• Refine Query
  • Source
  • Publication year
  • to
  • Language
  • 3
  • 2
  • Tagged with
  • 5
  • 2
  • 2
  • 2
  • 2
  • 2
  • 2
  • 1
  • 1
  • 1
  • 1
  • 1
  • 1
  • 1
  • 1
  • 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 dynamic model of ammonia production within grow-finish swine barns

Cortus, Erin Lesley 20 December 2006 (has links)
Ammonia is a nuisance gas in many swine barns. The overall objective of this research project was to model ammonia formation and transmission processes in a grower-finisher swine barn, by first modelling the ammonia production and emission from urine puddles on the floor surface and the ammonia emission from the slurry pit, and then incorporating these emission rates in a dynamic model that separates the room and slurry pit headspace as two separate, but linked, control volumes. A series of studies were conducted to gather more information about the processes affecting the ammonia emission rate from the floor surface and the slurry that were later included in the overall room model developed. The model was then used to investigate ammonia reducing techniques and technologies based on the understanding of ammonia production and transmission incorporated in the model. The first step in modelling the ammonia emission rate from the floor surface was to determine the frequency of urinations by grower-finisher pigs. Male and female pigs were observed three times during their finishing phase to determine their urination frequency over the course of a day. The average measured urination frequency was 0.62 ± 0.11 urinations pig-1 h-1. A sinusoidal dromedary model was developed to describe the daily variation in urination frequency for male and female pigs between 51 and 78 kg.<p>In order for the deposited urinations on the floor surface to emit ammonia, the urea in the urine must first be converted to ammonia and the urease enzyme catalyzes this reaction. Two methods, a fixed-time-point method using the indophenol assay for ammonium-nitrogen analysis and a continuous method using the coupled enzyme assay, were used to measure enzyme activity at the floor surface of a swine barn and were compared to reported urease activity levels in the literature. Using both methods, there appeared to be an ammonia-producing site on the floor surface or within the collected samples that made accurate measurements of urease activity impossible. A review of urease activity levels in the literature from dairy-cow houses suggest that urease activity will be lowest following floor-cleaning and increase quickly following fouling of the floor surface. Based on the literature review, a urease activity value of 5 g NH¬3 m-2 h-1 was suggested for use in ammonia emission modelling of fouled floor surfaces in swine barns until better measurements become available. <p>The ammonia emissions from 36 simulated urine puddles under a variety of temperature, air velocity and initial urea concentration conditions were measured in a bench-scale experimental set-up. The measurements were used to calibrate and validate a dynamic, mechanistic, urine puddle emission model that considered the processes of evaporation, urea conversion, change in liquid concentration and puddle pH in order to simulate the amount of ammonia emitted from a puddle. Based on the correlation coefficients (R) between measured and simulated values for water volume (R=0.99), total ammoniacal nitrogen concentration (R=0.90), and total emission (R=1.00), along with five other statistical tests for each simulated variable, the model was deemed accurate. The measurements and simulations in this experiment showed the impact of puddle pH, urease activity and changing environmental conditions on the average puddle emission rate. Puddle emission continued to occur as long as there was still water.<p> The impact of different slurry compositions on the ammonia emission rate from slurry pits was tested in another bench-scale experimental set-up with emission chambers. The emission chamber concentration data collected was used to calibrate and validate a developed slurry emission model. The collected slurry samples were concentrated mixtures of urine and feces from individually-housed animals fed different diets. An empirical equation was developed to express the amount of total ammoniacal nitrogen in the slurry that was in the form of ammonia (f) and thus volatile to the surroundings. Based on the empirical equation, the simulated value of f was between 0.03 and 0.08 and did not show the sensitivity to slurry pH that has been reported by other authors. The slurry emission model with the empirical equation for f was validated with ammonia emission measurements from eight different slurry samples and simulated hourly concentration measurements within 17% and five-day average concentration measurements within 3%. Further testing was recommended to ensure the model developed for concentrated manure in this study was applicable to the more dilute slurry found in swine barns. <p>Using the information gained in the previous experiments, a mechanistic model describing the dynamic ammonia concentration in the room and in the slurry channel headspace of grower-finisher swine barns, as well as the ammonia emitted to the surrounding environment was developed. Data was collected from two grower-finisher rooms to use as input data to the model and for calibration and validation purposes. The model calibration procedure determined that the amount of emissions originating from the slurry for the simulated room conditions was generally less than 5% of the total room emissions, the air exchange rate through the slatted floor was approximately 4% of the room ventilation rate, and that in the first two weeks of animal activity in a room the urease activity at the floor surface will increase. The model was validated using separate data from that used in the calibration process. The model simulated hourly room concentration levels within 2.2 ppm and 3-day average concentration levels within 1.6 ppm. The model simulations were more accurate for one room that was fed a typical grower-finisher diet compared to another room fed an experimental diet with lower protein content and sugar-beet pulp inclusion. <p>The dynamic model was tested for its sensitivity to various input factors in terms of the floor emission rate, slurry emission rate and total emission rate. An interesting aspect of the simulations was that increases in either floor or surface emission rate were compensated to a small extent by decreases in the other emission rate as a result of a reduced concentration gradient for mass transfer. The ammonia emission rate from the floor was most sensitive to changes in urease activity, fouled floor area and puddle area. The ammonia emission rate from slurry was most sensitive to changes in slurry pH. The impact of input variables on the total emission rate was dependant on the simulated proportion of the total ammonia emission coming from either the floor surface or slurry channel. Three ammonia reduction techniques were tested and evaluated on their impact to the total ammonia emission rate from a room compared to a given set of control conditions.<p>The work in this thesis highlighted the importance of ammonia emission from the floor surface. The proportion of ammonia originating from the slurry and from the floor surface respectively will vary on the specific conditions within the barn, and will impact the effect of any ammonia mitigation technique that is investigated or used.
2

