Ongoing investigation of peccary remains from fossiliferous deposits in the Yucatán resulted in re-examination of previously identified tayassuid fossils from the region. This included the recently described new genus and species of peccary, Muknalia minima, which is based on a dentary from Muknal Cave near Tulum, Quintana Roo, Mexico. Diagnostic characters of this taxon include a concave notch along the caudal edge of the ascending ramus and a ventrally directed angular process. Our assessment of the holotype indicates that these characteristics are not a reflection of the original morphology, but are instead the result of breakage and polishing of the posterior aspect of the dentary. Measurements and intact morphological features indicate the Muknal Cave specimen belongs to the extant collared peccary, Pecari tajacu.

An investigation was carried out on the current state of the art in bubble modelling for computational fluid dynamics, and comparisons made between the different methods for both polydisperse and monodisperse multiphase flows. A multigroup method for polydisperse bubbly flows with the bubbles binned in terms of mass was selected from the various alternatives, which included other multigroup models and moment methods. The latter of these involve the integration of moments of the bubble number density function and transport of these quantities. The equations from this multigroup solver were then changed to more accurately and efficiently model cases involving extremely small bubbles over significant amounts of time, as the original model which was subsequently adapted had, as its primary purpose, simulation of larger bubbles over shorter periods of time. This was done by decoupling the gas and liquid momentum equations and adding an empirical rise velocity term for the bubbles. This new model was then partially implemented into OpenFOAM. The functioning of this new solver was confirmed by comparisons between the results and basic analytical solutions to the problems, as well as by means of comparison with another similar multiphase CFD solver (pbeTransportFoam). Following this confirmation of its functionality, the bubble model was implemented into another solver specifically designed for modelling wakes. Finally, the newly created solver was used to run some cases of interest involving a submerged wake. / Master of Science / Bubbles in the ocean are significant for a number of reasons, ranging from mixing of the upper layer of the ocean to scavenging of biological matter, by which means they can also impact the state of the ocean's surface where they are present. They serve as an important mechanism by which air is dissolved in the ocean, and their breaking at the surface can cause particles or droplets to be ejected into the atmosphere. They can be created by a variety of sources, ranging from the movement of ship propellers and hulls to natural processes, both abiotic and from microorganisms or other living things. They can have exceedingly variable sizes, meaning bubbles behave very differently from one another in the same area. For these reasons, their study is both interesting and sometimes challenging. In this research, methods were developed to simulate the movement over a significant amount of time of a wide size variety of very small bubbles within the ocean. First, study was undertaken of preexisting methods of bubble simulation and the different cases they were intended to represent. One of these existing methods was selected for use and then changed to more accurately represent smaller bubbles, as well as including simplifications to allow the simulations to run faster. Lastly, these methods were implemented into OpenFOAM, an open-source set of solvers for computational fluid dynamics (CFD). These new methods for simulation were finally applied to some cases involving submerged bubbles in the ocean and the movement of bubbles in these cases studied.

No / Abstract: This paper focuses on the submerged landscapes of the southern North Sea, an area often referred to as Doggerland, which was inundated as a result of relative sea-level rise at the start of the Holocene. The timing, pattern and process of environmental changes and the implica­ tions for prehistoric (Mesolithic) human communities living in this area have long been a subject of debate and discussion. Recent developments in marine geophysics have pemtitted the mapping of the pre-submergence landscape, leading to the identification oflandforms including river channels and other contexts suitable for the preservation of palaeoecological records. The paper describes multi-proxy (pollen, foraminifera, plant macrofossil and insect) palaeoenvironmental analyses of a vibrocore sequence recovered from a palaeochannel feature c. 80 km off the coast of eastern England. The palaeocbsnnel preserves sediments of Late Pleistocene and Holocene age (MIS2/l); the record suggests that channel incision, probably duting the early Holocene, was followed by a phase of peat formation (c. 9-10 cal ka BP) indicating paludification and the subsequent reactiva­ tion of the cbsnnel (c. 9-6 cal ka BP), initially under freshwater and increasingly brackish/saline conditions, and a final transition to full marine conditions (6-5 cal ka BP). The pollen, macrofossil and beetle records indicate the presence of pre-submergence deciduous woodland, but detailed interpretation of the data is hindered by taphonomic complications.The paper concludes with a dis­ cussion of the problems and potentials of using palaeoenvironmental data to reconstruct complex patterns of environmental change across Doggerland in four dimensions, and considers specific questions concerning the implications of such processes for Mesolithic human communities.

