| 1. |
- Johansson, Magnus, 1970-, et al.
(författare)
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Internalisering av godstrafikens externa effekter – konsekvensanalyser med Samgodsmodellen : en delrapport inom SAMKOST 3
- 2018
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Rapport (övrigt vetenskapligt/konstnärligt)abstract
- Regeringen har gett VTI i uppdrag att förbättra kunskapen om transportsektorns samhällsekonomiska kostnader. I en särskild del av detta uppdrag ingår att analysera konsekvenser av en full internalisering av godstrafikens externa effekter.Syftet med denna rapport är att ge en bild av hur transportarbetet med olika trafikslag kan komma att påverkas om skatter och avgifter höjs till en nivå som motsvarar kostnaden för de externa effekter som trafiken ger upphov till. Rapporten innehåller dels en beräkning av hur mycket skatter och avgifter bör höjas för olika fordonsvarianter, dels en modellanalys av hur påföljande kostnadsökningar påverkar transportarbetet på väg, järnväg och sjö. Modellberäkningarna har utförts med Trafikverkets nationella godstransportmodell Samgods.Resultaten visar bland annat att sjöfarten skulle gynnas av den relativprisförändring som skatte- och avgiftshöjningarna ger upphov till. Järnvägstrafiken påverkas kraftigt negativt eftersom en marginalkostnadsprissättning skulle kräva kraftigt höjda banavgifter. En internalisering beräknas ge en positiv klimateffekt, men effekterna är relativt små.
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| 2. |
- Gottsäter, Erik, et al.
(författare)
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Crack widths in base restrained walls subjected to restraint loading
- 2019
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Ingår i: Engineering Structures. - : Elsevier BV. - 1873-7323 .- 0141-0296. ; 189, s. 272-285
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Tidskriftsartikel (refereegranskat)abstract
- Cracks in concrete structures can have a negative impact on durability and aesthetic appearance. It is therefore important to estimate crack widths before construction, and to use suitable reinforcement amounts to limit crack widths. Crack widths are however hard to predict in restrained structures, as cracking reduces the stiffness, which in turn reduces the restraint and thereby the amount of cracking. In this paper, nonlinear finite element analyses of cracking are performed on base restrained walls mainly subjected to shrinkage. A non-linear material model for concrete and a bond-slip relation for concrete – reinforcement interaction are used. The model does not include the hardening process of concrete but instead applies the load effects on mature concrete, and is validated by comparisons with test results from full scale tests performed in previous research. Additionally, a sensitivity study is made to investigate the influence of certain parameters on crack widths and crack patterns. The intention is to use the model in the development of a model to be used in design of concrete structures which takes restraint effects into account in an improved, yet a simplified way. The results show that the model gives realistic crack patterns, but that it tends to overestimate crack widths and the number of cracks obtained. Therefore, the model is considered to be acceptable.
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| 3. |
- Nasr, Amro, et al.
(författare)
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Quantitative assessment of the impact of climate change on creep of concrete structures
- 2021
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Ingår i: Proceedings of the 31st European Safety and Reliability Conference (ESREL 2021). - Singapore : Research Publishing Services. - 9789811820168 ; , s. 1318-1325
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Konferensbidrag (refereegranskat)abstract
- Creep of concrete structures is in most cases regarded as a serviceability problem that may have impacts on maintenance and repair costs but cannot lead to structural collapse. However, several structural collapses during the past decades have been, at least partly, attributed to excessive creep deformations. Recent studies suggest that concrete creep may be further exacerbated by climate change. The current study demonstrates how this effect can be quantitatively assessed. For this purpose, six different creep models (i.e, Model Code 1999, Model Code 2010, MPF, B3, B4, and B4s models) are used under considerations of historical and future climatic conditions in southernmost Sweden as given by a regional climate model. Furthermore, two different simulations were performed as follows: 1) considering only climate uncertainty represented by the climate model, and 2) considering climate uncertainty, parameter uncertainty, and creep model uncertainty. The highest impact of climate change on end of century creep coefficient is observed using model B4 where the 75th percentile of the increase in creep coefficient is found to range from 8% to ∼14% depending on the climate scenario. The results of the assessment in this article show that the uncertainty related to climate change on creep of concrete structures (higher effect in RCP8.5 than in RCP2.6 and RCP4.5 which have very similar results) is much smaller than uncertainties resulting from creep modelling.
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| 4. |
- Johansson, Glenn, 1990, et al.
