Inertial confinement fusion Randewich, Andrew; Lock, Rob; Garbett, Warren ...
Philosophical transactions of the Royal Society of London. Series A: Mathematical, physical, and engineering sciences,
11/2020, Letnik:
378, Številka:
2184
Journal Article
Political and commercial prospects for inertial fusion energy Holland, Andrew
Philosophical transactions of the Royal Society of London. Series A: Mathematical, physical, and engineering sciences,
11/2020, Letnik:
378, Številka:
2184
Journal Article
Recenzirano
Fusion energy holds the prospect of an energy source that is clean, safe, affordable and limitless. It will transform the global energy system. Today, around $1.5 billion in private capital has been ...invested in companies that are working on transformative approaches to fusion. Annually, even more than that is spent on fusion research by governments around the world. However, just achieving a scientific demonstration of fusion power will not be enough on its own to transition the global energy system. It will require innovations in the legal, regulatory, commercial and political spheres to support the massive deployment of fusion power that we know will be necessary to meet the global challenges of climate change and energy scarcity.
This article is part of a discussion meeting issue ‘Prospects for high gain inertial fusion energy (part 1)’.
We examine the characteristics that fusion-based generation technologies will need to have if they are to compete in the emerging low-carbon energy system of the mid-twenty-first century. It is ...likely that the majority of future electric energy demand will be provided by the lowest marginal cost energy technology—which in many regions will be stochastically varying renewable solar and wind electric generation coupled to systems that provide up to a few days of energy storage. Firm low-carbon or zero-carbon resources based on gas-fired turbines with carbon capture, advanced fission reactors, hydroelectric and perhaps engineered geothermal systems will then be used to provide the balance of load in a highly dynamic system operating in competitive markets governed by merit-order pricing mechanisms that select the lowest-cost supplies to meet demand. These firm sources will have overnight capital costs in the range of a few $/Watt, be capable of cycling down to a fraction of their maximum power output, operate profitably at low utilization fraction, and have a suitable unit size of order 100 MWₑ. If controlled fusion using either magnetic confinement or inertial confinement approaches is to have any chance of providing a material contribution to future electrical energy needs, it must demonstrate these key qualities and at the same time prove robust safety characteristics that avoid the perceived dread risk that plagues nuclear fission power, avoid the generation of long-lived radioactive waste and demonstrate highly reliable operations.
This article is part of a discussion meeting issue ‘Prospects for high gain inertial fusion energy (part 1)’.
Airborne particulate matter Harrison, Roy M.
Philosophical transactions of the Royal Society of London. Series A: Mathematical, physical, and engineering sciences,
10/2020, Letnik:
378, Številka:
2183
Journal Article
Recenzirano
Airborne particulate matter (PM) is a pollutant of concern not only because of its adverse effects on human health but because of its ability to reduce visibility and soil buildings and materials. It ...can be regarded as a suite of pollutants since PM covers a very wide range of particle sizes and also has a diverse chemical composition. Historically, much of the PM arose from coal burning and was measured as black smoke. However, in the second half of the twentieth century in developed countries, there was a reduction in black smoke emissions from coal burning and PM steadily became dominated by carbonaceous particles from road traffic exhaust and the secondary pollutants, ammonium salts and secondary organic carbon. This is exemplified by the composition of fine particles (referred to as PM2.5) as measured in London, Delhi and Beijing. Steadily, as control strategies have addressed the more tractable sources of emissions, so sources previously regarded as unconventional have emerged and have been seen to make a significant contribution to airborne PM concentrations. Among these are non-exhaust particles from road traffic, cooking aerosol and wood smoke. The particle size distribution of airborne PM is hugely diverse, ranging from newly formed particles of a few nanometres in diameter through to particles of tens of micrometres in diameter. There has been a great deal of interest in ultrafine (nano) particles because of suspicions of enhanced toxicity, and as traffic emissions decrease as a source, so regional nucleation processes have become much bigger relative contributors to particle number, but not mass.
This article is part of a discussion meeting issue ‘Air quality, past present and future’.
This paper focuses on the use of results of epidemiological studies to quantify the effects on health, particularly on mortality, of long-term exposure to air pollutants. It introduces health impact ...assessment methods, used to predict the benefits that can be expected from implementation of interventions to reduce emissions of pollutants. It also explains the estimation of annual mortality burdens attributable to current levels of pollution. Burden estimates are intended to meet the need to communicate the size of the effect of air pollution on public health to policy makers and others. The implications, for the interpretation of the estimates, of the assumptions and approximations underlying the methods are discussed. The paper starts with quantification based on results obtained from studies of the association of mortality risk with long-term average concentrations of particulate air pollution. It then tackles the additional methodological considerations that need to be addressed when also considering the mortality effects of other pollutants such as nitrogen dioxide (NO₂). Finally, approaches that could be used to integrate morbidity and mortality endpoints in the same assessment are touched upon.
This article is part of a discussion meeting issue ‘Air quality, past present and future’.
What does success look like for air quality policy? A perspective Monks, Paul S.; Williams, Martin L.
