Dissertations / Theses on the topic 'Temporary grace'

Gravity Recovery and Climate Experiment (GRACE) mission has amplified the knowledge of both static and time-variable part of the Earth’s gravity field. Currently, GRACE maps the Earth’s gravity field with a near-global coverage and over a five year period, which makes it possible to apply statistical analysis techniques to the data. The objective of this study is to analyse the most dominant spatial and temporal variability of the Earth’s gravity field observed by GRACE using a combination of analytical and statistical methods such as Harmonic Analysis (HA) and Principal Component Analysis (PCA). The HA is used to gain general information of the variability whereas the PCA is used to find the most dominant spatial and temporal variability components without having to introduce any presetting. The latter is an important property that allows for the detection of anomalous or a-periodic behaviour that will be useful for the study of various geophysical processes such as the effect from earthquakes. The analyses are performed for the whole globe as well as for the regional areas of: Sumatra- Andaman, Australia, Africa, Antarctica, South America, Arctic, Greenland, South Asia, North America and Central Europe. On a global scale the most dominant temporal variation is an annual signal followed by a linear trend. Similar results mostly associated to changing land hydrology and/or snow cover are obtained for most regional areas except over the Arctic and Antarctic where the secular trend is the prevailing temporal variability.
Apart from these well-known signals, this contribution also demonstrates that the PCA is able to reveal longer periodic and a-periodic signal. A prominent example for the latter is the gravity signal of the Sumatra-Andaman earthquake in late 2004. In an attempt to isolate these signals, linear trend and annual signal are removed from the original data and the PCA is once again applied to the reduced data. For a complete overview of these results the most dominant PCA modes for the global and regional gravity field solutions are presented and discussed.

Grave markers reflect a wealth of information and collectively epitomize society's historic, social, and economic patterns over time. Despite an abundance of cemetery research in other parts of the country, little research has been undertaken to evaluate grave marker attributes in Florida. The purpose of this research was to determine how grave marker attributes have changed over time in north-central, central, and southeast Florida. Data were collected from ten cemeteries in five counties in Florida, representing the grave markers of over 1,100 individuals. Data collection involved visiting each cemetery, photographing markers, and cataloging grave marker attributes. Attributes analyzed included marker type, marker material, epitaphs, iconographic images, memorial photographs, footstones, and kerbs. A number of important trends were noted. Marker material exhibited the clearest example of a temporal trend, shifting over time from 73% marble to 73% granite. Marker type varied greatly from upright and flat ground markers to a variety of customized markers and vaults. Cultural differences were also noted with in-ground vaults dominating traditionally black cemeteries. There were clear differences in marker style between affluent and less affluent cemeteries, with numerous hand-cast cement markers observed in less prosperous areas. Furthermore, beginning in the early 1980's there is an increase in customized laser engraved markers. Overall, Florida's cemeteries offer a rich history of the state's mortuary practices and further research should be conducted to preserve this history.
B.S.
Bachelors
Sciences
Anthropology

O objetivo deste trabalho é investigar o processo das variações do campo gravitacional, obtidas através da missão espacial GRACE e seu relacionamento com a dinâmica das águas na região Amazônica. A partir disto, procurou-se desenvolver uma metodologia para as estimativas das cotas dágua em áreas inundáveis não monitoradas ou de difícil acesso. Para isso, os coeficientes de Stokes, disponibilizados pelo GRGS de Toulouse, foram convertidos, por um processo denominado inversão, no equivalente à altura dágua (EqW) para o período de aproximadamente 4 anos (julho de 2002 a maio de 2006) e os valores comparados às cotas do nível dágua in-situ obtidas pela Agência Nacional de Águas (ANA). A escolha da bacia Amazônica está relacionada ao fato da mesma apresentar, próximo ao centro, amplitudes de aproximadamente 1250 mm no nível do EqW, sendo as maiores do mundo. A regionalização dos modelos globais das variações deste campo pôde ser aplicada para uma boa estimativa nas cotas dágua in-situ. Assim, foram estimados os erros desta metodologia, que são da ordem de ~160 mm para o EqW, oriundos dos erros nos coeficientes de Stokes, truncamento do espectro e erros de vazamento de informações hidrológicas das bacias vizinhas. Esta metodologia trata, portanto, de estimar as cotas onde não existam estações de monitoramento, avaliando a ordem de grandeza dos erros. Por fim, são apresentadas cartas que relacionam hidrogeologicamente as defasagens apresentadas nos ciclos semi-anuais e as áreas onde a metodologia poderá ser melhor aplicada com estimativas mais precisas do EqW e com maior coerência entre os dados satelitais e terrestres.
A comparison between vertically-integrated equivalent water height (EWH) derived from GRACE gravity anomalies with in situ water level time series measured at ground-based hydrometric stations (HS) in the Amazon basin is figure out in the thesis. A methodology for EWH estimation at ungauged sites is presented. The Stokes coefficients disponibilized by GRGS - Toulouse at a 10-day interval were converted into EWH for a ~4-year period (July-2002 to May-2006) using the methodology so-called inversion, and then compared to HS level. In the basin, the amplitudes of EWH signal are the largest on the Earth and can reach on the order of 1250 mm at the center of the basin (e.g. Manaus station). The uncertainties represent ~160 mm of EWH, including Stokes coefficient uncertainties, leakage errors and spectrum truncation. A methodology for acquire water level historical series at ungauged places is proposed with the estimated incertitude. A hydrological map is compared with a correlation chart and figure out areas where this methodology works better, in addition, compared also with shift phased semi-annual cycles.

