Numerical analysis of reinforced concrete beam subject to pitting corrosion

This paper presents a numerical study about the effects of chloride-induced corrosion on the service life of structures. A two-dimensional geometrically nonlinear mechanical model based on Finite Element Method (FEM) was developed for reinforced concrete structures. The corrosion initiation stage was evaluated by Fick's diffusion laws. The corrosion propagation was carried out by deterministic models based on Faraday's law. Pitting corrosion was simulated in the reinforcements by pit elements, distributed longitudinally on the steel rebars, which degrade the physical properties over time. The service life was determined by the crack width.Two parametric analyses were performed. In the first analysis, five models were created with a variablecover thickness and water/cement ratio (w/c). In the second analysis, the reduction in yield stress due to corrosion was considered.The results showed that the concrete cover thicknessand the w/c ratio significantly influence the service life. The reduction of the cover thickness from 30 mm to 25 mm resulted in 21.26% reduction in service life, whilethe increase in the w/c ratio from 0.50 to 0.55 caused 32.98% reduction in service life of the structural element analyzed.

Development of a Universal Scale for Validating the Process of Sanitization of Equipment, Materials and Surfaces in the Animal Facility

Background: Monitoring of sanitization of cage equipment is an essential function of any laboratory animal facilities, seeking to ensure the animal health and welfare. The purpose of the current study was to develop universal scale for monitoring sanitization through detection of residual ATP for the most effective process of sanitizing components of rodents micro- and macro-environment. Methods: Sterile pens and swabs for the HY-LiTE® Luminometer Instrument were used to measure ATP concentration (RLU) on the cleaned surface samples. We have examined the elements of the microenvironment (rodent and rabbit cage, cage wire meshes, feed separating pieces, water bottles with tips, houses, tunnels, IVC cage frames, cage tops and cage wire meshes). The assessed swab area on each of the surfaces was 10×10 cm. Result: We observed, that combined washing (cleaned manually and with automatic universal washers with detergent) gives the lowest RLU values. Monitoring of the quality of sanitization of equipment and surfacescan be carried out without the use of microbiological tests. Use of pre-washing allows increasing the service life of caging equipment. We have developed an assessment scale to monitor sanitizing, which can be recommended to scientific and breeding animal facilities for monitoring sanitization cage equipments.

Durability Assessment of ETICS: Comparative Evaluation of Different Insulating Materials

The External Thermal Insulation Composite System (ETICS) is a common cladding technology that is widely used thanks to its well-known advantages. Despite previous studies dealing with ETICS durability in real-building case studies or involving accelerated ageing tests in climatic chambers, little progress has been made in the knowledge of the long-term durability of the system. In order to realize optimized maintenance plans for this component, the durability of the whole system, and of the most-used insulating materials for the ETICS (i.e., cork, polyurethane, rock wool, glass wool, grey EPS, and fiberfill wood), has been investigated. Based on previous experiments on ageing cycles, different climatic chambers were used to accelerate performance decay by simulating natural outdoor exposure in order to assess different physical and thermal characteristics (thermal transmittance, decrement factor, time shift, water absorption, thermal resistance, and conductivity). Recorded trends show that materials with lower thermal conductivity exhibit lower performance decay, and vice versa. The durability of the ETICS with different insulating materials (as the only variable in the different samples) was evaluated in order to quantify service life and then correctly plan maintenance interventions. Life-cycle assessment must take into account service life and durability for each material of the system. A higher durability of insulating materials allows for the execution of less maintenance interventions, with the loss of less performance over time. This study shows the physical and thermal behavior of the ETICS during its service life, comparing the differences induced by the most-used insulating materials. As a result of accelerated ageing cycles, the analyzed ETICS reveals a low grade of decay and measured performances show little degradation; for thermal conductivity, differences between the measured and the declared conductivities by technical datasheet were observed.

