| 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. |
- Jacobsson, T. Jesper, 1984-, et al.
(författare)
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An open-access database and analysis tool for perovskite solar cells based on the FAIR data principles
- 2022
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Ingår i: Nature Energy. - : Springer Nature. - 2058-7546. ; 7:1, s. 107-115
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Tidskriftsartikel (refereegranskat)abstract
- Large datasets are now ubiquitous as technology enables higher-throughput experiments, but rarely can a research field truly benefit from the research data generated due to inconsistent formatting, undocumented storage or improper dissemination. Here we extract all the meaningful device data from peer-reviewed papers on metal-halide perovskite solar cells published so far and make them available in a database. We collect data from over 42,400 photovoltaic devices with up to 100 parameters per device. We then develop open-source and accessible procedures to analyse the data, providing examples of insights that can be gleaned from the analysis of a large dataset. The database, graphics and analysis tools are made available to the community and will continue to evolve as an open-source initiative. This approach of extensively capturing the progress of an entire field, including sorting, interactive exploration and graphical representation of the data, will be applicable to many fields in materials science, engineering and biosciences.
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| 3. |
- Fu, Kai, et al.
(författare)
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Kinetic Monte Carlo study of metal organic chemical vapor deposition growth dynamics of GaN thin film at microscopic level
- 2008
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Ingår i: Journal of Applied Physics. - : AIP Publishing. - 0021-8979 .- 1089-7550. ; 103:10, s. 103524-
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Tidskriftsartikel (refereegranskat)abstract
- Group III nitrides, especially gallium nitride (GaN), have many applications. The materials are usually grown by metal organic chemical vapor deposition (MOCVD) technology. By combining the computational fluid dynamics and kinetic Monte Carlo method, we present a multiscale modeling of fluid dynamics, thermodynamics, and molecular dynamics to study the chemical and physical growth process of GaN in a standard MOCVD reactor, which shows a general agreement with experimental results. The theoretical model thus provides us with a fundamental guideline for optimizing GaN MOCVD growth at the microscopic level.
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| 4. |
- Rieth, M., et al.
(författare)
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Review on the EFDA programme on tungsten materials technology and science
- 2011
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Ingår i: Journal of Nuclear Materials. - : Elsevier BV. - 0022-3115 .- 1873-4820. ; 417:1-3, s. 463-467
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Tidskriftsartikel (refereegranskat)abstract
- All the recent DEMO design studies for helium cooled divertors utilize tungsten materials and alloys, mainly due to their high temperature strength, good thermal conductivity, low erosion, and comparably low activation under neutron irradiation. The long-term objective of the EFDA fusion materials programme is to develop structural as well as armor materials in combination with the necessary production and fabrication technologies for future divertor concepts. The programmatic roadmap is structured into four engineering research lines which comprise fabrication process development, structural material development, armor material optimization, and irradiation performance testing, which are complemented by a fundamental research programme on "Materials Science and Modeling". This paper presents the current research status of the EFDA experimental and testing investigations, and gives a detailed overview of the latest results on fabrication, joining, high heat flux testing, plasticity, modeling, and validation experiments.
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| 5. |
- Chi, Chaodan, et al.
(författare)
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Si-based InGaAs photodetectors on heterogeneous integrated substrate
- 2021
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Ingår i: Science China: Physics, Mechanics and Astronomy. - : Springer Science and Business Media LLC. - 1674-7348 .- 1869-1927. ; 64:6
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Tidskriftsartikel (refereegranskat)abstract
- In this paper, InGaAs p-i-n photodetectors (PDs) on an InP/SiO2/Si (InPOI) substrate fabricated by ion-slicing technology are demonstrated and compared with the identical device on a commercial InP substrate. The quality of epitaxial layers on the InPOI substrate is similar to that on the InP substrate. The photo responsivities of both devices measured at 1.55 µm are comparable, which are about 0.808–0.828 A W−1. Although the dark current of PD on the InPOI substrate is twice as high as that of PD on the InP substrate at 300 K, the peak detectivities of both PDs are comparable. In general, the overall performance of the InPOI-based PD is comparable to the InP-based PD, demonstrating that the ion-slicing technology is a promising route to enable the high-quality Si-based InP platform for the full photonic integration on a Si substrate.
