With a goal to be able to cast a concrete slab and to dry out the moisture in the concrete in a faster way. To meet the requirement for certification of green building construction, the concrete slab must be dried out to an approved level before it is covered with a flooring material. This sets becomes a problem when today's buildings must be constructed quickly. Normal concrete slabs with 0.55 w/c take several years to dry out to the required levels. In this study we have looked at the parameters of concrete casting and how these affect the drying time. Calculations have been made in software with respect to weather, coverage, depth of water cement number and temperature at casting. Alternative methods have also been investigated such as separating the edge stiffening from the slab. The results show that changing the w/c or pouring with a cold concrete improves the drying process a lot.

Satellite radiometers are used to remotely measure properties of the Earth's surface. Radiometers enable wide spatial coverage and daily temporal coverage. Radiometer measurements are used in a wide array of applications, including freeze/thaw states inference, vegetation index calculations, rainfall estimation, and soil moisture estimation. Resolution enhancement of these radiometer measurements enable finer details to be resolved and improve our understanding of Earth. The Soil Moisture Active Passive (SMAP) radiometer was launched in April 2014 with a goal to produce high resolution soil moisture estimates. However, due to hardware failure of the radar channels, prepared algorithms could no longer be used. Current algorithms utilize a narrow spatial and temporal overlap between the SMAP radiometer and the SENTINEL-1 radar to produce high resolution soil moisture estimates that are spatially and temporally limited. This thesis explores the use of resolution enhancing algorithms to produce high resolution soil moisture estimates without the spatial coverage limitations caused by using multiple sensors. Two main approaches are considered: calculating the iterative update in brightness temperature and calculating the update in soil moisture. The best performing algorithm is the Soil Moisture Image Reconstruction (SMIR) algorithm that is a variation of the Radiometer form of the Scatterometer Image Reconstruction (rSIR) algorithm that has been adapted to operate in parameter space. This algorithm utilizes a novel soil moisture measurement response function (SMRF) in the reconstruction. It matches or exceeds the performance of other algorithms and allows for wide spatial coverage.

One of the benefits of colonial living in insect societies is the ability to build a nest which enables the maintenance of a homeostatic microenvironment. The detrimental and uncertain effects of fluctuating ambient conditions are thus avoided. An extensive amount of work has documented the regulation of respiratory gases and temperature by honeybee (Apis mellifera) colonies but relatively little is known of their water relations. Nest humidity influences the fitness of the honeybee colony by affecting adult and brood mortality, microbial and parasitic growth, nectar concentration and thermoregulation. This study aims at determining whether honeybee colonies are able to actively regulate humidity within their nest or whether humidity is stabilised merely as consequence of other socially regulated parameters. As a first step in understanding water relations in a hive, the daily, seasonal and two-dimensional humidity patterns are described in diverse contexts: various subspecies, nest architectures, ambient climates and colony conditions. The humidity in the brood nest of a healthy honeybee colony does not show a daily pattern: mean hourly RH remains between 50 and 60 % and high vapour pressure deficit results in a large evaporative capacity. Two-dimensional humidity patterns show that a vapour pressure gradient exists from the central brood area to the periphery of a hive. This finding suggests possible active regulation by workers and to test this idea we determined the behavioural response of a group of workers to a humidity gradient. Young honeybee workers in the absence of brood exhibit a weak hygropreference for approximately 75% RH. When brood is present the expression of this preference is further weakened, suggesting that workers tend to the brood by distributing evenly in the gradient. In addition, fanning behaviour is shown to be triggered by increasing humidity adding to our understanding of this behaviour. Although these results suggest that humidity in honeybee colonies is actively controlled by workers, passive mechanisms are also involved in the observed patterns. Cocoons that are spun by the larvae accumulate in cells and these hygroscopic cocoons contribute to passive stabilisation of humidity. Old comb containing cocoons absorb 11 % of its own mass in water when placed in high humidity and this water can readily evaporate into the atmosphere when humidity decreases. This buffering effect may increase brood survivorship by maintaining a high and stable humidity in the brood cells. This study contributes to our understanding of the complex mechanisms that govern microclimatic regulation in social insect nests and specifically the active and passive mechanisms that ensure homeostasis of honeybee nest humidity. Copyright / Dissertation (MSc)--University of Pretoria, 2008. / Zoology and Entomology / unrestricted

