| 1. |
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| 2. |
- Chen, Yifeng, et al.
(författare)
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Experimental characterization and micromechanical modeling of damage-induced permeability variation in Beishan granite
- 2014
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Ingår i: International Journal of Rock Mechanics And Mining Sciences. - : Elsevier BV. - 1365-1609 .- 1873-4545. ; 71, s. 64-76
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Tidskriftsartikel (refereegranskat)abstract
- Triaxial compression tests with measurements of permeability were performed on core granite samples taken at 450-550 m depth from the Beishan area in Gansu Province, a potential site for China's high-level radioactive waste (HLW) disposal. Corresponding to the distinct features in the stress-strain behaviors, the permeability of the Beishan granite was found to evolve with a clear permeability decrease in the initial microcrack closure region, a constant permeability value in the elastic region and a dramatic permeability increase in the crack growth region. The permeability increases by up to and over two orders of magnitude as deviatoric stress increases up to sample failure; but at a given deviatoric stress, the permeability reduces remarkably with the increase of confining pressure. An empirical upper bound permeability model was presented by relating the mechanisms involved in the microstructure alteration to the permeability change, and the experimental results were well simulated by the proposed model. Combined with field geological characterization and numerical simulation, the implications of the experimental results for China's HLW disposal were discussed.
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| 3. |
- Cheng, Benyuan, et al.
(författare)
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Pressure-induced metallization and amorphization in VO2(A) nanorods
- 2016
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Ingår i: Physical Review B. Condensed Matter and Materials Physics. - 1098-0121 .- 1550-235X. ; 93:18
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Tidskriftsartikel (refereegranskat)abstract
- A metallic state enabled by the metal-insulator transition (MIT) in single crystal VO2(A) nanorods is demonstrated, which provides important physical foundation in experimental understanding of MIT in VO2. The observed tetragonal metallic state at ∼28 GPa should be interpreted as a distinct metastable state, while increasing pressure to ∼32 GPa, it transforms into a metallic amorphous state completely. The metallization is due to V 3d orbital electrons delocalization, and the amorphization is attributed to the unique variation of V-O-V bond angle. A metallic amorphous VO2 state is found under pressure, which is beneficial to explore the phase diagram of VO2. Furthermore, this work proves the occurrence of both the metallization and amorphization in octahedrally coordinated materials.
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| 4. |
- Kristan, Matej, et al.
(författare)
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The Sixth Visual Object Tracking VOT2018 Challenge Results
- 2019
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Ingår i: Computer Vision – ECCV 2018 Workshops. - Cham : Springer Publishing Company. - 9783030110086 - 9783030110093 ; , s. 3-53
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Konferensbidrag (refereegranskat)abstract
- The Visual Object Tracking challenge VOT2018 is the sixth annual tracker benchmarking activity organized by the VOT initiative. Results of over eighty trackers are presented; many are state-of-the-art trackers published at major computer vision conferences or in journals in the recent years. The evaluation included the standard VOT and other popular methodologies for short-term tracking analysis and a “real-time” experiment simulating a situation where a tracker processes images as if provided by a continuously running sensor. A long-term tracking subchallenge has been introduced to the set of standard VOT sub-challenges. The new subchallenge focuses on long-term tracking properties, namely coping with target disappearance and reappearance. A new dataset has been compiled and a performance evaluation methodology that focuses on long-term tracking capabilities has been adopted. The VOT toolkit has been updated to support both standard short-term and the new long-term tracking subchallenges. Performance of the tested trackers typically by far exceeds standard baselines. The source code for most of the trackers is publicly available from the VOT page. The dataset, the evaluation kit and the results are publicly available at the challenge website (http://votchallenge.net).
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| 5. |
- Lei, Jian, et al.
