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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.
201

On optimum sample allocation in multivariate surveys

Kouri, Brian January 1976 (has links)
No description available.
202

A General Observational Strategy for Validation of Satellite NO₂ Retrievals using Multi-Axis Differential Optical Absorption Spectroscopy (MAX-DOAS)

Earley, Jeffrey D. 21 June 2022 (has links)
This thesis analyzes the effectiveness of spatially averaged Multi-AXis Differential Optical Absorption Spectroscopy (MAX-DOAS) measurements at regular azimuth angle intervals on an hourly basis to validate satellite based DOAS measurements. Off-Axis MAX-DOAS Measurements taken in Blacksburg, Virginia, between November 2021 and April 2022 with an evenly distributed set of measurements were averaged every hour and compared to Direct Sun measurements, also averaged every hour. Comparisons of the difference in average measurement from both measuring strategies, as well as the distribution standard deviations of hourly measurements suggests that the NO₂ distribution around Blacksburg is homogeneous. In order to test the effectiveness of this sampling strategy,in an inhomogeneous location, the LOTOS-EUROS high resolution (1kmx1km) chemical transport model was used to simulate profiles and vertical column densities of real measurements taken during the TROLIX'19 Field Campaign. The LOTOs-EUROS model was used to simulate vertical profiles as well as Vertical Column Densities based on real MAX-DOAS measurements as well as TROPOMI viewing geometry. While the individual ground measurements were not equal to the TROPOMI profile, the TROPOMI profile is approximately the average of the profiles of measurements made within the hour of TROPOMI overpass. / M.S. / This thesis analyzes the effectiveness of spatially averaged Multi-AXis Differential Optical Absorption Spectroscopy (MAX-DOAS) measurements at regular intervals of angles offset from due North on an hourly basis to validate satellite based DOAS measurements. MAX-DOAS Measurements taken relative to the position of the sun in Blacksburg, Virginia, a low NO₂ location, between November 2021 and April 2022 to determine the effectiveness of a generalized measuring strategy for satellite validation in low pollution environments. An evenly distributed set of measurements were averaged every hour and compared to measurements taken in the direction of the sun, also averaged every hour, to determine if the variability of NO₂ around Blacksburg is high enough to require a generalized sampling strategy, or if the NO₂ distribution is homogeneous enough to be accurately validated with Direct Sun measurements only.. Comparisons of the difference in average measurement from both measuring strategies, as well as the distribution of standard deviations of hourly measurements suggests that the NO₂ distribution around Blacksburg is low. In order to test the effectiveness of this sampling strategy in a higher pollution location with many sources and sinks of NO₂, the data from the LOTOS-EUROS high resolution (1kmx1km) chemical transport model run by the Royal Dutch Meteorological Institute for the TROLIX'19 Field Campaign was used to simulate vertical distributions of NO₂ and vertical column densities of measurements taken during the field campaign. The LOTOS-EUROS model was used to simulate vertical distributions of NO₂ as well as Vertical Column Densities based on real MAX-DOAS measurements as well as viewing geometry seen by the TROPOspheric Monitoring Instrument (TROPOMI) satellite-based instrument. While the individual ground measurements were not equal to the vertical distribution seen by TROPOMI, the TROPOMI vertical distribution is approximately the average of the vertical distributions of measurements made within an hour of TROPOMI passing over Rotterdam.
203

Comparative particulate sampling methods

Twitty, Frank Butler 28 July 2010 (has links)
At present, there are several methods of determining the mass concentration of suspended particulate matter in ambient air. Most of these methods, including the EPA reference method, require manual filtering and weighing of the collected sample. This is both costly and time-consuming and is subject to a considerable amount of human error. Another serious drawback to most of these procedures is the long (24 hour) sampling times required, and the resultant insensitivity to fluctuations due to the long averaging intervals. The piezoelectric microbalance and high volume sampler techniques were employed in this investigation to measure the mass of ambient undifferentiated particulate matter. The results were compared and conclusions drawn concerning the feasibility of using the piezoelectric microbalance along with or in place of the high volume sampler for measurement of ambient particulate matter. It was found that the piezoelectric microbalance can be used in place of or along with the high volume sampler but consideration must be given to the fact that the piezoelectric microbalance will give lower average particulate concentration readings depending on the particle size distribution of the ambient particulate matter being sampled. / Master of Science
204

