Due to the findings of extensive damage on geogrids used in a road embankment in northern Sweden, the Swedish Transport Administration (TRV) started to investigate the reason of these damages. Since the geogrids were installed at low temperature, below 0°C, it was suspected that the damages were connected the low temperature. To analyse whether low temperatures have an influence on the extent of installation damages, both a half-scale setup and temperature controlled tensile tests have been carried out on geogrids. In total five different types of geogrids have been tested; 3 extruded polypropylene geogrids, 1 woven PET geogrid, and 1 welded PET geogrid. All geogrids had an aperture size of approximately 35 mm and specified tensile strength of approximately 40 kN/m. The Half-scale tests was conducted by building a small road embankment inside a freeze container, at the Luleå University of Technology (LTU). The embankment contained crushed aggregate, type 0-70 mm, and geogrids. The purpose of the half-scale test was to simulate installation of geogrids at different temperatures and thereby investigate whether low temperatures have an influence on the rate of installation damages. The half-scale test was done for each type of geogrid at the temperatures: +20°C, -20°C and -30°C. First, the geogrid was covered by 150 mm of crushed aggregate. Then a vibratory plate (160 kg) was used to compact the crushed aggregate. After each installation, the crushed aggregate was removed carefully by vacuum suction. The geogrid was removed and then analysed by visual control and tensile tests conducted according to ISO 10319:2008 (wide width tensile test). Results from the half-scale tests indicate that 2 out of 5 of the tested geogrids were affected by the testing procedure. The results indicate that: -        one of the geogrids of polyprophylene (here referred to as G2) was more damaged at lower temperatures compared to installation at +20° C. -        the geogrid of woven PET (here referred to as G5) was less damaged at lower temperatures compared to installation at +20° C. Results for the other geogrids are either inconsistent or shows no significant variation of the measured parameters as function of temperature. Hence, these results cannot be interpreted as damage during installation. Temperature controlled tensile tests were done by tensile testing single strands from the geogrids to failure, inside a temperature controlled chamber. The purpose of these tests was to investigate how the strength properties of the geogrids are affected by low temperature. The test was repeated 5 times for each geogrid and temperature (+20°C, 0°C, -10°C and -20°C). Force and strain was measured during the tests. The results from the temperature controlled tensile tests show that the maximum strain decreases with lower temperature for all tested geogrids. The maximum strain decreased by 16% - 49% when the temperature dropped from +20°C to -20°C. The results show that the tensile strength increases with lower temperature for all tested geogrids except for the welded PET geogrid (here referred to as G1). For G1 the tensile strength decreased by approximately 7% at a temperature drop from +20°C to -20°C. For the woven PET geogrid (G5) and the polypropylene geogrids (G2-G3) the tensile strength increased between 13%-45% at a temperature drop from +20°C to -20°C. The E-modulus increased at lower temperature for all tested geogrids. The secant E-modulus at 2% strain increased by 13%-71% at a temperature drop from +20°C to -20°C. Summarized conclusions from the tests: Strength properties changed for all tested geogrids as the temperature decreased. All tested geogrids got stiffer at lower temperatures. The magnitude of the effects is different for different geogrids. The tensile strength increased with lower temperature for all tested geogrids except for the welded PET geogrid, which got lower tensile strength at lower temperature. The half-scale test indicates that the amount of installation damages at geogrids can be dependent of the temperature at installation. However, these indications can only be seen at two out of five tested geogrids. The effect cannot be connected to a specific step in the installation procedure and cannot be explained by the results from the temperature controlled tensile tests. The results from the half-scale test have a statistically low reliability since only one installation for each temperature and geogrid type was done. The compaction equipment used during the test was small, and had low compaction energy compared to a vibratory roller compactor commonly used in construction work. With respect to the discussion above, further studies should be focusing on developing the half-scale test. It is suggested that the test is scaled up to a full-scale test in order to simulate a real installation as close as possible. The test should also be conducted several times for each geogrid at each temperature in order to enable statistical analyses.

