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The Nanostructure of Water-in-Salt Electrolytes Revisited: Effect of the Anion Size
No full textThe increasing interest in developing safe and sustainable energy storage systems has led to the rapid rise in attention to superconcentrated electrolytes, commonly called water-in-salt (WiS). Several works indicate that the transport properties of these liquid electrolytes are related to the presence of nanodomains, but a detailed characterization of such structure is missing. Here, the structural nano-heterogeneity of lithium WiS electrolytes, comprising lithium trifluoromethanesulfonate (LiTf) and bis(trifluoromethanesulfonyl)imide (LiTFSI) solutions as a function of concentration and temperature, was assessed by resorting to the analysis of small-angle neutron scattering (SANS) patterns. Variations with the concentration of a correlation peak, rather temperature-independent, in a Q range around 3.5-5 nm-1 indicate that these electrolytes are composed of nanometric water-rich channels percolating a 3D dispersing anion-rich network, with differences between Tf and TFSI anions related to their distinct volumes and interactions. Furthermore, a common trend was found for both systems' morphology above a salt volume fraction of ∼0.5. These results imply that the determining factor in the formation of the nanostructure is the salt volume fraction (related to the anion size), rather than its molality. These findings may represent a paradigm shift for designing WiS electrolytes
Design and analysis of intelligent text entry systems with function structure models and envelope analysis
No full textDesigning intelligent interactive text entry systems often relies on factors that are difficult to estimate or assess using traditional HCI design and evaluation methods. We introduce a complementary approach by adapting function structure models from engineering design. We extend their use by extracting controllable and uncontrollable parameters from function structure models and visualizing their impact using envelope analysis. Function structure models allow designers to understand a system in terms of its functions and flows between functions and decouple functions from function carriers. Envelope analysis allows the designer to further study how parameters affect variables of interest, for example, accuracy, keystroke savings and other dependent variables.We provide examples of function structure models and illustrate a complete envelope analysis by investigating a parameterized function structure model of predictive text entry. We discuss the implications of this design approach for both text entry system design and for critique of system contributions
Charging Optimization of a YBCO Racetrack Coil with a Linear-Motor Type Flux Pump for an HTS Synchronous Motor
No full textThis paper presents the preliminary charging test results of an high temperature superconducting (HTS) no-insulated (NI) double racetrack coil with the linear-motor type flux pump. The racetrack coil is designed and manufactured for the rotor field winding of a 16.9-kW-class HTS synchronous motor. This HTS synchronous motor was designed to employ a contactless static excitation device (CSED), i.e., the linear-motor type flux pump, which can charge the racetrack coil installed in the rotating machine in contactless manner. In the experiment, the major components of the 16.9-kW-class HTS synchronous motor, such as the racetrack coil and the CSED, had been manufactured, tested and optimized. The charging performance was tested in 77 K. In particular, we optimize the CSED of the HTS synchronous motor by testing different wavelengths of flux pumps and different superconducting stator wires, so as to select the appropriate wavelength of the flux pump and stator wire to optimize the operation of the synchronous motor
Using probabilistic fault tree analysis and monte carlo simulation to examine the likelihood of risks associated with ballasted railway drainage failure
No full textInadequate track drainage can lead to a variety of issues, including flooding, accelerated track degradation, and progressive or sudden failure of railway track, slope, or embankment. These can result in unplanned track maintenance, additional passenger travel costs, and damage to third party property. However, railway drainage asset management is challenging because it involves the consideration of large interconnected assets, limited maintenance budgets, and unknown failure probabilities. To address this issue, this paper introduces a risk-informed approach for railway drainage asset management that uses fault tree analysis to identify the factors that contribute to railway drainage flood risk and quantifies the likelihood of the occurrence of these factors using Monte Carlo simulation. This rational approach enables drainage asset managers to evaluate easily the factors that affect the likelihood of railway track drainage failure, thereby facilitating the prioritization of appropriate mitigation measures and in so doing improve the allocation of scarce maintenance resources. The analysis identified 46 basic and 49 intermediate contributing factors associated with drainage failure of ballasted railway track (undesired event). The usefulness of the approach is demonstrated for three sites on the UK railway network, namely, Ardsley Tunnel, Clay Cross Tunnel, and Draycott. The analysis shows that the Clay Cross Tunnel had the highest probability of drainage failure and should be prioritized for maintenance over the other two sites. The maintenance required should focus on blockages because of vegetation overgrowth or debris accumulation
Kerr Comb-Driven Silicon Photonic Transmitter
No full textWe demonstrate the first on-chip silicon photonic transmitter using a Kerr frequency comb source for massive wavelength parallelism. The architecture is scalable to hundreds of wavelength channels, paving the way for multi-Tb/s photonic interconnects
Production Control in Earthworks: Concepts and Metrics
No full textThe lean construction theoretical lens afforded by the Transformation-Flow-Value (TFV) theory has led to changes in the way production is understood in building construction projects. However, this new perception of production has not taken root in the earthworks and infrastructure sectors, primarily because of the difficulty in discerning what the products are and how they flow. This research addresses the fundamental question of production flow in the specific context of earthworks. It proposes a novel lean view of production flow in earthworks, and it validates the proposed model by developing and testing assessment procedures for evaluation of the quality of production flow. Its metrics apply measurements of throughput, cycle time, work in progress, and waste to enable improved situational awareness for effective decision making in managing execution of earthworks onsite. The measurements use monitoring data acquired from machine control technologies, linked to a specialized information schema developed to represent continuous elements (e.g., road courses or landfills) using discrete elements. The procedures are demonstrated on a reservoir embankment construction project. Three different theoretical production scenarios are presented to illustrate the applicability of production theory and of the metrics and procedures to the context of earthworks
