| 1. |
- Algaba, Juan-Carlos, et al.
(författare)
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Broadband Multi-wavelength Properties of M87 during the 2017 Event Horizon Telescope Campaign
- 2021
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Ingår i: Astrophysical Journal Letters. - : American Astronomical Society. - 2041-8213 .- 2041-8205. ; 911:1
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Forskningsöversikt (refereegranskat)abstract
- In 2017, the Event Horizon Telescope (EHT) Collaboration succeeded in capturing the first direct image of the center of the M87 galaxy. The asymmetric ring morphology and size are consistent with theoretical expectations for a weakly accreting supermassive black hole of mass ∼6.5 × 109 M o˙. The EHTC also partnered with several international facilities in space and on the ground, to arrange an extensive, quasi-simultaneous multi-wavelength campaign. This Letter presents the results and analysis of this campaign, as well as the multi-wavelength data as a legacy data repository. We captured M87 in a historically low state, and the core flux dominates over HST-1 at high energies, making it possible to combine core flux constraints with the more spatially precise very long baseline interferometry data. We present the most complete simultaneous multi-wavelength spectrum of the active nucleus to date, and discuss the complexity and caveats of combining data from different spatial scales into one broadband spectrum. We apply two heuristic, isotropic leptonic single-zone models to provide insight into the basic source properties, but conclude that a structured jet is necessary to explain M87's spectrum. We can exclude that the simultaneous γ-ray emission is produced via inverse Compton emission in the same region producing the EHT mm-band emission, and further conclude that the γ-rays can only be produced in the inner jets (inward of HST-1) if there are strongly particle-dominated regions. Direct synchrotron emission from accelerated protons and secondaries cannot yet be excluded.
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| 2. |
- Delsing, Jerker, et al.
(författare)
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Migration of SCADA/DCS Systems to the SOA Cloud
- 2014
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Ingår i: Industrial Cloud-Based Cyber-Physical Systems. - Cham : Encyclopedia of Global Archaeology/Springer Verlag. - 9783319056234 - 9783319056241 ; , s. 111-135
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Bokkapitel (refereegranskat)abstract
- As process control and monitoring systems based on a Service-Oriented Architecture (SOA) are maturing, the need increases for a systematic approach to migrate systems. The legacy systems are traditionally based on a strict hierarchy and in order to gradually allow additional cross-layer interaction, the migration procedure needs to consider both—functionality and architecture of the legacy system. The migration procedure proposed here aims to preserve the functional integration, organize the SOA cloud through grouping of devices, and maintain the performance aspects such as real-time control throughout the whole migration procedure.
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| 3. |
- Jammes, François, et al.
(författare)
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Promising Technologies for SOA-Based Industrial Automation Systems
- 2014
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Ingår i: Industrial Cloud-Based Cyber-Physical Systems. - Cham : Encyclopedia of Global Archaeology/Springer Verlag. - 9783319056234 - 9783319056241 ; , s. 89-109
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Bokkapitel (refereegranskat)abstract
- In the last years service-oriented architectures have been extensively used to enable seamless interaction and integration among the various heterogeneous systems and devices found in modern factories. The emerging Industrial Automation Systems are increasingly utilising them. In the cloud-based vision of IMC-AESOP such technologies take an even more key role as they empower the backbone of the new concepts and approaches under development. Here we report about the investigations and assessments performed to find answers to some of the major questions that arise as key when technologies have to be selected and used in an industrial context utilizing Service-Oriented Architecture (SOA)-based distributed large-scale process monitoring and control system. Aspects of integration, real-timeness, distributeness, event-based interaction, service-enablement, etc., are approached from different angles and some of the promising technologies are analysed and assessed.
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| 4. |
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| 5. |
- Saritha, Appukuttan, et al.
