A three-component laser Doppler anemometer was used to measure the fully developed, turbulent flow in a closed, symmetric, smooth-wall compound channel. Measurements were made across one quadrant of the cross-section since the flow was assumed symmetric. Measurements were made for a single channel Reynolds number. All mean velocity components were calculated and are reported. The mean velocity field results are in good agreement with results reported for similar geometries. The vector plots and the axial vorticity distribution reveal the existence of secondary flow cells in both the main channel and the flood plain. The maximum values of the secondary velocities are at the comer region, on the interface between the main channel and the flood plain. In this region the mean velocity gradients are large, indicating that this might be an area of high turbulence production. The distributions of all Reynolds stresses across the cross-section are reported. The Reynolds stress distributions show peak values near the interface corner region and small values near the center-line and on the axes of symn1etry of the channel. The turbulence kinetic energy distribution verifies the existence of high turbulence energy fluid in the comer region. / Master of Science

ABSTRACT Light emitting diodes of non-fully conjugated coil-like homopolymers and fully conjugated rigid-rod homopolymers with electron withdrawing or donating group were studied. A series of Poly[2,2-(m-2-X-phenylene)-4-4¡A-hexafluoroisopropane- bibenzoxazoles] (6F-PBO-X, with X = amine, hydrogen and nitro) and poly-p-(2-X- phenylene)-benzobisoxazole (PBO-X, with X = amine, hydrogen and nitro) were synthesized for light emitting diode applications to observe electroluminescence emission affected by electron withdrawing or donating group. All polymers were fabricated identically to form bi-layer light emitting diodes. In the devices, poly(3,4-ethylenedioxythiophene):poly(styrenesulfonite)(PEDOT:PSS) was applied to be a hole transport layer; indium tin oxide (ITO) was the anode; and aluminum was the cathode. Devices of the non-fully conjugated coli-like polymers (6F-PBO-X) and the fully conjugated rigid-rod polymers (PBO-X) all showed threshold voltage about 4 V. In the electroluminescence (EL) spectrum, the maximum intensity of non-fully conjugated polymer (6F-PBO-X) with amine (-NH2), hydrogen (-H) or nitro (-NO2) functional group was at 499 nm, 505 nm and 515 nm, respectively, showing a 20 nm wavelength shift. From ¡VNH2, -H and ¡VNO2 groups, their Commission International de l`Eclairage (C. I. E.) coordinates were (0.30, 0.46), (0.34, 0.45) and (0.40, 0.46), respectively. The EL maximum intensity for fully conjugated rigid-rod polymer PBO-X was at 521 nm (-NH2) and 474 nm (-NO2) showing a 50 nm wavelength shift. Their C. I. E. coordinates were (0.42, 0.45) and (0.25, 0.38), respectively. This is attributed to the fully conjugated, collinear, coplanar, rigid-rod polymers (PBO-X) backbone readily affected by the push-pull functional groups showing a large red shift.

Due to the Covid-19 pandemic, many companies have been forced to make their employees work from home, fully distributed. One of the work aspects affected by this change is meetings. The purpose of this study is to investigate what effects the fully distributed context have on meetings, meeting participants, and meeting leaders. To achieve this purpose, a qualitative single-case study was conducted. The empirical data were gathered from 15 interviews with employees at a large information and communications technology company in Linköping, Sweden. The theoretical framework including the fully distributed context, leadership, motivation, and attitudes, behaviors, and norms is the foundation for the analytical model used to analyze the empirical data. For meetings, it was found that the number of meetings has increased, meetings without fixed end times get longer, meetings need clear agendas and structures, and that meetings are booked in a tighter sequence without room for breaks. Using cameras during meetings increases participation but not if there are many meeting participants or when someone starts sharing their screen. It was found that inter-office meetings work better in the fully distributed context. Discussions are fewer and less lively in fully distributed meetings, but virtual fika1 is a kind of informal meeting that can help employees feel more connected and maintain interpersonal relations. For meeting participants, it was found that the fully distributed context has enabled participants to not be seen during meetings, to multitask more, to go on walks during meetings, and to attend more meetings. Fully distributed meetings offer participants more flexibility in meeting attendance but are also more difficult for participants to stay focused during. The perceived social pressure from the surrounding often determines how participants behave in meetings, for example if participants turn on their cameras or not. For meeting leaders, it was found that, contrary to the literature, meeting participants’ behavior affect the motivation of the meeting leader. Meeting participants' multitasking during meetings is considered positive for productivity but makes meeting leaders feel insecure as participants seem to listen less. Cameras can offer supportive feedback as the meeting leader can see the participants reactions, but it only works in smaller meetings. Fully distributed meetings demand more of meeting leaders who need to work harder to structure the meetings, force discussions, aim questions, and keep participants active. The results implicate that meeting leaders should set agendas for and structure meetings, implement breaks between meetings, and start meetings with some informal conversations. Moreover, meeting leaders should turn on their cameras in smaller meetings without screen sharing and aim questions at specific participants instead of posing open questions. At the end of this report, a number of suggestions for future studies on the topic of fully distributed meetings are proposed. 1Fika is Swedish for taking a break and sharing a cup of coffee or tea with friends or colleagues possibly, but not necessarily, with a little something to eat.