Soil is the most widely used material in the construction of various civil infrastructure. Various types of soils are extensively used in its natural or compacted form in the construction of dams, canals, road and railway subgrades, and waste containment structures such as soil covers and liners. These infrastructure and foundation soils are exposed to the influence of environmental factors. In the permafrost and seasonally frozen regions, soils can be in different states (e.g., saturated or unsaturated, frozen or thawed, or combinations of them) due to the variations in moisture content and temperature. The soil-water characteristic curve (SWCC), which is the relationship between soil water content and suction, is used in the interpretation and prediction of unsaturated soils behavior. Similarly, the soil-freezing characteristic curve (SFCC), which is the relationship between unfrozen water content and subzero temperature, is used in the prediction and interpretation of frozen soils behavior. In this thesis, the SWCC and SFCC of two Canadian soils (i.e. Toronto silty clay (TSC) and Toronto lean clay (TLC)) were extensively investigated for better understanding the fundamental relationship between SWCC and SFCC. The soil resilient modulus (MR) is a key material property used in the rational design of pavements. Experimental investigations were undertaken to determine the MR of five Canadian soils (i.e., TSC, TLC, Kincardine lean clay (KLC), Ottawa Leda clay (OLC), and Indian Head till (IHT)), considering the influence of moisture and temperature, with the aid of an advanced triaxial testing equipment. Two simple models were proposed for estimating the MR of frozen soils, in this thesis. In addition, an artificial neural network (ANN) model was developed for estimating the MR of the five Canadian soils considering various influencing factors. The conclusions from the various studies in this thesis are succinctly summarized below. (1) Four expressions (i.e. power relationship, exponential relationship, van Genuchten equation, and Fredlund and Xing equation) that are widely used for representing the SFCC were selected for providing comparisons between the measured and fitted SFCCs for different soils. The results suggest that the exponential relationship and van Genuchten equation are suitable for sandy soils. The power relationship reasonably fits the SFCC for soils with different particle sizes, but not for saline silts. The Fredlund and Xing equation is flexible and provides good fits for all the soils. (2) The SFCC and SWCC of TSC and TLC were experimentally determined, analyzed, and compared. Many factors influence the reliable measurement of SFCC, which include sensors’ resolution and stability, sensor calibration for each soil, and thermodynamic equilibrium condition. The hysteresis of SFCC for the two soils is mainly attributed to the supercooling of pore water. The quantitative dissimilarity in the measured SFCC and SWCC may be attributed to specimen structure variations during compaction and saturation, and during freezing / thawing processes, and cracks formation due to sensors insertion. In addition, some fundamental differences may exist between the drying / wetting and freezing / thawing processes, resulting in dissimilarity. (3) Two novel models were proposed for the estimation of MR of frozen soils. The semi-empirical model extends the mechanics of unsaturated soils and employs SFCC for prediction. Several coarse- and fine-grained saturated soils were used to validate this model. The empirical hyperbolic model was proposed considering that the frozen MR versus subzero temperature relationship resembles hyperbola. This model was validated on coarse- and fine-grained soils under saturated / unsaturated conditions. The hyperbolic model has wider application since it can be used for both saturated and unsaturated frozen soils. Both the models are simple and promising. (4) The MR of five Canadian soils subjected to wetting and freezing was determined by using the GDS ELDyn triaxial testing system. A freezing system was established for controlling the desired testing temperatures within the soil specimens. The results suggest: (i) The effect of subzero temperature on the MR is significant. (ii) For TLC, KLC, OLC, and IHT, the frozen MR versus subzero temperature relationship of the saturated specimen typically has steeper slope than specimen at the optimum water content, for the temperature range from 0 to -5 °C. (iii) The effect of stress levels on the frozen MR depends on soil type, water content, and subzero temperature. Lastly, (iv) Loading frequency does not show a significant influence on the frozen MR. (5) The MR of the five Canadian soils was determined considering wetting and freeze-thaw (F-T) conditions. The results suggest: (i) The F-T cycles result in weak soil structure due to reduction in suction, particles movement, loss of cohesion, and formation of cracks / channels. (ii) The critical numbers of F-T cycles were determined as 1, 1, 2, and 1 for TLC, KLC, OLC, and IHT at the optimum water content, respectively. (iii) The percentage of reduction in MR after the critical number of F-T cycles was strongly related to the plasticity index for specimens tested at the optimum water content. (iv) The wetting process results in the decrease in suction and enlargement of soil pores. Consequently, relatively low MR values were measured at high water contents, and the effect of F-T cycles becomes insignificant. Finally, (v) The effect of stress levels on the MR was dependent on the initial water content of the specimen and soil type.

