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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

Factors affecting the clarification of colliery wastewater

Edusei, Enoch January 1984 (has links)
Investigations were initially carried out to characterize the materials present in shape, mineralogical and chemical composition, and particle size distribution. A micro-electrophoresis apparatus was constructed to determine the electrokinetic parameters of the colliery waste-water. The origin of the surface charge which forms on minerals immersed in water is important in flocculation. The nature of the charges on the fines were determined to be both positive and negative. This could be due to the coating of the particles by the addition of the froth flotation reagent used. The electrophoretic mobilities of the particles were measured at the various pH values and at different depths within the electrophoretic cells. These values of the electrophoretic mobilities were used to calculate the values of the zeta potential by the application of Smoluchowski's equation. The iso-electric point (IEP) and the zero point of charge (ZPC) were also investigated and found to coincide at all the different levels of depth within the electrophoretic cell. Finally the colliery waste-water was clarified successfully by flocculating it using the polyacrylamide solution.
2

A Survey of the Occurence of Oxygen 18 in Natural Sources

Vrooman, Ransom H. 10 1900 (has links)
An investigation of the concentration of the heavy isotope of oxygen, O18, in various samples of water was carried out. Natural variations as high as 2.9% were found - glacier water being 2.3% light and Dead Sea water 2.0% heavy, as compared to Lake Ontario water as standard. Other values - water from tank oxygen + 2.9%, atmospheric water vapor -0.9%, Atlantic Ocean water +0.4%, Pacific Ocean water - 0.8% , and atmospheric carbon dioxide - 0.5%. The water samples were equilibrated with tank carbon dioxide, which was then analyzed using the mass spectrometer. Some work was also done on photosynthesis. The free water, water of crystallization, and tissue oxygen (as water) , in a normal leaf which had bean photosynthesizing for 8 hours, were analyzed by equilibration with carbon dioxide as above. It was found that all of these were more enriched in oxygen 18 than the water with which they were fed . The free water averaged about 1.3% heavy, water of crystallization as high as 8.7% heavy, and tissue oxygen varied from 0.5% light to 5.5% heavy. This work only just touches the edges of this field - many more interesting experiments remain to be carried out later. / Thesis / Master of Science (MS)
3

Development and Co-occurrence of Emotional and Behavior Problems in Early Adolescence: Gender Differences and Intervention Effects

Klostermann, Susan Joan January 2011 (has links)
No description available.
4

Metodologia para inspeção visual e automatica de carga em vagões ferroviarios / Methodology for visual and automatic inspection of cargo in railway cars

Tambur, Gabriel dos Santos 12 July 2007 (has links)
Orientador: Clesio Luis Tozzi / Dissertação (mestrado) - Universidade Estadual de Campinas, Faculdade de Engenharia Eletrica e de Computação / Made available in DSpace on 2018-08-09T18:52:49Z (GMT). No. of bitstreams: 1 Tambur_GabrieldosSantos_M.pdf: 6836328 bytes, checksum: a9f9ee22e341720b36aab9a7e3566604 (MD5) Previous issue date: 2007 / Resumo: Neste trabalho foi desenvolvida uma metodologia para inspeção visual e automática de carga de grãos em vagões ferroviários que utiliza técnicas de processamento de imagens. A metodologia inclui três etapas principais: a localização do vagão na imagem utilizando a transformada de Hough, a descrição da carga usando cor e textura, e a identificação de regiões com possíveis objetos sobrepostos. A avaliação dos resultados foi feita a partir de imagens reais e simuladas. A abordagem proposta mostrou-se adequada para os objetivos especificados / Abstract: This work proposes the development of a methodology to scan visually and automatically the grain cargo in railway cars using image processing techniques. The methodology is composed by three main steps: the localization of the railway car in the image using the Hough Transform, the description of the cargo using its color and texture, and the identification of regions with possibly overlaid objects. The assessment of the results was done through real and simulated images. The proposed methodology proved to be adequate for the specified objectives / Mestrado / Engenharia de Computação / Mestre em Engenharia Elétrica
5

