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| 2. |
- Carvajal, Gisela, 1983, et al.
(författare)
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Comparison of Automotive FMCW and OFDM Radar Under Interference
- 2020
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Ingår i: IEEE National Radar Conference - Proceedings. - New York, NY : IEEE. - 1097-5659. ; 2020-September
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Konferensbidrag (refereegranskat)abstract
- Automotive radars are subject to interference in spectrally congested environments. To mitigate this interference, various waveforms have been proposed. We compare two waveforms (FMCW and OFDM) in terms of their radar performance and robustness to interference, under similar parameter settings. Our results indicate that under proper windowing both waveforms can achieve similar performance, but OFDM is more sensitive to interference.
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| 3. |
- Flys, Olena, 1971-, et al.
(författare)
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Using confocal fusion for measurement of metal AM surface texture
- 2020
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Ingår i: Surface Topography: Metrology and Properties. - Bristol : IOP Publishing Ltd. - 2051-672X. ; 8:2
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Tidskriftsartikel (refereegranskat)abstract
- The highly complex nature of as printed metal AM surfaces pose other challenges for making measurements compared to surfaces made with many conventional processing methods. The high complexity is caused by high aspect ratios, a mix of high and low reflexivity, steep angles etc. It is not clear which method is the most suitable for measuring these surfaces. The objective of this study was to compare four different measurement modes available in one instrument to evaluate the advantages and drawbacks of the respective techniques regarding measurements of metal AM surfaces. The evaluated measurement modes are Confocal Microscopy, Coherence Scanning Interferometry, Focus Variation and Confocal Fusion. The effect of advantages and drawbacks of studied techniques was tested on typical surfaces produced by L-PBF process. Surfaces printed at 0° and 90° inclinations were compared regarding the measurement results achieved from the different methods. The Power Spectral Density analysis and visual comparison were used for the examination of studied measurements methods. Besides the comparison of areal measurements acquired by different modes available in the instrument also extracted profile measurements were compared with profile images acquired using an Optical Microscope. This study reveals that confocal fusion is a promising technique for AM surface characterisation, due to the highest amount of valid data points in the typical measurement. The new approach developed in the study showed that PSD analysis can be used for evaluation of fill in algorithms incorporated in different software. Results of the profile comparisons help to illustrate features that can be depicted by surface measurements, applying different measurement principles, as well as enables comparison of raw profile data between different types of measurements. Further investigation of measurements on AM surfaces in the frequency domain will bring more understanding about the limitations of measurement techniques.
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| 4. |
- Averfalk, Helge, 1988-, et al.
(författare)
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Low‐temperature excess heat recovery in district heating systems : The potential of European Union metro stations
- 2020
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Ingår i: Book of Abstracts. ; , s. 34-34
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Konferensbidrag (övrigt vetenskapligt/konstnärligt)abstract
- This paper presents an assessment of the excess heat recovery potential from EU metro stations. The assessment is a sub-study on low temperature recovery opportunities, explored in the H2020 ReUseHeat project, and consists of spatial mapping of 1994 underground stations with quantitative estimates of sensible and latent heat, monthly and annually, attainable in rejected platform ventilation exhaust air. Being a low-temperature source, the assessment conceptually anticipates recovery of attainable heat with compressor heat pumps to facilitate the temperature increase necessary for utilisation in district heating systems. Further, the paper explores the influence on useful excess heat volumes from low-temperature heat recoveries when distributed at different temperature levels. The findings, which distinguishes available (resource) and accessible (useful) excess heat potentials, indicate an annual total EU28 available potential of ~21 PJ, characterised by a certain degree of seasonal temporality, and corresponding accessible potentials of ~40 PJ per year at 3rd generation distribution, and of ~31 PJ at anticipated 4th generation conditions. Despite lower accessible volumes, utilisation in 4th generation systems are naturally more energy efficient, since relatively less electricity is used in the recovery process, but also more cost-effective, since heat pumps, at lower temperatures, can be operated at capacities closer to design conditions and with less annual deviations.
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| 5. |
- Chen, Lei, et al.
(författare)
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Federated Learning to Enable Automotive Collaborative Ecosystem : Opportunities and Challenges
- 2020
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Ingår i: Proceedings of Virtual ITS European Congress.
