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101	IMPACT BEHAVIOR OF AMMONIUM PERCHLORATE (AP) - HYDROXYL-TERMINATED POLYBUTADIENE (HTPB) COMPOSITE MATERIAL Saranya Ravva (15353902) 25 April 2023 (has links) <p>This work investigated the effects of varying the crystal sizes of ammonium perchlorate (AP) when embedded with a polymeric binder, hydroxyl-terminated polybutadiene (HTPB) on impact-induced temperature behavior. AP and HTPB are the most used oxidizers and fuel binders in the aerospace solid rocket design industry. In this study, samples of 200 µm and 400µm coarse AP crystals in HTPB were constructed using a conventional hand-mixing method. Using a parametric optimization technique such as the Taguchi method, direct-ink-writing as the additive manufacturing process was used for achieving the required shape fidelity in printing HTPB and by introducing ultraviolet polymers to decrease the curing time.</p> <p>A drop hammer experiment in conjunction with an infrared camera was used to study the impact-induced behavior in the conventionally made AP-HTPB samples. The thermal images obtained from the camera at millisecond resolution are invaluable and provide information about distribution across the sample surface, and the evolution of temperature rise observed in the samples which are complex and not easily understood otherwise and therefore help in improving and attaining desired propellant performance. A two-sample t-Test has been utilized to infer the results and statistical nonsignificance has been observed in the highest temperature rises among 200 µm and 400 µm AP-HTPB sample conditions but a difference in temperature distribution has been observed. A much uniform distribution of temperature over the sample surface on impact is observed in thermal images of 200 µm AP-HTPB sample condition compared to 400 µm AP-HTPB sample condition.</p> Aerospace materials Aerospace structures Additive manufacturing Composite and hybrid materials Ammonium Perchlorate (AP) Hydroxyl-Terminated Polybutadiene (HTPB) Impact Testing Aerospace Engineering Additive Manufacturing Direct Ink Writing Parametric Optimization Taguchi Method Drop Hammer Impact IR camera Solid Rocket Propellant APCP T-test p-value Aerospace Materials
102	Active versus passive portfolio management : A study of risk-adjusted return and market fluctuations on short term and long term Duveskog, Ida, Halldén, Jesper January 2024 (has links) Today fund matching is a natural part of Swedes finance and is a popular form of savings that includes a large number of investors in the Swedish fund market. This in turn generates an increased interest in how portfolio managers should locate and acquire knowledge in portfolio selection. This gives a greater interest in how different investment strategies can be affected and generate an investors wealth to an increased level within the stock market, which gives an increased focus to be able to generate as high risk-adjusted return as possible. The study partly presents traditional theory and background on modern portfolio theory and the efficient market hypothesis. Empirical studies also present within the financial market that demonstrate the differences of opinion between how actively versus passively managed funds have performed and which investment strategy is most beneficial for investment. The purpose of the study is to compare realized return on active versus passive funds during long term, short term and specific time periods that had a lot of economic fluctuations, like bear markets. Within the study 10 actively managed funds and two index measures are selected to be studied and compared based on their respective performance, both within its rise and fall in the Swedish fund market. The performance measures will then be applied to be able to produce the results of the study and to be able to answer whether the active fund’s have any statistically significant over- and underperformance. After conducting single index models and t-test on the 10 active funds, the result of the study shows that despite using two benchmarks index, ten different active funds, long time period, short time period or specific time periods defined by market imbalance , we still resulted in many P-values that was not statistically significant. Active funds failed to overperform against passive funds, but passive funds also failed to outperform our selection of active funds. Active funds Passive funds Fund managers Risk-adjusted return Swedish Fund Market Index Benchmark OMXSGI OMXS30GI investment strategies Portfolio allocation diversification volatility NAV-course Bull and Bear market Beta systematic and unsystematic risk Small- and medium sized companies Large companies Market fluctuations Single index model linear regression T-test standard deviation risk level portfolio selection Alpha R-adjusted P-values. Business Administration Företagsekonomi
