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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.
31

NUMERICAL INVESTIGATION OF AIR-MIST SPRAY COOLING AND SOLIDIFICATION IN SECONDARY ZONE DURING CONTINUOUS CASTING

Vitalis Ebuka Anisiuba (11828069) 20 December 2021 (has links)
As a result of the intense air-water interaction in the spray nozzle, air-mist spray is one of the most promising technologies for attaining high heat transfer. CFD simulations and multivariable linear regression were used in the first part of this study to analyze the air-mist spray produced by a flat-fan atomizer and to predict the heat transfer coefficient using the casting operating conditions such as air pressure, water flow rate, cast speed and standoff distance. For the air-mist spray cooling simulation, a four-step simulation method was utilized to capture the turbulent flow and mixing of the two fluids in the nozzle, as well as the generation, transport, and heat transfer of droplets. Analysis of the casting parameters showed that an increase in air pressure results in efficient atomization, increases the kinetic energy of the droplets and produces smaller droplet size thus, the cooling of the slab increases significantly. Also, a decrease in water flow rate, standoff distance and casting speed would result in more efficient cooling of the steel slab. The second part of the study investigated the solidification of steel in the secondary cooling region. Caster geometry and casting parameters were studied to evaluate their impact on the solidification of steel. The parameters studied include roll gap, roll diameter, casting speed and superheat. It was found that a smaller ratio of roll gap to roll diameter is more efficient for adequate solidification of steel without any defect. Casting speed was found to have a significant effect on the solidification of steel while superheat was found to be insignificant in the secondary zone solidification. The result from the air-mist spray cooling was integrated into the solidification model to investigate the solidification of steel in the entire caster and predict the surface temperature, shell growth and metallurgical length. To replicate real casting process, temperature dependent material properties of the steel were evaluated using a thermodynamic software, JMatPro. The air-mist spray model was majorly investigated using ANSYS Fluent 2020R1 CFD tool while the solidification of steel was studied using STARCCM+ CFD software. Using the findings from this study, continuous casting processes and optimization can be improved.
32

Hevlín – sídlo v krajině / Hevlín – place in the landscape

Moutelíková, Veronika January 2020 (has links)
Railway. A line of houses hidden in the fog. A majestic steam powered locomotive. Although the great era of steam engines is long over and the built railway network is unfortunately gradually losing its significance, this part of history forms an important part of technical evolution and its significance for the transformation of human society. The surroundings of the station buildings are now quiet places, through which people only passes towards their final destination. Hrušovany nad Jevišovkou-Šanov railway station is also dealing with this problem. The diploma thesis focuses on the project of tourist attractive objects for the revitalization of the location of Hrušovany railway station near the Czech-Austrian border. New buildings inspired by steam, as an element of strength and movement, complement the development of the railway station and apartment building. Together they complete another line in the layout of the station with the track.
33

Software Development and Qualification Testing of a CubeSat X-ray Monitor

Persson, Marcus January 2019 (has links)
The CUBES (CUbesat x-ray Background Explorer using Scintillators) is a payload on the KTH student satellite MIST (MIniature STudent satellite) to evaluate Silicon Photo-multiplier technology and new scintillators such as GAGG (Gadolinium Aluminium Gallium Garnet, Gd3Al2Ga3O12) for future use in hard X-ray polarisation studies of Gamma-Ray Bursts. CUBES itself is designed to study the MIST in-orbit radiation environment by using a detector which is comprised of a silicon photomultiplier coupled to different scintillator materials. Three of these detectors will be mounted on the payload platform and then coupled to inputs of an Application Specific Integrated Circuit (ASIC) and connected to a Field-programmable Gate Array (FPGA) which will store and send data through the downlink on the MIST satellite to ground. This thesis covers the software development for the FPGA, together with two radiation tests of components and the preparation of these. / CUBES / MIST
34

A Proposal and Implementation of a Novel Architecture Model for Future IoT Applications : With focus on fog computing

Andersson, Viktor January 2022 (has links)
The number of IoT devices and their respective data is increasing for each day impacting the traditional architecture model of solely using the cloud for processing and storage in a negative way. This model may therefore need a supporting model to alleviate the different challenges for future IoT applications. Several researchers have described and presented algorithms and models with focus on distributed architecture models. The main issues with these however is that they fall short when it comes to the implementation and distribution of tasks. The former issue is that they are not implemented on actual hardware but simulated in a constrained environment. The latter issue is that they are not considering sharing a single task but to distribute a whole task. The objective of this thesis is therefore to present the different challenges regarding the traditional architecture model, investigate the research gap for the IoT and the different computing paradigms. Together with this implementing and evaluating a future architecture model capable of collaboration for the completion of a generated task on multiple off-the-shelf hardware. This model is evaluated based on task completion time, data size, and scalability. The results show that the different testbeds are capable communicating and splitting a single task to be completed on multiple devices. They further show that the testbeds containing multiple devices are performing better regarding completion time and do not suffer from noticeable scalability issues. Lastly, they show that the completion time drops remarkably for tasks that are split and distributed.
35

