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Sökning: WFRF:(Tufvesson Fredrik) > Naturvetenskap

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1.
  • Neij, Lena, et al. (författare)
  • Lunds kommuns klimatpolitiska råd: Rapport 2019
  • 2019
  • Rapport (populärvet., debatt m.m.)abstract
    • Lunds kommuns klimatpolitiska råd bildades hösten 2018 med uppdrag attutvärdera hur Lunds kommuns samlade politik är förenlig med de klimatmålsom antagits av kommunfullmäktige. Rådet som är det första lokala klimatpolitiska rådet i Sverige är en unik satsning för främjandet av ett aktivt och framåtsyftande lokalt klimatarbete.Sveriges kommuner har en viktig roll att fylla i klimatarbetet – för såväl minskad klimatpåverkan som anpassning till ett förändrat klimat. Lunds kommun har genom åren visat på handlingskraft inom miljö- och klimatområdet och har antagit ambitiösa klimatmål. I bildandet av ett klimatpolitiskt råd befäster kommunen sin ambition om att bedriva ett kunskapsbaserat klimatarbete. Kommunens vision ”Lund skapar framtiden – med kunskap, innovation och öppenhet” inspirerar även till handling och engagemang i det lokala klimatarbetet. Samarbetet mellan Lunds kommun och akademin har sedan länge stimulerat utvecklingen i Lund och utgör en viktig källa till nytänkande och problemlösning. Rådet ser fram emot uppgiften att utvärdera kommunens klimatarbete men uttrycker samtidigt en ödmjukhet inför komplexiteten i detta arbete. Rådets ambition är att bidra konstruktivt och lösningsorienterat till utvecklingen av det lokala klimatarbetet.Lunds kommuns klimatpolitiska råd kommer årligen att presentera en rapport i vilken rådet granskar Lunds kommuns samlade klimatpolitik. Detta är rådets första rapport och granskningen utgår från de mål som presenteras i LundaEko II under rubrikerna ”Minsta möjliga klimatpåverkan” och ”Klimatanpassning”. I rapporten utvärderar rådet i vilken utsträckning kommunens arbete är tillräckligt för att nå etappmålen för 2020 samt identifierar utmaningar och rekommendationer för arbetet med att nå de övergripande målen för 2030 och 2050. Rådet påbörjade sitt uppdrag först hösten 2018 och har behövt ägna tid åt att lära känna kommunens lokala klimatarbete. Granskningen i rådets första rapport är därför av övergripande karaktär.Ett framgångsrikt klimatarbete förutsätter en bred kunskapsbas. Lunds kommuns klimatpolitiska råd består av forskare med bred tvär- och mångvetenskaplig kompetens från Lunds universitet (LU) och SLU Alnarp. Ett lyckat klimatarbete kräver även ett bredare engagemang, vilket rådet avser bidra till genom god kommunikation och inkluderande dialog.
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2.
  • Fedorov, Aleksei, et al. (författare)
  • Implementation of spatially consistent channel models for real-time full stack C-ITS V2X simulations
  • 2021
  • Ingår i: 55th Asilomar Conference on Signals, Systems and Computers, ACSSC 2021. - 1058-6393. - 9781665458283 ; 2021-October, s. 67-71
  • Konferensbidrag (refereegranskat)abstract
    • Vehicle-to-everything (V2X) wireless communication is expected to play a key role in enabling complex Advanced Driving Assistance Applications, including the support of emerging autonomous vehicles. The development of V2X applications, especially safety-related, requires rigorous verification. Field trials, though, have to be supplemented with less expensive and more repeatable methods. Thorough V2X modeling could be an efficient approach to boost V2X development. However, to be helpful, V2X modeling has to be realistic and properly capture the signal propagation in a complex V2X environment. To this end, Geometry Based Stochastic Models (GSCM) have been derived to account for the influence of the environment as well as small yet critical details, where we typically lack information about their physical and geometrical properties. In this paper, we present an implementation of a GSCM in the Unity3D game engine. Due to extensive signal path search in a 3D environment with ray-tracing, the GSCM computation has to be further optimized to enable real-time V2X simulations. Thus, we also propose the approach for GSCM computation optimization and explain the practicalities of its implementation. The results show that optimization can accelerate the simulation framework up to a few thousand times without losing the precision in modeling channel characteristics.
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3.
  • Gustafson, Carl, et al. (författare)
  • Modeling the cluster decay in mm-wave channels
  • 2014
  • Ingår i: 8th European Conference on Antennas and Propagation, EuCAP 2014. - 9788890701849 ; , s. 803-807
  • Konferensbidrag (refereegranskat)abstract
    • © 2014 European Association on Antennas and Propagation.The cluster power is an important parameter for cluster-based wireless channel models. This paper addresses modeling and estimation of the cluster power for wireless channels. A novel way of estimating the cluster decay and cluster fading, where the effects of the noise floor is taken into account, is presented. Due to the noise floor present in the measurement, only a limited number of clusters are available when estimating the cluster decay. It is shown that the estimated cluster decay and cluster fading can be improved if the effects of the noise floor and cluster fading are modeled and taken into account in the estimation step. If the noise floor is not taken into account in the estimation of the cluster decay, the resulting model can overestimate the RMS delay spread. Further, the paper includes estimates of the cluster decay and fading based on measured clusters for an indoor wireless mm-Wave channel in a conference room environment.
