181 research outputs found

    KAM Theorem and Quantum Field Theory

    Full text link
    We give a new proof of the KAM theorem for analytic Hamiltonians. The proof is inspired by a quantum field theory formulation of the problem and is based on a renormalization group argument treating the small denominators inductively scale by scale. The crucial cancellations of resonances are shown to follow from the Ward identities expressing the translation invariance of the corresponding field theory.Comment: 32 page

    Random Curves by Conformal Welding

    Get PDF
    We construct a conformally invariant random family of closed curves in the plane by welding of random homeomorphisms of the unit circle given in terms of the exponential of Gaussian Free Field. We conjecture that our curves are locally related to SLE(κ)(\kappa) for κ<4\kappa<4.Comment: 5 page

    The Effect of Traction Sanding on Urban Suspended Particles in Finland

    Get PDF
    Springtime urban road dust forms one of the most serious problems regarding air pollution in Finland. The composition and origin of springtime dust was studied in southern Finland with two different methods. Suspended particles (PM10 and TSP) were collected with high volume particle samplers and particle deposition was collected with moss bags. The composition of the PM1.5−10 fraction was studied using individual particle analysis with SEM/EDX. The deposition in the moss bags was analysed with ICP-MS. The results showed that during the study period, approximately 10% of both PM1.5−10 particles and the deposition originated from sanding. Other sources in the springtime PM1.5−10 were e.g. asphalt aggregate or soil and combustion processes. It can be concluded that sanding produced a relatively small amount of particulate matter under the investigated circumstances

    Primary Emissions of Submicron and Carbonaceous Particles in Europe and the Potential for their Control

    Get PDF
    The interest in submicron and specifically carbonaceous particles in the atmosphere has risen recently, largely because of their potential role as climate forcing agents. Black carbon (BC) particles absorb solar radiation and are suspected to be a significant factor contributing to climate warming. Particulate organic carbon (OC), in turn, acts as a cooling substance. In principle, all of the atmospheric BC and a large part of the OC are emitted from incomplete combustion of fossil fuels and biomass. To model the climatic effects of carbonaceous aerosols it is crucial to provide robust estimates of their emission strengths. Recent measurements of atmospheric optical depth suggest that earlier BC emission inventories may lead to over-estimations of atmospheric BC over Europe. This paper describes estimates of emissions of primary submicron particles, BC and OC in Europe, applying an extended PM-module of the RAINS model. The European emissions in 2000 are estimated at 2.8, 0.67 and 0.99 Tg for submicron, BC and OC, respectively. The main sources are exhaust emissions from traffic and residential combustion of solid fuels, which together amount to 64 percent of the submicron emissions, 85 percent of the total BC and 81 percent of the total OC. By 2010 the emissions of all three pollutants are projected to decline by about 20 percent, largely due to implementation of the 'EURO-standards' for mobile sources and fuel switching in the residential sector

    A mobile laboratory for monitoring non-exhaust emissions in Finland

    Get PDF
    Local vehicular traffic is responsible for a substantial fraction of PM10 in urban air mainly due to non-exhaust traffic emissions and resuspension from street surfaces (e.g. Zhao et al., 2006). In Northern areas (e.g. Scandinavia) street dust levels are especially high during spring, and the diurnal average PM10 value (the EU directive) is exceeded more than the allowed 35 times per year. In this paper we introduce the sampling system of a mobile research laboratory SNIFFER for studying emission levels of respirable dust from street surfaces. We have measured a unique time series of the street level PM10 concentrations in a city of Helsinki, Finland, during the last five springs. A special 20 km route in downtown was selected to cover main streets including bus lanes, tram lanes, canyon streets, open transit streets and some cobblestone covered streets. For every spring the maximun emission level averaged over the whole route was 2000-4500 mg/m-3 and occurred in the turn from March to April, after which the clear decreasing trend was found. The most highest street concentrations were measured on the street canoyns as well as on the streets covered by copplestone and on the sections which were under work construction

