Mathematical modelling of curtain coating

We present a simple mathematical model for the fluid flow in the curtain coating process, exploiting the small aspect ratio, and examine the model in the large-Reynolds-number limit of industrial interest. We show that the fluid is in free fall except for a region close to the substrate, but find that the model can not describe the turning of the curtain onto the substrate. We find that the inclusion of a viscous bending moment close to the substrate allows the curtain to “turn the corner”

Reliably Accounting for Negative Emissions of Waste-to-Energy with Carbon Capture and Storage

When equipped with Carbon Capture and Storage (CCS), the Waste to Energy (WtE) sector can play a significant role in creating an overall system that removes excess greenhouse gases from the atmosphere while sustainably managing waste. Ultra-high CO2 capture rates can be achieved to eliminate all CO2 emissions from the combustion of the waste feedstock. As the biogenic carbon in most waste feedstocks originates in the atmosphere, the implementation of CCS on WtE plants can create a ‘negative emissions’ system; i.e., the removal and permanent storage of atmospheric carbon dioxide. Existing studies exploring the negative emissions potential of this technology are of limited scope, however, and do not account for the system-wide change in impacts or identify relevant cause-effect pathways. By not accounting for the impact of removing recyclable materials from the supply chain, for example, the comparative benefit of sending biogenic materials for recycling or to WtE with CCS is poorly understood. It is important to understand these benefits in the context of the whole economy. This paper reviews existing analyses of the carbon reduction of WtE with CCS and discusses the challenges of understanding its role in the transition to Net Zero in the context of the circular economy

Bailouts in a common market: a strategic approach

Governments in the EU grant Rescue and Restructure Subsidies to bail out ailing firms. In an international asymmetric Cournot duopoly we study effects of such subsidies on market structure and welfare. We adopt a common market setting, where consumers from the two countries form one market. We show that the subsidy is positive also when it fails to prevent the exit. The reason is a strategic effect, which forces the more efficient firm to make additional cost-reducing effort. When the exit is prevented, allocative and productive efficiencies are lower and the only gaining player is the rescued firm

Mathematical Model of Easter Island Society Collapse

In this paper we consider a mathematical model for the evolution and collapse of the Easter Island society, starting from the fifth century until the last period of the society collapse (fifteen century). Based on historical reports, the available primary sources consisted almost exclusively on the trees. We describe the inhabitants and the resources as an isolated system and both considered as dynamic variables. A mathematical analysis about why the structure of the Easter Island community collapse is performed. In particular, we analyze the critical values of the fundamental parameters driving the interaction humans-environment and consequently leading to the collapse. The technological parameter, quantifying the exploitation of the resources, is calculated and applied to the case of other extinguished civilization (Cop\'an Maya) confirming, with a sufficiently precise estimation, the consistency of the adopted model.Comment: 9 pages, 1 figure, final version published on EuroPhysics Letter

Estimations of rip current rescues and drowning in the United States

Rip currents are the greatest hazard to swimmers on surf beaches, but due to a lack of consistent incident reporting in many countries, it is often difficult to quantify the number of rip-current-related rescues and drowning deaths occurring along surf beaches. This study examines this problem using rescue data reported to the United States Lifesaving Association (USLA) by surf beach rescuers from 1997 through 2016. These data were checked, corrected, and culled so that only data from surf beach rescue agencies that reported the primary cause of rescue were included. Results show that rip currents are the primary cause of 81.9&thinsp;% of rescues on surf beaches, with regional variation from 75.3&thinsp;% (East Coast) to 84.7&thinsp;% (West Coast). These values are significantly higher than those previously reported in the scientific literature (e.g., 36.5&thinsp;%, 53.7&thinsp;%). Using this value as a proxy when examining overall surf beach drowning fatalities, it is suggested that more than 100 fatal drownings per year occur due to rip currents in the United States. However, it is clear that the United States data would benefit by an increase in the number of lifeguard agencies which report surf-related rescues by primary cause.</p