To Detect Water-Puddle On Driving Terrain From RGB Imagery Using Deep Learning Algorithms

Muske, Manideep Sai Yadav January 2021 (has links)
Background: With the emerging application of autonomous vehicles in the automotive industry, several efforts have been made for the complete adoption of autonomous vehicles. One of the several problems in creating autonomous technology is the detection of water puddles, which can cause damages to internal components and the vehicle to lose control. This thesis focuses on the detection of water puddles on-road and off-road conditions with the use of Deep Learning models. Objectives: The thesis focuses on finding suitable Deep Learning algorithms for detecting the water puddles, and then an experiment is performed with the chosen algorithms. The algorithms are then compared with each other based on the performance evaluation of the trained models. Methods: The study uses a literature review to find the appropriate Deep Learning algorithms to answer the first research question, followed by conducting an experiment to compare and evaluate the selected algorithms. Metrics used to compare the algorithm include accuracy, precision, recall, f1 score, training time, and detection speed. Results: The Literature Review indicated Faster R-CNN and SSD are suitable algorithms for object detection applications. The experimental results indicated that on the basis of accuracy, recall, and f1 score, the Faster R-CNN is a better performing algorithm. But on the basis of precision, training time, and detection speed, the SSD is a faster performing algorithm. Conclusions: After carefully analyzing the results, Faster R-CNN is preferred for its better performance due to the fact that in a real-life scenario which the thesis aims at, the models to correctly predict the water puddles is key
3

Ripples : The Interplay of Surface and Perception

Lu, Chi Jung January 2024 (has links)
This degree project, “Ripples,” explores the dynamic interplay of reflections in urban environments, focusing on how natural elements like puddles can transform the spatial experience and perception within these settings. Situated within the field of spatial design, this project emphasizes the potential of reflective surfaces to enrich urban spaces, making them more engaging and adaptable to environmental changes. The importance of “Ripples” lies in its ability to enhance urban livability and ecological awareness by integrating artfully designed reflective elements into everyday spaces. This approach addresses contemporary challenges such as increased rainfall and climate change, demonstrating how design can play a crucial role in urban sustainability and resilience. The project was conducted through a series of experiments and installations in diverse settings, including the Telefonplan tunnel and a controlled exhibition space at Konstfack. Using phenomenological methods alongside practical tools such as walking analyses and sensory observations, the project explored the effects of reflections caused by different materials and lighting conditions. Artistic interpretations through watercolour painting were also employed to conceptualize reflections abstractly, further enriching the study. Conclusions from “Ripples” suggest that thoughtful design interventions can significantly alter public engagement and enhance spatial perception, making everyday environments not only more aesthetically pleasing but also more responsive to human emotions and environmental factors. The project’s implications extend into future design practices, advocating for the integration of reflective surfaces in urban planning to foster environments that are not only functional but also inspirational, paving the way for a reflective future in urban design.
4

