No description available.

Fatigue assessment of welded joints using finite element methods is becoming very common. Research about new methods is being carried out every day that show a more accurate estimation of the fatigue life cycle than the previous ones. Some of these methods are investigated in this thesis for a thorough understanding of the weld fatigue evaluation process.The thesis study presents several methods as candidates for analysis of selected case studies for comparison. The sensitivity of methods towards FE model properties was studied. The ease of implementation for further automatization of the method was highly considered from the early stages of the project. A comparison study amongst feasible methods was then performed after analysis.The selected three case studies provided a wide range of difficulties in terms of geometry and loading and made them suitable for the methods to be evaluated. It should be noted that case studies only with fillet welds were considered during the literature study and analysis. Implementation of some methods on a case study where they have not previously been tested before gave a challenging task during the analysis phase. The proposed method after comparison and ranking of the methods based on several criteria such as accuracy, robustness, etc. was the hot spot stress method. The main advantages of this method are its low computational time, less complexity during both pre- and post-processing, and the ability to work for both solid and shell models.Finally, the report gives a walk-through of several functionalities of the post-processor tool built to enhance workflow for the hot spot based fatigue assessment of welds. Pseudo-codes for some functions of the tool are given for clarity. A summary of the workflow is presented as a flowchart. The outputs of the case studies were then evaluated using the tool and compared with the manual evaluation to check the effectiveness of the tool on different scenarios. The tool shows flexibility in handling different types of weld geometry with good agreement to the results obtained manually but only for welds lying on a flat surface. Some of the advantages of the tool are its capability to handle multiple welds simultaneously and the flexibility to the user in selecting the way the results are presented. Most of the postprocessing steps are automatized, while some require user inputs.

Wind power has been growing rapidly in Sweden over the past decade as the country focuses on 100% renewable energy by 2040. The thesis seeks to investigate if increased wind power has had a dampening effect on the hourly day-ahead spot prices in Sweden’s bidding area SE3. An empirical approach is undertaken to estimate the impact that wind power has had onprices. Hourly spot prices for bidding area SE3 for the years 2016-2019 are analysed using a multivariate regression method. Other important variables like hydropower and nuclear production which are very significant in the Swedish electricity market are controlled for in the study. The results confirm that in the period 2016-2019, bidding SE3 experienced a merit order effect on price caused by increased wind power. The study shows that a 1% increase inwind power production is estimated to have decreased SE3 hourly spot prices by between 0.0268% and 0.059% between 2016 and 2019.

Soybeans (Glycine max L.) are an important crop globally for its food, feed, and oilpurposes. It is impacted by many diseases, including Cercospora sojina, the causal agent of Frogeye Leaf Spot (FLS). Chemical and cultural controls to this fungal pathogen are insufficient, so genetic resistance must be acquired for adequate control. To this end, two recombinant inbred populations were screened in a greenhouse setting for their relative resistance to FLS, and their genomes were analyzed for contributing quantitative trait loci (QTL). In the Essex ́ Forrest population, one QTL was discovered on chromosome 13, and in the Forrest ́ Williams 82 population, two QTL were identified on chromosomes 6 and 11, respectively. These populations were then also screened in a field setting for agronomic traits. These traits were analyzed to detect one superior line for both FLS resistance and advanced agronomic traits, F ́W 125. This line should be used in future breeding projects to increase FLS resistance and reduce linkage drag for other desired characteristics.

京都大学 / 新制・課程博士 / 博士(理学) / 甲第23012号 / 理博第4689号 / 新制||理||1672(附属図書館) / 京都大学大学院理学研究科物理学・宇宙物理学専攻 / (主査)准教授 野上 大作, 教授 太田 耕司, 教授 一本 潔 / 学位規則第4条第1項該当 / Doctor of Science / Kyoto University / DFAM