No / The submerged landscape of the North Sea has long been known by archaeologists as an area of Mesolithic occupation, yet despite this the nature of the occupation of this landscape has remained poorly understood due to the submergence of the landscape. This paper presents the results of a “first pass" study to produce an initial model of the carrying capacity of the landscape and its associated demography. This model seeks to explore the impacts of sea level driven landscape change upon the Mesolithic population. The model reveals the diversity of resources present in this landscape and the potential these had to buffer human subsistence from the effects of marine inundation.

Orientador: Nilton Nobuhiro Imai / Banca: Maria de Lourdes Bueno Trindade Galo / Banca: Júlia Celia Mercedes Strauch / Resumo: Este trabalho relata um estudo de caso, no qual se procedeu a um levantamento ecobatimétrico para se obter dados de profundidade do corpo de água e da altura da vegetação aquática submersa, realizado num trecho do Rio Uberaba, que faz parte do Reservatório de Porto Colômbia, abrangendo uma área de aproximadamente 360 mil m². Os dados foram processados e avaliados com o objetivo principal de desenvolver uma abordagem de inferência espacial no mapeamento de macrófitas submersas presentes na região pesquisada. Para isso, verificou-se a viabilidade do uso de interpoladores convencionais para mapear as variáveis coletadas pelo ecobatímetro, avaliou-se o potencial de imagem multiespectral de alta resolução espacial (QuickBird) na detecção da vegetação estudada, realizou-se uma análise espacial para avaliar tendência para esse tipo de ocorrência e, finalmente, estudou-se a possibilidade de se utilizar técnica de geoestatística na inferência da altura de macrófitas submersas da área de estudo. As interpolações convencionais não se mostraram satisfatoriamente adequadas para mapear a variável altura da vegetação submersa, porém, a utilização da interpolação linear por triangulação foi suficiente para representar adequadamente o relevo submerso. A imagem multiespectral se mostrou capaz de detectar aproximadamente 21% de macrófitas submersas. Com relação à análise espacial, os resultados indicaram que a dependência espacial é uma tendência que deve ser levada em consideração, daí ter sido utilizada a geoestatística na abordagem de inferência espacial da vegetação. A análise dos semivariogramas forneceu conhecimento relacionado aos métodos de levantamentos ecobatimétricos. A inferência espacial por krigagem apresentou resultado satisfatório, comparado às interpolações convencionais mencionadas anteriormente... (Resumo completo, clicar acesso eletrônico abaixo) / Abstract: In this work was accomplished a case study in which an echo sounder survey was conducted to obtain data of water body depth and submerged aquatic vegetation height. The study was realized specifically on a region of Uberaba River with approximately 360.000 m². This river is part of the Porto Colombia reservoir. The data was processed and evaluated with main objective to develop an approach of spatial inference for map submersed macrophyte in the region studied. For this, it was verified the availability of using conventional interpolation to map the variables collected by the echo sounder, it was evaluated the potential of multispectral image with high spatial resolution (QuickBird) to detect the vegetation, it was done a spatial analysis and finally it was verified the possibility of using geostatistic technique to infer the submerged macrophytes height in the study area. The use of linear interpolation by triangulation was enough to represent rightly the underwater topography; however, the conventional interpolations were not satisfactorily to map the submerged vegetation height. The multispectral image was able to detect approximately 21% of submerged macrophytes. About spatial analysis, the results indicated that the spatial dependence must be considered, therefore, it was used the geostatistic in the spatial inference of submerged vegetation. Semivariograms analysis provided important knowledge about methods of echo sounder survey. The spatial inference by kriging showed satisfactory results if compared with conventional interpolations mentioned above. Finally, the approach used to mapping submerged macrophytes height can be applied in other regions and this can help the reservoirs management, allowing improve the knowledge about the local ecosystem and therewith developing an action strategy to contain the spread of submerged aquatic vegetation / Mestre