In this study we compare the ability of nitrifying activated sludge (NAS) and nitrifying trickling filter (NTF) wastewater treatment to remove the following contaminants: acetaminophen, caffeine, 1,7-dimethylxanthine, cotinine, ibuprofen, sulfamethoxazole, triclosan, and trimethoprim. Removal of acetaminophen, cotinine and caffeine was greater than 99% and removal 1,7-dimethylxanthine, ibuprofen, and triclosan was greater than 90% using NAS and NTF treatment. Sulfamethoxazole and trimethoprim were inadequately removed in both NAS and NTF treatments. The horizontal, subsurface flow treatment wetland showed removals of 45-89% for sulfamethoxazole and greater than 96% for trimethoprim. There was no statistical difference (P>0.05) between aeration, temperature and vegetation in the treatment wetland for the removal of sulfamethoxazole and trimethoprim.

Spring shock syndrome (SSS) is a condition where flowering and leaf development in peach and nectarine trees is delayed and those leaves that do develop are often small and discoloured. Trees experiencing spring shock syndrome yield poorly. To learn more about the development of this syndrome, this thesis has examined the influence of root zone temperature (RZT) and genotype on the growth of peach rootstocks and the scions grafted onto them. Other factors that influence the quality of peach seedling rootstocks were also examined. Initial trials examined the influence of Okinawa (a low chill cultivar) and Golden Queen (a high chill cultivar)rootstocks on the expression of SSS. Studies found that multiple stems could originate from either multiple seeds within a single stone or from axils originating from the base of cotyledons. The incidence of both conditions was heavily influenced by variety, thus suggesting that an active selection program based on the elimination of these traits would be beneficial to the stone fruit nursery industry. / Doctor of Philosophy (PhD)

Wind turbines operating in cold climate are exposed to periods of icing which lowers the plantprofitability by affecting the annual production. The loss of production has two components:The first (and most important) component is reduced power during operation due to disturbedaerodynamic properties of the blades. The second component is increased standstill. During this thesis project, methods to estimate production losses of a wind farm due to icinghave been developed, as well as a software tool to facilitate the use of these methods and thepresentation of the results. A method based on common metrological data and availableproduction data was desired, as modelling ice-related losses is expensive and may be inaccurate. The methods developed are based on using measured data for each turbine, such as activepower, temperature, wind direction and wind speed, and through this data describe theindividual turbine’s performance during different conditions. Production losses were thenestimated by comparing actual and expected power output (for the given wind speed). Thethesis then expanded on this basic concept by using reanalysis and mesoscale modelled data,which offers greater variety in the way estimating the losses may be performed, as well as theoption to derive losses for periods not covered by the production data. It was also important to develop a flexible and portable method that could incorporate newseasons of data or estimate losses for different wind farms with a completely differentconfiguration of turbines. The methods are developed using data from a wind farm in northern Sweden, consisting of 40Vestas V90 turbines and constructed a few years ago. It was found that eastern position in the wind farm and turbine altitude correlates with higherice-related losses, and that easterly winds relate to higher such losses than westerly winds. Thelosses during operation were estimated to 6.4 % of annual possible production and stops due toicing to 2.1 % of the total time. The losses figures are comparable to an earlier study performedin 2011 based on the same wind farm. The possibility of anti- or deicing systems for the wind farm and the profitability of such aninvestment should be further investigated as the wind farm is expected to continue operation fortwenty years or more.

