| 51. |
- Bosk, Daniel, et al.
(författare)
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Towards Perfectly Secure and Deniable Communication Using an NFC-Based Key-Exchange Scheme
- 2015
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Ingår i: Secure IT Systems. - Cham : Springer. ; , s. 72-87, s. 72-87
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Konferensbidrag (refereegranskat)abstract
- In this paper we first analyse the possibility for deniability under a strong adversary, who has an Internet-wide transcript of the communication. Secondly, we present a scheme which provides the desirable properties of previous messaging schemes, but with stronger deniability under the new adversary model. Our scheme requires physical meetings for exchanges of large amounts of random key-material via near-field communication and later uses this random data to key a one-time pad for text-messaging. We prove the correctness of the protocol and, finally, we evaluate the practical feasibility of the suggested scheme.
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| 52. |
- Brouwers, Lisa, 1967-, et al.
(författare)
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Multi-criteria decision-making of policy strategies with public-private re-insurance systems
- 2004
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Ingår i: Risk, Decision, and Policy. - : Informa UK Limited. - 1357-5309 .- 1466-4534. ; 9:1, s. 23-45
-
Tidskriftsartikel (refereegranskat)abstract
- This article describes an integrated flood catastrophe model as well as some results of a case study made in the Upper Tisza region in north-eastern Hungary: the Palad-Csecsei basin. The background data was provided through the Hungarian Academy of Sciences and complemented by interviews with different stakeholders in the region. Based on these data, for which a large degree of uncertainty is prevailing, we demonstrate how an implementation of a simulation and decision analytical model can provide insights into the effects of imposing different policy options for a flood risk management program in the region. We focus herein primarily on general options for designing a public-private insurance and reinsurance system for Hungary. Obviously, this is a multi-criteria and multi-stakeholder problem and cannot be solved using standard approaches. It should, however, be emphasised that the main purpose of this article is not to provide any definite recommendations, but rather to explore a set of policy packages that could gain a consensus among the stakeholders.
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| 53. |
- Brunnström, Kjell, 1960-, et al.
(författare)
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Latency impact on Quality of Experience in a virtual reality simulator for remote control of machines
- 2020
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Ingår i: Signal processing. Image communication. - : Elsevier. - 0923-5965 .- 1879-2677. ; 89
-
Tidskriftsartikel (refereegranskat)abstract
- In this article, we have investigated a VR simulator of a forestry crane used for loading logs onto a truck. We have mainly studied the Quality of Experience (QoE) aspects that may be relevant for task completion, and whether there are any discomfort related symptoms experienced during the task execution. QoE experiments were designed to capture the general subjective experience of using the simulator, and to study task performance. The focus was to study the effects of latency on the subjective experience, with regards to delays in the crane control interface. Subjective studies were performed with controlled delays added to the display update and hand controller (joystick) signals. The added delays ranged from 0 to 30 ms for the display update, and from 0 to 800 ms for the hand controller. We found a strong effect on latency in the display update and a significant negative effect for 800 ms added delay on latency in the hand controller (in total approx. 880 ms latency including the system delay). The Simulator Sickness Questionnaire (SSQ) gave significantly higher scores after the experiment compared to before the experiment, but a majority of the participants reported experiencing only minor symptoms. Some test subjects ceased the test before finishing due to their symptoms, particularly due to the added latency in the display update.
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| 54. |
- Brunnström, Kjell, 1960-, et al.
(författare)
-
Quality measurement methods for video assisting refereeing systems
- 2023
-
Ingår i: Sports Engineering. - : Springer Science and Business Media Deutschland GmbH. - 1369-7072 .- 1460-2687. ; 26:1
-
Tidskriftsartikel (refereegranskat)abstract
- Changes in the footballing world’s approach to technology and innovation, along with major advancements in broadcasting contributed to the decision by the International Football Association Board to introduce Video Assistant Referees in 2018. The change meant that under strict protocols referees could use video replays to review decisions in the event of a “clear and obvious error” or a “serious missed incident”. At the time of writing 48-Member Associations have introduced the Video Assistant Referees protocol in at least one of their tournaments and there are many technology providers who work with organisers to implement the Video Assistant Referees systems. To ensure that the use of Video Assistant Referees has a positive effect on the game, Fédération Internationale de Football Association collaborated with the RISE Research Institutes of Sweden to develop objective test methods that could be used to ensure that a system can provide an adequate solution. Each provider must be able to pass requirements that ensure that they can deal with the challenges of processing, coding, decoding, synchronising, and re-formatting of the broadcast feeds. This article will describe the development of the test methods and illustrate some initial results from a test event on Video Assistant Referees system candidates. The methods have shown to be robust and appropriate for their intended purpose and will be developed over the years to ensure the quality of Video Assistant Referees. The developed measurement methods are general and can be applied to other broadcast and video systems as well as to other sports. © 2023, The Author(s).
