| 1. |
- Öztürk, Cüneyd, et al.
(author)
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On the Impact of Hardware Impairments on RIS-aided Localization
- 2022
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In: IEEE International Conference on Communications. - 1550-3607. ; 2022-May, s. 2846-2851
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Conference paper (peer-reviewed)abstract
- We investigate a reconfigurable intelligent surface (RIS)-aided near-field localization system with single-antenna user equipment (UE) and base station (BS) under hardware impairments by considering a practical phase-dependent RIS amplitude variations model. To analyze the localization performance under the mismatch between the practical model and the ideal model with unit-amplitude RIS elements, we employ the misspecified Cramér-Rao bound (MCRB). Based on the MCRB derivation, the lower bound (LB) on the mean-squared error for estimation of UE position is evaluated and shown to converge to the MCRB at low signal-to-noise ratios (SNRs). Simulation results indicate more severe performance degradation due to the model misspecification with increasing SNR. In addition, the mismatched maximum likelihood (MML) estimator is derived and found to be tight to the LB in the high SNR regime. Finally, we observe that the model mismatch can lead to an order-of-magnitude localization performance loss at high SNRs.
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| 2. |
- Özkahraman, Özer, 1992-, et al.
(author)
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Collaborative Navigation-Aware Coverage in Feature-Poor Environments
- 2022
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In: International Conference on Intelligent Robots and Systems (IROS), 2022.
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Conference paper (peer-reviewed)abstract
- Multi agent coverage and robot navigation are two very important research fields within robotics. However, their intersection has received limited attention. In multi agent coverage, perfect navigation is often assumed, and in robot navigation, the focus is often to minimize the localization error with the aid of stationary features from the environment.The need for integration of the two becomes clear in environments with very sparse features or landmarks, for example when a group of Autonomous Underwater Vehicles (AUVs) are to search a uniform seafloor for mines or other dangerous objects.In such environments, localization systems are often deprived of detectable features to use that could increase their accuracy.In this paper we propose an algorithm for doing navigation aware multi agent coverage in areas with no landmarks.Instead of using identical lawn mower patterns, we propose to mirror every other pattern to enable the agents to meet up and makeinter-agent measurements and share information regularly. This improves performance in two ways,global drift in relation to the area to be covered is reduced, and local coverage gaps between adjacent patterns are reduced.Further, we show that this can be accomplished within the constraints of very limited sensing, computing and communication resources that most AUVs have available.The effectiveness of our method is shown through statistically significant simulated experiments.
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| 3. |
- Özkahraman, Özer, 1992-, et al.
(author)
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Combining Control Barrier Functions and Behavior Trees for Multi-Agent Underwater Coverage Missions
- 2020
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In: Proceedings of 59th Conference on Decision and Control, 2020.
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Conference paper (peer-reviewed)abstract
- Robot missions typically involve a number of desired objectives, such as avoiding collisions, staying connected to other robots, gathering information using sensors and returning to the charging station before the battery runs out.Some of these objectives need to be taken into account at the same time, such as avoiding collisions and staying connected, while others are focused upon during different parts of the executions, such as returning to the charging station and connectivity maintenance.In this paper, we show how Control Barrier Functions(CBFs) and Behavior Trees(BTs) can be combined in a principled manner to achieve both types of task compositions, with performance guarantees in terms of mission completion. We illustrate our method with a simulated underwater coverage mission.
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| 4. |
- Özkaya Sahin, Gülsen, et al.
