Showing papers in "Eastern-European Journal of Enterprise Technologies in 2018"

Studying the recurrent diagrams of carbon monoxide concentration at early ignitions in premises

Abstract: It was shown that the methods of nonlinear dynamics, surpassing traditional methods of temporal, frequency or frequency-temporal analysis of dangerous ignition factors may be used for early detection of ignitions in premises. The existence of carbon monoxide in gas medium was found to be most dangerous at fires in premises. The theoretical grounds for studying recurrent diagrams of carbon monoxide concentration in gas medium were substantiated. The modification of recurrent distance diagrams, based on power representations was proposed, making it possible to highlight selectively or to smooth structural features of configuration of recurrent points of distance diagrams. Results of research into recurrent diagrams of dynamics of carbon monoxide concentration show that the specified factor of ignition of materials has generally not stochastic, but chaotic dynamics. It was qualitatively determined that dynamics of carbon monoxide concentration in gas medium has non-uniformed distribution of points. In this case, the configuration of clustering of recurrent points of diagrams for various flammable materials varies and can be used for detecting the type and the beginning of early ignition of combustible material. The established fact of chaotic dynamics of carbon monoxide concentration in gas medium at early ignition of materials should be taken into consideration in the development of new technologies for reliable detection of early ignitions in premises. The data, obtained in the research, are important for deeper understanding of dynamics of the process of carbon monoxide formation in gas medium in non-airtight premises at ignition of various materials, because it is related to saving lives of people who are in these premises and their timely evacuation.

Development of the method for decomposition of superpositions of unknown pulsed signals using the second­order adaptive spectral analysis

Abstract: We considered the issue of "intuitive" analysis, processing, and synthesis of unknown pulse sequences in a detailed form. We studied both classical methods of analysis with all pluses and minuses and the developed prospective method created on their basis. The developed method is adaptive, it is based on the consistent use of various methods of spectral analysis, which increases reliability, sensitivity, and resolution capability of visual analysis of echo-pulse images. Thus, we solved the problem on processing pulse signals. The proposed method makes it possible to increase resolution capability in the processing of signals and images without using a priori information on the form of elementary pulses. It is resistant to the influence of measuring noise. We presented the results of numerical simulation and actual verification on the example of a seismic image. The considered method has a significant development potential, both in theoretical and application aspects (first of all, in areas of ultrasonic medical diagnosis, seismic imaging, and non-destructive testing).

Analysis of correlation dimensionality of the state of a gas medium at early ignition of materials

Abstract: We have considered the application of the method of nonlinear dynamic systems in order to analyze and detect the structural patterns in the dynamics of increments in the state of a gas medium generated by early ignitions of materials in a non-sealed chamber. The research method is based on analysis of the correlation dimensionality of increments in the state of a gas medium during ignition of materials. We have theoretically justified the method for evaluating the dynamics of correlation dimensionality of increments in the state of a gas medium at ignition. The considered method for CD evaluation is based on the computation of the Grassberger-Procaccia correlation integral, applied to the gas medium state increments using a sliding window with a fixed width. That allowed us to derive a current estimate of CD increments in the state of the gas medium during ignition of flammable materials in a chamber synchronized with the observation data acquisition rate. We have analyzed the dynamics of correlation dimensionality of increments in the state of a gas medium at early ignition of alcohol, paper, wood, and textiles in a simulation chamber. It was established that for the investigated state of the gas medium during ignition of various examined materials, the dynamics of correlation dimensionality is within 0.1 to 0.6. It is noted that this fact testifies to the fractal structure of the considered increments in the state of a gas medium in a chamber and its chaotic dynamics at the emergence of ignition sites of tested materials. In this case, the fractal structure is not the same, suggesting a "transitional chaos" in the examined state of the gas medium. It was established that current estimates of the correlation dimensionality of increments in the state at the time of materials ignition tend to a sharp increase. A given fact can be used to reliably detect early fires indoors. The results obtained are important for the in-depth studying and understanding of patterns in the structure of dynamics of increments in the state of a gas medium at early ignition. It has been shown the increments in the states of a gas medium at premises characterize it as a chaotic dynamic system with a small fractal dimensionality as opposed to the traditional approach assuming a gas medium being either deterministic or random system

Improving the installation for fire extinguishing with finely­dispersed water

Abstract: Fires at residential buildings are extinguished by both compact and sprayed jets of water. The result of fire suppression at facilities using compact jets of water is the increased consumption of water, which leads to collapse of the structures at a building. The application of water firehoses without fire-rescue vehicles is also impossible. Water that is sprayed to the droplets of small size makes it possible to extinguish a flame mainly by the dilution of a gas combustible medium with water vapor, formed during evaporation of droplets. The effectiveness of fire extinguishing with finely-dispersed water is affected by a diameter of the droplets or dispersion. It is proposed, to suppress developed fires at facilities, to apply the installation of fire extinguishing with finely-dispersed water of the pulse-periodic action. We have tested the designed installation for fire extinguishing. Based on the research results, we obtained parameters for the operation of the installation, such as the velocity of the shock wave, which amounted to 1,667–1,724 m/s. It was established that one detonation cycle uses about 30 mg/cycle of combustible mixture. Detonation cycle frequency is greater than 20 Hz. The estimated total power of the installation is 50 kW. According to results of the study, we found that the transition of combustion into detonation occurs at the expense of compression and heating of the combustible mixture. The established parameters for the operation of the installation make it possible to disperse water jets in the installation's barrel by a flow of detonation products. The resulting dispersion of a finely-dispersed water jet by the method of trapping the droplets of water is within 60‒100 µm. Based on the results of our study, it was established that an optimum water feed to the installation is 0.5‒1 l/s, which depends on the area of a fire. This means that during operation water consumption to suppress a fire would equal 1,800 l, which would enable the removal of heat from a fire site at about 4 GJ/h; the area of a fire in this case would make up 125 m 2 .

