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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

Análisis de estabilidad de talud en areniscas mediante el método empírico Hazard índex, cinemático y equilibrio límite en la carretera Tarapoto – Yurimaguas / Analysis of slope stability in sandstones using the empirical Hazard index, kinematic and boundary balancemethod on the Tarapoto - Yurimaguas road

Chávez De la Cruz, Raysa Milagros 15 July 2020 (has links)
La estabilidad de las pendientes rocosas se considera crucial para la seguridad pública en las carreteras, así como también para la seguridad del personal y los equipos que trabajan en los cortes de roca. La inestabilidad y fallas en taludes rocosos se producen debido a muchos factores, como la geometría, las discontinuidades geológicas, el material del talud, y las condiciones climáticas severas. Así también como las cargas externas, las fuertes precipitaciones y la sismicidad que podrían jugar un papel importante en la falla. En esta tesis se desarrolla el método cinemático y el método empírico de “Índice de Riesgo” (tomado del inglés “Hazard Índex”) para la evaluación de la estabilidad del talud en la carretera Tarapoto- Yurimaguas, donde el talud corresponde a una roca residual tipo arenisca de baja resistencia, con alta precipitación por ser zona tropical y ubicada dentro de una zona sísmica. Se identifican los posibles tipos de falla mediante el análisis cinemático basado en la dirección del rumbo y buzamiento de las discontinuidades, se analiza las fallas encontradas con respecto al factor sísmico, y la condición de la estabilidad con el método empírico “Hazard Index” con respecto al factor de precipitación para así identificar la condición de estabilidad y mostrar el resultado. La tesis destaca algunas limitaciones de los métodos utilizados. / The stability of rocky slopes is considered crucial for public safety on the roads, as well as for the safety of personnel and teams working on rock cuts. Rock slope instability and failure occur due to many factors such as geometry, geological discontinuities, slope material, and severe weather conditions. As well as external loads, heavy precipitation, and seismicity that could play an important role in the failure. In this thesis we develop the kinematic method and the empirical method of "hazard Index" for evaluating the stability of the slope on the Tarapoto-Yurimaguas road, where the slope corresponds to a residual rock Low resistance sandstone type, with high precipitation as it is a tropical zone and located within a seismic zone. Possible types of failure are identified through kinematic analysis based on the direction of heading and dip of the discontinuities, the failures found are analyzed with respect to the seismic factor, and the condition of stability with the empirical method "Hazard Index" with respect to to the precipitation factor to identify the stability condition and show the result. The thesis highlights some limitations of the methods used. / Tesis
2

Integrating Chemical Hazard Assessment into the Design of Inherently Safer Processes

Lu, Yuan 2011 December 1900 (has links)
Reactive hazard associated with chemicals is a major safety issue in process industries. This kind of hazard has caused the occurrence of many accidents, leading to fatalities, injuries, property damage and environment pollution. Reactive hazards can be eliminated or minimized by applying Inherently Safer Design (ISD) principles such as "substitute" or "moderate" strategies. However, ISD would not be a feasible option for industry without an efficient methodology for chemical hazard assessment, which provides the technical basis for applying ISD during process design. In this research, a systematic chemical hazard assessment methodology was developed for assisting the implementation of ISD in the design of inherently safer process. This methodology incorporates the selection of safer chemicals and determination of safer process conditions, which correspond to "substitute" and "moderate" strategies in ISD. The application of this methodology in conjunction with ISD technique can effectively save the time and investment spent on the process design. As part of selecting safer chemicals, prediction models were developed for predicting hazardous properties of reactive chemicals. Also, a hazard index was adopted to rate chemicals according to reactive hazards. By combining the prediction models with the hazard index, this research can provide important information on how to select safer chemicals for the processes, which makes the process chemistry inherently safer. As part of determining safer process conditions, the incompatibility of Methyl Ethyl Ketone Peroxide (MEKPO) with iron oxide was investigated. It was found that iron oxide at low levels has no impact on the reactive hazards of MEKPO as well as the operational safety. However, when iron oxide is beyond 0.3 wt%, it starts to change the kinetics of MEKPO runaway reaction and even the reaction mechanism. As a result, with the presence of a certain level of iron oxide (> 0.3 wt%), iron oxide can intensify the reactive hazards of MEKPO and impose higher risk to process operations. The investigation results can help to determine appropriate materials for fabricating process equipment and safer process conditions.
3

Evaluation and development of predictive streambank erosion curves for northeast Kansas using Rosgen's "bancs" methodology

