We investigate whether income inequality affects subsequent growth in a cross-country sample for 1965-90, using the models of Barro (1997), Bleaney and Nishiyama (2002) and Sachs and Warner (1997), with negative results. We then investigate the evolution of income inequality over the same period and its correlation with growth. The dominating feature is inequality convergence across countries. This convergence has been significantly faster amongst developed countries. Growth does not appear to influence the evolution of inequality over time. Outline

https://www.econstor.eu/bitstream/10419/81822/1/02-28.pdf

Economic growth and income inequality

Many optimal decision problems in scientific, engineering, and public sector applications involve both discrete decisions and nonlinear system dynamics that affect the quality of the final design or plan. These decision problems lead to mixed-integer nonlinear programming (MINLP) problems that combine the combinatorial difficulty of optimizing over discrete variable sets with the challenges of handling nonlinear functions. We review models and applications of MINLP, and survey the state of the art in methods for solving this challenging class of problems.Most solution methods for MINLP apply some form of tree search. We distinguish two broad classes of methods: single-tree and multitree methods. We discuss these two classes of methods first in the case where the underlying problem functions are convex. Classical single-tree methods include nonlinear branch-and-bound and branch-and-cut methods, while classical multitree methods include outer approximation and Benders decomposition. The most efficient class of methods for convex MINLP are hybrid methods that combine the strengths of both classes of classical techniques.Non-convex MINLPs pose additional challenges, because they contain non-convex functions in the objective function or the constraints; hence even when the integer variables are relaxed to be continuous, the feasible region is generally non-convex, resulting in many local minima. We discuss a range of approaches for tackling this challenging class of problems, including piecewise linear approximations, generic strategies for obtaining convex relaxations for non-convex functions, spatial branch-and-bound methods, and a small sample of techniques that exploit particular types of non-convex structures to obtain improved convex relaxations.We finish our survey with a brief discussion of three important aspects of MINLP. First, we review heuristic techniques that can obtain good feasible solution in situations where the search-tree has grown too large or we require real-time solutions. Second, we describe an emerging area of mixed-integer optimal control that adds systems of ordinary differential equations to MINLP. Third, we survey the state of the art in software for MINLP.

/pdf/mixed-integer-nonlinear-optimization-3yf57zxyv3.pdf

Mixed-integer nonlinear optimization

The contribution of this paper focuses on the development of a security-based methodology for the solution of short-term SCUC when considering the impact of natural gas transmission system. The proposed methodology examines the interdependency of electricity and natural gas in a highly complex transmission system. The natural gas transmission system is modeled as a set of nonlinear equations. The proposed solution applies a decomposition method to separate the natural gas transmission feasibility check subproblem and the power transmission feasibility check subproblem from the hourly unit commitment (UC) in the master problem. Gas contracts are modeled and incorporated in the master UC problem. The natural gas transmission subproblem checks the feasibility of natural gas transmission as well as natural gas transmission security constraints for the commitment and dispatch of gas-fired generating units. If any natural gas transmission violations arise, corresponding energy constraints will be formed and added to the master problem for solving the next iteration of UC. The iterative process will continue until a converged feasible gas transmission solution is found. A six-bus power system with seven-node gas transmission system and the IEEE 118-bus power system with 14-node gas transmission system are analyzed to show the effectiveness of the proposed solution. The proposed model can be used by a vertically integrated utility or the ISO for the short-term commitment and dispatch of generating units with natural gas transmission constraints.

/pdf/security-constrained-unit-commitment-with-natural-gas-1g1e7cvr5h.pdf

Security-Constrained Unit Commitment With Natural Gas Transmission Constraints

This paper provides a survey of the empirical literature on Environmental Kuznets Curve (EKC) estimation of carbon dioxide (CO2) emissions over the period of 1991-2017. This survey categorizes the studies on the basis of single country and cross-country contexts. It has been hypothesized that the EKC is an inverted U-shaped association between economic growth and CO2 emissions. For both single country and cross-country contexts, the results of EKC estimation for CO2 emissions are inconclusive in nature. The reasons behind this discrepancy can be attributed to the choice of contexts, time period, explanatory variables, and methodological adaptation. The future studies in this context should not only consider new set of variables (e.g., corruption index, social indicators, political scenario, energy research and development expenditures, foreign capital inflows, happiness, population education structure, public investment towards alternate energy exploration, etc.), but also the dataset should be refined, so that the EKC estimation issues raised by Stern (2004) can be addressed.