Development of the technique for restricting the propagation of fire in natural peat ecosystems

Abstract: In order to reduce the scale of peat fires, we suggest using fire barriers made of mineralized materials. The incombustible materials are proposed, specifically sand and bentonite clay, to be used for filling up artificial slits cut in a peat layer. Construction of anti-fire barriers requires a one-time expenditure, in contrast to the existing techniques for fire prevention that require continuous pumping of water in order to increase moisture content in peat. Mathematical modeling of thermal processes in the system peat layer–fire barrier was performed. The time of reaching the dangerous temperature by the protected layer, for the barriers made of river sand with a thickness of 300 mm, and for those made of bentonite clay with a thickness of 180 mm, is not less than 1 day. Given this, we have proven the effectiveness of the proposed barriers. By using mathematical modeling of the processes of fire development, a parabolic dependence was built of the thickness of fire protection barrier b, mm, on time τ, hours, required to protect an object. We established parameters for regression dependences of thickness of a barrier on the time required to protect a peat layer. The result of present research is the proposed technique for designing fire protection barriers made of river sand and bentonite clay, based on the obtained patterns and regression dependences. Research results could be used in the process of designing fire protection barriers for actual peatlands

Development of methods for estimating the environmental risk of degradation of the surface water state

Abstract: We presented three new methods for assessment of the environmental risk of deterioration of a surface water state. We defined the ecological risk of deterioration of surface water at the state level as an addition of the integrated parameter of the state of surface waters and the integral index of anthropogenic loading. We used the official information of the National Report on the state of the environment of Ukraine to calculate the mentioned indicators. We developed classifications of anthropogenic loading on aquatic ecosystems and ecological risk of deterioration of water ecosystems. The assessment of the ecological risk of deterioration of surface water state in Ukraine showed that there are watercourses of the Siversky Donets river basin in the most dangerous state. A base of the methodology for assessment of the risk of water ecosystem well-being disruption is the determination of all parameters of the state of quality of surface waters that exceed the ecological standards using the probit-regression model. The process of determining ecological risk for watercourses of the Siversky Donets river basin in Kharkiv region showed a high level of danger to the well-being of the water ecosystem of the Udi river. We obtained the forecast of climatic changes by parameters of temperature and volumes of precipitation in Kharkiv region. We investigated the dynamics of wastewater discharge to the Udi river for the period from 1992 to 2016. The study on an influence of natural and anthropogenic factors on the ecological state of the Udi river revealed that the impact of wastewater discharge with a correlation coefficient of 0.747 is a significant factor. The application of a new methodology for assessment of the risk of degradation processes made it possible to determine a list of small rivers in Kharkiv region, which require implementation of measures based on the analysis of water use efficiency, taking into consideration landscape and ecological features of a catchment area. We proposed an algorithm for the improvement of water protection strategy based on determining the ecological risk of deterioration of the condition of surface water at the state, regional and local levels. The improvement of water preservation strategy aims at introduction of an integrated interactive surface water quality management.

Experimental study of the fluctuations of gas medium parameters as early signs of fire

Abstract: The results of the experimental study of fluctuations of dynamics of hazardous factors of gaseous medium at early ignition of combustible materials in the chamber, simulating pressurized premises, are presented. The authors considered a non-traditional approach to research into dynamics of hazardous factors, based on current window estimation of the Pearson lag correlations for fluctuations of the main parameters of gaseous medium as non-stationary processes. In contrast to the known approaches, a given approach makes it possible to perform reliable localization in time of an early ignition of materials in premises. It was established that early ignition of materials has a significant effect on correlations of temperature fluctuations, concentrations of carbon monoxide and smoke in gaseous medium. It was shown that correlations of fluctuations of carbon monoxide and smoke concentrations are most informative for localization of early ignitions. Temperature fluctuations are more informative at localization of early ignition of alcohol and paper. The results of current window evaluation of the Pearson lag correlations show that in the absence of ignitions, fluctuations can be considered uncorrelated. In this case, existence of ignition leads to occurrence of non-stationary fluctuations of correlations. It is indicated that fluctuations of parameters of gaseous medium in the general case are described by autoregression processes of higher order, depending both on the type of combustible material and the stage of ignition development. A sustainable sign of early ignition of combustible materials in the simulation chamber is a significant increase in the correlation interval of non-stationary temperature fluctuations, as well as concentrations of carbon monoxide and smoke in gaseous medium. In equilibrium of gas medium, fluctuations of its parameters have a much smaller correlation interval, characteristic for uncorrelated processes

Method of integral estimation of channel state in the multiantenna radio communication systems

Abstract: A method of integrated estimation of channel state in multiantenna radio communication systems was developed. The distinguishing feature of the proposed method is estimation for several indicators, namely the bit error probability in the channel, frequency and pulse response of the channel state. After obtaining of the channel estimate for each indicator, a generalized channel state estimate is formed. Formation of the channel state estimate for each of the estimation indicators takes place in a separate layer of the neural network using the apparatus of fuzzy sets after which a generalized estimate is formed at the neural network output. Development of the proposed method was determined by necessity to raise speed of estimation of the channel state in multiantenna radio communication systems at an acceptable computational complexity. According to the results of the study, it has been established that the proposed method makes it possible to increase speed of estimation of channel state in multiantenna systems on average up to 30 % depending on the channel state while accuracy of the channel state estimation decreases by 5‒7 % because of reduced informativeness of estimation (because of using the apparatus of fuzzy sets) and is able to adapt to the signaling situation in the channel by training the neural network. Neural network training takes place on the basis of a training sequence and completes adaptation to the channel state after 10‒12 iterations of training. It is advisable to apply this method in radio stations with a programmable architecture to improve their interference immunity by reducing time for making decision on the channel state.

