• Refine Query
  • Source
  • Publication year
  • to
  • Language
  • 75
  • 65
  • 48
  • 21
  • 12
  • 8
  • 4
  • 3
  • 1
  • 1
  • 1
  • Tagged with
  • 262
  • 55
  • 52
  • 49
  • 36
  • 30
  • 29
  • 26
  • 25
  • 23
  • 21
  • 19
  • 19
  • 19
  • 17
  • 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.
11

The microclimate of Australian cattle feedlots

Petrov, Ryan January 2007 (has links)
[Abstract]: The incidence of cattle heat stress is a significant production and welfare issue for the feedlot industry. It is hypothesised that the presence and physical nature of feedlots causes significant microclimatic variations compared to the external environment.In order to test this hypothesis, data was collected using a series of automatic weather stations located in the external environment surrounding two Australian feedlots. Comparison of this data with regional Bureau of Meteorology sites was undertaken to verify the quality of these ‘control’ sites. To determine the climate within the feedlot separate automatic weather stations were placed within the cattle pens at each site, with one station located in an unshaded pen and one directly under an artificial shade structure within an adjacent pen.This dissertation reports the collection and analyses of detailed climatic data from the surrounds and within the cattle pens of these two Australian feedlots. The project also sought to determine microclimatic differences within the feedlot pen area that may be caused by the presence of the shade structures.It was found that the presence of a feedlot does create significant microclimatic variations. Specifically, it was determined that the albedo values of the feedlot pen surface are significantly lower (ranging from 0.13 to 0.19) than those of the external feedlot environment (typically 0.15 to 0.25). This is a result of the surface changes arising from the establishment of clay based manure covered pens. Under wet conditions the differences in albedo values were further increased. It was found that the short wave radiation reflection from the external feedlot environment was 4% greater than that from the unshaded feedlot pen surfaces under dry conditions and 10% greater under wet conditions. The increased adsorption of solar radiation by the feedlot pen surface created ground temperatures that were on average 2 to 4°C warmer than those of the feedlot surrounds. The re-radiation of heat from the pen surface was found to create warmer air temperatures within the feedlot pens compared to the external environment, particularly overnight. Between the hours of 4am to 6am it was found that on average the air temperatures of the shaded and unshaded feedlot pens were 0.7°C and 0.5°C warmer than the external feedlot environment.It was found that feedlot pen infrastructure and cattle significantly reduce wind speeds under a height of 10 metres. The average 2 metre wind speeds of the external feedlot environments were found to be 29% and 9% higher than those recorded in the unshaded pens at the northern and southern feedlots respectively.Shade structures within feedlot pens were found to be effective in reducing incoming solar radiation with the galvanised sheeting reducing incoming solar radiation by 76% and the shade cloth providing a 72% reduction. These reductions provided both lower ground temperatures and a significant reduction in radiant heat loads under the shade. It was determined that the environment under shade structures was more humid compared to that of the unshaded pens with humidity levels recorded being 8 to 12% higher. Shade structures also restrict horizontal wind movement with the 2 metre wind speeds in the shaded pens being on average 11% and 0.5% lower than those recorded in the unshaded pens for the Queensland and NSW feedlots respectively.Research has shown that microclimatic variations such as increased air temperatures, increased humidity and restricted air movement can have an adverse effect on cattle health. It is concluded from this project that in order to mitigate these effects a number of feedlot design concepts be implemented, and management practices should be adopted. Maintaining minimal quantities of manure on the pen surface will provide lower ground temperatures, dryer pen conditions and inhibit the re-radiation of heat and evapotranspiration from the pen surface. Adequate air flow should be maintained by siting feedlots in areas of suitable topography, and designing feedlot infrastructure and shade structures to maximise air movement. Shade structures need to aim at providing dryer pen surfaces to minimise humidity levels. Incorporation of these recommendations into feedlot design and management will assist in optimising the feedlot microclimate.
12

The role of fire, microclimate, and vegetation in lesser prairie-chicken habitat selection

