19 research outputs found
Fuzzy clustering with spatial correction and its application to geometallurgical domaining
Published online: 25 July 2018This paper describes a proposed method for clustering attributes on
the basis of their spatial variability and the uncertainty of cluster member-
ship. The method is applied to geometallurgical domaining in mining ap-
plications. The main objective of geometallurgical clustering is to ensure
consistent feed to a processing plant by minimising transitions between
di erent types of feed coming from di erent domains (clusters). For this
purpose, clusters should contain not only similar geometallurgical char-
acteristics but also be located in as few contiguous and compact spatial
locations as possible so as to maximise the homogeneity of ore delivered
to the plant. Most existing clustering methods applied to geometallurgy
have two problems. Firstly, they are unable to di erentiate subsets of
attributes at the cluster level and therefore cluster membership can only
be assigned on the basis of exactly identical attributes, which may not be
the case in practice. Secondly, as they do not take account of the spatial
relationships they can produce clusters which may be spatially dispersed
and/or overlapped. In the work described in this paper a new clustering
method is introduced that integrates three distinct steps to ensure qual-
ity clustering. In the rst step, fuzzy membership information is used to
minimise compactness and maximise separation. In the second step, the
best subsets of attributes are de ned and applied for domaining purposes.
These two steps are iterated to convergence. In the nal step a graph-
based labelling method, which takes spatial constraints into account, is
used to produce the nal clusters. Three examples are presented to illus-
trate the application of the proposed method. These examples demon-
strate that the proposed method can reveal useful relationships among
geometallurgical attributes within a clear and compact spatial structure.
The resulting clusters can be used directly in mine planning to optimise
the ore feed to be delivered to the processing plant.E. Sepúlveda, P. A. Dowd, C. X
Heavy quarkonia in a medium as a quantum dissipative system: Master-equation approach
The problem of the evolution of a heavy quarkonium in a medium can be recast
as that of a quantum dissipative system. Within the framework of the
master-equation approach to open quantum systems, we consider the real-time
dynamics of quarkonia. We find that in a plasma at fixed temperature, the
populations of the various quarkonium states evolve together, while their
momentum distribution satisfies a Fokker-Planck equation.Comment: 12 pages, 8 figures. Version 2 matches the published versio
Working paper analysing the economic implications of the proposed 30% target for areal protection in the draft post-2020 Global Biodiversity Framewor
58 pages, 5 figures, 3 tables- The World Economic Forum now ranks biodiversity loss as a top-five risk to the global economy, and the draft post-2020 Global Biodiversity Framework proposes an expansion of conservation areas to 30% of the earth’s surface by 2030 (hereafter the “30% target”), using protected areas (PAs) and other effective area-based conservation measures (OECMs). - Two immediate concerns are how much a 30% target might cost and whether it will cause economic losses to the agriculture, forestry and fisheries sectors. - Conservation areas also generate economic benefits (e.g. revenue from nature tourism and ecosystem services), making PAs/Nature an economic sector in their own right. - If some economic sectors benefit but others experience a loss, high-level policy makers need to know the net impact on the wider economy, as well as on individual sectors. [...]A. Waldron, K. Nakamura, J. Sze, T. Vilela, A. Escobedo, P. Negret Torres, R. Button, K. Swinnerton, A. Toledo, P. Madgwick, N. Mukherjee were supported by National Geographic and the Resources Legacy Fund. V. Christensen was supported by NSERC Discovery Grant RGPIN-2019-04901. M. Coll and J. Steenbeek were supported by EU Horizon 2020 research and innovation programme under grant agreement No 817578 (TRIATLAS). D. Leclere was supported by TradeHub UKRI CGRF project. R. Heneghan was supported by Spanish Ministry of Science, Innovation and Universities, Acciones de Programacion Conjunta Internacional (PCIN-2017-115). M. di Marco was supported by MIUR Rita Levi Montalcini programme. A. Fernandez-Llamazares was supported by Academy of Finland (grant nr. 311176). S. Fujimori and T. Hawegawa were supported by The Environment Research and Technology Development Fund (2-2002) of the Environmental Restoration and Conservation Agency of Japan and the Sumitomo Foundation. V. Heikinheimo was supported by Kone Foundation, Social Media for Conservation project. K. Scherrer was supported by the European Research Council (ERC) under the European Union’s Horizon 2020 research and innovation programme under grant agreement No 682602. U. Rashid Sumaila acknowledges the OceanCanada Partnership, which funded by the Social Sciences and Humanities Research Council of Canada (SSHRC). T. Toivonen was supported by Osk. Huttunen Foundation & Clare Hall college, Cambridge. W. Wu was supported by The Environment Research and Technology Development Fund (2-2002) of the Environmental Restoration and Conservation Agency of Japan. Z. Yuchen was supported by a Ministry of Education of Singapore Research Scholarship Block (RSB) Research FellowshipPeer reviewe
Rising rural body-mass index is the main driver of the global obesity epidemic in adults
Body-mass index (BMI) has increased steadily in most countries in parallel with a rise in the proportion of the population who live in cities 1,2 . This has led to a widely reported view that urbanization is one of the most important drivers of the global rise in obesity 3�6 . Here we use 2,009 population-based studies, with measurements of height and weight in more than 112 million adults, to report national, regional and global trends in mean BMI segregated by place of residence (a rural or urban area) from 1985 to 2017. We show that, contrary to the dominant paradigm, more than 55 of the global rise in mean BMI from 1985 to 2017�and more than 80 in some low- and middle-income regions�was due to increases in BMI in rural areas. This large contribution stems from the fact that, with the exception of women in sub-Saharan Africa, BMI is increasing at the same rate or faster in rural areas than in cities in low- and middle-income regions. These trends have in turn resulted in a closing�and in some countries reversal�of the gap in BMI between urban and rural areas in low- and middle-income countries, especially for women. In high-income and industrialized countries, we noted a persistently higher rural BMI, especially for women. There is an urgent need for an integrated approach to rural nutrition that enhances financial and physical access to healthy foods, to avoid replacing the rural undernutrition disadvantage in poor countries with a more general malnutrition disadvantage that entails excessive consumption of low-quality calories. © 2019, The Author(s)
Asymptotic Behavior of Solutions to the Drift-Diffusion Equation with Critical Dissipation
Weak compactness techniques and coagulation equations
International audienceSmoluchowski's coagulation equation is a mean-field model describing the growth of clusters by successive mergers. Since its derivation in 1916 it has been studied by several authors, using deterministic and stochastic approaches, with a blossoming of results in the last twenty years. In particular, the use of weak -compactness techniques led to a mature theory of weak solutions and the purpose of these notes is to describe the results obtained so far in that direction, as well as the mathematical tools used