Orientador : Prof. Dr. Regiane Dalazoana
Dissertação (mestrado) - Universidade Federal do Paraná, Setor de Ciências da Terra, Programa de Pós-Graduação em Ciências Geodésicas. Defesa: Curitiba, 28/07/2017
Inclui referências : f. 92-99
Resumo: A partir do lançamento dos primeiros satélites artificiais, deu-se início a uma grande revolução no que podemos denominar de Geodésia Moderna. Isso possibilitou, entre outras coisas, o desenvolvimento de modelos globais do geopotencial (MGGs) que geralmente são calculados em forma de coeficientes de uma expansão em séries de harmônicos esféricos e usados para modelar as funcionais do campo de gravidade da Terra. Com este trabalho tem-se o propósito de analisar a variação temporal da componente vertical de estações, que fazem parte da Rede Brasileira de Monitoramento Contínuo do GNSS (RBMC), através da utilização de modelos mensais derivados da missão GRACE, com base na funcional altitude geoidal. São realizadas comparações dos dados da RBMC, no que se refere à componente geométrica (altitudes elipsoidais) com altitudes com significado físico (as denominadas altitudes normais-ortométricas) geradas a partir dos MGGs. Os materiais para o cumprimento deste estudo compreendem: as séries temporais de coordenadas geodésicas referentes a 18 estações da RBMC, no período de tempo de Janeiro de 2012 a Julho de 2015, neste caso, coordenadas cartesianas são transformadas em coordenadas elipsoidais; e os modelos mensais do geopotencial baseados nos dados do satélite GRACE, provenientes de três centros de pesquisa, o Jet Propulsion Laboratory (JPL), o GeoForschungsZentrum (GFZ) e o Center for Space Research (CSR), sendo que os modelos foram desenvolvidos em diferentes graus, a saber: 60, 90 e 96. Destes modelos foram obtidos, para cada estação, os valores das altitudes geoidais que posteriormente foram utilizados na obtenção das altitudes normais-ortométricas. A metodologia emprega análises baseadas na determinação da regressão linear (visando obter a taxa de variação das altitudes) e a correlação entre as séries temporais de altitudes elipsoidais e normaisortométricas. Também foi feita a comparação entre as taxas de variação anual, para o período do trabalho, das altitudes geradas com as funcionais derivadas dos modelos do JPL, GFZ e CSR. Desta forma, o trabalho verificou a potencialidade da utilização de modelos mensais do geopotencial com base na missão GRACE. A verificação partiu de análises dos gráficos onde podem ser observadas as variações das altitudes elipsoidais e das altitudes ortométricas, gerando indicativos de possível soerguimento ou de subsidência da crosta. Na análise das variações anuais das altitudes elipsoidais e ortométricas, os valores obtidos pelo modelo JPL Release-05 desenvolvido até grau 60 e JPL Release-05 desenvolvido até o grau 90 mostraramse melhores quando comparados com os modelos gerados pelos outros centros de processamento na comparação com os mesmos graus de desenvolvimento, o que compreendeu 38,9% e 33,3% respectivamente, dos valores de variação menores do que um milímetro entre a altitude elipsoidal e a altitude ortométrica. Por fim, foram calculadas as correlações entre as séries temporais de altitudes elipsoidais, normais-ortométricas e altitudes geoidais. Os modelos mensais do geopotencial desenvolvidos até grau 60 tiveram maior correlação com os dados das altitudes elipsoidais quando comparados com os mesmos modelos desenvolvidos para os graus maiores, o que indica uma melhor correspondência entre as variações temporais da altitude elipsoidal e modelos mensais do geopotencial desenvolvidos até grau 60. Palavras-chave: Modelos mensais do geopotencial, GRACE, altitudes, variação temporal.
Abstract: From the launch of the first artificial satellites, it initiated a great revolution in what we can call Modern Geodesy. This allowed, among other things, the development of global geopotential models that are generally calculated as coefficients of an expansion in series of spherical harmonics and used to model the functionalities of the Earth's gravity field. The objective of this work is to analyze the temporal variation of the vertical component of stations that are part of the Rede Brasileira de Monitoramento Contínuo do GNSS (RBMC), using monthly models derived from the GRACE mission, based on the functional Geoid. Comparisons of RBMC data are made with respect to the geometric component (ellipsoidal height) with the component with physical meaning (ortometric height) generated from the MGGs. The materials for the accomplishment of this study comprise: the temporal series of geodesic coordinates referring to 18 RBMC stations, from January 2012 to July 2015, in this case, Cartesian coordinates are transformed into ellipsoidal coordinates: and the monthly geopotential models based on GRACE satellite data from three research centers, Jet Propulsion Laboratory (JPL), GeoForschungsZentrum (GFZ) and Center for Space Research (CSR), different degrees, namely: 60, 90 and 96. From these models were obtained, for each station, the values of the geoid that later were used to obtain the ortometric height. The methodology employs analyzes based on the determination of linear regression (aiming to obtain the rate of change of height) and the correlation between the time series of ellipsoidal and orthometric height. It was also made the comparison between the annual rates of change for the period of work, of the heights generated with the functional ones derived from the JPL, GFZ and CSR models. In this way, the work verified the potential of the use of monthly geopotential models based on the GRACE mission. The analysis was based on analysis of the graphs where the variations of the ellipsoidal height and the orthometric height can be observed, generating indications of possible uplift or subsidence of the crust. In the analysis of the annual variations of ellipsoidal and orthometric height, the values obtained by the JPL Release-05 developed until degree 60 and JPL Release-05 developed up to degree 90 showed the best results obtained when compared with the models generated by the others processing centers in comparison with the same degrees of development, which comprises 38,9 % and 33.3%, respectively, of variation values of less than one millimeter between ellipsoidal height and orthometric height. Finally, correlations between ellipsoidal and orthometric height were calculated. The monthly models of the geopotential developed up to degree 60 had a higher correlation with the data of the ellipsoidal height when compared with the same models developed for the greater degree, which indicates a better correspondence between the temporal variations of the ellipsoidal altitude and monthly models of the geopotential developed until degree 60. Keywords: Monthly models of geopotential, GRACE, heights, temporal variation.