    Integrated Assessment of Black Carbon and Tropospheric Ozone

    Get PDF
    The Integrated Assessment of Black Carbon and Tropospheric Ozone looks into all aspects of anthropogeic emissions of black carbon and tropospheric ozone precursors, such as methane. It analyses the trends in emissions of these substances and the drivers of these emissions; summarizes the science of atmospheric processes where these substances are involved; discusses related impacts on the climatic sysem, human health, crops in vulnerable regions and ecosystems; and societal responses to the environmntal changes caused by those impacts. The Assessment examines a large number of potential measures to reduce harmful emissions, identifying a small set of specific measures that would likely produce the greatest benefits, and which could be implemented with currently available technology. An outlook up to 2070 is developed illustrating the benefits of those emission mitigation policies and mesures for human well-being and climate. The Assessment concludes that rapid mitigation of anthropogenic black carbon and tropospheric ozone precursor emissions would complement carbon dioxide reduction measures and would have immediate benefits for human well-being. The Assessment is intended to support informed decision making at all levels as a guide for assessment, planning and management for the future

    Global anthropogenic emissions of particulate matter including black carbon

    Get PDF
    This paper presents a comprehensive assessment of historical (1990–2010) global anthropogenic particulate matter (PM) emissions including the consistent and harmonized calculation of mass-based size distribution (PM1, PM2. 5, PM10), as well as primary carbonaceous aerosols including black carbon (BC) and organic carbon (OC). The estimates were developed with the integrated assessment model GAINS, where source- and region-specific technology characteristics are explicitly included. This assessment includes a number of previously unaccounted or often misallocated emission sources, i.e. kerosene lamps, gas flaring, diesel generators, refuse burning; some of them were reported in the past for selected regions or in the context of a particular pollutant or sector but not included as part of a total estimate. Spatially, emissions were calculated for 172 source regions (as well as international shipping), presented for 25 global regions, and allocated to 0.5°  ×  0.5° longitude–latitude grids. No independent estimates of emissions from forest fires and savannah burning are provided and neither windblown dust nor unpaved roads emissions are included. We estimate that global emissions of PM have not changed significantly between 1990 and 2010, showing a strong decoupling from the global increase in energy consumption and, consequently, CO2 emissions, but there are significantly different regional trends, with a particularly strong increase in East Asia and Africa and a strong decline in Europe, North America, and the Pacific region. This in turn resulted in important changes in the spatial pattern of PM burden, e.g. European, North American, and Pacific contributions to global emissions dropped from nearly 30 % in 1990 to well below 15 % in 2010, while Asia's contribution grew from just over 50 % to nearly two-thirds of the global total in 2010. For all PM species considered, Asian sources represented over 60 % of the global anthropogenic total, and residential combustion was the most important sector, contributing about 60 % for BC and OC, 45 % for PM2. 5, and less than 40 % for PM10, where large combustion sources and industrial processes are equally important. Global anthropogenic emissions of BC were estimated at about 6.6 and 7.2 Tg in 2000 and 2010, respectively, and represent about 15 % of PM2. 5 but for some sources reach nearly 50 %, i.e. for the transport sector. Our global BC numbers are higher than previously published owing primarily to the inclusion of new sources. This PM estimate fills the gap in emission data and emission source characterization required in air quality and climate modelling studies and health impact assessments at a regional and global level, as it includes both carbonaceous and non-carbonaceous constituents of primary particulate matter emissions. The developed emission dataset has been used in several regional and global atmospheric transport and climate model simulations within the ECLIPSE (Evaluating the Climate and Air Quality Impacts of Short-Lived Pollutants) project and beyond, serves better parameterization of the global integrated assessment models with respect to representation of black carbon and organic carbon emissions, and built a basis for recently published global particulate number estimates

    The effects of climate change and abatement policies on the value of natural resources in Northern Europe and in the Arctic Sea area

    Get PDF
    The impact of the climate on the Arctic plays a crucial role for Finland's, as well as other Nordic countries', current and future climatic conditions. Far-reaching and multi-faceted changes are taking place in the Arctic, which have profound consequences for the region's economic and political significance in international relations. The review analyses the effects of climate change and likely climate abatement policies on the accessibility and value of natural resources in Northern Europe in the Arctic Sea area and on the logistical position of Northern Europe with a special emphasis on Finland

    Anomalous Scaling in the N-Point Functions of Passive Scalar

    Full text link
    A recent analysis of the 4-point correlation function of the passive scalar advected by a time-decorrelated random flow is extended to the N-point case. It is shown that all stationary-state inertial-range correlations are dominated by homogeneous zero modes of singular operators describing their evolution. We compute analytically the zero modes governing the N-point structure functions and the anomalous dimensions corresponding to them to the linear order in the scaling exponent of the 2-point function of the advecting velocity field. The implications of these calculations for the dissipation correlations are discussed.Comment: 16 pages, latex fil
    • …
    corecore