| 1. |
- Unsalan, Ozan, et al.
(författare)
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The Sariçiçek howardite fall in Turkey : Source crater of HED meteorites on Vesta and impact risk of Vestoids
- 2019
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Ingår i: Meteoritics and Planetary Science. - Hoboken : John Wiley & Sons. - 1086-9379 .- 1945-5100. ; 54:5, s. 953-1008
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Tidskriftsartikel (refereegranskat)abstract
- The Sariçiçek howardite meteorite shower consisting of 343 documented stones occurred on September 2, 2015 in Turkey and is the first documented howardite fall. Cosmogenic isotopes show that Sariçiçek experienced a complex cosmic‐ray exposure history, exposed during ~12–14 Ma in a regolith near the surface of a parent asteroid, and that an ~1 m sized meteoroid was launched by an impact 22 ± 2 Ma ago to Earth (as did one‐third of all HED meteorites). SIMS dating of zircon and baddeleyite yielded 4550.4 ± 2.5 Ma and 4553 ± 8.8 Ma crystallization ages for the basaltic magma clasts. The apatite U‐Pb age of 4525 ± 17 Ma, K‐Ar age of ~3.9 Ga, and the U,Th‐He ages of 1.8 ± 0.7 and 2.6 ± 0.3 Ga are interpreted to represent thermal metamorphic and impact‐related resetting ages, respectively. Petrographic; geochemical; and O‐, Cr‐, and Ti‐isotopic studies confirm that Sariçiçek belongs to the normal clan of HED meteorites. Petrographic observations and analysis of organic material indicate a small portion of carbonaceous chondrite material in the Sariçiçek regolith and organic contamination of the meteorite after a few days on soil. Video observations of the fall show an atmospheric entry at 17.3 ± 0.8 km s−1 from NW; fragmentations at 37, 33, 31, and 27 km altitude; and provide a pre‐atmospheric orbit that is the first dynamical link between the normal HED meteorite clan and the inner Main Belt. Spectral data indicate the similarity of Sariçiçek with the Vesta asteroid family (V‐class) spectra, a group of asteroids stretching to delivery resonances, which includes (4) Vesta. Dynamical modeling of meteoroid delivery to Earth shows that the complete disruption of a ~1 km sized Vesta family asteroid or a ~10 km sized impact crater on Vesta is required to provide sufficient meteoroids ≤4 m in size to account for the influx of meteorites from this HED clan. The 16.7 km diameter Antionia impact crater on Vesta was formed on terrain of the same age as given by the 4He retention age of Sariçiçek. Lunar scaling for crater production to crater counts of its ejecta blanket show it was formed ~22 Ma ago.
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| 2. |
- Wei, Xinshui, et al.
(författare)
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Delay-aware Rate Adjusting Scheme in Higher Speed Passive Optical Networks
- 2022
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Ingår i: Asia Communications and Photonics Conference, ACP. - 2162-108X. ; 2022-November, s. 1271-1274
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Konferensbidrag (refereegranskat)abstract
- Flexible rate is a new desirable operational feature of next-generation higher speed passive optical networks (e.g., ITU-50G PON). In this context, this paper proposes a delay-aware rate adjusting scheme, in which the line rate can be adjusted following the traffic load varying to save energy without degrading delay performance. Simulation results show that the proposed scheme has a similar performance with the benchmark in the aspect of energy saving, while the delay performance of time-sensitive services can be improved significantly, which can be up to 36%.
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| 3. |
- Chen, Haiyang, et al.
(författare)
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A guest-assisted molecular-organization approach for >17% efficiency organic solar cells using environmentally friendly solvents
- 2021
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Ingår i: Nature Energy. - : NATURE PORTFOLIO. - 2058-7546. ; 6:11, s. 1045-1053
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Tidskriftsartikel (refereegranskat)abstract
- The power conversion efficiencies (PCEs) of laboratory-sized organic solar cells (OSCs), usually processed from low-boiling-point and toxic solvents, have reached high values of over 18%. However, there is usually a notable drop of the PCEs when green solvents are used, limiting practical development of OSCs. Herein, we obtain certificated PCEs over 17% in OSCs processed from a green solvent paraxylene (PX) by a guest-assisted assembly strategy, where a third component (guest) is employed to manipulate the molecular interaction of the binary blend. In addition, the high-boiling-point green solvent PX also enables us to deposit a uniform large-area module (36 cm(2)) with a high efficiency of over 14%. The strong molecular interaction between the host and guest molecules also enhances the operational stability of the devices. Our guest-assisted assembly strategy provides a unique approach to develop large-area and high-efficiency OSCs processed from green solvents, paving the way for industrial development of OSCs. Organic solar cells processed from green solvents are easier to implement in manufacturing yet their efficiency is low. Chen et al. devise a guest molecule to improve the molecular packing, enabling devices with over 17% efficiency.
