The integration and use of superhydrophobic surfaces to microfluidic systems were investigated in this work. Superhydrophobic surfaces are believed to have the ability to reduce the hydrodynamic resistance of a microchannel, reduce the risk of clogging due to reduced liquid contact with the microchannel walls and reduce the losses in a microfluidic system. Two superhydrophobic surfaces with different fabrication methods were evaluated. It was found that fabrication methods that add material to the microchannel walls do not work well in microchannels. Methods that instead transform a present surface are more suitable for a microfluidic system. To visualize the superhydrophobic surfaces an AFM and SEM were used. By combining the information a good picture of the superhydrophobic surfaces where sometimes achieved. To investigate the impact of the superhydrophobic surfaces, two different designs of microchannels were created on silicon wafers and compared with microchannels created in polydimethylsiloxane. One design used straight channels and the other aimed to maximize the resistance reduction by patterning the walls of the microchannel. Due to manufacturing issues only the straight channels were evaluated, where it was found that superhydrophobic surfaces can increase the flow rate of a microfluidic system. However, the result was not reproduced easily. The reason is currently unknown but believed to originate from flaws in the manufacturing process. A simple version of a device that uses superhydrophobic surfaces to seal microfluidic systems was successfully used and reused. A device with a more refined design could offer the ability to create microfluidic systems with detachable lids. Finally, to further increase the availability of the properly created superhydrophobic surface an alternative functionalization step should be found.

As information technology pervades our lives we have increasingly come to rely on these evermore sophisticated and ubiquitous items of equipment. Portability and the desire to be connected around the clock has driven the rapid growth in adoption of mobile devices that enable us to talk, message, tweet and inform at will, whilst providing a means to shop and administer bank accounts. These high value, high risk, desirable devices are increasingly the target of theft and improvement in their protection is actively sought by Governments and security agencies. Although forms of security are in place they are compromised by human reluctance and inability to administer them effectively. With typical users operating across multiple devices, including traditional desktop PCs, laptops, tablets and smartphones, they can regularly find themselves having a variety of devices open concurrently. Even if the most basic security is in place, there is a resultant need to repeatedly authenticate, representing a potential source of hindrance and frustration. This thesis explores the need for a novel approach to user authentication, which will reduce the authentication burden whilst providing a secure yet adaptive security mechanism; a so called Authentication Aura. It proposes that the latent security potential contained in surrounding devices and possessions in everyday life can be leveraged to augment security, and provides a framework for a distributed and cooperative approach. An experiment was performed to ascertain the technological infrastructure, devices and inert objects that surround individuals throughout the day. Using twenty volunteers, over a fourteen-day period a dataset of 1.57 million recorded observations was gathered, which confirmed that between 6am and 12pm a significant device or possession is in near proximity 97.84% of the time. Using the data provided by the experiment as the basis for a simulation of the framework, it suggests a reduction of up to 80.36% in the daily number of required authentications for a user operating a device once every 30 minutes, with a 10 minute screen lock in place. Examining the influence of location alone indicated a reduction of 50.74% in user interventions lowering the average from 32 to 15.76, the addition of the surroundings reducing this further to 13.00. The analysis also investigated how a user’s own authentication status could be used to negate the need to repeatedly manually authenticate and it was found that it delayed the process for up to 90 minutes for an individual user. Ultimately, it confirms that during device activation it is possible to remove the need to authenticate with the Authentication Aura providing sufficient assurance.

京都大学 / 0048 / 新制・課程博士 / 博士(エネルギー科学) / 甲第22794号 / エネ博第408号 / 新制||エネ||78(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社会・環境科学専攻 / (主査)教授 石原 慶一, 准教授 奥村 英之, 教授 佐川 尚 / 学位規則第4条第1項該当 / Doctor of Energy Science / Kyoto University / DFAM

Among the alternatives to conventional Indium Tin Oxide (ITO) used in making transparent conducting electrodes, the random metal nanowire (NW) networks are considered to be superior offering performance at par with ITO. The performance is measured in terms of sheet resistance and optical transmittance. However, as the electrical properties of such random networks are achieved thanks to a percolation network, a minimum size of the electrodes is needed so it actually exceeds the representative volume element (RVE) of the material and the macroscopic electrical properties are achieved. There is not much information about the compatibility of this minimum RVE size with the resolution actually needed in electronic devices. Furthermore, the efficiency of NWs in terms of electrical conduction is overlooked. In this work, we address the above industrially relevant questions - 1) The minimum size of electrodes that can be made based on the dimensions of NWs and the material coverage. For this, we propose a morphology based classification in defining the RVE size and we also compare the same with that is based on macroscopic electrical properties stabilization. 2) The amount of NWs that do not participate in electrical conduction, hence of no practical use. The results presented in this thesis are a design guide to experimentalists to design transparent electrodes with more optimal usage of the material.

