| 1. |
- Fenstermacher, M.E., et al.
(författare)
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DIII-D research advancing the physics basis for optimizing the tokamak approach to fusion energy
- 2022
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Ingår i: Nuclear Fusion. - : IOP Publishing. - 0029-5515 .- 1741-4326. ; 62:4
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Tidskriftsartikel (refereegranskat)abstract
- DIII-D physics research addresses critical challenges for the operation of ITER and the next generation of fusion energy devices. This is done through a focus on innovations to provide solutions for high performance long pulse operation, coupled with fundamental plasma physics understanding and model validation, to drive scenario development by integrating high performance core and boundary plasmas. Substantial increases in off-axis current drive efficiency from an innovative top launch system for EC power, and in pressure broadening for Alfven eigenmode control from a co-/counter-I p steerable off-axis neutral beam, all improve the prospects for optimization of future long pulse/steady state high performance tokamak operation. Fundamental studies into the modes that drive the evolution of the pedestal pressure profile and electron vs ion heat flux validate predictive models of pedestal recovery after ELMs. Understanding the physics mechanisms of ELM control and density pumpout by 3D magnetic perturbation fields leads to confident predictions for ITER and future devices. Validated modeling of high-Z shattered pellet injection for disruption mitigation, runaway electron dissipation, and techniques for disruption prediction and avoidance including machine learning, give confidence in handling disruptivity for future devices. For the non-nuclear phase of ITER, two actuators are identified to lower the L-H threshold power in hydrogen plasmas. With this physics understanding and suite of capabilities, a high poloidal beta optimized-core scenario with an internal transport barrier that projects nearly to Q = 10 in ITER at ∼8 MA was coupled to a detached divertor, and a near super H-mode optimized-pedestal scenario with co-I p beam injection was coupled to a radiative divertor. The hybrid core scenario was achieved directly, without the need for anomalous current diffusion, using off-axis current drive actuators. Also, a controller to assess proximity to stability limits and regulate β N in the ITER baseline scenario, based on plasma response to probing 3D fields, was demonstrated. Finally, innovative tokamak operation using a negative triangularity shape showed many attractive features for future pilot plant operation.
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| 2. |
- Kristan, Matej, et al.
(författare)
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The Visual Object Tracking VOT2015 challenge results
- 2015
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Ingår i: Proceedings 2015 IEEE International Conference on Computer Vision Workshops ICCVW 2015. - : IEEE. - 9780769557205 ; , s. 564-586
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Konferensbidrag (refereegranskat)abstract
- The Visual Object Tracking challenge 2015, VOT2015, aims at comparing short-term single-object visual trackers that do not apply pre-learned models of object appearance. Results of 62 trackers are presented. The number of tested trackers makes VOT 2015 the largest benchmark on short-term tracking to date. For each participating tracker, a short description is provided in the appendix. Features of the VOT2015 challenge that go beyond its VOT2014 predecessor are: (i) a new VOT2015 dataset twice as large as in VOT2014 with full annotation of targets by rotated bounding boxes and per-frame attribute, (ii) extensions of the VOT2014 evaluation methodology by introduction of a new performance measure. The dataset, the evaluation kit as well as the results are publicly available at the challenge website(1).
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| 3. |
- Chen, Yuqing, et al.
(författare)
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A review of lithium-ion battery safety concerns : the issues, strategies, and testing standards
- 2021
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Ingår i: Journal of Energy Chemistry. - : Elsevier. - 2095-4956 .- 2096-885X. ; 59, s. 83-99
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Tidskriftsartikel (refereegranskat)abstract
- Efficient and reliable energy storage systems are crucial for our modern society. Lithium-ion batteries (LIBs) with excellent performance are widely used in portable electronics and electric vehicles (EVs), but frequent fires and explosions limit their further and more widespread applications. This review summarizes aspects of LIB safety and discusses the related issues, strategies, and testing standards. Specifically, it begins with a brief introduction to LIB working principles and cell structures, and then provides an overview of the notorious thermal runaway, with an emphasis on the effects of mechanical, electrical, and thermal abuse. The following sections examine strategies for improving cell safety, including approaches through cell chemistry, cooling, and balancing, afterwards describing current safety standards and corresponding tests. The review concludes with insights into potential future developments and the prospects for safer LIBs.
