| 1. |
- Agarwal, S., et al.
(författare)
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Fluctuations in Arctic sea-ice extent : Comparing observations and climate models
- 2018
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Ingår i: Philosophical Transactions. Series A. - : Royal Society Publishing. - 1364-503X .- 1471-2962. ; 376:2129
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Tidskriftsartikel (refereegranskat)abstract
- The fluctuation statistics of the observed sea-ice extent during the satellite era are compared with model output from CMIP5 models using a multifractal time series method. The two robust features of the observations are that on annual to biannual time scales the ice extent exhibits white noise structure, and there is a decadal scale trend associated with the decay of the ice cover. It is shown that (i) there is a large inter-model variability in the time scales extracted from the models, (ii) none of the models exhibits the decadal time scales found in the satellite observations, (iii) five of the 21 models examined exhibit the observed white noise structure, and (iv) the multi-model ensemble mean exhibits neither the observed white noise structure nor the observed decadal trend. It is proposed that the observed fluctuation statistics produced by this method serve as an appropriate test bed for modelling studies.
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| 2. |
- Agrell, Erik, 1965, et al.
(författare)
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Implications of information theory in optical fibre communications
- 2016
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Ingår i: Philosophical Transactions of the Royal Society A: Mathematical, Physical and Engineering Sciences. - : The Royal Society. - 1364-503X .- 1471-2962. ; 374:2062
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Forskningsöversikt (refereegranskat)abstract
- Recent decades have witnessed steady improvements in our ability to harness the information-carrying capability of optical fibres. Will this process continue, or will progress eventually stall? Information theory predicts that all channels have a limited capacity depending on the available transmission resources, and thus it is inevitable that the pace of improvements will slow. However, information theory also provides insights into how transmission resources should, in principle, best be exploited, and thus may serve as a guide for where to look for better ways to squeeze more out of a precious resource. This tutorial paper reviews the basic concepts of information theory and their application in fibre-optic communications.
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| 3. |
- Alfredsson, P. Henrik, et al.
(författare)
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Wind farms in complex terrains : an introduction
- 2017
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Ingår i: Philosophical Transactions. Series A. - : ROYAL SOC. - 1364-503X .- 1471-2962. ; 375:2091
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Tidskriftsartikel (refereegranskat)abstract
- Wind energy is one of the fastest growing sources of sustainable energy production. As more wind turbines are coming into operation, the best locations are already becoming occupied by turbines, and wind-farm developers have to look for new and still available areas-locations that may not be ideal such as complex terrain landscapes. In these locations, turbulence and wind shear are higher, and in general wind conditions are harder to predict. Also, the modelling of the wakes behind the turbines is more complicated, which makes energy-yield estimates more uncertain than under ideal conditions. This theme issue includes 10 research papers devoted to various fluid-mechanics aspects of using wind energy in complex terrains and illustrates recent progress and future developments in this important field. This article is part of the themed issue 'Wind energy in complex terrains'.
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| 4. |
- Andersson, Ole, et al.
(författare)
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Geometric phases for mixed states of the Kitaev chain
- 2016
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Ingår i: Philosophical Transactions. Series A. - : The Royal Society. - 1364-503X .- 1471-2962. ; 374:2069
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Tidskriftsartikel (refereegranskat)abstract
- The Berry phase has found applications in building topological order parameters for certain condensed matter systems. The question whether some geometric phase for mixed states can serve the same purpose has been raised, and proposals are on the table. We analyze the intricate behaviour of Uhlmann’s geometric phase in the Kitaev chain at finite temperature, and then argue that it captures quite different physics from that intended. We also analyze the behaviour of a geometric phase introduced in the context of interferometry. For the Kitaev chain, this phase closely mirrors that of the Berry phase, and we argue that it merits further investigation.
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| 5. |
- Asano, Masanari, et al.
(författare)
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Three-body system metaphor for the two-slit experiment and Escherichia coli lactose-glucose metabolism
- 2016
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Ingår i: Philosophical Transactions. Series A. - : The Royal Society. - 1364-503X .- 1471-2962. ; 374:2068
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Tidskriftsartikel (refereegranskat)abstract
- We compare the contextual probabilistic structures of the seminal two-slit experiment (quantum interference experiment), the system of three interacting bodies and Escherichia coli lactose-glucose metabolism. We show that they have the same non-Kolmogorov probabilistic structure resulting from multi-contextuality. There are plenty of statistical data with non-Kolmogorov features; in particular, the probabilistic behaviour of neither quantum nor biological systems can be described classically. Biological systems (even cells and proteins) are macroscopic systems and one may try to present a more detailed model of interactions in such systems that lead to quantum-like probabilistic behaviour. The system of interactions between three bodies is one of the simplest metaphoric examples for such interactions. By proceeding further in this way (by playing with n-body systems) we shall be able to find metaphoric mechanical models for complex bio-interactions, e.g. signalling between cells, leading to non-Kolmogorov probabilistic data.
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| 6. |
- Bagarello, F., et al.
(författare)
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A model of adaptive decision-making from representation of information environment by quantum fields
- 2017
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Ingår i: Philosophical Transactions. Series A. - : The Royal Society Publishing. - 1364-503X .- 1471-2962. ; 375:2106
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Tidskriftsartikel (refereegranskat)abstract
- We present the mathematical model of decisionmaking (DM) of agents acting in a complex and uncertain environment (combining huge variety of economical, financial, behavioural and geopolitical factors). To describe interaction of agents with it, we apply the formalism of quantum field theory (QTF). Quantum fields are a purely informational nature. The QFT model can be treated as a far relative of the expected utility theory, where the role of utility is played by adaptivity to an environment (bath). However, this sort of utility- adaptivity cannot be represented simply as a numerical function. The operator representation in Hilbert space is used and adaptivity is described as in quantum dynamics. We are especially interested in stabilization of solutions for sufficiently large time. The outputs of this stabilization process, probabilities for possible choices, are treated in the framework of classical DM. To connect classical and quantum DM, we appeal to Quantum Bayesianism. We demonstrate the quantumlike interference effect in DM, which is exhibited as a violation of the formula of total probability, and hence the classical Bayesian inference scheme. This article is part of the themed issue 'Second quantum revolution: foundational questions'.
