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The Effect of Air Temperature on the Incubation Period and Hatching Success of In Situ Loggerhead Sea Turtle (Caretta caretta) Clutches in Broward County, FloridaKawana, Lucy Teal 31 July 2013 (has links)
The survival rates of pre-emergent sea turtle hatchlings are critically dependent upon temperature. This study aimed to determine if changes in air temperature can explain some of the variability in hatching success observed over a 12 year period for loggerhead sea turtle (Caretta caretta) nests in Broward County. Air temperature data for the hatching seasons of 1999 to 2010 were obtained from the NOAA National Climatic Data Center’s Fort Lauderdale beach station. The loggerhead sea turtle hatching data collected by the Broward County Sea Turtle Conservation Program from the same time period was examined to assess the potential effects of air temperature on the hatching success and the incubation duration. Mean yearly incubation times were analyzed for trends and compared to mean nesting season temperatures. The relationships between the incubation durations and mean seasonal and intra-seasonal air temperature fluctuations as well as the relationship between hatching success and air temperature was tested for significance. The hatching success was also compared to the incubation times in order to establish if shorter incubation durations, were related to lower hatching success rates.
There have been large fluctuations in the average daily hatching success rates ranging from 10 to 100% over the twelve years examined in this study in Broward County. Significant decreases in incubation durations were apparent during times of increasing average air temperatures. In five of the twelve seasons there was also a significant relationship between the hatching success rates and the average air temperature, in which lower hatching success rates were evident during times of higher average air temperatures. There was a significant correlation between the incubation durations and the hatching success rates in six of the seasons as well, suggesting that lower hatching success rates are related to shorter incubation times. The pattern in average yearly hatching success rates were significantly related to the average monthly air temperatures in July suggesting that lower hatching success rates during the month of July were a result of higher temperatures during this time of the hatching season. A better understanding of the effects that air temperature has on loggerhead sea turtle clutches in Broward County can provide future insights for the fluctuating survival rates of sea turtle clutches and if the changes are natural or the result of conservation efforts.
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High-resolution Permafrost Distribution Modelling for the Central and Southern Yukon, and Northwestern British Columbia, CanadaBonnaventure, Philip P. January 2011 (has links)
Basal Temperature of Snow (BTS) measurements were used as the primary inputs to a high resolution (30 x 30 m grid cells) empirical-statistical regional permafrost probability model for the southern and central Yukon, and northernmost British Columbia (59° - 65°N). Data from seven individual study areas distributed across the region were combined using a blended distance decay technique, with an eighth area used for validation. The model predictions are reasonably consistent with previous permafrost maps for the area with some notable differences and a much higher level of detail. The modelling gives an overall permafrost probability of 52%. North of 62°N, permafrost becomes more extensive in the lowland areas whereas farther south permafrost is typically common only above treeline.
Significant differences exist between the mountain environments of the Yukon and the Swiss Alps where the BTS method originated and as a result different modelling approaches had to be developed. This work therefore: (1) develops additional explanatory variables for permafrost probability modelling, the most notable of which is equivalent elevation, (2) confirms the use of ground truthing as a requirement for empirical-statistical modelling in the Yukon and (3) uses a combination of models for the region in order to spatially predict between study areas.
The results of this thesis will be of use to linear infrastructure route-planning, geohazard assessment and climate change adaptation strategies. Future work employing the model will allow the effects of scenario-based climate warming to be examined.
