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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
331

Amherst Township, a regional study

Rockwood, Ruth C January 1936 (has links)
No description available.
332

Determination of Oxygen Fugacity using Olivine-Melt Equilibrium: Implications for the Redox States of Mid-Ocean Ridge Basalt and Ocean Island Basalt Mantle Source Regions

Peterman, Kenneth James January 2017 (has links)
No description available.
333

New constraints on timing and kinematics of rifting at Cape Roberts Basin and Roberts Ridge from integrated seismic and core analysis of fault arrays

Trunkely, Zachary J. 06 January 2012 (has links)
No description available.
334

Vernal Pool Mapping and Geomorphology in the Appalachian Mountains of Pennsylvania

Blackman, Taylor Nathaniel 11 June 2019 (has links)
Vernal pools are small seasonally-ponded wetlands that provide crucial habitat for amphibian reproduction and support trophic levels beyond their boundaries. The Ridge and Valley physiographic province in Pennsylvania is known to have vernal pools, but a regional inventory and geomorphology assessment is needed. My research is split into two independent parts focusing on the higher elevation areas of this region to determine vernal pool distribution and characteristics. Vernal pools were mapped using a LiDAR based suitability model and leaf-off aerial imagery interpretation. Four terrain rasters derived from a 1-meter DEM (modified wind modified wind exposure, terrain surface convexity, topographic position index, and a multiresolution index of valley bottom flatness) were used in the suitability model. An analysis of variance (ANOVA) and Tukey's HSD test found a significant difference using the model between terrestrial (non-wetland) habitat and vernal pools. Photo interpretation and field surveying lead to an inventory of 1011 vernal pools. Geomorphology was assessed from 13 variables to determine the best for vernal pool prediction. Three variables were significant for the occurrence and frequency of vernal pools; saddles with higher surface area, 0.6 to 1.5 kilometers between the summits of parallel ridgelines, and the presence of periglacial related solifluction. Vernal pool distribution is greater than previously known and they occur in predictable settings. Further research should focus on how and where vernal pools form, their impact on water quality, role in forest ecology, and ways to legally protect them at the state level. / Master of Science / Vernal pools are seasonally-ponded wetlands that are very important for amphibian reproduction. The Appalachian Mountains of Pennsylvania are known to have vernal pools, but comprehensive inventory is lacking. My research consists of two parts that focus on the higher elevation areas and assess the distribution and qualities of the vernal pools. Vernal pools were mapped using a LiDAR based suitability model and leaf-off aerial imagery interpretation. Statistical analysis was completed to prove that there was a significant difference in terrain morphology between non-wetland habitat and vernal pools. This research resulted in a total inventory of 1011 vernal pools. Results found that vernal pools were likely occur in landscape positions with higher surface area, 0.6 to 1.5 kilometers between the summits of parallel ridgelines, and the presence of topographic features indicative of glacial processes. Vernal pools are much more abundant than previously known and they occur in predictable settings. Further research could focus on the formation of vernal pools, impact on water quality, role in forest ecology, and ways to legally protect them at the state level.
335

Using Accumulation Based Network Identification Methods to Identify Hill Slope Scale Drainage Networks in a Raster GIS

