Equilibrium Effects Research Articles

Investigation on shock-induced separation loss mitigation method considering radial equilibrium in a transonic compressor rotor

AbstractA shock-induced separation loss reduction method, using local blade suction surface shape modification (smooth ramp structure) with constant adverse pressure gradient with the consideration of radial equilibrium effect to split a single shock foot into multiple weaker shock wave configuration, is investigated on the NASA Rotor 37 for promoting aerodynamic performance of a transonic compressor rotor. Numerical investigation on baseline blade and improved one with blade modification on suction side has been conducted employing the Reynolds-averaged Navier–Stokes method to reveal flow physics of ramp structure. The results indicate that the passage shock foot of baseline is replaced with a family of compression waves and a weaker shock foot generating moderate adverse pressure gradient on ramp profile, which is beneficial for mitigating the shock foot and shrinking flow separation region as well. In addition, the radial secondary flow of low-momentum fluids within boundary layer is decreased significantly in the region of passage shock-wave/boundary-layer interaction on blade suction side, which mitigates the mass flow and mixing intensity of tip leakage flow. With the reduction of flow separation loss induced by passage shock, the adiabatic efficiency and total pressure ratio of improved rotor are superior to baseline model. This study herein implies a potential application of ramp profile in design method of transonic and supersonic compressors.

A new moment-based general-relativistic neutrino-radiation transport code: Methods and first applications to neutron star mergers

ABSTRACTWe present a new moment-based energy-integrated neutrino transport code for neutron star merger simulations in general relativity. In the merger context, ours is the first code to include Doppler effects at all orders in υ/c, retaining all non-linear neutrino–matter coupling terms. The code is validated with a stringent series of tests. We show that the inclusion of full neutrino–matter coupling terms is necessary to correctly capture the trapping of neutrinos in relativistically moving media, such as in differentially rotating merger remnants. We perform preliminary simulations proving the robustness of the scheme in simulating ab-initio mergers to black hole collapse and long-term neutron star remnants up to ${\sim }70\,$ ms. The latter is the longest dynamical space-time, 3D, general relativistic simulations with full neutrino transport to date. We compare results obtained at different resolutions and using two different closures for the moment scheme. We do not find evidences of significant out-of-thermodynamic equilibrium effects, such as bulk viscosity, on the post-merger dynamics or gravitational wave emission. Neutrino luminosities and average energies are in good agreement with theory expectations and previous simulations by other groups using similar schemes. We compare dynamical and early wind ejecta properties obtained with M1 and with our older neutrino treatment. We find that the M1 results have systematically larger proton fractions. However, the differences in the nucleosynthesis yields are modest. This work sets the basis for future detailed studies spanning a wider set of neutrino reactions, binaries, and equations of state.

Numerical modeling of CO2 arc based on the non-chemically equilibrium effect

Carbon dioxide (CO2) and its mixtures are potential alternatives as the arc quenching medium in switchgear. During the arc decaying phase after the arc current drops to zero, the arc plasma will deviate from the local thermally equilibrium (LTE) state and then the non-chemically equilibrium (non-CE) effect should be considered to predict the arc behavior. A non-CE numerical model was established to investigate the dynamic behavior of CO2 arc during the current zero (CZ) period. The time-dependent distributions of temperature, energy and electrical conductivity between the LTE and non-CE models were compared. The distributions of the species compositions and the non-equilibrium parameters were also investigated to further explain the mechanism of the non-CE effect. The non-CE particle transport is the main reason for the difference of temperature decay between non-CE and LTE calculations. The transport of all particles at the edge of the arc is dominantly influenced by the radial convection and diffusion, while the transport of atoms at the arc center is the combined results of convection, diffusion and chemical kinetics. As a contrast, the transports of electrons and ions are dominated by the chemical reactions. The decay of electron density at the nozzle throat calculated by the non-CE model are in good agreement with the laser Thomson scattering tests, while the LTE model failed to predict the electron density accurately, which proves that the non-CE effect of CO2 arc during CZ period cannot be ignored.

