| 1. |
- Karlsson, Fredrik, et al.
(author)
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Sensor Fused Indoor Positioning Using Dual Band WiFi Signal Measurements
- 2015
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In: 2015 European Control Conference (ECC). - 9783952426937 ; , s. 1669-1672
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Conference paper (peer-reviewed)abstract
- In this paper, signal strengths from known WiFi access points are used together with a particle filter to perform indoor navigation. It is shown that more information is obtained by using signals of both 2.4 and 5.0 GHz, compared to using only one frequency. Thus, using both frequencies provides a more accurate positioning. The second contribution is an algorithm where WiFi measurements are combined with pedestrian dead reckoning (PDR), which is based on step counting using an accelerometer and hypotheses of the heading using a gyroscope. This was found to provide further accuracy compared to more conventional methods.
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| 2. |
- Amloy, Supaluck, et al.
(author)
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Excitons and biexcitons in InGaN quantum dot like localization centers
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Other publication (other academic/artistic)abstract
- Indium segregation in a narrow InGaN single quantum well creates quantum dot (QD) like exciton localization centers. Cross section transmission electron microscopy reveals varying shapes and lateral sizes in the range ~1-5 nm of the QD-like features, while scanning near field optical microscopy demonstrates a highly inhomogeneous spatial distribution of optically active individual localization centers. Microphotoluminescence spectroscopy confirms the spectrally inhomogeneous distribution of localization centers, in which the exciton and the biexciton related emissions from single centers of varying geometry could be identified by means of excitation power dependencies. Interestingly, the biexciton binding energy (Ebxx) was found to vary from center to center, between 3 to -22 meV, in correlation with the exciton emission energy. Negative binding energies justify the three-dimensional quantum confinement, which confirms QD-like properties of the localization centers.! The observed energy correlation is proposed to be understood as variations of the lateral extension of the confinement potential, which would yield smaller values of Ebxx for reduced lateral extension and higher exciton emission energy. The proposed relation between lateral extension and Ebxx is further supported by the exciton and the biexciton recombination lifetimes of a single QD, which suggest a lateral extension of merely ~3 nm for a QD with strongly negative Ebxx = -15.5 meV.
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| 3. |
- Amloy, Supaluck, et al.
(author)
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Excitons and biexcitons in InGaN quantum dot like localization centers
- 2014
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In: Nanotechnology. - : IOP Publishing. - 0957-4484 .- 1361-6528. ; 25:49, s. 495702-
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Journal article (peer-reviewed)abstract
- Indium segregation in a narrow InGaN single quantum well creates quantum dot (QD) like exciton localization centers. Cross-section transmission electron microscopy reveals varying shapes and lateral sizes in the range ∼1–5 nm of the QD-like features, while scanning near field optical microscopy demonstrates a highly inhomogeneous spatial distribution of optically active individual localization centers. Microphotoluminescence spectroscopy confirms the spectrally inhomogeneous distribution of localization centers, in which the exciton and the biexciton related emissions from single centers of varying geometry could be identified by means of excitation power dependencies. Interestingly, the biexciton binding energy (Ebxx) was found to vary from center to center, between 3 to −22 meV, in correlation with the exciton emission energy. Negative binding energies are only justified by a three-dimensional quantum confinement, which confirms QD-like properties of the localization centers. The observed energy correlation is proposed to be understood as variations of the lateral extension of the confinement potential, which would yield smaller values of Ebxx for reduced lateral extension and higher exciton emission energy. The proposed relation between lateral extension and Ebxx is further supported by the exciton and the biexciton recombination lifetimes of a single QD, which suggest a lateral extension of merely ∼3 nm for a QD with strongly negative Ebxx = −15.5 meV.
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| 4. |
- Bashir, Tariq, 1981-, et al.
(author)
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Cellulosic Smart Textile Fibers based on Organic Electronics
- 2016
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Conference paper (peer-reviewed)abstract
- The paradigm shift of merging structural properties of materials with other functionalities prevails and cellulose based fibres are no exception. For the realisation of so called smart materials, including smart textiles, electrical conductivity is of special importance, enabling sensorics, signal transmission, energy supply, energy generation, and actuation. We here discuss taking use of the advancement within the organic electronics community of conjugated polymeric systems producing smart textile fibres for inclusion into garment as well as interior and technical textiles. Specifically, poly(3,4-ethylenedioxythiophene) known as PEDOT is studied as a model system. PEDOT has relevance being a working horse within the organic electronics community. Our emerging pilot line is based on creating conductivity by vapour polymerization of EDOT monomers on an oxidant coated textile fibre where these could be taken from arrange of materials. Here we focus on cellulose based fibres. It is shown that Tencell-Lyocell is a suitable substrate offering many anchoring sites and that multiple depositions with layers deposited directly on each other decreased the resistance from 5.1 (± 1.6) kΩ/10 cm to 1.0 (± 0.1) kΩ/10 cm, for one layer and multiple layers respectively. Furthermore, adding 15 wt. % of the copolymer PEG-PPG-PEG to the oxidant solution decreased the resistance from 6.8 (± 1.2) kΩ/10 cm to 3.9 (± 0.8) kΩ/10 cm.