Burgholzer, Robert William 20 January 2006 (has links)
The simple accumulation-based network identification method (ANIM) in a raster Geographic Information System (GIS) posed by O'Callaghan and Mark (1984) has been criticized for producing a spatially uniform drainage density (Tarboton 2002) at the watershed scale. This criticism casts doubt on the use of ANIMs for deriving properties such as overland flow length for nonpoint source pollution models, without calibrating the accumulation threshold value. However, the basic assumption that underlies ANIMs is that convergent topography will yield a more rapid accumulation of cells, and thus, more extensive flow networks, with divergent, or planar terrain yielding sparser networks. Previous studies have focused on networks that are coarser than the hill-slope scale, and have relied upon visual inspection of drainage networks to suggest that ANIMs lack the ability to produce diverse networks. In this study overland flow lengths were calculated on a sub-watershed basis, with standard deviation, and range calculated for sub-watershed populations as a means of quantifying the diversity of overland flow lengths produced by ANIM at the hill slope scale. Linear regression and Spearman ranking analyses were used to determine if the methods represented trends in overland flow length as suggested by manual delineation of contour lines. Three ANIMs were analyzed: the flow accumulation method (O'Callaghan and Mark, 1984), the terrain curvature method (Tarboton, 2000) and the ridge accumulation method (introduced in this study). All three methods were shown to produce non-zero standard deviations and ranges using a single support area threshold, with the terrain curvature method producing the most diverse networks, followed by the ridge accumulation method, and then the flow accumulation method. At an analysis unit size of 20 ha, the terrain curvature method produced a standard deviation that was most similar to those suggested by the contour crenulations, -13.5%, followed by the ridge accumulation method, -21.5%, and the flow accumulation method, -61.6%. The ridge accumulation produced the most similar range, -19.1%, followed by terrain curvature, -24.9%, and flow accumulation, -65.4%. While the flow accumulation networks had a much narrower range of predicted flow lengths, it had the highest Spearman ranking coefficient, Rs=0.722, and linear regression coefficient, R2=0.602. The terrain curvature method was second, Rs=0.641, R2=0.469, and then ridge accumulation, Rs=0.602, R2=0.490. For all methods, as threshold values were varied, areas of dissimilar morphology (as evidenced by the common stream metric stream frequency) experienced changes in overland flow lengths at different rates. This results in an inconsistency in ranking of sub-watersheds at different thresholds. When thresholds were varied to produce average overland flow lengths from 75 m to 150 m, the terrain curvature method showed the lowest incidence of rank change, 16.05%, followed by the ridge accumulation method, 16.73%, then flow accumulation, 25.18%. The results of this investigation suggest that for all three methods, a causal relationship exists between threshold area, underlying morphology, and predicted overland flow length. This causal relationship enables ANIMs to represent contour network trends in overland flow length with a single threshold value, but also results in the introduction of rank change error as threshold values are varied. Calibration of threshold value (varying threshold in order to better match observed overland flow lengths) is an effective means of increasing the accuracy of ANIM predictions, and may be necessary when comparing areas with different stream frequencies. It was shown that the flow accumulation method produces less diverse networks than the terrain curvature and ridge accumulation methods. However, the results of rank and regression analyses suggest that further investigation is required to determine if these more diverse ANIM are in fact more accurate than the flow accumulation method. / Master of Science
336

Desarrollo de Nuevos Componentes Pasivos de Microondas en Tecnología Guiada para Bandas Altas de Frecuencia

