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1
Spiga, Pablo. "P elements in permutation groups." Thesis, Queen Mary, University of London, 2004. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.413152.
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2
Starbuck, Jonathan. "Structural studies of compounds containing p-block elements." Thesis, University of Bristol, 2001. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.340162.
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3
Matache, A. M. "Spectral and p-Finite Elements for problems with microstructure /." Zürich, 2000. http://e-collection.ethbib.ethz.ch/show?type=diss&nr=13815.
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4
Park, Gi-Ho. "p-Refinement Techniques for Vector Finite Elements in Electromagnetics." Diss., Georgia Institute of Technology, 2005. http://hdl.handle.net/1853/10602.
Повний текст джерелаАнотація:
The vector finite element method has gained great attention since overcoming the deficiencies incurred by the scalar basis functions for the vector Helmholtz equation. Most implementations of vector FEM have been non-adaptive, where a mesh of the domain is generated entirely in advance and used with a constant degree polynomial basis to assign the degrees of freedom. To reduce the dependency on the users' expertise in analyzing problems with complicated boundary structures and material characteristics, and to speed up the FEM tool, the demand for adaptive FEM grows high.
For efficient adaptive FEM, error estimators play an important role in assigning additional degrees of freedom. In this proposal study, hierarchical vector basis functions and four error estimators for p-refinement are investigated for electromagnetic applications.
5
Preissig, R. Stephen. "Local p refinement in two dimensional vector finite elements." Thesis, Georgia Institute of Technology, 1998. http://hdl.handle.net/1853/13739.
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6
Krebs, Andreas. "On solving nonlinear variational inequalities by p-version finite elements." [S.l.] : [s.n.], 2004. http://deposit.ddb.de/cgi-bin/dokserv?idn=974375454.
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7
Karamanos, George Sosei. "Large eddy simulation using unstructured spectral/h-p finite elements." Thesis, Imperial College London, 1999. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.392522.
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8
Wann, Derek A. "Gas-phase structures of molecules containing heavy p-block elements." Thesis, University of Edinburgh, 2005. http://hdl.handle.net/1842/1209.
Повний текст джерелаАнотація:
Gas-phase electron diffraction (GED) is the method of choice for determining the structures of molecules containing between two and 100 atoms, free from intermolecular interaction. However, for many molecules it becomes necessary to augment the experimental GED data with information from other sources. The SARACEN method, used routinely at Edinburgh when determining structures, allows computed parameters from ab initio and density functional theory (DFT) calculations to be used as extra data in the GED refinement process. This thesis describes the determinations of the gas-phase structures of molecules that contain heavy p-block elements, including examples from Groups 13, 14, 15 and 16. Each of the compounds studied was solid at room temperature, requiring heating to produce a suitable vapour pressure and vaporisation rate and testing the existing electron diffraction apparatus to its limits. Use was made of a new heated reservoir, recently developed in Edinburgh by a previous PhD student, which has allowed compounds to be studied that were previously inaccessible. The molecules that were studied during the course of this degree are: In(P3C2But2), In(P2C3But3), Sn(P2C2But2), Sb2(C6F6)3, Bi2(C6F6)3, Se(SCH3)2 and Te(SCH3)2. While determining the structures of these molecules, accurate theoretical geometries have been obtained using both ab initio and DFT methods. As a result a better understanding has been achieved of which methods are suitable for use in calculating the structures of molecules with heavy p-block elements. The use of pseudopotentials as opposed to all-electron basis sets proved necessary when performing calculations on such large molecules with heavy atoms. The extent to which these pseudopotentials, especially ones that consider very few electrons to be in the valence shell of an atom, can affect the calculated geometries has been shown to be considerable. In addition, methods being developed to compute vibrational corrections for gas-phase structure determination have been extended to the crystalline phase. Molecular dynamics simulations have been used to derive the effects of vibrations on average nuclear positions, relative to equilibrium positions. The differences, when applied to coordinates obtained experimentally by neutron diffraction yield experimental equilibrium structures.
9
Exley, Katherine Ann. "Structure, frequency and distribution of P elements in relation to P-M hybrid dysgenesis in Drosophila melanogaster." Thesis, University of Liverpool, 1989. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.279706.
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10
Lai, Chaoqiang. "Quantitative genetic variation induced by P transposable elements in Drosophila melanogaster." Thesis, University of Edinburgh, 1990. http://hdl.handle.net/1842/15184.
Повний текст джерелаАнотація:
To determine the ability of the P-M hybrid dysgenesis system of Drosophila melanogaster to generate mutations affecting quantitative traits, X chromosome lines were constructed in which replicates of isogenic M and P strain X chromosomes were exposed to a dysgcnic cross, a nondys-genic cross, or a control cross, and recovered in common autosomal backgrounds. Mutational heritabilities of abdominal and sternopleural bristle score were in general exceptionally high. P strain chromosomes were eight times more mutable than M strain chromosomes, and dysgcnic crosses three times more effective than nondysgenic crosses in inducing polygenic variation. However, mutational heritabilities of the bristle traits were appreciable for P strain chromosomes passed through one nondysgenic cross, and for M strain chromosomes backcrossed for seven generations to inbred P strain females. The new variation resulting from one generation of mu-tagenesis was caused by a few lines, with large effects on bristles score, and all mutations reduced bristle number. Among eight of these mutant lines and two additional mutant lines which occurred spontaneously during stock maintenance, the range of additive effects for both abdominal and sternopleural bristle scores are 2 to 9.5 bristles (1.2-5.0ap) in females, and 3.7 to 15.7 bristles (2.3-9.1<7p) in males. The effects of nine mutant chromosomes (the exception is line NDC(19)) on sternopleural bristle scores are similar and close to l.3fff, well within the wildtype range. The effects of mutants NDC(19) for both bristle traits, and lines DP(146) and DP(146)NAB for abdominal bristle scores, are extreme (2.53-5.53<7«) compared with the wildtype. This result supports the hypothesis that the distribution of effects of mutant genes on quantitative characters is highly variable, and possibly leptokurtic. The overall degree of dominance of all mutant X chromosomes suggests they are partially recessive, but the effect of line NDC(19) on abdominal bristle score appears completely recessive. Six of the mutant lines have similar low sternopleural bristle scores of about 15, are caused by allelic mutations with a map distance of approximately 24.7 cM, 4.7 cM from the cflocus. Deficiency mapping shows they are within chromosomal bands 8A4-8C6 Lines NDC(19) and DP(146) have extremely low abdominal and sternopleural bristle scores of 11.5 and 14.9, and of 10.3 and 12.5 respectively, and map closely linked to the y locus. The test of allclism and deficiency mapping indicate they are closely linked but at separate loci within chromosomal bands !B2;lB4-6 and 1B4-6;1B10, respectively, with some epistatic effects. They are apparently single mutant alleles with pleiotropic effects on both bristle traits and viability. The mutation of line NDC(19) is probably at the scute locus. In situ hybridization analysis suggests these two mutants are associated with insertion of P elements within chromosomal region 1A-1B10, but the other six mutants probably resulted from excision of P elements at the site of 8C.
11
Linheiro, Raquel. "Computational analysis of transposable element target site preferences in Drosophila melanogaster." Thesis, University of Manchester, 2011. https://www.research.manchester.ac.uk/portal/en/theses/computational-analysis-of-transposable-element-target-site-preferences-in-drosophila-melanogaster(33ac0a41-2fbd-4974-b6b6-db4e1e48a7b0).html.
