The article investigated the optical-frequency gas flow meter based on a transistor structure with negative differential resistance (NDR). A schematic diagram and design of an optical-frequency gas flow transducer that operates in the microwave range (0.85 to 1.5 GHz), which consists of a bipolar and field-effect transistor with a Schottky barrier, is proposed as a photosensitive element using a photoresistor. A mathematical model of an optical-frequency gas flow meter based on a transistor structure with negative differential resistance has been developed, which allows one to obtain the main characteristics of the transducer in a wide frequency range. Theoretically and experimentally, the possibility of controlling both the reactive component and the negative differential resistance from changes in control voltage and power is shown, it extends the functionality of optical transducers and allows linearization of the conversion function within (0.1 - 0.2)%. Experimental studies have shown that the greatest sensitivity and linearity of the conversion function of an opticalfrequency gas flow transducer lies in the range from 3 V to 3.5 V. The sensitivity of the developed optical-frequency gas flow transducer based on a transistor structure with NDR is 146 kHz/liter/hour, and the measurement error is ± 1.5%.
The article describes the foundations of using method of using laser Doppler flowmetry in evaluation of the state of blood microcirculation system in students, future software engineers. By the method of laser Doppler flowmetry (LDF) individually-typological features of indicators of tissue blood flow in conventionally healthy adolescent students aged 17-20 years have been studied. Due to the results of research 3 types of LDF-grams have been defined: aperiodic, monotonous low amplitude, sinusoidal type with high perfusion. Among the examined students, future engineersprogrammers different frequency of appearing microcirculatory types with predominance of normoemic type with characteristic “aperiodic” LDF-gram has been found.
In recent years, a tendency is established to reduce the size of orbital spacecrafts while preserving their functional capabilities. The modern element base allows to create inexpensive Earth-sensing satellites having 1U-2U form factor, which are capable to form images of the Earth's surface with the medium spatial resolution. To perform synthesis of such optoelectronic remote sensing equipment, a relatively simple calculation technique is required. In this article, a technique has been developed to estimate an information system "Earth’s surface – atmosphere – television camera". It allows to determine the basic parameters of a lens and a matrix detector of the television camera, based on harmonization of their resolution and providing a given spatial resolution on the surface of the Earth. By using the proposed technique, a lens and a matrix detector have been selected. They provide geometric resolution of 25 m at the orbit with a height of 600 km. The resulting technical solution enables to fulfil applied tasks, for example, in agriculture, and can be implemented in a nanosatellite with the 1U-2U form factor.
In this article, we work with turbo codes, which are widely used to reduce bit error rate in digital communication systems. we start with a brief discussion of the mathematical apparatus, which is connected with the turbo decoding algorithms. the key implementation issue for these algorithms is the overall high decoding complexity. therefore have been presented some estimations of the implementation complexity of the turbo decoding algorithms on digital signal processor.
In this article, we investigate the mathematical model of a digital optoelectronic processor for the purpose of determining the signal at the processor’s output. The study of the model allows us to determine the distortions of the input signal of the processor, which are caused by the matrix spatio-temporal modulator. The developed physical and mathematical model of the processor made it possible to obtain an analytical expression for the signal at the processor’s output. Its analysis shows that the formula for determining the spatial frequency differs significantly from the traditional formula. The spatial frequency depends on positions of the central and side maxima in the first-order diffraction maximum. In this case, the signal spectrum can be determined by measuring the lateral maximum, which is located closer to the optical axis of the processor. This allows to use of smaller matrix detectors, as well as to investigate the signal spectrum beyond the Nyquist frequency of the modulator.
The work is devoted to the development of an eight-digit priority encoder constructed on monoimmittance logic gates. The electric circuit on the properties of the long lines in the microwave range was developed. The mathematical model and additional optimization were carried out. The monoimmittance priority encoder computer simulation was performed. The advantages of the developed monoimmittance priority encoder are increased speed, simplicity of design, passive power supply, absence of a threshold of minimum operating voltage and increased immunity to electromagnetic interferences.