| 1. |
- Fenstermacher, M.E., et al.
(författare)
-
DIII-D research advancing the physics basis for optimizing the tokamak approach to fusion energy
- 2022
-
Ingår i: Nuclear Fusion. - : IOP Publishing. - 0029-5515 .- 1741-4326. ; 62:4
-
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.
|
|
| 2. |
- Voitsekhovitch, I., et al.
(författare)
-
Recent EUROfusion Achievements in Support of Computationally Demanding Multiscale Fusion Physics Simulations and Integrated Modeling
- 2018
-
Ingår i: Fusion Science and Technology. - : Informa UK Limited. - 1536-1055 .- 1943-7641. ; 74:3, s. 186-197
-
Tidskriftsartikel (refereegranskat)abstract
- © 2018, © 2018 The Authors. Published with license by Taylor & Francis Group, LLC. Integrated modeling (IM) of present experiments and future tokamak reactors requires the provision of computational resources and numerical tools capable of simulating multiscale spatial phenomena as well as fast transient events and relatively slow plasma evolution within a reasonably short computational time. Recent progress in the implementation of the new computational resources for fusion applications in Europe based on modern supercomputer technologies (supercomputer MARCONI-FUSION), in the optimization and speedup of the EU fusion-related first-principle codes, and in the development of a basis for physics codes/modules integration into a centrally maintained suite of IM tools achieved within the EUROfusion Consortium is presented. Physics phenomena that can now be reasonably modelled in various areas (core turbulence and magnetic reconnection, edge and scrape-off layer physics, radio-frequency heating and current drive, magnetohydrodynamic model, reflectometry simulations) following successful code optimizations and parallelization are briefly described. Development activities in support to IM are summarized. They include support to (1) the local deployment of the IM infrastructure and access to experimental data at various host sites, (2) the management of releases for sophisticated IM workflows involving a large number of components, and (3) the performance optimization of complex IM workflows.
|
|
| 3. |
|
|
| 4. |
- Pasquini, Luca, et al.
(författare)
-
Magnesium- and intermetallic alloys-based hydrides for energy storage : modelling, synthesis and properties
- 2022
-
Ingår i: Progress in Energy. - : Institute of Physics Publishing (IOPP). - 2516-1083. ; 4:3
-
Forskningsöversikt (refereegranskat)abstract
- Hydrides based on magnesium and intermetallic compounds provide a viable solution to the challenge of energy storage from renewable sources, thanks to their ability to absorb and desorb hydrogen in a reversible way with a proper tuning of pressure and temperature conditions. Therefore, they are expected to play an important role in the clean energy transition and in the deployment of hydrogen as an efficient energy vector. This review, by experts of Task 40 'Energy Storage and Conversion based on Hydrogen' of the Hydrogen Technology Collaboration Programme of the International Energy Agency, reports on the latest activities of the working group 'Magnesium- and Intermetallic alloys-based Hydrides for Energy Storage'. The following topics are covered by the review: multiscale modelling of hydrides and hydrogen sorption mechanisms; synthesis and processing techniques; catalysts for hydrogen sorption in Mg; Mg-based nanostructures and new compounds; hydrides based on intermetallic TiFe alloys, high entropy alloys, Laves phases, and Pd-containing alloys. Finally, an outlook is presented on current worldwide investments and future research directions for hydrogen-based energy storage.
|
|
| 5. |
- Kang, Jian, et al.
(författare)
-
Vegetation in urban streets, squares, and courtyards
- 2014
-
Ingår i: Environmental Methods for Transport Noise Reduction. - : CRC Press. - 9781482288773 ; , s. 177-194
-
Bokkapitel (övrigt vetenskapligt/konstnärligt)abstract
- One of various ways in which vegetation cover used in the greening of urban areas can help improve the health and well-being of people is in how it changes the acoustic environment. This chapter presents findings of computer simulations and scale modelling to examine and quantify the effectiveness of green roof and green wall (vertical garden) systems in reducing road traffic noise for streets, squares, and roadside courtyards. Noise reduction by sound absorption in reflected and diffracted (over roofs) sound paths is investigated. Particular attention is paid to the importance of vegetation placement relative to the receiver/listening positions. Because the soil substrate used for the vertical walls has good sound absorption properties, it also can be used for green barriers. In this chapter, the effects of a low barrier made of green wall substrate are studied for an installation on the ground and on the top of buildings surrounding a courtyard.
|
|
| 6. |
- Kim, D., et al.