Sass, Christopher K. January 1900 (has links)
Doctor of Philosophy / Environmental Design and Planning Program / Timothy D. Keane / The original purpose of this investigation was to develop streambank erosion prediction curves for Northeast Kansas streams. Rosgen's (2001, 2006) methods were employed and eighteen study banks were measured and monitored over a four-year period, summer 2007 through summer 2010. At each study bank, a toe pin and two to three bank pins were set at a recorded longitudinal profile station of the stream. Vertical and horizontal measures from the toe pin to the bank face were taken each summer, 2007 as the baseline measure and 2008 - 2010 as bank change years. Bank profiles were overlaid to gain insight into bank area lost or gained due to erosional or depositional processes. A Bank Erosion Hazard Index (BEHI) and Near Bank Stress (NBS) combination rating was assessed and calculated for each study bank during the initial survey of 2007. The streambanks experienced varied erosion rates for similar BEHI/NBS combinations producing R2 values from 0.43 as the High/Very High BEHI rating and 0.80 as the Moderate BEHI rating. In addition, Moderate BEHI ratings provided higher erosion rates than the High/Very High BEHI rating and curves intersected at lower NBS ratings, suggesting a discrepancy in the fit of the model used in the Northeast Kansas region and conditions. In this light, modification of the BEHI model was evaluated and variables were assessed in the model for additional influence exerted in the Northeast Kansas region. Vegetation seemed to provide the most influence to bank resistance and was more closely evaluated. Banks with and without woody riparian vegetation were then plotted against BEHI and NBS values, as banks lacking woody vegetation eroded at higher rates. This study's findings can allow us to calibrate the BEHI model according to woody vegetation occurrence levels along streambanks in the Black Vermillion watershed. Modifications regarding vegetation occurrence of the BEHI model was completed and the results of these modifications generated R2 values of 0.78 for High/Very High BEHI and 0.82 for Moderate BEHI ratings. High/Very High ratings provided higher predicted erosion rates than Moderate ratings, while the curve slopes did not intersect at lower NBS ratings.
4

Heavy metals in soils and edible tissues of Lepidium meyenii (maca) and health risk assessment in areas influenced by mining activity in the Central region of Peru

Orellana Mendoza, Edith, Cuadrado, Walter, Yallico, Luz, Zárate, Rosa, Quispe-Melgar, Harold Rusbelth, Limaymanta, Cesar H., Sarapura, Vicky, Bao-Cóndor, Diana 01 January 2021 (has links)
Heavy metal contamination of soil and agricultural products is an environmental problem, has an adverse effect on the quality of food crops, and is a danger to food security and public health. The concentration of arsenic (As), cadmium (Cd), lead (Pb), iron (Fe) and zinc (Zn) in surface soils and edible hypocotyls tissues of two ecotypes of Lepidium meyenii Walpers (maca) was evaluated in three districts of the Junín province, Peru. In addition, the risk to human health due to exposure to heavy metals from maca consumption was evaluated. Soil samples and maca hypocotyls were collected in areas influenced by mining and metallurgical activity. The mean concentration of Cd (0.32 ± 0.23 mg/kg) and Pb (0.20 ± 0.12 mg/kg) in maca samples exceeded the values established by the Food and Agriculture Organization and the World Health Organization. The bioconcentration factor was less than 1. The estimated daily intake of each metal was below the oral reference dose. The hazard quotient and hazard index were less than 1, it is unlikely to cause non-cancer adverse health outcome. The cancer risk for As and Cd was higher than the tolerable limit (1 × 10−6) in children and adults. In the district of Ondores, the cancer risk for As in children was higher than the acceptable limit (1 × 10−4). Residents of the Ondores district would be more exposed to As and Cd from consumption of maca hypocotyls. It is very important to carry out continuous monitoring of other toxic metals in different ecotypes of maca (red, black, yellow, purple, creamy white, pink) in order to evaluate the variation in the accumulation of heavy metals and the level of toxicity of each metal between ecotypes. / Revisón por pares
5

Quantifying the Hydraulic Performance of Treatment Wetlands

Wahl, Mark D. 03 September 2010 (has links)
No description available.
6

Índice de perigo para subsidiar a aplicação de lodo de esgoto em solo agrícola / Hazard index for the decision-making process of sludge agricultural use