DEVELOPMENT OF A DISTRIBUTED INFORMATION AND COMPUTING CONTROL SYSTEM FOR THE NUCLEAR UNIT AT NOVOVORONEZH NPP

Ядерные блоки атомных электростанций имеют длительный срок эксплуатации, что приводит к ситуации, когда в процессе эксплуатации технические и программные средства систем управления перестают отвечать текущим современным требованиям в плане надежности и безопасности их использования. В результате для продления срока действия ядерного блока требуется обязательное проведение модернизации информационно-вычислительной системы (ИВС) управления. Приводятся результаты такой работы, проведенной на 4 блоке Нововоронежской АЭС. При выборе оборудования для создания новой ИВС модернизируемого энергоблока был реализован принцип унификации. Программное обеспечение всех компонентов программно-технического комплекса ИВС, включая функции систем предоставления параметров безопасности и внутриреакторного контроля, реализовано на единых программных средствах. Представленные значения параметров сигналов на всех рабочих станциях программно-технического комплекса информационной системы, интерфейсы взаимодействия, человеко-машинный интерфейс и навигация по видеокадрам идентичны, что учитывает требования по оптимальному взаимодействию системы «человек-машина». Система удовлетворяет требованиям по обеспечению надёжности на основе резервирования, независимости, разнообразия, с учётом отказов по общей причине. Для этого ИВС была реализована в виде двухканальной информационной системы. Основной и дублирующий каналы измерения и обработки данных в программно-техническом комплексе ИВС функционируют одновременно в полном объеме. Разработанная информационно-вычислительная система позволила продлить срок эксплуатации 4 энергоблока Нововоронежской АЭС на 15 лет Nuclear units of nuclear power plants have a long service life, which leads to a situation when, during the operation, the technical and software tools of control systems no longer meet the current modern requirements in terms of reliability and safety of their use. As a result, in order to extend the validity period of the nuclear unit, mandatory modernization of the information and computing system (ICS) of management is required. This article presents the results of such work carried out at Unit 4 of the Novovoronezh NPP. When choosing the equipment to create a new ICS of the upgraded power unit, we implemented the principle of unification. The software of all components of the ICS software and hardware complex, including the functions of systems for providing security parameters and in-reactor control, is implemented on unified software tools. The representation of signal parameter values at all workstations of the software and hardware complex of the information system, the interfaces of human-machine interface interaction and navigation through video frames are identical, which takes into account the requirements for optimal interaction of the man-machine system. The system meets the requirements for ensuring reliability based on redundancy, independence, diversity, taking into account failures for a common reason. For this purpose, we implemented the ICS in the form of a two-channel information system. The main and backup channels of measurement and data processing in the ICS software and hardware complex function simultaneously in full. The developed information and computing system made it possible to extend the service life of 4 power units of the Novovoronezh NPP for 15 years

Analysis and Recommendations for LED Catastrophic Failure Due to Voltage Stress

Light-emitting diode (LED) lighting has, compared to other types of lighting, a significantly lower energy consumption. However, the perceived service life is also important for customer satisfaction and here there is a discrepancy between customers’ experience and manufacturers’ statements. Many customers experience a significantly shorter service life than claimed by the manufacturers. An experiment was carried out in the Pehr Högström Laboratory at Luleå University of Technology in Skellefteå, Sweden to investigate whether voltage disturbances could explain this discrepancy. Over 1000 LED lamps were exposed to high levels of voltage disturbances for more than 6000 h; the failure rate from this experiment was similar to the one from previous experiments in which lamps were exposed to normal voltage. The discrepancy thus remains, even though some possible explanations have emerged from the project’s results. The lamps were exposed to five different types of voltage disturbances: short interruptions; transients; overvoltage; undervoltage; and harmonics. Only overvoltage resulted in failure of the lamps, and only for a single topology of lamp. A detailed analysis has been made of the topology of lamps that failed. This lamp type contains a different internal electronics circuit than the other lamp types. Failures of the lamps when exposed to overvoltage are due to the heat development in the control circuit increasing sharply when the lamps are exposed to a higher voltage. Hence, it is concluded that there are lamps that are significantly more sensitive to voltage disturbances than other lamp types. Manufactures need to consider the voltage quality that can be expected at the terminal of the lamp to prevent failure of lamps due to voltage disturbances. This paper therefore contains recommendations for manufacturers of lighting; the recommendations describe which voltage disturbances lamps should cope with.