A game-theoretic perspective to study a nonlinear stochastic parabolic model of population competition

In this paper, a game of competition between two populations is designed. Populations are considered as two players competing against each other to increase their sizes. Players have been provided with costly two-component strategies. Population densities are described by two coupled nonlinear stochastic second-order parabolic equations. We have added stochastic terms to the deterministic model to consider random perturbations. First, we have considered the stochastic payoff functions and proved the game has a unique stochastic Nash equilibrium. Then, we have shown the stochastic Nash equilibrium is also a Nash equilibrium for the game with deterministic payoff functions defined by expectation. Cooperative game is also studied and stochastic Pareto efficient strategies are obtained. Then, the existence and uniqueness analyses of the deterministic Nash equilibrium and deterministic Pareto efficient strategies for the game with deterministic payoff functions are provided. The explicit forms of Nash equilibriums and Pareto efficient strategies are presented. Results about the losses the players experience when they don't cooperate are given. Finally, some numerical experiments are included to illustrate what we have claimed in the statements of theorems and show the effects of the Nash equilibrium and Pareto efficient strategy on the payoffs of the players.

Local Equilibrium and Discretization Effects on the Prediction of Scalar Dissipation Rates in Large Eddy Simulation of Turbulent Non-Premixed Combustion

ABSTRACT The effects of discretization and local equilibrium on the prediction of scalar dissipation rates are investigated by performing large-eddy simulation (LES) of a turbulent-piloted jet diffusion flame, Sandia Flame D. As a way to reduce the discretization errors on the prediction of scalar dissipation, an approach to use a higher-order finite difference scheme only for the evaluation of scalar gradients in a scalar dissipation model, while keeping the overall accuracy of the numerical method at second order, is investigated. Results indicate that the fourth-order scheme improves the accuracy with negligible addition to computational cost. With the improved evaluation of scalar gradients, the local equilibrium assumption, which is used in the algebraic model, is investigated by solving the subgrid-scale variance transport equation, where a model coefficient in a scaling-based relaxation model for subgrid-scale scalar dissipation is varied. It is found that the conditional mean scalar dissipation rates are insensitive to the model coefficient. This insensitivity is attributed to the prevalence of local equilibrium. A rapid decay of imbalance between production and dissipation of subgrid-scale scalar fluctuations is seen in both the predicted scalar dissipation and the transport budget in the variance equation. It is argued that since, at high Reynolds numbers, the transport of the scalar fluctuations occurs over a timescale larger than the subgrid-scale mixing timescale, its contribution to the evolution of subgrid-scale variance is statistically insignificant except near the nozzle exit where different streams begin to mix and scalar layers evolve rapidly. Consequently, the conditional (and unconditional) mean scalar dissipation rates in LES tend to depend solely on the production of subgrid-scale scalar fluctuations in most regions of turbulent jet flames, when the modeling is based on the Kolmogorov scaling.

Monetary Policy and Private Sector Performance in Nigeria (1995-2020)

The study examines the impact of monetary policy on private sector performance in Nigeria; for the period 1995-2019. Secondary data were used and collected from the Central Bank of Nigeria Statistical Bulletin. The study used Private Sector Output is proxy for Private Sector performance and employed as the dependent variable; whereas, broad money supply, liquidity rate and Credit Ratio respectively were used as the explanatory variables to measure monetary policy. Hypotheses were formulated and tested using time series econometric techniques. The study revealed a significant effect of credit ratio on private sector output in Nigeria. Liquidity ratio had a significant effect on private sector output in Nigeria. Broad money supply had a significant effect on private sector output in Nigeria. Hence, there is a long-run equilibrium effect on monetary policy and the private sector economy in Nigeria; and, the result confirms that about 73% short-run adjustment speed from long-run disequilibrium. The coefficient of determination indicated that about 65% of the variations in private sector led- economy can be explained by changes in monetary policy variables. The study concluded that monetary policy had impacted significantly on private sector growth in Nigeria. The study recommended that strong macroeconomic policies should be employed to maintain and stabilize the economy. CBN should lay down strict prudential guidelines to stabilize and strengthen the private sector led-economy. Government and policy makers should formulate policies that will increase the flow of investable funds and improves the capacity of private economy.

A highway across the Atlantic? Trade and welfare effects of the EU-Mercosur agreement

In this paper we analyze the EU-Mercosur agreement and predict its effects on trade and welfare using a general equilibrium structural gravity model. First, we exploit the detailed provision-level information available for the EU-Mercosur agreement to identify partial equilibrium trade effects of existing treaties with similar set of provisions. In a second step, the estimated increase in trade is mapped into reductions in bilateral trade costs and imputed to EU-Mercosur country pairs to compute the general equilibrium effects of the agreement in terms of trade creation, trade diversion, and welfare effects. Our results indicate that the positive effects on trade and welfare stemming from the EU-Mercosur agreement are likely to be economically important, especially for Mercosur countries, and substantially heterogeneous both between and within the two blocs.