Debatten kring ordningsvakternas roll gällande trygghetsarbetet i samhället har blivit allt mer aktuell. Fler och fler kommuner ansöker om ordningsvaktsfördordnanden för att patrullera på otrygga platser, trots att detta ligger utanför ordningsvakternas traditionella arbetsområde, samtidigt som deras inflytande på tryggheten står något oklar. Syftet med denna studie är att utvärdera effekten av implementerandet av ordningsvakter på ett centralt beläget stationsområde i Järfälla kommun. Studien baseras huvudsakligen på en baslinje- och en eftermätning i enkätform som genomförts innan och efter implementerandet av ordningsvakter, men också på kriminalstatistiken från det studerade området. Analysen som genomförts med hjälp av statistiska sambandsanalyser i SPSS har fokuserat på att se hur tryggheten utvecklats i ordningsvakternas förordnandeområde, med särskilt fokus på utvecklingen mellan olika åldersgrupper och mellan män och kvinnor. Dessutom har utvecklingen av den registrerade brottsligheten analyserats genom kriminalstatistiken. Resultatet indikerar att tryggheten inte ökats av insatsen. Däremot har konsekvenserna av otryggheten minskat, och då främst bland kvinnor. Vidare antyder kriminalstatistiken att den registrerade brottsligheten legat relativt konstant de senaste 10 åren, och att implementeringen av ordningsvakter inte haft någon mätbar effekt på de brottstyper som inkluderats i studien. Framtida studier bör likt denna genomföra mätningar vid flera tillfällen över tid med en implementerad trygghetåtgärd däremellan för att bättre kunna uttala sig om åtgärdens direkta påverkan på tryggheten. Samtidigt borde ordningsvakter som trygghetsåtgärd ifrågasättas, både med tanke på evidensbrist gällande deras effekt på tryggheten, men också med anledning av att brottsförebyggande och trygghetsskapande arbete går utanför deras arbetsbeskrivning och ansvarsområde. / The ongoing debate on security guards role in society is becoming more and more stressed. The phenomena has spread through several Swedish counties who´s intentions are to hire security guards for assignments like safety keeping and patrolling which doesn´t comply with their ability and training as security guards. The aim of this study is to evaluate the effects of the implementation of security guards on a central located train station in Järfälla county. The study is based on a former research that used survey methods for the gathering of data. The data was comprised with the help of a two time measure, one before the implementation of security guards and one after. The local criminal record has also been used as data for this study. The study has analyzed these different data through a statistical pattern program called SPSS. The program was used to measure how peoples view of safety had changed in the given location with focus on age and gender. The results indicated that there hasn´t been any change toward the view of safety after the implementation of security guards. Although the consequences of a person’s unsafety has decreased, which can be seen in women especially. Furthermore it can be seen through the local criminal record that the level of crime has been relatively stable the last 10 years. This suggests that the implementation of security guards hasn´t had the effect on crime it presumes to have. Future studies should continue to carry out measurements over time with an implemented security measure in between. This to better be able to express an opinion about the direct impact of the measure on the safety. At the same time security guards as security measure should be challenged, both considering the lack of evidence about their effect on safety, but also regarding that crime prevention and preventing security goes beyond their job descriptions and responsibility.

Annual bluegrass (Poa annua L.) is the most problematic weed to control in creeping bentgrass (Agrostis stolonifera L.) putting greens.  The objective of this study was to transition a mixed putting green stand of annual bluegrass and creeping bentgrass to a monoculture by using fertilizers and plant growth regulators that selectively inhibit annual bluegrass.  A 25 year old loamy sand rootzone research green, planted with \'Penn-Eagle\' creeping bentgrass, with roughly 45% initial annual bluegrass coverage was utilized.  The biweekly application of ammonium sulfate (4.8 kg ha-1) with treatments of ferrous sulfate at rates of 0, 12.2, 24.4, and 48.8 kg ha-1 and in combination with seaweed extract (12.8 L ha-1) or paclobutrazol (0.37 L ai ha-1 spring and fall; 0.18 L ai ha-1 summer) were applied March to October, 2011 and 2012.  Plots receiving the highest rate of ferrous sulfate resulted in annual bluegrass infestation declines from an early trial amount of 45% to a final average of 20% but also resulted in unacceptable late-summer events of annual bluegrass collapse.  The ferrous sulfate medium rate resulted in a smooth transition from early-trial annual bluegrass infestation of 45% to an end of trial infestation of 20% and had the highest putting green quality.  Previous research has reported that consistent use of paclobutrazol can effectively and safely reduce annual bluegrass infestations.  In this trial annual bluegrass was reduced to 9% infestation after three months of application.  Two unexpected observations from this trial were that ferrous sulfate, applied at medium to high rates, significantly reduced silvery thread moss (Bryum argentum Hedw.) populations and occurrences of dollar spot (Sclerotinia homoeocarpa F. T. Bennett) disease.  Dollar spot control with ferrous sulfate has not previously been reported in the literature, so additional studies were designed to investigate this phenomenon further.  A creeping bentgrass putting green study was conducted to determine if sulfur, iron, or the two combined as ferrous sulfate decreases dollar spot activity.  Ferrous sulfate resulted in the highest turf quality and suppressed S. homoeocarpa infection, even during high disease pressure.  Fe-EDTA suppressed dollar spot infection as well as ferrous sulfate but quality declined to unacceptable levels during the summer, due to Fe-EDTA only.  Sulfur did not affect or increased S. homoeocarpa infection, indicating that a high and frequent foliar rate of iron is responsible for dollar spot control.  An in-vitro study was conducted to determine if agar pH in combination with iron concentrations affects mycelial growth of S. homoeocarpa.  Results from this trial indicated that 5.4 agar pH is an optimal pH for mycelial growth.  The 10 to 100 mg iron kg-1 concentration had little effect on mycelial growth at 5.0 and 5.5 pH, but increased growth at 4.5 and 6.5 pH.  As the iron concentration was increased from 10 to 100 to 1000 mg kg-1, mycelial growth decreased or stopped.  Our final conclusions are that seasonal biweekly foliar applications of the medium rate of ferrous sulfate (24.4 kg ha-1) safely and effectively reduced annual bluegrass infestation out of a creeping bentgrass putting green, while also effectively suppressing silvery thread moss and dollar spot incidence. / Master of Science

