David J. Clements

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The purpose of this paper is to provide an evaluation of the three open-source LP optimization codes, GLPK, COIN-LP (CLP) and LPSOLVE in solving electricity spot market optimization problems. The paper describes a technique for automatically generating over 100 locational marginal pricing (LMP) electricity spot market optimization problems, each being(More)
A solution X of a discrete-time algebraic Riccati equation is called unmixed if the corresponding closed-loop matrix Φ(X) has the property that the common roots of det (sI − Φ(X)) and det (I − sΦ(X) *) (if any) are on the unit circle. A necessary and sufficient condition is given for existence and uniqueness of an unmixed solution such that the eigenvalues(More)
The only string models known to reproduce the Minimal Supersymmetric Standard Model in the low energy effective field theory are those constructed in the free fermionic formulation. We demonstrate the existence of quasi– realistic free fermionic heterotic–string models in which supersymmetric singlet flat directions do not exist. This raises the possibility(More)