Ba0.5Sr0.5Co0.8Fe0.2O3-delta (BSCF) and SrCo0.48Fe0.12Ti0.4O3-delta (SCFT) were synthesised by co-precipitation. BSCF was pressed and sintered at 1100℃ for 10 hours to pellets (relative density: 93%) from which X-ray diffraction (XRD) revealed single Pm-3m phase (a=3.9782 A). Scanning electron microscopy (SEM) revealed clear equiaxed grains (grain size 33 ± 16 micro metre). The pellets were decomposed in 7 ± 1 % CO2/N2 at 800℃ for 1 to 30 minutes. XRD confirmed secondary phases: R-3mH phase (a=b=5.1397 A, c=9.4847 A) and Fm-3m phase (a=4.2490 A). Electron backscattered diffraction (EBSD) ascribed R-3mH and Fm-3m phases to the surface and part of the cross-section precipitates, respectively as revealed by SEM. Energy dispersive X-ray spectroscopy (EDX) revealed the compositions of R-3mH and Fm-3m phases to be Ba0.65±0.03Sr0.35±0.03CO3 (BSC) and CoO, respectively. Transmission electron microscopy (TEM) and EDX revealed the structure (15R, R3m and R-3mH) and composition (Ba0.20Sr0.10Co0.59Fe0.10Ox) of lamellar precipitates in cross-section, suggesting Ba and Sr diffuse from the lamellae to BSC. A unique orientation relation (BSCF {111} // BSC {0001}) was uncovered by EBSD. TEM revealed high symmetry contact planes of lamellae and BSCF, suggesting nucleation energy governs decomposition. Fresh BSCF pellets were decomposed in N2 at 800℃. Fm-3m and P63/mmc phases were confirmed by XRD and lamellae were observed by SEM, followed by decomposition in 7±1 % N2/CO2 at 800℃. XRD revealed higher weight % of BSC and CoO. SEM revealed BSC preferring lamellae, hence hexagonal phases accelerated BSC formation. BSCF pellets were dip coated in SCFT propan-2-ol suspension (3:10), followed by sintering at 1165℃ for 10 hours. XRD revealed a Pm-3m phase (a=3.885 A) and SEM revealed a grain size of 65 ± 9 micro metre and open porosity of 1.6 ± 1 %. They were annealed in 7 ± 1 % CO2/N2 at 800℃. XRD revealed no secondary phases, suggesting enhanced stability. However, oxygen permeability was reduced (1.2 ml/cm2 to 0.8 ml/cm2) because the coating composition changed to Ba0.20Sr0.27Co0.40Fe0.10Ti0.04Ox; this was revealed by EDX.

In the second part, we further investigate algebraic structure of relational databases. The decomposition theory for relational databases is based on data dependencies. Nevertheless, the set-theoretic representations of data dependencies in terms of the attributes of relation schemes are incompatible with partial ordering operations. This brings a gap between the database decomposition theory and our theory. We identify the unique component constraint as a necessary condition for binary decomposition of a relation, i.e. there is a unique component for every join key value in the bipartite graph. We generalize the running intersection property as the partial ordering counterpart under the unique component constraint. It follows that we characterize the multivalued and acyclic join dependencies in terms of commutativity and unique component constraint. This shows the decompositions specified by these dependencies are special cases of our theory. Furthermore, we propose a lossless decomposition method for the class of data dependencies that is based on commutativity, and demonstrate that existing relational operations are sufficient for this method. / Relational information systems, systems that can be represented by tables of finite states, are widely used in many areas such as logic circuits, finite state machines, and relational databases. Decomposition is a natural method to remove redundancy of complex systems. It divides a system into a network of simpler components. In order to preserve the original functionalities of the system, any valid decomposition has to be lossless. This work is divided into two parts. In the first part, we develop a mathematical model for lossless decompositions of relational information systems. Commutative partitions play an important role in decompositions. The commutativity is essentially a general algebraic formulation of independency of two partitions. We express the interdependency of two commutative partitions by a bipartite graph, and classify the hierarchical independency structures by the topological property of bipartite graphs. In particular, we show that two partitions are decomposable, the strongest kind of independency, if and only if the associated bipartite graph is uniform. Moreover, we adopt Shannon's entropy to quantify the amount of information contained in each partition, and formulate information-lossless decompositions by entropy equalities. Under the assumption of running intersection property, we show that the general formulation of information-lossless decompositions of relational information systems is given by the entropy inclusion-exclusion equality. We also present the applications of these formulations to the above engineering systems to manifest the information-lossless decomposition processes. / Lo, Ying Hang. / Adviser: Tony T. Lee. / Source: Dissertation Abstracts International, Volume: 70-06, Section: B, page: 3606. / Thesis (Ph.D.)--Chinese University of Hong Kong, 2008. / Includes bibliographical references (leaves 159-163). / Electronic reproduction. Hong Kong : Chinese University of Hong Kong, [2012] System requirements: Adobe Acrobat Reader. Available via World Wide Web. / Electronic reproduction. [Ann Arbor, MI] : ProQuest Information and Learning, [200-] System requirements: Adobe Acrobat Reader. Available via World Wide Web. / Abstracts in English and Chinese. / School code: 1307.