A Analítica Visual (\textit{Visual Analytics}) é uma abordagem essencialmente computacional- incorporando aspectos multidisciplinares - dedicada à análise visual de um sistema de informação devidamente formatado para a inspeção e interpretação de dados por um especialista humano. Este trabalho está direcionado para o tratamento completo, incluindo a representação visual, de um sistema massivo de séries temporais. Este tratamento considera sua organização generalizada, a aplicação de ferramentas de análise e, por último, sua representação de forma que a visualização analítica possa ser utilizada pelo cientista na interpretação integrada dos dados para tomadas de decisão. Neste trabalho, é introduzido o conceito de grade numérica generalizada (GNG), que generaliza toda série temporal \textit{N}-dimensional a partir de três tipos de parâmetros: (i) grau variacional; (ii) coeficientes de extensão; e (iii) medidas analíticas. Demonstramos neste trabalho que qualquer conjunto de medidas nos domínios do tempo e do espaço pode ser reduzido a uma GNG. A funcionalidade, praticidade e robustez de uma representação de dados baseada no conceito de GNG são investigadas a partir de exemplos de aplicações em física espacial e ambiental. A pesquisa em analítica visual desenvolvida neste projeto de doutorado em Computação Aplicada envolveu a investigação de métodos de geração de séries temporais \textit{N}-dimensionais não lineares para construção de uma base canônica de dados, com o objetivo de testar a complexidade do modelo proposto. O método para análise de flutuações foi adotado como método analítico padrão para séries temporais, e o modelo de representação de GNGs foi desenvolvido em C++, XML e Java. Considerando o novo conceito proposto para grade numéricas generalizadas, como resultados principais desta pesquisa podemos destacar: proposta e apresentação de um novo modelo para representação e visualização analítica de séries temporais; e investigação de um gerador de dados canônicos para teste do modelo no contexto da sua aplicação para o monitoramento do clima espacial.
Visual Analytics is an essentially computational approach - incorporating multidisciplinary aspects - dedicated to the visual analysis of an information system to properly formatted to data inspection and interpretation by a human expert. This work is directed to the full treatment, including the visual representation, of a massive time series system. This treatment considers its generalized organization, the application of analysis tools and, finally, its representation so that the analytical visualization can be used by scientists in the integrated interpretation for decision making. In this paper, we introduce the concept of generalized numerical lattice (GNL), which generalizes every \textit{N}-dimensional time series from three types of parameters: (i) variational degree; (ii) extension coefficients; and (iii) analytical measurements. We have shown in this work that any set of measures in time and space domains can be reduced to a GNL. Functionality, practicity and robustness of a data representation based on GNL concept are investigated through examples of applications in space and environmental physics. The visual analytics research developed in this doctoral program in Applied Computing involved the investigation of methods for generating nonlinear \textit{N}-dimensional time series to construct a canonical data base, in order to test the proposed model complexity. The uctuation analysis method was adopted as a standard analytical method for time series, and the GNLs representation model was developed using C++, Java and XML. Given the new concept for generalized numerical lattices, as major results of this research we can highlight: the proposal and presentation of a new model for representing and visualizing analytical time series, and the investigation of a canonical data generator for testing the model in the context of its application in space weather monitoring.