103	Tidal sedimentology and geomorphology in the central Salish Sea straits, British Columbia and Washington State Mullan, Sean 03 January 2018 (has links) Intra-archipelago waterways, including tidal strait networks, present a complex set of barriers to, and conduits for sediment transport between marine basins. Tidal straits may also be the least well understood tide-dominated sedimentary environment. To address these issues, currents, sediment transport pathways, and seabed sedimentology & geomorphology were studied in the central Salish Sea (Gulf and San Juan Islands region) of British Columbia, Canada and Washington State, USA. A variety of data types were integrated: 3D & 2D tidal models, multibeam bathymetry & backscatter, seabed video, grab samples, cores and seismic reflection. This dissertation included the first regional sediment transport modelling study of the central Salish Sea. Lagrangian particle dispersal simulations were driven by 2D tidal hydrodynamics (~59-days). It was found that flood-tide dominance through narrow intra-archipelago connecting straits resulted in the transfer of sediment into the inland Strait of Georgia, an apparent sediment sink. The formative/maintenance processes at a variety of seabed landforms, including a banner bank with giant dunes, were explained with modelled tides and sediment transport. Deglacial history and modern lateral sedimentological and morphological transitions were also considered. Based on this modern environment, adjustments to the tidal strait facies model were identified. In addition, erosion and deposition patterns across the banner bank (dune complex) were monitored with 8-repeat multibeam sonar surveys (~10 years). With these data, spatially variable bathymetric change detection techniques were explored: A) a cell-by-cell probabilistic depth uncertainty-based threshold (t-test); and B) coherent clusters of change pixels identified with the local Moran's Ii spatial autocorrelation statistic. Uncertainty about volumetric change is a considerable challenge in seabed change research, compared to terrestrial studies. Consideration of volumetric change confidence intervals tempers interpretations and communicates metadata. Techniques A & B may both be used to restrict volumetric change calculations in area, to exclude low relative bathymetric change signal areas. / Graduate / 2018-12-07 tidal strait networks sediment transport pathways seabed sedimentology marine geomorphology Salish Sea Gulf Islands San Juan Islands multibeam bathymetry Lagrangian particle dispersal tidal hydrodynamics Strait of Georgia Strait of Juan de Fuca banner bank giant dunes tidal strait facies model bathymetric change detection t-test local Moran's Ii depth uncertainty volumetric change confidence intervals deglacial history repeat surveys sand dynamics tides sonar marine renewable energy offshore pipelines and cables benthic habitat spatial autocorrelation spatial analysis and statistics geographic information system (GIS) finite element method (FEM)
104	An exploration of reflective writing and self-assessments to explain professionalism lapses among medical students Hoffman, Leslie Ann January 2014 (has links) Indiana University-Purdue University Indianapolis (IUPUI) / Background: Recent literature on medical professionalism claims that self-awareness and the ability to reflect upon one’s experiences is a critical component of professionalism; however there is a paucity of empirical evidence to support this claim. This study employed a mixed methods approach to explore the utility of reflective writing and self- and peer assessments in explaining professionalism lapses among medical students. Methods: A retrospective case-control study was conducted using students from Indiana University School of Medicine (IUSM) who had been disciplined for unprofessional behavior between 2006-2013 (case group; n=70). A randomly selected control group (n=230) was used for comparison. Reflective ability was assessed using a validated rubric to score students’ professionalism journals. Mean reflection scores and assessment scores were compared using t-tests. Logistic regression analysis was used to determine the impact of reflection scores and self- and peer assessment scores on the likelihood of having been disciplined for unprofessional behavior. Subsequent qualitative analysis further explored when and how students learned professionalism during their clinical experiences. Results: The study found that students in the case group exhibited lower reflective ability than control students. Furthermore, reflective ability was a significant