Повний текст джерелаАнотація:
Transposable elements (TEs) are mobile DNA sequences that are a source of mutations and can target specific sites in host genome. Understanding the molecular mechanisms of TE target site preferences is a fundamental challenge in functional and evolutionary genomics. Here we used accurately mapped TE insertions in the Drosophila melanogaster genome, from large-scale gene disruption and resequencing projects, to better understand TE insertion site mechanisms. First we test predictions of the palindromic target site model for DNA transposon insertion using artificially generated P-element insertions. We provide evidence that the P-element targets a 14 bp palindromic motif that can be identified at the primary sequence level that differs significantly from random base composition in the D. melanogaster genome. This sequence also predicts local spacing, hotspots and strand orientation of P-element insertions. Next, we combine artificial P-element insertions with data from genome- wide studies on sequence properties of promoter regions, in an attempt to decode the genomic factors associated with P-element promoter targeting. Our results indicate that the P-element insertions are affected by nucleosome positioning and the presence of chromatin marks made by the Polycomb and trithorax protein groups. We provide the first genome-wide study which shows that core promoter architecture and chromatin structure impact P-element target preferences shedding light on the nuclear processes that influence its pattern of TE insertions across the D. melanogaster genome. In an effort to understand the natural insertion preferences of a wide range of TEs, we then used genome resequencing data to identify insertions sites not present in the reference strain. We found that both Illumina and 454 sequencing platforms showed consistent results in terms of target site duplication (TSD) and target site motif (TSM) discovery. We found that TSMs typically extend the TSD and are palindromic for both DNA and LTR elements with a variable center that depends on the length of the TSD. Additionally, we found that TEs from the same subclass present similar TSDs and TSMs. Finally, by correlating results on P-element insertion sites from natural strains with gene disruption experiments, we show that there is an overlap in target site preferences between artificial and natural insertion events and that P-element targeting of promoter regions of genes is a natural characteristic of this element that is influenced by the same features has the artificially generated insertions. Together, the results presented in this thesis provide important new findings about the target preferences of TEs in one of the best-studied and most important model organisms, and provide a platform for understanding target site preferences of TEs in other species using genomic data.
12
Zhu, Bin. "p-Version finite elements and applications in structural impact and damage detection /." access full-text access abstract and table of contents, 2005. http://libweb.cityu.edu.hk/cgi-bin/ezdb/thesis.pl?phd-bc-b19887565a.pdf.
Повний текст джерелаАнотація:
Thesis (Ph.D.)--City University of Hong Kong, 2005."Submitted to Department of Building and Construction in partial fulfillment of the requirements for the degree of Doctor of Philosophy" Includes bibliographical references (leaves 253-269)
13
PELOSI, Orietta. "The structural role of light elements in magmas: P, Cl and S." Doctoral thesis, Università degli Studi di Camerino, 2008. http://hdl.handle.net/11581/401883.
Повний текст джерелаАнотація:
This study is focused on the geochemical and structural behaviour of light elements in magmas. In particular we are interested in investigating the role of phosphorus, chlorine and sulfur in silicate glasses in order to get important information to apply in a natural model. The geochemical and structural role of P, S and Cl in silicate glasses of composition relevant for the Earth Sciences has been investigated by X-ray Absorption Spectroscopy (XAS). The geochemical behavior of these elements in silicate melts and glasses is of major importance for problems ranging from volcano-climate interactions to the genesis of ore deposits of great economic importance to industrial glass-forming processes and treatment of vitreous waste material from refuse incineration activities. Evaluation of such problems requires new data on the structural environments around P, Cl and S dissolved in silicate melts and potential interactions with metal cations. Direct structural data (local bonding environment) are lacking, due to experimental difficulty in analyzing minor to trace light elements. We collected high quality XANES and EXAFS data on synthetic glasses in order to obtain information on the local chemical and structural environment around the studied elements. Use of synthetic glasses produced under controlled pressure, temperature and oxygen fugacity conditions allowed to understand how the structural and geochemical role of these light elements vary according to the physical and chemical conditions existing in the magma chamber. Data analysis has been accomplished by comparison with well characterized model compounds with known absorber oxidation state and coordination number. Theoretical XANES calculations have further helped in understanding the chemical and structural environment of the studied elements (e.g. cations bonded to [PO4]3- groups or to Cl- and S2- anions) in the synthetic glasses
14
Lewis, Alan Peter. "The characterisation of p element-induced singed mutations in Drosophila melanogaster, and an analysis of the extent of mobilisation of transposable elements in a p-m hybrid dysgenic cross." Thesis, University of Leicester, 1987. http://hdl.handle.net/2381/34440.
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15
Bateman, Robert D. "Performance of U/P finite elements subjected to nearly incompressible linear axisymmetric orthotropic conditions." Thesis, Massachusetts Institute of Technology, 2011. http://hdl.handle.net/1721.1/66826.
Повний текст джерелаАнотація:
Thesis (M. Eng.)--Massachusetts Institute of Technology, Dept. of Civil and Environmental Engineering, 2011.Cataloged from PDF version of thesis.
Includes bibliographical references (p. 77).
Finite element analysis is a vastly expanding field which provides engineers a viable instrumentation to model and measure idealized constitutive stress strain relationships for various complex physical bodies. In the field of Civil Engineering, this tool has proven very useful to analyze problems that do not have a direct closed solution guided by elementary structural mechanics. Within this field, there are many choices of finite elements, and should be chosen by the engineer to best suit the given mathematical model. For structural analysis, displacement based elements are undeniably the most used in practice. However, these elements have limitations and in such cases, other elements should be used. In foundation design, it is important to accurately model soil deformations and stresses. If the ground conditions are proven to be best modeled orthotropic instead of isotropic, then a finite element analysis should be implemented. If the soil is also shown to be saturated and exhibiting an undrained condition, a finite element analysis with standard displacement based elements will produce erroneous results due to the formulation and therefore another choice of finite element must be made. The scope of this work is to graphically show the performance of U/P finite elements subjected to nearly incompressible linear axisymmetric orthotropic conditions and its superiority over standard displacement based finite elements in this situation.
by Robert D. Bateman.
M.Eng.
16
Tsoi, Kwok-Wing. "On special elements for p-adic representations and higher rank Iwasawa theory at arbitrary weights." Thesis, King's College London (University of London), 2018. https://kclpure.kcl.ac.uk/portal/en/theses/on-special-elements-for-padic-representations-and-higher-rank-iwasawa-theory-at-arbitrary-weights(95c87b01-0b66-4a9f-822b-ed6b7f381bb7).html.
Повний текст джерелаАнотація:
In this thesis, we develop a theory of special elements in the higher exterior powers (or, more precisely, in the higher exterior power biduals) of the Galois cohomology of general p-adic representations over number fields. These elements constitute a natural extension of the concept of a ‘higher rank Euler system’ and we present evidence that they encode detailed information about the structure of Galois cohomology groups. In particular, we prove that a canonical ideal that one can define in terms of these elements is contained in both the relevant higher Fitting ideal and the annihilator ideal of the associated Galois cohomology group. In fact, under mild hypotheses, we find that the special elements completely determine the relevant higher Fitting ideal of the cohomology groups. Building upon this result, we are then able to determine the complete structure of the torsion part of the quotient of the higher exterior powers of the Galois cohomology group modulo the subgroup generated by the special elements. By means of a first concrete application, we specialise our theory to the p-adic represen-tations that arise from the Tate motives with cyclotomic twists. In this way, we both recover and refine the theory of generalised Stark elements recently developed by Burns, Kurihara and Sano. At the same time, we are able to answer a question explicitly raised by both Wash-ington and Lang regarding the Galois structure of global units modulo cyclotomic units in abelian fields, and also strongly refine a result of El Boukhari regarding the Galois structure of higher algebraic K-groups. In the same way, we can also formulate conjectures concerning p-adic L-series that have been formulated in other settings in earlier work of Castillo and Jones and of Solomon.
