| 1. |
- Andersson, Emma V., 1983-, et al.
(författare)
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Quantifying railway timetable robustness in critical points
- 2013
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Ingår i: Journal of Rail Transport Planning and Management. - : Elsevier. - 2210-9706 .- 2210-9714. ; 3:3, s. 95-110
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Tidskriftsartikel (refereegranskat)abstract
- Several European railway traffic networks experience high capacity consumption during large parts of the day resulting in delay-sensitive traffic system with insufficient robustness. One fundamental challenge is therefore to assess the robustness and find strategies to decrease the sensitivity to disruptions. Accurate robustness measures are needed to determine if a timetable is sufficiently robust and suggest where improvements should be made.Existing robustness measures are useful when comparing different timetables with respect to robustness. They are, however, not as useful for suggesting precisely where and how robustness should be increased. In this paper, we propose a new robustness measure that incorporates the concept of critical points. This concept can be used in the practical timetabling process to find weaknesses in a timetable and to provide suggestions for improvements. In order to quantitatively assess how crucial a critical point may be, we have defined the measure robustness in critical points (RCP). In this paper, we present results from an experimental study where a benchmark of several measures as well as RCP has been done. The results demonstrate the relevance of the concept of critical points and RCP, and how it contributes to the set of already defined robustness measures
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| 2. |
- Björklund, Svante, et al.
(författare)
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On distinguishing between human individuals in micro-Doppler signatures
- 2013
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Ingår i: 14th International Radar Symposium (IRS). - : Institute of Electrical and Electronics Engineers (IEEE). - 9781467348218 ; , s. 865-870
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Konferensbidrag (refereegranskat)abstract
- Radar micro-Doppler signatures (MDS) of humans are created by movements of body parts, such as legs and arms. MDSs can be used in security applications to detect humans and classify their type and activity. Target association and tracking, which can facilitate the classification, become easier if it is possible to distinguish between human individuals by their MDSs. By this we mean to recognize the same individual in a short time frame but not to establish the identity of the individual. In this paper we perform a statistical experiment in which six test persons are able to distinguish between walking human individuals from their MDSs. From this we conclude that there is information in the MDSs of the humans to distinguish between different individuals, which also can be used by a machine. Based on the results of the best test persons we also discuss features in the MDSs that could be utilized to make this processing possible.
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| 3. |
- Duong, Quang Trung, et al.
(författare)
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Distributed Space-Time Coding in Two-Way Fixed Gain Relay Networks over Nakagami-m Fading
- 2012
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Ingår i: Proceedings of the IEEE International Conference on Communicatons (ICC). - Ottawa : IEEE. - 9781457720512 - 9781457720529 ; , s. 3521-3525
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Konferensbidrag (refereegranskat)abstract
- The distributed Alamouti space-time code in two-way fixed gain amplify-and-forward (AF) relay is proposed in this paper. In particular, closed-form expressions for approximated ergodic sum-rate and exact pairwise error probability (PWEP) are derived for Nakagami-m fading channels. To reveal further insights into array and diversity gains, an asymptotic PWEP is also obtained. Finally, numerical results are provided to corroborate the proposed theoretical analysis.
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| 4. |
- Hjelm, Olof, 1967-, et al.