Ruiz Garnica, Jesús 16 December 2019 (has links)
[ES] La presente tesis doctoral tiene como objetivo fundamental el desarrollo de nuevos componentes pasivos de microondas para bandas altas de frecuencia, que puedan llegar a operar, al menos, hasta la banda Ka. Estos nuevos componentes surgen en respuesta a la clara tendencia en el ámbito de las comunicaciones vía satélite de aumentar la frecuencia y el ancho de banda de trabajo, en aras de incrementar las velocidades de transmisión. Concretamente, se ha abordado el diseño de elementos básicos de un subsistema de comunicaciones vía satélite, como son las uniones en guía de onda y los filtros paso banda. Por una parte, se han desarrollado uniones compensadas en guía de onda double ridge (T en plano H, T en plano E y T mágica), superando las limitaciones en ancho de banda que presentan las uniones tradicionales construidas sobre guía rectangular. Se ha pretendido lograr el objetivo de desarrollar unas uniones capaces de interconectar elementos que cubran un amplio ancho de banda, lo que también incluye los filtros de nueva generación presentados en esta tesis. Por otro lado, se ha propuesto una novedosa técnica para el diseño de filtros paso banda con inversores de inmitancia, basada en el slope parameter. A diferencia de la técnica tradicional, este nuevo proceso tiene en cuenta la dependencia real de los elementos del filtro con la frecuencia, calculando y actualizando el slope parameter de cada resonador cargado con sus elementos de acoplo adyacentes en un proceso iterativo que llega a convergencia en pocas iteraciones. Así, este procedimiento basado en simulaciones electromagnéticas y cálculos, mejora la equivalencia entre el prototipo circuital y la estructura real sintetizada, ya que tiene en cuenta no sólo la dependencia con la frecuencia de los resonadores y los inversores individuales, sino también los efectos de carga que existen entre ellos. Además, se ha identificado que el mapeado en frecuencia elegido ha de ser el correcto para cada estructura y especificaciones del filtro. Como resultado, se obtienen unas mejores dimensiones iniciales, reduciendo de esta manera el coste computacional del paso final de optimización, que puede incluso llegar a ser innecesario en algunos casos. Este nuevo procedimiento se ha ilustrado mediante la síntesis de dos filtros de modo evanescente y mediante filtros radiantes que emplean una topología similar. Finalmente, se ha llevado a cabo el estudio de una nueva familia de filtros denominada Modified Hybrid Folded Rectangular Waveguide (MHFRW), que además de operar en las citadas bandas de frecuencia, son capaces de manejar altos niveles de potencia, son fáciles de diseñar y fabricar (sin requerir tornillos de sintonía en muchos casos) y además presentan bajas pérdidas. Todo ello con la ventaja añadida de poder poner un número de ceros de transmisión mayor al orden del filtro (filtros superelípticos) mediante el uso de stubs cortocircuitados de longitud adecuada. Para ilustrar su funcionamiento se han presentado dos ejemplos detallados. El primero de ellos, que no presenta ceros de transmisión, se ha diseñado mediante la nueva técnica del slope parameter. El segundo se trata de un filtro superelíptico, con 4 ceros de transmisión (2 antes de la banda de paso y 2 después) implementados con 4 stubs en un filtro de orden 3. Por último, se ha mostrado la gran potencialidad práctica de esta familia de filtros mediante su aplicación en complejos multiplexores para bancos de medida de intermodulación pasiva (PIM). / [CA] La present tesi doctoral té com a objectiu fonamental el desenvolupament de nous components passius de microones per a bandes altes de freqüència, que puguen arribar a operar almenys fins a la banda Ka. Aquests nous components sorgeixen en resposta a la clara tendència en l'àmbit de les comunicacions via satèl·lit d'augmentar la freqüència i l'amplada de banda de treball, a fi de incrementar les velocitats de transmissió. Concretament, s'ha abordat el disseny d'elements bàsics d'un subsistema de comunicacions via satèl·lit, com són les unions en guia d'ona i els filtres passabanda. D'una banda, s'han desenvolupat unions compensades en guia d'ona double ridge (T en pla H, T en pla E i T màgica), superant així les limitacions d'amplada de banda que presenten les unions tradicionals, construïdes sobre guia rectangular. S'ha pretès aconseguir l'objectiu de desenvolupar unes unions capaces d'interconnectar elements que cobrisquen una gran amplada de banda, cosa que inclou els filtres de nova generació presentats en aquesta tesi. D'altra banda, s'ha proposat una nova tècnica per al disseny de filtres passabanda amb inversors d'immitància, basada en l'slope parameter. A diferència de la tècnica tradicional, aquest nou procés té en compte la dependència real dels elements del filtre respecte de la freqüència, i calcula i actualitza l'slope parameter de cada ressonador carregat amb els elements d'acoblament adjacents, en un procés iteratiu que arriba a convergència en poques iteracions. Així, aquest procediment basat en simulacions electromagnètiques i càlculs millora l'equivalència entre el prototip circuital i l'estructura real sintetitzada, ja que té en compte no sols la dependència respecte de la freqüència dels ressonadors i