17
Sánchez, René Javier. "Dissecting contributions of structural elements of PSGL-1 to its interaction with P-selectin using AFM." Thesis, Georgia Institute of Technology, 2003. http://hdl.handle.net/1853/17961.
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18
Gsiea, Abdusalam Mohamed Saleh. "An ab initio study of the origin of p-type doping in ZnO using group-V elements." Thesis, University of Newcastle Upon Tyne, 2011. http://hdl.handle.net/10443/1360.
Повний текст джерелаАнотація:
Zinc oxide is a transparent semiconductor with a direct wide band-gap 3.4 eV and large exciton binding-energy of 60 meV, that combine to make ZnO a promising material for possible applications such as optoelectronic devices, lasers and light emitting diodes. Recently, the difficulty in obtaining high quality p-type ZnO has attracted much attention. Considerable effort has been made to obtain p-type ZnO by doping with the group- V elements N, P, As, and Sb, with the anticipation of replacing oxygen atoms in the ZnO lattice. However, experimentally these dopants can produce both p-type and n-type conductivity. Here the results of first principles density functional theory calculations performed using the AIMPRO code are presented. By evaluating the relative energies of substitution on the oxygen and zinc sub-lattices, it is possible to predict the most likely forms of doping centres that might be achieved depending both upon the dopant species and whether the ZnO is grown under oxygen or zinc rich conditions. As a general trend, it is found that dopants tend to be stabilised in environments where covalent bonds with oxygen can be formed, such as substitution on the zinc sub-lattice. The doping properties of the group-V elements can be best understood by not considering the dopant atoms individually, but as a part of an atomic group such as phosphate and nitrate ions either substituting for host atoms, or lying in interstitial sites. The preferential formation of dopant-oxygen bonds leads to a revision of the zinc-vacancy based model for p-type doping (such as P-(VZn)2 complexes) to structures involving interstitial oxygen.
19
Kimura, Kiyoshi. "Species-specific factors affecting the population dynamics of P transposable elements in Drosophila melanogaster and Drosophila simulans." Diss., The University of Arizona, 1991. http://hdl.handle.net/10150/185657.
Повний текст джерелаАнотація:
In order to compare the population dynamics of P elements in the sibling species D. melanogaster and D. simulans, three sets of studies were performed. In a series of comparative mixed population experiments, P-M mixed populations of D. melanogaster evolved into P or Q populations, depending on the strength of the P strains used as the original parental strains. However, no mixed populations of D. simulans evolved into P populations; even when the strongest P strains of D. simulans were used, all mixed populations evolved into Q or M' populations. Using an excision assay system, excision frequencies in a variety of strains of D. melanogaster and D. simulans were measured. On average, excision frequencies of P elements from plasmids were significantly lower in D. simulans than in D. melanogaster. In addition, there were no statistically significant correlations between GD sterility and excision frequencies. Using single neomycin -marked P elements, transposition frequencies of P elements were compared in D. melanogaster and D. simulans. As with excision frequencies, transposition frequencies were lower in D. simulans than in D. melanogaster. In addition, the position of the original insertion site had a strong effect on transposition frequency. All of these three experiments showed significantly lower average activity of P elements in D. simulans than in D. melanogaster. This consistency suggests that the three sets of results were influenced either directly and/or indirectly by common factors, such as host-encoded factors. Therefore, differences in the activity of P elements in these two species may be influenced by different host-encoded factors. The absence of P elements in natural populations of D. simulans may also be explained by the presence of different host factors.
20
Carneiro, da Silva Joana Servulo Correia. "Population genetics of P transposable elements and their host species, with emphasis on Drosophila willistoni and Drosophila sturtevanti." Diss., The University of Arizona, 2000. http://hdl.handle.net/10150/284221.
Повний текст джерелаАнотація:
The evolution of the P element family was studied in members of the Drosophila willistoni and Drosophila saltans species groups (subgenus Sophophora). The transmission of P elements among species, their spread within species and the strength of selective constraints, as well as the level at which they are imposed on these elements, were investigated using DNA sequence data. Particular emphasis was placed on the evolution of the canonical P element subfamily. This subfamily includes the functional P element first isolated from Drosophila melanogaster, which was termed canonical. It includes also other P elements belonging to the saltans and willistoni groups that are closely related to it. Based on the divergence among canonical elements, it was estimated that they last shared a common ancestor 3 million years ago, and that a minimum of eleven horizontal transfer events among species have taken place since then. This indicates that horizontal transfer is more important than anticipated in the transmission of P elements among species. The evolution of P elements within species was studied in detail in Drosophila sturtevanti and Drosophila willistoni. First, the population structure of these species was inferred from nuclear (alcohol dehydrogenase) and mitochondrial (part of subunits 4 and 5 of NADH dehydrogenase, and the transfer RNA gene for histidine) markers. The results suggest that only peripheral populations of D. willistoni show significant genetic differentiation. In D. sturtevanti significant population subdivision was detected among populations in the central part of the distribution, as well as between these and peripheral populations. These results were used as a reference to which P element divergence among populations could be compared. No selective constraints were detected in the evolution of canonical P elements within these two species. However, those constraints are present when elements were compared between species. It is concluded that selection is mostly effective at the time of horizontal transmission between species. Furthermore, P elements are shown to spread faster among populations than do neutral markers. This suggests that the spread of P elements within species can be achieved quickly, and surpass barriers such as moderate levels of population structuring within a species.
21
Alessi, Dario <1990>. "Reviewing interactions between uranyl’s oxygen atom, hydrogen, p block elements, and their effects in uranium-oxygen bond length." Master's Degree Thesis, Università Ca' Foscari Venezia, 2020. http://hdl.handle.net/10579/18359.
Повний текст джерелаАнотація:
Thanks to the Cambridge Structural Database, in this thesis work has been selected several uranyl’s ion crystal structures, which share interactions between uranyl’s oxygen and block p elements, or hydrogen. These interactions belong to hydrogen bond, chalcogen and halogen bond or, in a more generic way, short contact interactions. In order to select the structures, the research fields were limited for certain elements to a value within their Van der Waals peak. It was evaluated the influence that these interactions provide to the uranyl’s ion bond length (U=Oyl) from two points of view: a) by considering the type of interacting element and b) by considering the type of donor atom in equatorial position. The data collected were also used to verify the existence of a trend that correlates the interaction length, or nature of equatorial ligands, to the uranyl’s bond length. A comparation between the IR and Raman data, provided by the original works, completes the overview. In conclusion, the main synthetic routes to achieve the structures analysed in this research were highlighted.
22
Piriou, Laurent. "Extensions entre foncteurs de la categorie des espaces vectoriels sur le corps premier a p elements dans elle-meme." Paris 7, 1995. http://www.theses.fr/1995PA077146.
