A virtual instrument for determining basic parameters of sinusoidal signals in stationary modes

A virtual instrument is proposed for determining the frequency, amplitude, and initial phase of sinusoidal signals of voltage and current, as well as the angle of phase shift between the voltage and current, that is created in the LabVIEW development environment. Comparative analysis of errors of the proposed instrument and the standard virtual instrument Extract Single Tone Information VI from the LabVIEW package was performed, which has shown that the proposed instrument determines the signal parameters more accurately than the standard one if the signals are exposed to industrial noise and interferences.     

Distribution of impurities in steam-generating equipment with estimating the efficiency of their removal during the power unit shutdown process

The sludge distribution patterns in the volume of a steam generator and in the near-wall region of its heat-transfer surface are obtained. Recommendations for removing sludge in the power unit shutdown mode are given.     

EFFECTIVE DIFFUSION COEFFICIENT OF ACTIVE SOLVENTS IN COMPOSITE POLYMERIC MATERIALS

ABSTRACT

A method and a device for determination of the effective diffusion coefficient of active solvents in composite polymeric materials (CPM) based on cellulose derivatives are proposed and examined. This method accounts for anomalous mass transfer phenomena, considerable shrinkage and changes of sorption capacity of the CPM specimen allowing selection of the rational technological regime. Results of experimental studies on diffusion of acetone and ethanol in cellulose nitrate with various degrees of substitution are given as examples.     

Miniature coaxial resonator and related bandpass filter with ultra-wide stopband

Resonator of a new type is described, which is formed by two coaxial conductors applied onto the internal and external surfaces of a ceramic tube arranged in a metal case. An equation for the resonant frequencies is derived. In comparison to a standard coaxial quarter-wave resonator, the proposed device has a shorter length and manifold increased ratio of frequencies of the second resonance to the first resonance. The new resonator can be used for the creation of bandpass filters with ultra-wide stopband. The frequency response of a working prototype four-resonator filter is presented, in which the stopband at a −90 dB level extends up to a frequency that is 47 times greater than the central frequency of the passband.     

Solid-state track detectors in laser plasma investigations

The possibility of application of the solid-state track detectors, developed earlier for experimental nuclear physics, in laser plasmas investigations is considered. A review of the main physical and metrological properties of the solid-state track detectors is given. Special attention to the detector on the basis of the CR- 39 polymer plastic is made. The experimental layouts of the CR-39 applications for investigation of both the properties of the fast heavy particles generated in the femtosecond laser plasma and the properties of the various materials by irradiation by the flows of the fast particles emitted by the laser plasmas are investigated.     

Autothermal gasification of low-grade fuels in fluidized bed

Autothermal gasification of high-ash floatation wastes of Grade Zh Kuzbass coal and low-ash fuel in a suspended-spouted (fluidized) bed at atmospheric pressure is investigated, and a comparison is presented of experimental results that indicate that the ash content of fuels has only slight influence on the generator gas heating value.     

Synthesis gas production by steam reforming of ethanol

A two-layer fixed-bed catalytic reactor for syngas production by steam reforming of ethanol has been proposed. In the reactor, ethanol is first converted to a mixture of methane, carbon oxides and hydrogen over a Pd-based catalyst and then this mixture is converted to syngas over a Ni-based catalyst for methane steam reforming. It has been shown that the use of the two-layer fixed-bed reactor prevents coke formation and provides the syngas yield closed to equilibrium.     

Bandpass filter with an ultra-wide stopband designed on miniaturized coaxial resonators

Characteristics of a new miniaturized coaxial resonator are theoretically investigated. It is shown that the first resonant frequency of the resonator can be significantly lowered relative to the second one and the resonator dimensions can be considerably decreased as compared to those of a traditional dielectric-filled quarter-wavelength coaxial resonator. Based on the investigated resonator, a fourth-order bandpass filter has been designed and fabricated. The filter stopband at a level of no worse than ?90 dB extends to the frequency that exceeds the passband center frequency by a factor of 47. Calculated frequency responses are in good agreement with those measured on the fabricated filter prototypes.     

Robust control of electric generator in the case of time-dependent mechanical power

The problem of control of electric generator whose model is described by a third-order differential algebraic equation with a priori unknown parameters under uncontrollable external disturbance defined by an unknown time-dependent power is solved. When the problem is solved, it is assumed that the relative speed of the generator’s rotor can be measured. A control algorithm ensuring small amplitude of the rotor vibrations in the quasi-steady-state mode due to changes in the voltage at the excitation coil of the rotor is proposed. This algorithm also ensures the stable operation under emergency conditions caused by changes in the reactive resistance of the power transmission line. Numerical examples and the results of computer simulation are presented to illustrate the performance of the proposed control algorithm.