PSI - Issue 20

Volume 2 0 • 201 9

ISSN 2452-3216

ELSEVIER

1st International Conference on Integrity and Lifetime in Extreme Environment (ILEE-2019)

Guest Editors: Valeri y V . L e p ov

T heodoros R ousakis Bisong M b elle Samuel

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© 2019 The Authors. Published by Elsevier B.V. Peer-review under responsibility of the ILEE-2019 organizers © 2019 The Author(s). Published by Elsevier B.V. Peer-review under responsibility of the ILEE-2019 organizers Keywords: system of technical diagnostics; efficiency of diagnosing; quality of technical diagnosing; cost efficiency of system of technical diagnostics system diag osing. I practice the cost efficiency of the systems of technical diagn stics and various indexes characterizing quality of technic l diag osing are u ually calcul ed. In a general view, the "contribution" of th system of technical diagnostics to decrease in an ac i ent risk and r sk from operatio of the object f diagnostics can be estima ed on the ba i of th funct onal, ou ting the reduced cost of creation a d functio ing the system of t chnical diagnostics and the direct losse caused by risk of accident (refusal) of the sy tem of technical diagnostic . The inefficiency of the syst m f technical diagnostics is, s a rule caused by discrepancy of its parameters with th tasks solved by it; these t sks are: e elopment of algorithms of diagnosing, f recasting of change of technical condition, development of method and diagnost devices. This made it possible to formulate some main directions and conditions for the formation of effective systems of technical diagnostics. © 2019 The Autho (s). Published by Elsevier B.V. Peer-review under responsibility of the ILEE-2019 organizers Keywords: system of technical diagnostics; efficiency of diagnosing; quality of technical diagnosing; cost efficiency of system of technical diagnostics The growing importance of systems of technical diagnostics as an integral element of complex technical systems, determine the need of developing an assessment methodology and improve the effectiveness of systems of technical diagnostics themselves. Generally assessment of the impact of systems of technical diagnostics on results of functioning of an object of diagnostics can be received by comparison of indexes of efficiency of an object of diagnostics without the system of diagnosing and with the system of diagnosing. In practice the cost efficiency of the systems of technical diagnostics and various indexes characterizing quality of technical diagnosing are usually calculated. In a general view, the "contribution" of the system of technical diagnostics to decrease in an accident risk and risk from operation of the object of diagnostics can be estimated on the basis of the functional, accounting the reduced cost of creation and functioning the system of technical diagnostics and the direct losses caused by risk of accident (refusal) of the system of technical diagnostics. The inefficiency of the system of technical diagnostics is, as a rule, caused by discrepancy of its parameters with the tasks solved by it; these tasks are: development of algorithms of diagnosing, forecasting of change of technical condition, development of methods and diagnostic devices. This made it possible to formulate some main directions and conditions for the formation of effective systems of technical diagnostics. Th growing import ce of ystems of technical diagnostics as an int gral el ment of co plex technical systems, de er ine the n ed of developing an ass ss ent methodology and improve the effectiven s of systems of technical diagn stics themselves. G n rally assessment of the impact of systems of technical diagn stics o results of f nc ioning of an object of diag ostics can be r ceive by comparison of index s f ef i i f an object of diagnost s w thout he system of diagnosing and with the 1st International Conference on Integrity and Lifetime in Extreme Environment (ILEE-2019) Approaches to increasing the efficiency of systems of technical 1st International Conference on Integrity and Lifetime in Extreme Environment (ILEE-2019) Approaches to increasing the efficiency of systems of technical diagnostics V.I. Kuksova * Mechanical Engineering Research Institute, RAS , 4, M. Kharitonyevskiy Pereulok, 101990 Moscow, Russian Federation diagnostics V.I. Kuksova * Mechanical Engineering Research Institute, RAS , 4, M. Kharitonyevskiy Pereulok, 101990 Moscow, Russian Federation Abstract Abstract

* Corresponding author. Tel.: +7-916-133-3765; E-mail address: mibsts@mail.ru * Corresponding author. Tel.: +7-916-133-3765; E-mail address: mibsts@mail.ru

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1. Introduction The development of technical diagnostics, transformation of the systems of technical diagnostics (STD) to the integral element of complex technical systems (CTS) demanded a research of problems of efficiency of STD, assessment of their influence on production characteristics, safety and stability of the object of diagnostics (OD). The efficiency of STD depends on a number of factors; their action is defined by characteristics of the applied means of technical diagnosing, ability of an object to diagnosing, diagnostic providing (parameters of concrete STD), etc.