(författare)
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Altered expression of aggrecan, FAM20B, B3GALT6, and EXTL2 in patients with osteoarthritis and Kashin-Beck disease
- 2021
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Ingår i: Cartilage. - : Sage Publications. - 1947-6035 .- 1947-6043. ; 13:Suppl 1, s. 818S-828S
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Tidskriftsartikel (refereegranskat)abstract
- OBJECTIVE: The objective of this study was to investigate the expression of enzymes involved in synthesis and modification of chondroitin sulfate (CS) in knee cartilage tissue of patients with osteoarthritis (OA) and Kashin-Beck disease (KBD).METHODS: The knee articular cartilage samples were obtained from 18 age- and gender-matched donors with 6 each in KBD, OA, and control groups. Hematoxylin and eosin (HE) staining, toluidine blue (TB) staining, and immunohistochemical (IHC) staining were performed to estimate the expression level and localization of aggrecan, along with FAM20B, GalT-II, and EXTL2, which are associated with CS synthesis and modification. Rank-based analyses of variance test was used for the multiple comparisons of discrepancy in the positive staining rate among the 3 groups.RESULTS: In HE and TB staining results, damaged morphology, decreased chondrocyte numbers and proteoglycans were observed in OA and KBD groups compared with the control group. In line with these trends, the positive staining rates of aggrecan were lower in KBD and OA groups than in the control group. Meanwhile, the positive staining rates of CS chain modifying enzymes FAM20B, GalT-II, and EXTL2 decreased in OA and KBD groups.CONCLUSIONS: In conclusion, it was demonstrated that altered expression of CS chain modifying enzymes in OA and KBD groups influenced the synthesis procession of CS and could contribute to the damage of cartilage. Further investigation of these enzymes can provide new theoretical and experimental targets for OA and KBD pathogenesis studies.
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| 6. |
- Liu, Dedi, et al.
(författare)
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Pressure-induced phase transitions of C70 nanotubes
- 2011
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Ingår i: The Journal of Physical Chemistry C. - : American Chemical Society. - 1932-7447 .- 1932-7455. ; 115:18, s. 8918-8922
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Tidskriftsartikel (refereegranskat)abstract
- Single crystalline C70 nanotubes having a face-centered-cubic (fcc) structure with diameters on a nanometer scale were synthesized by a facile solution method. In situ high pressure Raman spectroscopy and X-ray diffraction have been employed to study the structural stability and phase transitions of the pristine sample. We show that the molecular orientation-related phase transition from the fcc structure to a rhombohedral structure occurs at about 1.5 GPa, which is 1 GPa higher than in bulk C70. Also, the C70 molecules themselves are more stable in the nanotubes than in bulk crystals, manifested by a partial amorphization at 20 GPa. The crystal structure of C70 nanotubes could partially return to the initial structure after a pressure cycle above 30.8 GPa, and the C70 molecules were intact up to 43 GPa. The bulk modulus of C70 nanotubes is measured to be 50 GPa, which is twice larger than that of bulk C70.
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| 7. |
- Pi, Xuehui, et al.
(författare)
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Mapping global lake dynamics reveals the emerging roles of small lakes
- 2022
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Ingår i: Nature Communications. - : Springer Science and Business Media LLC. - 2041-1723. ; 13:1
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Tidskriftsartikel (refereegranskat)abstract
- Lakes are important natural resources and carbon gas emitters and are undergoing rapid changes worldwide in response to climate change and human activities. A detailed global characterization of lakes and their long-term dynamics does not exist, which is however crucial for evaluating the associated impacts on water availability and carbon emissions. Here, we map 3.4 million lakes on a global scale, including their explicit maximum extents and probability-weighted area changes over the past four decades. From the beginning period (1984–1999) to the end (2010–2019), the lake area increased across all six continents analyzed, with a net change of +46,278 km2, and 56% of the expansion was attributed to reservoirs. Interestingly, although small lakes (<1 km2) accounted for just 15% of the global lake area, they dominated the variability in total lake size in half of the global inland lake regions. The identified lake area increase over time led to higher lacustrine carbon emissions, mostly attributed to small lakes. Our findings illustrate the emerging roles of small lakes in regulating not only local inland water variability, but also the global trends of surface water extent and carbon emissions.