The Itchy and Scratchy Show: Association Between Co-Occurring Parasites and Exploratory Behaviour in Mice

Caron-Lévesque, Merlin 28 October 2021 (has links)
Host-parasite interactions are complex, involving host behaviour, host condition, and possible antagonism or mutualism between co-occurring parasites. The white-footed mouse (Peromyscus leucopus) is a small, abundant, generalist rodent, and the primary host for the black-legged tick (Ixodes scapularis) in its larval stage. Since larval ticks do not actively pursue their hosts (they wait for possible hosts to come to them), individual differences in mouse exploratory behaviour might be expected to correlate with tick burden. However, mice may also prevent tick attachment with defensive behaviour such as grooming. Yet, the relationships between tick parasitism and host exploratory and grooming behaviours have never been assessed. I analysed data from a capture-mark-recapture study conducted over 5 summers (2016-2020) in eastern Ontario, Canada, in which 1,035 mice were captured a total of 4,333 times. The probability of tick parasitism occurring and being more intense was significantly higher when the mouse was also parasitized by fleas, suggesting co-occurrence of these two parasites on host mice. A total of 510 mice were subjected to an open-field test to quantify exploratory and grooming behaviours. Exploration had a negative relationship with tick presence and a positive relation with flea presence. Most interestingly, there was a significant “tick × flea” interaction on exploratory behaviour such that fleas were positively associated with exploration only when ticks were absent. Surprisingly, there was no relationship between grooming behaviour in the open-field test and parasite presence, although grooming increased with mouse activity. This study shows that co-occurring parasite species (ticks and fleas) may interact to affect their host’s exploratory behaviour. Alternatively, individual differences in exploratory behaviour of hosts may differentially affect their susceptibility to being infested with ticks, fleas, or both. Future manipulative studies should use experimental design to determine the causality of the parasitism-behaviour relationships observed.
6

Automated Prediction of Solar Flares Using SDO Data. The Development of An Automated Computer System for Predicting Solar Flares Based on SDO Satellite Data Using HMI Images Analysis, Visualisation, and Deep Learning Technologies

Abed, Ali K. January 2021 (has links)
Nowadays, space weather has become an international issue to the world's countries because of its catastrophic effect on space-borne and ground-based systems, and industries, impacting our lives. One of the main solar activities that is considered as a major driver of space weather is solar flares. Solar flares can be defined as an enormous eruption in the sun's atmosphere. This phenomenon happens when magnetic energy stored in twisted magnetic fields, usually near sunspots, is suddenly released. Yet, their occurrence is not fully understood. These flares can affect the Earth by the release of massive quantities of charged particles and electromagnetic radiation. Investigating the associations between solar flares and sunspot groups is helpful in comprehending the possible cause and effect relationships among solar flares and sunspot features. 01 This thesis proposes a new approach developed by integrating advances in image processing, machine learning, and deep learning with advances in solar physics to extract valuable knowledge from historical solar data related to sunspot regions and flares. This dissertation aims to achieve the following: 1) We developed a new prediction algorithm based on the Automated Solar Activity Prediction system (ASAP) system. The proposed algorithm updates the ASAP system by extending the training process and optimizing the learning rules to the optimize performance better. Two neural networks are used in the proposed approach. The first neural network is used to predict whether a specific sunspot class at a particular time is likely to produce a significant flare or not. The second neural network is used to predict the type of this flare, X or M-class. 2) We proposed a new system called the ASAP_Deep system built on top of the ASAP system introduced in [6] but improves the system with an updated deep learning-based prediction capability. In addition, we successfully apply Convolutional Neural Network (CNN) to the sunspot group image without any pr-eprocessing or feature extraction. Moreover, our system results are considerably better, especially for the false alarm ratio (FAR); this reduces the losses resulting from the protection measures applied by companies. In addition, the proposed system achieves a relatively high score of True Skill Statistic (TSS) and Heidke Skill Score (HSS). 3) We presented a novel system that used the Deep Belief Networks (DBNs) to predict the solar flares occurrence. The input data are SDO/HMI Intensitygram and Magnetogram images. The model outputs are "Flare or No-Flare" of significant flare occurrence (M and X-class flares). In addition, we created a dataset from the sunspots groups extracted from SDO HMI Intensitygram images. We compared the results obtained from the complete suggested system with those of three previous flare forecast models using several statistical metrics. In our view, these developed methods and results represent an excellent initial step toward enhancing the accuracy of flare forecasting, enhance our understanding of flare occurrence, and develop efficient flare prediction systems. The systems, implementation, results, and future work are explained in this dissertation.
7