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Утицај температуре ваздуха на сезоналност морталитета у Новом Саду / Uticaj temperature vazduha na sezonalnost mortaliteta u Novom Sadu / Impact of air temperature on seasonal variation of human mortality in Novi SadArsenović Daniela 23 May 2014 (has links)
<p>Основни циљ ове дисертације је истраживање утицаја температуре ваздуха на сезоналност морталитета становништва у Новом Саду. Однос између температуре ваздуха и морталитета становништва истраживан је у периоду од 1897. до 2009. године. Током анализе, а у циљу бољег уочавања сезоналних промена морталитета становништва, посматрана временска серија је подељена на неколико периода. Први период се односи на крај 19. и прву половину 20. века (1897-1952), други период обухвата другу половину 20. века (1953-1997), а трећи период чини 1998-2009. година.</p><p>У раду је анализиран утицај температуре ваздуха на морталитет укупног становништва, морталитет становништва према полу и морталитет становништва старог 65 и више година, а у периоду 1998-2009. године, у анализу су укључени и узроци смрти становништва. Посебно је анализиран кардиоваскуларни морталитет и морталитет становништва изазван респираторним болестима, док су остали узроци смрти посматрани заједно.</p><p>За анализу утицаја температуре ваздуха на сезоналност морталитета коришћене су различите статистичке методе као што су корелациона и регресиона анализа (графички приказане на дијаграму растурања), t-тест, релативни ризик и коефицијент сезоналне варијације морталитета. Код анализе морталитета према полу коришћен је и однос шанси.</p><p>Резултати добијени у овом раду показују да је морталитет становништва у Новом Саду већи током зимског периода године. У периоду 1897-1952. године није пронађена статистички значајна повезаност између температуре ваздуха и морталитета становништва, док је у другој половини 20. века (1953-1997) и у периоду 1998-2009. године уочена статистички значајна негативна корелација између температуре ваздуха и морталитета становништва, а регресиона анализа показује да се са растом температуре ваздуха морталитет становништва смањује. У периоду 1998-2009. године пронађена је и статистички значајна негативна корелација између морталитета кардиоваскуларних болести и температуре ваздуха, као и између морталитета респираторних болести и температуре ваздуха, док код осталих узрока смрти није уочена статистички значајна веза. Код анализе утицаја температуре ваздуха на морталитет становништва према полу нису уочене велике разлике између мушкараца и жена. За разлику од морталитета укупног становништва, код старог становништва (65+), као најугроженије категорије, статистички значајна негативна корелација јавља се од почетка посматране временске серије, а регресиона анализа такође показује да са растом температуре ваздуха морталитет старог становништва опада.</p><p>Анализа у раду показала је да се уочени сезонални образац морталитета постепено мења. Разлике између морталитета становништва у зимском пероду у односу на периоде пре и после зиме, се постепено смањују. Ове промене праћене су и променом просечне температуре ваздуха. На основу добијених резултата може се закључити да промене просечне температуре ваздуха утичу на промену и баланс морталитета по месецима у току године.</p> / <p>Osnovni cilj ove disertacije je istraživanje uticaja temperature vazduha na sezonalnost mortaliteta stanovništva u Novom Sadu. Odnos između temperature vazduha i mortaliteta stanovništva istraživan je u periodu od 1897. do 2009. godine. Tokom analize, a u cilju boljeg uočavanja sezonalnih promena mortaliteta stanovništva, posmatrana vremenska serija je podeljena na nekoliko perioda. Prvi period se odnosi na kraj 19. i prvu polovinu 20. veka (1897-1952), drugi period obuhvata drugu polovinu 20. veka (1953-1997), a treći period čini 1998-2009. godina.</p><p>U radu je analiziran uticaj temperature vazduha na mortalitet ukupnog stanovništva, mortalitet stanovništva prema polu i mortalitet stanovništva starog 65 i više godina, a u periodu 1998-2009. godine, u analizu su uključeni i uzroci smrti stanovništva. Posebno je analiziran kardiovaskularni mortalitet i mortalitet stanovništva izazvan respiratornim bolestima, dok su ostali uzroci smrti posmatrani zajedno.</p><p>Za analizu uticaja temperature vazduha na sezonalnost mortaliteta korišćene su različite statističke metode kao što su korelaciona i regresiona analiza (grafički prikazane na dijagramu rasturanja), t-test, relativni rizik i koeficijent sezonalne varijacije mortaliteta. Kod analize mortaliteta prema polu korišćen je i odnos šansi.