Nomenclature τ

the diagnosing period

I STD ( τ ) EF STD ( τ ) EF 0 ( τ ) STD ( τ )

index of effectiveness of a system of diagnosing

index of efficiency of an object of diagnostics with the system of diagnosing index of efficiency of an object of diagnostics without the system of diagnosing indexes, characterizing efficiency of an object with the system of diagnosing indexes of efficiency of an object without the system of diagnosing

k i k i a i n

0

weight coefficients of the corresponding characteristics

number of accepted indexes, characterizing efficiency of the object of diagnostics F ( a i k i STD ( τ )) function of the efficiency of an object of diagnostics with the system of diagnosing F ( a i k i 0 ( τ )) function of the efficiency of an object of diagnostics without the system of diagnosing R opt

functional determining the decreasing in an accident risk and risk from operation of OD as a result of functioning of STD

D 1 ( R ) D 2 ( R )

reduced cost of creation and functioning of STD direct losses caused by risk of accident (refusal) of STD

When determining efficiency of STD it is necessary to consider two aspects of assessment of effectiveness (efficiency) of technical diagnosing: assessment of the impact of STD on results of functioning of an object of diagnostics. assessment of effectiveness (quality) of functioning of STD itself. Diagnosing is an integral part of the processes of service of CTS, that’s why the indexes characterizing reliability and non-failure operation of their functioning, can be at the same time both STD and OD indexes. That’s why it is difficult to separate some attributes of the system of technical diagnostics and the object of diagnostics from each

other, and in a sense such division has conditional character. 2. Quantitative assessment of results of functioning of STD

Quantitative assessment of results of functioning of STD is important for practical purposes. In a general view, assessment of the impact of STD on results of functioning of OD can be received by comparison of indexes of efficiency of an object of diagnostics without the system of diagnosing EF 0 ( τ ) and with the system of diagnosing EF STD ( τ ). The index of effectiveness of a system of diagnosing I STD ( τ ) can be written as Gumenyuk (2010):

STD

o

( )

( )

( ) EF F a k (

( ))

( F a k i i

( )),

1,

I

EF

i

n .

(1)

0

STD

STD

i i

Assessment of effectiveness of functioning of STD itself is made on the basis of indexes of quality of technical diagnosing, which, as a rule, are the following by Akhmetkhanov et al. (2016): 1. The duration of the technical diagnosing (time interval necessary for carrying out diagnosing of an object). 2. The reliability of diagnosing, estimated by the degree of objective compliance of results of diagnosing to the real

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technical condition of OD. 3. The conditional probability of the undetected refusal – probability of that: a faulty (disabled) object as a result of diagnosing is recognized as properly functioning (efficient); in the presence of refusal (malfunction) as a result of diagnosing the decision on lack of refusal (malfunction) in the element of OD is made. 4. The conditional probability of the false refusal – probability of that: a properly functioning (efficient) object as a result of diagnosing is recognized as faulty (disabled); in the absence of refusal (malfunction) as a result of diagnosing the decision on existence of refusal (malfunction) in the element of OD is made. 5. The accuracy of diagnosing is characterized by compliance of results of the diagnosis to real indexes. It’s estimated with the help: a mean square deviation of the predicted parameter of technical condition of OD for the considered time period; a mean square deviation of the predicted OD residual resource; a probability of no-failure operation of OD, indexes of change of the predicted diagnostic parameter; a fiducial probability of the received diagnosis (the lower bound of probability of no-failure of OD in safety parameters for the considered time period). 6. The completeness of technical diagnosing. It can be determined by the relation of number of the parameters, captured by monitoring, to total number of the parameters, defining operability of an object. 7. The depth of searching of the place of refusal (malfunction) – the characteristic, set by the indication of a constituent of an object, with an accuracy to which the refusal (malfunction) is located. 8. The anticipation interval – the estimated time before the predicted refusal of OD, allowing to define the maintenance moment to avoid refusals and accidents. 9. The safety and resistance of STD to influence of the damaging factors of an emergency. 10. Technical and economic characteristics of diagnosing: cost per unit of diagnosing; average operational labor input of diagnosing; average operational duration of diagnosing; frequency of diagnosing. 11. Information indexes of quality of diagnosing and information value of results of diagnostics. 3. Cost efficiency of STD In practice they usually calculate (taking into account branch features of OD) the cost efficiency of STD and various indexes characterizing quality (target effectiveness) of technical diagnosing. The cost efficiency of STD is defined by comparison of expenses on creation, equipment, maintenance and development of STD with the received economy from results of its functioning. Economy from results of functioning of STD consists of two main components: economy of the current expenses on OD from implementation of STD; sum of losses, prevented from reducing accident rates OD. Depending on branch specifics of OD, the savings of the current expenses from the implementation of the STD can be formed by the following articles:

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Fig. 1. Main directions and conditions of formation of effective systems of technical diagnostics.

reduce the costs of maintaining equipment in working condition; an increase in the average time between repairs (increased productivity and reduced maintenance costs);

actual elimination of unforeseen refusals (increased reliability and efficiency); elimination of an excessive expense of details (replacement of serviceable parts); reduce the volume of renewals (issue of warning of need of the order of renewals); increased safety (decrease in probability of unforeseen refusals); increase in efficiency of productions; increases in non-failure operation, reduction of restoring time; increase availability and technical use; improvements of indexes of a longevity, etc.

An important index of safe operation of OD is the sum of losses, prevented from reducing accident rates OD as a result of functioning of STD. The sum of the prevented losses, depending on branch specifics, is defined by the extent of the prevented losses from decrease of number of refusals as a result of work of a system, the prevented accidents and emergency on potentially dangerous objects, etc. In a general view, STD «contribution» to decrease in an accident risk and risk from operation of OD can be estimated on the basis of the following functional:

min ( )

( ) D R D R

opt R

.

(2)

1

2

Using the Ropt functional in the development of a special system of technical diagnostics allows optimizing the costs of creating and operating STD taking into account the possible level of risk of its accident (refusal).

