315 research outputs found
Reversible heat production during electric double layer buildup depends sensitively on the electrolyte and its reservoir
No full textSeveral modern technologies for energy storage and conversion are based on the screening of electric charge on the surface of porous electrodes by ions in an adjacent electrolyte. This so-called electric double layer (EDL) exhibits an intricate interplay with the electrolyte’s temperature that was the focus of several recent studies. In one of them, Janssen et al. [Phys. Rev. Lett. 119, 166002 (2017)] experimentally determined the ratio rev/el of reversible heat flowing into a supercapacitor during an isothermal charging process and the electric work applied therein. To rationalize that data, here, we determine rev/el within different models of the EDL using theoretical approaches such as density functional theory (DFT) as well as molecular dynamics simulations. Applying mainly the restricted primitive model, we find quantitative support for a speculation of Janssen et al. that steric ion interactions are key to the ratio rev/el. Here, we identified the entropic contribution of certain DFT functionals, which grants direct access to the reversible heat. We further demonstrate how rev/el changes when calculated in different thermodynamic ensembles and processes. We show that the experiments of Janssen et al. are explained best by a charging process at fixed bulk density or in a “semi-canonical” system. Finally, we find that rev/el significantly depends on parameters such as pore and ion size, salt concentration, and valencies of the cations and anions of the electrolyte. Our findings can guide further heat production measurements and can be applied in studies on, for instance, nervous conduction, where reversible heat is a key element
Reversible Heating in Electric Double Layer Capacitors
No full textA detailed comparison is made between different viewpoints on reversible heating in electric double layer capacitors. We show in the limit of slow charging that a combined Poisson-Nernst-Planck and heat equation, first studied by d’Entremont and Pilon [J. Power Sources 246, 887 (2014)], recovers the temperature changes as predicted by the thermodynamic identity of Janssen et al. [Phys. Rev. Lett. 113, 268501 (2014)], and disagrees with the approximative model of Schiffer et al. [J. Power Sources 160, 765 (2006)] that predominates the literature. The thermal response to the adiabatic charging of supercapacitors contains information on electric double layer formation that has remained largely unexplored
Are EU spatial ex ante coexistence regulations proportional?
No full textThe EU is currently struggling to implement coherent coexistence regulations on genetically modified (GM) and non-GM crops in all member states. While it stresses that any approach needs to be “proportionate to the aim of achieving coexistence”, very few studies have actually attempted to assess whether the proposed spatial ex ante coexistence regulations (SEACERs) satisfy this proportionality condition. In this article, we define proportionality as a functional relationship which is weakly increasing in the incentives for coexistence. We propose a spatial framework based on an existing landscape and introduce the new concept of shadow factor as a measure for the opportunity costs induced by SEACERs. This enables comparing the proportionality of (i) rigid SEACERs which are based on large isolation distances imposed on GM farmers versus (ii) flexible SEACERs based on pollen barrier agreements between neighboring farmers. Our theoretical and empirical findings argue for flexibility as rigid SEACERs violate the proportionality condition and, hence, are not consistent with the objectives of the EU.policy analysis, GIS, shadow factor, Agricultural and Food Policy, Crop Production/Industries,
Risk and De-Collectivisation: Evidence from the Czech Republic
No full textThe replacement of wage-labour farms by family farms in Central and Eastern Europe during the transformation has been more limited than was initially expected. In this paper a formal framework is developed in order to analyse the behaviour of family farms and socialist-style farms in the presence of risk, given the typical post-socialist environment. Management incentives, ownership structure, lump-sum transfers and consumption choices are shown to have the potential to limit the size of family farms relative to socialist-style farms. The hypotheses are tested with survey data collected by the author in the Czech Republic.transition, agriculture, structural change, risk, survey data, Risk and Uncertainty, D21, D81, O18, Q12,
To be awarded, or Not to Be Awarded. Is that the Question?:Theoretical and Methodological Aspects of the Study of Literary and Translation Prizes in the Context of Cultural Transfer