Prediction and Analysis of PDC Bit Wear in Conglomerate Layer with Machine Learning and Finite-Element Method

Polycrystalline diamond compact (PDC) bits experience a serious wear problem in drilling tight gravel layers. To achieve efficient drilling and prolong the bit service life, a simplified model of a PDC bit with double cutting teeth was established by using finite-element numerical simulation technology, and the rock-breaking process of PDC bit cutting teeth was simulated using the Archard wear principle. The numerical simulation results of the wear loss of the PDC bit cutting teeth, such as the caster angle, temperature, linear velocity, and bit pressure, as well as previous experimental research results, were combined into a training dataset. Then, machine learning methods for equal-probability gene expression programming (EP-GEP) were used. Based on the accuracy of the training set, the effectiveness of this method in predicting the wear of PDC bits was demonstrated by verifying the dataset. Finally, a prediction dataset was established by a Latin hypercube experiment and finite-element numerical simulation. Through comparison with the EP-GEP prediction results, it was verified that the prediction accuracy of this method meets actual engineering needs. The results of the sensitivity analysis method for the gray correlation degree show that the degree of influence of bit wear is in the order of temperature, back dip angle of the PDC cutter, linear speed, and bit pressure. These results demonstrate that when an actual PDC bit is drilling hard strata such as a conglomerate layer, after the local high temperature is generated in the formation cut by the bit, appropriate cooling measures should be taken to increase the bit pressure and reduce the rotating speed appropriately. Doing so can effectively reduce the wear of the bit and prolong its service life. This study provides guidance for predicting the wear of a PDC bit when drilling in conglomerate, adjusting drilling parameters reasonably, and prolonging the service life of the bit.

Artificial Intelligence in the Protection and Inheritance of Cultural Landscape Heritage in Traditional Village

To continue to protect and inherit the cultural landscape heritage of traditional villages, starting from the perspective of artificial intelligence (AI), literature review methods are used, and related theories are collected. Then, Wuyuan County in Jiangxi Province in the traditional villages is taken as the research object. By analyzing the tourism income of this place from 2016 to 2020, the overall income of this county is relatively good. In fact, due to the weak protection of traditional villages in Wuyuan County, the lack of supervision awareness, the implementation of the “immigrant and relocation” policy, and the backward thinking of residents, the cultural landscape of traditional villages has collapsed and destroyed. Up to now, there are 113 ancient ancestral temples, 28 ancient mansion houses, 36 ancient private houses, 187 ancient bridges, and only 12 ancient villages. Finally, AI technology is applied to the cultural landscape of traditional villages. Through image restoration technology, traditional villages can be restored to a certain extent. Intelligent positioning and radio frequency (RF) technology can also realize real-time monitoring of traditional villages from the perspective of weather and service life to achieve the purpose of protecting cultural landscape heritage. Therefore, AI technology is applied in the protection and inheritance of traditional village cultural landscape heritage, which has great reference significance for the management of various historical and cultural heritage.

EXAMINATION OF THE QUALITY OF NANOMATERIALS IN THE DEVELOPMENT AND APPLICATION OF CIRCULATING RESOURCES IN CONSTRUCTION

the advantage of the equality indicator is the relative simplicity of definition and the possibility of periodic moni-toring. According to the equality indicator, it is possible to assign repairs and predict the service life, assess the condition of the road surface. Experimental studies have proved that there is a connection between the evenness of the coating and the strength of the pavement, which opens up the possibility of determining the structural strength of non-rigid pavement, which provides a given evenness of the coating for the last year of operation be-fore major repairs. The question of assessing the impact of the unevenness of the road surface on the processes of development and accumulation of deformations, changes in the evenness of the coating during operation remain largely open. This is due to the multifactorial nature of the problem of predicting the equality of coverage, so it is advisable to use approaches based on direct measurement methods. Most of the existing models of interaction of a pneumatic or rigid wheel with a coating are designed for problems of pavement mechanics or car theory, therefore they cannot be unambiguously applied to determine the value of the dynamism coefficient. A significant disad-vantage of these solutions is insufficient consideration of the deformative properties (modulus of elasticity) of the pavement.