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| 8. |
- Posey, Victoria A., et al.
(författare)
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Two-dimensional heavy fermions in the van der Waals metal CeSiI
- 2024
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Ingår i: Nature. - : Springer Nature. - 0028-0836 .- 1476-4687. ; 625:7995, s. 483-488
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Tidskriftsartikel (refereegranskat)abstract
- Heavy-fermion metals are prototype systems for observing emergent quantum phases driven by electronic interactions1-6. A long-standing aspiration is the dimensional reduction of these materials to exert control over their quantum phases7-11, which remains a significant challenge because traditional intermetallic heavy-fermion compounds have three-dimensional atomic and electronic structures. Here we report comprehensive thermodynamic and spectroscopic evidence of an antiferromagnetically ordered heavy-fermion ground state in CeSiI, an intermetallic comprising two-dimensional (2D) metallic sheets held together by weak interlayer van der Waals (vdW) interactions. Owing to its vdW nature, CeSiI has a quasi-2D electronic structure, and we can control its physical dimension through exfoliation. The emergence of coherent hybridization of f and conduction electrons at low temperature is supported by the temperature evolution of angle-resolved photoemission and scanning tunnelling spectra near the Fermi level and by heat capacity measurements. Electrical transport measurements on few-layer flakes reveal heavy-fermion behaviour and magnetic order down to the ultra-thin regime. Our work establishes CeSiI and related materials as a unique platform for studying dimensionally confined heavy fermions in bulk crystals and employing 2D device fabrication techniques and vdW heterostructures12 to manipulate the interplay between Kondo screening, magnetic order and proximity effects.
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| 9. |
- Song, Lu, et al.
(författare)
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Unique redox properties in defective CeO2-x nanocrystallines synthesized by laser melting
- 2018
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Ingår i: Science China Materials. - : Springer Science and Business Media LLC. - 2095-8226 .- 2199-4501. ; 61:8, s. 1078-1084
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Tidskriftsartikel (refereegranskat)abstract
- Defects in cerium oxide, especially oxygen vacancies, play an essential role in its versatile applications and are efficiently preserved at ambient conditions in a non-equilibrium process. Herein, defective CeO2-x with heterogeneous structure was synthesized by high-energy laser melting, where a large amount of oxygen vacancies and Ce3+ could be introduced, leading to improved visible light absorption, narrowed bandgap and room temperature ferromagnetism. Moreover, this laser melted CeO2-x exhibits significantly enhanced low-temperature oxidation behaviors than the counterpart prepared by normal hydrogen-reduction. This unique redox performance could be attributed to the intragranular diffusion at the boundaries of assembled nanocrystallites. This method paves a new way for introducing unique multi-functions in oxide ceramics.
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| 10. |
- Tao, Ran, et al.
(författare)
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Optimizing crop management with reinforcement learning and imitation learning
- 2023
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Ingår i: Proceedings of the 32nd International Joint Conference on Artificial Intelligence, IJCAI 2023. - : International Joint Conferences on Artificial Intelligence. ; , s. 6228-6236
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Konferensbidrag (refereegranskat)abstract
- Crop management has a significant impact on crop yield, economic profit, and the environment. Although management guidelines exist, finding the optimal management practices is challenging. Previous work used reinforcement learning (RL) and crop simulators to solve the problem, but the trained policies either have limited performance or are not deployable in the real world. In this paper, we present an intelligent crop management system that optimizes nitrogen fertilization and irrigation simultaneously via RL, imitation learning (IL), and crop simulations using the Decision Support System for Agrotechnology Transfer (DSSAT). We first use deep RL, in particular, deep Q-network, to train management policies that require a large number of state variables from the simulator as observations (denoted as full observation). We then invoke IL to train management policies that only need a few state variables that can be easily obtained or measured in the real world (denoted as partial observation) by mimicking the actions of the RL policies trained under full observation. Simulation experiments using the maize crop in Florida (US) and Zaragoza (Spain) demonstrate that the trained policies from both RL and IL techniques achieved more than 45% improvement in economic profit while causing less environmental impact compared with a baseline method. Most importantly, the IL-trained management policies are directly deployable in the real world as they use readily available information.