No full textTo be awarded the Nobel Prize in Literature or not to be awarded. Is that the question? Is not every author overwhelmed by the mere thought of being awarded the Noble Prize in Literature? After all, it means more translations, a broader audience, honour, money and fame. One good example of a writer who benefitted from the prize is the Icelandic author Halldór Laxness (1902-1998). A hitherto unknown poet and novelist, he became world famous after receiving the award in 1955, after which his works were translated into more than 25 languages.1 There have also been authors, however, who were anything but honoured to be nominated. Undoubtedly, the most famous example is Jean-Paul Sartre (1905-1980), who refused the Nobel Prize in 1964 to maintain his intellectual credibility as an anti-bourgeois philosopher and activist
Economics of spatial coexistence of genetically modified and conventional crops: Oilseed rape in Central France
No full textEurope is currently struggling to implement coherent coexistence regulations on genetically modified (GM) and non-GM crops in all EU Member States. We conduct simulations with the software ArcView® on a GIS dataset of a hypothetical case of GM herbicide tolerant oilseed rape cultivation in Central France. Our findings show that rigid coexistence rules, such as large distance requirements, may impose a severe burden on GM crop production in Europe. These rules are not proportional to the farmers’ basic incentives for coexistence and hence not consistent with the objectives of the European Commission. More alarming, we show that in densely planted areas a domino-effect may occur. This effect raises coexistence costs and even adds to the non-proportionality of rigid coexistence regulations. Instead, we show that flexible measures would be preferable since they are proportional to the incentives for coexistence and, hence, less counterproductive for European agriculture.regulation, GIS modelling, domino-effect, Crop Production/Industries,
The impact of investor sentiment on security prices: examining the difference between value and growth stocks
No full textThe impact of entrepreneurial finance on the success of ventures - Evidence from the software industry
No full textIntention-Aware Routing to Minimise Delays at Electric Vehicle Charging Stations
No full textEn-route charging stations allow electric vehicles to greatly extend their range. However, as a full charge takes a considerable amount of time, there may be significant waiting times at peak hours. To address this problem, we propose a novel navigation system, which communicates its intentions (i.e., routing policies) to other drivers. Using these intentions, our system accurately predicts congestion at charging stations and suggests the most efficient route to its user. We achieve this by extending existing time-dependent stochastic routing algorithms to include the battery's state of charge and charging stations. Furthermore, we describe a novel technique for combining historical information with agent intentions to predict the queues at charging stations. Through simulations we show that our system leads to a significant increase in utility compared to existing approaches that do not explicitly model waiting times or use intentions, in some cases reducing waiting times by over 80% and achieving near-optimal overall journey times.Software and Computer TechnologyElectrical Engineering, Mathematics and Computer Scienc
From Frequency Domain to Time Transient Methods for Halide Perovskite Solar Cells: The Connections of IMPS, IMVS, TPC, and TPV
No full textThe correlation of different methods of measurement can become an important tool to identify the dominant physical elements that govern the electronic and ionic dynamics in perovskite solar cells. The diverse phenomena underlying the response of halide perovskite materials to different stimuli are reflected in time-domain measurements, where transients appear with time scales spanning orders of magnitude, from nanoseconds to hours. We discuss the connection between different frequency- and time-domain methods to probe the voltage and current response of halide perovskite solar cells to different small perturbations. To solve the frequency-to-time transformation, we start from models of the transfer function of intensity-modulated photocurrent spectroscopy (IMPS) and derive the associated impulse response function, the transient photocurrent (TPC), in response to a short light pulse. Similarly, we determine the transient photovoltage (TPV) starting from the intensity-modulated photovoltage spectroscopy (IMVS) transfer function. We also discuss the open-circuit voltage decays (OCVD). We first show the response of simple equivalent circuit models, and then we treat the full model for generation–diffusion–recombination of electrons that shows a spiraling loop in IMPS. This model gives rise to overshoots in the time domain
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