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Nordén, Lars-Åke
Alternative names
Publications (10 of 29) Show all publications
Nordén, L.-Å., Mannila, L. & Pears, A. (2017). Development of a self-efficacy scale for digital competences in schools. In: 2017 IEEE Frontiers in Education Conference (FIE): . Paper presented at IEEE Frontiers in Education Conference (FIE).
Open this publication in new window or tab >>Development of a self-efficacy scale for digital competences in schools
2017 (English)In: 2017 IEEE Frontiers in Education Conference (FIE), 2017Conference paper, Published paper (Refereed)
National Category
Computer Sciences
Research subject
Computer Science with specialization in Computer Science Education Research
Identifiers
urn:nbn:se:uu:diva-337184 (URN)10.1109/FIE.2017.8190673 (DOI)
Conference
IEEE Frontiers in Education Conference (FIE)
Available from: 2017-12-21 Created: 2017-12-21 Last updated: 2018-06-05Bibliographically approved
Heintz, F., Mannila, L., Nordén, L.-Å., Parnes, P. & Regnell, B. (2017). Introducing Programming and Digital Competence in Swedish K–9 Education. In: Informatics in Schools: Focus on Learning Programming. Paper presented at 10th International Conference on Informatics in Schools: Situation, Evolution, and Perspective (ISSEP).
Open this publication in new window or tab >>Introducing Programming and Digital Competence in Swedish K–9 Education
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2017 (English)In: Informatics in Schools: Focus on Learning Programming, 2017Conference paper, Published paper (Refereed)
National Category
Computer Sciences
Research subject
Computer Science with specialization in Computer Science Education Research
Identifiers
urn:nbn:se:uu:diva-337182 (URN)10.1007/978-3-319-71483-7_10 (DOI)
Conference
10th International Conference on Informatics in Schools: Situation, Evolution, and Perspective (ISSEP)
Funder
VINNOVA
Available from: 2017-12-21 Created: 2017-12-21 Last updated: 2018-01-13Bibliographically approved
Girons Lopez, M., Wennerström, H., Nordén, L.-Å. & Seibert, J. (2015). Location and Density of Rain Gauges for the Estimation of Spatial Varying Precipitation. Geografiska Annaler. Series A, Physical Geography, 97(1), 167-179
Open this publication in new window or tab >>Location and Density of Rain Gauges for the Estimation of Spatial Varying Precipitation
2015 (English)In: Geografiska Annaler. Series A, Physical Geography, ISSN 0435-3676, E-ISSN 1468-0459, Vol. 97, no 1, p. 167-179Article in journal (Refereed) Published
Abstract [en]

Accurate estimation of precipitation and its spatial variability is crucial for reliable discharge simulations. Although radar and satellite based techniques are becoming increasingly widespread, quantitative precipitation estimates based on point rain gauge measurement interpolation are, and will continue to be in the foreseeable future, widely used. However, the ability to infer spatially distributed data from point measurements is strongly dependent on the number, location and reliability of measurement stations.

In this study we quantitatively investigated the effect of rain gauge network configurations on the spatial interpolation by using the operational hydrometeorological sensor network in the Thur river basin in north-eastern Switzerland as a test case. Spatial precipitation based on a combination of radar and rain gauge data provided by MeteoSwiss was assumed to represent the true precipitation values against which the precipitation interpolation from the sensor network was evaluated. The performance using scenarios with both increased and decreased station density were explored. The catchment-average interpolation error indices significantly improve up to a density of 24 rain gauges per 1000 km2, beyond which improvements were negligible. However, a reduced rain gauge density in the higher parts of the catchment resulted in a noticeable decline of the performance indices. An evaluation based on precipitation intensity thresholds indicated a decreasing performance for higher precipitation intensities. The results of this study emphasise the benefits of dense and adequately distributed rain gauge networks.

