The article examines the influence of various superplasticizers on the performance characteristics of concrete. A series of tests of samples-beams of fine-grained concrete modified with plasticizers of various types was carried out. The optimal amount of the introduced additive was experimentally determined to compare the plasticizing effect of the cement-sand mixture. Experimental data are given indicating the main operational characteristics of the material depending on the additive used. The most effective additive "Polyplast SP-3" has been determined.
Keywords: concrete, fine-grained concrete, mixture, lignosulfonates, polycarboxylates, naphthalene sulfonates, plasticizer, superplasticizer, water demand, plasticity
In industrial production, stacker loaders used for loading and transporting goods packed on pallets are quite widely used in warehouse work. Basically, when performing a loading and transport technological operation, the functionality of the stacker is sufficient. When an obstacle appears or pallets are stacked, additional maneuverability is required, as a result of which the overall performance of the loader is lost. As a result of the conducted research, it was found that when bypassing obstacles and laying pallets, the time spent on maneuvering the chassis is up to 13%, while the utilization factor of the loader-stacker in terms of productivity is 0.7. Numerical modeling of the positioning process of the load-handling body of the loading and transport unit was carried out, on this basis, the design of a loader-stacker with expanded functionality was proposed and developed, in particular, the service area increased due to the use of a tripod manipulator and two guide actuators, which reduces the time of the technological operation of loading and unloading pallets in warehouse work. Geometrical, structural and kinematic parameters of the loader mechanism are calculated.
Keywords: numerical simulation, loader-stacker, service area, lifting body, manipulator, hinges, chassis, structural analysis, geometric analysis, kinematic analysis, executive drive, pallet
The problems of studying the mathematical interpretation of the results of trajectory measurements in terms of increasing the accuracy of identification of bearings of unmanned aerial vehicles during their movement in the group "swarm" and "system" are discussed. The variants of identification of horizontal (IHP) and spatial bearings (PPI) are proposed both separately and in a complementary application. Identification of bearings of similar objects in the swarm type group is expedient to be carried out according to the IGP-IPP algorithm. However, it is only partly operational at distances of 3 km or more. As the main algorithm for identifying bearings of similar objects in the "Story" group, it is advisable to use IPP. Although these algorithms achieve high identification efficiency under favorable conditions, with tougher conditions, they drop rather sharply. Therefore, to maintain a high level of probability of "pure" identification, it is advisable to use additional measures to combat false triads. For the removal of problems, it is necessary to develop and apply combinatorial algorithms for exhaustive search, which is the direction for the development of further research.
Keywords: unmanned aerial vehicle, group of objects, bearing identification, horizontal bearing, spatial bearing, identification criteria, false notch
Laser tracking locators have certain drawbacks, among which there is a strong influence of the atmosphere on their energy and precision parameters, the process of aiming a narrow beam at the object, etc. High requirements for locators (the error of measuring the range to a few centimeters) lead to the need to take into account the state of the atmosphere on the route for application Corrections in the measurements. In particular, the phenomenon of refraction leads to a significant distortion of the signal. To reduce the error of distance measurements it is advisable to use methods to compensate for the effect of refraction or to take it into account and use the correction coefficients. The article shows that the effective solution to this problem in the absence of the possibility of obtaining operational and accurate information about meteorological parameters is the use of parallel laser probing of the atmosphere. More promising in this case is the use of laser methods for controlling atmospheric parameters, which we described and experimentally investigated at the Chauda, Feodosiya, and the Republic of Crimea provinces. The obtained atmospheric data were used to create a mobile laser-television locator for external-trajectory measurements of the descent of the aeroelastic systems "Kafa" and were installed both on the ground and on an air balloon. The trajectories of the descent of balloons and cargo parachute systems were studied.
Keywords: Laser tracking locator, ranging channel, atmospheric effect, refraction, model compensation method, laser probing
Refraction has a strong influence on the accuracy parameters of the range-finding tract of laser tracking locators and the process of directing a narrow laser beam onto the object. High requirements for locators (the error of measuring the range to a few dozen centimeters) lead to the need to take refraction into account for making corrections to the measurements. Significant distortion of the signal leads not only to the phenomenon of static refraction, but also dynamic. To reduce the error of distance measurements it is advisable to use methods to compensate for the effect of static refraction or to take it into account and use the correction coefficients. The article shows that the most effective solution to the problem of refraction in the presence of a dynamic component is also the use of parallel laser probing of the atmosphere, but it must be carried out at two different wavelengths. In this case, the main method of calculating the correction factors is the dispersion method, which makes it possible to reduce the relative measurement error to 106. The use of laser methods for controlling atmospheric parameters, including two-wave and two-frequency ones, was described by us and experimentally investigated at the Chauda, Feodosiya, and the Republic of Crimea fires on YAG: Nb3 + IZ-25 lasers and continuous lasers . The obtained atmospheric data on the LT-5Z laser were used to create a mobile laser-television locator for external-trajectory measurements of the descent of the aerial systems "Kafa +" and were installed both on the ground and on an air balloon. The flight trajectories of balloons and the descent of cargo parachute systems were studied.
Keywords: Laser tracking locator, ranging channel, atmospheric effect, static refraction, dynamic refraction, dispersion compensation method, laser two-wave probing of the atmosphere
Promising absorbing materials along with a Ni-Zn-ferrites are Mg-Zn-ferrites, as they are also intensively absorbs electromagnetic waves in the frequency range from 50 MHz to 1000 MHz. The main advantage of the Mg-Zn-ferrite is used as an inexpensive raw material magnesium oxide. The paper presents the results of research to improve the efficiency of broadband radio-magnesium-zinc ferrite by increasing the contribution of the dielectric loss. The influence of alloying elements of the atmosphere gas and cooling after the sintering thermal radiation by absorption of electromagnetic waves. Confirmed cooling efficiency of products after sintering in an atmosphere with reduced oxygen partial pressure to increase the dielectric constant. A model is proposed to explain the increase in the dielectric loss ferrite during cooling in a reducing atmosphere.
Keywords: radioabsorbing ferrites, microstructure grain boundaries radio measurement radiation thermal sintering