Analysis of the influence of types of spatial structures of public gardens of the Orel city on the architectural and ecological sustainability of urbanized landscapes

Introduction. A public garden or park improvement project should arise from a scientifically grounded study of the territory and proceed from the further development of this object. The aim of the study is to analyze the territory of public gardens in the city of Orel to determine the influence of types of spatial structures on the features of the functioning of a landscape object, to predict the stability of the studied landscape and to assess the dynamics of urban ecosystems based on the state of tree vegetation. Tasks: to analyze the placement and ratio of types of spatial structures on the objects under study; to make an aesthetic and sanitary-hygienic assessment of the landscape; to monitor the state of woody vegetation at the facilities. Materials and methods. For the development of scientifically based design of sustainable urban ecosystems and the reconstruction of urban objects of landscape architecture, a method is proposed for studying the territory of squares along the selected contours of types of spatial structures (TPS), which allows us to identify positive and negative factors affecting the development of design solutions. When analyzing the TPS of the investigated squares, satellite images of objects were used. Results. As studies of the type of spatial structure have shown, in most of the investigated squares, indoor TPS prevails; on average, this type of spatial structure is established on 41.8 % of the square of squares. The location of open and semi-open TPS is haphazard and random. The lowest aesthetic score was established for the closed TPS-21.9 points, which is due to the difficulty of identifying species points in such spaces, poor visibility, inhibition of the growth of not only trees, but also the ground vegetation cover, which in most cases is represented by a sparse grass stand with poor species diversity. When conducting a sanitary and hygienic assessment of various TPSs, it was found that a closed TPS also corresponds to the worst grade (2.5 class), which is associated with a decrease in the suitability for performing sanitary and hygienic functions in weakened and damaged plants. Conclusions. For the majority of public gardens in the city of Orel with a plant age close to the maximum in urban conditions, a closed type of spatial structure is characteristic. The closed type of spatial structure led to a decrease not only in attractiveness, but also in the performed sanitary and hygienic role of landscape architecture objects.

Mathematical simulation in the system of safety monitoring of hydraulic structures and automated control systems of stress-strain state

Introduction. The article describes the features of the systems for monitoring the safety of hydraulic structures, which are based on the apparatus of mathematical and computer modeling. Prospects for the use of automated control systems for the stress-strain state of building structures of hydraulic structures are considered. Materials and methods. An analytical review of foreign examples of the implementation of monitoring systems for high-pressure hydraulic structures based on mathematical models is presented. The results of computational studies of the Zagorsk PSPP complex within the framework of the hardware and software complex for safety monitoring are shown. The concept of automated stress-strain state control systems is described. Results. The advantages and limitations of widely used, domestic and foreign automated information and diagnostic systems are outlined. On specific examples of the integration of numerical models of hydraulic structures into integrated systems for monitoring the safety of hydraulic structures, methods of expanding the capabilities of monitoring systems in terms of analyzing the stress-strain state of structures and predictive estimates are demonstrated. Insufficient elaboration of the issues of management of the stress-strain state of structures is noted, but the need to develop special structural elements with variable parameters to influence the stress-strain state of hydraulic structures is substantiated. Conclusions. The data presented in the article confirm the need to develop systems for monitoring the safety of hydraulic structures based on complex, multiphysics mathematical models, which can significantly expand the functionality of monito­ring systems and, as a result, improve the safety of hydraulic structures. The analysis of world experience indicates the growing lag of the Russian hydropower industry in terms of the integration of mathematical models into the safety monitoring systems for hydraulic structures, which obviously requires additional research and practical work in this area.