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4.
  • Li, Xuhong, et al. (författare)
  • A Belief Propagation Algorithm for Multipath-based SLAM with Multiple Map Features: A mmWave MIMO Application
  • 2024
  • Annan publikation (övrigt vetenskapligt/konstnärligt)abstract
    • In this paper, we present a multipath-based simultaneous localization and mapping (SLAM) algorithm that continuously adapts mulitiple map feature (MF) models describing specularly reflected multipath components (MPCs) from flat surfaces and point-scattered MPCs, respectively. We develop a Bayesian model for sequential detection and estimation of interacting MF model parameters, MF states and mobile agent's state including position and orientation. The Bayesian model is represented by a factor graph enabling the use of belief propagation (BP) for efficient computation of the marginal posterior distributions. The algorithm also exploits amplitude information enabling reliable detection of weak MFs associated with MPCs of very low signal-to-noise ratios (SNRs). The performance of the proposed algorithm is evaluated using real millimeter-wave (mmWave) multiple-input-multiple-output (MIMO) measurements with single base station setup. Results demonstrate the excellent localization and mapping performance of the proposed algorithm in challenging dynamic outdoor scenarios.
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5.
  • Li, Xuhong, et al. (författare)
  • Robust Phase-Based Positioning Using Massive MIMO with Limited Bandwidth
  • 2018
  • Ingår i: 28th Annual IEEE International Symposium on Personal, Indoor and Mobile Radio Communications, PIMRC 2017.. - 9781538635292 - 9781538635322
  • Konferensbidrag (refereegranskat)abstract
    • This paper presents a robust phase-based positioningframework using a massive multiple-input multiple-output(MIMO) system. The phase-based distance estimates of MPCstogether with other parameters are tracked with an ExtendedKalman Filter (EKF), the state dimension of which varies withthe birth-death processes of paths. The iterative maximumlikelihoodestimation algorithm (RIMAX) and the modeling ofdense multipath component (DMC) in the framework furtherenhance the quality of parameter tracking by providing anaccurate initial state and the underlying noise covariance.The tracked MPCs are fed into a time-of-arrival (TOA) selfcalibrationpositioning algorithm for simultaneous trajectoryand environment estimation. Throughout the positioning process,no prior knowledge of the surrounding environment andbase station position is needed. The performance is evaluatedwith the measurement of a 2D complex movement, which wasperformed in a sports hall with an antenna array with 128 portsas base station using a standard cellular bandwidth of 40 MHz.The positioning result shows that the mean deviation of theestimated user equipment trajectory from the ground truth is13 cm. In summary, the proposed framework is a promisinghigh-resolution radio-based positioning solution for current andnext generation cellular systems.
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6.
  • Pirk, Norbert, et al. (författare)
  • Methane emission bursts from permafrost environments during autumn freeze-in: New insights from ground-penetrating radar
  • 2015
  • Ingår i: Geophysical Research Letters. - 1944-8007. ; 42:16, s. 6732-6738
  • Tidskriftsartikel (refereegranskat)abstract
    • Large amounts of methane (CH4) are known to be emitted from permafrost environments during the autumn freeze-in, but the specific soil conditions leading up to these bursts are unclear. Therefore, we used an ultrawide band ground-penetrating radar in Northeast Greenland in autumn 2009 to estimate the volumetric composition inside the soil through dielectric characterization from 200 to 3200 MHz. Our results suggest a compression of the gas reservoir during the phase transition of soil water, which is accompanied by a peak in surface CH4 emissions. About 1 week thereafter, there seems to be a decompression event, consistent with ground cracking which allows the gas reservoir to expand again. This coincides with the largest CH4 emission, exceeding the summer maximum by a factor of 4. We argue that these complementary measurement techniques are needed to come to an understanding of tundra CH4 bursts connected to soil freezing.
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7.