(author)
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Potent Intratype Neutralizing Activity Distinguishes Human Immunodeficiency Virus Type 2 (HIV-2) from HIV-1
- 2012
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In: Journal of Virology. - 1098-5514. ; 86:2, s. 961-971
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Journal article (peer-reviewed)abstract
- HIV-2 has a lower pathogenicity and transmission rate than HIV-1. Neutralizing antibodies could be contributing to these observations. Here we explored side by side potency and breadth of intratype and intertype neutralizing activity (NAc) in plasma of 20 HIV-1, 20 HIV-2 and 11 dually HIV-1/2 (HIV-D) seropositive individuals from Guinea-Bissau, West Africa. Panels of primary isolates, five HIV-1 and five HIV-2, were tested in a plaque reduction assay using U87.CD4-CCR5 cells as targets. Intratype NAc in HIV-2 plasma was found to be considerably more potent, and also broader, than intratype NAc in HIV-1 plasma. This indicates that HIV-2 infected individuals display potent type-specific neutralizing antibodies, whereas such a strong type-specific antibodies are absent in HIV-1 infection. Furthermore, potency of intratype NAc was positively associated with viral load of HIV-1, but not HIV-2, suggesting that NAc in HIV-1 infection is more antigen stimulation-dependent than in HIV-2 infection where plasma viral loads typically are at least tenfold lower than in HIV-1 infection. Intertype NAc of both HIV-1 and HIV-2 infected was instead of low potency. HIV-D subjects had NAc to HIV-2 with similar high potency as singly HIV-2 infected individuals, whereas neutralization of HIV-1 remained poor, indicating that the difference in NAc between HIV-1 and HIV-2 infections depends on the virus itself. We suggest that immunogenicity and/or antigenicity, meaning the neutralization phenotype, of HIV-2 is distinct from HIV-1, and that HIV-2 may display structures that favour triggering of potent neutralizing antibody responses.
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| 5. |
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| 6. |
- Öztürk, Ahmet Erdi, et al.
(author)
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Diyanet as a Turkish Foreign Policy Tool: Evidence from the Netherlands and Bulgaria
- 2018
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In: Politics and Religion. - : CAMBRIDGE UNIV PRESS. - 1755-0483 .- 1755-0491. ; 11:3, s. 624-648
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Journal article (peer-reviewed)abstract
- How does Turkeys Presidency of Religious Affairs (Diyanet) act as an instrument of foreign policy (FP)? What are the factors that allow such an instrumentalization of Islam in Turkish FP? In addressing these questions, this paper uses semi-structured expert interviews from Bulgaria and the Netherlands. Although both countries host a sizeable Muslim minority, these populations differ in their characteristics and historical ties with Turkey. Comparing Diyanets role in the Netherlands with its recent Turkish-Muslim diaspora, and in Bulgaria with its centuries-old Muslim minority allows us to reveal variation in the practical engagement strategies that Diyanet adopts in different country contexts. Thus, this paper advances two main claims; first, Diyanet serves as a primary FP tool of Turkey in countries with a significant Turkish-Muslim minority. Secondly, this instrumentalization destabilizes secularization projects both at home and abroad.
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| 7. |
- Miranda Carranza, Pablo, 1972-, et al.
(author)
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- 2009
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Conference paper (other academic/artistic)abstract
- This paper gives an overview of the approach of working methods at the Aedas R&DComputational Design and Research [CDR] Group. It first contextualizes research inarchitectural practice and tries to propose an explanation for the difficulties inimplementing it; then explains the evolution of the groups’ computing approach frombespoke to heuristic sets of lightweight applications. It concludes with examples of thedeveloped computational design approach.
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| 8. |
- Adler, Niclas, et al.
(author)
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- 2002
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Reports (other academic/artistic)
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| 9. |
- Sjödin, David Rönnberg, et al.
(author)
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- 2016
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In: IAMOT 2015. - Pretoria : Graduate School of Technology Management, University of Pretoria. - 9781775921110 ; , s. 477-487
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Conference paper (peer-reviewed)abstract
- Absorptive capacity, conceptualized as identifying, selecting and integrating useful knowledge from the environment into commercial applications, is a key capability for any organization, team or individual. While prior literature has made substantial advancement into the performance consequences of absorptive capacity, few studies have addressed what actually constitutes ACAP on a micro level. Thus, there exists a significant gap within the literature concerning the micro-foundations of ACAP. This study attempts to fill this gap by means of multiple case studies within the R&D organizations of three multinational engineering firms. Our findings show how the micro foundations of absorptive capacity are rooted in individual skills, roles and relationships.
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| 10. |
- Aad, G., et al.
(author)
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- 2012
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swepub:Mat__t (peer-reviewed)
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