A conservação da diversidade de anuros no cerrado brasileiro

Lima, Luciana Signorelli Faria 28 July 2014 (has links)
Submitted by Jaqueline Silva (jtas29@gmail.com) on 2014-09-04T21:36:39Z No. of bitstreams: 2 Luciano Signorelli Faria Lima.pdf: 6489666 bytes, checksum: ffffa86e79bc4373bbb31a31eac21136 (MD5) license_rdf: 23148 bytes, checksum: 9da0b6dfac957114c6a7714714b86306 (MD5) / Made available in DSpace on 2014-09-04T21:36:39Z (GMT). No. of bitstreams: 2 Luciano Signorelli Faria Lima.pdf: 6489666 bytes, checksum: ffffa86e79bc4373bbb31a31eac21136 (MD5) license_rdf: 23148 bytes, checksum: 9da0b6dfac957114c6a7714714b86306 (MD5) Previous issue date: 2014-07-28 / Land use activities have been frequently transforming broad native areas into pastures or plantations. This process turned out to be a global problem and is known as one major responsible for declinesin various taxonomical groups. Frogs are one of the most threated groups among vertebrates, from which species with aquatic larvae are more susceptible. Such populations follow metacommunity dynamics and can be structured in function of combined processes, such as patch dynamics, species ordination dynamics, mass effect and neutral dynamics. Nevertheless, the lack of knowledge with respect to anuran species occupation and richness patterns in local and regional scale poses as a threat to their conservation. The aim of my work is to provide relevant information to the conservation of anurans in the Brazilian Cerrado. I investigated regional and local scale patterns and identified factors related to richness and occupation of anuran species that breed in Cerrado ponds. For that, I have collected data in the state of Goiás, which is the only Brazilian state totally inserted in the Cerrado biome and that follows that same tendency of habitat loss as the whole biome (due to agriculture expansion). In Chapter I present the first official list for the whole state of Goiás, with the objective to cover inventory gaps. In Chapter II, I explore local and landscape factors that determine local and regional diversities of anurans. I also assess the effects of area, heterogeneity, productivity and local and landscape habitat complexity over alpha and beta diversities of anurans. In Chapter III, I approach one of the most classic and controversial models for the conservation of the species, known as "SLOSS" (single large or several small). This model should be considered especially when the goal is to preserve as many frog species associated with ponds.Finally, in Chapter IV, I built occupation models to assess the effects of amount of remaining habitats, isolation between remnants as well as local characteristics on the occurrence of some species of amphibians typical Brazilian Cerrado. / As atividades de uso da terra têm transformado grandes áreas naturais em áreas de pastagens ou agricultáveis. Este processo se tornou um problema mundial e é tido como um dos principais responsáveis pelo declínio de espécies de diferentes grupos taxonômicos. Dentre os vertebrados, os anfíbios são um dos grupos mais ameaçados, sendo que as espécies com larvas aquáticas são as mais susceptíveis. Tais populações seguem uma dinâmica de metacomunidades e podem estruturar-se de acordo com uma combinação de processos, conhecidos como dinâmica de manchas, dinâmica de ordenação de espécies, efeito de massa e dinâmica neutra. No entanto, a escassez de informações a respeito do padrão de riqueza e ocupação das espécies de anuros em escala local e regional é um problema para a conservação da diversidade dos mesmos. Tendo como principal objetivo fornecer informações relevantes para a conservação de anuros no Cerrado brasileiro, abordei questões relacionadas aos padrões em escala local e regional, bem como modelos de ocupação de algumas espécies de anfíbios com o intuito de identificar fatores que estão direcionando a riqueza e ocupação das espécies de anuros que se reproduzem em poças no Cerrado. Para isso, coletei dados no estado de Goiás, único estado brasileiro totalmente inserido no bioma Cerrado, e que segue a mesma tendência do restante do bioma em relação a perda de habitat devido ao avanço das fronteiras agrícolas. Com o intuito de cobrir lacunas de inventários para a região, no Capítulo I apresento a primeira lista oficial de espécies de anuros para o estado de Goiás. No Capítulo II, abordo como fatores locais e da paisagem determinam a diversidade local e regional de anuros. Busquei explorar os efeitos da área, heterogeneidade e complexidade de hábitats local e da paisagem e da produtividade sobre a diversidade alfa e beta de anuros. No Capítulo III¸ abordo um dos modelos mais clássicos e controversos para conservação das espécies, que é conhecido como: “muitas pequenas ou uma única grande” ou “SLOSS” (single large or several small). Este modelo deve ser especialmente considerado quando o objetivo é preservar o maior número de espécies de anuros associados a poças. E, por fim, no Capítulo IV, construí modelos de ocupação para ter acesso aos efeitos da quantidade de remanescentes de habitas, isolamento entre remanescentes de Cerrado, bem como características locais sobre a ocorrência de algumas espécies de anfíbios típicas do Cerrado Brasileiro.
5