4. Increasing of the efficiency of STD Practice shows that the inefficiency of STD is, as a rule, caused by discrepancy of characteristics (parameters) of

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STD to the tasks solved by it; these tasks are: development of algorithms of diagnosing, forecasting of change of technical condition, development of methods and diagnostic devices by Makhutov et al. (2016). Proceeding from the tasks solved by STD, it is possible to formulate the following main directions and conditions of formation of effective systems of technical diagnostics (see fig. 1).Concrete techniques of assessment of effectiveness of STD substantially depend on branch accessory of an object of diagnostics. Objects of defense industry, railway transport and methods of diagnostics of provable medicine can be examples. The formulated main directions and conditions for the formation of effective systems of technical diagnostics reflect solutions of primal problems of assessment and increase in effectiveness of STD. The best results at the same time can be achieved only on the basis of complex increase in target effectiveness of all STD elements defining quality of its functioning. 5. Conclusions So far in a number of the industries the practical experience of the quantitative assessment of effectiveness of STD including determination of their cost efficiency and also calculation of various indexes characterizing quality (target effectiveness) of technical diagnosing is accumulated. At the same time the number of questions demands specification and a further research. This refers primarily to differences in approaches to assessing the effectiveness of newly created and functioning STDs that need modernization. In the first case, the indexes discussed above can be applied (taking into account industry specifics). For functioning STDs, the choice of directions and conditions for increasing their effectiveness as applied to the main tasks solved by STDs becomes decisive. The issues related to the use of a generalizing parameter (function, functional) of the effectiveness of STDs are also insufficiently investigated. In this area, the use of fuzzy logic methods and models opens up new possibilities. References Akhmetkhanov R.S., Dubinin E.F., Kuksova V.I., 2016. Some Aspects of Assessment of the Effectiveness of Diagnostic Systems. Messenger of Scientific and Technical Development 4 (104), 3-18 (in Russian). Gumenyuk V.M., 2010. Reliability and Diagnostics of Electrotechnical Systems, in: Publishing House of the Dalnevost. Federal Technol. University (Ed.). Vladivostok, pp. 218 (in Russian). Makhutov N.A., Akhmetkhanov R.S., Dubinin E.F., Kuksova V.I., 2016. Assessment and Increasing of the Efficiency of Diagnostic Systems. Problems of Safety and Emergency Situations 4, 8-24 (in Russian).

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1st International Conference on Integrity and Lifetime in Extreme Environment (ILEE-2019) Assessment of the emergency recovery ability of heat supply systems in conditions of the Far North Ivanov V.N. a , Ivanova A.V. a , Stepanov A.V., b Kolodeznikova A.N. a, * a North-Eastern Federal University name M.K. Ammosov, Institute of Engeneering & Technology, 50, Kulakovskogo str., Yakutsk, 677000, Russia b V.P. larionov Institute of the Physical-Technical Problems of the North of the Siberian Branch of the RAS, 1, Oktyabr’skaya str,. Yakutsk, 677890, Russia The reliability of heat supply systems depends on the prevention, failure control and improving the efficiency of individual elements of heating systems and heat networks. Standard service life is determined for the operating conditions of central Russia. The heating system and heating networks in the North are engineering according to uniform requirements, as in the middle lane, but they work under more severe conditions due to the extended heating season and low average temperature of the heating period. This paper presents a novel study of the definition of service life and emergency recovery work, considering the factors of geographical location and climatic conditions of operation of elements of heating systems. Performed the analysis of statistical and calculated data for the operation of engineering systems for conditions of the Far North and the Arctic. As a pilot study, heating and heat supply systems are used in Yakutsk, Russia. An analysis of emergency situations of buildings. The results show that the indicator of heat resistance can be used as one of the indicators to select the optimal combination of centralized and decentralized heat supply, taking into account the provision of repair and rehabilitation works. Revealed the dependencies of the period of operational and restoration work on the initial parameters, changes in the temperatures of the internal and external air, the material of the structures and the element of the systems. 1st International Conference on Integrity and Lifetime in Extreme Environment (ILEE-2019) Assessment of the emergency recovery ability of heat supply systems in conditions of the Far North Ivanov V.N. a , Ivanova A.V. a , Stepanov A.V., b Kolodeznikova A.N. a, * a North-Eastern Federal University nam M.K. Ammosov, Institute of Eng neering & Tec nology, 50, Kulakovskogo str., Yakutsk, 677000, Russia b V.P. larionov Institute of the Physical-Technical Problem of the North of the Siberian Branch of the RAS, 1, Oktyabr’skaya str,. Yakutsk, 677890, Russia Abstract The reliability of heat supply systems depends on the pre ention, failur co trol and im rovi the efficiency of individu l elements of heating systems and heat networks. Standard service life is determined for the operating co ditions of central Russia. The eating system and heating networks in the North are engineering according to uniform requirements, as in the middle lane, but they work under more severe conditions du to the extended heating season and low average temperature of the heating p riod. This paper presents a novel study of the definition of service life and mer ency recovery work, considering the factors of geogr phical loc tion and climatic conditions of operation of eleme ts of heating systems. Performed the analysis of statistical and calculated data for the oper tion of e gineering systems for conditions of the Far North and the Arctic. As a pilot study, heating and heat supply systems are used in Yakutsk, Russia. An analysis of emergency situations of buildings. The results show that the indicator of heat resistance c n be used as one of the indic tors to select the optimal combination of centralized and d centralized heat supply, taking into account t provision of repair and r habilitation works. Reveal d the depe encies of the period of operational and restoration work on the initial parameters, changes in the temperatures of the internal and external air, the material of the structures and the element of the systems. Abstract

