Journal articles on the topic 'Cell cycling performance simulation'
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Beltran, Diana, Yachao Zeng, Gang Wu, Xianglin Li, and Shawn Litster. "Degradation Acceleration-Factor Analysis for Platinum Group Metal (PGM)-Free Polymer Electrolyte Fuel Cell Cathodes." ECS Meeting Abstracts MA2022-02, no. 42 (October 9, 2022): 1602. http://dx.doi.org/10.1149/ma2022-02421602mtgabs.
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This work explores designs and methods that can mitigate degradation and can be used to expand models to predict PGM-free fuel cell degradation due to voltage cycling during accelerated stress tests (AST) and constant potential holds, specifically current density loss over time. The motivation behind investigating degradation mechanisms is that most of the recent advances have mostly focused on enhancing initial electrocatalytic activity, and not on catalyst stability. Advancements in catalyst stability are less substantial and are well below the level for commercialization. The objective is to determine the impact of the operating point on degradation rate in membrane electrode assemblies (MEAs) and to perform time-efficient evaluation of degradation acceleration factors on a single MEA. The preliminary AST cycling results show that reducing temperature and upper potential cycling limit considerably reduces degradation rates. This work can help identify operating points that optimize between performance and durability using empirical data. Ultimately, the correlations extracted from this work can be applied into drive-cycle models for PGM-free catalysts for simulation-based lifetime performance forecasting. This work was partially supported by the U.S. Department of Energy, Office of Energy Efficiency and Renewable Energy under grant DE-0008440 (Prime: University of Kansas).
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Cho, Kyusang, Chandran Balamurugan, Hana Im, and Hyeong-Jin Kim. "Ceramic-Coated Separator to Enhance Cycling Performance of Lithium-ion Batteries at High Current Density." Korean Journal of Metals and Materials 59, no. 11 (November 5, 2021): 813–20. http://dx.doi.org/10.3365/kjmm.2021.59.11.813.
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Given the global demand for green energy, the battery industry is positioned to be an important future technology. Lithium-ion batteries (LIBs), which are the most widely used battery in the market, are the focus of various research and development efforts, from materials to systems, that seek to improve their performance. The separator is one of the core materials in LIBs and is a significant factor in the lifespan of high-performance batteries. To improve the performance of present LIBs, electrochemical testing and related surface analyses of the separator is essential. In this paper, we prepared a ceramic (Boehmite, γ-AlOOH) coated polypropylene separator and a porous polyimide separator to compare their electrochemical properties with a commercialized polypropylene (PP) separator. The prepared separators were assembled into nickelmanganese-cobalt (NMC) cathode half-cell and full-cell lithium-ion batteries. Their cycling performances were evaluated using differential capacity and electrochemical impedance spectroscopy with ethylene carbonate:dimethylcarbonate (EC:DMC) electrolyte. The ceramic coated polypropylene separator exhibited the best cycle performance at a high 5 C rate, with high ionic conductivity and less resistive solid electrolyte interphase. Also, it was confirmed that a separator solid electrolyte interface (SSEI) layer formed on the separator with cycle repetition, and it was also confirmed that this phenomenon determined the cycle life of the battery depending on the electrolyte.
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Sosa, Jordan D., and Michael Aziz. "Title: Static Cell and Porous Electrode Model for Cycling Behavior of Aqueous Organic Redox Active Materials." ECS Meeting Abstracts MA2022-02, no. 64 (October 9, 2022): 2340. http://dx.doi.org/10.1149/ma2022-02642340mtgabs.
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Aqueous Organic Redox Flow Batteries (AORBs) have shown growing potential as a stationary energy storage technology for regulating intermittent renewable sources. For long charge/discharge duration systems, the capital cost of a redox flow battery asymptotically approaches the cost of the electroactive material.[i] Therefore, for commercialization of this technology, proper evaluation of the redox active electrolytes is needed. The capacity retention over time and over cycling is one of the most vital criteria for evaluation. For very stable electrolytes with fade rates less than about 10% per year, disentangling cycle-denominated and time-denominated fade can be very difficult for flow batteries due to longer cycle time and noise due to pumping and splashing. Thus, we have used a sealed, static, non-flow cell to achieve capacity measurements with greater cycling frequency and reduced noise, as shown in Figure 1. To isolate decomposition from crossover through the membrane or apparent capacity fade due to changes in the resistance of the cell, we use volumetrically unbalanced, compositionally symmetric cells with potentiostatic cycling.[iii] For proper capacity fade rate evaluation, material properties of the electrode and electrolyte should be considered when setting up cycling protocols because the amount of accessed charge depends on these properties. Thus, simulations from porous electrode models that consider these material properties can inform appropriate cycling conditions. Using Newman’s porous electrode theory[iv] to model our static cell, we have simulated the spatial distribution of ions and potentials over time in response to time-varying applied potentials. From the transient behavior, we simulated the potentiostatic cycling of these cells. The simulations show how the physics inside porous electrodes and cycling performance depend on material properties. For example, the diffusivities can affect the spatial distributions of ions across a porous electrode, as shown in Figure 2 (left), as well as the minimum acceptable time for cycling and the accessed capacity for given cycling parameters, as shown in Figure 2 (right). Using the same porous electrode model for simulations, we aim to show differences between apparent and real capacity fade. [i] F. R. Brushett, M. J. Aziz, and K. E. Rodby. ACS Energy Lett. 2020, 5, 879−884 [ii] D. G. Kwabi, Y. Ji, and M. J. Aziz. C hem. Rev. 2020, 120, 14, 6467–6489 [iii] M.A. Goulet and M. J. Aziz, “Flow Battery Molecular Reactant Stability Determined by Symmetric Cell Cycling Methods”. Journal of The Electrochemical Society, 165 (7) A1466-A1477 (2018) [iv] J. Newman and C. W. Tobias, J. Electrochem. Soc., 1962, 109, 1183 Figure 1
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Neyhouse, Bertrand J., Jonathan Lee, and Fikile R. Brushett. "Predicting Cell Cycling Performance in Redox Flow Batteries Using Reduced-Order Analytical Models." ECS Meeting Abstracts MA2022-01, no. 3 (July 7, 2022): 474. http://dx.doi.org/10.1149/ma2022-013474mtgabs.
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Achieving decarbonization across multiple sectors (e.g., electricity generation, transportation, manufacturing) requires widespread adoption of renewable energy technologies, which demand energy storage solutions to enable sustainable, reliable, and resilient power delivery.1 To this end, redox flow batteries (RFBs) are a promising grid-scale energy storage platform, owing to their improved scalability, simplified manufacturing, and long service life.2 However, state-of-the-art RFBs remain too expensive for broad adoption, motivating the development of novel electrolyte formulations and reactor designs to meet performance, cost, and scale targets for emerging applications.3 While many recently-reported next-generation materials offer short-term performance improvements and the potential for cost reductions when produced at-scale, they often complicate system operation over extended durations due to a multitude of interrelated parasitic processes (e.g., side reactions, crossover, species decomposition) which lead to capacity fade and efficiency losses.3,4 Such processes challenge the establishment of quantitative and unambiguous connections between individual component properties and overall cell behavior. Here, we aim to develop mathematical models that translate fundamental material properties to cell performance metrics, enabling more informed design criteria for system engineering. In this presentation, we introduce an analytically-derived, zero-dimensional modeling framework to predict cell cycling behavior in RFBs. While previously-developed zero- and one-dimensional models demonstrate accurate performance predictions when compared to experimental systems, they must solve coupled differential equations using numerical methods.5,6 As a result, these approaches become computationally expensive for multi-cycle simulations (i.e., 10s – 100s of cycles), frustrating their implementation in system design and optimization. By deriving analytical solutions to these models, we can markedly reduce computation times and enable analyses hitherto unachievable. To demonstrate the utility of this modeling framework, we explore several representative scenarios that examine the connection between RFB material properties, operating conditions, and performance (i.e., power output, accessible capacity, efficiency). Additionally, we investigate the impact of different parasitic processes on capacity fade, highlighting the effects of species decomposition and crossover in durational cell cycling. Finally, we discuss several modalities for expanding this framework to include additional sources of performance losses and for integrating these models into larger computational schemes (e.g., optimization, parameter estimation, techno-economic assessments). The mathematical models developed in this work have potential to advance foundational understanding in RFB design, leading to quantitatively informed selection criteria for emerging candidate materials. Acknowledgments This work was supported by the Joint Center for Energy Storage Research, an Energy Innovation Hub funded by the U.S. Department of Energy, Office of Science, Basic Energy Sciences. B.J.N gratefully acknowledges the NSF Graduate Research Fellowship Program under Grant Number 1122374. J.L gratefully acknowledges support from the MIT Materials Research Laboratory REU Program, as part of the MRSEC Program of the NSF under grant number DMR-14-19807. Any opinion, findings, and conclusions or recommendations expressed in this material are those of the authors and do not necessarily reflect the views of the NSF. References S. Chu and A. Majumdar, Nature, 488, 294–303 (2012). M. L. Perry and A. Z. Weber, J. Electrochem. Soc., 163, A5064–A5067 (2016). F. R. Brushett, M. J. Aziz, and K. E. Rodby, ACS Energy Lett., 5, 879–884 (2020). M. L. Perry, J. D. Saraidaridis, and R. M. Darling, Current Opinion in Electrochemistry, 21, 311–318 (2020). M. Pugach, M. Kondratenko, S. Briola, and A. Bischi, Applied Energy, 226, 560–569 (2018). S. Modak and D. G. Kwabi, J. Electrochem. Soc., 168, 080528 (2021).
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Mayur, Manik, Mathias Gerard, Pascal Schott, and Wolfgang Bessler. "Lifetime Prediction of a Polymer Electrolyte Membrane Fuel Cell under Automotive Load Cycling Using a Physically-Based Catalyst Degradation Model." Energies 11, no. 8 (August 8, 2018): 2054. http://dx.doi.org/10.3390/en11082054.
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One of the bottlenecks hindering the usage of polymer electrolyte membrane fuel cell technology in automotive applications is the highly load-sensitive degradation of the cell components. The cell failure cases reported in the literature show localized cell component degradation, mainly caused by flow-field dependent non-uniform distribution of reactants. The existing methodologies for diagnostics of localized cell failure are either invasive or require sophisticated and expensive apparatus. In this study, with the help of a multiscale simulation framework, a single polymer electrolyte membrane fuel cell (PEMFC) model is exposed to a standardized drive cycle provided by a system model of a fuel cell car. A 2D multiphysics model of the PEMFC is used to investigate catalyst degradation due to spatio-temporal variations in the fuel cell state variables under the highly transient load cycles. A three-step (extraction, oxidation, and dissolution) model of platinum loss in the cathode catalyst layer is used to investigate the cell performance degradation due to the consequent reduction in the electro-chemical active surface area (ECSA). By using a time-upscaling methodology, we present a comparative prediction of cell end-of-life (EOL) under different driving behavior of New European Driving Cycle (NEDC) and Worldwide Harmonized Light Vehicles Test Cycle (WLTC).