Philosophical transactions of the Royal Society of London. Series A: Mathematical, physical, and engineering sciences,
10/2020, Letnik:
378, Številka:
2183
Journal Article
Recenzirano
This paper explores the drivers and role of science in air quality policy over the last 100 years or so. Case studies on the smogs of Los Angeles and London, acid rain, health impacts of particulate ...matter, diesel and lead in fuel are used to explore the drivers and models for the interaction of science, evidence and air quality policy. It suggests there are two phases to air quality mitigation, the first driven by the air quality emergency as the pollution is visible and the effects can be relatively obvious and the second driven by science that is directed towards continuous improvement. A critical element of the ‘science phase’ is the evidence base, the models of evidence-based and -informed policy-making are explored with the conclusion that it is optimal when guided by the ideal of co-creation of knowledge and policy options between scientists and policy-makers. The future and wider drivers for air quality are detailed with a number of key areas for ‘success’ indicated as important for air quality policy development such as continuous improvement. Overall, we find there is tension between two factors: the ambition to reduce emissions, improve air quality and reduce the impacts on public health and the environment on one hand, and questions of cost, technical feasibility and societal acceptability on the other.
This article is part of a discussion meeting issue ‘Air quality, past present and future’.
On the limits of experimental knowledge Evans, P. W.; Thébault, K. P. Y.
Philosophical transactions of the Royal Society of London. Series A: Mathematical, physical, and engineering sciences,
08/2020, Letnik:
378, Številka:
2177
Journal Article
Recenzirano
To demarcate the limits of experimental knowledge, we probe the limits of what might be called an experiment. By appeal to examples of scientific practice from astrophysics and analogue gravity, we ...demonstrate that the reliability of knowledge regarding certain phenomena gained from an experiment is not circumscribed by the manipulability or accessibility of the target phenomena. Rather, the limits of experimental knowledge are set by the extent to which strategies for what we call ‘inductive triangulation’ are available: that is, the validation of the mode of inductive reasoning involved in the source-target inference via appeal to one or more distinct and independent modes of inductive reasoning. When such strategies are able to partially mitigate reasonable doubt, we can take a theory regarding the phenomena to be well supported by experiment. When such strategies are able to fully mitigate reasonable doubt, we can take a theory regarding the phenomena to be established by experiment. There are good reasons to expect the next generation of analogue experiments to provide genuine knowledge of unmanipulable and inaccessible phenomena such that the relevant theories can be understood as well supported.
This article is part of a discussion meeting issue ‘The next generation of analogue gravity experiments’.
Optical analogues of black-hole horizons Rosenberg, Yuval
Philosophical transactions of the Royal Society of London. Series A: Mathematical, physical, and engineering sciences,
08/2020, Letnik:
378, Številka:
2177
Journal Article
Recenzirano
Hawking radiation is unlikely to be measured from a real black hole, but can be tested in laboratory analogues. It was predicted as a consequence of quantum mechanics and general relativity, but ...turned out to be more universal. A refractive index perturbation produces an optical analogue of the black-hole horizon and Hawking radiation that is made of light. We discuss the central and recent experiments of the optical analogue, using handson physics. We stress the roles of classical fields, negative frequencies, ‘regular optics’ and dispersion. Opportunities and challenges ahead are briefly mentioned.
This article is part of a discussion meeting issue ‘The next generation of analogue gravity experiments’.
The case for a Casimir cosmology Leonhardt, Ulf
Philosophical transactions of the Royal Society of London. Series A: Mathematical, physical, and engineering sciences,
08/2020, Letnik:
378, Številka:
2177
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The cosmological constant, also known as dark energy, was believed to be caused by vacuum fluctuations, but naive calculations give results in stark disagreement with fact. In the Casimir effect, ...vacuum fluctuations cause forces in dielectric media, which is very well described by Lifshitz theory. Recently, using the analogy between geometries and media, a cosmological constant of the correct order of magnitude was calculated with Lifshitz theory (Leonhardt 2019 Ann. Phys. (New York) 411, 167973. (doi:10.1016/j.aop.2019.167973)). This paper discusses the empirical evidence and the ideas behind the Lifshitz theory of the cosmological constant without requiring prior knowledge of cosmology and quantum field theory.
This article is part of a discussion meeting issue ‘The next generation of analogue gravity experiments’.
Stokes, Tyndall, Ruskin and the nineteenth-century beginnings of climate science Cardoso, Silvana S. S.; Cartwright, Julyan H. E.; Huppert, Herbert E.
Philosophical transactions of the Royal Society of London. Series A: Mathematical, physical, and engineering sciences,
06/2020, Letnik:
378, Številka:
2174
Journal Article
Recenzirano
Although we humans have known since the first smokey campfires of prehistory that our activities might alter our local surroundings, the nineteenth century saw the first indications that humankind ...might alter the global environment; what we currently know as anthropogenic climate change. We are now celebrating the bicentenaries of three figures with a hand in the birth of climate science. George Stokes, John Tyndall and John Ruskin were born in August 1819, August 1820 and February 1819, respectively. We look back from the perspective of two centuries following their births. We outline their contributions to climate science: understanding the equations of fluid motion and the recognition of the need to collect global weather data together with comprehending the role in regulating terrestrial temperature played by gases in the atmosphere. This knowledge was accompanied by fears of the Earth’s regression to another ice age, together with others that industrialization was ruining humankind’s health, morals and creativity. The former fears of global cooling were justified but seem strange now that the balance has tipped so far the other way towards global warming; the latter, on the other hand, today seem very prescient.
This article is part of the theme issue ‘Stokes at 200 (Part 1)’.
