas Ting). "Functional design and shade adaptation in Acer species". Thesis, McGill University, 1992. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=39406.
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This is a broad, quantitative comparison of 12 maple species, representing both canopy and subcanopy growth forms, grown under two ecologically relevant light environments. The maple seedlings responded mainly to light intensity; light quality plays only a minor role in the induction of shade characteristics. While a light-mediated trade off between light and dark reactions of photosynthesis was evident at the chloroplast level, this did not lead to similar differences in assimilaton rates. Gap-grown seedlings showed no apparent compromise in photosynthetic response to dim light and lightflecks. Seedlings of subcanopy trees trade off wood strength for increases in plant size while canopy seedlings sacrifice plant size for wood strength. The demand for greater wood strength in seedlings of canopy trees appears to pose a strong developmental constraint that delays maturation. Free of this constraint, subcanopy species can devote more resource to reach adult size quickly and at an earlier age.
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Cowan, Oliver. "The functional ecology of Eastern Rûens Shale Renosterveld". Doctoral thesis, Faculty of Science, 2019. https://hdl.handle.net/11427/31683.
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Globally, ecosystems are under mounting pressure as biodiversity is lost at an ever increasing rate due to drivers such as habitat destruction and climate change. The systematic degradation of natural habitats witnessed today is often accompanied by a loss of ecosystem functioning and services which not only endangers the future of humankind but has consequences for all life on earth. To manage the ecological challenges facing us there is an urgent need to increase our understanding of how ecosystems function, the relation/ship between biodiversity and ecosystem functioning, and the effect habitat degradation can have on this relationship. Eastern Rûens Shale Renosterveld, located in the Overberg region of South Africa, is a vegetation type both critically endangered and poorly understood. Centuries of agricultural activity in the region has resulted in a landscape typified by fragments of pristine vegetation, in addition to communities in various states of degradation, embedded in an agricultural matrix. The current quantities of pristine vegetation are inadequate to meet conservation goals and conservation efforts are further challenged by the fact that little is known of the functional ecology of not only pristine fragments of Renosterveld, but the degraded communities in various stages of secondary succession. The overarching aim of this thesis is to better understand the relationship between biodiversity and ecosystem functioning across a degradation gradient in critically endangered Renosterveld vegetation within an agricultural landscape in South Africa. To achieve this, a variety of methods were employed using different lenses of analysis. In Chapter 2, I studied the components of biodiversity to assess the relationship between taxonomic and functional diversity indices and investigate the effect of habitat degradation. In Chapters 3 and 4, I used litter traps to investigate the effect of plant litter type, season and habitat degradation on litter decomposition rates and Springtail (Collembola) community dynamics, respectively. Finally, in Chapter 5, I constructed three high-resolution plant-pollinator networks from sites with distinct land-use histories and with different above-ground vegetation communities. The results revealed a complex association between different taxonomic and functional diversity indices, influenced by habitat degradation, with potential ecological and conservation implications. Particularly, the loss of functional redundancy in degraded sites is likely to reduce resilience to future environmental perturbations which may reduce ecosystem functions. Conversely, the similarities in both taxonomic and functional diversity indices between pristine and moderately degraded sites may be cautiously interpreted as the occurrence of successful passive restoration. Litter decomposition rates were shown to be variable with litter type and season revealed as important controlling factors. Although degradation did not appear to significantly affect iv decomposition rates, the initial nutrient content of litter appears to correlate with decomposition rate and it can be expected this ecosystem function will be accelerated where habitat degradation results in shifts in above-ground vegetation and subsequent litter input, specifically where the cover of non-native, nitrogen-rich annual species is increased. There was found to be a significant impact of litter type on community composition, and of sampling day on species richness, abundance and community composition, in Springtail communities. Despite the overall lack of effect of degradation on Springtail community dynamics, the abundance of the non-native Entomobrya multifasciata in degraded sites, and its absence from pristine sites, raises the intriguing possibility of its suitability as a bioindicator for habitat degradation. Comparisons to similar global studies revealed the Renosterveld networks to be highly functionally specialized. Assessing network dynamics across a degradation gradient showed the impact of above-ground vegetation structure on network properties with the more open and diverse vegetation structure and floral resources provided by the highly degraded site resulting in network indices more similar to that of the pristine site when compared to the relatively structurally uniform moderately degraded site. Although this thesis has enhanced our understanding of the functional ecology of Renosterveld, it has also highlighted knowledge gaps which still exist. Creating and collating a database of functional trait data can provide the building blocks for future ecological work. Furthermore, to truly gain a mechanistic understanding of the biodiversity-ecosystem function relationship one needs to utilise an integrated analysis which considers different facets of biodiversity, particularly functional diversity, across multiple trophic levels while simultaneously acknowledging the legacy effects that distinct land-use histories can impose at the community level.
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Awrejcewicz, Jan, Lidiya Kurpa i T. Shmatko. "Vibration of functionally graded shallow shells with complex shape". Thesis, Department of Automation, Biomechanics and Mechatronics, 2015. http://repository.kpi.kharkov.ua/handle/KhPI-Press/37081.
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The method for studying the geometrically nonlinear vibrations of functionally graded shallow shells with a complex planform is proposed. Сomposite shallow shells made from a mixture of ceramic and metal are considered. In order to take into account varying of the volume fraction of ceramic the power law is accepted. Formulation of the problem is carried out using the refined geometrically nonlinear theory of shallow shells of the first order (Timoshenko’s type). The R-functions theory, variational Ritz’s method, procedure by Bubnov Galerkin and Runge-Kytta method are used in the developed approach. A distinctive feature of the proposed approach is the method of reducing the initial nonlinear system of equations of motion for partial derivatives to a nonlinear system of ordinary differential equations. According to the developed approach first it is necessary to solve linear vibration problem. Further to solve elasticity problems for inhomogeneous differential equations with right hand side, containing eigen functions. Obtained solutions of these problems are applied for representation of unknown functions of the nonlinear problem. Application of the theory of R-functions on every step allows us to extend the proposed approach to the shell with arbitrary shape of plan and different kinds of boundary condition. The proposed method is validated by investigation of test problems for shallow shells with rectangular and elliptical planform and applied to new vibration problems for shallow shells with complex planform.
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Johansson, Anders. "Shape functions in calculations of differential scattering cross-sections". Thesis, Uppsala University, Department of Physics and Astronomy, 2010. http://urn.kb.se/resolve?urn=urn:nbn:se:uu:diva-126674.
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Two new methods for calculating the double differential scattering cross-section (DDSCS) in electron energy loss spectroscopy (EELS) have been developed, allowing for simulations of sample geometries which have been unavailable to earlier methods of calculation. The new methods concerns the calculations of the thickness function of the DDSCS. Earlier programs have used an analytic approximation of a sum over the lattice vectors of the sample that is valid for samples with parallel entrance and exit surfaces.The first of the new methods carries out the sum explicitly, first identifying the unit cells illuminated by the electron beam, which are the ones needed to be summed over. The second uses an approach with Fourier transforms, yielding a final expression containing the shape amplitude, the Fourier transform of the shape function defining the shape of the electron beam inside the sample. Approximating the shape with a polyhedron, one can quickly calculate the shape amplitude as sums over it’s faces and edges. The first method gives fast calculations for small samples or beams, when the number of illuminated unit cells is small. The second is more efficient in the case of large beams or samples, as the number of faces and edges of the polyhedron used in the calculation of the shape amplitude does not need to be increased much for large beams. A simulation of the DDSCS for magnetite has been performed, yielding diffraction patterns for the L3 edge of the three Fe atoms in its basis.