Повний текст джерелаАнотація:
La categorie abelienne des foncteurs definis sur la categorie des espaces vectoriels de dimension finie sur un corps premier fini a valeurs dans la categorie des espaces vectoriels sur le meme corps n'est pas semi-simple. On etudie tout d'abord la filtration polynomiale de la sous-categorie des foncteurs analytiques: le resultat primordial est le calcul du foncteur de taylor du produit tensoriel de deux foncteurs. On retrouve ensuite, a l'aide de la notion de recollement de categories abeliennes, l'identification des sousquotients de la filtration polynomiale avec les categories des representations des groupes symetriques sur le corps de base ; ceci permet de construire les foncteurs simples. Le troisieme chapitre est consacre a l'etude des foncteurs de weyl, en particulier de leur comportement vis-a-vis du foncteur difference. On deduit de cette etude l'annulation du premier groupe d'extension de tout simple avec lui-meme. Tous ces outils sont utilises dans le dernier chapitre afin d'elucider le caractere artinien de certains foncteurs analytiques non-polynomiaux: ce resultat fournit un indice majeur en faveur de la conjecture artinienne (qui s'enonce ainsi: tout foncteur injectif indecomposable est artinien)
23
LEBAUD, MARIE-PIERRE. "Description de la formation d'un choc dans le p-systeme. Approximation de valeurs propres par des elements finis isoparametriques." Rennes 1, 1992. http://www.theses.fr/1992REN10094.
Повний текст джерелаАнотація:
La premiere partie de ce travail est consacree a l'etude d'un choc dans le p-systeme. On commence par construire, par la methode des caracteristiques, la solution faible entropique, presentant un choc, de l'equation scalaire en precisant sa regularite. A partir du p-systeme ecrit au moyen de ses invariants de riemann, on construit un schema iteratif initialise avec cette solution et on resout les equations lineaires obtenues; on verifie que la suite de fonctions trouvee converge uniformement vers une solution du p-systeme dont on donne les singularites. Dans la seconde partie, on s'interesse a l'approximation des valeurs propres d'un operateur elliptique par la methode des elements finis isoparametriques. Dans le cas d'un domaine quelconque de frontiere reguliere, si celle-ci est correctement approchee, on montre qu'on obtient egalement le phenomene de superconvergence observe dans le cas des elements finis conformes
24
IZAABEL, EL-HASSAN. "Contribution a l'etude du determinisme genetique de la susceptibilite aux elements transposables p dans les populations naturelles de drosophila melanogaster." Paris 6, 1988. http://www.theses.fr/1988PA066306.
Повний текст джерелаАнотація:
Polymorphisme des cytotypes p, m et intermediaires caracterises par leur capacite a reprimer les anomalies genetiques induites par les elements p de d. M. Etudie en correlation avec des elements p complets et defectifs
25
ADHAM-GEDEON, SAMAR. "Agregats bimetalliques a base de palladium : influence des elements s#2#p#2 sur la reaction d'hydrogenation du butadiene-1,3." Paris 6, 1992. http://www.theses.fr/1992PA066382.
Повний текст джерелаАнотація:
La synthese d'un catalyseur modele bimetallique a base de palladium, a ete realisee par l'intermediaire de la condensation en phase vapeur de jets atomiques sur silice. L'utilisation in situ des spectroscopies xps, ups et aes, et ex situ microscopie electronique et retrodiffusion d'ions nous a permis d'etudier l'effet des ajouts des elements de la colonne iv (pb, ge, sn) sur le palladium. Le mecanisme de croissance et de nucleation, ainsi que la variation des proprietes electroniques des agregats en fonction de la taille des particules ont ete mis en evidence. Ces catalyseurs modeles ont ete testes sur la reaction d'hydrogenation du butadiene-1,3. Pour les trois metaux etudies, nous avons montre la presence d'une selectivite en butene-1 inversant la sequence trouvee sur le palladium seul
26
Yilmaz, Asim Egemen. "Finite Element Modeling Of Electromagnetic Scattering Problems Via Hexahedral Edge Elements." Phd thesis, METU, 2007. http://etd.lib.metu.edu.tr/upload/12608587/index.pdf.
Повний текст джерелаАнотація:
In this thesis, quadratic hexahedral edge elements have been applied to the three dimensional for open region electromagnetic scattering problems. For this purpose, a semi-automatic all-hexahedral mesh generation algorithm is developed and implemented. Material properties inside the elements and along the edges are also determined and prescribed during the mesh generation phase in order to be used in the solution phase. Based on the condition number quality metric, the generated mesh is optimized by means of the Particle Swarm Optimization (PSO) technique. A framework implementing hierarchical hexahedral edge elements is implemented to investigate the performance of linear and quadratic hexahedral edge elements. Perfectly Matched Layers (PMLs), which are implemented by using a complex coordinate transformation, have been used for mesh truncation in the software. Sparse storage and relevant efficient matrix ordering are used for the representation of the system of equations. Both direct and indirect sparse matrix solution methods are implemented and used.
Performance of quadratic hexahedral edge elements is deeply investigated over the radar cross-sections of several curved or flat objects with or without patches. Instead of the de-facto standard of 0.1 wavelength linear element size, 0.3-0.4 wavelength quadratic element size was observed to be a new potential criterion for electromagnetic scattering and radiation problems.
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Frister, Jan Ole [Verfasser], Marina [Akademischer Betreuer] Rodnina, Kai [Gutachter] Tittmann, Holger [Gutachter] Stark, Ralf [Gutachter] Ficner, and Henning [Gutachter] Urlaub. "Recognition Elements for Elongation Factor P on the Ribosome / Jan Ole Frister ; Gutachter: Kai Tittmann, Holger Stark, Ralf Ficner, Henning Urlaub ; Betreuer: Marina Rodnina." Göttingen : Niedersächsische Staats- und Universitätsbibliothek Göttingen, 2019. http://d-nb.info/1200634187/34.
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Spry, Marcus P. "Synthesis and structural studies of macrocyclic complexes of the p-block (Sb, Ge, Te, O) and lanthanide (La, Ho, Er, Tm and Pr) elements." Thesis, University of Warwick, 1999. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.340984.
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Fluschnik, Till [Verfasser], Rolf [Akademischer Betreuer] Niedermeier, Rolf [Gutachter] Niedermeier, Bart M. P. [Gutachter] Jansen, and Stefan [Gutachter] Szeider. "Elements of efficient data reduction: fractals, diminishers, weights and neighborhoods / Till Fluschnik ; Gutachter: Rolf Niedermeier, Bart M. P. Jansen, Stefan Szeider ; Betreuer: Rolf Niedermeier." Berlin : Technische Universität Berlin, 2020. http://d-nb.info/1212508866/34.
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CUGIER, PHILIPPE. "Modelisation du devenir a moyen terme dans l'eau et le sediment des elements majeurs (n, p, si, ) rejetes par la seine en baie de seine." Caen, 1999. http://www.theses.fr/1999CAEN2019.
Повний текст джерелаАнотація:
La baie de seine est une zone tres enrichie en sels nutritifs apportes par la seine. Cet enrichissement du milieu entraine l'apparition de fortes biomasses phytoplanctoniques, caracteristiques des zones eutrophisees. En outre, depuis le debut des annees 80, la detection reguliere de phytoplancton toxique (dinophysis) oblige a une surveillance du milieu en periode estivale. Afin d'etudier le cycle des elements nutritifs (azote, phosphore, silicium) et de comprendre comment ils contribuent au controle de la production phytoplanctonique en baie de seine, un modele tridimensionnel de l'ecosysteme a ete developpe. Le modele est forme d'une partie hydrosedimentaire (modele sam-3d) et d'une partie ecologique considerant les principaux compartiments formant l'ecosysteme (sels nutritifs, phytoplancton, zooplancton,). Le modele ecologique de la baie de seine s'est avere capable de reproduire convenablement les principales caracteristiques physiques et biologiques de l'ecosysteme. L'etude des facteurs limitant la croissance phytoplanctonique montre, d'une part, le role important de la lumiere dans la zone du panache a proximite de l'estuaire ou les turbidites sont fortes et, d'autre part, le role respectif des 3 sels nutritifs. Malgre l'augmentation des apports d'azote au cours des 20 dernieres annees, il n'y a pas eu d'augmentation notable des biomasses phytoplanctoniques. La diminution des apports de phosphate durant la meme periode explique ce phenomene et le modele met en evidence une inversion de l'effet limitant de l'azote et du phosphate dans le panache au cours de cette periode. De plus, il semble, d'apres le modele, que la presence importante de flagelles en baie de seine soit fortement correlee aux faibles rapports si/n et si/p dans les apports de la seine. Enfin, l'etude, grace au modele, de scenarios de reduction d'apports d'azote et de phosphate par la seine, a permis d'estimer l'impact respectif des 2 types de reductions sur la production phytoplanctonique.