L’objet de cette étude consiste en la comparaison des dispositions qui régissent le référé-suspension dans les systèmes juridiques français et grec. Le référé-suspension est un mécanisme procédural, qui a pour objectif la protection juridictionnelle provisoire de l’administré. Par recours en référé-suspension, nous entendons l’action qui permet à l’administré d’adresser devant le juge administratif – le juge des référés-suspension – une requête tendant à revendiquer son droit à une protection provisoire. Pour que le recours soit admis par le juge des référés-suspension, certaines conditions doivent être remplies. Quant à la procédure, elle se distingue des autres procédures administratives contentieuses par sa rapidité et sa souplesse, qui doivent permettre au juge de se prononcer en urgence. Pour cette raison, elle doit suivre une série de règles procédurales spécifiques. Dans un premier temps, nous nous concentrerons sur le référé-suspension en tant que recours, en le considérant comme un moyen juridique mis à la disposition de l’administré et lui permettant de faire valoir son droit à être provisoirement protégé. En second lieu, nous nous attacherons à analyser la procédure suivie par le juge du référé-suspension jusqu’au prononcé de sa décision et les voies de recours contre cette décision. L'étude des deux systèmes de protection juridictionnelle provisoire nous permettra de mieux évaluer les règlementations grecques et de comparer leur efficacité avec le système juridique français jugé performant, qui a servi d’exemple à de nombreux pays. Cette comparaison entre les deux systèmes pourrait nous permettre d’évaluer l’innovation et l’efficacité du « système - modèle »
The purpose of this thesis is to compare the legal provisions that codify summary suspension in both the French and Greek judicial systems. Summary suspension is a procedural mechanism which aims at providing temporary jurisdictional protection to the citizen. By “request for summary suspension”, we refer to the action which allows the citizen to submit before an administrative judge a request aiming to establish their right to temporary protection. In order for this request to be admitted by a judge competent for summary suspensions, certain conditions must be met. As regards the procedure, it differs from other contentious administrative procedures by virtue of its swiftness and flexibility, which allow the judge to pronounce a verdict with urgency. For this reason, it must follow a series of procedural rules. We will first focus on the summary suspension as a legal remedy, serving as a judicial means provided to the citizen (administered) entitling them to the right of temporary protection. Furthermore, we will strive to analyze the procedure followed by a judge competent for summary suspension up to the publication of their verdict, as well as the possible channels of appeal against their decision. The study of these two temporary jurisdictional protection systems will allow us to better evaluate Greek regulations and to compare their efficiency to that of the French judicial system, distinguished for its efficiency and serving as an example for many other countries. This comparison between the two systems will enable us to assess the innovation level and efficiency of the “model system”

