Reduction of mean-square advection in turbulent passive scalar mixing

Direct numerical simulation data show that the variance of the coupling term in passive scalar advection by a random velocity field is smaller than it would be if the velocity and scalar fields were statistically independent. This effect is analogous to the "depression of nonlinearity" in hydrodynamic turbulence. We show that the trends observed in the numerical data are qualitatively consistent with the predictions of closure theories related to Kraichnan's direct interaction approximation. The phenomenon is demonstrated over a range of Prandtl numbers. In the inertial-convective range the depletion is approximately constant with respect to wavenumber. The effect is weaker in the Batchelor range

Open Access: An Analysis of Publisher Copyright and Licensing Policies in Europe, 2020

This report investigates the copyright retention policy amongst publishers, self-archiving policies and records publisher policies on open licensing, also as relating to the Plan S requirements on rights and licensing. It should be understood as a snapshot in time informing on the current policy status. It also provides policy development guidance to funders, institutions, publishers and their authors for positive change towards immediate OA. Over the past decade, Europe has seen a significant growth in activity to establish and advance Open Access (OA) policies, this includes the relatively recent formation of the funder coalition, cOAlition S, and its Plan S that is calling for immediate OA. However, to date, a lack of clarity has existed around our understanding of the extent to which publishers are responding to the OA policies of governments, funders and institutions to enable researchers to openly access and share their journal articles. From the outset, copyright has been a key challenge to OA; to ensure the widest possible reach of research through OA, widespread change is necessary. This report seeks to shed light on the extent to which publisher copyright, rights retention, self-archiving and open licensing policies, at this point in time, support this change. This report presents the results of a research study that was completed in the Summer of 2020 to explore copyright and licensing practices amongst the most prominent journal publishers in Europe and amongst European DOAJ journals. The study investigates copyright retention policy amongst publishers, self-archiving policies and records publisher policies on open licensing, also as relating to the Plan S requirements on rights and licensing. It should be understood as a snapshot in time informing on the current policy status. Whilst making concrete recommendations to far better enable immediate OA based on these findings, it also reports on instances where publisher policy changes are in the planning phase. This study seeks to provide policy development guidance to funders, institutions, publishers and their authors for positive change towards immediate OA

Open Access: An Analysis of Publisher Copyright and Licensing Policies in Europe, 2020

This report investigates the copyright retention policy amongst publishers, self-archiving policies and records publisher policies on open licensing, also as relating to the Plan S requirements on rights and licensing. It should be understood as a snapshot in time informing on the current policy status. It also provides policy development guidance to funders, institutions, publishers and their authors for positive change towards immediate OA. Over the past decade, Europe has seen a significant growth in activity to establish and advance Open Access (OA) policies, this includes the relatively recent formation of the funder coalition, cOAlition S, and its Plan S that is calling for immediate OA. However, to date, a lack of clarity has existed around our understanding of the extent to which publishers are responding to the OA policies of governments, funders and institutions to enable researchers to openly access and share their journal articles. From the outset, copyright has been a key challenge to OA; to ensure the widest possible reach of research through OA, widespread change is necessary. This report seeks to shed light on the extent to which publisher copyright, rights retention, self-archiving and open licensing policies, at this point in time, support this change. This report presents the results of a research study that was completed in the Summer of 2020 to explore copyright and licensing practices amongst the most prominent journal publishers in Europe and amongst European DOAJ journals. The study investigates copyright retention policy amongst publishers, self-archiving policies and records publisher policies on open licensing, also as relating to the Plan S requirements on rights and licensing. It should be understood as a snapshot in time informing on the current policy status. Whilst making concrete recommendations to far better enable immediate OA based on these findings, it also reports on instances where publisher policy changes are in the planning phase. This study seeks to provide policy development guidance to funders, institutions, publishers and their authors for positive change towards immediate OA

DEVELOPING CIRCULAR ECONOMY FOR THE RETAIL REFRIGERATION INDUSTRY: HOW FINANCIAL INCENTIVES COULD INFLUENCE REMANUFACTURiNG OF REFRIGERATED DISPLAY CABINETS IN THE UK