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Kim, Sang Cheol, and Yi Cui. "Probing Solvation Thermodynamics of Lithium Battery Electrolytes through Potentiometric Methods." ECS Meeting Abstracts MA2022-02, no. 2 (October 9, 2022): 164. http://dx.doi.org/10.1149/ma2022-022164mtgabs.
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The electrolyte is a principal component of a lithium battery that impacts almost every facet of the battery’s performance. Solvation of lithium ions in electrolyte solution is key to understanding the electrolyte, but our understanding of solvation lags behind its significance. Particularly, estimating solvation free energy has been largely limited to computational simulations. Despite their versatility, simulations can be computationally expensive, and experimental methods to complement simulations are desired. We have recently introduced a potentiometric technique to probe the relative solvation free energy of lithium ions in battery electrolytes. We devised an electrochemical cell composed of two half-cells, with symmetric electrodes but asymmetric electrolytes. Whereas the open circuit potential of a conventional lithium-ion battery measures the free energy differences of lithium ions in the two electrodes, our experimental setup measures the energy differences of the lithium ions in two different electrolytes. By measuring the cell potential with a reference electrolyte, we can quantitatively characterize lithium ion solvation energy of an electrolyte of interest. The effects of concentration, anion and solvent on solvation energy are explored and verified with simulations. Particularly, we establish a correlation between cell potential (Ecell) and cyclability of high-performance electrolytes for lithium metal anodes. We find that solvents with more negative cell potentials and positive solvation energies—those weakly binding to Li+—lead to improved cycling stability. Weaker solvents are conjectured to have more anion-rich solvation structures that lead to anion-derived solid-electrolyte interphases, a hypothesis supported by cryogenic electron microscopy. It reveals that weaker solvation is correlated to an inorganic anion-derived solid-electrolyte interphase that stabilizes cycling.
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Milanovic, Milos, and Verica Radisavljevic-Gajic. "Multi-Timescale-Based Partial Optimal Control of a Proton-Exchange Membrane Fuel Cell." Energies 13, no. 1 (December 30, 2019): 166. http://dx.doi.org/10.3390/en13010166.
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This paper presents a Proton-Exchange Membrane Fuel Cell (PEMFC) transient model in stack current cycling conditions and its partial optimal control. The derived model is used for a specific application of the recently published multistage control technique developed by the authors. The presented control-oriented transient PEMFC model is an extension of the steady-state control-oriented model previously established by the authors. The new model is experimentally validated for transient operating conditions on the Greenlight Innovation G60 testing station where the comparison of the experimental and simulation results is presented. The derived five-state nonlinear control-oriented model is linearized, and three clusters of eigenvalues can be clearly identified. This specific feature of the linearized model is known as the three timescale system. A novel multistage optimal control technique is particularly suitable for this class of systems. It is shown that this control technique enables the designer to construct a local LQR, pole-placement or any other linear controller type at the subsystem level completely independently, which further optimizes the performance of the whole non-decoupled system.
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Spitthoff, Lena, Paul R. Shearing, and Odne Stokke Burheim. "Temperature, Ageing and Thermal Management of Lithium-Ion Batteries." Energies 14, no. 5 (February 25, 2021): 1248. http://dx.doi.org/10.3390/en14051248.
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Heat generation and therefore thermal transport plays a critical role in ensuring performance, ageing and safety for lithium-ion batteries (LIB). Increased battery temperature is the most important ageing accelerator. Understanding and managing temperature and ageing for batteries in operation is thus a multiscale challenge, ranging from the micro/nanoscale within the single material layers to large, integrated LIB packs. This paper includes an extended literature survey of experimental studies on commercial cells investigating the capacity and performance degradation of LIB. It compares the degradation behavior in terms of the influence of operating conditions for different chemistries and cell sizes. A simple thermal model for linking some of these parameters together is presented as well. While the temperature appears to have a large impact on ageing acceleration above room temperature during cycling for all studied cells, the effect of SOC and C rate appear to be rather cell dependent.Through the application of new simulations, it is shown that during cell testing, the actual cell temperature can deviate severely from the reported temperature depending on the thermal management during testing and C rate. It is shown, that the battery lifetime reduction at high C rates can be for large parts due to an increase in temperature especially for high energy cells and poor cooling during cycling studies. Measuring and reporting the actual battery (surface) temperature allow for a proper interpretation of results and transferring results from laboratory experiments to real applications.
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Mehta, Rohit, and Amit Gupta. "(Digital Presentation) Simulating Coupled Effect of Heat Generation and Capacity Degradation on Performance of Lithium-Ion Cells." ECS Meeting Abstracts MA2022-01, no. 2 (July 7, 2022): 367. http://dx.doi.org/10.1149/ma2022-012367mtgabs.
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Lithium-ion batteries are gaining significant interest as energy storage devices in high power demand applications like power grids and EVs as the world seeks to reduce dependence on fossil fuels. High energy and power densities, high coulombic efficiency and low self-discharge of lithium-ion batteries make them a preferred choice in such applications. When a cell is cycled, various degradation processes occur, leading to a reduction in cell capacity over time. Among the various ageing mechanisms, electrolyte decomposition at the graphite electrode is the most significant contributor to capacity loss due to the consumption of cyclable lithium ions. Another mechanism for capacity loss is lithium plating on the surface of the graphite electrode particles and is observed under harsh cycling conditions or after extended cycling. These reactions lead to the formation of a passive layer, called the solid-electrolyte interface (SEI) layer, on the surface of the anode graphite particles. The ionic resistance offered by the SEI layer to the flow of lithium ions in the electrolyte leads to increased heat generation within the cell, thereby leading to higher cell temperature for the same operating conditions with cell ageing. Moreover, the ageing of the cell due to capacity loss, power reduction and impedance rise, is strongly dependent on the cell’s operating temperature and current. The internal cell temperature can be significantly different from its surface temperature for large-format cells when subjected to high current and different extent of forced cooling leading to a spatially varying degradation effects. Even though highly relevant, the coupled effect of current flow, heat generation and capacity fade have not been adequately examined in the literature. While several works have simulated the temperature distribution in large format cells [1,2] or capacity fade for cells [3] under isothermal conditions, very few have examined their coupled effect. Studies considering the coupled effect of capacity fade with heat generation have incorporated a pseudo-2D electrochemical degradation model [4,5]. The thermal model ranges from one to three-dimensional, with higher dimensional thermal models considering uniform heat generation within the cell. However, in a practical scenario, a large-format cell suffers from a non-uniform temperature distribution, leading to non-uniform electrochemical reactions and degradation. Hence, a detailed coupled thermo-electrochemical, capacity-fade model is required to understand cell degradation and temperature rise during its operational life. In a step towards this goal, a two-dimensional physics-based, coupled thermo-electrochemical model with capacity degradation will be demonstrated for cylindrical lithium-ion cells. The electrochemical model with capacity fade is based on the porous-electrode and concentrated solution theories [6]. The thermal model considers the effect of ohmic heat in various cell components and the reversible and irreversible heat of reactions in the electrodes. The contribution of side reactions in heat generation is incorporated. The effect of changing porosity and thermal and electronic impedance with ageing on the cell is considered in the model. The results will give a better understanding of (a) the safe operation of the cell as the internal temperature of the cell changes with ageing, and of (b) the dependence of cell ageing on temperature. Fig.1 shows the spatial distribution of temperature at the end of discharge for an LMO cell under different convective heat transfer coefficients. The cells were subjected to a 5C current at an ambient temperature of 25°C. While the temperature reached for a convective heat transfer coefficient h=5 W/m2.K is much higher, the temperature gradient developed is more significant for h=50 W/m2.K. This can be attributed to the increased Biot number for the cell under forced cooling. A difference of 8°C for h=50 W/m2.K between the internal and external cell temperature show that the capacity-fade model needs to consider the local temperature distribution within the cell for better prediction of cell degradation with cycling. References: [1] Pan, Y. W., Hua, Y., Zhou, S., He, R., Zhang, Y., Yang, S., Liu, X., Lian, Y., Yan, X. & Wu, B. (2020). Journal of Power Sources, 459, 228070. [2] Zhao, Y., Diaz, L. B., Patel, Y., Zhang, T., & Offer, G. J. (2019). Journal of The Electrochemical Society, 166(13), A2849. [3] Atalay, S., Sheikh, M., Mariani, A., Merla, Y., Bower, E., & Widanage, W. D. (2020). Journal of Power Sources, 478, 229026. [4] Xu, M., Wang, R., Zhao, P., & Wang, X. (2019). Journal of Power Sources, 438, 227015. [5] Jiang, G., Zhuang, L., Hu, Q., Liu, Z., & Huang, J. (2020). Applied Thermal Engineering, 171, 115080. [6] Rashid, M., & Gupta, A. (2014). ECS Electrochemistry Letters, 3(10), A95. Figure 1
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Li, Bin. "Unlocking Failure Mechanisms and Improvement of Practical Li-S Pouch Cells through in Operando Pressure Study." ECS Meeting Abstracts MA2022-01, no. 1 (July 7, 2022): 109. http://dx.doi.org/10.1149/ma2022-011109mtgabs.
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Lithium-sulfur (Li-S) batteries have been considered a promising candidate for next-generation high-energy density storage technology due to their low cost and high theoretical capacity. However, since 2017, more and more attentions have been paid to the gap of lab cell characterization (coin cell) and prototype cell (pouch cell) development since misinterpretations and false expectations are frequently reported: material property impacts are often over-interpreted, while parameters with indirect impact (e.g., electrode and separator porosity, tortuosity, and pressure on cell stack) are neglected. In order to accelerate Li-S battery commercialization, the rapid transfer of material-related concept discovered in coin cells to a pouch cell level is essential, as some problems ignored or deemed minimal at the smaller level could have a greater effect on the performance of the larger pouch cell. The issues existing in practical pouch cell should be discovered, which would shed light on further battery materials development, or inspire the novel approaches to identify cell failure and improve cell performances at the pouch cell level. Considering the gap between practical pouch cells and coin cells, in addition to the noticeable difference in electrode size (e.g., the electrode size of practical pouch cell is usually >100 times of that of coin cell), a much higher stack pressure (> 1Mpa) is usually applied inside the coin cell. It was taken for granted that stack pressure was playing a critical role, leading to inconsistent performance between pouch cells and coin cells. Furthermore, with increasing size of the cells (especially for multi-layer pouch cells), the electrolyte wettability needs to be taken seriously. Otherwise, the sulfur utilization would be largely reduced as ionic conduction pathways was significantly affected. Herein, we rationally designed two kinds of cathode: Non-calendared sulfur electrode (NCSE) and Calendared sulfur electrode (CSE). The former’s porosity (ε) and tortuosity (τ) were proven to change with stack pressures while the latter’s do not change by simulations based on micro-XCT results with in-situ pressure applied. These two sulfur cathodes provide preconditions to distinguish the effects of stack pressure and porosity/tortuosity on Li-S pouch cell performances. For the first time, through in-situ monitoring of pressure applied onto Li-S pouch cells, the failure mechanisms of Li-S pouch cells were deeply understood, and the approaches to improve Li-S pouch cell performances were identified. It is found that highly porous structures of cathodes/separators and slow electrolyte diffusion through cathodes/separators can both lead to poor initial wetting. Additionally, Li-metal anode dominates the thickness variation of the whole pouch cell, which is verified by in situ measured pressure variation. Consequently, a real-time approach that combined normalized pressure with dP/dV analysis is proposed and validated to diagnose the morphology evolution of Li-metal anode. Moreover, applied pressure and porosity/tortuosity ratio of the cathode are both identified as independent factors that influence anode performance. In addition to stabilizing anodes, high pressure is proven to improve the cathode connectivity and avoid cathode cracking over cycling, which improves the possibility of developing cathodes with high sulfur mass loading. This work provides insights into Li-S pouch cell design (e.g., cathode and separator) and highlights pathways to improve cell capacity and cycling performance with applied and monitored pressure. Figure 1
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Gurieff, Nicholas, Declan Finn Keogh, Mark Baldry, Victoria Timchenko, Donna Green, Ilpo Koskinen, and Chris Menictas. "Mass Transport Optimization for Redox Flow Battery Design." Applied Sciences 10, no. 8 (April 17, 2020): 2801. http://dx.doi.org/10.3390/app10082801.
