Depth sensors in augmented reality solutions. Literature review

The emergence of depth sensors has made it possible to track – not only monocular cues – but also the actual depth values of the environment. This is especially useful in augmented reality solutions, where the position and orientation (pose) of the observer need to be accurately determined. This allows virtual objects to be installed to the view of the user through, for example, a screen of a tablet or augmented reality glasses (e.g. Google glass, etc.). Although the early 3D sensors have been physically quite large, the size of these sensors is decreasing, and possibly – eventually – a 3D sensor could be embedded – for example – to augmented reality glasses. The wider subject area considered in this review is 3D SLAM methods, which take advantage of the 3D information available by modern RGB-D sensors, such as Microsoft Kinect. Thus the review for SLAM (Simultaneous Localization and Mapping) and 3D tracking in augmented reality is a timely subject. We also try to find out the limitations and possibilities of different tracking methods, and how they should be improved, in order to allow efficient integration of the methods to the augmented reality solutions of the future.

Matkustavan muistin jäljillä : Travelling memories : lives in transition -symposium Helsingissä, 27.-28.11.2014

Seminaariraportti

Open access is possible! On the transition of a business model

Kai Karin Geschun's presentation at Kirjastoverkkopäivät, Helsinki 21.10.2015.

Monitorointimenetelmät membraanin likaantumisen seurantaan suodatuksen aikana

Membraani on ohut kalvo, jossa on pieniä nanomittakaavan reikiä, jotka erottavat partikkelit ja liuenneet yhdisteet liuoksesta. Membraanisuodatuksen käyttö on lisääntynyt merkittävästi vedenpuhdistuksessa, johtuen lisääntyneestä puhtaan veden tarpeesta ja tiukentuneista ympäristövaatimuksista. Tässä työssä esitellään reaaliaikaisia mittausmenetelmiä membraanin likaantumisen seurantaan. Esiteltyjä menetelmiä ovat suora havainnointi pinnan läpi, lasertriangulometria, varjoanalyysi, taittokykymittaus, kuvakatkaisu-menetelmä, partikkelin nopeusmääritys, radioisotooppinen merkintä ja ydinmagneettinen resonanssispektrometria. Mittausmenetelmien avulla likakerroksen paksuutta ja sen leviämistä on mahdollista seurata reaaliaikaisesti. Mittausmenetelmien soveltuvuus olemassa oleviin prosesseihin on vielä epävarmaa. Suurin osa menetelmistä on rajoittunut tiettyyn membraanin materiaaliin, tietynlaiseen membraanisuodatusprosessin rakenteeseen tai tiettyihin olosuhteisiin. Vallitsevien prosessiolosuhteiden lisäksi mittausanturin tulisi kestää myös puhdistusolosuhteet. Lisätutkimuksia tarvitaan, jotta voidaan löytää toimiva laitekokonaisuus tarvittavan tiedon tuottamiseen.

Optical and photoelectric properties of dry bacteriorhodopsin sensors

In this thesis, bacteriorhodopsin (BR) photosensor’s optical and electrical properties were studied. The BR sensor consisted of a dry film with BR in polyvinyl alcohol and covered with transparent conductors. In the experiments the BR photocycle was started with two lasers. The characteristics of the BR sensor were measured in two ways. The first approach was theoretical and it required knowing the laser parameters. The second way required assembling a measurement setup for the optical response measurements. However, no measurable results were obtained due to low laser power. The photoelectric response was measured in the experiments with two laser systems and the amplifier was tested. In the experiment with a Cavitar laser, the photoelectric response was obtained. In the experiment with FemtoFiber Pro laser, the photoelectric response was not measured. The expected amplitude of the response was obtained. The experimental data was analyzed and possible solutions for reducing the interference were given.