The study investigated the long-term neuropsychological effects of repetitive mild traumatic brain injury (MTBI) due to participation in a contact sport amongst South African final year male high school athletes (N=189). The sample was divided by sports affiliation (Contact n = 115; Non-Contact n = 74) and concussion history (2+ Concussion n = 43; 0 Concussion n = 108). Comparative subgroups were statistically equivalent for age, education and estimated IQ (P > 0.05), with the Contact sport groups having markedly higher incidences of concussion than controls (p < 0.000). Measures included the ImPACT Verbal and Visual Memory, Visuomotor Speed and Reaction Time Composites, Digit Symbol Substitution and Digit Symbol Incidental Recall (immediate and delayed), the ImPACT Symptom Scale and a Post-concussion Symptom (PCS) questionnaire. Independent t-tests on cognitive measures at pre-and post-season revealed a predominant trend of Contact and 2+ Concussion groups performing worse, although only ImPACT Reaction Time at pre-season reached significance (p = 0.014). PCS comparisons revealed an overwhelming tendency of enhanced symptoms for Contact and 2+ Concussion groups with total scores being significantly different in most instances at pre-and post-season. Fatigue and aggression were the symptoms most pervasively high for the Contact and 2+ Concussion groups. Dependent t-test analyses at pre- versus post-season, revealed significant practice effects for the Contact group, not in evidence for controls on ImPACT Visual Motor Speed and Digit Symbol Incidental Recall-Delayed. Overall the results imply the possible presence of lingering neurocognitive and symptomatic concussion sequelae amongst South African final year high school participants of a contact sport. The indications gain potency when understood against the background of (i) Brain Reserve Capacity threshold theory, and (ii) the known risk of Type II error in group MTBI research, that might result in under-emphasis of subtle effects and miscalculation of cost-benefit risks. Clinical implications, and the need for prospective case-based research to ratify the results of this predominantly cross-sectional study, are discussed.

A study of local context has revealed that universal relief strategies are failing to meet the needs of those who have just lived through the traumatic experience of losing their primary dwelling. Where as conventional ‘donor’ structures may economically shelter the body, they neglect to address issues of home and belonging. The hypothesis argues that shelter after disaster is not just a temporary solution but rather a ‘starter kit’ with the potential of becoming a home. Hence shelter is the beginning of a process, that involves first a sign of the event of dwelling before it can host a more complex scope of concerns. While acknowledging that the design cannot be site specific, the proposal responds to regional disasters within greater Tshwane region, through a comprehensive investigation of context, climate and selected case studies. Set within the reality of monotonous modular design the project seeks to provide a flexible and innovative shelter typology that can remain on site, providing a period of grace. Thus enabling the displaced to focus on rebuilding their homes without living with the fear of their tent being reclaimed. The project conducts a critical investigation into rapidly deployable structure. The object of the study is to highlight the potential of cardboard as an alternative building material. Copyright
Dissertation (MInt(Prof))--University of Pretoria, 2010.
Architecture
unrestricted

碩士
中華大學
營建管理學系碩士在職專班
100
Railway reconstruction is formed from fives parts: civil engineering, signaling, electric engineering, electric supply, and rails. The various interface aspects and integration is more complex than general civil construction projects, with higher risks, time urgency, and other unique characteristics. During construction, work must be done close to the Taiwan Railway’s operating railway, or using times when trains are not operating, and coordinating with night time electricity shutoff and railroad route block off. This can cause train delays, accidents, or casualties with the slightest mistake. Before the start of railway conversion work, the existing rail system must be moved, and after the temporary rail is operating, the land for the existing track area must be vacated for railway Grade Separation. Because temporary railway construction is a critical part of the construction, its working space is limited, time is pressing, continuous railway operation must be maintained, and with a large number of unknown old TRA cables, these characteristics makes management during the construction process very important. Currently, most studies involve permanent elevation and underground utilization of the railway, cross railway construction, or worker safety. Less people are more familiar with the problems and handling that temporary railway construction stage faces. This study investigates the temporary railway track construction phase, and assembling literature review, collecting relevant domestic laws, and understanding the relevant regulations and restrictions, we proceed with case study and analysis. This study establishes the possible problems and coping strategies that faces the temporary railway construction phase. Then, by interviewing and verification of experts from various fields of railway construction, nine major problems are identified and include unfamiliarity of railway construction with neighboring railway operating environment, the great number of cables in the railway station, excavation and construction difficulties, the narrow and long construction route, the close planning of work to avoid interference, the complexity of the railway system interface, the need of close cooperation between various interface, the continued operation of the railway, the intrusion and clearing of railway requires night time power shut-off and route blockage, construction near adjacent power pole base and earth-retaining measures, the required clearance of the station platform edges to the railway, the safety limit and clearance maintenance of platform structure and building, and level crossing track lining and switching, as well as higher complexity before the construction. The experts then give suggested correction for the problems faced in the construction process and provide corresponding supplementary recommendations and coping strategies. It is hoped that this can provide the contractors, planning and design units, railway construction and supervision units, and construction companies with references, raising the awareness and alertness of risks faced by temporary railway track construction phase, and drawing up early coping strategies.