</p><p>Rezultati dobijeni u ovom radu pokazuju da je mortalitet stanovništva u Novom Sadu veći tokom zimskog perioda godine. U periodu 1897-1952. godine nije pronađena statistički značajna povezanost između temperature vazduha i mortaliteta stanovništva, dok je u drugoj polovini 20. veka (1953-1997) i u periodu 1998-2009. godine uočena statistički značajna negativna korelacija između temperature vazduha i mortaliteta stanovništva, a regresiona analiza pokazuje da se sa rastom temperature vazduha mortalitet stanovništva smanjuje. U periodu 1998-2009. godine pronađena je i statistički značajna negativna korelacija između mortaliteta kardiovaskularnih bolesti i temperature vazduha, kao i između mortaliteta respiratornih bolesti i temperature vazduha, dok kod ostalih uzroka smrti nije uočena statistički značajna veza. Kod analize uticaja temperature vazduha na mortalitet stanovništva prema polu nisu uočene velike razlike između muškaraca i žena. Za razliku od mortaliteta ukupnog stanovništva, kod starog stanovništva (65+), kao najugroženije kategorije, statistički značajna negativna korelacija javlja se od početka posmatrane vremenske serije, a regresiona analiza takođe pokazuje da sa rastom temperature vazduha mortalitet starog stanovništva opada.</p><p>Analiza u radu pokazala je da se uočeni sezonalni obrazac mortaliteta postepeno menja. Razlike između mortaliteta stanovništva u zimskom perodu u odnosu na periode pre i posle zime, se postepeno smanjuju. Ove promene praćene su i promenom prosečne temperature vazduha. Na osnovu dobijenih rezultata može se zaključiti da promene prosečne temperature vazduha utiču na promenu i balans mortaliteta po mesecima u toku godine.</p> / <p>The main aim of this dissertation is to investigate the temperature-related human mortality in Novi Sad, for the period from 1897 until 2009. In order to detect temporal sesonal changes during time, research period was split in three parts. First period is related to the end of 19th century and first half of 20th century (1897-1953), second period covers second half of 20th century (1953-1997) and third period is related to 1998-2009.</p><p>In this dissertation impact of air temerature on human mortality of total population, than mortality by sex and mortality of old population (population aged 65 and over) is scrutinised. In the period 1998-2009 in analyses and causes of death are included. Three group of cause of death are investigated: cardiovascular disease, respiratory disease and all other causes of death are observed together.</p><p>Several different statistical methods were used for analysis of impact of air temperature on seasonal variation of human mortality: correlation and regression analysis (presented at scatter diagram), t-test, relative risk and coefficient of seasonal variation of mortality. The odds-ratio was used in the chapter related to mortality by sex.</p><p>Results for Novi Sad, show that human mortality in higher during winter period. In the period 1897-1952 statistical analysis does not show significant relation between air temperature and human mortality, while in the period of second half of 20th century (1953-1997) and period 1998-2009 statistical analysis indicated strong negative correlation between air temperature and human mortality and according to results of regression analysis increasing of air temperature is related with decreasing mortality. In the period from 1998 to 2009 statistical analysis show significant and negative correlation between cardiovascular mortality and air temperature, as well as mortality from respiratory disease and air temperature. Analysis of relation between other causes of death and air temperature does not show any significant correlation. There is no clear difference between male and female in the temperature-related mortality patterns. The most vulnerable group is population aged 65 and over. From the beginning of the observed period, statistical analysis indicates strong negative correlation between mortality of old population and air temeprature and regression coefficient demonstrate that increasing air temperature is followed with decreasing mortality.</p><p>Analysis in this thesis shows changes of seasonal pattern of mortality. Differences between mortality in winter and non-winter period (preceding and following period) are decreasing. During the time, this changes are followed by fluctuation of air temperature. According to results presented in this dissertation it can be concluded that changes of air temperature are connected with changes of distribution of mortality by month, during the year.</p>
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An iterative design process for visualizing historical air temperature recordings effectively in a single display : A user study on narrative visualizations of geospatial time-dependent data / En iterativ designprocess for att visualisera historiska lufttemperaturer mätningar effektivt i en enda vy : En användarstudie på narrativa visualiseringar av geografisk och tidsberoende dataKangas, Jussi January 2021 (has links)
