1,048 research outputs found
Cost optimization of offshore wind farm combination with reversible solid oxide cell system producing hydrogen using the PyPSA power system modelling tool
In the context of reaching the net zero carbon target, the UK has set an ambitious target of having a green hydrogen production capacity of 5 GW by 2030. As part of the EPSRC-funded project on high efficiency reversible solid oxide cells (rSOC) for the integration of offshore renewable energy (ORE) using hydrogen, eight scenarios where hydrogen is combined with offshore renewable energy were identified. A model using the PyPSA power system modelling tool combined with a sensitivity study, investigated optimized rSOC system capacities, hydrogen storage capacities, and subsea cable connection capacities under various combinations of infrastructure cost, rSOC system efficiencies, and electricity prices for one of the scenarios. Preliminary results for a 600 MW wind farm situated 60 km from shore combined with offshore hydrogen production illustrate the impact of electricity price on decision-making in energy dispatch and on optimization of infrastructure of an ORE-rSOC system. Results indicate that high electricity price fluctuations call for large amounts of hydrogen production and storage capacity. Further refinement of input data would make this approach a promising decision-making tool for the use in the design of an ORE-rSOC system
Kerr non-linearity in a superconducting Josephson metamaterial
We present a detailed experimental and theoretical analysis of the dispersion
and non-linear Kerr frequency shifts of plasma modes in a one-dimensional
Josephson junction chain containing 500 SQUIDs in the regime of weak
nonlinearity. The measured low-power dispersion curve agrees perfectly with the
theoretical model if we take into account the Kerr renormalisation of the bare
frequencies and the long-range nature of the island charge screening by a
remote ground plane. We measured the self- and cross-Kerr shifts for the
frequencies of the eight lowest modes in the chain. We compare the measured
Kerr coefficients with theory and find good agreement
The Domination Number of Grids
In this paper, we conclude the calculation of the domination number of all
grid graphs. Indeed, we prove Chang's conjecture saying that for
every , .Comment: 12 pages, 4 figure
Reaction â¶Li(p, Îâșâș)â¶He At 1.04 GeV And The ÎâN Interaction
The reaction â¶Li(p, Îâșâș)â¶He has been studied at 1.04 GeV for transferred momenta ranging from 0.11 to 0.35 (GeV/c)2. An exponential decrease of the cross section is observed. A Glauber-type calculation is presented. The possibility of extracting information on Ï(ÎN) and α(ÎN) is discussed
Atomistic simulations of self-trapped exciton formation in silicon nanostructures: The transition from quantum dots to nanowires
Using an approximate time-dependent density functional theory method, we
calculate the absorption and luminescence spectra for hydrogen passivated
silicon nanoscale structures with large aspect ratio. The effect of electron
confinement in axial and radial directions is systematically investigated.
Excited state relaxation leads to significant Stokes shifts for short nanorods
with lengths less than 2 nm, but has little effect on the luminescence
intensity. The formation of self-trapped excitons is likewise observed for
short nanostructures only; longer wires exhibit fully delocalized excitons with
neglible geometrical distortion at the excited state minimum.Comment: 10 pages, 4 figure
Integrated multi-modality image-guided navigation for neurosurgery: open-source software platform using state-of-the-art clinical hardware.
PURPOSE: Image-guided surgery (IGS) is an integral part of modern neuro-oncology surgery. Navigated ultrasound provides the surgeon with reconstructed views of ultrasound data, but no commercial system presently permits its integration with other essential non-imaging-based intraoperative monitoring modalities such as intraoperative neuromonitoring. Such a system would be particularly useful in skull base neurosurgery. METHODS: We established functional and technical requirements of an integrated multi-modality IGS system tailored for skull base surgery with the ability to incorporate: (1) preoperative MRI data and associated 3D volume reconstructions, (2) real-time intraoperative neurophysiological data and (3) live reconstructed 3D ultrasound. We created an open-source software platform to integrate with readily available commercial hardware. We tested the accuracy of the system's ultrasound navigation and reconstruction using a polyvinyl alcohol phantom model and simulated the use of the complete navigation system in a clinical operating room using a patient-specific phantom model. RESULTS: Experimental validation of the system's navigated ultrasound component demonstrated accuracy of [Formula: see text] and a frame rate of 25 frames per second. Clinical simulation confirmed that system assembly was straightforward, could be achieved in a clinically acceptable time of [Formula: see text] and performed with a clinically acceptable level of accuracy. CONCLUSION: We present an integrated open-source research platform for multi-modality IGS. The present prototype system was tailored for neurosurgery and met all minimum design requirements focused on skull base surgery. Future work aims to optimise the system further by addressing the remaining target requirements
What Drives the Intensification of Mesoscale Convective Systems over the West African Sahel under Climate Change?