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| 55. |
- Brunnström, Kjell, 1960-, et al.
(författare)
-
Quality of experience of hand controller latency in a virtual reality simulator
- 2019
-
Ingår i: IS and T International Symposium on Electronic Imaging Science and Technology. - Springfield, VA, United States : Society for Imaging Science and Technology.
-
Konferensbidrag (refereegranskat)abstract
- In this study, we investigate a VR simulator of a forestry crane used for loading logs onto a truck, mainly looking at Quality of Experience (QoE) aspects that may be relevant for task completion, but also whether there are any discomfort related symptoms experienced during task execution. A QoE test has been designed to capture both the general subjective experience of using the simulator and to study task performance. Moreover, a specific focus has been to study the effects of latency on the subjective experience, with regards to delays in the crane control interface. A formal subjective study has been performed where we have added controlled delays to the hand controller (joystick) signals. The added delays ranged from 0 ms to 800 ms. We found no significant effects of delays on the task performance on any scales up to 200 ms. A significant negative effect was found for 800 ms added delay. The Symptoms reported in the Simulator Sickness Questionnaire (SSQ) was significantly higher for all the symptom groups, but a majority of the participants reported only slight symptoms. Two out of thirty test persons stopped the test before finishing due to their symptoms.
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| 56. |
- Brunnström, Kjell, et al.
(författare)
-
Scale and Resolution in Active Analysis of Local Image Structure
- 1990
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Ingår i: Image and Vision Computing. - : Elsevier. ; 8:4, s. 289-296
-
Tidskriftsartikel (refereegranskat)abstract
- Focus-of-attention is extremely important in human visual perception. If computer vision systems are to perform tasks in a complex, dynamic world they will have to be able to control processing in a way that is analogous to visual attention in humans. Problems connected to foveation (examination of selected regions of the world at high resolution) are examined. In particular, the problem of finding and classifying junctions from this aspect is considered. It is shown that foveation as simulated by controlled, active zooming in conjunction with scale-space techniques allows for robust detection and classification of junctions.
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| 57. |
- Brunnström, Kjell, 1960-, et al.
(författare)
-
Video quality of video professionals for Video Assisted Referee (VAR)
- 2023
-
Ingår i: IS and T International Symposium on Electronic Imaging Science and Technology. - : Society for Imaging Science and Technology. - 2470-1173. ; 35:10
-
Tidskriftsartikel (refereegranskat)abstract
- Changes in the footballing world’s approach to technology and innovation contributed to the decision by the International Football Association Board to introduce Video Assistant Referees (VAR). The change meant that under strict protocols referees could use video replays to review decisions in the event of a "clear and obvious error" or a "serious missed incident". This led to the need by Fédération Internationale de Football Association (FIFA) to develop methods for quality control of the VAR-systems, which was done in collaboration with RISE Research Institutes of Sweden AB. One of the important aspects is the video quality. The novelty of this study is that it has performed a user study specifically targeting video experts i.e., to measure the perceived quality of video professionals working with video production as their main occupation. An experiment was performed involving 25 video experts. In addition, six video quality models have been benchmarked against the user data and evaluated to show which of the models could provide the best predictions of perceived quality for this application. Video Quality Metric for variable frame delay (VQM_VFD) had the best performance for both formats, followed by Video Multimethod Assessment Fusion (VMAF) and VQM General model.
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| 58. |
- Busson, P., et al.