Environmental Kuznets curve for CO2 emissions: a literature survey

http://gama.fime.uanl.mx/~roger/work/Papers/report/report-pisis-2014-04.pdf

Optimization problems in natural gas transportation systems. A state-of-the-art review

The problem of distributing gas through a network of pipelines is formulated as a cost minimization subject to nonlinear flow-pressure relations, material balances, and pressure bounds. The solution method is based on piecewise linear approximations of the nonlinear flow-pressure relations. The approximated problem is solved by an extension of the Simplex method. The solution method is tested on real-world data and compared with alternative solution methods.

The Gas Transmission Problem Solved by an Extension of the Simplex Algorithm

The gas transmission problem solved by an extension of the simplex algorithm

We consider a stochastic version of the Stackelberg-Nash-Cournot model proposed by Murphy et al. (1983). Ln the first stage, the leader chooses and announces his production level taking into account the reaction of the followers. The decision of the leader is taken when market demand is uncertain. In the second stage, the followers, knowing the leader's output, react to this level according to the Cournot assumption. At this stage, demand is known. We study the extension of the Murphy et al. model and give a numerical illustration of this model using the European gas market.

A stochastic version of a Stackelberg-Nash-Cournot equilibrium model

We develop an algorithm to solve the problem of the optimal dimensioning of a fluid gas or water transmission network when the topology of the network is known. The pipe diameters must be chosen to minimize the sum of the investment and operating costs. This two stage problem is solved by application of the bundle method for nonsmooth optimization. The validity of the approach is tested on a problem corresponding to a real situation: the optimal design of a reinforcement of the Belgian gas network.

Optimal Dimensioning of Pipe Networks with Application to Gas Transmission Networks

This paper studies causal mechanism between indicators for sustainable energy development related to energy consumption from Tunisian road transport sector. The investigation is made using the Johansen cointegration technique and the environmental Kuznets curve (EKC) approach. It examines the nexus between transport value added, road transport-related energy consumption, road infrastructure, fuel price and CO2 emissions from Tunisian transport sector during the period of 1980–2010.

Empirical results show that road transport-related energy consumption, transport value added, transport CO2 emissions and road infrastructure are mutually causal in the long-run. These results do not support the hypothesis of neutrality between energy and income for the Tunisian road transport sector. Also, there is a unidirectional causality running from fuel price to road transport-related energy consumption with no feedback in both the short and long runs. The fuel price and the road infrastructure are significant in the causal chain. Though the estimated long-run cointegrated equation, we conclude that there is an inverse N-shaped relation between transport value added and transport CO2 emissions, with income turning point respectively equal to 75 and 579 (constant 2000 TND prices). Therefore, our empirical findings refute the hypothesis of an inverted U-shaped EKC for transport CO2 emissions in Tunisia.

The findings of this study have a number of policy implications. Economic growth, environmental degradation, energy and transportation policies should be recognized in order to improve the energy efficiency in transport sector. All measures that should reduce petroleum consumption and greenhouse gas emissions without affecting economic growth may be undertaken. The policymakers in Tunisia should plan urban transport, relocate production units, improve fuel-efficient vehicles and reinforce legislation on controlling emissions in order to copying with policies based on low-carbon development and climate-resilient strategies.

/pdf/indicators-for-sustainable-energy-development-a-multivariate-4p71emcc55.pdf

Daniel De Wolf

Papers

The Gas Transmission Problem Solved by an Extension of the Simplex Algorithm

The gas transmission problem solved by an extension of the simplex algorithm

A stochastic version of a Stackelberg-Nash-Cournot equilibrium model

Optimal Dimensioning of Pipe Networks with Application to Gas Transmission Networks

Indicators for sustainable energy development: A multivariate cointegration and causality analysis from Tunisian road transport sector