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Jung, M., and J. F. Maitre. "Some Remarks on the Constant in the Strengthened C.B.S. Inequality: Application to $h$- and $p$-Hierarchical Finite Element Discretizations of Elasticity Problems." Universitätsbibliothek Chemnitz, 1998. http://nbn-resolving.de/urn:nbn:de:bsz:ch1-199801431.
Повний текст джерелаАнотація:
For a class of two-dimensional boundary value problems including diffusion and elasticity problems it is proved that the constants in the corresponding strengthened Cauchy-Buniakowski-Schwarz (C.B.S.) inequality in the cases of h -hierarchical and p -hierarchical finite element discretizations with triangular meshes differ by the factor 0.75.
For plane linear elasticity problems and triangulations with right isosceles tri- angles formulas are presented that show the dependence of the constant in the C.B.S. inequality on the Poisson's ratio. Furthermore, numerically determined bounds of the constant in the C.B.S. inequality are given for three-dimensional elasticity problems discretized by means of tetrahedral elements.
Finally, the robustness of iterative solvers for elasticity problems is discussed briefly.
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Ashley, Kyle Thomas. "Constraining Metamorphic and Tectonic Evolution in Convergent Terranes: How Trace Elements and Mineral Inclusions Shape Mechanical and Reconstructive Models." Diss., Virginia Tech, 2015. http://hdl.handle.net/10919/52888.
Повний текст джерелаАнотація:
Conventional thermobarometry in metamorphic systems has been primarily limited to constraining peak temperature (or pressure) along a generalized P-T loop. This is largely attributed to the assumption that mineral assemblages and chemistries achieve a state closest to equilibrium with the maximum thermal (and therefore energetic) input at these peak conditions. However, this traditional approach is limited in providing much information about the evolution of a metamorphic terrane, which is modified by tectonic (kinematic) forces, fluid and component mobility, and heating duration.
The ubiquity of quartz in the continental crust has driven much interest in using the phase for thermobarometric purposes. In this dissertation, I discss the application of elastic theory in reconstructing conditions of inclusion encapsulation through inclusion pressure estimation with Raman spectroscopy. In some instances, overpressuring of quartz inclusions in garnet give evidence for high-pressure formation conditions. When analyses are collected from garnet core to rim, pressure paths along garnet growth can be inferred (if temperature can be reasonably estimated). In high-T, low-P terranes, quartz may become dilated if the inclusion adheres to the host. If a quartz inclusion is sufficiently stretched, transformation to a low-density polymorph may occur.
Trace element uptake, particularly Ti, have been characterized in quartz and understood to be the result of a temperature- (and to a lesser extent, pressure-) sensitive substitution for Si4+. However, the application of the Ti-in-quartz thermobarometer in quartz mylonites has led to mixed results due to the low-Ti resetting that occurs with dynamic recrystallization. We applied defect energy simulations and took a global assessment of deformed quartz trace element chemistries to infer that sweeping grain boundaries provide short pathways that allows localized re-equilibration with a Ti-undersaturated medium, resulting in Ti removal from the quartz lattice. In addition, thermodynamic pseudosection modeling has provided a method to assess Ti activity as a dynamic parameter – one that evolves as the phase stability changes through prograde and retrograde metamorphic reactions. With this understanding, better growth-composition models can be derived to infer complex pressure-temperature-time-deformation (P-T-t-D) histories of metamorphic rocks.
These techniques and results are coupled with conventional thermobarometry techniques to provide a more comprehensive picture of the conditions experienced by a rock through the evolution, from burial to exhumation to the Earth's surface. The thermal evolution is used to provide conceptual thermal-kinematic models to explain tectonic evolution and heat advection in the continental lithosphere in ancient mountain belts.Ph. D.
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Dozzi, M. V. "IMPROVING THE PHOTOCATALYTIC ACTIVITY OF TIO2 FOR ENVIRONMENTAL APPLICATIONS: EFFECTS OF DOPING AND OF SURFACE MODIFICATION." Doctoral thesis, Università degli Studi di Milano, 2012. http://hdl.handle.net/2434/167910.
Повний текст джерелаАнотація:
Different routes were explored for the solution of the two limiting aspects of TiO2 use in photocatalytic processes, i.e. its large band gap, allowing the exploitation of only a small portion of sunlight, and the fast recombination of photoproduced electron-hole pairs. The attention was first focused on the consequences of noble metal nanoparticles deposition on TiO2, with a systematic study on the photocatalytic performance of commercial TiO2 bearing gold nanoparticles deposited either by so-called deposition-precipitation, with particular attention to the method, either thermal or chemical, employed to reduce the Au(III) precursor into metallic gold, or by photodeposition. Two organic substrates, i.e. the azo dye Acid Red 1 and formic acid, were mainly employed as substrates in photocatalytic oxidative degradation kinetic tests.
In order to minimize the major drawback of TiO2 as a photocatalytic material, i.e. its high-energy band gap, sulphur, fluorine and boron were tested as dopants of TiO2. Doped materials prepared by the sol-gel method, containing different nominal dopant amounts and calcined at different temperatures, were systematically investigated in both liquid and gas phase photocatalytic reactions under polychromatic irradiation. Furthermore, the photo-oxidation of acetic acid was also investigated systematically as a function of irradiation wavelength, by collecting so-called action spectra, which represent the most powerful photocatalytic characterization tool to determine the effective wavelength-dependent response and activity of a photocatalyst. The comparison between the shapes of the absorption and the action spectra of the materials allowed one to distinguish between absorption features which are active or inactive in photocatalysis. XPS and EPR analyses gave an essential contribution in order to correlate extra absorption peaks to the chemical composition of doped-TiO2.
Finally, the effect of noble metal (Pt and Au) nanoparticles photodeposition on the activity of the best performing doped TiO2 photocatalysts calcined at 700°C was investigated in both energetically down-hill and up-hill reactions, i.e. in formic acid and acetic acid degradation in aqueous suspension and in hydrogen production from methanol/water vapor mixtures. Intriguing synergistic effects of TiO2 doping and of noble metal nanoparticles deposition were observed in both types of reaction.
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Mettling, Clément. "Utilisation de la transformation pour l'etude des elements regulateurs des genes de la glu chez drosophila melanogaster." Université Louis Pasteur (Strasbourg) (1971-2008), 1987. http://www.theses.fr/1987STR13152.
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Azif, Ettibari. "Solubilite des elements du groupe du platine (pt et pd) dans les liquides silicates en fonction de fo 2, fs 2, t, p et composition : experimentation, modelisation, implications metallogeniques et geochimiques." Orléans, 1998. https://tel.archives-ouvertes.fr/tel-00585305.