factor in explaining the odds that a student had been cited for professionalism lapses. There were no differences in self-assessment scores between the two groups, but students in the case group had significantly lower peer assessment scores than control students. Peer assessment scores also had the greatest influence on the odds that a student had been cited for professionalism deficiencies during medical school. Qualitative analysis revealed that students learn professionalism from role models who demonstrated altruism and respect (or lack thereof). Conclusions: These findings suggest that students should be provided with guidance and feedback on their reflective writing to promote higher levels of reflection, which may reduce the number of students who are cited for professionalism lapses. These findings also indicate that peer assessments can be used to provide students with insightful feedback regarding their professional development. Finally, role models have a strong influence on students’ professional development, and therefore must be cognizant of the implicit messages their behaviors convey. professionalism reflection peer assessment medical students Medical students -- Attitudes Medical ethics -- Study and teaching Peer review Discourse analysis, Narrative Communication in medicine Feedback (Psychology) -- Research Qualitative research Role models -- Research Reflection (Philosophy) Students -- Self-rating of Professional ethics
105	GRAVIDA KVINNORS INTAG AV KOSTTILLSKOTT : En kvantitativ studie med fokus på järn och probiotika / PREGNANT WOMEN´S INTAKE OF DIETARY SUPPLEMENT : A quantitative study focusing on iron and probiotics Lange Bålman, Miriam January 2019 (has links) Sammanfattning Bakgrund Vitamin- och mineralbrister hos gravida kvinnor kan leda till missfall och allvarliga störningar i barnets utveckling. Moderns tarmflora överförs med stor sannolikhet till barnet under förlossningen och kan därför innebära ett viktigt steg i utvecklingen av barnets tarmflora. En tänkbar lösning för att säkra ett adekvat intag kan vara konsumtion av kosttillskott och probiotika. I dagsläget finns osäkra uppgifter om hur många gravida kvinnor som intar tillskott. Syfte Att undersöka hur många gravida kvinnor i Västerbottens län som valde att inta kosttillskott, främst järn och probiotika, samt om det fanns en skillnad mellan olika faktorer och intag. Metod En kvantitativ tvärsnittsstudie där gravida kvinnor (n=1473) från Northpop-studien i Västerbottens län svarade på ett frågeformulär gällande intag av kosttillskott och faktorer som ålder, utbildning, kostregim etc. De statistiska tester som användes var Chi-2-test, oberoende t-test och Mann Whitney U-test. Materialet analyserades i SPSS. Signifikansnivån sattes till p<0,05. Resultat Majoriteten av deltagarna svarade att de intog kosttillskott. Faktorer som ökade intaget av kosttillskott hos gravida kvinnor var högre ålder (p=0,030) jämfört med lägre ålder, högre utbildningsnivå (p=0,006) jämfört med lägre utbildningsnivå och vegetarisk/vegansk kost (p=0,021) jämfört med blandkost. Femtiofem procent uppgav att de intog järntillskott. De faktorer som ökade intaget av järntillskott hos gravida kvinnor var vegetarisk/vegansk kost (p=0,001) jämfört med blandkost. Probiotika intogs av 2 procent. Ett högre intag av probiotika sågs hos personer boende i stadsområde (p=0,024) jämfört med övriga boenderegioner samt de som åt vegetarisk/vegansk kost (p=0,001) jämfört med blandkost. Slutsats Majoriteten av deltagarna intog någon typ av kosttillskott, hälften intog järntillskott och en liten andel intog probiotika. Lågutbildade, yngre, de som äter blandkost och bor utanför stadsområde verkar vara i riskgruppen för att inte inta kosttillskott. / Abstract Background Vitamin and mineral deficiencies in pregnant women can lead to miscarriage and serious disturbances in children’s development. The intestinal flora of the mother is most likely transmitted to the child during childbirth and may lay the foundation for the child's health. One possible solution to ensure an adequate intake may be the consumption of dietary supplements and probiotics. At present, there is insufficient data on supplement consumption among pregnant women. Objective The purpose of the study was to examine how many pregnant women in Västerbotten County chose to consume dietary supplements, mainly iron and probiotics, and whether there was a difference between different factors and intake. Method A quantitative cross-sectional study where pregnant women (n=1473) from the Northpop-study in Västerbotten County responded to a questionnaire regarding consumption of dietary supplements and factors such as age, education, diet etc. The material was analyzed in SPSS with Chi-2-test, independent