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The world is moving to the next phase of the energy transition with high penetrations of renewable energy. Flexible and scalable redox flow battery (RFB) technology is expected to play an important role in ensuring electricity network security and reliability. Innovations continue to enhance their value by reducing parasitic losses and maximizing available energy over broader operating conditions. Simulations of vanadium redox flow battery (VRB/VRFB) cells were conducted using a validated COMSOL Multiphysics model. Cell designs are developed to reduce losses from pump energy while improving the delivery of active species where required. The combination of wedge-shaped cells with static mixers is found to improve performance by reducing differential pressure and concentration overpotential. Higher electrode compression at the outlet optimises material properties through the cell, while the mixer mitigates concentration gradients across the cell. Simulations show a 12% lower pressure drop across the cell and a 2% lower charge voltage for improved energy efficiency. Wedge-shaped cells are shown to offer extended capacity during cycling. The prototype mixers are fabricated using additive manufacturing for further studies. Toroidal battery designs incorporating these innovations at the kW scale are developed through inter-disciplinary collaboration and rendered using computer aided design (CAD).
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Schlegl, Harald, and Richard Dawson. "Finite element analysis and modelling of thermal stress in solid oxide fuel cells." Proceedings of the Institution of Mechanical Engineers, Part A: Journal of Power and Energy 231, no. 7 (June 20, 2017): 654–65. http://dx.doi.org/10.1177/0957650917716269.
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Durability and reliability of anode supported solid oxide fuel cell stacks have proven unsatisfactory in large-scale trials, showing rapid failure, thermal cycling intolerance and step change in electrochemical performance most likely related to mechanical issues. Monitoring and understanding the mechanical conditions in the stack especially during temperature changes can lead to improvements of the design and of the operating regime targeting maximum durability. Within this project modelling and simulation of thermal stresses within the different parts of the cells and the stack and the validation of these models play a key role and were performed in this work. The modelling and simulation of stress and strain have been carried out using the FEA software ABAQUS™. Model variations documented the importance of exact knowledge of material properties like Young’s modulus, Poisson’s ratio, thermal expansion coefficient, thermal conductivity and creep viscosity. The benefit of literature data for these properties is limited by the fact that all these properties are highly dependent on the composition of materials but also on details of the fabrication process like mixing, fabrication technique and sintering temperature and duration. The work presented here is an investigation into the modelling techniques, which can be most efficiently applied to represent anode supported solid oxide fuel cells and demonstrates the temperature gradient and constraint on the stresses experienced in a typical design. Comparing different meshing elements representing the cell parts thin shell elements (S4R) provided the most efficiently derived solution. Tensile stress is most significant in the cathode layers reaching 155 MPa at working conditions. The stress relieving effect of creep led to a reduction of stress by up to 20% after 1000 h at 750 ℃, reducing the tensile stress in the cathode area to maximal 121 MPa. Constraint between bipolar plates increases the tensile stress, especially in the cathode layers leading to a peak value of 161 MPa.
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Porter, Jason Morgan, Sean Skweres, and Lydia Meyer. "Measuring Lithium-Ion Transport Properties in Electrolytes Via in Situ Infrared Spectroscopy." ECS Meeting Abstracts MA2022-02, no. 6 (October 9, 2022): 625. http://dx.doi.org/10.1149/ma2022-026625mtgabs.
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Electrolyte transport capability is a critical measure of battery function for both current Li-ion technology and chemistries beyond Li-ion. Ion transport plays a vital role in fast-charging, lithium plating, and performance under extreme temperature and cycling conditions. Though traditional electrolytes have been widely studied, current experimental methods do not allow for simple measurements of transport properties, often requiring large electrolyte volumes, long experiment times, and a dilute assumption. In this research, we developed analytical models that accurately predict apparent diffusion coefficient and transference number from numerical models of electrolyte ion concentrations in a lithium symmetric cell. The first analytical model utilized one-dimensional diffusion to predict the transient response of lithium concentration in the bulk electrolyte to an applied current. The second analytical model predicted lithium-ion concentration decay in a Li/Li cell at the electrode surface following a brief current pulse. The analytical models were used to fit numerical finite difference simulations of Li/Li cell performance to predict transport properties. This result suggests that current pulse methods can be applied to experimentally ascertain electrolyte diffusion properties. A new diagnostic is under development for characterizing electrolyte transport properties, diffusion coefficient and transference number, using the current pulse method applied to an in situ symmetric Li/Li cell. This diagnostic utilizes Fourier transform infrared spectroscopy and attenuated total reflectance to measure transport properties with low volumes of electrolyte and short experiment times. This capability may enable simple and rapid measurement of transport properties for electrolyte candidate screening and enrich broader understanding of electrolyte transport.
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Tutone, Marco, Giulia Culletta, Luca Livecchi, and Anna M. Almerico. "A Definitive Pharmacophore Modelling Study on CDK2 ATP Pocket Binders: Tracing the Path of New Virtual High-Throughput Screenings." Current Drug Discovery Technologies 17, no. 5 (December 23, 2020): 740–47. http://dx.doi.org/10.2174/1570163816666190620113944.
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Cyclin Dependent Kinases-2 (CDK2) are members of serine/threonine protein kinases family. They play an important role in the regulation events of the eukaryotic cell division cycle, especially during the G1 to S phase transition. Experimental evidence indicate that excessive expression of CDK2s should cause abnormal cell cycle regulation. Therefore, since a long time, CDK2s have been considered potential therapeutic targets for cancer therapy. In this work, onehundred and forty-nine complexes of inhibitors bound in the CDK2-ATP pocket were submitted to short MD simulations (10ns) and free energy calculation. Comparison with experimental data (K<sub>i</sub>, K<sub>d</sub> and pIC<sub>50</sub>) revealed that short simulations are exhaustive to examine the crucial ligand-protein interactions within the complexes. Information collected on MD simulations of protein-ligand complexes has been used to perform a molecular modelling approach that incorporates flexibility into structure-based pharmacophore modelling (Common Hits Approach, CHA). The high number of pharmacophore models resulting from the MD simulation was thus reduced to a few representative groups of pharmacophore models. The performance of the models has been assessed by using the ROC curves analysis. This definitive set of validated pharmacophore models could be used to screen in-house and/or commercial datasets for detection of new CDK-2 inhibitors. We provide the models to all the researchers involved in this field.
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Nousch, Laura, Mathias Hartmann, and Alexander Michaelis. "Improvements of Micro-CHP SOFC System Operation by Efficient Dynamic Simulation Methods." Processes 9, no. 7 (June 26, 2021): 1113. http://dx.doi.org/10.3390/pr9071113.
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Solid Oxide Fuel Cell (SOFC) technology is of high interest for stationary decentralized generation of electricity and heat in combined heat and power systems (CHP) for the residential sector. Application scenarios for SOFC systems in an electricity-regulated mode play an important role, especially in places where an electrical grid connection is not available or rather unstable. The advantages of SOFC systems are the high fuel flexibility and the high efficiencies also under partial load operation compared to other decentralized power generation technologies. Due to the long, energy-consuming system heat-up and the limited partial load capability, SOFC systems do not reach the performance of conventional power generation technologies. Furthermore, stack thermal cycling is associated with power degradation and should be minimized. In this paper, the improvement of these drawbacks are investigated for hotbox-based SOFC systems in the 1 kWel-class for residential applications. Since experimental investigations of the high-temperature systems are limited, modeling tools are established, enabling the visualization of internal system characteristics and providing the opportunity to simulate system operation in critical regions. To achieve this, a methodology for dynamic SOFC system modeling in a process engineering manner is developed based on the modeling language Modelica. A suitable approach is particularly important for modeling and simulation of the strong thermal interaction between the hot system components within the hotbox. The parametrized and validated models are used for the investigation of different dynamic effects, such as the system heat-up and the operation in low partial load points. A second reduced thermal system model aims for annual simulations of the SOFC system together with a battery to investigate the number of thermal cycles and the advantage of a hot standby operation. As a result, it is found that an adequate control of the power input at the start-up device and the cathode air flow has a high improvement potential to increase the stack heating rate and accelerate the heat-up in an energy-saving way. The hotbox-internal thermal management is identified as a crucial issue to reach low partial load points. To avoid the risk of stack cooling, lower heat losses and/or additional heat sources are of importance. Furthermore, the robustness of the tail gas oxidizer is found to be crucial for a higher load flexibility during partial load and the end of life stack operation. The annual simulation results indicate that operating the battery hybrid system with a hot standby mode requires much lower battery capacity for a high grid independence and a complete avoidance of system shutdown and associated power degradation.
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Dunlap, Nathan A. "Structural and Electrochemical Analysis of Thick Laser Patterned Electrodes for Fast Charging Batteries." ECS Meeting Abstracts MA2022-01, no. 1 (July 7, 2022): 86. http://dx.doi.org/10.1149/ma2022-01186mtgabs.