ESTRUTURA ESPACIAL DE COMUNIDADES DE ANUROS DE DUAS REGIÕES FISIOGRÁFICAS DO BIOMA PAMPA / SPATIAL STRUCTURE OF ANURAN COMMUNITIS IN TWO PHYSIOGRAPHIC REGIONS OF PAMPA BIOME

Lipinski, Victor Mendes 26 February 2013 (has links)
Coordenação de Aperfeiçoamento de Pessoal de Nível Superior / In this study, we sampled two anuran communities in two physiographic regions of the Pampa biome, Serra do Sudeste and Depressão Central, were made monthly campaigns during the period between September 2011 and August 2012 where there were registered 25 species of frogs. Scinax granulatus, Physalaemus gracilis e Pseudis minuta were the most abundant species in the Serra do Sudeste, while Dendropsophus minutus, D. sanborni and Scinax squalirostris were the most abundant of the Depressão Central. We recorded 15 species of frogs in the larval stage and four reproductive modes classified as generalists. Ordination analysis showed a segregation among the two physiographic regions, related to anurofauna with a difference of 65% between them. The influence of environmental descriptors and physicochemical variables of water in the structure of the two communities showed that the set of variables, pH, number of extracts of emergent vegetation and temperature were important in structuring the community of Depressão Central, as dissolved oxygen, electrical conductivity number of extracts of emergent vegetation, hydroperiod and percentage of vegetation cover were important factors structuring the community of Serra do Sudeste. However the abundance and richness of the Serra do Sudeste community showed no significant relation with the variables tested and the distance between the puddles did not influence the structure of both communities. / Neste estudo, foram amostradas duas comunidades de anuros em duas regiões fisiográficas do bioma Pampa, a Serra do Sudeste e a Depressão Central, nestas, foram realizadas campanhas mensais durante o período de setembro de 2011 a agosto de 2012 onde foram registradas 25 espécies de anuros. Scinax granulatus, Physalaemus gracilis e Pseudis minuta foram as espécies mais abundantes na Serra do Sudeste, enquanto Dendropsophus minutus, D. sanborni e Scinax squalirostris foram as mais abundantes da Depressão Central. Foram registrados 15 espécies de anuros em estágio larval e quatro modos reprodutivos generalistas. A análise de ordenação mostrou uma segregação quanto a anurofauna das duas regiões fisiográficas e uma diferença de 65% entre elas. A influência dos descritores ambientais e das variáveis físico-químicas da água na estrutura das duas comunidades mostrou que o conjunto de variáveis, pH, número de extratos de vegetação emergente e temperatura foram importantes na estruturação da comunidade da Depressão Central, já o oxigênio dissolvido, condutividade elétrica número de extratos de vegetação emergente, hidroperíodo e porcentagem de cobertura vegetal foram importantes estruturadores da comunidade da Serra do Sudeste. A abundância e a riqueza de anuros da Serra do Sudeste não apresentou relação significativa com as variáveis testadas e a distância entre as poças não influenciou na estrutura das mesmas.

Page generated in 0.0424 seconds