T-Test and Mann-Whitney U-Test. Using significance level <0.05. Results The majority of participants, 90 percent, responded that they consumed dietary supplements. The factors that increased the intake of dietary supplements in pregnant women were higher age (p=0.030), higher education (p=0.006) and vegetarian/vegan diet (p=0.021). Iron was reported to be consumed by 804 people, 55 percent. The factors that increased the intake of iron supplement in pregnant women were vegetarian/vegan diet (p=0.001). Probiotics were consumed by 25 people, 2 percent. Living in urban areas (p=0.024) and eating vegetarian/vegan diet (p=0.002) increased consumption of probiotics. Conclusion The majority of participants chose to consume some type of dietary supplement, half of the participants consumed iron supplements and a small part consumed probiotics. It appears that pregnant women who are low educated, younger, eating an omnivorous diet and living outside urban areas are in the risk zone for not consuming dietary supplements. / Northpop Pregnant pregnant women woman pregnancy children fetus dietary supplements supplements iron iron supplements probiotics probiotic supplements intestinal flora bacteria gut vitamin vitamins minerals minerals B12 folate diet education low educated highly educated region age intake diet regime northpop Västerbotten Västerbotten County Council Umeå University Umeå Sweden Miriam Lange Bålman Miriam Lange Balman science economist vegetarian vegan mixed diet omnivore urban area country side quantitative nutrition diet dietician dietetics quantitative nutrition diet Chi-2 test independent t-test Mann Whitney U-test Multivitamins (mixture of vitamins) Multi-minerals (blend of minerals) Probiotics Omega-3 fish oil Blutsaft A- vitamin B vitamin vitamin C vitamin D vitamin E folic acid iron calcium beta-carotene vitamin B complex selenium antioxidants zinc magnesium q10 exercise physical activity lifestyle bachelor essay Gravid gravida kvinnor kvinna graviditet foster barn kosttillskott tillskott järn järntillskott probiotika probiotikatillskott tarmflora bakterier tarm vitamin vitaminer mineral mineraler B12 folat kost utbildning lågutbildad högutbildad boenderegion stad landsbygd ålder intag kostregim northpop Västerbotten Västerbottens läns landsting Umeå universitet Umeå Sverige Miriam Lange Bålman Miriam Lange Bålman kostvetenskap kostekonom vegetarisk vegetariskt vegan veganskt blandkost stadsområde kvantitativ näring samhällsrelevans dietist dietetik Chi-2-test oberoende t-test Mann Whitney U-test Multivitaminer (blandning av vitaminer) Multimineraler (blandning av mineraler) Probiotika Omega-3 fiskolja Blutsaft A-vitamin B-vitamin C-vitamin D-vitamin E-vitamin Folsyra Järn Kalcium Betakaroten Vitamin B-komplex Selen Antioxidanter Zink Magnesium Q10 träning fysisk aktivitet livsstil uppsats kandidatexamen Nutrition and Dietetics Näringslära
106	Railway curve squeal: Statistical analysis of train speed impact on squeal noise Asplund, Ruben January 2024 (has links) No description available. ml operation maintenance railway maintenance railway curve machine learning statistics railway train passenger train x60 squeal noise curve squeal squealing noise squeal wheel squeal squealing programming system development computer engineering data visualization data preprocessing industrial computer systems matlab python vibration vibrations vibration signals signals and systems filtering signal processing computer systems communication system infrastructure technology infrastructure track t-test z-test random forest xgboost feature importance speed detection band-pass filter script yaw angle angle of attack decision tree gbdt filter temperature humidity dew point curve radius cloud accelerometers sensors track rail statistical analysis acoustics sound ai artificial intelligence gradient boosting decision trees curve software development drift underhåll järnvägsunderhåll järnvägskurva maskininlärning statistik järnväg tåg x60 skrikljud snäva kurvor kurvradie kurvskrik hjulskrik programmering systemutveckling datateknik data industriella datorsystem matlab python vibration signaler vibrations signaler signaler och system filtrering signalbehandling datorsystem kommunikationssystem infrastrukturteknik infrastruktur spår t-test z-test random forest Södertälje band-pass filter hastighets detektion attackvinkeln anfallsvinkel IMx SKF temperatur fuktighet daggpunkt accelerometer järnvägskurvskrik tåg hastighetens statistisk analys akustik ljud ai kurva kurvor mjukvaruutveckling artificiell intelligens Infrastructure Engineering Infrastrukturteknik Signal Processing Signalbehandling Communication Systems Kommunikationssystem Computer Systems Datorsystem

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