Повний текст джерелаАнотація:
L'etude experimentale a demontre (1) l'influence importante de certains parametres (fo2, composition de l'alliage metallique, fs2) sur la solubilite des egp dans les liquides basaltiques et (2) le role sensiblement moins important d'autres parametres (t, composition du liquide silicate). A 1 atm, 1300< t <1430\c et pour les compositions daf0, la solubilite des egp augmente avec la fo2 et t. Les egp sont dissous dans le bain silicate sous forme d'especes oxydees et metalliques. Le calcul de speciation montre la presence de trois (pd) et deux (pt) especes dissoutes dont les proportions varient avec la fo2. La dependance positive de la solubilite des egp avec la temperature impliquerait une preference pour les especes egp oxydees. L'introduction du fer dans le systeme silicate (daf5 et daf10) n'influe pas sur la tendance generale de solubilite des egp avec la fo2. Cependant, pt et pd sont dissous sous forme oxydee (2+). En presence de soufre, les solubilites des egp montrent une inversion de la tendance avec une augmentation des concentrations de pd et pd (1) vers les conditions reductrices et (2) avec l'introduction du fer. Le traitement thermodynamique des resultats et leur comparaison avec les concentrations en egp mesurees ou estimees dans un certain nombre de liquides naturels montre que : (1) en absence de soufre et pour des compositions de metal pur (pt et/ou pd), les concentrations predites sont tres superieures a celles des liquides naturels. La prise en compte d'alliages d'activite en egp < 1 reduit les ecarts entre les valeurs de pt et pd du modele et des liquides naturels. (2) en presence de soufre, et malgre l'absence de donnees precises sur la fs2 des systemes naturels, la comparaison est encourageante. Enfin, les resultats du calcul des coefficients de partage de pt et pd et leur comparaison avec ceux estimes a partir des abondances des egp dans le manteau montre que les teneurs observees ne sont pas le resultat d'un equilibre chimique entre le coeur et le manteau. La presence de soufre pourrait regler le probleme du surplus des egp et constitue une bonne hypothese de travail.
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SANGARE, MOUSTAPHA. "Amelioration de la qualite des calculs elements finis par l'analyse auto-adaptative. Controle de la precision, et optimisation des calculs elasto-statiques de structures en plaques et coques par la methode p. )." Paris, CNAM, 1994. http://www.theses.fr/1994CNAM0186.
Повний текст джерелаАнотація:
L'amelioration de la qualite des resultats de calculs elements finis par l'analyse auto-adaptative est, depuis quelques annees, un aspect tres important de la phase de conception d'un systeme mecanique. Apres examen de nombreux procedes d'estimation et d'amelioration de la fiabilite des calculs realises, cette etude se consacre aux possibilites offertes par l'optimisation de discretisations grace a la methode p. Pour la modelisation de structures mecaniques elasto-statiques, nous evoquons le concept d'elements finis dits p-hierarchises. A ce titre, dans un premier temps, la formulation et l'implantation d'un p-element quadrilateral de plaque et de coque sont discutees. Cet element tridimensionnel degenere a neuf nuds possede des fonctions d'interpolation (de type lagrange) dont les degres peuvent etre fixes de maniere adaptable dans son plan ainsi que dans sa direction transverse. Dans un second temps, nous proposons: d'une part, deux methodes d'estimation ou d'indication de l'erreur commise au niveau des elements d'un maillage prealablement defini. Ces methodes sont issues de l'analyse des residus des equations d'equilibre du probleme mecanique. D'autre part, des criteres d'adaptation bidirectionnelle optimisee des degres de polynomes des elements a modifier. Des exemples d'applications numeriques (y compris des exemples industriels) sont presentes dans le but d'eprouver l'element implante ainsi que l'algorithme d'analyse auto-adaptative mis en uvre
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Heck, Guilherme. "The impact of voltage scaling over delay elements with focus on post-silicon tests." Pontif?cia Universidade Cat?lica do Rio Grande do Sul, 2018. http://tede2.pucrs.br/tede2/handle/tede/8254.
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A demanda sem precedentes por poderosos dispositivos de processamento gerou quebras consecutivas de paradigma de projeto de circuito na ?rea de Circuitos Integrados (CIs). O uso de tecnologia submicrom?trica profunda aumenta a densidade de integra??o a n?veis nunca vistos antes. No entanto, com CIs mais densos, a inclina??o do rel?gio e outros efeitos requerem compensa??es em design s?ncrono, o que pode aumentar a ?rea e o consumo de energia a valores inaceit?veis. Como alternativa, o paradigma ass?ncrono est? re-emergindo, focado na efici?ncia de energia. Entre os modelos cl?ssicos de projeto ass?ncrono, o Empacotamento-de-Dados (ED) se destaca pela sua capacidade de fornecer alto desempenho, reduzir a pot?ncia e obter resultados de ?rea semelhante ? dos modelos s?ncronos. Diferentemente dos modelos mais robustos de quase-atraso insens?vel, uma outra classe comum de modelos para implementar circuitos ass?ncronos, circuitos ED requerem o uso extensivo de Elementos de Atraso (EAs) para garantir a correta funcionalidade. No entanto, todos os circuitos s?o afetados por varia??es de Processo, Tens?o e Temperatura (PTT), incluindo a L?gica Combinacional (LC) em ED impondo margem em elementos de atraso. Al?m disso, projetos atuais usam escalonamento de tens?o para melhorar a efici?ncia de energia, o que afeta o atraso diferentemente em LCs e EAs adicionando mais margem em EAs. Um novo modelo baseado em ED chamado Blade usa o conceito de resili?ncia como uma esperan?a para evitar a margem de atraso causada por PTT e escalonamento de tens?o. Contudo, o uso de dois elementos de atraso ir? representar mais margens e mais tempo de teste no circuito final. Assim, este trabalho mostra uma an?lise do comportamento de elementos de atraso sob escalonamento de tens?o e o impacto em testes p?s-sil?cio. Ele introduz um novo termo para determinar o impacto da escala de tens?o sobre os elementos de atraso e tamb?m a compara??o entre os EAs mais utilizados em projetos ED usando esta nova m?trica. Uma an?lise de testes em modelos ED e Blade ? apresentada e o impacto da escala de tens?o nestes projetos ? analisado. Finalmente, um novo elemento de atraso ? proposto focando na redu??o de margem e redu??o no tempo de teste para o modelo Blade.
The unprecedented demand for powerful processing devices has generated consecutive circuit design paradigm breaks in the Integrated Circuits (ICs) arena. The use of deep submicron technology increases the integration density to levels never seen before. However, with denser ICs, clock skew and other effects require compensations in synchronous design, which can increase area overhead and power consumption to unacceptable values. As an alternative, the asynchronous paradigm is re-emerging, focused on power efficiency. Among classical asynchronous design templates, the Bundled-Data (BD) one stands off for its capability to provide high performance, reduce power and achieve area results similar to that of synchronous designs. Unlike the more robust Quasi-Delay Insensitive (QDI) templates, another common class of templates to implement asynchronous circuits, BD circuits require the extensive use of Delay Elements (DEs) to guarantee correct functionality. However, all circuits are affected by Process, Voltage and Temperature (PVT) variations, including the Combinational Logic (CL) on BD imposing margin on delay elements. In addition, current designs use voltage scaling to improve power efficiency, which impacts the delay differently in CLs and DEs adding more margin in DEs. A new template based on BD called Blade uses resiliency concept as a hope to avoid the delay margin caused by PVT and voltage scaling. Although, the use of two delay elements will represents more margins and extra test time on final circuit. So, this work shows an analysis of delay elements behavior under voltage scaling and the impact on post-silicon tests. It introduces a new term to determine the voltage scaling impact on delay elements and also the comparison between the most used DEs on BD designs using this novel metric. An analysis of tests in BD and Blade templates are presented and the impact of voltage scaling in these designs is analyzed. Finally, a novel delay element is proposed focusing in margin reduction and reduction in test time for Blade template.