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Konferensbidrag (refereegranskat)abstract
- Despite the strong interests in creating data economy, automotive industries are creating data silos with each stakeholder maintaining its own data cloud. Federated learning (FL), designed for privacy-preserving collaborative Machine Learning (ML), offers a promising method that allows multiple stakeholders to share information through ML models without the exposure of raw data, thus natively protecting privacy. Motivated by the strong need for automotive collaboration and the advancement of FL, this paper investigates how FL could enable privacy-preserving information sharing for automotive industries. We first introduce the statuses and challenges for automotive data sharing, followed by a brief introduction to FL. We then present a comprehensive discussion on potential applications of federated learning to enable an automotive collaborative ecosystem. To illustrate the benefits, we apply FL for driver action classification and demonstrate the potential for collaborative machine learning without data sharing.
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| 6. |
- Dénarié, Alice, et al.
(författare)
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Assessment of renewable and waste heat recovery for DH through GIS mapping : the national potential in Italy
- 2020
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Ingår i: Book of Abstracts. ; , s. 129-129
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Konferensbidrag (övrigt vetenskapligt/konstnärligt)abstract
- This work aims at showing the potential of waste and renewable heat recovery in Italy through detailed mapping of these sources. The ambition of this analysis is to highlight the areas with important heat recovery potential and to show how the matching with suitable heat demand would allow its exploitation through district heating expansion. The importance of waste heat and renewable heat potentially recoverable to reduce primary energy consumption in the civil sector is widely recognized. Nevertheless, these potential is widely unexploited in Italy. The processes and energy sources have been analysed in terms of geographical location, quantification of available heat and recovery costs with a special focus on temperature levels. The main distinction between low temperature and high temperature heat sources has been applied in order to identify the heat recovery characteristics and the consequent additional costs for temperature upgrades. The inputs of the analysis performed in this work come from national database, which has allowed obtaining more detailed and wider results with respect to international existing studies on the same subject. Two different approaches have been used to map potential heat: one to identify and quantify existing waste heat recovery and one to assess and estimate energy coming from potential new plants. The analysed sources belonging to the first category are industrial processes, waste to energy plants, waste water treatment plants and datacentres, while biomass, geothermal energy and electrolysis plants estimation belong to the second one. Results shows that the national available waste and renewable heat amount to 270 TWh which is an important outcome in comparison with a national heat demand for the residential and tertiary sector of 400 TWh. Out of this results, according to a nuts 3 regional aggregation of heat demand, 95 TWh could be recovered in DH. The reduction from theoretical potential of 270 TWh to 95 TWh is due to geographical matching of heat demand and available waste heat and on some hypothesis related to the diffusion of DH. This work shows the huge unexpressed potential of waste heat reutilisation in Italy and how the mapping of recoverable heat and not only its quantification is essential to properly estimate the utilization potential.
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| 7. |
- Ghasemi, Yahya, 1982-, et al.
(författare)
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Shape-dependent calculation of specific surface area of aggregates versus X-ray microtomography
- 2020
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Ingår i: Magazine of Concrete Research. - London : Institution of Civil Engineers (ICE). - 0024-9831 .- 1751-763X. ; 72:2, s. 88-96
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Tidskriftsartikel (refereegranskat)abstract
- The specific surface area (SSA) of constituents in a concrete mixture has a significant effect on its workability in fresh state. Excess layer theories relate the SSA to the flow behaviour of mixtures and can be used as part of an approach to mix design. However, measurement of SSA is complex and includes several issues, and thus is commonly replaced by mathematical estimation of the parameter. The mathematical approximation of surface area is based on the assumption of a spherical shape for the particles, which leads to failure of taking into account the effect of shape and the square–cube law. The article explores the possibility of replacing the assumption of a spherical shape with that of Platonic solids as the representative shape to account for the angularity of aggregates. The calculation was conducted based on information on the particle size distribution (PSD) obtained from dry sieving method. A calculated surface area on the assumption of a dodecahedron shape for natural aggregates and a cubical shape for crushed aggregates showed good agreement with SSA measurements conducted by X-ray microtomography. Furthermore, the effect of changes in PSD on the accuracy of the approach was also studied. It was found that the estimated value of SSA was improved in comparison with the traditional way of calculation on the assumption of a spherical shape.