How to represent data visually in an intuitive and effective way for gaining quick insights is something that the field of visualization deals with. Effective in this context means that a visualization can be understood accurately or rapidly by the viewer. However, how to visualize geospatial time series data effectively is challenging. The challenge consists of how to visualize geospatial time-dependent data in a single view that can provide both an effective overview and details of the data set. With three or more data dimensions the available coding options grows; hence, the challenge consists in combining several visual coding and viewing options into a single effective view. This thesis investigated visualization guidelines that should promote effectivness for a visualization of geospatial time-dependent data. Furthermore, in this project the data set consisted of historical air temperature measurements in Sweden, which has both geospatial and time-dependent features. The guidelines where used in an iterative design process to redesign an existing geospatial time series visualization. The goal of the redesign was to increase the effectiveness of the existing visualization. An alternative visualization was created and compared to the original visualization in a user study. The results indicate that these users experienced the alternative visualization as more effective than the original. However, the performance of the participants on four tasks indicates that the alternative visualization is not more effective. Furthermore, compared to related work the alternative visualization is not more effective. In conclusion, the alternative visualization is harder to learn than the original which may have an effect on the user’s performance. However, once the visualization is learned, then it may be more effective than the original visualization. Additionally, the use of guidelines was helpful in the design process but, in this case, did not guarantee an effective visualization. / Hur data bör representeras visuellt på ett intuitivt och effektivt sätt undersöks i det vetenskapliga fältet om visualiseringar. Vidare är det utmanande hur geografiska tidsserier ska visualiserar. Utmaningen består i hur en enda visualiserings vy ska skapas som både kan ge en överblick över data och detaljer om specifika data punkter. Anledning till att detta är utmanande är att med fler data dimensioner blir även de möjliga visuella kodnings möjligheterna flera. Därför består utmaningen i hur olika visuella kodningssätt och vyer ska kombineras i en enda vy effektivt. För att designa en effektiv vy undersöktes olika designriktlinjer kopplade till effektivitet. Dessa riktlinjer användes sedan för att designa om en existerande geografisk tidsserie visualisering in en iterativ designprocess. Data som visualiserades var historiska lufttemperaturmätningar i Sverige, en datamängd med både geografiska och tidsberoende komponenter. Den skapade alternativa visualiseringen jämfördes med originalet med hänsyn till effektivitet i en användarstudie. Resultaten tyder på att användarna uppfattar den alternativa visualiseringen som mer effektiv än originalet. Men prestations resultatet på fyra uppgifter tyder inte på att den alternativa visualiseringen skulle vara effektivare. Vidare, jämfört med relaterade arbeten är inte den alternative visualiseringen mer effektiv. Sammanfattningsvis är den alternativa visualiseringen svårare att lära sig än originalet, vilken kan påverka användarnas prestation. Men när användarna lärt sig att använda den alternativa visualiseringen, kan den alternativa vara effektivare att använda än originalet. Vidare är designriktlinjerna användbara i en designprocess men, ingen garanti för en effektiv visualisering i detta fall.
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Vazby mezi atmosférickou cirkulací a rozděleními přízemní teploty vzduchu v klimatických modelech / Links between atmospheric circulation and surface air temperature distributions in climate modelsPejchová Plavcová, Eva January 2012 (has links)
Title: Links between atmospheric circulation and surface air temperature distributions in climate models Abstract: This thesis comprises a collection of five papers dealing with validation of regional climate model (RCM) simulations over Central Europe. The first paper illustrates and discusses problems with observed data that are used for model validation and how the choice of reference dataset affects the outcomes in validating the RCMs' performances. The second paper evaluates daily temperatures, and it indicates that some temperature biases may be related to deficiencies in the simulations of large- scale atmospheric circulation. RCMs' ability to simulate atmospheric circulation and the observed links between circulation and surface air temperatures are examined in detail in the third paper. This article also compares performances of individual RCMs with respect to the driving data by analysing the results for the driving data themselves. The fourth paper focuses on biases in the diurnal temperature range within RCMs and their possible causes by examining links of the errors to the at- mospheric circulation and cloud amount. The last paper investigates the observed relationships between atmospheric circulation and daily precipitation amounts over three regions in the Czech Republic, as well as how these...