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For widespread adoption of electric vehicles, lithium-ion batteries need to achieve energy densities of around 350 Wh/kg, cost less than $100/Wh, and be able to charge quickly within 15 minutes. The production of most inactive materials within modern Li-ion cells (e.g. separator, current collector, packaging) have already undergone tremendous optimization but many opportunities remain for improving the performance of the electrodes and reducing the cost and time of wetting, formation and aging processes. By increasing the thickness of electrodes clear opportunities exist for enhancing the energy densities of conventional cell materials and reducing cost. For example, doubling the thickness of electrodes in full cells from 50 μm to 100 μm can increase the energy density of the cell by about 16% and reduce the cost of the cell by 50% (from $249/kWh to $172/kWh)1. These benefits arise from increasing the ratio of electrode active material to inactive material within cells; however, increased thickness is often accompanied by reduced rate performance and increasingly difficult electrolyte wetting and formation processes due to the challenge of infiltrating the electrode pore structure with electrolyte and displacing gases during formation2. One emerging electrode processing technology involves the laser-ablation of small micro pores or channels into Li-ion battery electrodes to enhance their electrolyte wetting and rate performance. Pulsed lasers are increasingly being used in advanced manufacturing processes due to their ability to weld, sinter, or remove materials quickly and with very high precision. When applied to high energy density thick electrodes, micro-structuring by laser patterning has been shown to improve the rate capabilities of cells while maintaining high capacity retention3. These laser ablated pores or channels provide low tortuosity paths for lithium ions to reach deeper regions in the thick electrodes more quickly than before, limiting concentration gradients and thus reducing unwanted lithium plating at elevated rates. Despite these benefits, the utilization of ultrafast lasing ablation systems as an in-line technique to selectively remove patterned regions of active material from lithium-ion battery electrodes during production has not yet been widely adopted by the industry. In this work, we identify and manufacture laser-ablated 3D electrode architectures for enhanced Li+ transport and electrochemical performance with the hope of inspiring confidence in the benefits, practicality and cost effectiveness of the laser patterning technique. Preliminary modelling work at NREL has explored the limitations of planar electrodes for fast charge performance and the importance of microscale features for improving ion-transport4-8. With the correct pore/channel geometry, the energy density of ablated electrodes can be significantly improved compared to traditional architectures. We have combined simulation models and experimental data to optimize the 3-D laser patterning of our electrodes. Modelling elucidated the electrodes baseline transport limitations and quickly identified the most promising electrode architectures for favorable cost, energy- and power-density. Next, we used our benchtop ultrafast femtosecond laser ablation system to pattern our thick (ca. 100 µm) electrodes. After processing, the electrodes were inspected using cross-section scanning electron microscopy (SEM) so that ablation parameters such as laser wavelength, power and repetition rate could be optimized and distributions of feature sizes could be identified giving insight into the limitations of the laser system. We observed that the anode and cathode materials responded significantly different to the laser ablation process and that this must be considered during electrode preparation. Next, scanning electron microscopy with energy dispersive spectroscopy (SEM-EDS) and x-ray diffraction (XRD) were used to probe for local chemical or structural changes in the electrodes’ with patterning to determine if the remaining active materials experienced permanent laser-induced damages. Once successful achievement of the target electrode architecture was confirmed, the benefits of the achieved 3-D patterning were investigated by cycling the electrodes in full cell coin cells and comparing their performance against standard cells with unmodified electrodes (benchmark). Cycling data clearly shows improved rate performance and capacity retention derived from the patterning of the thick graphite and NMC electrodes. Direct structuring of the electrodes has improved their ion transport and reduced lithium concentration gradients (cell polarization) resulting in high specific energy- and high power-density. While clear evidence of rapid lithium plating was observed in the standard benchmark cells at rates exceeding 1C, this has been largely mitigated in the laser ablated electrodes. Lastly, we probed the wetting of these electrodes with electrochemical impedance spectroscopy to map in real time the improved rate and extent of wetting achieved through the adoption of our 3-D laser patterns. Achieving shorter wetting times will correspond to reductions in cell manufacturing costs and is expected to present a significant market advantage. Figure 1
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Gupta, Raghvendra, Rohit Mehta, Supreet Singh Bahga, and Amit Gupta. "(Digital Presentation) Thermal Behaviour Prediction of Commercial Lithium-Ion Cells Under Different C-Rate and Ambient Conditions Using Surrogate Modelling." ECS Meeting Abstracts MA2022-01, no. 2 (July 7, 2022): 389. http://dx.doi.org/10.1149/ma2022-012389mtgabs.
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Lithium-ion batteries (LIBs) have found widespread application in energy storage due to their high energy density, low self-discharge and low maintenance characteristics. However, the stability and longevity of the batteries under extreme operating conditions is yet to be fully understood. Numerous experimental and simulation studies have been performed to elucidate the effect of temperature, current, depth of discharge, and the number of cycles [1,2,3] on the performance of LIBs. These studies show that the solid-electrolyte interface (SEI) layer and gas formation accelerate at high C-rates due to increased electrolyte decomposition [4,5]. Consequently, the cell's internal resistance increases, resulting in ever-increasing irreversible heat generation inside the cell [6]. This heat generation leads to high internal temperature and a corresponding reduction in cell capacity. The data of cell temperature for a wide range of ambient temperatures and cycling rates is limited because cell performance is typically reported at room temperature. The design of battery packs for electric vehicles(EVs) is also based on test data taken at room conditions. Given that the cell's capacity, specific energy, maximum power output is bound to depend on C-rate and ambient temperature, it is necessary to test and design battery packs based on these parameters. The thermal characteristics of a lithium-ion cell can be predicted using a physics-based thermal model or data-driven methods (DDM) relying on empirical data. Experimental determination of internal cell parameters required in physics-based thermal models is challenging and time-consuming for commercial cells. On the other hand, DDM requires only cell cycling data at specific operating conditions, thereby eliminating the need for internal parameter estimation. This model predicts the experimental input and output data pattern and fits the response surface to estimate the unknown output. In this study, surrogate modelling has been employed to estimate the surface temperature, capacity, energy, and average power of commercial lithium-ion cells for different discharge currents and ambient temperatures. Surrogate modelling, a popular data analysis and reduced-order modelling technique, aims to find a global minimum of a particular objective function using a few objective function evaluations [7]. The surrogate-based model divides experimental data into training and test data sets. The training data set is employed to train the algorithm. After that, the testing data set is used to validate the model's accuracy. Experiments were performed to develop a surrogate model, with the number of experiments decided using the design of experiments[8] for a current range of 0.5C to 3C-rate and ambient temperature range of 0°C to 45°C . The cycling of cells was performed using a high current battery cycler (Arbin), and the ambient temperature was maintained using a thermal chamber (Cincinnati). The surface temperature of commercial 18650 (NMC811) lithium-ion cells was recorded using T-type thermocouples and a National Instruments DAQ module. A polynomial response surface was fitted using surrogate modelling on experimentally obtained data. The response surface shown in figure 1. contains nine data points for the preliminary study, sub-divided into a set of seven training and two testing data. The prediction error sum of squares (PRESS) is currently bounded within 10% due to the limited training data set availability and is expected to be within a band of 1% after adding data from ongoing experiments. The estimation of temperature, capacity, and specific energy can be used to optimize and develop an improved thermal management system for electric vehicles that works under various operating conditions. References Waldmann, T., Wilka, M., Kasper, M., Fleischhammer, M., & Wohlfahrt-Mehrens, M. (2014). Journal of Power Sources, 262, 129-135. Guan, T., Sun, S., Yu, F., Gao, Y., Fan, P., Zuo, P., Du,C., & Yin, G. (2018). Electrochimica Acta, 279, 204-212. Simolka, M., Heger, J. F., Traub, N., Kaess, H., & Friedrich, K. A. (2020). Journal of The Electrochemical Society, 167(11), 110502. Xu, B., Diao, W., Wen, G., Choe, S. Y., Kim, J., & Pecht, M. (2021). Journal of Power Sources, 510, 230390. Rashid, M., & Gupta, A. (2017). Electrochimica Acta, 231, 171-184. Leng, F., Tan, C. M., & Pecht, M. (2015). Scientific reports, 5(1), 1-12. Queipo, N. V., Haftka, R. T., Shyy, W., Goel, T., Vaidyanathan, R., & Tucker, P. K. (2005). Progress in aerospace sciences, 41(1), 1-28. Li, W., Xiao, M., Peng, X., Garg, A., & Gao, L. (2019). Applied Thermal Engineering, 147, 90-100. Figure 1
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Bradley, J. A., A. M. Anesio, J. S. Singarayer, M. R. Heath, and S. Arndt. "SHIMMER (1.0): a novel mathematical model for microbial and biogeochemical dynamics in glacier forefield ecosystems." Geoscientific Model Development Discussions 8, no. 8 (August 6, 2015): 6143–216. http://dx.doi.org/10.5194/gmdd-8-6143-2015.
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Abstract. SHIMMER (Soil biogeocHemIcal Model for Microbial Ecosystem Response) is a new numerical modelling framework which is developed as part of an interdisciplinary, iterative, model-data based approach fully integrating fieldwork and laboratory experiments with model development, testing, and application. SHIMMER is designed to simulate the establishment of microbial biomass and associated biogeochemical cycling during the initial stages of ecosystem development in glacier forefield soils. However, it is also transferable to other extreme ecosystem types (such as desert soils or the surface of glaciers). The model mechanistically describes and predicts transformations in carbon, nitrogen and phosphorus through aggregated components of the microbial community as a set of coupled ordinary differential equations. The rationale for development of the model arises from decades of empirical observation on the initial stages of soil development in glacier forefields. SHIMMER enables a quantitative and process focussed approach to synthesising the existing empirical data and advancing understanding of microbial and biogeochemical dynamics. Here, we provide a detailed description of SHIMMER. The performance of SHIMMER is then tested in two case studies using published data from the Damma Glacier forefield in Switzerland and the Athabasca Glacier in Canada. In addition, a sensitivity analysis helps identify the most sensitive and unconstrained model parameters. Results show that the accumulation of microbial biomass is highly dependent on variation in microbial growth and death rate constants, Q10 values, the active fraction of microbial biomass, and the reactivity of organic matter. The model correctly predicts the rapid accumulation of microbial biomass observed during the initial stages of succession in the forefields of both the case study systems. Simulation results indicate that primary production is responsible for the initial build-up of substrate that subsequently supports heterotrophic growth. However, allochthonous contributions of organic matter are identified as important in sustaining this productivity. Microbial production in young soils is supported by labile organic matter, whereas carbon stocks in older soils are more refractory. Nitrogen fixing bacteria are responsible for the initial accumulation of available nitrates in the soil. Biogeochemical rates are highly seasonal, as observed in experimental data. The development and application of SHIMMER not only provides important new insights into forefield dynamics, but also highlights aspects of these systems that require further field and laboratory research. The most pressing advances need to come in quantifying nutrient budgets and biogeochemical rates, in exploring seasonality, the fate of allochthonous deposition in relation to autochthonous production, and empirical studies of microbial growth and cell death, to increase understanding of how glacier forefield development contributes to the global biogeochemical cycling and climate in the future.
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Cheng, Ming, Tintula Kottakkat, and Christina Roth. "(Digital Presentation) The Influence of Post-Processing on Dynamic Hydrogen Bubble Templated Bi Modified Graphite Felt in Vanadium Redox Flow Batteries." ECS Meeting Abstracts MA2022-01, no. 3 (July 7, 2022): 463. http://dx.doi.org/10.1149/ma2022-013463mtgabs.