(författare)
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Elastomer-based materials for EMI shielding applications
- 2020
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Ingår i: Materials for Potential EMI Shielding Applications. - : Elsevier. - 9780128175903 ; , s. 121-143
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Bokkapitel (övrigt vetenskapligt/konstnärligt)abstract
- Electromagnetic shielding is presently considered very crucial for various electrical systems owing to the creation of electromagnetic pollution instigated by the alarming usage of electronic gadgets working at diverse frequencies and power levels. Conventionally used electromagnetic interference (EMI) metallic shields lack flexibility and hence cannot be considered as the right candidates for certain applications. This problem requires immediate attention because it causes drastic effects on the lifetime and performance of electronic devices and has an adverse effect on human beings as well. Rubber-based composite materials are regarded as suitable candidates for the fabrication of electromagnetic shields due to their combined electrical conductivity, interesting mechanical, and dielectric properties, elasticity to cover curved structures, and weather resistance for outdoor applications. This chapter aims to discuss the various fillers as well as elastomers used in the fabrication of elastomeric composites used in the preparation of EMI shielding devices. Finally a discussion of elastomeric blends used for shielding purpose will also be added.
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| 6. |
- Thomas, Bony, et al.
(författare)
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Electrochemical Properties of Biobased Carbon Aerogels Decorated with Graphene Dots Synthesized from Biochar
- 2021
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Ingår i: ACS Applied Electronic Materials. - : American Chemical Society (ACS). - 2637-6113. ; 3:11, s. 4699-4710
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Tidskriftsartikel (refereegranskat)abstract
- Carbon aerogels prepared from low-cost renewable resources are promising electrode materials for future energy storage applications. However, their electrochemical properties must be significantly improved to match the commercially used high-carbon petroleum products. This paper presents a facile method for the green synthesis of carbon aerogels (CAs) from lignocellulosic materials and graphene dots (GDs) from commercially available biochar. The produced carbon aerogels exhibited a hierarchical porous structure, which facilitates energy storage by forming an electrical double-layer capacitance. Surprisingly, the electrochemical analyses of the GD-doped carbon aerogels revealed that in comparison to pristine carbon aerogels, the surface doping of GDs enhanced the electrochemical performance of carbon aerogels, which can be attributed to the combined effect from both double-layer capacitance and pseudocapacitance. Herein, we designed and demonstrated the efficacy of a supercapacitor device using our green carbon electrode as a sustainable option. These green carbon aerogels have opened a window for their practical use in designing sustainable energy storage devices.
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| 7. |
- Thomas, Bony, et al.
(författare)
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Hetero-Porous, High-Surface Area Green Carbon Aerogels for the Next-Generation Energy Storage Applications
- 2021
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Ingår i: Nanomaterials. - : MDPI. - 2079-4991. ; 11:3
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Tidskriftsartikel (refereegranskat)abstract
- Various carbon materials have been developed for energy storage applications to address the increasing energy demand in the world. However, the environmentally friendly, renewable, and nontoxic bio-based carbon resources have not been extensively investigated towards high-performance energy storage materials. Here, we report an anisotropic, hetero-porous, high-surface area carbon aerogel prepared from renewable resources achieving an excellent electrical double-layer capacitance. Two different green, abundant, and carbon-rich lignins which can be extracted from various biomasses, have been selected as raw materials, i.e., kraft and soda lignins, resulting in clearly distinct physical, structural as well as electrochemical characteristics of the carbon aerogels after carbonization. The obtained green carbon aerogel based on kraft lignin not only demonstrates a competitive specific capacitance as high as 163 F g−1 and energy density of 5.67 Wh kg−1 at a power density of 50 W kg−1 when assembled as a two-electrode symmetric supercapacitor, but also shows outstanding compressive mechanical properties. This reveals the great potential of the carbon aerogels developed in this study for the next-generation energy storage applications requiring green and renewable resources, lightweight, robust storage ability, and reliable mechanical integrity.
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| 8. |
- Thomas, Bony, et al.
