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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.
1

A sensitivity analysis of uncertainty in the spatial resolution of the underlying data used for estimating soil erosion susceptibility in New Zealand

Skurupey, James January 2013 (has links)
This study investigates the effect of changes in map scale on the error in the development of areal map units and their associated erosion severity measurements of New Zealand’s (NZ) Land Use Capability (LUC) surveying system. A map scale of 1:50,000 was used in the underlying data (i.e., a LUC survey) of an Erosion Susceptibility Classification (ESC) system, which was developed by Bloomberg and others (2011) of the University of Canterbury for the Ministry for the Environment’s (MFE) 2010 proposed National Environmental Standard for Plantation Forestry. The ESC was intended for local erosion management decisions, yet most literature would classify the map scale of 1:50,000 as more appropriate for regional management issues. Thus, this study will test two finer 1:10,000 scale datasets against the current 1:50,000 national LUC areal map units and their erosion severity measurements of the underlying data for the ESC system, to quantify the level of agreement. This study first attempted to identify a unique discriminating parameter of high erosion severity. A case study was conducted in the Sherry River catchment, located in the Tasman District of the South Island, NZ. The Sherry River Case Study had two aims; the first was to investigate the correlation between the Melton ratio and LUC erosion severity. This was accomplished by calculating the Melton ratio, a tested morphometric factor that describes basin (watershed) ruggedness, using Irvine’s (2011) Geographic Information Systems (GIS) debris-flow model. The product of this GIS debris-flow model, a calculated Melton ratio ≥ 0.50 with the areal extent outlined by a River Environment Classification (REC) order one polygon, were designated the areas of interest (AOIs). The Melton ratio was then tested against LUC erosion severity using the Spearman’s Ranked Correlation Coefficient, within the designated AOIs. A field investigation was conducted to verify debris-flow in GIS identified AOIs. Only five of the thirteen AOIs identified showed evidence of debris-flow. Two were un-checked due to accessibility and the others had a high degree of fluvial activity, which indicates a high probability that surface evidence of alluvial erosion deposition was erased. Nominal association between the two measurements of erosion (Melton ratio and LUC erosion severity) was found at the map scales of 1:50,000 or 1:10,000. Therefore the Melton ratio was not recommended as an independent parameter of erosion severity. The second aim of the Sherry River Catchment study was to assess the sensitivity of empirically generalised LUC areal map units and their erosion severity measurements to spatial resolution, that is, what is the effect of agreement between the smallest measurable value when looking at LUC map units and their erosion severity measurements recorded at two different map scales. A hard classification accuracy assessment was chosen to accomplish this objective. An accuracy assessment is a statistical model, which provides a probability of error (uncertainty), in essence a goodness-of-fit measurement, and quantified the agreement between a sample and reference dataset. This was accomplished by the calculation of an Overall accuracy (i.e., overall thematic agreement), Producer’s accuracy, and a User’s accuracy analytical statistics. The Producer’s accuracy refers to the probability that an area of sampled erosion severity category in the sample map is classified as such according to the reference map, while the user’s accuracy refers to the probability that a point labelled as a certain erosion severity in the sample map has that severity rating in reality (i.e., according to the reference map). An accuracy assessment also includes a second goodness-of-fit test, the Kappa statistic (K ̂), which measures the agreement between the sample and references map as well as chance agreement. An accuracy assessment of the AOIs within the Sherry Catchment Study area using an 85% significance criterion was conducted. This accuracy assessment investigated a sample LUC survey measured at the map scale of 1:10,000, as compared to the referenced underlying data of the ESC (1:50,000 map scale). Overall accuracy was marginal (69%) with equally marginal levels of Producer’s and User’s accuracy. The Kappa statistic showed a marginal level of significance according to Landis and Koch (1977) (K ̂ = 44%). The disagreement seen between the two LUC surveys, which were empirically developed using different map scales, provides evidence of high spatial resolution sensitivity, when comparing areal map units and erosion severity measurements. To further investigate evidence of spatial resolution sensitivity in LUC surveying, a second case study was conducted using a LUC survey across a broad geographical area of the Manawatu-Wanganui Region of the North Island, NZ. A sample dataset from the LUC survey, empirically generalised at 1:10,000 map scale by the Horizons Regional Council, was compared to the referenced underlying data of the ESC. There was a moderately-strong consistency found between the assessors of each LUC survey using Spearman’s Ranked Correlation Coefficient. This provides evidence of limited surveyor bias, as each map was made using empirical judgment. The accuracy assessment’s overall agreement was 63% and as for the previous case study, had equally low Producer’s and User’s accuracy levels. The Kappa statistic for this case study was K ̂= 46%, a moderate chance agreement. This evidence, along with the evidence provided by the Sherry River Catchment Case study, suggested that the MFE’s ESC system is sensitive to changes in map scale and that any decision based on it will have different results when its underlying data is produced at different spatial resolutions. It is therefore recommended that MFE reassess the map scales and resolutions of its underlying data, given that the ESC’s purpose is for local level environmental management, before imposing the system as a regulatory requirement in the National Environmental Standards for Plantation Forestry.
2