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Nicholas, Helen Ruth. "P element susceptibility in Drosophila melanogaster." Thesis, University of Nottingham, 2003. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.275318.
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Liu, Yunshan. "P-adaptive hybrid/mixed finite element method /." The Ohio State University, 1998. http://rave.ohiolink.edu/etdc/view?acc_num=osu1487950153602937.
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Zézé, Djédjé Sylvain. "Calcul de fonctions de forme de haut degré par une technique de perturbation." Thesis, Metz, 2009. http://www.theses.fr/2009METZ056S.
Повний текст джерелаАнотація:
La plupart des problèmes de la physique et de la mécanique conduisent à des équations aux dérivées partielles. Les nombreuses méthodes qui existent déjà sont de degré relativement bas. Dans cette thèse, nous proposons une méthode de très haut degré. Notre idée est d'augmenter l'ordre des fonctions d'interpolation via une technique de perturbation afin d'éviter ou de réduire les difficultés engendrées par les opérations très coûteuses comme les intégrations. En dimension 1, la technique proposée est proche de la P-version des éléments finis. Au niveau élémentaire, on approxime la solution par une série entière d'ordre p. Dans le cas d'une équation linéaire d'ordre 2, cette résolution locale permet de construire un élément de degré élevé, avec deux degrés de liberté par élément. Pour les problèmes nonlinéaires, une linéarisation du problème par la méthode de Newton s'impose. Des tests portant sur des équations linéaires et nonlinéaires ont permis de valider la méthode et de montrer que la technique a une convergence similaire à la p-version des éléments finis. En dimension 2, le problème se discrétise grâce à une réorganisation des polynômes en polynômes homogènes de degré k. Après une définition de variables dites principales et secondaires associé à un balayage vertical du domaine, le problème devient une suite de problème 1D. Une technique de collocation permet de prendre en compte les conditions aux limites et les conditions de raccord et de déterminer la solution du problème. La collocation couplée avec la technique des moindres carrés a permis de d'améliorer les premiers résultats et a ainsi rendu plus robuste la technique de perturbationMost problems of physics and mechanics lead to partial differential equations. The many methods that exist are relatively low degree. In this thesis, we propose a method of very high degree. Our idea is to increase the order of interpolation function via a perturbation technique to avoid or reduce the difficulties caused by the high cost operations such as integrations. In dimension 1, the proposed technique is close to the P-version finite elements. At a basic level, approximates the solution by a power series of order p. In the case of a linear equation of order 2, the local resolution can build an element of degree, with two degrees of freedom per element. For nonlinear problems, a linearization of the problem by Newton's method is needed. Tests involving linear and nonlinear equations were used to validate the method and show that the technique has a similar convergence in the p-version finite elements. In dimension 2, the problem is discretized through reorganizing polynomials in homogeneous polynomials of degree k. After a definition of variables called principal and secondary combined with a vertical scanning field, the problem becomes a series of 1D problem. A collocation technique allows to take into account the boundary conditions and coupling conditions and determine the solution of the problem. The collocation technique coupled with the least-squares enabled to improve the initial results and has made more robust the perturbation technique
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BONNIN, PATRICK. "Effets sur la croissance de bidens pilosa l. : 1) de quelques elements mineraux (p, zn, co, ni, cr) contenus dans les scories de dephosphoration. 2) d'un stimulus mecanique (etude des teneurs cellulaires en h#+ et k#+ et de l'activite atpasique du plasmalemme)." Clermont-Ferrand 2, 1993. http://www.theses.fr/1993CLF21568.
Повний текст джерелаАнотація:
La premiere partie de ce travail a consiste a etudier l'absorption de quelques elements mineraux contenus dans les scories de dephosphoration (p, zn, co, ni, cr) et leurs effets sur la croissance des plantules de bidens pilosa l. - l'absorption racinaire et le transfert de ces elements dans la plante sont regules par des mecanismes actifs dont la regulation est sous la dependance de la composition ionique du milieu de culture. - sur milieu liquide, la teneur en element (p, zn, co, ni, cr) dans les tissus augmente proportionnellement a la quantite apportee au milieu de culture. Dans le cas ou ces ions sont necessaires au developpement des plantes (p, zn), il existe une teneur seuil dans le milieu de culture et dans les tissus qui permet la croissance optimale. En deca et au-dela de ces teneurs, la croissance des plantes est diminuee. En revanche, dans le cas des metaux lourds, la croissance des plantes n'est jamais augmentee. - sur sol, les plantes n'absorbent pas les metaux lourds contenus dans les scories de dephosphoration. Alors que, s'ils sont sous forme de sel, on observe une augmentation de leur teneur dans les tissus et une modification de croissance, cependant, plus faibles que sur milieu liquide. Cette diminution est due au fait que les sols possedent un pouvoir adsorbant qui limite la solubilite des elements et donc leur assimilation par les plantes. Ce pouvoir adsorbant des sols est dependant de leur composition chimique. Les courbes de dilution obtenues sur milieu liquide, peuvent etre utilisees pour tester l'effet de la composition ionique des sols sur la croissance des plantes. La deuxieme partie de notre travail a consiste a etudier, chez bidens pilosa, quels evenements ioniques et biochimiques intervenaient dans l'inhibition de croissance de l'hypocotyle induite par des traumatismes cotyledonaires. Ils induisent rapidement un blocage de l'activite des atpases du plasmalemme qui entraine une chute de la teneur cytoplasmique en protons et en potassium. Ces modifications ioniques bloquent le cycle et l'elongation cellulaire et conduisent a l'inhibition de croissance. Cette reponse est dependante de la composition ionique du milieu de culture
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She, Jairus Lai Yan. "Prediction of P-Y curves from finite element analyses." Thesis, University of British Columbia, 1986. http://hdl.handle.net/2429/26736.
Повний текст джерелаАнотація:
The prediction of P-Y curves for undrained clay and sand based on the results of finite element analyses is presented in this thesis.
A higher-ordered finite element program was used in the analyses. The ability of the program to accurately model the undrained soil condition was verified by comparing predicted load-deflection responses with closed form solutions for the cylindrical cavity expansion problem.
Pressuremeter curves were predicted from plane strain axisymmetric finite element analyses. The effect of pressuremeter size on the predicted results was examined.
P-Y curves were predicted for plane strain and plane stress conditions. Values for the initial slope and Pun- of the curves were obtained. The curves were normalized for comparison, and simplified methods presented for determining P-Y curves.
Finite element predictions for the pressuremeter and laterally loaded pile problems were also compared. Factors were determined from these comparisons to generate P-Y curves from pressuremeter curves.Applied Science, Faculty of
Civil Engineering, Department of
Graduate
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French, David John. "The evolution of P element repression in Drosophila melanogaster." Thesis, University of Leicester, 1999. http://hdl.handle.net/2381/30316.