© 2019 The Authors. Published by Elsevier B.V. Peer-review under responsibility of the ILEE-2019 organizers © 2019 The Author(s). Published by Elsevier B.V. Peer-review under responsibility of the ILEE-2019 organizers © 2019 The Author(s). Published by Elsevier B.V. Peer-review under responsibility of the ILEE-2019 organizers

Keywords: reliability, safety, service life, recovery period, emergency recovery ability, critical thermal condition of a building, the Far North and the Arctic. K ywords: reliability, safety, service life, recovery period, emergency recovery ability, critical thermal condition of a building, the Far North and the Arctic.

* Corresponding author. Tel.: +8-964-422-39-21. E-mail address: Anika20052009@mail.ru * Correspon ing author. Tel.: +8- 64-422-39-21. E-mail address: Anika20052009@mail.ru

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1. Introduction

The system of maintenance, repair and reconstruction should ensure the normal functioning of buildings and engineering systems during the entire period of their use as intended. The timing of the repair of buildings, engineering systems or their elements should be determined on the basis of an assessment of their technical condition found by Ionin (1989). The reliability of the individual elements of heating systems and heat networks depends on the life of each element. One of the areas of prevention and prevention of failures, improving the efficiency of operational work of the building's heat supply systems is the definition of the service life of each element of heating systems and heat networks.

Nomenclature 

failure rate of the heating system estimated time estimated time



λ i

thermal conductivity of the material of thermal insulation, (W/m·º С )

d str d out

outer diameter of the insulating structure, (m) outer diameter of the isolated object, (m)

the heat transfer coefficient from the outer surface of the insulating structure, (W/m 2 ·º С )

α

d int

internal diameter of the steel pipe, (m)

coolant density, (kg/m 3 )

ρ c c c

specific heat carrier coolant, (kJ/kg·º С )

d ext external diameter of the steel pipe, equal to the internal diameter of the heat-insulating layer, (m) t cr crystallization temperature of the coolant, (º С ) t out outdoor temperature, (º С ) t c coolant temperature, (º С ) t vk acceptable minimum value of t i , (º С ) Standard service life (the minimum duration of the effective operation of the elements) of engineering equipment are given in reference books and they contain the recommended frequency of repair and construction works. See VSN (1990), GOST (2015). The standard service life of each element of the heating system and heating networks is determined for the operating conditions of central Russia. It does not take into account the geographical place of use of the equipment, climatic conditions of operation. The heating system and heating networks in the North are designed the same as in the middle lane, but they work in more difficult conditions due to the extended heating season and low average temperature of the heating period. 2. Materials and methods The analysis was carried out according to the method of calculating the reliability indicators, given by Ivanov (1990) in Chapter 2. The probability of trouble-free operation of the heating system and heat networks is determined: ܲ ൌ ݁ ఒήఛ (1) In the analysis to determine the service life of the element of the heating system and heating networks, only the change in the heating period and the average temperature of the heating period are taken into account. The following assumptions are made in the calculations: the heat supply systems are designed to be the same, the failure rates of the same type of elements are equal and are distributed according to the exponential law.

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For example, table 1 shows the service life of some elements of the heating system and heating networks in the conditions of the city of Yakutsk, calculated from these data.

Table 1. The duration of the effective operation of the elements heating systems.

Duration of operation to overhaul (replacement), (years) Regulatory data For Yakutsk