Tamanho, forma de parcelas e suficiência amostral para avaliação e monitoramento do componente vegetal de ecossistemas em restauração com cinco anos de idade no estado de São Paulo / Size, shape of plots and sampling sufficiency for assessment and monitoring of the 5 aged plant component of ecosystem restoration in the state of São Paulo

Fragoso, Ariadina Callegari Ferrari 05 December 2014 (has links)
A avaliação e o monitoramento são etapas fundamentais para testar teorias e metodologias usadas na restauração ecológica, além de indicar ações corretivas que podem ser aplicadas para garantir o sucesso dos projetos. No entanto, para que estas atividades sejam realmente efetivas e proporcionem resultados seguros é necessário o uso de ferramentas estatísticas em seu planejamento e aplicação para que os dados obtidos sejam precisos e seguros. O objetivo deste estudo é testar o tamanho, a forma de parcelas e a suficiência amostral para avaliar e monitorar áreas em processo de restauração no Bioma Mata Atlântica com idade aproximada de cinco anos. Foram amostradas três áreas que inseridas na Floresta Estacional Semidecidual com cerca de cinco anos submetidas ao plantio total de mudas e inseridas em paisagens fragmentadas. Para amostragem foram alocadas sistematicamente 10 parcelas em SOS (Itu) e ARA (Batatais) e 7 parcelas em A_Q (Batatais) com dimensões de 12x20 m2. Os indivíduos amostrados receberam uma placa numerada, e foram registradas as medidas de CAP de todos os ramos se ao menos um deles tiver CAP >= 10 cm. Para caracterização dos locais a regeneração natural foi amostrada em parcelas de 2x2 m2 incluindo indivíduos com altura maior ou igual a 0,5 m. As parcelas foram subdivididas em 8 tamanhos diferentes, para simular o tamanho e forma de parcela ideal. Para o cálculo de tamanho de parcelas foi utilizado o método de máxima curvatura e a suficiência amostral foi determinada a partir da variabilidade do indicador, do erro e precisão predeterminados a 20%. O tamanho ideal da parcela selecionado para a maioria dos indicadores amostrados foi 90 m2 (9x10 m). A comparação do coeficiente de variação e do erro amostral entre parcelas com mesma área e diferentes dimensões não foi conclusiva a respeito da melhor forma da unidade amostral que se deve utilizar nestas áreas. Os indicadores e verificadores que apresentaram menores valores de CV e erro amostral e são recomendados para estudo de áreas em restauração são número de indivíduos, numero de espécies, número de espécies do grupo de plantio diversidade, número de espécies do grupo pioneiras e número de espécies zoocoóricas. A suficiência amostral variou amplamente para cada indicador entre as áreas, mostrando que a variabilidade de cada local influencia diretamente o cálculo do número de parcelas ideais para amostragem. Para os indicadores selecionados nas áreas estudadas recomenda-se que seja utilizada intensidade amostral de 14,65% da área estudada ou oito parcelas de 9x10m. Apesar das dificuldades encontradas, os estudos de amostragem em restauração florestal são necessários para viabilizar o estabelecimento de um protocolo de monitoramento que tenha bases estatísticas e garanta que os dados obtidos sejam seguros e precisos, facilitando, ainda, a comparação e extrapolação de dados. / The evaluation and monitoring are key steps to test theories and methodologies used in ecological restoration and indicates corrective actions that can be taken to ensure the success of the projects. The evaluation and monitoring are key steps to test theories and methodologies used in ecological restoration and indicates corrective actions that can be taken to ensure the success of the projects. However, for these activities to be really effective and provide reliable results is necessary to use statistical tools in their planning and implementation so that the obtained data is accurate and secure. The aim of this study is to test the size, shape of plots and sampling sufficiency to assess and monitor areas in restoration process in the Atlantic Forest biome aged approximately five years. Three areas that were sampled inserted in semideciduous forest with about five years subject to the total planting seedlings and inserted in fragmented landscapes. For sampling were systematically allocated 10 plots in SOS (Itu) and ARA (Batatais) and 7 plots in A_Q (Batatais) with dimensions of 12x20 m2 including four tree rows with 10 individuals per row. Individuals were tagged and measured in diameter and breast height (CAP) of all branches were registered, if at least one of them had CAP >= 10 cm. To characterize the local natural regeneration was sampled in 2x2 m2 plots including individuals with greater height not exceeding 0.5 m. The plots were divided into 8 different sizes to simulate the size and shape of optimal share. For the plot size was used for calculating the maximum bending method and sample sufficiency was determined from the indicator variable, predetermined accuracy of error of 20%. The optimum size of the portion selected to most 90 m2 was sampled indicators (9x10 m). The comparison of the coefficient of variation and the sampling error between fields with the same area and different dimensions was inconclusive as to the best way of sampling units that must be used in these areas. The indicators and verifiers had lower CV values and sampling error and are recommended for study areas in restoration are number of individuals, species number, number of species planting group diversity, number of pioneering group species and number of species zoocoóricas. The sample sufficiency varied widely for each indicator between the areas, showing that the variability of each site directly influences the calculation of the number of plots ideal for sampling. For indicators selected in the study area is recommended to be used sampling intensity of 14.65% of the study area or eight 9x10m plots. Despite the difficulties encountered, in forest restoration sampling studies are needed to facilitate the establishment of a monitoring protocol that has statistical bases and ensure that data is safe and accurate, facilitating also the comparison and extrapolation of data.
205