Повний текст джерелаАнотація:
P elements have invaded and spread through populations of Drosophila melanogaster in the last sixty years, despite the induction of a severe set of genetic abnormalities known as hybrid dysgenesis (HD). P element spread has occurred because of the co-evolution of several systems that repress P element transposition and HD. Such repression systems, singly or in combination, give rise to populations phenotypically defined as P, M' and Q, with Q further subdivided in Qmat (strong repression transmitted maternally only) and Qbip (strong repression transmitted biparentally). What are the evolutionary dynamics of these repression systems? Do they co-exist or will all populations subsequently gravitate towards one stable system? Qbip populations possess all of the fitness benefits of P, M' and Qmat strains, but have none of their apparent disadvantages. A type I deletion element, called SR, has been isolated from a Qbip strain and its presence has been demonstrated to correlate with strong repression. My thesis tests a working model that the Qbip phenotype, mediated by SR or 'SR-like' elements, is the evolutionary stable state for repression. A D. melanogaster strain devoid of P elements was transformed with SR. Gonadal dysgenesis assays failed to detect strong repression, but the more sensitive A4-4 eye-colour assay failed to detected intermediate strength repression that may be dependent on genomic position. Molecular analysis of naturally occurring Q stains revealed the existence of putative 'SR-like' elements which fulfil the structural requirements of strong repressors. Molecular and phenotypic analysis of flies from a cline on the east coast of Australia, which ten years ago had P populations in the north, Q at central sites and M' in the south, shows that Q and M' flies have increased their range at the expense of P lines. Competition cage experiments which comprise mixtures of repression systems indicate potential trends towards Qbip. The data support the proposition that Qbip is the evolutionary end state for repression in D. melanogaster.
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Good, Allen G. "The population genetics of the P element of Drosophila melanogaster." Thesis, University of Ottawa (Canada), 1986. http://hdl.handle.net/10393/5012.
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Heisserer, Ulrich. "High order finite elements for material and geometric nonlinear finite strain problems." Aachen Shaker, 2008. http://d-nb.info/991820061/04.
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Jackson, Michael Stewart. "KP element regulation of P-M hybrid dysgenesis in Drosophila melanogaster." Thesis, University of Cambridge, 1988. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.279913.
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Badge, Richard Morley. "Mobility and repression of the P transposable element in Drosophila melanogaster." Thesis, University of Nottingham, 1996. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.320789.
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Sommer, Karen Marie. "Identification and characterization of elements regulating the expression of the phenobarbital-inducible CYP2B1 and CYP2B2 genes /." Thesis, Connect to this title online; UW restricted, 1996. http://hdl.handle.net/1773/8477.
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Oliveira, Wlamir Carlos de. "Um elemento finito hierarquico para analise dinamica P-adaptativa de placas espessas." [s.n.], 1993. http://repositorio.unicamp.br/jspui/handle/REPOSIP/263029.
Повний текст джерелаАнотація:
Orientador: Fernando IgutiTese (doutorado) - Universidade Estadual de Campinas, Faculdade de Engenharia Mecanica
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Resumo: Este trabalho tem por objetivo apresentar um processo adaptativo de refinamento hierárquico, baseado na formulação paramétrica, versão p, do Método dos Elementos Finitos. O processo é aplicado na resolução do problema dinâmico de autovalor generalizado de placas espessas na elasticidade linear. O primeiro nível de aproximação da solução e obtido através do elemento isoparamétrico 3D de dezesseis nós, proposto neste trabalho, utilizando-se funções de interpolação do tipo standard da família Serendipity. Para outros níveis de aproximação, são realizados sucessivos refinamentos hierárquicos, conforme as informações adquiridas na análise de erros a-posteriori. A distribuição seletiva de novos graus de liberdade, nos elementos mais carentes de refinamento, se processa em função da utilização de um indicador de erro. Para avaliar o erro global de uma solução, considera-se um estimador de erro, o qual serve também como critério principal de parada do processo de refinamento hierárquico. É mostrado que a implementação do elemento 3D no processo p-adaptativo adotado produz soluções com altas taxas de convergência. Os resultados numéricos obtidos nos exemplos de aplicação são comparados com soluções analíticas e por outras técnicas numéricas
Abstract: The purpose of this research is to present an adaptive process of hierarchical refinement, based on the p-version parametric formulation from the Finite Element Method. The process is applied on the resolution of generalized dynamic eigenvalue problem of thick plates in the linear elasticity mode. The first leveI of approximation of the solution is obtained through the isoparametric 3D element of sixteen nodes, proposed in this work, using functions of interpolation from the standard type derived from the Serendipity family. For other approximation levels, successive hierarchical refinements are used, according to the information acquired from the a-posteriori error analysis. The selective distribution of new degrees of freedom in the elements in need of refinement is processed according to the utilization of an error indicator. To evaluate the global error of a solution, an error estimator is considered and it also works as a main criterion for the stopping of the process of hierarchical refinement. It is showed that the implementation of the 3D element in the adopted p-adaptive process produces solutions with high rate of convergence. The numerical results obtained in the application examples are compared with analytical solutions and other numerical techniques
Doutorado
Mecanica dos Solidos
Doutor em Engenharia Mecânica
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Ayala, Bravo Cedric Marcelo Augusto. "Um sistema de refinamento H-P adaptativo utilizando elementos finitos hierarquicos multidimensionais." [s.n.], 2000. http://repositorio.unicamp.br/jspui/handle/REPOSIP/265121.
Повний текст джерелаАнотація:
Orientadores : Philippe Remy Bernard Devloo, Renato PavanelloTese (doutorado) - Universidade Estadual de Campinas, Faculdade de Engenharia Mecanica
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Resumo: Descrevem-se de uma maneira formal os conceitos matemáticos que permitem implementar um refmamento multidimensional h-p adaptativo para o método dos elementos finitos. Os conceitos são implementados em código orientado para objetos num ambiente de programação de elementos finiitos denominado PZ. O conceito de transformação geométrica define o mapeamento entre um elemento de referência uni, bi ou tridimensional e o elemento deformado em ~. Estende-se o conceito de "lado" de um elemento fmito representando canto, aresta, face ou volume. Associa-se funções de fonna hierárquicas a lados de um elemento e para uma malha refmada, defme-se uma dependência entre as bases associadas a lados adjacentes de níveis distintos. Descreve-se detalhadamente a defmição dos elementos hierárquicos e a construção das suas funções de forma. Demonstra-se que os elementos assim defmidos possuem a ordem p completa para o espaço de interpolação associado, independente da ordem p escolhida. Através da introdução dos "parâmetros variacionais" e das restrições entre funções de forma associadas a lados de elementos, consegue-se combinar de forma adaptativa qualquer um destes elementos. Mostra-se de forma teórica e prática que uma combinação adaptativa de elementos, ainda que de distintas dimensões, implica na obtenção de um espaço de elementos fmitos de funções contínuas. Relacionam-se os testes de qualificação para as ferramentas desenvolvidas
Abstract: A formal description of the multidimensional hp adaptive refmement process is developed. The concepts are implemented within the PZ object oriented environment for finite element programming. The concept of the geometric transformation defmes the mapping between a one-, two- or three dimensional master element and its defonned configuration in ~. The concept of a side is extended to inc1ude comers, tines, faces and volumes. Hierarchical shape functions are associated with sides and for adaptively refmed meshes, the concept of restrained shape functions is introduced. A detailed description of the construction process is given for the complete family of fmite elemento It is shown for each element that the space of interpolation for arbitrary order p is complete. U sing variational parameters associated with the sides of the elements and the restraints between shape functions of adaptive fmite element meshes, it is possible to use hp adaptivity on heterogeneous meshes. It is shown that shape functions of elements of different dimensions maintain continuity at their interfaces. Qualification tests and numerical examples are inc1uded to demonstrate the correctness of the approach
Doutorado
Mecanica dos Sólidos e Projeto Mecanico
Doutor em Engenharia Mecânica