Lautenbach, Jonathan David January 1900 (has links)
Master of Science / Division of Biology / David A. Haukos / The lesser prairie-chicken is a prairie grouse native to the southwestern Great Plains that has experienced significant population and habitat declines since European settlement. Ongoing declines prompted the U.S. Fish and Wildlife Service to list lesser prairie-chickens as threatened under the Endangered Species Act in spring of 2014. In fall of 2015, the listing was vacated on procedural grounds and the lesser prairie-chicken was removed from listing in summer 2016. Despite the legislative change, considerable conservation efforts emerged with the initial listing and have continued following the removal of the species from the threatened and endangered species list. Understanding how lesser prairie-chickens use landscapes and how management actions can influence their space use is important for long-term strategies to meet conservation goals. I modeled lesser prairie-chicken habitat selection relative to landscape mosaics of vegetation patches generated through patch-burn grazing, microclimate, and vegetation characteristics across their range. I captured, attached GPS satellite or VHF radio transmitters to, tracked, and measured vegetation characteristics used by and available to female lesser prairie-chickens across the northern portion of their range in Kansas and Colorado. Female lesser prairie-chickens use all patch types created in a patch-burn grazing mosaic, with female selecting greater time-since-fire patches (>2-years post-fire) for nesting, 2-year post-fire patches during the spring lekking season, 1- and 2-year post-fire patches during the summer brooding period, and 1-year post-fire units during the nonbreeding season. Available vegetation structure and composition in selected patches during each life-cycle stage was similar to the needs of female lesser prairie-chickens during that life-cycle stage. To assess their selected microclimate conditions, I deployed Maxim Integrated Semiconductor data loggers (iButtons) at female flush locations and across a landscape inhabited by lesser prairie-chickens. Females selected locations that minimized thermal stress at microsite, patch, and landscape scales during peak midday temperatures during summer. Females selected midday locations based on vegetation characteristics; where selected sites had >60% forb cover and <25% grass cover, or >75% grass cover and <10% forb cover. In addition, females selected sites with greater visual obstruction. I measured vegetation composition and structure at use and available sites at four study areas located along the precipitation gradient characterizing the full extent of the lesser prairie-chicken range. Vegetation structure use by females varied in relation to long-term precipitation patterns. Females used sites with lower visual obstruction than available during the fall and spring. However, they used vegetation composition that was similar to available within each study area. Overall, my findings indicate that lesser prairie-chickens require structural and compositional heterogeneity to support a suite of habitat needs throughout the year. Therefore, management should focus on providing structural and compositional heterogeneity across landscapes. Greater heterogeneity in vegetation conditions can be achieved through management practices that allow domestic grazers to select grazing locations, such as patch-burn grazing or increased pasture area.
13

Kvalita ovzduší ve školách / Air quality at school

Hromádka, Jiří January 2013 (has links)
(EN) Thesis describes air quality in schools, its main factors of interest and according to the longitudinal study it suggests possible solutions for improvement. The study had been done in Kladská elementary school, Prague, Czech Republic, based on the findings obtained from the initial literature review. Although many scientific papers have been published mainly during last decade, there is a very limited amount of information concerning this issue within a longer timescale and a complex point of view is missing. The school environment was chosen because children are one of the groups at higher risk when adverse health effects caused by inadequate indoor air quality are evaluated. Aerosol particles and carbon dioxide concentration, temperature and relative humidity levels are important factors of interest in this case and all of them were included in the study. 8 measuring campaigns, each of them took 1 week, had been done throughout the whole school year. The main aim of these campaigns was monitoring and describing the variability of all selected factors during the day or year as well as between different classrooms. Average aerosol particles concentration (PM10) didn't exceed 70µg.m-3 during most of the campaigns and the pupil's activity was evaluated as the main influencing factor. The...
14

Personal-portable Cooling Garment Based on Adsorption Vacuum Membrane Evaporative Cooling

Yang, Yifan 15 March 2011 (has links)
A cutting edge man-portable AVMEC cooling garment was demonstrated to be able to provide sufficient cooling for personnel working at mediate activity loads. Studies were first carried out in a well controlled vacuum desiccator at room temperature to elucidate the effects of several key parameters on the performance of an AVEC device, which was similar to AVMEC except that membrane was not involved. Under the best condition, an average cooling capacity of 179 W/M2 was achieved in a period of four hours and cooling continued at a slowly declining rate for another four hours afterward. The temperature of water was maintained at approximately 12.5 oC after the pseudo steady state was established. Then, it was shown that the AVMEC cooling pads were able to provide a cooling capacity of 277.4 W/m2 in a 37 oC ambient environment (incubator). The temperature of the cooling core surface was maintained in a range of 20 – 21.8 oC in the one-hour test period. No power supply was required except for the initialization stage, which took 5 minutes. Furthermore, human subject tests with or without wearing NWBC (Nuclear Warfare Biological and Chemical) suit demonstrated that, a AVMEC garment composed of 12 cooling pads were able to maintain the core body temperature of the subjects below 38.5 oC for up to 90 minutes while the subject was walking on a treadmill at a speed of 2 miles per hour in an environment of 40 oC and 50% RH (relative humidity). These results indicate that the AVMEC garment is a promising man-portable personal cooling technology.
15