Elements of heat supply systems for buildings

Pipelines

30 25 12

24 19 10

Risers with closed circuits

Brownies Highways

In Yakutsk conditions, the service life of elements of heating systems and heat networks is almost 18% shorter than is customary in the reference data. Knowledge of the estimated service life depending on the terrain will allow you to plan overhauls and effectively use the turnaround time. Difficult and crucial tasks arise before the service operation in extreme conditions: in case of accidents in the heat supply system, especially during the cold period of the heating season shown by Inga Šar ū nien ė et al (2016), Shanshan et al (2017), Wojdyga (2009). The specific nature of the climatic conditions of the North puts forward special requirements for a comprehensive solution to the problem of human security and its environment in the event of natural and man-made accidents and disasters. Examples of major accidents show that the safety of the population, industrial enterprises and social and cultural facilities in Yakutia in winter is mainly determined by the reliability of energy supply. Emergencies associated with the violation of heat supply of buildings pose a potential danger of unacceptable deterioration of the thermal conditions in the premises. All this can cause serious material and moral damage, even bring a threat to the safety of human life and production, pointed by Kononovich (1989), in Recommendations (1987), by Kilatchanov and Shomoev (1999). Engineering communications are in the zone of low temperatures. Field studies show that the temperature near the floor decreases by 5 ... 10°C than in the middle zone of a room 1.5 m from the floor. Under these conditions, at the termination of circulation or low velocity of the coolant, there is a risk of its freezing. The time during which the temperature of the coolant decreases to the crystallization temperature can be determined by Kolodeznikova (2018), Zhirkova (2013), Dulkin et al (2014), SP (2004): ݐ ൌ ቀ ଶగ ଵ ఒ ೔ ݈݊ ௗ ೞ೟ೝ ௗ ೚ೠ೟ െ ఈగௗ ଵ ೞ೟ೝ ቁ ቀ ߨ ௗ ೔ మ ೙೟ ସ ߩ ௖ ܿ ௖ ൅ ߨ ௗ ೐మ ೣ೟ ିௗ ೔ మ ೙೟ ସ ቁ ݈݊ ቀ ௧ ೎ೝ ି௧ ೚ೠ೟ ௧ ೎ ି௧ ೚ೠ೟ ቁ (2) 3. Results and discussion Analysis of the time of cooling water in the return pipe of heat networks is shown in figures (fig. 1, 2). The calculation was made with different parameters of the coolant: 95-70 (° С ) and 80-60 (° С ). As thermal insulation, the most used in the North are mineral wool mats with thermal conductivity λ = 0.06 (W/m·°C) and thickness δ = 0.100. Analysis of accidents of heating systems and heating networks of Yakutia (12-apartment residential building of health workers in Markha, an accident in Block A of the NRC and OMTsZ buildings, freezing of hospital complexes in Nyurba, Vilyuisk, Zhigansk, Olenek, etc.) showed that first of all there was a freezing of the heating systems of the terminal branches, staircases, at the entrances and in buildings with low thermal resistance connected to external networks and only then in the heat networks. Changes in the air temperature in a residential area after the heating is turned off are shown in Table 2. Thus, lowering the air temperature in residential premises to 10...12° С is an indicator of the critical thermal condition of the building, since at the same time the temperature conditions of the room become extremely unfavorable for a person, emergency conditions for the work of engineering equipment are created. The analysis of the time to reduce the temperature in a residential area to a critical level during an accident of the heat supply system, which is given above (Table 2), indicates the rapid development of this phenomenon depending

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on the building envelope, found by Malyavina (2015), Malyavina and Tsygankov (2015), Zhirkova and Kolodeznikova (2017), Dulkin et al (2014), Xiaofang (2017).

Fig. 1. The cooling time of water in heat networks with a diameter of 57 (mm), the parameters of the coolant 95-70 (°C) and 80-60 (°C): 1 – t out =-40° С ; 2 – t out =-50° С ; 3 - t out =-60° С ; 4 – t out =-40° С ; 5 - t out =-50° С ; 6 - t out =-60° С .

Fig. 2. The cooling time of water in heat networks with a diameter of 108 (mm), the parameters of the coolant 95-70 (°C) and 80-60 (°C): 1 – t out =-40° С ; 2 – t out =-50° С ; 3 - t out =-60° С ; 4 – t out =-40° С ; 5 - t out =-50° С ; 6 - t out =-60° С .

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Table 2. The change in air temperature in the room after turning off the heating. t out , (  С ) t int , (  С ) z=2 z=4 z=6

Air temperature after switching off the heating in z hours, (  С )

z=8

z=10

z=12

Brick

22 20 18 16 22 20 18 16 22 20 18 16 22 20 18 16 22 20 18 16 22 20 18 16 22 20 18 16 22 20 18 16 22 20 18 16 22 20 18 16 22 20 18 16 22 20 18 16

14.5 12.7 10.9 15.0 13.2 11.4 16.0 14.2 12.3 10.5 16.9 15.1 13.3 11.5 12.9 11.2 9.1 9.6 13.5 11.8 10.0 14.7 12.9 11.2 15.8 14.1 12.3 10.6 12.1 10.3 8.2 9.4 9.4 7.6

13.2 11.4

11.9 10.1

10.6 8.9 7.2 5.5 9.6 7.9 6.2 11.3 12.8 11.1

9.4 7.7 6.1 4.4 8.5 6.9 5.2

8.1 6.5 4.8 3.2 9.0 7.4 5.7 4.1 9.2 7.5 5.9

- 55

9.6 7.8

8.4 6.7

13.7 12.0 10.2 14.9 13.1 11.3 16.0 14.3 12.5 10.7 8.4 9.6 8.5 6.8 5.1 9.2 7.6 5.9 10.9 12.5 10.8 10.2

12.5 10.8

10.2

- 50

9.1 7.3

13.8 12.1 10.4 15.2 13.4 11.7 10.0 8.6

11.8 10.2

10.8

- 40

9.4 7.7

8.5 6.8

14.3 12.6 10.9

13.5 11.8 10.1

12.6 11.0

-30

9.3 7.7

9.2

8.5

Wooden

8.4 5.9 4.2 2.6 8.4 6.8 5.2 3.6 8.7 7.1 5.4 5.2 3.7 2.1 0.5 6.3 4.7 3.2 1.6 8.5 6.9 5.4 3.8 9.1 7.5 6.0 8.9 7.3

4.9 3.4 1.8 0.3 6.0 4.5 2.9 1.4 8.3 6.7 5.1 3.6 8.9 7.4 5.8 2.0 0.5

2.5 1.0

0.1 -1.3 -2.7 -4.2 1.5 0.1 -1.3 -2.8 4.4 2.9 1.5 0.1 7.2 5.8 4.4 2.9 -3.9 -5.2 -6.5 -7.8 -2.2 -3.5 -4.8 -6.2 1.2 -0.1 -1.5 -2.8 4.5 3.2 1.9 0.6