Audit sampling: A qualitative study on the role of statistical and non-statistical sampling approaches on audit practices in Sweden

Ayam, Rufus Tekoh January 2011 (has links)
PURPOSE: The two approaches to audit sampling; statistical and nonstatistical have been examined in this study. The overall purpose of the study is to explore the current extent at which statistical and nonstatistical sampling approaches are utilized by independent auditors during auditing practices. Moreover, the study also seeks to achieve two additional purposes; the first is to find out whether auditors utilize different sampling techniques when auditing SME´s (Small and Medium-Sized Enterprise) and big companies and the second is to find out some common selection methods that are used by auditors for selecting statistical or nonstatistical audit samples during audit sampling practices.   METHOD: The population that has been investigated consists of professional auditors residing in Umeå-Sweden.Data for the study was collected by conducting semi-structured interviews and convenient sampling; a non-probability sampling technique was used for respondent’s selection. An interviewed guide was sent to respondents in advance with the objective of giving them the opportunity to have both mental and psychological preparations prior to each interview scheduled date. The semi-structured interview technique was adopted because it was a suitable approach to extract valuable information and in-depth explanations from auditors about the current extent of the use of statistical audit sampling and nonstatistical audit sampling during auditing practices. Ultimately, the selected respondents actively participated in which they thoroughly expressed their views and experiences about audit sampling, statistical audit sampling, and nonstatistical audit sampling.   RESULTS: Statistical audit sampling and nonstatistical audit sampling were found to be used most often by auditors when auditing the financial statements of big companies compare to SME´s where nonstatistical audit sampling is most often used. Therefore, both statistical and nonstatistical samplings are in dominant utilization by auditors in Sweden. Audit samples are selected through random selection method and systematic selection methods when using statistical audit sampling and for nonstatistical audit sampling; items are selected by the use of professional judgment. However, auditors in Sweden are more inclined with the use of random selection method for statistical audit sampling and their professional judgment for nonstatistical audit sampling. The main reasons for the auditors using both statistical audit sampling and nonstatistical audit sampling are to minimize risks and to guarantee high quality audit. The conclusion of the study was that auditors in Sweden use both statistical and nonstatistical audit sampling techniques when auditing big companies, use nonstatistical audit sampling when auditing SME´s, select samples using random selection method and systematic selection method for statistical audit sampling and for nonstatistical audit sampling, items are selected within the parameters of their professional judgment.
206

Comparisons of methods for generating conditional Poisson samples and Sampford samples

