| 1. |
- Cheng, Jie, et al.
(författare)
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DISCS: A Distributed Coordinate System Based on Robust Nonnegative Matrix Completion
- 2017
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Ingår i: IEEE/ACM Transactions on Networking. - : IEEE. - 1063-6692 .- 1558-2566. ; 25:2, s. 934-947
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Tidskriftsartikel (refereegranskat)abstract
- Many distributed applications, such as BitTorrent, need to know the distance between each pair of network hosts in order to optimize their performance. For small-scale systems, explicit measurements can be carried out to collect the distance information. For large-scale applications, this approach does not work due to the tremendous amount of measurements that have to be completed. To tackle the scalability problem, network coordinate system (NCS) was proposed to solve the scalability problem by using partial measurements to predict the unknown distances. However, the existing NCS schemes suffer seriously from either low prediction precision or unsatisfactory convergence speed. In this paper, we present a novel distributed network coordinate system (DISCS) that utilizes a limited set of distance measurements to achieve high-precision distance prediction at a fast convergence speed. Technically, DISCS employs the innovative robust nonnegative matrix completion method to improve the prediction accuracy. Through extensive experiments based on various publicly-available data sets, we found that DISCS outperforms the state-of-the-art NCS schemes in terms of prediction precision and convergence speed, which clearly shows the high usability of DISCS in real-life Internet applications.
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| 2. |
- Gosselin, Stéphane, et al.
(författare)
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Fixed and Mobile Convergence: Needs and Solutions
- 2014
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Konferensbidrag (refereegranskat)abstract
- The drivers of Fixed and Mobile Convergence (FMC) are discussed. A reference framework for FMC proposed by European project COMBO is then presented. Some use cases of FMC are described, showing the needs for mutualization and convergence of fixed and mobile broadband networks. Five network scenarios providing technical solutions to FMC use cases are proposed. They target an optimal and seamless quality of experience for the end user together with an optimized network infrastructure ensuring increased performance, flexibility, reduced cost and reduced energy consumption.
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| 3. |
- Kang, Peiyuan, et al.
(författare)
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Transient Photoinactivation of Cell Membrane Protein Activity without Genetic Modification by Molecular Hyperthermia
- 2019
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Ingår i: ACS Nano. - : AMER CHEMICAL SOC. - 1936-0851 .- 1936-086X. ; 13:11, s. 12487-12499
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Tidskriftsartikel (refereegranskat)abstract
- Precise manipulation of protein activity in living systems has broad applications in biomedical sciences. However, it is challenging to use light to manipulate protein activity in living systems without genetic modification. Here, we report a technique to optically switch off protein activity in living cells with high spatiotemporal resolution, referred to as molecular hyperthermia (MH). MH is based on the nanoscale-confined heating of plasmonic gold nanoparticles by short laser pulses to unfold and photoinactivate targeted proteins of interest. First, we show that protease-activated receptor 2 (PAR2), a G-protein-coupled receptor and an important pathway that leads to pain sensitization, can be photoinactivated in situ by MH without compromising cell proliferation. PAR2 activity can be switched off in laser-targeted cells without affecting surrounding cells. Furthermore, we demonstrate the molecular specificity of MH by inactivating PAR2 while leaving other receptors intact. Second, we demonstrate that the photoinactivation of a tight junction protein in brain endothelial monolayers leads to a reversible blood-brain barrier opening in vitro. Lastly, the protein inactivation by MH is below the nanobubble generation threshold and thus is predominantly due to the nanoscale heating. MH is distinct from traditional hyperthermia (that induces global tissue heating) in both its time and length scales: nanoseconds versus seconds, nanometers versus millimeters. Our results demonstrate that MH enables selective and remote manipulation of protein activity and cellular behavior without genetic modification.
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| 4. |
- Tang, R., et al.
(författare)
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Increasing terrestrial ecosystem carbon release in response to autumn cooling and warming
- 2022
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Ingår i: Nature Climate Change. - : Springer Science and Business Media LLC. - 1758-678X .- 1758-6798. ; 12, s. 380-385
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Tidskriftsartikel (refereegranskat)abstract
- Despite overall warming, many regions in the Northern Hemisphere have been cooling in autumn. This cooling resulted in an increasing release of net CO2 2004-2018 as primary production decreased more than respiration in cooling and respiration increased more than production in warming areas. Part of the Northern Hemisphere has experienced widespread autumn cooling during the most recent decades despite overall warming, but how this contrasting temperature change has influenced the ecosystem carbon exchange remains unclear. Here, we show that autumn cooling has occurred over about half of the area north of 25 degrees N since 2004, producing a weak cooling trend over the period 2004-2018. Multiple lines of evidence suggest an increasing net CO2 release in autumn during 2004-2018. In cooling areas, the increasing autumn CO2 release is due to the larger decrease of gross primary productivity (GPP) growth than total ecosystem respiration (TER) growth suppressed by cooling. In the warming areas, TER increased more than GPP because the warming and wetting conditions are more favourable for TER growth than GPP increase. Despite the opposite temperature trends, there has been a systematic increase in ecosystem carbon release across the Northern Hemisphere middle and high latitudes.
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| 5. |
- Wang, Sifan, et al.
