545 research outputs found
Influence of pore architecture and chemical structure on the sodium storage in nitrogen-doped hard carbons
Hard carbon is the material of choice for sodium ion battery anodes. Capacities comparable to those of lithium/graphite can be reached, but the understanding of the underlying sodium storage mechanisms remains fragmentary. A two-step process is commonly observed, where sodium first adsorbs to polar sites of the carbon (âsloping regionâ) and subsequently fills small voids in the material (âplateau regionâ). To study the impact of nitrogen functionalities and pore geometry on sodium storage, a systematic series of nitrogen-doped hard carbons is synthesized. The nitrogen content is found to contribute to sloping capacity by binding sodium ions at edges and defects, whereas higher plateau capacities are found for materials with less nitrogen content and more extensive graphene layers, suggesting the formation of 2D sodium structures stabilized by graphene-like pore walls. In fact, up to 84% of the plateau capacity is measured at potentials less than 0Â V versus metallic Na, that is, quasimetallic sodium can be stabilized in such structure motifs. Finally, gas physisorption measurements are related to chargeâdischarge data to identify the energy storage relevant pore architectures. Interestingly, these are pores inaccessible to probe gases and electrolytes, suggesting a new view on such âclosed poresâ required for efficient sodium storage
Follow the Leader: Examining Real and Augmented Reality Lead Vehicles as Driving Navigational Aids
Two studies investigated the concept of following a lead vehicle as a navigational aid. The first videobased study (n=34) considered how drivers might use a real-world lead vehicle as a navigational aid, whilst the second simulator-based study (n=22) explored how an Augmented Reality (AR) virtual car, presented on a head-up display (HUD), may aid navigation around a complex junction. Study 1indicated that a lead vehicle is most valued as a navigation aid just before/during a required maneuver. During the second study the dynamic virtual car (which behaved like a real vehicle) resulted in greater confidence and lower workload than a static virtual car that âwaitsâ at the correct junction exit, but resulted in more gaze concentration. It is concluded that a virtual car may be a valuable element of a navigation system, in combination with other forms of information, to completely fulfil all a driverâs navigational task requirements
Archiving Software Surrogates on the Web for Future Reference
Software has long been established as an essential aspect of the scientific
process in mathematics and other disciplines. However, reliably referencing
software in scientific publications is still challenging for various reasons. A
crucial factor is that software dynamics with temporal versions or states are
difficult to capture over time. We propose to archive and reference surrogates
instead, which can be found on the Web and reflect the actual software to a
remarkable extent. Our study shows that about a half of the webpages of
software are already archived with almost all of them including some kind of
documentation.Comment: TPDL 2016, Hannover, German
Mechanistic insights into the reversible lithium storage in an open porous carbon via metal cluster formation in all solid-state batteries
Porous carbons are promising anode materials for next generation lithium batteries due to their large lithium storage capacities. However, their high voltage slope during lithiation and delithiation as well as capacity fading due to intense formation of solid electrolyte interphase (SEI) limit their gravimetric and volumetric energy densities. Herein we compare a microporous carbide-derived carbon material (MPC) as promising future anode for all solid-state batteries with a commercial high-performance hard carbon anode. The MPC obtains high and reversible lithiation capacities of 1000 mAh gâ1carbon in half-cells exhibiting an extended plateau region near 0âŻV vs. Li/Li+ preferable for full-cell application. The well-defined micro porosity of the MPC with a specific surface area of >1500âŻm2âŻgâ1 combines well with the argyrodite-type electrolyte (Li6PS5Cl) suppressing extensive SEI formation to deliver high coulombic efficiencies. Preliminary full-cell measurements vs. nickel-rich NMC-cathodes (LiNi0.9Co0.05Mn0.05O2) provide a considerably improved average potential of 3.76âŻV leading to a projected energy density as high as 449âŻWh kgâ1 and reversible cycling for more than 60 cycles. 7Li Nuclear Magnetic Resonance spectroscopy was combined with ex-situ Small Angle X-ray Scattering to elucidate the storage mechanism of lithium inside the carbon matrix. The formation of extended quasi-metallic lithium clusters after electrochemical lithiation was revealed