(författare)
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From Tool Technique to Tool Practice : Experiences from the Project Seamless : Strategic Environmental Assessment and Management in Local Authorities in Sweden
- 2011
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Rapport (övrigt vetenskapligt/konstnärligt)abstract
- This report contains the results from the project SEAMLESS, Strategic Environmental Assessment and Management in Local authoritiES in Sweden. The aim of SEAMLESS was to explore conceptual foundations as well as feasibility of establishing better operational and methodological linkages between tools for strategic environmental planning, assessment and management, especially between SEA (according to the EG directive 2001/42/EC and EMS based on the main principles of ISO 14001/EMAS) in local authorities. The rationale for the study was that local authorities are important actors on the environmental arena, which make and implement a large number of decisions directly and indirectly affecting the environment. A multitude of different systems and tools have been developed to support environmental management at local authorities and an integrated use of different tools can have various benefits. The SEAMLESS project has been realized through five main steps. First, a literature review and a survey of international practice were performed. Second, in parallel to the first step, an initial conceptual framework was constructed. The third step in the research process was to carry out case studies in six selected Swedish local authorities in order get a better understanding of how SEA and EMS are dealt with in practice. In the fourth step, the results from the previous steps in the research process were compiled and analyzed in order to develop and conduct a pilot study. Finally in the fifth step, general recommendations for integrated use of strategic planning, assessment and management tools were formulated. Theoretically, local sustainable development strategies could benefit from having influence from some of the main approaches and principles in SEA and EMS methodologies. Achieving this in practice, however, is a challenge that requires a wide systems perspective and a certain degree of maturity in the organization. At the time of SEAMLESS an integrated approach of SEA and EMS was not possible nor asked for by the studied local authorities. The SEAMLESS project‘s core concepts tool technique and tool practice were used for explaining and analyzing the preconditions, possibilities and difficulties in integrating SEA and EMS. Tool technique addresses the more technical aspects of the tools use and integration, neglecting the context in which it is to be used. Applying a tool technique perspective there are several possible linkages between the studied tools that could enhance each tool, e.g. widening the scope of EMS and facilitating follow up of SEA. It is important to understand the context, since it influences the feasibility of tool integration; therefore a tool practice perspective is needed. Furthermore tool integration is another important concept in the SEAMLESS project, where three different stages of integration were identified: formal integration, learning integration and interactive integration. A too strong focus on formal integration (which is closely connected to tool technique) might lead to that potential linkages are not realized. To make such integration possible the focus should be more on learning integration. Interactive integration is hard to achieve and it can be questioned if it is desired. Too much focus on interactive integration might lead to complex resource demanding tool causing ineffectiveness and tool fatigue. The SEAMLESS project resulted in a set of recommendations based on that integration should not be seen as a goal in itself; that attempts of tool integration should focus on bridging the different professional cultures; and that a wide systems perspective is needed.
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| 5. |
- Ngo, Hien Quoc, et al.
(författare)
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Uplink Performance Analysis of Multicell MU-MIMO with Zero-Forcing Receivers and Perfect CSI
- 2011
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Ingår i: Proceedings of the IEEE Swedish Communication Technologies Workshop (Swe-CTW). - Stockholm : IEEE. - 9781457718762 - 9781457718779 ; , s. 40-45
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Konferensbidrag (refereegranskat)abstract
- We consider the uplink of a multicell multiuser MIMO system. The data detection is done by using the zero-forcing (ZF) technique, assuming the base station has perfect channel state information. We derive an exact closed-form expression for the uplink rate per user. We further study the asymptotic performance of the system. We show that, at high signal-to-noise ratio, the system is interference-limited and hence, we cannot improve the system performance by increasing the transmit power at each user. Instead, by increasing the number of base station antennas, the effects of interference and noise can be reduced, thereby improving the system performance. In particular, we show that, with very large antenna arrays at the base station, the transmit power of each user can be made inversely proportional to the number of base station antennas while maintaining a desired quality-of-service. Numerical results verify our analysis.
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| 6. |
- Ngo, Hien Quoc, et al.
(författare)
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Uplink Performance Analysis of Multicell MU-SIMO Systems with ZF Receivers
- 2013
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Ingår i: IEEE Transactions on Vehicular Technology. - : IEEE. - 0018-9545 .- 1939-9359.
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Tidskriftsartikel (refereegranskat)abstract
- We consider the uplink of a multicell multiuser single-input multiple-output system where the channel experiences both small and large-scale fading. The data detection is done by using the linear zero-forcing technique, assuming the base station (BS) has perfect channel state information of all users in its cell. We derive new, exact analytical expressions for the uplink rate, symbol error rate, and outage probability per user, as well as alower bound on the achievable rate. This bound is very tight and becomes exact in the large-number-of-antennas limit. We further study the asymptotic system performance in the regimes of high signal-to-noise ratio (SNR), large number of antennas, and large number of users per cell. We show that at high SNRs, the system is interference-limited and hence, we cannot improve the system performance by increasing the transmit power of each user. Instead, by increasing the number of BS antennas, the effects of interference and noise can be reduced, thereby improving the system performance. We demonstrate that, with very large antenna arrays at the BS, the transmit power of each user can be made inversely proportional to the number of BS antennas while maintaining a desired quality-of-service. Numerical results are presented to verify our analysis.
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| 7. |
- Suraweera, Himal, et al.
