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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
231

Studium degradačních procesů inkjetových inkoustů / Study of Inkjet Inks Degradative Processes

Samcová, Kateřina January 2009 (has links)
This diploma thesis follows the degradation of inkjet print by ultraviolet radiation and ozone effect for different types of papers. Colour test charts for the evaluation of accelerated ageing effect of ultraviolet light and gas fading were designed. These test charts were printed by dye-based inks on selected receiving media and exposed to ozone-enriched environment, UV radiation and their combination. The colorimetric values L* a* b* were calculated from spectral data of all patches of the test charts. The ozone effect on the prints was evaluated in the terms of total colour difference and dye concentration. The degradation of dye caused by ozone was observed also in a long-term period, after the contact of sample with ozone was terminated. Results of printed samples accelerated ageing by UV radiation and those that were influenced by the ozone effect were evaluated in the same way. It was found out that UV radiation and ozone treatment have a different effect on the degradation of dyes. The degradation rate is also strongly influenced by the receiving layer composition of papers used for inkjet printing. Also the catalytic effect of dyes was evaluated.
232

Zvýšení světlostálosti fotografií lakováním a laminováním / Enhancement of print lightfastness by varnishing and lamination

Komárková, Hana January 2013 (has links)
This diploma thesis deals with recent methods of lightfastness evaluation of both classic and digitally printed photographs. It summarizes the experimental methods used for colour change measurements. Primarily, it studies an influence of additional protection on lightfastness enhancement. Lightfastness testing of colour prints was carried out by accelerated ageing. Samples were prepared by 3 types of inkjet printers and 3 different print media. The surface of photographs was left untreated or modified by varnishing or lamination. A set of samples, thus achieved, was used to monitor a print behaviour during the light exposure. In conclusion effects of used receiving layer, ink or additional surface treatment were discussed. Colour changes were evaluated on the basis of measured reflectance spectra from which colorimetric quantities were calculated. Results were processed using VolGa application. An actual print-life was calculated from the plot of the normalized gamut volume loss and the exposure.
233

Mezní ohřev kulového kloubu při akcelerovaném testu / Ball-Joint Limited Heating during Accelerated Testing

Kříž, Ondřej January 2010 (has links)
The object of this work is design model of ball joint and define boundary conditions for real condition representation as most exact as possible. Then set parameters of test in TRW-DAS, a.s. for prevention of reacceleration with change of failure mode. Summary of ball joints, their testing and accelerated tests is in the beginning of the work. Next part describes ball joint creation in Pro/Engineer, transfer to Ansys, preparing to solution, fatigue test evaluation and comparing with create model.
234

Accelerated testing with application in finance

Oppel, Anel January 2016 (has links)
The event of a default for low-default portfolios, such as sovereign debt or banks, have received much attention as a result of the increasing instabilities in financial markets. The lack of sufficient default information on low-default portfolios complicates the protection of such portfolios. Default protections have typically, in the past, relied on extreme value theory and reporting the value at risk. The focus here, is the application of an engineering concept, accelerated test techniques, to the problem of insufficient data on low-default portfolios. In the application, high-default portfolios serve as stressed cases of low-default portfolios. Since high-default portfolios have more data available, viewing it as a stressed case of a low-default portfolio enables us to extrapolate the data to the low-default portfolio environment, and do estimation such as estimating the default probability for a low-default portfolio. The flexible framework through which the above is achieved, is provided. / Dissertation (MSc)--University of Pretoria, 2016. / Statistics / MSc / Unrestricted
235

Aplikace analytických metod pro analýzu barviv využívaných v uměleckých dílech. / Application of analytical methods for analysis of dyes employed in works of art.

Svobodová, Eva January 2011 (has links)
Natural organic dyes suffer from degradation during the time. Therefore, the works of art need to be restored and the identification of dyes by analytical methods is important here. The possibilities of using three separation (thin-layer chromatography - TLC, capillary zone electrophoresis - CZE, and micellar electrokinetic chromatography - MEKC) and two spectroscopic (infrared microspectroscopy - IR and Raman microspectroscopy) methods for the identification of red dyes (acaroid, brazil, dragon blood, kamala, logwood, cochineal, madder, lac, and sandalwood) were studied and critically discussed. In TLC, under optimised conditions (silicagel with octadecyl, 80/20 (v/v) MeOH/1% TEA in 0.1 mol·dm-3 acetate buffer, pH 5, and 80/20 (v/v) MeOH/1% TEA in 0.025 mol·dm-3 tetraborate buffer, pH 7 and 9), the stain broadening of sandalwood, logwood, acaroid, dragon blood, and brazil was observed. Carminic acid, haematein and purpurin were not detected. A comparison of CZE and MEKC showed that MEKC was superior as it permits separation of all analytes, using 0.015 mol·dm-3 sodium dodecyl sulfate in 0.01 mol·dm-3 tetraborate buffer, pH 8.5, at a voltage of 20 kV. The developed method was validated and applied to the identification of dyes in Rubia tinctorum, Rubia cordifolia, and in the mycelium of fungi...
236