Distorsion de la perception visuelle spatiale en réalité virtuelle : mythe ou réalité ? / Distortion of spatial visual perception in virtual reality : myth or reality?

Rousset, Thomas 19 December 2018 (has links)
Cette thèse vise à avoir une meilleure compréhension des mécanismes qui sous-tendent la perception visuelle spatiale, et plus particulièrement la perception de la distance égocentrique. Nous cherchons à déterminer les raisons qui font que la distance égocentrique est, en général, sous-estimée lorsque l’observateur est placé dans un dispositif de réalité virtuelle par rapport au monde réel. Dans une première étude, nous montrons que la présence d’indice visuels liés à la parallaxe du mouvement de la tête impacte le comportement de suivi de véhicule des conducteurs en simulateur de conduite de manière différente selon qu’elle est couplée à une vision stéréoscopique ou non. Dans la seconde étude, nous montrons que l’étude de la variabilité interpersonnelle peut se révéler très informative et conduit à penser que le phénomène de sous-estimation de la distance en réalité virtuelle n’est pas généralisable à tous les participants. Dans la troisième étude, par le biais d’un modèle d’identification de facteur de gains, nous proposons une méthode afin de distinguer l’effet des erreurs de perceptions de distance égocentrique de celui des erreurs de perception de la distance parcourue. Les résultats de ces études montrent que la variabilité inter-individuelle doit être prise en compte dans l’évaluation de la perception spatiale. Ils apportent de plus des éléments de preuve en faveur d’une utilisation de différents référentiels spatiaux dépendant de la tâche demandée et pouvant varier significativement d’un individu à l’autre. Ces résultats sont à prendre en compte dès lors qu’on cherche à généraliser au monde réel les résultats d’études effectuées grâce à la réalité virtuelle. / This thesis aims to better understand the mechanisms that underlie spatial visual perception, and more particularly the perception of egocentric distance. We seek to determine the reasons that egocentric distance is, in general, underestimated when the observer is placed in a virtual reality device in relation to the real world. In a first study, we show that the presence of visual cues related to the head motion parallax impacts the drivers behavior in driving simulator differently depending on whether it is coupled to a stereoscopic vision or not. In the second study, we show that the analyse of interpersonal variability can be very informative and leads us to believe that the phenomenon of underestimation of distance in virtual reality is not generalizable to all participants. In the third study, using a gain factor identification model, we propose a method to distinguish the effect of egocentric distance perceptual errors from the perception of distance traveled. The results of these studies show that inter-individual variability must be taken into account in the evaluation of spatial perception. In addition, its provide evidence for the use of different spatial referenceframe that depend on the task requested and can vary significantly from one individual to another. These results are to be taken into account when one seeks to generalize to the real world the results of studies carried out thanks to the virtual reality.
3

Território usado e circuito superior marginal: equipamentos médico-hospitalares em Campinas, Ribeirão Preto e São José do Rio Preto (SP) / Used territory and upper circuit marginal: medical and hospital equipment in Campinas, Ribeirão Preto and São José do Rio Preto (SP)

