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Numerical Modeling and Experimental Studies on the Hydrodynamics and Heat Transfer of Silica Glass ParticlesJanuary 2020 (has links)
abstract: Granular material can be found in many industries and undergo process steps like drying, transportation, coating, chemical, and physical conversions. Understanding and optimizing such processes can save energy as well as material costs, leading to improved products. Silica beads are one such granular material encountered in many industries as a catalyst support material. The present research aims to obtain a fundamental understanding of the hydrodynamics and heat transfer mechanisms in silica beads. Studies are carried out using a hopper discharge bin and a rotary drum, which are some of the most common process equipment found in various industries. Two types of micro-glass beads with distinct size distributions are used to fill the hopper in two possible packing arrangements with varying mass ratios. For the well-mixed configuration, the fine particles clustered at the hopper bottom towards the end of the discharge. For the layered configuration, the coarse particles packed at the hopper bottom discharge first, opening a channel for the fine particles on the top. Also, parameters such as wall roughness (WR) and particle roughness (PR) are studied by etching the particles. The discharge rate is found to increase with WR, and found to be proportional to (Root mean square of PR)^(-0.58). Furthermore, the drum is used to study the conduction and convection heat transfer behavior of the particle bed with varying process conditions. A new non-invasive temperature measurement technique is developed using infrared thermography, which replaced the traditional thermocouples, to record the temperatures of the particles and the drum wall. This setup is used to understand the flow regimes of the particle bed inside the drum and the heat transfer mechanisms with varying process conditions. The conduction heat transfer rate is found to increase with decreasing particle size, decreasing fill level, and increasing rotation speed. The convection heat transfer rate increased with increasing fill level and decreasing particle size, and rotation speed had no significant effect. Due to the complexities in these systems, it is not always possible to conduct experiments, therefore, heat transfer models in Discrete Element Method codes (MFIX-DEM: open-source code, and EDEM: commercial code) are adopted, validated, and the effects of model parameters are studied using these codes. / Dissertation/Thesis / Doctoral Dissertation Chemical Engineering 2020
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In situ-IR-spektroskopische Untersuchungen zur MTS-ThermolyseHemeltjen, Steffen 13 October 2003 (has links)
In dieser Arbeit wird beschrieben, wie sich die in situ-IR-Spektroskopie zur Charakterisierung von CVD-Prozessen einsetzen läßt. Es werden Modellreaktoren vorgestellt, deren Konstruktion an die spektroskopische Verfolgung thermisch aktivierter Gasphasenreaktionen angepaßt ist. Ausgehend von Referenzmessungen, mit deren Hilfe Möglichkeiten und Grenzen der FT-IR-Spektroskopie in Bezug auf die CVD-Prozeßanalytik aufgezeigt werden, können auftretende Species im untersuchten System sicher bestimmt werden.
Im Mittelpunkt der Arbeit steht die Untersuchung der Gasphase bei der Thermolyse von Methyltrichlorsilan in Abhängigkeit von den Prozeßparametern Temperatur und Eduktgaszusammensetzung. Die gefundenen Korrelationen werden durch Thermolysen einzelner, nachgewiesener Verbindungen bestätigt. Eine weitere Absicherung der Ergebnisse erfolgt durch Isotopenmarkierung mit Deuterium. Untersuchungen zur Schichtbildung ergänzen die Gasphasenanalytik.
Auf Grundlage der nachgewiesenen stabilen und instabilen Species und deren Abhängigkeit von den Prozeßparametern wird ein Mechanismus vorgeschlagen und diskutiert, der die Thermolyse von Methyltrichlorsilan zur Abscheidung von Siliciumcarbid vollständig beschreibt.