CoordenaÃÃo de AperfeiÃoamento de Pessoal de NÃvel Superior / A pesquisa foi realizada com o objetivo de avaliar a decomposiÃÃo da folhagem de marmeleiro (Croton sonderianus), em funÃÃo da forma de acondicionamento e disposiÃÃo do material no solo na estaÃÃo seca e na estaÃÃo chuvosa. O experimento foi conduzido na Fazenda Experimental Vale do AcaraÃ, onde foram selecionadas duas Ãreas com 1 ha cada. Uma Ãrea apresentava a vegetaÃÃo preservada e a outra Ãrea sofreu aÃÃes antropogÃnicas. Foram acondicionados 30 g de folhagem de marmeleiro em 72 sacolas de decomposiÃÃo (que foram confeccionadas com malha telada de n 0 com 30 cm x 30 cm) as quais foram divididas em 3 tratamentos: sacolas com ambas as faces livres (A); sacolas com a face superior protegida por um plÃstico transparente (B), sacolas com a face superior protegida por lona branca (C). O delineamento experimental foi inteiramente casualizado em um arranjo fatorial de 3 x 2 x 2 x 2, sendo 3 tipos de sacolas x 2 Ãreas x 2 posiÃÃes x 2 estaÃÃes, com trÃs repetiÃÃes. Foi mensurada a temperatura ambiental, mÃxima e mÃnima, a temperatura do solo, assim como a umidade presente no mesmo, e a radiaÃÃo solar. As taxas de decomposiÃÃo real foram obtidas atravÃs de equaÃÃo, em que houve a subtraÃÃo da porcentagem inicial de biomassa vegetal pela quantidade restante nas sacolas ao fim de cada estaÃÃo. A forma de acondicionamento do material, as posiÃÃes em que os mesmos estavam assim como a influÃncia das estaÃÃes do ano e seus fatores abiÃticos caracterÃsticos, influenciaram na taxa de decomposiÃÃo da folhagem de marmeleiro, sendo que ocorrem maiores taxas de decomposiÃÃo na Ãrea preservada durante o perÃodo chuvoso. / The research was conducted to evaluate the decomposition of leaves of marmeleiro (Croton sonderianus), depending on the shape and arrangement of the packing material in the soil in the dry and rainy seasons. The experiment was conducted at the Fazenda Experimental Vale do AcaraÃ, where two areas were selected with 1 ha each. One area showed the preserved vegetation and other anthropogenic area suffered. Were placed 30 g of leaves of marmeleiro in 72 bags of decomposition (which were made with mesh screened from No. 0 to 30 cm x 30 cm) which were divided into three treatments: bags with both free surfaces (A); bags with the top surface protected by a transparent plastic (B), bags with the top surface protected by white canvas (C). The experimental design was completely randomized in a factorial arrangement of 3 x 2 x 2 x 2, and 3 types of bags x 2 x 2 locations x 2 seasons, with three replications. Was measured at ambient temperature, maximum and minimum soil temperature and the moisture present in it, and solar radiation. Decomposition rates were obtained by real equation, in which there was the subtraction of the initial percentage of plant biomass by the amount remaining in the bags at the end of each season. The form of packaging material, the positions in which they were as well the influence of the seasons and their abiotic characteristics, influence the rate of decomposition of leaves of marmeleiro, with higher rates of degradation occur in the preserved during the rainy season.