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Time series analysis of ground frost conditions at Abisko, sub-Arctic Sweden, 1985-2010 / Tidserieanalys av marktemperatur i Abisko,Norra Sverige, under perioden 1985-2010Schmidt, Anja January 2012 (has links)
Observed climatic change may result in modification of the ground thermal regime.The causes of shallow ground temperature variability, however, are not well documented.This thesis reports ground temperatures from Absiko Scientific Research Station, measured ata site currently not underlain by permafrost to illustrate the response of shallow groundtemperatures to changes in climatic parameters. Both air temperature and precipitationincreased at Abisko from 1985-2010. The strongest increase in air temperature occurred inwinter, whereas the precipitation increased mainly during the summer months. There was asignificant trend towards later onset of permanent snow cover, as well as a steadily earlierdisappearance of permanent snow cover in spring, resulting in reduced snow cover duration.Also the snow thickness decreased at Abisko during the study period. The ground experiencedapproximately five months of frost at 5 and 20 cm depth and approx. four, respectively two,months at 50 and 100 cm depth. Annual ground temperatures were found to be increasingfrom 1985-2010 with approx. 0.31 °C, 0.64 °C, 0.82 °C and 0.94 °C at 5, 20, 50, respectively100 cm depth from the surface. The duration and intensity of the seasonal frost cycles weredecreasing, which would reflect the increasing ground temperatures. Changes in short-termfrost cycles were not found to be significant. The changes in mean annual and winter groundtemperature were significantly correlated to the changes in mean annual and winter airtemperature, but surprisingly not to the changes in snow cover. However, seasonally theincreasing trend of ground temperatures was found in autumn and winter, whereas thesummer ground temperatures were decreasing. The cooling of ground temperature in summerat increasing air temperatures may be explained by increased precipitation totals and henceincreased soil moisture due to the so called soil-moisture feedback. From this fact, it can bededuced that the changes in air temperature alone cannot explain all variances in groundtemperatures. However, the results of the study may suggest that in sub-Arctic Swedenchanges in air temperatures may be used as indicator for changes in shallow groundtemperatures. / perioden 1985-2010 ökade både lufttemperatur och nederbörd i Abiskoområdet. Denstörsta ökningen av lufttemperatur skedde under vinterhalvåret medan nederbörden ökademest under sommarhalvåret. En signifikant förkortning i längden av vintersnötäckets existensunder året observerades under studieperioden. Reduceringen av vintesnötäcket skedde genomatt den första snön kom senare och bortsmältningen på våren skedde tidigare. Snötäcketstjocklek minskade också under studieperioden. Marktemperaturmätningarna visar frysgraderpå 5 och 20 cm djup fem månader och fyra respektive två månader på 50 och 100cm djup.Den årliga medeltemperaturen i marken ökade under perioden med 0.31 °C, 0.64 °C, 0.82 °Coch 0.94 °C vid 5, 20, 50 och 100 cm djup. Den årliga längden och intensiteten avfrysförhållandena i marken minskade vilket förmodligen är en konsekvens av de ökandemarktemperaturerna. Ingen trend i förekomsten av kortare svängningar i frysförhållandenakunde observeras. Förändringarna i årsmedetemperaturen i marken är signifikant korrelerademed förändringen i den årliga medeltemperaturen och vintertemperaturen i luften, men ingenkorrelation mellan marktemperaturen och förändringar i snötäckets tjocklek och längdobserverades. Studien avslöjade också att temperaturen i marken ökade under vinternhalvåretmedan den sjönk under sommaren. Avkylningen av marken under sommaren kan förklaras avökad nederbörd under sommaren som ger högre markfuktighet som ger en kylande effektgenom den så kallade jord-fuktighets återkopplingsmekanismen (soil-moisture feedback).Från detta kan vi dra slutsatsen att förändringar i enbart lufttemperatur inte kan förklara denhela observerade variansen av marktemperatur men att lufttemperaturen har en domineranderoll. Resultaten från denna studie indikerar således att förändringar lufttemperatur kananvändas som en indikator på marktemperaturförändringar i Abisko området.