Development of the method of frequency­temporal representation of fluctuations of gaseous medium parameters at fire

Abstract: The method of operative frequency-temporal representation of fluctuations of gaseous media parameters at an early stage of fire at premises was developed. The basic assumptions about the peculiarities of dynamics of hazardous factors of gaseous medium at early ignition at premises were stated. The authors created theoretical framework for development of the method, based on the fact that violation of equilibrium state of gaseous medium is translated by the medium to the zone of sensors’ localization and responds to emergence of an ignition in premises. The fire source in this case is considered a moving source of disturbances and parameters of the medium carry information about temporal and frequency shifts of disturbances. It was shown that these shifts of disturbances are characterized by the correspondent uncertainty function, which is an invariant with respect to the double Fourier transformation, determined by squared modulus of frequency-temporal energy density of the parameter. The proposed method is a further development of frequency-temporal representations of the Cohen class in case of fluctuations of gaseous medium parameters at early ignitions in premises. The main features of the method are its relative simplicity and the use of data in real time. The verification of the developed method was performed based on the experimental data of the main parameters of the gaseous medium at an early ignition of alcohol, paper, wood, and textiles in the simulation chamber.

Influence of ultrasound and template on the properties of nickel hydroxide as an active substance of supercapacitors

Abstract: Nickel hydroxide is widely used as an active material s of supercapacitors. The most active are Ni(OH) 2 (α+β) samples with layered structure synthesized in a slit-diaphragm electrolyzer. The study on the influence of template synthesis and ultrasound treatment on the characteristics of the samples was conducted. The synthesis of nickel hydroxide samples in the presence of polyvinyl alcohol as a template and the use of ultrasound treatment of the Ni(OH) 2 suspension directly after formation was carried out. The synthesized samples of nickel hydroxide were studied by means X-ray diffraction analysis, scanning electron microscopy, and BET nitrogen adsorption-desorption. Electrochemical characteristics were evaluated by means of galvanostatic charge-discharge cycling in the supercapacitor regime. Comparative analysis of the Ni(OH) 2 sample has revealed both negative and positive effect of the template and ultrasound. The use of PVA as a template and ultrasound treatment resulted in a significant decrease in specific surface area (to 6 m 2 /g) and an increase of the average pore diameter (to 1181 Ǻ). Application of the template and ultrasound decreases crystallinity and increases the content of α-form, which results in the increased capacity of the samples. The maximum value of 233 F/g is achieved at a current density of 40 mA/cm 2 obtained from the combined effect of the template and ultrasound. Under these conditions, the specific capacity of the sample prepared without the template and ultrasound is 76 F/g. However, with an increase of current density to 120 mA/cm 2 , the capacity of this sample increases to 303 F/g. At the same time, for samples synthesized with the template and ultrasound, a decrease of capacity is observed at higher current densities, which is related to difficulties in the breakdown of agglomerated particles. In case of the introduced template, this is explained by the binding effect of the remaining PVA and in case of ultrasound treatment – particle condensation. Based on the results of the comparative analysis, it is recommended to replace the template with a more easily removable one and also conduct an electrochemical synthesis of Ni(OH) 2 in SDE directly in the ultrasound field and increase the power of the emitter.

Research into a possibility to prolong the time of operation of universal open top wagon bodies that have exhausted their standard resource

Abstract: The intensification of utilization of railroad cars predetermines the wear of their bodies as the most loaded element of design and necessitates the introduction of new cars. To reduce the cost of manufacturing new car designs, it is proposed to prolong the operation of universal open top wagon bodies beyond standard 1.5 operation terms. When carrying out calculations for strength under conditions of wagon building enterprises, the normative magnitudes of loading are applied, which do not take into consideration possible wear in the elements of bearing structures of open top wagon bodies under operation. This can lead to a significant error when determining a possibility to extend a period of operation of open top wagon bodies that have exhausted their standard resource. Therefore, when substantiating a possible prolongation of the operation period of cars it is important to take into consideration, at the stage of strength estimations, the refined magnitudes of dynamic loads acting on them in operation. To investigate dynamic loading acting on a open top wagon body during an impact at shunting, which is the case of the greatest loading to its structure, we employed mathematical modeling. The results of present research allowed us to conclude that the acceleration that acts on the bearing structure of a open top wagon with the wear characteristic of 1.5 terms of operation during an impact at shunting is about 4g. In addition, research into dynamic loading of the bearing structure of a open top wagon body during an impact at shunting was performed using computer simulation based on the software CosmosWorks. The research results showed that the maximum accelerations of a open top wagon body make up approximately 5g. To verify the adequacy of the developed models, we used the Fisher criterion. Results of the calculations have shown that the hypothesis of adequacy is not contradicted. The research results obtained were taken into consideration when determining strength indicators of a open top wagon body with the wear characteristic of 1.5 terms of operation. To this end, we constructed a spatial computer model of the body of a base open top wagon, model 12-757, whose bearing elements are of the thickness corresponding to the minimally defined one. The calculation employed a method of finite elements. Based on the performed calculations it was determined that the maximum equivalent stresses do not exceed the permissible ones and make up about 345 MPa, which makes it possible to draw a conclusion about the possibility of further utilization of a railroad car. The study conducted would help determine the feasibility of prolongation of service operation of open top wagons that have exhausted their standard resource.

Development of methods, models, and means for the author attribution of a text

Abstract: The level of accuracy of author attribution of a text is not high enough at the lexical and syntactic levels of a language as these levels are not strictly organized systems. In this study, the author attribution of a text is based on the differentiation of phonostatistical structures of styles. We have developed a system of differentiation of phonostatistical structures of styles, which differs from the existing ones by the chosen level of a language ‒ phonological. At this level of a language one can obtain results with a greater accuracy. In addition, the system constructed is based on a modular principle, which makes it possible to rapidly modify the developed software. We have developed methods and models that are based on the theory of mathematical statistics and allow the improvement in the accuracy of differentiation of phonostatistical structures of styles. A method was devised for a comprehensive analysis of phonostatistical structures of styles, as well as a multifactor method for determining the degrees of action of factors related to style, substyle, and author's manner of presentation. We have constructed a statistical model of stylistic differentiation using the ranking method, and a statistical model for determining a general stylistic markedness of the examined text. A software system for the differentiation of texts was designed. The criterion for the differentiation of texts is the mean frequencies of groups of consonant phonemes. In the process of implementing a system we used the programming language java, which ensures that the software is platform-independent. This study reports results of the application of the developed methods, models, and software tools. The research results confirm that author attribution of a text at the phonological level is more effective. The developed methods, models, and means for the author attribution of a text could be used when determining the percentage of creative contribution of each of the co-authors of scientific papers.