Les conditions nécessaires pour obtenir des céramiques transparentes (absence de porosité, absence de seconde phase) requièrent une totale maitrise de chacune des étapes (synthèse, mise en forme, frittage) intervenant dans le processus, ce qui rend encore difficile l'industrialisation d'un procédé d'élaboration reproductible. Dans ce contexte, ce travail de thèse s’est focalisé à développer et évaluer la capacité du procédé de frittage micro-ondes à améliorer la robustesse du processus d'élaboration de spinelle transparent. La mise en place d'un dispositif de dilatométrie optique et une nouvelle technique de calibration originale, basée sur la fusion d'oxyde, ont permis de caractériser le frittage micro-ondes du spinelle pur avec une plus grande confiance. Même si aucun effet lié au procédé micro-onde n’a pu être mis en évidence pour le frittage du spinelle pur (trajectoire de frittage, mécanisme de densification et évolution de la porosité identiques), ces travaux ont démontré que l’impact de dopants pouvait être amplifié en présence du rayonnement micro-ondes. Ainsi, un décalage des courbes de retrait vers les basses températures a été observé lors du frittage micro-ondes du spinelle dopé avec TiO2 et MgO. L'existence d'un couplage particulier entre les défauts ponctuels chargés (lacunes, cations interstitiels) et le champ électrique pourrait être à l'origine de ce phénomène. Ces travaux de thèse ont également démontré la faisabilité de fritter des pièces de spinelle carrées de grandes dimensions (< 65 mm) compatibles avec un post-traitement HIP, en vue d'obtenir des pièces transparentes. Pour cela, un four micro-ondes monomode 915 MHz a été automatisé et une cellule de frittage adaptée a été développée. A l'issue du traitement HIP, les pièces ont présenté une transparence et des propriétés mécaniques (dureté; ténacité) comparables à celles des pièces pré frittées par voie conventionnelle. / The elaboration of transparent ceramics (no porosity, no second phase) requires a strict control of all steps of the process (synthesis, shaping, sintering). As a result, the industrialization of a reproducible process is still difficult to achieve. In this context, this thesis has focused on developing and evaluating the ability of the microwave sintering process to improve the robustness of the transparent spinel elaboration process.The set-up of an optical dilatometer and a new original calibration method, based of melting of different oxides, allowed to characterize the microwave sintering with a greater confidence. Even if no microwave effect has been observed on the sintering of pure spinel (identical sintering trajectory, densification mechanism and porosity evolution), this work has shown an amplification of the impact of dopants during microwave sintering. A shift of the shrinkage curves towards the low temperatures was observed during the microwave sintering of the spinel doped with TiO2 and MgO. The existence of a particular interaction between charged point defects (vacancies, interstitial cations) and the electric field could explain this phenomenon.This work thesis has shown also the feasibility of sintering of large square spinel pieces (< 65 mm) compatible with post treatment HIP in order to produce transparent ceramics. For this purpose, the microwave system working at 915 MHz was automatized and a new sintering configuration was developed. After a post-treatment, the transparency and mechanical properties (hardness; tenacity) of microwave pre-sintered samples were comparable with those of samples sintered by conventional heating.

The purpose of this Master Thesis has been to investigate the possibilities for a new type of noise reduction solution that could decrease the negative effects resulting from larger traffic roads. The idea has been to construct a noise barrier with a roof – like a tunnel placed on a road. The choice of material has been focused on transparent materials in order to lower visual intrusion and barrier effects. This project idea is called the Noise tunnel. After having investigated the current offer of noise solutions, it has been concluded that these solutions rarely provide a sufficient level of noise reduction – at least not when government regulations of acceptable noise levels are applied. To reach these acceptable noise levels at large traffic roads, noise barriers must be constructed at a larger scale or else the roads must be built below ground level. The Noise tunnel has therefore been investigated as an alternative noise solution. With the reduced noise levels resulting from the Noise tunnel, it will be possible to exploit new land for construction –something which would contribute to the funding of the Noise tunnel. In order to investigate the Noise tunnel in a more concrete way, a part of Nynäsvägen has been studied. Nynäsvägen is a large road situated south of Stockholm, and some parts of the road, as well as its surroundings, suffer from severe noise problems. Moreover, there is unexploited land available near Nynäsvägen, and this could be used for constructions. The result of the investigations shows that the Noise tunnel is approximately 10 times more expensive than a noise barrier, but 10 times cheaper than decking over the road. Furthermore, it has been found that it is possible to construct the Noise tunnel with today’s production methods. This conclusion is supported by both primary research and observations from similar projects conducted abroad. It has been found that the Noise Tunnel represent an alternative solution at large traffic roads in urban environments where noise problems are of concern. This thesis concludes that although there are no technical problems preventing the Noise tunnel from becoming reality, the incentives to implement it are likely to represent a greater barrier.