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| 4. |
- Li, Xiaowei, 1986, et al.
(författare)
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Metabolic network remodelling enhances yeast’s fitness on xylose using aerobic glycolysis
- 2021
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Ingår i: Nature Catalysis. - : Springer Science and Business Media LLC. - 2520-1158. ; 4:9, s. 783-796
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Tidskriftsartikel (refereegranskat)abstract
- The reprogramming of metabolism in response to switching the carbon source from glucose to non-preferred carbon sources is well-studied for yeast. However, understanding how metabolic networks respond to utilize a non-natural carbon source such as xylose is limited due to the incomplete knowledge of cellular response mechanisms. Here we applied a combination of metabolic engineering, systems biology and adaptive laboratory evolution to gain insights into how yeast can perform a global rewiring of cellular processes to efficiently accompany metabolic transitions. Through metabolic engineering, we substantially enhanced the cell growth on xylose after the growth on glucose. Transcriptome analysis of the engineered strains demonstrated that multiple pathways were involved in the cellular reprogramming. Through genome resequencing of the evolved strains and reverse engineering, we further identified that SWI/SNF chromatin remodelling, osmotic response and aldehyde reductase were responsible for the improved growth. Combined, our analysis showed that glycerol-3-phosphate and xylitol serve as two key metabolites that affect cellular adaptation to growth on xylose. [Figure not available: see fulltext.].
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| 5. |
- Lu, Xiang, et al.
(författare)
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Fine-Granularity Bandwidth Allocation for Diverse Low-Latency Services in Higher-Speed Passive Optical Networks
- 2022
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Ingår i: Asia Communications and Photonics Conference, ACP. - 2162-108X. ; 2022-November, s. 1135-1139
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Konferensbidrag (refereegranskat)abstract
- To support time-sensitive (TS) services with differential low latency requirements, this paper proposes a fine-granularity bandwidth allocation algorithm (FgBA) in higher speed passive optical networks (i.e., ITU-T 50G PON). Simulation results show that FgBA can meet the diverse low latency requirements of TS services regardless of traffic load.
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| 6. |
- Pucilowski, Mateusz, et al.
(författare)
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Comparison of kinetic mechanisms for numerical simulation of methanol combustion in dici heavy-duty engine
- 2019
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Ingår i: Technical Paper - WCX SAE World Congress Experience. - 400 Commonwealth Drive, Warrendale, PA, United States : SAE International. - 0148-7191. ; 2019
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Konferensbidrag (refereegranskat)abstract
- The combustion process in a homogeneous charge compression ignition (HCCI) engine is mainly governed by ignition wave propagation. The in-cylinder pressure, heat release rate, and the emission characteristics are thus largely driven by the chemical kinetics of the fuel. As a result, CFD simulation of such combustion process is very sensitive to the employed reaction mechanism, which model the real chemical kinetics of the fuel. In order to perform engine simulation with a range of operating conditions and cylinder-piston geometry for the design and optimization purpose, it is essential to have a chemical kinetic mechanism that is both accurate and computational inexpensive. In this paper, we report on the evaluation of several chemical kinetic mechanisms for methanol combustion, including large mechanisms and skeletal/reduced mechanisms. These mechanisms are evaluated in terms of homogeneous ignition delay time, laminar flame speed, and multi-phase simulations of HCCI heavy-duty engine. The results are compared with experimental data and evaluated in terms of the accuracy and computational cost. It was found that scattering of ignition delay time predicted from different chemical kinetic mechanisms reported in the literature under homogeneous mixture ignition conditions give rise to a high sensitivity of the engine in-cylinder pressure prediction to the selected mechanism.