David, Virna Carvalho 03 March 2011 (has links)
No contexto da especificidade da urbanização brasileira, onde as cidades crescem simultaneamente às formas de trabalho com capitais reduzidos e tecnologias menos modernas, nossa pesquisa analisa o território usado por diferentes agentes do sistema produtivo de equipamentos médicohospitalares no Estado de São Paulo, atentando para as diferentes divisões do trabalho existentes na forma dos circuitos da economia urbana. Valorizado de forma seletiva, o meio construído permite que atividades mais e menos rentáveis se instalem, enquanto a coexistência de divisões do trabalho que datam de diferentes épocas assegura uma dinâmica interdependente entre os circuitos da economia urbana. Neste sentido, discutimos a existência de um circuito superior marginal ligado às atividades de produção de equipamentos médicohospitalares em Campinas, Ribeirão Preto e São José do Rio Preto (SP) e o papel complementar que este cumpre para os serviços de saúde do país. / In the context of the specificity of Brazilian urbanization, where simultaneous with the growth of the cities, the types of work with reduced capital and less modern technologies also grow, our research analyses the territory used by different agents of the medicalhospital equipments production system in the state of São Paulo, looking at the different divisions of labor, existing in ways of the circuits of urban economy. Valued in a selective way, the environment building allows installation of more or less profitable activities, while the coexistence of divisions of labor of different ages ensures an interdependent dynamic among the circuits of the urban economy. In this way, we discuss the existence of a marginal upper circuit related to the medicalhospital equipments production in Campinas, Ribeirão Preto e São José do Rio Preto (SP) and its complementary function that it accomplishes for the brazilian health services.
4

Território usado e circuito superior marginal: equipamentos médico-hospitalares em Campinas, Ribeirão Preto e São José do Rio Preto (SP) / Used territory and upper circuit marginal: medical and hospital equipment in Campinas, Ribeirão Preto and São José do Rio Preto (SP)

Virna Carvalho David 03 March 2011 (has links)
No contexto da especificidade da urbanização brasileira, onde as cidades crescem simultaneamente às formas de trabalho com capitais reduzidos e tecnologias menos modernas, nossa pesquisa analisa o território usado por diferentes agentes do sistema produtivo de equipamentos médicohospitalares no Estado de São Paulo, atentando para as diferentes divisões do trabalho existentes na forma dos circuitos da economia urbana. Valorizado de forma seletiva, o meio construído permite que atividades mais e menos rentáveis se instalem, enquanto a coexistência de divisões do trabalho que datam de diferentes épocas assegura uma dinâmica interdependente entre os circuitos da economia urbana. Neste sentido, discutimos a existência de um circuito superior marginal ligado às atividades de produção de equipamentos médicohospitalares em Campinas, Ribeirão Preto e São José do Rio Preto (SP) e o papel complementar que este cumpre para os serviços de saúde do país. / In the context of the specificity of Brazilian urbanization, where simultaneous with the growth of the cities, the types of work with reduced capital and less modern technologies also grow, our research analyses the territory used by different agents of the medicalhospital equipments production system in the state of São Paulo, looking at the different divisions of labor, existing in ways of the circuits of urban economy. Valued in a selective way, the environment building allows installation of more or less profitable activities, while the coexistence of divisions of labor of different ages ensures an interdependent dynamic among the circuits of the urban economy. In this way, we discuss the existence of a marginal upper circuit related to the medicalhospital equipments production in Campinas, Ribeirão Preto e São José do Rio Preto (SP) and its complementary function that it accomplishes for the brazilian health services.
5

REGION-BASED GEOMETRIC ACTIVE CONTOUR FOR CLASSIFICATION USING HYPERSPECTRAL REMOTE SENSING IMAGES

Yan, Lin 20 October 2011 (has links)
No description available.
6

The Geography of Maternal Health Indicators in Ghana

Iyanda, Ayodeji Emmanuel 05 1900 (has links)
Ghana is identified among the developing countries with high maternal mortality ratio in Africa. This study unpacked the Demographic and Health Survey data by examining the maternal health indicators at the district level using GIS methods. Understanding the geographic patterns of antenatal care, place of delivery, and skilled birth attendants at the small scale will help to formulate and plan for location-specific health interventions that can improve maternal health care behavior among Ghanaian women. Districts with high rates and low rates were identified. Place of residence, Gini-Coefficient, wealth status, internet access, and religious affiliation were used to explore the underlying factors associated with the observed patterns. Economic inequality was positively associated with increased use of maternal health care services. The ongoing free maternal health policy serves as a cushion effect for the economic inequality among the districts in the Northern areas. Home delivery is common among the rural districts and is more prominent mostly in the western part of Northern Region and southwest of Upper West. Educating women about the free maternal health policy remains the most viable strategy for positive maternal health outcomes and in reducing MMR in Ghana.

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