Forest stand characterisation using very high resolutions satellite remote sensing/Caractérisation des peuplements forestiers par télédétection à très hautes résolutions

Kayitakire, François 26 April 2006 (has links)
Effective management of forest resources requires reliable and timely information on their status. In this regard, remote sensing techniques have played an important role, as they allow collection of data on extensive, remote and inaccessible areas. Historically, aerial photographs were the primary remote sensing data source in forest inventory and mapping, and they are still extensively for visual photo-interpretation. In this thesis, we show that their use can be improved thanks to automatic processing and an application using digitised orthophotos is provided. Satellite-based remote sensing has been regarded as an alternative, low-cost and rapid, data source to aerial photography and ground survey. Indeed, it has proved to be effective at the continental and global scales, but applications for local forest management purposes are still rare. The main reason for this is that the spatial resolution of satellite remote sensing data that was available until recently (mainly from Landsat TM/ETM and SPOT HRV) was too coarse for stand level information. Satellite images with enhanced spatial resolution (such as IKONOS) should overcome this limitation. This thesis investigates their actual capabilities for forest stand mapping and characterisation. We show that they are well suited for forest stand type classification and for retrieval of several dendrometric variables in coniferous stands with an accuracy similar to that of field sampling. For the sake of solutions to provide more precise and detailed information on forest stand, we assessed also the contribution of hyperspectral and multiple-view angle data acquired by CHRIS/PROBA. Although the winter season scene did not fully permit utilisation of the hyperspectral dimension of this dataset, the study provides insights into directional effects. This work makes, hopefully, a step towards automated processing and effective integration of satellite-based remote sensing data into the forest management information system and, by upscaling, into the national forest inventories.
8

Plant Species Richness and Species Area Relationships in a Florida Sandhill

Downer, Monica Ruth 01 January 2012 (has links)
Pine sandhill are integral pyrogenic communities in the southeastern United States. Though once widespread, habitat destruction, fire suppression and fragmentation have reduced the population to nearly 3%. It is important to learn as much as possible about these unique areas in order to implement best management practices to conserve and restore the existing populations of these communities. Fire is central to the maintenance of pine sandhill communities and two conceptual hypothesis regarding burn frequency have come to light in maintaining the unique species composition and richness of these areas. The first is the Intermediate Disturbance Hypothesis which suggests that intermediate fire regime maintains species diversity. The second is the Most Frequent Fire Hypothesis suggests that these areas should be burned as frequently as fuels allow. We used species area curves and species area relationships to answer the following questions about a pine sandhill community in the burn plot area of the University of South Florida Ecological Research Area (ERA). What are the patterns of species richness and how do they change with spatial scale? What are the factors contributing to the heterogeneity of this area and how much are they contributing? Do similarly burned areas have similar species composition? Do our results shed some light on the Intermediate Disturbance Hypothesis or Most Frequent Fire Hypothesis? We found that physical distance contributed more to species compositional and spatial patterns than burn regime or elevation, whose effects were small. On this particular scale, the results did not support either the Intermediate Disturbance Hypothesis or Most Frequent Fire Hypothesis, as acquisition rates of species in all burn regimes were quite similar. There was no obvious pattern of increased species richness with frequent or intermediate burning. Our results suggest a need for a dynamic plan for the conservation, preservation and management of pine sandhill communities. One must consider as many factors as possible when managing these lands, as every sandhill is unique. More research should be conducted on these ecologically sensitive and diminished areas in order to formulate best management practices to conserve, protect and restore pine sandhill in the southeastern United States.
9

