Phonological units for phonological change: synchrony shall provide them

The question of what types of units and domains are needed in order to capture phonological change is a reasonable one to ask. To answer this question, however, we first need to properly define how we understand phonological change, and the definition that we adopt for that clearly depends on the phonological framework that is assumed. I consider several influential frameworks here and then come to the conclusion that the same condition holds for all of them: change can only be described in terms of the same units (and domains) as are used for synchronic description. This leads to the following conclusion: the set of units for phonological change is a subset of the set of units that are needed for synchronic phonological description. However, it is also unlikely that some units needed for synchronic description can be fully ignored for all descriptions of changes, which leads us to the conclusion that the set of units that are needed for phonological change is also a superset of that set. The sets are thus equal: the phonological units needed for synchronic description are the units needed to account for phonological change, and the question above is meaningless

Estimation of 500 kV power transmission line parameters with PMU

This work is devoted to the research of the real-time estimation of 500 kV power transmission lines parameters with PMU based on the solution of the optimization problem of minimizing the root-mean-square deviations of the specific line parameters or the sum of the modules of the correlation coefficients between the specific parameters and the sum of the squares of the voltages or currents measured at the ends of the line. Independent optimization variables are the correction factors of the measuring systems of currents and voltages. Based on an artificially simulated PMU dataset with specified Gaussian noise and systematic errors, it is shown that the use of correlation coefficients in the objective function is more effective than standard deviations. All 5 estimated coefficients turned out to be closer to the reference values. The results of calculations are obtained from the data of real PMUs for an operating 500 kV line with a length of 504.6 km. The deviation of the specific capacitive conductivity from the nominal value is 0.13%, compared with - 0.29% when using the sum of squares of deviations as an objective function