Democratizing Information Visualization. A Study to Map the Value of Graphic Design
No full textVisual representations are a consistent component of human evolution. They are forms of concept designs using combinations of colors, patterns, and geometrical figures. As history displays, graphical visualization has been used since early ages as a mean to transfer knowledge between human beings across generations. Recently, visual representations became recognized by various scientists as tools to ease cognitive comprehension in various scientific fields. Therefore, visual representations are becoming important in science communication and education. Notwithstanding the general relevance of visual representations, there is not extensive recognition of the value of graphical representation to improve communication of scientific results and the level of awareness of visual design principles among non-design-centered communities is low. Considering these aspects, this explorative study investigates the perception of STEM researchers, without any specific visual design background, and the value of visual representations as tools to support the communication of technical and scientific knowledge among academics and a wider non-design-centered community. To measure the user perception and the value of visual representations in daily working practice, an interpretive approach was used, and a pilot study was conducted with a group of voluntary participants recruited among research members from a well-known American institution. Results emphasize how researchers, who included professionally executed graphical representations in their publications, reports, and grant proposals, perceived their work as more easily readable. Early findings show that visual representations can positively support scientists to share research outcomes in a more compelling, visually clear, and impactful manner, reaching a wider audience across different disciplines
A new vision of short-time and long-time AC loss measurement and modelling: A superconducting power electronic circuit
No full textThis paper provides a new vision of loss measurement and modelling for superconducting coils, with both the short-time test and long-time test, as the behaviour of the AC loss in superconductors is actually a dynamic process with the temperature and time dependence, particularly for the medium-to-high frequency AC operation. A single-pancake High temperature superconducting (HTS) coil was tested in a power electronic circuit (DC-AC inverter). The operating current was from 15 A to 50 A, and the operating frequency was from 1 kHz to 5 kHz. The AC loss measurements were carried out using the function of fully decoupling power by a commercial power analyzer. This method was able to measure the real-time AC loss, and the loss measuring process is much easier than the conventional electrical and magnetic method. As expected, for short-time loss tests, the experiment, the FEM H-formulation model, and the conventional analytical model agree with each other. However, the AC losses in long-time tests are found having power-law relations with the operating time (above kHz level). As the accumulated heat in the HTS coil as well as the interrelation between the critical current and temperature, the real-time AC losses are strongly time-dependent. A new time-dependent analytical model is developed, for the purpose of accurately modelling the real-time loss in the HTS coil. The new analytical model well matches the AC loss tests over both the long and short testing time. The experimental method and new analytical model offer a new sight at the AC loss of superconducting coil for both the short-time and long-time operation in a power electronic circuit, which is able to explore more reasonable guidelines of safe operating area (SOA) during the practical AC operation of superconducting applications
A semi-implicit immersed boundary method for simulating viscous flow-induced sound with moving boundaries
No full textIn this paper, a semi-implicit immersed boundary body force model is derived from the compressible Navier–Stokes equations, to directly predict the viscous flow-induced sound from moving objects on a fixed Cartesian grid. To overcome the conflict of grid quality with efficiency in simulating moving-boundary problems with high-order computational aeroacoustics methods, a prediction–correction technique is utilized. This accurately satisfies no-slip wall boundary conditions at every time step without any feedback treatment. A particular contribution of the work is the introduction of a numerical model equation to analyze the body force convergence. This is useful to pre-evaluate the generated Cartesian and body-surface grids. Several benchmark aeroacoustic problems are simulated to validate the present model. Results show that the unsteady force and far-field sound directivity agree well with the previous direct numerical simulation results. The work further suggests that the developed body force model/CAA methods are capable of predicting interaction noise, especially those associated with oscillating multiple objects
Multilayer Codes for Synchronization from Deletions and Insertions
No full textConsider two remote nodes (encoder and decoder), each with a binary sequence. The encoder's sequence X differs from the decoder's sequence Y by a small number of edits (deletions and insertions). The goal is to construct a message M, to be sent via a one-way error free link, such that the decoder can reconstruct X using M and Y. In this paper, we devise a coding scheme for this one-way synchronization model. The scheme is based on multiple layers of Varshamov-Tenengolts (VT) codes combined with off-the-shelf linear error-correcting codes, and uses a list decoder. We bound the expected list size of the decoder under certain assumptions, and validate its performance via numerical simulations. We also consider an alternative decoder that uses only the constraints from the VT codes (i.e., does not require a linear code), and has a smaller redundancy at the expense of a slightly larger average list size