Vol 11, No 2 (2021)

Corrugated steel beams represent a promising area of research in the fi eld of structural engineering today. The article studies the behavior of a metal beam with a corrugated wall of an I-profi le under bending conditions. Beam considered span of 12 m. A fi nite element model of the calculated structure was built in the LIRA-SAPR software package. The analysis of the stress-strain state of a corrugated beam of variable stiff ness, which has a fl at fragment in the central part of the wall, is carried out. The beam thus obtained has a number of advantages over beams with only a fl at or fully corrugated wall. The conclusions based on the results of the analysis of the calculation are presented.

A numerical study of heat transfer and friction in the heat exchanger channels in the presence of a variable pressure gradient is performed. The research was carried out in software complexes (Code_Saturne, Salome). The results of the validation of the research method are presented and they showed that the deviation of the numerical simulation results from the calculation data according to the known criterion equations is within the error of generalization of the experimental data by the criterion equations. According to the results of studies at Red=3000, Red=4177, Red=6000, it was found that the average value of the heat transfer coeffi cient of the channel of variable cross-section is up to 20 % higher than for the channel at dp/dx<0 and 16 % higher than for dp/dx>0. At the same time, the thermal-hydraulic effi ciency of the alternating channel (L=117 mm, l=58.5 mm, n=2) in the initial section at x =0...0.08 is lower than in the channel with dp/dx>0 by 26.7 %, and at x =0.08...1 it is higher by 5 ... 15 %, at dp/dx<0 the thermal-hydraulic effi ciency of the alternating channel is higher by up to 77 %.

A distinctive feature of waste water of fi sh processing enterprises is the high content of organic substances: COD - 620-3500 mg/L, BOD-220-2860 mg/L. The ratio of BOD:COD=0.68-0.83 in the waste water of fi sh processing enterprises shows a high potential for the use of biological treatment methods. Further study requires the removal of biogenic elements, because, for example, for a fi sh cannery, the ratio of BOD:N:P=100:3.79:1.08 and 100:4.77:0.57. This article presents the experience of design, construction, start-up and adjustment of sewage treatment facilities of a fi sh processing enterprise. For wastewater treatment, the following scheme was developed and manufactured by the ECOLOS company: a receiving well with a basket, a drum grate, a horizontal grease trap, an homogenizer, a reagent pressure fl otation unit, a membrane bioreactor, and ultraviolet disinfection. The quality of waste water at the outlet of the treatment facilities meets the requirements of the Normative- permissible discharge provided by LLC «Russkaya Treska».

The article compares the removal of phosphates from wastewater by promising biological methods, namely biotechnologies based on the use of phosphate-accumulating organisms. The microbial community under study gives great hopes for further fundamental studies of the metabolism of phosphate-accumulating organisms, and for improving biotechnologies for purifying wastewater from phosphorus.

The study of the nature of high-temperature corrosion of metals is one of the tasks in substantiating the relevance of the use of corrosion-resistant, heat-resistant coatings and barrier layers obtained on the basis of the natural oxidation process. The article presents the gradation of oxidation of surfaces of 08kp thin-sheet steel at diff erent temperature-time parameters of one cycle “heating-cooling”. To regulate the processing modes and register thermal eff ects, a diff erential thermal analysis device was used. It is shown that the eff ect of elevated temperatures on steel in air at atmospheric pressure triggers an intensive growth of scale, which peels off from the metal base and breaks down. After descaling on the steel surface, in addition to blue tarnishing, in some cases, fi lms of a red tint were found. Based on the data of diff erential thermal analysis, an att empt was made to separate and interpret transformations related directly to steel and to reactions in scale associated with iron oxides.

The experience of operation of surface emergency gates in ice-breaking conditions at a number of hydroelectric power plants has shown the insuffi cient eff ectiveness of the methods used to combat freezing of structures. The rules for technical operation of spillway dam gates in winter provide for heating of structures by slots, threshold and skin in conjunction with measures to maintain mines before construction. However, measures to heat gates and build mines are not always suffi ciently justifi ed and justifi ed. In order to obtain full-scale data and scientifi c information for the development of recommendations on operating and accounting modes during design, full-scale studies of stresses and defl ections in the load-bearing elements of the watershed gate of the hydroelectric power station were carried out. This article presents the results of fi eld studies in comparison with calculated values. As a result of the studies, information on the static operation of fl at gates in winter conditions is obtained, which is of theoretical and practical interest. The materials can be used to clarify technical operation rules and to clarify regulatory documents for the design of hydromechanical equipment at hydroelectric power stations.

The principles of determining the conditions of tightness of the construction site in accordance with the requirements of normative documentation are shown. On concrete examples the features of defi nition of types of cranes, conditions of their placement on a construction site are considered. Shows examples of the placement of diff erent valves within a single construction site. The possibilities of limiting the boundaries of the zones of operation of the crane are determined. Possibilities of restriction of a dangerous zone of action of the crane according to the standard literature are presented.

Nowadays the area of cities is almost everywhere increasing - the territory urbanization is developing. At the same time, due to lack of land resources, the underground space development intensifi es, and the underground construction volume increases, i.e., underground urbanization takes place. This process has undoubtedly positive results, as it can help solve territorial, transport, environmental and other problems of cities while preserving the unique appearance of buildings in the historical centers of cities. At the same time, some engineering and geological processes may be activated as a negative underground urbanization result. The article deals with underground urbanization history in Samara and defi nes its main stages. More than one million people live in Samara city, subway line was built, there are subway objects of industrial and defense importance (bunkers) reaching considerable depth. Active underground construction can lead to geological processes strengthening (weathering, karst formation, suff osia, etc.), change of strength properties of rocks, violation of natural hydrological regime of the territory. The territory of Samara has an inhomogeneous geological structure and complex engineering and geological construction conditions. Seven engineering-geological districts have been identifi ed and studied, on the territory where underground construction development can lead to diff erent, including negative, consequences.