博士
國立交通大學
土木工程學系
98
This dissertation is aimed at temporal gravity field recovery from the analyses of the high-low satellite-to-satellite tracking (hl-SST) data from the COSMIC and GRACE satellite missions. In order to estimate the time-varying geopotential coefficients, two efficient methodologies, the analytical orbital perturbation (AOP) approach and the residual acceleration (ACC) approach, are developed in the research. With the reference orbits removed, orbital perturbations (difference between kinematic and reference orbits) and residual accelerations (difference between observed and reference accelerations) from the residual orbits are linear functions of the time-varying geopotential coefficients. Such linear functions enable convenient establishments of observation equations to estimate geopotential coefficients. The Bernese 5.0 software is used to compute the cm-level kinematic orbits of COSMIC and GRACE. The NASA Goddard’s GEODYN II software is used to compute the perturbing forces acting on COSMIC and GRACE satellites based on the standard models of orbit dynamics. The accelerations due to the atmospheric drag, solar radiation pressure and other minor surface forces are estimated by some relevant model parameters over one orbital period from COSMIC’s kinematic and reduced dynamic orbits. The 5s kinematic and dynamic orbits from six COSMIC and the 10s orbits from two GRACE satellites are re-sampled into 1 minute normal point positional data and then converted to acceleration data by numerical differential for gravity recovery. To validate the theories and computer programs associated with the AOP and ACC approaches, some experimental solutions of time-varying geopotential coefficients are carried out using one-month (August 2006) of COSMIC and GRACE kinematic and dynamic orbits. The average RMS in RTN directions of reduced COSMIC and GRACE (1 minute) between kinematic orbits and dynamic orbits are about 7.5 and 6.5 cm. The COSMIC solutions reveal several well-known temporal gravity signatures, but contain artifacts. The combined COSMIC-GRACE solutions enhance some local features in the GRACE solutions. The monthly COSMIC and GRACE precise orbit data from September 2006 to December 2007 (16 months) are processed to recover monthly low-degree (up to degree 5) geopotential coefficients by the AOP and ACC approaches. The geoid variations from such low-degree geopotential coefficients are compared with the CSR RL04 solutions. Two combined solutions by the AOP and ACC approaches (up to degree 15) are also carried out. The monthly variations of the zonal geopotential coefficients, the AOP and ACC solutions (degree 5) closely resemble the SLR-derived and CSR RL04 solutions.

Lead is a toxic heavy metal that has been extensively used in modern society, causing widespread environmental contamination, even in isolated parts of the world. There is now overwhelming evidence associating lead exposure with wideranging health effects, including reductions in intelligence scores, hyperactivity, shortened concentration spans, poor school performance, violent/aggressive behaviour, hearing loss, delayed onset of puberty, anaemia, and in severe cases, coma and death. In recent years consensus has been reached in respect of the absence of a threshold of safety for key health effects associated with lead exposure, and the permanent and irreversible nature of many of the health and social consequences of exposure to lead. The public health problem of environmental lead exposure has been widely investigated in developed countries such as the United States of America where, since the 1970s, policies and interventions have been followed by significant reductions in blood lead levels amongst children. In developing countries, and in African countries in particular, there is a relative dearth of information on the sources, mechanisms of exposure and blood lead distributions in children, and little action has been taken to protect children against lead poisoning. This study was undertaken to determine the current distribution of blood lead concentrations, and associated risk factors, amongst selected groups of first grade school children in the South African urban settings of Cape Town, Johannesburg 7 and Kimberley, a lead mining town (Aggeneys) and two rural towns in the Northern Cape province. A further objective of the study was to compare blood lead distributions determined in the current study with the findings of similar studies undertaken prior to the introduction in 1996 of unleaded petrol in South Africa. The results show that over the past decade, blood lead concentrations amongst first grade school children have declined considerably, but that large proportions of children, especially those living or attending school in impoverished areas, continue to have intolerably high blood lead concentrations, within a range that puts them at risk of detrimental health and social outcomes. The major sources of exposure to lead in the samples studied were leaded petrol, lead-based paint used to decorate homes and schools, lead solder used in “cottage industries” and other home-based lead-related activities, as well as the transfer of lead particles from lead-related work settings into homes. Recommendations for policy and relevant interventions for the South African context are discussed.