Personal-portable Cooling Garment Based on Adsorption Vacuum Membrane Evaporative Cooling

Yang, Yifan 15 March 2011 (has links)
A cutting edge man-portable AVMEC cooling garment was demonstrated to be able to provide sufficient cooling for personnel working at mediate activity loads. Studies were first carried out in a well controlled vacuum desiccator at room temperature to elucidate the effects of several key parameters on the performance of an AVEC device, which was similar to AVMEC except that membrane was not involved. Under the best condition, an average cooling capacity of 179 W/M2 was achieved in a period of four hours and cooling continued at a slowly declining rate for another four hours afterward. The temperature of water was maintained at approximately 12.5 oC after the pseudo steady state was established. Then, it was shown that the AVMEC cooling pads were able to provide a cooling capacity of 277.4 W/m2 in a 37 oC ambient environment (incubator). The temperature of the cooling core surface was maintained in a range of 20 – 21.8 oC in the one-hour test period. No power supply was required except for the initialization stage, which took 5 minutes. Furthermore, human subject tests with or without wearing NWBC (Nuclear Warfare Biological and Chemical) suit demonstrated that, a AVMEC garment composed of 12 cooling pads were able to maintain the core body temperature of the subjects below 38.5 oC for up to 90 minutes while the subject was walking on a treadmill at a speed of 2 miles per hour in an environment of 40 oC and 50% RH (relative humidity). These results indicate that the AVMEC garment is a promising man-portable personal cooling technology.
16

MOKYKLOS MIKROKLIMATO IR MOKYTOJO ĮTAKA MOKINIŲ DOROVINIŲ VERTYBIŲ UGDYMUI / The role of the school microclimate and teachers in moral education

Butkeraitytė, Sonata 05 June 2006 (has links)
Author: Sonata Butkeraitytė Subject: The role of the school microclimate and teachers in moral education Location: Lithuanian University of Agriculture. The department of Professional Pedagogy and Psychology. Academy, 2006 Coverage: pages The work includes: 25 pictures, 5 appendices Literature sources: Object of the research: A moral education of a pupil. Methods of the research: 1. Analysis of scientific sources 2. Diagnostic methods – questionnaires 3. Interview 4. Statistic data analysis Results of the research: The purpose of the research was to analyze the conception and the content of moral education in pedagogical literature and to disclose a contemporary role of a teacher in the process of moral education. The research results reveal that pedagogical literature focuses mainly on the theoretical side of moral education, lacking in practical examples. The results show that the individuality of a teacher, his attitude towards work and motivation of pupils are of major significance for moral education. Teacher’s capabilities to match training and education are very important to pupils. Unfortunately, as disclosed by the research, more often than not teaching is merely a source of income. Teachers are of the opinion that the teacher’s role in the process of moral education would increase, if the standing of a teachers were greater in society, which at present remains steadily diminished. Secondly... [to full text]
17

A Microclimate Analysis of a Niagara Peninsula Vineyard Using Solar Aspect as a Variable

Dixon, Philip G. 09 May 2012 (has links)
This study, based on data collected in 2006, examined the effect of microclimate, as solar aspect, on yield and quality parameters of Riesling vines of a vineyard in the Niagara Peninsula, Thirty Bench Winery, Beamsville, Ontario. Precision viticulture practices including GPS (Global Positioning System), GIS (Geographic Information System) and LIDAR (Laser Range Finder) were used to delineate the microclimate and categorize variations within the vineyard. Within GIS, slope and aspect analysis tools generated solar aspect data. Two different zones were identified and compared for yield and quality data. Monoterpene concentrations in grapes differed by solar aspect, with vines receiving elevated solar radiation showing increased monoterpene concentrations. Since monoterpenes are important to the aroma and flavour of Riesling wines, a difference could impact the quality of the wine produced. Overall, this work shows the potential of precision viticulture in the development of terroir –specific wine in the Niagara region.
18