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Normativní studie paměťového testu FCSRT-IR pro starší populaci / Normative Study Of A Memory Test "FCSRT-IR" in Older PopulationHoráková, Karolína January 2017 (has links)
The diploma thesis is focused on standardization of the neuropsychological test The Free and Cued Selective Reminding Test with Immediate Recall (FCSRT-IR), this test is a one of memory tests which contains phase with controlled learning. In the theoretical part it deals with aging and cognitive functions especially memory, further episodic memory test especially FCSRT-IR and its administration and benefits of this test against other episodic memory tests. In the practical part of this diploma thesis we report norms based on population in age 60 years and older (N= 362; range of age from 61 to 97), the norms are based on National Normative Study of Cognitive Determinants of Healthy Ageing which took place from 2012 to 2015 (IGA NT13145) and the author of this diploma thesis was a member of its team. In the second part of this thesis we deal with validation study which was conducted on population of people with dementia in Alzheimer's disease (N= 37; range of age from 61 to 88) comparing with healthy control group. In this validation study we confirmed that FCSRT-IR is a sensitive method for detection dementia in Alzheimer's disease. Keywords: Episodic memory, FCSRT-IR, controlled learning, norms, validation
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Vibrační spektroskopie farmakologicky významných molekul: Studium L-DOPA a jeho deuterovaných derivátů / Vibrational spectroscopy of pharmacologically important molecules: Study of L-DOPA and its deuterated derivativesSpasovová, Monika January 2020 (has links)
L-3,4-dihyroxyphenylalanine (L-DOPA, levodopa) is a gold standard treatment of Parkinson's disease. Lately, it has been found that some of its deuterated analogues exhibit higher potency in the treatment; thus, they could replace L-DOPA. The subject of this thesis was a study of L-DOPA and its deuterated derivatives by the means of vibrational spectroscopy (Raman, ROA, IR, and VCD) and a comparison of the experimental results to a quantum mechanical simulations of the spectra. ROA and VCD are chiroptical methods, thus they are suitable for measurement of chiral molecules amongst which L-DOPA indeed belongs. Thanks to the quantum chemistry calculations, which yielded spectra with a very good agreement with the experiment, we were able to assign experimental spectral features to individual vibrational modes of the L-DOPA. The use of chiroptical techniques (mainly ROA) enabled an assignment of an absolute configuration of double deuterated derivative of L-DOPA, α,β-D2-L-DOPA. It reviled that it occurs in a (S-α,S-β)-enantiomeric form.
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Grundskollärares tankar om undervisning i problemlösning med avseende på kreativa och imitativa resonemang : Problemlösning ur ett lärarperspektiv för elever i årskurs 1–3Tärndal, Julia January 2020 (has links)
I denna studie har grundskollärares, i årskurs 1–3, tankar om sin undervisning i problemlösning i ämnet matematik, med avseende på kreativa och imitativa resonemang undersökts. Fem kvalitativa intervjuer med grundskollärare från olika skolor utfördes och analyserades därefter med stöd från Lithners (2008) teori om kvalitativa och imitativa resonemang. Studien visar på att grundskollärarna har svårt att undervisa problemlösning utifrån de kriterier Lithner (2008) anser vara matematiska kreativa resonemang (problemlösning) på ett sätt som uppmuntrar och möjliggör för eleverna att resonera kreativt. Empirin visar att lärare i högre utsträckning möjliggör imitativa resonemang då de anser att elevernas kunskapsnivå är för låg och att de är måna om att eleverna ska få lyckas. / <p>Matematik</p>
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"Blinded by the Lines: Mid-IR Spectra of Mira Variables Taken with Spitzer"Baylis-Aguirre, Dana, Creech-Eakman, Michelle J., Luttermoser, Donald G., Gueth, Tina 28 September 2016 (has links)
We present preliminary analysis of mid-infrared spectra of M-type and C-type Mira variables. Due to the brightness of this sample, it is straightforward to monitor changes with phase in the infrared spectral features of these regular pulsators. We have spectra of 25 Mira variables, taken with phase, using the Spitzer Infrared Spectrograph (IRS) high-resolution module. Each star has multiple spectra obtained over a one-year period from 2008-09. This is a rich, unique data set due to multiple observations of each star and the high signal-to-noise ratio from quick exposure times to prevent saturation of the IRS instrument. This paper focuses on the 17.6 and 33.2 micron lines shared by M-types and C-types. These are mostly emission lines that change with phase. We discuss preliminary physical diagnostics for the atmospheres based on the lines, as well as possible line identifcations such as fuorescence of metal species.