Aspects of program control over technological innovations with consideration of risks

Abstract: The dynamic system of control of technological innovations is considered Its dynamics is described by a vector linear discrete recurrent ratio and influenced by control parameters (controls) and an uncontrollable parameter (vector of risks or obstacles) In this case, the risks in the system of control of technological innovation will imply factors that influence negatively or catastrophically the results the processes, considered in it To solve the problem on control over technological innovations, we proposed methods based on the construction of predictive sets – reachability regions of the considered dynamic model These are the sets of all permissible states of a phase vector of the system at an assigned moment, correspondent to the fixed program control and to all permissible vectors of risk This procedure is accompanied by the minimax-based method for finding a guaranteed result Its essence is that the value of the worst (maximum) vector of possible risks is the least compared with similar values for the others at minimally guaranteed optimal control Thus, we minimize the impact of risks in the problem of control of technological innovations, where the risks are uncontrollable parameters This is implemented based on selection of such optimal control, which would guarantee the obtained result under the influence of any maximal risk from the set of permissible risks The proposed method enables the development of effective numerical procedures that make it possible to implement computer modeling of dynamics of the studied problem, to form program minimax control over technological innovations and to obtain an optimal guaranteed result The results reported here could be used for economic-mathematical modeling and for solving other problems on the optimization of data forecasting and control processes under conditions of insufficient information and in the existence of risks In addition, the developed modeling toolset could form the basis for development of appropriate software-hardware complexes to support making effective control decisions in the innovation activity

Analysis of statistical methods for stable combinations determination of keywords identification

Abstract: The study has solved the task of making comparative analysis and choosing an optimal statistical method to determine stable word combinations while identifying keywords to process English-language and Ukrainian-language Web-resources. The effectiveness of the method directly proportionally depends on the quality of linguistic analysis, of Ukrainian and English texts, respectively, based on the technology of Web Mining and NLP. A decomposition of methods of linguistic analysis was performed to determine the impact on the quality of forming stable word combinations as keywords. The features of the method are the adaptation of the morphological and syntactic analyses of lexical units to the peculiarities of Ukrainian-language words/texts. To determine stable word combinations effectively, it is essential to exclude functional words (stops or references), pronouns, numerals and verbs because they are not related to the subject and content of a published work. A set of stable word combinations as keywords is determined by qualitative morphological and syntactic analyses of relevant texts. The set of the identified stable word combinations is used further to compare and determine the degree of the text relevance to a specific topic or user request. The internal “dynamics” of forming a set of stable word combinations as keywords was investigated in the study depending on the statistical method applied to the texts. The obtained results have been verified. The study has produced results of the experimental testing of the proposed content-monitoring method for determining stable word combinations to identify keywords in the processing of English-language and Ukrainian-language web-resources of the technical content based on Web Mining technology. It has been determined that the authors of published works often identify the keywords that are far from being considered. It has also been proven that the quality of the result is influenced by the quality of linguistic analysis of texts and subsequent filtering. Further experimental research requires approbation of the proposed method for determining keywords for other categories of texts – scientific, humanitarian, belletristic, journalistic, etc.

Research of the treatment of depleted nickel­plating electrolytes by the ferritization method

Abstract: Considerable attention has been paid recently to the development of comprehensive recycling of industrial wastewater, which provides for an appropriate degree of purification for both organization of circulation water supply, and subsequent disposal of waste of water treatment. The improved ferritization process, which allows decreasing original concentration of nickel ions in depleted electrolytes of nickel plating from 50–100 g/dm 3 to <0.2 mg/dm 3 , was presented. The experimental ferrite-reactor with the use of the traditional thermal and electromagnetic pulse method of activation of ferritization process in the range of generating frequencies of up to 0.9 kHz was developed. Economic benefits of the use of the electromagnetic pulse activation compared to the high temperature one were identified. Kinetics of extraction of nickel and iron ions from aqueous solutions was explored. The impact of the basic technological parameters of ferritization at different ways of activation was experimentally determined. The most effective results of treatment of highly concentrated wastewater were achieved using the electromagnetic pulse (T=20 °C) and thermal (T=70 °C) way of activation of the ferritization process at the original ration of concentration Fe 2+ /Ni 2+ within 3/1–4/1, total concentration of ions of heavy metals of 20–25 g/dm 3 , original pH of the reaction mixture of 9.5 and duration of ferritization process of 15 min. Research into phase composition and physical properties of ferritization sediments was performed. Comparative analysis of sediment volumes at different ways of compaction was carried out. Sediments are mainly characterized by the crystalline structure, ferromagnetic properties, and considerable chemical resistance. This provides for actual environmental ways of recycling, which makes it possible to avoid the loss of valuable and, at the same time, toxic metal – nickel. The proposed comprehensive process of recycling liquid industrial waste prevents pollution of the environment, ensures effective and efficient use of water, raw materials, and power in the system of galvanic production.