Good Names Beget Favors: The Impact of Country Image on Trade Flows and Welfare

This paper estimates the effects of time-varying consumer preference bias on trade flows and welfare. We use a unique data set from the BBC World Service Poll, which surveys (annually during 2005–2017 with some gaps) the populations of a wide array of countries on their views of whether an evaluated country is having a mainly positive or negative influence in the world. We identify the effects on consumer preference parameters due to shifts in these country image perceptions and quantify their general equilibrium effects on bilateral exports and welfare (each time for an evaluated exporting country, holding the exporting country’s own preference parameters constant). We consider five important shifts in country image: the George W. Bush effect, the Donald Trump effect, the Senkaku Islands Dispute effect, the Brexit effect, and the Good-Boy Canadian effect. We find that such changes in bilateral country image perceptions have quantitatively important trade and welfare effects. The negative impact of Donald Trump’s “America First” campaign rhetoric on the U.S.’s country image might have cost the United States 4%–5% of its total exports and welfare gains from trade. In contrast, the consistent improvement of Canada’s country image between 2010 and 2017 has amounted to more than 8% of its total welfare gains from trade. This paper was accepted by Matthew Shum, marketing.

Strategic interactions in mobile network investment with a new entrant and unobserved heterogeneity

I estimate a game of mobile network investment between national incumbents and a new entrant to shed light on the limited success of competition enhancing policies in Canada. I recover player-specific unobserved heterogeneity from bids for spectrum licences to address the unavailability of regressors required to identify incumbents’ responses to the new entrant’s decisions. I find that incumbents benefitting from important economies of density is a plausible explanation for policies’ limitations. I then evaluate the equilibrium effect of subsidizing the new entrant’s transceivers and find that this counterfactual policy increases its investment while only slightly modifying incumbents’.

Methanol mediated direct CO2 hydrogenation to hydrocarbons: Experimental and kinetic modeling study

Carbon dioxide can be utilized as a feedstock to produce chemicals and renewable fuels sustainably. CO2 hydrogenation to hydrocarbons through a methanol mediated pathway requires a more detailed study, examining interactions between reaction processes leading to different product selectivities. In this particular work, we propose a kinetic model for the direct CO2 hydrogenation to different hydrocarbon products over an In2O3/HZSM-5 bifunctional catalytic bed. The model includes a CO2 hydrogenation to methanol model based on a Langmuir Hinshelwood Hougen Watson (LHHW) reaction mechanism over In2O3 catalyst combined with a lump-type methanol to hydrocarbon (MTH) model over the HZSM-5 zeolite. Interestingly, the combined model could largely predict the suppression of the reverse water gas shift (RWGS) reaction and an increase in the yield of hydrocarbons compared to the formation of methanol in case of the same reaction conditions carried out with only the methanol synthesis catalyst (In2O3). Further, by varying the mass ratio of the individual components of the bifunctional catalytic bed, it was demonstrated that a higher outlet concentration of methanol achieved with a higher mass ratio of the methanol synthesis catalyst caused less suppression of the RWGS reaction and shifted the hydrocarbon product distribution to a slightly larger share of higher hydrocarbons. These changes in product selectivity caused by variation of the catalyst mass ratio were both also successfully reproduced by the model. Therefore, a comparison between the experimental results and the model predictions shows that this model, including equilibrium effects for the reactions, can accurately predict the trends of the experimental findings for direct CO2 hydrogenation to hydrocarbons over the In2O3/HZSM-5 catalyst.

Economic modelling to evaluate Smart Specialisation: an analysis of research and innovation targets in Southern Europe

ABSTRACT We make the case for a technology-enabled approach to Smart Specialisation policymaking aimed at increasing its effectiveness by assessing the general equilibrium effects of the European Cohesion Policy objectives contained in the regional Operational Programmes prepared by the regional policymakers. We simulate the impact of achieving the research and development personnel targets on gross domestic product and its components in a set of Southern European regions. We discuss the implications and challenges of the proposed methodology for future assessments of Smart Specialisation and for its implementation in the regions of the European Union.

Trade, productivity, and the spatial organization of agriculture: Evidence from Brazil

This paper studies how regional productivity shocks in agriculture propagate to the rest of the economy via trade and migration linkages, shaping their aggregate effects on GDP, welfare, and agricultural employment. Using comprehensive agricultural data from Brazil, I estimate a general equilibrium model with a rich spatial structure to evaluate the effects of a critical shock in modern agriculture: the adaptation of soybeans to tropical regions. Results show that this shock increased Brazil’s agricultural GDP by 4%–6%, with the bulk of this impact coming from international trade. Because soybeans are land-intensive relative to other agricultural sectors, agricultural employment fell in tropical regions to which soybeans expanded. In other parts of the economy, however, agricultural employment rose substantially. Additionally, I show that general equilibrium effects have important implications for the analysis of the returns to agricultural research and the evaluation of the reduced-form effects of productivity shocks on agricultural employment.