ABSTRACT Dollar spot is a fungal disease that affects grass, and is caused by the fungus Sclerotinia homoeocarpa. It was discovered for the first time in Scandinavia in 2013. Dollar spot is a very serious disease of grass in the United States and a lot of money is spent to control the fungus. In the present study, dollar spot development in potted turfgrass, caused by four geographically distinct, Scandinavian isolates of S. homoeocarpa, was investigated at three different temperatures; 6 °C, 15 °C and 21 °C. The objective was to identify the lowest temperature of development of disease, and to establish possible differences among the isolates with regard to disease development. The isolates used originated from Denmark, Norway and Sweden. The grass samples that were inoculated with S. homoeocarpa came from two golf courses in Sweden, located in Uppsala and in Gävle, respectively. Turf grass was dug out and placed in pots, and subsequently inoculated with fungal hyphae from cultures of S. homoeocarpa. These pots were individually covered with plastic bags and placed in different climate chambers at set temperatures. At three time points (day 7, 14 and 21), the ratio of area infected grass to total grass-covered area was estimated. After all the results had been analysed, it was concluded that dollar spot had the most severe disease development at 6 °C. Differences in disease development of dollar spot were also observed among the four isolates at different temperatures. There was a link between geographical origin of an isolate and its optimum temperature for disease development, which may suggest that the isolates can have adapted to the environment in which they have established themselves. S. homoeocarpa is apparently able to proliferate at low temperatures. The present study demonstrates it should be able to infect grass and establish in turf grass even in a colder climate, and thus it is very likely that dollar spot has gained a foothold in Scandinavia, and that it is here to stay. With climate change taking place, i.e. increasing temperatures and precipitation, which in turn results in elevated humidity, the disease will be able to establish and spread yet more, because the fungus thrives in humid conditions. If the climate zones will continue to move northward in the Nordic countries, it will increase the potential for continued establishment and spread of dollar spot. / SAMMANFATTNING Dollar spot är en svampsjukdom som drabbar gräs och som orsakas av svampen Sclerotinia homoeocarpa. Under 2013 upptäcktes dollar spot för första gången i Norden. Dollar spot är en mycket allvarlig grässjukdom i USA och man spenderar massor med pengar för att bekämpa svampen. I denna uppsats har sjukdomsutvecklingen av dollar spot, från fyra geografiskt skilda isolat, undersökts vid olika temperaturer; 6 °C, 15 °C och 21°C. Detta för att hitta den lägsta tillväxttemperaturen hos svampen som orsakar sjukdomen och även för att upptäcka eventuell skillnad mellan de olika isolatens sjukdomsutveckling i gräs. Isolaten som använts i experimenten kom ifrån Danmark, Norge och Sverige. Gräsproverna som svampen S. homoeocarpa odlades på kom ifrån två golfbanor, från Uppsala respektive Gävle. Krukor med gräs inokulerades med S. homoeocarpa och dessa krukor placerades i klimatskåp som höll olika temperatur. Vid tre tidpunkter (dag 7, 14 och 21) lästes den infekterade gräsarean av. Efter att alla resultat hade sammanställts visade det sig att dollar spot hade den snabbaste och mest aggressiva sjukdomsutvecklingen vid 6 °C. Det fanns även skillnader i sjukdomsutveckling av dollar spot mellan de fyra isolaten vid olika temperaturer. Det fanns en viss koppling mellan geografisk härkomst och optimumtemperatur för sjukdomsutveckling hos isolaten, vilket kan tyda på att de kan ha anpassat sig till den omgivning som de etablerat sig i. Med de låga tillväxttemperaturer som svampen S. homoeocarpa klarar för infektion och etablering i grönytor är det mycket troligt att sjukdomen dollar spot fått fäste i Norden, och kommit för att stanna. Med de klimatförändringar som sker, dvs. ökade temperaturer och ökad nederbörd, som i sin tur medför förhöjd luftfuktighet, kommer sjukdomen att kunna breda ut sig ännu mer, eftersom svampen trivs vid hög luftfuktighet. Flyttas klimatzonerna högre upp i Norden kommer det att bidra till att utbredningen av dollar spot ökar.