Development of models and research into tooling for machining centers

Abstract: We have constructed three-dimensional solid models for tool storage of the disk type (for 14 instruments) and the chain type for 32 tools, mounted onto the side surface of a machine column. We propose a 3D model of the tool positioner with a hydraulic cylinder that performs an automated tool change. The generated set of models for tooling, in combination with models of tool storage and tool positioners, represents the entire complexity and special features of design and technological preparation of machining processes at machining centers of standard size III and IV. We have developed models and algorithms for parametric modeling of basic elements of profile cutting tools. Using the built-in parametrizer in the APM Graph module makes it possible to implement a simpler approach to constructing models for unified profiles of tools in order to speed up the process of creating specialized application libraries. We have built analytical models for determining the rigidity of shape-forming machine nodes. Such an approach is most effective for typical circuits of double-support spindles that are equipped with various tooling. In contrast to the generally accepted procedure, the proposed analytical models (static backlogs) provide for obtaining express estimations for the optimum correlation between design parameters of spindle nodes. Such an approach to research is defined by a tendency toward expanding technological possibilities of machining centers equipped with a constantly changing range of tooling. The emergence of new kinds of industrial tooling must be provided with methods and algorithms that interrelate the stages of constructing models of designs and assessment of their performance for the criterion of rigidity. Under conditions of machine-tool industry, the toolset proposed in this work is aimed at improving the quality of creating the three-dimensional models of structures, their photorealistic imaging, rapid adaptation to changing conditions and operative estimation of rigidity of the shape-forming nodes. Implementation of the proposed toolset is directed towards improving the competitiveness of the designed projects.

Development of the Procedure for the Estimation of Reliability of Reinforced Concrete Beams, Strengthened by Building Up the Stretched Reinforcing Bars Under Load

Abstract: We studied the stresses state of rectangular reinforced concrete beams strengthened by building up the stretched reinforcing bars under the action of load. We developed two principal methods for assessing the reliability of the strengthened beams based on various regulatory documents. According to the developed methods, we established reliability of the tested structures and obtained the results of qualitative and quantitative indicators for reliability, specifically, reliability indices and probabilities of failure-free operation. We analyzed an effect of the considered stochastic parameters of the reserve of bearing capacity of normal cross sections of strengthened beams on a general reliability estimate.The establishment of actual indicators of reliability of beams strengthened under the action of load will make it possible to approach the issue of reconstruction of elements of buildings and structures more efficiently and economically. In particular, this relates to strengthening of bending of reinforced concrete elements under operation. In addition, the obtained results of reliability study make it possible to operate with those variable parameters that have the maximum influence on variance of the limiting bending moment of beams studied with sufficient accuracy of calculation.The developed principal methods for assessing reliability make it possible to design strengthened reinforced concrete bending elements with the assigned level of reliability (efficiency of solutions) ‒ probability of failure-free operation, which may be also the subject for further research. Finally, the obtained results make it possible to approach the choice of the strengthening method more effectively.Thus, we propose a methodology adapted to the current design standards of Ukraine for assessment of reliability. It includes a relatively simple mathematical calculation apparatus. Moreover, in contrast to the results of earlier studies, the obtained values of reliability indicators are clear, since they have a distribution close to proportionality depending on a load level and a diameter of reinforcement extension. Thus, for reliability indices βi, the range of values was from 3.35 to 3.45, and for the probability of failure-free operation P(β)i ‒ from 0.999596 to 0.999720 (towards increasing the reliability level at a larger diameter of the reinforcement of extension and a load level at the moment of strengthening). The discrepancy between identical values of indices found in accordance with engineering and deformation models of calculation was about 8 % only. This fact allows the application of the developed methodology in the design practice. Therefore, taking into consideration the lack of research in the field of assessment of reliability of the reinforced concrete bending elements strengthened under the action of load, we can state that the results obtained are relevant

Substantiation of projects that account for risk in the resource-saving technological changes at enterprises

Abstract: The purpose of the study was to model the investment risk of implementation of resource-saving technological changes at enterprises and to develop a method for consideration of risk for the substantiation of projects for introducing resource-saving technologies. Risk management is an important condition for increasing the expediency of technological change activities. In turn, the correct consideration of a risk factor can increase the confidence of owners of enterprises in the expediency of introduction of resource-saving technologies, which will increase the scale of such implementation. We determined principles, an information base, and a sequence of assessment of the potential of resource-saving technological changes at enterprises. We modeled an influence of prices for production resources, for which enterprises acquire industrial resources, on the effectiveness of resource-saving technologies implementation. The simulation results showed that the level of such efficiency is quite high only in a certain range of prices for resources. In this connection, we obtained expressions for determining the price ranges for a certain type of resource, which correspond to the three main options for the application of existing technological process. Such options are: to continue operation of the existing technology; to terminate its operation with the replacement of a new resource-saving technology; to stop using the existing technology without replacing it with a new one. The study substantiates expediency of consideration of a risk factor in substantiation of projects of resource-saving technological changes at enterprises by calculation of a value of the maximum acceptable amount of investments in such an introduction. It proposes to determine the maximum acceptable amount of investments based on a constructed set of scenarios of values of those project indicators that have a low level of predictability. There is no need to substantiate a value of a discount rate, which often has a high degree of subjectivity, for this approach to a risk factor. Application of the developed method of substantiation of projects for resource-saving technological changes will increase reasonableness of relevant investment decisions due to the comprehensive consideration of a risk factor in the practice of enterprises

Ensuring comfort microclimate in the classrooms under condition of the required air exchange

Abstract: We performed comparative analysis of regulatory documents, which relate to ventilation of school premises and operate in European countries at present. We showed the essential difference of the recommended air exchange values. We assessed sanitary and hygienic conditions formed in classrooms at different efficiency of a ventilation system both by analytical calculations and by subjective monitoring of microclimate of experimental measurements conducted in school classrooms, when every pupil-participant performed an assessment of the internal environment in the form of a questionnaire. We measured carbonic acid gas contents emitted in a room and determined the required ventilation intensity in the evaluated school premises. We compared the multiplication factor of air exchange of the ventilation system determined in this way with the values obtained by analytical calculations carried out in accordance with current legislation and standards, which are active in Europe. We made calculations based on known analytical dependencies. We determined performance of the ventilation system of the classroom based on СО2 concentrations in internal and inflow air at various values of the multiplication factor of air exchange. It made possible to state that we can achieve the optimal microclimate parameters at air exchange of 30 m3/h per person.We presented the results of field studies and analytical calculations in the form of tables and visual graphic dependencies. The proposed research method makes it possible to increase accuracy and reliability of air quality control in classrooms by direct measurement of СО2 concentration in a serviced area of a room. The study results provide an opportunity to improve ventilation systems of school buildings. This creates prerequisites for obtaining a social effect due to an increase in labor and learning efficiency

