| 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. |
- Abata, E., et al.
(författare)
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Study of energy response and resolution of the ATLAS barrel calorimeter to hadrons of energies from 20 to 350 GeV
- 2010
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Ingår i: Nuclear Instruments and Methods in Physics Research Section A. - : Elsevier. - 0168-9002 .- 1872-9576 .- 0167-5087. ; 621:1-3, s. 134-150
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Tidskriftsartikel (refereegranskat)abstract
- A fully instrumented slice of the ATLAS detector was exposed to test beams from the SPS (Super Proton Synchrotron) at CERN in 2004. In this paper, the results of the measurements of the response of the barrel calorimeter to hadrons with energies in the range 20-350 GeV and beam impact points and angles corresponding to pseudo-rapidity values in the range 0.2-0.65 are reported. The results are compared to the predictions of a simulation program using the Geant 4 toolkit. (C) 2010 Published by Elsevier B.V.
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| 3. |
- Tommasini, R., et al.
(författare)
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Accepted Tutorials at The Web Conference 2022
- 2022
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Ingår i: WWW 2022 - Companion Proceedings of the Web Conference 2022. - New York, NY, USA : Association for Computing Machinery (ACM). ; , s. 391-399
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Konferensbidrag (refereegranskat)abstract
- This paper summarizes the content of the 20 tutorials that have been given at The Web Conference 2022: 85% of these tutorials are lecture style, and 15% of these are hands on.
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| 4. |
- Cui, H. T., et al.
(författare)
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Carbon flow through continental-scale ground logistics transportation
- 2023
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Ingår i: iScience. - : Elsevier BV. - 2589-0042. ; 26:1
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Tidskriftsartikel (refereegranskat)abstract
- The flourishing logistics in both developed and emerging economies leads to huge greenhouse gas (GHG) emissions; however, the emission fluxes are poorly constrained. Here, we constructed a spatial network of logistic GHG emissions based on multisource big data at continental scale. GHG emissions related to logistics transportation reached 112.14Mt CO2-equivalents (CO(2)e), with seven major urban agglomerations contributing 63% of the total emissions. Regions with short transport distances and well-developed road infrastructure had relatively high emission efficiency. Underlying value flow of the commodities is accompanied by logistics carbon flow along the supply chain. The main driving factors affecting GHG emissions are driving speed and gross domestic product. It may mitigate GHGemissions by 27.50-1162.75 Mt CO(2)e in 15 years if a variety of energy combinations or the appropriate driving speed (65-70 km/h) is adopted. The estimations are of great significance to make integrated management policies for the global logistics sector.
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| 5. |
- Zhang, Z. P., et al.
(författare)
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Structural properties of GeSn thin films grown by molecular beam epitaxy
- 2017
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Ingår i: AIP Advances. - : AIP Publishing. - 2158-3226 .- 2158-3226. ; 7:4, s. Article number 045211-
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Tidskriftsartikel (refereegranskat)abstract
- GeSn thin films on Ge (001) with various Sn concentrations from 3.36 to 7.62% were grown by molecular beam epitaxy and characterized. The structural properties were analyzed by reciprocal space mapping in the symmetric (004) and asymmetric (224) planes by high resolution X-ray diffraction (XRD). The lateral correlation length (LCL) and the mosaic spread (MS) were extracted for the epi-layer peaks in the asymmetric (224) diffraction. With the increase of Sn concentration, the LCL reduces while the MS increases, indicating degrading crystalline quality. Dislocations were observed in the sample with 7.62% Sn concentration by transmission electron microscope, consistent with the strain relaxation found in XRD mapping. Besides, the surface morphologies were investigated.
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| 6. |
- Liu, J. J., et al.
(författare)
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Bi2Te3 photoconductive detectors on Si
- 2017
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Ingår i: Applied Physics Letters. - : AIP Publishing. - 0003-6951 .- 1077-3118. ; 110:14
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Tidskriftsartikel (refereegranskat)abstract
- The peculiar properties of the gapless surface states with a Dirac cone shaped energy dispersion in topological insulators (TIs) enable promising applications in photodetection with an ultra-broad band and polarization sensitivity. Since many TIs can be easily grown on silicon (Si) substrates, TIs on Si could make an alternative route for photon detection of Si photonics. We present good device performances of a Si-based single-crystal bismuth telluride (Bi2Te3) photoconductive detector. Room temperature photo responses to 1064 nm and 1550 nm light illumination were demonstrated. Linear dependences of the photocurrent on both the incident light power and the bias voltage were observed. The main device parameters including responsivity and quantum efficiency were extracted. Published by AIP Publishing.
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| 7. |
- Zheng, Y. H., et al.
(författare)
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Photocatalytic activity of Ag/ZnO heterostructure nanocatalyst: Correlation between structure and property
- 2008
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Ingår i: Journal of Physical Chemistry C. - : American Chemical Society (ACS). - 1932-7447 .- 1932-7455. ; 112:29, s. 10773-10777
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Tidskriftsartikel (refereegranskat)abstract
- Ag/ZnO heterostructure nanocatalysts with Ag content of 1 wt % are successfully prepared through three different simple methods, where chemical reduction and photolysis reaction are adopted to fabricate the heterostructure. The dispersity of Ag clusters and/or nanoparticles in Ag/ZnO nanocatalyst is investigated by EDX mapping and XPS techniques. The experimental results show that deposition-precipitation is an efficient method to synthesize Ag/ZnO nanocatalyst with highly dispersed Ag clusters and/or nanoparticles; the photocatalytic activity of Ag/ZnO photocatalysts mainly depends on the dispersity of metallic Ag in Ag/ZnO nanocatalyst; the higher the dispersity of metallic Ag in Ag/ZnO nanocatalyst is, the higher the photocatalytic activity of Ag/ZnO photocatalyst should be. In addition, it is also found that the dispersity of Ag/ZnO photocatalyst in the dye solution is another key factor for liquid-phase photocatalysis due to the UV-light utilizing efficiency. The higher the UV-light utilizing efficiency is, the higher the photocatalytic activity of Ag/ZnO heterostructure photocatalyst should be.
