Environmental sustainability, nonlinear dynamics and chaos reloaded: 0 matters!

n this paper, we reconsider the overlapping generations (OLG) environmental model in- troduced in John and Pecchenino (1994) and Zhang (1999) by adopting the specification of the environmental dynamics proposed by Naimzada and Sodini (2010). The model is characterized by two different regimes that may alternate: one in which environmental evolution and economic growth co-evolve in the same direction; the other in which the environmental problem is not internalized by the agents, that is, the agents do not devolve any private resource to the environmental quality, leading to a possible trade-off between environment and economic growth. The analysis of the equilibrium dynamics, described by a two dimensional piecewise smooth map, shows that starting from a parametric configuration in which the dynamics are eventually driven by a unique regime, the increase of the negative effect of the agents’ consumption activity ends up in scenarios where the two regimes alternate, determining the rise of stable cycles or the occurrence of chaotic regimes. It is interesting to notice that because of the nonsmoothness of the map, the rise in environmental harm produced by economic activity may induce a sudden transition to chaotic regime

Process Simulation of Impurity Impacts on CO2 Fluids Flowing in Pipelines

YesCaptured carbon dioxide flowing in pipelines is impure. The impurities contained in the carbon dioxide fluid impact on the properties of the fluid. The impact of each impurity has not been adequately studied and fully understood. In this study, binary mixtures containing carbon dioxide and one impurity, at the maximum permitted concentration, flowing in pipelines are studied to understand their impact on pipeline performance. A hypothetical 70 km uninsulated pipeline is assumed and simulated using Aspen HYSYS (v.10) and gPROMS (v.5.1.1). The mass flow rate is 2,200,600 kg/h; the internal and external diameters are 0.711 m and 0.785 m. 15 MPa and 9 MPa were assumed as inlet and minimum pressures and 33 oC as the inlet temperature, to ensure that the fluid remain in the dense (subcritical or supercritical) phase. Each binary fluid is studied at the maximum allowable concentration and deviations from pure carbon dioxide at the same conditions is determined. These deviations were graded to rank the impurities in order of the degree of impact on each parameter. All impurities had at least one negative impact on carbon dioxide fluid flow. Nitrogen with the highest concentration (10-mol %) had the worst impact on pressure loss (in horizontal pipeline), density, and critical pressure. Hydrogen sulphide (with 1.5-mol %) had the least impact, hardly changing the thermodynamic properties of pure carbon dioxide

Population dynamics and economic development

This research develops a continuous-time optimal growth model that accounts for population dynamics resembling the historical pattern of the demographic transition. The Ramsey model then becomes able to generate multiple determinate or indeterminate stationary equilibria and explain the process of the transition from a state with high fertility and low income per capita to a state with low fertility and high income per capita. The article also investigates the emergence of damped or persistent cyclical dynamics

Monopoly with differentiated final goods and heterogeneous markets

This work attempts to characterise the dynamic properties of a nonlinear model in which a monopolist produces a fixed amount of an intermediate good. The firm employs this good in producing two vertically differentiated final commodities, sold in two distinct markets. Consumers’ preferences are described by quasi-linear and quadratic utility functions respectively yielding isoelastic and linear demand functions. In addition, we assume that the monopolist adopts a gradient adjustment rule based on profit variation to adjust its choice about the amount of intermediate good to employ in the production of each final good. Two alternative scenarios emerge: in the first, there exists coexistence of two markets; in the second, the monopolist specialises on the production of a single final good. The dynamics show that the elasticities of market demands play an ambiguous role in affecting the stability of the equilibrium, whereas the speed of adjustment unambiguously destabilises the system. Moreover, the article investigates the role of the productive capacity and the gap in marginal costs in defining the different scenarios. In particular, economic dynamics may be chaotic and/or multiple attractors may appear