- 55

-0.5 -2.0 3.7 2.2 0.7 -0.8 6.3 4.8 3.3 1.8 8.8 7.3 5.8 4.3 -0.9 -2.4 3.8 -5.2 0.5 -0.9 -2.3 -3.7 3.5 2.1 0.7 -0.7 6.5 5.1 3.7 2.3

- 50

10.3

- 40

9.1 7.4

14.0 12.3 10.6

12.2 10.6

10.5

- 30

8.9

Effective three-layer panel

8.5 6.9 5.2 3.6 9.4 7.8 6.1 4.5 9.5 7.9 6.2

- 55

8.6 6.9

-0.9 -2.4 3.3 1.8 0.4 -1.1 5.9 4.4 3.0 1.5 8.5 7.0 5.5 4.1

12.7 11.0

- 50

9.2 7.5

14.0 12.3 10.5 15.3 13.6 11.8 10.1 8.8

11.2

-40

12.9 11.3

10.7

-30

9.6 8.0

Accidents can occur at any random point in time. Analysis of the emergency of the building shows the dependence of the decrease in room temperature on the initial temperature of the room (Table 2). The (fig. 4) graphically shows the temperature change at different temperatures of the indoor air. For example, under the conditions of Yakutsk in stone buildings that have an internal air temperature before the accident 22°C, the critical temperature 10°C occurs after 9 hours, and at 18°C - after 4 hours. In wooden buildings, the rate of decrease in temperature is even faster, respectively, at 22°C in 5 hours, at 18°C in only about 2 hours.

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The duration of repair work in emergency situations can be estimated using the following formula when the heating system of a building is completely turned off: œ ൏ ߚ ή ୏ భ ሺ୲ ౟౤౪ ି୲ ౥౫౪ ሻ ሺ୲ ౬ౡ ି୲ ౥౫౪ ሻ (3) The air temperature t vk should not create conditions for the freezing of water in pipes and heating appliances. The permissible minimum value of the internal temperature of the room in case of an accident, t vk = 10 ... 12°C is an indicator of the critical thermal condition of the building, since this makes the temperature conditions extremely unfavorable for a person and emergency conditions for the work of engineering equipment are created. For the specified conditions, z at t vk = 10° С and t o = -30° С lies in the range of 6 ... 18 h. If t o goes down to -55° С , then z decreases to 3 ... 10 h.

t i , С

24

20

1

16

2

12

3

8

4

5

4

6

0

0

2

4

6

8

z,

Fig. 3. Graph of t = f (z) for different values β and t i :1- β =100, t int =22  С , t out =  55  С ; 2- β =100, t int =22  С , t out =  30  С ; 3- β =50, t int =22  С , t out =  55  С ; 4- β =100, t int =18  С , t out =  55  С ; 5- β =100, t int =18  С , t out =  30  С ; 6- β =50, t int =18  С , t out =  55  С For example, turning off the light in the village of Borogontsy caused the boilers to stop. Due to an incorrect calculation of the cooling time of the internal air temperature of a building, 65% of the heating systems were frozen, the reason being the late late discharge of water from the heating system. Another example, in the village of Olenyok, there was also a light cut-off, hurried, flushed the system, switched on electricity, incurred high costs with filling the system with imported water, starting the system, later 2 residential houses were frozen. Indicator maintainability is the probability of recovery of the system element within the allowable time z a , proveded by Ivanov (2001), Villemeur (1992), Valinc  ius (1992). To eliminate the failure within this time by a probability of 0.9, it is necessary that z rec = 0.433·z a . In this case, the permissible time should be (2.3) ... (4.6) hours.

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The average recovery time in the conditions of Yakutia can be taken 1, 2 hours more than in Moscow, which is shown by experimental data. In this regard, in order to guarantee the provision of repair and restoration work, for heating systems connected to heat networks, it is proposed to introduce a minimum value of heat resistance index β for a given area. The indicator β , which characterizes the ratio of the values of specific heat capacity and heat loss of the room, is associated with the thermal massiveness of the external walls. Therefore, the massiveness of exterior walls for mass buildings should, depending on the terrain, be set to a minimum value, below which it cannot be connected to centralized networks in terms of maintainability. Thus, the indicator of heat resistance can be used as one of the indicators for choosing the optimal combination of centralized and decentralized heat supply, taking into account the provision of repair and rehabilitation works. The relevance of this issue is increasing in connection with the development of energy-saving buildings, which require increased standards for heat transfer resistance. In the conditions of Yakutia, it is necessary to apply only combined building structures to fulfill these norms. The duration of repair work in emergency situations, defined by the formula (3) for buildings with various enclosing structures, is given in Table 3.