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| 4. |
- Li, Cheng, et al.
(författare)
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Optimal Planning of Community Integrated Energy Station Considering Frequency Regulation Service
- 2021
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Ingår i: Journal of Modern Power Systems and Clean Energy. - : IEEE-INST ELECTRICAL ELECTRONICS ENGINEERS INC. - 2196-5625 .- 2196-5420. ; 9:2, s. 264-273
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Tidskriftsartikel (refereegranskat)abstract
- With the extensive integration of high-penetration renewable energy resources, more fast-response frequency regulation (FR) providers are required to eliminate the impact of uncertainties from loads and distributed generators (DGs) on system security and stability. As a high-quality FR resource, community integrated energy station (CIES) can effectively respond to frequency deviation caused by renewable energy generation, helping to solve the frequency problem of power system. This paper proposes an optimal planning model of CIES considering FR service. First, the model of FR service is established to unify the time scale of FR service and economic operation. Then, an optimal planning model of CIES considering FR service is proposed, with which the revenue of participating in the FR service is obtained under market mechanism. The flexible electricity pricing model is introduced to flatten the peak tie-line power of CIES. Case studies are conducted to analyze the annual cost and the revenue of CIES participating in FR service, which suggest that providing ancillary services can bring potential revenue.
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| 5. |
- Chuang, Zhenju, et al.
(författare)
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Numerical analysis of blade icing influence on the dynamic response of an integrated offshore wind turbine
- 2022
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Ingår i: Ocean Engineering. - : Elsevier BV. - 0029-8018. ; 257
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Tidskriftsartikel (refereegranskat)abstract
- When a wind turbine is working in a cold and humid environment, icing may occur which lead to its performance reduction or even blades fracture. In this paper, a CFD-WTIA (Wind Turbine Integrated Analysis) coupled method is established to analyze the blade icing process and its influence on the overall dynamic performance of an integrated jacket-support offshore wind turbine. Firstly, motions of the blades are calculated by the WTIA method and used as input into CFD. Then, dispersed multi-phase model and melting-solidification model are used to simulate the icing growth phenomenon of three-dimensional blades. The k-ε turbulence model is used to calculate the aerodynamic performance before and after icing. Finally, the aerodynamic results after blade icing are returned to WTIA for integrated dynamic response acquisition. At the same time, the dynamic response of the wind turbine under the combined influence of ice and sea ice is analyzed. Results show that the blade ice-accretion increases linearly along the blade span-wise direction and is mainly concentrated on the leading edge of the blade. Lift and drag coefficients are seen deceased and increased respectively after icing. Power production, generator torque, rotor speed, as well as blade vibration are quantitatively studied. The methodology and findings of this paper can provide a good reference for the safety performance evaluation of an icing offshore wind turbine.
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| 6. |
- Li, Zheng, et al.
(författare)
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A Review of Spatter in Laser Powder Bed Fusion Additive Manufacturing: In Situ Detection, Generation, Effects, and Countermeasures
- 2022
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Ingår i: Micromachines. - : MDPI AG. - 2072-666X. ; 13:8
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Forskningsöversikt (refereegranskat)abstract
- Spatter is an inherent, unpreventable, and undesired phenomenon in laser powder bed fusion (L-PBF) additive manufacturing. Spatter behavior has an intrinsic correlation with the forming quality in L-PBF because it leads to metallurgical defects and the degradation of mechanical properties. This impact becomes more severe in the fabrication of large-sized parts during the multi-laser L-PBF process. Therefore, investigations of spatter generation and countermeasures have become more urgent. Although much research has provided insights into the melt pool, microstructure, and mechanical property, reviews of spatter in L-PBF are still limited. This work reviews the literature on the in situ detection, generation, effects, and countermeasures of spatter in L-PBF. It is expected to pave the way towards a novel generation of highly efficient and intelligent L-PBF systems.
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| 7. |
- Chen, Cheng, et al.