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The Women, Peace, and Security (WPS) Agenda: A Normative Investigation of the Agenda in Southeast Asian CountriesBrink, Sandra January 2022 (has links)
This research engages with debates about globalizing IR and studies of the Women, Peace, and Security (WPS) Agenda established by the UN in the year of 2000. There have for many years been a lot of literature that is focused on the Agenda in the West using theories which are also established in the same region. This thesis therefore wants to contribute by looking at the WPS Agenda outside the West. This study does so by looking at the Southeast Asian countries of Timor Leste, Indonesia, and the Philippines with a normative investigation. This study adopts questions of how the Southeast Asian region has accepted norms and ideas from the resolution into their own National Action Plans (NAPs) and wants to investigate how these plans conform and differ from the original WPS Agenda. What this thesis finds are a lacking adoption and acceptance of norms in the Philippine, Indonesia, and Timor Leste National Action Plan (NAP). By conducting a conventional content analysis and using the norm-life cycle as a theoretical model this thesis concludes that there are some varying levels of norm acceptance and that the three countries are yet to fully implement the Women, Peace, and Security Agenda (WPS). What the findings also presents is that the local context and culture of a particular country is very important in determining the extent of adoption to international norms and concepts such as those proposed in the WPS Agenda. This means that we need to globalize the study of norms within IR, and we cannot assume that all countries will adopt norms in the same way, or in the same way as the Western states. Based on these findings the research has a small contribution to the larger globalization of IR, Global Political Economy, and studies of the WPS Agenda in the Southeast Asian countries. This thesis recommends future research of other agendas and for additional regions to enhance further knowledge within the normative field of research.
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Novel materials for Yb and Er-Yb doped microchip lasersHellström, Jonas January 2006 (has links)
The objective of this thesis has been to investigate novel host material configurations for high-power end-pumped Er-Yb co-doped, or Yb doped microchip lasers and try to increase their performance. In Er-Yb co-doped systems, the main limitation is the thermal shortcomings of the phosphate glass host material. The thesis presents some novel results that contribute to the search for a crystalline replacement. In Yb doped systems, most end-pumped schemes reported have been using relatively low-power single-emitter diodes. The thesis presents experiments with Yb:KGW microchips end-pumped by high-power diode bars. Another common limitation of end-pumped Yb microchip lasers is the thermal lens that destabilizes the cavity and decreases the beam quality. The approach to reduce the thermal lens by using an athermal propagation direction has been evaluated and the results are presented in the thesis. In the search for a crystalline host material for Er-Yb systems, borates have been found increasingly interesting. Consequently, we started out by investigating Gadolinium-calcium-oxoborate, GdCOB, which could be grown in platinum crucibles. It was found that the cw performance of such monolithic microchips is quite comparable to glass hosts in terms of slope efficiency, but the threshold is significantly larger. As for Q-switched performance, which is essential to most Er-Yb applications, the first efficient Q-switched results with a crystalline host is presented in the thesis. Similar to the cw regime, the slope efficiencies are comparable to glass, while the threshold is quite high. However, the perhaps most important parameter, maximum output power before thermal fracture, is neither significantly improved nor worsened compared with phosphate glass. This is believed to be due to higher threshold and a stronger thermal expansion that negates the benefit of a thermal conductivity that is only 2-3 times higher. To find a host material that could withstand higher pump powers, we turned our attention to the double-tungstates KGW and KYW, which have higher thermal conductivity and higher cross-sections. They have, however, energy level lifetimes which differ significantly from glass or borates and as a consequence, a thorough spectroscopic investigation has been undertaken to optimize dopant concentrations. Laser experiments on crystals with dopant concentrations based on this investigation are expected in the near future. When pumping Yb:KGW with a high-power diode bar, we achieved output powers of 9 – 12.4 W under different experimental conditions with incident powers of 18.3 – 26 W. The incident power of 26 W in one design was enough to fracture the crystal. Using a crystal cut for propagation along an athermal direction and comparing it with an identical b-cut crystal, we found that the thermal lens in the athermally oriented crystal was about a factor two weaker at the same absorbed power. / QC 20101116
