The Experts below are selected from a list of 210 Experts worldwide ranked by ideXlab platform
Stephan Dempe - One of the best experts on this subject based on the ideXlab platform.
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Applications to Natural Gas Cash-Out Problem
Energy Systems, 2015Co-Authors: Stephan Dempe, Vyacheslav V. Kalashnikov, Gerardo A. Pérez-valdés, Nataliya I. KalashnykovaAbstract:The nature of natural gas implies that imbalances occur between the declared and really extracted amount of gas in a pipeline system. The transmit system operator penalizes the gas shipping company for these imbalances. The task of minimizing the resulting cash flow is modeled as bilevel optimization problem with one Boolean Variable in the lower level problem. We report related models, arising in applications, if the Boolean Variable is shifted to the upper level problem or when stochastic data are implemented. Solution algorithms and numerical results are presented.
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discrete bilevel programming application to a natural gas cash out problem
European Journal of Operational Research, 2005Co-Authors: Stephan Dempe, Vyacheslav V. Kalashnikov, Roger Z RiosmercadoAbstract:In this paper, we present a mathematical framework for the problem of minimizing the cash-out penalties of a natural gas shipper. The problem is modeled as a mixed-integer bilevel programming problem having one Boolean Variable in the lower level problem. Such problems are difficult to solve. To obtain a more tractable problem we move the Boolean Variable from the lower to the upper level problem. The implications of this change of the problem are investigated thoroughly. The resulting lower level problem is a generalized transportation problem. The formulation of conditions guaranteeing the existence of an optimal solution for this problem is also in the scope of this paper. The corresponding results are then used to find a bound on the optimal function value of our initial problem.
Riccardo Zecchina - One of the best experts on this subject based on the ideXlab platform.
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Statistical mechanics of the random K-SAT model
Physical Review E, 1997Co-Authors: Remi Monasson, Riccardo ZecchinaAbstract:The Random K-Satisfiability Problem, consisting in verifying the existence of an assignment of N Boolean Variables that satisfy a set of M=alpha N random logical clauses containing K Variables each, is studied using the replica symmetric framework of diluted disordered systems. We present an exact iterative scheme for the replica symmetric functional order parameter together for the different cases of interest K=2, K>= 3 and K>>1. The calculation of the number of solutions, which allowed us [Phys. Rev. Lett. 76, 3881 (1996)] to predict a first order jump at the threshold where the Boolean expressions become unsatisfiable with probability one, is thoroughly displayed. In the case K=2, the (rigorously known) critical value (alpha=1) of the number of clauses per Boolean Variable is recovered while for K>=3 we show that the system exhibits a replica symmetry breaking transition. The annealed approximation is proven to be exact for large K.
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Statistical mechanics of the random K-satisfiability model
Physical Review E, 1997Co-Authors: Remi Monasson, Riccardo ZecchinaAbstract:The random $K$-satisfiability problem, consisting in verifying the existence of an assignment of $N$ Boolean Variables that satisfy a set of $M=\ensuremath{\alpha}N$ random logical clauses containing $K$ Variables each, is studied using the replica symmetric framework of diluted disordered systems. We present an exact iterative scheme for the replica symmetric functional order parameter together for the different cases of interest $K=2$, $Kg~3$, and $K\ensuremath{\gg}1$. The calculation of the number of solutions, which allowed us [Phys. Rev. Lett. 76, 3881 (1996)] to predict a first order jump at the threshold where the Boolean expressions become unsatisfiable with probability one, is thoroughly displayed. In the case $K=2$, the (rigorously known) critical value $(\ensuremath{\alpha}=1)$ of the number of clauses per Boolean Variable is recovered while for $Kg~3$ we show that the system exhibits a replica symmetry breaking transition. The annealed approximation is proven to be exact for large $K$.
Nataliya I. Kalashnykova - One of the best experts on this subject based on the ideXlab platform.
