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
Currently, loaders for piece loads used in the technological process of loading-transporting and laying barrels of oil are widely used in industry. In particular cases, during loading and transport operations, the functionality of the loader is sufficient, but when laying cargo or obstacles occur, it is necessary to maneuver using the loader chassis, which significantly increases the execution time of the technological process. The results of the conducted studies have shown that when performing the technological operation of capturing, transporting and stacking barrels, the time to move the chassis is up to 12%, while the loader performance coefficient is 0.65. Numerical modeling of the positioning process of the load-handling body of the output link of the loading and transport unit is carried out, on this basis, a loader design based on a stacker is proposed and developed. The degree of mobility of the manipulation mechanism is calculated.
Keywords: numerical modeling, loader, manipulator, hinges, chassis, structural analysis, degree of mobility, kinematic analysis, service area, lifting body, mechanism
The article presents a study of accidents on the roads involving children and persons under the age of majority. An analysis was made of the legal norms for the protection of the rights of the child on the roadway. In addition, an additional means of reducing accidents on the roads, as well as its location relative to the pedestrian, was identified.
Keywords: accident, traffic accident, child, children, incident, road, section, pedestrian
The article proposes new compositions of a fast-hardening concrete mixture using Portland cement, fine and coarse aggregates, basalt fiber, a complex modifying additive including acetone-formaldehyde resins and magnesium chloride (bischofite). The results of scientific and experimental studies are presented and the influence of the proposed additives on the formation of the structure, rheological and physico-mechanical properties of fast-hardening concrete is determined. Analysis of the test results showed that the proposed formulations, including a complex additive and basalt fiber, contributed to a decrease in the water-cement ratio, increased mobility of the mixture and increased strength of hardened concrete in the early and final hardening periods.
Keywords: concretes, oil and gas storage, modifying additives, fiber, mobility, setting time, strength
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 work is aimed at improving the algorithm of automated formation of solutions for the production of construction works based on the combinatorial approach. The essence of the approach is to form all feasible solutions for the production of construction works, taking into account the specified resources and constraints, and choosing the best option according to the specified criteria. At the same time, at some stages of the generation of altenatives, it is advisable to eliminate obviously losing options, in particular, it is proposed to take into account the losses from downtime of workers and construction machines formed due to some difference in the total productivity of workers and construction machines when forming the composition of resources for performing mechanized construction work. The proposed algorithm assumes the choice of the composition of resources for performing a mechanized technological process with minimal losses from idle resources.
Keywords: organizational and technological design, simulation model, algorithm, logical and mathematical model, combinatorial approach, multivariate design, automated control system in construction
The article describes the specifics of OOP concepts implementation in the open source projects that contain address book model in comparison to OASIS UBL Party Reference model. The open source software analysis is performed using the formal criteria for evaluating the matching between open source project models and reference model based on quantitative characteristics, conceptual graph transformation and cluster analysis. First, the scope coverage, elaboration factor and structural connectedness were calculated based on model parameters. Second, the domain models were represented as conceptual graphs and they were compared based on semantic equivalence. And third, the model was clustered into four subdomains, and quantitative characteistics were evaluated separately for each cluster. Based on the experimental results of model analysis the authors propose methods to reduce the conceptual mismatch between reference model and project models.
Keywords: OOP, semantic analysis, reference model, OASIS UBL, conceptual graph, cluster analysis
The article presents the usage of the semantic network for storing and retrieving information from unstructured sources. The authors describe the semantic network model based on labeled oriented graph, consider basic semantic network elements (concepts, relations and attributes) and basic relation types between elements (hyponymic and meronimic as well as class-instance relations), and define main single and group operations on the network. Besides the method of storing the concept instances and related wordforms and glosses for automated information retrieval from semi-structured sources is provided. The designed semantic network is decomposed into atomic concepts providing absence of stored information redundancy without necessity to apply the normalization procedure. The developed model was applied in several practical tasks, for example in real estate information parsing, the address information system input validation, and information extraction from spreadsheet data. The model was improved and extended based on experimental results.
Keywords: semantic network, graph model, concept, relation, attribute, instance, semi-structured data
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
The article describes how to maximize the profit of investment and construction projects on the basis of organizational and technological approach. The proposed model is value-based management based on organizational approach allows you to set goals not only on financial performance, but also to balance the interests of all projects
Keywords: projects; housing; value-based management
In this work we have investigated the structure of individual single-walled and multi-walled carbon nanotubes by high-resolution electron microscopy and electron diffraction. To grow carbon nanotubes we used a catalytic chemical vapor deposition method. It was shown, that this synthesis protocol gave in general single-walled and double-walled carbon nanotubes with a high level of crystallinity. The diameters of the nanotubes were in the range 1.5 - 7 nm. We also observed that there was a certain level of amorphous carbon deposited on the nanotube surface during the growth. In this work we also present the structure analysis of the double-walled carbon nanotube by means of electron diffraction. We show that the structural date derived from electron microscopy and electron diffraction agree within the experimental error.
Keywords: Carbon nanotubes, electron diffraction, electron microscopy
To date, the main method of mass production of advanced functional materials for various purposes is the ceramic technology. In the manufacture of multi-component oxide compounds using of ceramic technology is difficult to achieve high uniformity of chemical composition. For activation of the raw ingredients and make it more uniform use of chemical-tions (co-precipitation of salts or hydroxides, spray drying, Cryochemistry) and physical-tions (mechano-chemical, microwave, ultrasonic) methods. The paper presents the results of work on obtaining Ni-Zn-ferrite 2000NN radiation-thermal sintering. The influence of base composition and alloying additions on the electromagnetic properties of the ferrites. Confirmed the effectiveness of the use of surface-active additives To increase the density of the raw pieces and level parameters. We propose a model that explain schaya efficiency of dopants in the radiation-thermal sintering.
Keywords: Nickel-zinc ferrite, radiation thermal sintering, base composition, alloying additives, permeability
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