The favorable wind recourses in many cold climate regions make them interesting for development of wind farms. However, with the cold climate come drawbacks due to icing. Production losses, fatigue loadings, ice throws and increased noise are some of the more severe issues that have to be addressed. Thus, wind power in cold climaterequires ice detectors both during the prospecting phase in the site assessment and during production for controlling of the turbines. This study aimed to evaluate six ice detector systems and their ability to detect time periods with ice and ice growth. The usability of the detector data for site assessment or controlling of the turbine was also discussed. The tested detectors were: the T 40 series from HoloOptics (HoloOptics), 0872F1 Ice Detector from Goodrich (Goodrich), LID-3300IP from Labkotec (LID), IceMonitor from SAAB Combitech (IceMonitor) and IGUS BLADcontrol from Rexroth Bosch Group (IGUS). Also a combination of the three anemometers Thies 4.3350.00.0000 from Adolf Thies GmbH & Co.KG (Thies), Vaisala WAA252 from Vaisala Oyj (Vaisala) and NRG Icefree3 from NRG Systems (NRG), used for wind measurements, has been analyzed for ice detection purposes. Data from field tests in Åsele municipality in the northern part of Sweden has been processed in MATLAB. Indications of ice and ice growth have been compared between the detectors to see how often they indicate concurrently. The measurements showed that the IceMonitor and the three anemometers indicated the occurrence of ice at the same time most of the time. The detectors with the ability to detect ice growth (Goodrich, LID, T44 and T41, IceMonitor) had a lot fewer concurrent indications. The correspondence between production loss time periods and the IGUS and T41 ice and ice growth indications were also low. Thus it was concluded that periods with ice were possible to find with a decent precision while ice growth and production loss periods were hard to find with any accuracy. The biggest limitation to the detectors’ functionality was the severe icing events that either hindered the detectors from working properly or broke them completely. None of the detectors were recommended for controlling of the wind turbines. If the reliability of the detectors during the more sever icing events could be increase they could however be used for site assessment to give a rough idea of the icing climate. / De gynnsamma vindar som finns i många regioner med kallt klimat gör dem intressanta för utveckling av vindkraftparker. Men med det kalla klimatet kommer nackdelar på grund av isbildning. Produktionsförluster, utmattningslaster, iskast och ökat buller är några av de mer allvarliga problem som måste åtgärdas. Således kräver vindkraft i kallt klimat isdetektorer både under prospekteringsfasen av området och under produktion, för styrning av turbinerna. Denna studie hade som syfte att utvärdera sex isdetektorsystem och deras förmåga att upptäcka tidsperioder med is och istillväxt. Detektorernas användbarhet vid projektering eller kontroll av vindturbiner diskuterades också. De testade detektorerna var: T 40-serien från HoloOptics (HoloOptics), 0872F1 Ice Detector från Goodrich (Goodrich), LID-3300IP från Labkotec (LID), IceMonitor från SAAB Combitech (IceMonitor) och IGUS BLADcontrol från Rexroth Bosch Group (IGUS). Även en kombination av de tre anemometrarna Thies 4.3350.00.0000 från Adolf Thies GmbH & Co.KG (Thies), Vaisala WAA252 från Vaisala Oyj (Vaisala) och NRG Icefree3 från NRG Systems (NRG), som används för vindmätningar, har analyserats för isdetektionsändamål. Data från fältstudier i Åsele kommun i norra delen av Sverige har behandlats i MATLAB. Indikationer på is och istillväxt har jämförts mellan detektorerna för att se hur ofta de visar samtidigt. Mätningarna visade att IceMonitor och de tre anemometrarna för det mesta indikerade förekomst av is samtidigt. Detektorerna med förmåga att detektera istillväxt (Goodrich, LID, T44 och T41, IceMonitor) hade mycket färre samtidiga indikationer. Överensstämmelsen mellan tidsperioder med produktionsbortfall, is (IGUS) och istillväxt (T41) var också låg. Således drogs slutsatsen att perioder med is var möjligt att hitta med en anständig precision emedan istillväxt och produktionsförlustperioder var svåra att hitta med någon större exakthet. Den största begränsningen av detektorernas funktionalitet var de svåra nedisningseventen som antingen hindrade detektorerna från att fungera ordentligt eller förstörde dem helt. Ingen av detektorerna rekommenderas för styrning av vindkraftverk. Om tillförlitligheten på detektorerna under de svårare nedisningseventen förbättras skulle detektorerna dock kunna användas vid projektering för att ge en ungefärlig uppfattning av isklimatet. / Vindforsk III: V-363 project