The purpose of the article is a comprehensive study of the urban forest park located within the boundaries of the Sluzovaya microdistrict, Komsomolsky district of Togliatt i, with a subsequent project proposal for its improvement. The historical analysis of the general plans and natural characteristics of the forest park is designed to rethink a particularly valuable territory for its preservation and development in the future. The task is to evaluate and compare the implemented objects of the adjacent historical development, in order to use the identifi ed language of forms in the new improvement proposal.

Cities are complex systems consisting of capital objects (architectural objects, transport system and other infrastructural systems), state and non-state institutions, social and economic processes, people (in their various aspects and types of activities), also natural components (topography, hydrography, climate). The article discusses issues related to these specifi c aspects and the relationship between the elements of the architectural and planning structure of the city as a space and a system. Within the framework of the study, a morphological analysis of planning and development was carried out using the example of Samara in the context of sustainable development in order to identify and systematize universal urban elements.

The article (part II) contains the results of studying the features of adaptation of the living environment of the population of the largest city to the vital challenges of the pandemic of the new coronavirus infection COVID-19. The verifi cation of the working hypothesis and the detailing of the main provisions formulated in the fi rst part of the article (see “Urban planning and architecture”. 2021, no. 1) were carried out on the example of an ordinary St. Petersburg locus, actively developed by the townspeople who observed the regimes of self-isolation, partial lifting of strict restrictions and minimal restrictions (2020), which is located within the boundaries of the former sett lement of the Life Guards Semyonovsky regiment, which gave the name to the historical district of the city “Sementsy” and the municipal district “Semyonovsky” (Admiralteisky district of St. Petersburg). In the course of the study, a relationship was established between the immanent properties and parameters of the transformed urban sett lement (territorial- urban-planning, situational-genesis, compositional planning, architectural-spatial, social-functional) and its “anti-epidemiological” potential, realized by the local population and the authorities in the conditions of “pandemic reality” by methods of social self-regulation and centralized management.

The article is devoted to the reality of the modern historical city in the totality of the actual values of the valuable heritage, traces of the past, mental codes, archetypal images and the memory of civilization. The place of history in today’s socio-cultural fi eld and in the professional context is not clearly defi ned. Together with the understanding of the need to preserve the heritage, traces and memory of the past, there are global trends that mediate the features of the glocal in architecture. However, even this compromise cannot fully demonstrate the complexity of the historical city viability. According to the author, it is necessary to search for reasons that sometimes appear outside the material reality, but address directly to the spiritual world and mental space of a person, which is the main purpose of the article. The emphasis is placed on the artistic dimension of environmental realities, which allows us to determine the living connections of history and modernity on the basis of the author’s concept of artc integration. The article is illustrated by some results of cooperation between the Nizhny Novgorod State University of Architecture and Civil Engineering and the Polytechnic University of Milan (Politecnico di Milano) in the fi eld of reconstruction and renovation of historically valuable territories and author’s photographs.

The article discusses the problem of increasing the effi ciency of the linear section of the main gas pipeline system by developing eff ective control algorithms for the operating modes of the gas cooling unit. To develop control algorithms for a gas cooling unit, adapted mathematical models of thermal processes in air-cooled gas devices and in a gas pipeline are used. It is shown that when considering the dynamic modes, the gas pipeline system can be represented as consisting of two dynamic links. The link “gas cooling unit”, which includes up to 24 electric drives with heat exchangers, is characterized by relatively short time constants. In the main gas pipeline, heat exchange processes proceed much more slowly. This circumstance allows the main att ention to be focused on the development of an eff ective control system for the cooling plant. The control is carried out by discrete or continuous change in the fl ow rate of the cooling air through the heat exchanger by adjusting the number of switched on air coolers and changing the fan speed. The search for control algorithms for air coolers is carried out by formulating and solving the problem of minimizing the root-mean-square deviation of the gas temperature at the outlet from the heat exchanger from the required value. To implement the obtained control algorithms, a functional diagram of the automatic control system for the operating modes of the gas cooling unit has been developed.

Non-contact seals with fl at slott ed gaps of drives of electric power systems used in switchgears of hydraulic units, as well as in pumps and hydraulic motors have been investigated. Calculation of seals based on average clearance results in an underestimation or overestimation of the leakage rate compared to the operational values. The regularity of the distribution of pressure and fl ow rate in the gap of a fl at conical slot is determined, and formulas for the fl ow rate (leakage) and friction forces acting on the walls of the conical slot are found. To solve the problem, the approximate Navier-Stokes and fl ow continuity equations are used. Several special cases of the fl ow of the working fl uid in diff erent gaps are considered: a plane-parallel gap with an oscillating wall and at a constant pressure gradient and a conical gap at diff erent ratios of the pressure drop and the frictional action of the moving channel wall. When the wall oscillates in a conical gap and constant pressure, the presence of an extremum is characteristic. In this case, an excess pressure appeared in the slott ed gap, creating a supporting force, and the pressure value became high enough. When the lower wall of the conical slot moves in the direction of the increasing gap, the pressure inside the slott ed channel, under certain conditions, can reach a complete vacuum, the value of which is limited by the bulk strength of the liquid and the pressure of saturated vapor at a given temperature. When the pressure drop and oscillations of the wall of the conical gap are additive, then at a suffi ciently high velocity of the wall movement, the pressure inside the slot can even increase and exceed the value of the supplied pressure.