Risks associated with fluctuating exchange rates affect investment cost and investor profitability. Approximately 50% of firms in emerging markets have significant exposure to fluctuating exchange rates. Grounded in principal-agent theory (PAT), the purpose of this case study was to explore hedging strategies to mitigate risks of fluctuating exchange rates. The population comprised a census sampling of 12 bank hedgers (risk managers and controllers) in Dar es Salaam in Tanzania, East Africa. Data collection involved semistructured interviews, casual observations of the work environment, and analysis of reports including risk management, internal control, and compliance policies. Data were analyzed by coding and grouping narrative segments and significant statements into themes of participants' experience in hedging exchange rate risks. Method triangulation and member checking were used to increase the trustworthiness of interpretations. Four themes emerged directly related to the PAT conceptual framework: training and skills development, management of hedging strategies and contracts, corporate governance, and benefits to management and the organization through effective compensation programs. A focus on training and skill development helped develop appropriate exchange rate hedging strategies and corporate governance improved compliance with laws, regulations, and policies. The benefits of effective hedging strategies include a reduction in cost and increase in profitability. The findings may help improve the soundness of professional hedging practices, which will increase the stability of the Tanzanian banking system.

A thesis submitted to the College of Dental Medicine of Nova Southeastern University of the degree of Master of Science in Dentistry. Objective: This study was conducted to determine the resistance to wear and effectiveness of Opal®Seal (Opal Orthodontics by Ultradent, South Jordan, UT, USA) against enamel demineralization in comparison to L.E.D. Pro Seal® (Reliance Orthodontic Products, Itasca, IL, USA). Background: Development of white spot lesions (WSL) is a primary concern during fixed orthodontic treatment. With poor oral hygiene during orthodontic therapy, it is almost inevitable that enamel demineralization will occur and WSLs will be seen clinically. Numerous materials have demonstrated successful prevention of WSLs, including topical varnishes and sealants, gels, pastes and bonding agents. The newly developed sealant Opal Seal is claimed by the manufacturer to prevent demineralization and subsequent WSLs from forming during orthodontic treatment. To evaluate the effectiveness of Opal Seal, we tested and compared it to Pro Seal, which has proven to be successful at WSL prevention and is, like Opal Seal, a fluoride-releasing, light-cured, low viscosity filled resin sealant. Methods: A total of 48 non-carious extracted human premolar teeth were divided into 3 groups representing one of the following topical treatments: no treatment (C), Opal Seal (OS) or L.E.D. Pro Seal (PS). Each group was subdivided into either T1 or T2 time interval groups (C1, C2, OS1, OS2, PS1 and PS2) and teeth were subjected to 10,000 or 20,000 simulated brush strokes, respectively, followed by exposure to an acidic solution for 96 hours. Teeth were examined macroscopically for product wear and assessment of WSL development and then sectioned for quantitative examination with polarized light microscopy. Results: Visual assessment revealed wear of L.E.D. Pro Seal in 62.5% of the PS2 teeth following exposure to toothbrush abrasion and acidic challenge. No L.E.D. Pro Seal or Opal Seal wear was found in any PS1 or OS teeth, respectively. WSLs involving 50-100% of the exposed enamel surface developed in all control teeth and 37.5% of PS teeth had WSLs involving less than 50% of their enamel surface. These WSLs were visible as small, white, isolated points. No visible WSLs were found in any teeth in the OS group. A Fisher's Exact test was used to evaluate any differences in demineralization within groups over time. The results indicate a significant difference in the number of lesions found at T1 compared to T2 in the PS group (p = 0.003). A non-parametric Kruskal-Wallis test using a Wilcoxon test for all multiple comparisons was conducted to evaluate any differences among the treatment groups for change in depth of demineralization (µm) at two different time points. PS and OS groups were found to have significant differences in average lesion depth compared to the control groups at T1 and T2 (pConclusions: Our results showed that both Opal Seal and L.E.D. Pro Seal reduce enamel demineralization when teeth are subjected to simulated toothbrush abrasion and an acidic environment over time. Opal Seal provided superior protection of the enamel surface and demonstrated complete wear resistance and prevention of demineralized lesion development in our experimental groups.