Identifying at-Risk Nursing Students Using a Midcurricular Examination

Buckner, Martha M., Dietrich, Mary S., Merriman, Carolyn, Keeley, Jennifer Peterson 01 May 2013 (has links)
The purpose of this study was to investigate the usefulness of the midcurricular HESI examination in identifying at-risk students early in their nursing program. The sample included baccalaureate nursing graduates from two university programs in the southeastern United States (n = 256). A quasiexperimental design was used to determine how well the midcurricular HESI predicted outcomes on the HESI E2 and the NCLEX-RN passing status while controlling for demographic and institutional covariates. The study used logistic regression and multiple linear regression to analyze the hypotheses. The midcurricular HESI examination was found to be a statistically significant predictor of NCLEX-RN outcomeboth before (P = .044) and after (P = .041) controlling for demographic factors. The study further found a statistically significant relationship between the midcurricular HESI and the HESI E 2 examinations (P < .001). In the post hoc analyses, students from the Accelerated and Fast Track degree programs scored significantly higher than did students in the Traditional Track on themidcurricular HESI examination. There were no statistically significant differences in HESI E2 scores or NCLEX-RN outcomes among the degree tracks. As anticipated, there was a statistically significant difference in both midcurricular HESI (P < .043) and HESI E2 (P < .016) scores between students who passed and those who failed NCLEX-RN. This study indicates that the midcurricular HESI examination is very useful in predicting outcomes in baccalaureate nursing education programs.
237

Leader Developmental Readiness of Generation Y in the Training Industry

Garrigue, Marie 12 1900 (has links)
Members of Generation Y in the training and development industry will be required to assume leadership roles as Baby Boomers retire, yet little empirical research exists regarding how best to prepare them for leadership. The purpose of this study was to examine differences in leader developmental readiness between generational cohorts in the training industry, specifically Baby Boomers, Generation X, and Generation Y. Leader developmental readiness provided a definition of developmental readiness for leaders using the five constructs (learning goal orientation, developmental efficacy, self-awareness, leader complexity, and metacognitive ability). A volunteer sample was compiled from members of the ASTD National LinkedIN group (n = 636). Results were analyzed using structured means analysis with maximum likelihood (ML) estimation. Generational cohorts demonstrated differences in leader developmental readiness. Baby Boomers indicated statistically and practically higher metacognitive ability and developmental efficacy than Generation Y. Results demonstrated statistically and practically higher leader complexity in Generation Y and both Generation X and Baby Boomers. These results should inform leader development practitioners as they continue to use existing methods in preparing the different generations for leader development interventions while pointing to possible needs to increase the metacognitive ability and developmental efficacy in Generation Y and ensure accurate perception of leader complexity in those individuals. Further research would be helpful to confirm or refute findings and expand on the target population for enhanced generalizability.
238

Accelerated Carbonation Of Cement Pastes And Mortars / Accelererad karbonatisering av cementpastor och cementbruk