O desenvolvimento de aplicações de forma a atingir níveis de desempenho próximos aos níveis teóricos de uma determinada plataforma é uma tarefa que exige conhecimento técnico do ambiente de hardware, uma vez que o software deve explorar detalhes específicos da plataforma em questão. Pelo fato do software ser específico à plataforma, caso ela evolua ou se altere, as otimizações realizadas podem não explorar a nova arquitetura de forma eficiente. Auto-tuners são sistemas que surgiram como um meio automatizado de adaptar um determinado software a uma arquitetura alvo. Essa adaptação ocorre através de uma busca empírica de valores ótimos para parâmetros específicos de uma aplicação, a fim de ajustá-los às características do hardware, ou ainda através da geração de códigofonte otimizado para a plataforma. Este trabalho propõe um módulo auto-tuner orientado à adaptação parametrizada de uma aplicação paralela, que trabalha variando os fatores da dimensão do domínio bidimensional, o número de processos e a extensão das regiões de sobreposição. Para cada variação dos fatores, o auto-tuner testa a aplicação na arquitetura paralela de forma a buscar a combinação de parâmetros com melhor desempenho. Para possibilitar o auto-tuning, foi desenvolvida uma classe em linguagem C++ denominada Mesh, baseada no padrão MPI. A classe busca abstrair a decomposição de domínios de uma aplicação paralela por meio do uso de Orientação a Objetos, e facilita a variação da extensão das regiões de sobreposição entre os subdomínios. Os resultados experimentais demonstraram que o auto-tuner explora o ganho de desempenho pela variação do número de processos da aplicação, que também é tratado pelo módulo auto-tuner. A arquitetura paralela utilizada na validação não se mostrou ideal para uma otimização através do aumento da extensão das regiões sobrepostas entre subdomínios. / Achieving the peak performance level of a particular platform requires technical knowledge of the hardware environment involved, since the software must explore specific details inherent to the hardware. Once the software is optimized for a target platform, if the hardware evolves or is changed, the software probably would not be as efficient in the new environment. This performance portability problem is addressed by software auto-tuning, which emerged in the past decade as an automated technique to adapt a particular software to an underlying hardware. The software adaptation is performed by an auto-tuner. The auto-tuner is an entity that empirically adjusts specific application parameters in order to improve the overall application performance, or even generates source-code optimized for the target platform. This dissertation proposes an auto-tuner to optimize the domain decomposition of a parallel application that performs stencil computations. The proposed auto-tuner works in a parameterized adaptation fashion, and varies the dimensions of a 2D domain, the number of parallel processes and the extension of the overlapping zones between subdomains. For each combination of parameter values, the auto-tuner probes the application in the parallel architecture in order to seek the best combination of values. In order to make auto-tuning possible, it is proposed a C++ class called Mesh, based on the Message Passing Interface (MPI) standard. The role of this class is to abstract the domain decomposition from the application using the Object Orientation facilities provided by C++, and also to enable the extension of the overlapping zones between subdomain. The experimental results showed that the performance gains were mainly due to the variation of the number of processes, which was one of the application factors dealt by the auto-tuner. The parallel architecture used in the experiments showed itself as not adequate for optimizing the domain decomposition by increasing the overlapping zones extension.

A matroid M is a finite set E, called the ground set of M, together with a notion of what it means for subsets of E to be independent. Some matroids, called regular matroids, have the property that all elements in their ground set can be represented by vectors over any field. A matroid is called round if its dual has no two disjoint minimal dependent sets. Roundness is an important property that was very useful in the recent proof of Rota's conjecture, which remained an unsolved problem for 40 years in matroid theory. In this thesis, we give a characterization of regular round matroids.

Coastal marine sediments have recently been identified as globally important stocks of organic carbon (Corg) that, if compromised, could significantly exacerbate global greenhouse gas emissions. While resource managers and policy makers are eager to incorporate this ecosystem service into seagrass ecosystem valuation frameworks, similar to those already in existence for terrestrial forests, there has been insufficient information regarding how environmental conditions and seagrass ecology control carbon storage. These include the influence of the seagrass to the production and preservation of soil organic matter, the fate of stored carbon following conversion of coastal wetlands, and the interactions between organic and inorganic carbon cycling. This dissertation intends to to understand the drivers of Corg storage and preservation to better prioritize and evaluate the worth of seagrasses to large scale carbon cycles and greenhouse gas mitigation planning. Long-term experiments and thorough field surveys reveal that seagrasses are not categorically necessary nor sufficient for long-term Corg storage. Soil Corg stocks as well as their recalcitrance and breakdown rates are all correlated with sediment grain size, where muddy, fine sediments have higher Corg stocks that are less likely to breakdown. Sediment grain size can be influenced by the presence of seagrasses at some sites, likely where the leaf canopy can modify local hydrology enough to create a depositional environmental that wouldn’t otherwise exist. However, similar depositional environments that collect and store Corg can be obtained through local geomorphological features and natural hydrology, independent of benthic flora. This distinction has important implications on how soil C is managed to continue its preservation. The relation between seagrass Corg and CO2 can be blurred by calcification and carbonate dissolution processes that occur concurrently, and have direct but antagonistic effects on CO2. Carbonate processes are dependent on local environmental factors, though augmented by biological processes, thus the ability of carbonate processes to interfere with seagrass Corg storage and loss is limited to geographic areas where processes can occur. Warm, shallow waters, like those in Florida Bay, encourage calcification, though the magnitude of soil inorganic and organic carbon interaction can vary locally as well. Seagrasses are declining globally thus additional ecosystem value via greenhouse gas mitigation could greatly benefit conservation efforts. To make conservation efforts worthwhile to greenhouse gas mitigation, these findings help to consider and prioritize sites where risk and impact of Corg lost is more severe.