Cotton (<i>Gossypium hirsutum</i> L.) is a low residue crop, that may not provide sufficient surface residue to reduce erosion and protect the soil. A winter annual cover crop could alleviate erosion between cotton crops. Field experiments were conducted to evaluate selected winter annual cover crops for biomass production, ground cover, and N assimilation. The cover crop treatments were monitored under no-till and conventional tillage systems for the effects on soil moisture, cotton yield and quality. Six cover crop treatments, crimson clover (<i>Trifolium incarnatum</i> L.), hairy vetch (<i>Vicia vilosa</i> L.), hairy vetch and rye (<i>Secale cereale</i> L.), rye, wheat (<i>Triticum aestivum</i> L. amend. Thell.), and white lupin (<i>Lupinus albus</i> L.), and two tillage systems (conventional and no-till) were arranged in a split-plot design with four replications. Cover crop biomass production depended on climate conditions. Ground cover percent and N assimilation by cover crops were directly correlated with the amount of biomass produced within cover crop treatments. Within a range of near average winter temperatures, all cover crops except lupin provided enough ground cover to comply with federal conservation tillage standards. More ground cover remained on the soil surface further into the cotton growing season following the small grain treatments compared to the legume cover crop treatments. Soil moisture was higher (P < 0.05) under no-till compared to conventional tillage during the periods of drought in 1997. Tillage system had no effect on cotton yield and quality in 1995 and 1996. High cover crop biomass production coupled with an extended cotton growing season in 1995 resulted in higher lint yield for cotton grown following the hairy vetch + rye treatment compared with cotton grown following the wheat treatment. High heat unit accumulation in October 1995 led to the over maturity of cotton fiber and high micronaire values for cotton grown following all cover crop treatments. The high micronaire values (5.0 - 5.2) for cotton grown in all cover crop treatments except hairy vetch + rye (4.9), resulted in a market price deduction of 1.4 cents per kilogram of lint in 1995. All cover crops used in this experiment, with the exception of lupin, provided enough ground cover within a range of average winter temperatures to meet federal conservation requirements. The winter annual cover crops in a no-till cotton production system provided greater soil moisture conservation during periods of drought, and produced cotton yields and quality comparable to conventional tillage. / Master of Science