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| 8. |
- Chen, X., et al.
(författare)
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Achieving memory access equalization via round-trip routing latency prediction in 3D many-core NoCs
- 2015
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Ingår i: Proceedings of IEEE Computer Society Annual Symposium on VLSI, ISVLSI. - : IEEE. ; , s. 398-403
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Konferensbidrag (refereegranskat)abstract
- 3D many-core NoCs are emerging architectures for future high-performance single chips due to its integration of many processor cores and memories by stacking multiple layers. In such architecture, because processor cores and memories reside in different locations (center, corner, edge, etc.), memory accesses behave differently due to their different communication distances, and the performance (latency) gap of different memory accesses becomes larger as the network size is scaled up. This phenomenon may lead to very high latencies suffered from by some memory accesses, thus degrading the system performance. To achieve high performance, it is crucial to reduce the number of memory accesses with very high latencies. However, this should be done with care since shortening the latency of one memory access can worsen the latency of another as a result of shared network resources. Therefore, the goal should focus on narrowing the latency difference of memory accesses. In the paper, we address the goal by proposing to prioritize the memory access packets based on predicting the round-trip routing latencies of memory accesses. The communication distance and the number of the occupied items in the buffers in the remaining routing path are used to predict the round-trip latency of a memory access. The predicted round-trip routing latency is used as the base to arbitrate the memory access packets so that the memory access with potential high latency can be transferred as early and fast as possible, thus equalizing the memory access latencies as much as possible. Experiments with varied network sizes and packet injection rates prove that our approach can achieve the goal of memory access equalization and outperforms the classic round-robin arbitration in terms of maximum latency, average latency, and LSD1. In the experiments, the maximum improvement of the maximum latency, the average latency and the LSD are 80%, 14%, and 45% respectively.
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| 9. |
- Tang, X. D., et al.
(författare)
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Kinetic temperature of massive star-forming molecular clumps measured with formaldehyde: IV. The ALMA view of N113 and N159W in the LMC
- 2021
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Ingår i: Astronomy and Astrophysics. - : EDP Sciences. - 0004-6361 .- 1432-0746. ; 655
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Tidskriftsartikel (refereegranskat)abstract
- We mapped the kinetic temperature structure of two massive star-forming regions, N113 and N159W, in the Large Magellanic Cloud (LMC). We have used 1.6 (0.4 pc) resolution measurements of the para-H2CO JKaKc = 303-202, 322-221, and 321-220 transitions near 218.5 GHz to constrain RADEX non local thermodynamic equilibrium models of the physical conditions. The gas kinetic temperatures derived from the para-H2CO line ratios 322-221/303-202 and 321-220/303-202 range from 28 to 105 K in N113 and 29 to 68 K in N159W. Distributions of the dense gas traced by para-H2CO agree with those of the 1.3 mm dust and Spitzer 8.0 μm emission, but they do not significantly correlate with the Hα emission. The high kinetic temperatures (Tkin50 K) of the dense gas traced by para-H2CO appear to be correlated with the embedded infrared sources inside the clouds and/or young stellar objects in the N113 and N159W regions. The lower temperatures (Tkin < 50 K) were measured at the outskirts of the H2CO-bearing distributions of both N113 and N159W. It seems that the kinetic temperatures of the dense gas traced by para-H2CO are weakly affected by the external sources of the Hα emission. The non thermal velocity dispersions of para-H2CO are well correlated with the gas kinetic temperatures in the N113 region, implying that the higher kinetic temperature traced by para-H2CO is related to turbulence on a 0.4 pc scale. The dense gas heating appears to be dominated by internal star formation activity, radiation, and/or turbulence. It seems that the mechanism heating the dense gas of the star-forming regions in the LMC is consistent with that in Galactic massive star-forming regions located in the Galactic plane.
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| 10. |
- Chen, H., et al.
(författare)
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Unprecedented non-hysteretic superelasticity of [001]-oriented NiCoFeGa single crystals
- 2020
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Ingår i: Nature Materials. - : Nature Research. - 1476-1122 .- 1476-4660.
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Tidskriftsartikel (refereegranskat)abstract
- Superelasticity associated with the martensitic transformation has found a broad range of engineering applications1,2. However, the intrinsic hysteresis3 and temperature sensitivity4 of the first-order phase transformation significantly hinder the usage of smart metallic components in many critical areas. Here, we report a large superelasticity up to 15.2% strain in [001]-oriented NiCoFeGa single crystals, exhibiting non-hysteretic mechanical responses, a small temperature dependence and high-energy-storage capability and cyclic stability over a wide temperature and composition range. In situ synchrotron X-ray diffraction measurements show that the superelasticity is correlated with a stress-induced continuous variation of lattice parameter accompanied by structural fluctuation. Neutron diffraction and electron microscopy observations reveal an unprecedented microstructure consisting of atomic-level entanglement of ordered and disordered crystal structures, which can be manipulated to tune the superelasticity. The discovery of the large elasticity related to the entangled structure paves the way for exploiting elastic strain engineering and development of related functional materials.
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