Extreme rainfall is expected to increase under climate change, carrying potential socioeconomic risks. However, the magnitude of increase is uncertain. Over recent decades, extreme storms over the West African Sahel have increased in frequency, with increased vertical wind shear shown to be a cause. Drier midlevels, stronger cold pools, and increased storm organization have also been observed. Global models do not capture the potential effects of lower- to midtropospheric wind shear or cold pools on storm organization since they parameterize convection. Here we use the first convection-permitting simulations of African climate change to understand how changes in thermodynamics and storm dynamics affect future extreme Sahelian rainfall. The model, which simulates warming associated with representative concentration pathway 8.5 (RCP8.5) until the end of the twenty-first century, projects a 28% increase of the extreme rain rate of MCSs. The Sahel moisture change on average follows ClausiusâClapeyron scaling, but has regional heterogeneity. Rain rates scale with the product of time-of-storm total column water (TCW) and in-storm vertical velocity. Additionally, prestorm wind shear and convective available potential energy both modulate in-storm vertical velocity. Although wind shear affects cloud-top temperatures within our model, it has no direct correlation with precipitation rates. In our model, projected future increase in TCW is the primary explanation for increased rain rates. Finally, although colder cold pools are modeled in the future climate, we see no significant change in near-surface winds, highlighting avenues for future research on convection-permitting modeling of storm dynamics
The genome of Δ15, a serotype-converting, Group E1 Salmonella enterica-specific bacteriophage
AbstractThe genome sequence of the Salmonella enterica serovar Anatum-specific, serotype-converting bacteriophage Δ15 has been completed. The nonredundant genome contains 39,671 bp and 51 putative genes. It most closely resembles the genome of ÏV10, an Escherichia coli O157:H7-specific temperate phage, with which it shares 36 related genes. More distant relatives include the Burkholderia cepacia-specific phage, BcepC6B (8 similar genes), the Bordetella bronchiseptica-specific phage, BPP-1 (8 similar genes) and the Photobacterium profundum prophage, P PÏpr1 (6 similar genes).Δ15 gene identifications based on homologies with known gene families include the terminase small and large subunits, integrase, endolysin, two holins, two DNA methylase enzymes (one adenine-specific and one cytosine-specific) and a RecT-like enzyme. Genes identified experimentally include those coding for the serotype conversion proteins, the tail fiber, the major capsid protein and the major repressor. Δ15's attP site and the Salmonella attB site with which it interacts during lysogenization have also been determined
NA60 results on spectra and the spectral function in In-In collisions
The NA60 experiment at the CERN SPS has studied low-mass muon pairs in 158
AGeV In-In collisions. A strong excess of pairs is observed above the yield
expected from neutral meson decays. The unprecedented sample size of close to
400K events and the good mass resolution of about 2% have made it possible to
isolate the excess by subtraction of the decay sources (keeping the ).
The shape of the resulting mass spectrum exhibits considerable broadening, but
essentially no shift in mass. The acceptance-corrected transverse-momentum
spectra have a shape atypical for radial flow and show a significant mass
dependence, pointing to different sources in different mass regions.Comment: 4 pages, 4 figures, Quark Matter 2006 conference proceeding
A data-parallel many-source shortest-path algorithm to accelerate macroscopic transport network assignment
The performance and scalability of macroscopic assignment and simulation software limits the quantity, scale and complexity of simulations of transport networks that are used to aid the planning, design and operation of transport systems. Through the application of many-core processing architectures (such as Graphics Processing Units (GPUs)) and data-parallel algorithms, the performance of such software can be dramatically increased. In this paper, a work-efficient, Multiple Source Shortest Path (MSSP) implementation of the Bellman-Ford algorithm is proposed to dramatically increase the performance of shortest path calculations for low-density high-diameter graphs, which are characteristic of transportation networks. This is achieved through the use of an Origin-Vertex Frontier to increase the level of parallelism within the shortest path algorithm for multiple source vertices in low-density graphs, when executed on GPUs. The algorithm is implemented within the SATURN transport simulation software and benchmarked on a range of real-world transportation networks. Our algorithm improves hardware utilisation of massively-parallel GPUs; demonstrating performance improvements of up to x over a multi-core CPU (Central Processing Unit) implementation
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