Investigation of Ni­Al hydroxide with silver addition as an active substance of alkaline batteries

Abstract: Layered double hydroxides with different ratios of nickel and aluminum in the presence of Ag + ions and without silver have been synthesized: Ni: Al – 80 %: 20 %, Ni: Al: Ag – 80 %: 15 %: 5 % and 75 %: 15 %: 5 %. The obtained nickel hydroxide powders have a structure similar to α-Ni(OH) 2 with a large number of crystal lattice defects. As a result of galvanostatic charge-discharge cycling, it was revealed that the addition of silver in the chemical synthesis stage increases the hydroxide utilization coefficient at fast discharges but decrease it at slow discharges. A possible mechanism that explains the influence of added silver during synthesis on discharge characteristics of hydroxide powders was proposed. The mechanism is that silver oxide, which is a semiconductor, is mixed with hydroxide and increases the specific conductivity of the powder. Increased electrical conductivity has a positive effect on charge effectiveness, because the initial phase has lower electrical conductivity than the oxidized form – NiOOH. Because the charge involves two processes – the main process of active material charging and evolution of molecular oxygen, the electrical conductivity would play a key role in the electrode charging. At low electrical conductivity and fast charge, the current would primarily be consumed by the side process of oxygen evolution. In case of slow charges, additional electrical conductivity due to the presence of silver oxide would not have a great effect on charge effectiveness, because under such conditions the own conductivity of hydroxide is sufficient. Additionally, the presence of silver oxide would decrease the hydroxide content, which in turn would decrease the utilization coefficient that is calculated from the total mass of the powder.

Analysis of the developed quantitative method for automatic attribution of scientific and technical text content written in Ukrainian

Abstract: A formal approach was proposed to implement text content attribution. The study was conducted with Ukrainian scientific and technical texts. The results of application of the designed algorithms of automatic attribution of the text content based on the NLP and stylemetry methods were analyzed. Prospects and features of application of stylemetry information technologies for attribution of the text content were considered. Quantitative content analysis of scientific and technical text content takes advantage of content monitoring and text content analysis based on NLP, Web-Mining and stylemetry methods to identify the multitude of authors whose talking style is similar to that of the analyzed text fragment. This narrows the range of search for further use in the stylemetry methods to determine the degree of belonging of the analyzed text to a particular author. Decomposition of the attribution method was carried out based on analysis of such talking coefficients as lexical diversity, degree (measure) of syntactic complexity, talking coherence, indexes of exclusivity and concentration of the text. At the same time, author's style parameters such as the number of words in a certain text, the total number of words of this text, the number of sentences, the number of prepositions, the number of conjunctions, the number of words with occurrence frequency 1, the number of words with occurrence frequency 10 or more were analyzed. Further experimental study requires testing of the proposed method in identifying keywords of texts of other categories: scientific humanitarian, artistic, journalistic, etc.

Algorithm for the simplification of solution to discrete optimization problems

Abstract: Typically, the search for solutions in discrete optimization problems is associated with fundamental computational difficulties. The known methods of accurate or approximated solution of such problems are studied talking into consideration their belonging to so-called problems from P and NP class (algorithms for polynomial and exponential implementation of solution). Modern combinatorial methods for practical solution of discrete optimization problems are focused on the development of algorithms which allow obtaining an approximated solution with guaranteed evaluation of deviations from the optimum. Simplification algorithms are an effective technique of the search for solutions to an optimization problem. If we make a projection of a multi-dimensional process onto a two-dimensional plane, this technique will make it possible to clearly display a set of all solutions to the problem in graphical form. The method for simplification of the combinatorial solution to the discrete optimization problem was proposed in the framework of this research. It is based on performance of decomposition of a system that reflects the system of constraints of the original five-dimensional original problem on a two-dimensional plane. This method enables obtaining a simple system of graphic solutions to a complex problem of linear discrete optimization. From the practical point of view, the proposed method enables us to simplify computational complexity of optimization problems of such a class. The applied aspect of the proposed approach is the use of obtained scientific results in order to provide a possibility to improve the typical technological processes, described by systems of linear equations with existence of systems of linear constraints. This is a prerequisite for subsequent development and improvement of similar systems. In this study, the technique for decomposition of a discrete optimization system through projection of an original problem on two-dimensional coordinate planes was proposed. In this case, the original problem is transformed to a combinatorial family of subsystems, which makes it possible to obtain a system of graphic solutions to a complex problem of linear discrete optimization.

Development of the Linguometric Method for Automatic Identification of the Author of Text Content Based on Statistical Analysis of Language Diversity Coefficients

Abstract: We have developed the linguometric method for algorithmic support of content monitoring processes to solve the problem of the automatic identification of the author of the Ukrainian text content based on the technology of statistical analysis of the language diversity coefficients. The decomposition of the method for identification of the author based on the analysis of such speech factors as lexical diversity, degree (measure) of syntactic complexity, speech coherence, indexes of exclusivity and concentration of a text was performed. Such parameters of the author’s style as the number of words in the specified text, the total number of words in this text, the number of sentences, the number of prepositions, the number of conjunctions, the number of words with the frequency of 1, the number of words with the frequency of 10 and more were analyzed. The features of the developed methods are the adaptation of the morphological and syntactic analysis of lexical units to the peculiarities of the structures of Ukrainian words/texts. That is, when analyzing linguistic units of the word type, their belonging to a part of speech and declension within this part of speech was taken into account. For this, the flections of these words for their classification, separation of the base for the formation of the corresponding alphabetic-frequency dictionaries were analyzed. Filling these dictionaries was subsequently taken into consideration at the following stages of the identification of the authorship of a text, such as the calculation of parameters and coefficients of the author's speech. Syntactic words (stop or anchor) words are most essential for an individual style of an author, as they are not related to the subject and content of the publication. We compared the results in a set of 200 one-author papers in the technical area of more than 100 different authors over the period of 2001–2017 to determine if and how the coefficients of diversity of a text of these authors change within different periods of time. It was found that for the selected experimental base of more than 200 papers, the best results according to the density criterion are reached by the method for analysis of an article without the initial compulsory information, such as abstracts and keywords in different languages, as well as the list of literature.