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Acoustic Tomography inside a small surface layerArnold, Klaus, Ziemann, Astrid, Raabe, Armin 04 January 2017 (has links)
Acoustic travel time tomography is presented as an experimental technique for remote monitoring of spatially averaged meteorological quantities, such as the virtual air temperature and the horizontal wind speed. This ground based remote sensing technique uses the nearly horizontal propagation of sound waves in the atmospheric surface layer. Here the acoustic travel time tomography was applied by measuring the travel time at defined propagation paths between several sound sources and receivers. The resulting sound speed was used to obtain estimates of the meteorological parameters. Several measuring campaigns were carried out to compare the acoustically derived data with conventional systems. The results of a cross validation during a field experiment in autumn 2000 are presented, where receivers at different heights above the ground were used. / Die Akustische Laufzeittomographie wird als ein Verfahren zur Fernerkundung räumlich gemittelter Größen, wie der virtuellen Temperatur und der horizontalen Windgeschwindigkeit, vorgestellt. Dieses bodengebundene Fernerkundungsverfahren beruht auf der annährend horizontalen Schallausbreitung in der atmosphärischen Grenzschicht. Das hier angewendete Verfahren der Laufzeittomographie beruht auf der Bestimmung der Ausbreitungszeit von Schallwellen zwischen mehreren Schallsendern und -empfängern. Die daraus abgeleitete Schallgeschwindigkeit liefert eine Information über die interessierenden meteorologischen Parameter. Eine Reihe von Feldexperimenten wurde durchgeführt mit dem Ziel, die akustisch bestimmten Größen mit denen konventioneller Verfahren zu vergleichen. Hier werden die Ergebnisse eines Vergleiches im Herbst 2000 präsentiert, bei dem die Schallempfänger in unterschiedlichen
Höhen über dem Boden angebracht wurden.
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Fältmätningar av termisk komfort och luftkvalitet i kontorsrum i äldre temperaturreglerad stenbyggnadBoström, Hanna, Lindelöw, Hanna January 2022 (has links)
Personal på Högskolan i Gävle tycks periodvis uppleva dålig komfort ikontorsrummen på södersidan i skolans gamla kasernbyggnader. En undersökninggjordes därför på högskolan i april månad i tre kontor, ett med fönsterhuvudsakligen i norrläge och två med fönster huvudsakligen i söderläge. Syftet varatt kartlägga den termiska komforten och luftkvaliteten i de olika väderstrecken ochjämföra med gällande rekommendationer, bland annat genom att beräkna PMV vidolika tillfällen. Vidare undersöktes potentiella samband mellan ute- och inneklimatsamt tunna gardiners inverkan på termostat, värmeflöde och komfort. Den undersökta byggnaden är en äldre stenbyggnad med ovanligt välisoleradefönster och termostatstyrda, vätskeburna radiatorer. Byggnaden har FTX-ventilationmed ett till- och ett överluftsdon i varje kontorsrum. Mätningarna utfördes meddataloggrar som mätte lufttemperatur, relativ luftfuktighet och koldioxidhalt. I tvåav rummen mättes även globtemperatur. Utöver det mättes lufthastighet på tre olikahöjder i två av rummen samt ventilationsflödet i samtliga rum. Resultatet visade att inomhus- och utomhustemperatur har en relativt högkorrelation. Relativa luftfuktigheten var nästan alltid högst i norrläge, men i samtligarum var den låg – lägre än vad som rekommenderas i riktlinjerna. Soligt väderpåverkade temperatur och relativ luftfuktighet inomhus mest av alla vädervariabler,men personnärvaro och ventilation påverkade mer än utomhusklimatet. Kontor isöderläge hade som förväntat högre temperatur än i norrläge, och översteg deriktlinjer som finns för temperatur i kontor. Som följd av detta blev PMV högre isöderläge, tillfälligt högre än komfortgränsen 0,5, med ett högsta värde på 1,41. Kontoret i norrläge höll sig vid de undersökta tillfällena inom intervallet föraccepterat PMV med ett lägsta värde på -0,35. Detta tyder på att värme i söderlägeär ett större problem än kyla i norrläge. Lufthastigheterna blev låga i bådaväderstrecken. Ventilationsflödena visade sig vara 2/3 av det projekterade värdet,men ändå låg koldioxidhalten på en acceptabel nivå enligt riktlinjer. Gardiner påverkade komforten mer i söderläge än norrläge, men påverkade intetillräckligt mycket för att komma ner i en acceptabel komfortnivå vilket kan bero påatt de var av mycket tunt material. Det var svårt att se tydlig gardinpåverkan påtermostaten, men fråndragna gardiner kan leda till att termostaten reagerar påtemperaturökningar i ett rum snabbare. Däremot påverkades värmeflödet tydligaregenom fönstret av gardinerna. Skillnaden i värmeflödet vid för- och fråndragnagardiner blev 4,1 W. / Employees at University of Gävle seem to periodically experience suboptimalcomfort in south facing offices in the school’s old barrack buildings. Therefore, acase study was conducted in April in three offices, one facing north and two facingsouth. The aim of the study was to map the thermal