Hajibabaei, Pejman January 2022 (has links)
Concrete structures have the largest surface area of all human made structures. Large surface area makes concrete capable to absorb CO2 from environment during its lifetime. It is estimated that concrete during its lifetime can absorb about 15-20% of CO2 which had produced in cement production. In Sweden the CO2 uptake by concrete construction is estimated to 300 000 tons annually. This study aims to investigate the influences of fly ash and ground granulated blast furnace slag on carbonation. Accelerated carbonation with 65% relative humidity and 10% CO2 concentration was utilized to simulate the carbonation in cement pastes and cement mortars. Series of experiments have accomplished by collaborating with RISE and university of Borås. In this study cement pastes crushed into three fractions in order to evaluate the impact of particle size and influence of blended cement in CO2 uptake. Lastly, carbonation depth of mortars after 14 days accelerated carbonation were analyzed. Experimental results show that the increasing CO2 uptake induced by adding mineral admixture such fly ash in cement pastes. In this study cement paste with 30% fly ash replacement and fraction lower than 2 mm exhibit the highest CO2 uptake compared to other cement paste in this study. Moreover, carbonation depth of cement mortar was also increased three times more in mortar with 30% fly ash compared with mortar with 100% Portland cement. Therefore, incorporation of mineral admixture in cement pastes can improve the CO2 uptake and moreover, CO2 uptake can be more efficient if more surface area be involved with CO2 by crushing cement paste into lower 2 mm. / Betongkonstruktioner har den största ytan av alla människor gjorda strukturer. Stor yta gör att betong kan absorbera CO2 från luften under betongens hela livstid. Det uppskattas att betong under sin livstid kan absorbera cirka 15–20 % av CO2 som hade producerats i cementproduktionen. I Sverige uppskattas CO2-upptaget till 300 000 ton per år. Denna studie syftar till att undersöka den optimala kombinationen som kan påverka karbonatisering. Accelererad karbonatisering med 65% relativ luftfuktighet och 10% CO2-koncentration utfördes för att kunna simulera upptaget av koldioxid i cementpastor och cementbruk. En rad experiment har genomförts tillsammans med RISE och Högskolan i Borås. I denna studie krossades cementpastor i tre olika fraktioner för att utvärdera effekten av kornstorlek och påverkan av cementpastasinnehål i upptaget av CO2. Slutligen analyserades karboneringsdjupen för cementbruk efter 14 dagar accelererad karbonatisering. De experimentella resultaten från accelererad karbonatisering visar att med ökad halt av flygaska kan CO2-upptaget ökas. Cementpastan med 30 % flygaska och fraktionen lägre än två mm uppvisar det högsta CO2-upptaget jämfört med andra cementpastor med grövre fraktioner i denna studie. Dessutom ökade karbonatiseringsdjupet i cementbruk med 30% flygaska cirka tre gånger mer jämfört med cementbruk med 100% Portlandcement. Utifrån dessa resultat kan det konstateras att inblandning av tillsattmaterial i cementpasta kan förbättra CO2-upptaget och dessutom kan CO2-upptaget sker effektivare om mer kontaktytor blir involverade med CO2 genom att krossa cementpastan i fraktionen 0–2 mm.
239

FPGA-Accelerated Digital Signal Processing for UAV Traffic Control Radar

Moody, Kacen Paul 07 April 2021 (has links)
As an extension of previous work done by Luke Newmeyer in his master's thesis \cite{newmeyer2018efficient}, this report presents an improved signal processing chain for efficient, real-time processing of radar data for small-scale UAV traffic control systems. The HDL design described is for a 16-channel, 2-dimensional phased array feed processing chain and includes mean subtraction, windowing, FIR filtering, decimation, spectral estimation via FFT, cross-correlation, and averaging, as well as a significant amount of control and configuration logic. The design runs near the the max allowable memory bus frequency at 300MHz, and using AXI DMA engines can achieve throughput of 38.3 Gb/s (~0.25% below theoretical 38.4 Gb/s), transferring 2MB of correlation data in about 440us. This allows for a pulse repetition frequency of nearly 2kHz, in contrast to 454Hz from the previous design. The design targets the Avnet UltraZed-EV MPSoC board, which boots custom PetaLinux images. API code and post-processing algorithms run in this environment to interface with the FPGA control registers and further process frames of data. Primary configuration options include variable sample rate, window coefficients, FIR filter coefficients, chirp length, pulse repetition interval, decimation factor, number of averaged frames, error monitoring, three DMA sampling points, and DMA ring buffer transfers. The result is a dynamic, high-speed, small-scale design which can process 16 parallel channels of data in real time for 3-dimensional detection of local UAV traffic at a range of 1000m.
240