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Applications to Natural Gas Cash-Out Problem
Energy Systems, 2015Co-Authors: Stephan Dempe, Vyacheslav V. Kalashnikov, Gerardo A. Pérez-valdés, Nataliya I. KalashnykovaAbstract:The nature of natural gas implies that imbalances occur between the declared and really extracted amount of gas in a pipeline system. The transmit system operator penalizes the gas shipping company for these imbalances. The task of minimizing the resulting cash flow is modeled as bilevel optimization problem with one Boolean Variable in the lower level problem. We report related models, arising in applications, if the Boolean Variable is shifted to the upper level problem or when stochastic data are implemented. Solution algorithms and numerical results are presented.
Vyacheslav V. Kalashnikov - One of the best experts on this subject based on the ideXlab platform.
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Applications to Natural Gas Cash-Out Problem
Energy Systems, 2015Co-Authors: Stephan Dempe, Vyacheslav V. Kalashnikov, Gerardo A. Pérez-valdés, Nataliya I. KalashnykovaAbstract:The nature of natural gas implies that imbalances occur between the declared and really extracted amount of gas in a pipeline system. The transmit system operator penalizes the gas shipping company for these imbalances. The task of minimizing the resulting cash flow is modeled as bilevel optimization problem with one Boolean Variable in the lower level problem. We report related models, arising in applications, if the Boolean Variable is shifted to the upper level problem or when stochastic data are implemented. Solution algorithms and numerical results are presented.
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discrete bilevel programming application to a natural gas cash out problem
European Journal of Operational Research, 2005Co-Authors: Stephan Dempe, Vyacheslav V. Kalashnikov, Roger Z RiosmercadoAbstract:In this paper, we present a mathematical framework for the problem of minimizing the cash-out penalties of a natural gas shipper. The problem is modeled as a mixed-integer bilevel programming problem having one Boolean Variable in the lower level problem. Such problems are difficult to solve. To obtain a more tractable problem we move the Boolean Variable from the lower to the upper level problem. The implications of this change of the problem are investigated thoroughly. The resulting lower level problem is a generalized transportation problem. The formulation of conditions guaranteeing the existence of an optimal solution for this problem is also in the scope of this paper. The corresponding results are then used to find a bound on the optimal function value of our initial problem.
Remi Monasson - One of the best experts on this subject based on the ideXlab platform.
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Statistical mechanics of the random K-SAT model
Physical Review E, 1997Co-Authors: Remi Monasson, Riccardo ZecchinaAbstract:The Random K-Satisfiability Problem, consisting in verifying the existence of an assignment of N Boolean Variables that satisfy a set of M=alpha N random logical clauses containing K Variables each, is studied using the replica symmetric framework of diluted disordered systems. We present an exact iterative scheme for the replica symmetric functional order parameter together for the different cases of interest K=2, K>= 3 and K>>1. The calculation of the number of solutions, which allowed us [Phys. Rev. Lett. 76, 3881 (1996)] to predict a first order jump at the threshold where the Boolean expressions become unsatisfiable with probability one, is thoroughly displayed. In the case K=2, the (rigorously known) critical value (alpha=1) of the number of clauses per Boolean Variable is recovered while for K>=3 we show that the system exhibits a replica symmetry breaking transition. The annealed approximation is proven to be exact for large K.
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Statistical mechanics of the random K-satisfiability model
Physical Review E, 1997Co-Authors: Remi Monasson, Riccardo ZecchinaAbstract:The random $K$-satisfiability problem, consisting in verifying the existence of an assignment of $N$ Boolean Variables that satisfy a set of $M=\ensuremath{\alpha}N$ random logical clauses containing $K$ Variables each, is studied using the replica symmetric framework of diluted disordered systems. We present an exact iterative scheme for the replica symmetric functional order parameter together for the different cases of interest $K=2$, $Kg~3$, and $K\ensuremath{\gg}1$. The calculation of the number of solutions, which allowed us [Phys. Rev. Lett. 76, 3881 (1996)] to predict a first order jump at the threshold where the Boolean expressions become unsatisfiable with probability one, is thoroughly displayed. In the case $K=2$, the (rigorously known) critical value $(\ensuremath{\alpha}=1)$ of the number of clauses per Boolean Variable is recovered while for $Kg~3$ we show that the system exhibits a replica symmetry breaking transition. The annealed approximation is proven to be exact for large $K$.