Matta, Marcus Emmanuel Mamana da 12 August 2011 (has links)
A ampliação dos sistemas de tratamento de esgoto sanitário implica diretamente no aumento da geração de lodos de esgoto, que precisam ser adequadamente dispostos. Devido aos benefícios agronômicos, a incorporação de lodo de esgoto em solo agrícola tem sido, em diversos países, a forma mais sustentável para aproveitamento deste resíduo. A Resolução Conama 375 de 2006 normatiza essa prática no Brasil, e os critérios para a tomada de decisão quanto a ocorrência de poluentes químicos no lodo de esgoto se restringe a determinação de onze compostos inorgânicos, o que gera preocupação em relação a outros compostos presentes na matriz e que podem proporcionar riscos ao ecossistema e à saúde humana. Para complementar a avaliação de matrizes complexas como lodo de esgoto, efluentes, sedimentos, solos contaminados, se tem preconizado o uso de testes de toxicidade, os quais fornecem evidências do perigo da mistura como um todo. O objetivo da tese foi desenvolver um índice para avaliar a periculosidade de lodo de esgoto, utilizando ensaios ecotoxicológicos de curta duração e baixo custo, com objetivo de subsidiar decisões mais rápidas quanto a sua aplicação em solo agrícola. O Índice de Perigo de Lodo de Esgoto (IPLE) integrou os resultados de teste de ecotoxicidade com Vibrio fischeri, Daphnia similis e teste de inibição do alongamento de raiz e da germinação de sementes. A fórmula do IPLE desenvolvido foi: log natural de um somado ao número de testes positivos, multiplicado pela ecotoxicidade média obtida nos testes, convertidos em unidade tóxica. O IPLE foi calculado utilizando os dados publicados pela CETESB de caracterização química e ecotoxicológica de 28 amostras de lodo de esgoto coletadas em 7 Estações de Tratamento de Esgoto (ETE) do Estado de São Paulo. O IPLE foi testado pela avaliação do percentual de amostras não conformes por faixa de índice, considerando para tanto os limites de substância química estabelecidos em diferentes normas de uso agrícola de lodo. As amostras com IPLE acima de 2 (n=15) apresentaram maior frequência de não conformidade quando comparado com as amostras com índice abaixo de 2 (n=13). O IPLE parece ser um bom indicador preliminar do perigo de amostras de lodo de esgoto, sugerindo reprovação e aprovação precoce de seu uso agrícola e como instrumento para acompanhamento e gestão da qualidade do lodo e comunicação de perigo / The expansion of urban wastewater treatment plants increases the generation of sewage sludge, that must be properly disposed. Due to the agronomic benefits, the incorporation of sewage sludge on agricultural land has been in several countries, the most sustainable use of this waste. CONAMA Resolution 375 of 2006 regulates the practice in Brazil, and the criteria for chemical pollutants in the sewage sludge are based on the concentration of eleven inorganic compounds, which raises concern in relation to other compounds present in matrix that could provide risk to the ecosystem and human health. Ecotoxicology evaluation of complex samples as sewage sludge, wastewater, sediments, contaminated soils, has been often recommended to provide evidence of the whole mixture. The aim of this thesis was to develop a Sewage Sludge Hazard Index (SSHI) based on short term and low cost bioassays, to be a complementary tool for the decisionmaking process of sewage sludge application to agricultural land. SSHI integrated results from Vibrio fischeri, Daphnia similis and seed elongation/germination test. Sewage Sludge Hazard Index (SSHI) was calculated as the natural logarithm of one plus the number of positive toxic responses multiplied by the average of the toxic units obtained in each bioassay. The index was calculated using data generated by CETESB from chemical and ecotoxicological characterization of 28 samples collected in 7 different wastewater treatment plants (WWTP) of Sao Paulo State. SSHI was tested by assessing the percentage of samples non-compliances for indexranks, considering chemical thresholds of pollutants in sewage sludge from differents norms for agricultural use of sludge. All samples with SSHI above 2 (n = 15) had higher incidence of non-compliance then samples below 2 (n = 13). SSHI seems to be a good primary indicator of the hazard of sewage sludge samples, suggesting early approval or disapproval to agricultural use, also as a tool for monitoring and managing the quality of sludge, and for hazard communication
7

The relationship of mercury intake from food consumption and hair mercury level of Taiwan population