Getting the driver back into the loop: the quality of manual vehicle control following long and short non-critical transfer-of-control requests: TI:NS
Specific vehicle automation use-cases such as traffic jams will be the first level 3 functions on the market. When the âtraffic jam pilotâ nears its limits in non-critical situations, control needs to be handed back to the driver, enabling appropriate situation awareness (SA) and vehicle handling. According to previous research, operational vehicle stabilisation can be achieved within a transfer-of-control (TOC) of a few seconds in simple traffic environments, but tactical level decisions benefit from longer hand-over times. To date, the effects of non-critical TOCs have not been studied using set time frames. To investigate the impact of short (unplanned, 5 seconds) and long (planned, 50 seconds) TOC requests, while playing/not playing an engaging tablet game, a simulator experiment was conducted with 16 participants. Comparisons of the 60-second-period of manual driving following automation suggest better longitudinal vehicle control as well as more appropriate SA following the long TOC request, and automation periods without the game. However, following no engaging game, lateral performance was worse during the first 10 seconds of manual driving. Control-level visual search patterns did not change with TOC time or the game. Future research needs to consider support for driversâ SA maintenance and readiness to drive following high automation
Knowledge based improvement:simulation and artificial intelligence for identifying and improving human decision-making in an operations systems
The performance of most operations systems is significantly affected by the interaction of human decision-makers. A methodology, based on the use of visual interactive simulation (VIS) and artificial intelligence (AI), is described that aims to identify and improve human decision-making in operations systems. The methodology, known as 'knowledge-based improvement' (KBI), elicits knowledge from a decision-maker via a VIS and then uses AI methods to represent decision-making. By linking the VIS and AI representation, it is possible to predict the performance of the operations system under different decision-making strategies and to search for improved strategies. The KBI methodology is applied to the decision-making surrounding unplanned maintenance operations at a Ford Motor Company engine assembly plant
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Third-harmonic generation enhancement in an ITO nanoparticle-coated microresonator
We report a ∼3-fold enhancement of third-harmonic generation (THG) conversion efficiency using indium tin oxide (ITO) nanoparticles on the surface of an ultra-high-Q silica microsphere. This is one of the largest microcavity-based THG enhancements reported. Phase-matching and spatial mode overlap are explored numerically to determine the microsphere radius (∼29 µm) and resonant mode numbers that maximize THG. Furthermore, the ITO nanoparticles are uniformly bonded to the cavity surface by drop-casting, eliminating the need for complex fabrication. The significant improvement in THG conversion efficiency establishes functionalized ITO microcavities as a promising tool for broadband frequency conversion, nonlinear enhancement, and applications in integrated photonics.</p
Getting the driver back into the loop: the quality of manual vehicle control following long and short non-critical transfer-of-control requests: TI:NS
Specific vehicle automation use-cases such as traffic jams will be the first level 3 functions on the market. When the âtraffic jam pilotâ nears its limits in non-critical situations, control needs to be handed back to the driver, enabling appropriate situation awareness (SA) and vehicle handling. According to previous research, operational vehicle stabilisation can be achieved within a transfer-of-control (TOC) of a few seconds in simple traffic environments, but tactical level decisions benefit from longer hand-over times. To date, the effects of non-critical TOCs have not been studied using set time frames. To investigate the impact of short (unplanned, 5 seconds) and long (planned, 50 seconds) TOC requests, while playing/not playing an engaging tablet game, a simulator experiment was conducted with 16 participants. Comparisons of the 60-second-period of manual driving following automation suggest better longitudinal vehicle control as well as more appropriate SA following the long TOC request, and automation periods without the game. However, following no engaging game, lateral performance was worse during the first 10 seconds of manual driving. Control-level visual search patterns did not change with TOC time or the game. Future research needs to consider support for driversâ SA maintenance and readiness to drive following high automation
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