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Graphite felts (GFs) are a widely used electrode material in vanadium redox flow batteries (VRFB) by virtue of their high porosity, chemical stability, low cost and good electrical conductivity. However, the hydrophobicity and the low electrochemical activity are the main obstacles for the use of pristine GF in VFRB applications. To tackle such problems, bismuth has been reported to be a promising catalyst for V2+/ V3+ redox reactions [1]. Post-processing parameters, such as air/vacuum drying, exposure time to water during rinsing step, etc. can impact the performance of the Bi modified GFs, which will correspondingly affect morphology, purity and distribution of the catalyst leading to different kinetics. These parameters are rarely studied and reported in the literature. In this work, an effective synthesis method, the so-called dynamic hydrogen bubble template (DHBT) electrodeposition, has been employed for the deposition of high surface area Bi on GFs [2]. This method involves galvanostatic deposition of the metal at high current densities which is accompanied by hydrogen evolution, and the hydrogen bubbles serve as dynamic template for metal deposition. Cyclic Voltammetry (CV) and Electrochemical Impedance Spectroscopy (EIS) were carried out in a half-cell setup. The kinetics of Bi modified GFs could be obtained qualitatively by using Friedl’s method [3], in which the charge transfer resistance and double layer capacitance from impedance measurements are correlated, and quantitatively from the CV fitting routine in Polarographica developed by Tichter et al. [4]. The kinetic trends derived from both methods are consistent, with Polarographica exhibiting specific quantitative values as compared to Friedl’s method. It has been found that the post processing and drying conditions after Bi electrodeposition affect the performance of the GFs significantly. Therefore, the impacting parameters including electrochemically active surface area, Bi distribution, impurity, etc. are further studied by excluding certain parameters under different conditions. By the two previously mentioned methods of obtaining kinetics and the characterization of SEM and XRD, it is demonstrated that long time exposure to water during the rinsing step combined with vacuum drying after synthesis will promote a relatively higher kinetics than the other post-processing treatments on the Bi modified GFs. Full-cell tests with a VRFB test bench have been carried out. According to the polarization curves and charge-discharge curves at 25 mA/cm2 and 50 mA/cm2, the electrodes with Bi show pronounced advantages over pristine GF, namely, lower overpotential, lower charge voltage, higher discharge voltage and higher electrolyte utilization. Long term cycling will be compared and discussed in detail as well. [1] B. Li et al., “Bismuth Nanoparticle Decorating Graphite Felt as a High-Performance Electrode for an All-Vanadium Redox Flow Battery,” Nano Lett., vol. 13, no. 3, pp. 1330–1335, Mar. 2013, doi: 10.1021/nl400223v. [2] M. Yang, “Fern-shaped bismuth dendrites electrodeposited at hydrogen evolution potentials,” J. Mater. Chem., vol. 21, no. 9, p. 3119, 2011, doi: 10.1039/c0jm03213a. [3] J. Friedl and U. Stimming, “Determining Electron Transfer Kinetics at Porous Electrodes,” Electrochimica Acta, vol. 227, pp. 235–245, Feb. 2017, doi: 10.1016/j.electacta.2017.01.010. [4] T. Tichter et al., “Real-space simulation of cyclic voltammetry in carbon felt electrodes by combining micro X-ray CT data, digital simulation and convolutive modeling,” Electrochimica Acta, vol. 353, p. 136487, Sep. 2020, doi: 10.1016/j.electacta.2020.136487.
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Goda, Marwa S., Mohamed S. Nafie, Basma M. Awad, Maged S. Abdel-Kader, Amany K. Ibrahim, Jihan M. Badr, and Enas E. Eltamany. "In Vitro and In Vivo Studies of Anti-Lung Cancer Activity of Artemesia judaica L. Crude Extract Combined with LC-MS/MS Metabolic Profiling, Docking Simulation and HPLC-DAD Quantification." Antioxidants 11, no. 1 (December 22, 2021): 17. http://dx.doi.org/10.3390/antiox11010017.
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Artemisia judaica L. (Family: Asteraceae) exhibited antioxidant, anti-inflammatory, and antiapoptotic effects. The in vitro cytotoxic activity of A. judaica ethanolic extract was screened against a panel of cancer cell lines. The results revealed its cytotoxic activity against a lung cancer (A549) cell line with a promising IC50 of 14.2 μg/mL compared to doxorubicin as a standard. This was confirmed through the downregulation of antiapoptotic genes, the upregulation of proapoptotic genes, and the cell cycle arrest at the G2/M phase. Further in vivo study showed that a solid tumor mass was significantly reduced, with a tumor inhibition ratio of 54% relative to doxorubicin therapy in a Xenograft model. From a chemical point of view, various classes of natural products have been identified by liquid chromatography combined with tandem mass spectrometry (LC-MS/MS). The docking study of the detected metabolites approved their cytotoxic activity through their virtual binding affinity towards the cyclin-dependent kinase 2 (CDK-2) and epidermal growth factor receptor (EGFR) active sites. Finally, A. judaica is a fruitful source of polyphenols that are well-known for their antioxidant and cytotoxic activities. As such, the previously reported polyphenols with anti-lung cancer activity were quantified by high-performance liquid chromatography coupled with a diode array detector (HPLC-DAD). Rutin, quercetin, kaempferol, and apigenin were detected at concentrations of 6 mg/gm, 0.4 mg/gm, 0.36 mg/gm, and 3.9 mg/gm of plant dry extract, respectively. It is worth noting that kaempferol and rutin are reported for the first time. Herein, A. judaica L. may serve as an adjuvant therapy or a promising source of leading structures in drug discovery for lung cancer treatment.
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Danzi, Federico, Mafalda Valente, Sylwia Terlicka, and M. Helena Braga. "Sodium and potassium ion rich ferroelectric solid electrolytes for traditional and electrode-less structural batteries." APL Materials 10, no. 3 (March 1, 2022): 031111. http://dx.doi.org/10.1063/5.0080054.
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The transition to a sustainable society is vital and requires electrification. Sodium and potassium ion-based electrolytes will likely play an important role in energy storage as these elements are very abundant. The latter cations and chloride are especially interesting since life on the planet is somehow based on biological transfers of these ions through cell membranes. K+ is the key charge carrier in plants. Here, we characterize electrochemically, electrostatically, and structurally novel electrolytes, K3ClO and K2.99Ba0.005ClO, and compare their performance with Na3ClO and Na2.99Ba0.005ClO in symmetric and asymmetric structural electrode-less cells, such as K/K2.99Ba0.005ClO in a cellulose membrane/K, Na/Na2.99Ba0.005ClO in a cellulose membrane/Na, Al/K2.99Ba0.005ClO composite/Cu, and Al/Na2.99Ba0.005ClO composite/Cu, at temperatures that range from −45 to 65 °C. An ab initio molecular dynamics structural study followed by band structure determination using density functional theory and hybrid simulations allowed us to compare the amorphous character of the structures, bandgap, and electron localization function for both K3ClO at 25 °C and Na3ClO at 37 °C, temperatures at which preliminary studies indicate that these compounds are already amorphous. As in Na+-based electrolytes, the ferroelectric character of the K+-based electrolytes is well recognizable, especially at −45 °C, where the relative real permittivity achieves 1013 in K/K2.99Ba0.005ClO in cellulose membrane/K symmetric cells for an ionic conductivity of ∼120 mS/cm. As in Na+-based electrodes-less structural battery cells, self-charge and self-cycling phenomena are also demonstrated reinforcing the ferroelectric nature of the A3ClO (A = Li, Na, and K) family of electrolytes. These studies may contribute to understanding the K+ and Na+ transfer behavior in energy harvesting and storage as well as the biologic world.
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Palacios, Antonio, and Patrick Longhini. "Cycling Behavior in Near-Identical Cell Systems." International Journal of Bifurcation and Chaos 13, no. 09 (September 2003): 2719–32. http://dx.doi.org/10.1142/s0218127403008247.
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A generic pattern of collective behavior of symmetric networks of coupled identical cells is cycling behavior. In networks modeled by symmetric systems of differential (difference) equations, cycling behavior appears in the form of solution trajectories (orbits) that linger around symmetrically related steady-states (fixed points) or periodic solutions (orbits) or even chaotic attractors. In this last case, it leads to what is called "cycling chaos". In particular, Dellnitz et al. [1995] demonstrated the existence of cycling chaos in continuous-time three-cell systems modeled by Chua's circuit equations and Lorenz equations, while Palacios [2002, 2003] later demonstrated the existence of cycling chaos in discrete-time cell systems. In this work, we consider two issues that follow-up from these previous works. First of all, we address the generalization of existence of cycling behavior in continuous-time systems with more than three cells. We demonstrate that increasing the number of cells, while maintaining the same network connectivity used by Dellnitz et al. [1995], is not enough to sustain the nature of a cycle, in which only one cell is active at any given time. Secondly, we address the existence of cycling behavior in networks with near-identical cells, where the internal dynamics of each cell is governed by an identical model equation but with possibly different parameter values. We show that, under a new connectivity scheme, cycling behavior can also occur in networks with near-identical cells.
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Ginsburg, N., and P. Karpiuk. "Simulation of Human Performance on a Random Generation Task." Perceptual and Motor Skills 81, no. 3_suppl (December 1995): 1183–86. http://dx.doi.org/10.2466/pms.1995.81.3f.1183.
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A method was described for simulating human performance on a random generation task. It was illustrated by comparing protocols thus simulated with results produced by humans themselves. Using tests to represent scores on repetition, seriation, and cycling, simulated results were similar to those of actual subjects but differed significantly from scores taken directly from truly random numbers.
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Miyao, Toshihiro, Hanako Nishino, Hiroko Yamazaki, Satoko Sato, Kayoko Tamoto, Makoto Uchida, Akihiro Iiyama, Kazuya Shibanuma, and Naoto Koizumi. "Catalytic Activity for ORR of Pt Supported on Ordered Mesoporous Carbon with Network Structure." ECS Meeting Abstracts MA2022-02, no. 42 (October 9, 2022): 1578. http://dx.doi.org/10.1149/ma2022-02421578mtgabs.