Reducing energy capacity and increasing the environmental safety of industrial areas when using radiative heating systems based on water infrared radiators

Introduction. It has been repeatedly proven that the use of radiant heating systems leads to an increase in the environmental safety of industrial premises by increasing their energy efficiency. The most promising solution is the use of gas infrared emitters, in which there is no intermediate coolant, and the heat of combustion of the gas enters the room. However, such a solution has a number of limitations on gas availability, comfort and fire hazard. Also, a highly efficient solution is the use of water infrared emitters, which can be represented by emitting panels or emitting profiles that use an intermediate coolant, but do not have many limitations inherent in gas systems. Materials and methods. This study was conducted in the Laboratory of radiant Heating of NNGASU and is devoted to the study of the peculiarities of the formation of the temperature regime in rooms heated by water infrared radiators, as well as the thermal regime of external enclosing structures in these rooms. Results. Based on the results of the experiments, the authors concluded about the formed thermal regime in rooms with heating systems based on water infrared emitters. It is proved that the use of radiant heating leads to a more uniform temperature regime in a heated room, and less overheating of the room covering than when using convective heating systems. Conclusions. The energy efficiency of the use of radiant heating systems based on water infrared emitters has been proven. The study showed that the system of water radiant heating allows to reduce the gradient of air temperature in height not only in large-volume rooms, such as workshops, depots, gyms, but also in rooms with a low height of the coating location. This feature allows you to reduce heat losses through the coating. The temperature regime in the working area of the room with the use of radiant water heating, in comparison with convective, remains unchanged.

Improving the analysis of technical risk factors using the integrated FLDS model on the example of the construction of multi-storey residential buildings

Introduction. This study is aimed at developing a model of the life cycle of a multi-storey residential building, taking into account the factors of technical risks. This model makes it possible to identify the main factors of technical risks at different stages of a project’s life and predict its behavior. After examining an extensive list of both domestic and foreign literature, it is clear that the systematization and classification of the elements of the life cycle of a construction object in conditions of technical risk factors is an urgent task in the construction industry. The purpose of the study is to develop the most effective mathematical model for determining and predicting the influence of technical risk factors on the life cycle of a multi-storey residential building. Materials and methods. The study is based not only on an extensive review of scientific literature, whose attention is focused on technical risks, but also analyzed the stages of the life cycle of buildings and structures, used the method of analogies and the method of diagrams, based on the theory of fuzzy set and the Dempster-Schafer theory, a mathematical model of FLDS is formed, so an expert survey was conducted with leading experts in the construction industry, on the basis of which the selection of the main factors of technical risks is formed. Results. The problem of analyzing technical risks in the construction industry plays a significant role, this is due to the construction of a significant number of modern structures that are unique in their kind, both from an architectural point of view, and from the point of view of the originality of design and technological solutions. Conclusions. Due to the uncertainty of experts’ opinions regarding the likelihood of occurrence and the degree of impact of risk factors, a demonstrative mathematical model of FLDS based on two theories is proposed, which allows numerically determining and distributing the influence of a risk factor by ranks. The result of the study shows that the application of the FLDS mathematical model will significantly increase the success of the project, allowing you to see the critical factors of technical risks at the initial stage of the life cycle of a construction project.

Impact of the fire on the bearing capacity of the ordinary concrete used in reinforced concrete structures in Burundi. History and architecture

Introduction. This paper presents the results of an assessment of the impact of fire on the bearing capacity of the ordinary concrete, to be taken into account in the rehabilitation of fire-damaged reinforced concrete structures in Burundi. Materials and methods. Experimental samples of the ordinary concrete made respectively of coarse river aggregates and crushed coarse quarry aggregates were prepared and subjected to different heating temperatures (250, 350, 450, 600 and 900 °C) simulating the fire. After natural cooling, experimental samples were subjected to compression test; and diagrams showing the loss of the load-bearing capacity of the ordinary concrete used in reinforced concrete structures in Burundi were drawn. Results. Negative impact of the fire on the load-bearing capacity of the ordinary concrete occurs above of 350 °C of heating temperature. Concrete made of crushed coarse quarry aggregates loses 50 and 78 % of its bearing capacity at around 525 and 900 °C of heating temperature, respectively. Similarly, concrete made of coarse river aggregates loses 50 and 70 % of its load-bearing capacity respectively at 600 and 900 °C of heating temperature. An evaluation curve of the after-fire bea­ring capacity of the concrete used in reinforced concrete structures in Burundi is established. Conclusions. The negative impact of the fire on the load-bearing capacity of the ordinary concrete occurs above of 350 °C of heating temperature. Concretes made of crushed coarse quarry aggregates and concrete made of coarse river aggregates lose 50 % of its bearing capacity at around 525 and 600 °C of heating temperature respectively. Knowing the heating temperature that the fire-damaged reinforced concrete structure has undergone is indispensable in deciding on its demolition or rehabilitation.