Made available in DSpace on 2014-06-11T19:22:25Z (GMT). No. of bitstreams: 0 Previous issue date: 2001-02-25Bitstream added on 2014-06-13T20:48:52Z : No. of bitstreams: 1 rotta_lhs_me_prud.pdf: 9845813 bytes, checksum: 8afe01cd2ab27aa9636ee65187b34e5d (MD5) / Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq) / Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES) / Este trabalho relata um estudo de caso, no qual se procedeu a um levantamento ecobatimétrico para se obter dados de profundidade do corpo de água e da altura da vegetação aquática submersa, realizado num trecho do Rio Uberaba, que faz parte do Reservatório de Porto Colômbia, abrangendo uma área de aproximadamente 360 mil m². Os dados foram processados e avaliados com o objetivo principal de desenvolver uma abordagem de inferência espacial no mapeamento de macrófitas submersas presentes na região pesquisada. Para isso, verificou-se a viabilidade do uso de interpoladores convencionais para mapear as variáveis coletadas pelo ecobatímetro, avaliou-se o potencial de imagem multiespectral de alta resolução espacial (QuickBird) na detecção da vegetação estudada, realizou-se uma análise espacial para avaliar tendência para esse tipo de ocorrência e, finalmente, estudou-se a possibilidade de se utilizar técnica de geoestatística na inferência da altura de macrófitas submersas da área de estudo. As interpolações convencionais não se mostraram satisfatoriamente adequadas para mapear a variável altura da vegetação submersa, porém, a utilização da interpolação linear por triangulação foi suficiente para representar adequadamente o relevo submerso. A imagem multiespectral se mostrou capaz de detectar aproximadamente 21% de macrófitas submersas. Com relação à análise espacial, os resultados indicaram que a dependência espacial é uma tendência que deve ser levada em consideração, daí ter sido utilizada a geoestatística na abordagem de inferência espacial da vegetação. A análise dos semivariogramas forneceu conhecimento relacionado aos métodos de levantamentos ecobatimétricos. A inferência espacial por krigagem apresentou resultado satisfatório, comparado às interpolações convencionais mencionadas anteriormente... / In this work was accomplished a case study in which an echo sounder survey was conducted to obtain data of water body depth and submerged aquatic vegetation height. The study was realized specifically on a region of Uberaba River with approximately 360.000 m². This river is part of the Porto Colombia reservoir. The data was processed and evaluated with main objective to develop an approach of spatial inference for map submersed macrophyte in the region studied. For this, it was verified the availability of using conventional interpolation to map the variables collected by the echo sounder, it was evaluated the potential of multispectral image with high spatial resolution (QuickBird) to detect the vegetation, it was done a spatial analysis and finally it was verified the possibility of using geostatistic technique to infer the submerged macrophytes height in the study area. The use of linear interpolation by triangulation was enough to represent rightly the underwater topography; however, the conventional interpolations were not satisfactorily to map the submerged vegetation height. The multispectral image was able to detect approximately 21% of submerged macrophytes. About spatial analysis, the results indicated that the spatial dependence must be considered, therefore, it was used the geostatistic in the spatial inference of submerged vegetation. Semivariograms analysis provided important knowledge about methods of echo sounder survey. The spatial inference by kriging showed satisfactory results if compared with conventional interpolations mentioned above. Finally, the approach used to mapping submerged macrophytes height can be applied in other regions and this can help the reservoirs management, allowing improve the knowledge about the local ecosystem and therewith developing an action strategy to contain the spread of submerged aquatic vegetation

Robust Vallisneria americana was cultured for restoration purposes. Preliminary studies, with various iron treatments, were conducted to ascertain the amount of phosphorous release into the water column from sediments. There was a significant difference in the amount of phosphorous released if commercial sediment was used with a low iron amendment or without an iron amendment. The second study consisted of planting V. americana on two different sediment types while supplying half of the plants with additional CO2. Plants grown on pond sediment with additional CO2 had significantly more biomass. In the third study all plants were grown on pond sediment, and half were treated with CO2. All plants that were treated with additional CO2 had significantly more biomass than those that were aerated.