comfort and air quality in thedifferent directions and compare these to the existing recommendations, includingcalculating PMV at different times. A potential correlation between out- and indoorclimate was also examined, as well as the effect of thin curtains on the thermostat, heat flux and comfort. The University of Gävle is an old brick building with unusually well insulatingwindows and thermostatically regulated, waterborne radiators. The building hasmechanical ventilation with heat recovery, and each office has one supply and oneover-air diffuser. The measurements were made with data loggers that measured airtemperature, relative humidity and carbon dioxide. The globe temperature was alsomeasured in two of the rooms. The air velocity on three heights was measured aswell in two of the offices and the ventilation flow was measured in all the rooms. The result showed that indoor- and outdoor temperature have a relatively highcorrelation. The relative humidity was almost always higher in the north facingoffice, but in all the rooms it was low – lower than the recommended guidelines.Sunny weather affected the indoor temperature and relative humidity the most of allthe weather variables, but presence of people and ventilation affected more than theoutdoor climate. South facing offices had as expected a higher temperature thannorth facing ones, and exceeded the guidelines concerning temperatures in offices.Due to that the PMV was higher in the south facing office, temporarily exceedingthe comfort limit of 0,5, with a maximum value of 1,41. The north facing office waswithin the limits during the measurements and had a minimum value of -0,35. Thisindicates that heat in the south facing office is more of a problem than coldness inthe north facing office. The air velocities were low in both directions of thebuilding. The ventilation flow turned out to be 2/3 of the intended value, but thecarbon dioxide content was still acceptable according to guidelines. Curtains influenced the comfort more in the south facing office than in the northfacing office, but they didn’t influence enough to get to an acceptable comfort level,which may be because of the very thin material. It was difficult to see a distinctinfluence from the curtains on the thermostat, but using no curtains could lead tothe thermostat responding faster to increases in temperature in a room. However,the heat flow through the window was influenced more distinctly by the curtains.The difference in heat flow when using curtains compared to no curtains was 4,1 W.
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Oxygen dynamics in the bottom waters of lakes: Understanding the past to predict the futureLewis, Abigail Sara Larson 20 May 2024 (has links)
Dissolved oxygen concentrations are declining in the bottom waters of many lakes around the world, posing critical water quality concerns. Throughout my dissertation, I assessed how bottom-water dissolved oxygen may mediate the effects of climate and land use change on water quality in lakes. First, I characterized causes of variation in summer bottom-water temperature and dissolved oxygen. I demonstrated that spring air temperatures may play a greater role than summer air temperatures in shaping summer bottom-water dynamics. I then characterized the effects of declining bottom-water oxygen concentrations across diverse scales of analysis (i.e., using microcosm incubations, whole-ecosystem oxygenation experiments, and data analysis of >600 widespread lakes). I found that low dissolved oxygen concentrations contributed to release of nutrients and organic carbon from lake sediments, potentially altering the role of lakes in global biogeochemical cycles. Importantly, I also found support for a previously-hypothesized Anoxia Begets Anoxia feedback, whereby bottom-water anoxia (i.e., no dissolved oxygen) in a given year promotes increasingly severe occurrences of anoxia in following summers. This finding demonstrates the need for forecasts of future oxygen dynamics in lakes, as management actions to preempt the first occurrence of anoxia will be more effective than actions to restore ecological function after oxygen concentrations have already declined. To build the capacity for such forecasts, I led a systematic review of ecological forecasting literature that characterized the state of the field, emerging best practices, and relative predictability of four ecological variables. Combined, my dissertation provides a mechanistic examination of the effects of climate change on water quality in lakes worldwide, ultimately helping to anticipate, mitigate, and preempt future water quality declines. / Doctor of Philosophy / Changes in climate and land use have caused dissolved oxygen concentrations to decline in many lakes around the world. These declines are concerning because low oxygen concentrations can cause substantial water quality problems. If we could better predict future water quality, we may be able to develop more effective lake management programs. To help meet