(författare)
-
On the benefit of inter-operator cooperation in C-RAN
- 2021
-
Ingår i: IET Communications. - : Institution of Engineering and Technology (IET). - 1751-8628 .- 1751-8636. ; 15:2, s. 191-199
-
Tidskriftsartikel (refereegranskat)abstract
- Cooperation of co-located mobile network operators can provide potential benefits for the capacity expansion without further densification of radio nodes. However, such benefits need to be scrutinised for coexisting cloud radio access network (C-RAN) operators because the inter-operator cooperation may compromise the superb interference coordination capability that each C-RAN has. Furthermore, altering C-RAN infrastructure for the cooperation incurs a high investment cost. In this paper, quantitative gain of inter-operator coordination strategies is evaluated to provide the C-RAN operators with a guideline on their cooperation decisions. The coordination strategies encompass dynamic user association and the spectrum sharing which aim at maximising the total user throughput. A heuristic algorithm is proposed that reduces the computational burden of the coordination significantly. Numerical results suggest that the inter-operator cooperation is beneficial particularly when the network size of each operator tends to be highly asymmetric. It is also verified that the users who belong to smaller network attain more coordination gains.
|
|
| 7. |
|
|
| 8. |
- Jin, Y., et al.
(författare)
-
District household electricity consumption pattern analysis based on auto-encoder algorithm
- 2019
-
Ingår i: IOP Conference Series: Materials Science and Engineering.
-
Konferensbidrag (refereegranskat)abstract
- The energy shortage is one key issue for sustainable development, a potential solution of which is the integration with the renewable energy resources. However, the temporal sequential characteristic of renewable resources is different from traditional power grid. For the entire power grid, it is essential to match the energy generation side with the energy consumption side, so the load characteristic at the energy use side is crucial for renewable power integration. Better understanding of energy consumption pattern in buildings contributes to matching different source of energy generation. Under the background of integration of traditional and renewable energy, this research focuses on analysis of different household electricity consumption patterns in an urban scale. The original data is from measurement of daily energy consumption with smart meter in households. To avoid the dimension explosion phenomenon, the auto-encoder algorithm is introduced during the clustering analysis of daily electricity use data, which plays the role of principal component analysis. The clustering based on auto-encoder gives a clear insight into the urban electricity use patterns in household. During the data analysis, several feature variables are proposed, which include peak value, valley value and average value. The distinction analysis is also conducted to evaluate the analysis performance. The study takes households in Nanjing city, China as a case study, to conduct the clustering analysis on electricity consumption of residential buildings. The analysis results can be further applied, such as during the capacity design of district energy storage.
|
|
| 9. |
- Yuan, Kang, et al.
(författare)
-
Influence of Ru, Mo and IR on the behavior of Ni-based MCrAlY coatings in high temperature oxidation
- 2014
-
Ingår i: Proceedings of the ASME Turbo Expo. - : American Society of Mechanical Engineers (ASME). - 9780791845752
-
Konferensbidrag (refereegranskat)abstract
- To improve the oxidation/corrosion resistance of MCrAlY coatings (M for Ni and/or Co), elements like Y, Si and Ta have been added into the coatings in past decades. In this study the oxidation performance of a Ni-based MCrAlY coating with small proportion of Ru, Mo and/or Ir were investigated after high-temperature exposure. The oxidation tests were carried out at 900C 1000C or 1100C The microstructure study showed that the addition of Ru, Mo and/or Ir had significant influence on the oxidation behavior at the coating surface and the microstructural evolution in the material. The microstructural evolution was quantitatively evaluated by measuring the phase degradation of β-NiAl in the coating and γ′-Ni3Al in the substrate of superalloy. Since no oxides of Ru, Mo and Ir were found on the coating surface, it was believed that the effects by those elements were mainly due to their dissolution in the metallic phases in the coatings.
|
|
| 10. |
- Chin, Yung-Kang, et al.
(författare)
-
Transient thermal analysis using both lumped-circuit approach and finite element method of a permanet magnet traction motor
- 2006
-
Ingår i: SAIEE Africa Research Journal. - 0038-2221. ; 97:4, s. 263-273
-
Tidskriftsartikel (refereegranskat)abstract
- This paper presents the transient thermal analysis of a permanent magnet (PM) synchronous traction motor. The motor has magnets inset into the surface of the rotor to give a maximum field-weakening range of between 2 and 2.5. Both analytically based lumped circuit and numerical finite element methods have been used to simulate the motor. A comparison of the two methods is made showing the advantages and disadvantages of each. Simulation results are compared with practical measurements.
|
|