Preparation and Magneto-optical Effect of Ferrite-based Composites and Thin Films / フェライト系複合材料および薄膜の作製と磁気光学効果

Yao, Situ 23 March 2016 (has links)
京都大学 / 0048 / 新制・課程博士 / 博士(工学) / 甲第19728号 / 工博第4183号 / 新制||工||1645(附属図書館) / 32764 / 京都大学大学院工学研究科材料化学専攻 / (主査)教授 田中 勝久, 教授 平尾 一之, 教授 三浦 清貴 / 学位規則第4条第1項該当 / Doctor of Philosophy (Engineering) / Kyoto University / DGAM
36

View, Bedrock, Forest, Forest Edge : A Recreational Facility at Avholmsberget

Andersson, Klara January 2018 (has links)
The program of the proposal is a small recreational facility with a restaurant,conference facilities, a reception, hotel rooms and a bath.The size of the program is approximately 1200 m2.Rough approximation:- Staff and information building: 200 m2- Hotel rooms (10 á 25 m2): 250 m2- Bath building: 210 m2- Conference building: 300 m2
37

Fabrication of MoO₂ and VO₂ Thin Films Using Mist Chemical Vapor Deposition / MoO₂およびVO₂薄膜のミスト化学気相成長法による作製

Matamura, Yuya 23 March 2022 (has links)
京都大学 / 新制・課程博士 / 博士(エネルギー科学) / 甲第24011号 / エネ博第447号 / 新制||エネ||84(附属図書館) / 京都大学大学院エネルギー科学研究科エネルギー応用科学専攻 / (主査)教授 平藤 哲司, 教授 土井 俊哉, 教授 藤本 仁 / 学位規則第4条第1項該当 / Doctor of Energy Science / Kyoto University / DFAM
38

Methods for Estimating the Magnetic Dipole Moment of Small Objects

Arvidsson, Elina, Brunskog, Rickard January 2020 (has links)
A small satellite can be adversely affected by Earth’s magnetic field due to the resulting torque the magnetic field exerts on the satellites magnetic dipole moment. Therefore, this dipole moment needs to be estimated during the development of the satellite to make sure that the torque does not become a problem once the satellite is in orbit. This needs to be done for the MIniture STudent satellite (MIST), built at KTH Royal Institute of Technology. Two methods that make use of different techniques to measure the magnetic dipole moment of objects are evaluated through simulations. The first method holds the promise of being able to accurately estimate the dipole moment on components and the whole satellite alike, but has the downside of having a more complex setup. The second method can be set up easily, and can quickly produce an estimate of the dipole moment of one single object. However, the method is more susceptible to external disturbances in the magnetic field, and placement of the object. Due to time constraints, only the second method is evaluated experimentally. To understand how the second method performs, reference measurements are made on a coil with a known dipole moment. The results from the reference measurements show that the second method works well enough to produce values accurate enough for this project. Measurements are thereafter made on components similar to the flight hardware which are put through a set of tests to see how easily magnetised they are. The resulting values show that the magnetic field from magnetic tools can magnetise the components to the extent of becoming a problem, making the satellite’s dipole moment exceed the set limit. A more thorough investigation of MIST’s magnetic dipole moment should be conducted to determine if the satellites total magnetic dipole moment runs the risk of exceeding the set limit. / Små satelliter kan påverkas negativt av jordens magnetfält då det i samband med satellitens magnetiska dipolmoment kan resultera i ett moment som verkar på satelliten. Därför behöver det magnetiska dipolmomentet uppskattas under utvecklingen av satelliten för att fastställa att problem inte uppstår när satelliten är i omloppsbana runt jorden. Denna uppskattning måste göras på MIniture STudent satelliten MIST, som byggs på Kungliga Tekniska Högskolan i Stockholm. Två metoder som använder sig av olika tekniker för att mäta det magnetiska dipolmomentet på komponenter undersöks genom simuleringar. Första metoden verkar från simuleringarna kunna göra en mätning av det magnetiska dipolmomentet med hög precision på enskilda komponenter och hela satelliten. Metoden har dock en komplex mätuppställning. Andra metoden kan snabbt ställas upp och en uppskattning av en komponent kan fås. Nackdelen med metoden är dess känslighet mot störningar i magnetfältet samt felplacering av dipolen. På grund av projektets tidsram väljs den andra metoden för att göra experimentella mätningar. För att förstå hur den andra metoden presterar görs mätningar på en spole med ett känt magnetiskt dipolmoment. Resultaten från mätningarna på spolen visar att metoden fungerar bra nog för att ge tillräckligt noggranna värden för projektet. Mätningar görs därefter på komponenter som liknar MISTs hårdvara för att undersöka hur lätta de är att magnetisera. Resultaten visar att magnetiska fält från verktyg kan magnetisera komponenterna så pass mycket att den satta gränsen för satellitens magnetiska dipolmomentet överskrids. En mer grundlig utredning av MISTs magnetiska dipolmoment bör göras för att fastställa om dipolmomentet riskerar att överskrida gränsen. / Kandidatexjobb i elektroteknik 2020, KTH, Stockholm
39