this need, I analyzed how dissolved oxygen has mediated historical changes in water quality, and how dissolved oxygen may affect water quality in the future. I focused on bottom-water (rather than surface-water) dissolved oxygen, because bottom waters are more likely to experience very low oxygen concentrations that can lead to water quality problems. I started by assessing the drivers of summer bottom-water dissolved oxygen in 615 lakes. Across these lakes, spring air temperatures played a greater role than summer air temperatures in shaping summer bottom-water temperature and dissolved oxygen. I then characterized the effects of declining bottom-water oxygen concentrations using small-scale incubations in the lab, manipulations of oxygen concentrations in a whole reservoir, and data analysis across 656 lakes. I found that low dissolved oxygen conditions led to the release of nutrients and organic carbon from lake sediments, which may worsen water quality. Importantly, I also found support for a feedback effect, whereby low bottom-water dissolved oxygen in one summer perpetuates oxygen declines in following summers. This finding motivates the need for forecasts of future dissolved oxygen concentrations, as management actions to stop the first occurrence of low oxygen concentrations will be more effective than actions to restore water quality after oxygen concentrations have already started to decline. To build capacity for lake oxygen forecasts, I synthesized many published papers that have predicted future ecological states, and I documented proposed best practices in this emerging field. Ultimately, by advancing our understanding of how climate and land use change affect water quality in lakes worldwide, my dissertation research will help to anticipate, mitigate, and preempt future water quality declines.
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Návrh zařízení pro měření a hodnocení tepelného stavu prostředí / Device Proposal for Measurement and Evaluation of Environmental Thermal StateJanečka, Jan January 2012 (has links)
The thesis deals with evaluation of the environmental thermal state in closed rooms with people inside the room. The achievement of thermal comfort is related to thermal balance of human body. People are producing heat during their work, which has to be carried away from the body to surrounding area by radiation, convection, conduction, respiration and evaporation. The intensity of heat removal is influenced by environmental parameters, especially by air temperature, mean radiant temperature, air velocity and humidity. Personal factors as energy expenditure of human body and clothing resistance are influencing the intensity of heat removal as well. People are able to influence the thermal comfort by their behaviour in given environment, appropriate clothing and regulation of basic environmental parameters. CSN EN ISO 7730 standard states that environmental parameters should be estimated or measured. The operative temperature is than evaluated from collected data. This operative temperature is defined as the temperature of black enclosed area where the human body will be by convection and radiation sharing the same amount of heat as in real inconsistent environment. Nowadays on the market there is no cheap solution for sensor which is able to evaluate the operating temperature and could be used in buildings. There are a lot of professional sensors which have very high accuracy, but are very expensive. Therefore are mainly used only for research or for single and exceptional measurement of environmental thermal state in rooms. The thesis is therefore focused on proposal of suitable (compact) operative temperature sensor assembled according to valid regulations and standards. Emphasis is placed mainly on the sensor price together with guarantee of sufficient accuracy. The proposed sensor is providing information to control system which is than able to adjust the parameters of environment using appropriate way based on relevant requirements. Here is some space for energy savings due to possible continuous measurement and evaluation of environmental thermal state in different rooms. Therefore, during continuous measurement no unnecessary rooms overheating in winter as well as unreasonable cooling in summer should occur. This research and solution is than reflected in reduction of energy consumption used for building operation and subsequently reduction of the pollutants production. This issue is being watched with increasing interest. Another advantage is that whole system is able to work autonomously without human intervention. People no longer have to continuously adjust air temperature because the control system is able to evaluate the most appropriate adjustments based on objective data obtained from the sensor. The thesis includes subsequent verification of proposed sensor as well as the definition of sensor technical parameters including analysis of measurement uncertainties.
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