(författare)
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Molecular Engineering of Triphenylamine-Based Non-Fullerene Electron-Transport Materials for Efficient Rigid and Flexible Perovskite Solar Cells
- 2018
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Ingår i: ACS Applied Materials and Interfaces. - : AMER CHEMICAL SOC. - 1944-8244 .- 1944-8252. ; 10:45, s. 38970-38977
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Tidskriftsartikel (refereegranskat)abstract
- There has been a growing interest in the design and synthesis of non-fullerene electron transport materials (ETMs) for perovskite solar cells (PSCs), which may overcome the drawbacks of traditional fullerene derivatives. In this work, a novel donor-acceptor (D-A) structured ETM termed TPA-3CN is presented by molecular engineering of triphenylamine (TPA) as the donor group and (3-cyano-4,5,5-trimethyl-2(5H)-furanylidene) malononitrile as the acceptor group. To further improve the electron mobility and conductivity and achieve excellent photovoltaic performance, a solution processable n-type dopant is introduced during the ETM spin-coating step. After device optimization, PSCs based on the doped TPA-3CN exhibit an impressive power conversion efficiency (PCE) of 19.2% with a negligible hysteresis. Benefitting from the low temperature and good solution processability of ETM TPA-3CN, it was further applied in flexible inverted PSCs and an impressive PCE of 13.2% was achieved, which is among the highest values reported for inverted flexible fullerene-free PSCs.
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| 8. |
- Ding, C., et al.
(författare)
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Study on fracture of the fibrous monolith cemented carbide
- 2013
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Ingår i: Advanced Materials Research. - 1662-8985 .- 1022-6680. ; 815, s. 43-47
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Konferensbidrag (refereegranskat)abstract
- A fibrous monolith cemented carbide with WC-6%Co as cell and WC-20%Co as cell boundaries was produced through hot co-extrusion process in this paper. The density, hardness, transverse rupture strength (TRS) and fracture toughness (KIc) of the fibrous monolith cemented carbide were tested, and the fracture and crack propagation were observed by metalloscope and Scanning Electron Microscope. The result shows fibrous monolith structure design could effectively improve the TRS and the KIc of WC/Co cemented carbide without a significant decrease of hardness. It is the reason of high transverse rupture strength and fracture toughness that WC-20%Co can absorb more fracture energy in order to slow, prevent, or deflect crack propagation, proved by metalloscope and scanning electron microscope.
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| 9. |
- Jian, Wang, et al.
(författare)
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A PSO-Based Layout Method for GNSS Pseudolite System
- 2017
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Ingår i: Proceedings of the 2017 International Conference on Information Technology. - New York, NY, USA : ACM. - 9781450363518 ; , s. 313-317
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Konferensbidrag (refereegranskat)abstract
- In order to improve the user positioning accuracy in GNSS (Global Navigation Satellite System) pseudolite system, we propose a PSO (Particle Swarm Optimization)-based method to optimize the pseudolite layout in this paper. In detail, given the pseudolite layout information, we calculate the system GDOP (Geometric Dilution of Precision) and then minimize it by using a PSO-based algorithm with N particles. Here the first particle indicates the classical layout under the given scenario and the other particles separately represent N-1 randomly generated layouts. In each iteration of our PSO-based algorithm, these particles move to a direction to reduce the GDOP value. After several iterations, the GDOP value can be minimized and the optimal pseudolite layout is found out as well. To evaluate the merits of our method, we perform some experiments. The experimental results show that compared to the classical pseudolite layout, our method can reduce the GDOP by 13.4%. This, with no doubt, improves the user positioning accuracy. For example, when the pseudo-range error is about 1%, the user positioning accuracy in our optimized layout can be improved by 12.4% against the classical layout.
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| 10. |
- Liu, X., et al.
(författare)
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Microstructure and mechanical properties of sintered fibrous monolith cemented carbide
- 2013
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Ingår i: Advanced Materials Research. - 1662-8985 .- 1022-6680. ; 815, s. 233-239
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Konferensbidrag (refereegranskat)abstract
- A fibrous monolith cemented carbide with WC-6Co as cell and WC-20Co as cell boundaries was produced through hot co-extrusion process in this paper. The density, hardness, bending strength and fracture toughness of the fibrous monolith cemented carbide were tested, and the fracture and crack propagation were observed by metalloscope and SEM. The results showed that the bending strength and fracture toughness of the fibrous monolith cemented carbides was remarkably improved 71.91% and 45.7% respectively, while the hardness was slightly decreased 1% compared with WC-6Co composites. It is the reason that the tougher shell WC-20Co with higher bending strength and fracture toughness can absorb more fracture energy, which can slow down and prevent the crack propagating from brittle core WC-6Co.
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