Curiosity is the cause of investigations, and the thirst for knowledge originates from it. Many times at the end of investigations, the number of questions raised are greater than those for which answers are sought. Therefore, all the information gathered through scientific investigations may not be of value for immediate application in practical life. Nevertheless, no research can be considered less important than the other because the integration of several scientific findings considered less less important at the time of investigation may reveal something of very high significance. Similarly, the study of various transformation reactions that the added fertilizers undergo may not be of value to the one whose main objective is to increase production, though it is of great value for the efficient use of fertilizers. Information on the reactions of each intermediate compound produced during the transformations of ammoniacal fertilizers may be useful in reducing or preventing the loss of N that could arise through some of the reactions. Such knowledge will be useful for the economical use of fertilizers. Nitrite is an intermediate compound produced in nitrification, denitrification, and nitrite reduction processes. Chemistry of nitrite in alkaline solutions is well understood, while its fate in acid soils and solutions has eluded the attention of most workers. This is probably due to the fact that under acid conditions nitrite does not appear in large quantities contrary to its behavior in the alkaline region. However, the existence of nitrite in smaller concentrations under acid conditions suggests the possibility that it may be rapidly transformed to other forms of N and may lead to the loss of added N. The rates of such reactions and losses may be higher in acid than in alkaline soils. In acid solutions nitrite also exists as un-ionized nitrous acid; the concentration of the latter form increases at higher acidities. In the following pages these two terms, nitrite and nitrous acid, will be used interchangeably. In acid soils, nitrous acid undergoes several changes such as its fixation by various soil components, chemical conversion to other N compounds, and loss of N either as N2 or in the form of oxides of nitrogen. Most of these reactions may probably result in reduced nitrogen availability to the crops. In this investigation some of the factors influencing nitrite transformations, such as non-biological nitrification and loss of N in different forms, were studied. Validity of some of the proposed nitrite decomposition pathways were verified, and conditions favoring individual reactions were studied in various soil and resin systems.

Engineering activities by nature are collaborative endeavors. Single-user applications like CAD, CAE, and CAM force a strictly serial design process, which ultimately lengthens time to market. New multi-user applications such as NXConnect address the issue during the design stage of the product development process by enabling users to work in parallel. Multi-user collaborative tool path planning software addresses the same serial limitations in tool path planning, thereby decreasing cost and increasing the quality of manufacturing processes. As part complexity increases, lead times are magnified by serial workflows. Multi-user tool path planning can shorten the process planning time. But, to be effective, it must be possible to intelligently decompose the manufacturing sequence and distribute path planning assignments among several users. A new method of process decomposition is developed and described in this research. A multi-user CAM (MUCAM) prototype was developed to test the method. The decomposition process and MUCAM prototype together were used to manufacture a part to verify the method.

A transitive decomposition of a graph is a partition of the arc set such that there exists a group of automorphisms of the graph which preserves and acts transitively on the partition. This turns out to be a very broad idea, with several striking connections with other areas of mathematics. In this thesis we first develop some general theory of transitive decompositions, and in particular we illustrate some of the more interesting connections with certain combinatorial and geometric structures. We then give complete, or nearly complete, structural characterisations of certain classes of transitive decompositions preserved by a group with a rank 3 action on vertices (such a group has exactly two orbits on ordered pairs of distinct vertices). The main classes of rank 3 groups we study (namely those which are imprimitive, or primitive of grid type) are derived in some way from 2-transitive groups (that is, groups which are transitive on ordered pairs of distinct vertices), and the results we achieve make use of the classification by Sibley in 2004 of transitive decompositions preserved by a 2-transitive group.

Thesis (Ph.D.)--University of Delaware, 2007. / Principal faculty advisor: Babatunde Ogunnaike, Dept. of Chemical Engineering, and Robert W. Birkmire, Dept. of Materials Science & Engineering. Includes bibliographical references.