Grafström, Anton January 2005 (has links)
Methods for conditional Poisson sampling (CP-sampling) and Sampford sampling are compared and the focus is on the efficiency of the methods. The efficiency is investigated by simulation in different sampling situations. It was of interest to compare methods since new methods for both CP-sampling and Sampford sampling were introduced by Bondesson, Traat & Lundqvist in 2004. The new methods are acceptance rejection methods that use the efficient Pareto sampling method. They are found to be very efficient and useful in all situations. The list sequential methods for both CP-sampling and Sampford sampling are other methods that are found to be efficient, especially if many samples are to be generated.
207

Determination of atmospheric carbonyls and carboxylic acids by denudersampling, gradient elution and capillary electrophoresis

Chan, King-yee., 陳景怡. January 2003 (has links)
published_or_final_version / abstract / toc / Chemistry / Master / Master of Philosophy
208

Tamanho, forma de parcelas e suficiência amostral para avaliação e monitoramento do componente vegetal de ecossistemas em restauração com cinco anos de idade no estado de São Paulo / Size, shape of plots and sampling sufficiency for assessment and monitoring of the 5 aged plant component of ecosystem restoration in the state of São Paulo

Ariadina Callegari Ferrari Fragoso 05 December 2014 (has links)
A avaliação e o monitoramento são etapas fundamentais para testar teorias e metodologias usadas na restauração ecológica, além de indicar ações corretivas que podem ser aplicadas para garantir o sucesso dos projetos. No entanto, para que estas atividades sejam realmente efetivas e proporcionem resultados seguros é necessário o uso de ferramentas estatísticas em seu planejamento e aplicação para que os dados obtidos sejam precisos e seguros. O objetivo deste estudo é testar o tamanho, a forma de parcelas e a suficiência amostral para avaliar e monitorar áreas em processo de restauração no Bioma Mata Atlântica com idade aproximada de cinco anos. Foram amostradas três áreas que inseridas na Floresta Estacional Semidecidual com cerca de cinco anos submetidas ao plantio total de mudas e inseridas em paisagens fragmentadas. Para amostragem foram alocadas sistematicamente 10 parcelas em SOS (Itu) e ARA (Batatais) e 7 parcelas em A_Q (Batatais) com dimensões de 12x20 m2. Os indivíduos amostrados receberam uma placa numerada, e foram registradas as medidas de CAP de todos os ramos se ao menos um deles tiver CAP >= 10 cm. Para caracterização dos locais a regeneração natural foi amostrada em parcelas de 2x2 m2 incluindo indivíduos com altura maior ou igual a 0,5 m. As parcelas foram subdivididas em 8 tamanhos diferentes, para simular o tamanho e forma de parcela ideal. Para o cálculo de tamanho de parcelas foi utilizado o método de máxima curvatura e a suficiência amostral foi determinada a partir da variabilidade do indicador, do erro e precisão predeterminados a 20%. O tamanho ideal da parcela selecionado para a maioria dos indicadores amostrados foi 90 m2 (9x10 m). A comparação do coeficiente de variação e do erro amostral entre parcelas com mesma área e diferentes dimensões não foi conclusiva a respeito da melhor forma da unidade amostral que se deve utilizar nestas áreas. Os indicadores e verificadores que apresentaram menores valores de CV e erro amostral e são recomendados para estudo de áreas em restauração são número de indivíduos, numero de espécies, número de espécies do grupo de plantio diversidade, número de espécies do grupo pioneiras e número de espécies zoocoóricas. A suficiência amostral variou amplamente para cada indicador entre as áreas, mostrando que a variabilidade de cada local influencia diretamente o cálculo do número de parcelas ideais para amostragem. Para os indicadores selecionados nas áreas estudadas recomenda-se que seja utilizada intensidade amostral de 14,65% da área estudada ou oito parcelas de 9x10m. Apesar das dificuldades encontradas, os estudos de amostragem em restauração florestal são necessários para viabilizar o estabelecimento de um protocolo de monitoramento que tenha bases estatísticas e garanta que os dados obtidos sejam seguros e precisos, facilitando, ainda, a comparação e extrapolação de dados. / The evaluation and monitoring are key steps to test theories and methodologies used in ecological restoration and indicates corrective actions that can be taken to ensure the success of the projects. The evaluation and monitoring are key steps to test theories and methodologies used in ecological restoration and indicates corrective actions that can be taken to ensure the success of the projects. However, for these activities to be really effective and provide reliable results is necessary to use statistical tools in their planning and implementation so that the obtained data is accurate and secure. The aim of this study is to test the size, shape of plots and sampling sufficiency to assess and monitor areas in restoration process in the Atlantic Forest biome aged approximately five years. Three areas that were sampled inserted in semideciduous forest with about five years subject to the total planting seedlings and inserted in fragmented landscapes. For sampling were systematically allocated 10 plots in SOS (Itu) and ARA (Batatais) and 7 plots in A_Q (Batatais) with dimensions of 12x20 m2 including four tree rows with 10 individuals per row. Individuals were tagged and measured in diameter and breast height (CAP) of all branches were registered, if at least one of them had CAP >= 10 cm. To characterize the local natural regeneration was sampled in 2x2 m2 plots including individuals with greater height not exceeding 0.5 m. The plots were divided into 8 different sizes to simulate the size and shape of optimal share. For the plot size was used for calculating the maximum bending method and sample sufficiency was determined from the indicator variable, predetermined accuracy of error of 20%. The optimum size of the portion selected to most 90 m2 was sampled indicators (9x10 m). The comparison of the coefficient of variation and the sampling error between fields with the same area and different dimensions was inconclusive as to the best way of sampling units that must be used in these areas. The indicators and verifiers had lower CV values and sampling error and are recommended for study areas in restoration are number of individuals, species number, number of species planting group diversity, number of pioneering group species and number of species zoocoóricas. The sample sufficiency varied widely for each indicator between the areas, showing that the variability of each site directly influences the calculation of the number of plots ideal for sampling. For indicators selected in the study area is recommended to be used sampling intensity of 14.65% of the study area or eight 9x10m plots. Despite the difficulties encountered, in forest restoration sampling studies are needed to facilitate the establishment of a monitoring protocol that has statistical bases and ensure that data is safe and accurate, facilitating also the comparison and extrapolation of data.
209