No description available.

In this thesis technical and economic analysis of Fiber Reinforced Composite Polymer (FRPC) bridges was performed. Current condition and main issues of conventional bridges in the world and in Lithuania are assessed, main defects are indicated. In this thesis FRPC is considered as an alternative solution for bridge construction. Application range of FRPC for bridge construction is classified and actual bridge examples are analysed. Further, main properties of FRPC are introduced, taking into account influence of material composition, manufacturing technology, long term effects and advantages over conventional materials. Load-deformation, failure behavior analysis of FRPC bridge decks and bridges revealed advantages over conventional bridge solutions and design issues. In addition, existing codes for FRPC bridge design are analysed, design peculiarities are emphasized and current problems are identified. Performed Life Cycle Cost (LCC) analysis revealed financial viability of FRPC bridges. Finally, main conclusions and problems to be solved are stated and FRPC application potential for bridges construction in Lithuania is suggested. Performed analysis revealed that FRPC application for bridges construction is technically and economically viable solution. / Šiame magistriniame darbe atlikta Pluoštais Armuotų Polimerinių Kompozitinių (PAPK) tiltų techninė ir ekonominė analizė. Nagrinėjama esama pasaulio ir Lietuvos tiltų būklė, nustatytos būdingos problemos bei defektai. Šiame darbe PAPK yra svarstoma kaip alternativi medžiaga tiltų statybai. Atlikta PAPK panaudojimo klasifikacija tiltų statybai, analizuojami esami PAPK tiltų pavyzdžiai bei jų paplitimas. Toliau nustatomos mechaninės bei fizinės PAPK savybės, atsižvelgiant į medžiagos sandarą, gamybos būdą, ilagalaikius veiksnius ir privalumus lyginant su plienu ir gelžbetoniu. Pagal atliktą PAPK tiltų ir perdangų apkrovos-deformacijų, suirimo analizę nustatyta elementų elgsena, pateiktos pagrindinės problemos bei privalumai palyginus su tradiciniais tiltų sprendiniais. Taip pat išnagrinėtos PAPK tiltų projektavimų normos, pateikti skaičiavimų ypatumai bei problemos. Paskutiniame skyriuje atlikta Gyvavimo Ciklo Kainos analizė parodė PAPK tiltų finansinį įgyvendinamumą. Darbo pabaigoje pateikiamos pagrindinės išvados, rezultatai, spręstinos problemos bei PAPK tiltų panaudojimo rekomendacijos Lietuvoje. Atlikta techninė ir ekonominė analizė parodė, jog PAPK panaudojimas tiltų statybai yra techniškai ir ekonomiškai efektyvus sprendimas.

Renormalization group analysis is a useful tool for studying critical behaviour of stochastic systems. In this thesis, field-theoretic renormalization group will be applied to the scalar model representing directed percolation, known as Gribov model, in presence of the random velocity field. Turbulent mixing will be modelled by the compressible form of stochastic Navier-Stokes equation where the compressibility is described by an additional field related to the density. The task will be to find corresponding scaling properties.