(författare)
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Ice-Templating of Lignin and Cellulose Nanofiber-Based Carbon Aerogels: Implications for Energy Storage Applications
- 2022
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Ingår i: ACS Applied Nano Materials. - : American Chemical Society (ACS). - 2574-0970. ; 5:6, s. 7954-7966
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Tidskriftsartikel (refereegranskat)abstract
- Hierarchically porous carbon aerogels (CAs) were synthesized by following a green, facile preparation route involving ice-templating and lyophilization followed by carbonization. For the first time, we report CAs prepared with a cooling rate of 7.5 K/min, demonstrating a very high specific surface area (SSA) of 1260 m2 g–1 without any physical or chemical activation steps, and the electrode prepared using the latter aerogel showed superior electrochemical performance with a specific capacitance of 410 F g–1 at 2 m V s–1 with a cyclic stability of 94% after 4500 charge–discharge cycles. The effects of the ice-templating cooling rate and the solid content of lignin and cellulose nanofibers (CNFs) in the suspension on the structure and electrochemical performance of the CAs were investigated. The ice-templating process and the cooling rate were found to have a large effect on the generation of the nanoporous structure and the specific surface area of carbon aerogels, while the solid content of the lignin-nanocellulose suspension showed negligible effects. When assembled as a supercapacitor (SC), a remarkable specific capacitance of 240 F g–1 at 0.1 A g–1 was achieved. The relaxation time constant for the prepared SC was 1.3 s, which shows the fast response of these SCs. In addition, an energy density of 4.3 Wh kg–1 was also obtained at a power density of 500 W kg–1. Thus, this study opens new perspectives for the preparation of green, environment-friendly, free-standing, high-performance CA electrodes for future energy storage applications.
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| 9. |
- Thomas, Bony, et al.
(författare)
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Morphological and Dynamic Mechanical Properties of Biobased Epoxy Composites with Anisotropic, Green Carbon Aerogels as Reinforcement
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Annan publikation (övrigt vetenskapligt/konstnärligt)abstract
- Hierarchically porous, anisotropic, and green carbon aerogels (CAs) prepared from second most abundant and underutilized biopolymer lignin is used together with biobased epoxy resin to prepare green composite materials with superior mechanical properties. Green and facile preparation route involving ice-templating, lyophilization followed by carbonization was followed for the preparation of CAs. Ice-templating cooling rate is an important parameter in determining the porous structure of the CAs and by choosing a slower cooling rate bigger macropores can be achieved which facilitate the capillary infiltration of the epoxy resin through the CA structure. Hence in this study a cooling rate of 5 K/min was used and the CAs were prepared at 1000 ºC from lignin/CNF suspensions containing 3, 5 and 7 wt.% of total solid contents. Composites prepared using these CAs as reinforcements showed interesting morphologies which were analyzed using scanning electron microscopy and X-Ray microtomography. Prepared composites contained a mass fraction of 5 to 9 wt.% of CAs. Composites showed remarkable 72% higher dynamic mechanical properties compared to neat epoxy. Thus, this study introduces new synthesis strategy for carbon composites with completely biobased anisotropic CAs as oriented and strong reinforcements.
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| 10. |
- Thomas, Bony, et al.
(författare)
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Sustainable Carbon Derived from Sulfur-Free Lignins for Functional Electrical and Electrochemical Devices
- 2022
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Ingår i: Nanomaterials. - : MDPI. - 2079-4991. ; 12:20
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Tidskriftsartikel (refereegranskat)abstract
- Technical lignins, kraft, soda, lignoboost, and hydrolysis lignins were used for the production of carbon particles at different carbonization temperatures, 1000 °C and 1400 °C. The results showed that the lignin source and carbonization temperature significantly influenced the carbon quality and microstructure of the carbon particles. Soda lignin carbonized up to 1400 °C showed higher degree of graphitization and exhibited the highest electrical conductivity of 335 S·m−1, which makes it suitable for applications, such as electromagnetic interference shielding and conductive composite based structural energy storage devices. The obtained carbon particles also showed high surface area and hierarchical pore structure. Kraft lignin carbonized up to 1400 °C gives the highest BET surface area of 646 m2 g−1, which makes it a good candidate for electrode materials in energy storage applications. The energy storage application has been validated in a three-electrode set up device, and a specific capacitance of 97.2 F g−1 was obtained at a current density of 0.1 A g−1 while an energy density of 1.1 Wh kg−1 was observed at a power density of 50 W kg−1. These unique characteristics demonstrated the potential of kraft lignin-based carbon particles for electrochemical energy storage applications.
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