博士
國立交通大學
土木工程系所
93
With the advent of the CHAMP and GRACE satellite missions, satellite gravimetry has opened a new era featuring high spatial resolution and accuracy. These two missions provide continuous satellite tracking data in a high-low（HL-SST） and a low-low satellite-to-satellite tracking（LL-SST） scenario. They are both equipped with accelerometers for determining non-gravitational forces and star-cameras for determining attitudes. For each mission a laser retro-reflector is also mounted to provide additional tracking data. The GRACE mission uses a K-band ranging system to determine ranges and range rates (RR) between the two GRACE satellites at an accuracy of 10 m and 1 m/s, respectively. Precise range-rate rates (RRR) can be derived from RR. The uniqueness and the unprecedented accuracy of CHAMP and GRACE's tracking data have motivated this study, which mainly focuses on methods for efficiently recovering the Earth's gravity field and its temporal variation. A phase method is developed. In this method, GPS phase observations of a low earth orbiter (LEO) are used to compute line-of-sight accelerations between GPS and LEO, which are then used to determine the 3-dimensional accelerations of LEO using precise GPS ephemeris. Accelerations are linear functions of gravity coefficients, which make the least-squares estimation of gravity coefficients very simple in terms of computational effort. This method is efficient and does not require modeling GPS integer ambiguities. However, accelerations other than the Earth's gravity-induced acceleration must be modeled and removed from the phase-determined accelerations. The gravity coefficients recovered from CHAMP by this method agree well with the EGM96 gravity coefficients. Closed, linear expressions between RR or RRR and gravity coefficients are established using a linear orbit perturbation theory. These expressions are based on the concepts that RR is a function of the potential difference between two satellites and RRR is the line-of-sight acceleration. These expressions are used in a least-squares estimation of gravity coefficients from GRACE's RR or RRR. Seven days of simulated data using EGM96 and OSU91A have been used to test the theories and computer programs based on these expressions. A direct acceleration method is employed to determine the time variation of the Earth's gravity field. In this method, the accelerations of LEO are determined by numerical differentiations of the positions of LEO. After removing accelerations other than the Earth's gravity-induced accelerations, linear relations between LEO accelerations and gravity coefficients can be established, as in the phase method. Empirical parameters can be used to model the residual non-Earth-gravity accelerations. The time series of J2 derived from one year of CHAMP data and four months of GRACE data by this method closely resemble the SLR-derived time series of J2. Moreover, one set of normal equations is computed from a 7-day orbit arc. A total of 42 such normal equations from CHAMP data and 33 normal equations from GRACE data are computed. These normal equations are considered uncorrelated and are combined to determine an averaged gravity field. This gravity field yields a geoid model with an accuracy of better 5 mm at a spatial resolution of 1000 km half-wavelength, which is better than those derived from the recent satellite-only EIGEN-1S and EGM96 gravity fields.