Using the criterion of resistibility to assess of a structural limit state

Introduction. Subject of research: behaviour characteristics of an arbitrary structure under the loads that approach the limit load value. Goals: development of an objective and sufficiently universal methodology for the identification of the bearing capacity of a structure, which could allow to stop using any subjective assessments of their limit bearing capacity. Materials and methods. Behaviour characteristics are assessed by analyzing a curve of equilibrium states. The curve is constructed using the characteristic displacement, understood as the generalized displacement q, which energetically matches applied generalized force λ in the sense that the product of λdq is the growth of work performed by generalized force λ in respect of the growth of displacement dq. Results. The article shows that the system’s response, no matter what fixed conditions it is in, is not always sufficient for the assessment of the reliability of the system in case of the variable interaction with the environment. The co-authors use the V.V. Katyushin concept about supplementing the notion of the limit state with the characteristics of the system’s beha­viour determined by the velocity of a change in the system’s response caused by the change in the external action. According to the co-authors’ suggestion, the meter should represent the reduction in the slope of the curve of equilibrium states, which characterizes the loss of resistibility and, consequently, it can be used to assess the closeness of the structure to the state of failure, which arises if the resistibility of the system is equal to zero. The suggestion is to use the value of the slope of the curve of equilibrium states as the limit state, when the resistibility has reduced, and the velocity of deformation intensification has gone up 100 times if compared with the behaviour of an unloaded system. This suggestion is illustrated by the case of the analysis of a reinforced concrete diaphragm of a building. Conclusions. The proposed calculation methodology can be applied in the design of loadbearing structural elements, whose finite-element computational model has components that are different from the rod ones.

Saint Nicholas Church in the pomor settlement of Maloshuyka — the oldest tent roof temple of the octagon-on-quadrangle type. History and architecture

Introduction. The Saint Nicholas Church in Maloshuyka, dated 1638, is notable for being one of the earliest known examples of a widely spread type of wooden temple. Despite its historical and cultural significance, this object remains largely unstudied. To better understand the development of Russian wooden church construction and set up a typology, it is necessary to consider the Saint Nicholas Church in the context of all-Russian church building traditions of the 17th century. A monument of such significance needs to have its own place in the history of Russian wooden architecture. Materials and methods. The study was based on historical archival documents and on-site survey results. We considered the monument together with the history of the settlement and the entire region. A joint historical and architectural approach was used to study the object. The object was compared with its equivalents via comparative typological analysis. In order to identify individual and typical features in the Saint Nicholas Church architecture, typologically similar objects were reviewed chronologically and geographically. Results. New historical sources were introduced into the scientific discourse. Construction history and periodization of the Saint Nicholas Church were identified. We determined changes in appearance at each construction stages, and described architectural, artistic and stylistic descriptions of the object at each construction stage. The object was compared with similar objects, and characteristic features of this type of church at the early stages of its evolution were identified. They were expressed in general dimensions, proportions, and decorative finish. Regional typical features and all-Russian features were singled out. The place of the object in the Russian history of wooden architecture was defined. Conclusions. The Saint Nicholas Church is a unique monument of Russian wooden architecture. Being the oldest tent roof wooden temple of octagon-on-quadrangle type, this object reflects the earliest development stages of this architectural type. The Saint Nicholas Church has certain local architectural features, but it generally conforms to the all-Russian architectural traditions of the 17h century.