I detta examensarbete som utfördes under vårterminen 2019 på Malmö universitet undersöktes hur temperaturförändringar i det omgivande klimatet påverkar mätresultat vid fuktmätningar i betong. Vid fuktmätningar i betong, i fält, används metoden borrhålsmätning. Vid borrhålsmätningar borras ett hål i en betongplatta eller ett betongbjälklag, därefter monteras ett mätrör i hålet sedan monteras en fuktgivare. Detta görs vanligtvis enligt RBK-systemets, Manual – Fuktmätning i betong. För att undersöka hur temperaturförändringar i det omgivande klimatet påverkar mätresultatet vid fuktmätningar utfördes försök där en provkropp gjöts med bascement, vct 0,38. Åtta termistorer gjöts in på olika djup för att kunna logga temperaturen på olika djup i provkroppen vid en temperaturförändring i det omgivande klimatet, dessa mätvärden jämfördes sedan med den loggade temperaturen samt de loggade RF-värdena från fuktgivaren. Fuktgivaren som användes vid försöken var Vaisala HMP110. För att utföra kontrollerade temperaturförändringar utfördes försöken i en fuktgenerator. Tre huvudförsök utfördes, ett med en momentan temperaturförändring i det omgivande klimatet, ett med en långsam temperaturförändring i det omgivande klimatet samt ett där okontrollerade temperaturförändringar i det omgivande klimatet skedde.Resultaten från dessa försök visar att när en temperaturförändring i det omgivande klimatet sker mäter fuktgivarens temperatursensor betongens faktiska temperatur med god noggrannhet, men ett felaktigt RF-värde kommer att ges om en avläsning av mätvärdet sker innan en ny temperaturjämvikt har etablerats. Resultaten visar även att vid omräkning av RF till RF vid 20°C, enligt RBK-systemet, förvärras mätfelet när temperaturen inte är stabil i det omgivande klimatet. / In this bachelor thesis a study is done to see how ambient climate changes impacts the measurement results during moisture measurements in concrete. The method of measurement used is borehole measurements according to the RBK-system, Manual – Fuktmätning i betong. The experiments were conducted in a laboratory environment on a concrete slab, which was casted with bascement and had a w/c ratio of 0,38. To see how well the moisture meter performed during ambient climate changes eight thermistors were cast into the concrete slab to log the temperature at different depths of the concrete during the ambient climate changes.The results show that the moisture meter does read the actual temperature of the concrete during an ambient climate change, however the ambient climate change had an impact on the measurement results of the relative humidity (RH). If a snapshot measurement of the RH is done after a temperature change in the ambient climate, an incorrect measurement result of the RH is obtained. When the obtained RH is converted to RH at 20°C the fault will get enlarged. To obtain a correct RH measurement when a field measurement is done, a logged measurement should be conducted.

The conversion of ammonia nitrogen to nitrite and nitrate forms of nitrogen has aroused much attention in the past and continues to receive much of the energy of the present day researcher. It has been known for many years that the phenomenon of nitrification is almost in its entirety a biological process. In 1862, Louis Pasteur demonstrated the microbiological nature of the oxidation of alcohol to acetic acid. He suggested that the oxidation of ammonia might be of similar nature. In 1877 this suggestion was verified by schloesing and Muntz, and for the next ten years the process received much attention, culminating in 1891 in the isolation of the responsible organisms by Winogradsky.

Plant responses to different soil moisture regimes have been extensively studied. Because of interactions between the soil, plant and climatic factors, few convincing generalizations concerning the influence of soil water on the transpiration of water by plants have been established. Generally single factors or at most the interaction of two have been studied at any one time. Useful theories describing the conditions of water retention in plant tissues and movement of water through plants have been proposed. Equally useful theories have been suggested for describing the retention and transmission of water in soil. The integration of these theories and their applications to evapotranspiration remains to be elucidated. This indicates a need for studying the total free energy path that causes water transport from soil to atmosphere through plants. Two interrelated categories of processes or factors, atmospheric desiccation and rate of soil water uptake, need to be studied simultaneously. The energy status of plant water, herein called total plant water potential, in conjugation with soil water potential appears to be critically involved in the process of water transfer through the soil-plant-atmosphere system. Plant water potential is the best criterion for detecting the degree of plant water stress. By studying water retention and flow properties of both plants and the supporting soil, one may be able to find relations that will help to predict the behavior of plants as they remove water from soil. For example, water retention characteristics of drought resistant plants may suggest reasons why some desert plants survive desiccating conditions that cause death to more succulent plant species. The major objective of this study was to investigate the influence of soil water potential and atmospheric environment on both the transpiration rates and components of the plant water potential.

