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This letter presents a simple optimal placement algorithm of phasor measurement units (PMU) by using integer linear programming. Cases with and without conventional power flow and injection measurements are considered. The measurement placement problems under those cases are formulated as an integer linear programming which saves the CPU computation time greatly. Simulation results show that the proposed algorithm can be used in practice.Index Terms-Integer linear programming, observability analysis, phasor measurement units.

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This paper presents an algebraic method that uses the triangular factors of singular, symmetric gain matrix to determine the observable islands of a measured power system. This is accomplished in a noniterative manner via the use of selected rows of the inverse factors. Implementation of the proposed method presents little additional effort, since sparse triangular factorization and forward/back substitution procedures common to existing state estimators, are the only required functions. The method is further extended for the choice of pseudo-measurements in order to merge the observable islands into a single observable system. Numerical examples are given to illustrate the details of the proposed methods.Index Terms-Observability analysis, measurement placement, observable islands, sparse triangular factorization, forward/back substitutions.

Nine triply excited states of lithium are calculated with the saddle-point and saddle-point complex-rotation methods. Relativistic corrections are computed with first-order perturbation theory. The widths are studied with one open channel at a time as well as fully coupled open channels. Some coupled calculations include up to ten open channels. Radiative decays of the triply excited states are also computed. The predicted Auger branching ratios are in excellent agreement with experiment. An identification is found for a weak line in the observed Auger spectra. Our predicted 2s2s2p P width is substantially smaller than the experiment of Kiernan et al. [Phys. Rev. Lett. 72, 2359 (1994)] but it agrees much better with the recent experiment of Kiernan et al. [J.

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