Hur långt kan man egentligen gå innan man korsar gränsen för det privata i en bostad, när blir en bostad dålig för att huvudmålet varit att tillföra kontexten och området något av värde med bostaden som verktyg? I denna gestaltningsstudie har syftet varit att komma så nära gränsen för vad en bostad tål i offentlighet utan att den blir oattraktiv. Studien har undersökt vad som händer med bostadens planlösning när utsidan sätter förutsättningarna. Resultatet visar att bostaden har stora möjligheter att vara öppen och transparent mot sin omgivning, men för att de boende inte ska glömmas bort, krävs medveten planlösning och även en reflekterande utformning av utsidan med cykelstråk, anvisade gångvägar m.m. Kan dessutom den transparenta fasaden få en funktion för de boende från insidan sett, det vill säga med en tydligt riktad kvalitativ utsikt eller kanske en funktionell utsikt på t.ex. lekområdet, lekplasten eller dyl. jämställs utsidan med insidan samtidigt som huvudmålet med den offentliga bostaden uppfylls. / How far can you actually go before you crosses the boundary of the privacy in a home, when does a home get bad because the main goal has been to provide the context and the area with something of value. In this design study, the aim has been to get as close as possible to the limit of what a home can withstand in public without making it unattractive. The study has examined what happens to the property in plan when the outside set the conditions. The result shows that the home has large opportunities to be open and transparent to its surroundings, but to not forget the residents, requires conscious plan and also a reflective design of the exterior with cycle paths , designated walkways etc. If the transparent facade aswell get a function for the residents from within speaking ,like a clear directional qualitative view or perhaps a functional view on eg. spawning area, playground or similar, this equated the outside with the inside , while the main goal of public housing although is met.

Transparent exopolymer particles (TEP) have been reported as one of the main factors of membrane fouling in seawater reverse osmosis (SWRO) process. Research has been focused on algal TEP so far, overlooking bacterial TEP. This thesis investigated the effects of coagulation on removal of bacterial TEP/TEP precursors in seawater and subsequent reduction on TEP fouling in ultrafiltration (UF), as a pretreatment of SWRO. Furthermore, the performance of pretreatment (coagulation + UF) has been investigated on a bench-scale SWRO system. TEP/TEP precursors were harvested from a strain of marine bacteria, Pseudoalteromonas atlantica, isolated from the Red Sea. Isolated bacterial organic matter (BOM), containing 1.5 mg xanthan gum eq./L TEP/TEP precursors, were dosed in Red Sea water to mimic a high TEP concentration event. Bacterial TEP/TEP precursors added to seawater were coagulated with ferric chloride and aluminum sulfate at different dosages and pH. Results showed that ferric chloride had a better removal efficiency on TEP/TEP precursors. Afterwards, the non-coagulated/coagulated seawater were tested on a UF system at a constant flux of 130 L/m2h, using two types of commercially available membranes, with pore sizes of 50 kDa and 100 kDa, respectively. The fouling potential of coagulated water was determined by the Modified Fouling Index (MFI-UF). Transmembrane pressure (TMP) was also continuously monitored to investigate the fouling development on UF membranes. TEP concentrations in samples were determined by the alcian blue staining assay. Liquid chromatography-organic carbon detection (LC-OCD) was used to determine the removal of TEP precursors with particular emphasis on biopolymers. Finally, SWRO tests showed that TEP/TEP precursors had a high fouling potential as indicated by MFI-UF, corresponding to the TMP measurements. Coagulation could substantially reduce TEP/TEP precursors fouling in UF when its dosage was equal or higher than 0.2 mg Fe/L. The flux decline experiments showed that coagulation + UF pretreated water had a smaller fouling potential than MF pretreated water. This thesis also provides useful and practical information on controlling bacterial TEP/TEP precursors fouling in UF and RO systems.

3D display technology is limited by the user's ability to interact with displays without being connected to external equipment. In order to feel tactile feedback in conjunction with displays, ultrasonic sound pressure fields have been created; however, ceramic transducers interfere with the user's immersive experience. We have created transparent ultrasonic transducers using capacitive micromachined ultrasonic transducer (CMUT) and piezoelectric micromachined ultrasonic transducer (PMUT) technology that allow the user to remain immersed in the experience while interacting with the display. Individual transparent piezoelectric transducers made with indium tin oxide (ITO) and polyvinylidene fluoride (PVDF) generate 66.9dB with 91.6% transparency. Samples were phased and modulated using a field programmable gate array (FPGA) in a 36-element array.

No description available.