Personal-portable Cooling Garment Based on Adsorption Vacuum Membrane Evaporative Cooling

Yang, Yifan 15 March 2011 (has links)
A cutting edge man-portable AVMEC cooling garment was demonstrated to be able to provide sufficient cooling for personnel working at mediate activity loads. Studies were first carried out in a well controlled vacuum desiccator at room temperature to elucidate the effects of several key parameters on the performance of an AVEC device, which was similar to AVMEC except that membrane was not involved. Under the best condition, an average cooling capacity of 179 W/M2 was achieved in a period of four hours and cooling continued at a slowly declining rate for another four hours afterward. The temperature of water was maintained at approximately 12.5 oC after the pseudo steady state was established. Then, it was shown that the AVMEC cooling pads were able to provide a cooling capacity of 277.4 W/m2 in a 37 oC ambient environment (incubator). The temperature of the cooling core surface was maintained in a range of 20 – 21.8 oC in the one-hour test period. No power supply was required except for the initialization stage, which took 5 minutes. Furthermore, human subject tests with or without wearing NWBC (Nuclear Warfare Biological and Chemical) suit demonstrated that, a AVMEC garment composed of 12 cooling pads were able to maintain the core body temperature of the subjects below 38.5 oC for up to 90 minutes while the subject was walking on a treadmill at a speed of 2 miles per hour in an environment of 40 oC and 50% RH (relative humidity). These results indicate that the AVMEC garment is a promising man-portable personal cooling technology.
19

Internal environment of badger (Meles meles) setts

Moore, Jude Arthur Hamilton January 1997 (has links)
No description available.
20

A fine scale assessment of urban greenspace impacts on microclimate and building energy in Manchester

Skelhorn, Cynthia January 2014 (has links)
Climate change projections estimate a rise of approximately 3 °C by the 2080‘s for most of the UK (under a medium emissions scenario at 50% probability level, 1961-1990 baseline). Warming is of particular concern for urban areas due to the issues of urban densification and the Urban Heat Island (UHI) effect. To combat warming, one adaptation strategy that has been suggested for urban areas is increasing the proportion of greenspace, such as parks, gardens, street tree plantings, and green roofs. While a number of studies have investigated the cooling effect of greenspace in terms of park size, proximity to a park, or area covered by tree canopy, little is yet known about the specific types of greenspace that contribute to its cooling effectiveness and how this relates to building energy demand. This thesis employs an interdisciplinary approach to model fine-scale changes to greenspace for a temperate northern UK city, linking the resulting microclimate changes to building energy consumption in commercial buildings. Using the urban microclimate model ENVI-met, two study areas (one urban one suburban) were modelled with seven different greenspace scenarios (a base case representing current field conditions, +5% new trees, +5% mature trees, +5% hedges, addition of a green roof on the largest building, changing all current greenspace to grass only, and changing all current greenspace to asphalt only) for a summer day in July 2010. The models were calibrated based on measured air temperature data and then analysed for microclimate changes due to each greenspace scenario. Both the modelled and measured microclimate data were then used to inform a series of building energy models using IES-VE 2012 for three commercial building types, estimating summer cooling and winter heating trade-offs due to greenspace effects. For the most effective scenario of adding 5% mature trees to the urban case study, the microclimate modelling estimates a maximum hourly air temperature reduction of nearly 0.7 °C at 5 pm and surface temperature reductions up to 1.7 °C at 3 pm. In the suburban case study, a 5% increase in mature deciduous trees can reduce mean hourly surface temperatures by 1 °C between 10 am and 5 pm, while the worst case scenario of replacing all current vegetation (20% of the study area) with asphalt results in increased air temperature of 3.2 °C at mid-day. The building energy modelling estimates a reduction of 2.7% in July chiller energy due to the combination of reduced UHI peak hours and eight additional trees (four on the north side and four on the south side) of a three-storey shallow plan building. These energy savings increase to 4.8% under a three-day period of peak UHI conditions. While winter boiler energy usage shows large reductions for a building in an urban location with a low proportion of greenspace (as compared to a suburban location), this benefit is marginal when analysed in terms of carbon trade-offs between summer cooling and winter heating requirements.

Page generated in 0.0707 seconds