Chen, Yi-chun 04 September 2009 (has links)
Mercury is a naturally existing element. It could be transported into human body through food chain, and harm the central nervous system. This is the first study to analyze the concentrations of mercury in different kinds of food in Taiwan. The purpose of the study was to assess the mercury intake of total diet and the health risk. Moreover, the concentration of hair mercury was used to evaluate the body burden. The mercury concentrations in foods were determined by furnace-gold amalgation mercury analyzer. Nine kinds of foods, fish, nonfish seafood, meats, soybean products, eggs, dairy products, vegetables, fruits and cereals were included in the sample. A total of 118 food composites with 574 samples were collected from three largest cities in Taiwan during 2004 to 2006. Dietary information of 446 Taiwanese was collected by using semi-quantitative food frequency questionnaire. Meanwhile, both diet information and hair sample of 355 Taiwanese that were collected. The mean mercury concentrations of nine kinds of food were significantly different (p < 0.05), ranging from 0.5 to 82.9 ng/g wet wt. The mean mercury concentrations was highest in fish, and sequentially decreased in nonfish seafood, eggs, meats, soybean products, vegetables, cereals, dairy products and fruit. All the mean mercury concentrations of foods were below the standard limits of Department of Health in Taiwan, FAO/WHO and European Commission. The dietary mercury intakes for vegetarian, general population lived in the city, fishing village, outlying islands and fishing workers were 0.16, 0.89, 1.22, 1.66 and 3.50 £gg/kg/week, respectively. There were significant differences (p < 0.05) among the five groups mentioned above. The highest mercury intake was found in the fishing workers. However, the mean mercury intakes for those five groups were still within the PTWI safe limit suggested by FAO/WHO, corresponding to 3 to 76% of PTWI. Fishes were the major source of mercury intake among nine kinds of foods for Taiwan population, corresponding to 42 to 77% of mean mercury intake. Mean concentrations of hair mercury of vegetarian, general population lived in the city, fishing village, outlying islands and fishing workers were 0.5¡Ó0.5¡B2.4¡Ó1.8¡B4.4¡Ó3.3¡B4.6¡Ó7.4 and 9.1¡Ó13.6 mg/kg respectively. Significant differences were found among the five groups (p < 0.05). The highest mercury concentration of hair was also found in the fishing workers corresponding to the result of diet intake. 2.3% of Taiwan population with hair mercury higher than the toxic level, 20 mg/kg, proposed by FAO/WHO. They were all fishing workers and outlying islanders. Multiple regression analysis revealed that the concentrations of hair mercury were significantly correlated with the frequency of fish consumption for the population lived in the city, fishing village, and fishing workers. The mercury concentrations of hair was also related with the age of people and the fish species. Aspects of nutrient balance and the health risk, consumption of small and medium-sized fish with mercury lower than 50 ng/g was recommended. No more than 150 g per week was acceptable for the people like to eat large-sized predatory fishes.
8

Obsah rtuti v rybách z údolní nádrže Jordán v Táboře. / The Mercury Content in Fish from the Jordán Resesvoir in Tábor.

KUBECOVÁ, Jana January 2008 (has links)
The aim of those study was to find out an up-to date content of mercury in the tissues of fish in the dam reservoir Jordan in Tabor. To compare particular fish according to their species, age and dietary strategy and their capability to accumulate mercury. The distribution and the mutual rates of total content of mercury in particular tissues of carnivorous and non-carnivorous species of fish were determined (muscle, liver, kidneys). Dedicated atomic absorption spectrophotometer AMA 254 was used to determine the total content of mercury. The results show that exceeding the former hygienic limit 0.1 mg.kg-1 w. w. in the muscle of non-carnivorous fish with almost all samples. It was the low-age carnivorous species of fish was probably the cause that the hygienic limit (0,5 mg.kg-1 w. w.) was exceeded only rarely (in the muscle a five-year-old asp, Aspius aspius, 0,888 {$\pm$} 0,041 mg.kg-1 w. w.). The pond Kosin located above the dam reservoir Jordan was exploitation as a comparative locality. The average content of mercury in the muscle of selected indicator species of fish in the reservoir Jordan - bream large (Abramis brama) at the age of 5 years - it was 0,241 {$\pm$} 0,080 mg.kg-1 w. w., whereas from comparative locality, from the pond Kosin, for the same species and age of fish it was only 0,045 {$\pm$} 0,008 mg.kg-1 w.w., i.e. more than five times more of the content in comparison with an unweighted locality. The realized results also show that the burden of the fish with mercury for a common consumer does not exceed neither the {\clqq}hazard index`` (HI) nor the toxicological limit ( the maximum recommended ration a week from the food is 1,6 {$\mu$}g MeHg per 1 kg of body weight according) to the WHO. However, with more intensive consumption of mainly carnivorous fish from the reservoir Jordan, e.g. of the sport fishermen´s family members, it could cause risk from this consumption ( i.e. HI > 1). Further work should be aimed at monitoring of the content of mercury in the tissues of mainly predators of higher age category.
9