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Introduction In order to realize carbon neutrality, working toward becoming a hydrogen-based society using renewable energy is essential, and hydrogen fuel cell vehicles will be one of the key devices. For further widespread deployment of fuel cell vehicles, cost reduction and performance enhancement of polymer electrolyte fuel cell (PEFC) systems are urgently needed. Recently, Pt/C-based electrocatalysts using mesoporous carbon as a support material have attracted attention, because well-designed mesopores can act as “accessible pores,” in which direct contact between ionomer and Pt surface is avoided, while the transport of protons, oxygen and generated water is not suppressed. Ordered mesoporous carbon (OMC) with a uniform nanopore structure is one of the ideal candidate materials for a catalyst support with accessible pores. However, with conventional synthesis methods, the typical OMC primary particle size is on the order of micrometers, and mass transport within the nanopores could be a difficult issue. In the present study, we focused on the development of OMC nanoparticles with a network structure. By use of nonionic surfactant micelles with phenol-formaldehyde resole resin as a carbon source, we obtained OMC nanoparticles with a novel hierarchical network structure (ns-OMC). To the best of our knowledge, there are no reports of the synthesis of ordered mesoporous carbon nanoparticles with a rigid network structure. In this study, in addition to the effect of synthesis conditions on the ns-OMC structure, a newly developed technique for the selective deposition of Pt nanoparticles within the ns-OMC nanopores, and the ORR activity of the Pt/ns-OMC catalysts, will be discussed in detail. Experimental Ns-OMC powder was synthesized with resol-nonionic surfactant micelles as a carbon source and structure directing agent. Resol-F127 (nonionic surfactant) micelles were synthesized by mixing phenol, formaldehyde, water and F127 with sodium hydroxide. After hydrothermal treatment of the mixture, the resulting solid was filtered and washed thoroughly and dried under vacuum. The obtained powder was carbonized at 700 ºC followed by annealing at 1000 ºC. Pt was deposited on the ns-OMC powder by the reverse micelle and colloid techniques. Cyclic voltammetry and linear sweep voltammetry were carried out in N2-saturated and O2-saturated 0.1 M HClO4 solution at 25 ºC using the conventional rotating disk electrode (RDE) technique. Potential step cycling measurements simulating load cycling between 0.6 V and 1.0 V vs. RHE were carried out according to the FCCJ protocol. Coating of the catalyst on a glassy carbon disk substrate was carried out by an electrospray (ES) coating technique developed by our group [1]. N2 adsorption measurement at liquid nitrogen temperature was carried out. The morphology of the Pt/ns-OMC was observed by scanning transmission electron microscope (STEM). Results and discussion As seen in the STEM images of the ns-OMC powder (Figure 1), the network structure formed by connection of OMC primary nanoparticles to form developed macropores is clearly observed. The OMC nanoparticles were tightly connected via a thick necking structure. The primary particle size of the OMC and neck thickness were controllable via the resol-F127 micelle concentration and the temperature during the hydrothermal treatment. Highly ordered nanopores were observed on the surface of the OMC particles, with a pore size of ca. 5 nm and an interpore distance of ca. 8 nm. The nanopores and the network structure were stable even after high temperature annealing at 1400 ºC. The BET specific surface area for the ns-OMC annealed at 1000 ºC was 814 m2 g-1, and the BJH pore size distribution curve of the ns-OMC showed a mesopore peak at 4.5 nm, which is in good agreement with the STEM observation. When Pt was deposited on the ns-OMC support, most of the Pt particles, with diameters of 4 to 5 nm, were dispersed on the support and, interestingly, located inside or right above the nanopore entrances. Careful STEM measurements revealed that the Pt particles were not deposited deeply within the OMC nanopores, but most were deposited at relatively shallow positions. RDE measurements revealed that the Pt/ns-OMC catalysts showed higher specific activity and mass activity for the ORR and much higher stability for the ECSA values during potential step cycling measurements in comparison with a commercial Pt/CB catalyst. The higher catalytic activity and durability observed for the Pt/ns-OMC catalyst may be due to a near-ideal distance between neighboring Pt particles deposited on the novel support. Aggregation and sintering of the Pt particles were successfully suppressed due to the nanopore structure. [1] S. Cho, K. Tamoto and M. Uchida, Energy Fuels, 34, 14853 (2020). Acknowledgement: This work was supported by the ECCEED’30-FC project from NEDO. Figure 1
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Asghari, S., and M. Salimi. "Finite element simulation of thermal barrier coating performance under thermal cycling." Surface and Coatings Technology 205, no. 7 (December 2010): 2042–50. http://dx.doi.org/10.1016/j.surfcoat.2010.08.099.
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Copetti, Cândice L. K., Fernando Diefenthaeler, Fernanda Hansen, Francilene G. K. Vieira, and Patricia F. Di Pietro. "Fruit-Derived Anthocyanins: Effects on Cycling-Induced Responses and Cycling Performance." Antioxidants 11, no. 2 (February 15, 2022): 387. http://dx.doi.org/10.3390/antiox11020387.
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Previous evidence has shown that the consumption of fruit-derived anthocyanins may have exercise benefits. This review aimed to summarize the effects of fruit-derived anthocyanins on cycling-induced responses and cycling performance. Medline, Science Direct, Cochrane Library, and SPORTDiscus online databases were searched. Nineteen articles met the inclusion criteria. The fruit-derived anthocyanins used in these studies were from cherry (n = 6), blackcurrant (n = 8), pomegranate (n = 2), açai (n = 1), and juçara fruit (n = 2), and were offered in juice, pulp, powder, freeze-dried powder, and extract form. The supplementation time ranged from acute consumption to 20 days, and the amount of anthocyanins administered in the studies ranged from 18 to 552 mg/day. The studies addressed effects on oxidative stress (n = 5), inflammation (n = 4), muscle damage (n = 3), fatigue (n = 2), nitric oxide biomarkers (n = 2), vascular function (n = 2), muscle oxygenation (n = 2), performance (n = 14), substrate oxidation (n = 6), and cardiometabolic markers (n = 3). The potential ergogenic effect of anthocyanin supplementation on cycling-induced responses seems to be related to lower oxidative stress, inflammation, muscle damage, and fatigue, and increased production of nitric oxide, with subsequent improvements in vascular function and muscle oxygenation leading to improved performance. In addition, the observed increase in fat oxidation can direct nutritional strategies to change the use of substrate and improve performance.
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Nguyen, Ngoc-Anh, Olivier Schneegans, Jouhaiz Rouchou, Raphael Salot, Yann Lamy, Jean-Marc Boissel, Marjolaine Allain, Sylvain Poulet, and Sami Oukassi. "(G02 Best Presentation Award Winner) Elaboration and Characterization of CMOS Compatible, Pico-Joule Energy Consumption, Electrochemical Synaptic Transistors for Neuromorphic Computing." ECS Meeting Abstracts MA2022-01, no. 29 (July 7, 2022): 1293. http://dx.doi.org/10.1149/ma2022-01291293mtgabs.
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Non-Von Neumann computing application constituted by artificial synapses based on electrochemical random-access memory (ECRAM) has aroused tremendous attention owing to its capability to perform parallel operations, thus reducing the cost of time and energy spent [1-3]. Existing ECRAM synapses comprise two-terminal memristors and three-terminal synaptic transistors (SynT). While low cost, scalability, and high density are the highlights for memristors, their nonlinear, asymmetric state modulation, high ON current withdrawal, and sneak path in crossbar array integration prevent them from becoming the ideal synaptic elements for artificial neural networks (ANN) [4]. SynT configuration, on the other hand, offers an additional electrolyte-gated control from which ion doping content can be monitored via redox reactions, thus decoupling write-read actions and improving the linearity of programming states [5-6]. Nevertheless, existing SynTs suffer from different integration issues stemming from liquid-based ionic conductors and manually exfoliated channels. Moreover, several kinds of SynTs possess highly conductive channels in the range of µS to mS, significantly scaling up the energy spent for analog states reading. Despite having numerous communications on the performance of different ECRAM, a comprehensive electrochemical view of ion intercalation into the active material, the main root of conductance modulation, is clearly missing. In this work, we present the elaboration procedure of an all-solid-state synaptic transistor composed of nanoscale electrolyte and channel layers. The devices have been elaborated on 8’’ Silicon wafers using microfabrication processes compatible with conventional semiconductor technology and CMOS back end of line (BEoL) integration. (Figure 1a) We demonstrate the excellent synaptic plasticity properties of short-term potentiation (STP) and long-term potentiation (LTP) of our SynT. We performed tests to study the correlation between linearity, asymmetry, and the number of analog states. By averaging the amount of injected ions per write operation, we estimated the energy consumed for switching among adjacent states of this device is 22.5 pJ, yielding area-normalized energy of 4 fJ/µm2. In addition, operating in the range of nS, our SynTs meet the critical criteria of low energy consumption for both write and read operations. Endurance was highlighted by cycling in ambient conditions with 100 states of potentiation and depression for over 1000 cycles with only a slight variation of Gmax/Gmin ratio of 6.2 % (Figure 1b, c). Approximately 95 % accuracy in MNIST pattern recognition test on ANN in the crossbar array configuration has been obtained by simulation with SynTs as synaptic elements reassured SynT is a promising candidate for future neuromorphic computing hardware. To shed light on the properties of intercalation phenomena of Li ions into the TiO2 layer, a further electrochemical study on a cell comprising Ti/TiO2/LiPON/Li corresponding to the SynT gate stack was performed. This understanding will help to elucidate the correlation with conductance modulation characteristics for a synaptic transistor. Multiple tests were carried out, including cyclic voltammetry (CV) with different scan rates, rate capability with Galvanostatic cycling with potential limit (GCPL), and electrochemical impedance spectroscopy (EIS) on different states of charge. A circuit model was introduced to fit the frequency response of the cell, and it explained well the behavior of charging capability at different OCV (Figure 1d). References [1] P. Narayanan et al., “Toward on-chip acceleration of the backpropagation algorithm using nonvolatile memory,” IBM J. Res. Dev., vol. 61, no. 4/5, p. 11:1-11:11, Jul. 2017, doi: 10.1147/JRD.2017.2716579. [2] J. Tang et al., “ECRAM as Scalable Synaptic Cell for High-Speed, Low-Power Neuromorphic Computing,” in 2018 IEEE International Electron Devices Meeting (IEDM), San Francisco, CA, Dec. 2018, p. 13.1.1-13.1.4. doi: 10.1109/IEDM.2018.8614551. [3] Y. Li et al., “In situ Parallel Training of Analog Neural Network Using Electrochemical Random-Access Memory,” Front. Neurosci., vol. 15, p. 636127, Apr. 2021, doi: 10.3389/fnins.2021.636127. [4] M. A. Zidan, H. A. H. Fahmy, M. M. Hussain, and K. N. Salama, “Memristor-based memory: The sneak paths problem and solutions,” Microelectron. J., vol. 44, no. 2, pp. 176–183, Feb. 2013, doi: 10.1016/j.mejo.2012.10.001. [5] Y. van de Burgt et al., “A non-volatile organic electrochemical device as a low-voltage artificial synapse for neuromorphic computing,” Nat. Mater., vol. 16, no. 4, pp. 414–418, Apr. 2017, doi: 10.1038/nmat4856. [6] E. J. Fuller et al., “Li-Ion Synaptic Transistor for Low Power Analog Computing,” Adv. Mater., vol. 29, no. 4, p. 1604310, Jan. 2017, doi: 10.1002/adma.201604310. Figure 1
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Ridgway, Paul, Honghe Zheng, A. F. Bello, Xiangyun Song, Shidi Xun, Jin Chong, and Vincent Battaglia. "Comparison of Cycling Performance of Lithium Ion Cell Anode Graphites." Journal of The Electrochemical Society 159, no. 5 (2012): A520—A524. http://dx.doi.org/10.1149/2.006205jes.
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Suriyakumar, Shruti, Kanagaraj Madasamy, Murugavel Kathiresan, Mohamed H. Alkordi, and A. Manuel Stephan. "Improved Cycling Performance of Lithium–Sulfur Cell through Supramolecular Interactions." Journal of Physical Chemistry C 122, no. 49 (October 22, 2018): 27843–49. http://dx.doi.org/10.1021/acs.jpcc.8b08785.