Designing the flow-through parts of distribution systems for the PRG series planetary hydraulic motors

Abstract: Improved efficiency of using the self-propelled machines is defined by the existence of hydraulic machines for the actuators of active working elements and running systems. Hydraulic drives of self-propelled machines exploit planetary hydraulic motors. The advantage of these hydraulic motors is a possibility to install them directly to the actuators of drilling machines, conveyors, winches, motor-wheels, etc. The basic node, limiting the work of a planetary hydraulic motor, is the distribution system. A distribution system creates a rotating hydraulic field that enables the working cycle of a planetary hydraulic motor. Therefore, improvement of the structural parameters of the distribution system is an important field of research aimed at improving the output characteristics of the planetary hydraulic motor. We have developed a design diagram and proposed a mathematical apparatus which make it possible to explore the influence of structural parameters of the distribution system on the output characteristics of the planetary hydraulic motor. The study we conducted has established that the synchronicity of a hydraulic field rotation depends on the number of working chambers and is characterized by a kinematic diagram of the distribution system. Dependence of change in the total area of the flow section in the distribution systems for different kinematic circuits is cyclical in character with a fluctuation amplitude dependent on the kinematic diagram. We have substantiated rational kinematic diagram of the distribution systems. We identified a zone where hydraulic losses are formed. The losses are caused by local resistances, when the working fluid passes along the distributing windows of the sleeve valve and the distributor. We have developed an algorithm for designing the flow-through parts. It enables the application of rational kinematic diagrams of the distribution system in order to improve the output characteristics of the planetary hydraulic motor.

A study of the effect of tungstate ions on the electrochromic properties of Ni(OH)2 films

Abstract: Thin films of nickel hydroxide were prepared using the cathodic template method and were tested in different electrolytes. The electrolytes were 0.1 M KOH and 0.1 M KOH with the addition of 0.1, 0.3 and 1 mM K2WO4. The test revealed, that the presence of tungstate can have a significant effect on electrochemical and electrochromic characteristics of Ni(OH)2 films. The initial sample, cycled in 0.1 M KOH showed different characteristics from those cycled in tungstate-containing electrolytes: significant difference between current densities of cathodic and anodic peaks and presence of the current plateau on the cyclic voltamperometry curve. However, the initial sample demonstrated the highest coloration degree of 74 %. On the other hand, the sample showed degradation of the coloration degree past initial growth.The samples cycled in the tungstate-containing electrolyte showed better electrochemical characteristics – sharper cathodic and anodic peaks, with the lesser difference between peak values. The dynamics of the absolute coloration degree of the samples cycled in tungstate-containing electrolyte showed a constant increase. The sample tested in a solution with 1 mM tungstate had the lowest value of the absolute coloration degree – 60 %. For tungstate concentrations of 0.1 and 0.3 mM, the absolution coloration degree at the last cycle was 72 and 71 % respectively.The samples tested in a solution with tungstate additive had a significantly lower bleaching time – 40–50 s in comparison to 360 s of the sample cycled in 0.1 М KOH.A possible mechanism that explains such differences in behavior was proposed

Two­stage treatment of solid waste leachates in aerated lagoons and at municipal wastewater treatment plants

Abstract: The two-stage technology of treatment of the leachates of the municipal solid waste (MSW) dumps in aerated lagoons and at municipal wastewater treatment plants (WWTP) has been studied. The study objective was to develop a technology that can be implemented at existing MSW dumps and landfills. Static and dynamic modes of implementation of both stages of the technology were investigated on the model units. Static 16-day mode was experimentally studied in the aerated lagoon conditions. As a result, we have managed to achieve almost a 2-fold reduction of COD and more than a 3-fold decrease in concentration of ammonium ions. Dynamic mode studies have established that the optimal time of leachate staying in the reactor was 10 days. Change of the relative concentration of ammonium nitrogen in the leachate largely depends on the process temperature, so in real conditions, it is necessary to adjust the modes of realization of the individual stages depending on the ambient temperature. It has been established that for treatment of leachate at municipal WWTP in a static mode at the value of the ratio of leachate dilution with municipal sewage of 1:1000, the maximum effect of treatment of both from ammonium ions and COD was achieved. The study of leachate treatment at municipal WWTP in a dynamic mode has confirmed stability of maintaining the treatment indicators in time. By implementation of the two-stage technology of leachate treatment, it will be possible to minimize environmental hazard from surface and ground water contamination in the zone of influence of MSW dumps and landfills

Comparative investigation of electrochemically synthesized (α+β) layered nickel hydroxide with mixture of α-Ni(OH)2 and β-Ni(OH)2

Abstract: Nickel hydroxides, owing to their high electrochemical activity are promising materials for chemical power sources (alkaline accumulators, lithium accumulators and hybrid supercapacitors), electrochromic devices, electrochemical oxidation of organic compounds. The most promising is nickel hydroxide that contains both α-Ni(OH) 2 and β-Ni(OH) 2 . The aim of the research was to determine the properties of model mechanical mixtures with different ratios between α-Ni(OH) 2 and β-Ni(OH) 2 and to prove the hypothesis about the layered structure of nickel hydroxide samples synthesized in the slit diaphragm electrolyzer by means of comparative study. The XRD patterns of samples composed of α-Ni(OH) 2 and β-Ni(OH) 2 mixture show peaks corresponding to separate phases. By means of cyclic voltamperometry, it was discovered , that mixture samples do not show an oxidation peak during the first cycle, while two reduction peaks that correspond to reduction of α and β components are observed on the cathodic curve. A synergetic effect, which results in significant improvement in electrochemical activity of α-Ni(OH) 2 and β-Ni(OH) 2 mixture was discovered – specific reduction peak current values are 2.3 A/g (20 % α-phase), 3.5 A/g (30 % α-phase), 6.9 A/g (50 % α-phase), which exceed those of initial β-Ni(OH) 2 (1.5 A/g) and α-Ni(OH) 2 (2.0 A/g). By means of XRD analysis, it was discovered , that Ni(OH) 2 samples synthesized in the SDE are composed of α and β and a series of intermediate structures. These samples demonstrate high electrochemical activity: presence of a defined oxidation peak during the first cycle, single reduction peaks with high specific currents of 6.5–11.7 A/g. The comparative analysis has revealed that electrochemically synthesized samples are composed of α-Ni(OH) 2 and β-Ni(OH) 2 , but are not a mixture of these phases, owing to significantly different electrochemical behavior from mixture samples. Using mechanical modeling, the layered (α+β) structure of samples electrochemically synthesized in the slit diaphragm electrolyzer has been proved by contradiction.