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| 8. |
- Gidlund, Mikael, 1972-, et al.
(författare)
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Guest Editorial : Security, Privacy, and Trust for Industrial Internet of Things
- 2020
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Ingår i: IEEE Transactions on Industrial Informatics. - Piscataway, NJ : IEEE. - 1551-3203 .- 1941-0050. ; 16:1, s. 625-628
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Tidskriftsartikel (övrigt vetenskapligt/konstnärligt)abstract
- This Special Section on "Security, privacy, and trust for Industrial Internet of Things" of the IEEE Transactions on Industrial Informatics (TII) highlights the main research challenges in the industrial Internet of Things (IoT) security, privacy, and trust. The designated nine high-quality research articles cover a wide range of the special section theme, including innovative solutions and novel technologies. These articles are briefly summarized. © 2019 IEEE.
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| 9. |
- KRISHNA, AMOGH VEDANTHA, 1990
(författare)
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Towards Topography Characterization of Additive Manufacturing Surfaces
- 2020
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Licentiatavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Additive Manufacturing (AM) is on the verge of causing a downfall to conventional manufacturing with its huge potential in part manufacture. With an increase in demand for customized product, on-demand production and sustainable manufacturing, AM is gaining a great deal of attention from different industries in recent years. AM is redefining product design by revolutionizing how products are made. AM is extensively utilized in automotive, aerospace, medical and dental applications for its ability to produce intricate and lightweight structures. Despite their popularity, AM has not fully replaced traditional methods with one of the many reasons being inferior surface quality. Surface texture plays a crucial role in the functionality of a component and can cause serious problems to the manufactured parts if left untreated. Therefore, it is necessary to fully understand the surface behavior concerning the factors affecting it to establish control over the surface quality. The challenge with AM is that it generates surfaces that are different compared to conventional manufacturing techniques and varies with respect to different materials, geometries and process parameters. Therefore, AM surfaces often require novel characterization approaches to fully explain the manufacturing process. Most of the previously published work has been broadly based on two-dimensional parametric measurements. Some researchers have already addressed the AM surfaces with areal surface texture parameters but mostly used average parameters for characterization which is still distant from a full surface and functional interpretation. There has been a continual effort in improving the characterization of AM surfaces using different methods and one such effort is presented in this thesis. The primary focus of this thesis is to get a better understanding of AM surfaces to facilitate process control and optimization. For this purpose, the surface texture of Fused Deposition Modeling (FDM) and Laser-based Powder Bed Fusion of Metals (PBF-LB/M) have been characterized using various tools such as Power Spectral Density (PSD), Scale-sensitive fractal analysis based on area-scale relations, feature-based characterization and quantitative characterization by both profile and areal surface texture parameters. A methodology was developed using a Linear multiple regression and a combination of the above-mentioned characterization techniques to identify the most significant parameters for discriminating different surfaces and also to understand the manufacturing process. The results suggest that the developed approaches can be used as a guideline for AM users who are looking to optimize the process for gaining better surface quality and component functionality, as it works effectively in finding the significant parameters representing the unique signatures of the manufacturing process. Future work involves improving the accuracy of the results by implementing improved statistical models and testing other characterization methods to enhance the quality and function of the parts produced by the AM process.
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| 10. |
- Marinho, Marco A. M., 1986-, et al.
(författare)
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Non-Line-of-Sight Based Radio Localization With Dual-Polarization Antenna Arrays
- 2020
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Ingår i: WSA 2020. - Berlin : VDE Verlag GmbH. - 9783800752003
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Konferensbidrag (refereegranskat)abstract
- This work presents an approach for radio-based localization in non-line-of-sight (NLOS) environments by leveraging a dual-polarization antenna array. By estimating the polarization of the received signal, it is possible to estimate the angle of reflection of a NLOS signal. An estimate of the position of the transmitter concerning the receiver can be obtained based on a joint estimation of the reflection angle of several NLOS signals together with their respective directions of arrival (DOAs) and time differences of arrival (TDOAs). A set of numerical simulations is used to assess the performance of the proposed method. © VDE VERLAG GMBH. Berlin. Offenbach
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