碩士
國立屏東師範學院
教育心理與輔導研究所
90
The main purpose of this study was to explore the effects of social comparison and temporal comparison of academic performance on primary school students’ grade expectancy and performance. 716 students enrolled in the fifth or sixth grade of three schools were sampled from two major cities of southern Taiwan. They were administered a questionnaire that assessed background data, importance attributed to grade, social comparison targets and preferences, self-esteem, self-efficacy of grade improvement, grades of the four major courses in the previous test, grade expectancy for each of the 4 courses for the next test, and well-being. Longitudinal regression analyses were conducted to investigate the effects of social comparison directions and temporal comparison on students'' grade expectancy, performance on the next test, self-esteem, self-efficacy, and well-being. The following major findings were obtained: (1)Students tended to choose upward or similar comparison. Downward comparison was the least preferred. (2)The higher the grade of social comparison target, the higher the grade expectancy for the next test. Upward comparison was found to raise the grades of some subjects on the next test even after the grade of previous test and grade expectancy were controlled for. (3) Temporal comparison tended to have positive effects of grade expectancy and performance. (4)Longitudinal analysis showed that upward comparison and temporal comparison did not have effects on students’ self-esteem and well being.

碩士
國立中興大學
土木工程學系所
104
Due to Taiwan’s special geographical environment and the excessive concentration of rainfall in recent years, groundsills are frequently used to reduce scouring and stabilize the riverbed. However, the local scour downstream of the groundsill may grow with time, even causing the collapse of the structure. In order to increase our understanding of the temporal and spatial variations of the scour hole downstream of a grade-control structure, this study uses a PIV system to measure the mean velocity, turbulence intensity and Reynolds stress etc. for the movable bed tests in an indoor flume. The independent variables include the experimental duration(15 mins,1 hr, and 5 hrs), unit discharge(0.0167, 0.0283 and 0.0475 ㎡/s), and channel bed slope(1% and 1.5%). In addition, the measured bed shear stresses are compared with critical shear stresses calculated from the Shields diagram, and the exceeding probabilities are calculated along the whole scour hole surface. According to the experiment results, the flow enters the scour hole with a submerged jet, and the most violent variation of the turbulent flow occurs in the areas of the high-speed nappe and the hydraulic jump. Because of the diffusion phenomenon, velocity profiles will gradually develop into approximate normal distribution curves between the section with maximum scour depth and that with maximum water depth. The reach between the maximum scour depth and the maximum flow depth have almost reached equilibrium at t= 5 hrs except the large unit discharge (M-2 and M-3) cases. Besides, the exceeding probability decreases with time, and increases with the unit discharge and slope. The results also reveal that the scour hole still continuously stretches after 5 hrs for the large unit discharge cases.

In der vorliegenden Arbeit wurde durch die Kombination zweier nichtinvasiver MR-Methoden in vivo untersucht, ob sich die funktionelle Sprachlateralisierung in einer strukturellen Asymmetrie der weißen Substanz widerspiegelt. Dafür wurden die Ergebnisse einer Patientengruppe mit Temporallappenepilepsie mit den Ergebnissen einer gesunden Kontrollgruppe verglichen. Es konnte gezeigt werden, dass mittels BOLD MRT eine Sprachlateralisierung in der grauen Substanz nachgewiesen werden kann, die mit einem strukturellen Korrelat in der weißen Substanz der sprachdominanten Hemisphäre einhergeht. Dieses Korrelat konnte als Asymmetrie der Mikrostruktur der weißen Substanz in DTI-Messungen belegt werden. Darüber hinaus konnte bewiesen werden, dass Patienten mit einer Temporallappenepilepsie im Vergleich zu gesunden Probanden eine atypische Lateralisierung der Sprachaktivierung im Broca-Areal aufweisen, die von einer gleichsinnig atypischen strukturelle Asymmetrie der weißen Substanz im Broca-Areal begleitet wird. Die These, dass eine funktionelle Sprachlateralisierung mit einer mikrostrukturellen Veränderung der weißen Substanz assoziiert ist, wird durch die vorliegende Arbeit sowohl für die gesunden Kontrollprobanden als auch für die Patienten mit einer fokalen Epilepsie bestätigt. Die Ergebnisse der vorliegenden Arbeit zeigen, dass DTI-Messungen eine sinnvolle Ergänzung zu BOLD MRT-Messungen in der Bestimmung der sprachrelevanten Areale darstellen können. Sprachlateralisierung könnte mit ihrer Hilfe in Zukunft exakt und nichtinvasiv bestimmt werden. Es stellte sich jedoch auch heraus, dass das in der vorliegenden Arbeit angewendete Verfahren in der Praxis sehr aufwendig ist, ohne eine entschieden höhere Aussagekraft über die Sprachlateralisierung zu erbringen. In dieser Form wird die nichtinvasive Bildgebung den Wada-Test als Goldstandard für den klinischen Alltag noch nicht ersetzen können.