Two field experiments were carried out. In the first experiment, 13 variables were studied for 3 inbred groups as influenced by genetic differences, source of pollen, soil moisture, fertilizers , and size of bulbs. Path-coefficient analysis was made of var ious insect pollinators influencing seed yield in different inbreds, and of components of seed production in all inbreds together. In the second experiment, 4 variables were studied for one male-sterile inbred and one male-fertile inbred as influenced by soil moisture and fertilizers. Genetic differences among inbreds were the most important source of variation in seed yields. This points out that a major portion of the onion seed problem could be solved through plant breeding. The inbreds differed very significantly in t heir attractiveness to pollinating insects, probably as a result of varying genetic vigor which influenced nectar formation. Most of the inbreds had negative correlation or no correlation between the number of honey bee nectar collectors and seed yield. The separation of correlation with honey bee nectar and pollen collectors into components of direct and indirect effects indicates that the number of pollinating insects was excessive for all inbreds in the experiment. Negative direct effects on seed yield and negative indirect effects through percent fertilized flowers and seeds per fertilized flower disclose some important aspects as possible causes for low onion seed yields: 1. Depletion of assimilated food needed for the development of fertilized ovules through an overdraw on nectar by nectar collectors. 2. Water deficit affecting fertilized developing ovules due to increased transpiration resulting from overhandling of flowers by honey bees, especially by pollen collectors, which through nervous search for pollen on male- sterile lines might cause enough physical damage to increase transpiration even at low visitation levels. At high visitation levels, pollen collectors might also harm male-fertile lines. 3 . Removal of pollen from the stigmas of male-sterile flowers by high populations of pollen collecting honey bees. Compatibility of the pollen parents with the male-sterile inbreds was influenced by soil moisture levels. At high moisture, M611C increased seed yields while B12115-2C decreased them. At low moisture the reverse was true. In the first experiment there was no significant yield response to varying soil moisture levels due to contrasting effects of high soil moisture on compatibility with pollen parents. In the second experiment, the pollen parent B2215C was used and a significant favorable response to high soil moisture was obtained. Salinity aspects and the effects of indiscriminate use of fertilizers were tested through the method of fertilizer placement. While fertilizers reduced seed yield , high soil moisture tended to reduce the negative effects of nitrogen and to produce favorable response to phosphorus. Seed yield followed the trend in plant survival as affected by the induced salinity x moisture relationships. The size of bulbs had a great influence on seed yields, mainly through an increased number of umbels per plant. It seems that the number of umbels per plant had more influence on the number of flowers per row than did the number of flowers per umbel. Path-coefficient analysis of components of onion seed production indicates that the percentage of fertilized flowers is the most important criterion for selection to improve seed yield. It would be ideal to combine both high percentage of fertilized flowers and large number of flowers per umbel, but if compromise has to be made, selection would best be considered on the basis of greater percentage of fertilized flowers in the umbel. Plants which have a large percentage of fertilized flowers can be easily detected at the pre-seed harvest stage.

The effects of grazing and moisture availability on the competitive interactions of intermediate wheatgrass (Thinopyrum intermedium (Host) Barkw. & D.R. Dewey) and western wheatgrass (Pascopyrum smithii (Rhydb.) A. Love) were examined under a short-duration grazing system in central Utah. The fate of tiller cohorts was observed at approximately monthly intervals at the interface between patches of these two rhizomatous grasses and in monospecific stands. The effects of short-duration grazing, clipping of western wheatgrass following grazing to achieve levels of utilization equivalent to that of intermediate wheatgrass, irrigation, and removal of the competitor were assessed in terms of the recruitment, longevity, and mortality of ramets of both species. The effects of severance of clonal connections and defoliation on the performance of young shoots of both species were also studied. The tiller dynamics of the two species differed greatly. Maximum life span of intermediate wheatgrass tillers was approximately 18 months, while that of western wheatgrass tillers exceeded the 3.5-year observation period. Tiller turnover was higher in intermediate wheatgrass than in western wheatgrass. Defoliation tended to increase the mortality risk of intermediate wheatgrass ramets but not that of western wheatgrass ramets. Supplemental water had the opposite effect. Irrigation increased the probability of ramet survival for intermediate wheatgrass during the growing season but led to higher winter mortality for western wheatgrass ramets. During the four years of this study (1987-1990), western wheatgrass was the competitive dominant species. Recruitment of intermediate wheatgrass ramets at the interface was reduced compared to monospecific stands while that of western wheatgrass was enhanced. The mortality of intermediate wheatgrass tillers increased as a result of competition with western wheatgrass but only when plants were grazed. Competition had little effect on the mortality of western wheatgrass ramets. The competitive ability of intermediate wheatgrass versus western wheatgrass improved when both species were grazed heavily and when plants were irrigated.