Development of the universal model of mechatronic system with a hydraulic drive

Abstract: The growing demands to performance of mechatronic systems with a hydraulic drive of movable operating elements of self-propelled machines require application of new approaches to the process of their development and design. Functional parameters of the mechatronic systems depend on a rational choice of operating modes of the hydraulic system and the design implementation of the mechatronic modules of these systems. Quality of the mechanically driven mechatronic system is largely determined by its dynamic characteristics. In order to improve dynamic characteristics, a universal model describing dynamic and static processes occurring in the elements of the mechatronic system was proposed. The pump, the hydraulic motor, the safety valve and the working fluid are considered interrelated as a single whole. The universal model takes into account peculiarities of functioning and mutual influence of all elements of the mechatronic system as well as the features of the working fluid and can be used with any hydraulic machines of a volumetric action. The study of dynamics of the changes in functional parameters of the mechanically driven mechatronic system was carried out for four stages of its operation: acceleration of the hydraulic drive (triggering of the safety valve); valve closure; completion of acceleration and steady-state operation. The conducted studies have established that when activating the hydraulic drive of the mechatronic system from the moment of the safety valve activation and to its closure, operating conditions do not affect changes in the functional parameters. In the steady-state operation, there are fluctuations caused by unevenness of the pump feed and load fluctuations. It should also be noted that the mechatronic system with a hydraulic motor having larger working volume has better dynamic characteristics than that with smaller working volume.

Development of a method to determine deformations in the manufacture of a vehicle wheel rim

Abstract: The desire to anticipate and predict quality of the manufactured products, its compliance with the technical requirements of the customer at the stage of technology design leads to the development of various methods for theoretical analysis of the processes of plastic deformation. The purpose of these methods is to establish explicit patterns in the processes implemented using the intuitively clear mathematical functions. We have formulated a method for determining relative deformations at a local change in the shape of a closed shell of rotation through radial-rotational profiling. It is shown that it is possible, based on the derived analytical dependences, to predict dimensions of a semi-finished product at the design stage of the technological process. Up to now, there have not been any analytical expressions that would estimate an unambiguous dependence of deformation on the rollers radii ratio, on a billet, and on the magnitude of feed. It is established that the magnitude of relative deformations in three mutually perpendicular directions depends on the ratio of diametrical dimensions of deforming rollers and initial diameter of a billet. Comparison of calculation results, obtained in this work, with experimental data and existing expressions allows us to argue that a given method of calculation demonstrates the accuracy acceptable for the industrial production. This contributes to the possibility to control a field of stresses and deformations in order to manufacture an equally strong wheel rim at the stage of production preparation and a technological process design. The practical application of a given method of calculation would enable technologists and designers to take into consideration the deformation strengthening after each run of profiling. As well as to determine the operational dimensions of semi-finished products and to predict thickness of a finished product in radius transitions of the profile, that is, to intensify the considered process.

Activation of the nickel foam as a current collector for application in supercapacitors

Abstract: Nickel foam is widely used as a current collector and as a major component of the faradic electrode in supercapacitors. Activation of nickel foam would allow increasing the capacity of the nickel hydroxide electrode or preparing high-speed electrodes without additional active material. Multiple (1 – 20 times) short-term (5 min) treatment in a 1 М solution of HCl, H3BO3 or H2C2O4 has been proposed. The possibilities of activation of commercial nickel foam samples manufactured by “Novoment-Perm” (Russian Federation) and “Linyi Gelon LIB Co Ltd” (China) have been studied. Activated and non-activated nickel foam samples have been studied by means of X-ray diffraction analysis and scanning electron microscopy, electrochemical characteristics were determined by means of cyclic voltamperometry and galvanostatic charge-discharge cycling in the supercapacitor regime. The comparative analysis of nickel foam samples from Chinese and Russain manufacturers has revealed very low reactivity and low susceptibility to activation of nickel foam from Chinese manufacturer. An assumption has been made that low reactivity is because the sample is composed of Ni-P or Ni-B alloy. The maximum specific capacity of 0.084 F/cm2 has been obtained after 20 treatments in HCl solutions. The activation mechanism is the increase in the specific surface area of nickel. However, this value is significantly lower than that of non-activated nickel foam from Russian manufacturer (0.333 F/cm2). It has been discovered that the nickel foam sample from Russian manufacturer can be easily activated. The maximum activation effect is achieved when treated with oxalic acid: specific capacities are 1.213 F/cm2 (one treatment), 6.578 F/cm2 (five treatments) and 20.003 F/cm2 (twenty treatments). The activation mechanism is the formation of nickel oxalate on the surface of nickel foam. The results of the comparative analysis have revealed the effectiveness of activation of the nickel foam sample from Russian manufacturer by multiple short-term treatment with oxalic acid. It has been concluded that activation of the nickel foam sample from Chinese manufacturer by multiple short-term treatment in solutions of hydrochloric, boric and oxalic acids is ineffective. Activation of nickel foam from Chinese manufacturer requires the development of a different method.