PHARMACOKINETICS OF RESVERATROL, ITS MONOCONJUGATES AND ITS TRIMETHOXY ANALOG TMS

Sharan, Satish January 2013 (has links)
Resveratrol (RES) has been associated with numerous pharmacological effects. Yet its pharmacokinetics is not clearly understood. It is known to get extensively metabolized into its sulfated and glucuronidated metabolites and has very low circulating RES concentrations in plasma. Although the concentrations of conjugated metabolites of RES have been reported to be much greater than that of RES, they have not been evaluated. This also becomes important in light of positive biological activities reported for sulfated metabolites of RES. Conjugation is a complex process which can sometimes be a reversible process and needs comprehensive evaluation to better understand RES and its metabolites' disposition. There has been a debate among the researchers regarding the differences in kinetics of preformed versus in vivo formed metabolites in the light of guidelines issued by regulatory bodies regarding metabolites in safety testing (MIST). We have addressed the above questions in this work, in addition to evaluating brain permeability of a potent RES analog, trimethoxy-trans-stilbene (TMS). Chapter 1 presents a detailed introduction, hypothesis and significance of my work. Chapter 2 includes the development and validation of a bioanalytical method for quantitation of RES and its metabolites on LC/MS/MS. We were able to develop and validate a robust bioanalytical method to quantitate RES and its four major metabolites resveratrol-4'-glucuronide (R4'G), resveratrol-3-glucuronide (R3G), resveratrol-4'-sulfate (R4'S) and resveratrol-3-sulfate (R3S). In Chapter 3, lung as a possible metabolizing organ for RES was evaluated. This study was performed in vivo in mouse model using multiple site of administration and single site of sampling approach. In vitro studies were also performed to confirm the in vivo results. Inter species differences in RES pulmonary metabolism were also studied. We observed lungs to be the major metabolizing organs for RES with inter species differences in its metabolism. Chapter 4 provides detailed pharmacokinetics of sulfated metabolites of RES, i.e. resveratrol-3-sulfate (R3S) and resveratrol-4'-sulfate (R4'S) in mouse model by both systemic and oral routes. In vitro studies were also conducted to test the desulfation in liver. Although we did not observe any significant RES in plasma, we observed from our in vitro studies that sulfated metabolites were desulfated in liver. Chapter 5 explains the detailed pharmacokinetics of glucuronidated metabolites of RES i.e. resveratrol-3-glucuornide (R3G) after both systemic and oral route. R3G was observed to undergo enterohepatic circulation. Explanation of R3G disposition in hepatocytes and enterocytes were proposed based on our own and reported results. In Chapter 6 we compared the differences in the kinetics of preformed versus in vivo formed metabolites using modeling and simulation approach. Individual models for disposition of RES, R3S and R3G were developed. These models were combined to give a global model for RES metabolism into R3S and R3G. Simulations were performed under two assumptions; preformed versus in vivo formed metabolite kinetics a) are same and b) they are not same. Our results reported that preformed and in vivo formed metabolite kinetics are not same at least for hydrophilic phase II metabolites. Chapter 7 includes method development and validation for quantitation of TMS in plasma and brain of mouse. Chapter 8 includes a steady state study to characterize the pharmacokinetic parameters of TMS, which was used to evaluate brain permeability of TMS. In summary we developed a robust bioanalytical method for direct quantitation of RES and its metabolites, found the lung to be a major metabolizing organ for RES, delineated complex kinetics of conjugated metabolites of RES, and showed differences in preformed versus in vivo formed metabolite kinetics and better brain permeability of TMS. / Pharmaceutical Sciences
40

Design of measurement circuits for SiC experiment : KTH student satellite MIST / Konstruktion av mätkretsar för SiC-experimentet

Ericson, Matthias, Silverudd, Johan January 2016 (has links)
SiC in Space is one of the experiments on KTH’s miniature satellite, MIST. The experiment carries out tests on bipolar junction transistors of silicon and silicon carbide. This thesis describes how the characteristics of a transistor can be measured using analog circuits. The presented circuit design will work as a prototype for the SiC in Space experiment. The prototype measures the base current, the collector current, the base-emitter voltage as well as the temperature of the transistor. This thesis describes how a test circuit may be designed. The selected design has been constructed in incremental steps, with each design choice explained. Different designs have been developed. The designs have been verified with simulations. We have also constructed and tested three different prototypes on breadboards and printed circuit boards. / SiC in Space är ett av experimenten på KTHs miniatyrsatellit, MIST. Experimentet utför test på bipolära transistorer av kisel och kiselkarbid. Detta examensarbete förklarar hur transistorns karakteristik kan mätas med analoga kretsar. Den framtagna kretsdesignen kommer att fungera som en prototyp till SiC in Space-experimentet. Prototypen mäter basströmmen, kollektorströmmen, bas-emitter-spänningen samt temperaturen för transistorn. Detta examensarbete förklarar hur en testkrets kan designas. Den valda designen byggs i inkrementella steg, där varje designval förklaras. Olika designer har utvecklats. Designerna har verifierats genom simuleringar. Vi har också konstruerat och testat tre olika prototyper på kopplingsdäck och kretskort.

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