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| 7. |
- Blomqvist, Björn R. H., et al.
(författare)
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Inferring the dynamics of rising radical right-wing party support using Gaussian processes
- 2019
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Ingår i: Philosophical Transactions. Series A. - : ROYAL SOC. - 1364-503X .- 1471-2962. ; 377:2160
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Tidskriftsartikel (refereegranskat)abstract
- The use of classical regression techniques in social science can prevent the discovery of complex, nonlinear mechanisms and often relies too heavily on both the expertise and prior expectations of the data analyst. In this paper, we present a regression methodology that combines the interpretability of traditional, well used, statistical methods with the full predictability and flexibility of Bayesian statistics techniques. Our modelling approach allows us to find and explain the mechanisms behind the rise of Radical Right-wing Populist parties (RRPs) that we would have been unable to find using traditional methods. Using Swedish municipality-level data (2002-2018), we find no evidence that the proportion of foreign-born residents is predictive of increases in RRP support. Instead, education levels and population density are the significant variables that impact the change in support for the RRP, in addition to spatial and temporal control variables. We argue that our methodology, which produces models with considerably better fit of the complexity and nonlinearities often found in social systems, provides a better tool for hypothesis testing and exploration of theories about RRPs and other social movements. This article is part of the theme issue 'Coupling functions: dynamical interaction mechanisms in the physical, biological and social sciences'.
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| 8. |
- Breton, Simon-Philippe, et al.
(författare)
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A survey of modelling methods for high-fidelity wind farm simulations using large eddy simulation
- 2017
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Ingår i: Philosophical Transactions. Series A. - : ROYAL SOC. - 1364-503X .- 1471-2962. ; 375:2091
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Forskningsöversikt (refereegranskat)abstract
- Large eddy simulations (LES) of wind farms have the capability to provide valuable and detailed information about the dynamics of wind turbine wakes. For this reason, their use within the wind energy research community is on the rise, spurring the development of new models and methods. This review surveys the most common schemes available to model the rotor, atmospheric conditions and terrain effects within current state-of-the-art LES codes, of which an overview is provided. A summary of the experimental research data available for validation of LES codes within the context of single and multiple wake situations is also supplied. Some typical results for wind turbine and wind farm flows are presented to illustrate best practices for carrying out high-fidelity LES of wind farms under various atmospheric and terrain conditions. This article is part of the themed issue 'Wind energy in complex terrains'.
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| 9. |
- Caffarelli, Luis A., et al.
(författare)
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Regularity of free boundaries a heuristic retro
- 2015
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Ingår i: Philosophical Transactions. Series A. - : The Royal Society. - 1364-503X .- 1471-2962. ; 373:2050
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Forskningsöversikt (refereegranskat)abstract
- This survey concerns regularity theory of a few free boundary problems that have been developed in the past half a century. Our intention is to bring up different ideas and techniques that constitute the fundamentals of the theory. We shall discuss four different problems, where approaches are somewhat different in each case. Nevertheless, these problems can be divided into two groups: (i) obstacle and thin obstacle problem; (ii) minimal surfaces, and cavitation flow of a perfect fluid. In each case, we shall only discuss the methodology and approaches, giving basic ideas and tools that have been specifically designed and tailored for that particular problem. The survey is kept at a heuristic level with mainly geometric interpretation of the techniques and situations in hand.
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| 10. |
- Charette, M, et al.
(författare)
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Coastal ocean and shelf-sea biogeochemical cycling of trace elements and isotopes: lessons learned from GEOTRACES
- 2016
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Ingår i: Philosopical Transactions of the Royal Society A. - : The Royal Society. - 1364-503X. ; 374:2081
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Forskningsöversikt (refereegranskat)abstract
- Continental shelves and shelf seas play a central role in the global carbon cycle. However,their importance with respect to trace element and isotope (TEI) inputs to ocean basinsis less well understood. Here, we present major findings on shelf TEI biogeochemistryfrom the GEOTRACES programme as well as a proof of concept for a new method toestimate shelf TEI fluxes. The case studies focus on advances in our understanding of TEIcycling in the Arctic, transformations within a major river estuary (Amazon), shelf sedimentmicronutrient fluxes and basin-scale estimates of submarine groundwater discharge. Theproposed shelf flux tracer is 228-radium (T1/2 =5.75 yr), which is continuously supplied tothe shelf from coastal aquifers, sediment porewater exchange and rivers. Model-derived shelf228Ra fluxes are combined with TEI/ 228Ra ratios to quantify ocean TEI fluxes from thewestern North Atlantic margin. The results from this new approach agree well with previousestimates for shelf Co, Fe, Mn and Zn inputs and exceed published estimates of atmosphericdeposition by factors of approximately 3–23. Lastly, recommendations are made for additionalGEOTRACES process studies and coastal margin-focused section cruises that will help refinethe model and provide better insight on the mechanisms driving shelf-derived TEI fluxesto the ocean.This article is part of the themed issue ‘Biological and climatic impacts of ocean trace elementchemistry’.
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