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Zheng, Honghe, Paul Ridgway, Xiangyun Song, Shidi Xun, Jin Chong, Gao Liu, and Vincent Battaglia. "Comparison of Cycling Performance of Lithium Ion Cell Anode Graphites." ECS Transactions 33, no. 29 (December 17, 2019): 91–100. http://dx.doi.org/10.1149/1.3564872.
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Bridgewater, Grace, Matthew J. Capener, James Brandon, Michael J. Lain, Mark Copley, and Emma Kendrick. "A Comparison of Lithium-Ion Cell Performance across Three Different Cell Formats." Batteries 7, no. 2 (June 8, 2021): 38. http://dx.doi.org/10.3390/batteries7020038.
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To investigate the influence of cell formats during a cell development programme, lithium-ion cells have been prepared in three different formats. Coin cells, single layer pouch cells, and stacked pouch cells gave a range of scales of almost three orders of magnitude. The cells used the same electrode coatings, electrolyte and separator. The performance of the different formats was compared in long term cycling tests and in measurements of resistance and discharge capacities at different rates. Some test results were common to all three formats. However, the stacked pouch cells had higher discharge capacities at higher rates. During cycling tests, there were indications of differences in the predominant degradation mechanism between the stacked cells and the other two cell formats. The stacked cells showed faster resistance increases, whereas the coin cells showed faster capacity loss. The difference in degradation mechanism can be linked to the different thermal and mechanical environments in the three cell formats. The correlation in the electrochemical performance between coin cells, single layer pouch cells, and stacked pouch cells shows that developments within a single cell format are likely to lead to improvements across all cell formats.
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Burgess, S. C. "Improving cycling performance with large sprockets." Sports Engineering 1, no. 2 (February 1999): 107–13. http://dx.doi.org/10.1046/j.1460-2687.1999.00012.x.
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Anam, Khairul, Chih Kuang Lin, and Anindito Purnowidodo. "Simulation of Cracking Behavior in Planar Solid Oxide Fuel Cell during Thermal Cycling." Key Engineering Materials 656-657 (July 2015): 484–89. http://dx.doi.org/10.4028/www.scientific.net/kem.656-657.484.
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Cracking behavior of positive electrode-electrolyte-negative electrode (PEN) assembly in a planar solid oxide fuel cells (pSOFC) during thermal cycling are investigated by using a commercial finite element analysis (FEA). The stress intensity factor for various combinations of surface crack size of 1 μm, 10 μm, and 100 μm and shape of semi-circular and semi-elliptical at highly stressed regions in the PEN are repeatedly calculated at room temperature and steady stage for twenty cycles. Simulation results indicate the stress intensity factor is significantly decreased at room temperature and is slightly increased at steady stage with increasing number of cycle. However, all the calculated stress intensity factors during thermal cycling in the present investigation are less than the corresponding fracture toughness given in the literature.
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Ridgway, Paul, Honghe Zheng, Gao Liu, Xiangyun Song, Abdelbast Guerfi, Patrick Charest, K. Zaghib, and Vincent Battaglia. "Performance of Lithium Ion Cell Anode Graphites Under Various Cycling Conditions." ECS Transactions 13, no. 19 (December 18, 2019): 1–12. http://dx.doi.org/10.1149/1.3018745.
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Roth, Christina, Ming Cheng, Marcus Gebhard, Jonathan Schneider, Tim Tichter, Andre Hilger, and Ingo Manke. "(Keynote) Pro and Con of Bi-Decorated Carbon Felts in Vanadium Redox Flow Batteries." ECS Meeting Abstracts MA2022-01, no. 48 (July 7, 2022): 2010. http://dx.doi.org/10.1149/ma2022-01482010mtgabs.
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Carbon felts are commonly utilized electrodes in vanadium flow batteries due to their low cost, light weight, good electronic conductivity, and chemical inertness. In contrast, their activity in catalyzing the vanadium redox reactions is less remarkable. In particular at the negative side, where V3+ reduction competes with the parasitic hydrogen evolution reaction (HER) at low potentials. In the literature, the addition of Bi3+ into the electrolyte [1] or its deposition on the felts has been suggested as a remedy. However, it is not clear yet, whether the Bi decoration remains stable with time and cycling and which mechanisms are responsible for the observed performance increase. The aim of this work is therefore to unravel more details about the catalyzing effect of Bi and its stability on the cell level. To this effect, the electrode kinetics with and without Bi decoration were studied comparing results obtained using Friedl’s method [2] with cyclic voltammetry (CV) data analyzed by the Polarographica curve fitting routine [3]. This approach can also be generalized to obtain precise kinetic information with other decorating metals. We furthermore applied negative dynamic hydrogen bubble templating (DHBT) deposition as an interesting way to coat commercially available carbon felts with a structured metallic layer of high surface area. Using this strategy, a significant positive effect was observed. However, the drying parameters and post-processing of the felts are important parameters which severely affect the final performance. In order to study the stability of Bi deposits in realistic battery experiments, in-situ synchrotron radiography has been used to monitor the Bi-decorated felts during charge-discharge cycles [4]. The figure demonstrates the effect of different flow rates on the Bi deposition patterns. Dark spots show metal-decorated areas within the felts at flow rates of 5 mlmin-1 (left), 15 mlmin-1 (middle) and 25 mlmin-1 (right). It can be easily seen that the operation conditions influence the felt decoration significantly, while Bi deposits dissolve and deposit during the charge-discharge routine. Further studies will be necessary to find out a) whether different deposit positions affect the performance enhancement and b) if DHBT-Bi remains more stable under operating conditions. In our presentation, we will not only focus on the materials, but also highlight techniques especially suitable for the stuctural and electrochemical analysis of felt electrodes. [1] B. Li, M. Gu, Z. Nie, Y. Shao, Q. Luo, X. Wei, X. Li, J. Xiao, C. Wang, V. Sprenkle, W. Wang, Bismuth Nanoparticle Decorating Graphite Felt as a High-Performance Electrode for an All-Vanadium Redox Flow Battery, Nano Letters 13(3) (2013) 1330-1335. [2] J. Friedl and U. Stimming, Determining Electron Transfer Kinetics at Porous Electrodes, Electrochim. Acta 227 (2017) 235–245. [3] T. Tichter, J. Schneider, D. Andrae, M. Gebhard, and C. Roth, Universal algorithm for simulating and evaluating cyclic voltammetry atmacroporous electrodes by considering random arrays of microelectrodes, ChemPhysChem 21 (2019) 428 –441. [4] M. Gebhard, T. Tichter, J. Schneider, J. Mayer, A. Hilger, M. Osenberg, M. Rahn, I. Manke, C. Roth J. Power Sources 478 (2020) 228695. Figure 1
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Selen, Willem J., and Jalal Ashayeri. "Manufacturing cell performance improvement: a simulation study." Robotics and Computer-Integrated Manufacturing 17, no. 1-2 (February 2001): 169–76. http://dx.doi.org/10.1016/s0736-5845(00)00051-x.
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Bobbert, Maarten F., L. J. Richard Casius, Stephan van der Zwaard, and Richard T. Jaspers. "Effect of vasti morphology on peak sprint cycling power of a human musculoskeletal simulation model." Journal of Applied Physiology 128, no. 2 (February 1, 2020): 445–55. http://dx.doi.org/10.1152/japplphysiol.00674.2018.
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Fascicle length of m. vastus lateralis in cyclists has been shown to correlate positively with peak sprint cycling power normalized for lean body mass. We investigated whether vasti morphology affects sprint cycling power via force-length and force-velocity relationships. We simulated isokinetic sprint cycling at pedaling rates ranging from 40 to 150 rpm with a forward dynamic model of the human musculoskeletal system actuated by eight leg muscles. Input of the model was muscle stimulation over time, which was optimized to maximize the average power output over a pedal cycle. This was done for a reference model and for models in which the vasti had equal volume but different morphology. It was found that models with longer muscle fibers but a reduced physiological cross-sectional area of the vasti produced a higher sprint cycling power. This was partly explained by better alignment of the peak power-pedaling rate curve of the vasti with the corresponding curves of the other leg muscles. The highest sprint cycling power was achieved in a model in which the increase in muscle fiber length of the vasti was accompanied by a concomitant shift in optimum knee angle. It was concluded that muscle mechanics can partly explain the positive correlations between fascicle length of m. vastus lateralis and normalized peak sprint cycling power. It should be investigated whether muscle fiber length of the vasti and optimum knee angle are suitable training targets for athletes who want to concurrently improve their sprint and endurance cycling performance. NEW & NOTEWORTHY We simulated isokinetic sprint cycling at pedaling rates ranging from 40 to 150 rpm with a forward dynamic model of the human musculoskeletal system actuated by eight leg muscles. We selectively modified vasti morphology: we lengthened the muscle fibers and reduced the physiological cross-sectional area. The modified model was able to produce a higher sprint cycling power.
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Das, Barnali, and Pralay Mitra. "High-Performance Whole-Cell Simulation Exploiting Modular Cell Biology Principles." Journal of Chemical Information and Modeling 61, no. 3 (March 8, 2021): 1481–92. http://dx.doi.org/10.1021/acs.jcim.0c01282.
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Bennett, George, and Cliff Elwell. "Effect of boiler oversizing on efficiency: a dynamic simulation study." Building Services Engineering Research and Technology 41, no. 6 (May 22, 2020): 709–26. http://dx.doi.org/10.1177/0143624420927352.
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Gas boilers dominate domestic heating in the UK, and significant efficiency improvements have been associated with condensing boilers. However, the potential remains for further efficiency improvement by refining the control, system specification and installation in real dwellings. Dynamic building simulation modelling, including detailed heating system componentry, enables a deeper analysis of boiler underperformance. This paper explores the link between the space heat oversizing of boilers and on/off cycling using dynamic simulation, and their subsequent effect on boiler efficiency and internal temperatures. At plant size ratio (PSR) 8.5 daily cycles numbered over 50, similar to median levels seen in real homes. Simulations show that typical oversizing (PSR >3) significantly increases cycling behaviour and brings an efficiency penalty of 6–9%. There is a clear link between raising PSR, increased cycling and an associated decreased efficiency; however, in the UK, boilers are regularly oversized with respect to space heating, especially combination boilers to cover peak hot water demand. Current legislation and labelling (ErP and SAP) overlook PSR as a determinant of system efficiency, failing to incentivise appropriate sizing. Reducing boiler oversizing through addressing installation practices and certification has the potential to significantly improve efficiency at low cost, decreasing associated carbon emissions. Practical application: This research provides the basis for a practical and cost effective means of assessing the potential for underperformance of boiler heating systems at the point of installation or refurbishment. By assessing the oversizing of the boiler with respect to space heating, unnecessary cycling and the associated efficiency penalty can be avoided. Plant size ratio, as an indicator of cycling potential, can be implemented in energy performance certificates (EPCs), through the standard assessment procedure (SAP), using existing data. The potential for real carbon savings in the existing boiler stock is considerable, and the findings have wider implications for next generation heating systems.
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Vilimek, M. "The simulation of cycling—optimization of sport performance based on different frequency of pedaling." Journal of Biomechanics 39 (January 2006): S549. http://dx.doi.org/10.1016/s0021-9290(06)85259-0.