A reliable framework to predict the temperature dependent thermal conductivity of multicomponent salt based PCMs in both solid and liquid state

Among all the properties required for the design of the next generation of phase change materials (PCMs) (density, heat capacity, thermal expansion, latent energy, volume change upon melting, corrosion rate, etc.) the thermal transport properties are by far the least known, especially for molten salt mixtures and solid solutions. We present in this paper a theoretical framework for accurate predictions of thermal conductivity of multicomponent salt-based PCMs, from 273.15 K up to above melting temperature. The solid phase is considered as a microstructure with its proper temperature dependent parameters: phase volume fraction, grain size distribution, porosity, etc. As case studies, five new potential PCMs for concentrated solar power (CSP) applications are considered. Their thermal conductivity is estimated as a function of temperature, from room temperature to 200 K above their melting point. The predictive capability of the proposed framework is discussed based on a comparison with available experimental data. The effect of equilibrium and non-equilibrium microstructural parameters (i.e. phase fraction, phase composition, average grain size, inter-grain, and intra-grain porosity) on the effective thermal conductivity of the solid states of the promising chloride PCMs is discussed. Lastly, recommendations for the design of next generations of PCM materials are suggested in order to improve their thermal transport properties.

An Interesting Acute Renal Failure Case which Developed in a Patient with Chronic Kidney Disease

Abstract: Chronic Kidney Disease (CKD) is defined as a chronic and progressive deterioration in kidney functions such as, balancing fluid-solute equilibrium and metabolic-endocrine effects as a result of a decrease in glomerular filtration rate. In present case, we aimed to report an acute renal failure case in an elderly man with CKD. A sixty two year old man presented with dyspnea, leg swelling and loss of appetite for two weeks. He is diagnosed with acute exacerbation of CKD caused by infected diabetic foot ulcer. He responded well to antibiotic and diuretic treatment. Management of acute exacerbation of kidney failure in patients with CKD requires a systematic approach and elimination of underlying causes. Careful treatment usually results in restoration of kidney function to the pre-exacerbation stage. Keywords: Chronic kidney disease, Diabetic foot ulcer, Diuretic, Antibiotic, Kidney function, Glomerular filtration rate.

Quantification the diffusion-induced fractionation of 1H217O isotopologue in air accompanying the process of water evaporation

Advances in laser technology enabling simultaneous analyses of three heavy water isotopologues (1H2H16O, 1H218O and 1H217O) triggered renewed interest in studies of the hydrological cycle using full isotopic composition of water. Such studies require adequate knowledge of equilibrium and kinetic isotope effects accompanying phase transitions of water. Here we report the results of laboratory experiments aimed at quantification of diffusion-induced fractionation of 1H217O isotopologue in air, accompanying the process of water evaporation. Three evaporation experiments have been conducted: (i) evaporation under constant temperature and relative humidity levels, (ii) evaporation under constant temperature and at three different relative humidity levels, and (iii) evaporation under constant relative humidity level and at two different temperatures. Experiment (i) yield the value of diffusive fractionation coefficient of 1H217O isotopologue in air equal 14.64 ± 0.24‰ at 20.4 °C. This value is indistinguishable within the quoted uncertainties from the value of 14.71 ± 0.05‰ derived experimentally for the first time by Barkan and Luz (2007). We confronted these experimental values with the results of state-of-the art quantum–mechanical calculations published recently by Hellmann and Harvey (2020). Experiments (ii) and (iii) yield for the first time the experimental evidence that, contrary to the d-excess, the 17O-excess parameter is largely insensitive to changes in temperature but is sensitive to changes of the relative humidity and this sensitivity increases with the degree of isotope enrichment of the evaporating water body. The linear dependence of kinetic fractionation coefficients of heavy water isotopologues in air on the relative humidity deficit, postulated by the Craig-Gordon isotope model of evaporation process, was confirmed by the results of experiment (ii) for all three isotope systems studied, pointing to correctness of the conceptual framework underlying this widely used model.

What Effects Could Global Value Chain and Digital Infrastructure Development Policies Have on Poverty and Inequality after COVID-19?