Phenol removal by enhanced electrocoagulation process with persulfate salt

Introduction. Phenol is classified as priority pollutant. Phenol and its derivatives are stable in water, environmental contamination, and health concerns that are used as raw material in many chemical industries. This study investigated the removal of phenol by the reactivity of free sulfate radicals (SO4•–), activated by electrochemically generated Fe2+/Fe3+ ions which furthermore are evaluated to destroy phenol in aqueous solution. Materials and methods. In the present experimental study, electrocoagulation reactor by iron electrodes is used in the pre­sence of persulfate ions to phenol removing from aqueous solutions. In this regard, the effect of four independent variables including pH, electric current, persulfate dosage, and initial phenol concentration were studied on phenol removal. Results. The study determined the optimum conditions for maximum phenol removal using electro-persulfate process (EPS) as pH 3, 7.4 mM persulfate dosage, 27.78 mA/cm2 current density, and 100 mg/L initial phenol concentration at 30-min reaction time. The results showed that the efficiency of phenol removal was directly related to the initial persulfate dosage. In addition, the pH values, less than the phenol pKa, has slight effect onto the phenol removal. However, it was inversely correlated with a highly alkaline pH and higher phenol concentration. Conclusions. The study concluded that electro-persulfate process is an effective and robust process that can be used for handling of phenol containing wastewater.

Features of using cement suspension in concrete mixture recycling technology

Introduction. Recycling technologies may solve the problem of landfill waste. The problem of hydraulic active cement waste using not fully resolved in concrete mixtures recycling technologies. Using hydraulic active cement waste as an addition directly influences the technological and mechanical characteristics of new concrete mixtures. That requires additional research. Materials and methods. The cement waste obtained after recycling was simulated by pre-hydrated cement suspension produce at V/C equal to 0.7 for 6 hours of hydration. Different compositions of cement mixtures were investigated. The difference of which was amount of introduced pre-hydrated cement additive, both in the presence and without plasticizer. Technological properties, namely the normal consistency and setting time of cement compositions were investigated by standard methods of GOST 30744-2001. Mechanical properties, namely the compressive strength at the age of 28 days, were determined by destructive method on a hydraulic press PSU-10. Results. The introduction of a pre-hydrated suspension causes an increase in normal consistency, a reduction in the setting time and a decrease in strength with an increase in its quantity. The use of such a suspension in conjunction with a superplasticizer can level out the increase in normal density, as well as increase the strength of the samples. Timing of setting remained similar to the results of the test without the plasticizer. Conclusions. The results of the study show influences of cement waste obtained after recycling on the technological and mechanical characteristics of new mixtures. These influences are important and must be taken into account in the design of new concretes and mortars.

Using interpolation and correlation to evaluate the quality of cement composites exposed to a thermally aggressive environment

Introduction. The article addresses the quality evaluation of cement composites after their exposure to the atmospheric environment that features a rapid change in positive and negative temperatures. The article has a numerical assessment of the quality of cement composites. The quality assessment method encompasses the Spearman’s rank correlation, the coefficient of determination, and the adjustment ratio. Materials and methods. Testable cement composites are the compositions numbered from one to eight. They differ in the concentration of various additives, including superplasticizers and aggregates. Testable compositions were exposed to cyclic changes in positive and negative temperatures, and four of their properties were checked in the points of control on Day 0, Day 15, and Day 45. Linear interpolation was used to expand the data array. Changes in the properties of composites were compared with the benchmark values; the Spearman’s rank correlation and the coefficient of determination were calculated. Moreover, arrays of interpolated values were reduced to relative units to calculate the adjustment ratios. Entry values were employed to develop the evaluation metrics and assess the quality of cement composites. Results. The proposed numerical metrics is used to rank the testable samples and identify the best compositions. Library functions and transformations, available in the MATLAB system, are applied to each action, which can be implemented in nearly any software programming language. Conclusions. The proposed method of heuristic quality evaluation of cement composites may be applied to the cases when testable samples are exposed to versatile adverse and aggressive operating conditions.