Table 3. The duration of repair work in case of emergency.

z, hour t out , о С

t int , о С

-55

-50

-40

-30

-20

Stone building

22 20 18 16 22 20 18 16 22 20 18 16 22 20 18 16

21.0 17.7 14.3 10.8 17.3 14.6 11.8

23.5 20.0 16.3 12.5 19.4 16.5 13.5 10.3

30.0 25.8 21.5 17.1 24.7 21.3 17.7 14.1

39.5 34.6 29.5 24.1 32.5 28.5 24.3 19.8 14.9 13.0 11.1

55.1 49.0 42.4 35.6 45.4 40.4 34.9 29.3 20.8 18.5 16.0 13.4 16.1 14.3 12.4 10.4

Brick building

8.9

Wooden building

7.9 6.7 5.4 4.1 6.1 5.2 4.2 3.1

8.9 7.6 6.2 4.7 6.9 5.8 4.8 3.7

11.3

9.8 8.1 6.5 8.7 7.5 6.3 5.0

9.1

Effective three-layer panel

11.5 10.1

8.6 7.0

The service of operating heat supply systems in the Arctic and the Far North is faced with the task not only to operate normally, but also not to allow an emergency situation. Accidents in the winter can have disastrous consequences for the safety of the population and have large material costs. At low ambient temperatures, stopping the operation of the heating system can lead to the freezing of the entire system for the entire subsequent heating period, without the possibility or sufficiently difficult restoration of the operating state. 4. Conclusions Thus, we can distinguish the following conclusions: 1. The service life of the elements of the heat supply systems of buildings in the long heating season, which is characteristic in the conditions of Eastern Siberia, is reduced to 17 - 33% relative to regulatory data. 2. The calculation of the cooling time of thermal networks and building premises shows that buildings with low thermal stability cool faster than thermal networks, therefore the cooling time of external thermal networks with a

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minimum diameter of 57x3 and the cooling time of buildings with a low thermal stability coefficient should be taken as the basis for the repair time. 3. Cooling of the room temperature depends on the initial room temperature before the emergency stop, the thermal stability of the enclosing structures and the outdoor temperature. 4. In the conditions of the Far North, in order to restore the heating network systems, it is necessary to build buildings with a heat resistance coefficient of β ≤ 45. References Dulkin, A.B., Dulkin, B.A., Golovanchikov, A.B, 2014. Assessment of time of freezing of water in the pipeline. News of Volgograd State Technical University 1(128), 19-22. GOST R 56501-2015. Housing and communal services and management of apartment buildings. Maintenance services of house heating systems, heating and hot water supply of apartment buildings. Standardinform, Moscow, 2016. Inga Šar ū nien ė , Juozas Augutis, Ri č ardas Krikštolaitis, Gintautas Dundulis, Mindaugas Valincius, Rimkevicius Sigitas, 2016. Risk and reliability assessment of the district heating network methodology with case study. Conference Paper. European safety and reliability conference ESREL, September 2016, 2578-2585. Ionin, A.A., 1989. Reliability of heating networks. Stroyizdat, Moscow, pp. 268. Ivanov, V.N., 2001. Features of ensuring the thermal regime of buildings in Eastern Siberia. PhD dissertation. NNGASU, Nizhniy Novgorod. Kilatchanov, A.P., Shomoev, V.M., 1999. Security of operation of heat supply systems. Journal of the head and chief accountant of housing and public utilities 10, 18-20. Kolodeznikova, A.N., 2018. The effect of the reduced temperature schedule of heating systems on the thermal regime of heated buildings. Modern problems of construction and life support: safety, quality, energy and resource saving. Collection of articles of the Vth All-Russian Scientific and Practical Conference, Yakutsk, 315-319. Kononovich, Yu.V., 1986. Thermal regime of buildings of mass building. Stroyizdat, Moscow, 157. Malyavina, E.G., 2015. Calculation of the rate of cooling of a room after turning off the heat supply. Industrial and Civil Engineering 2, 55-58. Malyavina, E.G., Tsygankov, A.V., 2015. The influence of various factors on the rate of cooling of the room after the heat supply is turned off. News of universities. Building 1, 53-59. Recommendations for the preparation of housing for the winter. 1987. TSNIIEP engineering equipment, Moscow, pp. 71. Shanshan Cao, Peng Wang, Wei Wang, Yang Yao., 2017. Reliability evaluation of existing district heating networks based on a building's realistic heat gain under failure condition. Science and Technology for the Built Environment 23, 522-531. SP 23-101-2004 Design of thermal protection of buildings. Gosstroy of Russia FSUE ZPP, Moscow, 2004. Valinc  ius, Z  utautaite I., Dundulis G., Rimkevicius S., Janulionisa R., Bakas R.., 2015. Integrated assessment of failure probability of the district heating network. Reliability Eng Syst Saf 22, 133:314. Villemeur, A., 1992. Reliability, availability, maintainability and safety assessment, hardware. Software and Human Factors: Wiley. VSN 58-88 (r), 1990. Regulations on the organization and conduct of reconstruction, repair and maintenance of buildings, public facilities and socio-cultural purposes. Stroyizdat, Moscow, 32. Wojdyga, K., 2008. An influence of weather conditions on heat demand in district heating systems. Energy Build 40(11), 14. Xiaofang Shan,Peng Wang,Weizhen Lu. The reliability and availability evaluation of repairable district heating networks under changeable external conditions. Applied Energy. Elsevier 203, 686-695. Zhirkova, M.V., 2013. Improving the reliability of heat supply systems of small settlements in the Far North. Industrial and civil construction 8, 47-50. Zhirkova, M.V., Kolodeznikova, A.N., 2017. Indicators of the efficiency of the operational state of the heating system. International Research Journal 1(55), 67-69.