els inversors individuals, sinó també els efectes de càrrega que hi ha entre aquests. A més, s'ha identificat que el mapatge en freqüència triat ha de ser el correcte per a cada estructura i especificacions del filtre. Com a resultat, s'obtenen unes millors dimensions inicials, i d'aquesta manera es redueix el cost computacional del pas final d'optimització, que fins i tot pot arribar a ser innecessari en alguns casos. Aquest nou procediment s'ha il·lustrat mitjançant la síntesi de dos filtres de mode evanescent i mitjançant filtres radiants que empren una topologia similar. Finalment, s'ha portat a terme l'estudi de una nova família de filtres denominada Modified Hybrid Folded Rectangular Waveguide (MHFRW), que, a més d'operar en les citades bandes de freqüència, són capaços de manejar alts nivells de potència, fàcils de dissenyar i fabricar (sense requerir caragols de sintonia en molts casos) i, a més, presenten baixes pèrdues. Tot això, amb l'avantatge afegit de poder posar un nombre de zeros de transmissió major que l'ordre del fltre (filtres superel·líptics) mitjançant l'ús de stubs curtcircuitats de longitud adequada. Per il·lustrar-ne el funcionament se n'han presentat dos exemples detallats. El primer d'aquests, que no presenta zeros de transmissió, s'ha dissenyat mitjançant la nova tècnica de l'slope parameter. El segon es tracta de un filtre superel·líptic, amb 4 zeros de transmissió (2 abans de la banda de pas i 2 després) implementats amb 4 slope en un filtre d'ordre 3. Finalment, s'ha mostrat la gran potencialitat pràctica d'aquesta família de filtres mitjançant l'aplicació en multiplexors complexos per a bancs de mesurament de la intermodulació passiva (PIM). / [EN] The main objective of this Ph.D. thesis is the development of new passive microwave components for high frequency bands, able to work at least up to Ka band. These new components aim at satisfying the needs of new communication systems, especially for satellite communications, where there is a trend to increase frequency and bandwidth of operation. Specifically, the design of basic hardware elements of satellite communication subsystems has been addressed, such as waveguide junctions and bandpass filters. On the one hand, compensated T-junctions have been developed in double ridge waveguide (H-plane T, E-plane T and magic T), in order to overcome the bandwidth limitations of traditional junctions built on rectangular waveguide technology. The development of junctions able of interconnecting elements over a wide bandwidth has been pretended, including also the new generation of filters presented in this Ph.D. thesis. On the other hand, a novel technique for the design of bandpass filters with immittance inverters has been proposed. This technique is based on the slope parameter. Unlike traditional techniques, this new process takes into account the actual dependence of filter elements with frequency, calculating and updating the slope parameter of each resonator loaded with its adjacent coupling elements in an iterative process. This process reaches convergence after few iterations. Therefore, this procedure (based on electromagnetic simulations and calculations) improves the equivalence between the circuit prototype and the real structure, since it takes into account the frequency dependence of resonators and individual inverters, including also the loading effects between them. In addition, it is important to point out that an appropriate frequency mapping must be chosen for each structure and filter specifications. As a result, better initial dimensions can be obtained, thus reducing the computational cost of the final optimization step, which can even become unnecessary in some cases. This new procedure has been illustrated by the synthesis of two evanescent-mode filters and several radiating filters based on a similar topology. Finally, the study of a new filter family called Modified Hybrid Folded Rectangular Waveguide (MHFRW) has been carried out. Besides operating in the mentioned frequency bands, theses filters are capable of handling high power levels, are easy to design and manufacture (without requiring tuning screws in many cases) and also present low losses. Likewise, this type of filters are able to generate a number of transmission zeros greater than the order of the filter (i.e., provide super-elliptic responses) by means of shortcircuited stubs. To illustrate its operation, two examples have been presented in detail. The first of them, which does not have transmission zeros, has been implemented using the new technique of slope parameter. Accordingly, the suitability of this method for this type of structure is demonstrated. The second is a super-elliptic filter, with 4 transmission zeros (2 before the passband and 2 after it) implemented with 4 stubs in a filter of order 3. To conclude and show the practical capabilities of the proposed family of filters, they have been successfully applied in the development of complex multiplexers for passive intermodulation (PIM) measurement test benches. / Ruiz Garnica, J. (2019). Desarrollo de Nuevos Componentes Pasivos de Microondas en Tecnología Guiada para Bandas Altas de Frecuencia [Tesis doctoral]. Universitat Politècnica de València. https://doi.org/10.4995/Thesis/10251/133058
337