Irritable bowel syndrome diagnosed in primary care : Occurrence, treatment and impact on everyday life

Olsen Faresjö, Åshild January 2006 (has links)
Background: IBS is the most common functional gastrointestinal disorders and affects approximately 10-20 % of the general population and is widespread in all societies and socio-economic groups. Although the disorder does not have a life-threatening course, it still seriously affects the patients in their everyday life. Aim: The general aims of this thesis were to estimate the occurrence of irritable bowel syndrome in the general population and to achieve a better understanding of present treatment of this disorder and impact on every-day life in those suffering from IBS. Material and methods: The LIPS study comprises two parts. Part I was a retrospective register study where the data collection was based on computerised medical records at three selected Primary Health Care centres in a defined region. Part II was a population based case-control study. The identified IBS cases from part I constitute the cases, while their control groups were randomly selected from the population census register in the same area as the cases. Data in part II were collected by means of a postal questionnaire to cases and controls. The study was conducted in Linköping, a city located in the south-east of Sweden with 135 000 inhabitants. Results: The female IBS patients reported lower influence on planning their work and working hours as well as fewer opportunities to learn new things at their work compared to their controls, even after adjustments in multiple logistic regressions for potential confounders like; mood, sleeping problems and perceived health. The female IBS patients had considerably lower HRQOL in all dimensions compared to their controls, even when compared to male patients. Younger female IBS cases (18-44 years) reported lower mental health on the SF-36 scale than the older IBS female cases (p=0.015). In the multivariate analysis these variables, lack of influence on planning the work, family history of IBS, anxiety and sleeping disturbance displayed an association with being diagnosed with IBS in women. In men, lack of influence on working pace, family history of IBS was associated with an IBS diagnosis.The consultation incidence of IBS in part I was 3.4 (95% CI 3.20-3.70) per 1000 person-years for all IBS cases, among females; the incidence rate was 4.6 per 1000 person-years (95% CI 4.16-4.97) and males; 2.3 per 1000 person-years (95% CI 2.01-2.59). The dominating pharmacological treatment prescribed for abdominal complaints were fibre and bulking laxatives agents as well as acid suppressive drugs. These variables had an independent impact on the probability of a follow-up consultation; diagnosed co-morbidity besides the IBS diagnosis, rectoscopy ordered and laboratory tests ordered. Conclusions: IBS patients identified in primary care are significantly affected in their working-life compared to individuals in the general population. Especially female IBS-patients report lower decision latitude at work and they also appear to have a particularly impaired psychosocial functioning in their every day life and impaired HRQOL. Factors associated with IBS diagnosis among females are anxiety as well as family history of IBS and lack of co-determination at work. The incidence rate of IBS was 3.4 per 1000 person-years which increased with age and with an overrepresentation of females. IBS patients did not appear to be heavy utilisers of primary care and those who attended were treated by their GP without further consultation. The strongest predictors for having a follow-up consultation were diagnosed co-morbidity, rectoscopy and laboratory tests ordered / Figure on page 8 reprinted from Lancet 360(9332), Nicholas, J Talley and Robin Spiller, "Irritable bowel syndrome: a little understood organic bowel disease?", pp. 555-564, Copyright 2006 with permission from Elsevier. On the day of the public defence of the doctoral thesis, the status of articles III and IV was Submitted.
10

Funkční vlastnosti vysokohorských rostlin východního Ladaku (SZ Himaláje) / Functional traits of high-altitude plants in Eastern Ladakh (NW Himalayas)

CHLUMSKÁ, Zuzana January 2011 (has links)
Functional traits of 217 high altitude plants were studied in Eastern Ladakh (NW Himalayas, India). Changes in functional traits along altitudinal and moisture gradient were analysed. Plants were classified into 9 different habitats according to their frequency of occurence.

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