(författare)
-
Ferroelectric liquid crystalline dendrimers : Synthesis, thermal behavior, and electrooptical characterization
- 2001
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Ingår i: Macromolecules. - : American Chemical Society (ACS). - 0024-9297 .- 1520-5835. ; 34:5, s. 1221-1229
-
Tidskriftsartikel (refereegranskat)abstract
- The preparation and characterization of a series of novel ferroelectric liquid crystalline dendrimers are presented. End-capping of 1-, 2-, and 3-generation dendrimers based on 2,2-bis(hydroxymethyl)propionic acid with mesogens gave surface-functionalized liquid crystalline compounds with 6, 12, and 24 mesogen-containing units, respectively. 4 -((R)-1-Methylheptyloxy)phenyl 4-(4 '-[10(hydroxycarbonyl)decyloxyl phenyl)benzoate was synthesized and used as a mesogen-containing unit. The purity and structure of each compound were determined by H-1 NMR spectroscopy, size exclusion chromatography, and elemental analysis. Differential scanning calorimetry and optical microscopy were used to investigate the mesomorphic properties of the mesogen-functionalized dendrimers. The materials displayed a variety of mesophases, including the smectic C* phase. All the liquid crystalline dendrimers showed ferroelectricity, and tilt angle and spontaneous polarization measurements were performed. The obtained results show that the ferroelectric properties of the materials are independent of the generation number of the dendritic scaffold.
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| 59. |
- Busson, P., et al.
(författare)
-
Preparation of mesogen-functionalized dendrimers for second-order nonlinear optics
- 2002
-
Ingår i: Macromolecules. - : American Chemical Society (ACS). - 0024-9297 .- 1520-5835. ; 35:5, s. 1663-1671
-
Tidskriftsartikel (refereegranskat)abstract
- Liquid crystalline dendrimers with peripheral mesogen-containing units have been prepared. Multistep synthesis with several selective reactions was used in the preparation of the mesogen-containing molecules, 4-[10-(hydroxycarbonyl)decyloxy]phenyl 4-[4'-(2-(R)-octyloxy)-3'-nitrophenyl]benzo ate and 4-[10-(hydroxycarbonyl)decyloxy]biphenyl 4-[4'-(2-(R)-octyloxy)-3'-nitrophenyl]benzoate. Both molecules possessed an electron-accepting nitro group placed perpendicular to the long axis of the molecules in order to enhance the nonlinear optical activity. A second generation hydroxyl functional aliphatic dendrimer based on the dihydroxy acid, 2,2-bis(hydroxymethyl)propionic acid, was used as dendritic scaffold and was subsequently functionalized with the aforementioned groups. The purity and structure of the two liquid crystalline dendrimers were determined by H-1 NMR spectroscopy, size exclusion chromatography, and elemental analysis. The synthesis of both the mesogen-containing units and the liquid crystalline dendrimers is described in detail. Investigation of the liquid crystalline properties of the materials by differential scanning calorimetry and optical microscopy showed that they exhibited different mesophases, including the chiral smectic C phase. Ferroelectric switching was observed in this tilted phase, and electrooptical properties, including tilt angle and spontaneous polarization measurements, were investigated. Finally, the nonlinear optical properties of one of the materials were preliminary characterized.
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| 60. |
- Bäckström, Marie, et al.
(författare)
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Beatability and runnability studies of ion-exchanged unbleached kraft pulps on a pilot scale
- 2009
-
Ingår i: Nordic Pulp & Paper Research Journal. - : Walter de Gruyter GmbH. - 0283-2631 .- 2000-0669. ; 24:1, s. 94-100
-
Tidskriftsartikel (refereegranskat)abstract
- It has earlier been shown that the counter-ion to the charged groups in the fibre has a significant effect on the beatability of fibres, but large-scale investigations of this effect are scarce in the literature. The objectives of the present study were therefore to develop a technique to ion-exchange large quantities of industrial pulp into the Na +-form using complexing agents and to study the effect of industrial-scale refining on pulp fibres in the Na +-form and how the fibres respond to industrial-like papermaking. The results show that ion-exchange can indeed be conducted on a pilot-scale using complexing agents such as DTPA. The study further indicates that an energy reduction of 50% at a given WRV or tensile index may be achieved if the fibres are converted to Na +-form prior to pilot-scale refining. By applying these techniques in full-scale production, it should thus be possible to save significant amount of energy, especially in the case of papers made from unbleached pulp that usually demands a higher degree of beating to achieve sufficient strength.
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