Índice de perigo para subsidiar a aplicação de lodo de esgoto em solo agrícola / Hazard index for the decision-making process of sludge agricultural use

Marcus Emmanuel Mamana da Matta 12 August 2011 (has links)
A ampliação dos sistemas de tratamento de esgoto sanitário implica diretamente no aumento da geração de lodos de esgoto, que precisam ser adequadamente dispostos. Devido aos benefícios agronômicos, a incorporação de lodo de esgoto em solo agrícola tem sido, em diversos países, a forma mais sustentável para aproveitamento deste resíduo. A Resolução Conama 375 de 2006 normatiza essa prática no Brasil, e os critérios para a tomada de decisão quanto a ocorrência de poluentes químicos no lodo de esgoto se restringe a determinação de onze compostos inorgânicos, o que gera preocupação em relação a outros compostos presentes na matriz e que podem proporcionar riscos ao ecossistema e à saúde humana. Para complementar a avaliação de matrizes complexas como lodo de esgoto, efluentes, sedimentos, solos contaminados, se tem preconizado o uso de testes de toxicidade, os quais fornecem evidências do perigo da mistura como um todo. O objetivo da tese foi desenvolver um índice para avaliar a periculosidade de lodo de esgoto, utilizando ensaios ecotoxicológicos de curta duração e baixo custo, com objetivo de subsidiar decisões mais rápidas quanto a sua aplicação em solo agrícola. O Índice de Perigo de Lodo de Esgoto (IPLE) integrou os resultados de teste de ecotoxicidade com Vibrio fischeri, Daphnia similis e teste de inibição do alongamento de raiz e da germinação de sementes. A fórmula do IPLE desenvolvido foi: log natural de um somado ao número de testes positivos, multiplicado pela ecotoxicidade média obtida nos testes, convertidos em unidade tóxica. O IPLE foi calculado utilizando os dados publicados pela CETESB de caracterização química e ecotoxicológica de 28 amostras de lodo de esgoto coletadas em 7 Estações de Tratamento de Esgoto (ETE) do Estado de São Paulo. O IPLE foi testado pela avaliação do percentual de amostras não conformes por faixa de índice, considerando para tanto os limites de substância química estabelecidos em diferentes normas de uso agrícola de lodo. As amostras com IPLE acima de 2 (n=15) apresentaram maior frequência de não conformidade quando comparado com as amostras com índice abaixo de 2 (n=13). O IPLE parece ser um bom indicador preliminar do perigo de amostras de lodo de esgoto, sugerindo reprovação e aprovação precoce de seu uso agrícola e como instrumento para acompanhamento e gestão da qualidade do lodo e comunicação de perigo / The expansion of urban wastewater treatment plants increases the generation of sewage sludge, that must be properly disposed. Due to the agronomic benefits, the incorporation of sewage sludge on agricultural land has been in several countries, the most sustainable use of this waste. CONAMA Resolution 375 of 2006 regulates the practice in Brazil, and the criteria for chemical pollutants in the sewage sludge are based on the concentration of eleven inorganic compounds, which raises concern in relation to other compounds present in matrix that could provide risk to the ecosystem and human health. Ecotoxicology evaluation of complex samples as sewage sludge, wastewater, sediments, contaminated soils, has been often recommended to provide evidence of the whole mixture. The aim of this thesis was to develop a Sewage Sludge Hazard Index (SSHI) based on short term and low cost bioassays, to be a complementary tool for the decisionmaking process of sewage sludge application to agricultural land. SSHI integrated results from Vibrio fischeri, Daphnia similis and seed elongation/germination test. Sewage Sludge Hazard Index (SSHI) was calculated as the natural logarithm of one plus the number of positive toxic responses multiplied by the average of the toxic units obtained in each bioassay. The index was calculated using data generated by CETESB from chemical and ecotoxicological characterization of 28 samples collected in 7 different wastewater treatment plants (WWTP) of Sao Paulo State. SSHI was tested by assessing the percentage of samples non-compliances for indexranks, considering chemical thresholds of pollutants in sewage sludge from differents norms for agricultural use of sludge. All samples with SSHI above 2 (n = 15) had higher incidence of non-compliance then samples below 2 (n = 13). SSHI seems to be a good primary indicator of the hazard of sewage sludge samples, suggesting early approval or disapproval to agricultural use, also as a tool for monitoring and managing the quality of sludge, and for hazard communication
10

Optimization of Parameters Used in Predictive Models for Respirator Cartridge Service Life for Toxic Organic Vapors

Janvier, Florence 08 1900 (has links)
No description available.

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