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Deng, Changyu, and Wei Lu. "A Generic Battery Cycling Optimization Framework with Learned Sampling and Early Stopping Strategies." ECS Meeting Abstracts MA2022-02, no. 64 (October 9, 2022): 2334. http://dx.doi.org/10.1149/ma2022-02642334mtgabs.
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Battery optimization is a challenging task due to the large amount of cost and time required to evaluate different configurations in experiment or simulation. It is especially costly to optimize cycling performance since cycling the batteries is costly and time-consuming. In this project, we report an optimization framework with learned sampling and early stopping strategies, designed to optimize battery parameters in an efficient way to reduce total cycling time. It consists of a pruner and a sampler. The pruner stops unpromising cycling batteries to save the budget for further exploration. The sampler can predict the next promising configurations based on query history. The framework can deal with categorical, discrete and continuous parameters, and can run in an asynchronously parallel way to allow multiple simultaneous cycling cells. We demonstrated the performance by a parameter fitting problem for a calendar aging model. Comparisons with current methods are made to demonstrate the effectiveness of our method to reduce cycling time. Our framework can foster battery optimization in simulations and experiments.
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Goldthorpe, W. H., and J. K. Drohm. "APPLICATION OF THE BLACK OIL PVT REPRESENTATION TO SIMULATION OF GAS CONDENSATE RESERVOIR PERFORMANCE." APPEA Journal 27, no. 1 (1987): 370. http://dx.doi.org/10.1071/aj86032.
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Special attention must be paid to the generation of PVT parameters when applying conventional black oil reservoir simulators to the modelling of volatile oil and gas-condensate reservoirs. In such reservoirs phase behaviour is an important phenomenon and common approaches to approximating this, via the black oil PVT representation, introduce errors that may result in prediction of incorrect recoveries of surface gas and condensate. Further, determination of production tubing pressure drops for use in such simulators is also prone to errors. These affect the estimation of well potentials and reservoir abandonment pressures.Calculation of black oil PVT parameters by the method of Coats (1985) is shown to be preferred over conventional approaches, although the PVT parameters themselves lose direct physical meaning. It is essential that a properly tuned equation of state be available for use in conjunction with experimental data.Production forecasting based on simulation output requires further processing in order to translate the black oil surface phase fluxes into products such as sales gas, LPG and condensate. For gas-condensate reservoirs, such post-processing of results from the simulation of depletion or cycling above the dew point is valid. In principle it is invalid for cycling below the dew point but in practice it can still provide useful information.
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Wu, Lianhai, Martin Blackwell, Sarah Dunham, Javier Hernández-Allica, and Steve P. McGrath. "Simulation of Phosphorus Chemistry, Uptake and Utilisation by Winter Wheat." Plants 8, no. 10 (October 9, 2019): 404. http://dx.doi.org/10.3390/plants8100404.
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The phosphorus (P) supply from soils is crucial to crop production. Given the complexity involved in P-cycling, a model that can simulate the major P-cycling processes and link with other nutrients and environmental factors, e.g., soil temperature and moisture, would be a useful tool. The aim of this study was to describe a process-based P module added to the SPACSYS (Soil Plant and Atmosphere Continuum System) model and to evaluate its predictive capability on the dynamics of P content in crops and the impact of soil P status on crop growth. A P-cycling module was developed and linked to other modules included in the SPACSYS model. We used a winter wheat (Triticum aestivum, cv Xi-19) field experiment at Rothamsted Research in Harpenden to calibrate and validate the model. Model performance statistics show that the model simulated aboveground dry matter, P accumulation and soil moisture dynamics reasonably well. Simulated dynamics of soil nitrate and ammonium were close to the observed data when P fertiliser was applied. However, there are large discrepancies in fields without P fertiliser. This study demonstrated that the SPACSYS model was able to investigate the interactions between carbon, nitrogen, P and water in a single process-based model after the tested P module was implemented.
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Arano, Khryslyn G., Beth L. Armstrong, Ethan D. Boeding, Rachel J. Korkosz, Thomas F. Malkowski, and Gabriel M. Veith. "Covalent Surface Functionalization of Silicon for Enhanced Cycling Performance." ECS Meeting Abstracts MA2022-02, no. 3 (October 9, 2022): 245. http://dx.doi.org/10.1149/ma2022-023245mtgabs.
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Silicon (Si)-based negative electrodes often have these two prerequisites for improved performance: submicron or nanoscale dimension and additives (generally for electrolytes). In this work, a single approach was implemented to achieve the beneficial effects of both. Functionalized Si particles with an average diameter of less than 300 nm and with good polydispersity indices (0.2 to 0.3) were successfully generated by ball-milling the Si with vinylene carbonate (VC) and polyethylene oxide (PEO). Surface characterization using x-ray photoelectron spectroscopy (XPS) confirms the modification of the Si surface and the presence of the additives even after the electrode fabrication processes. We demonstrate through half-cell cycling that the addition of small amounts of VC result in increased specific capacities compared to the neat Si, i.e., ~370 mAh.g-1 higher for Si-VC electrode after the formation cycles. On the other hand, the presence of PEO introduces a passivating film on the surface of Si that hinders Li+ transport to the electrode as indicated by electrochemical impedance spectroscopy (EIS), resulting in reduced specific capacities, i.e., ~325 mAh.g-1 less relative to the neat Siafter formation. Nevertheless, the Si-PEO system exhibited the most promising cycling stability compared to the neat Si and Si-VC electrodes after extended cycling. Similar observations were drawn from full cell studies using high voltage NMC 811 cathodes, confirming the viability of our approach for the improvement of Si-based next generation lithium-ion batteries.
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Zhao, Sheng Nan, Hong Sun, Zheng Nan Jin, and Yu Hou Wu. "Simulation on Performance Curves of PEM Fuel Cell." Advanced Materials Research 287-290 (July 2011): 2477–80. http://dx.doi.org/10.4028/www.scientific.net/amr.287-290.2477.
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Proton exchange membrane (PEM) fuel cell is a clean electrochemical device with great prospect of application. Performance plays an important role in the application of PEM fuel cell. In this paper, a voltage characteristics model of PEM fuel cell is established, its performance curves is simulated, and the influence of the operating parameters on its performance is analyzed. The results show that the simulated performance curves of PEM fuel cell and its experimental performance curves have a high degree of agreement; when the cell temperature is lower than the gas humidification temperature, the drooping extent in the high current density section of performance curve increases with the increase of the gas humidification temperatures. When the cell temperature is equal to or higher than the gas humidification temperature, the slope of the straight line section of the performance curve decreases with the increase of the gas humidification temperatures. The performance curve of the PEM fuel cell goes up with the increase of reaction gas pressure. The results are very helpful to optimization and application of PEM fuel cell.
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Muhammad Habieb, Alvin, Muhammad Irwanto, Ilham Alkian, Fitri Khalimatus Sya’diyah, Hendri Widiyandari, and Vincensius Gunawan. "Dye-sensitized solar cell simulation performance using MATLAB." Journal of Physics: Conference Series 1025 (May 2018): 012001. http://dx.doi.org/10.1088/1742-6596/1025/1/012001.
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Shenoy, S. M., and R. G. Kasilingam. "Performance analysis of machine cell configurations using simulation." Computers & Industrial Engineering 21, no. 1-4 (January 1991): 279–83. http://dx.doi.org/10.1016/0360-8352(91)90102-c.
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Poyner, Mark A., Indumini Jayasekara, and Dale Teeters. "Fabrication of a Novel Nanostructured SnO2/LiCoO2 Lithium-Ion Cell." MRS Advances 1, no. 45 (2016): 3075–81. http://dx.doi.org/10.1557/adv.2016.537.
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ABSTRACTIncorporating nanotechnology processes and techniques to Li ion batteries has helped to improve the cycling capabilities and overall performance of several lithium ion battery chemistries. Nanostructuring a lithium ion battery’s anode and cathode, allows for extremely high surface area electrodes to be produced and utilized in many of these battery systems. Using a nanoporous Anodized Aluminum Oxide (AAO) membrane with nanopores of 200nm in diameter as a template, high surface area nanostructured electrode materials can be synthesized and utilized in a lithium ion cell. Through the use of RF magnetron sputter coating, these nanoporous AAO templates can be sputter coated with a thin film of active anode or cathode materials. The anode and cathode material in this research are SnO2 and LiCoO2, respectively. Nanostructured SnO2 has been investigated as an alternative high capacity anode to replace the more commonly used carbon based anodes of current lithium ion batteries. A novel nanostructured SnO2/LiCoO2 cell can be fabricated in a liquid electrolyte. The galvanostatic cell cycling performance will be discussed. Nanostructuring both electrode materials as well as the electrolyte can lead to a novel all-solid-state Li ion battery. Nanostructured SnO2 anode and LiCoO2 electrodes have been generated along with a polyethylene-oxide (PEO) based electrolyte nanoconfined in an AAO membrane, to generate a functioning nanostructured all-solid-state cell. The cell was investigated using AC impedance spectroscopy and galvanostatic cell cycling. The cycling results of both SnO2/LiCoO2 cell systems will be discussed.
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GFÖHLER, MARGIT, THOMAS ANGELI, and PETER LUGNER. "MODELING OF ARTIFICIALLY ACTIVATED MUSCLE AND APPLICATION TO FES CYCLING." Journal of Mechanics in Medicine and Biology 04, no. 01 (March 2004): 77–92. http://dx.doi.org/10.1142/s0219519404000850.
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Functional Electrical Stimulation (FES) enables paraplegics to move their paralyzed limbs; the skeletal muscles are artificially activated. The purpose of this study is to establish a mechanical muscle model for an artificially activated muscle, based on a Hill-type muscle model. In comparison to modeling a physiologically activated muscle, for the artificially activated muscle, a number of additional parameters and their influence on the force generation has to be considered. The model was implemented into a forward dynamic simulation of paraplegic cycling. The stimulation patterns were optimized for surface stimulation of gluteus maximus, quadriceps, hamstrings, and peronaeus reflex. A simulation of a startup with 50% of maximum activation in the optimized stimulation intervals analyses drive torques and mean power per cycle and the resulting riding performance of the rider-cycle system. For validation of the simulation, the results were compared to measurements of the forces applied to the crank during steady-state cycling of a paraplegic test person.
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Zeng, Ling Jun, and Hong Wu Huang. "The Research on the Fuel Performance of Fsae EFI Engine." Applied Mechanics and Materials 43 (December 2010): 647–50. http://dx.doi.org/10.4028/www.scientific.net/amm.43.647.
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For the modeled engine, the soft AVL-BOOST is applied to do the single-dimensional cycling simulation and calculation. And then the engine performance after assembling the improving limiter（its diameter is 20mm） is analyzed. According to the calculation and analysis, the torque and pneumatic efficiency are largely affected by limiter, the maximum torque and pneumatic efficiency decreases 20 percents and 30 percents respectively. The limiter not only improves the engine’s fuel performance, but also reduces its power performance.