Solving recent RBC models using linearization: further reserves

Through a simple example, we show that the successive sophistications introduced in the early RBC models in order to improve their internal propagation mechanisms have actually increased their non-linearities, even locally. Accordingly, linearization-based resolution methods become much more disputableı than they were for early RBC models. Simple comparative studies ofı impulse-response functions are used to illustrate this point. We conclude by pointing at sorne alternative resolution techniques that allow the model builder to take non-linearities into account and/or to handle with the presence of large state spaces

Solving recent RBC models using linearization: further reserves.

Through a simple example, we show that the successive sophistications introduced in the early RBC models in order to improve their internal propagation mechanisms have actually increased their non-linearities, even locally. Accordingly, linearization-based resolution methods become much more disputableı than they were for early RBC models. Simple comparative studies ofı impulse-response functions are used to illustrate this point. We conclude by pointing at sorne alternative resolution techniques that allow the model builder to take non-linearities into account and/or to handle with the presence of large state spaces.RBC Models; Linearization Methods; Impulse-Response Functions;

Salt and Water Uptake in Nanocon!nement under Applied Electric Field: An Open Ensemble Monte Carlo Study

Permeation of electrolytes in nanoporous materials underlies many applications in energy and materials technologies. Wetting of apolar nanopores can be enhanced by electric !eld, attracting water and ions from unperturbed electrolyte bath. We study absorption of water and NaCl in the pores by Expanded Ensemble Grand Canonical Monte Carlo simulation, which implements particle insertions and deletions through incremental changes in particles’ coupling with the system. We determine the uptake of water and ions in the pores, and concomitant changes in pore thermodynamics, as functions of !eld strength in the pore and salinity in the external bath. Pressure increase and reduction of wetting free energy, !, in the pore intensify near-quadratically with the !eld. Surprisingly, the in uence of bulk salinity on ! can change qualitatively with pore width and !eld strength. Conforming to Gibbs adsorption isotherm, narrow pores with salt molality below that of the bath experience an increase in ! with rising bulk salinity. The !eld can change salt depletion to excess and consequently reverse the salinity dependence of wetting free energy from increasing to declining function of bulk molality. Field polarity continues to play a role, leading to asymmetric wettability at opposing walls as we previously observed in the absence of ions

A review of computable general equilibrium models for transport and their applications in appraisal

© 2018 Elsevier Ltd In the transport planning process, decision makers require reliable and informative appraisals to facilitate comparisons and determine if a proposal is worthwhile to society. The cost–benefit analysis is the most common form of appraisal, where benefits are primarily measured from the change in consumer surplus in the transport market. However, these benefits will only reflect maximum social welfare if markets operate perfectly competitively and without any market failures. There may be significant uncaptured impacts, known as wider economic impacts, which agencies are beginning to incorporate in appraisals using ad-hoc methods. Computable general equilibrium (CGE) models are an increasingly popular method for assessing the economic impact of transport, including both direct and wider economic impacts, as they can determine the distribution of impacts among every market and agent in the economy by simulating the behaviour of households, firms and others from microeconomic first principles. Aside from their traditional role estimating changes in macroeconomic variables, CGE models can provide a measure of welfare that guarantees no double counting and accounts for nth order effects. This paper reviews the full range of CGE models that have been applied to transport issues and discusses their role in transport appraisal. CGE models for transport have been developed in urban, regional and environmental economics as well as other fields, and each field has applied its own theory, assumptions and practices to represent the relationships between transport and the economy relevant to the field. This paper also discusses the general role of CGE modelling in transport appraisal, as well as theoretical and practical concerns regarding CGE modelling practice

Solving nonlinear rational expectations models by eigenvalue-eigenvector decompositions

We provide a summarized presentation of solution methods for rational expectations models, based on eigenvalue/eigenvector decompositions. These methods solve systems of stochastic linear difference equations by relying on the use of stability conditions derived from the eigenvectors associated to unstable eigenvalues of the coefficient matrices in the system. For nonlinear models, a linear approximation must be obtained, and the stability conditions are approximate, This is however, the only source of approximation error, since the nonlinear structure of the original model is used to produce the numerical solution. After applying the method to a baseline stochastic growth model, we explain how it can be used: i) to salve some identification problems that may arise in standard growth models, and ii) to solve endogenous growth models

The rise of goods-market competition and the fall of nominal wage contracting: endogenous wage contracting in a multisector economy

This paper shows how heterogeneity wage-setting and a link between nominal wage flexibility andg goods-market competition rise in a multisector economy that is affected by aggregate and sector-specific shocks. Aggregate volatility increases the variance of real contract wages, whereas sectoral volatility increase the relative variance of real Walrasian wages. Given this tradeoff, the prevalence of nominal wage contracting reflects both the relative volatility of aggregate versus sectoral disturbances and the overall degree of goods-market market competition. We find that these variables help explain the decline in unionization (a proxy for contracting in) the United States.Markets ; Wages

Molecular modelling and simulation of fluids, surfaces and their interactions in reservoir settings

Fluid interactions within porous media are of vital importance in petrol-chemical processes. Problems encountered macroscopically, e.g., contact line tracking, confined fluid, and wetting alternation motivates investigations at a smaller scale. Nanoscale molecular modeling techniques such as molecular dynamics (MD) are a suitable tool; recent development of the Statistical Associating Fluid Theory (SAFT) force fields used in MD makes coarse-grained (CG) representation a viable option to describe large and complex systems. The work starts by assessing the predictive and correlative capability of the SAFT CG force field as applied to pure components and mixtures of CO2 with n-decane and n-hexadecane and 2,2,4-trimethylhexane, a lubricant. By using the principle of corresponding states to obtain the SAFT force field parameters for chemicals of limited experimental measurements and are selected as representative components based on 2D gas chromatography data of three different stock tank crude oils, the density, viscosity and surface tension as functions of temperature are simulated and compared to experimental data, observing good overall agreement. This work also provides a strategy for converting the topography of a natural rock surface measured by atomic force microscopy (AFM) into a series of synthetic surfaces of nanometer-scale amplitudes and wavelengths. The surface chemistry is characterised as calcite by fitting the water-surface interactions to atomistic water density profiles and the oil-surface interactions to experimental contact angle measurements on a smoothly cleaved calcite. The wettability can be examined systematically via the apparent contact angles and curvatures of the droplet at various surface roughness. The dependence of the contact angle with roughness is found to be in qualitative agreement with macroscopic Wenzel and Cassie-Baxter relations. Overall, the flow of this work provides a plausible strategy of assessing nanoscale wetting in reservoir settings; future information on surface adsorption of specific components would facilitate more quantitative evaluations.Open Acces