No. 1

On compensation of disbalance of high-frequency differential sensor

A method for compensation of parasitic disbalance in differential sensor connected to high-frequency excitation circuit is suggested, with special emphasis on suppression of effects of vibration and other disturbing factors. The output of the sensor is amplified, detected and digitised to produce a vector consisting of quadrature components. Additional repetitive measurements are performed with transducers of the sensor being de-energised one after another. A compensation is performed by means of vector calculations. The results of additional measurements are used to neutralize the influence of disturbing factors on the completeness of disbalance compensation.

The method was employed in experimental multi-element capacitive differential sensor for monitoring of paper sheet thickness non-uniformity. The excitation frequency of the sensor is 50 MHz, the sheet speed is 2 m/s, the capacitance of a single capacitive element is 640 fF, and the response time equals to 24 microseconds per differential pair of elements. The experimental results showed complete compensation of disbalance despite strong mechanical vibration. When used with a uniform test sheet, the resulting fluctuations fit 8 micrometer interval which is equivalent to 2,6 fF interval of capacitance.

Keywords: differential capacitive sensor, differential inductive sensor, disbalance, vector calculations.

Development of a mathematical model of a dual-circuit vibration protection system for inertial navigation systems including laser gyroscope

The article describes the issues of development a model of dual-circuit complex for shock-absorption of aircraft inertial navigation system, including laser gyroscope with vibro-frequency division. There are the elastic-mass model of the depreciation complex and describing it equations. The amplitude-frequency characteristics of the contours of shock-absorption complex, determined in accordance with developed model, are shown in the article too. In the end are given recommendations that should be taken into account when develop such devises.

Keywords: inertial navigation system, dual-circuit shock-absorption protection system, amplitude-frequency characteristics.

Model ranges non-contact gauges temperatures

The article is devoted to the recent trend in the development of contactless temperature meters (pyrometers), which consists in a high level of unification of the developed products and the creation of model ranges. Using the Thermocont model range as an example, it is shown how following this trend allowed us to create the widest range of pyrometers in Russia with minimal development costs.

Keywords: temperature measurement, pyrometer, unification, model range.

Lens piezoactuator of the system for measuring dither parameters in a laser gyro

In this paper we consider the optoelectronic system that measures relative vibration parameters of a laser gyro sensing element in the dither mode. The system enables to compensate the component of the gyro output signal caused by these oscillations. Mentioned measuring system consists of a miniature flat pattern plate mounted on the sensing element, an optoelectronic module mounted on the laser gyro body and an electronic signal processing unit. The operation principle of the system is based on registration of laser radiation reflected from areas of the pattern plate with micromarks. The measuring system lens piezoactuator, which serves to maintain its optical characteristics, is described. The mathematical model of the actuator is given, as well as a description of its control system. The results of numerical simulation of lens movement, which position is adjusted by the piezoactuator, are shown.

Keywords: laser gyro, ring laser, dither system, optoelectronic system, piezoactuator, mathematical model, control system.

Principles of modernization of gas units and schemes of analytical control devices

In this paper, the main principles of the ongoing modernization of gas units and pneumatic circuits of analytical control devices are considered.

Keywords: analytical control instruments, nitrogen, argon, oxygen, hydrogen, helium, modernization of devices.

A fastener assembly of temperature sensor elements on the surface of a thermal expansion absorber of busbars

This paper describes the design development of fastener assembly for mounting of the fiber-optic temperature sensors on the warped surface of the thermal expansion compensators of high-current DC busbars.

Keywords: ITER (International Thermonuclear Experimental Reactor), thermal expansion compensator, temperature sensor.

Mathematical model for measuring strain and temperature with a fiber-optic sensor

The materials present a mathematical model for measuring strain and temperature with a fiber-optic sensor based on a fiber Bragg grating, taking into account the compensation for the creep of the adhesive layer due to external temperature effects on the sensor. The results of evaluating the adequacy of the model for compensating the temperature creep of a fiber-optic strain sensor are presented. Based on the results of mathematical modeling, an approach to measuring deformation parameters with the allocation of time sections corresponding to temperature intervals with characteristic values of the parameters of the creep function is proposed.

Keywords: fiber-optic strain gauge, measurement, fiber Bragg grating, monitoring system, creep.

Method for modifying the composition of non-combustible composite coatings based on powdered alumino oxides for electromagnetic shields

A method for modifying the composition of non-combustible composite coatings based on powder alumina (electrocorundum, alum earth) for electromagnetic shields in order to improve radioabsorbing and radioshielding properties of such coatings has been described. It is shown that when using this method, it is possible to reduce by 1.0…6.0 dB of these coatings electromagnetic radiation reflection coefficient values in the frequency ranges 0,9…4.0 GHz, 11.0…17.0 GHz (provided that they are applied to a metal substrates) and by 4.0…12.0 dB of its electromagnetic radiation transmission coefficient values in the frequency range 0.7…17.0 GHz (provided that they are applied to a cellulose substrates). It has been found that composite coatings based on powdered alumino oxides for electromagnetic shields, the composition of which is modified in accordance with the proposed method, are non-combustible. It has been experimentally confirmed that, as a result of heat treatment of such coatings, it is possible to provide a reduction by 2.0…15.0 dB dB of their electromagnetic radiation reflection coefficient values in the frequency range 1.2…6.0 GHz (provided that they are applied to a metal substrate).

Keywords: alumino oxide, alum earth, composite material, reflection coefficient, transmission coefficient, electromagnetic radiation, electrocorundum.