Title: Homomorphic encryption and coding theory Author: Veronika Půlpánová Department: Department of algebra Supervisor: RNDr. Michal Hojsík, Ph.D., Department of algebra Abstract: The current mainstream in fully homomorphic encryption is the appro- ach that uses the theory of lattices. The thesis explores alternative approaches to homomorphic encryption. First we present a code-based homomorphic encrypti- on scheme by Armknecht et. al. and study its properties. Then we describe the family of cryptosystems commonly known as Polly Cracker and identify its pro- blematic aspects. The main contribution of this thesis is the design of a new fully homomorphic symmetric encryption scheme based on Polly Cracker. It proposes a new approach to overcoming the complexity of the simple Polly Cracker - based cryptosystems. It uses Gröbner bases to generate zero-dimensional ideals of po- lynomial rings over finite fields whose factor rings are then used as the rings of ciphertexts. Gröbner bases equip these rings with a multiplicative structure that is easily algorithmized, thus providing an environment for a fully homomorphic cryptosystem. Keywords: Fully homomorphic encryption, Polly Cracker, coding theory, zero- dimensional ideals

Master of Science / Department of Electrical and Computer Engineering / William B. Kuhn / A technique for measuring and characterizing transistor noise is presented. The primary goal of the measurements is to locate the 1/f noise corner for select transistors in Silicon-on-Sapphire processes. Additionally, the magnitude of the background channel noise of each transistor is measured. With this data, integrated circuit (IC) engineers will have a qualitative and quantitative resource for selecting transistors in designs with low noise requirements. During tests, transistor noise behavioral change is investigated over varying channel lengths, device type (N-type and P-type), threshold voltage, and bias voltage levels. Noise improvements for increased channel lengths from minimal, 1.0μm, and 4.0μm are measured. Transistors with medium and high threshold voltages are tested for comparison of their noise performance. The bias voltages are chosen to represent typical design values used in practice, with approximately 400 mV overdrive and a drain-to-source voltage range of 0.5 to 3.0V. The transistors subjected to tests are custom designed in Peregrine’s 0.5μm (FC) and 0.25μm (GC) Silicon-on-Sapphire (SOS) processes. In order to allow channel current noise to dominate over other circuit noise, the transistors have extraordinarily large aspect ratios (~2500 - 5000). The transistor noise produced is amplified and measured over a frequency range of 1kHz - 100MHz. This range allows the measurement of each device’s low and high frequency noise spectrum and resulting noise corner.

Flexible manufacturing is something that most companies is aiming to accomplish due to the increased demand for variety and a competitive global market. This thesis report includes an introduction to the automation concept and the development towards flexible automation. A general flexible assembly cell is presented and its content and requirements are discussed. The work has been done with focus on an assembly process with dedicated fixtures at VCE (Volvo Construction Equipment). Based on the literature review and the general example, a list of actions to take while planning and implementing a process is developed. The actions roughly include: mapping of the process, defining goals, investigation of automation level, holistic view while planning, definition of the need for flexibility, investment plan, designing and comparing concepts, investigation of possible issues and implementation in small scale. The current manual process at VCE is presented and analysed. Three concepts are designed with product flexibility as an alternative to processes in which traditional dedicated fixtures are used. The designed concepts are a fully automated concept, a hybrid concept with separated workspace and a human-robot collaboration. Finally, the concepts are analysed and compared based on following parameters: productivity, product cost, investment, flexibility, space requirement and setup time. One final comparing summary of the concepts is done. The analysis shows that a fully automated concept is to prefer in this case. However, a human-robot collaboration could be appropriate to use if the process is expected to improve with the human workforce. Examples of when it could be reasonable to use human-robot collaboration despite this are: if the task provides better quality when conducted by human or if the task is complex to automate.

Segmentation of mammograms pertains to assigning a meaningful label to each pixel found in the image. The segmented mammogram facilitates both the function of Computer Aided Diagnosis Systems and the development of tools used by radiologists during examination. Over the years many approaches to this problem have been presented. A surge in the popularity of new methods to image processing involving deep neural networks present new possibilities in this domain, and this thesis evaluates mammogram segmentation as an application of a specialized neural network architecture, U-net. Results are produced on publicly available datasets mini-MIAS and CBIS-DDSM. Using these two datasets together with mammograms from Hologic and FUJI, instances of U-net are trained and evaluated within and across the different datasets. A total of 10 experiments are conducted using 4 different models. Averaged over classes Pectoral, Breast and Background the best Dice scores are: 0.987 for Hologic, 0.978 for FUJI, 0.967 for mini-MIAS and 0.971 for CBIS-DDSM.