This paper examines how influential financial incentives could be in achieving a Circular Economy, with particular reference to the retail refrigeration industry. It underlines the potential monetary benefits for consumers who purchase remanufactured retail refrigeration equipment and highlights the potential financial incentives, which could help the producers of Refrigerated Display Cabinets (RDCs) to remanufacture. The Circular Economy is an economic and industrial system where resources are kept in use for as long as possible. This system is an alternative to the linear “take-make-use-dispose” path, which is adopted in many industries. Remanufacturing uses less energy and resources than the traditional linear approach, whilst making products that are considered to be as good as new. Due to the economical and environmental benefits the impetus to remanufacture is growing. The growth of the remanufacturing industry in the UK in relation to RDCs, could help to create a more sustainable and competitive retail industry. This paper evaluates the potential financial savings a supermarket could make from the purchase of remanufactured RDCs and proposes that financial incentives could help producers implement remanufacturing in their business models, in an attempt to encourage the industry to become more resource-efficient and circula

Pro-circular behaviours and refrigerated display cabinets: supporting resource efficiency in the retail refrigeration sector

There is a need to change business and behaviour models from the linear to the circular in order to conserve energy and resources. This paper identifies what pro-circular behaviours can influence the development of a Circular Economy, with particular reference to the retail refrigeration industry. Pro-circular behaviour is an action that is brought about due to the prioritisation of resource-efficiency with the aim of supporting the growth of a Circular Economy. A Circular Economy is an economic and industrial system where resources are kept in use for as long as possible. Greater uptake of alternative business models in the UK could help to create a more sustainable industry in retail refrigeration

Turbulence Fluctuations and New Universal Realizability Conditions in Modelling

General turbulent mean statistics are shown to be characterized by a variational principle. The variational functionals, or ``effective actions'', have experimental consequences for turbulence fluctuations and are subject to realizability conditions of positivity and convexity. An efficient Rayleigh-Ritz algorithm is available to calculate approximate effective actions within PDF closures. Examples are given for Navier-Stokes and for a 3-mode system of Lorenz. The new realizability conditions succeed at detecting {\em a priori} the poor predictions of PDF closures even when the classical 2nd-order moment realizability conditions are satisfied.Comment: 4 pages, LaTeX (Version 2.09), 3 figures, Postscript, Submitted to Phys. Rev. Let

Fluctuations in the Irreversible Decay of Turbulent Energy

A fluctuation law of the energy in freely-decaying, homogeneous and isotropic turbulence is derived within standard closure hypotheses for 3D incompressible flow. In particular, a fluctuation-dissipation relation is derived which relates the strength of a stochastic backscatter term in the energy decay equation to the mean of the energy dissipation rate. The theory is based on the so-called ``effective action'' of the energy history and illustrates a Rayleigh-Ritz method recently developed to evaluate the effective action approximately within probability density-function (PDF) closures. These effective actions generalize the Onsager-Machlup action of nonequilibrium statistical mechanics to turbulent flow. They yield detailed, concrete predictions for fluctuations, such as multi-time correlation functions of arbitrary order, which cannot be obtained by direct PDF methods. They also characterize the mean histories by a variational principle.Comment: 26 pages, Latex Version 2.09, plus seceq.sty, a stylefile for sequential numbering of equations by section. This version includes new discussion of the physical interpretation of the formal Rayleigh-Ritz approximation. The title is also change

The Position of High Frequency Waves with Respect to the Granulation Pattern

High frequency velocity oscillations were observed in the spectral lines Fe I 543.45nm and 543.29nm, using 2D spectroscopy with a Fabry- Perot and speckle reconstruction, at the VTT in Tenerife. We investigate the radial component of waves with frequencies in the range 8 - 22mHz in the internetwork, network and a pore. We find that the occurrence of waves do not show any preference on location and are equally distributed over down-flows and up-flows, regardless of the activity of the observed area in the line of Fe I 543.45nm. The waves observed in the lower formed line of Fe I 543.29nm seem to appear preferentially over down-flows.Comment: Article has 12 pages and 7 images. It is accepted in Solar Physics Journa

The geometry of a vorticity model equation

We provide rigorous evidence of the fact that the modified Constantin-Lax-Majda equation modeling vortex and quasi-geostrophic dynamics describes the geodesic flow on the subgroup of orientation-preserving diffeomorphisms fixing one point, with respect to right-invariant metric induced by the homogeneous Sobolev norm $H^{1/2}$ and show the local existence of the geodesics in the extended group of diffeomorphisms of Sobolev class $H^{k}$ with $k\ge 2$.Comment: 24 page