It is clear that in the transition out of the COVID-19 crisis in Colombia there will be great need for formal job creation. One source that has been widely discussed in policy circles is strengthening linkages of Colombian firms with Global Value Chains (GVCs). Another source that has received recent attention, and deservedly so, is digital infrastructure development (DID)—which can boost telework and virtual human capital accumulation. Reduction in poverty and inequality through more and better formal employment is an important aspect of a jobs and economic transformation (JET) agenda. In this paper, we explore—through a computable general equilibrium model (CGE) and a microsimulation framework—to what extent reforms of the type envisioned in the JET agenda and which could generate GVC linkages, as well as through DID, for Colombia, and we project their impact on poverty and inequality up to 2030. Our findings show limited impact of the three types of policy changes considered for GVCs—namely (i) fall in barriers for seamless business logistics, (ii) reductions in tariffs, and (iii) lower barriers to foreign direct investment (FDI). The impact of DID on inequality is also moot. There is however a modest impact on poverty reduction in the combined policy of digital infrastructure with a boost in skilled labor. This finding can be linked to different factors. First, there are relatively few direct jobs created to benefit households with low levels of human capital. Second, there might be indirect job creation through backward linkages to local suppliers by firms linked to GVCs, but this effect would be a general equilibrium effect that our CGE model with a partial equilibrium microsimulation distributional module does not fully capture. Third, the positioning of Colombian firms to latch onto GVCs, and also generate demand for local intermediate inputs and services, is not optimal. Fourth, DID may generate more general labor market opportunities through telework and virtual learning expansions but could also induce larger wage gaps as the skill premium rises so that the net effect on inequality is ambiguous.

Study of Natural Convection with Local Thermal Non Equilibrium Effects in Nanoliquid-Saturated Low Porosity Enclosures

Study of Natural Convection with Local Thermal Non Equilibrium Effects in Nanoliquid-Saturated Low Porosity Enclosures

How does fiscal austerity impact on poverty and inequality? The Spanish case

The aim of this paper is contributing to fill the gap between the macroeconomic effects of policy reforms and the microeconomic and social ones, considering simultaneously both kind of impacts. Regarding fiscal adjustments, concern about the sustainability of public deficit and debt resulting from the Great Recession led governments to adopt austerity measures in most European countries. Our analysis considers the redistributive effects of such adjustments for the Spanish economy by simulating a hypothetical reduction of public deficit and distinguishing between spending cuts and tax hikes. In terms of analytical approach, a Computable General Equilibrium (CGE) model and a microsimulation model are integrated to include the general equilibrium effects of these measures as well as the effects on income distribution. The results contribute to the growing but limited literature on the distributional effects of fiscal consolidations by showing that policymakers have to choose between more inequality or more poverty.

Abundance of beryllium in the Sun and stars: The role of non-local thermodynamic equilibrium effects

Context. Earlier studies have suggested that deviations from the local thermodynamic equilibrium (LTE) play a minor role in the formation of Be II 313 nm resonance lines in solar and stellar atmospheres. Recent improvements in the atomic data allow a more complete model atom of Be to be constructed and the validity of these claims to be reassessed using more up-to-date atomic physics. Aims. The main goal of this study therefore is to refocus on the role of non-local thermodynamic equilibrium (NLTE) effects in the formation of Be II 313.04 and 313.11 nm resonance lines in solar and stellar atmospheres. Methods. For this, we constructed a model atom of Be using new atomic data that recently became available. The model atom contains 98 levels and 383 radiative transitions of Be I and Be II and uses the most up-to-date collision rates with electrons and hydrogen. This makes it the most complete model atom used to determine 1D NLTE solar Be abundance and to study the role of NLTE effects in the formation of Be II 313 nm resonance lines. Results. We find that deviations from LTE have a significant influence on the strength of the Be II 313 nm line in solar and stellar atmospheres. For the Sun, we obtained the 1D NLTE Be abundance of A(Be)NLTE = 1.32 ± 0.05, which is in excellent agreement with the meteoritic value of A(Be) = 1.31 ± 0.04. Importantly, we find that NLTE effects become significant in FGK stars. Moreover, there is a pronounced variation in 1D NLTE–LTE abundance corrections with the effective temperature and metallicity. Therefore, contrary to our previous understanding, the obtained results indicate that NLTE effects play an important role in Be line formation in stellar atmospheres and have to be properly taken into account in Be abundance studies, especially in metal-poor stars.

Effect of Temperature Switching and Dynamic Phase Equilibrium on Polymer Microstructure in Condensed-Mode Operation

Effect of Temperature Switching and Dynamic Phase Equilibrium on Polymer Microstructure in Condensed-Mode Operation