The functional significance of grooming behaviour in higher primates : the case of free-living chimpanzees

Slater, Kerry 17 October 2009 (has links)
As a contribution to the existing knowledge of grooming in primates five and a half years of grooming data were examined from a group of free-living chimpanzees (Pan troglodytes) in the Budongo Forest, Uganda, to investigate various functional significances of grooming behaviour within the context of social reinforcement. The fission–fusion social structure of chimpanzees results in group members not moving around as a single unit, but forming temporary units as the need arises. This reduces opportunities for individuals to groom others and therefore, based on time and association constraints alone, grooming was as expected found to be unevenly distributed among group members. Grooming patterns found among this group of chimpanzees were comparable to those observed in other free-living populations with variations possibly being attributed to resource base, population numbers and differences in age-sex class composition. One of the suggested social benefits of grooming is that it is used to enhance reproductive success, either by allowing males to enhance their proximity to oestrous females, or by influencing female choice through the development of affiliative relationships with males. Grooming was found to increase between males and females, whilst females displayed sexual receptivity through the presence of anogenital swellings and grooming may be a strategy used by males to increase their access to copulation opportunities, whereas females may use grooming to increase protection from harassment by less preferred males during swollen periods and also increase the likelihood of copulation with preferred partners. Based on the availability of oestrous females, copulations between males and adult females occurred significantly less frequently than expected, whereas copulations between males and subadult females occurred significantly more frequently than expected. Overall a positive correlation was found between grooming of females by males and frequency of copulations. Due to concerns regarding the validity of different sampling methods, scan-focal and ad libitum sampling methods were compared to establish if results from different sampling methods were similar. Results from the scan-focal and ad libitum sampling methods had very few discrepancies, and it is suggested that ad libitum sampling methods which record behaviour types whenever they occur, may be more beneficial for species which don’t move around as a single unit and live in environments where visibility is reduced, therefore increasing the possibility of recording individuals or behaviours that are observed infrequently. Scan-focal sampling may be more beneficial in studying species which move around together in habitats which are conducive to greater visibility, therefore allowing all or most group members to be observed simultaneously. / Thesis (DPhil)--University of Pretoria, 2009. / Zoology and Entomology / unrestricted
210

Extending Ranked Sampling in Inferential Procedures

Matthews, Michael J. 15 August 2017 (has links)
No description available.

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