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| 11. |
- Tao, Ran, et al.
(författare)
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Optimizing Crop Management with Reinforcement Learning and Imitation Learning
- 2023
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Ingår i: 22nd International Conference on Autonomous Agents and Multiagent Systems, AAMAS 2023. - : International Foundation for Autonomous Agents and Multiagent Systems (IFAAMAS). ; , s. 2511-2513
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Konferensbidrag (refereegranskat)abstract
- To increase crop yield while minimizing environmental impact, we present an intelligent crop management system that optimizes nitrogen fertilization and irrigation simultaneously via reinforcement learning (RL), imitation learning (IL), and crop simulations using DSSAT. We first use deep RL to train management policies that require a large number of state variables from the simulator as observations (denoted as full observation). We then invoke IL to train management policies that only need a limited number of variables that are measurable in the real world (denoted as partial observation) by mimicking the actions of the RL-trained policies under full observation. Simulation experiments using maize in Florida demonstrate that our trained policies under both full and partial observations achieve better outcomes than a baseline policy. Most importantly, the IL-trained management policies are directly deployable in the real world as they use readily available information.
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| 12. |
- Tsuneto, Makoto, et al.
(författare)
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Anomalous thermal effect in ZrTe5 observed via photothermal measurements
- 2024
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Ingår i: Physical Review Applied. - : American Physical Society (APS). - 2331-7019. ; 21:3
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Tidskriftsartikel (refereegranskat)abstract
- In this study, we explore the magnetothermoelectric power (MTP) of ZrTe5, a canonical Dirac semimetal, through a photothermal technique. Unlike conventional thermoelectric studies that rely on on-chip heaters and are limited by fabrication processes, especially for stress-sensitive materials, our approach utilizes photothermal effects to induce temperature gradients. Our experiments, applying a magnetic field approximately parallel and transverse to the photocurrent detection direction, reveal that the photothermal method efficiently and reliably extracts both diagonal and off-diagonal components of the thermoelectric coefficient of ZrTe5. We observe that the longitudinal MTP reproduces features previously reported in thermal transport studies, while the photoinduced transverse MTP confirms the anomalous Nernst effect. This photothermal measurement technique opens avenues for investigating transport properties in a wide range of quantum materials, in both three-dimensional and two-dimensional systems.
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| 13. |
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| 14. |
- Zhang, Lei, et al.
(författare)
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Discovery of a radio jet in the Cloverleaf quasar at z = 2.56
- 2023
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Ingår i: Monthly Notices of the Royal Astronomical Society. - 0035-8711 .- 1365-2966. ; 524:3, s. 3671-3682
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Tidskriftsartikel (refereegranskat)abstract
- The fast growth of supermassive black holes and their feedback to the host galaxies play an important role in regulating the evolution of galaxies, especially in the early Universe. However, due to cosmological dimming and the limited angular resolution of most observations, it is difficult to resolve the feedback from the active galactic nuclei (AGNs) to their host galaxies. Gravitational lensing, for its magnification, provides a powerful tool to spatially differentiate emission originating from AGN and host galaxy at high-redshifts. Here, we report a discovery of a jet-like radio structure in a strongly lensed starburst quasar, H1413+117 or Cloverleaf at redshift z = 2.56, based on observational data at optical, submillimetre, and radio wavelengths. With both parametric and non-parametric lens models and with reconstructed images in the source plane, we find a well-separated, kpc-scaled, single-sided radio jet located at projected to the north-west of the host galaxy in the source plane. This could indicate the co-existence of feedback from the AGN by both wind and jet in the Cloverleaf quasar.
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| 15. |
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- 2019
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Tidskriftsartikel (refereegranskat)
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