246 research outputs found

    Near-Field UHF RFID Transponder with a Screen-Printed Graphene Antenna

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    As a method of producing RFID tags, printed graphene provides a low-cost and eco-friendly alternative to the etching of aluminum or copper. The high resistivity of graphene, however, sets a challenge for the antenna design. In practice, it has led to using very large antennas in the UHF RFID far field tags demonstrated before. Using inductive near field as the coupling method between the reader and the tag is an alternative to the radiating far field also at UHF. The read range of such a near field tag is very short, but, on the other hand, the tag is extremely simple and small. In this paper, near field UHF RFID transponders with screen-printed graphene antennas are presented and the effect of the dimensions of the tag and the attachment method of the microchip studied. The attachment of the microchip is an important step of the fabrication process of a tag that has its impact on the final cost of a tag. Of the tags demonstrated, even the smallest one with the outer dimensions of 21 mm * 18 mm and the chip attached with isotropic conductive adhesive (ICA) was readable from a distance of 10 mm with an RF power marginal of 19 dB, which demonstrates that an operational and small graphene-based UHF RFID tag can be fabricated with low-cost industrial processes.Comment: 8 pages, 9 figures. IEEE Transactions on Components, Packaging and Manufacturing Technology, 201

    Aikuisen kuhan liikkeet ja elinympäristönvalinta Oulujoen Pyhäkosken patoaltaassa

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    Two-dimensional aquatic habitat quality modelling

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    Two-dimensional modelling of aquatic habitats of different organisms was developed, analysed and validated. The habitats and abundance of salmon, brown trout, grayling, pikeperch, stone loach, bullhead, crayfish and Persicaria Foliosa were modelled. In fish habitat modelling, two-dimensional hydraulic modelling was used, where wind induced potential lake bed erosion was calculated for crayfish. Models were calibrated with many types of biological material and tested. The effect of different methods of using biological information and of carrying out field measurements and hydraulic modelling were analysed. The selection of habitat preference curves and the density of field measurements were found to have the greatest effect on results. The models for salmonids and Persicaria Foliosa were found out to work consistently in sensitivity tests. The model was validated against observed habitat use. With the models, abundance of salmonids and Persicaria Foliosa could be predicted. Transferability of the habitat model of crayfish to different types of lakes must be further developed and confirmed. Two-dimensional habitat models were found to work consistently if appropriately applied and used, in prediction of abundance of organisms despite a large natural variability and dynamics of habitat selection and the difficulty to accurately observe habitat selection making the validation of habitat models difficult

    Schools as professional learning communities

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    The main objectives in building professional learning communities are to improve teachers’ professionalism and well-being, and create positive impacts on student learning. It is a question of changing the school culture. The main objective of this quantitative study was to investigate the maturity level of thirteen Finnish schools as professional learning communities from the perspectives of school culture, leadership, teaching, and professional development. The participants’ perceptions indicated a culture of collegiality, trust and commitment as common strengths at all schools. The school cultures supported professional collaboration, and the teachers had the knowledge, skills and dispositions to engage in professional collaboration. The challenges were related to structural conditions, especially the lack of collaboration time. Three school profiles were identified in the cluster analysis from the viewpoint of maturity as professional learning communities. Statistically significant differences between the three clusters were found in organizational and operational characteristics.Peer reviewe

    Review of LTCC technology for millimeter waves and photonics

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    VTT Technical Research Centre of Finland Ltd. has developed and utilized Low Temperature Co-fired Ceramic (LTCC) technology for about 25 years. This paper presents our activities related to photonics and millimetre-waves, including also a relevant literature survey. First a short summary of the technology is given. Especially, the unique features of LTCC technology are described in more details. In addition, several examples have been given to show the validity of LTCC technology in these high-performance fields

    Review of LTCC Technology for Millimeter Waves and Photonics

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    VTT Technical Research Centre of Finland Ltd. has developed and utilized Low Temperature Co-fired Ceramic (LTCC) technology for about 25 years. This paper presents our activities related to photonics and millimetre-waves, including also a relevant literature survey. First a short summary of the technology is given. Especially, the unique features of LTCC technology are described in more details. In addition, several examples have been given to show the validity of LTCC technology in these high-performance fields
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