Keywords
precipitation monitoring, point measurements, sensor networks, interpolation
National Category
Oceanography, Hydrology and Water Resources
Research subject
Hydrology
Identifiers
urn:nbn:se:uu:diva-244441 (URN)10.1111/geoa.12094 (DOI)000350500400011 ()
Available from: 2015-02-16 Created: 2015-02-16 Last updated: 2018-01-11Bibliographically approved
Wennerström, H., Hermans, F., Rensfelt, O., Rohner, C. & Nordén, L.-Å. (2013). A long-term study of correlations between meteorological conditions and 802.15.4 link performance. In: Proc. 10th International Conference on Sensing, Communications, and Networking: . Paper presented at SECON 2013 (pp. 221-229). IEEE Communications Society
Open this publication in new window or tab >>A long-term study of correlations between meteorological conditions and 802.15.4 link performance
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2013 (English)In: Proc. 10th International Conference on Sensing, Communications, and Networking, IEEE Communications Society, 2013, p. 221-229Conference paper, Published paper (Refereed)
Place, publisher, year, edition, pages
IEEE Communications Society, 2013
National Category
Computer Sciences Communication Systems
Identifiers
urn:nbn:se:uu:diva-200165 (URN)10.1109/SAHCN.2013.6644981 (DOI)978-1-4799-0230-9 (ISBN)
Conference
SECON 2013
Projects
CNDSWISENET
Available from: 2013-05-21 Created: 2013-05-21 Last updated: 2018-01-11Bibliographically approved
Wennerström, H., McNamara, L., Rohner, C. & Nordén, L.-Å. (2013). A Study of Packet Errors on Outdoor 802.15.4 Links. In: The 9th Swedish National Computer Networking Workshop 2013: . Paper presented at SNCNW 2013.
Open this publication in new window or tab >>A Study of Packet Errors on Outdoor 802.15.4 Links
2013 (English)In: The 9th Swedish National Computer Networking Workshop 2013, 2013Conference paper, Poster (with or without abstract) (Refereed)
National Category
Communication Systems
Identifiers
urn:nbn:se:uu:diva-201323 (URN)
Conference
SNCNW 2013
Projects
CNDSWISENET
Available from: 2013-06-10 Created: 2013-06-10 Last updated: 2018-06-05Bibliographically approved
Boano, C. A., Wennerström, H., Zúñiga, M. A., Brown, J., Keppitiyagama, C., Oppermann, F. J., . . . Römer, K. (2013). Hot Packets: A systematic evaluation of the effect of temperature on low power wireless transceivers. In: Proc. 5th Extreme Conference on Communication: . Paper presented at ExtremeCom 2013 (pp. 7-12). New York: ACM Press
Open this publication in new window or tab >>Hot Packets: A systematic evaluation of the effect of temperature on low power wireless transceivers
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2013 (English)In: Proc. 5th Extreme Conference on Communication, New York: ACM Press, 2013, p. 7-12Conference paper, Published paper (Refereed)
Abstract [en]

Temperature is known to have a significant effect on the performance of radio transceivers: the higher the temperature, the lower the quality of links. Analysing this effect is particularly important in sensor networks because several applications are exposed to harsh environmental conditions. Daily or hourly changes in temperature can dramatically reduce the throughput, increase the delay, or even lead to network partitions. A few studies have quantified the impact of temperature on low-power wireless links, but only for a limited temperature range and on a single radio transceiver. Building on top of these preliminary observations, we design a low-cost experimental infrastructure to vary the onboard temperature of sensor nodes in a repeatable fashion, and we study systematically the impact of temperature on various sensornet platforms. We show that temperature affects transmitting and receiving nodes differently, and that all platforms follow a similar trend that can be captured in a simple first-order model. This work represents an initial stepping stone aimed at predicting the performance of a network considering the particular temperature profile of a given environment.

Place, publisher, year, edition, pages
New York: ACM Press, 2013
National Category
Computer Sciences Communication Systems
Identifiers
urn:nbn:se:uu:diva-201338 (URN)978-1-4503-2171-6 (ISBN)
Conference
ExtremeCom 2013
Projects
CNDSWISENET
Available from: 2013-06-10 Created: 2013-06-10 Last updated: 2018-01-11Bibliographically approved
Hermans, F., Rensfelt, O., Voigt, T., Ngai, E., Nordén, L.-Å. & Gunningberg, P. (2013). SoNIC: Classifying interference in 802.15.4 sensor networks. In: Proc. 12th International Conference on Information Processing in Sensor Networks: . Paper presented at IPSN 2013 (pp. 55-66). New York: ACM Press
Open this publication in new window or tab >>SoNIC: Classifying interference in 802.15.4 sensor networks
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2013 (English)In: Proc. 12th International Conference on Information Processing in Sensor Networks, New York: ACM Press, 2013, p. 55-66Conference paper, Published paper (Refereed)
Place, publisher, year, edition, pages
New York: ACM Press, 2013
National Category
Computer Systems
Research subject
Computer Science with specialization in Computer Communication
Identifiers
urn:nbn:se:uu:diva-198284 (URN)10.1145/2461381.2461392 (DOI)978-1-4503-1959-1 (ISBN)
Conference
IPSN 2013
Projects
WISENETProFuN
Funder
Vinnova
Available from: 2013-04-11 Created: 2013-04-11 Last updated: 2014-09-25Bibliographically approved
Wennerström, H., McNamara, L., Rohner, C. & Nordén, L.-Å. (2013). Transmission errors in a sensor network at the edge of the world. In: Proc. 5th Extreme Conference on Communication: . Paper presented at ExtremeCom 2013. New York: ACM Press
Open this publication in new window or tab >>Transmission errors in a sensor network at the edge of the world
2013 (English)In: Proc. 5th Extreme Conference on Communication, New York: ACM Press, 2013Conference paper, Published paper (Refereed)
Abstract [en]

The performance of an outdoor wireless sensor network for remote monitoring is dictated by its ability to deliver sensed data to a sink. The often isolated location means that radio interference is typically low and with different patterns in transmission errors compared to an indoor deployment. To better understand these processes, we investigate packet errors in such a network. Specically, we study characteristics of decoding errors within 802.15.4 transmissions.

