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This paper describes a knowledge model for the design of Massive Open Online Course (MOOC) platforms. It is based on our generic instructional engineering method called Knowledge Field of Educational Environment with Competence Boundary Conditions (KFEEC). KFEEC uses the ontology as a foundation for the knowledge representation model. It provides a flexible structure to the various self-paced e-learning system designs but appears to be overcomplicated for the MOOC platform. This paper describes the KFEEC method, the steps of adapting the KFEEC to the MOOC platform design, and the specification of the resulting knowledge model. This model is a core of the MOOC platform that will be developed in future work.

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The error of root-mean-square voltmeters in a broadband voltage measurement is considered, and proposals are made for standardizing the metrological characteristics of those voltmeters so that the error of measurement of the signals can be evaluated. Several versions of an automatic error estimater to be incorporated into the voltmeter circuit are described.Root-mean-square (rms) voltmeters are designed to measure sinusoidal as well as nonsinusoidal voltages. Clearly, if the signal is nonsinusoidal it has a more or less broad spectrum. Since the voltmeter has a limited operating range, the question is what are the allowed input nonsinusoidal signal frequency and the error of measurement of that signal.It was shown in [1] that the way that the metrological characteristics of rrns voltmeters are standardized at present, the error of measurement of nonsinusoidal voltages cannot be estimated. The experimental data reported in [1] show that the voltmeter error in the measurement of a distorted voltage can be several times that specified even for signals that have a frequency hundreds or thousands of times lower than the upper limit of the operating range of the instrument.The rms voltmeters considered here have an operating frequency range with an upper limit of up to a few megaberz. The instrument reading distortions caused only by the irregularity of the amplitude-frequency characteristic (AFC) are investigated. In principle, when high-frequency nonsinusoidal voltages are measured there is one more cause of error, which is associated with a characteristic of the voltmeter functional units such as the limitation of the rate of growth of their output voltage, but it is not taken into account in this article. We assume that the rms voltmeter is otherwise ideal. Below we consider the error of an rms voltmeter in a measurement of a broadband voltage, make proposals for standardization of the metrological characteristics that allows the error of measurement of such signals to be evaluated, and describe several versions of a unit that could be added to the voltmeter circuit to automate the error revaluation. Nonsinusoidal periodic voltage is described by a spectrum consisting of a series of harmonics. In [2] we showed that in the measuring channel of an rms voltmeter the" error of conversion of each harmonic depends on the frequency of that harmonic or, to be more exact, on the frequency of the harmonic and the rms of the voltage measured.Suppose that the voltmeter input receives a voltage with an rms value of

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