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| 7. |
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| 8. |
- Cao, Yuan, et al.
(författare)
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Multi-Tenant Provisioning for Quantum Key Distribution Networks With Heuristics and Reinforcement Learning : A Comparative Study
- 2020
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Ingår i: IEEE Transactions on Network and Service Management. - : Institute of Electrical and Electronics Engineers (IEEE). - 1932-4537. ; 17:2, s. 946-957
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Tidskriftsartikel (refereegranskat)abstract
- Quantum key distribution (QKD) networks are potential to be widely deployed in the immediate future to provide long-term security for data communications. Given the high price and complexity, multi-tenancy has become a cost-effective pattern for QKD network operations. In this work, we concentrate on addressing the online multi-tenant provisioning (On-MTP) problem for QKD networks, where multiple tenant requests (TRs) arrive dynamically. On-MTP involves scheduling multiple TRs and assigning non-reusable secret keys derived from a QKD network to multiple TRs, where each TR can be regarded as a high-security-demand organization with the dedicated secret-key demand. The quantum key pools (QKPs) are constructed over QKD network infrastructure to improve management efficiency for secret keys. We model the secret-key resources for QKPs and the secret-key demands of TRs using distinct images. To realize efficient On-MTP, we perform a comparative study of heuristics and reinforcement learning (RL) based On-MTP solutions, where three heuristics (i.e., random, fit, and best-fit based On-MTP algorithms) are presented and a RL framework is introduced to realize automatic training of an On-MTP algorithm. The comparative results indicate that with sufficient training iterations the RL-based On-MTP algorithm significantly outperforms the presented heuristics in terms of tenant-request blocking probability and secret-key resource utilization.
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| 9. |
- Niu, Jiqiang, et al.
(författare)
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Aerodynamic simulation of effects of one- and two-side windbreak walls on a moving train running on a double track railway line subjected to strong crosswind
- 2022
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Ingår i: Journal of Wind Engineering and Industrial Aerodynamics. - : Elsevier BV. - 0167-6105. ; 221
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Tidskriftsartikel (refereegranskat)abstract
- High-speed railway lines are widely distributed worldwide. The surrounding wind environment of such railway lines is complex, which significantly affects the safety of high-speed train operations. Using a combination of the computational fluid dynamics method of improved delayed detached eddy simulation and sliding grid technology, the effects of one- and two-side windbreak walls on the unsteady aerodynamic performance of a high-speed train running under a crosswind on a double-track railway line with an embankment and the flow-field characteristics around the train were systematically studied. The grid independence and numerical methods used in this study were verified. The results showed that when the windbreak wall was absent, the aerodynamic performance of the train running on the upstream railway line was the poorest, while the train running on the downstream railway line exhibited large aerodynamic fluctuations. The windbreak wall significantly reduced the aerodynamic force and its fluctuation; the one- and two-side windbreak walls had different effects on the unsteady aerodynamic performance of trains running on the upstream and downstream railway lines under a crosswind. The one-side windbreak wall could restrain the aerodynamic fluctuation of the train more and is thus preferred from the perspective of construction effort and cost.
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| 10. |
- Pereira, Rui, 1986, et al.
(författare)
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Metabolic Engineering of Yeast
- 2021
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Ingår i: Metabolic Engineering: Concepts and Applications: Volume 13a and 13b. - : Wiley. ; 13, s. 689-733
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Bokkapitel (övrigt vetenskapligt/konstnärligt)abstract
- This chapter focuses on a few examples that can serve as illustrations of how powerful yeast metabolic engineering stands today. Yeast, especially S. cerevisiae, plays an essential role in bioethanol production. Rapid ethanol production by yeast cells makes the fermentation process less susceptible to contamination. Higher alcohols are attractive due to some advantages compared with bioethanol, such as higher energy density, better blending into gasoline, higher octane value, lower hygroscopicity, and less corrosivity. The ethanol production process in the industry is mainly achieved through simultaneous saccharification and fermentation. Production of insulin, by volume the largest pharmaceutical protein produced, has paved the way for a wide use of S. cerevisiae for production of recombinant proteins. Virus like particles are proteins of virus capsid, which are produced by recombinant DNA technology and are important for the development of viral vaccines as they can self-assemble and display similar immunogenic properties as native viruses.
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