Manobra de Chompret: alterações dimensionais alveolares vestíbulo palatinas em regiões homólogas que foram submetidas a exodontia / Chomprets manouver: dimensional differences on bucco-palatal measurements in homologues sites submitted to teeth extraction

Hanna, Leandro Botelho 15 June 2011 (has links)
A exodontia é o procedimento cirúrgico odontológico bastante praticado pelo Cirurgião Dentista clínico geral e pelo especialista quando, por diversos motivos, o elemento dentário necessita ser avulsionado. Atualmente a literatura ressalta enfaticamente a importância da preservação do rebordo alveolar durante o planejamento cirúrgico da exodontia, no que tange ao uso de técnicas cirúrgicas minimamente traumáticas, bem como o tratamento dado ao alvéolo fresco. Este estudo caso controle verifica variações das dimensões alveolares horizontais em alvéolos de dentes homólogos anteriores superiores, onde se realizou a manobra de Chompret (controle) e alvéolos onde esta não foi realizada (teste), ao final de um intervalo de sete dias pós operatórios, e conclui que há uma alteração dimensional média de 6,2% em espessura na parte coronária do alvéolo (p=0,003), quando se faz a manobra, também conhecida por compressão alveolar bidigital pós exodontia. O paciente necessita e deve ser reabilitado para que possa, dentro dos limites protéticos, voltar a ter suas funções mastigatória, estética e dictiva restauradas, o que nos compromete a espoliar ao mínimo suas estruturas ósseas remanescentes. / Tooth extraction is a surgical dental procedure always performed by general dentists and specialists when a tooth requires extraction, by several causes. Actually dental literature enphasizes alveolar ridge preservation importance during surgical planning to teeth extraction considering minimally traumatic surgical skill and the treatment gave to fresh socket. This case control study verifies horizontal alveolar dimensions in homologues upper anterior tooth extracted alveoli, in which Chomprets maneuver, known by post-extraction alveolar compression, was performed (Control) and alveoli in which this one was not performed (Test), in a post-operative seven days gap of time, and concludes that there is width dimensional difference of 6,2% in the alveolus coronary section (p=0.003) when the maneuver is done. Patients must be rehabilited to can, inside prosthetics limits, to chew, to speak, to smile, to get aesthetics, what compromises us to prevent damages to remaining bone structures during tooth extraction and post-extraction socket procedures.
338

Manobra de Chompret: alterações dimensionais alveolares vestíbulo palatinas em regiões homólogas que foram submetidas a exodontia / Chomprets manouver: dimensional differences on bucco-palatal measurements in homologues sites submitted to teeth extraction

Leandro Botelho Hanna 15 June 2011 (has links)
A exodontia é o procedimento cirúrgico odontológico bastante praticado pelo Cirurgião Dentista clínico geral e pelo especialista quando, por diversos motivos, o elemento dentário necessita ser avulsionado. Atualmente a literatura ressalta enfaticamente a importância da preservação do rebordo alveolar durante o planejamento cirúrgico da exodontia, no que tange ao uso de técnicas cirúrgicas minimamente traumáticas, bem como o tratamento dado ao alvéolo fresco. Este estudo caso controle verifica variações das dimensões alveolares horizontais em alvéolos de dentes homólogos anteriores superiores, onde se realizou a manobra de Chompret (controle) e alvéolos onde esta não foi realizada (teste), ao final de um intervalo de sete dias pós operatórios, e conclui que há uma alteração dimensional média de 6,2% em espessura na parte coronária do alvéolo (p=0,003), quando se faz a manobra, também conhecida por compressão alveolar bidigital pós exodontia. O paciente necessita e deve ser reabilitado para que possa, dentro dos limites protéticos, voltar a ter suas funções mastigatória, estética e dictiva restauradas, o que nos compromete a espoliar ao mínimo suas estruturas ósseas remanescentes. / Tooth extraction is a surgical dental procedure always performed by general dentists and specialists when a tooth requires extraction, by several causes. Actually dental literature enphasizes alveolar ridge preservation importance during surgical planning to teeth extraction considering minimally traumatic surgical skill and the treatment gave to fresh socket. This case control study verifies horizontal alveolar dimensions in homologues upper anterior tooth extracted alveoli, in which Chomprets maneuver, known by post-extraction alveolar compression, was performed (Control) and alveoli in which this one was not performed (Test), in a post-operative seven days gap of time, and concludes that there is width dimensional difference of 6,2% in the alveolus coronary section (p=0.003) when the maneuver is done. Patients must be rehabilited to can, inside prosthetics limits, to chew, to speak, to smile, to get aesthetics, what compromises us to prevent damages to remaining bone structures during tooth extraction and post-extraction socket procedures.
339