Thermal induced yellowing of peroxide bleached birch pulp

Nygren, Alexander January 2020 (has links)
Brightness reversion, also known as yellowing, is a well-known phenomenon which means that the brightness of paper products decreases during ageing. The name of this phenomenon is based on that paper products usually change in color towards yellow during ageing. Yellowing is considered to occur due to a mixture of chemical and physical factors, which makes it a complex problem for the pulp &amp; paper industry. The majority of the literature and research conducted with respect towards yellowing claims that light and heat is the two main factors that contributes the most to a brightness reversion, depending on the type of pulp and process that is utilized. Smurfit Kappa in Piteå is a manufacturer of the paper grade Kraftliner and has during some occasions noted unstable brightness. Based on previous work at Smurfit Kappa, it is known that the finished liners produced from bleached pulp in a completely chlorine-free process is very sensitive to heat, especially for longer periods of time during storage. It has also been documented that the storage temperature for paper products is of great importance, especially the cooling rate of the paper-rolls from production, which could take around two weeks to reach the ambient temperature. This thesis work, alongside with a literature study as a basis will examining the effect of pH towards yellowing during thermal exposure. Through a factorial experiment it was initially found that the yellowing is favored by higher temperatures in conjunction with lower pH values. In order to obtain a brightness reversion of a paper product within a reasonable timeframe an accelerated aging method was used according to the ISO standard 5630-1. Throughout this thesis is the brightness reversion expressed in the so-called b* value, which indicates the color change from blue to yellow. Further experiments, including ageing methods with moisture, also concluded that an acidic pH results in a more severe yellowing. It was also observed that the pH was decreasing during experiments of pulp storage, this most likely to the chemical phenomena known as acidic hydrolysis. The b*-value seemed to be favorable of the decreased pH, thus could the pulp be stored at pH around 8 instead of 9-10 in order to suppress potential yellowing reactions.  Furthermore, it was found that cooling of the paper resulted in a decrease of the b* value, it is however unclear what causes this phenomenon but a theory could be that chromophoric groups are being deactivated/activated due to the temperature changes and hence making the phenomena reversible. / Eftergulning är ett välkänt fenomen som innebär att ljusheten hos pappersprodukter minskar när dessa åldras. Namnet på detta fenomen grundar sig i att pappersprodukter vanligtvis skiftar i färg mot det gula hållet. Detta anses bero på en blandning av kemiska och fysikaliska faktorer, vilket därmed gör det till ett komplext problem som berör massa &amp; pappersindustrin. Majoriteten av litteraturen och den forskning som utförts inom området gällande eftergulning visar att de två faktorerna ljus och värme påverkar förändringen av ljusheten i högst omfattning, beroende på vilken typ av massa och process som pappret är producerat av. Smurfit Kappa i Piteå är en tillverkare av papperstypen Kraftliner och har under olika perioder noterat ostabila ljushetsvärden på grund av eftergulningen. Frida Sandin konstaterade genom sitt examensarbete hos Smurfit Kappa under 2008 att massan som bleks i en helt klorfri process är extra känslig mot värme, speciellt under längre tidsperioder. Sandin konstaterade även att lagringstemperaturen för pappersprodukter har stor betydelse, speciellt gällande avsvalningsförloppet i de nytillverkade pappersrullarna under papperstillverkning vilka kunde ta ungefär två veckor på sig att nå omgivningens temperatur. Detta arbete fortsätter på Sandins tidigare studier, samt med en litteraturstudie som grund, genom att undersöka pH:s påverkan på papper i samband med varierande temperaturer mer noggrant. Genom ett inledande faktorförsök konstaterades det att eftergulningen gynnas av högre temperaturer i samband med lägre pH värden. För att kunna få en eftergulning på en pappersprodukt inom en rimlig tid så användes en accelererad åldringsmetod, i detta arbete användes främst en metod med en temperatur på 105 °C enligt ISO standarden 5630–1. Eftergulningen inom detta arbete uttrycks i det så kallade b*-värdet vilket indikerar en färgskiftning mellan blått och gult. Ytterligare försök, bland annat i kombination med fukt, konstaterade vidare att ett surt pH starkt missgynnar stabiliteten på eftergulningen för pappersprodukter. Det observerades också att pH-värdet sjönk under experiment där pappersmassa lagrades, detta skedde mest troligt på grund av det kemiska fenomenet som kallas sur hydrolys. b*-värdet tycktes däremot vara gynnsamt av det sänkta pH-värdet. Förslagsvis så borde massan lagras vid pH runt 8 istället för 9–10 för att reducera potentiella eftergulnings-reaktioner. Det konstaterades också att kylning av papperet resulterar i en sänkning av b*-värdet, det är dock oklart vad som får detta att ske men en teori är att det är kromofora grupper som aktiveras/inaktiveras.

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