The present thesis focuses on the interaction between refractory and liquid steel. The aim of this work is to understand the interaction behavior between refractory and liquid steel regarding steel cleanliness. The effect of different refractories on different inclusions in Al-killed steel was studied in a furnace. The sintering mechanism of filler sand were also investigated in laboratory. In the industrial trials, the attachments of different oxides on the walls of submerged entry nozzle (SEN) were discussed in the cases of high strength low alloy steel (HSLA) and ultra-low carbon steel (ULC). It is found that the effect of alumina and spinel refractory on all the three types of inclusions is very little, while MgO refractory influences the inclusions depending on the activity of dissolved oxygen in liquid steel. At low oxygen level, alumina inclusions could transform into spinel inclusions with the help of MgO refractory, while the effect on spinel and calcium aluminate inclusions is not evident. On the other hand, when the activity of dissolved oxygen is high enough, the evolution of spinel inclusions from alumina inclusions could not be seen. The reaction between chromite and silica grains leading to liquid formation is the main mechanism for the sintering of filler sand. The factors viz. steel composition, silica size and content, operation temperature and process holding time have a strong influence on the sintering of the filler sand. Smaller size and higher content of silica in sand, steel grades containing higher Mn and Al contents, higher temperature and longer holding time would result in serious sintering. The choice of the sand needs to take those factors into account. The results show that solid alumina particles are always agglomerated on the inner wall of SEN in the case of ULC steel. The top slag with high FeO and MnO contents is considered as the main reason of this kind of attachments. The removal of slag might be a good method to avoid the attachments. In the case of HSLA steel, liquid calcium aluminate inclusions could attach on the inner wall of SEN as well. The smoothness of the inner wall of the SEN holds the key of liquid attachments. In addition, the attachment situation on the outer wall of SEN depends on the operations. The oxygen entrainment through the mold powder would result in the formation of plate-like alumina attachments. The control of reoxidation due to oxygen entrainment would help to avoid this situation. / <p>QC 20160816</p>

Low-head dams are capable of creating dangerous counter-currents just downstream from the structure. These dangerous counter-currents are known as submerged hydraulic jumps and are responsible for hundreds of fatalities at numerous low-head dams across the United States. The counter-current creates high upstream-directed surface velocities across the width of the channel, making it nearly impossible for an individual to escape. This submerged jump can occur during a range of upstream and downstream conditions. Effective, safe and low-cost remediation options must be explored in order to prevent further fatalities at these structures. This document explores such a remediation option: the Multiple Staggered Deflector Design. This remediation option will disrupt uniform upstream-directed surface velocities across the channel within a submerged jump for nearly all downstream conditions that create a submerged jump for a range of upstream conditions. The dam modification is designed such that an individual will escape the submerged jump without severe injury or harm, while being relatively inexpensive and simple to install.

This thesis describes a short study to examine the behaviour of submerged flow over a thin plate weir with differing upstream and downstream bed levels i.e. an unequal bed weir as opposed to an equal bed weir where the upstream and downstream beds are at the same level. As submerged weir flow is a function of downstream conditions, it was thought that a lower downstream bed would make submerged flow over the weir easier, This is turn suggested that; The shape of the upstream head (Hu) vs downstream head (Hd) graph would change, being initially more steep in the unequal bed case. The Froude Number of the approaching flow would be lower for the unequal bed weir than for an equal bed weir at the same submergence. Using one of the existing submerged flow formula would lead to an erroneous calculated value. A series of measurements was done on two model weirs of different sizes subject to successive levels of submergence. Analysis of the readings of upstream and downstream heads indicated that the difference in bed levels was significant and the three effects above were noted. The work also suggested a new form of equation to calculate flow over a submerged weir. This was looked at briefly.