Hydrogen Sensor Application of Anodic Titanium Oxide Nanostructures

Hydrogen (H2) fuel cells have been considered a promising renewable energy source. The recent growth of H2 economy has required highly sensitive, micro-sized and cost-effective H2 sensor for monitoring concentrations and alerting to leakages due to the flammability and explosiveness of H2 Titanium dioxide (TiO2) made by electrochemical anodic oxidation has shown great potential as a H2 sensing material. The aim of this thesis is to develop highly sensitive H2 sensor using anodized TiO2. The sensor enables mass production and integration with microelectronics by preparing the oxide layer on suitable substrate. Morphology, elemental composition, crystal phase, electrical properties and H2 sensing properties of TiO2 nanostructures prepared on Ti foil, Si and SiO2/Si substrates were characterized. Initially, vertically oriented TiO2 nanotubes as the sensing material were obtained by anodizing Ti foil. The morphological properties of tubes could be tailored by varying the applied voltages of the anodization. The transparent oxide layer creates an interference color phenomena with white light illumination on the oxide surface. This coloration effect can be used to predict the morphological properties of the TiO2 nanostructures. The crystal phase transition from amorphous to anatase or rutile, or the mixture of anatase and rutile was observed with varying heat treatment temperatures. However, the H2 sensing properties of TiO2 nanotubes at room temperature were insufficient. H2 sensors using TiO2 nanostructures formed on Si and SiO2/Si substrates were demonstrated. In both cases, a Ti layer deposited on the substrates by a DC magnetron sputtering method was successfully anodized. A mesoporous TiO2 layer obtained on Si by anodization in an aqueous electrolyte at 5°C showed diode behavior, which was influenced by the work function difference of Pt metal electrodes and the oxide layer. The sensor enabled the detection of H2 (20-1000 ppm) at low operating temperatures (50–140°C) in ambient air. A Pd decorated tubular TiO2 layer was prepared on metal electrodes patterned SiO2/Si wafer by anodization in an organic electrolyte at 5°C. The sensor showed significantly enhanced H2 sensing properties, and detected hydrogen in the range of a few ppm with fast response/recovery time. The metal electrodes placed under the oxide layer also enhanced the mechanical tolerance of the sensor. The concept of TiO2 nanostructures on alternative substrates could be a prospect for microelectronic applications and mass production of gas sensors. The gas sensor properties can be further improved by modifying material morphologies and decorating it with catalytic materials.

Filopodia and stromal extracellular matrix as regulators of cancer cell invasion and growth

Bidirectional exchange of information between the cancer cells and their environment is essential for cancer to evolve. Cancer cells lose the ability to regulate their growth, gain the ability to detach from neighboring cells and finally some of the cells disseminate from the primary tumor and invade to the adjacent tissue. During cancer progression, cells acquire features that promote cancer motility and proliferation one of them being increased filopodia number. Filopodia are dynamic actin-rich structures extending from the leading edge of migrating cells and the main function of these structures is to serve as environmental sensors. It is nowadays widely appreciated, that not only the cancer cells, but also the surrounding of the tumor – the tumor microenvironment- contribute to cancer cell dissemination and tumor growth. Activated stromal fibroblasts, also known as cancer-associated fibroblasts (CAFs) actively participate on tumor progression. CAFs are the most abundant cell type surrounding the cancer cells and they are the main cell type producing the extracellular matrix (ECM) within tumor stroma. CAFs secrete growth factors to promote tumor growth, direct cancer cell invasion as well as modify the stromal ECM architecture. The aim of this thesis was to investigate the function of filopodia, particularly the role of filopodia-inducing protein Myosin-X (Myo10), in breast cancer cell invasion and metastasis. We found that Myo10 is an important regulator of basal type breast cancer spreading downstream of mutant p53. In addition, I investigated the role of CAFs and their secreted matrix on tumor growth. According to the results, CAF-derived matrix has altered organization and stiffness which induces the carcinoma cell proliferation via epigenetic mechanisms. I identified histone demethylase enzyme JMJD1a to be regulated by the stiffness and to participate in stiffness induced growth control.

Evaluation of the main energy scenarios for the global energy transition

Energy scenarios are used as a tool to examine credible future states and pathways. The one who constructs a scenario defines the framework in which the possible outcomes exist. The credibility of a scenario depends on its compatibility with real world experiences, and on how well the general information of the study, methodology, and originality and processing of data are disclosed. In the thesis, selected global energy scenarios’ transparency and desirability from the society’s point of view were evaluated based on literature derived criteria. The global energy transition consists of changes to social conventions and economic development in addition to technological development. Energy solutions are economic and ethical choices due to far-reaching impacts of energy decision-making. Currently the global energy system is mostly based on fossil fuels, which is unsustainable over the long-term due to various reasons: negative climate change impacts, negative health impacts, depletion of fossil fuel reserves, resource-use conflicts with water management and food supply, loss of biodiversity, challenge to preserve ecosystems and resources for future generations, and inability of fossil fuels to provide universal access to modern energy services. Nuclear power and carbon capture and storage cannot be regarded as sustainable energy solutions due to their inherent risks and required long-term storage. The energy transition is driven by a growing energy demand, decreasing costs of renewables, modularity and scalability of renewable technologies, macroeconomic benefits of using renewables, investors’ risk awareness, renewable energy related attractive business opportunities, almost even distribution of solar and wind resources on the planet, growing awareness of the planet’s environmental status, environmental movements and tougher environmental legislation. Many of the investigated scenarios identified solar and wind power as a backbone for future energy systems. The scenarios, in which the solar and wind potentials were deployed in largest scale, met best the set out sustainability criteria. In future research, energy scenarios’ transparency can be improved by better disclosure on who has ordered the study, clarifying the funding, clearly referencing to used sources and indicating processed data, and by exploring how variations in cost assumptions and deployment of technologies influence on the outcomes of the study.