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| 6. |
- Lin, H., et al.
(författare)
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Characteristics of electric vehicle charging demand at multiple types of location - Application of an agent-based trip chain model
- 2019
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Ingår i: Energy. - : Elsevier Ltd. - 0360-5442 .- 1873-6785. ; 188
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Tidskriftsartikel (refereegranskat)abstract
- This paper developed an agent-based trip chain model (ABTCM) to study the distribution of electric vehicles (EVs) charging demand and its dynamic characteristics, including flexibility and uncertainty, at different types of location. Key parameters affecting charging demand include charging strategies, i.e. uncontrolled charging (UC) and off-peak charging (OPC), and EV supply equipment, including three levels of charging equipment. The results indicate that the distributions of charging demand are similar as the travel patterns, featured by traffic flow at each location. A discrete peak effect was found in revealing the relation between traffic flow and charging demand, and it results in the smallest equivalent daily charging demand and peak load at public locations. EV charging and vehicle-to-grid (V2G) flexibility were examined by instantaneous adjustable power and accumulative adjustable amount of electricity. The EVs at home locations have the largest charging and V2G flexibility under the UC strategy, except for a period of regular working time. The V2G flexibility at work and public locations is generally larger than charging flexibility. Due to the fast charging application, the uncertainties of charging demand at public locations are the highest in all locations. In addition, the OPC strategy mitigates the uncertainty of charging demand.
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| 7. |
- Delsing, Per, 1959, et al.
(författare)
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The 2019 surface acoustic waves roadmap
- 2019
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Ingår i: Journal of Physics D: Applied Physics. - : IOP Publishing. - 1361-6463 .- 0022-3727. ; 52:35
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Forskningsöversikt (refereegranskat)abstract
- Today, surface acoustic waves (SAWs) and bulk acoustic waves are already two of the very few phononic technologies of industrial relevance and can been found in a myriad of devices employing these nanoscale earthquakes on a chip. Acoustic radio frequency filters, for instance, are integral parts of wireless devices. SAWs in particular find applications in life sciences and microfluidics for sensing and mixing of tiny amounts of liquids. In addition to this continuously growing number of applications, SAWs are ideally suited to probe and control elementary excitations in condensed matter at the limit of single quantum excitations. Even collective excitations, classical or quantum are nowadays coherently interfaced by SAWs. This wide, highly diverse, interdisciplinary and continuously expanding spectrum literally unites advanced sensing and manipulation applications. Remarkably, SAW technology is inherently multiscale and spans from single atomic or nanoscopic units up even to the millimeter scale. The aim of this Roadmap is to present a snapshot of the present state of surface acoustic wave science and technology in 2019 and provide an opinion on the challenges and opportunities that the future holds from a group of renown experts, covering the interdisciplinary key areas, ranging from fundamental quantum effects to practical applications of acoustic devices in life science.
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| 8. |
- Fu, Shuangshuang, et al.
(författare)
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Feedback policies for measurement-based quantum state manipulation
- 2014
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Ingår i: Physical Review A. Atomic, Molecular, and Optical Physics. - 1050-2947 .- 1094-1622. ; 90:6
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Tidskriftsartikel (refereegranskat)abstract
- In this paper, we propose feedback designs for manipulating a quantum state to a target state by performing sequential measurements. In light of Belavkin's quantum feedback control theory, for a given set of (projective or nonprojective) measurements and a given time horizon, we show that finding the measurement selection policy that maximizes the probability of successful state manipulation is an optimal control problem for a controlled Markovian process. The optimal policy is Markovian and can be solved by dynamical programming. Numerical examples indicate that making use of feedback information significantly improves the success probability compared to classical scheme without taking feedback. We also consider other objective functionals including maximizing the expected fidelity with the target state as well as minimizing the expected arrival time. The connections and differences among these objectives are also discussed.
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