Abstract The purpose of the study was to examine the amount of cold exposure and factors affecting it at the population level in Finland, to determine what type of cold acclimatisation, if any, develops in urban residents in winter, and to find out whether cold acclimatisation or acclimation has a functional significance on psychological or physical performance. Tasks of low physical activity requiring attention and concentration (cognition, postural control) were assessed in cold. In a cross-sectional population study Finns aged from 25 to 74 years (n=6,951) were queried of their wintertime outdoor exposure duration and factors affecting it. In experimental studies seasonal cold acclimatisation (thermal responses) and its effect on cognition were assessed in the laboratory, where 15 young urban subjects were exposed to cold in winter and summer in bright or dim light. A controlled cold acclimation trial (n=10) was performed to study the effects of repeated exposures to cold on cognitive performance and postural control in young urban subjects. In the Finnish population the average amount of cold exposure in winter represents 4% of the total time. Most of the cold exposure occurs during leisure time and in outdoor occupations (agriculture, forestry, mining, industry, construction). Factors explaining increased occupational cold exposure were: occupation, age and a lesser amount of education. Factors associated with more leisure-time cold exposure were: being employed in outdoor occupations, being a pensioner, housewife, unemployed, practising physical exercise, and reporting at least average health. The experimental studies showed seasonal differences and aggravated thermal responses in urban residents in winter, but did not detect habituation responses typical of cold acclimatisation. In both seasons, acute moderate cold exposure resulted in positive, negative or mixed effects on cognition, reflected as changes in response times and accuracy. Simple cognitive tasks were impaired in cold, and in complex tasks both negative, positive and mixed effects were observed. It is suggested that cold exposure affects cognition through different mechanisms related to either distraction or arousal. Cold exposure increased postural sway by 70-90%, suggesting impaired postural control. Repeated exposures to moderate cold, reducing stress and discomfort and dampening physiological responses, did not markedly affect cognitive performance or postural control.

No description available.

<p>Space and water heating contribute over 50% of all the residential building energy consumption and are especially major energy consumers in the cold climates. Meanwhile, conventional furnaces and boilers with energy efficiency limited to below 100% dominate the residential heating in the cold climate, and the electric vapor-compression heat pump capacity and efficiency decline drastically at low ambient temperatures. Thermally driven ammonia-based chemical adsorption (chemisorption) heat pump (CSHP) systems utilize the reversible chemical reaction between the ammonia vapor and solid sorbent to generate heat pumping effect, which can provide heating with much higher energy efficiency than existing cold-climate heating technologies. Despite the significant potential of energy efficiency improvement from existing technologies, most studies in the literature on chemisorption heat pump systems focus on adopting the technology for refrigeration and energy storage applications, with very limited investigations available for using the technology for producing heating in cold climates. </p> This thesis study is thus conducted to characterize the operation behavior and performance of a CSHP system under cold ambient conditions and further identify optimal design and control for such systems to achieve high performance. In this study, both experimental and modelling approaches are pursued to investigate a CSHP heating system from the perspective of the sorption material using the multiple-stage LiCl-ammonia reactions, to the novel adsorber component with hybrid heat pipe heat exchanger, and finally to the performance of the complete heat pump system. The experimental studies are based on a prototype CSHP system tested to identify the chemical kinetics of the sorption material, as well as the transient performance of the adsorber and the system. The calibrated chemical kinetics are then used in the development of a transient adsorber model to analyze the operation and improve design of the adsorber. The heating COP of the prototype system was measured to be 0.75-1.16 under ambient temperatures of 8-20 C. Finally, a dynamic system model is developed based on the dynamic models of the adsorber and other components in the system. The system model is validated against the experimental data and used to analyze the detailed energy flow and operation dynamic. Based on the inefficiencies revealed by the simulation of the current prototype system, an improved system design with reduced thermal mass and heat loss is introduced. Simulation of the improved system results in heating COP of 1.17 to 1.23 under -13.9 C to 8.3 C ambient, respectively.

In recent years, the treatment of phosphorus in Nyland's water treatment plant (located in Åre municipality) has been substandard. The problem has persisted despite attempts to lower the concentration to meet the emission requirements. A desire to find alternative, more environmentally friendly treatment methods has therefore been expressed from the municipality.Aside from the requirements, there is a desire to keep nutrient levels in the recipient (Indalsälven) low to preserve its natural state. A recognized method for treating wastewater is the use of constructed wetlands, where the characteristics of a natural wetland are enhanced and taken advantage of.The assessment of which type of constructed wetland that would be most beneficial to apply, was done by rating and weighting a number of characteristics of importance for lowering the phosphorus concentration. A first-order area-based model was used to estimate the size of the wetland.This report found that there is a suitable site to build a free water surface wetland in the vicinity of the water treatment plant. The wetland would act as a polishing step in the treatment train. As there is an element of uncertainty in treatment performance when a living ecosystem as wetlandis used, it is advised to enlarge this study and include more design aspects to refine the layout and configuration. / <p>2023-06-02</p>