(författare)
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Removal and release of microplastics and other environmental pollutants during the start-up of bioretention filters treating stormwater
- 2024
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Ingår i: Journal of Hazardous Materials. - : Elsevier. - 0304-3894 .- 1873-3336. ; 468
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Tidskriftsartikel (refereegranskat)abstract
- Untreated stormwater is a major source of microplastics, organic pollutants, metals, and nutrients in urban water courses. The aim of this study was to improve the knowledge about the start-up periods of bioretention filters. A rain garden pilot facility with 13 bioretention filters was constructed and stormwater from a highway and adjacent impervious surfaces was used for irrigation for ∼12 weeks. Selected plants (Armeria maritima, Hippophae rhamnoides, Juncus effusus, and Festuca rubra) was planted in ten filters. Stormwater percolated through the filters containing waste-to-energy bottom ash, biochar, or Sphagnum peat, mixed with sandy loam. Influent and effluent samples were taken to evaluate removal of the above-mentioned pollutants.
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| 5. |
- Linderoth, Oskar, et al.
(författare)
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Fuktegenskaper hos cementbundet material med flygaskainblandning
- 2019
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Ingår i: Bygg & teknik. - 0281-658X. ; 111:7, s. 8-11
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Tidskriftsartikel (populärvet., debatt m.m.)abstract
- Med cementbundna materials fuktegenskaper menas hur de binder och transporterar vatten. Känner man fuktegenskaper kan man räkna ut hur exempelvis en betong torkar. Mätning av fuktegenskaper för cementbundna material är något Avd. Byggnadsmaterial i Lund har stor erfarenhet av, särskilt för material med Portlandcement som bindemedel [1] [2]. På senare år har forskning vid avdelningen också visat hur fuktegenskaperna förändras när delar av Portlandcementet ersätts med slagg eller silika [3] [4]. Denna artikel är en kortfattad sammanfattning av resultaten från ett pågående doktorandprojekt inom vilket fuktegenskaperna undersöks för cementbundet material där delar av Portlandcementet ersatts med flygaska. Projektet kommer redovisas i sin helhet nästa år.
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| 6. |
- Stylianopoulos, Charalampos, 1991, et al.
(författare)
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CLort: High Throughput and Low Energy Network Intrusion Detection on IoT Devices with Embedded GPUs
- 2018
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Ingår i: Lecture Notes in Computer Science (including subseries Lecture Notes in Artificial Intelligence and Lecture Notes in Bioinformatics). - Cham : Springer International Publishing. - 1611-3349 .- 0302-9743. ; 11252 LNCS, s. 187-202
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Konferensbidrag (refereegranskat)abstract
- While IoT is becoming widespread, cyber security of its devices is still a limiting factor where recent attacks (e.g., the Mirai bot-net) underline the need for countermeasures. One commonly-used security mechanism is a Network Intrusion Detection System (NIDS), but the processing need of NIDS has been a significant bottleneck for large dedicated machines, and a show-stopper for resource-constrained IoT devices. However, the topologies of IoT are evolving, adding intermediate nodes between the weak devices on the edges and the powerful cloud in the center. Also, the hardware of the devices is maturing, with new CPU instruction sets, caches as well as co-processors. As an example, modern single board computers, such as the Odroid XU4, come with integrated Graphics Processing Units (GPUs) that support general purpose computing. Even though using all available hardware efficiently is still an open issue, it has the promise to run NIDS more efficiently. In this work we introduce CLort, an extension to the well-known NIDS Snort that a) is designed for IoT devices b) alleviates the burden of pattern matching for intrusion detection by offloading it to the GPU. We thoroughly explain how our design is used as part of the latest release of Snort and suggest various optimizations to enable processing on the GPU. We evaluate CLort in regards to throughput, packet drops in Snort, and power consumption using publicly available traffic traces. CLort achieves up to 52% faster processing throughput than its CPU counterpart. CLort can also analyze up to 12% more packets than its CPU counterpart when sniffing a network. Finally, the experimental evaluation shows that CLort consumes up to 32% less energy than the CPU counterpart, an important consideration for IoT devices.
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| 7. |
- Zetterström, Oskar, et al.