We describe the experimental deployment of an outdoor sensor network, located above the Arctic circle, where we log both successfully received and broken packets. Results indicate that a substantial amount of received packets contain errors, where the errors in each packet are typically few. We distinguish between transmission errors and payload errors, and find that transmission errors are equally probable over all positions of a packet, whereas bit errors in the payload are not. This results in some bits having a 25% higher risk of being corrupted than others.

Place, publisher, year, edition, pages
New York: ACM Press, 2013
National Category
Computer Sciences Communication Systems
Identifiers
urn:nbn:se:uu:diva-201447 (URN)978-1-4503-2171-6 (ISBN)
Conference
ExtremeCom 2013
Projects
CNDSWISENET
Available from: 2013-06-11 Created: 2013-06-11 Last updated: 2018-01-11
Hermans, F., Rensfelt, O., Larzon, L.-Å. & Gunningberg, P. (2012). A Lightweight Approach to Online Detection and Classification of Interference in 802.15.4-based Sensor Networks. Paper presented at 3rd International Workshop on Networks of Cooperating Objects (CONET 2012). ACM SIGBED Review, 9(3), 11-20
Open this publication in new window or tab >>A Lightweight Approach to Online Detection and Classification of Interference in 802.15.4-based Sensor Networks
2012 (English)In: ACM SIGBED Review, ISSN 1551-3688, Vol. 9, no 3, p. 11-20Article in journal (Refereed) Published
Abstract [en]

With a rapidly increasing number of devices sharing access to the 2.4 GHz ISM band, interference becomes a serious problem for 802.15.4-based, low-power sensor networks. Consequently, interference mitigation strategies are becoming commonplace. In this paper, we consider the step that precedes interference mitigation: interference detection. We have performed extensive measurements to characterize how different types of interferers affect individual 802.15.4 packets. From these measurements, we define a set of features which we use to train a neural network to classify the source of interference of a corrupted packet. Our approach is sufficiently lightweight for online use in a resource constrained sensor network. It does not require additional hardware, nor does it use active spectrum sensing or probing packets. Instead, all information about interferers is gathered from inspecting corrupted packets that are received during the sensor network’s regular operation. Even without considering a history of earlier packets, our approach reaches a mean classification accuracy of 79.8%, with per interferer accuracies of64.9% for WiFi, 82.6% for Bluetooth, 72.1% for microwave ovens, and 99.6% for packets that are corrupted due to insufficient signal strength.

National Category
Computer Engineering Communication Systems
Identifiers
urn:nbn:se:uu:diva-179803 (URN)10.1145/2367580.2367582 (DOI)
Conference
3rd International Workshop on Networks of Cooperating Objects (CONET 2012)
Projects
WISENET
Available from: 2012-08-23 Created: 2012-08-23 Last updated: 2018-01-12Bibliographically approved
Wennerström, H., Hermans, F., Rensfelt, O., Rohner, C. & Nordén, L.-Å. (2012). A Long-Term Study on the Effects of Meteorological Conditions on 802.15.4 Links. In: 8th Swedish National Computer Networking Workshop, Stockholm, June 7-8. Paper presented at SNCNW 2012.
Open this publication in new window or tab >>A Long-Term Study on the Effects of Meteorological Conditions on 802.15.4 Links
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2012 (English)In: 8th Swedish National Computer Networking Workshop, Stockholm, June 7-8, 2012Conference paper, Published paper (Refereed)
Abstract [en]

Remote monitoring of natural phenomena using wireless sensor networks requires these networks to successfully operate while being exposed to the surrounding environment. Weather conditions are an essential aspect of the environment, therefore it is important to understand the effects of weather on sensor networks. This understanding is especially important since weather varies strongly over time and affects the communication between sensor nodes. In our ongoing work we study how different meteorological conditions influence radio links in outdoor wireless sensor networks that use IEEE 802.15.4 for communication. We deploy an experimental setup next to a meteorological research station and aim to run experiments over several months in order to capture both short- and long-term changes in the link characteristics. We show some initial measurements of the deployment, highlighting influences on packet reception rate and signal strength.

National Category
Communication Systems
Research subject
Computer Science with specialization in Computer Communication
Identifiers
urn:nbn:se:uu:diva-184624 (URN)
Conference
SNCNW 2012
Projects
CNDSWISENET
Available from: 2012-11-12 Created: 2012-11-12 Last updated: 2018-06-05
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