“Chemical fingerprinting” of volcanic tephra found in Kansas using trace elements

David, Brian T. January 1900 (has links)
Master of Science / Department of Geology / Matthew W. Totten / Sedimentary beds rich in volcanic ash have been reported throughout Kansas. It is believed the source of these ashes are the large-scale eruptions from the Yellowstone Calderas. Very few of these ash units have been dated, however, and the vast majority simply reported as “Pearlette Ash.” The objective of this research was to investigate the potential of trace element geochemistry in correlating individual ash outcrops in Kansas to their eruptive source. Thirty-six previously reported ash occurrences of unknown age in Kansas were reoccupied and sampled. In addition, three unreported ash deposits were discovered and sampled. Two ash units previously identified as Huckleberry Ridge-aged and three as Lava Creek B were also collected. The samples were processed using the method of Hanan and Totten (1998) to concentrate ash shards. These ash concentrates were analyzed for specific trace and rare earth element (REE) concentrations using inductively coupled mass-spectrometry (ICP-MS) at the University of Kansas. The ash samples from known eruptions have distinct trace and REE signatures, allowing comparison to the unknown ash units. Most of the unknown ash samples correlate with specific Yellowstone eruptions. The majority of the undifferentiated “Pearlette Ash” samples correlate with the most recent Lava Creek B eruption and several unknown ashes correlate to the Huckleberry Ridge eruption. The distribution of ash units in Kansas being dominated by Lava Creek (0.60 ma) is expected because it is the most recent of the Yellowstone eruptions. The abundance of the older Huckleberry Ridge (2.10 ma) over the more recent Mesa Falls (1.27 ma) is likely the result of the much larger Huckleberry Ridge eruption.
340

The implementation of noise addition partial least squares

Moller, Jurgen Johann 03 1900 (has links)
Thesis (MComm (Statistics and Actuarial Science))--University of Stellenbosch, 2009. / When determining the chemical composition of a specimen, traditional laboratory techniques are often both expensive and time consuming. It is therefore preferable to employ more cost effective spectroscopic techniques such as near infrared (NIR). Traditionally, the calibration problem has been solved by means of multiple linear regression to specify the model between X and Y. Traditional regression techniques, however, quickly fail when using spectroscopic data, as the number of wavelengths can easily be several hundred, often exceeding the number of chemical samples. This scenario, together with the high level of collinearity between wavelengths, will necessarily lead to singularity problems when calculating the regression coefficients. Ways of dealing with the collinearity problem include principal component regression (PCR), ridge regression (RR) and PLS regression. Both PCR and RR require a significant amount of computation when the number of variables is large. PLS overcomes the collinearity problem in a similar way as PCR, by modelling both the chemical and spectral data as functions of common latent variables. The quality of the employed reference method greatly impacts the coefficients of the regression model and therefore, the quality of its predictions. With both X and Y subject to random error, the quality the predictions of Y will be reduced with an increase in the level of noise. Previously conducted research focussed mainly on the effects of noise in X. This paper focuses on a method proposed by Dardenne and Fernández Pierna, called Noise Addition Partial Least Squares (NAPLS) that attempts to deal with the problem of poor reference values. Some aspects of the theory behind PCR, PLS and model selection is discussed. This is then followed by a discussion of the NAPLS algorithm. Both PLS and NAPLS are implemented on various datasets that arise in practice, in order to determine cases where NAPLS will be beneficial over conventional PLS. For each dataset, specific attention is given to the analysis of outliers, influential values and the linearity between X and Y, using graphical techniques. Lastly, the performance of the NAPLS algorithm is evaluated for various

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