A thesis submitted to the College of Dental Medicine of Nova Southeastern University of the degree of Master of Science in Dentistry. Objective: The objectives of this study were 1) to evaluate the effect of enamel deproteinization on the shear bond strength(SBS) of orthodontic brackets bonded with a resin modified glass-ionomer (RMGI) adhesive and a composite resin, 2) to determine the mode of bond failure according to the adhesive remnant index (ARI) and 3) to evaluate the effect of these adhesives in the prevention of white spot lesions (WSLs). Background: WSLs are a concern for orthodontic patients. RMGI orthodontic adhesives are capable of absorbing fluoride from the oral environment and releasing it continuously over time, however, they are not frequently used as they exhibit low SBS. Techniques such as non-invasive enamel deproteinization with 5.25% sodium hypochlorite prior to acid etching rid the surface of organic components and have the potential to enhance the etching pattern. Methods: Eighty-eight extracted bovine incisors were randomly divided into two groups. 48 incisors in group (A) underwent SBS testing, through debonding of brackets with the Universal Testing Machine and subsequent measurement of the ARI. 40 incisors in group (B) underwent demineralization testing by measuring the depth of WSLs formed after exposure to an acidic challenge for 96 hours. In groups A and B, the teeth were divided to have brackets bonded with GC Fuji ORTHO™ LC adhesive or Transbond™ XT adhesive and a self-etching primer. Each adhesive group had an experimental group receiving the intervention of enamel deproteinization prior to etching and bonding and a control group. Results: The highest mean SBS was observed in the Transbond™ XT control group (12.48 ± 6.23 MPa) and the lowest mean SBS was observed in the Fuji ORTHO™ experimental group (5.49 ± 2.97 MPa). ANOVA and Post-Hoc Tukey tests revealed statistically significant differences (p<0.05) in the SBS of both Fuji ORTHO™ groups compared to the Transbond™ XT control group. A significantly greater percentage of Transbond™ XT control teeth had an ARI score of 0 and a greater percentage of Fuji ORTHO™ experimental teeth had an ARI score of 3. The Transbond™ XT experimental group had the largest average demineralization lesions (62.97 ± 10.95 micrometers). The smallest lesion depths were found in the Fuji ORTHO™ groups, with an average of 7.74 micrometers in the experimental group and 6.57 micrometers in the control group. ANOVA and Post-Hoc Tukey tests revealed significant differences (p<0.001) in the depth of white spot lesions when comparing both composite resin groups to each other, and when each glass ionomer group was compared to each composite resin group. Conclusions: Enamel deproteinization did not increase the SBS of orthodontic brackets bonded with either Fuji ORTHO™ adhesive or Transbond™ XT adhesive. However, according to the ARI, more bond failures occurred at the bracket-adhesive interface in the Fuji ORTHO™ experimental group. Also, both Fuji ORTHO™ adhesive groups showed greater protection against enamel demineralization, when compared to the Transbond™ XT adhesive groups.