(författare)
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Multi-pair amplify-and-forward relaying with very large antenna arrays
- 2013
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Ingår i: Proceedings of the IEEE International Conference on Communicatons (ICC). - Budapest : IEEE. - 9781467331227 ; , s. 4635-4640
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Konferensbidrag (refereegranskat)abstract
- We consider a multi-pair relay channel where multiple sources simultaneously communicate with destinations using a relay. Each source or destination has only a single antenna, while the relay is equipped with a very large antenna array. We investigate the power efficiency of this system when maximum ratio combining/maximal ratio transmission (MRC/MRT) or zero-forcing (ZF) processing is used at the relay. Using a very large array, the transmit power of each source or relay (or both) can be made inversely proportional to the number of relay antennas while maintaining a given quality-of-service. At the same time, the achievable sum rate can be increased by a factor of the number of source-destination pairs. We show that when the number of antennas grows to infinity, the asymptotic achievable rates of MRC/MRT and ZF are the same if we scale the power at the sources. Depending on the large scale fading effect, MRC/MRT can outperform ZF or vice versa if we scale the power at the relay.
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| 8. |
- Svensson, Martin, et al.
(författare)
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@ the emotional edge : When enough is enough in e-mail communication
- 2013
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Ingår i: Individual sources, dynamics, and expressions of emotion. - : Emerald Group Publishing Limited. - 9781781908884 ; , s. 309-342
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Konferensbidrag (refereegranskat)abstract
- Emailing does not preclude emotional exchange and many times it causes us to engage in spiralling exchanges of increasingly angry emailing. The purpose of this chapter is threefold: to explore how factors of temporality are related to anger when emailing, to model circumstances that protect against, but also ignite, anger escalation, and to raise a discussion for practitioners of how to avoid damaging email communication. By intersecting literature on communication, information systems, psychology and organisational studies, factors leading to an ‘emotional verge’ are identified and summarised in a model showing factors likely to prime, but also protect against, anger escalation.
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| 9. |
- Svensson, Peter, 1974-, et al.
(författare)
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Users’ Influence in Social-service Innovations : Two Swedish Case Studies
- 2010
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Ingår i: Journal of Social Entrepreneurship. - : Routledge Taylor and Francis. - 1942-0676 .- 1942-0684. ; 1:2, s. 190-212
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Tidskriftsartikel (refereegranskat)abstract
- This article uses case studies to address the sources of social innovation, a major contributor to economic growth and welfare services. Following the findings of user-innovation research in the commercial sector, the authors found that social-problem users innovate new social services for solving specific social problems. They also found that superior problem and solution knowledge is one reason for their ability to do this, that their legitimacy with other potential users is an important factor for their innovations’ diffusion and that the legitimacy of the new social services’ operators with other stakeholders is important for acquiring resources for their projects. This contributes to the understanding of the management of social innovation using the established theoretical framework of user innovation.
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| 10. |
- Trygg, Louise, 1966-, et al.
(författare)
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District Heating and CHP : A Vital Role for the Development towards a Sustainable Society?
- 2012
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Ingår i: Latest trends in sustainable and green deveopment - Proceedings of the 3<sup>rd</sup> International Conference on Urban Sustainability, Cultural Sustainability, Green Development, Green Structures and Clean Cars (USCUDAR 12). - : WSEAS Press. - 9781618041326 ; , s. 157-167
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Konferensbidrag (refereegranskat)abstract
- In Sweden, district heating (DH) is quite well developed and is already mainly based on non-fossil fuels. Increased use of DH is therefore considered as a way of phasing out fossil energy for heating purposes. Furthermore, increased use of DH provides an increased basis for combined heat and power production (CHP). Considering that coal condensing is the marginal production of electricity in Europe, increased use of bio-fueled CHP leads to even greater reductions of global carbon dioxide (CO2) emissions. However, in a sustainable society, where there is no longer a systematic increase of CO2 (and no other sustainability problems), the benefits of DH are less obvious. The aim of this work is to explore the impact of DH and CHP in the development towards such a society. A local energy system is studied for five different time periods from 2010 to 2060 with different marginal technologies for electricity production. Results show that when the local energy utility co-operate with a local industry plant and invests in a new CHP plant for waste incineration the global CO2 emissions for the whole studied time period will be reduced with about 48 000 tonnes, which corresponds to over 100 % of the emissions from today’s system for the same time period. When considering that bio fuel is a scarce resource, and that the amount of CO2 emission linked to waste probably will be lower in sustainable society, the global CO2 emissions will be about 250% lower compared to the system of today. The studied DH related cooperation and introduction of CHP will reduce the system cost for the whole studied energy system with 2 500 MSEK for the studied period. In general, the results indicate that the modeled measures will not have any major advantages over other heating technologies in a sustainable society but that it can play a vital role for the development towards such a society.
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