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| 5. |
- Gren, Anna, et al.
(author)
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Energianvändning i bebyggelse - boendes och aktörers val av teknik : Antologi från forskarskolan program energisystem
- 2007
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Book (other academic/artistic)abstract
- Energianvändning är grunden för välstånd och samhällsutveckling. Men vårt sätt att använda energi orsakar miljöpåverkan som i värsta fall kan rasera grunden inte bara för välstånd och samhällsutveckling utan också ytterst för existensen av allt liv på jorden. Vilka är möjligheterna att förändra energianvändningen så att den blir miljömässigt, socialt och ekonomiskt uthållig? Detta är en process som i mycket måste utgå från vad människor gör i sin vardag, i yrkeslivet och som konsumenter och användare av energi i olika aktiviteter. Antologin behandlar energianvändning i bebyggelse utifrån de valmöjligheter som olika aktörer – professionella och hushåll – har när det gäller att bygga och bo i energisnåla hus, att installera och bruka teknik som är energieffektiv och som utnyttjar förnybar energi, till exempel solenergi.Boken vänder sig till alla som har professionellt intresse för frågor om energianvändning i bebyggelse som till exempel aktörer som planerar, bygger och förvaltar byggnader. Den vänder sig också till hushållen, som bor i husen och använder energi. Boken vill vidare visa hur teknisk och samhällsvetenskaplig forskning kan kombineras för att nå ny kunskap om processer i så komplexa sociotekniska system som moderna energisystem.
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| 6. |
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| 7. |
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| 8. |
- Hsu, Chih-Wei, et al.
(author)
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Controlled Growth of GaN Pyramidal template hosting InGaN Quantum Dots
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Other publication (other academic/artistic)abstract
- The emission properties of InGaN grown on hexagonal GaN pyramids with various pitch distances (PD) are studied. Emissions associated with InGaN quantum wells (QWs) and InGaN quantum dots (QDs) can be identified. The emission energies of InGaN QWs and QDs shift toward opposite directions with increasing PD; red-shift for QWs and blue-shift for QDs. Based on the source supply mechanism in a selective area growth process, the formation of InGaN QDs on GaN pyramids is believed to be a combined effect of Stranski-Krastanow growth mode and spinodal decomposition taking place at the microscopic (0001) surfaces on GaN pyramids.
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| 9. |
- Karlsson, Fredrik, et al.
(author)
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Measured and predicted energy demand of a low energy building : Important aspects when using building energy simulation
- 2007
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In: Building Services Engineering Research & Technology. - : SAGE Publications. - 0143-6244 .- 1477-0849. ; 28:3, s. 223-235
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Journal article (peer-reviewed)abstract
- Three different simulation tools were used to simulate a low energy terraced house in the south of Sweden. The software tools all use dynamic models to calculate, for example, the energy demand for heating and the indoor temperatures. The aim of this paper is to discuss the relative importance to the annual energy demand of different energy aspects of a Swedish low-energy house. Both measured and simulated values are considered and compared. The focus is on the impact of choice of software, the habits of the tenants, and the relative impact of different design parameters such as ventilation rates. The measured values for total electricity demand range from about 6000 kWh to over 12000kWh, the average demand being 8020kWh. The annual predicted total energy demand using three different simulation software tools deviated by about 2%. The energy use deviation due to airflow control was about 10%, and the deviation due to differences in heat exchanger efficiency was about 20% and the deviation in annual energy use due to differences in internal gains due to differences in tenant habits, assumed in the models, was 7%. Furthermore, when comparing the predicted energy use during the design process of the low-energy building with actual measurements after the tenants have moved in, these differ about 50% in average for this specific case. Practical application: Building energy simulation software is often used to make predictions of how different construction materials, design principles and operation influence the energy balance and indoor thermal comfort. It is therefore important that the output of these software tools is trustworthy and accurate. This paper discusses the importance of accurate input data during the design process in order to achieve a valid prediction of energy use with emphasis on tenants' behaviour. It was shown that the deviations in a parametric study were larger than the deviations in the comparison between the results from the three simulation tools. This indicates a need for more accurate models for modelling tenant behaviour and habits rather than more accurate building component models.
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| 10. |
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