  • Pradhan, Anish, et al. (författare)
  • Stochastic Geometry Analysis of a New GSCM with Dual Visibility Regions
  • 2023
  • Ingår i: 2023 IEEE 34th Annual International Symposium on Personal, Indoor and Mobile Radio Communications : 6G The Next Horizon - From Connected People and Things to Connected Intelligence, PIMRC 2023 - 6G The Next Horizon - From Connected People and Things to Connected Intelligence, PIMRC 2023. - 9781665464833
  • Konferensbidrag (refereegranskat)abstract
    • The geometry-based stochastic channel models (GSCM), which can describe realistic channel impulse responses, often rely on the existence of both local and far scatterers. However, their visibility from both the base station (BS) and mobile station (MS) depends on their relative heights and positions. For example, the condition of visibility of a scatterer from the perspective of a BS is different from that of an MS and depends on the height of the scatterer. To capture this, we propose a novel GSCM where each scatterer has dual disk visibility regions (VRs) centered on itself for both BS and MS, with their radii being our model parameters. Our model consists of short and tall scatterers, which are both modeled using independent inhomogeneous Poisson point processes (IPPPs) having distinct dual VRs. We also introduce a probability parameter to account for the varying visibility of tall scatterers from different MSs, effectively emulating their noncontiguous VRs. Using stochastic geometry, we derive the probability mass function (PMF) of the number of multipath components (MPCs), the marginal and joint distance distributions for an active scatterer, the mean time of arrival (ToA), and the mean received power through non-line-of-sight (NLoS) paths for our proposed model. By selecting appropriate model parameters, the propagation characteristics of our GSCM are demonstrated to closely emulate those of the COST-259 model.
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8.
  • Tärneberg, William, et al. (författare)
  • The 6G Computing Continuum (6GCC) : Meeting the 6G computing challenges
  • 2022
  • Ingår i: 2022 1st International Conference on 6G Networking, 6GNet 2022. - : IEEE Computer Society. - 9781665467636
  • Konferensbidrag (refereegranskat)abstract
    • 6G systems, such as Large Intelligent Surfaces, will require distributed, complex, and coordinated decisions through-out a very heterogeneous and cell free infrastructure. This will require a fundamentally redesigned software infrastructure accompanied by massively distributed and heterogeneous computing resources, vastly different from current wireless networks. To address these challenges, in this paper, we propose and motivate the concept of a 6G Computing Continuum (6GCC) and two research testbeds, to advance the rate and quality of research. 6G Computing Continuum is an end-to-end compute and software platform for realizing large intelligent surfaces and its tenant users and applications. One for addressing the challenges or orchestrating shared computational resources in the wireless domain, implemented on a Large Intelligent Surfaces testbed. Another simulation-based testbed is intended to address scalability and global-scale orchestration challenges.
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9.
  • Yaman, Ilayda, et al. (författare)
  • LuViRA Dataset Validation and Discussion: Comparing Vision, Radio, and Audio Sensors for Indoor Localization
  • Ingår i: IEEE Journal of Indoor and Seamless Positioning and Navigation. - 2832-7322.
  • Tidskriftsartikel (refereegranskat)abstract
    • We present a unique comparative analysis, and evaluation of vision, radio, and audio based localization algorithms. We create the first baseline for the aforementioned sensors using the recently published Lund University Vision, Radio, and Audio (LuViRA) dataset, where all the sensors are synchronized and measured in the same environment. Some of the challenges of using each specific sensor for indoor localization tasks are highlighted. Each sensor is paired with a current state-of-the-art localization algorithm and evaluated for different aspects: localization accuracy, reliability and sensitivity to environment changes, calibration requirements, and potential system complexity. Specifically, the evaluation covers the ORB-SLAM3 algorithm for vision-based localization with an RGB-D camera, a machine-learning algorithm for radio-based localization with massive MIMO technology, and the SFS2 algorithm for audio-based localization with distributed microphones. The results can serve as a guideline and basis for further development of robust and high-precision multi-sensory localization systems, e.g., through sensor fusion, and context- and environment-aware adaptation.
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10.
  • Yaman, Ilayda, et al. (författare)
  • The LuViRA Dataset: Synchronized Vision, Radio, and Audio Sensors for Indoor Localization
  • 2024
  • Ingår i: 2024 IEEE International Conference on Robotics and Automation (ICRA). - 9798350384574
  • Konferensbidrag (refereegranskat)abstract
    • We present a synchronized multisensory dataset for accurate and robust indoor localization: the Lund University Vision, Radio, and Audio (LuViRA) Dataset. The dataset includes color images, corresponding depth maps, inertial measurement unit (IMU) readings, channel response between a 5G massive multiple-input and multiple-output (MIMO) testbed and user equipment, audio recorded by 12 microphones, and accurate six degrees of freedom (6DOF) pose ground truth of 0.5 mm. We synchronize these sensors to ensure that all data is recorded simultaneously. A camera, speaker, and transmit antenna are placed on top of a slowly moving service robot, and 89 trajectories are recorded. Each trajectory includes 20 to 50 seconds of recorded sensor data and ground truth labels. Data from different sensors can be used separately or jointly to perform localization tasks, and data from the motion capture (mocap) system is used to verify the results obtained by the localization algorithms. The main aim of this dataset is to enable research on sensor fusion with the most commonly used sensors for localization tasks. Moreover, the full dataset or some parts of it can also be used for other research areas such as channel estimation, image classification, etc. Our dataset is available at: https://github.com/ilaydayaman/LuViRA_Dataset
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