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1st International Conference on Integrity and Lifetime in Extreme Environment (ILEE-2019) Basic approaches to ensuring structural integrity of technical systems D. Reznikov a, * a Mechanical Engineering Research Institute, RAS. 4 Maly Kharitonievsky lane, Moscow,101990, Russia Structural reliability of technical systems is to be insured in the presence of high level of uncertainty related to natural variability of loads acting on the system, scatter of mechanical properties of structural materials, inaccuracies of geometrical dimensions, imperfections of test equipment and design models. In the view of these uncertainties two basic approaches to securing structural integrity can be distinguished: deterministic (standard-based) approach founded on the application of the so called safety factors that are introduced into the design equation to compensate uncertainties; and probabilistic (reliability-based) approach that requires that the probability of structural failure occurrence not to exceed some allowable limiting value considered acceptable by society at the current stage of the technological development, available resources and the willingness of the society to pay for the implementation of protection measures. The paper presents a comparative assessment of deterministic and probabilistic approaches to securing structural integrity of technical systems subjected to various types of loading regimes. The condition of the equivalence of these two basic approaches to securing structural integrity is considered. 1st International Conference on Integrity and Lifetime in Extreme Environment (ILEE-2019) Basic approaches to ensuring structural integrity of technical systems D. Reznikov a, * a Mechanical Engineering Research Institute, RAS. 4 Maly Kharitonievsky lane, Moscow,101990, Russia Abstract Structural reliability of technical systems is to be insured in the presence of high l vel of uncert inty relat d to natural variability of loads acting on th system, scatter of mechanical properties of structural materials, inaccuracies of geometrical dimensions, imperfectio s of test equipment and design models. In the view of these uncertainties two basic approaches to securing structural integrity can be distinguished: deterministic (standard-based) approach founded on the application of the so called safety factors that are introduced into the design equation t ompensate uncertainties; and pro abilistic (reliability-bas d) approach that requires that the probability of structural failure occurrenc not to exceed s me allowabl limiting value considered acceptable by society at the current stage of the technological development, available resources nd the willingness of the society to pay for the im lementation of protection measures. Th paper presents a comparative assessment of eterministic and probabilistic approaches to securing structural integrity of technical systems subjected to various types of loading regimes. The condition of the equivalence of these two basic approaches to securing structural integrity is considered. Abstract

© 2019 The Authors. Published by Elsevier B.V. Peer-review under responsibility of the ILEE-2019 organizers © 2019 The Author(s). Published by Elsevier B.V. Peer-review under responsibility of the ILEE-2019 organizers © 2019 The Author(s). Published by Elsevier B.V. Peer-review under responsibility of the ILEE-2019 organizers Keywords: stractural integrity; safety factor; probability of failure Keywords: stractural integrity; safety factor; probability of failure

2452-3216 © 2019 The Author(s). Published by Elsevier B.V. Peer-review under responsibility of the ILEE-2019 organizers 2452 3216 © 2019 Th Author(s). Publis d by lsevier B.V. Peer-review under responsibility of the ILEE-2019 organizers * Correspon ing author. Tel.: +7-495-623-5835; fax: +7-495-623-5835. E-mail address: imashreznikoff@yandex.ru. * Corresponding author. Tel.: +7-495-623-5835; fax: +7-495-623-5835. E-mail address: imashreznikoff@yandex.ru.

2452-3216 © 2019 The Authors. Published by Elsevier B.V. Peer-review under responsibility of the ILEE-2019 organizers 10.1016/j.prostr.2019.12.109

D. Reznikov / Procedia Structural Integrity 20 (2019) 17–23 D. Reznikov / Structural Integrity Procedia 00 (2019) 000–000

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2

1. 1. Introduction

Structural failure refers to the loss of structural integrity, or the loss of the ability of a technical system ( TS ) to withstand its intended loading without failing due to fracture, excessive deformation, or fatigue and remain functional for a desired service life in real environmental service conditions.

Nomenclature c i

capacity parameter

{ C }

vectors of capacity parameters

d i

demand parameter

{ D } E { x }

vectors of demand parameters

mathematical mean of the random variable x

K IC fracture toughness, K I max maximum stress intensity factor N C ( σ a ) number of cycles to failure at the specific load amplitude n i safety factor against the i -th failure mechanism [ n i ] normative safety factors against the i -th failure mechanism N ( σ a ) number of loading cycles at a specific load amplitude P f estimated probability of the system’s failure [ P f ] tolerable value of the system’s failure probability t time T d design service life δ C critical displacement,  max maximum displacement * ( ) i t   maintenance function Δ i ( t ) degradation function ε max maximum local strain ε y yield strain, σ max maximum local stress σ y yield strength ζ maintenance program χ societal criterion factor

Structural failure occurs when at least one of the so-called demand parameters (maximum local stress σ max , maximum local strain ε max , maximum stress intensity factor K I max , maximum displacement  max , number of loading cycles at a specific load amplitude N ( σ a ), etc.) exceeds the respective capacity parameter of the structure (yield strength σ y , yield strain ε max , fracture toughness K IC , critical displacement δ C , number of cycles to failure at the specific load amplitude N C ( σ a ), etc.), Makhuov (2008), Doronin et al. (2005):

;

max     max max K K  ; Y Y I max    ( ) a C ;

   

  

;

IC

max    N    

N

( ); 



C a