(författare)
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V-Band Geodesic Generalized Luneburg Lens Antenna with High Beam Crossover Gain
- 2023
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Ingår i: IEEE Transactions on Antennas and Propagation. - : Institute of Electrical and Electronics Engineers (IEEE). - 0018-926X .- 1558-2221. ; 71:9, s. 7591-7596
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Tidskriftsartikel (refereegranskat)abstract
- Quasi-optical beamformers provide attractive properties for antenna applications at millimeter-wave (mm-wave) frequencies. Antennas implemented with these beamformers have demonstrated wide-angle switching of directive beams, making them suitable as base station antennas for future communication networks. For these applications, it is essential to ensure a high beam crossover gain to provide a robust service to end users within the steering range. Here, we propose a geodesic generalized Luneburg lens antenna operating from 57 to 67 GHz that provides increased crossover gain compared to previously reported geodesic Luneburg lens antennas. The focal curve of the generalized Luneburg lens can be displaced from the beamformer, allowing for a higher angular resolution in the placement of the feed array along the focal curve. The lens is fed with 21 ridge waveguides with an angular separation of 5.1°, thus providing beam steering in a 102° range. The peak realized gain varies from 19 to 21 dBi throughout the steering and frequency ranges and the beam crossover gain is roughly 3 dB below the peak gain. The simulations are experimentally validated.
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| 8. |
- Jalo, Hoor, 1994, et al.
(författare)
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Early Characterization of Stroke Using Video Analysis and Machine Learning
- 2023
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Ingår i: Emerging Technologies in Healthcare and Medicine. - 9781958651926 ; 116:2023, s. 74-84
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Konferensbidrag (refereegranskat)abstract
- Stroke is one of the leading causes of death and disability worldwide and requires an immediate attention as the longer the patient is left untreated, the more sever its outcomes are. Enhancing access to optimal treatment and reducing mortality rates require improving the accuracy of stroke characterization methods in prehospital settings. This study explores how video analysis and machine learning (ML) can be leveraged to identify stroke symptoms on the National Institute of Health Stroke Scale (NIHSS), with the goal of facilitating the prehospital management of patients with suspected stroke. A total of 888 videos were captured from the research group members, who mimicked stroke symptoms including facial palsy, leg and arm paresis, ataxia and dysarthria, following the criteria of the NIHSS. Multiple algorithms, utilized in earlier studies, were examined to predict these symptoms, and their performance was assessed using accuracy, sensitivity and specificity. The best method for detecting facial palsy was found using Histogram of Oriented Gradients (HOG) features in conjunction with Adaptive Boosting (AdaBoost), achieving an accuracy, sensitivity and specificity values of 97.8%, 98.0% and 97.0%, respectively. The identification of arm paresis reached 100% on all metrics using a combination of MediaPipe and SVM. For leg paresis, all algorithms had poor detection rates. The outcome for ataxia for both limbs varied. Google Cloud Speech-to-Text was used to detect dysarthria and reached 100% on all evaluation metrics. These findings suggest that video analysis and ML have the potential to assist early stroke diagnosis, but further research is needed to validate this.
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| 9. |
- Nasr, Amro, et al.
(författare)
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Climate change impact on safety and performance of existing and future bridges
- 2018
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Ingår i: Proceedings of the Sixth International Symposium on Life-Cycle Civil Engineering (IALCCE 2018). ; , s. 1735-1741, s. 1735-1741
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Konferensbidrag (refereegranskat)abstract
- Recent decades have seen an increased attention towards the threat of climate change to our built environment and not least our infrastructure. Accounting for the different ways in which potential climate change scenarios can affect our infrastructure is paramount in determining appropriate adaptation and risk management strategies. This paper presents the initial findings of a new research project which is concerned with establishing an improved management of the risks to our infrastructure, especially bridges, in light of a changing climate. In this paper, a preliminary survey of the climate change related risks on bridges is conducted. Timely consideration of these impacts is of utmost importance to ensure a satisfactory performance of our bridges in the future. The interplay between the different risks and how the occurrence of one risk may influence other risks is also briefly discussed. The future stages of the project are mentioned as well. The authors would like to acknowledge the support of the Swedish Transport Administration. Any opinions, findings, or conclusions in this work are those of the authors and are not necessarily in accordance with those of the Swedish Transport Administration.
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| 10. |
- Algaba-Brazalez, A., et al.
(författare)
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Compact Polarization Transformation in a Geodesic Luneburg Lens Antenna
- 2021
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Ingår i: 2021 IEEE International Symposium on Antennas and Propagation and North American Radio Science Meeting, APS/URSI 2021 - Proceedings. - : Institute of Electrical and Electronics Engineers Inc.. ; , s. 1992-1993
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Konferensbidrag (refereegranskat)abstract
- This paper describes the design of a compact polarizer that rotates the linear polarization of a fully metallic geodesic Luneburg lens antenna for applications requiring polarization diversity. The polarization rotation is achieved by loading the radiating aperture of the antenna with two metallic screens. The integrated antenna operates in the Ka-band, from 25 to 31 GHz, showing around 20% bandwidth with S11 below -10 dB, and a scanning range of 100°.
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