(författare)
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Fire carbon emissions over Equatorial Asia reduced by shortened dry seasons
- 2023
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Ingår i: npj Climate and Atmospheric Science. - 2397-3722. ; 6:1
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Tidskriftsartikel (refereegranskat)abstract
- Fire carbon emissions over Equatorial Asia (EQAS) play a critical role in the global carbon cycle. Most regional fire emissions (89.0%) occur in the dry season, but how changes in the dry-season length affect the fire emissions remains poorly understood. Here we show that, the length of the EQAS dry season has decreased significantly during 1979–2021, and the delayed dry season onset (5.4 ± 1.6 (± one standard error) days decade−1) due to increased precipitation (36.4 ± 9.1 mm decade−1) in the early dry season is the main reason. The dry season length is strongly correlated with the length of the fire season. Increased precipitation during the early dry season led to a significant reduction (May: −0.7 ± 0.4 Tg C decade−1; August: −12.9 ± 6.7 Tg C decade−1) in fire carbon emissions during the early and peak fire season. Climate models from the Coupled Model Intercomparison Project Phase 6 project a continued decline in future dry season length in EQAS under medium and high-emission scenarios, implying further reductions in fire carbon emissions.
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| 6. |
- Wang, Wei, et al.
(författare)
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Entropy generation analysis of fully-developed turbulent heat transfer flow in inward helically corrugated tubes
- 2018
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Ingår i: Numerical Heat Transfer; Part A: Applications. - : Informa UK Limited. - 1040-7782 .- 1521-0634. ; 73:11, s. 788-805
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Tidskriftsartikel (refereegranskat)abstract
- The entropy generation analysis of fully-developed turbulent heat transfer flow in inward helically corrugated tubes was numerically performed by using a Reynolds stress model. The simulations were conducted for a smooth tube and five cases of corrugated tubes with Reynolds number (Re) ranging from 10,020 to 40,060 at a constant wall temperature condition. The effects of corrugation pitch and height on the flow patterns as well as local thermal and frictional entropy generation are detailed in the near wall region. The results indicate that the local heat transfer entropy generation is significantly evident at the sub-layer region and the detached vortex region, and the local thermal entropy is improved with increases in the secondary flow. Local friction entropy generation is mainly located at the windward of the corrugation and the severely turbulent fluctuation region and is mainly induced by the velocity gradient. The average friction entropy generation exhibits an exponential growth, while the average heat transfer and the total entropy generation display a linear growth trend with increased Re. The average Bejan number (Be) exhibits an exponential decline, and the minimum value can reach 0.69. From a comprehensive viewpoint, it is optimal for the Re to be lower than 30,050. When Re <20,030, higher and dense corrugations are beneficial. When 20,030 < Re <30,050, low and spare corrugations are more optimal. Besides, the case with Hl/D = 0.08 is not recommended.
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| 7. |
- Wang, Wei, et al.
(författare)
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Large eddy simulation of turbulent flow and heat transfer in outward transverse and helically corrugated tubes
- 2019
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Ingår i: Numerical Heat Transfer; Part A: Applications. - : Informa UK Limited. - 1040-7782 .- 1521-0634. ; 75:7, s. 456-468
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Tidskriftsartikel (refereegranskat)abstract
- Turbulent flow and heat transfer in outward transverse and helically corrugated tubes are performed with large eddy simulation by the ANSYS Fluent software. The prediction accuracy is validated by comparison with experimental data and empirical correlations for a wavy surface wall and smooth tube, respectively. The turbulent flow patterns, local heat transfer, and friction factor are discussed. The results show that the secondary and turbulent eddies are inhibited by the spiral flow. Otherwise, the flow impact of the wall is the key factor for heat transfer enhancement, and the spiral flow has of small effect on heat transfer performance, however it can decrease the flow resistance significantly. The overall heat transfer performance for the helical corrugated tube is 1.23, which is superior to the value of 1.18 for the transverse corrugated tube.
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| 8. |
- Wang, Wei, et al.
(författare)
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Numerical investigation of entropy generation of turbulent flow in a novel outward corrugated tube
- 2018
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Ingår i: International Journal of Heat and Mass Transfer. - : Elsevier BV. - 0017-9310. ; 126, s. 836-847
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Tidskriftsartikel (refereegranskat)abstract
- The present study numerically investigates the second law analysis of turbulent flow in novel outward helical corrugated tubes by using a Reynolds Stress Model (RSM). A case of a transverse corrugated tube and five cases of helical corrugated tubes with different height-to-diameter ratios and pitch-to-diameter ratios are examined with Reynolds number ranging from 3800 to 43,800 at a constant wall temperature condition. The results indicate that the secondary flow significantly increases the thermal and viscous dissipation irreversibilities. However, the spiral flow inhibits the secondary flow and the production of local entropy. The heat transfer effective zone (Belocal > 0.5) is mainly located at the sub-layer and buffer-layer, and the ineffective zone (Belocal < 0.2) is located at the turbulent severe pulsation zone. A comprehensive consideration of the total entropy generation number (Ns-tot) and average Bejan number (Beave) indicates that the optimal Re is less than 31,000 for all the cases although Re does not exceed 18,800 in the case of Hl/D = 0.15, pl/D = 1.0 and Hl/D = 0.10, pl/D = 0.5. Additionally, the helical corrugated tube exhibits an overall advantage when compared with a transverse corrugated tube with the same geometrical parameters.
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