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Strength Training and Insulin Resistance: The Mediating Role of Body CompositionNiemann, McKayla Jean 19 March 2020 (has links)
OBJECTIVE: The main objective of the present study was to assess the association between varying amounts of strength training and insulin resistance. Another goal was to assess the influence of several potential confounding variables on the strength training and insulin resistance relationship. Lastly, the role of waist circumference, fat free mass, and body fat percentage on the association between strength training and insulin resistance was assessed. METHODS: This cross-sectional study included 6561 randomly selected men and women in the US. Data were collected using the precise protocol established by NHANES. HOMA-IR was used as the outcome variable. Both time spent strength training and frequency of strength training bouts were used as exposure variables. RESULTS: There was not a statistically significant relationship between strength training and insulin resistance in women. However, after controlling for 10 potential confounding variables, men who reported no strength training had significantly higher levels of HOMA-IR compared to men who reported moderate or high levels of strength training (F = 9.87, P < 0.0001). Odds ratios were also assessed, and 10 potential confounding variables were controlled. Men reporting no strength training had 2.42 times the odds of having insulin resistance compared to men reporting moderate levels of strength training (95% CI: 1.19 to 4.93). Similarly, men reporting no strength training had 2.50 times the odds of having insulin resistance compared to men reporting high levels of strength training (95% CI: 1.25 to 5.00). CONCLUSION: There was a strong relationship between strength training and insulin resistance in US men, but not in US women. Differences in waist circumference, fat free mass, and body fat percentage, as well as demographic and lifestyle measures, do not appear to mediate the relationship.
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Impact of non-idealities and integrator leakage on the performance of IR-UWB receiver front endNavineni, Tharakaramu January 2012 (has links)
UWB has the huge potential to impact the present communication systems due to its enormous available bandwidth, range/data rate trade-off, and potential for very low cost operation. According to FCC, Ultra Wideband (UWB) radio signal defined as a signal that occupies a bandwidth of 500 MHz or fractional bandwidth larger than 20% with strict limits on its power spectral density to -41.3dBm/MHz in the range 3.1GHz to 10.6GHz. Decades of research in the area of wide-band systems have lead us to new possibilities in the design of low power, low complexity radios, comparing with existing narrowband radio systems. In particular, impulse radio based ultra wideband (IR-UWB) is a promising solution for short-range radio communications such as low power radio-frequency identification (RFID), wireless sensor network's and wireless personal area network (WPAN) etc. Since a simple circuit, architecture adopted in the IR-UWB system, the non-idealities of receiver front end may lead to degrade the overall performance. Therefore, it is important to study these effects in order to create robust and efficient UWB system. However, majorities of recent studies are formed on the channel analysis, rather than the receiver system. The main objectives of this thesis work are, (a) System level modeling of non-coherent IR-UWB receiver, (b) Performance analysis of IR-UWB receiver with the help of bit error rate (BER) estimation, (c) A study on the impact of receiver front end non-idealities over BER, (d) Analysis of charge leakage in integrator and its effect on overall performance of UWB receiver. In this work, IR-UWB non-coherent energy detector receiver operating in the frequency band of 3GHz-5GHz based on the on-off keying (OOK) modulation was simulated in Matlab/Simulink. The effect of receiver front end non idealities and integrator charge leakages were discussed in detail with respect to overall performance of the receiver. The results show that non idealities and leakage degrade the performance as expected. In order to achieve a specific BER of 10-2 with the integrator leakage of 25%, the SNR should be increased by 2.1 dB compared to the SNR with no leakage at a data rate of 200Mbps. Finally, integrator design and its specifications were discussed.
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